Power supply system
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- HONDA MOTOR CO LTD
- Filing Date
- 2024-12-25
- Publication Date
- 2026-07-07
Smart Images
Figure 2026112630000001_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a power supply system.
Background Art
[0002] Japanese Patent Application Laid-Open No. 2016-123141 discloses a technique for dealing with a short-circuit fault occurring in an inverter in a motor system composed of an inverter and a three-phase AC motor.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] A power supply system is used that converts polyphase AC power output from a generator into DC power by a power conversion circuit (for example, a converter) and outputs it. In such a power supply system, it is desirable to perform suitable control when a short-circuit fault occurs in the power conversion circuit.
[0005] The present disclosure aims to solve the above-described problems.
Means for Solving the Problems
[0006] An aspect of the present disclosure is a power supply system comprising: a converter that includes a plurality of switching elements and converts a multiphase AC voltage output from a generator into a DC voltage; a control unit that controls the converter; and a determination unit that determines whether or not a short-circuit fault has occurred in any of the plurality of switching elements provided in the converter, wherein the converter includes a plurality of switching element sections corresponding to each phase of the multiphase AC voltage, in which upper arm-side switching elements, which are the switching elements on the upper arm side, and lower arm-side switching elements, which are the switching elements on the lower arm side, are connected in series with each other, and when the determination unit determines that a short-circuit fault has occurred in any of the plurality of switching elements provided in the converter, the control unit can perform a first control to turn on all of the switching elements provided in the converter. [Effects of the Invention]
[0007] According to this disclosure, suitable control can be performed when a short-circuit fault occurs in the power conversion circuit. [Brief explanation of the drawing]
[0008] [Figure 1] Figure 1 is a schematic diagram of a power supply system according to one embodiment. [Figure 2] Figure 2 is a schematic diagram of a first power generation device according to one embodiment. [Figure 3] Figure 3 is a schematic diagram showing an example of a backflow prevention device in one embodiment. [Figure 4] Figure 4 is a schematic diagram showing another example of a backflow prevention device in one embodiment. [Figure 5] Figure 5 is a control block diagram of a control device in one embodiment. [Figure 6] Figure 6 shows the operation of a power supply system under normal conditions in one embodiment. [Figure 7] Figure 7 is a flowchart of the process for dealing with a short-circuit fault. [Figure 8]Figure 8A shows the phase currents supplied from the first generator to the first converter. Figure 8B shows the current flowing to the upper arm side of the first converter in one embodiment. Figure 8C shows the current flowing to the lower arm side of the first converter in one embodiment. Figure 8D shows the switch signal in one embodiment. [Figure 9] Figure 9 shows the operation of the first converter in one embodiment. [Figure 10] Figure 10A shows the phase currents supplied from the first generator to the first converter in the comparative example. Figure 10B shows the current flowing to the upper arm side of the first converter in the comparative example. Figure 10C shows the current flowing to the lower arm side of the first converter in the comparative example. Figure 10D shows the switch signal in the comparative example. [Figure 11] Figure 11 shows the operation of the first converter in one embodiment. [Figure 12] Figure 12 is a flowchart of the process for suppressing temperature differences between multiple switching elements. [Figure 13] Figure 13 is a flowchart of the process for transitioning from the second control to the first control. [Figure 14] Figure 14 is a schematic diagram of the moving object. [Modes for carrying out the invention]
[0009] A converter that converts multiphase AC power (voltage, current) to DC power (voltage, current) includes separate switching element sections for each phase of the multiphase AC power. Each switching element section includes an upper arm switching element and a lower arm switching element connected in series with each other.
[0010] In such a converter, if a short-circuit failure (on-lock failure) occurs in any of the switching elements, problems such as overheating and demagnetization of the generator supplying multiphase AC power to the converter will occur. To avoid these problems, one option is to turn on all the switching elements belonging to the arm containing the short-circuit failure. For example, if a short-circuit failure occurs in any of the switching elements on the upper arm, controlling all the switching elements on the upper arm to be constantly on can reduce the increase in generator heat generation and the demagnetization of the generator.
[0011] However, simply keeping the switching element constantly on leads to another problem: the switching element becomes overheated. This disclosure provides a power supply system that can suppress the temperature rise of the switching element provided in a converter.
