JP2024038763A - power converter - Google Patents

Abstract

[Problem] To provide a power conversion device that can easily achieve both a storage capacity and a current output. [Solution] The power conversion device includes a leg 2 and a control unit 5, and each of an upper arm 3H and a lower arm 3L includes a series circuit in which a plurality of high current modules PM and a plurality of high capacity modules EM are connected in series, the high current module PM includes a high current storage unit BP and a first switching circuit, the high capacity module EM includes a high capacity storage unit BE and a second switching circuit, the rated current value of the high current storage unit BP is greater than the rated current value of the high capacity storage unit BE, and the storage capacity of the high capacity storage unit BE is greater than the storage capacity of the high current storage unit BP, and the control unit 5 controls each of the first switching circuits and each of the second switching circuits to execute a first mode in which a current is selectively output from among the plurality of high current storage units BP and the plurality of high capacity storage units BE, and a second mode in which a current is selectively output from only the plurality of high current storage units BP. [Selected Figure] FIG.

Description

The present invention relates to a power conversion device that performs power conversion.

In recent years, a modular multilevel converter (MMC), which combines modules in which a plurality of unit converters are connected in series, has been used as an inverter that performs DC-AC conversion (see, for example, Patent Document 1). A modular multilevel converter is capable of outputting an arbitrary output voltage by adding the terminal voltages of energy storage elements included in the unit converter. An inverter using a modular multilevel converter is suitably used in electric vehicles such as electric cars and hybrid cars.

Japanese Patent Application Publication No. 2015-012769

By the way, when the energy storage element of the unit converter is discharged, the terminal voltage decreases. Therefore, in order to continue operating the modular multilevel converter stably, it is desirable that the energy storage element has a large storage capacity. On the other hand, energy storage elements with a large storage capacity that are generally available on the market have a small rated current. Therefore, it is difficult to achieve both power storage capacity and current output.

An object of the present invention is to provide a power conversion device that can easily achieve both electrical storage capacity and current output.

The power conversion device according to the present invention includes a leg in which an upper arm, an inductor, and a lower arm are connected in series in this order, and a control section, and each of the upper arm and the lower arm has a plurality of high current modules. and a plurality of high-capacity modules are connected in series, and each of the high-current modules has first and second terminals, a high-current power storage unit that stores electric charge, and a plurality of high-current storage units that connect the first and second terminals to the first and second terminals. a first switching circuit for switching connection states including an on state for connecting a high current power storage unit and a disengaged state for shorting between the first and second terminals; A terminal, a high-capacity power storage unit that stores charge, and a connection state that includes a connection state in which the high-capacity power storage unit is connected to the third and fourth terminals, and a disconnection state in which the third and fourth terminals are short-circuited. a second switching circuit for switching, the rated current value of the high current power storage unit is greater than the rated current value of the high capacity power storage unit, and the storage capacity of the high capacity power storage unit is greater than the rated current value of the high current power storage unit. capacity, and the control unit controls switching of the connection state by each of the first switching circuits and each of the second switching circuits, thereby controlling the plurality of high-current power storage units and the plurality of high-capacity power storage units. A first mode in which current is selectively outputted from among the high-current power storage units, and a second mode in which current is selectively outputted only from among the plurality of high-current power storage units are executed.

According to this configuration, the high-current power storage unit of the high-current module and the high-capacity power storage unit of the high-capacity module that are in the joining state are connected in series, and the high-current power storage unit of the high-current module and the high-capacity module that are in the disconnected state are connected in series. The high-capacity power storage units are not connected in series. The first and second switching circuits therefore make it possible to control the voltage of the legs by increasing or decreasing the number of high current modules and high capacity modules in the joined state. A first mode in which current is selectively output from among the plurality of high-current power storage units and a plurality of high-capacity power storage units, and a second mode in which current is selectively output from only the plurality of high-current power storage units. By performing these steps appropriately, it is possible to use a combination of easily available high-current power storage units with large rated current values and small storage capacity, and high-capacity power storage units with low rated current values and large storage capacity. It becomes easy to achieve both current output and current output.

Further, the control unit executes the first mode during a period in which the absolute value of the instantaneous value of the current output from the leg is less than the rated current value of the high-capacity power storage unit, and the control unit executes the first mode so that the current output from the leg It is preferable that the second mode is executed during a period in which the absolute value of the instantaneous value of exceeds the rated current value of the high capacity power storage unit.

If the absolute value of the instantaneous value of the current output from the leg exceeds the rated current value of the high-capacity power storage unit, the high-capacity power storage unit cannot pass the current. According to this configuration, the second mode is executed during a period in which the absolute value of the instantaneous value of the current output from the leg exceeds the rated current value of the high-capacity power storage unit, and the current is generated only from the high-current power storage unit with a large rated current value. By outputting , it becomes possible to perform current output by the leg.

