Power supply device, charging device, charging / discharging device, charging / discharging system, and control method

Abstract

To provide a power supply device, a charging device, a charging / discharging device, a charging / discharging system, and a control method that enable not only charging a battery from an AC power source but also supplying power (discharging) from the battery to the AC power source with a simple configuration.SOLUTION: A charging / discharging device includes: a first inverter connected between one winding of a motor having multiple windings and a battery; a second inverter connected to the other winding; a grid-connected relay for opening and closing a connection to an AC power supply source; a third inverter for converting the AC power from the AC power supply source connected via the grid-connected relay into a DC power at charging to output to the second inverter, and converting the DC power from the second inverter to the AC power at discharging to output to the AC power supply source via the grid-connected relay; and a first relay switch connected between the DC side of the second inverter and the DC side of the third inverter, wherein a status of the battery is monitored, the connection of the first relay switch is closed when charging / discharging, and the connection of the grid-connected relay is closed when voltage and frequency of the AC power supply source are within a predetermined range.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power supply device, a charging device, a charging / discharging device, a charging / discharging system, and a control method. [Background technology]

[0002] As renewable energy adoption expands toward achieving carbon neutrality, technologies that smooth unstable renewable energy generation and stabilize commercial power grids are becoming increasingly important. For example, smoothing the balance of power supply and demand using storage batteries is one example. In particular, V2X (Vehicle to X) systems, which utilize storage batteries installed in electric vehicles (EVs), which have become increasingly popular in recent years, have attracted attention. In a V2H (Vehicle to Home) system, one form of V2X system, the battery installed in an EV is connected to a residential power grid. The battery can be charged from the grid or the battery's power can be fed back to the grid. For example, during the daytime, when the solar power generation system generates more power than the home's power consumption, the surplus power can be stored in the EV's battery. At night, when the solar power generation system is low and power consumption is high, power from the EV's battery can be supplied to the home. This reduces the amount of power generated by the PV system sold to the commercial power grid and reduces the power supplied to the home from the commercial power grid, thereby smoothing the balance of power supply and demand.

[0003] However, to configure a V2X system, a V2X device is required, separate from the electric vehicle, to charge and discharge the battery installed in the electric vehicle. A V2X device generally consists of a charge / discharge unit consisting of an isolated DC-DC converter and an inverter, and a grid connection protection unit that protects both by isolating the charge / discharge unit from the AC power system in the event of an abnormality in the AC power system. Therefore, configuring a V2X system requires a complex and expensive system, and has not yet become widespread.

[0004] As a technology to solve this problem, for example, Patent Document 1 discloses a technology that includes a first inverter and a second inverter that drive a dual three-phase motor, and a converter that converts power from an AC power supply system into DC power and supplies it to the second inverter; when charging the battery from the AC power supply system, the dual three-phase motor is used as an isolation transformer, and functions as an isolated DC-DC converter together with the first inverter and the second inverter.This eliminates the need for the isolation function of an external charging device, while minimizing the complexity and size of component mechanisms that would otherwise be required to add an isolation function to an electric vehicle, thereby simplifying the charging system. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6079455 Summary of the Invention [Problem to be solved by the invention]

[0006] However, while the charging device disclosed in Patent Document 1 can charge the battery in an electric vehicle from an AC power system, it cannot supply (discharge) battery power to the AC power system. Therefore, a separate V2X device is required to configure the above-mentioned V2X system, which poses the problem of making the V2X system complex and large. Furthermore, when charging and discharging using a separate V2X device, sequence control via communication is required between the battery control unit in the electric vehicle and the charge / discharge control unit in the V2X device, which poses the problem of charging and discharging being impossible if a communication abnormality occurs due to incompatibility between the devices.

[0007] The present disclosure has been made in consideration of the above-mentioned circumstances, and one of its objectives is to provide a power supply device, a charging device, a charging / discharging device, a charging / discharging system, and a control method that are simply configured and capable of not only charging a battery from an AC power source but also supplying (discharging) power from a battery to an AC power source. [Means for solving the problem]

[0008] One aspect of the present disclosure is a power supply device that supplies power from a battery to an AC power supply source, the power supply device including: a motor having multiple windings; a first inverter connected between a first winding of the multiple windings and the battery, and configured to convert DC power from the battery into AC power and output the AC power to the motor when power from the battery is supplied to the AC power supply source; a second inverter connected to a second winding of the multiple windings, and configured to convert AC power output by the motor into DC power and output the DC power when power from the battery is supplied to the AC power supply source; an interconnection relay connected to one end of the AC power supply source and configured to open and close the connection with the AC power supply source in response to an external command; a third inverter connected to the other end of the interconnection relay and configured to convert DC power output by the second inverter into AC power and output the AC power to the AC power supply source via the interconnection relay; and a third inverter connected to one end of the second inverter and configured to open and close the connection with the AC power supply source in response to an external command. a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter, and the grid-connection relay based on the outputs; wherein the control unit outputs a drive signal to the first relay switch as the external command to close the connection of the first relay switch when power from the battery is to be supplied to the AC power supply source, and outputs a drive signal to the grid-connection relay as the external command to the grid-connection relay when the voltage and frequency of the AC power supply source measured by the measurement unit are within predetermined ranges.

[0009] Another aspect of the present disclosure is a charging device that charges a battery with power from an AC power supply source, the charging device including: a motor having multiple windings; a first inverter connected between a first winding of the multiple windings and the battery, and configured to convert AC power output by the motor into DC power and output the DC power to the battery when charging the battery with power from the AC power supply source; a second inverter connected to a second winding of the multiple windings, and configured to convert DC power into AC power and output the AC power to the motor when charging the battery with power from the AC power supply source; an interconnection relay connected to the AC power supply source on one side and configured to open and close the connection with the AC power supply source in response to an external command; a third inverter connected to the other side of the interconnection relay, and configured to convert AC power from the AC power supply source connected via the interconnection relay and output the DC power when charging the battery with power from the AC power supply source; a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter, and the grid-connection relay based on the outputs; wherein the control unit outputs a drive signal to the first relay switch as the external command when the battery is to be charged with power from the AC power supply source, and outputs a drive signal to the grid-connection relay as the external command when the voltage and frequency of the AC power supply source measured by the measurement unit are within a predetermined range.

[0010] Another aspect of the present disclosure is a charging / discharging device that charges and discharges between a battery and an AC power supply source, the charging / discharging device including: a motor having multiple windings; a first inverter connected between one winding of the multiple windings and the battery, the first inverter converting AC power output by the motor into DC power and outputting the DC power to the battery when charging the battery, and converting DC power from the battery into AC power and outputting the DC power to the motor when discharging the battery; a second inverter connected to the other winding of the multiple windings, the second inverter converting DC power into AC power and outputting the DC power to the motor when charging the battery, and converting AC power output by the motor into DC power when discharging the battery; an interconnection relay connected to one end of the interconnection relay and opening and closing a connection with the AC power supply source in response to an external command; and a second inverter connected to the other end of the interconnection relay, the second inverter converting AC power from the AC power supply source connected via the interconnection relay into DC power and outputting the DC power when charging the battery, and converting DC power output by the second inverter into DC power when discharging the battery. a third inverter that converts the converted AC power into AC power and outputs it to the AC power supply source via the grid-connection relay; a first relay switch that has one side connected to the DC side of the second inverter and the other connected to the DC side of the third inverter and that opens and closes the connection between the DC side of the second inverter and the DC side of the third inverter in response to an external command; a measurement unit that measures the voltage and frequency of the AC power supply source; a battery monitoring unit that monitors the state of the battery; and a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter, and the grid-connection relay based on the inputs, wherein the control unit outputs a drive signal to the first relay switch as the external command when charging or discharging between the battery and the AC power supply source, and outputs a drive signal to the grid-connection relay as the external command when the voltage and frequency of the AC power supply source measured by the measurement unit are within predetermined ranges.

[0011] Another aspect of the present disclosure is a charging / discharging system including a battery, an AC power supply source, and a charging / discharging device that charges and discharges between the battery and the AC power supply source, the charging / discharging system including a motor having multiple windings, a first inverter connected between one winding of the multiple windings and the battery, and that converts AC power output by the motor into DC power and outputs it to the battery when charging the battery, and converts DC power from the battery into AC power and outputs it to the motor when discharging the battery, and a second inverter connected to the other winding of the multiple windings. a second inverter connected to the grid, which converts DC power into AC power and outputs it to the motor when charging the battery, and converts AC power output by the motor into DC power and outputs it when discharging the battery; an interconnection relay connected to one end of the interconnection relay and which opens and closes the connection with the AC power supply source in response to an external command; and a second inverter connected to the grid, which converts AC power from the AC power supply source connected via the interconnection relay into DC power and outputs it when charging the battery, and converts AC power from the AC power supply source connected via the interconnection relay into DC power and outputs it when discharging the battery. a third inverter that converts DC power output by a second inverter into AC power and outputs the AC power to the AC power supply source via the grid-connection relay; a first relay switch, one side of which is connected to the DC side of the second inverter and the other side of which is connected to the DC side of the third inverter, and which opens and closes the connection between the DC side of the second inverter and the DC side of the third inverter in response to an external command; a measurement unit that measures the voltage and frequency of the AC power supply source; a battery monitoring unit that monitors the state of the battery; and a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter, and the grid-connection relay based on the inputs, wherein the control unit outputs a drive signal to the first relay switch as the external command when charging or discharging between the battery and the AC power supply source, and outputs a drive signal to the grid-connection relay as the external command when the voltage and frequency of the AC power supply source measured by the measurement unit are within a predetermined range.

[0012] Another aspect of the present disclosure is a motor having multiple windings, a first inverter connected between a first winding of the multiple windings and a battery, and converting DC power from the battery into AC power and outputting the AC power to the motor when power from the battery is supplied to an AC power supply source, a second inverter connected to a second winding of the multiple windings, and converting AC power output by the motor into DC power and outputting the DC power when power from the battery is supplied to the AC power supply source, a grid-connected relay connected to one end of the AC power supply source and opening and closing the connection with the AC power supply source in response to an external command, a third inverter connected to the other end of the grid-connected relay and converting the DC power output by the second inverter into AC power and outputting the AC power to the AC power supply source via the grid-connected relay, and a third inverter connected to one end of the grid-connected relay and to the DC side of the second inverter and the DC side of the third inverter in response to an external command. a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter, and the grid-connection relay based on the inputs, and that supplies power from the battery to the grid-connection relay; the control unit outputs a drive signal to the first relay switch as the external command when power from the battery is to be supplied to the grid-connection relay; and when the voltage and frequency of the AC power supply source measured by the measurement unit are within predetermined ranges, the control unit outputs a drive signal to the grid-connection relay as the external command.

[0013] Another aspect of the present disclosure includes a motor having multiple windings, a first inverter connected between a first winding of the multiple windings and a battery, the first inverter converting AC power output by the motor into DC power and outputting the DC power to the battery when charging the battery with power from an AC power supply source, a second inverter connected to a second winding of the multiple windings, the second inverter converting DC power into AC power and outputting the AC power to the motor when charging the battery with power from the AC power supply source, a grid-connected relay connected to one end of the grid-connected relay and opening and closing the connection with the AC power supply source in response to an external command, a third inverter connected to the other end of the grid-connected relay and converting AC power from the AC power supply source connected via the grid-connected relay into DC power and outputting the DC power when charging the battery with power from the AC power supply source, and a third inverter connected to one end of the grid-connected relay and to the DC side of the second inverter and the other end of the grid-connected relay and opening and closing the connection with the second inverter in response to an external command. a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter and the grid-connection relay based on the inputs, and that charges the battery with power from the AC power supply source, the control unit including: a first relay switch that opens and closes a connection between a DC side of the inverter and a DC side of the third inverter; a measurement unit that measures the voltage and frequency of the AC power supply source; a battery monitoring unit that monitors a state of the battery; and a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter and the grid-connection relay based on the inputs, the control unit outputting a drive signal to the first relay switch as the external command when the battery is to be charged with power from the AC power supply source; and a step of outputting a drive signal to the grid-connection relay as the external command when the voltage and frequency of the AC power supply source measured by the measurement unit are within predetermined ranges.

[0014] Another aspect of the present disclosure includes a motor having multiple windings; a first inverter connected between one winding of the multiple windings and a battery, the first inverter converting AC power output by the motor into DC power and outputting the DC power to the battery when charging the battery, and converting DC power from the battery into AC power and outputting the DC power to the motor when discharging the battery; a second inverter connected to the other winding of the multiple windings, the first inverter converting DC power into AC power and outputting the DC power to the motor when charging the battery, and converting AC power output by the motor into DC power and outputting the DC power when discharging the battery; an interconnection relay connected to an AC power supply source on one side and opening and closing a connection with the AC power supply source in response to an external command; and a third inverter connected to the other side of the interconnection relay, the third inverter converting AC power from the AC power supply source connected via the interconnection relay into DC power and outputting the DC power when charging the battery, and converting DC power output by the second inverter into AC power and outputting the AC power to the AC power supply source via the interconnection relay when discharging the battery; a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter, and the grid-connection relay based on the outputs; and a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter, and the grid-connection relay based on the outputs. The control method for charging and discharging a battery between the battery and the AC power supply source includes: a step of outputting a drive signal to the first relay switch as the external command when charging or discharging between the battery and the AC power supply source; and a step of outputting a drive signal to the grid-connection relay as the external command when charging or discharging between the battery and the AC power supply source when the voltage and frequency of the AC power supply source measured by the measurement unit are within predetermined ranges. [Effects of the Invention]

[0015] According to the present disclosure, with a simple configuration, it is possible to not only charge a battery from an AC power source but also supply (discharge) power from the battery to the AC power source. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic block diagram showing an example of the configuration of a charge / discharge system according to a first embodiment. [Figure 2] 1 is a diagram showing a part of the configuration of a charge / discharge system according to a first embodiment. [Figure 3] 4 is a flowchart showing an example of processing performed by a charge / discharge controller in the charge / discharge system according to the first embodiment. [Figure 4] FIG. 3 is a diagram showing an example of an output current waveform of the inverter in a charge / discharge mode according to the first embodiment. [Figure 5] FIG. 6 is a diagram showing another example of an output current waveform of the inverter in the charge / discharge mode according to the first embodiment. [Figure 6] 5 is a flowchart showing an example of a linkage relay control process when connected to a single-phase AC power supply system according to the first embodiment. [Figure 7] 5 is a flowchart showing an example of a linkage relay control process when connected to a three-phase AC power supply system according to the first embodiment. [Figure 8] 6 is a flowchart showing an example of a relay switch control process when a DC power bus is connected according to the first embodiment. [Figure 9] FIG. 4 is a diagram showing an example of another AC power supply source according to the first embodiment. [Figure 10] FIG. 10 is a schematic block diagram showing an example of the configuration of a charge / discharge system according to a second embodiment. [Figure 11] 10 is a flowchart showing an example of processing performed by a charge / discharge controller in a charge / discharge system according to a second embodiment. [Figure 12] 10 is a flowchart showing another example of the process performed by the charge / discharge controller during charging in the charge / discharge system according to the second embodiment. [Figure 13]10 is a flowchart showing another example of the process performed by the charge / discharge controller during discharge in the charge / discharge system according to the second embodiment. [Figure 14] FIG. 10 is a diagram showing another example of the connection of the third relay switch according to the second embodiment. [Figure 15] FIG. 10 is a diagram showing another example of the connection of the fourth relay switch according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments will be described with reference to the drawings. First Embodiment [Charging and discharging system configuration] Fig. 1 is a schematic block diagram showing an example of the configuration of a charge / discharge system according to this embodiment. The charge / discharge system 1 shown in Fig. 1 includes an electric vehicle 100, a single-phase AC power supply system 201 (single-phase AC power supply source), a three-phase AC power supply system 202 (three-phase AC power supply source), and a DC power supply bus 204 (direct current power supply source) generated by solar power generation or the like.

[0018] Electrically powered vehicle 100 includes a charge / discharge device 5, a battery 10, and inlets 111, 112, and 114. Charging / discharging device 5 is an on-board charging / discharging device mounted on electric vehicle 100. Charging / discharging device 5 includes a first inverter 21, a second inverter 22, a dual three-phase motor 3 including a first winding 31 and a second winding 32, a third inverter 23, a filter 6, a battery controller 15, a charge / discharge controller 25, grid-connected relays 71 and 72, relay switches 412, 423, and 424, relay switches 512, 523, and 524, and a measurement unit 8. Grid-connected relays 71 and 72 are configured by integrating a plurality of relay switches, and the contacts of the plurality of relay switches are interconnected to open and close. The interconnection relays 71 and 72, the relay switches 412, 423 and 424, and the relay switches 512, 523 and 524 are turned ON or OFF (contacts are opened or closed) by an external command (for example, a drive signal from the charge / discharge controller 25).

[0019] (Connection configuration between electric vehicle and external power supply system) First, a configuration for connecting electric vehicle 100 to an external power supply system will be described. Note that connection basically means an electrical connection. Inlets 111, 112, and 114 are provided as charging ports (an example of a connection section) for electric vehicle 100. A connector 121 is connected to single-phase AC power supply system 201, and electric vehicle 100 can be connected to single-phase AC power supply system 201 by connecting this connector 121 to inlet 111. A connector 122 is connected to three-phase AC power supply system 202, and electric vehicle 100 can be connected to three-phase AC power supply system 202 by connecting this connector 122 to inlet 112. A connector 124 is connected to DC power supply bus 204, and electric vehicle 100 can be connected to DC power supply bus 204 by connecting this connector 124 to inlet 114.

[0020] (Electric vehicle configuration) Next, the configuration of the charging / discharging system 1 on the side of the electric vehicle 100 will be described. The inlets 111 and 112 are connected to one side of the filter 6 via the grid-connection relays 71 and 72, respectively. The other side of the filter 6 is connected to the AC section (AC side) of the third inverter 23. The DC section (DC side) of the third inverter 23 is connected to the DC section (DC side) of the second inverter 22 via the relay switches 423 and 523.

[0021] The third inverter 23 is a bridge circuit using six IGBTs (Insulated Gate Bipolar Transistors) as switching devices (switching elements). Each of the six IGBTs is provided as a set with a diode (FWD: Free Wheeling Diode) connected in anti-parallel. When the power flow is in the direction of charging the battery 10, the third inverter 23 converts AC power input from a single-phase AC power supply system 201 connected to the inlet 111 via a connector 121 into DC power and outputs the DC power to the second inverter 22. On the other hand, when the power flow is in the direction of discharging the battery 10, the third inverter 23 converts DC power input from the second inverter 22 into AC power and outputs the AC power to the single-phase AC power supply system 201 connected to the inlet 111 via the connector 121. Alternatively, when the flow of power is in the direction of charging the battery 10, the third inverter 23 converts the AC power input from the three-phase AC power supply system 202 connected to the inlet 112 via the connector 122 into DC power and outputs it to the second inverter 22. On the other hand, when the flow of power is in the direction of discharging the battery 10, the third inverter 23 converts the DC power input from the second inverter 22 into AC power and outputs it to the three-phase AC power supply system 202 connected to the inlet 112 via the connector 122. Here, charging and discharging are defined in terms of the flow of power relative to the battery 10.

