JP7183952B2 - Power converters, power supply systems, and control systems for power converters - Google Patents

Description

The present invention relates to a power converter that converts DC power into AC power, a power supply system, and a control system for the power converter.

Single-phase three-wire, often with two voltage lines carrying two alternating voltages out of phase with each other, and one neutral carrying a neutral voltage, for example for powering electronic appliances in the home A power converter of the type is utilized. For example, Patent Literatures 1 to 3 disclose single-phase three-wire power converters.

JP 2015-231259 A JP 2015-2657 A JP 2015-27197 A

Chienru Lung, Hiroaki Kakigano, Yushi Miura, Toshifumi Ise“Implementation of Sigma-Delta Modulation Controller for Single-Phase Three-Wire Inverter in Stand-Alone Operation Applied for Hybrid Generation System for Residential Houses.”, PEDS2013, pp.680-685 .

In a power conversion device, for example, when a load is overloaded, it is desired that power supply to that load be stopped, and it is expected that power supply and power supply stop can be appropriately performed. It is

It is desirable to provide a power conversion device, a power supply system, and a control system for the power conversion device that can appropriately supply and stop power supply.

The power conversion device of the present invention includes a first switching element pair, a second switching element pair, a third switching element pair, a first output terminal, a second output terminal, and a third output. A terminal, a low-pass filter, and a control section are provided. The first switching element pair includes a first switching element provided on the path between the first voltage line and the first node and a switching element provided on the path between the second voltage line and the first node. and a second switching element provided. The second switching element pair includes a third switching element provided on a path between the first voltage line and the second node, and a third switching element provided on a path between the second voltage line and the second node. and a fourth switching element provided. The third switching element pair includes a fifth switching element provided on the path between the first voltage line and the third node, and a fifth switching element provided on the path between the second voltage line and the third node. and a sixth switching element provided. The low pass filter has a first path between the first node and the first output terminal, a second path between the second node and the second output terminal, and a third node and the third output terminal. from the first node, the second node, and the third node toward the first output terminal, the second output terminal, and the third output terminal in a third path between the output terminals of It has a first circuit and a second circuit arranged in this order. The first circuit includes a reactor provided in each of two or more paths including the third path among the first path, the second path, and the third path. The second circuit includes a first capacitive element provided between the first path and the third path, and a second capacitive element provided between the second path and the third path. and The controller can control switching operations of the first switching element pair, the second switching element pair, and the third switching element pair. The control unit can generate a first voltage command value that is a command value of a first voltage that is a differential voltage between the output voltage of the low-pass filter in the first path and the output voltage of the low-pass filter in the third path. and is capable of generating a second voltage command value that is a command value of a second voltage that is a differential voltage between the output voltage of the low-pass filter in the second path and the output voltage of the low-pass filter in the third path; A first current command value, which is a command value of a first current flowing through a first path, is generated based on a voltage command value of 1, a first voltage, and a first load current flowing through a first output terminal. A second current command value that can be generated and is a second current command value that flows through a second path based on a second voltage command value, a second voltage, and a second load current that flows through a second output terminal. Two current command values can be generated, and the switching operation can be controlled based on the first current command value and the second current command value.

A power supply system of the present invention includes the above-described power converter and a DC power supply. A DC power supply is connected to the first voltage line and the second voltage line of the power converter. The power converter can generate AC power based on DC power supplied from a DC power supply.

A control system for a power converter according to the present invention includes the above-described power converter and a DC power supply. A DC power supply is connected to the first voltage line and the second voltage line of the power converter. The power converter has a first input terminal connected to the first path and a second input terminal connected to the second path. The power conversion device has a first operation capable of generating AC power based on DC power supplied from a DC power supply, and a power supply connected to a first input terminal and a second input terminal. Based on the AC power, it is possible to selectively perform a second operation capable of generating DC power to be supplied to the DC power supply.

According to the power conversion device, the power supply system, and the control system of the power conversion device of the present invention, the first and a second voltage command value that is the differential voltage between the output voltage of the low-pass filter in the second path and the output voltage of the low-pass filter in the third path and based on the first voltage command value, the first voltage, and the first load current flowing through the first output terminal, the first voltage command value flowing through the first path is generated. A first current command value, which is a current command value, is generated, and based on the second voltage command value, the second voltage, and the second load current flowing through the second output terminal, the second path is generated. Since the second current command value, which is the command value for the second current to flow, is generated and the switching operation is controlled based on the first current command value and the second current command value, power supply and power It is possible to appropriately stop the supply.

BRIEF DESCRIPTION OF THE DRAWINGS It is a circuit diagram showing one structural example of the power converter device which concerns on one embodiment of this invention. 2 is a block diagram showing a configuration example of a control unit shown in FIG. 1; FIG. 2 is a table showing an operation example in unipolar PWM operation of the power converter shown in FIG. 1; 3 is an explanatory diagram showing an operation example of a control unit shown in FIG. 2; FIG. 3 is an explanatory diagram showing another operation example of the control unit shown in FIG. 2; FIG. 3 is an explanatory diagram showing another operation example of the control unit shown in FIG. 2; FIG. 3 is an explanatory diagram showing another operation example of the control unit shown in FIG. 2; FIG. FIG. 2 is a waveform diagram showing an operation example of the power converter shown in FIG. 1; 2 is a table showing an operation example in bipolar PWM operation of the power converter shown in FIG. 1; 2 is a state transition diagram showing an operation example of the power converter shown in FIG. 1; FIG. 3 is an explanatory diagram showing an operation example of a duty ratio generator shown in FIG. 2; FIG. 3 is an explanatory diagram showing another operation example of the duty ratio generator shown in FIG. 2; FIG. It is a table showing simulation conditions. FIG. 2 is a timing waveform diagram showing an operation example of the power converter shown in FIG. 1; 3 is a timing waveform diagram showing another operation example of the power converter shown in FIG. 1. FIG. FIG. 11 is a block diagram showing a configuration example of a duty ratio generator according to a modification; FIG. 11 is a block diagram showing a configuration example of a duty ratio generator according to another modification; It is a circuit diagram showing one structural example of the power converter device which concerns on another modification. It is a circuit diagram showing one structural example of the power converter device which concerns on another modification.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Configuration example]
FIG. 1 shows a configuration example of a power conversion device (power conversion device 1) according to an embodiment of the present invention. This power converter 1 is a self-sustaining DC/AC inverter capable of selectively performing single-phase three-wire output operation and single-phase two-wire output operation. The power conversion device 1 includes input terminals T11, T12 and output terminals T21, T22, T23. A DC power supply PDC is connected to the input terminals T11 and T12. The DC power supply PDC may be, for example, a DC power supply. In addition, the DC power supply PDC has, for example, a solar cell and a DC/DC converter. may be supplied. Further, the DC power supply PDC may have, for example, a battery and a DC/DC converter, convert the DC power supplied from the battery, and supply the converted DC power to the power converter 1 . The output terminals T21, T22, T23 are connected to the load device LOAD.

The power converter 1 includes a voltage detection unit 21, a capacitive element 22, switching elements SW1 to SW6, current detection units 23U and 23W, a low-pass filter 29, voltage detection units 26U and 26W, switches 27U and 27W, 27O and a control unit 30 .

The voltage detector 21 is configured to detect the DC bus voltage Vdc. One end of the voltage detector 21 is connected to the voltage line L1 led to the input terminal T11, and the other end is connected to the reference voltage line L2 led to the input terminal T12. The voltage detection unit 21 detects the voltage on the voltage line L1 with reference to the voltage on the reference voltage line L2 as the DC bus voltage Vdc. The voltage detector 21 then supplies information about the detected DC bus voltage Vdc to the controller 30 .

One end of the capacitive element 22 is connected to the voltage line L1, and the other end is connected to the reference voltage line L2. The capacitive element 22 is configured using, for example, an electrolytic capacitor. The capacitive element 22 has a capacitance (capacitance value) Cdc.

The switching elements SW1 to SW6 are configured to perform switching operations based on the gate signals S1 to S6, respectively. The switching elements SW1 to SW6 are configured using, for example, insulated gate bipolar transistors (IGBTs). Each of the switching elements SW1 to SW6 has a free wheel diode. The freewheeling diode of the switching element SW1 has an anode connected to the emitter of the switching element SW1 and a cathode connected to the collector of the switching element SW1. The same applies to the switching elements SW2 to SW6.

Switching element SW1 is provided on a path between voltage line L1 and node N1, and is configured to connect voltage line L1 to node N1 when turned on. The switching element SW1 has a collector connected to a voltage line L1, a gate supplied with a gate signal S1, and an emitter connected to a node N1. The switching element SW2 is provided on a path between the reference voltage line L2 and the node N1, and is configured to connect the reference voltage line L2 to the node N1 when turned on. The switching element SW2 has a collector connected to the node N1, a gate supplied with a gate signal S2, and an emitter connected to the reference voltage line L2. A node N1 is a connection point between the emitter of the switching element SW1 and the collector of the switching element SW2.

Switching element SW3 is provided on a path between voltage line L1 and node N2, and is configured to connect voltage line L1 to node N2 when turned on. The switching element SW3 has a collector connected to the voltage line L1, a gate supplied with a gate signal S3, and an emitter connected to the node N2. Switching element SW4 is provided on a path between reference voltage line L2 and node N2, and is configured to connect reference voltage line L2 to node N2 when turned on. Switching element SW4 has a collector connected to node N2, a gate supplied with gate signal S4, and an emitter connected to reference voltage line L2. A node N2 is a connection point between the emitter of the switching element SW3 and the collector of the switching element SW4.

Switching element SW5 is provided on a path between voltage line L1 and node N3, and is configured to connect voltage line L1 to node N3 when turned on. The switching element SW5 has a collector connected to the voltage line L1, a gate supplied with the gate signal S5, and an emitter connected to the node N3. Switching element SW6 is provided on a path between reference voltage line L2 and node N3, and is configured to connect reference voltage line L2 to node N3 when turned on. The switching element SW6 has a collector connected to the node N3, a gate supplied with the gate signal S6, and an emitter connected to the reference voltage line L2. A node N3 is a connection point between the emitter of the switching element SW5 and the collector of the switching element SW6.

The current detection unit 23U is provided on a path from the node N1 to the output terminal T21 and configured to detect the current i_u flowing from the node N1 toward the low-pass filter 29. FIG. Current detection unit 23 U has one end connected to node N 1 and the other end connected to low-pass filter 29 . The current detection unit 23U supplies the control unit 30 with information about the detected current i_u.

The current detection unit 23W is provided on a path from the node N2 to the output terminal T22, and configured to detect the current i_w flowing from the node N2 toward the low-pass filter 29. FIG. One end of the current detector 23W is connected to the node N2, and the other end is connected to the low-pass filter 29. FIG. The current detection section 23W supplies information about the detected current i_w to the control section 30 .

Low-pass filter 29 is provided in the path from node N1 to output terminal T21, the path from node N2 to output terminal T22, and the path from node N3 to output terminal T23, and the voltage at node N1 and the voltage at node N3 are equal to each other. It is configured to remove high frequency components contained in the difference and to remove high frequency components contained in the voltage difference between the voltage at the node N2 and the voltage at the node N3. The low-pass filter 29 has AC reactors 24U, 24W, 24O and capacitive elements 25U, 25W.

One end of AC reactor 24U is connected to the other end of current detector 23U, and the other end is connected to U-phase voltage line UL. The AC reactor 24U has an inductance Lu and an internal resistance value Ru. One end of the AC reactor 24W is connected to the other end of the current detector 23W, and the other end is connected to the W-phase voltage line WL. AC reactor 24W has inductance Lw and internal resistance value Rw. AC reactor 24O has one end connected to node N3 and the other end connected to neutral line OL. The AC reactor 24O has an inductance Lo and an internal resistance value Ro.

The inductances Lu, Lw, Lo may be equal to each other, or one or more of the inductances Lu, Lw, Lo may be different. Similarly, the internal resistance values Ru, Rw and Ro may be equal to each other, or one or more of the internal resistance values Ru, Rw and Ro may be different. Also, in this example, the three AC reactors 24U, 24W, 24O are provided, but the present invention is not limited to this, and for example, one of the AC reactors 24U, 24W may be omitted.

Capacitive element 25U has one end connected to U-phase voltage line UL and the other end connected to neutral line OL. The capacitive element 25U has a capacitance (capacitance value) Cu and an internal resistance value Rcu. One end of the capacitive element 25W is connected to the W-phase voltage line WL, and the other end is connected to the neutral line OL. The capacitive element 25W has a capacitance (capacitance value) Cw and an internal resistance value Rcw. The capacitive elements 25U and 25W are configured using AC film capacitors, for example. Capacitive elements 25U and 25W may be, for example, so-called X capacitors of an EMI (Electro Magnetic Interference) filter circuit.

