Power supply system, movable body, and control method for power supply system

Abstract

To provide a power supply system, a movable body, and a control method for the power supply system that contribute to energy efficiency.SOLUTION: A power supply system 10 includes: a first power supply circuit 12a that supplies power output from a first power conversion device 14a to a first load device 16a; a second power supply circuit 12b that supplies power output from a second power conversion device 14b to a second load device 16b; and a first connection circuit 18a that connects the first power supply circuit and the second power supply circuit, wherein when the power output from the second power conversion device is supplied to the first load device, the first power supply circuit and the second power supply circuit are connected after lowering the power output from the second power conversion device.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to a power supply system, a mobile object, and a method for controlling a power supply system. [Background technology]

[0002] In recent years, research and development into electrification technologies that contribute to energy efficiency has been conducted to ensure that more people have access to affordable, reliable, sustainable and advanced energy.

[0003] Patent Document 1 below discloses an aircraft electric energy supply network (power supply system). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2022-529997 Summary of the Invention [Problem to be solved by the invention]

[0005] In the field of electrification technology, there is a demand for better power supply systems, mobile bodies having better power supply systems, and better methods for controlling power supply systems.

[0006] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0007] A first aspect of the present disclosure includes a first power generating device that outputs three-phase AC power, a second power generating device that outputs three-phase AC power, a first power conversion device having a smoothing capacitor and converting the three-phase AC power output from the first power generating device into DC power, a second power conversion device having a smoothing capacitor and converting the three-phase AC power output from the second power generating device into DC power, a first power supply circuit that supplies the DC power output from the first power conversion device to a first load device, a second power supply circuit that supplies the DC power output from the second power conversion device to a second load device, a first power storage device connected to the first power supply circuit in parallel with the first power generating device, and a second power storage device connected to the second power supply circuit in parallel with the first power generating device. The power supply system includes a second storage device connected in parallel with the second power generation device to a power supply circuit, a first connection circuit having a first connection device capable of connecting the first power supply circuit and the second power supply circuit, and a control device capable of executing first connection control on the first connection device to connect the first power supply circuit and the second power supply circuit, wherein when the DC power output from the second power conversion device is supplied to the first load device, the control device executes the first connection control on the first connection device after first power reduction control is executed on the second power conversion device to reduce the DC power output from the second power conversion device.

[0008] A second aspect of the present disclosure is a mobile object having the power supply system according to the first aspect.

[0009] A third aspect of the present disclosure provides a power supply system including a first power generating device that outputs three-phase AC power, a second power generating device that outputs three-phase AC power, a first power conversion device having a smoothing capacitor and converting the three-phase AC power output from the first power generating device into DC power, a second power conversion device having a smoothing capacitor and converting the three-phase AC power output from the second power generating device into DC power, a first power supply circuit that supplies the DC power output from the first power conversion device to a first load device, a second power supply circuit that supplies the DC power output from the second power conversion device to a second load device, and a first storage battery connected to the first power supply circuit in parallel with the first power generating device. a second power storage device connected in parallel with the second power generation device to the second power supply circuit; and a first connection circuit provided with a first connection device capable of connecting the first power supply circuit and the second power supply circuit, wherein, when the DC power output from the second power conversion device is supplied to the first load device, first power reduction control is executed on the second power conversion device to reduce the DC power output from the second power conversion device, and then first connection control is executed on the first connection device to connect the first power supply circuit and the second power supply circuit. [Effects of the Invention]

[0010] The present invention can provide a better power supply system, a mobile object having a better power supply system, and a better control method for the power supply system, which in turn contributes to energy efficiency. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of a power supply system according to the first embodiment. [Figure 2] FIG. 2 is a schematic diagram of the first power conversion device of the first embodiment. [Figure 3] FIG. 3 is a schematic diagram showing the configuration of the backflow prevention device according to the first embodiment. [Figure 4]FIG. 4 is a schematic diagram showing the configuration of the backflow prevention device according to the first embodiment. [Figure 5] FIG. 5 is a diagram showing the operation of the power supply system in a normal state in the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating the operation of the power supply system in the first embodiment when an abnormality occurs. [Figure 7] FIG. 7 is a diagram illustrating the operation of the power supply system in the first embodiment when an abnormality occurs. [Figure 8] FIG. 8 is a diagram illustrating the operation of the power supply system in the first embodiment when an abnormality occurs. [Figure 9] FIG. 9 is a diagram illustrating the operation of the power supply system in the first embodiment when an abnormality occurs. [Figure 10] FIG. 10 is a schematic diagram showing the state of the second power converter when the first power reduction control is executed. [Figure 11] FIG. 11 is a control block diagram of the control device in the first embodiment. [Figure 12] FIG. 12 is a flowchart showing the fail-safe control in the first embodiment. [Figure 13] FIG. 13 is a diagram illustrating the operation of the power supply system in the first comparative example when an abnormality occurs. [Figure 14] FIG. 14 is a diagram illustrating the operation of the power supply system in the first comparative example when an abnormality occurs. [Figure 15] FIG. 15 is a diagram illustrating the operation of the power supply system in the first comparative example when an abnormality occurs. [Figure 16] FIG. 16 is a diagram illustrating the operation of the power supply system in the first embodiment when an abnormality occurs. [Figure 17] FIG. 17 is a diagram illustrating the operation of the power supply system in the first embodiment when an abnormality occurs. [Figure 18] FIG. 18 is a schematic diagram of a power supply system in the second comparative example. [Figure 19] FIG. 19 is a time chart showing the state of the power supply system before and after the first connection control is executed on the first connection device. [Figure 20] FIG. 20 is a time chart showing the state of the power supply system before and after the first connection control is executed on the first connection device. [Figure 21] FIG. 21 is a diagram illustrating the operation of the power supply system in the second embodiment when an abnormality occurs. [Figure 22] FIG. 22 is a diagram illustrating the operation of the power supply system in the second embodiment when an abnormality occurs. [Figure 23] FIG. 23 is a diagram illustrating the operation of the power supply system in the second embodiment when an abnormality occurs. [Figure 24] FIG. 24 is a diagram illustrating the operation of the power supply system in the second embodiment when an abnormality occurs. [Figure 25] FIG. 25 is a flowchart showing the fail-safe control in the second embodiment. [Figure 26] FIG. 26 is a flowchart showing the fail-safe control in the second embodiment. [Figure 27] FIG. 27 is a schematic diagram of a moving body in the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] [First embodiment] [Power supply system configuration] A power supply system 10 of this embodiment will be described with reference to the drawings. Fig. 1 is a schematic diagram of the power supply system 10 of this embodiment.

[0013] The power supply system 10 includes a first power supply circuit 12a, a second power supply circuit 12b, a third power supply circuit 12c, and a fourth power supply circuit 12d.

[0014] The first power supply circuit 12a supplies the DC power output from the first power conversion device 14a to the first load device 16a. The second power supply circuit 12b supplies the DC power output from the second power conversion device 14b to the second load device 16b. The third power supply circuit 12c supplies the DC power output from the first power conversion device 14a to the third load device 16c. The fourth power supply circuit 12d supplies the DC power output from the second power conversion device 14b to the fourth load device 16d.

[0015] The first power converter 14a converts the three-phase AC power output from the first power generator 15a into DC power, and the second power converter 14b converts the three-phase AC power output from the second power generator 15b into DC power.

[0016] The first power generating device 15a and the second power generating device 15b each have an engine and a generator (not shown). The generator is driven by the engine and generates three-phase AC power.

[0017] 2 is a schematic diagram of the first power converter 14a of this embodiment. The configuration of the second power converter 14b is the same as the configuration of the first power converter 14a.

[0018] The first power converter 14a has upper arm switching elements 17a to 17c, lower arm switching elements 19a to 19c, and a smoothing capacitor .

[0019] The switching elements 17a to 17c and the switching elements 19a to 19c are semiconductor switches such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), IGBTs (Insulated Gate Bipolar Transistors), etc. Freewheeling diodes may be provided in parallel with the switching elements 17a to 17c and the switching elements 19a to 19c, respectively.

[0020] In first power conversion device 14a, the on / off timings of switching elements 17a-17c and switching elements 19a-19c are controlled, thereby rectifying the three-phase AC power output from first power generation device 15a and converting it into DC power. Voltage fluctuations of the rectified DC power are suppressed in smoothing capacitor 21, and DC power with a stable voltage is output from first power conversion device 14a.