[0022] The inlet 114 is connected to the DC section (DC side) of the second inverter 22 via the relay switch 424 and the relay switch 524. That is, the relay switch 424 and the relay switch 524 are connected between the DC power supply bus 204 and the DC section (DC side) of the second inverter 22.

[0023] The first inverter 21 is a bridge circuit using six IGBTs as switching devices. Each of the six IGBTs is provided as a set with an anti-parallel-connected diode (FWD). In the first inverter 21, reference numeral 21aH denotes the IGBT and FWD of the U-phase upper arm, reference numeral 21bH denotes the IGBT and FWD of the V-phase upper arm, and reference numeral 21cH denotes the IGBT and FWD of the W-phase upper arm. In the first inverter 21, reference numeral 21aL denotes the IGBT and FWD of the U-phase lower arm, reference numeral 21bL denotes the IGBT and FWD of the V-phase lower arm, and reference numeral 21cL denotes the IGBT and FWD of the W-phase lower arm.

[0024] First inverter 21 is connected between first winding 31 of dual three-phase motor 3 and battery 10. First winding 31 of dual three-phase motor 3 is connected to the AC section (AC side) of first inverter 21, and battery 10 is connected to the DC section (DC side) of first inverter 21. When power is flowing in the direction discharging battery 10, first inverter 21 converts DC power input from battery 10 into AC power and outputs it to dual three-phase motor 3. On the other hand, when power is flowing in the direction charging battery 10, first inverter 21 converts AC power input from dual three-phase motor 3 into DC power and outputs it to battery 10.

[0025] The second inverter 22 is a bridge circuit using six IGBTs as switching devices. Each of the six IGBTs is provided as a set with an anti-parallel-connected diode (FWD). In the second inverter 22, reference numeral 22aH denotes the IGBT and FWD of the U-phase upper arm, reference numeral 22bH denotes the IGBT and FWD of the V-phase upper arm, and reference numeral 22cH denotes the IGBT and FWD of the W-phase upper arm. In the second inverter 22, reference numeral 22aL denotes the IGBT and FWD of the U-phase lower arm, reference numeral 22bL denotes the IGBT and FWD of the V-phase lower arm, and reference numeral 22cL denotes the IGBT and FWD of the W-phase lower arm.

[0026] The second inverter 22 is connected between the second winding 32 of the dual three-phase motor 3 and the battery 10. The second winding 32 of the dual three-phase motor 3 is connected to the AC section (AC side) of the second inverter 22, and the DC section (DC side) of the second inverter 22 is connected to the battery 10 and the DC section (DC side) of the first inverter 21 via the relay switch 412 and the relay switch 512. That is, the relay switch 412 and the relay switch 512 are connected between the battery 10 and the DC section (DC side) of the second inverter 22. When the power flow is in the direction to charge the battery 10, the second inverter 22 converts DC power input from the DC power supply bus 204 connected to the inlet 114 via the connector 124 or the third inverter 23 into AC power and outputs the AC power to the dual three-phase motor 3. On the other hand, when the flow of power is in the direction of discharging from the battery 10, the second inverter 22 converts the AC power input from the dual three-phase motor 3 into DC power and outputs it to the third inverter 23 or the DC power bus 204 connected to the inlet 114 via the connector 124.

[0027] 2 is a diagram showing part of the configuration of the charge / discharge system shown in FIG. 1, redrawing the connections between the first inverter 21, the first winding 31 and the second winding 32 of the dual three-phase motor 3, and the second inverter 22 as an electrical circuit diagram. The dual three-phase motor 3 has the first winding 31 and the second winding 32 wound on a single stator core, and can be regarded as a three-phase isolated transformer. The first inverter 21 connected to the first winding 31 and the second inverter 22 connected to the second winding 32 can be regarded as forming an isolated DC-DC converter circuit, which operates as follows.

[0028] When power flows in the direction of charging battery 10, second inverter 22 converts DC power to three-phase AC power and outputs it, causing a three-phase AC voltage to be applied to second winding 32 of dual three-phase motor 3, and three-phase AC power to be induced in first winding 31, which is magnetically coupled to second winding 32. The induced three-phase AC power is rectified by first inverter 21 and converted into DC power. On the other hand, when power flows in the direction of discharging battery 10, first inverter 21 converts DC power to three-phase AC power and outputs it, causing a three-phase AC voltage to be applied to first winding 31 of dual three-phase motor 3, and three-phase AC power to be induced in second winding 32, which is magnetically coupled to first winding 31. The induced three-phase AC power is rectified by second inverter 22 and converted into DC power.

[0029] Returning to FIG. 1 , the measurement unit 8 measures the voltage and frequency of the connected lines. The measurement unit 8 is connected to the lines of each phase of the single-phase AC power supply system 201 between the interconnection relay 71 and the inlet 111. The measurement unit 8 is also connected to the lines of each phase of the three-phase AC power supply system 202 between the interconnection relay 72 and the inlet 112. The measurement unit 8 is also connected to the positive and negative lines of the DC power supply bus between the relay switches 424 and 524 and the inlet 114. The measurement unit 8 is further connected to the charge / discharge controller 25 by control lines.

[0030] The battery 10 is a secondary battery that stores power to be supplied to an electric motor that serves as a power source for the electric vehicle 100, and is configured to be charged and discharged in the charge / discharge system 1. A control line from the battery 10 is connected to a battery controller 15. The battery controller 15 monitors the state of the battery 10 using the control line from the battery 10. The control line from the battery 10 is further connected to a charge / discharge controller 25.

[0031] The charge / discharge controller 25 is connected to each of the first inverter 21, the second inverter 22, the third inverter 23, the battery controller 15, the grid-connected relays 71 and 72, the relay switches 412, 423 and 424, the relay switches 512, 523 and 524, and the measurement unit 8 via control lines.

[0032] The charge / discharge controller 25 acquires status information indicating the status of the battery 10 using a control line from the battery controller 15, and controls the charging operation of the battery 10 based on the acquired status information of the battery 10. For example, the charge / discharge controller 25 outputs drive signals to the first inverter 21, the second inverter 22, the third inverter 23, the grid-connected relays 71 and 72, the relay switches 412, 423, and 424, and the relay switches 512, 523, and 524 based on the status information of the battery 10 acquired from the battery controller 15.

[0033] Furthermore, when charging the battery 10 with power from an external power supply system, the charge / discharge controller 25 determines whether the battery 10 is connected to the single-phase AC power supply system 201, the three-phase AC power supply system 202, or the DC power supply bus 204, and controls the interconnection relays 71, 72, relay switches 412, 423, 424, and relay switches 512, 523, 524 to be turned ON (contacts closed) or OFF (contacts open) depending on the determination result.

[0034] As an example, when charging the battery 10 with power from the DC power bus 204, the charge / discharge controller 25 outputs a drive signal to the relay switches 412 and 512 to turn the relay switches 412 and 512 OFF, and also outputs a drive signal to the relay switches 424 and 524 to turn the relay switches 424 and 524 ON. On the other hand, when not charging the battery 10 with power from the DC power bus 204, the charge / discharge controller 25 outputs a drive signal to the relay switches 412 and 512 to turn the relay switches 412 and 512 ON, and also outputs a drive signal to the relay switches 424 and 524 to turn the relay switches 424 and 524 OFF. The charging process performed by the charge / discharge controller 25 will be described in detail below.

[0035] [Charging and discharging system operation] Next, the processing operations performed by the charge / discharge controller 25 in the charge / discharge system 1 according to this embodiment will be described with reference to Fig. 1 and Fig. 3. Below, the explanation will be divided into <1(1) Operation when the electric vehicle is traveling>, <1(2) Charging / discharging operation between the battery and a single-phase AC power supply system>, <1(3) Charging / discharging operation between the battery and a three-phase AC power supply system>, and <1(4) Charging / discharging operation between the battery and a DC power supply bus>. Hereinafter, a drive signal that turns on the relay switch will be referred to as an "ON signal," and a drive signal that turns off the relay switch will be referred to as an "OFF signal." In addition, an operation mode in which charging / discharging (charging or discharging) between the battery 10 and an external power supply system while the electric vehicle 100 is stopped will be referred to as a "charge / discharge mode."

[0036] FIG. 3 is a flowchart showing an example of processing performed by the charge / discharge controller in the charge / discharge system according to this embodiment.

[0037] (Step S101) The charge / discharge controller 25 determines whether or not the charge / discharge mode is in effect. If the charge / discharge controller 25 determines that the charge / discharge mode is not in effect (NO), the process proceeds to step S103, where the charge / discharge controller 25 performs an operation for when the electric vehicle is running.

[0038] <1(1) Operation of electric vehicles when driving> (Step S103) When not in the charge / discharge mode (for example, when the electric vehicle 100 is traveling), the charge / discharge controller 25 controls the opening and closing of the contacts of the relay switches as follows. The charge / discharge controller 25 outputs an OFF signal to the relay switches 423 and 424 and the relay switches 523 and 524 to open the contacts of these relay switches. The charge / discharge controller 25 also outputs an ON signal to the relay switches 412 and 512 to close the contacts of these relay switches. As a result, the DC section (DC side) of the second inverter 22 is connected only to the battery 10 and the DC section (DC side) of the first inverter 21. The charge / discharge controller 25 also outputs an OFF signal to the grid-connection relays 71 and 72 to open the contacts of these grid-connection relays. As a result, the AC section (AC side) of the third inverter 23 and the filter 6 are disconnected from the inlets 111 and 112, the single-phase AC power supply system 201, and the three-phase AC power supply system 202.

[0039] The charge / discharge controller 25 outputs gate drive signals to the first inverter 21 and the second inverter 22, causing the first inverter 21 and the second inverter 22 to output sinusoidal three-phase AC current, thereby driving the dual three-phase motor 3 to rotate.

[0040] On the other hand, if the charge / discharge controller 25 determines that the electric vehicle 100 is stopped and is in the charge / discharge mode in step S101 (YES), the process proceeds to step S105.

[0041] (Step S105) The charge / discharge controller 25 determines whether or not the connector 121 of the single-phase AC power supply system 201 is connected to the inlet 111. If the charge / discharge controller 25 determines that the connector 121 of the single-phase AC power supply system 201 is connected to the inlet 111 (YES), the process proceeds to step S107, and shifts to processing for performing a charge / discharge operation between the battery 10 and the single-phase AC power supply system 201.

[0042] <1(2) Charging and discharging between the battery and the single-phase AC power supply system> (Step S107) The charge / discharge controller 25 controls the operation of charging and discharging between the battery 10 and the single-phase AC power supply system 201. When charging the battery 10 with power from the single-phase AC power supply system 201, the charge / discharge controller 25 controls the opening and closing of the contacts of the relay switch as follows.

[0043] The charge / discharge controller 25 outputs an OFF signal to the relay switches 412, 424 and the relay switches 512, 524, thereby opening the contacts of these relay switches. The charge / discharge controller 25 also outputs an ON signal to the relay switches 423 and 523, thereby closing the contacts of these relay switches. This places the DC section (DC side) of the second inverter connected only to the DC section (DC side) of the third inverter 23. Furthermore, the charge / discharge controller 25 outputs an OFF signal to the grid-connection relay 72, thereby opening the contacts of the grid-connection relay 72. This places the AC section (AC side) of the third inverter 23 and the filter 6 in a state of being disconnected from the inlet 112 and the three-phase AC power supply system 202.

[0044] Furthermore, the charge / discharge controller 25 controls the opening and closing of the contacts of the grid-connection relay 71 based on the measurement values ​​of the voltage and frequency of the single-phase AC power supply system 201 by the measurement unit 8 (see FIG. 6 described later). For example, when the inter-phase voltage and frequency of the single-phase AC power supply system 201 are within a predetermined range, the charge / discharge controller 25 outputs an ON signal to the grid-connection relay 71 to close the contacts of the grid-connection relay 71. As a result, the AC section (AC side) of the third inverter 23 and the filter 6 are connected to the single-phase AC power supply system 201 via the grid-connection relay 71, the inlet 111, and the connector 121. The process of outputting an ON signal to the grid-connection relay 71 will be described in detail below with reference to the flowchart shown in FIG. 6.

[0045] Next, we will first explain the operation of power conversion when the flow of power is in the direction of charging the battery 10. The charge / discharge controller 25 outputs a gate drive signal to the third inverter 23 to control it so that the power factor of the power flowing from the single-phase AC power supply system 201 to the third inverter 23 is 1 and so that the DC voltage of the third inverter 23 is higher than the voltage of the battery 10. At this time, the operation of the third inverter 23 converts the AC power from the single-phase AC power supply system 201 into DC power, and inputs it to the DC section (DC side) of the second inverter 22.

[0046] The charge / discharge controller 25 outputs a gate drive signal to the second inverter 22 and controls the output current of the second inverter 22 to have a current waveform that causes the dual three-phase motor 3 to stop rotating.

[0047] FIG. 4 shows an example of the inverter output current waveform in the charge / discharge mode according to this embodiment. For example, as shown in FIG. 4, the charge / discharge controller 25 controls the U-, V-, and W-phase currents so that the output current waveform of the second inverter 22 becomes a high-frequency AC current waveform that causes the magnetic field inside the dual three-phase motor 3 to become a high-frequency alternating magnetic field and stops the dual three-phase motor 3 from rotating. Here, high frequency refers to 100 Hz or higher, and a frequency of 1 kHz or higher can further suppress the effects of pulsating rotational torque. The charge / discharge controller 25 also outputs gate drive signals to the first inverter 21 to turn off all IGBTs, causing the first inverter 21 to operate as a rectifier circuit. By passing currents with waveforms that are out of phase with each other by 0° or 180°, as shown in FIG. 4, the output torque fluctuates at the same frequency as the fluctuations in the phase current of the second winding 32, thereby suppressing the DC torque component generated in the second winding 32 of the dual three-phase motor 3.

[0048] When the high-frequency AC current output from the second inverter 22 flows through the second winding 32 of the dual three-phase motor 3, the dual three-phase motor 3 operates as a current transformer (CT). A current flows through the first winding 31 to cancel out the magnetic flux in the iron core of the dual three-phase motor 3. This current is rectified by the first inverter 21 and charges the battery 10. In other words, the current flowing through each phase of the first winding 31 fluctuates at the same frequency as the fluctuations in the phase current of the second winding 32, thereby suppressing the DC torque components generated in the second windings 31 and 32 of the dual three-phase motor 3. Because the dual three-phase motor 3 is configured as a multi-inertia system, gain characteristics are reduced in the range higher than the resonant frequency determined by inertia. Therefore, when the output torque fluctuates at the frequency of this embodiment, this does not appear in the rotational behavior, effectively stopping the rotation. Furthermore, the sliding resistance of the entire multi-inertia system, including the dual three-phase motor 3, also acts to promote rotational stopping. Furthermore, the battery controller 15 monitors the state of the battery 10. The charge / discharge controller 25 acquires state information of the battery 10 from the battery controller 15, and controls the above-described charging operation based on the acquired state information of the battery 10.

[0049] Next, the operation of power conversion when power is flowing in the direction of discharging from the battery 10 to the single-phase AC power supply system 201 will be described. The charge / discharge controller 25 outputs a gate drive signal to the first inverter 21 and controls the output current of the first inverter 21 to have a high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating. For example, as shown in FIG. 4, the charge / discharge controller 25 controls the magnetic field inside the dual three-phase motor 3 to become a high-frequency alternating magnetic field, resulting in a high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating. In addition, the charge / discharge controller 25 outputs a gate drive signal to the second inverter 22 to turn off all IGBTs, causing the second inverter 22 to operate as a rectifier circuit.

[0050] At this time, when the high-frequency AC current output from the first inverter 21 flows through the first winding 31 of the dual three-phase motor 3, the dual three-phase motor 3 operates as a current transformer (CT), and a current flows through the second winding 32 so as to cancel out the magnetic flux in the iron core of the dual three-phase motor 3. This current is rectified by the second inverter 22 and input to the third inverter 23. In addition, the charge / discharge controller 25 outputs a gate drive signal to the third inverter 23 to control the third inverter 23 so that the power factor of the power flowing from the third inverter 23 to the single-phase AC power supply system 201 becomes 1 and so that the DC voltage of the third inverter 23 is lower than the voltage of the battery 10. At this time, the operation of the third inverter 23 converts the DC power input to the third inverter 23 into AC power, which is output to the single-phase AC power supply system 201 via the filter 6, the grid-connection relay 71, the inlet 111, and the connector 121. In addition, the battery controller 15 monitors the state of the battery 10. The charge / discharge controller 25 acquires the state information of the battery 10 from the battery controller 15, and controls the above-mentioned discharge operation based on the acquired state information of the battery 10.

[0051] In the above description, the output current of the first inverter 21 or the second inverter 22 is controlled to have the high-frequency AC current waveform shown in Fig. 4 during charging and discharging, which causes the magnetic field inside the dual three-phase motor 3 to become a high-frequency alternating magnetic field and stops the rotation of the dual three-phase motor 3. However, the present invention is not limited to this. Any current waveform that stops the rotation of the dual three-phase motor 3 will suffice, and the output current may be controlled to have the high-frequency AC current waveform shown in Fig. 5, for example.

[0052] Fig. 5 is a diagram showing another example of the output current waveform of the inverter in the charge / discharge mode according to this embodiment. During the charge and discharge operations, the charge / discharge controller 25 may control the current waveform of the output current of the first inverter 21 or the second inverter 22 so that it becomes a high-frequency AC current waveform (high-frequency alternating current or zero current with coincident zero-cross timings) that causes the dual three-phase motor 3 to stop rotating, as shown in Fig. 5.

[0053] For example, when charging and discharging between the battery 10 and the single-phase AC power supply system 201, the waveform of the output current of each phase of the second inverter 22 may be an alternating current or a zero current with the same zero-cross timing, and the sum of the currents of each phase may be zero.

[0054] During charging and discharging operations, if the inter-phase voltage and frequency of the single-phase AC power supply system 201 deviate from a predetermined range based on the measured values ​​of the voltage and frequency of the single-phase AC power supply system 201 measured by the measurement unit 8, the charge / discharge controller 25 outputs an OFF signal to the grid-connection relay 71 to open the contacts of the grid-connection relay 71 (see FIG. 6 described later) and turn OFF the gate drive signals of all inverters. As a result, the AC section (AC side) of the third inverter 23 and the filter 6 are disconnected from the inlet 111, the connector 121, and the single-phase AC power supply system 201, and charging and discharging operations are stopped. These functions are equivalent to those of a grid-connection protection device.