Further, the control unit controls the first mode for a period in which the absolute value of the instantaneous value of the voltage output from the leg exceeds a maximum series voltage that is a maximum voltage that can be output using only the high current module. Preferably, the second mode is executed during a period during which the absolute value of the instantaneous value of the voltage output from the leg is less than the maximum series voltage.

If the absolute value of the instantaneous value of the voltage output from the leg exceeds the maximum series voltage, the high current module alone cannot output that voltage. According to this configuration, the first mode is executed during a period in which the absolute value of the instantaneous value of the voltage output from the leg exceeds the maximum series voltage, and the voltage is output using both the high current power storage unit and the high capacity power storage unit. Therefore, it is possible to output voltage using the legs.

Further, the control unit may be configured such that the absolute value of the instantaneous value of the current output from the leg is less than the rated current value of the high capacity power storage unit, and the absolute value of the instantaneous value of the voltage output from the leg is The first mode is executed for a period in which the maximum series voltage, which is the maximum voltage that can be output using only the high current module, is exceeded, and the absolute value of the instantaneous value of the current output from the leg is set to the high capacity power storage unit. Preferably, the second mode is executed during a period in which the current exceeds the rated current value and during a period in which the absolute value of the instantaneous value of the voltage output from the leg is less than the maximum series voltage.

According to this configuration, the absolute value of the instantaneous value of the current output from the leg is less than the rated current value of the high-capacity power storage unit, and the absolute value of the instantaneous value of the voltage output from the leg only applies to the high-current module. It is necessary to use both the high-current power storage unit and the high-capacity power storage unit for voltage output during a period exceeding the maximum series voltage, which is the maximum voltage that can be output using the high-capacity power storage unit, that is, within the current range that the high-capacity power storage unit can output. In some cases, the first mode may be implemented to effectively utilize both high current storage and high capacity storage.

Further, each of the first switching circuits may be a half-bridge or full-bridge bridge circuit, and each of the second switching circuits may be a half-bridge or full-bridge bridge circuit.

The first and second switching circuits of the half bridge can switch the connection state of the high current module and the high capacity module between an joining state and a disconnecting state. The first and second switching circuits of the full bridge change the connection state of the high current module and the high capacity module into a connected state and a disconnected state, as well as a high current power storage unit and a high capacity power storage unit with polarity opposite to the connected state. It can be switched to the inverted state to connect.

Further, it is preferable that the three legs are provided, and the three legs are connected in parallel to each other to form a three-phase inverter.

According to this configuration, it becomes possible to output three-phase AC power.

A power conversion device having such a configuration can easily achieve both power storage capacity and current output.

1 is a block diagram showing an example of the configuration of a power conversion device according to an embodiment of the present invention. 2 is a conceptual circuit diagram showing an example of the configuration of a high current module PM and a high capacity module EM shown in FIG. 1. FIG. FIG. 2 is a conceptual circuit diagram showing an example of a high current module PM and a high capacity module EM using full bridges as a first switching circuit and a second switching circuit. 2 is a flowchart showing an example of the operation of the power conversion device shown in FIG. 1. FIG. 2 is a flowchart showing an example of the operation of the power conversion device shown in FIG. 1. FIG. FIG. 2 is an explanatory diagram showing the relationship between instantaneous current value Ir(u), output current Iu, rated current value Ie, and first mode M1 and second mode M2. FIG. 2 is an explanatory diagram showing the relationship between instantaneous voltage value Vr(u), output voltage Vu, maximum series voltage Vp(u), and first mode M1 and second mode M2.

Hereinafter, embodiments according to the present invention will be described based on the drawings. It should be noted that structures given the same reference numerals in each figure indicate the same structure, and the explanation thereof will be omitted. FIG. 1 is a block diagram showing an example of the configuration of a power conversion device according to an embodiment of the present invention.

The power conversion device 1 shown in FIG. 1 roughly includes legs 2u, 2v, and 2w, a capacitor C, a control section 5, and external terminals Tu, Tv, and Tw. The legs 2u, 2v, and 2w are connected in parallel to form a three-phase inverter 6.

The three-phase inverter 6 and the capacitor C are connected in parallel by a power line WH on the high potential side and a power line WL on the low potential side. Capacitor C performs smoothing, voltage stabilization, etc. Note that the power conversion device 1 does not necessarily need to include the capacitor C.