[0021] The first power conversion device 14a and the second power conversion device 14b may also include various elements such as various sensors such as voltage sensors and current sensors, fuses, relays, breakers, diodes, transistors, resistors, coils, and capacitors.

[0022] The first load device 16a, the second load device 16b, the third load device 16c, and the fourth load device 16d each have an inverter and an electric motor (not shown). The inverter converts input DC power into three-phase AC power, and the electric motor is driven by the three-phase AC power. The first load device 16a, the second load device 16b, the third load device 16c, and the fourth load device 16d may also have a DC / DC converter and a low-voltage drive device (not shown). The DC / DC converter reduces the voltage of the input DC power, and the low-voltage drive device is driven by the DC power.

[0023] The first load device 16a, the second load device 16b, the third load device 16c, and the fourth load device 16d may have various sensors such as voltage sensors and current sensors, and elements such as fuses, relays, breakers, diodes, transistors, resistors, coils, and capacitors.

[0024] The power supply system 10 includes a first connection circuit 18a and a second connection circuit 18b. The first connection circuit 18a includes a first connection device 20a that can connect the first power supply circuit 12a and the second power supply circuit 12b. The second connection circuit 18b includes a second connection device 20b that can connect the third power supply circuit 12c and the fourth power supply circuit 12d.

[0025] The first connection device 20a is switched by a contactor (not shown) between a state in which the first power supply circuit 12a and the second power supply circuit 12b are connected and a state in which the first power supply circuit 12a and the second power supply circuit 12b are disconnected. Similarly, the second connection device 20b is switched by a contactor (not shown) between a state in which the third power supply circuit 12c and the fourth power supply circuit 12d are connected and a state in which the third power supply circuit 12c and the fourth power supply circuit 12d are disconnected.

[0026] The first connection device 20a and the second connection device 20b may have a relay instead of a contactor. The first connection device 20a and the second connection device 20b may have a breaker instead of a contactor. The first connection device 20a and the second connection device 20b may have a semiconductor switch instead of a contactor.

[0027] Normally, the first power supply circuit 12a and the second power supply circuit 12b are disconnected. This prevents an abnormality from occurring in either the first power supply circuit 12a or the second power supply circuit 12b from affecting the other. For example, if an overcurrent occurs in either the first power supply circuit 12a or the second power supply circuit 12b, the overcurrent is prevented from flowing in the other.

[0028] Similarly, the third power supply circuit 12c and the fourth power supply circuit 12d are normally disconnected. This prevents an abnormality from occurring in either the third power supply circuit 12c or the fourth power supply circuit 12d from affecting the other. For example, if an overcurrent occurs in either the third power supply circuit 12c or the fourth power supply circuit 12d, the overcurrent is prevented from flowing in the other.

[0029] When the supply of power from the first power conversion device 14a to the first power supply circuit 12a is cut off, the first connection device 20a connects the first power supply circuit 12a to the second power supply circuit 12b, thereby supplying power from the second power conversion device 14b to the first power supply circuit 12a.

[0030] When the supply of power from the first power converter 14a to the third power supply circuit 12c is cut off, the second connection device 20b connects the third power supply circuit 12c to the fourth power supply circuit 12d, thereby supplying power from the second power converter 14b to the third power supply circuit 12c.

[0031] When the supply of power from the second power conversion device 14b to the second power supply circuit 12b is cut off, the first connection device 20a connects the first power supply circuit 12a and the second power supply circuit 12b, thereby supplying power from the first power conversion device 14a to the second power supply circuit 12b.

[0032] When the supply of power from the second power converter 14b to the fourth power supply circuit 12d is cut off, the second connection device 20b connects the third power supply circuit 12c and the fourth power supply circuit 12d, thereby supplying power from the first power converter 14a to the fourth power supply circuit 12d.

[0033] The power supply system 10 includes interrupting devices 22a to 22d. The interrupting device 22a can interrupt the first power conversion device 14a from the first power supply circuit 12a and the first connection circuit 18a. The interrupting device 22b can interrupt the second power conversion device 14b from the second power supply circuit 12b and the first connection circuit 18a. The interrupting device 22c can interrupt the first power conversion device 14a from the third power supply circuit 12c and the second connection circuit 18b. The interrupting device 22d can interrupt the second power conversion device 14b from the fourth power supply circuit 12d and the second connection circuit 18b.

[0034] The circuit breaker 22a switches, by a contactor (not shown), between a state in which the first power conversion device 14a is disconnected from the first power supply circuit 12a and the first connection circuit 18a and a state in which the first power conversion device 14a is connected to the first power supply circuit 12a and the first connection circuit 18a. Similarly, the circuit breaker 22b switches, by a contactor (not shown), between a state in which the second power conversion device 14b is disconnected from the second power supply circuit 12b and the first connection circuit 18a and a state in which the second power conversion device 14b is connected to the second power supply circuit 12b and the first connection circuit 18a.

[0035] Furthermore, the circuit breaker 22c switches, by a contactor (not shown), between a state in which the first power conversion device 14a is disconnected from the third power supply circuit 12c and the second connection circuit 18b and a state in which the first power conversion device 14a is connected to the third power supply circuit 12c and the second connection circuit 18b. Similarly, the circuit breaker 22d switches, by a contactor (not shown), between a state in which the second power conversion device 14b is disconnected from the fourth power supply circuit 12d and the second connection circuit 18b and a state in which the second power conversion device 14b is connected to the fourth power supply circuit 12d and the second connection circuit 18b.

[0036] The interrupting devices 22a to 22d may have a relay instead of a contactor.The interrupting devices 22a to 22d may have a breaker instead of a contactor.The interrupting devices 22a to 22d may have a semiconductor switch instead of a contactor.

[0037] The power supply system 10 includes a first power storage device 24a, a second power storage device 24b, a third power storage device 24c, and a fourth power storage device 24d. The first power storage device 24a is connected to the first power supply circuit 12a in parallel with the first power conversion device 14a. The second power storage device 24b is connected to the second power supply circuit 12b in parallel with the second power conversion device 14b. The third power storage device 24c is connected to the third power supply circuit 12c in parallel with the first power conversion device 14a. The fourth power storage device 24d is connected to the fourth power supply circuit 12d in parallel with the second power conversion device 14b.

[0038] The first power storage device 24a, the second power storage device 24b, the third power storage device 24c, and the fourth power storage device 24d include lithium ion batteries. The first power storage device 24a, the second power storage device 24b, the third power storage device 24c, and the fourth power storage device 24d may include secondary batteries other than lithium ion batteries. The first power storage device 24a, the second power storage device 24b, the third power storage device 24c, and the fourth power storage device 24d may include large-capacity capacitors.

[0039] The first power storage device 24a, the second power storage device 24b, the third power storage device 24c, and the fourth power storage device 24d may include various elements such as voltage sensors, current sensors, fuses, relays, breakers, diodes, transistors, resistors, coils, and capacitors.

[0040] The power supply system 10 includes interrupting devices 26a to 26d. The interrupting device 26a can disconnect the first power storage device 24a from the first power supply circuit 12a and the first load device 16a. The interrupting device 26b can disconnect the second power storage device 24b from the second power supply circuit 12b and the second load device 16b. The interrupting device 26c can disconnect the third power storage device 24c from the third power supply circuit 12c and the third load device 16c. The interrupting device 26d can disconnect the fourth power storage device 24d from the fourth power supply circuit 12d and the fourth load device 16d.

[0041] The circuit breaker 26a switches, by a contactor (not shown), between a state in which the first power storage device 24a is disconnected from the first power supply circuit 12a and the first load device 16a and a state in which the first power storage device 24a is connected to the first power supply circuit 12a and the first load device 16a. Similarly, the circuit breaker 26b switches, by a contactor (not shown), between a state in which the second power storage device 24b is disconnected from the second power supply circuit 12b and the second load device 16b and a state in which the second power storage device 24b is connected to the second power supply circuit 12b and the second load device 16b.

