JP2023157416A - Power conditioner device and power supply system - Google Patents

Abstract

To provide a power conditioner device capable of protecting a regenerative diode of an ARCP circuit from overvoltage.SOLUTION: Disclosed is a power conditioner device 10 having independent output ends T2 (U), T2 (O), T2 (W) of a single-phase three wire system which includes: an invertor circuit 13; a bidirectional DC/DC converter circuit 14; and a control part 15. The bidirectional DC/DC converter circuit 14 includes a main circuit and an ARCP circuit. When the overvoltage exceeding a predetermined threshold is applied to the independent output ends T2 (U), T2 (O), and T2 (W), the control part 15 performs a stop process to stop the operation of the ARCP circuit so as to prevent a voltage value of the voltage applied to a regeneration diode of the ARCP circuit from exceeding a predetermined permissible voltage value.SELECTED DRAWING: Figure 2

Description

The present invention relates to a power conditioner device and a power supply system including the power conditioner device.

In general, power supply systems are known that include a first power conditioner device that performs charging and discharging operations on a storage battery, and a second power conditioner device that controls power generated by a solar panel. There is.

The first power conditioner device has a single-phase three-wire independent output terminal, and further includes an inverter circuit and a bidirectional DC/DC converter circuit with an ARCP (Auxiliary Resonant Commutated Pole) circuit. It is known to have the following. The circuit configuration of the ARCP circuit is as described in Patent Document 1, for example.

If the independent output terminal of the first power conditioner device is single-phase two-wire type, the second power conditioner device can only be connected upstream of the first power conditioner device, but as mentioned above, the independent output terminal is single-phase. In the case of a three-wire system, the second power conditioner device can be connected to the independent output end of the first power conditioner device.

In a power supply system in which the second power conditioner device is connected to the independent output terminal of the first power conditioner device, the second power conditioner device is connected to the grid power of the power grid when the power grid is in a energized state. On the other hand, when the power system is in a power outage state, a grid connection operation (pseudo grid connection operation) is performed for the independent output power of the first power conditioner device. As a result, even during a power outage, the power generated by the solar panel can be used to charge the storage battery, and the generated power can be used together with the discharged power of the storage battery to load the load connected to the independent output terminal (e.g. home appliances).

However, if the generated power output from the second power conditioner device is larger than the power consumption of the load or the charging power that can be charged to the storage battery, the second power conditioner Since the device attempts to continue supplying the generated power, the output voltage of the second power conditioner device continues to rise. As a result, an overvoltage is applied to the independent output terminal of the first power conditioner device.

In order to stop the power supply from the second power conditioner, the first power conditioner changes the frequency of the voltage applied at the independent output terminal, and detects that an abnormality has occurred in the second power conditioner. Let it be detected. However, it takes time for the second power conditioner device to stop power supply after detecting an abnormality, and overvoltage continues to be applied to the independent output terminal of the first power conditioner device for a certain period of time.

The ARCP circuit of the bidirectional DC/DC converter circuit of the first power conditioner device includes a resonance switch, a resonance reactor, a resonance capacitor, a regeneration transformer, and a regeneration diode. In a regenerative transformer, the number of turns of the regenerative winding is usually larger than the number of turns of the main winding, for example, the number of turns of the regenerative winding: the number of turns of the main winding = 2:1. . In this case, the voltage generated in the regenerative winding is twice the voltage applied to the main winding.

Therefore, the voltage applied to the regenerative diode via the regenerative winding is twice the voltage applied to the main winding + the overshoot voltage during switching of the resonance switch, which is a very high voltage. . If an overvoltage is applied to the independent output terminal in such a state, the voltage applied to the regeneration diode becomes even higher. A problem arises in that it is not possible to use a diode.

JP 2021-19396 Publication

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power conditioner device and a power supply system that can protect a regeneration diode of an ARCP circuit from overvoltage. .