With this configuration, the low-pass filter 29 outputs a U-phase AC voltage having, for example, a sine wave shape to the U-phase voltage line UL, and outputs a W-phase AC voltage having, for example, a sine wave shape to the W-phase voltage line WL. It is designed to

The voltage detection unit 26U is configured to detect a voltage e_uo associated with the U-phase AC voltage output from the low-pass filter 29 . Voltage detection unit 26U has one end connected to U-phase voltage line UL and the other end connected to neutral line OL. Voltage detection unit 26U detects the voltage on U-phase voltage line UL with reference to the voltage on neutral line OL as voltage e_uo. The voltage detection unit 26U supplies the control unit 30 with information about the detected voltage e_uo.

The voltage detection unit 26 W is configured to detect a voltage e_wo associated with the W-phase AC voltage output from the low-pass filter 29 . Voltage detector 26W has one end connected to W-phase voltage line WL and the other end connected to neutral line OL. The voltage detection unit 26W detects the voltage on the W-phase voltage line WL with reference to the voltage on the neutral line OL as the voltage e_wo. The voltage detection unit 26W supplies information about the detected voltage e_wo to the control unit 30 .

Switch 27U is configured to connect U-phase voltage line UL to load device LOAD when turned on. The switch 27U is configured using, for example, a relay. One end of the switch 27U is connected to the U-phase voltage line UL, and the other end is connected to the output terminal T21. The switch 27U is turned on and off based on the switch control signal Sstdu.

The switch 27W is configured to connect the W-phase voltage line WL to the load device LOAD when turned on. The switch 27W is configured using, for example, a relay. One end of the switch 27W is connected to the W-phase voltage line WL, and the other end is connected to the output terminal T22. The switch 27W is turned on and off based on the switch control signal Sstdw.

The switch 27O is configured to connect the neutral line OL to the load device LOAD by turning on. The switch 27O is configured using, for example, a relay. One end of the switch 27O is connected to the neutral line OL, and the other end is connected to the output terminal T23. The switch 27O is turned on and off based on the switch control signal Sstdo.

The output terminals T21, T22, T23 are connected to the load device LOAD. The load device LOAD includes a load Z1 having one end connected to the output terminal T21 and the other end connected to the output terminal T23, a load Z2 having one end connected to the output terminal T22 and the other end connected to the output terminal T23, is connected to the output terminal T21 and the other end thereof is connected to the output terminal T22.

The control unit 30 is configured to control the operation of the power converter 1 . The control unit 30 is configured using, for example, one or more microcontrollers.

The control unit 30 receives information about the DC bus voltage Vdc supplied from the voltage detection unit 21, information about the currents i_u and i_w supplied from the current detection units 23U and 23W, and information about the currents i_u and i_w supplied from the voltage detection units 26U and 26W. Gate signals S1 to S6 to be supplied to switching elements SW1 to SW6 are generated based on information about voltages e_uo and e_wo. The control unit 30 has an AD conversion circuit that samples at the sampling frequency fs. Then, the control unit 30 performs AD conversion based on information about the DC bus voltage Vdc supplied from the voltage detection unit 21, for example, every period Ts (for example, 50 μsec. (=1/20 kHz)). A digital value indicating the DC bus voltage Vdc is obtained, and control is performed based on this digital value. The same applies to currents i_u, i_w and voltages e_uo, e_wo. Hereinafter, the DC bus voltage Vdc, the currents i_u and i_w, and the voltages e_uo and e_wo are appropriately used to represent AD-converted digital values. The switching elements SW1 to SW6 are turned on and off based on the gate signals S1 to S6 generated by the control section 30. FIG.

The control unit 30 has a plurality of control modes M including a single-phase three-wire output mode and a single-phase two-wire output mode, as will be described later. For example, when the control mode M is the single-phase three-wire output mode, for example, when an overcurrent occurs in the current supplied to the load device LOAD or an overvoltage occurs in the voltage supplied to the load device LOAD, The control unit 30 changes the control mode M from the single-phase three-wire output mode to the single-phase two-wire output mode. The control unit 30 returns the control mode M to the single-phase three-wire output mode when such overcurrent and overvoltage are eliminated. Further, the control unit 30 can selectively set the control mode M to the single-phase two-wire output mode or the single-phase three-wire output mode based on the control signal CTL supplied from the outside. .

For example, when the control mode M is the single-phase three-wire output mode, the control unit 30 controls the voltage amplitude of the voltage e_uw between U and W by controlling the operations of the switching elements SW1 to SW4. , the voltage at the neutral point (neutral line OL) is controlled so as to keep the voltage balance between the voltage e_uo and the voltage e_wo by controlling the operations of the switching elements SW5 and SW6. The control of the voltage e_uw using the switching elements SW1 to SW4 is hereinafter also referred to as differential mode (DM) control. Control of the neutral point voltage using the switching elements SW5 and SW6 is hereinafter also referred to as common mode (CM) control.

Next, equations representing operations in the power conversion device 1 will be described below.

Equation EQ1 provides definitions for DM voltage e_dm, DM current i_dm, DM voltage v_dm, DM inductance Ldm, and DM resistance Rdm for use in differential mode control. The first formula indicates that the DM voltage e_dm is the difference between the voltage e_uo detected by the voltage detection unit 26U and the voltage e_wo detected by the voltage detection unit 26W. The difference between this voltage e_uo and voltage e_wo is the voltage e_uw across UW. The second formula indicates that the DM current i_dm is the difference between the current i_u detected by the current detector 23U and the current i_w detected by the current detector 23W. The third equation indicates that the DM voltage v_dm is the difference between the voltage v_u at node N1 and the voltage v_w at node N2. The fourth equation indicates that the DM inductance Ldm is the difference between the inductance Lu of the AC reactor 24U and the inductance Lw of the AC reactor 24W. The fifth formula indicates that the DM resistance value Rdm is the difference between the internal resistance value Ru of the AC reactor 24U and the internal resistance value Rw of the AC reactor 24W.

Equation EQ2 defines CM voltage e_cm, CM current i_cm, CM voltage v_cm, CM inductance Lcm, and CM resistance Rcm used in common mode control. The first formula indicates that the CM voltage e_cm is the sum of the voltage e_uo detected by the voltage detection unit 26U and the voltage e_wo detected by the voltage detection unit 26W. The second expression indicates that the CM current i_cm is the sum of the current i_u detected by the current detector 23U and the current i_w detected by the current detector 23W. This second equation also indicates that this CM current i_cm is the current i_o that flows from the AC reactor 24O toward the node N3. The third equation indicates that CM voltage v_cm is the sum of voltage v_u at node N1 and voltage v_w at node N2. This third equation also indicates that this CM voltage V_cm is the voltage v_o at node N3. The fourth equation indicates that the CM inductance Lcm is the inductance Lo of the AC reactor 24O. The fifth formula indicates that the CM resistance value Rcm is the internal resistance value Ro of the AC reactor 24O.

The first expression of the expression EQ3 indicates that the voltage v_u at the node N1 is the product of the duty ratio d_u of the switching elements SW1 and SW2 and the DC bus voltage Vdc, and the second expression indicates that the voltage v_o at the node N3 is the switching The third equation shows that the voltage v_w at the node N2 is the product of the duty ratio d_o of the switching elements SW3 and SW4 and the DC bus voltage Vdc. indicates that there is

式ＥＱ４の第１式は、ＤＭ電圧ｖ_dmが、ＤＭインダクタンスＬdmおよびＤＭ電流ｉ_dmの微分の積と、ＤＭ抵抗値ＲdmおよびＤＭ電流ｉ_dmの積と、ＤＭ電圧ｅ_dmとの和であることを示す。第２式は、ＤＭ電圧ｖ_dmが、ＤＭデューティ比ｄ_dmおよび直流バス電圧Ｖdcの積であることを示す。第３式は、ＣＭ電圧ｖ_cmが、ＣＭ電圧ｅ_cmから、ＣＭインダクタンスＬcmおよびＣＭ電流ｉ_cmの微分の積と、ＣＭ抵抗値ＲcmおよびＣＭ電流ｉ_cmの積とを減算したものであることを示す。第４式は、ＣＭ電圧ｖ_cmが、ＣＭデューティ比ｄ_cmおよび直流バス電圧Ｖdcの積であることを示す。第５式は、電流ｉ_uが、容量素子２５ＵのキャパシタンスＣuおよび電圧ｅ_uoの微分の積と、出力端子Ｔ２１に流れる負荷電流ｉ_lduとの和であることを示す。第６式は、電流ｉ_wが、容量素子２５ＷのキャパシタンスＣwおよび電圧ｅ_woの微分の積と、出力端子Ｔ２２に流れる負荷電流ｉ_ldwとの和であることを示す。 Using these equations EQ1-EQ3, Kirchhoff's voltage law, and Kirchhoff's current law, the following equation EQ4 is obtained.

The first of equation EQ4 indicates that the DM voltage v_dm is the sum of the product of the differentiation of the DM inductance Ldm and the DM current i_dm, the product of the DM resistance Rdm and the DM current i_dm, and the DM voltage e_dm. A second equation indicates that the DM voltage v_dm is the product of the DM duty ratio d_dm and the DC bus voltage Vdc. The third equation indicates that the CM voltage v_cm is the CM voltage e_cm minus the product of the differentiation of the CM inductance Lcm and the CM current i_cm and the product of the CM resistance Rcm and the CM current i_cm. The fourth equation indicates that CM voltage v_cm is the product of CM duty ratio d_cm and DC bus voltage Vdc. The fifth equation indicates that the current i_u is the sum of the product of the capacitance Cu of the capacitive element 25U and the differentiation of the voltage e_uo and the load current i_ldu flowing through the output terminal T21. The sixth equation indicates that the current i_w is the sum of the product of the capacitance Cw of the capacitive element 25W and the differentiation of the voltage e_wo, and the load current i_ldw flowing through the output terminal T22.

式ＥＱ５の第１式は、負荷電流ｉ_lduが、電流ｉ_uと、Ｕ相電圧線ＵＬから容量素子２５Ｕに向かって流れる電流ｉ_cuとの差であることを示す。第２式は、負荷電流ｉ_ldwが、電流ｉ_wと、Ｗ相電圧線ＷＬから容量素子２５Ｗに向かって流れる電流ｉ_cwとの差であることを示す。第３式および第４式は、電流ｉ_cu，ｉ_cwが、サイン波形状を有する波形を用いて推定されることを示す式である。Ｅuormsは、電圧ｅ_uoの実効値であり、Ｅwormsは、電圧ｅ_woの実効値であり、ｆsdは自立運転周波数ｆsd（例えば６０Ｈｚ）であり、θsdは、位相角度である。この位相角度θsdは、時間ｔの関数であり、自立運転周波数ｆsd（例えば６０Ｈｚ）に応じて変化するものである。 In this example, load currents i_ldu and i_ldw are estimated using the following equations EQ5 and EQ6.

The first equation of equation EQ5 indicates that load current i_ldu is the difference between current i_u and current i_cu flowing from U-phase voltage line UL toward capacitive element 25U. The second expression indicates that the load current i_ldw is the difference between the current i_w and the current i_cw flowing from the W-phase voltage line WL toward the capacitive element 25W. Equations 3 and 4 are equations showing that currents i_cu and i_cw are estimated using waveforms having sine wave shapes. Euorms is the effective value of the voltage e_uo, Eworms is the effective value of the voltage e_wo, fsd is the self-sustaining frequency fsd (eg 60 Hz), and θsd is the phase angle. This phase angle θsd is a function of time t, and varies according to the self-sustaining operation frequency fsd (eg, 60 Hz).

The first and second expressions of the expression EQ6 are expressions for calculating the effective values Euorms and Eworms. The seventh formula indicates that the period Tsd of the voltages e_uo and e_wo is the reciprocal of the self-sustaining operation frequency fsd. In this example, the effective values Euorms and Eworms are calculated in units of half the period Tsd of the voltages e_uo and e_wo. This improves the responsiveness of the process of calculating the current i_cu based on the voltage e_uo and the process of calculating the current i_cw based on the voltage e_wo.

Next, a specific configuration of the control section 30 will be described.

FIG. 2 shows a configuration example of the control unit 30. As shown in FIG. The control unit 30 has a duty ratio generation unit 40 , a drive unit 60 and a power supply control unit 31 .

The duty ratio generator 40 generates the DC bus voltage Vdc detected by the voltage detector 21, the currents i_u and i_w detected by the current detectors 23U and 23W, the e_uo and e_wo detected by the voltage detectors 26U and 26W, the power It is configured to generate a DM duty ratio command value d_dm* and a CM duty ratio command value d_cm* based on the control signals Sgbu and Sgbw supplied from the supply control unit 31 . Duty ratio generation unit 40 includes voltage command value generation unit 41, current estimation unit 42, subtraction units 43 and 44, U-phase voltage control unit 45, W-phase voltage control unit 46, subtraction unit 47, addition It has a section 48 , subtraction sections 51 and 52 , addition sections 53 and 54 , a DM current control section 55 and a CM current control section 56 . Equations EQ7 and EQ8 used in the arithmetic processing of this duty ratio generator 40 are shown below.