[0055] Here, with reference to Fig. 6, an explanation will be given of the operation of the linked relay control process in which the charge / discharge controller 25 outputs an ON signal or OFF signal to the grid-connected relay 71 to control the opening and closing of the contacts of the grid-connected relay 71 during charging / discharging operations between the battery 10 and the single-phase AC power supply system 201. Fig. 6 is a flowchart showing an example of the linked relay control process when connected to the single-phase AC power supply system according to this embodiment. Here, an example of the process is shown in which the single-phase AC power supply system 201 is a single-phase three-wire system with a standard voltage between each phase of 101 Vrms and a standard frequency of 60 Hz as a specific example.

[0056] (Step S121) The charge / discharge controller 25 determines whether or not a command to start a charge / discharge operation has been received. The command to start a charge / discharge operation corresponds to, for example, determining that the charge / discharge mode is being set in step S101 in FIG. 3. When the charge / discharge controller 25 determines that a command to start a charge / discharge operation has not been received (NO), it outputs an OFF signal to the interconnection relay 71, opening the contacts of the interconnection relay 71 (step S122). This process corresponds to the process of outputting an OFF signal to the interconnection relay 71 in step S103 in FIG. 3 (processing when a charge / discharge operation is not being performed).

[0057] On the other hand, when it is determined in step S121 that a command to start a charge / discharge operation has been received (YES), the charge / discharge controller 25 determines whether the voltage and frequency of the single-phase AC power supply system 201 measured by the measurement unit 8 are within predetermined ranges by performing an overvoltage determination (steps S123, S124), an undervoltage determination (steps S125, S126), an overfrequency determination (steps S127, S128), and an underfrequency determination (steps S129, S130), and controls whether to output an ON signal or an OFF signal to the interconnection relay 71 according to the determination result. First, the charge / discharge controller 25 proceeds to step S123.

[0058] (Step S123) The charge / discharge controller 25 determines whether the U-phase-to-neutral voltage (effective value) of the single-phase AC power supply system 201 measured by the measurement unit 8 has exceeded a predetermined voltage (e.g., 115 Vrms) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 71 to open the contacts of the interconnection relay 71 (step S132). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the single-phase AC power supply system 201, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S124.

[0059] (Step S124) The charge / discharge controller 25 determines whether the W-phase-to-neutral voltage (effective value) of the single-phase AC power supply system 201 measured by the measurement unit 8 has exceeded a predetermined voltage (e.g., 115 Vrms) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 71 to open the contacts of the interconnection relay 71 (step S132). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the single-phase AC power supply system 201, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S125.

[0060] (Step S125) The charge / discharge controller 25 determines whether the U-phase-to-neutral voltage (effective value) of the single-phase AC power supply system 201 measured by the measurement unit 8 has remained below a predetermined voltage (e.g., 80 Vrms) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 71 to open the contacts of the interconnection relay 71 (step S132). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the single-phase AC power supply system 201, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S126.

[0061] (Step S126) The charge / discharge controller 25 determines whether the W-phase-to-neutral voltage (effective value) of the single-phase AC power supply system 201 measured by the measurement unit 8 has remained below a predetermined voltage (e.g., 80 Vrms) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 71 to open the contacts of the interconnection relay 71 (step S132). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the single-phase AC power supply system 201, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S127.

[0062] (Step S127) The charge / discharge controller 25 determines whether the U-phase-neutral frequency of the single-phase AC power supply system 201 measured by the measurement unit 8 exceeds a predetermined frequency (e.g., 61.2 Hz) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 71 to open the contacts of the interconnection relay 71 (step S132). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the single-phase AC power supply system 201, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S128.

[0063] (Step S128) The charge / discharge controller 25 determines whether the W-phase-to-neutral frequency of the single-phase AC power supply system 201 measured by the measurement unit 8 exceeds a predetermined frequency (e.g., 61.2 Hz) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 71 to open the contacts of the interconnection relay 71 (step S132). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the single-phase AC power supply system 201, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S129.

[0064] (Step S129) The charge / discharge controller 25 determines whether the U-phase-to-neutral frequency of the single-phase AC power supply system 201 measured by the measurement unit 8 has been below a predetermined frequency (for example, 58.8 Hz) for a predetermined time (for example, 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 71 to open the contacts of the interconnection relay 71 (step S132). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the single-phase AC power supply system 201, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S130.

[0065] (Step S130) The charge / discharge controller 25 determines whether the W-phase-to-neutral frequency of the single-phase AC power supply system 201 measured by the measurement unit 8 has been below a predetermined frequency (for example, 58.8 Hz) for a predetermined time (for example, 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 71 to open the contacts of the interconnection relay 71 (step S132). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the single-phase AC power supply system 201, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S131.

[0066] (Step S131) ​​The charge / discharge controller 25 outputs an ON signal to the grid-connection relay 71 to close the contact of the grid-connection relay 71. As a result, the AC section (AC side) of the third inverter 23 and the filter 6 are connected to the single-phase AC power supply system 201 via the grid-connection relay 71, the inlet 111, and the connector 121, and enter a normal operating state in which charge / discharge operations are possible.

[0067] In this way, if the determination results are all false (NO) in the overvoltage determination (steps S123, S124), the undervoltage determination (steps S125, S126), the overfrequency determination (steps S127, S128), and the underfrequency determination (steps S129, S130), the charge / discharge controller 25 determines that the interphase voltages and frequency of the single-phase AC power supply system 201 are within predetermined ranges and outputs an ON signal to the interconnection relay 71. This closes the contacts of the interconnection relay 71, and the AC section (AC side) of the third inverter 23 and the filter 6 are connected to the single-phase AC power supply system 201 via the interconnection relay 71, the inlet 111, and the connector 121, thereby entering a normal operating state in which charging and discharging operations are possible.

[0068] On the other hand, if any one of the determination results of the overvoltage determination (steps S123, S124), the undervoltage determination (steps S125, S126), the overfrequency determination (steps S127, S128), and the underfrequency determination (steps S129, S130) is true (YES), the charge / discharge controller 25 determines that the interphase voltage and frequency of the single-phase AC power supply system 201 have deviated from the predetermined ranges, and outputs an OFF signal to the grid-connection relay 71. This opens the contacts of the grid-connection relay 71, disconnects the AC section (AC side) of the third inverter 23 and the filter 6 from the inlet 111, the connector 121, and the single-phase AC power supply system 201, and stops the charge / discharge operation.

[0069] Returning to FIG. 3, if the charge / discharge controller 25 determines in step S105 that the connector 121 of the single-phase AC power supply system 201 is not connected to the inlet 111 (NO), the process proceeds to step S109.

[0070] (Step S109) The charge / discharge controller 25 determines whether or not the connector 122 of the three-phase AC power supply system 202 is connected to the inlet 112. If the charge / discharge controller 25 determines that the connector 122 of the three-phase AC power supply system 202 is connected to the inlet 112 (YES), the process proceeds to step S111, and shifts to processing for performing a charge / discharge operation between the battery 10 and the three-phase AC power supply system 202.

[0071] <1(3) Charging and discharging between the battery and the three-phase AC power supply system> (Step S111) The charge / discharge controller 25 controls the operation of charging and discharging between the battery 10 and the three-phase AC power supply system 202. When charging the battery 10 with power from the three-phase AC power supply system 202, the charge / discharge controller 25 controls the opening and closing of the contacts of the relay switch as follows.

[0072] The charge / discharge controller 25 outputs an OFF signal to the relay switches 412, 424 and the relay switches 512, 524, thereby opening the contacts of these relay switches. The charge / discharge controller 25 also outputs an ON signal to the relay switches 423 and 523, thereby closing the contacts of these relay switches. This causes the DC section (DC side) of the second inverter 22 to be connected only to the DC section (DC side) of the third inverter 23. Furthermore, the charge / discharge controller 25 outputs an OFF signal to the grid-connection relay 71, thereby opening the contacts of the grid-connection relay 71. This causes the AC section (AC side) of the third inverter 23 and the filter 6 to be disconnected from the inlet 111 and the single-phase AC power supply system 201.

[0073] Furthermore, the charge / discharge controller 25 controls the opening and closing of the contacts of the grid-connection relay 72 based on the measurement values ​​of the voltage and frequency of the three-phase AC power supply system 202 by the measurement unit 8 (see FIG. 7 described later). For example, when the inter-phase voltage and frequency of the three-phase AC power supply system 202 are within a predetermined range, the charge / discharge controller 25 outputs an ON signal to the grid-connection relay 72 to close the contacts of the grid-connection relay 72. As a result, the AC section (AC side) of the third inverter 23 and the filter 6 are connected to the three-phase AC power supply system 202 via the grid-connection relay 72, the inlet 112, and the connector 122. The process of outputting an ON signal to the grid-connection relay 72 will be described in detail below with reference to the flowchart shown in FIG. 7.

[0074] The subsequent operation is the same as in <1(2) Charging and discharging operation between the battery and the single-phase AC power supply system> described above, and first, the operation of power conversion when the flow of power is in the direction of charging the battery 10 will be described. The charge and discharge controller 25 outputs a gate drive signal to the third inverter 23 to control it so that the power factor of the power flowing from the three-phase AC power supply system 202 to the third inverter 23 is 1 and so that the DC voltage of the third inverter 23 is higher than the voltage of the battery 10. At this time, the operation of the third inverter 23 converts the AC power from the three-phase AC power supply system 202 into DC power, which is input to the DC section (DC side) of the second inverter.

[0075] The charge / discharge controller 25 outputs a gate drive signal to the second inverter 22 and controls the output current of the second inverter 22 to have a current waveform that stops the rotation of the dual three-phase motor 3. For example, as shown in Fig. 4, the charge / discharge controller 25 controls the U-phase, V-phase, and W-phase currents so that the magnetic field inside the dual three-phase motor 3 becomes a high-frequency alternating magnetic field and a high-frequency AC current waveform that stops the rotation of the dual three-phase motor 3. The charge / discharge controller 25 also outputs a gate drive signal to the first inverter 21 to turn off all IGBTs, causing the first inverter 21 to operate as a rectifier circuit.

[0076] At this time, when the high-frequency AC current output by second inverter 22 flows through second winding 32 of dual three-phase motor 3, dual three-phase motor 3 operates as a current transformer (CT), and a current flows through first winding 31 so as to cancel out the magnetic flux in the iron core of dual three-phase motor 3. This current is rectified by first inverter 21 and charges battery 10. Battery controller 15 also monitors the state of battery 10. Charge / discharge controller 25 acquires state information of battery 10 from battery controller 15 and controls the above-mentioned charging operation based on the acquired state information of battery 10.

[0077] Next, the operation of power conversion when power is flowing in the direction of discharging from the battery 10 to the three-phase AC power supply system 202 will be described. The charge / discharge controller 25 outputs a gate drive signal to the first inverter 21 and controls the output current of the first inverter 21 to have a current waveform that stops the dual three-phase motor 3 from rotating. For example, as shown in FIG. 4, the charge / discharge controller 25 controls the output current so that the magnetic field inside the dual three-phase motor 3 becomes a high-frequency alternating magnetic field and a high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating. In addition, the charge / discharge controller 25 outputs a gate drive signal to the second inverter 22 to turn off all IGBTs, causing the second inverter 22 to operate as a rectifier circuit.

[0078] At this time, when the high-frequency AC current output from the first inverter 21 flows through the first winding 31 of the dual three-phase motor 3, the dual three-phase motor 3 operates as a current transformer (CT), and a current flows through the second winding 32 so as to cancel out the magnetic flux in the iron core of the dual three-phase motor 3. This current is rectified by the second inverter 22 and input to the third inverter 23. In addition, the charge / discharge controller 25 outputs a gate drive signal to the third inverter 23 to control the third inverter 23 so that the power factor of the power flowing from the third inverter 23 to the three-phase AC power supply system 202 is 1 and so that the DC voltage of the third inverter 23 is lower than the voltage of the battery 10. At this time, the operation of the third inverter 23 converts the DC power input to the third inverter 23 into AC power, which is output to the three-phase AC power supply system 202 via the filter 6, the grid-connection relay 72, the inlet 112, and the connector 122. In addition, the battery controller 15 monitors the state of the battery 10. The charge / discharge controller 25 acquires the state information of the battery 10 from the battery controller 15, and controls the above-mentioned discharge operation based on the acquired state information of the battery 10.

[0079] In the above description, the output current of the first inverter 21 or the second inverter 22 is controlled to have the high-frequency AC current waveform shown in Fig. 4 during charging and discharging operations, in which the magnetic field inside the dual three-phase motor 3 becomes a high-frequency alternating magnetic field and the dual three-phase motor 3 stops rotating. However, the present invention is not limited to this. Any current waveform that stops the dual three-phase motor 3 from rotating will suffice. For example, the charge / discharge controller 25 may control the output current to have the high-frequency AC current waveform shown in Fig. 5 (alternating current or zero current with synchronized zero-cross timing).

[0080] Furthermore, during charging and discharging operations, if the inter-phase voltage and frequency of the three-phase AC power supply system 202 deviate from a predetermined range based on the measured values ​​of the voltage and frequency of the three-phase AC power supply system 202 measured by the measurement unit 8, the charge / discharge controller 25 outputs an OFF signal to the grid-connection relay 72 to open the contacts of the grid-connection relay 72 (see FIG. 7 described later), and turns OFF the gate drive signals of all inverters. As a result, the AC section (AC side) of the third inverter 23 and the filter 6 are disconnected from the inlet 112, the connector 122, and the three-phase AC power supply system 202, and charging and discharging operations are stopped. These functions are equivalent to those of a grid-connection protection device.

[0081] 7, the operation of the linked relay control process in which the charge / discharge controller 25 outputs an ON signal or OFF signal to the grid-connected relay 72 to control the opening and closing of the contacts of the grid-connected relay 72 during charging / discharging operations between the battery 10 and the three-phase AC power supply system 202 will be described. Fig. 7 is a flowchart showing an example of the linked relay control process when the three-phase AC power supply system is connected according to this embodiment. Here, an example of the process is shown in which the three-phase AC power supply system 202 is a three-phase, three-wire system with a standard voltage between each phase of 202 Vrms and a standard frequency of 60 Hz as a specific example.

[0082] (Step S141) The charge / discharge controller 25 determines whether or not a command to start a charge / discharge operation has been received. The command to start a charge / discharge operation corresponds to, for example, determining that the charge / discharge mode is in the charge / discharge mode in step S101 of FIG. 3. When the charge / discharge controller 25 determines that a command to start a charge / discharge operation has not been received (NO), it outputs an OFF signal to the interconnection relay 72 and opens the contact of the interconnection relay 72 (step S142). This process corresponds to the process of outputting an OFF signal to the interconnection relay 72 in step S103 of FIG. 3 (processing when a charge / discharge operation is not being performed).

[0083] On the other hand, when it is determined in step S141 that a command to start a charge / discharge operation has been received (YES), the charge / discharge controller 25 determines whether the voltage and frequency of the three-phase AC power supply system 202 measured by the measurement unit 8 are within predetermined ranges by performing an overvoltage determination (steps S143 to S145), an undervoltage determination (steps S146 to S148), an overfrequency determination (steps S149 to S151), and an underfrequency determination (steps S152 to S154), and controls whether to output an ON signal or an OFF signal to the interconnection relay 72 according to the determination result. First, the charge / discharge controller 25 proceeds to step S143.

[0084] (Step S143) The charge / discharge controller 25 determines whether the voltage (effective value) between the U phase and the V phase of the three-phase AC power supply system 202 measured by the measurement unit 8 exceeds a predetermined voltage (e.g., 230 Vrms) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 72 to open the contact of the interconnection relay 72 (step S156). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the three-phase AC power supply system 202, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S144.

[0085] (Step S144) The charge / discharge controller 25 determines whether the voltage (effective value) between the V phase and the W phase of the three-phase AC power supply system 202 measured by the measurement unit 8 exceeds a predetermined voltage (e.g., 230 Vrms) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 72 to open the contacts of the interconnection relay 72 (step S156). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the three-phase AC power supply system 202, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S145.

[0086] (Step S145) The charge / discharge controller 25 determines whether the voltage (effective value) between the W phase and the U phase of the three-phase AC power supply system 202 measured by the measurement unit 8 exceeds a predetermined voltage (e.g., 230 Vrms) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 72 to open the contacts of the interconnection relay 72 (step S156). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the three-phase AC power supply system 202, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S146.

[0087] (Step S146) The charge / discharge controller 25 determines whether the U-phase-V-phase voltage (effective value) of the three-phase AC power supply system 202 measured by the measurement unit 8 has remained below a predetermined voltage (e.g., 160 Vrms) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 72 to open the contacts of the interconnection relay 72 (step S156). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the three-phase AC power supply system 202, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S147.

[0088] (Step S147) The charge / discharge controller 25 determines whether the voltage (effective value) between the V phase and the W phase of the three-phase AC power supply system 202 measured by the measurement unit 8 has remained below a predetermined voltage (e.g., 160 Vrms) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 72 to open the contacts of the interconnection relay 72 (step S156). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the three-phase AC power supply system 202, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S148.

[0089] (Step S148) The charge / discharge controller 25 determines whether the voltage (effective value) between the W phase and the U phase of the three-phase AC power supply system 202 measured by the measurement unit 8 has remained below a predetermined voltage (e.g., 160 Vrms) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 72 to open the contacts of the interconnection relay 72 (step S156). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the three-phase AC power supply system 202, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S149.

[0090] (Step S149) The charge / discharge controller 25 determines whether the U-phase-V-phase frequency of the three-phase AC power supply system 202 measured by the measurement unit 8 has exceeded a predetermined frequency (e.g., 61.2 Hz) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 72 to open the contacts of the interconnection relay 72 (step S156). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the three-phase AC power supply system 202, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 returns to step S150 Proceed to.

[0091] (Step S150) The charge / discharge controller 25 determines whether the V-phase-W-phase frequency of the three-phase AC power supply system 202 measured by the measurement unit 8 has exceeded a predetermined frequency (e.g., 61.2 Hz) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 72 to open the contacts of the interconnection relay 72 (step S156). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the three-phase AC power supply system 202, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S151.

[0092] (Step S151) The charge / discharge controller 25 determines whether the W-phase-U-phase frequency of the three-phase AC power supply system 202 measured by the measurement unit 8 has exceeded a predetermined frequency (e.g., 61.2 Hz) for a predetermined time (e.g., 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 72 to open the contacts of the interconnection relay 72 (step S156). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the three-phase AC power supply system 202, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S152.