In order to solve the above problems, a power conditioner device according to the present invention includes:
A power conditioner device having a single-phase three-wire independent output end,
an inverter circuit connected to the independent output terminal;
a DC/DC converter circuit connected to the inverter circuit;
a control unit that controls the inverter circuit and the DC/DC converter circuit;
Equipped with
The DC/DC converter circuit includes:
A main circuit including a main switch,
Equipped with an ARCP circuit including a resonant switch, a regenerative transformer, and a regenerative diode,
The control unit includes:
When an overvoltage exceeding a predetermined threshold is applied to the independent output terminal, a stop process is performed to stop the operation of the ARCP circuit, and the voltage value of the voltage applied to the regeneration diode via the regeneration transformer is It is characterized by ensuring that the voltage does not exceed a predetermined permissible voltage value.

According to this configuration, when an overvoltage exceeding a predetermined threshold is applied to the independent output terminal, a stop process is performed to stop the operation of the ARCP circuit, and the voltage value of the voltage applied to the regeneration diode is reduced to a predetermined allowable voltage. Since the value is not exceeded, the regenerative diode can be protected from overvoltage.

In the power conditioner device,
The DC/DC converter circuit includes:
connected to the inverter circuit via a capacitor,
The inverter circuit is
When an overvoltage is applied to the independent output terminal, an operation is performed to supply voltage to the capacitor in order to absorb the overvoltage,
The control unit includes:
It can be configured to determine whether or not to perform the stop processing based on the voltage across the capacitor.

In the power conditioner device,
The control unit includes:
When performing the stop processing, the resonance switch may be continuously turned off, while the main switch may be turned on/off by PWM control.

In order to solve the above problems, the power supply system according to the present invention includes:
storage battery and
a first power conditioner device having a single-phase three-wire independent output terminal having the characteristics of the power conditioner device;
a second power conditioner device connected to the independent output terminal;
including;
The first power conditioner device is characterized in that it performs charging and discharging operations for the storage battery.

In the power supply system,
The second power conditioner device includes:
Performing a grid-connection operation on the AC power output from the independent output terminal,
The first power conditioner device includes:
When an overvoltage exceeding a predetermined threshold is applied to the independent output terminal, a grid-linked operation stop process for stopping the grid-linked operation of the second power conditioner device can be configured.

According to the present invention, it is possible to provide a power conditioner device and a power supply system that can protect a regeneration diode of an ARCP circuit from overvoltage.

FIG. 1 is a block diagram of a power supply system according to the present invention. FIG. 1 is a block diagram of a power conditioner device according to the present invention. FIG. 2 is a circuit diagram of an inverter circuit of a power conditioner device according to the present invention. FIG. 2 is a circuit diagram of a bidirectional DC/DC converter circuit of a power conditioner device according to the present invention. FIG. 5 is various waveform diagrams during operation of the ARCP circuit according to the present invention, in which (A) is the gate voltage of switching elements Q8 and Q10, (B) is the reactor current and resonance current, and (C) is the drain current of switching element Q8. and a waveform diagram of the drain-source voltage.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a power conditioner device and a power supply system according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a power supply system 1 according to an embodiment of the present invention. The power supply system 1 includes a first power conditioner device 10 (corresponding to the "power conditioner device" of the present invention), a second power conditioner device 20, a changeover switch SW, a storage battery BT, and a solar panel PV. including.

The first power conditioner device 10 has a single-phase three-wire first terminal T1, a single-phase three-wire second terminal (independent output terminal) T2, and a third terminal T3 connected to the storage battery BT. Be prepared. The first terminal T1 is connected to the power system 2 and also to a load 3 (for example, a home appliance) via a changeover switch SW. The second terminal (self-supporting output terminal) T2 is connected to the load 3 via the changeover switch SW.

The changeover switch SW is configured with a relay, for example, and connects the first terminal T1 to the load 3 when the power system 2 is energized (hereinafter referred to as energized state), and connects the first terminal T1 to the load 3 when the power system 2 is in a power outage state. (hereinafter referred to as a power outage), the second terminal (independent output terminal) T2 is connected to the load 3. That is, the first power conditioner device 10 can supply a voltage of AC 200 [V] to the load 3 even during a power outage.

The second power conditioner device 20 includes a fourth terminal T4 connected to the load 3 and a fifth terminal T5 connected to the solar panel PV. The fourth terminal T4 is connected to the power system 2 when energized, and is connected to the second terminal (independent output terminal) T2 of the first power conditioner device 10 during a power outage. The second power conditioner device 20 performs a grid-connected operation for the grid power of the power system 2 when energized, and performs a grid-connected operation (pseudo-grid-connected operation) for the independent output power of the first power conditioner device 10 during a power outage. action).

