Power supply system, mobile unit, control method and program for power supply system

Abstract

The present invention provides a better power supply system, a mobile device having a better power supply system, a method for controlling a better power supply system, and a program for causing a computer to execute the method for controlling a better power supply system. [Solution] In the power supply system 10, when the supply of DC power from the first power generator 14a to the first power supply circuit 18a is interrupted, the control device 30 performs a first power suppression control on the first inverter 15a to reduce the power supplied to the first motor 17a from the first inverter 15a to less than the power supplied to the first power supply circuit from the first power generator before the interruption occurred, and performs a second power increase control on the second inverter 15b to increase the power supplied to the first motor from the second inverter 15b to more than the power supplied to the first power supply circuit from the first power generator before the interruption occurred.

Description

Technical Field

[0001] The present disclosure relates to a power supply system, a moving body, a control method for a power supply system, and a program.

Background Art

[0002] Japanese Patent Publication No. 2022-529997 discloses an aircraft electrical energy supply network (power supply system).

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a long-felt need for a better power supply system, a moving body having a better power supply system, a control method for a better power supply system, and a program for causing a computer to execute a control method for a better power supply system.

[0005] The present disclosure aims to solve the above-described problems.

Means for Solving the Problems

[0006] A first aspect of the present disclosure comprises: a first power supply circuit that supplies DC power output from a first power generator to a first inverter; a first energy storage device connected in parallel with the first power generator to the first power supply circuit; a second power supply circuit that supplies DC power output from a second power generator to a second inverter; a second energy storage device connected in parallel with the second power generator to the second power supply circuit; a first motor which is a dual three-phase motor that can be driven by power converted to AC by the first inverter and can also be driven by power converted to AC by the second inverter; and a control device that controls the first inverter and the second inverter. 1. When the supply of DC power to the power supply circuit is interrupted, the control device performs a first power suppression control on the first inverter, which reduces the first ratio, the ratio of the first power supplied from the first inverter to the first motor to the power consumption of the first motor, to less than before the supply of DC power from the first generator to the first power supply circuit was interrupted. At the same time, it performs a second power increase control on the second inverter, which increases the second ratio, the ratio of the second power supplied from the second inverter to the first motor to the power consumption of the first motor, to more than before the supply of DC power from the first generator to the first power supply circuit was interrupted.

[0007] A second aspect of this disclosure is a mobile device having a power supply system according to the first aspect.

[0008] A third aspect of the present disclosure is a control method for a power supply system comprising: a first power supply circuit that supplies DC power output from a first power generator to a first inverter; a first energy storage device connected in parallel with the first power generator to the first power supply circuit; a second power supply circuit that supplies DC power output from a second power generator to a second inverter; a second energy storage device connected in parallel with the second power generator to the second power supply circuit; and a first motor which is a dual three-phase motor that can be driven by power converted to AC by the first inverter and can also be driven by power converted to AC by the second inverter, wherein the first power supply This is a control method for a power supply system, in which, when the supply of DC power to the circuit is interrupted, a first power suppression control is performed on the first inverter to reduce the first ratio, which is the ratio of the first power supplied from the first inverter to the first motor to the power consumption of the first motor, to less than before the supply of DC power from the first power generator to the first power supply circuit was interrupted, and a second power increase control is performed on the second inverter to increase the second ratio, which is the ratio of the second power supplied from the second inverter to the first motor to the power consumption of the first motor, to more than before the supply of DC power from the first power generator to the first power supply circuit was interrupted.

[0009] A fourth aspect of this disclosure is a program that causes a computer to execute the control method for a power supply system according to the third aspect. [Effects of the Invention]

[0010] According to this disclosure, it is possible to provide a better power supply system, a mobile body having a better power supply system, a method for controlling a better power supply system, and a program for causing a computer to execute the method for controlling a better power supply system. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram of a power supply system in one embodiment. [Figure 2]Figure 2 shows the operation of a power supply system under normal conditions in one embodiment. [Figure 3] Figure 3 shows the operation of the power supply system during an abnormal situation in one embodiment. [Figure 4] Figure 4 shows the operation of the power supply system during an abnormal situation in one embodiment. [Figure 5] Figure 5 shows the operation of the power supply system during an abnormal situation in one embodiment. [Figure 6] Figure 6 is a control block diagram of a control device in one embodiment. [Figure 7] Figure 7 is a flowchart showing a fail-safe control in one embodiment. [Figure 8] Figures 8A to 8C are graphs showing the time changes in the state of the power supply system before and after the point in time when the first power supply system and the second power supply system were connected. [Figure 9] Figures 9A to 9C are graphs showing the time changes in the state of the power supply system before and after the point in time when the first power supply system and the second power supply system were connected. [Figure 10] Figure 10 is a schematic diagram of the power supply system in the comparative example. [Modes for carrying out the invention]

[0012] Conventionally, power supply systems equipped with two power supply systems, a first power supply system and a second power supply system, have been proposed as power supply systems to be installed on electric vertical take-off and landing aircraft (eVTOLs).

[0013] The first power supply system is a system that supplies power to the first motor, and includes a first power generation device as the main power source, a first energy storage device as the auxiliary power source, and a first power supply circuit that supplies power from the first power generation device to the first motor. The second power supply system is a system that supplies power to the second motor, and includes a second power generation device as the main power source, a second energy storage device as the auxiliary power source, and a second power supply circuit that supplies power from the second power generation device to the second load device. Each of the first motor and the second motor is a motor that drives each VTOL rotor mounted on the eVTOL.

[0014] When the first power generation device cannot supply power to the first power supply circuit, the first motor needs to be driven using only the power of the first energy storage device. Therefore, in the conventional power supply system, the output torque of the first motor is suppressed to make the driving time of the first motor as long as possible. Also, in the second motor, the output torque is increased to compensate for the amount by which the output torque of the first motor is suppressed, ensuring the lift thrust for the entire eVTOL.

[0015] However, in the conventional power supply system, even if the lift thrust for the entire eVTOL can be ensured, it is difficult to maintain the balance of the lift thrust of the VTOL rotors, and there is a risk that it will be difficult to maintain the attitude of the aircraft.

[0016] In the present disclosure, the output torque of the first motor can be ensured even when the first power generation device cannot supply power to the first power supply circuit. Hereinafter, the power supply system of the present disclosure, the moving body having the power supply system, the control method of the power supply system, and the program for causing a computer to execute the control method of the power supply system will be described.

[0017] [Configuration of Power Supply System] [Configuration of Power Supply System] FIG. 1 is a schematic diagram of a power supply system 10 in an embodiment. The power supply system 10 includes a first power supply system 12a and a second power supply system 12b. The first power supply system 12a includes a first power generation device 14a as a main power source, a first energy storage device 16a as an auxiliary power source, and a third energy storage device 16c. The second power supply system 12b includes a second power generation device 14b as a main power source, a second energy storage device 16b as an auxiliary power source, and a fourth energy storage device 16d.

[0018] The first power supply system 12a includes a first power supply circuit 18a and a third power supply circuit 18c. The first power supply circuit 18a supplies the DC power output from the first power generation device 14a to the first inverter 15a and the third inverter 15c. The third power supply circuit 18c supplies the DC power output from the first power generation device 14a to the fifth inverter 15e and the seventh inverter 15g.

[0019] The second power supply system 12b includes a second power supply circuit 18b and a fourth power supply circuit 18d. The second power supply circuit 18b supplies the DC power output from the second power generation device 14b to the second inverter 15b and the fourth inverter 15d. The fourth power supply circuit 18d supplies the DC power output from the second power generation device 14b to the sixth inverter 15f and the eighth inverter 15h.

[0020] The first power generation device 14a and the second power generation device 14b have an engine, a generator, and a power control unit (not shown). The generator is driven by the engine, and the generator generates three-phase AC power. The power control unit converts the three-phase AC power into DC power.

[0021] The first power generation device 14a and the second power generation device 14b may have various sensors such as voltage sensors and current sensors, and each element such as fuses, relays, breakers, diodes, transistors, resistors, coils, and capacitors.