[0042] Furthermore, the circuit breaker 26c switches, by a contactor (not shown), between a state in which the third power storage device 24c is disconnected from the third power supply circuit 12c and the third load device 16c and a state in which the third power storage device 24c is connected to the third power supply circuit 12c and the third load device 16c. Similarly, the circuit breaker 26d switches, by a contactor (not shown), between a state in which the fourth power storage device 24d is disconnected from the fourth power supply circuit 12d and the fourth load device 16d and a state in which the fourth power storage device 24d is connected to the fourth power supply circuit 12d and the fourth load device 16d.

[0043] The circuit breakers 26a to 26d may have relays instead of contactors.The circuit breakers 26a to 26d may have breakers instead of contactors.The circuit breakers 26a to 26d may have semiconductor switches instead of contactors.

[0044] The power supply system 10 includes backflow prevention devices 28a to 28d. The backflow prevention device 28a limits the supply of power from the first power storage device 24a to the first power supply circuit 12a. The backflow prevention device 28b limits the supply of power from the second power storage device 24b to the second power supply circuit 12b. The backflow prevention device 28c limits the supply of power from the third power storage device 24c to the third power supply circuit 12c. The backflow prevention device 28d limits the supply of power from the fourth power storage device 24d to the fourth power supply circuit 12d.

[0045] 3 is a schematic diagram showing the configuration of the backflow prevention device 28a in this embodiment. The configurations of the backflow prevention devices 28b to 28d are the same as the configuration of the backflow prevention device 28a. The backflow prevention device 28a includes a diode 30 and a transistor 32.

[0046] The diode 30 is provided on the positive wiring. When the anode voltage is lower than the cathode voltage, the diode 30 barely passes any current. When the anode voltage is higher than the cathode voltage and the potential difference between the cathode and anode is equal to or greater than the forward voltage, the diode 30 passes current. As a result, power is supplied from the first power supply circuit 12a to the first load device 16a and the first power storage device 24a via the diode 30. On the other hand, power is not supplied from the first load device 16a and the first power storage device 24a to the first power supply circuit 12a via the diode 30.

[0047] The transistor 32 is provided to bypass the diode 30. When a current flows from the base to the emitter of the transistor 32, the current flows from the collector to the emitter. This causes power to be supplied from the first power storage device 24a to the first power supply circuit 12a via the transistor 32. When power is not supplied from the first power storage device 24a to the first power supply circuit 12a, the transistor 32 may be omitted. Another switching element may be used instead of the transistor 32.

[0048] Fig. 4 is a schematic diagram showing the configuration of the backflow prevention device 28a in this embodiment. As shown in Fig. 4, the diode 30 may be provided in the negative electrode wiring. Alternatively, the diode 30 may be provided in both the positive electrode wiring and the negative electrode wiring.

[0049] In addition to the configuration described above, the power supply system 10 may include various sensors such as a voltage sensor and a current sensor, and various elements such as fuses, resistors, coils, and capacitors.

[0050] [Operation of the power supply system under normal conditions] 5 is a diagram showing the operation of the power supply system 10 in a normal state in this embodiment. Arrows shown in FIG. 5 indicate power supply paths.

[0051] The first power conversion device 14a is connected to the first power supply circuit 12a by the interrupter 22a, and the first power conversion device 14a is connected to the third power supply circuit 12c by the interrupter 22c. As a result, the three-phase AC power output from the first power generation device 15a is converted into DC power in the first power conversion device 14a and supplied to the first load device 16a and the third load device 16c.

[0052] The second power conversion device 14b is connected to the second power supply circuit 12b by the interrupter 22b, and the second power conversion device 14b is connected to the fourth power supply circuit 12d by the interrupter 22d. As a result, the three-phase AC power output from the second power generation device 15b is converted to DC power in the second power conversion device 14b and supplied to the second load device 16b and the fourth load device 16d.

[0053] The first power storage device 24a is connected to the first load device 16a by the interrupting device 26a. As a result, the DC power output from the first power storage device 24a is supplied to the first load device 16a. The second power storage device 24b is connected to the second load device 16b by the interrupting device 26b. As a result, the DC power output from the second power storage device 24b is supplied to the second load device 16b. The third power storage device 24c is connected to the third load device 16c by the interrupting device 26c. As a result, the DC power output from the third power storage device 24c is supplied to the third load device 16c. The fourth power storage device 24d is connected to the fourth load device 16d by the interrupting device 26d. As a result, the DC power output from the fourth power storage device 24d is supplied to the fourth load device 16d.

[0054] Under normal conditions, the first connection device 20a disconnects the first power supply circuit 12a and the second power supply circuit 12b, and the second connection device 20b disconnects the third power supply circuit 12c and the fourth power supply circuit 12d.

[0055] [Power supply system operation during abnormal conditions] 6 to 9 are diagrams showing the operation of the power supply system 10 in the event of an abnormality in this embodiment. The arrows in Fig. 6 to 9 indicate the power supply paths. Fig. 6 to 9 show the operation of the power supply system 10 when the supply of power from the first power conversion device 14a to the first power supply circuit 12a and the third power supply circuit 12c is cut off.

[0056] The state in which the power supply from the first power conversion device 14a to the first power supply circuit 12a and the third power supply circuit 12c is cut off refers to, for example, a state in which the first power generation device 15a has stopped and cannot be restarted, or a state in which a short circuit, a break, or the like has occurred between the first power conversion device 14a and the circuit breaker 22a or between the first power conversion device 14a and the circuit breaker 22c.

[0057] When the supply of power from the first power converter 14a to the first power supply circuit 12a and the third power supply circuit 12c is cut off, the first power converter 14a is cut off from the first power supply circuit 12a and the first connection circuit 18a by the interrupter 22a, as shown in Fig. 6. Furthermore, the first power converter 14a is cut off from the third power supply circuit 12c and the second connection circuit 18b by the interrupter 22c. In this case, power is supplied to the first load device 16a only from the first power storage device 24a. Furthermore, power is supplied to the third load device 16c only from the third power storage device 24c.

[0058] Thereafter, the first power reduction control is executed on the second power conversion device 14b as shown in Fig. 7. The first power reduction control is control in which the second power conversion device 14b short-circuits the output of the second power generation device 15b, thereby reducing the DC power output from the second power conversion device 14b.

[0059] FIG. 10 is a schematic diagram showing the state of the second power converter 14b when the first power reduction control is executed. As shown in FIG. 10, each of the upper arm switching elements 17a to 17c is turned on (connected). The phases of the U-phase voltage, V-phase voltage, and W-phase voltage of the second power generator 15b are shifted by 120 degrees from each other. By short-circuiting the output of the second power generator 15b, the U-phase voltage, V-phase voltage, and W-phase voltage cancel each other out, and the output voltage of the second power generator 15b can be set to zero. As a result, only the DC power stored in the smoothing capacitor 21 is output from the second power converter 14b.

[0060] When the first power reduction control is executed, each of the switching elements 19a to 19c of the lower arm may be turned on (connected state). When each of the switching elements 19a to 19c of the lower arm is turned on (connected state), the output voltage of the second power generating device 15b can be set to zero.

[0061] After the first power reduction control is executed on the second power conversion device 14b, the first connection control is executed on the first connection device 20a while the first power reduction control is continued, as shown in FIG. 8 . By executing the first connection control, the first power supply circuit 12a and the second power supply circuit 12b are connected. At this time, the voltage of the first power supply circuit 12a is lower than the voltage of the second power supply circuit 12b, so a relatively large current flows through the first connection circuit 18a and the first power supply circuit 12a. However, because the first power reduction control is being executed, the current flowing through the first connection circuit 18a and the first power supply circuit 12a can be reduced compared to when the first power reduction control is not being executed. This reduces damage to the first load device 16a and the first power storage device 24a.

[0062] Furthermore, after the first power reduction control is executed on the second power conversion device 14b, the second connection control is executed on the second connection device 20b while the first power reduction control is continued, as shown in FIG. 8. By executing the second connection control, the third power supply circuit 12c and the fourth power supply circuit 12d are connected. At this time, the voltage of the third power supply circuit 12c is lower than the voltage of the fourth power supply circuit 12d, so a relatively large current flows through the second connection circuit 18b and the third power supply circuit 12c. However, because the first power reduction control is being executed, the current flowing through the second connection circuit 18b and the third power supply circuit 12c can be reduced compared to when the first power reduction control is not being executed. This reduces damage to the third load device 16c and the third power storage device 24c.