FIG. 2 shows a block diagram of the first power conditioner device 10. The first power conditioner device 10 includes a relay circuit 11, a noise filter 12, an inverter circuit 13, a bidirectional DC/DC converter circuit 14 (corresponding to the "DC/DC converter circuit" of the present invention), and a control section. 15 and various detection circuits (not shown).

Relay circuit 11 includes relays S1 to S9 that are turned on and off under the control of control unit 15. Relays S1 to S3 are installed in each wiring that connects first terminals T1 (U), T1 (O), and T1 (W) of U phase, O phase, and W phase, respectively, and noise filter 12. Relays S4 to S6 have first terminals T1(U), T1(O), T1(W) and independent output terminals T2(U), T2(O), T2(W) of U phase, O phase, and W phase, respectively. ) is interposed in each wiring that connects the Relays S7 to S9 are interposed in each wiring connecting independent output terminals T2 (U), T2 (O), T2 (W) and noise filter 12, respectively.

Noise filter 12 is provided between relay circuit 11 and inverter circuit 13. The noise filter 12 is composed of, for example, a capacitor and a coil, and cuts noise propagated through the wiring connecting the relay circuit 11 and the inverter circuit 13.

Inverter circuit 13 connects first terminals T1 (U), T1 (O), T1 (W) and independent output terminals T2 (U), T2 (O), T2 (W) through noise filter 12 and relay circuit 11. ). As shown in FIG. 3, the inverter circuit 13 includes a filter section made up of capacitors C1 to C3 and coils L1 to L3, and three arm sections made up of switching elements Q1 to Q6 and diodes D1 to D6. . The switching elements Q1 to Q6 are turned on/off under the control of the control section 15.

For example, MOSFETs (metal oxide semiconductor field effect transistors) are used as the switching elements Q1 to Q6. The diodes D1 to D6 are connected in parallel in opposite directions to the current paths (between drains and sources) of the switching elements Q1 to Q6. The diodes D1 to D6 may be parasitic diodes of the switching elements Q1 to Q6, external diodes independent of the switching elements Q1 to Q6, or both.

Bidirectional DC/DC converter circuit 14 is connected to inverter circuit 13 . As shown in FIG. 4, the bidirectional DC/DC converter circuit 14 includes a main circuit 14A, an ARCP circuit 14B, and input/output terminals Ta to Td. The input/output terminals Ta, Tb are connected to the inverter circuit 13, and the input/output terminals Tc, Td are connected to the third terminals T3(+), T3(-), that is, the storage battery BT.

The main circuit 14A includes switching elements Q7, Q8 and diodes D7, D8 that constitute a main switch, a DC reactor L4, and capacitors C4, C5. The ARCP circuit 14B includes switching elements Q9, Q10 and diodes D9, D10 constituting a resonance switch, a resonance reactor L5, resonance capacitors C6, C7, and a regeneration circuit including a main winding N1 and a regenerative winding N2. It includes a transformer TR1 and regeneration diodes D11 and D12.

For example, MOSFETs are used for the switching elements Q7 to Q10. The diodes D7-D10 are connected in parallel in the opposite direction to the current path (between the drain and source) of the switching elements Q7-Q10. The diodes D7-D10 may be parasitic diodes of the switching elements Q7-Q10, external diodes independent of the switching elements Q7-Q10, or both.

The switching elements Q7, Q8 are connected in series with each other, one end of the series-connected current path is connected to the input/output terminal Ta, and the other end is connected to the input/output terminals Tb, Td. A connection point X1 between switching element Q7 and switching element Q8 is connected to input/output terminal Tc via DC reactor L4. The capacitor C4 is connected between the input and output terminals Ta and Tb on the side closer to the input and output terminals Ta and Tb than the switching elements Q7 and Q8. The capacitor C5 is connected between the input and output ends Tc and Td on the side closer to the input and output ends Tc and Td than the DC reactor L4.