The leg 2u is configured by an upper arm 3H, an inductor L, and a lower arm 3L connected in series in this order. Legs 2v and 2w are configured similarly to leg 2u, so a description thereof will be omitted. Hereinafter, legs 2u, 2v, and 2w will be collectively referred to as leg 2.

The midpoint of inductor L of leg 2u is connected to external terminal Tu, the midpoint of inductor L of leg 2v is connected to external terminal Tv, and the midpoint of inductor L of leg 2w is connected to external terminal Tw. Thereby, the external terminals Tu, Tv, and Tw function as three-phase power output terminals or three-phase regenerative current input terminals of the power conversion device 1. Various three-phase power loads, such as a three-phase motor, can be connected to the external terminals Tu, Tv, and Tw, and the power conversion device 1 may be mounted on an electric vehicle.

The inductor L may be, for example, a reactor with a center tap, or may be one in which two inductors are connected in series and their connection points are connected to external terminals Tu, Tv, and Tw. The output voltages of the legs 2u, 2v, and 2w, that is, the voltages of the external terminals Tu, Tv, and Tw, are defined as output voltages Vu, Vv, and Vw. Further, the output currents of the legs 2u, 2v, and 2w, that is, the currents outputted to the outside from the external terminals Tu, Tv, and Tw, are referred to as output currents Iu, Iv, and Iw.

Each of the upper arm 3H and the lower arm 3L includes a series circuit in which a plurality of high current modules PM and a plurality of high capacity modules EM are connected in series. In the example shown in FIG. 1, the upper arm 3H and the lower arm 3L are composed of only a series circuit in which a plurality of high current modules PM and a plurality of high capacity modules EM are connected in series. The arm 3H and the lower arm 3L only need to include a series circuit of a plurality of high current modules PM and a plurality of high capacity modules EM, other than a series circuit of a plurality of high current modules PM and a plurality of high capacity modules EM. It may also include.

FIG. 2 is a conceptual circuit diagram showing an example of the configuration of the high current module PM and high capacity module EM shown in FIG. 1. In FIG. 2, the symbols of the components related to the high-capacity module EM are shown in parentheses.

The high current module PM of leg 2 includes a terminal T1 (first terminal), a terminal T2 (second terminal), a high current power storage unit BP that stores charge, and an electrical connection of the high current power storage unit BP to the terminal T1 and the terminal T2. It includes switching elements SW1 and SW2 (first switching circuit) for switching connection states. The switching elements SW1 and SW2 used in the high current module PM correspond to an example of a first switching circuit, and the switching elements SW1 and SW2 used in the high capacity module EM correspond to an example of a second switching circuit. In the example shown in FIG. 2, the first switching circuit and the second switching circuit constitute a half bridge.

Specifically, in high current module PM, high current power storage unit BP and switching element SW1 are connected in series, and switching element SW2 is connected in parallel to the series circuit of high current power storage unit BP and switching element SW1. A connection point between switching element SW1 and switching element SW2 is connected to terminal T1, and a connection point between switching element SW2 and high current power storage unit BP is connected to terminal T2.

High-capacity module EM differs from high-current module PM in that high-capacity power storage unit BE is used instead of high-current power storage unit BP, and terminal T3 (third terminal) and terminal T4 (third terminal) are used instead of terminals T1 and T2. The difference is that it uses four terminals). In other respects, the high-capacity module EM is configured similarly to the high-current module PM, so a description thereof will be omitted.

Terminal T1 of high current module PM is connected to terminal T2 of high current module PM or terminal T4 of high capacity module EM, which is on the higher potential side than the own module. Terminal T2 of high current module PM is connected to terminal T1 of high current module PM or terminal T3 of high capacity module EM, which is on the lower potential side than the own module.

Similarly, the terminal T3 of the high capacity module EM is connected to the terminal T2 of the high current module PM or the terminal T4 of the high capacity module EM, which is on the higher potential side than the own module. The terminal T4 of the high capacity module EM is connected to the terminal T1 of the high current module PM or the terminal T3 of the high capacity module EM, which is on the lower potential side than the own module. Thereby, the plurality of high current modules PM and the plurality of high capacity modules EM are connected in series.

In the example shown in FIG. 1, a series circuit of only a plurality of high-current modules PM and a series circuit of only a plurality of high-capacity modules EM are connected in series, but the high-current modules PM and high-capacity modules EM A mixture of these may be connected in series.

The terminal T1 of the high current module PM or the terminal T3 of the high capacity module EM on the highest potential side in the upper arm 3H is connected to the power line WH. The terminal T2 of the high current module PM or the terminal T4 of the high capacity module EM, which is the lowest potential side in the upper arm 3H, is connected to one end of the inductor L. The terminal T1 of the high current module PM or the terminal T3 of the high capacity module EM on the highest potential side in the lower arm 3L is connected to the other end of the inductor L. The terminal T2 of the high current module PM or the terminal T4 of the high capacity module EM on the lowest potential side in the lower arm 3L is connected to the power line WL.