[0063] As shown in FIG. 9, the first power reduction control for the second power converter 14b is terminated in the following cases: when the difference between the voltage of the first power supply circuit 12a and the voltage of the second power supply circuit 12b is equal to or less than a predetermined voltage threshold, and when the difference between the voltage of the third power supply circuit 12c and the voltage of the fourth power supply circuit 12d is equal to or less than a predetermined voltage threshold. As a result, the three-phase AC power of the second power generator 15b is converted to DC power in the second power converter 14b and supplied to the first load device 16a and the third load device 16c. This allows the first load device 16a and the third load device 16c to continue to be driven.

[0064] [Control device configuration] The power supply system 10 includes a control device 34. Fig. 11 is a control block diagram of the control device 34 in this embodiment. The control device 34 controls the first power conversion device 14a, the second power conversion device 14b, the first connection device 20a, the second connection device 20b, the circuit breakers 22a to 22d, and the circuit breakers 26a to 26d. The control device 34 may control the first connection device 20a, the second connection device 20b, the circuit breakers 22a to 22d, and the circuit breakers 26a to 26d, and a control device separate from the control device 34 may control the first power conversion device 14a and the second power conversion device 14b.

[0065] The control device 34 has a calculation unit 36 and a storage unit 38. The calculation unit 36 is a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). The calculation unit 36 controls each device by executing a program stored in the storage unit 38. At least a part of the calculation unit 36 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). At least a part of the calculation unit 36 may be realized by an electronic circuit including discrete devices.

[0066] The storage unit 38 is configured by a volatile memory (not shown) and a nonvolatile memory (not shown), which are computer-readable storage media. The volatile memory is, for example, a random access memory (RAM). The nonvolatile memory is, for example, a read-only memory (ROM), a flash memory, etc. Data, etc., are stored in the volatile memory. Programs, tables, maps, etc., are stored in the nonvolatile memory. At least a part of the storage unit 38 may be provided in the processor, integrated circuit, etc. described above.

[0067] [Fail-safe control] 12 is a flowchart showing the fail-safe control in this embodiment. The fail-safe control is repeatedly executed at predetermined intervals.

[0068] In step S1, the control device 34 determines whether the supply of power from the first power conversion device 14a to the first power supply circuit 12a and the third power supply circuit 12c has been cut off. If it is determined that the supply of power from the first power conversion device 14a to the first power supply circuit 12a and the third power supply circuit 12c has been cut off (step S1: YES), the control device 34 proceeds to step S2.

[0069] In step S2, the control device 34 controls the breaker device 22a to break the first power conversion device 14a from the first power supply circuit 12a and the first connection circuit 18a, and then proceeds to step S3.

[0070] In step S3, the control device 34 controls the breaker device 22c to break the first power converter 14a from the third power supply circuit 12c and the second connection circuit 18b, and then proceeds to step S4.

[0071] In step S4, the control device 34 executes the first power reduction control on the second power conversion device 14b. This reduces the power output from the second power conversion device 14b. Then, the process proceeds to step S5. If the second power conversion device 14b is controlled by a control device other than the control device 34, the other control device may execute the first power reduction control on the second power conversion device 14b.

[0072] In step S5, the control device 34 executes first connection control on the first connection device 20a. As a result, the first power supply circuit 12a and the second power supply circuit 12b are connected via the first connection circuit 18a. Then, the process proceeds to step S6.

[0073] In step S6, the control device 34 executes second connection control on the second connection device 20b. As a result, the third power supply circuit 12c and the fourth power supply circuit 12d are connected via the second connection circuit 18b. Then, the process proceeds to step S7.

[0074] In step S7, the control device 34 determines whether the difference between the voltage of the first power supply circuit 12a and the voltage of the second power supply circuit 12b is equal to or less than a predetermined voltage threshold. If it is determined that the difference between the voltage of the first power supply circuit 12a and the voltage of the second power supply circuit 12b is equal to or less than the predetermined voltage threshold, the process proceeds to step S8. If it is determined that the difference between the voltage of the first power supply circuit 12a and the voltage of the second power supply circuit 12b is greater than the predetermined voltage threshold, the process of step S7 is repeated.

[0075] In step S8, the control device 34 determines whether the difference between the voltages of the third power supply circuit 12c and the fourth power supply circuit 12d is equal to or less than a predetermined voltage threshold. If it is determined that the difference between the voltages of the third power supply circuit 12c and the fourth power supply circuit 12d is equal to or less than the predetermined voltage threshold, the control device 34 proceeds to step S9. If it is determined that the difference between the voltages of the third power supply circuit 12c and the fourth power supply circuit 12d is greater than the predetermined voltage threshold, the process of step S8 is repeated.

[0076] In step S9, the control device 34 ends the first power reduction control for the second power electronics device 14b. Thereafter, the fail-safe control is ended. Note that the processing of step S7 and the processing of step S8 may be omitted, and the first power reduction control may be ended after a predetermined time threshold has elapsed from the time point at which the second connection control is executed. If the second power electronics device 14b is controlled by a control device other than the control device 34, the other control device may end the first power reduction control for the second power electronics device 14b.

[0077] In step S1, if it is determined that power is being supplied from the first power conversion device 14a to the first power supply circuit 12a and the third power supply circuit 12c (step S1: NO), the process proceeds to step S10.

[0078] In step S10, the control device 34 determines whether the supply of power from the second power conversion device 14b to the second power supply circuit 12b and the fourth power supply circuit 12d has been cut off. If it is determined that the supply of power from the second power conversion device 14b to the second power supply circuit 12b and the fourth power supply circuit 12d has been cut off (step S10: YES), the control device 34 proceeds to step S11. If it is determined that power is being supplied from the second power conversion device 14b to the second power supply circuit 12b and the fourth power supply circuit 12d (step S10: NO), the fail-safe control ends.

[0079] In step S11, the control device 34 controls the breaker device 22b to break the second power conversion device 14b from the second power supply circuit 12b and the first connection circuit 18a, and then proceeds to step S12.

[0080] In step S12, the control device 34 controls the breaker device 22d to break the second power converter 14b from the fourth power supply circuit 12d and the second connection circuit 18b, and then proceeds to step S13.

[0081] In step S13, the control device 34 executes second power reduction control on the first power conversion device 14a. The second power reduction control is control in which the output of the first power generation device 15a in the first power conversion device 14a is short-circuited to reduce the DC power output from the first power conversion device 14a. Then, the process proceeds to step S14. If the first power conversion device 14a is controlled by a control device other than the control device 34, the other control device may execute the second power reduction control on the first power conversion device 14a.

[0082] In step S14, the control device 34 executes the first connection control for the first connection device 20a. As a result, the first power supply circuit 12a and the second power supply circuit 12b are connected via the first connection circuit 18a. Then, the process proceeds to step S15.

[0083] In step S15, the control device 34 executes the second connection control for the second connection device 20b. As a result, the third power supply circuit 12c and the fourth power supply circuit 12d are connected via the second connection circuit 18b. Then, the process proceeds to step S16.

[0084] In step S16, the control device 34 determines whether the difference between the voltages of the first power supply circuit 12a and the second power supply circuit 12b is equal to or less than a predetermined voltage threshold. If it is determined that the difference between the voltages of the first power supply circuit 12a and the second power supply circuit 12b is equal to or less than the predetermined voltage threshold, the process proceeds to step S17. If it is determined that the difference between the voltages of the first power supply circuit 12a and the second power supply circuit 12b is greater than the predetermined voltage threshold, the process of step S16 is repeated.

[0085] In step S17, the control device 34 determines whether the difference between the voltage of the third power supply circuit 12c and the voltage of the fourth power supply circuit 12d is equal to or less than a predetermined voltage threshold. If it is determined that the difference between the voltage of the third power supply circuit 12c and the voltage of the fourth power supply circuit 12d is equal to or less than the predetermined voltage threshold, the process proceeds to step S18. If it is determined that the difference between the voltage of the third power supply circuit 12c and the voltage of the fourth power supply circuit 12d is greater than the predetermined voltage threshold, the process of step S17 is repeated.