[0022] The first inverter 15a converts the input DC power into three-phase AC power and outputs it to the first motor 17a. The second inverter 15b converts the input DC power into three-phase AC power and outputs it to the first motor 17a. The third inverter 15c converts the input DC power into three-phase AC power and outputs it to the second motor 17b. The fourth inverter 15d converts the input DC power into three-phase AC power and outputs it to the second motor 17b. The fifth inverter 15e converts the input DC power into three-phase AC power and outputs it to the third motor 17c. The sixth inverter 15f converts the input DC power into three-phase AC power and outputs it to the third motor 17c. The seventh inverter 15g converts the input DC power into three-phase AC power and outputs it to the fourth motor 17d. The eighth inverter 15h converts the input DC power into three-phase AC power and outputs it to the fourth motor 17d.

[0023] Each of the first motor 17a, second motor 17b, third motor 17c, and fourth motor 17d is a dual three-phase motor.

[0024] The power supply system 10 includes a first connection circuit 22a and a second connection circuit 22b. The first connection circuit 22a is equipped with a first connection device 24a that can connect the first power supply circuit 18a and the second power supply circuit 18b. The second connection circuit 22b is equipped with a second connection device 24b that can connect the third power supply circuit 18c and the fourth power supply circuit 18d.

[0025] The first connection device 24a and the second connection device 24b have contactors. The first connection device 24a and the second connection device 24b may have relays. The first connection device 24a and the second connection device 24b may have circuit breakers. The first connection device 24a and the second connection device 24b may have semiconductor switches.

[0026] Normally, the first power supply circuit 18a and the second power supply circuit 18b are disconnected by the first connection device 24a, and the third power supply circuit 18c and the fourth power supply circuit 18d are disconnected by the second connection device 24b. In other words, the first power supply system 12a and the second power supply system 12b are not connected. This prevents the effects of an abnormality in one of the power supply systems from spreading to the other. For example, even if a short circuit occurs in the first power supply system 12a, and power cannot be supplied from the first power supply system 12a to the first motor 17a, the second motor 17b, the third motor 17c, and the fourth motor 17d, the power supplied from the second power supply system 12b will allow the first motor 17a, the second motor 17b, the third motor 17c, and the fourth motor 17d to continue to operate.

[0027] If the supply of DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c is interrupted, the first power supply circuit 18a and the second power supply circuit 18b are connected by the first connection device 24a. In addition, the third power supply circuit 18c and the fourth power supply circuit 18d are connected by the second connection device 24b. As a result, power is supplied from the second power generator 14b to the first power supply circuit 18a and the third power supply circuit 18c.

[0028] If the supply of DC power from the second power generator 14b to the second power supply circuit 18b and the fourth power supply circuit 18d is interrupted, the first power supply circuit 18a and the second power supply circuit 18b are connected by the first connection device 24a. In addition, the third power supply circuit 18c and the fourth power supply circuit 18d are connected by the second connection device 24b. As a result, power is supplied from the first power generator 14a to the second power supply circuit 18b and the fourth power supply circuit 18d.

[0029] The power supply system 10 includes circuit breakers 26a to 26d. Circuit breaker 26a can disconnect the first power generator 14a from the first power supply circuit 18a and the first connection circuit 22a. Circuit breaker 26b can disconnect the second power generator 14b from the second power supply circuit 18b and the first connection circuit 22a. Circuit breaker 26c can disconnect the first power generator 14a from the third power supply circuit 18c and the second connection circuit 22b. Circuit breaker 26d can disconnect the second power generator 14b from the fourth power supply circuit 18d and the second connection circuit 22b.

[0030] The circuit breakers 26a to 26d have contactors. The circuit breakers 26a to 26d may have relays. The circuit breakers 26a to 26d may have circuit breakers. The circuit breakers 26a to 26d may have semiconductor switches.

[0031] The first energy storage device 16a is connected in parallel with the first power generator 14a to the first power supply circuit 18a. The second energy storage device 16b is connected in parallel with the second power generator 14b to the second power supply circuit 18b. The third energy storage device 16c is connected in parallel with the first power generator 14a to the third power supply circuit 18c. The fourth energy storage device 16d is connected in parallel with the second power generator 14b to the fourth power supply circuit 18d.

[0032] The first energy storage device 16a, the second energy storage device 16b, the third energy storage device 16c, and the fourth energy storage device 16d each have a lithium-ion battery. The first energy storage device 16a, the second energy storage device 16b, the third energy storage device 16c, and the fourth energy storage device 16d may also have a secondary battery other than a lithium-ion battery. The first energy storage device 16a, the second energy storage device 16b, the third energy storage device 16c, and the fourth energy storage device 16d may also have a large-capacity capacitor.

[0033] The first energy storage device 16a, the second energy storage device 16b, the third energy storage device 16c, and the fourth energy storage device 16d may have various sensors such as voltage sensors and current sensors, as well as various elements such as fuses, relays, circuit breakers, diodes, transistors, resistors, coils, and capacitors.

[0034] The power supply system 10 includes circuit breakers 28a to 28d. Circuit breaker 28a can disconnect the first energy storage device 16a from the first power supply circuit 18a, the first inverter 15a, and the third inverter 15c. Circuit breaker 28b can disconnect the second energy storage device 16b from the second power supply circuit 18b, the second inverter 15b, and the fourth inverter 15d. Circuit breaker 28c can disconnect the third energy storage device 16c from the third power supply circuit 18c, the fifth inverter 15e, and the seventh inverter 15g. Circuit breaker 28d can disconnect the fourth energy storage device 16d from the fourth power supply circuit 18d, the sixth inverter 15f, and the eighth inverter 15h.

[0035] The circuit breakers 28a to 28d have contactors. The circuit breakers 28a to 28d may have relays. The circuit breakers 28a to 28d may have circuit breakers. The circuit breakers 28a to 28d may have semiconductor switches.

[0036] As shown in Figure 1, when the circuit breakers 26a, 26c and 28a, 28c are connected, the first power generator 14a, the first energy storage device 16a, the first inverter 15a, the third inverter 15c, the third energy storage device 16c, the fifth inverter 15e, and the seventh inverter 15g are connected to each other. Therefore, assuming that the voltage drop in the first power supply circuit 18a and the third power supply circuit 18c is sufficiently small, the output voltage of the first power generator 14a, the output voltage of the first energy storage device 16a, the applied voltage of the first inverter 15a, the applied voltage of the third inverter 15c, the output voltage of the third energy storage device 16c, the applied voltage of the fifth inverter 15e, and the applied voltage of the seventh inverter 15g are approximately equal. In the following, the output voltage of the first power generator 14a, the output voltage of the first energy storage device 16a, the applied voltage of the first inverter 15a, the applied voltage of the third inverter 15c, the output voltage of the third energy storage device 16c, the applied voltage of the fifth inverter 15e, and the applied voltage of the seventh inverter 15g may be collectively referred to as the voltage of the first power supply system 12a.

[0037] Similarly, when circuit breakers 26b, 26d and 28b, 28d are connected, the second power generator 14b, the second energy storage device 16b, the second inverter 15b, the fourth inverter 15d, the fourth energy storage device 16d, the sixth inverter 15f, and the eighth inverter 15h are connected to each other. Therefore, the output voltage of the second power generator 14b, the output voltage of the second energy storage device 16b, the applied voltage of the second inverter 15b, the applied voltage of the fourth inverter 15d, the output voltage of the fourth energy storage device 16d, the applied voltage of the sixth inverter 15f, and the applied voltage of the eighth inverter 15h are approximately equal. In the following, the output voltage of the second power generator 14b, the output voltage of the second energy storage device 16b, the applied voltage of the second inverter 15b, the applied voltage of the fourth inverter 15d, the output voltage of the fourth energy storage device 16d, the applied voltage of the sixth inverter 15f, and the applied voltage of the eighth inverter 15h may be collectively referred to as the voltage of the second power supply system 12b.

[0038] [Operation of the power supply system under normal conditions] Figure 2 shows the operation of the power supply system 10 under normal conditions in one embodiment. The arrows shown in Figure 2 indicate the power supply path.

[0039] The first connection device 24a disconnects the connection between the first power supply circuit 18a and the second power supply circuit 18b. The second connection device 24b disconnects the connection between the third power supply circuit 18c and the fourth power supply circuit 18d.

[0040] The circuit breaker 26a connects the first power generator 14a to the first power supply circuit 18a and the first connection circuit 22a. As a result, DC power is supplied from the first power generator 14a to the first inverter 15a and the third inverter 15c. The circuit breaker 26c connects the first power generator 14a to the third power supply circuit 18c and the second connection circuit 22b. As a result, power is supplied from the first power generator 14a to the fifth inverter 15e and the seventh inverter 15g.