Equation EQ7 indicates DM duty ratio command value d_dm*, CM duty ratio command value d_cm*, current command values i_u*, i_w*, and voltage command values e_uo*, e_wo*. The DM duty ratio command value d_dm* is the command value for the DM duty ratio d_dm, and the CM duty ratio command value d_cm* is the command value for the CM duty ratio d_cm. A current command value i_u* is a command value of the current i_u, and a current command value i_w* is a command value of the current i_w. The voltage command value e_uo* is the command value of the voltage e_uo, and the voltage command value e_wo* is the command value of the voltage e_wo. The first equation of equation EQ7 is obtained based on the first and second equations of equation EQ4. The second equation of equation EQ7 is obtained based on the third and fourth equations of equation EQ4. The third equation of equation EQ7 is obtained based on the fifth equation of equation EQ4, and the fourth equation of equation EQ7 is obtained based on the sixth equation of equation EQ4.

Based on the control signals Sgbu and Sgbw supplied from the power supply control unit 31, the voltage command value generation unit 41 calculates the voltage command values e_uo* and e_wo* by using the fifth and sixth equations of the equation EQ7. configured to generate Emax is the voltage amplitude of voltages e_uo and e_wo. The control signals Sgbu and Sgbw are signals that can take "1" or "0" as will be described later. The voltage command value e_uo* is an AC command value when the control signal Sgbu is "1", and is "0" when the control signal Sgbu is "0". Similarly, the voltage command value e_wo* is an AC command value when the control signal Sgbw is "1", and is "0" when the control signal Sgbw is "0".

Based on the voltages e_uo and e_wo, the current estimator 42 estimates the current i_cu flowing through the capacitive element 25U by using the third formula of the formula EQ5, and estimates the current i_cu flowing through the capacitive element 25U by using the fourth formula of the formula EQ5. It is configured to estimate the current i_cw flowing at 25W. In the third expression of the expression EQ5, the effective value Euorms can be obtained based on the voltage e_uo using the first expression of the expression EQ6, for example. Similarly, in the fourth equation of equation EQ5, the effective value Eworms can be obtained based on the voltage e_wo using, for example, the second equation of equation EQ6.

The subtraction unit 43 is configured to calculate the load current i_ldu by subtracting the current i_cu from the current i_u based on the current i_u and the current i_cu, as shown in the first equation of the equation EQ5.

The subtraction unit 44 is configured to calculate the load current i_ldw by subtracting the current i_cw from the current i_w based on the current i_w and the current i_cw, as shown in the second equation of the equation EQ5.

The U-phase voltage control unit 45 is configured to generate the current command value i_u* based on the voltage command value e_uo*, the voltage e_uo, and the load current i_ldu by using the third equation of the equation EQ7. Differentiation of the voltage e_uo in the third equation can be obtained, for example, by dividing the difference between the voltage command value e_uo* and the voltage e_uo by the cycle Ts, as shown in the first equation of the equation EQ8. The control unit 30 performs loop control using the U-phase voltage control unit 45 so that the voltage e_uo is approximately equal to the voltage command value e_uo*.

The W-phase voltage control unit 46 is configured to generate the current command value i_w* based on the voltage command value e_wo*, the voltage e_wo, and the load current i_ldw by using the fourth equation of the equation EQ7. Differentiation of the voltage e_wo in the fourth equation can be obtained, for example, by dividing the difference between the voltage command value e_wo* and the voltage e_wo by the period Ts, as shown in the second equation of the equation EQ8. The control unit 30 performs loop control using the W-phase voltage control unit 46 so that the voltage e_wo is approximately equal to the voltage command value e_wo*.

Based on the current command values i_u* and i_w*, the subtraction unit 47 calculates the difference between the current command values i_u* and i_w* in the same manner as in the second equation of the equation EQ1, thereby obtaining the DM current command value It is configured to generate i_dm*.

Based on the current command values i_u* and i_w*, the adder 48 calculates the sum of the current command value i_u* and the current command value i_w* in the same manner as in the second equation of the equation EQ2, thereby obtaining the CM current command value It is configured to generate i_cm*.

The subtractor 51 is configured to generate the DM voltage e_dm based on the voltages e_uo and e_wo by using the first equation of the equation EQ1. Subtractor 52 is configured to generate DM current i_dm based on currents i_u and i_w by using the second equation of equation EQ1.

The adder 53 is configured to generate the CM voltage e_cm based on the voltages e_uo and e_wo by using the first equation of the equation EQ2. Adder 54 is configured to generate CM current i_cm based on currents i_u and i_w by using the second equation of equation EQ2.

Based on the DM current command value i_dm*, the DM current i_dm, the DM voltage e_dm, and the DC bus voltage Vdc, the DM current control unit 55 calculates the DM duty ratio command value d_dm* by using the first equation of the equation EQ7. configured to generate The differentiation of the DM current i_dm in the first equation can be obtained by dividing the difference between the DM current command value i_dm* and the DM current i_dm by the period Ts, as shown in the third equation of EQ8. The controller 30 performs loop control using the DM current controller 55 so that the DM current i_dm is approximately equal to the DM current command value i_dm*.

CM current control unit 56 calculates CM duty ratio command value d_cm* based on CM current command value i_cm*, CM current i_cm, CM voltage e_cm, and DC bus voltage Vdc using the second equation of equation EQ7. configured to generate The differentiation of the CM current i_cm in the second equation can be obtained by dividing the difference between the CM current command value i_cm* and the CM current i_cm by the cycle Ts, as shown in the fourth equation of EQ8. The control unit 30 performs loop control using the CM current control unit 56 so that the CM current i_cm is approximately equal to the CM current command value i_cm*.

The drive unit 60 generates gate signals S1 to S6 based on the DM duty ratio command value d_dm* and the CM duty ratio command value d_cm*, drives the switching elements SW1 and SW2 using the gate signals S1 and S2, respectively, The gate signals S3 and S4 are used to drive the switching elements SW3 and SW4, respectively, and the gate signals S5 and S6 are used to drive the switching elements SW5 and SW6, respectively. The drive section 60 has a multiplication section 61, a switch SW0, multiplication sections 62U, 62W and 62O, and gate signal generation sections 63U, 63W and 63O.

The multiplier 61 is configured to multiply the DM duty ratio command value d_dm* and the control signal PWMSW. The control signal PWMSW is set to "-1" when the power conversion device 1 performs a unipolar PWM (Pulse Width Modulation) operation, and is set to "1" when the power conversion device 1 performs a bipolar PWM operation. It has become.

The switch SW0 is configured to select one of the three terminals T0, T1, and T2 based on the control signal SEL, and supply the duty ratio command value supplied to the selected terminal to the multiplier 62O. be done.

The multiplier 62U is configured to generate the duty ratio command value d_u* by multiplying the DM duty ratio command value d_dm* and the control signal Sgbu. The control signal Sgbu is a signal that can take "1" or "0", as will be described later. The duty ratio command value d_u* is the DM duty ratio command value d_dm* when the control signal Sgbu is "1", and is "0" when the control signal Sgbu is "0".

Gate signal generator 63U is configured to generate gate signals S1 and S2 using PWM based on duty ratio command value d_u*. The gate signal generator 63U also has a function of stopping generation of the gate signals S1 and S2 based on the control signal Sgbu. Specifically, when the control signal Sgbu is "1", the gate signal generation unit 63U generates the gate signals S1 and S2 based on the duty ratio command value d_u*, and the control signal Sgbu is "0". , the gate signals S1 and S2 are set to a low level. The switching elements SW1 and SW2 shown in FIG. 1 are turned off based on the low level gate signals S1 and S2. Thus, the control signal Sgbu functions as a so-called gate block signal for the switching elements SW1 and SW2.

The multiplier 62W is configured to multiply the output value of the multiplier 61 and the control signal Sgbw to generate the duty ratio command value d_w*. The control signal Sgbw is a signal that can take "1" or "0", as will be described later. The duty ratio command value d_w* is the output value of the multiplier 61 when the control signal Sgbw is "1", and is "0" when the control signal Sgbw is "0".

The gate signal generator 63W is configured to generate the gate signals S3 and S4 using PWM based on the duty ratio command value d_w*. The gate signal generator 63W also has a function of stopping generation of the gate signals S3 and S4 based on the control signal Sgbw. Specifically, when the control signal Sgbw is "1", the gate signal generator 63W generates the gate signals S3 and S4 based on the duty ratio command value d_w*, and the control signal Sgbw is "0". , the gate signals S3 and S4 are set to low level. The switching elements SW3 and SW4 shown in FIG. 1 are turned off based on the low level gate signals S3 and S4. Thus, the control signal Sgbw functions as a so-called gate block signal for the switching elements SW3 and SW4.

The multiplier 62O is configured to generate a duty ratio command value d_o* by multiplying the output value of the switch SW0 and the control signal Sgbo. The control signal Sgbo is a signal that can take "1" or "0", as will be described later. The duty ratio command value d_o* is the output value of the switch SW0 when the control signal Sgbo is "1", and is "0" when the control signal Sgbo is "0".

The gate signal generator 63O is configured to generate the gate signals S5 and S6 using PWM based on the duty ratio command value d_o*. The gate signal generator 63O also has a function of stopping generation of the gate signals S5 and S6 based on the control signal Sgbo. Specifically, when the control signal Sgbo is "1", the gate signal generator 63O generates the gate signals S5 and S6 based on the duty ratio command value d_o*, and the control signal Sgbo is "0". , the gate signals S5 and S6 are set to a low level. The switching elements SW5 and SW6 shown in FIG. 1 are turned off based on the low level gate signals S5 and S6. Thus, the control signal Sgbo functions as a so-called gate block signal for the switching elements SW5 and SW6.

Power supply control unit 31 generates control signals Sgbu, Sgbw, Sgbo, control signals PWMSEL, SEL, and switch control signals Sstdu, Sstdw, Sstdo based on voltages e_uo, e_wo, currents i_u, i_w, and control signal CTL. By doing so, the operation of supplying power to the load device LOAD of the power conversion device 1 is configured to be controlled.

スイッチＳＷ０では、制御信号ＳＥＬが“０”を示すである場合には端子Ｔ０が選択され、制御信号ＳＥＬが“１”である場合には端子Ｔ１が選択され、制御信号ＳＥＬが“２”である場合には端子Ｔ２が選択されるようになっている。 The power supply control unit 31 generates the control signal SEL based on the control signals Sgbu, Sgbw, and Sgbo using the following equation EQ9.

In the switch SW0, the terminal T0 is selected when the control signal SEL indicates "0", the terminal T1 is selected when the control signal SEL indicates "1", and the terminal T1 is selected when the control signal SEL indicates "2". In some cases, terminal T2 is selected.

The control unit 30 has four control modes (output stop mode MA, single-phase three-wire output mode MB, single-phase two-wire output (UO) mode MC, single-phase two-wire output (WO) mode MD). have. The output stop mode MA is a mode for stopping power output to the load device LOAD. The single-phase three-wire output mode MB is a mode in which the power conversion device 1 operates as a single-phase three-wire power conversion device to supply power to the load device LOAD. In single-phase two-wire output (UO) mode MC, power conversion device 1 operates as a single-phase two-wire power conversion device to supply power to load device LOAD via two output terminals T21 and T23. is a mode that supplies In the single-phase two-wire output (WO) mode MD, the power conversion device 1 operates as a single-phase two-wire power conversion device to supply power to the load device LOAD via the two output terminals T22 and T23. is a mode that supplies

For example, when the power converter 1 is operating in the single-phase three-wire output mode MB, the power supply control unit 31 detects, for example, an overvoltage in the voltage e_wo or an overcurrent in the current i_w, the W-phase voltage is stopped, and the power converter 1 is controlled to operate in the single-phase two-wire output (UO) mode MC. Further, for example, when the power converter 1 is operating in the single-phase three-wire output mode MB, the power supply control unit 31 detects an overvoltage in the voltage e_uo or an overcurrent in the current i_u. Generation of the phase voltage is stopped, and the power converter 1 is controlled to operate in the single-phase two-wire output (WO) mode MD.

First, an example in which the power conversion device 1 performs unipolar PWM operation will be described in detail below. After that, an example in which the power converter 1 performs the bipolar PWM operation will be briefly described.

FIG. 3 shows an operation example of the power supply control unit 31 when the power converter 1 performs unipolar PWM operation. 4A to 4D show an operation example of the drive unit 60 when the power conversion device 1 performs unipolar PWM operation. FIG. 4A shows the operation in the output stop mode MA, and FIG. Operation in phase three-wire output mode MB is shown, FIG. 4C shows operation in single-phase two-wire output (UO) mode MC, and FIG. 4D shows operation in single-phase two-wire output (WO) mode MD. indicates In FIGS. 4A to 4D, among the three gate signal generators 63U, 63O, 63W, the gate signal generator whose operation is stopped is indicated by a dashed line. In the unipolar PWM operation, the control signal PWMSW is set to "-1". FIG. 5 shows an example of the output voltage waveform of the power conversion device 1, (A) shows the operation in the single-phase three-wire output mode MB, and (B) shows the single-phase two-wire output (UO). Operation in mode MC is shown.