[0012] [Configuration of power supply system 10] Figure 1 is a schematic diagram of a power supply system 10 according to one embodiment. As shown in Figure 1, 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. The first power supply circuit 12a supplies DC power output from the first power generator 14a to the first load device 16a. The second power supply circuit 12b supplies DC power output from the second power generator 14b to the second load device 16b. The third power supply circuit 12c supplies DC power output from the first power generator 14a to the third load device 16c. The fourth power supply circuit 12d supplies DC power output from the second power generator 14b to the fourth load device 16d.
[0013] The power supply system 10 includes a first power generation device 14a and a second power generation device 14b. The first power generation device 14a includes a first engine 18a, a first generator 20a, and a first converter 22a. The second power generation device 14b includes a second engine 18b, a second generator 20b, and a second converter 22b. The first engine 18a and the second engine 18b are, for example, gas turbine engines. Note that the first engine 18a and the second engine 18b may be other engines such as reciprocating engines. The first generator 20a is driven by the first engine 18a and generates three-phase AC power. The first converter 22a converts the three-phase AC power output from the first generator 20a into DC power. The second generator 20b is driven by the second engine 18b and generates three-phase AC power. The second converter 22b converts the three-phase AC power output from the second generator 20b into DC power.
[0014] Figure 2 is a schematic diagram of the first power generation device 14a of an embodiment. The configuration of the second power generation device 14b is the same as that of the first power generation device 14a. As shown in FIG. 2, the first converter 22a provided in the first power generation device 14a includes switching element units 24U, 24V, and 24W corresponding to each of the three-phase voltages output from the first generator 20a, and a smoothing capacitor 26. The configurations of the switching element units 24V and 24W are the same as that of the switching element unit 24U.
[0015] The switching element section 24U has an upper arm 28 and a lower arm 30. The upper arm 28 has a switching element (upper arm side switching element) 32 (32Uu, 32Vu, 32Wu) and a diode 34 (34Uu, 34Vu, 34Wu). The lower arm 30 has a switching element (lower arm side switching element) 32 (32Ud, 32Vd, 32Wd) and a diode 34 (34Ud, 34Vd, 34Wd). For example, in the switching element section 24U, the switching element 32Uu and the switching element 32Ud are connected in series with each other. That is, the first end of the switching element 32Uu is connected to the positive wiring of the first converter 22a. The second end of the switching element 32Uu is connected to the first end of the switching element 32Ud. The second end of the switching element 32Ud is connected to the negative wiring of the first converter 22a. The second end of the switching element 32Uu and the first end of the switching element 32Ud are connected to the terminal of the first phase (for example, U phase) of the first generator 20a. The anode of the diode 34Uu is connected to the second end of the switching element 32Uu. The cathode of the diode 34Uu is connected to the first end of the switching element 32Uu. The anode of the diode 34Ud is connected to the second end of the switching element 32Ud. The cathode of the diode 34Ud is connected to the first end of the switching element 32Ud.
[0016] In addition, in the switching element section 24V, the second end of the switching element 32Vu and the first end of the switching element 32Vd are connected to the terminal of the second phase (for example, V phase) of the first generator 20a. In the switching element section 24W, the second end of the switching element 32Wu and the first end of the switching element 32Wd are connected to the terminal of the third phase (for example, W phase) of the first generator 20a.
[0017] Each switching element 32 is a semiconductor switch (power device) such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor).
[0018] In the first converter 22a, the timing of the on and off states of each switching element 32 is controlled to rectify the three-phase AC power output from the first generator 20a and convert it into DC power. The rectified DC power has its voltage fluctuations suppressed by the smoothing capacitor 26, and a stable voltage DC power is output from the first converter 22a. When the first generator 20a starts up, the smoothing capacitor 26 needs to be charged in advance.
[0019] Each upper arm 28 is equipped with a short-circuit sensor (voltage sensor or current sensor) 40 for detecting short-circuit failures of the switching element 32. Similarly, each lower arm 30 is equipped with a short-circuit sensor 40 for detecting short-circuit failures of the switching element 32.
[0020] Each upper arm 28 is equipped with a temperature sensor 42 for detecting the temperature of the switching element 32. Similarly, each lower arm 30 is equipped with a temperature sensor 42 for detecting the temperature of the switching element 32.