[0041] The circuit breaker 28a connects the first energy storage device 16a to the first inverter 15a and the third inverter 15c. As a result, DC power is supplied from the first energy storage device 16a to the first inverter 15a and the third inverter 15c. The circuit breaker 28c connects the third energy storage device 16c to the fifth inverter 15e and the seventh inverter 15g. As a result, DC power is supplied from the third energy storage device 16c to the fifth inverter 15e and the seventh inverter 15g.

[0042] The circuit breaker 26b connects the second power generator 14b to the second power supply circuit 18b and the first connection circuit 22a. As a result, DC power is supplied from the second power generator 14b to the second inverter 15b and the fourth inverter 15d. The circuit breaker 26d connects the second power generator 14b to the fourth power supply circuit 18d and the second connection circuit 22b. As a result, DC power is supplied from the second power generator 14b to the sixth inverter 15f and the eighth inverter 15h.

[0043] The circuit breaker 28b connects the second energy storage device 16b to the second inverter 15b and the fourth inverter 15d. This supplies DC power from the second energy storage device 16b to the second inverter 15b and the fourth inverter 15d. The circuit breaker 28d connects the fourth energy storage device 16d to the sixth inverter 15f and the eighth inverter 15h. This supplies DC power from the fourth energy storage device 16d to the sixth inverter 15f and the eighth inverter 15h.

[0044] [Operation of the power supply system during abnormal conditions] Figures 3 to 5 show the operation of the power supply system 10 in the event of an abnormality in one embodiment. The arrows shown in Figures 3 to 5 indicate the power supply path. Figures 3 to 5 show the operation of the power supply system 10 when the supply of DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c is interrupted.

[0045] A state in which the supply of DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c is interrupted means, for example, that the first power generator 14a has stopped and cannot be restarted. Another state in which the supply of DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c is interrupted means, for example, that a break in the wire occurs between the first power generator 14a and the circuit breaker 26a, or between the first power generator 14a and the circuit breaker 26c. Yet another state in which the supply of DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c is interrupted means, for example, that a short circuit occurs between the first power generator 14a and the circuit breaker 26a, or between the first power generator 14a and the circuit breaker 26c.

[0046] If the supply of DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c is interrupted, the first power generator 14a is disconnected from the first power supply circuit 18a and the first connection circuit 22a by the circuit breaker 26a, as shown in Figure 3. In addition, the first power generator 14a is disconnected from the third power supply circuit 18c and the second connection circuit 22b by the circuit breaker 26c.

[0047] If there is a difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b, the power supply system 10 of one embodiment performs a first power suppression control on the first inverter 15a, as shown in Figure 4. The power supply system 10 also performs a third power suppression control on the third inverter 15c. Furthermore, the power supply system 10 performs a fifth power suppression control on the fifth inverter 15e. And furthermore, the power supply system 10 performs a seventh power suppression control on the seventh inverter 15g.

[0048] If there is a difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b, the power supply system 10 of one embodiment performs a second power increase control on the second inverter 15b, as shown in Figure 4. The power supply system 10 also performs a fourth power increase control on the fourth inverter 15d. Furthermore, the power supply system 10 performs a sixth power increase control on the sixth inverter 15f. And furthermore, the power supply system 10 performs an eighth power increase control on the eighth inverter 15h.

[0049] The power suppression and power increase controls described above are performed to approximate the voltage of the first power supply system 12a with the voltage of the second power supply system 12b. The approximation of the voltage of the first power supply system 12a with the voltage of the second power supply system 12b will be described in detail later.

[0050] After approximating the voltage of the first power supply system 12a and the voltage of the second power supply system 12b, the power supply system 10 of one embodiment performs connection control on the first connection device 24a, as shown in Figure 5. As a result, the first power supply circuit 18a and the second power supply circuit 18b are connected by the first connection device 24a. Therefore, DC power is supplied from the second power generator 14b to the first power supply circuit 18a. The power supply system 10 also performs connection control on the second connection device 24b. As a result, the third power supply circuit 18c and the fourth power supply circuit 18d are connected by the second connection device 24b. Therefore, DC power is supplied from the second power generator 14b to the third power supply circuit 18c.

[0051] [Control device configuration] The power supply system 10 includes a control device 30. Figure 6 is a control block diagram of the control device 30 in one embodiment.

[0052] The control device 30 includes an arithmetic unit 32 and a storage unit 34. The arithmetic unit 32 is, for example, a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). The arithmetic unit 32 controls each device by executing a program stored in the storage unit 34. At least a portion of the arithmetic unit 32 may be implemented by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). At least a portion of the arithmetic unit 32 may be implemented by an electronic circuit including discrete devices.

[0053] The storage unit 34 is composed of computer-readable storage media, namely volatile memory (not shown) and non-volatile memory (not shown). The volatile memory is, for example, RAM (Random Access Memory). The non-volatile memory is, for example, ROM (Read Only Memory) or flash memory. Data is stored in the volatile memory, for example. Programs, tables, maps, etc., are stored in the non-volatile memory, for example. At least a part of the storage unit 34 may be provided in the processor, integrated circuit, etc. mentioned above.

[0054] The control device 30 controls the first inverter 15a, the second inverter 15b, the third inverter 15c, the fourth inverter 15d, the fifth inverter 15e, the sixth inverter 15f, the seventh inverter 15g, and the eighth inverter 15h, respectively. The control device 30 also controls the first connection device 24a, the second connection device 24b, the circuit breakers 26a to 26d, and the circuit breakers 28a to 28d, respectively. There may be multiple control devices 30. For example, one control device 30 may control the first inverter 15a, the second inverter 15b, the third inverter 15c, the fourth inverter 15d, the fifth inverter 15e, the sixth inverter 15f, the seventh inverter 15g, and the eighth inverter 15h, respectively. Alternatively, another control device 30 may control the first connection device 24a, the second connection device 24b, the circuit breakers 26a to 26d, and the circuit breakers 28a to 28d, respectively.

[0055] [Fail-safe control] Figure 7 is a flowchart illustrating fail-safe control in one embodiment. Fail-safe control is repeatedly executed at predetermined intervals.

[0056] In step S1, the control device 30 determines whether the supply of DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c has been cut off. If it is determined that the supply of DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c has been cut off (step S1: YES), the process proceeds to step S2.

[0057] In step S2, the control device 30 controls the circuit breaker 26a to disconnect the first power generator 14a from the first power supply circuit 18a and the first connection circuit 22a. Then, the process proceeds to step S3.

[0058] In step S3, the control device 30 controls the circuit breaker 26c to disconnect the first power generator 14a from the third power supply circuit 18c and the second connection circuit 22b. Then, the process proceeds to step S4.

[0059] In step S4, the control device 30 determines whether the difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b is less than or equal to the first voltage threshold. If it is determined that the difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b is greater than the first voltage threshold (step S4: NO), the process proceeds to step S5. The first voltage threshold is predetermined according to the magnitude of the current that each device and equipment of the power supply system 10 can withstand.

[0060] In step S5, the control device 30 performs a first power suppression control on the first inverter 15a. The control device 30 also performs a third power suppression control on the third inverter 15c. Furthermore, the control device 30 performs a fifth power suppression control on the fifth inverter 15e. And furthermore, the control device 30 performs a seventh power suppression control on the seventh inverter 15g. After that, the process proceeds to step S6.

[0061] The first power suppression control is a control that reduces the ratio of the power supplied from the first inverter 15a to the first motor 17a (hereinafter referred to as the first power) to the power consumed by the first motor 17a (hereinafter referred to as the first ratio) to the ratio before the supply of DC power from the first power generator 14a to the first power supply circuit 18a was cut off.

[0062] The third power suppression control is a control that reduces the ratio of the power supplied from the third inverter 15c to the second motor 17b (hereinafter referred to as the third power) to the power consumed by the second motor 17b (hereinafter referred to as the third ratio) to the ratio before the supply of DC power from the first power generator 14a to the first power supply circuit 18a was cut off.