In the output stop mode MA, as shown in FIG. 3, the power supply control unit 31 turns the switches 27U, 27O, 27W to "OFF", "OFF", "" through the switch control signals Sstdu, Sstdo, Sstdw. OFF”. As a result, the power conversion device 1 is electrically disconnected from the load device LOAD. Further, the power supply control unit 31 sets the control signals Sgbu, Sgbo, Sgbw to "0", "0", and "0", respectively, and the switch SW0 selects the terminal T0 via the control signal SEL. to control. Thereby, as shown in FIGS. 3 and 4A, the duty ratio command values d_u*, d_o* and d_w* are set to "0", "0" and "0" respectively. Then, the gate signal generation section 63U sets the gate signals S1 and S2 to low level, the gate signal generation section 63O sets the gate signals S5 and S6 to low level, and the gate signal generation section 63W sets the gate signal S3 to low level. , S4 to a low level. As a result, all the switching elements SW1 to SW6 are turned off. Thus, the power conversion device 1 stops power output to the load device LOAD.

In the single-phase three-wire output mode MB, as shown in FIG. 3, the power supply control unit 31 turns the switches 27U, 27O and 27W "ON" and "ON" via the switch control signals Sstdu, Sstdo and Sstdw. ” and “ON” respectively. Thereby, the power conversion device 1 is electrically connected to the load device LOAD via the three output terminals T21, T22, T23. Further, the power supply control unit 31 sets the control signals Sgbu, Sgbo, Sgbw to "1", "1", and "1", respectively, and the switch SW0 selects the terminal T1 via the control signal SEL. to control. Thereby, as shown in FIGS. 3 and 4B, the duty ratio command values d_u*, d_o* and d_w* are set to "d_dm*", "d_cm*" and "-d_dm*", respectively. Gate signal generator 63U generates gate signals S1 and S2 based on duty ratio command value d_u* (“d_dm*”), and gate signal generator 63O generates duty ratio command value d_o* (“d_cm*”). and the gate signal generator 63W generates gate signals S3 and S4 based on the duty ratio command value d_w* (“−d_dm*”). Switching elements SW1 and SW2 are turned on and off based on gate signals S1 and S2, switching elements SW5 and SW6 are turned on and off based on gate signals S5 and S6, and switching elements SW3 and SW4 are turned on and off based on gate signals S3 and S4. . The control unit 30 controls the voltage amplitude of the voltage e_uw by controlling the operations of the switching elements SW1 to SW4, and balances the voltage e_uo and the voltage e_wo by controlling the operations of the switching elements SW5 and SW6. The voltage at the neutral point (neutral line OL) is controlled so as to maintain the voltage. As a result, as shown in FIG. 5A, the voltage e_u at the output terminal T21 and the voltage e_w at the output terminal T22 have alternating waveforms with opposite polarities, and the voltage e_o at the output terminal T23 is becomes about 0V. Thus, the power conversion device 1 performs single-phase three-wire output operation.

In the single-phase two-wire output (UO) mode MC, as shown in FIG. 3, the power supply control unit 31 switches the switches 27U, 27O, 27W to " ON”, “ON”, and “OFF” respectively. Thereby, the power conversion device 1 is electrically connected to the load device LOAD via the two output terminals T21 and T23. Further, the power supply control unit 31 sets the control signals Sgbu, Sgbo, Sgbw to "1", "1", and "0", respectively, and the switch SW0 selects the terminal T2 via the control signal SEL. to control. Thereby, as shown in FIGS. 3 and 4C, the duty ratio command values d_u*, d_o* and d_w* are set to "d_dm*", "-d_dm*" and "0", respectively. The gate signal generator 63U generates gate signals S1 and S2 based on the duty ratio command value d_u* (“d_dm*”), and the gate signal generator 63O generates the duty ratio command value d_o* (“−d_dm*” ), and the gate signal generator 63W sets the gate signals S3 and S4 to low level. Switching elements SW1 and SW2 are turned on and off based on gate signals S1 and S2, switching elements SW5 and SW6 are turned on and off based on gate signals S5 and S6, and switching elements SW3 and SW4 are turned off based on gate signals S3 and S4. become. The control unit 30 controls the voltage amplitude of the voltage e_uo by controlling the operations of the switching elements SW1, SW2, SW5 and SW6. As a result, as shown in FIG. 5B, the voltage e_u at the output terminal T21 and the voltage e_o at the output terminal T23 have AC waveforms with opposite polarities. Thus, the power conversion device 1 performs single-phase two-wire output operation.

In the single-phase two-wire output (WO) mode MD, as shown in FIG. 3, the power supply control unit 31 switches the switches 27U, 27O, 27W to " OFF”, “ON”, and “ON” respectively. Thereby, the power conversion device 1 is electrically connected to the load device LOAD via the two output terminals T22 and T23. Further, the power supply control unit 31 sets the control signals Sgbu, Sgbo, Sgbw to "0", "1", and "1", respectively, and the switch SW0 selects the terminal T0 via the control signal SEL. to control. Thereby, as shown in FIGS. 3 and 4D, the duty ratio command values d_u*, d_o* and d_w* are set to "0", "d_dm*" and "-d_dm*", respectively. The gate signal generator 63U sets the gate signals S1 and S2 to a low level, the gate signal generator 63O generates the gate signals S5 and S6 based on the duty ratio command value d_o* (“d_dm*”), The gate signal generator 63W generates gate signals S3 and S4 based on the duty ratio command value d_w* (“−d_dm*”). Switching elements SW1 and SW2 are turned off based on gate signals S1 and S2, switching elements SW5 and SW6 are turned on and off based on gate signals S5 and S6, and switching elements SW3 and SW4 are turned off based on gate signals S3 and S4. turn on and off. The control unit 30 controls the voltage amplitude of the voltage e_wo by controlling the operations of the switching elements SW3 to SW6. As a result, the voltage e_w at the output terminal T22 and the voltage e_o at the output terminal T23 are alternating waveforms with opposite polarities, as in the single-phase two-wire output (UO) mode MC (FIG. 5B). become. Thus, the power conversion device 1 performs single-phase two-wire output operation.

FIG. 6 shows an operation example of the power supply control unit 31 when the power converter 1 performs the bipolar PWM operation. The settings of control signals Sgbu, Sgbo, Ssbw, switches 27U, 27O, 27W, and switch SW0 are the same as in the case of unipolar PWM operation (FIG. 3). On the other hand, in the bipolar PWM operation, the control signal PWMSW is set to "1", so the duty ratio command values d_u*, d_o*, d_w* are different from those in the unipolar PWM operation.

Specifically, in the single-phase three-wire output mode MB, the duty ratio command values d_u*, d_o*, d_w* are set to "d_dm*", "d_cm*", and "d_dm*", respectively. Gate signal generator 63U generates gate signals S1 and S2 based on duty ratio command value d_u* (“d_dm*”), and gate signal generator 63O generates duty ratio command value d_o* (“d_cm*”). and the gate signal generator 63W generates gate signals S3 and S4 based on the duty ratio command value d_w* (“d_dm*”).

In single-phase two-wire output (UO) mode MC, duty ratio command values d_u*, d_o*, d_w* are set to "d_dm*", "d_dm*", and "0", respectively. Gate signal generator 63U generates gate signals S1 and S2 based on duty ratio command value d_u* (“d_dm*”), and gate signal generator 63O generates duty ratio command value d_o* (“d_dm*”). , and the gate signal generator 63W sets the gate signals S3 and S4 to low level.

In the single-phase two-wire output (WO) mode MD, the duty ratio command values d_u*, d_o* and d_w* are set to "0", "d_dm*" and "d_dm*", respectively. The gate signal generator 63U sets the gate signals S1 and S2 to a low level, the gate signal generator 63O generates the gate signals S5 and S6 based on the duty ratio command value d_o* (“d_dm*”), The gate signal generator 63W generates the gate signals S3 and S4 based on the duty ratio command value d_w* (“d_dm*”).

FIG. 7 shows state transitions between the four control modes M. In FIG.

For example, when the power converter 1 is operating in the single-phase three-wire output mode MB, when the power supply control unit 31 detects, for example, an overvoltage in the voltage e_uo or an overcurrent in the current i_u, the control mode M transitions from the single-phase three-wire output mode MB to the single-phase two-wire output (WO) mode MD. Then, when the power conversion device 1 is operating in the single-phase two-wire output (WO) mode MD, when such overvoltage and overcurrent are eliminated, the control mode M is the single-phase 2 A transition is made from the line output (WO) mode MD to the single-phase three-line output mode MB. For example, when the power conversion device 1 is operating in the single-phase two-wire output (WO) mode MD, the power supply control unit 31 detects, for example, an overvoltage in the voltage e_wo or an overcurrent in the current i_w. , the control mode M transitions from the single-phase two-wire output (WO) mode MD to the output stop mode MA. Then, when all overvoltages and overcurrents are eliminated, the control mode M transitions from the output stop mode MA to the single-phase three-wire output mode MB.

Similarly, for example, when the power converter 1 is operating in the single-phase three-wire output mode MB, when the power supply control unit 31 detects, for example, an overvoltage in the voltage e_wo or an overcurrent in the current i_w, Control mode M transitions from single-phase three-wire output mode MB to single-phase two-wire output (UO) mode MC. Then, when the power converter 1 is operating in the single-phase two-wire output (UO) mode MC, when such overvoltage and overcurrent are eliminated, the control mode M is the single-phase 2 A transition is made from the line output (UO) mode MC to the single-phase three-line output mode MB. For example, when the power converter 1 is operating in the single-phase two-wire output (UO) mode MC, the power supply control unit 31 detects, for example, an overvoltage in the voltage e_uo or an overcurrent in the current i_u. , the control mode M transitions from the single-phase two-wire output (UO) mode MC to the output stop mode MA. Then, when all overvoltages and overcurrents are eliminated, the control mode M transitions from the output stop mode MA to the single-phase three-wire output mode MB.

Similarly, for example, when the power converter 1 is operating in the single-phase three-wire output mode MB, the power supply control unit 31 detects, for example, an overvoltage in the voltage e_uo or an overcurrent in the current i_u, and the voltage When an overvoltage in e_wo or an overcurrent in current i_w is detected, the control mode M transitions from the single-phase three-wire output mode MB to the output stop mode MA. Then, when all these overvoltages and overcurrents are eliminated, the control mode M transitions from the output stop mode MA to the single-phase three-wire output mode MB.

In addition, the power supply control unit 31 changes the control mode M from an output stop mode MA, a single-phase three-wire output mode MB, and a single-phase two-wire output (UO) mode based on an externally supplied control signal CTL. Either MC or single-phase two-wire output (WO) mode MD can be selectively set.

The power supply control unit 31 thus controls the power supply operation of the power conversion device 1 to the load device LOAD in the four control modes M. FIG.

Here, the switching elements SW1, SW2, SW3, SW4, SW5, and SW6 are "first switching element," "second switching element," "third switching element," and "fourth switching element" in the present disclosure. ”, “fifth switching element”, and “sixth switching element”, respectively. The voltage line L1 corresponds to a specific example of the "first voltage line" in the present disclosure, and the reference voltage line L2 corresponds to a specific example of the "second voltage line" in the present disclosure. The node N1 corresponds to a specific example of the "first node" in the present disclosure, the node N2 corresponds to a specific example of the "second node" in the present disclosure, and the node N3 corresponds to the " This corresponds to a specific example of "third node". The output terminal T21 corresponds to a specific example of the "first output terminal" in the present disclosure, the output terminal T22 corresponds to a specific example of the "second output terminal" in the present disclosure, and the output terminal T23 corresponds to , corresponds to a specific example of the “third output terminal” in the present disclosure. The low-pass filter 29 corresponds to a specific example of "low-pass filter" in the present disclosure. The controller 30 corresponds to a specific example of the "controller" in the present disclosure. The single-phase three-wire output mode MB corresponds to a specific example of "first control mode" in the present disclosure. The single-phase two-wire output (UO) mode MC corresponds to a specific example of "second control mode" in the present disclosure. The single-phase two-wire output (WO) mode MD corresponds to a specific example of the "third control mode" in the present disclosure. The switch 27U corresponds to a specific example of the "first switch" in the present disclosure, the switch 27W corresponds to a specific example of the "second switch" in the present disclosure, and the switch 27O corresponds to the " This corresponds to a specific example of "third switch".