[0086] In step S18, the control device 34 ends the second power reduction control for the first power electronics device 14a. Thereafter, the fail-safe control is ended. Note that the processing of step S16 and the processing of step S17 may be omitted, and the second power reduction control may be ended after a predetermined time threshold has elapsed from the time point at which the second connection control was executed. If the first power electronics device 14a is controlled by a control device other than the control device 34, the other control device may end the second power reduction control for the first power electronics device 14a.

[0087] [Comparison between the power supply system of this embodiment and the power supply system of Comparative Example 1] Figures 13 and 14 are diagrams showing the operation of the power supply system 100 in the event of an abnormality in Comparative Example 1. Unlike the power supply system 10 of the present embodiment (Figure 1), the power supply system 100 of Comparative Example 1 shown in Figure 13 does not have backflow prevention devices 28a to 28d. Figures 13 and 14 show the operation of the power supply system 100 when the supply of power from the first power conversion device 14a to the first power supply circuit 12a and the third power supply circuit 12c is cut off.

[0088] In this case, the first power converter 14a is disconnected from the first power supply circuit 12a and the first connection circuit 18a by the interrupter 22a, and the first power converter 14a is disconnected from the third power supply circuit 12c and the second connection circuit 18b by the interrupter 22c.

[0089] The first load device 16a is supplied with power only from the first power storage device 24a, and the third load device 16c is supplied with power only from the third power storage device 24c. Therefore, the SOC of the first power storage device 24a and the SOC of the third power storage device 24c decrease. Accordingly, the output voltage of the first power storage device 24a and the output voltage of the third power storage device 24c decrease. Meanwhile, the second load device 16b is supplied with power from the second power conversion device 14b and the second power storage device 24b, and the fourth load device 16d is supplied with power from the second power conversion device 14b and the fourth power storage device 24d. As a result, the SOC of the second power storage device 24b and the SOC of the fourth power storage device 24d hardly decrease. Therefore, the output voltage of the second power storage device 24b and the output voltage of the fourth power storage device 24d hardly decrease. As a result, the output voltage of the first power storage device 24a and the output voltage of the third power storage device 24c become lower than the output voltage of the second power storage device 24b and the output voltage of the fourth power storage device 24d.

[0090] The power supply system 100 does not include the backflow prevention device 28b and the backflow prevention device 28d. Since the second power storage device 24b and the fourth power storage device 24d output voltages stably, the output voltage of the second power conversion device 14b becomes substantially the same voltage as the output voltage of the second power storage device 24b and the output voltage of the fourth power storage device 24d.

[0091] 14, if the first power supply circuit 12a and the second power supply circuit 12b are connected by the first connection device 20a, an overcurrent may flow between the first power supply circuit 12a and the second power supply circuit 12b. Similarly, if the third power supply circuit 12c and the fourth power supply circuit 12d are connected by the second connection device 20b, an overcurrent may flow between the third power supply circuit 12c and the fourth power supply circuit 12d. This may damage the second power conversion device 14b, the first load device 16a, the second load device 16b, the third load device 16c, the fourth load device 16d, the first power storage device 24a, the second power storage device 24b, the third power storage device 24c, and the fourth power storage device 24d.

[0092] Fig. 15 is a diagram showing the operation of the power supply system 100 in the event of an abnormality in Comparative Example 1. Fig. 15 shows a state in which a short circuit occurs between the breaker device 22a and the first load device 16a and the first power storage device 24a.

[0093] In this case, an overcurrent may flow between the short-circuited point and the first power conversion device 14a, the first load device 16a, the first power storage device 24a, the third load device 16c, and the third power storage device 24c. This may damage the first power conversion device 14a, the first load device 16a, the first power storage device 24a, the third load device 16c, and the third power storage device 24c. As a result, the first load device 16a and the third load device 16c may not be able to continue operating.

[0094] Fig. 16 is a diagram showing the operation of the power supply system 10 in the event of an abnormality in this embodiment. Fig. 16 shows a state in which a short circuit occurs between the breaker device 22a and the backflow prevention device 28a.

[0095] In this case, there is a risk of an overcurrent flowing between the short-circuited location and the first power conversion device 14a. However, since the power supply system 10 of this embodiment is equipped with the backflow prevention device 28a and the backflow prevention device 28c, an overcurrent does not flow between the short-circuited location and the first load device 16a, the first power storage device 24a, the third load device 16c, and the third power storage device 24c. Therefore, the first load device 16a and the third load device 16c can continue to be driven.

[0096] Fig. 17 is a diagram showing the operation of the power supply system 10 in the event of an abnormality in this embodiment. Fig. 17 shows a state in which a short circuit occurs between the backflow prevention device 28a and the first load device 16a and the first power storage device 24a.

[0097] In this case, there is a risk of an overcurrent flowing between the short-circuited point and the first power conversion device 14a, the first load device 16a, and the first power storage device 24a. However, since the power supply system 10 of this embodiment is provided with the backflow prevention device 28c, an overcurrent does not flow between the short-circuited point and the third load device 16c and the third power storage device 24c. Therefore, the third load device 16c can continue to be driven.

[0098] [Comparison between the power supply system of this embodiment and the power supply system of Comparative Example 2] 18 is a schematic diagram of a power supply system 200 in Comparative Example 2. The power supply system 200 in Comparative Example 2 includes voltage conversion devices 40a to 40d. The voltage conversion devices 40a to 40d are DC-DC converters.

[0099] When the supply of power from the first power conversion device 14a to the first power supply circuit 12a and the third power supply circuit 12c is cut off, the power supply system 200 sets the output power of the voltage conversion device 40b to be lower than the output voltage of the second power storage device 24b. Also, the power supply system 200 sets the output power of the voltage conversion device 40d to be lower than the output voltage of the fourth power storage device 24d. This allows the output voltage of the second power conversion device 14b to be lower than the output voltage of the second power storage device 24b and the output voltage of the fourth power storage device 24d.

[0100] Therefore, when the first power supply circuit 12a and the second power supply circuit 12b are connected by the first connection device 20a, it is possible to prevent an overcurrent from flowing between the first power supply circuit 12a and the second power supply circuit 12b. Similarly, when the third power supply circuit 12c and the fourth power supply circuit 12d are connected by the second connection device 20b, it is possible to prevent an overcurrent from flowing between the third power supply circuit 12c and the fourth power supply circuit 12d.

[0101] However, the voltage conversion devices 40a to 40d are heavier than the backflow prevention devices 28a to 28d. The power supply system 10 of this embodiment can be made lighter by including the backflow prevention devices 28a to 28d.

[0102] [Comparison of whether or not the first power reduction control is executed] 19 and 20 are time charts showing the states of the power supply system 10 before and after the first connection control is executed on the first connection device 20a. Fig. 19 is a time chart showing the state when the first power reduction control is not executed before the first connection control is executed. Fig. 20 is a time chart showing the state when the first power reduction control is executed before the first connection control is executed.

[0103] The top graphs in Figures 19 and 20 show time charts illustrating the execution state of the first connection control. In the time charts illustrating the execution state of the first connection control, "1" indicates a state in which the first connection control is being executed, and "0" indicates a state in which the first connection control is not being executed. The second graphs from the top in Figures 19 and 20 show time charts illustrating the execution state of the first power reduction control. In the time charts illustrating the execution state of the first power reduction control, "1" indicates a state in which the first power reduction control is being executed, and "0" indicates a state in which the first power reduction control is not being executed. The third graphs from the top in Figures 19 and 20 show time charts of the voltage of the first power supply circuit 12a and the voltage of the second power supply circuit 12b. The bottom graphs in Figures 19 and 20 show time charts of the current of the first connection circuit 18a.

[0104] If the first power reduction control is not executed before the first connection control is executed, a large current flows through the first connection circuit 18a when the first connection control is executed (arrow "P" in FIG. 19). Even if the first power reduction control is executed before the first connection control is executed, a large current flows through the first connection circuit 18a when the first connection control is executed (arrow "Q" in FIG. 20).

[0105] The magnitude of the current at the time point indicated by the arrow "Q" in Fig. 20 is smaller than the magnitude of the current at the time point indicated by the arrow "P" in Fig. 19. Therefore, damage to the first load device 16a and the first power storage device 24a can be suppressed.