[0063] The fifth power suppression control is a control that reduces the ratio of the power supplied from the fifth inverter 15e to the third motor 17c (hereinafter referred to as the fifth power) to the power consumption of the third motor 17c (hereinafter referred to as the fifth ratio) to the ratio before the supply of DC power from the first power generator 14a to the third power supply circuit 18c was cut off.

[0064] The seventh power suppression control is a control that reduces the ratio of the power supplied from the seventh inverter 15g to the fourth motor 17d (hereinafter referred to as the seventh power) to the power consumed by the fourth motor 17d (hereinafter referred to as the seventh ratio) to the ratio before the supply of DC power from the first power generator 14a to the third power supply circuit 18c was cut off.

[0065] In step S6, the control device 30 performs a second power increase control on the second inverter 15b. The control device 30 also performs a fourth power increase control on the fourth inverter 15d. Furthermore, the control device 30 performs a sixth power increase control on the sixth inverter 15f. Finally, the control device 30 performs an eighth power increase control on the eighth inverter 15h. The process then proceeds to step S7.

[0066] The second power increase control is a control that increases the ratio of the power supplied from the second inverter 15b to the first motor 17a (hereinafter referred to as the second power) to the power consumed by the first motor 17a (hereinafter referred to as the second ratio) to the ratio before the supply of DC power from the first power generator 14a to the first power supply circuit 18a is cut off.

[0067] The magnitude of the first ratio reduced by the first power suppression control described above is equal to the magnitude of the second ratio increased by the second power increase control. As a result, the increase or decrease in the output torque of the first motor 17a can be suppressed by the execution of the first power suppression control and the second power increase control. The difference between the magnitude of the first ratio reduced by the first power suppression control and the magnitude of the second ratio increased by the second power increase control may be less than or equal to a predetermined value.

[0068] The fourth power increase control is a control that increases the ratio of the power supplied from the fourth inverter 15d to the second motor 17b (hereinafter referred to as the fourth power) to the power consumed by the second motor 17b (hereinafter referred to as the fourth ratio) to the ratio before the supply of DC power from the first power generator 14a to the first power supply circuit 18a is cut off.

[0069] The magnitude of the third ratio, which is reduced by the aforementioned third power suppression control, is equal to the magnitude of the fourth ratio, which is increased by the fourth power increase control. As a result, the increase or decrease in the output torque of the second motor 17b can be suppressed by the execution of the third power suppression control and the fourth power increase control. The difference between the magnitude of the third ratio, which is reduced by the third power suppression control, and the magnitude of the fourth ratio, which is increased by the fourth power increase control, may be less than or equal to a predetermined value.

[0070] The sixth power increase control is a control that increases the ratio of the power supplied from the sixth inverter 15f to the third motor 17c (hereinafter referred to as the sixth power) to the power consumption of the third motor 17c (hereinafter referred to as the sixth ratio) to the ratio before the supply of DC power from the first power generator 14a to the third power supply circuit 18c is cut off.

[0071] The magnitude of the fifth ratio, which is reduced by the fifth power suppression control described above, is equal to the magnitude of the sixth ratio, which is increased by the sixth power increase control. As a result, the increase or decrease in the output torque of the third motor 17c can be suppressed by the execution of the fifth power suppression control and the sixth power increase control. The difference between the magnitude of the fifth ratio, which is reduced by the fifth power suppression control, and the magnitude of the sixth ratio, which is increased by the sixth power increase control, may be less than or equal to a predetermined value.

[0072] The eighth power increase control is a control that increases the ratio of the power supplied from the eighth inverter 15h to the fourth motor 17d (hereinafter referred to as the eighth power) to the power consumed by the fourth motor 17d (hereinafter referred to as the eighth ratio) to the ratio before the supply of DC power from the first power generator 14a to the third power supply circuit 18c is cut off.

[0073] The magnitude of the seventh ratio, which is reduced by the aforementioned seventh power suppression control, is equal to the magnitude of the eighth ratio, which is increased by the eighth power increase control. As a result, the increase or decrease in the output torque of the fourth motor 17d can be suppressed by the execution of the seventh power suppression control and the eighth power increase control. The difference between the magnitude of the seventh ratio, which is reduced by the seventh power suppression control, and the magnitude of the eighth ratio, which is increased by the eighth power increase control, may be less than or equal to a predetermined value.

[0074] In step S7, the control device 30 determines whether the difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b is less than or equal to the second voltage threshold. If it is determined that the difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b is greater than the second voltage threshold (step S7: NO), the process returns to step S5. The second voltage threshold is predetermined according to the magnitude of the current that each device and equipment of the power supply system 10 can withstand. The second voltage threshold may be the same value as the first voltage threshold mentioned above, or it may be a different value from the first voltage threshold.

[0075] If, in step S4 described above, it is determined that the difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b is less than or equal to the first voltage threshold (step S4: YES), or if, in the preceding step S7, it is determined that the difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b is less than or equal to the second voltage threshold (step S7: YES), the process proceeds to step S8.

[0076] In step S8, the control device 30 performs connection control on the first connection device 24a. As a result, the first power supply circuit 18a and the second power supply circuit 18b are connected via the first connection circuit 22a. The process then proceeds to step S9.

[0077] In step S9, the control device 30 performs connection control on the second connection device 24b. This connects the third power supply circuit 18c and the fourth power supply circuit 18d via the second connection circuit 22b. After that, the fail-safe control is terminated.

[0078] If, in step S1 described above, it is determined that DC power is being supplied from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c (step S1: NO), the process proceeds to step S10.

[0079] In step S10, the control device 30 determines whether the power supply from the second power generator 14b to the second power supply circuit 18b and the fourth power supply circuit 18d has been cut off. If it is determined that the power supply from the second power generator 14b to the second power supply circuit 18b and the fourth power supply circuit 18d has been cut off (step S10: YES), the process proceeds to step S11. If it is determined that power is being supplied from the second power generator 14b to the second power supply circuit 18b and the fourth power supply circuit 18d (step S10: NO), the fail-safe control is terminated.

[0080] In step S11, the control device 30 controls the circuit breaker 26b to disconnect the second power generator 14b from the second power supply circuit 18b and the first connection circuit 22a. Then, the process proceeds to step S12.

[0081] In step S12, the control device 30 controls the circuit breaker 26d to disconnect the second power generator 14b from the fourth power supply circuit 18d and the second connection circuit 22b. Then, the process proceeds to step S13.

[0082] In step S13, the control device 30 determines whether the difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b is less than or equal to the first voltage threshold. If it is determined that the difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b is greater than the first voltage threshold (step S13: NO), the process proceeds to step S14.

[0083] In step S14, the control device 30 performs a second power suppression control on the second inverter 15b. The control device 30 also performs a fourth power suppression control on the fourth inverter 15d. Furthermore, the control device 30 performs a sixth power suppression control on the sixth inverter 15f. Finally, the control device 30 performs an eighth power suppression control on the eighth inverter 15h. After this, the process proceeds to step S15.

[0084] The second power suppression control is a control that reduces the second ratio of the second power supplied from the second inverter 15b to the first motor 17a to the power consumption of the first motor 17a to less than the ratio before the supply of DC power from the second power generator 14b to the second power supply circuit 18b was cut off.

[0085] The fourth power suppression control is a control that reduces the fourth ratio of the fourth power supplied from the fourth inverter 15d to the second motor 17b to the power consumption of the second motor 17b to less than the ratio before the supply of DC power from the second generator 14b to the second power supply circuit 18b was cut off.

[0086] The sixth power suppression control is a control that reduces the sixth ratio of the sixth power supplied from the sixth inverter 15f to the third motor 17c to the power consumption of the third motor 17c to a smaller ratio than before the supply of DC power from the second power generator 14b to the fourth power supply circuit 18d was cut off.

[0087] The eighth power suppression control is a control that reduces the ratio of the eighth power supplied from the eighth inverter 15h to the fourth motor 17d to the power consumption of the fourth motor 17d to a smaller ratio than before the supply of DC power from the second power generator 14b to the fourth power supply circuit 18d was cut off.

[0088] In step S15, the control device 30 performs a first power increase control on the first inverter 15a. The control device 30 also performs a third power increase control on the third inverter 15c. Furthermore, the control device 30 performs a fifth power increase control on the fifth inverter 15e. Finally, the control device 30 performs a seventh power increase control on the seventh inverter 15g. The process then proceeds to step S16.