Voltage e_uo corresponds to a specific example of "first voltage" in the present disclosure. The voltage command value e_uo* corresponds to a specific example of "first voltage command value" in the present disclosure. Voltage e_wo corresponds to a specific example of "second voltage" in the present disclosure. The voltage command value e_wo* corresponds to a specific example of "second voltage command value" in the present disclosure. Current i_u corresponds to a specific example of "first current" in the present disclosure. The load current i_ldu corresponds to a specific example of "first load current" in the present disclosure. The current command value i_u* corresponds to a specific example of "first current command value" in the present disclosure. Current i_w corresponds to a specific example of "second current" in the present disclosure. The load current i_ldw corresponds to a specific example of "second load current" in the present disclosure. The current command value i_w* corresponds to a specific example of "second current command value" in the present disclosure. The DM duty ratio command value d_dm* corresponds to a specific example of "first duty ratio command value" in the present disclosure. The CM duty ratio command value d_cm* corresponds to a specific example of "second duty ratio command value" in the present disclosure.

[Operation and action]
Next, the operation and action of the power converter 1 of the present embodiment will be described.

(Outline of overall operation)
First, with reference to FIGS. 1 and 2, an overview of the overall operation of the power converter 1 will be described.

In the output stop mode MA, the controller 30 sets the switches 27U, 27O and 27W to "OFF", "OFF" and "OFF", respectively. As a result, the power conversion device 1 is electrically disconnected from the load device LOAD. Also, the control unit 30 sets the gate signals S1 to S6 to a low level. As a result, all the switching elements SW1 to SW6 are turned off. Thus, the power conversion device 1 stops power output to the load device LOAD.

In the single-phase three-wire output mode MB, the controller 30 sets the switches 27U, 27O and 27W to "ON", "ON" and "ON", respectively. Thereby, the power conversion device 1 is electrically connected to the load device LOAD via the three output terminals T21, T22, T23. The control unit 30 also generates gate signals S1 to S6 based on the DC bus voltage Vdc, the currents i_u and i_w, and the voltages e_uo and e_wo. The switching elements SW1 to SW6 are turned on and off based on these gate signals S1 to S6. The control unit 30 controls the voltage amplitude of the voltage e_uw by controlling the operations of the switching elements SW1 to SW4, and balances the voltage e_uo and the voltage e_wo by controlling the operations of the switching elements SW5 and SW6. The voltage at the neutral point (neutral line OL) is controlled so as to maintain the voltage. Thus, the power converter 1 performs single-phase three-wire output operation.

In the single-phase two-wire output (UO) mode MC, the controller 30 sets the switches 27U, 27O and 27W to "ON", "ON" and "OFF", respectively. Thereby, the power conversion device 1 is electrically connected to the load device LOAD via the two output terminals T21 and T23. The control unit 30 also generates gate signals S1 to S6 based on the DC bus voltage Vdc, the currents i_u and i_w, and the voltages e_uo and e_wo. The switching elements SW1 and SW2 are turned on and off based on the gate signals S1 and S2, and the switching elements SW5 and SW6 are turned on and off based on the gate signals S5 and S6. The switching elements SW3 and SW4 are turned off based on the gate signals S3 and S4. The control unit 30 controls the voltage amplitude of the voltage e_uo by controlling the operations of the switching elements SW1, SW2, SW5 and SW6. Thus, the power converter 1 performs single-phase two-wire output operation.

In the single-phase two-wire output (WO) mode MD, the controller 30 sets the switches 27U, 27O and 27W to "OFF", "ON" and "ON", respectively. Thereby, the power conversion device 1 is electrically connected to the load device LOAD via the two output terminals T22 and T23. The control unit 30 also generates gate signals S1 to S6 based on the DC bus voltage Vdc, the currents i_u and i_w, and the voltages e_uo and e_wo. The switching elements SW5 and SW6 are turned on and off based on the gate signals S5 and S6, and the switching elements SW3 and SW4 are turned on and off based on the gate signals S3 and S4. The switching elements SW1 and SW2 are turned off based on the gate signals S1 and S2. The control unit 30 controls the voltage amplitude of the voltage e_wo by controlling the operations of the switching elements SW3 to SW6. Thus, the power converter 1 performs single-phase two-wire output operation.

(detailed operation)
The duty ratio generation unit 40 of the control unit 30 (FIG. 2) generates the DC bus voltage Vdc, current i_u, DM duty ratio command value d_dm* and CM duty ratio command value d_cm* are calculated based on i_w and voltages e_uo and e_wo. Then, the driving section 60 generates the gate signals S1 to S6 based on the DM duty ratio command value d_dm* and the CM duty ratio command value d_cm*. The switching elements SW1 to SW6 are turned on and off based on these gate signals S1 to S6. In the power conversion device 1, the voltage e_uo is controlled to be approximately the same as the voltage command value e_uo* by loop control, the voltage e_wo is controlled to be approximately the same as the voltage command value e_wo*, and the DM current i_dm is controlled to be approximately the same as the voltage command value e_wo*. It is controlled so as to be approximately the same as the DM current command value i_dm*, and the CM current i_cm is controlled so as to be approximately the same as the CM current command value i_cm*.

Further, the control unit 30 controls the power supply operation of the power converter 1 to the load device LOAD based on the currents i_u, i_w and the voltages e_uo, e_wo. Specifically, for example, when an overvoltage in the voltage e_uo or an overcurrent in the current i_u is detected, the control unit 30 changes the control mode M from the single-phase three-wire output mode MB to the single-phase two-wire output (W- O) By making a transition to mode MD, generation of the U-phase voltage is stopped and single-phase two-wire output operation is performed. Further, for example, when an overvoltage in the voltage e_wo or an overcurrent in the current i_w is detected, the control unit 30 changes the control mode M from the single-phase three-wire output mode MB to the single-phase two-wire output (UO) mode. By making the transition to MC, generation of the W-phase voltage is stopped, and single-phase two-wire output operation is performed.

(Transition from single-phase three-wire output mode MB to single-phase two-wire output (WO) mode MD)
FIG. 8 shows an operation example of the duty ratio generator 40 when the control mode M transitions from the single-phase three-wire output mode MB to the single-phase two-wire output (WO) mode MD.

これにより、デューティ比生成部４０は、図８に示したように動作する。Ｕ相電圧制御部４５に供給される、電圧指令値ｅ_uo*、電圧ｅ_uo、負荷電流ｉ_lduはともに“０”になる。よって、Ｕ相電圧制御部４５が生成する電流指令値i_u*は、式ＥＱ７の第３式に基づいて“０”になる。よって、減算部４７が生成するＤＭ電流指令値ｉ_dm*は“－ｉ_w*”になる。ＤＭ電流制御部５５は、ＤＭ電流指令値ｉ_dm*（“－ｉ_w*”）、ＤＭ電流ｉ_dm（“－ｉ_w”）、ＤＭ電圧ｅ_dm（“－ｅ_wo”）に基づいて、ＤＭデューティ比指令値ｄ_dm*を生成する。このＤＭデューティ比指令値ｄ_dm*は“－ｄ_w*”になる。すなわち、ＤＭデューティ比指令値ｄ_dm*は、Ｗ相の負のデューティ比指令値である。 For example, when an overvoltage of the voltage e_uo or an overcurrent of the current i_u is detected, the power supply control unit 31 sets the control signal Sgbu to “0” and turns off the switch 27U via the switch control signal Sstdu. to Since the control signal Sgbu becomes "0", the voltage command value e_uo* shown in the fifth equation of the equation EQ7 becomes "0", and accordingly the voltage e_uo and the differential of the voltage e_uo become "0". . Also, since the switch 27U is turned off, the load current i_ldu becomes "0" and the current command value i_u* shown in the third equation of the equation EQ7 becomes "0". becomes "0". As a result, the following equation EQ10 is derived.

As a result, the duty ratio generator 40 operates as shown in FIG. The voltage command value e_uo*, the voltage e_uo, and the load current i_ldu supplied to the U-phase voltage control unit 45 all become "0". Therefore, the current command value i_u* generated by the U-phase voltage control unit 45 becomes "0" based on the third expression of the expression EQ7. Therefore, the DM current command value i_dm* generated by the subtraction unit 47 is "-i_w*". Based on the DM current command value i_dm* (“-i_w*”), the DM current i_dm (“-i_w”), and the DM voltage e_dm (“-e_wo”), the DM current control unit 55 sets the DM duty ratio command value d_dm *. This DM duty ratio command value d_dm* becomes "-d_w*". That is, the DM duty ratio command value d_dm* is a W-phase negative duty ratio command value.

Since the control signals Sgbu, Sgbo and Sgbw are "0", "1" and "1", the terminal T0 is selected in the switch SW0 of the driving section 60 (FIG. 2). Thus, for example, in unipolar PWM operation, as shown in FIG. 4D, the gate signal generator 63W generates the gate signals S3 and S4 based on the DM duty ratio command value −d_dm* (“d_w*”). , the gate signal generator 63O generates the gate signals S5 and S6 based on the DM duty ratio command value d_dm* (“−d_w*”). The gate signal generator 63U generates low-level gate signals S1 and S2. In the single-phase two-wire output (WO) mode MD, the CM duty ratio command value d_cm* generated by the CM current control section 56 is not used.

Thus, in the power converter 1, the control mode M transitions from the single-phase three-wire output mode MB to the single-phase two-wire output (WO) mode MD. During this transition, the power conversion device 1 continuously generates a self-sustaining voltage between WO. That is, since the DM current control unit 55 does not perform discontinuous operation when the control signal Sgbu changes from "1" to "0", the power converter 1 can switch the control mode M without instantaneous interruption. It can be performed.

Here, "no instantaneous interruption" includes, for example, not only the case where an instantaneous interruption does not occur, but also that the instantaneous interruption time is 5 milliseconds or less even when an instantaneous interruption occurs. This 5 milliseconds corresponds to, for example, 1/4 of the period of a 50 Hz power supply signal. That is, for example, when the momentary power failure time exceeds the time corresponding to one cycle of the power supply signal, there is a possibility that the load device that operates by receiving the supply of this power supply signal may malfunction or stop operating. However, if the momentary power failure time is 1/4 or less of the cycle of the power supply signal, it is possible to reduce the risk of malfunction or stoppage of the load device.

In the power converter 1, when the control mode M transitions from the single-phase three-wire output mode MB to the single-phase two-wire output (WO) mode MD, the control signal Sgbu is changed from "1" to "0". In this example, the AD conversion circuit of the control unit 30 performs AD conversion every cycle Ts (for example, 50 μsec. (=1/20 kHz)), so the power converter 1 can switch the control mode M within 50 μsec. can. That is, in the power conversion device 1, the momentary power failure time accompanying the transition of the control mode M can be reduced to 5 milliseconds or less. As a result, in the load device LD of the power conversion device 1, it is possible to reduce the possibility of malfunction or stopping of operation.

(Transition from single-phase three-wire output mode MB to single-phase two-wire output (UO) mode MC)
FIG. 9 shows an operation example of the duty ratio generator 40 when the control mode M transitions from the single-phase three-wire output mode MB to the single-phase two-wire output (UO) mode MC.

これにより、デューティ比生成部４０は、図９に示したように動作する。Ｗ相電圧制御部４６に供給される、電圧指令値ｅ_wo*、電圧ｅ_wo、負荷電流ｉ_ldwはともに“０”になる。よって、Ｗ相電圧制御部４６が生成する電流指令値i_w*は、式ＥＱ７の第４式に基づいて“０”になる。よって、減算部４７が生成するＤＭ電流指令値ｉ_dm*は“ｉ_u*”になる。ＤＭ電流制御部５５は、ＤＭ電流指令値ｉ_dm*（“ｉ_u*”）、ＤＭ電流ｉ_dm（“ｉ_u”）、ＤＭ電圧ｅ_dm（“ｅ_uo”）に基づいて、ＤＭデューティ比指令値ｄ_dm*を生成する。このＤＭデューティ比指令値ｄ_dm*は、Ｕ相のデューティ比指令値ｄ_u*である。 For example, when an overvoltage of the voltage e_wo or an overcurrent of the current i_w is detected, the power supply control unit 31 sets the control signal Sgbw to “0” and turns off the switch 27W via the switch control signal Sstdw. to Since the control signal Sgbw becomes "0", the voltage command value e_wo* shown in the sixth equation of the equation EQ7 becomes "0", and accordingly the voltage e_wo and the differential of the voltage e_wo become "0". . Also, since the switch 27W is turned off, the load current i_ldw becomes "0" and the current command value i_w* shown in the fourth equation of the equation EQ7 becomes "0". becomes "0". As a result, the following equation EQ10 is derived.

As a result, the duty ratio generator 40 operates as shown in FIG. The voltage command value e_wo*, the voltage e_wo, and the load current i_ldw supplied to the W-phase voltage control unit 46 all become "0". Therefore, the current command value i_w* generated by the W-phase voltage control unit 46 becomes "0" based on the fourth expression of the expression EQ7. Therefore, the DM current command value i_dm* generated by the subtraction unit 47 becomes "i_u*". The DM current control unit 55 generates a DM duty ratio command value d_dm* based on the DM current command value i_dm* (“i_u*”), the DM current i_dm (“i_u”), and the DM voltage e_dm (“e_uo”). do. This DM duty ratio command value d_dm* is the U-phase duty ratio command value d_u*.