[0021] The first converter 22a and the second converter 22b may also have other elements such as sensors, fuses, relays, circuit breakers, diodes, transistors, resistors, coils, and capacitors.
[0022] As shown in Figure 1, the power supply system 10 includes a first load device 16a, a second load device 16b, a third load device 16c, and a fourth load device 16d. The first load device 16a, the second load device 16b, the third load device 16c, and the fourth load device 16d each have, for example, an inverter and an electric motor (see, for example, electric motors 86 and 90 in Figure 14). The inverter converts the 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, second load device 16b, third load device 16c, and fourth load device 16d may have various sensors such as voltage sensors and current sensors, fuses, relays, circuit breakers, diodes, transistors, resistors, coils, and capacitors. Multiple first load devices 16a may be connected in parallel to each other in the first power supply circuit 12a. Multiple second load devices 16b may be connected in parallel to each other in the second power supply circuit 12b. Multiple third load devices 16c may be connected in parallel to each other in the third power supply circuit 12c. Multiple fourth load devices 16d may be connected in parallel to each other in the fourth power supply circuit 12d.
[0024] The power supply system 10 includes connection circuits 44a and 44b. Connection circuit 44a is equipped with a connection device 46a. Connection circuit 44b is equipped with a connection device 46b.
[0025] The connection device 46a can connect the first power supply circuit 12a and the second power supply circuit 12b. The connection device 46a switches 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 by a contactor (not shown).
[0026] Similarly, the connection device 46b can connect the third power supply circuit 12c and the fourth power supply circuit 12d. The connection device 46b switches 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 by a contactor (not shown).
[0027] The connecting devices 46a and 46b may have relays instead of contactors. The connecting devices 46a and 46b may have circuit breakers instead of contactors. The connecting devices 46a and 46b may have semiconductor switches instead of contactors.
[0028] Normally, the first power supply circuit 12a and the second power supply circuit 12b are disconnected. This prevents an abnormality in one of the power supply circuits from affecting the other. For example, if an overcurrent occurs in one of the power supply circuits, it prevents the overcurrent from flowing to the other.
[0029] Similarly, the third power supply circuit 12c and the fourth power supply circuit 12d are normally disconnected. This prevents an abnormality in one of the third power supply circuit 12c and the fourth power supply circuit 12d from affecting the other. For example, if an overcurrent occurs in one of the third power supply circuit 12c and the fourth power supply circuit 12d, it prevents the overcurrent from flowing to the other.
[0030] If a malfunction occurs in the power supply from the first power generator 14a to the first power supply circuit 12a, the connection device 46a connects the first power supply circuit 12a and the second power supply circuit 12b. As a result, power is supplied from the second power supply circuit 12b to the first power supply circuit 12a.
[0031] If a malfunction occurs in the power supply from the first power generator 14a to the third power supply circuit 12c, the connection device 46b connects the third power supply circuit 12c and the fourth power supply circuit 12d. As a result, power is supplied from the fourth power supply circuit 12d to the third power supply circuit 12c.
[0032] If a malfunction occurs in the power supply from the second power generator 14b to the second power supply circuit 12b, the connection device 46a connects the first power supply circuit 12a and the second power supply circuit 12b. This allows power to be supplied from the first power supply circuit 12a to the second power supply circuit 12b.
[0033] If a malfunction occurs in the power supply from the second power generator 14b to the fourth power supply circuit 12d, the connection device 46b connects the third power supply circuit 12c and the fourth power supply circuit 12d. This allows power to be supplied from the third power supply circuit 12c to the fourth power supply circuit 12d.
[0034] The power supply system 10 includes circuit breakers 48a to 48d. Circuit breaker 48a can disconnect the first power generator 14a from the first power supply circuit 12a and the connection circuit 44a. Circuit breaker 48b can disconnect the second power generator 14b from the second power supply circuit 12b and the connection circuit 44a. Circuit breaker 48c can disconnect the first power generator 14a from the third power supply circuit 12c and the connection circuit 44b. Circuit breaker 48d can disconnect the second power generator 14b from the fourth power supply circuit 12d and the connection circuit 44b.