[0089] The first power increase control is a control that increases the first ratio of the first power supplied from the first inverter 15a to the first motor 17a to the power consumption of the first motor 17a to the ratio before the supply of DC power from the second power generator 14b to the second power supply circuit 18b is cut off.

[0090] The magnitude of the second ratio, which is reduced by the second power suppression control described above, is equal to the magnitude of the first ratio, which is increased by the first power increase control. As a result, the increase or decrease in the output torque of the first motor 17a can be suppressed by the execution of the second power suppression control and the first power increase control. The difference between the magnitude of the second ratio, which is reduced by the second power suppression control, and the magnitude of the first ratio, which is increased by the first power increase control, may be less than or equal to a predetermined value.

[0091] The third power increase control is a control that increases the third ratio of the third power supplied from the third inverter 15c to the second motor 17b to the power consumption of the second motor 17b to the ratio before the supply of DC power from the second power generator 14b to the second power supply circuit 18b is cut off.

[0092] The magnitude of the fourth ratio, which is reduced by the fourth power suppression control described above, is equal to the magnitude of the third ratio, which is increased by the third power increase control. As a result, the increase or decrease in the output torque of the second motor 17b can be suppressed by the execution of the fourth power suppression control and the third power increase control. The difference between the magnitude of the fourth ratio, which is reduced by the fourth power suppression control, and the magnitude of the third ratio, which is increased by the third power increase control, may be less than or equal to a predetermined value.

[0093] The fifth power increase control is a control that increases the fifth ratio of the fifth power supplied from the fifth inverter 15e to the third motor 17c to the power consumption of the third motor 17c to the ratio before the DC power supply from the second power generator 14b to the fourth power supply circuit 18d is cut off.

[0094] The magnitude of the sixth ratio, which is reduced by the aforementioned sixth power suppression control, is equal to the magnitude of the fifth ratio, which is increased by the fifth power increase control. As a result, the output torque of the third motor 17c can be suppressed from increasing or decreasing when the sixth power suppression control and the fifth power increase control are executed. The difference between the magnitude of the sixth ratio, which is reduced by the sixth power suppression control, and the magnitude of the fifth ratio, which is increased by the fifth power increase control, may be less than or equal to a predetermined value.

[0095] The seventh power increase control is a control that increases the ratio of the seventh power supplied from the seventh inverter 15g to the fourth motor 17d to the power consumption of the fourth motor 17d to the ratio

[0096] The magnitude of the eighth ratio, which is reduced by the eighth power suppression control described above, is equal to the magnitude of the seventh ratio, which is increased by the seventh power increase control. As a result, the increase or decrease in the output torque of the fourth motor 17d can be suppressed by the execution of the eighth power suppression control and the seventh power increase control. The difference between the magnitude of the eighth ratio, which is reduced by the eighth power suppression control, and the magnitude of the seventh ratio, which is increased by the seventh power increase control, may be less than or equal to a predetermined value.

[0097] In step S16, the control device 30 determines whether the difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b is less than or equal to the second voltage threshold. If it is determined that the difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b is greater than the second voltage threshold (step S16: NO), the process returns to step S14.

[0098] If, in step S13 described above, it is determined that the difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b is less than or equal to the first voltage threshold (step S13: YES), or if, in the preceding step S16, it is determined that the difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b is less than or equal to the second voltage threshold (step S16: YES), the process proceeds to step S17.

[0099] In step S17, the control device 30 performs connection control on the first connection device 24a. As a result, the first power supply circuit 18a and the second power supply circuit 18b are connected via the first connection circuit 22a. The process then proceeds to step S18.

[0100] In step S18, the control device 30 performs connection control on the second connection device 24b. As a result, the third power supply circuit 18c and the fourth power supply circuit 18d are connected via the second connection circuit 22b. After that, the fail-safe control is terminated.

[0101] [Regarding the approximation between the voltage of the first power supply system and the voltage of the second power supply system] In one embodiment of the power supply system 10, if there is a difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b, the voltages of the first power supply system 12a and the second power supply system 12b are approximated before connecting them.

[0102] The state of the power supply system 10 when the first power supply system 12a and the second power supply system 12b are connected while there is a voltage difference between the first power supply system 12a and the second power supply system 12b will be described below.

[0103] Figures 8A to 8C are graphs showing the time changes in the state of the power supply system 10 before and after the time when the first power supply system 12a and the second power supply system 12b are connected. The graph in Figure 8A shows the time changes in the voltage of the first power supply system 12a and the voltage of the second power supply system 12b. The graph in Figure 8B shows the time changes in the output torque of the first motor 17a, the second motor 17b, the third motor 17c, and the fourth motor 17d. The graph in Figure 8C shows the time changes in the current flowing through the first connection circuit 22a and the second connection circuit 22b. Each graph in Figures 8A to 8C schematically shows the time changes in voltage, power, and current.

[0104] At time t1, the supply of DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c is cut off. At time t2, the first power supply circuit 18a and the second power supply circuit 18b are connected, and the third power supply circuit 18c and the fourth power supply circuit 18d are connected. During the periods shown in the graphs of Figures 8A to 8C, the power consumption of the first motor 17a, the second motor 17b, the third motor 17c, and the fourth motor 17d remain constant.

[0105] Prior to time t1, the output power of the first generator 14a is equal to half the sum of the power consumption of the first motor 17a, the second motor 17b, the third motor 17c, and the fourth motor 17d. Also prior to time t1, the output power of the second generator 14b is equal to half the sum of the power consumption of the first motor 17a, the second motor 17b, the third motor 17c, and the fourth motor 17d. Therefore, the first energy storage devices 16a, 2nd energy storage devices 16b, 3rd energy storage devices 16c, and 4th energy storage devices 16d are not being charged or discharged.

[0106] At time t1, the supply of DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c is cut off, causing the first energy storage device 16a and the third energy storage device 16c to begin discharging at time t1. As the first energy storage device 16a begins to discharge, its output power increases, and its output current increases. Consequently, the voltage drop due to internal resistance in the first energy storage device 16a increases, causing its output voltage to decrease. Also, as the third energy storage device 16c begins to discharge, its output power increases, and its output current increases. Consequently, the voltage drop due to internal resistance in the third energy storage device 16c increases, causing its output voltage to decrease. In other words, the voltage of the first power supply system 12a decreases (the part indicated by the symbol P in Figure 8A).

[0107] Furthermore, during the period from time t1 to time t2, power is supplied to the first inverter 15a and the third inverter 15c from the first energy storage device 16a, and power is supplied to the fifth inverter 15e and the seventh inverter 15g from the third energy storage device 16c. In other words, during the period from time t1 to time t2, the first energy storage device 16a and the third energy storage device 16c discharge, causing the SOC (State of Charge) of the first energy storage device 16a and the SOC of the third energy storage device 16c to gradually decrease. As the SOC decreases, the open-circuit voltage of the first energy storage device 16a and the open-circuit voltage of the third energy storage device 16c decrease, and the output voltage of the first energy storage device 16a and the output voltage of the third energy storage device 16c to gradually decrease. In other words, the voltage of the first power supply system 12a gradually decreases (the part indicated by the symbol Q in Figure 8A).

[0108] On the other hand, during the period from time t1 to time t2, the second inverter 15b, the fourth inverter 15d, the sixth inverter 15f, and the eighth inverter 15h are supplied with power from the second power generator 14b. In other words, during the period from time t1 to time t2, the second energy storage devices 16b and the fourth energy storage devices 16d do not charge or discharge. Therefore, the output current of the second energy storage device 16b and the output current of the fourth energy storage device 16d remain unchanged, and the voltage drop due to internal resistance in the second energy storage device 16b and the fourth energy storage device 16d remains unchanged. Furthermore, the state of charge (SOC) of the second energy storage device 16b and the state of charge (SOC) of the fourth energy storage device 16d are maintained. Therefore, the output voltage of the second energy storage device 16b and the output voltage of the fourth energy storage device 16d are maintained. In other words, the voltage of the second power supply system 12b is maintained.