Various switching elements can be used as the switching elements SW1 and SW2, and for example, semiconductor switching elements such as transistors can be suitably used. Switching elements SW1 and SW2 are turned on and off according to a control signal from control section 5.

Various types of power storage elements can be suitably used as the high current power storage unit BP and the high capacity power storage unit BE, and are not limited to single power storage elements, but also battery packs in which a plurality of power storage elements are combined, etc. It may also be used as a high capacity power storage unit BE.

Rated current value Ip of high-current power storage unit BP is larger than rated current value Ie of high-capacity power storage unit BE. Furthermore, high-capacity power storage unit BE has a larger power storage capacity than high-current power storage unit BP. The power storage element used in high-current power storage unit BP and the power storage element used in high-capacity power storage unit BE may be different in type. For example, a capacitor such as an electric double layer capacitor may be used as the power storage element for the high current power storage unit BP, and a secondary battery such as a lithium ion secondary battery may be used as the power storage element for the high capacity power storage unit BE.

The high current module PM and high capacity module EM indicated by symbol A are in the connected state, and the high current module PM and high capacity module EM indicated by symbol B are in the disconnected state. In the join state, the switching element SW1 is on and the switching element SW2 is off, and in the detached state, the switching element SW1 is off and the switching element SW2 is on.

High current power storage unit BP and high capacity power storage unit BE in high current module PM and high capacity module EM in the joined state are connected in series at upper arm 3H and lower arm 3L, and high current module PM and high capacity module EM in disconnected state is shorted. As a result, the voltage across upper arm 3H and lower arm 3L becomes the total voltage of high current power storage unit BP and high capacity module EM in the connected state in upper arm 3H and lower arm 3L.

Hereinafter, high capacity module EM and high current module PM may be collectively referred to as module XM, and high current power storage unit BP and high capacity power storage unit BE may be collectively referred to as power storage unit BX.

Note that the high current module PM may use a full bridge as the first switching circuit, and the high capacity module EM may use a full bridge as the second switching circuit. FIG. 3 is a conceptual circuit diagram showing an example of a high current module PM and a high capacity module EM using full bridges as the first switching circuit and the second switching circuit.

The full-bridge high-current module PM and high-capacity module EM shown in FIG. 3 further include switching elements SW3 and SW4 in addition to the half-bridge high-current module PM and high-capacity module EM shown in FIG. As the switching elements SW3 and SW4, switching elements similar to the switching elements SW1 and SW2 can be used.

Specifically, a series circuit of switching elements SW3 and SW4 is connected in parallel to a series circuit of switching elements SW1 and SW2. A connection point between switching elements SW1 and SW2 is connected to terminal T1 or terminal T3, and a connection point between switching elements SW3 and SW4 is connected to terminal T2 or terminal T4. The switching elements SW1 to SW4 used in the high-current module PM correspond to an example of a full-bridge first switching circuit, and the switching elements SW1 to SW4 used in the high-capacity module EM correspond to an example of a full-bridge second switching circuit. do.

The full-bridge high-current module PM and high-capacity module EM shown in FIG. 3 can be in an inverted state as shown in C, in addition to an joining state shown as A and a leaving state as shown B. In the high current module PM and high capacity module EM in the inverted state, the high current power storage unit BP and the high capacity power storage unit BE are connected with their polarities reversed.

In the joining state, switching elements SW1 and SW4 are turned on and switching elements SW2 and SW3 are turned off. In the detached state, switching elements SW1 and SW3 are turned off, and switching elements SW2 and SW4 are turned on. In the inverted state, switching elements SW1 and SW4 are turned off, and switching elements SW2 and SW3 are turned on. Note that in the detached state, the switching elements SW1 and SW3 may be turned on and the switching elements SW2 and SW4 may be turned off.

Hereinafter, the control unit 5 controls the switching elements SW1 and SW2 to control the connection state including the joining state and the leaving state, or controlling the switching elements SW1 to SW4 to control the joining state, the leaving state, and the inverted state. Controlling the connection state including the connection state is simply referred to as controlling the connection state.

When using the full bridge high current module PM shown in FIG. The voltage is obtained by subtracting the total voltage of high current power storage unit BP and high capacity power storage unit BE of high current module PM and high capacity module EM in the inverted state from the total voltage of current power storage unit BP and high capacity power storage unit BE.

For example, an unillustrated external power source is connected to the power lines WH and WL, so that the high current power storage unit BP and the high capacity power storage unit BE can be charged as appropriate.