Since the control signals Sgbu, Sgbo and Sgbw are "1", "1" and "0", the terminal T2 is selected in the switch SW0 of the driving section 60 (FIG. 2). Thus, for example, in the unipolar PWM operation, as shown in FIG. 4C, the gate signal generator 63U generates the gate signals S1 and S2 based on the DM duty ratio command value d_dm* (“d_u*”), The gate signal generator 63O generates the gate signals S5 and S6 based on the DM duty ratio command value -d_dm* ("-d_u*"). The gate signal generator 63W generates low-level gate signals S3 and S4. In the single-phase two-wire output (UO) mode MC, the CM duty ratio command value d_cm* generated by the CM current control section 56 is not used.

Thus, in the power converter 1, the control mode M transitions from the single-phase three-wire output mode MB to the single-phase two-wire output (UO) mode MC. During this transition, in the power conversion device 1, the self-sustaining voltage between U and O is continuously generated. That is, since the DM current control unit 55 does not perform discontinuous operation when the control signal Sgbw changes from "1" to "0", the power converter 1 can switch the control mode M without instantaneous interruption. It can be performed. In the power conversion device 1, the momentary power failure time accompanying the transition of the control mode M can be reduced to 5 milliseconds or less. As a result, in the load device LD of the power conversion device 1, it is possible to reduce the possibility of malfunction or stopping of operation.

(Simulation example)
The operation and effects of the power converter 1 will be described below using some simulation examples. In the following simulation, simulation conditions were set as shown in FIG. In this example, in the load device LOAD, the load Z1 between U and O is a half-wave rectification load, and the load Z2 between WO and WO is a full-wave rectification load. No load Z3 is provided between U and W.

First, the transition between single-phase three-wire output mode MB and single-phase two-wire output (WO) mode MD will be described in detail.

FIG. 11 shows an example of simulation results of the power conversion device 1. (A) shows waveforms of voltages e_uo and e_wo, (B) shows waveforms of load currents i_ldu and i_ldw, and (C) shows waveforms of load currents i_ldu and i_ldw. Waveforms of effective values Euorms and Eworms are shown, and (D) shows waveforms of control signals Sgbu and Sgbw. In this example, the power converter 1 performs unipolar PWM operation.

In this example, the control mode M transitions from the single-phase three-wire output mode MB to the single-phase two-wire output (WO) mode MD at timing t1, and the single-phase two-wire output (WO) mode at timing t2. A transition is made from MD to single-phase three-wire output mode MB. Timings t1 and t2 can be set independently of so-called zero-cross timings in voltages e_uo and e_wo.

In this example, the power conversion device 1 operates in the single-phase three-wire output mode MB during a period before timing t1. Voltages e_uo and e_wo have a sine wave shape (FIG. 11(A)). In this example, the effective values Euorms and Eworms are both about 120V (FIG. 11(C)). Since the load Z1 is a half-wave rectified load, the load current i_ldu has a half-wave waveform (FIG. 11(B)). On the other hand, since the load Z2 is a full-wave rectified load, the load current i_ldw has a sine wave shape.

Then, at timing t1, the control mode M transitions from the single-phase three-wire output mode MB to the single-phase two-wire output (WO) mode MD. Specifically, at this timing t1, the power supply control unit 31 turns off the switch 27U via the switch control signal Sstdu, and changes the control signal Sgbu from "1" to "0". (FIG. 11(D)). As a result, the gate signal generator 63U sets the gate signals S1 and S2 to a low level, the voltage e_uo becomes approximately 0 V ((A) in FIG. 11), and the effective value Euorms is approximately becomes "0" (FIG. 11(C)). The duty ratio generator 40 generates a DM duty ratio command value d_dm*. In the single-phase two-wire output (WO) mode MD (FIG. 4D), the gate signal generator 63W generates gate signals S3 and S4 based on the duty ratio command value d_w* (“−d_dm*”), The gate signal generator 63O generates gate signals S5 and S6 based on the duty ratio command value d_o* (“d_dm*”). Thereby, the power conversion device 1 continues to generate the voltage e_wo, which is the AC output voltage (FIG. 11(A)). Thus, in the power conversion device 1, the control mode M can be quickly switched from the single-phase three-wire output mode MB to the single-phase two-wire output (WO) mode MD based on the change in the control signal Sgbu. can.

At subsequent timing t2, the control mode M transitions from the single-phase two-wire output (WO) mode MD to the single-phase three-wire output mode MB. Specifically, at this timing t2, the power supply control unit 31 turns on the switch 27U via the switch control signal Sstdu, and changes the control signal Sgbu from "0" to "1". (FIG. 11(D)). The duty ratio generator 40 generates a DM duty ratio command value d_dm* and a CM duty ratio command value d_cm*. In the single-phase three-wire output mode MB (FIG. 4B), the gate signal generator 63U generates the gate signals S1 and S2 based on the duty ratio command value d_u* (“d_dm*”), and the gate signal generator 63W , the gate signals S3 and S4 based on the duty ratio command value d_w* (“−d_dm*”), and the gate signal generator 630 generates the gate signal based on the duty ratio command value d_o* (“d_cm*”). Generate S5 and S6. As a result, the power electronics device 1 continues to generate the voltage e_wo and resumes generating the voltage e_uo, which is the AC output voltage (FIG. 11(A)). Thus, in the power conversion device 1, the control mode M can be quickly switched from the single-phase two-wire output (WO) mode MD to the single-phase three-wire output mode MB based on the change in the control signal Sgbu. can.

Next, transitions between single-phase three-wire output mode MB and single-phase two-wire output (UO) mode MC will be described in detail.

FIG. 12 shows an example of simulation results of the power conversion device 1. (A) shows waveforms of voltages e_uo and e_wo, (B) shows waveforms of load currents i_ldu and i_ldw, and (C) shows waveforms of load currents i_ldu and i_ldw. Waveforms of effective values Euorms and Eworms are shown, and (D) shows waveforms of control signals Sgbu and Sgbw.

In this example, the control mode M transitions from the single-phase three-wire output mode MB to the single-phase two-wire output (UO) mode MC at timing t3, and the single-phase two-wire output (UO) mode at timing t4. A transition is made from MC to single-phase three-wire output mode MB. Timings t3 and t4 can be set independently of so-called zero-cross timings in voltages e_uo and e_wo.

In this example, the power conversion device 1 operates in the single-phase three-wire output mode MB during a period before timing t3. Then, at timing t3, the control mode M transitions from the single-phase three-wire output mode MB to the single-phase two-wire output (UO) mode MC. Specifically, at this timing t3, the power supply control unit 31 turns off the switch 27W via the switch control signal Sstdw, and changes the control signal Sgbw from "1" to "0". (FIG. 12(D)). As a result, the gate signal generator 63W sets the gate signals S3 and S4 to a low level (“0”), the voltage e_wo becomes approximately 0 V ((A) in FIG. 12), and the effective value Eworms reaches this timing t3. 12(C)). The duty ratio generator 40 generates a DM duty ratio command value d_dm*. In the single-phase two-wire output (UO) mode MC (FIG. 4C), the gate signal generator 63U generates the gate signals S1 and S2 based on the duty ratio command value d_u* (“d_dm*”), and the gate The signal generator 63O generates the gate signals S5 and S6 based on the duty ratio command value d_o* (“-d_dm*”). As a result, the power converter 1 continues to generate the voltage e_uo, which is the AC output voltage ((A) in FIG. 12). Thus, in the power conversion device 1, the control mode M can be quickly switched from the single-phase three-wire output mode MB to the single-phase two-wire output (UO) mode MC based on the change in the control signal Sgbw. can.

At subsequent timing t4, the control mode M transitions from the single-phase two-wire output (UO) mode MC to the single-phase three-wire output mode MB. Specifically, at timing t4, the power supply control unit 31 turns on the switch 27W via the switch control signal Sstdw, and changes the control signal Sgbw from "0" to "1". (FIG. 12(D)). The duty ratio generator 40 generates a DM duty ratio command value d_dm* and a CM duty ratio command value d_cm*. In the single-phase three-wire output mode MB (FIG. 4B), the gate signal generator 63U generates the gate signals S1 and S2 based on the duty ratio command value d_u* (“d_dm*”), and the gate signal generator 63W , the gate signals S3 and S4 based on the duty ratio command value d_w* (“−d_dm*”), and the gate signal generator 630 generates the gate signal based on the duty ratio command value d_o* (“d_cm*”). Generate S5 and S6. As a result, the power electronics device 1 continues to generate the voltage e_uo and restarts generating the voltage e_wo, which is the AC output voltage (FIG. 12(A)). Thus, in the power conversion device 1, the control mode M can be quickly switched from the single-phase two-wire output (UO) mode MC to the single-phase three-wire output mode MB based on the change in the control signal Sgbw. can.

Thus, in the power conversion device 1, one of the switching element pair consisting of the switching elements SW1 and SW2 and the switching element pair consisting of the switching elements SW3 and SW4 can be selectively turned off. . As a result, in the power conversion device 1, for example, when an overvoltage of the voltage e_wo or an overcurrent of the current i_w is detected, the power supply to the load Z2 can be stopped and the power supply to the load Z1 can be continued. . Similarly, in the power conversion device 1, for example, when an overvoltage of the voltage e_uo or an overcurrent of the current i_u is detected, power supply to the load Z1 is stopped and power supply to the load Z2 can be continued. . As a result, the power conversion device 1 can appropriately supply power and stop the power supply. As a result, the power converter 1 can appropriately supply power and stop the power supply without stopping the power conversion operation. As a result, the robustness of the power conversion device 1 can be enhanced.

Further, in the power converter 1, a current command value i_u* is generated based on the voltage command value e_uo*, the voltage e_uo, and the load current i_ldu, and based on the voltage command value e_wo*, the voltage e_wo, and the load current i_ldw A current command value i_w* is generated. A DM duty ratio command value d_dm* is generated based on the difference between the current command value i_u* and the current command value i_w*, and a CM duty ratio command value is generated based on the sum of the current command value i_u* and the current command value i_w*. I made it to generate the value d_cm*. Based on the DM duty ratio command value d_dm* and the CM duty ratio command value d_cm*, the operations of the switching elements SW1 to SW6 are controlled. As a result, in the power conversion device 1, for example, between the single-phase three-wire output mode MB and the single-phase two-wire output (WO) mode MD, between the single-phase three-wire output mode MB and the single-phase two-wire output ( When the control mode M is switched between the UO) mode MC, etc., the DM current control unit 55 does not perform discontinuous operation. can be switched.

Further, in the power converter 1, a current command value i_u* is generated based on the voltage command value e_uo*, the voltage e_uo, and the load current i_ldu, and based on the voltage command value e_wo*, the voltage e_wo, and the load current i_ldw A current command value i_w* is generated. Then, for example, when stopping power supply to load Z1, the current command value i_u* is set to "0" as shown in FIG. 8, and when stopping power supply to load Z2, FIG. , the current command value i_w* is set to "0". That is, the current command value i_u* is set to a predetermined command value that prevents the current i_u from flowing, and the current command value i_w* is set to a predetermined command value that prevents the current i_w from flowing. As a result, the power conversion device 1 can switch the control mode M without interruption.

Further, in the power conversion device 1, when stopping the power supply to the load Z1, as shown in FIG. *”), the switching elements SW5 and SW6 are driven, so that the power can be continuously supplied to the load Z2 by performing the single-phase two-wire output operation. Similarly, when stopping the power supply to load Z2, as shown in FIG. Since the switching elements SW5 and SW6 are driven based on the above, power can be continuously supplied to the load Z1. As a result, the power converter 1 can appropriately supply power and stop the power supply.

Further, in the power converter 1, the current estimating unit 42 of the control unit 30 estimates the current i_cu flowing through the capacitive element 25U based on the voltages e_uo and e_wo as shown in the equation EQ5, and The flowing current i_cw was estimated. Then, the subtraction unit 43 calculates the load current i_ldu using the first equation of the equation EQ5 based on the currents i_u and i_cu, and the subtraction unit 44 calculates the second equation of the equation EQ5 based on the currents i_w and i_cw. was used to obtain the load current i_ldw. Then, as shown in FIG. 2, the control unit 30 controls the operations of the switching elements SW1 to SW6 based on these load currents i_ldu and i_ldw. As described above, in the power conversion device 1, the estimated load currents i_ldu and i_ldw are added to the current control loop as disturbance components, so that the responsiveness of the current control can be improved.

Further, in the power converter 1, the load currents i_ldu and i_ldw are obtained by estimating the currents flowing through the capacitive elements 25U and 25W. can be made smaller.