[0035] The circuit breaker 48a switches between a state in which the first power generator 14a is disconnected from the first power supply circuit 12a and the connection circuit 44a, and a state in which the first power generator 14a is connected to the first power supply circuit 12a and the connection circuit 44a, using a contactor (not shown). Similarly, the circuit breaker 48b switches between a state in which the second power generator 14b is disconnected from the second power supply circuit 12b and the connection circuit 44a, and a state in which the second power generator 14b is connected to the second power supply circuit 12b and the connection circuit 44a, using a contactor (not shown).
[0036] Furthermore, the circuit breaker 48c switches between a state in which the first power generator 14a is disconnected from the third power supply circuit 12c and the connection circuit 44b, and a state in which the first power generator 14a is connected to the third power supply circuit 12c and the connection circuit 44b, using a contactor (not shown). Similarly, the circuit breaker 48d switches between a state in which the second power generator 14b is disconnected from the fourth power supply circuit 12d and the connection circuit 44b, and a state in which the second power generator 14b is connected to the fourth power supply circuit 12d and the connection circuit 44b, using a contactor (not shown).
[0037] The circuit breakers 48a to 48d may have relays instead of contactors. The circuit breakers 48a to 48d may have circuit breakers instead of contactors. The circuit breakers 48a to 48d may have semiconductor switches instead of contactors.
[0038] The power supply system 10 includes a first energy storage device 50a, a second energy storage device 50b, a third energy storage device 50c, and a fourth energy storage device 50d. The first energy storage device 50a is connected in parallel to the first power supply circuit 12a with respect to the first power generator 14a. The second energy storage device 50b is connected in parallel to the second power supply circuit 12b with respect to the second power generator 14b. The third energy storage device 50c is connected in parallel to the third power supply circuit 12c with respect to the first power generator 14a. The fourth energy storage device 50d is connected in parallel to the fourth power supply circuit 12d with respect to the second power generator 14b.
[0039] The first energy storage device 50a, the second energy storage device 50b, the third energy storage device 50c, and the fourth energy storage device 50d each have a lithium-ion battery. The first energy storage device 50a, the second energy storage device 50b, the third energy storage device 50c, and the fourth energy storage device 50d may also have a secondary battery other than a lithium-ion battery. The first energy storage device 50a, the second energy storage device 50b, the third energy storage device 50c, and the fourth energy storage device 50d may also have a large-capacity capacitor.
[0040] The first energy storage device 50a, the second energy storage device 50b, the third energy storage device 50c, and the fourth energy storage device 50d may have various sensors such as voltage sensors and current sensors, and various elements such as fuses, relays, circuit breakers, diodes, transistors, resistors, coils, and capacitors.
[0041] The power supply system 10 includes circuit breakers 52a to 52d. Circuit breaker 52a can disconnect the first energy storage device 50a from the first power supply circuit 12a and the first load device 16a. Circuit breaker 52b can disconnect the second energy storage device 50b from the second power supply circuit 12b and the second load device 16b. Circuit breaker 52c can disconnect the third energy storage device 50c from the third power supply circuit 12c and the third load device 16c. Circuit breaker 52d can disconnect the fourth energy storage device 50d from the fourth power supply circuit 12d and the fourth load device 16d.
[0042] The circuit breaker 52a, using a contactor (not shown), switches between a state in which the first energy storage device 50a is disconnected from the first power supply circuit 12a and the first load device 16a, and a state in which the first energy storage device 50a is connected to the first power supply circuit 12a and the first load device 16a. Similarly, the circuit breaker 52b, using a contactor (not shown), switches between a state in which the second energy storage device 50b is disconnected from the second power supply circuit 12b and the second load device 16b, and a state in which the second energy storage device 50b is connected to the second power supply circuit 12b and the second load device 16b.
[0043] Furthermore, the circuit breaker 52c switches between a state in which the third energy storage device 50c is disconnected from the third power supply circuit 12c and the third load device 16c, and a state in which the third energy storage device 50c is connected to the third power supply circuit 12c and the third load device 16c, using a contactor (not shown). Similarly, the circuit breaker 52d switches between a state in which the fourth energy storage device 50d is disconnected from the fourth power supply circuit 12d and the fourth load device 16d, and a state in which the fourth energy storage device 50d is connected to the fourth power supply circuit 12d and the fourth load device 16d, using a contactor (not shown).