Switching elements Q9 and Q10 are provided between switching elements Q7 and Q8 and capacitor C4, are connected in series with each other, and are connected in parallel with switching elements Q7 and Q8. A connection point X2 between switching element Q9 and switching element Q10 is connected to connection point X1 via main winding N1 of regeneration transformer TR1 and resonance reactor L5. Resonant capacitor C6 is connected in parallel between the drain and source of switching element Q7, and resonant capacitor C7 is connected in parallel between the drain and source of switching element Q8.

One end and the other end of the regenerative winding N2 of the regenerative transformer TR1 are connected to the input/output terminal Ta via regenerative diodes D11 and D12, respectively. Moreover, the regenerative winding N2 has a center tap, and the center tap is connected to the input/output terminal Tb. In this embodiment, the turn ratio between the main winding N1 and the regenerative winding N2 is N1:N2=1:2. Furthermore, in this embodiment, relatively inexpensive general-purpose diodes (eg, 1200V diode) can be used as the regeneration diodes D11 and D12.

The control unit 15 includes a relay control circuit for controlling the relay circuit 11, each drive circuit of the switching elements Q1 to Q10 for turning on/off the switching elements Q1 to Q10, and for sending control signals to each drive circuit. control circuit. The control unit 15 may be composed of an analog circuit, a digital circuit using a microcontroller or the like, or a circuit that is a combination of an analog circuit and a digital circuit. .

Regarding the control of the inverter circuit 13, the control unit 15 converts the AC voltage input to the inverter circuit 13 via the noise filter 12 into a DC voltage, and outputs the AC/DC voltage to the bidirectional DC/DC converter circuit 14 side. A conversion operation and a DC/AC conversion operation of converting the DC voltage input from the bidirectional DC/DC converter circuit 14 into an AC voltage and outputting it to the noise filter 12 side are performed.

Regarding the control of the bidirectional DC/DC converter circuit 14, the control unit 15 controls the bidirectional DC/DC converter circuit 14 from the input/output terminals Tc, Td side (storage battery BT) to the input/output terminals Ta, Tb side (inverter circuit 13). side) and power conversion operation (step-down operation) from the input/output terminals Ta, Tb side (inverter circuit 13 side) to the input/output terminals Tc, Td side (storage battery BT). let The control unit 15 performs PWM control on the switching elements Q7 and Q8 of the main switch.

FIGS. 5A to 5C show various waveform diagrams during the boost operation and when the ARCP circuit 14B is in operation. 5(A) shows the gate voltage Vgs of switching elements Q8 and Q10, FIG. 5(B) shows the reactor current I L4 flowing through the DC reactor L4 and the resonant current I _L5 flowing through the resonance reactor _L5 , and FIG. 5(C) shows the switching 3 is a waveform diagram of drain current Id and drain-source voltage Vds of element Q8. FIG.

At time _t1 , when the control unit 15 turns on the switching element Q10, the current flowing through the diode D7 is commutated to the resonant reactor L5, and the resonant reactor L5 acts to extract the charge from the resonant capacitor C7. Therefore, the resonance reactor L5, the leakage inductance of the regeneration transformer TR1, and the resonance capacitor C7 resonate. As a result, a resonant current _IL5 flows through the resonant reactor L5, and the drain-source voltage Vds of the switching element Q8 decreases.

At time _t2 , when the control unit 15 turns on the switching element Q8 at the timing when the falling current waveform of the resonant current I _L5 intersects with the current waveform of the reactor current I _L4 , the switching element Q10 is turned on. The drain-source voltage Vds of the switching element Q8 becomes approximately 0 [V], and the drain current Id of the switching element Q10 rises from 0 [A]. As a result, zero voltage switching and zero current switching are realized, and switching loss when switching element Q8 is turned on is reduced.

When the charge extracted from the resonant capacitor C7 flows as a resonant current _IL5 to the main winding N1 of the regenerative transformer TR1, a voltage is induced in the regenerative winding N2 of the regenerative transformer TR1. The voltage induced in the regenerative winding N2 is regenerated to the capacitor C4 via the regenerative diodes D11 and D12.

After the resonance current I _L5 becomes 0 [A] at time _t3 , the control unit 15 turns off the switching element Q10 at time _t4 , and then turns off the switching element Q8 according to the duty of PWM control ( time _t5 ).