[effect]
As described above, in the present embodiment, one of the pair of switching elements SW1 and SW2 and the pair of switching elements SW3 and SW4 can be selectively turned off. Therefore, it is possible to properly supply power and stop the power supply.

In the present embodiment, the current command value i_u* is generated based on the voltage command value e_uo*, the voltage e_uo, and the load current i_ldu, and the current command value i_u* is generated based on the voltage command value e_wo*, the voltage e_wo, and the load current i_ldw. to generate the value i_w*. A DM duty ratio command value d_dm* is generated based on the difference between the current command value i_u* and the current command value i_w*, and a CM duty ratio command value is generated based on the sum of the current command value i_u* and the current command value i_w*. I made it to generate the value d_cm*. Then, based on the DM duty ratio command value d_dm* and the CM duty ratio command value d_cm*, the operation of the switching element is controlled. As a result, the control mode can be switched without interruption.

In the present embodiment, when stopping the power supply to the load Z1, the current command value i_u* is set to a predetermined command value that prevents the current from flowing, and when stopping the power supply to the load Z2, Since the current command value i_w* is set to a predetermined command value that prevents the current from flowing, the control mode can be switched without interruption.

[Modification 1]
In the above embodiment, the voltage command value generator 41 generates the voltage command values e_uo* and e_wo* based on the control signals Sgbu and Sgbw using the fifth and sixth equations of the equation EQ7. did. Then, for example, when an overvoltage of the voltage e_uo or an overcurrent of the current i_u is detected, by setting the voltage command value e_uo* to "0", the current command value i_u* is set to "0" (predetermined command value). For example, when an overvoltage of the voltage e_wo or an overcurrent of the current i_w is detected, by setting the voltage command value e_wo* to "0", the current command value i_w* is set to "0" (predetermined command value). However, it is not limited to this. For example, based on the control signals Sgbu and Sgbw, the current command value i_u* and the current command value i_w* may be set to "0" (predetermined command values) using another method. In the following, this modified example will be described in detail with several examples.

FIG. 13 shows a configuration example of a duty ratio generation section 40A in a control section 30A according to this modification. The duty ratio generator 40A has a voltage command value generator 41A and multipliers 45A and 46A.

The voltage command value generator 41A is configured to generate voltage command values e_uo* and e_wo* by using the following equation EQ12.

The multiplier 45A is configured to multiply the output value of the U-phase voltage controller 45 and the control signal Sgbu to generate the current command value i_u*. The multiplier 46A is configured to generate a current command value i_w* by multiplying the output value of the W-phase voltage controller 46 and the control signal Sgbw.

In the control unit 30A, the power supply control unit 31 sets the control signal Sgbu to "0", for example, when an overvoltage of the voltage e_uo or an overcurrent of the current i_u is detected. The multiplier 45A can set the current command value i_u* to "0" based on this control signal Sgbu. Similarly, the power supply control unit 31 sets the control signal Sgbw to "0" (predetermined command value), for example, when an overvoltage of the voltage e_wo or an overcurrent of the current i_w is detected. The multiplier 46A can set the current command value i_w* to "0" (predetermined command value) based on this control signal Sgbw.

FIG. 14 shows a configuration example of a duty ratio generation section 40B in another control section 30B according to this modification. The duty ratio generator 40B has a voltage command value generator 41A, a U-phase voltage controller 45B, and a W-phase voltage controller 46B.

When the control signal Ssbu is "1", the U-phase voltage control unit 45B controls the voltage command value e_uo*, the voltage e_uo, and the load current i_ldu similarly to the U-phase voltage control unit 45 according to the above embodiment. Based on this, the current command value i_u* is generated by using the third expression of the expression EQ7. Further, the U-phase voltage control unit 45B sets the current command value i_u* to "0" when the control signal Ssbu is "0".

When the control signal Ssbw is "1", the W-phase voltage control unit 46B controls the voltage command value e_wo*, the voltage e_wo, and the load current i_ldw similarly to the W-phase voltage control unit 46 according to the above embodiment. Based on this, it is configured to generate the current command value i_w* by using the fourth expression of the expression EQ7. Further, the W-phase voltage control section 46B sets the current command value i_w* to "0" when the control signal Ssbw is "0".

In the control unit 30B, the power supply control unit 31 sets the control signal Sgbu to "0", for example, when an overvoltage of the voltage e_uo or an overcurrent of the current i_u is detected. The U-phase voltage control unit 45B can set the current command value i_u* to "0" (predetermined command value) based on this control signal Sgbu. Similarly, the power supply control unit 31 sets the control signal Sgbw to "0", for example, when an overvoltage of the voltage e_wo or an overcurrent of the current i_w is detected. The W-phase voltage control unit 46B can set the current command value i_w* to "0" (predetermined command value) based on this control signal Sgbw.

Although the predetermined command value is set to "0" in this example, it is not limited to this, and may be set to a sufficiently small value. In other words, the predetermined command value may be any value as long as it is a command value that allows almost no current to flow.

[Modification 2]
In the above embodiment, for example, the control mode M is switched between the single-phase three-wire output mode MB and the single-phase two-wire output (WO) mode MD at arbitrary timing unrelated to the zero cross timing. However, it is not limited to this. Alternatively, for example, when switching the control mode M from the single-phase three-wire output mode MB to the single-phase two-wire output (WO) mode MD, the control mode M is switched at an arbitrary timing. When switching the mode M from the single-phase two-wire output (WO) mode MD to the single-phase three-wire output mode MB, for example, the control mode M is switched at the zero cross timing of the voltages e_uo and e_wo and the currents i_u and i_w. may Similarly, for example, when switching the control mode M from the single-phase three-wire output mode MB to the single-phase two-wire output (UO) mode MC, the control mode M is switched at an arbitrary timing. is switched from the single-phase two-wire output (UO) mode MC to the single-phase three-wire output mode MB, for example, even if the control mode M is switched at the zero cross timing of the voltages e_uo and e_wo and the currents i_u and i_w good.

[Modification 3]
In the above embodiment, the current detection unit 23U for detecting the current i_u is provided on the path from the node N1 to the output terminal T21, and the current detection unit 23W for detecting the current i_w is provided on the path from the node N2 to the output terminal T22. was provided, but is not limited to this. For example, a current detection unit 23U for detecting the current i_u may be provided on the path from the node N1 to the output terminal T21, and a current detection unit 23O for detecting the current i_o may be provided on the path from the node N3 to the output terminal T23. good. In this case, the current i_w can be obtained based on the current i_u and the current i_o by using the following equation EQ13. Similarly, for example, a current detection unit 23W for detecting the current i_w is provided on the path from the node N2 to the output terminal T22, and a current detection unit 23O for detecting the current i_o is provided on the path from the node N3 to the output terminal T23. may be provided. Also in this case, the current i_u can be obtained based on the current i_w and the current i_o by using this equation EQ13.

Similarly, in the above embodiment, the voltage detection unit 26U that detects the voltage e_uo and the voltage detection unit 26W that detects the voltage e_wo are provided, but the present invention is not limited to this. For example, a voltage detection unit 26U that detects voltage e_uo and a voltage detection unit that detects voltage e_uw may be provided. In this case, the voltage e_wo can be obtained based on the voltages e_uo and e_uw by using the following equation EQ14. Similarly, for example, a voltage detection unit 26W that detects the voltage e_wo and a voltage detection unit that detects the voltage e_uw may be provided. Also in this case, the voltage e_uo can be obtained based on the voltage e_wo and the voltage e_uw by using this equation EQ14.

[Modification 4]
In the above-described embodiment, the power conversion device 1 is configured to perform self-sustained operation, but is not limited to this, and may be configured to be able to perform grid-connected operation as well. In the following, this modified example will be described in detail by citing several examples.

FIG. 15 shows a configuration example of a power conversion device 1C according to this modification. The power converter 1C is a grid-connected power converter having a self-sustaining function, and is configured to be able to selectively perform grid-connected operation and self-sustained operation. The power converter 1C has terminals T31 and T32, input terminals T41 to T43, and output terminals T21 to T23. A battery BT is connected to the terminals T31 and T32. The input terminals T41, T42, T43 are connected to the power supply device 100. FIG. The power supply device 100 is a three-phase 200V system power supply.

The power conversion device 1C includes a bidirectional DC/DC converter 65, current detection units 23U and 23W, a low-pass filter 69, voltage detection units 26UV and 26VW, switches 27U, 27W and 27O, and switches 67U, 67W and 67V. , and a control unit 70 .

In this example, the switching elements SW1-SW6 operate as a bidirectional DC/AC inverter 66. FIG.

The bidirectional DC/DC converter 65 is configured to perform bidirectional power conversion, stepping up a DC voltage or stepping down a DC voltage. Bidirectional DC/DC converter 65 is connected to battery BT via terminals T31 and T32, and to bidirectional DC/AC inverter 66 via voltage line L1 and reference voltage line L2. The bidirectional DC/DC converter 65 converts the battery BT based on the voltage (DC bus voltage Vdc) between the voltage line L1 and the reference voltage line L2, for example, when the power converter 1C performs grid-interconnected operation. is charged and discharged. Further, when the power conversion device 1C performs self-sustained operation, the bidirectional DC/DC converter 65 generates a DC bus voltage Vdc based on the battery voltage Vbt of the battery BT, and the DC bus voltage Vdc is set at a predetermined value. Voltage constant control is performed so that the voltage is maintained.

Current detection unit 23U is provided on a path from node N1 to input terminal T41 and output terminal T21, and configured to detect current i_u flowing from node N1 toward low-pass filter 69. FIG. Current detection unit 23W is provided on a path from node N2 to input terminal T42 and output terminal T22, and configured to detect current i_w flowing from node N2 toward low-pass filter 69. FIG.

The low-pass filter 69 has AC reactors 24U, 24V, 24W and capacitive elements 25UV, 25VW, 25UW.

One end of AC reactor 24U is connected to the other end of current detector 23U, and the other end is connected to U-phase voltage line UL. One end of the AC reactor 24W is connected to the other end of the current detector 23W, and the other end is connected to the W-phase voltage line WL. AC reactor 24V has one end connected to node N3 and the other end connected to V-phase voltage line VL. Although not shown, each of AC reactors 24U, 24W, 24V has an inductance and an internal resistance value, as in the above embodiment.

One end of the capacitive element 25UV is connected to the U-phase voltage line UL, and the other end is connected to the V-phase voltage line VL. One end of the capacitive element 25VW is connected to the V-phase voltage line VL, and the other end is connected to the W-phase voltage line WL. Capacitive element 25UW has one end connected to U-phase voltage line UL and the other end connected to W-phase voltage line WL. Although not shown, each of capacitive elements 25UV, 25VW, and 25UW has a capacitance and an internal resistance value as in the above embodiment.

The voltage detection unit 26UV is configured to detect the voltage on the U-phase voltage line UL based on the voltage on the V-phase voltage line VL as the voltage e_uv. The voltage detection unit 26VW is configured to detect the voltage on the V-phase voltage line VL based on the voltage on the W-phase voltage line WL as the voltage e_vw.

Switch 27U is configured to connect U-phase voltage line UL to load device LOAD when turned on. The switch 27W is configured to connect the W-phase voltage line WL to the load device LOAD when turned on. The switch 27O is configured to connect the V-phase voltage line VL to the load device LOAD by being turned on.

Switch 67U is configured to connect U-phase voltage line UL to power supply device 100 when turned on. One end of the switch 67U is connected to the U-phase voltage line UL, and the other end is connected to the input terminal T41. The switch 67U is turned on and off based on the switch control signal Su.

Switch 67W is configured to connect W-phase voltage line WL to power supply device 100 when turned on. One end of the switch 67W is connected to the W-phase voltage line WL, and the other end is connected to the input terminal T42. The switch 67W is turned on and off based on the switch control signal Sw.

Switch 67V is configured to connect V-phase voltage line VL to power supply device 100 when turned on. One end of the switch 67V is connected to the V-phase voltage line VL, and the other end is connected to the input terminal T43. The switch 67V is turned on and off based on the switch control signal Sv.

When the power converter 1C performs grid-connected operation, for example, the control unit 70 turns on the switches S67U, 67W, and 67V via the switch control signals Su, Sw, and Sv, and outputs the switch control signal Sstdu , Sstdw and Sstdo to turn off the switches 27U, 27W and 27O. Control unit 70 controls operations of bidirectional DC/AC inverter 66 and bidirectional DC/DC converter 65 . Bidirectional DC/AC inverter 66 generates DC bus voltage Vdc based on the AC voltage supplied from power supply device 100 based on an instruction from control unit 70, and this DC bus voltage Vdc reaches a predetermined voltage. Constant voltage control is performed so that Bidirectional DC/DC converter 65 performs charge/discharge power control for battery BT based on this DC bus voltage Vdc based on an instruction from control unit 70 .