[0093] (Step S152) The charge / discharge controller 25 determines whether the U-phase-V-phase frequency of the three-phase AC power supply system 202 measured by the measurement unit 8 has been below a predetermined frequency (for example, 58.8 Hz) for a predetermined time (for example, 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 72 to open the contacts of the interconnection relay 72 (step S156). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the three-phase AC power supply system 202, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S153.

[0094] (Step S153) The charge / discharge controller 25 determines whether the V-phase-W-phase frequency of the three-phase AC power supply system 202 measured by the measurement unit 8 has been below a predetermined frequency (for example, 58.8 Hz) for a predetermined time (for example, 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 72 to open the contacts of the interconnection relay 72 (step S156). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the three-phase AC power supply system 202, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S154.

[0095] (Step S154) The charge / discharge controller 25 determines whether the W-phase-U-phase frequency of the three-phase AC power supply system 202 measured by the measurement unit 8 has been below a predetermined frequency (for example, 58.8 Hz) for a predetermined time (for example, 1.0 second). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the interconnection relay 72 to open the contacts of the interconnection relay 72 (step S156). As a result, as a protective operation, the third inverter 23 and the filter 6 are disconnected from the three-phase AC power supply system 202, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S155.

[0096] (Step S155) The charge / discharge controller 25 outputs an ON signal to the grid-connection relay 72 to close the contact of the grid-connection relay 72. As a result, the AC section (AC side) of the third inverter 23 and the filter 6 are connected to the three-phase AC power supply system 202 via the grid-connection relay 72, the inlet 112, and the connector 122, and enter a normal operating state in which charge / discharge operations are possible.

[0097] In this way, if the determination results are all false (NO) in all of the overvoltage determination (steps S143 to S145), undervoltage determination (steps S146 to S148), overfrequency determination (steps S149 to S151), and underfrequency determination (steps S152 to S154), the charge / discharge controller 25 determines that the interphase voltages and frequency of the three-phase AC power supply system 202 are within predetermined ranges and outputs an ON signal to the interconnection relay 72. This closes the contacts of the interconnection relay 72, and the AC section (AC side) of the third inverter 23 and the filter 6 are connected to the three-phase AC power supply system 202 via the interconnection relay 72, the inlet 112, and the connector 122, thereby entering a normal operating state in which charging and discharging operations are possible.

[0098] On the other hand, if the result of any one of the determinations of overvoltage (steps S143 to S145), undervoltage (steps S146 to S148), overfrequency (steps S149 to S151), and underfrequency (steps S152 to S154) is true (YES), the charge / discharge controller 25 determines that the interphase voltages and frequency of the three-phase AC power supply system 202 have deviated from predetermined ranges, and outputs an OFF signal to the grid-connection relay 72. This opens the contacts of the grid-connection relay 72, disconnects the AC section (AC side) of the third inverter 23 and the filter 6 from the inlet 112, the connector 122, and the three-phase AC power supply system 202, and stops the charge / discharge operation.

[0099] Returning to FIG. 3, if the charge / discharge controller 25 determines in step S109 that the connector 122 of the three-phase AC power supply system 202 is not connected to the inlet 112 (NO), the process proceeds to step S113.

[0100] (Step S113) The charge / discharge controller 25 determines whether or not the connector 124 of the DC power bus 204 is connected to the inlet 114. If the charge / discharge controller 25 determines that the connector 124 of the DC power bus 204 is connected to the inlet 114 (YES), the process proceeds to step S115, where the process proceeds to a process of performing a charge / discharge operation between the battery 10 and the DC power bus 204. On the other hand, if the charge / discharge controller 25 determines that the connector 124 of the DC power bus 204 is not connected to the inlet 114 (NO), the process proceeds to step S103.

[0101] <1(4) Charging and discharging between the battery and the DC power bus> (Step S115) The charge / discharge controller 25 controls the operation to charge and discharge between the battery 10 and the DC power supply bus 204. When charging the battery 10 with power from the DC power supply bus 204, the charge / discharge controller 25 controls the relay switch as follows.

[0102] The charge / discharge controller 25 outputs an OFF signal to the relay switches 412 and 423, the relay switches 512 and 523, and the grid-connected relays 71 and 72, thereby opening the contacts of these relay switches and grid-connected relays. The charge / discharge controller 25 also controls the opening and closing of the contacts of the relay switch 424 and the relay switch 524 based on the measurement value of the voltage of the DC power supply bus 204 by the measurement unit 8 (see FIG. 8 , which will be described later). For example, when the voltage of the DC power supply bus 204 is within a predetermined range, the charge / discharge controller 25 outputs an ON signal to the relay switch 424 and the relay switch 524, thereby closing the contacts of these relay switches. This places the DC section (DC side) of the second inverter 22 in a state of being connected to the DC power supply bus 204 via the inlet 114 and the connector 124. The process of outputting an ON signal to the relay switch 424 and the relay switch 524 will be described in detail below with reference to the flowchart shown in FIG. 8.

[0103] The subsequent operation is the same as in <1(2) Charging and discharging operation between the battery and the single-phase AC power supply system> described above. First, the power conversion operation when the power flow is in the direction of charging the battery 10 will be described. The charge / discharge controller 25 outputs a gate drive signal to the second inverter 22 and controls the output current of the second inverter 22 to have a current waveform that stops the dual three-phase motor 3 from rotating. For example, as shown in FIG. 4, the charge / discharge controller 25 controls the U-, V-, and W-phase currents so that the magnetic field inside the dual three-phase motor 3 becomes a high-frequency alternating magnetic field and a high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating. The charge / discharge controller 25 also outputs a gate drive signal to the first inverter 21 to turn off all IGBTs, causing the first inverter 21 to operate as a rectifier circuit.

[0104] At this time, when the high-frequency AC current output by second inverter 22 flows through second winding 32 of dual three-phase motor 3, dual three-phase motor 3 operates as a current transformer (CT), and a current flows through first winding 31 so as to cancel out the magnetic flux in the iron core of dual three-phase motor 3. This current is rectified by first inverter 21 and charges battery 10. Battery controller 15 also monitors the state of battery 10. Charge / discharge controller 25 acquires state information of battery 10 from battery controller 15 and controls the above-mentioned charging operation based on the acquired state information of battery 10.

[0105] Next, the operation of power conversion when power is flowing in the direction of discharging from the battery 10 to the DC power bus 204 will be described. The charge / discharge controller 25 outputs a gate drive signal to the first inverter 21 and controls the output current of the first inverter 21 to have a current waveform that stops the dual three-phase motor 3 from rotating. For example, as shown in FIG. 4, the charge / discharge controller 25 controls the internal magnetic field of the dual three-phase motor 3 to become a high-frequency alternating magnetic field, resulting in a high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating. In addition, the charge / discharge controller 25 outputs a gate drive signal to the second inverter 22 to turn off all IGBTs, causing the second inverter 22 to operate as a rectifier circuit.

[0106] At this time, when the high-frequency AC current output by first inverter 21 flows through first winding 31 of dual three-phase motor 3, dual three-phase motor 3 operates as a current transformer (CT), and a current flows through second winding 32 so as to cancel out the magnetic flux in the iron core of dual three-phase motor 3. This current is rectified by second inverter 22 and output to DC power bus 204 via relay switch 424, relay switch 524, inlet 114, and connector 124. In addition, battery controller 15 monitors the state of battery 10. Charge / discharge controller 25 acquires state information of battery 10 from battery controller 15 and controls the above-mentioned discharge operation based on the acquired state information of battery 10.

[0107] In the above description, the output current of the first inverter 21 or the second inverter 22 is controlled to have the high-frequency AC current waveform shown in Fig. 4 during charging and discharging operations, in which the magnetic field inside the dual three-phase motor 3 becomes a high-frequency alternating magnetic field and the dual three-phase motor 3 stops rotating. However, the present invention is not limited to this. Any current waveform that stops the dual three-phase motor 3 from rotating will suffice. For example, the charge / discharge controller 25 may control the output current to have the high-frequency AC current waveform shown in Fig. 5 (alternating current or zero current with synchronized zero-cross timing).

[0108] During charging and discharging operations, if the voltage of the DC power bus 204 deviates from a predetermined range based on the voltage value of the DC power bus 204 measured by the measurement unit 8, the charge / discharge controller 25 outputs an OFF signal to the relay switch 424 and the relay switch 524 (see FIG. 8 described later), opens the contacts of these relay switches, and turns off the gate drive signals of all inverters. This disconnects the second inverter 22 from the inlet 114, the connector 124, and the DC power bus 204, and stops the charging and discharging operations.

[0109] 8, a description will be given of the operation of a relay switch control process in which the charge / discharge controller 25 outputs an ON signal or an OFF signal to the relay switch 424 and the relay switch 524 to control the opening and closing of the contacts of the relay switch 424 and the relay switch 524 during charge / discharge operations between the battery 10 and the DC power bus 204. Fig. 8 is a flowchart showing an example of the relay switch control process when the DC power bus is connected according to this embodiment. Here, an example of the process will be shown in which the standard output voltage is DC 50 V to DC 450 V as a specific example of the DC power bus 204.

[0110] (Step S161) The charge / discharge controller 25 determines whether or not a command to start a charge / discharge operation has been received. The command to start a charge / discharge operation corresponds to, for example, determining that the mode is the charge / discharge mode in step S101 of FIG. 3. When the charge / discharge controller 25 determines that a command to start a charge / discharge operation has not been received (NO), it outputs an OFF signal to the relay switch 424 and the relay switch 524, and opens the contacts of these relay switches (step S162). This process corresponds to the process of outputting an OFF signal to the relay switch 424 and the relay switch 524 in step S103 of FIG. 3 (processing when a charge / discharge operation is not being performed).

[0111] On the other hand, when it is determined in step S161 that a command to start a charge / discharge operation has been received (YES), the charge / discharge controller 25 determines whether the voltage of the DC power supply bus 204 measured by the measurement unit 8 is within a predetermined range by performing an overvoltage determination (step S163) and an undervoltage determination (step S164), and controls whether to output an ON signal or an OFF signal to the relay switch 424 and the relay switch 524 according to the determination result. First, the charge / discharge controller 25 proceeds to step S163.

[0112] (Step S163) The charge / discharge controller 25 determines whether the voltage of the DC power bus 204 measured by the measurement unit 8 exceeds a predetermined voltage (e.g., DC 450 V) for a predetermined time (e.g., 0.5 seconds). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the relay switch 424 and the relay switch 524 to open the contacts of these relay switches (step S166). As a result, as a protective operation, the second inverter 22 is disconnected from the inlet 114, the connector 124, and the DC power bus 204, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S164.

[0113] (Step S164) The charge / discharge controller 25 determines whether the voltage of the DC power bus 204 measured by the measurement unit 8 has been less than a predetermined voltage (e.g., DC 50 V) for a predetermined time (e.g., 0.5 seconds). If the determination result is true (YES), the charge / discharge controller 25 outputs an OFF signal to the relay switch 424 and the relay switch 524 to open the contacts of these relay switches (step S166). As a result, as a protective operation, the second inverter 22 is disconnected from the inlet 114, the connector 124, and the DC power bus 204, and the charge / discharge operation is stopped. On the other hand, if the determination result is false (NO), the charge / discharge controller 25 proceeds to step S165.

[0114] (Step S165) The charge / discharge controller 25 outputs an ON signal to the relay switch 424 and the relay switch 524 to close the contacts of these relay switches. As a result, the DC section (DC side) of the second inverter 22 is connected to the DC power bus 204 via the inlet 114 and the connector 124, and enters a normal operating state in which charge / discharge operations are possible.

[0115] In this way, if the determination results of both the overvoltage determination (step S163) and the undervoltage determination (step S164) are false (NO), the charge / discharge controller 25 determines that the voltage of the DC power supply bus 204 is within a predetermined range and outputs an ON signal to the relay switch 424 and the relay switch 524. This closes the contacts of the relay switch 424 and the relay switch 524, and the DC section (DC side) of the second inverter 22 is connected to the DC power supply bus 204 via the inlet 114 and the connector 124, thereby entering a normal operating state in which charging and discharging operations are possible.

[0116] On the other hand, if the result of either the overvoltage determination (step S163) or the undervoltage determination (step S164) is true (YES), the charge / discharge controller 25 determines that the voltage of the DC power supply bus 204 has deviated from the predetermined range, and outputs an OFF signal to the relay switch 424 and the relay switch 524. This opens the contacts of the relay switch 424 and the relay switch 524, disconnects the DC section (DC side) of the second inverter 22 from the inlet 114, the connector 124, and the DC power supply bus 204, and stops the charge / discharge operation.

[0117] As described above, the charge / discharge system 1 according to this embodiment includes the battery 10 and the charge / discharge device 5 that charges and discharges between the battery 10 and an external power supply system. For example, the charge / discharge system 1 includes a single-phase AC power supply system 201 and a three-phase AC power supply system 202 (an example of an AC power supply source) as the external power supply systems. For example, the charge / discharge system 1 (charge / discharge device 5) includes a dual three-phase motor 3 (an example of a motor) having a first winding 31 and a second winding 32 (an example of a multiplexed winding), a first inverter 21, a second inverter 22, grid-connected relays 71 and 72 (an example of a grid-connected relay), a third inverter 23, a relay switch 423 and a relay switch 523 (an example of a first relay switch), a measurement unit 8, a battery controller 15 (an example of a battery monitoring unit), and a charge / discharge controller 25 (an example of a control unit).

[0118] The first inverter 21 is connected between one of the first winding 31 and the second winding 32 (for example, the first winding 31) and the battery 10, and when charging the battery 10, converts the AC power output by the dual three-phase motor 3 into DC power and outputs it to the battery 10, and when discharging the battery 10, converts the DC power from the battery 10 into AC power and outputs it to the dual three-phase motor 3. The second inverter 22 is connected to the other of the first winding 31 and the second winding 32 (for example, the second winding 32), and when charging the battery 10, converts the DC power into AC power and outputs it to the dual three-phase motor 3, and when discharging the battery 10, converts the AC power output by the dual three-phase motor 3 into DC power and outputs it. The grid-connected relays 71 and 72 each have one end connected to the single-phase AC power supply system 201 and the three-phase AC power supply system 202, respectively, and open and close the connection (electrical connection) with the single-phase AC power supply system 201 and the three-phase AC power supply system 202 in response to an external command. The third inverter 23 is connected to the other end of the grid-connected relays 71 and 72, and when charging the battery 10, converts AC power from the single-phase AC power supply system 201 or the three-phase AC power supply system 202 connected via the grid-connected relays 71 or 72 into DC power and outputs the DC power. When discharging the battery 10, the third inverter 23 converts DC power output by the second inverter 22 into AC power and outputs the AC power to the single-phase AC power supply system 201 or the three-phase AC power supply system 202 via the grid-connected relays 71 or 72. One of the relay switches 423 and 523 is connected to the DC section (DC side (direct current side)) of the second inverter 22, and the other is connected to the DC section (DC side) of the third inverter 23, and opens and closes the connection between the DC section (DC side) of the second inverter 22 and the DC section (DC side) of the third inverter 23 in response to an external command.

[0119] The measurement unit 8 measures the voltage and frequency of the single-phase AC power supply system 201 and the three-phase AC power supply system 202. The battery controller 15 monitors the state of the battery 10. The charge / discharge controller 25 receives the outputs of the measurement unit 8 and the battery controller 15 and outputs drive signals to the first inverter 21, the second inverter 22, the third inverter 23 and the grid-connected relays 71 and 72 based on the inputs. For example, when charging / discharging between the battery 10 and the single-phase AC power supply system 201 or the three-phase AC power supply system 202, the charge / discharge controller 25 outputs drive signals (ON signals) to close the contacts (connections) of the relay switches 423 and 523 as the external commands to the relay switches 423 and 523. In addition, when the voltage and frequency of the single-phase AC power supply system 201 or the three-phase AC power supply system 202 measured by the measurement unit 8 are within a predetermined range, the charge / discharge controller 25 outputs a drive signal (ON signal) to the interconnection relay 71 or the interconnection relay 72 as the external command to close the contacts (connections) of the interconnection relay 71 or the interconnection relay 72.

[0120] As a result, the charging / discharging system 1 (charging / discharging device 5) has a simple configuration without using a separate charging / discharging device, and is not only able to charge the battery 10 from the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202), but also able to supply (discharge) power from the battery 10 to the AC power supply source. Furthermore, because the charging / discharging system 1 (charging / discharging device 5) does not use a separate charging / discharging device, control through communication with the separate charging / discharging device is not required, and it is possible to prevent problems such as inability to charge or discharge due to communication abnormalities.

[0121] Furthermore, the charging / discharging system 1 (charging / discharging device 5) is configured to connect to the AC power supply source to perform charging / discharging when the voltage and frequency of the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202) are within a predetermined range. Therefore, when there is an abnormality in the voltage or frequency of the AC power supply source, the charging / discharging system 1 is electrically disconnected from the AC power supply source, thereby ensuring the safety of the AC power supply source and the charging / discharging device 5.

[0122] Furthermore, the charge / discharge device 5 has one end connected to the DC section (DC side) of the first inverter 21 and the other end connected to the DC section (DC side) of the second inverter 22, and includes a relay switch 412 and a relay switch 512 (an example of a second relay switch) that open and close the connection between the DC section (DC side) of the first inverter 21 and the DC section (DC side) of the second inverter 22 in response to the external command. When no charge or discharge is performed between the battery 10 and the AC power supply source (the single-phase AC power supply system 201 or the three-phase AC power supply system 202), the charge / discharge controller 25 outputs a drive signal (ON signal) to the relay switch 423 and the relay switch 523 as the external command to open the contacts (connections) of the relay switch 423 and the relay switch 523 (an example of a first relay switch), and outputs a drive signal (OFF signal) to the relay switch 412 and the relay switch 512 as the external command to close the contacts (connections) of the relay switch 412 and the relay switch 512 (an example of a second relay switch).

[0123] As a result, when charging / discharging system 1 (charging / discharging device 5) is not charging / discharging between battery 10 and the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202), it can drive dual three-phase motor 3 with the power of battery 10.

[0124] Furthermore, by controlling the opening and closing of the contacts of each relay switch, charging / discharging system 1 (charging / discharging device 5) can ensure insulation within dual three-phase motor 3 and charge / discharge power to / from battery 10 of electric vehicle 100 even between DC power source bus 204 such as a solar power generation system that does not have an isolated power conversion unit. For example, charging / discharging system 1 (charging / discharging device 5) includes relay switches 412, 423, 424, 512, 523, and 524, and can charge / discharge between battery 10 and DC power source bus 204 by closing the contacts of relay switch 424 and relay switch 524 (while opening the contacts of the other relay switches). Therefore, charging / discharging system 1 (charging / discharging device 5) does not require an isolated power conversion unit in a separate charging / discharging device when charging / discharging using a DC power source, and the charging / discharging device and the charging / discharging system can be simplified and made smaller.