[0106] After the first connection control is executed, even when the first power reduction control ends, a large current flows through the first connection circuit 18a (arrow "R" in FIG. 20). This is because the short circuit in the second power generation device 15b is resolved when the first power reduction control ends. The magnitude of the current at the time indicated by the arrow "R" in FIG. 20 is smaller than the magnitude of the current at the time indicated by the arrow "P" in FIG. 19. Therefore, damage to the first load device 16a and the first power storage device 24a can be suppressed. The period during which the first power reduction control is executed is several [ms].

[0107] Second Embodiment The configuration of the power supply system 10 of this embodiment is the same as the configuration of the power supply system 10 of the first embodiment. The fail-safe control performed by the control device 34 of this embodiment is partially different from the fail-safe control performed by the control device 34 of the first embodiment.

[0108] [Power supply system operation during abnormal conditions] 21 to 24 are diagrams showing the operation of the power supply system 10 in the event of an abnormality in this embodiment. The arrows in Fig. 21 to 24 indicate the power supply path. Fig. 21 to 24 show the operation of the power supply system 10 when the supply of power from the first power conversion device 14a to the first load device 16a is stopped.

[0109] The state in which the supply of power from the first power converter 14a to the first load device 16a is stopped is, for example, a state in which the first load device 16a has stopped and cannot be restarted, or a state in which a short circuit, a break, or the like has occurred between the interrupter 22a and the first load device 16a.

[0110] When the supply of power from the first power conversion device 14a to the first load device 16a is stopped, as shown in FIG. 21, the first power conversion device 14a is disconnected from the first power supply circuit 12a and the first connection circuit 18a by the disconnection device 22a.

[0111] The first power conversion device 14a supplies power only to the third load device 16c. In contrast, the second power conversion device 14b supplies power to both the second load device 16b and the fourth load device 16d. Therefore, the SOC of the second power storage device 24b and the SOC of the fourth power storage device 24d are lower than the SOC of the third power storage device 24c. As a result, the output voltage of the second power storage device 24b and the output voltage of the fourth power storage device 24d are lower than the output voltage of the third power storage device 24c. Therefore, the voltage of the third power supply circuit 12c is higher than the voltage of the fourth power supply circuit 12d.

[0112] In this state, if the third power supply circuit 12c and the fourth power supply circuit 12d are connected, an overcurrent may flow to the second power conversion device 14b, the second load device 16b, the second power storage device 24b, the fourth load device 16d, and the fourth power storage device 24d, which may damage the second power conversion device 14b, the second load device 16b, the second power storage device 24b, the fourth load device 16d, and the fourth power storage device 24d.

[0113] In the power supply system 10 of this embodiment, as shown in Fig. 22, the second power reduction control is executed on the first power conversion device 14a. The second power reduction control is a control in the first power conversion device 14a in which the output of the first power generation device 15a is short-circuited to reduce the DC power output from the first power conversion device 14a. As a result, only the DC power stored in the smoothing capacitor 21 is output from the first power conversion device 14a.

[0114] After the second power reduction control is executed on the first power converter 14a, the second connection control is executed on the second connection device 20b, connecting the third power supply circuit 12c and the fourth power supply circuit 12d, as shown in FIG. 23, while the second power reduction control is continued. At this time, the voltage of the fourth power supply circuit 12d is lower than the voltage of the third power supply circuit 12c, so a relatively large current flows through the second connection circuit 18b and the fourth power supply circuit 12d. However, because the second power reduction control is being executed, the current flowing through the second connection circuit 18b and the fourth power supply circuit 12d can be reduced compared to when the second power reduction control is not being executed. This reduces damage to the fourth load device 16d and the fourth power storage device 24d.

[0115] When the difference between the voltage of the third power supply circuit 12c and the voltage of the fourth power supply circuit 12d becomes equal to or less than a predetermined voltage threshold, the second power reduction control for the first power conversion device 14a ends, as shown in Fig. 24. As a result, the three-phase AC power of the first power generation device 15a is converted into DC power in the first power conversion device 14a and supplied to the fourth load device 16d.

[0116] [Fail-safe control] 25 and 26 are flowcharts showing the fail-safe control in this embodiment. The fail-safe control is repeatedly executed at predetermined intervals.

[0117] In step S21, the control device 34 determines whether the supply of power from the first power conversion device 14a to the first load device 16a has been stopped. If it is determined that the supply of power from the first power conversion device 14a to the first load device 16a has been stopped (step S21: YES), the control device 34 proceeds to step S22.

[0118] In step S22, the control device 34 controls the breaker device 22a to break the first power conversion device 14a from the first power supply circuit 12a and the first connection circuit 18a, and then proceeds to step S23.

[0119] In step S23, the control device 34 executes the second power reduction control on the first power conversion device 14a. This reduces the power output from the first power conversion device 14a. Then, the process proceeds to step S24. If the first power conversion device 14a is controlled by a control device other than the control device 34, the other control device may execute the second power reduction control on the first power conversion device 14a.

[0120] In step S24, the control device 34 executes the second connection control for the second connection device 20b. As a result, the third power supply circuit 12c and the fourth power supply circuit 12d are connected via the second connection circuit 18b. Then, the process proceeds to step S25.

[0121] In step S25, the control device 34 determines whether the difference between the voltages of the third power supply circuit 12c and the fourth power supply circuit 12d is equal to or less than a predetermined voltage threshold. If it is determined that the difference between the voltages of the third power supply circuit 12c and the fourth power supply circuit 12d is equal to or less than the predetermined voltage threshold, the control device 34 proceeds to step S26. If it is determined that the difference between the voltages of the third power supply circuit 12c and the fourth power supply circuit 12d is greater than the predetermined voltage threshold, the process of step S25 is repeated.

[0122] In step S26, the control device 34 ends the second power reduction control for the first power electronics device 14a. Thereafter, the fail-safe control is ended. Note that the processing of step S25 may be omitted, and the second power reduction control may be ended a predetermined threshold after the second connection control is executed. If the first power electronics device 14a is controlled by a control device other than the control device 34, the other control device may end the second power reduction control for the first power electronics device 14a.

[0123] In step S21, if it is determined that power is being supplied from the first power converter 14a to the first load device 16a (step S21: NO), the process proceeds to step S27.

[0124] In step S27, the control device 34 determines whether the supply of power from the second power conversion device 14b to the second load device 16b has been stopped. If it is determined that the supply of power from the second power conversion device 14b to the second load device 16b has been stopped (step S27: YES), the process proceeds to step S28.

[0125] In step S28, the control device 34 controls the breaker device 22b to break the second power conversion device 14b from the second power supply circuit 12b and the first connection circuit 18a, and then proceeds to step S29.

[0126] In step S29, the control device 34 executes the first power reduction control on the second power conversion device 14b. This reduces the power output from the second power conversion device 14b. Then, the process proceeds to step S30. If the second power conversion device 14b is controlled by a control device other than the control device 34, the other control device may execute the first power reduction control on the second power conversion device 14b.

[0127] In step S30, the control device 34 executes second connection control on the second connection device 20b. As a result, the third power supply circuit 12c and the fourth power supply circuit 12d are connected via the second connection circuit 18b. Then, the process proceeds to step S31.

[0128] In step S31, the control device 34 determines whether the difference between the voltage of the third power supply circuit 12c and the voltage of the fourth power supply circuit 12d is equal to or less than a predetermined voltage threshold. If it is determined that the difference between the voltage of the third power supply circuit 12c and the voltage of the fourth power supply circuit 12d is equal to or less than the predetermined voltage threshold, the control device 34 proceeds to step S32. If it is determined that the difference between the voltage of the third power supply circuit 12c and the voltage of the fourth power supply circuit 12d is greater than the predetermined voltage threshold, the process of step S31 is repeated.

[0129] In step S32, the control device 34 ends the first power reduction control for the second power electronics device 14b. Thereafter, the fail-safe control is ended. Note that the processing of step S31 may be omitted, and the first power reduction control may be ended after a predetermined time threshold has elapsed from the time point at which the second connection control is executed. If the second power electronics device 14b is controlled by a control device other than the control device 34, the other control device may end the first power reduction control for the second power electronics device 14b.

[0130] If it is determined in step S27 that power is being supplied from the second power converter 14b to the second load device 16b (step S27: NO), the process proceeds to step S33.