Further, when the power conversion device 1C performs the self-sustained operation, the control unit 70 turns on the switches 27U, 27W, and 27O via the switch control signals Sstdu, Sstdw, and Sstdo, for example, and also turns on the switch control signal Su. , Sw and Sv to turn off the switches S67U, 67W and 67V. Control unit 70 controls operations of bidirectional DC/DC converter 65 and bidirectional DC/AC inverter 66 . The bidirectional DC/DC converter 65 generates a DC bus voltage Vdc based on the battery voltage Vbt of the battery BT, and performs voltage constant control so that the DC bus voltage Vdc becomes a predetermined voltage. The bidirectional DC/AC inverter 66 generates an AC output voltage to be supplied to the load device LOAD on the basis of the DC bus voltage Vdc, and maintains a constant voltage amplitude so that the voltage amplitude of the AC output voltage has a predetermined amplitude. control. The control unit 70 performs the same operation as the control unit 30 according to the above-described embodiment during self-sustained operation. As shown in the following equation EQ15, the voltage e_uo can be obtained based on the voltage e_uv detected by the voltage detector 26UV, and the voltage e_vw can be obtained based on the voltage e_vw detected by the voltage detector 26VW.

Here, the input terminal T41 corresponds to a specific example of the "first input terminal" in the present disclosure, and the input terminal T42 corresponds to a specific example of the "second input terminal" in the present disclosure. The controller 70 corresponds to a specific example of the "controller" in the present disclosure. The switch 67U corresponds to a specific example of the "fourth switch" in the present disclosure, and the switch 67W corresponds to a specific example of the "fifth switch" in the present disclosure.

FIG. 16 shows a configuration example of a power conversion device 1D according to another modification. The power conversion device 1D has input terminals T41 and T42. The input terminals T41 and T42 are connected to the power supply device 110 . The power supply device 110 is a single-phase 200V system power supply.

The power conversion device 1D includes current detection units 23U and 23W, a low-pass filter 29, voltage detection units 26W and 26UW, switches 27U, 27W and 27O, switches 67U and 67W, and a control unit 90.

The voltage detection unit 26W is configured to detect the voltage on the W-phase voltage line WL with reference to the voltage on the neutral line OL as the voltage e_wo. The voltage detection unit 26UW is configured to detect the voltage on the U-phase voltage line UL based on the voltage on the W-phase voltage line WL as the voltage e_uw.

Switch 27U is configured to connect U-phase voltage line UL to load device LOAD when turned on. The switch 27W is configured to connect the W-phase voltage line WL to the load device LOAD when turned on. The switch 27O is configured to connect the neutral line OL to the load device LOAD by turning on.

Switch 67U is configured to connect U-phase voltage line UL to power supply device 110 when turned on. Switch 67W is configured to connect W-phase voltage line WL to power supply device 110 when turned on.

When the power converter 1D performs grid-connected operation, for example, the control unit 90 turns on the switches S67U and 67W via the switch control signals Su and Sw, and turns on the switch control signals Sstdu, Sstdw and Sstdo. to turn off the switches 27U, 27W, and 27O. Also, the control unit 90 turns off the switching elements SW5 and SW6 via the gate signals S5 and S6. Control unit 90 controls operations of bidirectional DC/AC inverter 66 and bidirectional DC/DC converter 65 . Bidirectional DC/AC inverter 66 generates DC bus voltage Vdc based on the AC voltage supplied from power supply device 110 based on an instruction from control unit 90, and this DC bus voltage Vdc reaches a predetermined voltage. Constant voltage control is performed so that Bidirectional DC/DC converter 65 performs charge/discharge power control for battery BT based on this DC bus voltage Vdc based on instructions from control unit 90 .

Further, when the power conversion device 1D performs the self-sustained operation, the control unit 90 turns on the switches 27U, 27W, and 27O via the switch control signals Sstdu, Sstdw, and Sstdo, for example, and turns on the switch control signal Su. , Sw to turn off the switches S67U and 67W. Control unit 90 controls operations of bidirectional DC/DC converter 65 and bidirectional DC/AC inverter 66 . The bidirectional DC/DC converter 65 generates a DC bus voltage Vdc based on the battery voltage Vbt of the battery BT, and performs voltage constant control so that the DC bus voltage Vdc becomes a predetermined voltage. The bidirectional DC/AC inverter 66 generates an AC output voltage to be supplied to the load device LOAD on the basis of the DC bus voltage Vdc, and maintains a constant voltage amplitude so that the voltage amplitude of the AC output voltage has a predetermined amplitude. control. The control unit 90 performs the same operation as the control unit 30 according to the above-described embodiment during self-sustained operation. As shown in equation EQ14, voltage e_wo can be obtained based on voltage e_wo detected by voltage detector 26W and voltage e_uw detected by voltage detector 26UW.

Although the present invention has been described above with reference to the embodiments and modifications, the present invention is not limited to these embodiments and the like, and various modifications are possible.

For example, in the above embodiment, the load currents i_ldu and i_ldw are obtained by estimating the currents flowing through the capacitive elements 25U and 25W. A current detection unit for detecting and a current detection unit for detecting the load current i_ldw may be provided.

1, 1A, 1B, 1C, 1D... power converter, 21... voltage detector, 22... capacitive element, 23U, 23W... current detector, 24U, 24W, 24O, 24V... AC reactor, 25U, 25W... capacitive element , 26U, 26W, 26UV, 26UW, 26VW... voltage detection section, 27U, 27W, 27O... switch, 29... low-pass filter, 30, 70... control section, 31... power supply control section, 40, 40A, 40B... duty ratio Generating unit 41, 41A... Voltage command value generating unit 42... Current estimating unit 43, 44... Subtracting unit 45, 45B... U phase voltage control unit 45A... Multiplication unit 46, 46B... W phase voltage control unit , 46A multiplication unit 47 subtraction unit 48 addition unit 51, 52 subtraction unit 53, 54 addition unit 55 DM current control unit 56 CM current control unit 60 drive unit 61 Multiplication section 62U, 62W, 62O Multiplication section 63U, 63W, 63O Gate signal generation section 65 Bidirectional DC/DC converter 66 Bidirectional DC/AC inverter 67U, 67W, 67V Switch, 69 Low-pass filter, BT battery, CTL control signal, Cu, Cw capacitance, d_cm* CM duty ratio command value, d_dm* DM duty ratio command value, d_u*, d_w*, d_o* duty ratio command Value, Euorms, Eworms... Execution value, e_cm... CM voltage, e_dm... DM voltage, e_u, e_w, e_o, e_uo, e_uw, e_wo... Voltage, e_uo*, e_wo*... Voltage command value, 100, 110... Power supply, i_cm... CM current, i_cu, i_cw, i_u, i_w, i_o... current, i_u*, i_w*... current command value, i_dm... DM current, i_ldu, Ildw... load current, LOAD... load device, Lu, Lw, Lo... Inductance L1...Voltage line L2...Reference voltage line MA...Output stop mode MB...Single-phase three-wire output mode MC...Single-phase two-wire output (UO) mode MD...Single-phase two-wire output ( WO) mode N1 to N3 nodes OL neutral wire PWMSW control signals Rcu, Rcw, Ru, Rw, Ro internal resistance values SEL control signals Sgbu, Sgbw, Sgbo control signals , Sstdu, Sstdw, Sstdo... switch control signals, SW0... switches, SW1 to SW6... switching elements, S1 to S6... gate signals, T0 to T2... terminals, T11, T12... input terminals, T21 to T23... output terminals, T31 , T32... end child, T41 to T43... input terminal, UL... U-phase voltage line, Vbt... battery voltage, Vdc... DC bus voltage, v_u, v_w, v_o, v_uo, v_wo... voltage, WL... W-phase voltage line, Z1 to Z3... load.

Claims (10)

A first switching element provided on a path between the first voltage line and the first node, and a second switching element provided on a path between the second voltage line and the first node. a first switching element pair including
a third switching element provided in a path between the first voltage line and the second node, and a fourth switching element provided in a path between the second voltage line and the second node a second pair of switching elements including
a fifth switching element provided on the path between the first voltage line and the third node, and a sixth switching element provided on the path between the second voltage line and the third node a third switching element pair including
a first output terminal, a second output terminal, and a third output terminal;
a first path between the first node and the first output terminal, a second path between the second node and the second output terminal, and a third node and the a third path from the first node, the second node, and the third node to the first output terminal, the second output terminal, and the third output terminal; a first circuit and a second circuit arranged in this order toward a third output terminal, wherein the first circuit is connected to the first path, the second path, and the third path; a reactor provided in each of two or more paths including the third path among the paths, wherein the second circuit is provided between the first path and the third path a low-pass filter including a first capacitive element and a second capacitive element provided between the second path and the third path;
a control unit capable of controlling switching operations of the first switching element pair, the second switching element pair, and the third switching element pair;
The control unit
generating a first voltage command value that is a command value of a first voltage that is a differential voltage between the output voltage of the low-pass filter in the first path and the output voltage of the low-pass filter in the third path; ,
a second voltage command value that is a command value of a second voltage that is a differential voltage between the output voltage of the low-pass filter in the second path and the output voltage of the low-pass filter in the third path; ,
A first voltage command value, which is a command value of a first current flowing through the first path, based on the first voltage command value, the first voltage, and a first load current flowing through the first output terminal. It is possible to generate a current command value of
A second voltage command value, which is a command value of a second current flowing through the second path, based on the second voltage command value, the second voltage, and a second load current flowing through the second output terminal. It is possible to generate a current command value of
A power converter capable of controlling the switching operation based on the first current command value and the second current command value. The control unit can control the switching operation based on the sum of the first current command value and the second current command value and the difference between the first current command value and the second current command value. The power converter according to claim 1. The control unit
Based on the difference between the first current command value and the second current command value, the difference between the first current and the second current, and the difference between the first voltage and the second voltage , capable of generating a first duty ratio command value,
Based on the sum of the first current command value and the second current command value, the sum of the first current and the second current, and the sum of the first voltage and the second voltage , capable of generating a second duty ratio command value,
The power converter according to claim 2, wherein the switching operation can be controlled based on the first duty ratio command value and the second duty ratio command value. The control unit
capable of switching control modes between a plurality of control modes including a first control mode, a second control mode, and a third control mode;
In the first control mode, the operations of the first switching element pair and the second switching element pair are controlled based on the first duty ratio command value, and the second duty ratio command value based on the value, it is possible to control the operation of the third switching element pair;
In the second control mode, based on the first duty ratio command value, the operations of the first switching element pair and the third switching element pair are controlled, and the operation of the second switching element pair is controlled. It is possible to stop the operation of
In the third control mode, based on the first duty ratio command value, the operations of the second switching element pair and the third switching element pair are controlled, and the operation of the first switching element pair is controlled. The power conversion device according to claim 3, wherein the operation of is stopped. The control unit
capable of switching control modes between a plurality of control modes including a first control mode, a second control mode, and a third control mode;
In the second control mode, the second current command value can be set to a predetermined command value,
The power converter according to any one of claims 1 to 3, wherein the first current command value can be set to the predetermined command value in the third control mode. The control unit switches the control mode based on one or more of the first voltage, the second voltage, the first current, the second current, and an external control signal. 6. The power converter according to claim 4 or 5, capable of a first switch provided between the low-pass filter and the first output terminal in the first path;
a second switch provided between the low-pass filter and the second output terminal in the second path;
a third switch provided between the low-pass filter and the third output terminal in the third path,
The control unit
In the first control mode, it is possible to turn on the first switch, the second switch, and the third switch,
In the second control mode, it is possible to turn on the first switch and the third switch and turn off the second switch,
7. In the third control mode, the second switch and the third switch can be turned on, and the first switch can be turned off. The power conversion device according to any one of the items. a first input terminal connected to the first path;
a second input terminal connected to the second path;
a fourth switch provided between the low-pass filter and the first input terminal in the first path;
a fifth switch provided between the low-pass filter and the second input terminal in the second path,
The plurality of control modes include a fourth control mode in addition to the first control mode, the second control mode, and the third control mode,
The control unit
In the first control mode, the second control mode, and the third control mode, the fourth switch and the fifth switch can be turned off,
In the fourth control mode, the first switch, the second switch, and the third switch are turned off, and the fourth switch and the fifth switch are turned on. 8. The voltage difference between the voltage on the first voltage line and the voltage on the second voltage line can be controlled by controlling the switching operation. power converter. A power converter according to any one of claims 1 to 7;
a DC power supply connected to the first voltage line and the second voltage line of the power converter,
A power supply system, wherein the power conversion device is capable of generating AC power based on the DC power supplied from the DC power supply. A power conversion device according to any one of claims 1 to 8;
a DC power supply connected to the first voltage line and the second voltage line of the power converter,
The power converter,
a first input terminal connected to the first path;
a second input terminal connected to the second path;
a first operation capable of generating AC power based on the DC power supplied from the DC power supply;
a second operation capable of generating DC power to be supplied to the DC power supply based on AC power supplied from a power supply connected to the first input terminal and the second input terminal; A power conversion device control system capable of

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