At time _t5 , when the control unit 15 turns off the switching element Q8, the current flowing through the switching element Q8 is commutated to the resonance capacitor C7, and the resonance capacitor C7 is charged. While the drain current Id of the switching element Q8 decreases relatively quickly, the drain-source voltage Vds of the switching element Q8 increases slowly, so the fall of the drain current Id and the rise of the drain-source voltage Vds overlap. Area decreases. As a result, zero voltage switching is achieved and switching loss when switching element Q8 is turned off is reduced.

In the bidirectional DC/DC converter circuit 14, the step-up operation and the step-down operation have the same operating principle, so the control section 15 during the step-down operation controls the switching element Q7 of the main switch and the resonance switch in the same manner as described above. The switching element Q9 is controlled.

Next, a description will be given of a stop process in which the control unit 15 stops the operation of the ARCP circuit 14B.

In the power supply system 1 according to the present embodiment, the generated power output from the fourth terminal T4 of the second power conditioner device 20 during a power outage in the power system 2 is the power consumed by the load 3 or the charging power that can charge the storage battery BT. If it is larger than , the output voltage of the second power conditioner device 20 increases because the second power conditioner device 20 tries to continue supplying the generated power even though there is nowhere for the surplus power to go. As a result, an overvoltage is applied to the independent output terminal T2 of the first power conditioner device 10.

When an overvoltage is applied to the independent output terminal T2 of the first power conditioner device 10, the inverter circuit 13 of the first power conditioner device 10 connects the capacitor C4 of the bidirectional DC/DC converter circuit 14 to absorb the overvoltage. performs the operation of supplying voltage to the As a result, the voltage across capacitor C4 increases.

The bidirectional DC/DC converter circuit 14 is provided with a voltage detection sensor (not shown) for detecting the voltage across the capacitor C4, and the voltage value detected by the voltage detection sensor is sent to the control unit 15.

The control unit 15 determines whether or not to perform the stop processing based on the voltage across the capacitor C4 (the voltage value detected by the voltage detection sensor), and determines the voltage value of the voltage applied to the regeneration diodes D11 and D12. The stop processing is executed so that the voltage does not exceed a predetermined allowable voltage value (for example, 1200 [V]).

For example, when the voltage across the capacitor C4 is 360 to 380 [V] during normal operation (when no overvoltage is applied to the independent output terminal T2), the control unit 15 determines that the voltage across the capacitor C4 is 400 [V]. When the voltage is reached, it is determined that an overvoltage exceeding a predetermined threshold value has been applied to the independent output terminal T2, and a stop process is executed.

During the stop processing, the control unit 15 continuously turns off the switching elements Q9 and Q10 of the resonance switch, and turns on/off the switching elements Q7 and Q8 of the main switch by PWM control. As a result, the bidirectional DC/DC converter circuit 14 stops the operation of the ARCP circuit 14B, and switches to a simple PWM-controlled bidirectional chopper operation.

When the operation of the ARCP circuit 14B is stopped, no voltage is applied to the regeneration diodes D11 and D12, so the regeneration diodes D11 and D12 can be protected from overvoltage. That is, in the first power conditioner device 10 and the power supply system 1 according to the present embodiment, relatively inexpensive general-purpose diodes (eg, 1200V diode) can be used as the regeneration diodes D11 and D12.

The control unit 15 may perform grid connection operation stop processing to stop the operation of the ARCP circuit 14B and to stop the grid connection operation (pseudo grid connection operation) of the second power conditioner device 20. The control unit 15 during the grid-connection operation stop processing changes the frequency of the voltage applied to the independent output terminal T2, etc., to detect that an abnormality has occurred in the second power conditioner device 20. Further, when the voltage across the capacitor C4 returns to the voltage during normal operation, the control unit 15 may restart the operation of the ARCP circuit 14B.

Note that the control unit 15 defines a period in which a resonant current is flowing in the ARCP circuit 14B as a period in which PWM control is not possible (for example, time t ₁ to t ₃ in FIG. 5), and a period in which resonant current is not flowing in a period in which PWM control is possible (for example, , time t ₃ to time t ₆ in FIG. 5), PWM control is performed by varying the duty of switching elements Q7 and Q8.