[0109] As the voltage of the first power supply system 12a decreases while the voltage of the second power supply system 12b is maintained, the voltage difference between the first power supply system 12a and the second power supply system 12b increases. Therefore, at time t2, when the first power supply circuit 18a and the second power supply circuit 18b are connected, and the third power supply circuit 18c and the fourth power supply circuit 18d are connected, an overcurrent flows through the power supply system 10. This overcurrent may damage each device and component of the power supply system 10. Furthermore, if each device and component of the power supply system 10 is made capable of withstanding overcurrents, the manufacturing cost of the power supply system 10 will increase.

[0110] The state of the power supply system 10 when the voltage of the first power supply system 12a and the voltage of the second power supply system 12b are approximated and then connected is described below.

[0111] Figures 9A to 9C are graphs showing the time changes in the state of the power supply system 10 before and after the time when the first power supply system 12a and the second power supply system 12b are connected. The graph in Figure 9A shows the time changes in the voltage of the first power supply system 12a and the voltage of the second power supply system 12b. The graph in Figure 9B shows the time changes in the output torque of the first motor 17a, the second motor 17b, the third motor 17c, and the fourth motor 17d. The graph in Figure 9C shows the time changes in the current flowing through the first connection circuit 22a and the second connection circuit 22b. Each graph in Figures 9A to 9C schematically shows the time changes in voltage, power, and current.

[0112] At time t11, the supply of DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c is cut off. At time t12, the first power suppression control is performed on the first inverter 15a, the third power suppression control is performed on the third inverter 15c, the fifth power suppression control is performed on the fifth inverter 15e, and the seventh power suppression control is performed on the seventh inverter 15g. Also at time t12, the second power increase control is performed on the second inverter 15b, the fourth power increase control is performed on the fourth inverter 15d, the sixth power increase control is performed on the sixth inverter 15f, and the eighth power increase control is performed on the eighth inverter 15h.

[0113] Prior to time t11, the output power of the first generator 14a is equal to half the sum of the power consumption of the first motor 17a, the second motor 17b, the third motor 17c, and the fourth motor 17d. Also, prior to time t1, the output power of the second generator 14b is equal to half the sum of the power consumption of the first motor 17a, the second motor 17b, the third motor 17c, and the fourth motor 17d. Therefore, the first energy storage devices 16a, 2nd energy storage devices 16b, 3rd energy storage devices 16c, and 4th energy storage devices 16d are not being charged or discharged.

[0114] Similar to the period from time t1 to t2 in Figure 8A, during the period from time t11 to t12 in Figure 9A, the voltage of the first power supply system 12a decreases while the voltage of the second power supply system 12b is maintained. Therefore, the difference between the voltage of the first power supply system 12a and the voltage of the second power supply system 12b becomes large.

[0115] In one embodiment of the power supply system 10, at time t12, a first power suppression control is performed on the first inverter 15a, a third power suppression control is performed on the third inverter 15c, a fifth power suppression control is performed on the fifth inverter 15e, and a seventh power suppression control is performed on the seventh inverter 15g.

[0116] The first and third power suppression controls gradually reduce the output power of the first energy storage device 16a, and the output current of the first energy storage device 16a gradually decreases. As a result, the voltage drop due to internal resistance in the first energy storage device 16a gradually decreases. Furthermore, the fifth and seventh power suppression controls gradually reduce the output power of the third energy storage device 16c, and the output current of the third energy storage device 16c gradually decreases. As a result, the voltage drop due to internal resistance in the third energy storage device 16c gradually decreases.

[0117] Furthermore, compared to the period from time t11 to time t12, the power supplied from the first inverter 15a to the first motor 17a decreases, and the power supplied from the third inverter 15c to the second motor 17b decreases during the period from time t12 to time t13. Therefore, the decrease in the SOC of the first energy storage device 16a is suppressed. Similarly, compared to the period from time t11 to time t12, the power supplied from the fifth inverter 15e to the third motor 17c decreases, and the power supplied from the seventh inverter 15g to the fourth motor 17d decreases during the period from time t12 to time t13. Therefore, the decrease in the SOC of the third energy storage device 16c is suppressed.

[0118] As described above, the voltage drop due to the internal resistance in the first energy storage device 16a and the third energy storage device 16c is reduced, and furthermore, the decrease in the SOC of the first energy storage device 16a and the third energy storage device 16c is suppressed, thereby suppressing the decrease in the output voltage of the first energy storage device 16a and the third energy storage device 16c. In other words, the decrease in the voltage of the first power supply system 12a is suppressed.

[0119] Furthermore, in the power supply system 10 of one embodiment, at time t12, the second power increase control is performed on the second inverter 15b, the fourth power increase control is performed on the fourth inverter 15d, the sixth power increase control is performed on the sixth inverter 15f, and the eighth power increase control is performed on the eighth inverter 15h.

[0120] The second, fourth, sixth, and eighth power increase control mechanisms increase the power requirements of the second inverter 15b, fourth inverter 15d, sixth inverter 15f, and eighth inverter 15h. As a result, the second generator 14b is controlled to increase its output power. However, because the response speed of the output power of the second generator 14b is relatively slow, for a while the output power of the second generator 14b will be insufficient to meet the combined power requirements of the second inverter 15b, fourth inverter 15d, sixth inverter 15f, and eighth inverter 15h.

[0121] The insufficient power is supplied from the second energy storage device 16b to the second inverter 15b and the fourth inverter 15d, and from the fourth energy storage device 16d to the sixth inverter 15f and the eighth inverter 15h. As the power requirements of the second inverter 15b and the fourth inverter 15d gradually increase, the output power of the second energy storage device 16b gradually increases, and the output current of the second energy storage device 16b gradually increases. As a result, the voltage drop due to internal resistance in the second energy storage device 16b gradually increases. Also, as the power requirements of the sixth inverter 15f and the eighth inverter 15h gradually increase, the output power of the fourth energy storage device 16d gradually increases, and the output current of the fourth energy storage device 16d gradually increases. As a result, the voltage drop due to internal resistance in the fourth energy storage device 16d gradually increases.

[0122] Furthermore, during the period from time t12 to time t13, the second energy storage device 16b and the fourth energy storage device 16d discharge, which promotes a decrease in the SOC of the second energy storage device 16b and the SOC of the fourth energy storage device 16d.

[0123] As described above, the voltage drop due to internal resistance gradually increases in the second energy storage device 16b and the fourth energy storage device 16d. Furthermore, this promotes a decrease in the SOC of the second energy storage device 16b and the SOC of the fourth energy storage device 16d, thereby accelerating the decrease in the output voltage of the second energy storage device 16b and the output voltage of the fourth energy storage device 16d. In other words, the voltage of the second power supply system 12b is accelerated.

[0124] By promoting the voltage drop in the second power supply system 12b and suppressing the voltage drop in the first power supply system 12a, the voltage of the second power supply system 12b can be brought closer to the voltage of the first power supply system 12a. At the point t13 when the voltages of the first power supply system 12a and the second power supply system 12b are similar, the first power supply circuit 18a and the second power supply circuit 18b are connected, and the third power supply circuit 18c and the fourth power supply circuit 18d are connected. This prevents overcurrent from flowing through the power supply system 10. Therefore, damage to each device and equipment in the power supply system 10 is suppressed. In addition, it is not necessary to make each device and equipment in the power supply system 10 capable of withstanding overcurrent, which reduces the manufacturing cost of the power supply system 10.

[0125] When the first power suppression control is applied to the first inverter 15a, the first ratio of the first power supplied from the first inverter 15a to the first motor 17a to the power consumption of the first motor 17a decreases. However, when the second power increase control is applied to the second inverter 15b, the second ratio of the second power supplied from the second inverter 15b to the first motor 17a to the power consumption of the first motor 17a increases. As a result, the output torque of the first motor 17a is maintained.

[0126] Similarly, when a third power suppression control is applied to the third inverter 15c, the third ratio of the third power supplied from the third inverter 15c to the second motor 17b relative to the second motor 17b's power consumption decreases. However, when a fourth power increase control is applied to the fourth inverter 15d, the fourth ratio of the fourth power supplied from the fourth inverter 15d to the second motor 17b relative to the second motor 17b's power consumption increases. This maintains the output torque of the second motor 17b.

[0127] Furthermore, when the fifth power suppression control is applied to the fifth inverter 15e, the fifth ratio of the fifth power supplied from the fifth inverter 15e to the third motor 17c relative to the third motor 17c's power consumption decreases. However, when the sixth power increase control is applied to the sixth inverter 15f, the sixth ratio of the sixth power supplied from the sixth inverter 15f to the third motor 17c relative to the third motor 17c's power consumption increases. As a result, the output torque of the third motor 17c is maintained.