[0125] Furthermore, the charge / discharge system 1 (charge / discharge device 5) is configured such that the charge / discharge operation of the battery 10 is controlled by the charge / discharge controller 25, so that charge / discharge control can be completed within the electric vehicle 100. This eliminates the need for charge / discharge control through communication with a separate device, and can prevent problems such as inability to charge / discharge due to communication abnormalities caused by incompatibility between devices.

[0126] Furthermore, when the battery 10 is charged from the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202), the waveform of the output current of the second inverter 22 is a current waveform that stops the rotation of the dual three-phase motor 3. When the battery 10 is discharged to the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202), the waveform of the output current of the first inverter 21 is a current waveform that stops the rotation of the dual three-phase motor 3.

[0127] This allows the charge / discharge system 1 (charge / discharge device 5) to prevent the dual three-phase motor 3 from rotating when charging or discharging the battery 10.

[0128] For example, when charging the battery 10 from an AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202), the waveform of the output current of each phase of the second inverter 22 is a high-frequency alternating current or zero current with the same zero-cross timing, and the sum of the currents of each phase is zero. When discharging from the battery 10 to the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202), the waveform of the output current of each phase of the first inverter 21 is a high-frequency alternating current or zero current with the same zero-cross timing, and the sum of the currents of each phase is zero.

[0129] This allows the charge / discharge system 1 (charge / discharge device 5) to prevent the dual three-phase motor 3 from rotating when charging or discharging the battery 10.

[0130] Furthermore, the control method for the charge / discharge system 1 (charge / discharge device 5) according to this embodiment includes the steps of: when charging / discharging between the battery 10 and the single-phase AC power supply system 201 or the three-phase AC power supply system 202 (an example of an AC power supply source), the charge / discharge controller 25 (an example of a control unit) outputs, as the external command, a drive signal (ON signal) to close the contacts (connections) of the relay switch 423 and the relay switch 523 (an example of a first relay switch); and when the voltage and frequency of the single-phase AC power supply system 201 or the three-phase AC power supply system 202 measured by the measurement unit 8 are within predetermined ranges, outputting, as the external command, a drive signal (ON signal) to close the contacts (connections) of the interconnection relay 71 or the interconnection relay 72.

[0131] As a result, the control method for charge / discharge system 1 (charge / discharge device 5) has a simple configuration that does not use a separate charge / discharge device, and is not only able to charge battery 10 from the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202), but also able to supply (discharge) power from battery 10 to the AC power supply source. Furthermore, because the control method for charge / discharge system 1 (charge / discharge device 5) does not use a separate charge / discharge device, control through communication with the separate charge / discharge device is not required, and it is possible to prevent problems such as inability to charge or discharge due to communication abnormalities.

[0132] Furthermore, the control method of the charging / discharging system 1 (charging / discharging device 5) connects to the AC power supply source to perform charging / discharging when the voltage and frequency of the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202) are within a predetermined range, and therefore, when there is an abnormality in the voltage or frequency of the AC power supply source, the charging / discharging system 1 is electrically disconnected from the AC power supply source, thereby ensuring the safety of the AC power supply source and the charging / discharging device 5.

[0133] The configuration of this embodiment is not limited to the above configuration. For example, although this embodiment is configured to be able to connect two types of AC power supply systems, the single-phase AC power supply system 201 and the three-phase AC power supply system 202, it may be configured to be able to connect only one of them.

[0134] Furthermore, in this embodiment, a single-phase three-wire system and a single-phase grounded three-phase three-wire system, which are typical power supply systems in Japan, are used as AC power supply systems (AC power supply sources), but other AC power supply sources may also be used. Fig. 9 is a diagram showing an example of another AC power supply source according to this embodiment. Fig. 9 shows an example in which a neutral-grounded three-phase four-wire system 203 is used as the AC power supply source. In the example shown, connectors 121 and 122 are connected to neutral-grounded three-phase four-wire system 203, and by connecting connectors 121 and 122 to inlets 111 and 112, electric vehicle 100 can be connected to neutral-grounded three-phase four-wire system 203.

[0135] Furthermore, the DC power bus 204 can provide the same effect as long as it is a power source that outputs DC power and does not require charge control communication with the electric vehicle 100, such as a storage battery or a DC output power conversion device, in addition to the solar power source shown in this embodiment.

[0136] Furthermore, although an example of a configuration in which IGBTs are used as switching devices that constitute the first inverter 21, the second inverter 22, and the third inverter 23 has been shown, other power devices such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) may also be used.

[0137] For example, in the present embodiment, an example has been described in which the IGBT of the first inverter 21 is turned off when the flow of power is in the direction of charging the battery 10, but if a MOSFET is used as the constituent switching device, the same effect can be obtained by performing switching operation to perform synchronous rectification. Similarly, in the present embodiment, an example has been described in which the IGBT of the second inverter 22 is turned off when the flow of power is in the direction of supplying (discharging) power from the battery 10 to the AC power supply system, but if a MOSFET is used as the constituent switching device, the same effect can be obtained by performing switching operation to perform synchronous rectification.

[0138] Furthermore, the first inverter 21 and the second inverter 22 are configured as a three-phase full-bridge inverter circuit, but a multilevel inverter circuit such as a three-level inverter circuit will also work in the same way and provide the same effects.

[0139] Furthermore, the relay switch may be a mechanical switch or a semiconductor switch, and the operation and effect will be the same.

[0140] <Second embodiment> Next, a second embodiment will be described. The charging / discharging system according to this embodiment includes an electric vehicle 100, a single-phase AC power supply system 201, a three-phase AC power supply system 202, and a DC power supply bus 204, similar to the charging / discharging system 1 according to the first embodiment.

[0141] [Charging and discharging system configuration] Fig. 10 is a schematic block diagram showing an example of the configuration of the charge / discharge system according to this embodiment. Fig. 10 shows an excerpt of the configuration of the charge / discharge system 1A according to this embodiment, including the first inverter 21, the second inverter 22, and the dual three-phase motor 3. As shown in Fig. 10, the configuration of the charge / discharge system 1A (charge / discharge device 5A) differs from the configuration of the charge / discharge system 1 (charge / discharge device 5) shown in Fig. 1 in that relay switches (1311, 1312, 1321, 1322) are provided in the circuits between the first inverter 21, the second inverter 22, and the dual three-phase motor 3. The configuration other than that shown in Fig. 10 is the same as the configuration shown in Fig. 1, and therefore, illustration and description thereof will be omitted as appropriate.

[0142] The AC section (AC side) of the first inverter 21 is connected to one side of the first winding 31 of the dual three-phase motor 3, and the other side of the first winding 31 is connected to one side of a relay switch 1312, the other side of which is short-circuited between phases. That is, the relay switch 1312 is provided as a relay switch that opens and closes the connection of the neutral point of the first winding 31.

[0143] One of contacts 1311a of relay switch 1311 is connected to the inverter side of U-phase winding 31a of first winding 31, and the other is connected to the neutral side of W-phase winding 31c of first winding 31. One of contacts 1311b of relay switch 1311 is connected to the inverter side of W-phase winding 31c of first winding 31, and the other is connected to the neutral side of V-phase winding 31b of first winding 31. One of contacts 1311c of relay switch 1311 is connected to the inverter side of V-phase winding 31b of first winding 31, and the other is connected to the neutral side of U-phase winding 31a of first winding 31. In other words, relay switch 1311 is provided as a relay switch that opens and closes the connection of the delta connection of first winding 31.

[0144] The AC section (AC side) of the second inverter 22 is connected to one side of the second winding 32 of the dual three-phase motor 3, and the other side of the second winding 32 is connected to one side of a relay switch 1322, the other side of which is short-circuited between phases. In other words, the relay switch 1322 is provided as a relay switch that opens and closes the connection of the neutral point of the second winding 32.

[0145] One of contacts 1321a of relay switch 1321 is connected to the inverter side of U-phase winding 32a of second winding 32, and the other is connected to the neutral side of W-phase winding 32c of second winding 32. One of contacts 1321b of relay switch 1321 is connected to the inverter side of W-phase winding 32c of second winding 32, and the other is connected to the neutral side of V-phase winding 32b of second winding 32. One of contacts 1321c of relay switch 1321 is connected to the inverter side of V-phase winding 32b of second winding 32, and the other is connected to the neutral side of U-phase winding 32a of second winding 32. In other words, relay switch 1321 is provided as a relay switch that opens and closes the connection of the delta connection of second winding 32.

[0146] [Charging and discharging system operation] Next, the processing operations performed by the charge / discharge controller 25 in the charge / discharge system 1A according to this embodiment will be described with reference to Figures 1, 3, 10, and 11. Below, the operations will be explained in sections: <2(1) Operation when the electric vehicle is running>, <2(2) Charging / discharging operation between the battery and the single-phase AC power supply system>, <2(3) Charging / discharging operation between the battery and the three-phase AC power supply system>, and <2(4) Charging / discharging operation between the battery and the DC power supply bus>.

[0147] FIG. 11 is a flowchart showing an example of processing performed by the charge / discharge controller in the charge / discharge system according to this embodiment.

[0148] (Step S201) The charge / discharge controller 25 determines whether or not the charge / discharge mode is in effect. If the charge / discharge controller 25 determines that the charge / discharge mode is not in effect (NO), the process proceeds to step S103 in FIG. 3, where the charge / discharge controller 25 performs an operation for driving the electric vehicle, and then proceeds to step S203.

[0149] <2(1) Operation of electric vehicles when driving> When the charge / discharge controller 25 is not in the charge / discharge mode (for example, when the electric vehicle 100 is traveling), the charge / discharge controller 25 performs the process of step S103 in Fig. 3. That is, by the process of step S103 in Fig. 3, the charge / discharge controller 25 outputs an OFF signal to the relay switches 423, 424 and the relay switches 523, 524 to open the contacts of these relay switches. In addition, the charge / discharge controller 25 outputs an ON signal to the relay switches 412 and 512 to close the contacts of these relay switches. As a result, the DC section (DC side) of the second inverter 22 is connected only to the battery 10 and the DC section (DC side) of the first inverter 21. In addition, the charge / discharge controller 25 outputs an OFF signal to the grid-connection relays 71, 72 to open the contacts of these grid-connection relays. As a result, the AC section (AC side) of the third inverter 23 and the filter 6 are disconnected from the inlet 111, the inlet 112, the single-phase AC power supply system 201, and the three-phase AC power supply system 202.

[0150] Furthermore, the charge / discharge controller 25 performs the process of step S203 in FIG. (Step S203) The charge / discharge controller 25 controls the opening and closing of the contacts of the relay switches 1311, 1321, 1312, and 1322 as follows: The charge / discharge controller 25 outputs an OFF signal to the relay switches 1311 and 1321 to open the contacts of the relay switches 1311 and 1321, and outputs an ON signal to the relay switches 1312 and 1322 to close the contacts of the relay switches 1312 and 1322. As a result, both the first winding 31 and the second winding 32 of the dual three-phase motor 3 are connected in a Y-connection. Although a Y-connection is used here, when charge / discharge operations are not being performed, a Delta-connection may be established by outputting an ON signal to the relay switches 1311 and 1321 to close the contacts of the relay switches 1311 and 1321 and outputting an OFF signal to the relay switches 1312 and 1322 to open the contacts of the relay switches 1312 and 1322.

[0151] The charge / discharge controller 25 outputs gate drive signals to the first inverter 21 and the second inverter 22, causing the first inverter 21 and the second inverter 22 to output sinusoidal three-phase AC current, thereby driving the dual three-phase motor 3 to rotate.

[0152] On the other hand, when the charge / discharge controller 25 determines that the electric vehicle 100 is stopped and is in the charge / discharge mode in step S201 (YES), the charge / discharge controller 25 performs the processes shown in steps S105 to S115 in Fig. 3. For example, when the charge / discharge controller 25 determines that the connector 121 of the single-phase AC power supply system 201 is connected to the inlet 111, the charge / discharge controller 25 proceeds to a process (step S107 in Fig. 3) for performing a charge / discharge operation between the battery 10 and the single-phase AC power supply system 201. When the charge / discharge controller 25 determines that the connector 122 of the three-phase AC power supply system 202 is connected to the inlet 112, the charge / discharge controller 25 proceeds to a process (step S111 in Fig. 3) for performing a charge / discharge operation between the battery 10 and the three-phase AC power supply system 202. Furthermore, if the charge / discharge controller 25 determines that the connector 124 of the DC power bus 204 is connected to the inlet 114, it proceeds to a process of performing a charge / discharge operation between the battery 10 and the DC power bus 204 (step S115 in FIG. 3).

[0153] <2(2) Charging and discharging between the battery and the single-phase AC power supply system> First, a description will be given of the operation when charging and discharging is performed between the battery 10 and the single-phase AC power supply system 201 while the electric vehicle 100 is stopped. As shown in step S107 of Fig. 3, when charging and discharging is performed between the battery 10 and the single-phase AC power supply system 201, the charge and discharge controller 25 controls the opening and closing of the contacts of the relay switch as follows.

[0154] The charge / discharge controller 25 outputs an OFF signal to the relay switches 412, 424 and the relay switches 512, 524, thereby opening the contacts of these relay switches. The charge / discharge controller 25 also outputs an ON signal to the relay switches 423 and 523, thereby closing the contacts of these relay switches. This places the DC section (DC side) of the second inverter connected only to the DC section (DC side) of the third inverter 23. Furthermore, the charge / discharge controller 25 outputs an OFF signal to the grid-connection relay 72, thereby opening the contacts of the grid-connection relay 72. This places the AC section (AC side) of the third inverter 23 and the filter 6 in a state of being disconnected from the inlet 112 and the three-phase AC power supply system 202.

[0155] 6 , when the inter-phase voltage and frequency of the single-phase AC power supply system 201 are within predetermined ranges, the charge / discharge controller 25 outputs an ON signal to the interconnection relay 71 to close the contacts of the interconnection relay 71. As a result, the AC section (AC side) of the third inverter 23 and the filter 6 are connected to the single-phase AC power supply system 201 via the interconnection relay 71, the inlet 111, and the connector 121.

[0156] Also, if it is determined in step S201 of FIG. 11 that the charging / discharging mode is selected (YES), the charging / discharging controller 25 proceeds to step S205, and outputs drive signals to the relay switches 1311, 1312, 1321, and 1322 based on the relationship between the voltage of the DC section (DC side) of the second inverter and the voltage of the battery 10, thereby controlling the opening and closing of the contacts of each relay switch.

[0157] The following describes the case where the coupling coefficient between U-phase winding 31a of first winding 31 of dual three-phase motor 3 and U-phase winding 32a of second winding of the dual three-phase motor, the coupling coefficient between V-phase winding 31b of first winding of the dual three-phase motor and V-phase winding 32b of second winding of the dual three-phase motor, and the coupling coefficient between W-phase winding 31c of first winding of the dual three-phase motor and W-phase winding 32c of second winding of the dual three-phase motor are 1.

[0158] (Step S205) The charge / discharge controller 25 determines whether or not the voltage of the DC section (DC side) of the second inverter 22 is higher than √3 times the voltage of the battery 10. If the charge / discharge controller 25 determines that the voltage of the DC section (DC side) of the second inverter 22 is higher than √3 times the voltage of the battery 10 (YES), the process proceeds to step S207. On the other hand, if the charge / discharge controller 25 determines that the voltage of the DC section (DC side) of the second inverter 22 is equal to or lower than √3 times the voltage of the battery 10 (NO), the process proceeds to step S209.

[0159] (Step S207) The charge / discharge controller 25 outputs an OFF signal to the relay switches 1312 and 1321 to open the contacts of the relay switches 1312 and 1321, and outputs an ON signal to the relay switches 1311 and 1322 to close the contacts of the relay switches 1311 and 1322. As a result, the first winding 31 of the dual three-phase motor 3 is connected in a Δ connection, and the second winding 32 is connected in a Y connection.

[0160] (Step S209) The charge / discharge controller 25 determines whether or not the voltage of the DC section (DC side) of the second inverter 22 is lower than 1 / √3 times the voltage of the battery 10. If the charge / discharge controller 25 determines that the voltage of the DC section (DC side) of the second inverter 22 is lower than 1 / √3 times the voltage of the battery 10 (YES), the process proceeds to step S211.

[0161] (Step S211) The charge / discharge controller 25 outputs an OFF signal to the relay switches 1311 and 1322 to open the contacts of the relay switches 1311 and 1322, and outputs an ON signal to the relay switches 1312 and 1321 to close the contacts of the relay switches 1312 and 1321. As a result, the first winding 31 of the dual three-phase motor 3 is connected in a Y connection, and the second winding 32 is connected in a Δ connection.

[0162] On the other hand, if the charge / discharge controller 25 determines in step S209 that the voltage of the DC section (DC side) of the second inverter 22 is 1 / √3 times or more the voltage of the battery 10 (NO), the process proceeds to step S203. That is, if the determinations in both steps S205 and S209 are "NO," the charge / discharge controller 25 proceeds to step S203. If the determinations in both steps S205 and S209 are "NO," this occurs, for example, when the voltage of the DC section (DC side) of the second inverter 22 is the same as the voltage of the battery 10.

[0163] Here, we will first explain the operation of power conversion when the flow of power is in the direction of charging the battery 10. The charge / discharge controller 25 outputs a gate drive signal to the third inverter 23 to control it so that the power factor of the power flowing from the single-phase AC power supply system 201 to the third inverter 23 is 1 and so that the DC voltage of the third inverter 23 is higher than the voltage of the battery 10. At this time, the operation of the third inverter 23 converts the AC power from the single-phase AC power supply system 201 into DC power, which is input to the DC section (DC side) of the second inverter.

[0164] The charge / discharge controller 25 outputs a gate drive signal to the second inverter 22 and controls the output current of the second inverter 22 to have a current waveform that stops the dual three-phase motor 3 from rotating. For example, as shown in FIG. 4, the charge / discharge controller 25 controls the U-phase, V-phase, and W-phase currents so that the magnetic field inside the dual three-phase motor 3 becomes a high-frequency alternating magnetic field and a high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating. Note that when controlling the current waveform that stops the dual three-phase motor 3 from rotating, the charge / discharge controller 25 may also control the current waveform shown in FIG. 5 (alternating current or zero current with synchronized zero-cross timing). In addition, the charge / discharge controller 25 outputs a gate drive signal to the first inverter 21 to turn off all IGBTs, causing the first inverter 21 to operate as a rectifier circuit.

[0165] At this time, when the high-frequency AC current output by second inverter 22 flows through second winding 32 of dual three-phase motor 3, dual three-phase motor 3 operates as a current transformer (CT), and a current flows through first winding 31 so as to cancel out the magnetic flux in the iron core of dual three-phase motor 3. This current is rectified by first inverter 21 and charges battery 10. Battery controller 15 also monitors the state of battery 10. Charge / discharge controller 25 acquires state information of battery 10 from battery controller 15 and controls the above-mentioned charging operation based on the acquired state information of battery 10.