[0044] The circuit breakers 52a to 52d may have relays instead of contactors. The circuit breakers 52a to 52d may have circuit breakers instead of contactors. The circuit breakers 52a to 52d may have semiconductor switches instead of contactors.
[0045] The power supply system 10 is equipped with reverse current prevention devices 54a to 54d. Reverse current prevention device 54a restricts the supply of power from the first energy storage device 50a to the first power supply circuit 12a and the first power generator 14a. Reverse current prevention device 54b restricts the supply of power from the second energy storage device 50b to the second power supply circuit 12b and the second power generator 14b. Reverse current prevention device 54c restricts the supply of power from the third energy storage device 50c to the third power supply circuit 12c and the first power generator 14a. Reverse current prevention device 54d restricts the supply of power from the fourth energy storage device 50d to the fourth power supply circuit 12d and the second power generator 14b.
[0046] Figure 3 is a schematic diagram showing an example of a reverse current prevention device 54a in one embodiment. As shown in Figure 3, the configurations of the reverse current prevention devices 54b to 54d are the same as the configuration of the reverse current prevention device 54a. The reverse current prevention device (blocking section) 54a includes, for example, a diode 56 and a transistor 58.
[0047] Diode 56 is provided in the positive terminal wiring. When the anode voltage is lower than the cathode voltage, diode 56 conducts almost no current. When the anode voltage becomes higher than the forward voltage relative to the cathode voltage, current flows through diode 56. As a result, power is supplied from the first power generator 14a to the first load device 16a and the first energy storage device 50a via diode 56. On the other hand, power is not supplied from the first load device 16a and the first energy storage device 50a to the first power generator 14a via diode 56.
[0048] Transistor 58 is provided by bypassing diode 56. When current flows from the base to the emitter of transistor 58, current flows from the collector to the emitter. This supplies power from the first energy storage device 50a to the first power generator 14a via the first power supply circuit 12a. Diode 56 may be provided in the negative terminal wiring. Alternatively, diode 56 may be provided in both the positive terminal wiring and the negative terminal wiring.
[0049] Furthermore, the reverse current prevention device 54a may be provided with a diode 56, but not with a transistor 58. Also, as shown in Figure 4, the reverse current prevention device 54a may include a switching device such as a contactor 60 that switches between connection and disconnection in response to a switching signal from the control unit 68. The contactor 60 is provided on at least one of the positive terminal wiring and the negative terminal wiring.
[0050] In addition to the configuration described above, the power supply system 10 may also include various sensors such as voltage sensors and current sensors, as well as elements such as fuses, resistors, coils, and capacitors.
[0051] Figure 5 is a control block diagram of the control device 62 in one embodiment. The power supply system 10 includes the control device 62. The control device 62 controls the first converter 22a, the second converter 22b, the connection devices 46a, 46b, the circuit breakers 48a to 48d, the circuit breakers 52a to 52d, and the reverse current prevention devices 54a to 54d.
[0052] The control device 62 includes an arithmetic unit 64 and a storage unit 66. The arithmetic unit 64 is, for example, a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). The arithmetic unit 64 includes a control unit 68, a determination unit 70, and a temperature detection unit 72. The control unit 68, the determination unit 70, and the temperature detection unit 72 are realized by the execution of a program stored in the storage unit 66 in the arithmetic unit 64. At least a portion of the control unit 68, the determination unit 70, and the temperature detection unit 72 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 portion of the control unit 68, the determination unit 70, and the temperature detection unit 72 may be realized by an electronic circuit including discrete devices.
[0053] The storage unit 66 is a computer-readable, non-transient, tangible storage medium. The storage unit 66 is composed of volatile memory (not shown) and non-volatile memory (not shown). The volatile memory is, for example, RAM (Random Access Memory). The non-volatile memory is, for example, ROM (Read Only Memory), flash memory, etc. Data is stored in the volatile memory, for example. Programs, tables, maps, etc. are stored in the non-volatile memory, for example. At least a part of the storage unit 66 may be provided in the processor, integrated circuit, etc. mentioned above.