The control unit 5 shown in FIG. 1 includes, for example, a CPU (Central Processing Unit) that executes predetermined logical operations, a RAM (Random Access Memory) that temporarily stores data, a nonvolatile storage device, and peripheral circuits thereof. etc., and operates by executing a predetermined program. The control unit 5 also receives information from the outside of the power converter 1, for example, an electric vehicle, such as the rotation angle R of the rotor of the motor, the required torque T, and the output currents Iu, Iv, and Iw supplied to the motor from the legs 2u, 2v, and 2w. It is possible to obtain information indicating the

The rotation angle R of the rotor is detected by a rotation angle sensor (such as a resolver) attached to the motor shaft. The required torque T is a required value of motor torque output from a vehicle controller or the like of the electric vehicle. The output currents Iu, Iv, and Iw are detected by current sensors provided on the electric vehicle side. Note that the power conversion device 1 may include a current sensor that detects the output currents Iu, Iv, and Iw.

The control unit 5 controls the switching of the connection state by the switching elements SW1, SW2 (SW3, SW4) in each high current module PM and each high capacity module EM, thereby connecting the external terminals Tu, Tv from the legs 2u, 2v, 2w. , Tw to the outside to output voltages Vu, Vv, and Vw with desired waveforms. Then, by applying the output voltages Vu, Vv, and Vw to an external load such as a motor, output currents Iu, Iv, and Iw flow.

As a control method for converting or regenerating voltage, voltage waveforms, etc. by the three-phase inverter 6, that is, the legs 2u, 2v, and 2w, a known inverter control method can be used. For example, a control method for a modular multilevel converter may be used. Can be used.

Further, the control unit 5 selectively selects one of the plurality of high current power storage units BP and the plurality of high capacity power storage units BE by controlling switching of the connection state by each first switching circuit and each second switching circuit. A first mode M1 in which current is outputted and a second mode M2 in which current is selectively outputted only from among the plurality of high current power storage units BP are executed.

4 and 5 are flowcharts showing an example of the operation of the power conversion device 1 shown in FIG. 1. In the following example, a case will be described in which the external load connected to the power conversion device 1 is a motor of an electric vehicle. First, the control unit 5 obtains the rotation angle R and the required torque T by receiving a signal from an external electric vehicle or the like (step S1).

Next, the control unit 5 acquires the target current It, which is the current to be output from the three-phase inverter 6, that is, the current required to cause the motor to generate the required torque T, based on the required torque T (step S2 ). Specifically, the control unit 5 may calculate the target current It from the required torque T using a known formula set in advance. Alternatively, the control unit 5 may obtain the target current It corresponding to the required torque T by referring to a preset lookup table showing the relationship between torque and current. The method for obtaining the target current It from the required torque T is not limited to a specific method, and various known methods can be used.

Next, the control unit 5 controls the legs 2u, 2v, 2w so that the output currents Iu, Iv, Iw become the target currents It by feedback control based on the output currents Iu, Iv, Iw acquired in real time from the outside. The output voltages Vu, Vv, and Vw are controlled by controlling the connection state at (step S3). In step S3, steps S13, S14, S23, S24 . If the first mode M1 or the second mode M2 has already been set in S33 and S34, the connection state in legs 2u, 2v, and 2w is controlled according to the mode set for legs 2u, 2v, and 2w, respectively. do.

Specifically, when the first mode M1 is set, the control unit 5 selectively outputs a current from among the plurality of high current power storage units BP and the plurality of high capacity power storage units BE in each leg. In other words, the connection states in legs 2u, 2v, and 2w are controlled so that output currents Iu, Iv, and Iw become target current It using both high-current power storage unit BP and high-capacity power storage unit BE.

On the other hand, when the second mode M2 is set, the control unit 5 sets all the high-capacity modules EM in each leg to the detached state, thereby causing the multiple high-capacity power storage units BE to output no current. By selectively outputting a current from among the high current power storage units BP, that is, by using only the high current power storage unit BP, the legs 2u, 2v, 2w control the connection state in

As the feedback control, various control methods such as PI control can be used. Moreover, it is sufficient if the output currents Iu, Iv, and Iw can be controlled so as to approach the target current It, and the control method is not limited to feedback control.

Next, the control unit 5 calculates instantaneous voltage values Vr(u), Vr(v), and Vr(w) of each phase of the output voltages Vu, Vv, and Vw from the connection state by the feedback control in step S3 ( Step S4). Based on the real-time connection state obtained in step S3, the control unit 5 determines the voltage of the power storage unit BX of the module XM in the joined state in legs 2u, 2v, and 2w in the case of a half bridge, and the voltage of the power storage unit BX of the module XM in the joining state in the case of a full bridge. The instantaneous voltage values Vr(u), Vr(v), Vr(w) of the output voltages Vu, Vv, Vw are calculated from the voltages of the power storage unit BX of the module It can be calculated. The voltage of each power storage unit BX can be acquired, for example, by providing a voltage detection circuit (not shown) that detects the voltage of each power storage unit BX.