[0166] Next, the operation of power conversion when power is discharging from the battery 10 to the single-phase AC power supply system 201 will be described. The charge / discharge controller 25 outputs a gate drive signal to the first inverter 21 and controls the output current of the first inverter 21 to have a current waveform that stops the dual three-phase motor 3 from rotating. For example, as shown in FIG. 4, the charge / discharge controller 25 controls the output current of the first inverter 21 so that the magnetic field inside the dual three-phase motor 3 becomes a high-frequency alternating magnetic field, resulting in a high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating. Note that when controlling the output current to have a high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating, the charge / discharge controller 25 may also control the output current to have a high-frequency AC current waveform (high-frequency alternating current or zero current with synchronized zero-cross timing) as shown in FIG. 5. The charge / discharge controller 25 also outputs a gate drive signal to the second inverter 22 to turn off all IGBTs, causing the second inverter 22 to operate as a rectifier circuit.

[0167] At this time, when the high-frequency AC current output from the first inverter 21 flows through the first winding 31 of the dual three-phase motor 3, the dual three-phase motor 3 operates as a current transformer (CT), and a current flows through the second winding 32 so as to cancel out the magnetic flux in the iron core of the dual three-phase motor 3. This current is rectified by the second inverter 22 and input to the third inverter 23. In addition, the charge / discharge controller 25 outputs a gate drive signal to the third inverter 23 to control the third inverter 23 so that the power factor of the power flowing from the third inverter 23 to the single-phase AC power supply system 201 becomes 1 and so that the DC voltage of the third inverter 23 is lower than the voltage of the battery 10. At this time, the operation of the third inverter 23 converts the DC power input to the third inverter 23 into AC power, which is output to the single-phase AC power supply system 201 via the filter 6, the grid-connection relay 71, the inlet 111, and the connector 121. In addition, the battery controller 15 monitors the state of the battery 10. The charge / discharge controller 25 acquires the state information of the battery 10 from the battery controller 15, and controls the above-mentioned discharge operation based on the acquired state information of the battery 10.

[0168] FIG. 11 illustrates a case where both the charging operation and the discharging operation are performed. However, if the discharging operation is not performed, step S209 can be omitted, and if the charging operation is not performed, step S205 can be omitted.

[0169] Furthermore, if the coupling coefficient is not 1, the same effect can be obtained by replacing "√3" in steps S205 and S209 in Fig. 11 with "the product of the coupling coefficient and √3." When using the coupling coefficient as the judgment threshold, it may be a value that takes into account variations in the specification values.

[0170] During charging and discharging operations, if the inter-phase voltage and frequency of the single-phase AC power supply system 201 deviate from a predetermined range, the charge / discharge controller 25 outputs an OFF signal to the grid-connection relay 71 to open the contacts of the grid-connection relay 71 and turn OFF the gate drive signals of all inverters, according to the measured values ​​of the voltage and frequency of the single-phase AC power supply system 201 by the measurement unit 8 and the flowchart shown in Fig. 6. This disconnects the AC unit (AC side) of the third inverter 23 and the filter 6 from the inlet 111, the connector 121, and the single-phase AC power supply system 201, and stops the charging and discharging operations. These functions are equivalent to those of a grid-connection protection device.

[0171] <2(3) Charging and discharging between the battery and the three-phase AC power supply system> Next, a description will be given of the operation when charging and discharging is performed between the battery 10 and the three-phase AC power supply system 202 while the electric vehicle 100 is stopped. As shown in step S111 of Fig. 3, when charging and discharging is performed between the battery 10 and the three-phase AC power supply system 202, the charge and discharge controller 25 controls the opening and closing of the contacts of the relay switch as follows.

[0172] The charge / discharge controller 25 outputs an OFF signal to the relay switches 412, 424 and the relay switches 512, 524, thereby opening the contacts of these relay switches. The charge / discharge controller 25 also outputs an ON signal to the relay switches 423 and 523, thereby closing the contacts of these relay switches. This causes the DC section (DC side) of the second inverter 22 to be connected only to the DC section (DC side) of the third inverter 23. Furthermore, the charge / discharge controller 25 outputs an OFF signal to the grid-connection relay 71, thereby opening the contacts of the grid-connection relay 71. This causes the AC section (AC side) of the third inverter 23 and the filter 6 to be disconnected from the inlet 111 and the single-phase AC power supply system 201.

[0173] 7 , when the inter-phase voltage and frequency of the three-phase AC power supply system 202 are within predetermined ranges, the charge / discharge controller 25 outputs an ON signal to the interconnection relay 72 and closes the contacts of the interconnection relay 72. As a result, the AC section (AC side) of the third inverter 23 and the filter 6 are connected to the three-phase AC power supply system 202 via the interconnection relay 72, the inlet 112, and the connector 122.

[0174] In addition, the charge / discharge controller 25 outputs drive signals to the relay switches 1311, 1312, 1321, and 1322 based on the relationship between the voltage of the DC section (DC side) of the second inverter and the voltage of the battery 10, in accordance with the flowchart shown in Figure 11, and controls the opening and closing of the contacts of each relay switch.

[0175] For example, if the charge / discharge controller 25 determines that the voltage of the DC section (DC side) of the second inverter 22 is higher than √3 times the voltage of the battery 10, it outputs an OFF signal to the relay switches 1312 and 1321 to open the contacts of the relay switches 1312 and 1321, and outputs an ON signal to the relay switches 1311 and 1322 to close the contacts of the relay switches 1311 and 1322. As a result, the first winding 31 of the dual three-phase motor 3 is connected in a Δ connection, and the second winding 32 is connected in a Y connection. Power flows in the direction of charging the battery 10.

[0176] Furthermore, if the charge / discharge controller 25 determines that the voltage of the DC section (DC side) of the second inverter 22 is lower than 1 / √3 times the voltage of the battery 10, it outputs an OFF signal to the relay switches 1311 and 1322 to open the contacts of the relay switches 1311 and 1322, and outputs an ON signal to the relay switches 1312 and 1321 to close the contacts of the relay switches 1312 and 1321. As a result, the first winding 31 of the dual three-phase motor 3 is connected in a Y connection, and the second winding 32 is connected in a Δ connection. The power flows in the direction that discharges the battery 10.

[0177] In the charge / discharge mode, when the relationship between the voltage of the DC section (DC side) of the second inverter 22 and the voltage of the battery 10 is other than that described above, for example, when the voltage of the DC section (DC side) of the second inverter 22 and the voltage of the battery 10 are the same, the charge / discharge controller 25 outputs an OFF signal to the relay switches 1311 and 1321 to open the contacts of the relay switches 1311 and 1321, and outputs an ON signal to the relay switches 1312 and 1322 to close the contacts of the relay switches 1312 and 1322. As a result, both the first winding 31 and the second winding 32 of the dual three-phase motor 3 are connected in a Y connection.

[0178] Here, we will first explain the operation of power conversion when the flow of power is in the direction of charging the battery 10. The charge / discharge controller 25 outputs a gate drive signal to the third inverter 23 to control it so that the power factor of the power flowing from the three-phase AC power supply system 202 to the third inverter 23 is 1 and so that the DC voltage of the third inverter 23 is higher than the voltage of the battery 10. At this time, the operation of the third inverter 23 converts the AC power from the three-phase AC power supply system 202 into DC power, which is input to the DC section (DC side) of the second inverter.

[0179] The charge / discharge controller 25 outputs a gate drive signal to the second inverter 22 and controls the output current of the second inverter 22 to have a current waveform that stops the dual three-phase motor 3 from rotating. For example, as shown in FIG. 4, the charge / discharge controller 25 controls the U-, V-, and W-phase currents so that the magnetic field inside the dual three-phase motor 3 becomes a high-frequency alternating magnetic field and a high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating. Note that when controlling the high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating, the charge / discharge controller 25 may also control the current waveform shown in FIG. 5 (alternating current or zero current with synchronized zero-cross timing). In addition, the charge / discharge controller 25 outputs a gate drive signal to the first inverter 21 to turn off all IGBTs, causing the first inverter 21 to operate as a rectifier circuit.

[0180] At this time, when the high-frequency AC current output by second inverter 22 flows through second winding 32 of dual three-phase motor 3, dual three-phase motor 3 operates as a current transformer (CT), and a current flows through first winding 31 so as to cancel out the magnetic flux in the iron core of dual three-phase motor 3. This current is rectified by first inverter 21 and charges battery 10. Battery controller 15 also monitors the state of battery 10. Charge / discharge controller 25 acquires state information of battery 10 from battery controller 15 and controls the above-mentioned charging operation based on the acquired state information of battery 10.

[0181] Next, the operation of power conversion when power is flowing from the battery 10 to the three-phase AC power supply system 202 will be described. The charge / discharge controller 25 outputs a gate drive signal to the first inverter 21 and controls the output current of the first inverter 21 to have a current waveform that stops the dual three-phase motor 3 from rotating. For example, as shown in FIG. 4, the charge / discharge controller 25 controls the output current of the first inverter 21 so that the magnetic field inside the dual three-phase motor 3 becomes a high-frequency alternating magnetic field, resulting in a high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating. Note that when controlling the current waveform that stops the dual three-phase motor 3 from rotating, the charge / discharge controller 25 may also control the output current to have a high-frequency AC current waveform (high-frequency alternating current or zero current with synchronized zero-cross timing) as shown in FIG. 5. The charge / discharge controller 25 also outputs a gate drive signal to the second inverter 22 to turn off all IGBTs, causing the second inverter 22 to operate as a rectifier circuit.

[0182] At this time, when the high-frequency AC current output from the first inverter 21 flows through the first winding 31 of the dual three-phase motor 3, the dual three-phase motor 3 operates as a current transformer (CT), and a current flows through the second winding 32 so as to cancel out the magnetic flux in the iron core of the dual three-phase motor 3. This current is rectified by the second inverter 22 and input to the third inverter 23. In addition, the charge / discharge controller 25 outputs a gate drive signal to the third inverter 23 to control the third inverter 23 so that the power factor of the power flowing from the third inverter 23 to the three-phase AC power supply system 202 is 1 and so that the DC voltage of the third inverter 23 is lower than the voltage of the battery 10. At this time, the operation of the third inverter 23 converts the DC power input to the third inverter 23 into AC power, which is output to the three-phase AC power supply system 202 via the filter 6, the grid-connection relay 72, the inlet 112, and the connector 122. In addition, the battery controller 15 monitors the state of the battery 10. The charge / discharge controller 25 acquires the state information of the battery 10 from the battery controller 15, and controls the above-mentioned discharge operation based on the acquired state information of the battery 10.

[0183] During charging and discharging operations, if the inter-phase voltage and frequency of the three-phase AC power supply system 202 deviate from a predetermined range, the charge / discharge controller 25 outputs an OFF signal to the grid-connection relay 72 to open the contacts of the grid-connection relay 72 and turn OFF the gate drive signals of all inverters, according to the measured values ​​of the voltage and frequency of the three-phase AC power supply system 202 by the measurement unit 8 and the flowchart shown in Fig. 7. This disconnects the AC unit (AC side) of the third inverter 23 and the filter 6 from the inlet 112, the connector 122, and the three-phase AC power supply system 202, and stops the charging and discharging operations. These functions are equivalent to those of a grid-connection protection device.

[0184] <2(4) Charging and discharging between the battery and the DC power bus> Next, a description will be given of the operation when charging and discharging is performed between the battery 10 and the DC power bus 204 while the electric vehicle 100 is stopped. As shown in step S115 of Fig. 3, when charging and discharging is performed between the battery 10 and the DC power bus 204, the charge and discharge controller 25 controls the opening and closing of the contacts of the relay switch as follows.

[0185] The charge / discharge controller 25 outputs an OFF signal to the relay switches 412 and 423, the relay switches 512 and 523, and the grid-connected relays 71 and 72, thereby opening the contacts of these relay switches and grid-connected relays. Furthermore, the charge / discharge controller 25 outputs an ON signal to the relay switches 424 and 524, thereby closing the contacts of these relay switches, when the voltage of the DC power supply bus 204 is within a predetermined range, in accordance with the measurement value of the voltage of the DC power supply bus 204 by the measurement unit 8 and the flowchart shown in FIG. 8. This causes the DC section (DC side) of the second inverter 22 to be connected to the DC power supply bus 204 via the inlet 114 and the connector 124.

[0186] In addition, the charge / discharge controller 25 outputs drive signals to the relay switches 1311, 1312, 1321, and 1322 based on the relationship between the voltage of the DC section (DC side) of the second inverter and the voltage of the battery 10, in accordance with the flowchart shown in Figure 11, and controls the opening and closing of the contacts of each relay switch.

[0187] For example, if the charge / discharge controller 25 determines that the voltage of the DC section (DC side) of the second inverter 22 is higher than √3 times the voltage of the battery 10, it outputs an OFF signal to the relay switches 1312 and 1321 to open the contacts of the relay switches 1312 and 1321, and outputs an ON signal to the relay switches 1311 and 1322 to close the contacts of the relay switches 1311 and 1322. As a result, the first winding 31 of the dual three-phase motor 3 is connected in a Δ connection, and the second winding 32 is connected in a Y connection. Power flows in the direction of charging the battery 10.

[0188] Furthermore, if the charge / discharge controller 25 determines that the voltage of the DC section (DC side) of the second inverter 22 is lower than 1 / √3 times the voltage of the battery 10, it outputs an OFF signal to the relay switches 1311 and 1322 to open the contacts of the relay switches 1311 and 1322, and outputs an ON signal to the relay switches 1312 and 1321 to close the contacts of the relay switches 1312 and 1321. As a result, the first winding 31 of the dual three-phase motor 3 is connected in a Y connection, and the second winding 32 is connected in a Δ connection. The power flows in the direction that discharges the battery 10.

[0189] In the charge / discharge mode, when the relationship between the voltage of the DC section (DC side) of the second inverter 22 and the voltage of the battery 10 is other than that described above, for example, when the voltage of the DC section (DC side) of the second inverter 22 and the voltage of the battery 10 are the same, the charge / discharge controller 25 outputs an OFF signal to the relay switches 1311 and 1321 to open the contacts of the relay switches 1311 and 1321, and outputs an ON signal to the relay switches 1312 and 1322 to close the contacts of the relay switches 1312 and 1322. As a result, both the first winding 31 and the second winding 32 of the dual three-phase motor 3 are connected in a Y connection.

[0190] Here, we will first explain the operation of power conversion when the power flow is in the direction of charging the battery 10. The charge / discharge controller 25 outputs a gate drive signal to the second inverter 22 and controls the output current of the second inverter 22 so that it has a current waveform that stops the dual three-phase motor 3 from rotating. For example, as shown in FIG. 4, the charge / discharge controller 25 controls the U-phase, V-phase, and W-phase currents so that the magnetic field inside the dual three-phase motor 3 becomes a high-frequency alternating magnetic field and a high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating. Note that when controlling the high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating, the charge / discharge controller 25 may also control the current waveform shown in FIG. 5 (alternating current or zero current with synchronized zero-cross timing). The charge / discharge controller 25 also outputs a gate drive signal to the first inverter 21 to turn off all IGBTs, causing the first inverter 21 to operate as a rectifier circuit.

[0191] At this time, when the high-frequency AC current output by second inverter 22 flows through second winding 32 of dual three-phase motor 3, dual three-phase motor 3 operates as a current transformer (CT), and a current flows through first winding 31 so as to cancel out the magnetic flux in the iron core of dual three-phase motor 3. This current is rectified by first inverter 21 and charges battery 10. Battery controller 15 also monitors the state of battery 10. Charge / discharge controller 25 acquires state information of battery 10 from battery controller 15 and controls the above-mentioned charging operation based on the acquired state information of battery 10.

[0192] Next, the operation of power conversion when power is flowing from the battery 10 to the DC power bus 204 will be described. The charge / discharge controller 25 outputs a gate drive signal to the first inverter 21 and controls the output current of the first inverter 21 to have a current waveform that stops the dual three-phase motor 3 from rotating. For example, as shown in FIG. 4, the charge / discharge controller 25 controls the output current of the first inverter 21 so that the magnetic field inside the dual three-phase motor 3 becomes a high-frequency alternating magnetic field and a high-frequency AC current waveform that stops the dual three-phase motor 3 from rotating. Note that when controlling the current waveform that stops the dual three-phase motor 3 from rotating, the charge / discharge controller 25 may also control the output current to have a high-frequency AC current waveform (high-frequency alternating current or zero current with synchronized zero-cross timing) as shown in FIG. 5. The charge / discharge controller 25 also outputs a gate drive signal to the second inverter 22 to turn off all IGBTs, causing the second inverter 22 to operate as a rectifier circuit.

[0193] At this time, when the high-frequency AC current output by first inverter 21 flows through first winding 31 of dual three-phase motor 3, dual three-phase motor 3 operates as a current transformer (CT), and a current flows through second winding 32 so as to cancel out the magnetic flux in the iron core of dual three-phase motor 3. This current is rectified by second inverter 22 and output to DC power bus 204 via relay switch 424, relay switch 524, inlet 114, and connector 124. In addition, battery controller 15 monitors the state of battery 10. Charge / discharge controller 25 acquires state information of battery 10 from battery controller 15 and controls the above-mentioned discharge operation based on the acquired state information of battery 10.

[0194] During charging and discharging operations, if the voltage of DC power supply bus 204 deviates from a predetermined range, charge / discharge controller 25 outputs an OFF signal to relay switch 424 and relay switch 524, opens the contacts of these relay switches, and turns OFF the gate drive signals of all inverters, in accordance with the measurement value of the voltage of DC power supply bus 204 measured by measurement unit 8 and the flowchart shown in Fig. 8. This disconnects second inverter 22 from inlet 114, connector 124, and DC power supply bus 204, and stops charging and discharging operations.

[0195] In this way, in addition to the processing described in the first embodiment (see FIG. 3), the charge / discharge controller 25 opens and closes the contacts of the relay switches 1311, 1312, 1321, and 1322, and changes the connection of the first winding 31 and the second winding 32 of the dual three-phase motor 3 to a Y connection or a Δ connection.

[0196] As a result, when the voltage of the DC power supply bus 204 is high and the DC side voltage of the second inverter 22 is higher than √3 times the voltage of the battery 10, the charge / discharge controller 25 connects the second winding 32 of the dual three-phase motor 3 to a Y connection and the first winding 31 of the dual three-phase motor 3 to a Δ connection, thereby reducing the voltage of the DC section (DC side) of the second inverter 22 to 1 / √3 and outputting it to the DC section (DC side) of the first inverter 21.At this time, the current becomes √3 times, so the current used to charge the battery 10 increases and the charging time can be shortened.