[0131] In step S33, the control device 34 determines whether the supply of power from the first power conversion device 14a to the third load device 16c has been stopped. If it is determined that the supply of power from the first power conversion device 14a to the third load device 16c has been stopped (step S33: YES), the control device 34 proceeds to step S34.

[0132] In step S34, the control device 34 controls the breaker device 22c to break the first power converter 14a from the third power supply circuit 12c and the second connection circuit 18b, and then proceeds to step S35.

[0133] In step S35, the control device 34 executes the second power reduction control on the first power conversion device 14a. This reduces the power output from the first power conversion device 14a. Then, the process proceeds to step S36. If the first power conversion device 14a is controlled by a control device other than the control device 34, the other control device may execute the second power reduction control on the first power conversion device 14a.

[0134] In step S36, the control device 34 executes the first connection control for the first connection device 20a. As a result, the first power supply circuit 12a and the second power supply circuit 12b are connected via the first connection circuit 18a. Then, the process proceeds to step S37.

[0135] In step S37, the control device 34 determines whether the difference between the voltage of the first power supply circuit 12a and the voltage of the second power supply circuit 12b is equal to or less than a predetermined voltage threshold. If it is determined that the difference between the voltage of the first power supply circuit 12a and the voltage of the second power supply circuit 12b is equal to or less than the predetermined voltage threshold, the process proceeds to step S38. If it is determined that the difference between the voltage of the first power supply circuit 12a and the voltage of the second power supply circuit 12b is greater than the predetermined voltage threshold, the process of step S37 is repeated.

[0136] In step S38, the control device 34 ends the second power reduction control for the first power electronics device 14a. Thereafter, the fail-safe control is ended. Note that the processing of step S37 may be omitted, and the second power reduction control may be ended after a predetermined time threshold has elapsed from the time point at which the first connection control was executed. If the first power electronics device 14a is controlled by a control device other than the control device 34, the other control device may end the second power reduction control for the first power electronics device 14a.

[0137] If it is determined in step S33 that power is being supplied from the first power converter 14a to the third load device 16c (step S33: NO), the process proceeds to step S39.

[0138] In step S39, the control device 34 determines whether the supply of power from the second power conversion device 14b to the fourth load device 16d has been stopped. If it is determined that the supply of power from the second power conversion device 14b to the fourth load device 16d has been stopped (step S39: YES), the control device 34 proceeds to step S40. If it is determined that power is being supplied from the second power conversion device 14b to the fourth load device 16d (step S39: NO), the fail-safe control is terminated.

[0139] In step S40, the control device 34 controls the breaker device 22d to break the second power converter 14b from the fourth power supply circuit 12d and the second connection circuit 18b, and then proceeds to step S41.

[0140] In step S41, the control device 34 executes the first power reduction control on the second power conversion device 14b. This reduces the power output from the second power conversion device 14b. Then, the process proceeds to step S42. If the second power conversion device 14b is controlled by a control device other than the control device 34, the other control device may execute the first power reduction control on the second power conversion device 14b.

[0141] In step S42, the control device 34 executes the first connection control for the first connection device 20a. As a result, the first power supply circuit 12a and the second power supply circuit 12b are connected via the first connection circuit 18a. Then, the process proceeds to step S43.

[0142] In step S43, the control device 34 determines whether the difference between the voltage of the first power supply circuit 12a and the voltage of the second power supply circuit 12b is equal to or less than a predetermined voltage threshold. If it is determined that the difference between the voltage of the first power supply circuit 12a and the voltage of the second power supply circuit 12b is equal to or less than the predetermined voltage threshold, the process proceeds to step S44. If it is determined that the difference between the voltage of the first power supply circuit 12a and the voltage of the second power supply circuit 12b is greater than the predetermined voltage threshold, the process of step S43 is repeated.

[0143] In step S44, the control device 34 ends the first power reduction control for the second power electronics device 14b. Thereafter, the fail-safe control is ended. Note that the processing of step S43 may be omitted, and the first power reduction control may be ended after a predetermined time threshold has elapsed from the time point at which the first connection control was executed. If the second power electronics device 14b is controlled by a control device other than the control device 34, the other control device may end the first power reduction control for the second power electronics device 14b.

[0144] It should be noted that both the fail-safe control of this embodiment and the fail-safe control of the first embodiment may be performed.

[0145] Third Embodiment 27 is a schematic diagram of a moving object 44 according to the third embodiment. The power supply system 10 is mounted on the moving object 44.

[0146] The moving body 44 of this embodiment is an electric vertical take-off and landing aircraft (eVTOL). The moving body 44 includes eight VTOL rotors 46. The VTOL rotors 46 generate thrust in the upward direction relative to the airframe 48. The moving body 44 includes eight electric motors 50. Each electric motor 50 drives one VTOL rotor 46. The moving body 44 has two cruise rotors 52. The cruise rotors 52 generate thrust in the forward direction relative to the airframe 48. The moving body 44 includes four electric motors 54. Each electric motor 54 drives one cruise rotor 52.

[0147] Each of the first load device 16a, the second load device 16b, the third load device 16c, and the fourth load device 16d may include two electric motors 50 and one electric motor 54. Each of the first load device 16a, the second load device 16b, the third load device 16c, and the fourth load device 16d may include a low-voltage drive device in addition to the electric motor 50 and the electric motor 54.

[0148] The moving object 44 is not limited to an aircraft, but may be a ship, an automobile, a train, or the like.

[0149] The following additional notes are further disclosed regarding the above embodiment.

[0150] (Appendix 1) A power supply system (10) of the present disclosure includes a first power generating device (15a) that outputs three-phase AC power, a second power generating device (15b) that outputs three-phase AC power, a first power conversion device (14a) that has a smoothing capacitor (21) and converts the three-phase AC power output from the first power generating device into DC power, a second power conversion device (14b) that has a smoothing capacitor and converts the three-phase AC power output from the second power generating device into DC power, a first power supply circuit (12a) that supplies the DC power output from the first power conversion device to a first load device (16a), a second power supply circuit (12b) that supplies the DC power output from the second power conversion device to a second load device (16b), and a power supply circuit (12c) that is connected in parallel with the first power generating device to the first power supply circuit. The power supply system includes a first power storage device (24a) connected in series with the second power generation device, a second power storage device (24b) connected in parallel with the second power generation device to the second power supply circuit, a first connection circuit (18a) including a first connection device (20a) capable of connecting the first power supply circuit and the second power supply circuit, and a control device (34) capable of executing first connection control on the first connection device to connect the first power supply circuit and the second power supply circuit, wherein, when the DC power output from the second power conversion device is supplied to the first load device, the control device executes the first connection control on the first connection device after executing first power reduction control on the second power conversion device to reduce the DC power output from the second power conversion device. With this configuration, when the control device executes the first connection control on the first connection device, it is possible to prevent an overcurrent from flowing between the first load device and the first power storage device, thereby preventing damage to the first load device and the first power storage device. This in turn contributes to energy efficiency.

[0151] (Appendix 2) In the power supply system described in Supplementary Note 1, the control device may execute the first power reduction control on the second power conversion device to short-circuit the output of the second power generation device in the second power conversion device. With this configuration, it is possible to reduce the DC power output from the second power conversion device.

[0152] (Appendix 3) The power supply system described in Supplementary Note 1 may further include a backflow prevention device (28b) that limits the supply of DC power from the second power storage device to the second power supply circuit. Such a configuration can suppress damage to the second power storage device.

[0153] (Appendix 4) In the power supply system described in Supplementary Note 1, the first power reduction control for the second power conversion device may be terminated after the first connection control for the first connection device is executed. With this configuration, the three-phase AC power of the second power generation device can be converted into DC power in the second power conversion device and supplied to the first load device.

[0154] (Appendix 5) In the power supply system described in Supplementary Note 4, the first power reduction control for the second power conversion device may be terminated when a difference between a voltage of the first power supply circuit and a voltage of the second power supply circuit becomes equal to or less than a predetermined voltage threshold after the first connection control is executed for the first connection device. With this configuration, the three-phase AC power of the second power generation device can be converted into DC power in the second power conversion device and supplied to the first load device.

[0155] (Appendix 6) In the power supply system described in Supplementary Note 4, the first power reduction control for the second power conversion device may be terminated when the elapsed time from the time the first connection control was executed for the first connection device becomes equal to or greater than a predetermined time threshold. With this configuration, the three-phase AC power of the second power generation device can be converted into DC power in the second power conversion device and supplied to the first load device.