However, if the ON time of switching elements Q7 and Q8 becomes so short that the PWM control uncontrollable period cannot be secured (when the input/output voltage difference is small and the load is light) or the OFF time of switching elements Q7 and Q8 becomes so short that (When the input/output voltage difference is large and the load is heavy), switching loss will increase even if the ARCP circuit 14B is operated. Therefore, in the case of a light load or a heavy load as described above, the control unit 15 stops the operation of the ARCP circuit 14B and switches the operation of the bidirectional DC/DC converter circuit 14 to PWM-controlled bidirectional chopper operation. .

Although the embodiments of the power conditioner device and power supply system according to the present invention have been described above, the present invention is not limited to the above embodiments.

The power conditioner device according to the present invention is a power conditioner device having a single-phase three-wire independent output terminal, and includes an inverter circuit connected to the independent output terminal, and a DC/DC converter connected to the inverter circuit. circuit, and a control unit that controls an inverter circuit and a DC/DC converter circuit, and the DC/DC converter circuit includes an ARCP circuit including a main circuit including a main switch, a resonance switch, a regeneration transformer, and a regeneration diode. The controller includes a circuit, when an overvoltage exceeding a predetermined threshold is applied to the independent output terminal, performs a stop process to stop the operation of the ARCP circuit, and applies the overvoltage to the regeneration diode via the regeneration transformer. The configuration can be changed as appropriate as long as the voltage value of the voltage does not exceed a predetermined allowable voltage value.

For example, the control unit 15 in the above embodiment determines whether or not an overvoltage exceeding a predetermined threshold is applied to the independent output terminal T2 based on the voltage across the capacitor C4. It is also possible to directly detect the voltage and determine whether there is an overvoltage.

A switching element other than MOSFET (for example, IGBT) can be used as the switching element of the main switch and/or the resonance switch.

The power supply system according to the present invention includes a storage battery, a power conditioner device according to the present invention (first power conditioner device) having a single-phase three-wire independent output terminal, and a second power conditioner device connected to the independent output terminal. As long as the power conditioner device includes a power conditioner device and performs a charging operation and a discharging operation for a storage battery, the configuration can be changed as appropriate.

1 Power supply system 2 Power system 3 Load 10 First power conditioner device 11 Relay circuit 12 Noise filter 13 Inverter circuit 14 Bidirectional DC/DC converter circuit 14A Main circuit 14B ARCP circuit 15 Control unit 20 Second power conditioner device

Claims (5)

A power conditioner device having a single-phase three-wire independent output end,
an inverter circuit connected to the independent output terminal;
a DC/DC converter circuit connected to the inverter circuit;
a control unit that controls the inverter circuit and the DC/DC converter circuit;
Equipped with
The DC/DC converter circuit includes:
A main circuit including a main switch,
Equipped with an ARCP circuit including a resonant switch, a regenerative transformer, and a regenerative diode,
The control unit includes:
When an overvoltage exceeding a predetermined threshold is applied to the independent output terminal, a stop process is performed to stop the operation of the ARCP circuit, and the voltage value of the voltage applied to the regeneration diode via the regeneration transformer is A power conditioner device characterized by ensuring that the voltage does not exceed a predetermined allowable voltage value. The DC/DC converter circuit includes:
connected to the inverter circuit via a capacitor,
The inverter circuit is
When an overvoltage is applied to the independent output terminal, an operation is performed to supply voltage to the capacitor in order to absorb the overvoltage,
The control unit includes:
The power conditioner device according to claim 1, wherein the power conditioner device determines whether or not to perform the stop processing based on the voltage across the capacitor. The control unit includes:
2. The power conditioner device according to claim 1, wherein when performing the stop processing, the resonance switch is continuously turned off, while the main switch is turned on/off by PWM control. storage battery and
A first power conditioner device having the features of the power conditioner device according to any one of claims 1 to 3 and having a single-phase three-wire independent output end;
a second power conditioner device connected to the independent output terminal;
including;
The power supply system is characterized in that the first power conditioner device performs charging and discharging operations for the storage battery. The second power conditioner device includes:
Performing a grid-connection operation on the AC power output from the independent output terminal,
The first power conditioner device includes:
According to claim 4, when an overvoltage exceeding a predetermined threshold is applied to the independent output terminal, a grid connection operation stop process is performed to stop the grid connection operation of the second power conditioner device. Power system as described.

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