Next, the control unit 5 calculates instantaneous current values Ir(u), Ir(v), and Ir(w) of the output currents Iu, Iv, and Iw of the three-phase AC waveform from the target current It (step S5). .

Next, the control unit 5 moves the process to steps S11, S21, and S31. Hereinafter, steps S11 to S14, steps S21 to S24, and steps S31 to S34 are executed in parallel.

First, processing related to the U phase of leg 2u will be explained. If the absolute value of the instantaneous current value Ir(u) exceeds the rated current value Ie (NO in step S11), the control unit 5 moves the process to step S14.

In step S14, control unit 5 sets second mode M2 for leg 2u, so that power storage unit BX that outputs current in step S3 is one of only the plurality of high current power storage units BP in leg 2u. (step S14), and the process returns to step S1.

FIG. 6 shows the instantaneous current value Ir(u), the output current Iu represented by a continuous waveform of the instantaneous current value Ir(u), the rated current value Ie, and the first mode M1 and second mode M2. It is an explanatory diagram showing a relationship. The horizontal axis represents time t, and the vertical axis represents current value. Note that FIG. 6 illustrates a case in which the absolute value of the instantaneous voltage value Vr(u) is less than or equal to the maximum series voltage Vp(u), which will be described later.

According to steps S11 and S14, as shown in FIG. 6, in the AC waveform of the output current Iu, from timing t1 to timing t2, which is the period during which the absolute value of the instantaneous current value Ir(u) exceeds the rated current value Ie, The second mode M2 is executed in step S3 from timing t3 to timing t4, from timing t5 to timing t6, and from timing t7 to timing t8.

If the absolute value of the instantaneous current value Ir(u) exceeds the rated current value Ie (NO in step S11), it means that the high-capacity power storage unit BE cannot output the current of the instantaneous current value Ir(u) at that moment. do. Therefore, when the absolute value of the instantaneous current value Ir(u) exceeds the rated current value Ie (NO in step S11), the control unit 5 sets the second mode M2 in step S14, and sets the second mode M2 in step S3. Execute M2.

Thereby, current output from leg 2u in step S3 is performed only by high current power storage unit BP, and no current is output from high capacity power storage unit BE. As a result, it becomes possible to output an instantaneous current value Ir(u) exceeding the rated current value Ip from the leg 2u.

On the other hand, if the absolute value of the instantaneous current value Ir(u) is less than or equal to the rated current value Ie (YES in step S11), the control unit 5 sets the absolute value of the instantaneous voltage value Vr(u) and the maximum series voltage Vp(u ) (step S12). The maximum series voltage Vp(u) is the maximum voltage that can be output using only the high current module PM included in the leg 2u.

Specifically, regardless of whether the module XM is a herb bridge or a full bridge, the maximum series voltage Vp(u) is This is the total value of the voltages of high current power storage units BP, and when the instantaneous voltage value Vr(u) is −, it is the total value of the voltages of all high current power storage units BP included in upper arm 3H of leg 2u. Control unit 5 can calculate maximum series voltage Vp(u) by summing the voltages of each high current power storage unit BP detected by the voltage detection circuit described above.

Alternatively, a voltage value that is approximately appropriate as the maximum voltage that can be output using only the high current module PM included in the leg 2u may be fixedly set in advance as the maximum series voltage Vp(u).

When both upper arm 3H and lower arm 3L are used, the effect of the full bridge is limited to the ability to selectively use charging and discharging for each power storage unit. In the case of a three-phase inverter circuit configured only with the lower arm 3L, by using a full bridge circuit, positive and negative voltage outputs are possible, and sine wave AC output is possible.

Like the maximum series voltage Vp(u), the maximum series voltages Vp(v) and Vp(w) are the maximum voltages that can be output using only the high current modules PM included in the legs 2v and 2w, respectively. The maximum series voltages Vp(v) and Vp(w) are set in the same manner as the maximum series voltage Vp(u) based on the high current modules PM included in the legs 2v and 2w.

If the absolute value of the instantaneous voltage value Vr(u) exceeds the maximum series voltage Vp(u) (YES in step S12), in the second mode M2 using only the high current module PM, the instantaneous voltage value Vr(u) cannot be output, the control section 5 moves to step S13 and sets the first mode.