[0054] The control unit 68 controls the first converter 22a and the second converter 22b. Specifically, the control unit 68 controls the switching of each of the multiple switching elements 32 provided in the first converter 22a. The control unit 68 controls the second converter 22b in the same manner.
[0055] The determination unit 70 determines whether a short-circuit fault has occurred in any of the multiple switching elements 32 provided in the first converter 22a, based on signals supplied from each of the multiple short-circuit sensors 40 provided in the first converter 22a. Similarly, the determination unit 70 determines whether a short-circuit fault has occurred in any of the multiple switching elements 32 provided in the second converter 22b.
[0056] The temperature detection unit 72 detects the temperature of each of the multiple switching elements 32 provided in the first converter 22a based on signals supplied from each of the multiple temperature sensors 42 provided in the first converter 22a. Similarly, the temperature detection unit 72 detects the temperature of each of the multiple switching elements 32 in the second converter 22b.
[0057] [Operation of power supply system 10] Figure 6 shows the operation of the power supply system 10 under normal conditions in one embodiment. The arrows shown in Figure 6 indicate the power supply path.
[0058] As shown in Figure 6, the first power generator 14a is connected to the first power supply circuit 12a by the circuit breaker 48a, and the first power generator 14a is connected to the third power supply circuit 12c by the circuit breaker 48c. As a result, the three-phase AC power output from the first generator 20a is converted to DC power in the first converter 22a and supplied to the first load device 16a and the third load device 16c.
[0059] The circuit breaker 48b connects the second generator 14b to the second power supply circuit 12b, and the circuit breaker 48d connects the second generator 14b to the fourth power supply circuit 12d. As a result, the three-phase AC power output from the second generator 20b is converted to DC power in the second converter 22b and supplied to the second load device 16b and the fourth load device 16d.
[0060] The circuit breaker 52a connects the first energy storage device 50a to the first load device 16a. As a result, the DC power output from the first energy storage device 50a is supplied to the first load device 16a. The circuit breaker 52b connects the second energy storage device 50b to the second load device 16b. As a result, the DC power output from the second energy storage device 50b is supplied to the second load device 16b. The circuit breaker 52c connects the third energy storage device 50c to the third load device 16c. As a result, the DC power output from the third energy storage device 50c is supplied to the third load device 16c. The circuit breaker 52d connects the fourth energy storage device 50d to the fourth load device 16d. As a result, the DC power output from the fourth energy storage device 50d is supplied to the fourth load device 16d.
[0061] Under normal conditions, the connection device 46a disconnects the first power supply circuit 12a and the second power supply circuit 12b, and the connection device 46b disconnects the third power supply circuit 12c and the fourth power supply circuit 12d.
[0062] In the event of a malfunction in the first power generator 14a or the second power generator 14b, the first power supply circuit 12a and the second power supply circuit 12b may be connected by the connecting device 46a. Similarly, in the event of a malfunction in the first power generator 14a or the second power generator 14b, the third power supply circuit 12c and the fourth power supply circuit 12d may be connected by the connecting device 46b. As a result, the three-phase AC power output from the first generator 20a can be converted to DC power in the first converter 22a and supplied to the second load device 16b and the fourth load device 16d. Alternatively, the three-phase AC power output from the second generator 20b can be converted to DC power in the second converter 22b and supplied to the first load device 16a and the third load device 16c.
[0063] [Processing to address short-circuit faults] Figure 7 is a flowchart of the process for responding to a short-circuit fault. The arithmetic unit 64 provided in the control device 62 executes the process shown in Figure 7. The process performed with respect to the first converter 22a will be described below, but the process performed with respect to the second converter 22b is carried out in the same manner.
[0064] If a short-circuit failure occurs in any of the switching elements 32 in the first converter 22a, problems such as an increase in the heat generated by the first generator 20a and demagnetization of the first generator 20a will occur. To avoid such problems, the control unit 68 of this embodiment performs the first control described below.
[0065] In step S1, the determination unit 70 acquires signals from each of the short-circuit sensors 40 provided in the first converter 22a. For example, if each of the short-circuit sensors 40 is a voltage sensor, the determination unit 70 acquires a signal indicating the voltage between the input and output terminals of the switching element 32. For example, if each of the short-circuit sensors 40 is a current sensor, the determination unit 70 acquires a signal indicating the current flowing through the switching element 32.