[0128] Furthermore, when the seventh power suppression control is applied to the seventh inverter 15g, the ratio of the seventh power supplied from the seventh inverter 15g to the fourth motor 17d to the fourth motor 17d's power consumption decreases. However, when the eighth power increase control is applied to the eighth inverter 15h, the ratio of the eighth power supplied from the eighth inverter 15h to the fourth motor 17d to the fourth motor 17d's power consumption increases. As a result, the output torque of the fourth motor 17d is maintained.

[0129] The above describes the case where the DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c is interrupted. However, even if the DC power from the second power generator 14b to the second power supply circuit 18b and the fourth power supply circuit 18d is interrupted, the voltage of the first power supply system 12a and the voltage of the second power supply system 12b are approximated before connecting the first power supply system 12a and the second power supply system 12b.

[0130] If the supply of DC power from the second power generator 14b to the second power supply circuit 18b and the fourth power supply circuit 18d is interrupted, the second power suppression control is performed on the second inverter 15b, the fourth power suppression control is performed on the fourth inverter 15d, the sixth power suppression control is performed on the sixth inverter 15f, and the eighth power suppression control is performed on the eighth inverter 15h. Furthermore, the first power increase control is performed on the first inverter 15a, the third power increase control is performed on the third inverter 15c, the fifth power increase control is performed on the fifth inverter 15e, and the seventh power increase control is performed on the seventh inverter 15g. This approximates the voltage of the first power supply system 12a and the voltage of the second power supply system 12b.

[0131] [Comparison with the power supply system of the comparative example] Figure 10 is a schematic diagram of the power supply system 100 in the comparative example. The power supply system 100 in the comparative example includes voltage converters 30a to 30d. Voltage converters 30a to 30d are DC-DC converters.

[0132] In the power supply system 100, the output voltages of the voltage converters 30a to 30d are made approximately equal. Therefore, when the first power supply circuit 18a and the second power supply circuit 18b are connected by the first connection device 24a, it is possible to prevent overcurrent from flowing through the first power supply circuit 18a and the second power supply circuit 18b. Similarly, when the third power supply circuit 18c and the fourth power supply circuit 18d are connected by the second connection device 24b, it is possible to prevent overcurrent from flowing through the third power supply circuit 18c and the fourth power supply circuit 18d.

[0133] However, since the power supply system 100 has voltage converters 30a to 30d, the number of components constituting the power supply system 100 increases, the weight of the power supply system 100 increases, and the manufacturing cost of the power supply system 100 increases. In one embodiment, the power supply system 10 does not have voltage converters 30a to 30d, so the number of components constituting the power supply system 10 is reduced, the weight of the power supply system 10 is reduced, and the manufacturing cost of the power supply system 10 can be suppressed.

[0134] One embodiment of the power supply system 10 has a first connection circuit 22a and a second connection circuit 22b. However, the above technology can also be applied to a power supply system 10 that does not have a first connection circuit 22a and a second connection circuit 22b.

[0135] For example, if the supply of DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c is interrupted, the first power suppression control is performed on the first inverter 15a, the third power suppression control is performed on the third inverter 15c, the fifth power suppression control is performed on the fifth inverter 15e, and the seventh power suppression control is performed on the seventh inverter 15g. This suppresses the decrease in the State of Charge (SOC) of the first energy storage device 16a and the third energy storage device 16c.

[0136] Furthermore, if the supply of DC power from the first power generator 14a to the first power supply circuit 18a and the third power supply circuit 18c is interrupted, the second power increase control is performed on the second inverter 15b, the fourth power increase control is performed on the fourth inverter 15d, the sixth power increase control is performed on the sixth inverter 15f, and the eighth power increase control is performed on the eighth inverter 15h. As a result, the power that is reduced from the first power supply system 12a to the first motors 17a to the fourth motors 17d can be supplied from the second power supply system 12b to the first motors 17a to the fourth motors 17d. Therefore, the decrease in output torque of the first motors 17a to the fourth motors 17d can be suppressed.

[0137] The following additional information is disclosed regarding the above embodiments.

[0138] (Note 1) The power supply system (10) of this disclosure includes a first power supply circuit (18a) that supplies DC power output from a first power generator (14a) to a first inverter (15a), a first energy storage device (16a) connected in parallel with the first power generator to the first power supply circuit, a second power supply circuit (18b) that supplies DC power output from a second power generator (14b) to a second inverter (15b), a second energy storage device (16b) connected in parallel with the second power generator to the second power supply circuit, a first motor (17a) which is a dual three-phase motor that can be driven by power converted to AC by the first inverter and can also be driven by power converted to AC by the second inverter, and the first inverter and the second inverter The system includes a control device (30) that controls the motor, and when the supply of DC power from the first power generator to the first power supply circuit is interrupted, the control device performs a first power suppression control on the first inverter to reduce the first ratio, which is the ratio of the first power supplied from the first inverter to the first motor to the power consumption of the first motor, to less than before the supply of DC power from the first power generator to the first power supply circuit was interrupted, and performs a second power increase control on the second inverter to increase the second ratio, which is the ratio of the second power supplied from the second inverter to the first motor to the power consumption of the first motor, to more than before the supply of DC power from the first power generator to the first power supply circuit was interrupted. As a result, even when the supply of DC power from the first power generator to the first power supply circuit is interrupted, a decrease in the output torque of the first motor can be suppressed.

[0139] (Note 2) In the power supply system described in Appendix 1, the system further includes a connection circuit (22a) equipped with a connection device (24a) capable of connecting the first power supply circuit and the second power supply circuit, and the control device is capable of performing connection control on the connection device to connect the first power supply circuit and the second power supply circuit via the connection circuit. If the supply of DC power from the first generator to the first power supply circuit is interrupted and the difference between the voltage of the first power supply circuit and the voltage of the second power supply circuit is greater than or equal to a predetermined first voltage threshold, the control device may perform the first power suppression control on the first inverter and the second power increase control on the second inverter until the difference between the voltage of the first power supply circuit and the voltage of the second power supply circuit falls below a predetermined second voltage threshold, and then perform the connection control on the connection device. This makes it possible to suppress the flow of overcurrent in the power supply system when connection control is performed on the connection device.

[0140] (Note 3) In the power supply system described in Appendix 2, the system further includes a circuit breaker (26a) capable of disconnecting the first power supply circuit and the connection circuit from the first power generator. If the power supply from the first power generator to the first power supply circuit is interrupted, the control device may, after disconnecting the first power supply circuit and the connection circuit from the first power generator using the circuit breaker, perform the connection control on the connection device. This makes it possible to suppress the effects of an abnormality occurring in the first power generator on the first power supply circuit and the connection circuit.

[0141] (Note 4) In the power supply system described in Appendix 1, the difference between the magnitude of the first ratio reduced by the first power suppression control and the magnitude of the second ratio increased by the second power increase control may be less than or equal to a predetermined value. This makes it possible to suppress a decrease in the output torque of the first motor even when the supply of DC power from the first power generator to the first power supply circuit is interrupted.

[0142] (Note 5) The power supply system described in Appendix 1 further comprises a second motor (17b), which is a dual three-phase motor that can be driven by power converted to AC by a third inverter (15c) and also by power converted to AC by a fourth inverter (15d), wherein the first power supply circuit supplies DC power output from the first power generator to the first inverter and the third inverter, and the second power supply circuit supplies DC power output from the second power generator to the second inverter and the fourth inverter, and the supply of DC power from the first power generator to the first power supply circuit is interrupted. If this occurs, the control device may perform a third power suppression control on the third inverter, which reduces the third ratio, the ratio of the third power supplied from the third inverter to the second motor to the power consumption of the second motor, to less than before the supply of DC power from the first generator to the first power supply circuit was cut off. At the same time, it may perform a fourth power increase control on the fourth inverter, which increases the fourth ratio, the ratio of the fourth power supplied from the fourth inverter to the second motor to the power consumption of the second motor, to more than before the supply of DC power from the first generator to the first power supply circuit was cut off. This makes it possible to suppress a decrease in the output torque of the second motor even when the supply of DC power from the first generator to the first power supply circuit is cut off.