[0197] Furthermore, when the voltage of the DC power supply bus 204 is low and the DC side voltage of the second inverter 22 is lower than 1 / √3 times the voltage of the battery 10, the charge / discharge controller 25 connects the first winding 31 of the dual three-phase motor 3 to a Y connection and the second winding 32 of the dual three-phase motor 3 to a Δ connection, thereby reducing the voltage of the DC section (DC side) of the first inverter 21 to 1 / √3 and outputting it to the DC section (DC side) of the second inverter 22. At this time, the current becomes √3 times, so that the current supplied to the DC power supply bus 204 increases and the discharge power can be increased.

[0198] As described above, the charging / discharging system 1A (charging / discharging device 5A) according to this embodiment includes a relay switch 1311 (an example of a third relay switch) that opens and closes the connection of the delta connection of the first winding 31 (an example of one winding of a multiple winding), a relay switch 1312 (an example of a fourth relay switch) that opens and closes the connection of the neutral point of the first winding 31, a relay switch 1321 (an example of a fifth relay switch) that opens and closes the connection of the delta connection of the second winding 32 (an example of the other winding of a multiple winding), and a relay switch 1322 (an example of a sixth relay switch) that opens and closes the connection of the neutral point of the second winding 32.

[0199] When no charging or discharging is performed between the battery 10 and the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202), the charge / discharge controller 25 turns on the relay switch 1312 and the relay switch 1322 and turns off the relay switch 1311 and the relay switch 1321 (see step S203 in FIG. 11 ). In this case, both the first winding 31 and the second winding 32 of the dual three-phase motor 3 are connected in a Y-connection.

[0200] Furthermore, when charging / discharging between the battery 10 and the AC power supply source (the single-phase AC power supply system 201 or the three-phase AC power supply system 202), the charge / discharge controller 25 performs, for example, the following first control, second control, or third control. In the first control, the charge / discharge controller 25 turns on the relay switch 1312 and the relay switch 1322 and turns off the relay switch 1311 and the relay switch 1321 (see step S203 in FIG. 11). In this case, both the first winding 31 and the second winding 32 of the dual three-phase motor 3 are connected in a Y connection (no voltage step-up / step-down).

[0201] In addition, in the second control, the charge / discharge controller 25 turns on the relay switches 1312 and 1321 and turns off the relay switches 1311 and 1322 (see step S211 in FIG. 11). In this case, the first winding 31 of the dual three-phase motor 3 is connected in a Y connection, and the second winding 32 is connected in a Δ connection, so that the voltage increases in the direction in which the battery 10 is charged and decreases in the direction in which the battery 10 is discharged.

[0202] In addition, in the third control, the charge / discharge controller 25 turns on the relay switches 1311 and 1322 and turns off the relay switches 1312 and 1321 (see step S207 in FIG. 11). In this case, the first winding 31 of the dual three-phase motor 3 is connected in a delta connection, and the second winding 32 is connected in a Y connection, so that the voltage drops in the direction in which the battery 10 is charged and rises in the direction in which the battery 10 is discharged.

[0203] As a result, when charging the battery 10, the charging / discharging system 1A (charging / discharging device 5A) can increase the charging current to the battery 10 and shorten the charging time of the battery 10 when the voltage of the battery 10 is lower than 1 / √3 of the voltage of the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202).

[0204] Furthermore, when supplying (discharging) power from the battery 10 to an AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202), if the voltage of the battery 10 is higher than √3 times the voltage of the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202), the charging / discharging system 1A (charging / discharging device 5A) can increase the power supply current to the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202) and increase the power supply to the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202).

[0205] Although an example of the processing performed by the charge / discharge controller 25 in the charge / discharge system 1A has been described with reference to Fig. 11, the present invention is not limited to this. Next, another example of the processing performed by the charge / discharge controller 25 will be described, divided into the case of charging and the case of discharging. First, another example of the processing for charging will be described with reference to Fig. 12. FIG. 12 is a flowchart showing another example of the process performed by the charge / discharge controller during charging in the charge / discharge system according to this embodiment.

[0206] In step S301, the charge / discharge controller 25 determines whether the voltage of the DC section (DC side) of the second inverter 22 is higher than √3 times the voltage of the battery 10. If the charge / discharge controller 25 determines that the voltage of the DC section (DC side) of the second inverter 22 is higher than √3 times the voltage of the battery 10 (YES), the charge / discharge controller 25 proceeds to step S303, outputs an OFF signal to the relay switches 1312 and 1321 to open the contacts of the relay switches 1312 and 1321, and outputs an ON signal to the relay switches 1311 and 1322 to close the contacts of the relay switches 1311 and 1322. As a result, the first winding 31 of the dual three-phase motor 3 is connected in a Δ connection, and the second winding 32 is connected in a Y connection. As a result, the voltage of the DC section (DC side) of the second inverter 22 is stepped down to 1 / √3 and output to the DC section (DC side) of the first inverter 21.

[0207] On the other hand, if the charge / discharge controller 25 determines in step S301 that the voltage of the DC section (DC side) of the second inverter 22 is less than or equal to √3 times the voltage of the battery 10 (NO), it proceeds to step S305 and determines whether the voltage of the DC section (DC side) of the second inverter 22 is higher than 1 time the voltage of the battery 10.

[0208] If the charge / discharge controller 25 determines in step S305 that the voltage of the DC section (DC side) of the second inverter 22 is higher than one time the voltage of the battery 10 (YES), the charge / discharge controller 25 proceeds to step S307, where it outputs an OFF signal to the relay switches 1311 and 1321 to open the contacts of the relay switches 1311 and 1321, and outputs an ON signal to the relay switches 1312 and 1322 to close the contacts of the relay switches 1312 and 1322. As a result, both the first winding 31 and the second winding 32 of the dual three-phase motor 3 are connected in a Y connection. As a result, a voltage one time the voltage of the DC section (DC side) of the second inverter 22 is output to the DC section (DC side) of the first inverter 21.

[0209] On the other hand, if the charge / discharge controller 25 determines in step S305 that the voltage of the DC section (DC side) of the second inverter 22 is less than or equal to 1 time the voltage of the battery 10 (NO), it proceeds to step S309 and determines whether the voltage of the DC section (DC side) of the second inverter 22 is higher than 1 / √3 times the voltage of the battery 10.

[0210] If the charge / discharge controller 25 determines in step S309 that the voltage of the DC section (DC side) of the second inverter 22 is higher than 1 / √3 times the voltage of the battery 10 (YES), the charge / discharge controller 25 proceeds to step S311, where it outputs an OFF signal to the relay switches 1311 and 1322 to open the contacts of the relay switches 1311 and 1322, and outputs an ON signal to the relay switches 1312 and 1321 to close the contacts of the relay switches 1312 and 1321. As a result, the first winding 31 of the dual three-phase motor 3 is connected in a Y connection, and the second winding 32 is connected in a Δ connection. As a result, the DC section (DC side) voltage of the second inverter 22 is boosted by √3 times and output to the DC section (DC side) of the first inverter 21.

[0211] If the charge / discharge controller 25 determines in step S309 that the voltage of the DC section (DC side) of the second inverter 22 is 1 / √3 times or less the voltage of the battery 10 (NO), it proceeds to step S313 and outputs an OFF signal to the relay switches 1311, 1312, 1321, and 1322 to open the contacts of the relay switches 1311, 1312, 1321, and 1322, thereby stopping the charging operation.

[0212] If the coupling coefficient between the first winding 31 of the dual three-phase motor 3 and the second winding 32 of the dual three-phase motor 3 is not 1, the same effect can be achieved by replacing "√3" in steps S301 and S309 of Fig. 12 with the product of the coupling coefficient and √3, and by replacing "1" in step S305 with the product of the coupling coefficient and 1. When using the coupling coefficient as the determination threshold, it may be a value that takes into account variations in the specification values.

[0213] Next, another example of the process in the case of discharge will be described with reference to FIG. FIG. 13 is a flowchart showing another example of the process performed by the charge / discharge controller during charging in the charge / discharge system according to this embodiment.

[0214] In step S401, the charge / discharge controller 25 determines whether the voltage of the DC section (DC side) of the second inverter 22 is lower than 1 / √3 times the voltage of the battery 10. If the charge / discharge controller 25 determines that the voltage of the DC section (DC side) of the second inverter 22 is lower than 1 / √3 times the voltage of the battery 10 (YES), the charge / discharge controller 25 proceeds to step S403, outputs an OFF signal to the relay switches 1311 and 1322 to open the contacts of the relay switches 1311 and 1322, and outputs an ON signal to the relay switches 1312 and 1321 to close the contacts of the relay switches 1312 and 1321. As a result, the first winding 31 of the dual three-phase motor 3 is connected in a Y connection, and the second winding 32 is connected in a Δ connection. As a result, the DC section (DC side) voltage of the first inverter 21 is stepped down to 1 / √3 times and output to the DC section (DC side) of the second inverter 22.

[0215] On the other hand, if the charge / discharge controller 25 determines in step S401 that the voltage of the DC section (DC side) of the second inverter 22 is 1 / √3 times or more the voltage of the battery 10 (NO), it proceeds to step S405 and determines whether the voltage of the DC section (DC side) of the second inverter 22 is lower than 1 time the voltage of the battery 10.

[0216] If the charge / discharge controller 25 determines in step S405 that the voltage of the DC section (DC side) of the second inverter 22 is lower than one time the voltage of the battery 10 (YES), the charge / discharge controller 25 proceeds to step S407, where it outputs an OFF signal to the relay switches 1311 and 1321 to open the contacts of the relay switches 1311 and 1321, and outputs an ON signal to the relay switches 1312 and 1322 to close the contacts of the relay switches 1312 and 1322. As a result, both the first winding 31 and the second winding 32 of the dual three-phase motor 3 are connected in a Y connection. As a result, a voltage one time the voltage of the DC section (DC side) of the first inverter 21 is output to the DC section (DC side) of the second inverter 22.

[0217] On the other hand, if the charge / discharge controller 25 determines in step S405 that the voltage of the DC section (DC side) of the second inverter 22 is equal to or greater than 1 time the voltage of the battery 10 (NO), it proceeds to step S409 and determines whether the voltage of the DC section (DC side) of the second inverter 22 is lower than √3 times the voltage of the battery 10.

[0218] If the charge / discharge controller 25 determines in step S409 that the voltage of the DC section (DC side) of the second inverter 22 is lower than √3 times the voltage of the battery 10 (YES), the charge / discharge controller 25 proceeds to step S411, where it outputs an OFF signal to the relay switches 1312 and 1321 to open the contacts of the relay switches 1312 and 1321, and outputs an ON signal to the relay switches 1311 and 1322 to close the contacts of the relay switches 1311 and 1322. As a result, the first winding 31 of the dual three-phase motor 3 is connected in a Δ connection, and the second winding 32 is connected in a Y connection. As a result, the DC section (DC side) voltage of the first inverter 21 is boosted by √3 times and output to the DC section (DC side) of the second inverter 22.

[0219] If the charge / discharge controller 25 determines in step S409 that the voltage of the DC section (DC side) of the second inverter 22 is equal to or greater than √3 times the voltage of the battery 10 (NO), it proceeds to step S413 and outputs an OFF signal to the relay switches 1311, 1312, 1321, and 1322 to open the contacts of the relay switches 1311, 1312, 1321, and 1322, thereby stopping the charging operation.

[0220] If the coupling coefficient between the first winding 31 of the dual three-phase motor 3 and the second winding 32 of the dual three-phase motor 3 is not 1, the same effect can be achieved by replacing "√3" in steps S401 and S409 of Fig. 13 with the product of the coupling coefficient and √3, and by replacing "1" in step S405 with the product of the coupling coefficient and 1. When using the coupling coefficient as the determination threshold, it may be a value that takes into account variations in the specification values.

[0221] By operating the charge / discharge controller 25 in this manner, even if the voltage of the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202) or the DC power supply bus 204 is low and the voltage of the DC section (DC side) of the second inverter 22 is lower than the voltage of the battery 10, the charge / discharge controller 25 connects the second winding 32 of the dual three-phase motor 3 to a delta connection and the first winding 31 of the dual three-phase motor 3 to a Y connection, thereby boosting the voltage of the DC section (DC side) of the second inverter 22 and outputting it to the DC section (DC side) of the first inverter 21, thereby making it possible to charge the battery 10.

[0222] Furthermore, even if the voltage of the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202) or the DC power supply bus 204 is high and the voltage of the DC section (DC side) of the second inverter 22 is higher than the voltage of the battery 10, the charge / discharge controller 25 connects the second winding 32 of the dual three-phase motor 3 to a Y connection and the first winding 31 of the dual three-phase motor 3 to a Delta connection, thereby boosting the voltage of the DC section (DC side) of the first inverter 21 and outputting it to the DC section (DC side) of the second inverter 22, making it possible to supply (discharge) power from the battery 10 to the AC power supply source or the DC power supply bus 204.

[0223] The configuration of this embodiment is not limited to the above. For example, in the process of step S203, the charge / discharge controller 25 may output an OFF signal to the relay switches 1312 and 1322 to open the contacts of the relay switches 1312 and 1322, and output an ON signal to the relay switches 1311 and 1321 to close the contacts of the relay switches 1311 and 1321, thereby causing both the first winding 31 and the second winding 32 of the dual three-phase motor 3 to be connected in a Δ connection.

[0224] Furthermore, the positions at which contacts 1311a, 1311b, and 1311c of relay switch 1311 are connected need not be limited to the connection positions shown in Fig. 10, as long as closing all of the contacts of relay switch 1311 connects first winding 31 to a delta connection. Fig. 14 is a diagram showing another example of the connection of relay switch 1311 (an example of a third relay switch) according to this embodiment. For example, contacts 1311a, 1311b, and 1311c of relay switch 1311 may be connected to first winding 31 as shown in Fig. 14.

[0225] Similarly, the positions at which contacts 1321a, 1321b, and 1321c of relay switch 1321 are connected need only be such that the wiring of second winding 32 is connected to a delta connection by closing all of the contacts of relay switch 1321, and are not limited to the connection positions shown in Fig. 10. For example, each contact of relay switch 1321 may be connected to second winding 32, similar to the connection of each contact of relay switch 1311 to first winding 31 shown in Fig. 14.

[0226] Furthermore, the positions at which contacts 1312a, 1312b, and 1312c of relay switch 1312 are connected need not be limited to the connection positions shown in Fig. 10, as long as the neutral point of first winding 31 can be formed by closing all of the contacts of relay switch 1312. Fig. 15 is a diagram showing another example of the connection of relay switch 1312 (an example of the fourth relay switch) according to this embodiment. For example, contacts 1312a, 1312b, and 1312c of relay switch 1312 may be connected to first winding 31 as shown in Fig. 15.

[0227] Similarly, the positions at which contacts 1322a, 1322b, and 1322c of relay switch 1322 are connected need not be limited to the connection positions shown in Fig. 10, as long as the neutral point of second winding 32 can be formed by closing all of relay switch 1322. For example, each contact of relay switch 1322 may be connected to second winding 32, similar to the connection of each contact of relay switch 1312 to first winding 31 shown in Fig. 15.

[0228] It is also possible to record a program for realizing the functions of the charge / discharge controller 25 (an example of a control unit) on a computer-readable recording medium, and have a computer system read and execute the program to perform the processing of the charge / discharge controller 25. Note that the term "computer system" here includes hardware such as an OS and peripheral devices.

[0229] Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, the term "computer-readable recording medium" also includes devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs over networks like the Internet or communication lines like telephone lines, and devices that store programs for a fixed period of time, such as volatile memory within the computer systems that serve as servers or clients. The program may be a program that implements part of the aforementioned functions, or may be a program that can implement the aforementioned functions in combination with a program already stored in the computer system. The program may also be stored on a designated server and distributed (e.g., downloaded) over communication lines in response to requests from other devices.

[0230] Furthermore, some or all of the functions of the charge / discharge controller 25 may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each function may be implemented as a processor individually, or some or all of the functions may be integrated into a processor. The integrated circuit method is not limited to LSI, and may be implemented using a dedicated circuit or a general-purpose processor. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology, an integrated circuit based on that technology may be used.

[0231] In the above embodiment, the charging / discharging system 1, 1A (charging / discharging device 5, 5A) that charges / discharges between the battery 10 and an AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202) or the DC power supply bus 204 has been described. The charging / discharging system 1, 1A (charging / discharging device 5, 5A) has a function of charging the battery 10 from the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202) or the DC power supply bus 204, and a function of supplying (discharging) power from the battery 10 to the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202) or the DC power supply bus 204. In other words, the charging / discharging system 1, 1A (charging / discharging device 5, 5A) functions as a charging device that has a function of charging the battery 10 from the AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202) or the DC power supply bus 204. In addition, the charging / discharging system 1, 1A (charging / discharging device 5, 5A) also functions as a power supply (discharging) device that supplies (discharges) power from the battery 10 to an AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202) or a DC power bus 204.

[0232] The charging / discharging system 1, 1A (charging / discharging device 5, 5A) may have any one of the above functions. That is, the charging / discharging system 1, 1A (charging / discharging device 5, 5A) may be configured as a charging device having, among the functions of the charging / discharging system 1, 1A (charging / discharging device 5, 5A), a function of charging the battery 10 from an AC power supply source (single-phase AC power supply system 201 or three-phase AC power supply system 202) or a DC power supply bus 204. Also, the charging / discharging system 1, 1A (charging / discharging device 5, 5A) may be configured as a power supply device having, among the functions of the charging / discharging system 1, 1A (charging / discharging device 5, 5A), a function of supplying power from the battery 10 to the AC power supply source or the DC power supply bus 204.