In step S13, the control unit 5 sets the first mode for the leg 2u so that the power storage unit BX that outputs current is set to the plurality of high-current power storage units BP and the plurality of high-capacity power storage units in the leg 2u. (step S13), and the process returns to step S1.

FIG. 7 shows the instantaneous voltage value Vr(u), the output voltage Vu in which the instantaneous voltage value Vr(u) is represented by a continuous waveform, the maximum series voltage Vp(u), and the first mode M1 and the second mode. FIG. 2 is an explanatory diagram showing the relationship with M2. The horizontal axis represents time t, and the vertical axis represents voltage value. Note that FIG. 7 illustrates a case where the absolute value of the instantaneous current value Ir(u) is less than or equal to the rated current value Ie.

According to steps S12 and S13, as shown in FIG. 7, in the AC waveform of the output voltage Vu, from timing t11, which is a period in which the absolute value of the instantaneous voltage value Vr(u) exceeds the maximum series voltage Vp(u), The first mode M1 is executed in step S3 until t12, from timing t13 to timing t14, from timing t15 to timing t16, and from timing t17 to timing t18.

If the absolute value of the instantaneous voltage value Vr(u) exceeds the maximum series voltage Vp(u) (YES in step S12), the leg 2u will at that moment This means that voltage cannot be output. Therefore, when the absolute value of the instantaneous voltage value Vr(u) exceeds the maximum series voltage Vp(u) (YES in step S12), the control unit 5 sets the first mode M1 (step S13), and in step S3 The first mode M1 is executed.

Thereby, the voltage output from leg 2u in step S3 can be output using both high current power storage unit BP and high capacity power storage unit BE in first mode M1. As a result, as shown in FIG. It becomes possible to output by one mode M1.

On the other hand, in step S12, if the absolute value of the instantaneous voltage value Vr(u) does not exceed the maximum series voltage Vp(u) (NO in step S12), the instantaneous voltage value is Since Vr(u) can be output, the control unit 5 moves to step S14 to set the second mode M2, and executes the second mode M2 in step S3.

Note that if the absolute value of the instantaneous current value Ir(u) is less than the rated current value Ie (YES in step S11), the process moves to step S12, and the absolute value of the instantaneous current value Ir(u) is greater than or equal to the rated current value Ie. In this case (NO in step S11), the process may proceed to step S14. Further, if the absolute value of the instantaneous voltage value Vr(u) is greater than or equal to the maximum series voltage Vp(u) (YES in step S12), the process moves to step S13, and the absolute value of the instantaneous voltage value Vr(u) is equal to or higher than the maximum series voltage Vp(u). If it is less than Vp(u) (NO in step S12), the process may proceed to step S14.

Steps S21 to S24 regarding the V phase of leg 2v and steps S31 to S34 regarding the W phase of leg 2w are performed using instantaneous current values Ir(v), Ir(w) and instantaneous voltage instead of instantaneous current value Ir(u). It is the same as steps S11 to S14 except that the instantaneous voltage values Vr(v) and Vr(w) are used instead of the value Vr(u), and legs 2v and 2w are used instead of leg 2u, so the explanation thereof will be omitted. .

Since the power storage units BX of the legs 2u, 2v, and 2w supply power to the load with a voltage waveform converted to three-phase AC or the like, it is necessary to follow load fluctuations and instantaneously flow a large current. Therefore, it is preferable that power storage unit BX is a secondary battery with a large rated current. On the other hand, since the voltage of power storage unit BX decreases when it is discharged, it is desirable that the power storage capacity of power storage unit BX is large in order to continue operating power converter 1 stably. However, a power storage element with a large rated current and a large power storage capacity is difficult to obtain or is expensive.

Therefore, by using a combination of easily available high-current power storage unit BP with a large rated current value Ip and small storage capacity and high-capacity power storage unit BE with a small rated current value Ie and large storage capacity, it is possible to obtain power storage unit BX. This makes it easy to implement and reduce costs. Furthermore, a first mode M1 in which current is selectively outputted from among the plurality of high-current power storage units BP and the plurality of high-capacity power storage units BE, and a current is selectively outputted from only the plurality of high-current power storage units BP. By executing second mode M2, it becomes easy to achieve both power storage capacity and current output while using a combination of high-current power storage unit BP and high-capacity power storage unit BE.

Note that the control unit 5 does not necessarily need to execute steps S12, S22, and S32; when YES in step S11, the process proceeds to step S13; when YES in step S21, the process proceeds to step S23; If YES in S31, the process may proceed to step S33.

Further, the control unit 5 does not necessarily need to execute steps S11, S21, and S31, and may shift the process from step S5 to steps S12, S22, and S32.