[0156] (Appendix 7) In the power supply system described in Supplementary Note 1, there is provided a third power supply circuit (12c) that supplies the DC power output from the first power conversion device to a third load device (16c), a fourth power supply circuit (12d) that supplies the DC power output from the second power conversion device to a fourth load device (16d), a third power storage device (24c) that is connected in parallel with the first power generation device to the third power supply circuit, a fourth power storage device (24d) that is connected in parallel with the second power generation device to the fourth power supply circuit, a second connection circuit (18b) that is provided with a second connection device (20b) that can connect the third power supply circuit and the fourth power supply circuit, and a power supply circuit that is connected to the first power supply circuit and the first connection circuit. The power converter may further include a disconnecting device (22a) capable of disconnecting the first power generation device from the third power supply circuit and the fourth power supply circuit, and the control device may execute second connection control on the second connection device to connect the third power supply circuit and the fourth power supply circuit. When stopping the supply of DC power from the first power conversion device to the first load device, the control device may execute disconnection control on the disconnecting device to disconnect the first power conversion device from the first power supply circuit and the first connection circuit, and execute second power reduction control on the first power conversion device to reduce the DC power output from the first power conversion device, after which the control device executes the second connection control on the second connection device. With this configuration, when the control device executes the second connection control on the second connection device, it is possible to prevent overcurrent from flowing through the second power generation device, the second load device, the second power storage device, the fourth load device, and the fourth power storage device. Therefore, damage to the second power generation device, the second load device, the second power storage device, the fourth load device, and the fourth power storage device can be suppressed.

[0157] (Appendix 8) A moving body (44) of the present disclosure includes the power supply system described in any one of Supplementary Notes 1 to 7. With this configuration, when the control device executes the first connection control on the first connection device, it is possible to prevent an overcurrent from flowing through the first load device and the first power storage device. This makes it possible to prevent damage to the first load device and the first power storage device. This in turn contributes to energy efficiency.

[0158] (Appendix 9) The control method for a power supply system according to the present disclosure includes a first power generating device that outputs three-phase AC power, a second power generating device that outputs three-phase AC power, a first power conversion device having a smoothing capacitor and converting the three-phase AC power output from the first power generating device into DC power, a second power conversion device having a smoothing capacitor and converting the three-phase AC power output from the second power generating device into DC power, a first power supply circuit that supplies the DC power output from the first power conversion device to a first load device, a second power supply circuit that supplies the DC power output from the second power conversion device to a second load device, and a control method for a power supply system including a first power storage device connected in parallel to the second power generation device, a second power storage device connected in parallel to the second power generation device, and a first connection circuit including a first connection device capable of connecting the first power supply circuit and the second power supply circuit, wherein, when the DC power output from the second power conversion device is supplied to the first load device, a first power reduction control for reducing the DC power output from the second power conversion device is executed on the second power conversion device, and then a first connection control for connecting the first power supply circuit and the second power supply circuit is executed on the first connection device. This makes it possible to suppress the occurrence of overcurrent in the power supply system. With this configuration, when the control device executes the first connection control on the first connection device, it is possible to suppress the flow of overcurrent between the first load device and the first power storage device. Therefore, it is possible to suppress damage to the first load device and the first power storage device. This ultimately contributes to energy efficiency.

[0159] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values or mathematical expressions are used in the description of the above-described embodiments. [Explanation of symbols]

[0160] 10... Power supply system 12a... First power supply circuit 12b...Second power supply circuit 12c...Third power supply circuit 12d...Fourth power supply circuit 14a...First power conversion device 14b... Second power conversion device 15a... First power generation device 15b... Second power generating device 16a... First load device 16b...Second load device 16c...Third load device 16d...Fourth load device 18a...First connection circuit 18b... Second connection circuit 20a... First connection device 20b... Second connection device 21... Smoothing capacitor 22a to 22d... Circuit breaker 24a... First power storage device 24b...Second power storage device 24c...Third power storage device 24d...Fourth storage device 26a-26d...Breaker 28a to 28d... Backflow prevention device 34... Control device 44...Mobile

Claims

1. a first power generating device that outputs three-phase AC power; a second power generating device that outputs three-phase AC power; a first power conversion device having a smoothing capacitor and converting the three-phase AC power output from the first power generation device into DC power; a second power conversion device having a smoothing capacitor and converting the three-phase AC power output from the second power generation device into DC power; a first power supply circuit that supplies the DC power output from the first power conversion device to a first load device; a second power supply circuit that supplies the DC power output from the second power conversion device to a second load device; a first power storage device connected in parallel with the first power generation device to the first power supply circuit; a second power storage device connected in parallel with the second power generation device to the second power supply circuit; a first connection circuit including a first connection device that can connect the first power supply circuit and the second power supply circuit; a control device capable of executing a first connection control for connecting the first power supply circuit and the second power supply circuit to the first connection device; Equipped with A power supply system in which, when the DC power output from the second power conversion device is supplied to the first load device, first power reduction control that reduces the DC power output from the second power conversion device is executed on the second power conversion device, and then the control device executes the first connection control on the first connection device.

2. 2. The power supply system according to claim 1, The power supply system wherein the first power reduction control is executed on the second power conversion device, thereby short-circuiting the output of the second power generation device in the second power conversion device.

3. 2. The power supply system according to claim 1, The power supply system further comprises a backflow prevention device that limits the supply of the DC power from the second power storage device to the second power supply circuit.

4. 2. The power supply system according to claim 1, a power supply system in which the first power reduction control for the second power conversion device is terminated after the first connection control is executed for the first connection device;

5. 5. The power supply system according to claim 4, a power supply system in which, after the first connection control is executed for the first connection device, when a difference between a voltage of the first power supply circuit and a voltage of the second power supply circuit becomes equal to or less than a predetermined voltage threshold, the first power reduction control for the second power conversion device is terminated.

6. 5. The power supply system according to claim 4, A power supply system in which the first power reduction control for the second power conversion device is terminated when the elapsed time from the time the first connection control was executed for the first connection device becomes equal to or greater than a predetermined time threshold.

7. 2. The power supply system according to claim 1, a third power supply circuit that supplies the DC power output from the first power conversion device to a third load device; a fourth power supply circuit that supplies the DC power output from the second power conversion device to a fourth load device; a third power storage device connected in parallel to the first power generation device to the third power supply circuit; a fourth power storage device connected in parallel to the second power generation device to the fourth power supply circuit; a second connection circuit including a second connection device that can connect the third power supply circuit and the fourth power supply circuit; a disconnection device that can disconnect the first power generation device from the first power supply circuit and the first connection circuit; Further provided with the control device is capable of executing second connection control on the second connection device to connect the third power supply circuit and the fourth power supply circuit; A power supply system in which, when the supply of DC power from the first power conversion device to the first load device is stopped, a disconnection control is executed on the disconnection device to disconnect the first power conversion device from the first power supply circuit and the first connection circuit, and after a second power reduction control is executed on the first power conversion device to reduce the DC power output from the first power conversion device, the control device executes the second connection control on the second connection device.

8. A mobile object comprising the power supply system according to any one of claims 1 to 7.

9. a first power generating device that outputs three-phase AC power; a second power generating device that outputs three-phase AC power; a first power conversion device having a smoothing capacitor and converting the three-phase AC power output from the first power generation device into DC power; a second power conversion device having a smoothing capacitor and converting the three-phase AC power output from the second power generation device into DC power; a first power supply circuit that supplies the DC power output from the first power conversion device to a first load device; a second power supply circuit that supplies the DC power output from the second power conversion device to a second load device; a first power storage device connected in parallel with the first power generation device to the first power supply circuit; a second power storage device connected in parallel with the second power generation device to the second power supply circuit; a first connection circuit including a first connection device that can connect the first power supply circuit and the second power supply circuit; A control method for a power supply system comprising: A control method for a power supply system, wherein, when the DC power output from the second power conversion device is supplied to the first load device, first power reduction control that reduces the DC power output from the second power conversion device is executed on the second power conversion device, and then first connection control that connects the first power supply circuit and the second power supply circuit is executed on the first connection device.

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