[0233] The above has described in detail the embodiments of the present disclosure with reference to the drawings, but the specific configurations are not limited to these embodiments, and the embodiments of the present disclosure can be modified or omitted as appropriate. [Explanation of symbols]

[0234] 1. Charging and discharging system 5, 5A charging / discharging device 8. Measurement section 10 Battery 15 Battery Controller 21 First inverter 21aH First inverter U-phase upper arm IGBT and FWD 21aL First inverter U-phase lower arm IGBT and FWD 21bH First inverter V-phase upper arm IGBT and FWD 21bL First inverter V-phase lower arm IGBT and FWD 21cH First inverter W-phase upper arm IGBT and FWD 21cL First inverter W-phase lower arm IGBT and FWD 22 Second inverter 22aH Second inverter U-phase upper arm IGBT and FWD 22aL Second inverter U-phase lower arm IGBT and FWD 22bH Second inverter V-phase upper arm IGBT and FWD 22bL Second inverter V-phase lower arm IGBT and FWD 22cH W-phase upper arm IGBT and FWD of second inverter 22cL W-phase lower arm IGBT and FWD of second inverter 23 Third inverter 25 Charge / Discharge Controller 3 Dual three-phase motor 31a U-phase winding of the first winding of a dual three-phase motor 31b V-phase winding of the first winding of a dual three-phase motor 31c W-phase winding of the first winding of a dual three-phase motor 32 Second winding of a dual three-phase motor 32a U-phase winding of the second winding of a dual three-phase motor 32b V-phase winding of the second winding of a dual three-phase motor 32c W-phase winding of the second winding of a dual three-phase motor 412, 423, 424 Relay Switch 512, 523, 524 Relay Switch 6 Filters 71, 72 Interconnection relay 111, 112, 114 Inlets 121, 122, 124 Connectors 1311, 1312, 1321, 1322 relay switches 1311a~c, 1312a~c, 1321a~c, 1322a~c contacts 201 Single-phase AC power system 202 Three-phase AC power system 204 DC Power Bus

Claims

1. A power supply device that supplies power from a battery to an AC power supply source, a motor having multiple windings; a first inverter connected between a first winding of the multiple windings and the battery, for converting DC power from the battery into AC power and outputting the AC power to the motor when power from the battery is supplied to the AC power supply source; a second inverter connected to a second winding of the multiple windings, which converts AC power output by the motor into DC power and outputs the DC power when power from the battery is supplied to the AC power supply source; an interconnection relay connected to one end thereof with the AC power supply source and configured to open and close a connection with the AC power supply source in response to an external command; a third inverter connected to the other end of the grid-connection relay, which converts DC power output by the second inverter into AC power and outputs the AC power to the AC power supply source via the grid-connection relay; a first relay switch, one of which is connected to the DC side of the second inverter and the other of which is connected to the DC side of the third inverter, for opening and closing the connection between the DC side of the second inverter and the DC side of the third inverter in response to an external command; a measuring unit that measures the voltage and frequency of the AC power supply source; a battery monitoring unit that monitors the state of the battery; a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter, and the grid-connection relay based on the inputs; Equipped with The control unit When power is supplied from the battery to the AC power supply source, a drive signal for closing the connection of the first relay switch is output to the first relay switch as the external command; When the voltage and frequency of the AC power supply source measured by the measurement unit are within a predetermined range, a drive signal for closing the connection of the interconnection relay is output to the interconnection relay as the external command. Power supply device.

2. a second relay switch, one of which is connected to the DC side of the first inverter and the other of which is connected to the DC side of the second inverter, for opening and closing the connection between the DC side of the first inverter and the DC side of the second inverter in response to an external command; Equipped with The control unit When power from the battery is not supplied to the AC power supply source, a drive signal for opening the first relay switch is output as the external command to the first relay switch, and a drive signal for closing the second relay switch is output as the external command to the second relay switch. The power supply device according to claim 1 .

3. a third relay switch that opens and closes the connection of the delta connection of the first winding; a fourth relay switch that opens and closes the connection of the neutral point of the first winding; a fifth relay switch that opens and closes the connection of the delta connection of the second winding; a sixth relay switch that opens and closes the connection of the neutral point of the second winding; Equipped with The control unit When power from the battery is not supplied to the AC power supply source, turning on the fourth relay switch and the sixth relay switch, and turning off the third relay switch and the fifth relay switch; Alternatively, the third relay switch and the fifth relay switch are turned ON, and the fourth relay switch and the sixth relay switch are turned OFF, When power from the battery is supplied to the AC power supply source, turning on the fourth relay switch and the sixth relay switch, and turning off the third relay switch and the fifth relay switch; Alternatively, the fourth relay switch and the fifth relay switch are turned ON, and the third relay switch and the sixth relay switch are turned OFF. Alternatively, the third relay switch and the sixth relay switch are turned ON, and the fourth relay switch and the fifth relay switch are turned OFF. The power supply device according to claim 1 .

4. The control unit When power from the battery is supplied to the AC power supply source, when a difference between a product of √3 times the DC side voltage of the second inverter and a coupling coefficient between one winding and the other winding of the multiplex winding, and a voltage of the battery, is greater than a predetermined value, the fourth relay switch and the fifth relay switch are turned ON, and the third relay switch and the sixth relay switch are turned OFF. The power supply device according to claim 3 .

5. When power from the battery is supplied to the AC power supply source, the waveform of the output current of the first inverter is a current waveform that causes the motor to stop rotating. The power supply device according to any one of claims 1 to 4.

6. When power from the battery is supplied to the AC power supply source, the waveforms of the output currents of the first inverter are alternating currents or zero currents with coincident zero-cross timings, and the sum of the currents of the phases is zero. The power supply device according to any one of claims 1 to 4.

7. A charging device that charges a battery with power from an AC power supply source, a motor having multiple windings; a first inverter connected between a first winding of the multiple windings and the battery, for converting AC power output by the motor into DC power and outputting the DC power to the battery when the battery is charged with power from the AC power supply source; a second inverter connected to a second winding of the multiple windings, which converts DC power into AC power and outputs the AC power to the motor when the battery is charged with power from the AC power supply source; an interconnection relay connected to one end thereof with the AC power supply source and configured to open and close a connection with the AC power supply source in response to an external command; a third inverter connected to the other end of the grid-connection relay, which, when charging the battery with power from the AC power supply source, converts AC power from the AC power supply source connected via the grid-connection relay into DC power and outputs the DC power; a first relay switch, one of which is connected to the DC side of the second inverter and the other of which is connected to the DC side of the third inverter, for opening and closing the connection between the DC side of the second inverter and the DC side of the third inverter in response to an external command; a measuring unit that measures the voltage and frequency of the AC power supply source; a battery monitoring unit that monitors the state of the battery; a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter, and the grid-connection relay based on the inputs; Equipped with The control unit When charging the battery with power from the AC power supply source, a drive signal for closing the connection of the first relay switch is output to the first relay switch as the external command; When the voltage and frequency of the AC power supply source measured by the measurement unit are within a predetermined range, a drive signal for closing the connection of the interconnection relay is output to the interconnection relay as the external command. Charging device.

8. a second relay switch, one of which is connected to the DC side of the first inverter and the other of which is connected to the DC side of the second inverter, for opening and closing the connection between the DC side of the first inverter and the DC side of the second inverter in response to an external command; Equipped with The control unit When the battery is not charged with power from the AC power supply source, a drive signal for opening the connection of the first relay switch is output to the first relay switch as the external command, and a drive signal for closing the connection of the second relay switch is output to the second relay switch as the external command. The charging device according to claim 7.

9. a third relay switch that opens and closes the connection of the delta connection of the first winding; a fourth relay switch that opens and closes the connection of the neutral point of the first winding; a fifth relay switch that opens and closes the connection of the delta connection of the second winding; a sixth relay switch that opens and closes the connection of the neutral point of the second winding; Equipped with The control unit When the battery is not being charged with power from the AC power supply, turning on the fourth relay switch and the sixth relay switch, and turning off the third relay switch and the fifth relay switch; Alternatively, the third relay switch and the fifth relay switch are turned ON, and the fourth relay switch and the sixth relay switch are turned OFF, When the battery is charged with power from the AC power supply, turning on the fourth relay switch and the sixth relay switch, and turning off the third relay switch and the fifth relay switch; Alternatively, the fourth relay switch and the fifth relay switch are turned ON, and the third relay switch and the sixth relay switch are turned OFF. Alternatively, the third relay switch and the sixth relay switch are turned ON, and the fourth relay switch and the fifth relay switch are turned OFF. The charging device according to claim 7.

10. The control unit When the battery is charged with power from the AC power supply, When the difference between the product of the voltage of the battery multiplied by √3 and the coupling coefficient between one winding and the other winding of the multiple winding, and the DC side voltage of the second inverter is greater than a predetermined value, turning on the third relay switch and the sixth relay switch, and turning off the fourth relay switch and the fifth relay switch; The charging device according to claim 9.

11. When the battery is charged with power from the AC power supply source, the waveform of the output current of the second inverter is a current waveform that causes the motor to stop rotating. The charging device according to any one of claims 7 to 10.

12. When the battery is charged with power from the AC power supply source, the waveforms of the output currents of the respective phases of the second inverter are alternating currents or zero currents with coincident zero-cross timings, and the sum of the currents of the respective phases is zero. The charging device according to any one of claims 7 to 10.

13. A charging / discharging device that charges and discharges between a battery and an AC power supply source, a motor having multiple windings; a first inverter connected between one winding of the multiple windings and the battery, for converting AC power output by the motor into DC power and outputting the DC power to the battery when charging the battery, and for converting DC power from the battery into AC power and outputting the AC power to the motor when discharging the battery; a second inverter connected to the other winding of the multiple windings, for converting DC power into AC power and outputting the AC power to the motor when charging the battery, and for converting AC power output by the motor into DC power and outputting the DC power when discharging the battery; an interconnection relay connected to one end thereof with the AC power supply source and configured to open and close a connection with the AC power supply source in response to an external command; a third inverter connected to the other end of the grid-connection relay, which converts AC power from the AC power supply source connected via the grid-connection relay into DC power and outputs the DC power when charging the battery, and converts DC power output by the second inverter into AC power and outputs the AC power to the AC power supply source via the grid-connection relay when discharging the battery; a first relay switch, one of which is connected to the DC side of the second inverter and the other of which is connected to the DC side of the third inverter, for opening and closing the connection between the DC side of the second inverter and the DC side of the third inverter in response to an external command; a measuring unit that measures the voltage and frequency of the AC power supply source; a battery monitoring unit that monitors the state of the battery; a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter, and the grid-connection relay based on the inputs; Equipped with The control unit When charging or discharging between the battery and the AC power supply source, a drive signal for closing the connection of the first relay switch is output to the first relay switch as the external command; When the voltage and frequency of the AC power supply source measured by the measurement unit are within a predetermined range, a drive signal for closing the connection of the interconnection relay is output to the interconnection relay as the external command. Charge / discharge device.

14. a second relay switch, one of which is connected to the DC side of the first inverter and the other of which is connected to the DC side of the second inverter, for opening and closing the connection between the DC side of the first inverter and the DC side of the second inverter in response to an external command; Equipped with The control unit When no charge or discharge is performed between the battery and the AC power supply source, a drive signal for opening the first relay switch is output as the external command to the first relay switch, and a drive signal for closing the second relay switch is output as the external command to the second relay switch. The charging / discharging device according to claim 13.

15. a third relay switch that opens and closes the connection of a delta connection of one winding of the multiple windings; a fourth relay switch that opens and closes the connection of the neutral point of one of the multiple windings; a fifth relay switch that opens and closes the connection of the delta connection of the other winding of the multiple windings; a sixth relay switch that opens and closes the connection of the neutral point of the other winding of the multiple windings; Equipped with The control unit When no charge or discharge is performed between the battery and the AC power supply source, turning on the fourth relay switch and the sixth relay switch, and turning off the third relay switch and the fifth relay switch; Alternatively, the third relay switch and the fifth relay switch are turned ON, and the fourth relay switch and the sixth relay switch are turned OFF, When charging and discharging between the battery and the AC power supply source, turning on the fourth relay switch and the sixth relay switch, and turning off the third relay switch and the fifth relay switch; Alternatively, the fourth relay switch and the fifth relay switch are turned ON, and the third relay switch and the sixth relay switch are turned OFF. Alternatively, the third relay switch and the sixth relay switch are turned ON, and the fourth relay switch and the fifth relay switch are turned OFF. The charging / discharging device according to claim 13.

16. When charging and discharging between the battery and the AC power supply source, The control unit Turning the fourth relay switch and the sixth relay switch ON and turning the third relay switch and the fifth relay switch OFF, or Alternatively, the fourth relay switch and the fifth relay switch are turned on, and the third relay switch and the sixth relay switch are turned off, Alternatively, the third relay switch and the sixth relay switch are turned on, and the fourth relay switch and the fifth relay switch are turned off. determining the coupling coefficient between one winding and the other winding of the multiple windings based on the voltage of the battery, the DC side voltage of the second inverter, and The charging / discharging device according to claim 15.

17. When the battery is charged from the AC power supply source, the waveform of the output current of the second inverter is a current waveform that causes the motor to stop rotating. and when discharging from the battery to the AC power supply source, the waveform of the output current of the first inverter is a current waveform that causes the motor to stop rotating. The charging / discharging device according to any one of claims 13 to 16.

18. When the battery is charged from the AC power supply source, the waveforms of the output currents of the respective phases of the second inverter are alternating currents or zero currents with the same zero crossing timing, and the sum of the currents of the respective phases is zero. and when discharging from the battery to the AC power supply source, the waveforms of the output currents of the respective phases of the first inverter are alternating currents or zero currents with the same zero crossing timing, and the sum of the currents of the respective phases is zero. The charging / discharging device according to any one of claims 13 to 16.

19. A charging / discharging system including a battery, an AC power supply source, and a charging / discharging device that charges and discharges between the battery and the AC power supply source, a motor having multiple windings; a first inverter connected between one winding of the multiple windings and the battery, for converting AC power output by the motor into DC power and outputting the DC power to the battery when charging the battery, and for converting DC power from the battery into AC power and outputting the AC power to the motor when discharging the battery; a second inverter connected to the other winding of the multiple windings, for converting DC power into AC power and outputting the AC power to the motor when charging the battery, and for converting AC power output by the motor into DC power and outputting the DC power when discharging the battery; an interconnection relay connected to one end thereof with the AC power supply source and configured to open and close a connection with the AC power supply source in response to an external command; a third inverter connected to the other end of the grid-connection relay, which converts AC power from the AC power supply source connected via the grid-connection relay into DC power and outputs the DC power when charging the battery, and converts DC power output by the second inverter into AC power and outputs the AC power to the AC power supply source via the grid-connection relay when discharging the battery; a first relay switch, one of which is connected to the DC side of the second inverter and the other of which is connected to the DC side of the third inverter, for opening and closing the connection between the DC side of the second inverter and the DC side of the third inverter in response to an external command; a measuring unit that measures the voltage and frequency of the AC power supply source; a battery monitoring unit that monitors the state of the battery; a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter, and the grid-connection relay based on the inputs; Equipped with The control unit When charging or discharging between the battery and the AC power supply source, a drive signal for closing the connection of the first relay switch is output to the first relay switch as the external command; When the voltage and frequency of the AC power supply source measured by the measurement unit are within a predetermined range, a drive signal for closing the connection of the interconnection relay is output to the interconnection relay as the external command. Charging and discharging system.

20. a motor having multiple windings; a first inverter connected between a first winding of the multiple windings and a battery, and configured to convert DC power from the battery into AC power and output the AC power to the motor when power from the battery is supplied to an AC power supply source; a second inverter connected to a second winding of the multiple windings, and configured to convert AC power output by the motor into DC power and output the DC power when power from the battery is supplied to the AC power supply source; a grid-connected relay connected to one end of the AC power supply source and configured to open and close the connection with the AC power supply source in response to an external command; and a grid-connected relay connected to the other end of the grid-connected relay, and configured to convert DC power output by the second inverter into AC power and output the DC power via the grid-connected relay. a third inverter that outputs to an AC power supply source; a first relay switch that has one side connected to a DC side of the second inverter and the other side connected to the DC side of the third inverter and that opens and closes the connection between the DC side of the second inverter and the DC side of the third inverter in response to an external command; a measurement unit that measures a voltage and a frequency of the AC power supply source; a battery monitoring unit that monitors a state of the battery; and a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter and the grid-connection relay based on the inputs, When the control unit supplies power from the battery to the AC power supply source, outputting a drive signal to close the connection of the first relay switch as the external command to the first relay switch; outputting, to the interconnection relay as the external command, a drive signal for closing a connection of the interconnection relay when the voltage and frequency of the AC power supply source measured by the measurement unit are within a predetermined range; A control method comprising:

21. a motor having multiple windings; a first inverter connected between a first winding of the multiple windings and a battery, the first inverter converting AC power output by the motor into DC power and outputting the DC power to the battery when the battery is charged with power from an AC power supply source; a second inverter connected to a second winding of the multiple windings, the second inverter converting DC power into AC power and outputting the AC power to the motor when the battery is charged with power from the AC power supply source; a grid-connected relay connected to one end of the grid-connected relay and opening and closing a connection with the AC power supply source in response to an external command; and a second inverter connected to the other end of the grid-connected relay and connected via the grid-connected relay when the battery is charged with power from the AC power supply source. a third inverter that converts AC power from a power supply source into DC power and outputs the DC power; a first relay switch that has one side connected to the DC side of the second inverter and the other side connected to the DC side of the third inverter and that opens and closes the connection between the DC side of the second inverter and the DC side of the third inverter in response to an external command; a measurement unit that measures the voltage and frequency of the AC power supply source; a battery monitoring unit that monitors a state of the battery; and a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter and the grid-connection relay based on the inputs, When the control unit charges the battery with power from the AC power supply source, outputting a drive signal to close the connection of the first relay switch as the external command to the first relay switch; outputting, to the interconnection relay as the external command, a drive signal for closing a connection of the interconnection relay when the voltage and frequency of the AC power supply source measured by the measurement unit are within a predetermined range; A control method comprising:

22. a motor having multiple windings; a first inverter connected between one winding of the multiple windings and a battery, for converting AC power output by the motor into DC power and outputting the DC power to the battery when charging the battery, and for converting DC power from the battery into AC power and outputting the DC power to the motor when discharging the battery; a second inverter connected to the other winding of the multiple windings, for converting DC power into AC power and outputting the DC power to the motor when charging the battery, and for converting AC power output by the motor into DC power and outputting the DC power when discharging the battery; a grid-connected relay connected to one end of an AC power supply source and for opening and closing a connection with the AC power supply source in response to an external command; and a second inverter connected to the other end of the grid-connected relay, for connecting AC power from the AC power supply source connected via the grid-connected relay to the other end of the grid-connected relay when charging the battery. a third inverter that converts the DC power output by the second inverter into AC power and outputs it to the AC power supply source via the grid-connection relay when discharging the battery, a first relay switch having one side connected to the DC side of the second inverter and the other connected to the DC side of the third inverter, and opening and closing the connection between the DC side of the second inverter and the DC side of the third inverter in response to an external command, a measurement unit that measures a voltage and a frequency of the AC power supply source, a battery monitoring unit that monitors a state of the battery, and a control unit that receives outputs from the measurement unit and the battery monitoring unit and outputs drive signals to the first inverter, the second inverter, the third inverter and the grid-connection relay based on the inputs, When the control unit charges and discharges between the battery and the AC power supply source, outputting a drive signal to close the connection of the first relay switch as the external command to the first relay switch; outputting, to the interconnection relay as the external command, a drive signal for closing a connection of the interconnection relay when the voltage and frequency of the AC power supply source measured by the measurement unit are within a predetermined range; A control method comprising:

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