Furthermore, the power conversion device 1 is not limited to being mounted on an electric vehicle, and the control unit 5 does not need to obtain the rotation angle R or the required torque T, and does not need to execute steps S1 and S2. . Furthermore, the control unit 5 does not need to acquire the output currents Iu, Iv, and Iw, and is not limited to the example in which feedback control is performed based on the output currents Iu, Iv, and Iw in step S3.

The output currents Iu, Iv, Iw and the output voltages Vu, Vv, Vw may have various waveforms, and are not limited to motor drive waveforms. For example, the output currents Iu, Iv, Iw and the output voltages Vu, Vv, Vw may be sine wave alternating currents with fixed amplitudes and frequencies, or may be direct currents.

Moreover, the power conversion device 1 is not limited to the example provided with three legs 2u, 2v, and 2w. The power converter 1 may be a single-phase power converter having one leg, or may be a power converter having two, four or more legs.

1 Power converter 2u, 2v, 2w Leg 3H Upper arm 3L Lower arm 5 Control unit 6 Three-phase inverter BE High capacity power storage unit BP High current power storage unit BX Power storage unit C Capacitor EM High capacity module Ie, Ip Rated current value Ir ( u), Ir(v), Ir(w) Instantaneous current value It Target current Iu, Iv, Iw Output current L Inductor M1 First mode M2 Second mode PM High current module R Rotation angle SW1 to SW4 Switching element (first switching circuit, second switching circuit)
T Required torque T1 Terminal (first terminal)
T2 terminal (second terminal)
T3 terminal (third terminal)
T4 terminal (fourth terminal)
Tu, Tv, Tw External terminals Vp (u), Vp (v), Vp (w) Maximum series voltage Vr (u), Vr (v), Vr (w) Instantaneous voltage values Vu, Vv, Vw Output voltage WH, WL Power Line XM Module

Claims (6)

A leg in which an upper arm, an inductor, and a lower arm are connected in series in this order;
It is equipped with a control section,
Each of the upper arm and the lower arm includes a series circuit in which a plurality of high current modules and a plurality of high capacity modules are connected in series,
Each of the high current modules is
first and second terminals;
A high current storage unit that stores charge,
a first switching circuit that switches between connection states including a connection state in which the high current power storage unit is connected to the first and second terminals and a disconnection state in which the first and second terminals are short-circuited;
Each of the high capacity modules is
third and fourth terminals;
A high-capacity storage unit that stores electric charge,
a second switching circuit that switches between connection states including a connection state in which the high-capacity power storage unit is connected to the third and fourth terminals and a disconnection state in which the third and fourth terminals are short-circuited;
The rated current value of the high current power storage unit is larger than the rated current value of the high capacity power storage unit,
The power storage capacity of the high capacity power storage unit is larger than the power storage capacity of the high current power storage unit,
The control unit includes:
Selectively outputting current from among the plurality of high current power storage units and the plurality of high capacity power storage units by controlling switching of the connection state by each of the first switching circuit and each of the second switching circuit. A power conversion device that executes a first mode and a second mode in which current is selectively output from only the plurality of high current power storage units. The control unit includes:
The first mode is executed during a period in which the absolute value of the instantaneous value of the current output from the leg is less than the rated current value of the high-capacity power storage unit, and the absolute value of the instantaneous value of the current output from the leg is The power conversion device according to claim 1 , wherein the second mode is executed during a period in which the current exceeds a rated current value of the high-capacity power storage unit. The control unit includes:
The first mode is executed during a period in which the absolute value of the instantaneous value of the voltage output from the leg exceeds a maximum series voltage that is the maximum voltage that can be output using only the high current module, and the voltage is output from the leg. The power conversion device according to claim 1 , wherein the second mode is executed during a period in which the absolute value of the instantaneous value of the voltage applied is less than the maximum series voltage. The control unit includes:
The absolute value of the instantaneous value of the current output from the leg is less than the rated current value of the high-capacity power storage unit, and the absolute value of the instantaneous value of the voltage output from the leg uses only the high-current module. The first mode is executed for a period in which the absolute value of the instantaneous value of the current output from the leg exceeds the rated current value of the high-capacity power storage unit. The power conversion device according to claim 1 , wherein the second mode is executed during a period in which the absolute value of the instantaneous value of the voltage output from the leg is less than the maximum series voltage. Each of the first switching circuits is a half-bridge or full-bridge bridge circuit,
The power conversion device according to claim 1, wherein each of the second switching circuits is a half-bridge or full-bridge bridge circuit. comprising three of the legs;
The power conversion device according to claim 1, wherein the three legs are connected in parallel to each other to constitute a three-phase inverter.

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