[0143] (Note 6) In the power supply system described in Appendix 5, the system further includes a connection circuit equipped with a connection device capable of connecting the first power supply circuit and the second power supply circuit, and the control device is capable of performing connection control on the connection device to connect the first power supply circuit and the second power supply circuit via the connection circuit. If the supply of DC power from the first generator to the first power supply circuit is interrupted and the difference between the voltage of the first power supply circuit and the voltage of the second power supply circuit is greater than or equal to a predetermined first voltage threshold, the control device may perform the first power suppression control on the first inverter, the second power increase control on the second inverter, the third power suppression control on the third inverter, and the fourth power increase control on the fourth inverter until the difference between the voltage of the first power supply circuit and the voltage of the second power supply circuit falls below a predetermined second voltage threshold, and then perform the connection control on the connection device. This makes it possible to suppress the flow of overcurrent in the power supply system when connection control is performed on the connection device.

[0144] (Note 7) The mobile body of this disclosure has a power supply system as described in any one of appendices 1 to 6. This makes it possible to suppress a decrease in the output torque of the first motor even when the supply of DC power from the first power generator to the first power supply circuit is interrupted.

[0145] (Note 8) The control method for a power supply system of the present disclosure comprises: a first power supply circuit that supplies DC power output from a first power generator to a first inverter; a first energy storage device connected in parallel with the first power generator to the first power supply circuit; a second power supply circuit that supplies DC power output from a second power generator to a second inverter; a second energy storage device connected in parallel with the second power generator to the second power supply circuit; and a first motor which is a dual three-phase motor that can be driven by power converted to AC by the first inverter and can also be driven by power converted to AC by the second inverter, wherein the first power generator If the supply of DC power from the device to the first power supply circuit is interrupted, a first power suppression control is performed on the first inverter to reduce the first ratio, which is the ratio of the first power supplied from the first inverter to the first motor to the power consumption of the first motor, to less than before the supply of DC power from the first power generator to the first power supply circuit was interrupted. At the same time, a second power increase control is performed on the second inverter to increase the second ratio, which is the ratio of the second power supplied from the second inverter to the first motor to the power consumption of the first motor, to more than before the supply of DC power from the first power generator to the first power supply circuit was interrupted. As a result, even if the supply of DC power from the first power generator to the first power supply circuit is interrupted, a decrease in the output torque of the first motor can be suppressed.

[0146] (Note 9) The program of this disclosure causes a computer to execute the control method for the power supply system described in Appendix 8. This makes it possible to suppress a decrease in the output torque of the first motor even when the supply of DC power from the first power generator to the first power supply circuit is interrupted.

[0147] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the intent of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above. [Explanation of Symbols]

[0148] 10...Power supply system 14a...First power generator 14b...Second power generator 15a...First inverter 15b...2nd inverter 15c...3rd inverter 15d...Fourth inverter 16a...First energy storage device 16b...Second energy storage device 17a...First motor 17b...Second motor 18a...First power supply circuit 18b...Second power supply circuit 22a...First connection circuit (connection circuit) 24a...First connection device (connection device) 26a...Breakdown device 30...Control device

Claims

1. A first power supply circuit that supplies DC power output from the first power generator to the first inverter, The first power supply circuit includes a first energy storage device connected in parallel with the first power generation device, A second power supply circuit that supplies DC power output from the second power generator to the second inverter, The second power supply circuit includes a second energy storage device connected in parallel with the second power generation device, A first motor is a dual three-phase motor that can be driven by power converted to AC by the first inverter and can also be driven by power converted to AC by the second inverter, A control device for controlling the first inverter and the second inverter, Equipped with, If the supply of DC power from the first power generator to the first power supply circuit is interrupted, The control device is A first power suppression control is performed on the first inverter, which is the ratio of the first power supplied from the first inverter to the first motor to the power consumption of the first motor, to a first ratio that is smaller than the ratio before the supply of DC power from the first power generator to the first power supply circuit was cut off. A power supply system that performs a second power increase control on the second inverter, which is the ratio of the second power supplied from the second inverter to the first motor to the power consumption of the first motor, to a second ratio, which is greater than the ratio before the supply of DC power from the first power generator to the first power supply circuit was interrupted.

2. In the power supply system according to claim 1, The connection circuit further includes a connection device that can connect the first power supply circuit and the second power supply circuit, The control device is capable of performing connection control on the connection device for connecting the first power supply circuit and the second power supply circuit via the connection circuit. A power supply system in which, when the supply of DC power from the first power generator to the first power supply circuit is interrupted, and the difference between the voltage of the first power supply circuit and the voltage of the second power supply circuit is greater than or equal to a predetermined first voltage threshold, the control device performs the first power suppression control on the first inverter and the second power increase control on the second inverter, and then performs the connection control on the connection device, until the difference between the voltage of the first power supply circuit and the voltage of the second power supply circuit falls below a predetermined second voltage threshold.

3. In the power supply system according to claim 2, The device further includes a circuit breaker capable of disconnecting the first power supply circuit and the connection circuit from the first power generation device. A power supply system in which, when the power supply from the first power generator to the first power supply circuit is interrupted, the control device disconnects the first power supply circuit and the connection circuit from the first power generator using the disconnection device, and then performs the connection control on the connection device.

4. In the power supply system according to claim 1, A power supply system in which the difference between the magnitude of the first ratio reduced by the first power suppression control and the magnitude of the second ratio increased by the second power increase control is less than or equal to a predetermined value.

5. In the power supply system according to claim 1, The system further includes a second motor, which is a dual three-phase motor that can be driven by power converted to AC by a third inverter and also by power converted to AC by a fourth inverter. The first power supply circuit supplies DC power output from the first power generator to the first inverter and the third inverter. The second power supply circuit supplies DC power output from the second power generator to the second inverter and the fourth inverter. If the supply of DC power from the first power generator to the first power supply circuit is interrupted, The control device is A third power suppression control is performed on the third inverter, which is the ratio of the third power supplied from the third inverter to the second motor to the power consumption of the second motor, to less than the ratio before the supply of DC power from the first power generator to the first power supply circuit was cut off. A power supply system that performs a fourth power increase control on the fourth inverter, which makes the fourth ratio, which is the ratio of the fourth power supplied from the fourth inverter to the second motor to the power consumption of the second motor, greater than before the supply of DC power from the first power generator to the first power supply circuit was interrupted.

6. In the power supply system according to claim 5, The connection circuit further includes a connection device that can connect the first power supply circuit and the second power supply circuit, The control device is capable of performing connection control on the connection device for connecting the first power supply circuit and the second power supply circuit via the connection circuit. A power supply system in which, when the supply of DC power from the first power generator to the first power supply circuit is interrupted and the difference between the voltage of the first power supply circuit and the voltage of the second power supply circuit is greater than or equal to a predetermined first voltage threshold, the control device performs the first power suppression control on the first inverter, the second power increase control on the second inverter, the third power suppression control on the third inverter, and the fourth power increase control on the fourth inverter, and then performs the connection control on the connection device, until the difference between the voltage of the first power supply circuit and the voltage of the second power supply circuit falls below a predetermined second voltage threshold.

7. A mobile body having a power supply system according to any one of claims 1 to 6.

8. A first power supply circuit that supplies DC power output from the first power generator to the first inverter, The first power supply circuit includes a first energy storage device connected in parallel with the first power generation device, A second power supply circuit that supplies DC power output from the second power generator to the second inverter, The second power supply circuit includes a second energy storage device connected in parallel with the second power generation device, A first motor is a dual three-phase motor that can be driven by power converted to AC by the first inverter and can also be driven by power converted to AC by the second inverter, A control method for a power supply system comprising: If the supply of DC power from the first power generator to the first power supply circuit is interrupted, A first power suppression control is performed on the first inverter, which is the ratio of the first power supplied from the first inverter to the first motor to the power consumption of the first motor, to a first ratio that is smaller than the ratio before the supply of DC power from the first power generator to the first power supply circuit was cut off. A control method for a power supply system, comprising: executing a second power increase control on the second inverter, which is the ratio of the second power supplied from the second inverter to the first motor to the power consumption of the first motor, to a second ratio greater than before the supply of DC power from the first power generator to the first power supply circuit was interrupted.

9. A program that causes a computer to execute the control method for the power supply system described in claim 8.

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