[0066] In step S2, the determination unit 70 determines whether a short-circuit fault has occurred in any of the multiple switching elements 32 based on the signals supplied from each of the short-circuit sensors 40. For example, the determination unit 70 determines that a short-circuit fault has occurred if it detects a switching element 32 that is conducting despite not outputting an ON signal indicating an ON state. If a short-circuit fault has occurred in at least one of the multiple switching elements 32 (step S2: YES), the process proceeds to step S3. On the other hand, if no short-circuit fault has occurred in any of the multiple switching elements 32 (step S2: NO), the process returns to step S1.
[0067] When the process moves from step S2 to step S3, the control unit 68 turns on all the switching elements 32. The control performed by the control unit 68 in step S3 is called the first control. The first control will be explained using Figures 8A to 8D and Figure 9.
[0068] Figure 8A shows the phase currents supplied from the first generator 20a to the first converter 22a. Figure 8B shows the current flowing to the upper arm 28 side of the first converter 22a in one embodiment. Figure 8C shows the current flowing to the lower arm 30 side of the first converter 22a in one embodiment. Figure 8D shows the switch signal in one embodiment. Figure 9 shows the operation of the first converter 22a in one embodiment. Figure 9 shows the operation of the first converter 22a after a short-circuit fault occurs. The arrows in Figure 9 indicate the direction of current flow. The direction of current flow (arrows) and the amount of current change over time. Figure 9 shows the current flow at time t1 in Figures 8A to 8D.
[0069] When a short-circuit fault occurs, the control unit 68 continuously outputs an ON signal (voltage V1) to instruct all switching elements 32 to be ON, as shown in Figure 8D. In this state, the potential difference between the positive and negative terminals of the smoothing capacitor 26 provided in the first converter 22a becomes approximately zero. Therefore, the first power generator 14a does not supply power to the first power supply circuit 12a and the third power supply circuit 12c. Although the first power generator 14a is connected to the first energy storage device 50a via the first power supply circuit 12a, the supply of power (current) from the first energy storage device 50a to the first power generator 14a is blocked because the first power supply circuit 12a is equipped with a reverse current prevention device 54a. Similarly, the first power generator 14a is connected to the third energy storage device 50c via the third power supply circuit 12c, but since the third power supply circuit 12c is equipped with a reverse current prevention device 54c, the supply of power (current) from the third energy storage device 50c to the first power generator 14a is blocked.
[0070] When all switching elements 32 are turned on, a corresponding phase current flows continuously through all switching elements 32, as shown in Figure 9. The phase current supplied from the first generator 20a to the first converter 22a is divided between the upper arm 28 and the lower arm 30 in each switching element section 24U, 24V, and 24W. As shown in Figure 8B, in each switching element section 24U, 24V, and 24W, the phase current flowing through the switching element 32 of the upper arm 28 is reduced to about half of the phase current supplied from the first generator 20a to the first converter 22a. Similarly, as shown in Figure 8C, in each switching element section 24U, 24V, and 24W, the phase current flowing through the switching element 32 of the lower arm 30 is reduced to about half of the phase current supplied from the first generator 20a to the first converter 22a.
[0071] Here, a comparative example will be explained using Figures 10A to 10D and Figure 11. Similar to this embodiment, the comparative example is a technique to avoid problems such as increased heat generation and demagnetization of the first generator 20a caused by a short-circuit failure of any of the switching elements 32.
[0072] Figure 10A shows the phase currents supplied from the first generator 20a to the first converter 22a in the comparative example. Figure 10B shows the current flowing to the upper arm 28 side of the first converter 22a in the comparative example. Figure 10C shows the current flowing to the lower arm 30 side of the first converter 22a in the comparative example. Figure 10D shows the switch signal in the comparative example. Figure 11 shows the operation of the first converter 22a in one embodiment. Figure 11 shows the operation of the first converter 22a after a short-circuit fault occurs. The arrows shown in Figure 11 indicate the direction of current flow.
[0073] In the comparative example, we assume a case where a short-circuit failure occurs in the switching element 32 of any of the upper arms 28. In the comparative example, all the switching elements 32 of the upper arms 28 are turned ON, and all the switching elements 32 of the lower arms 30 are turned OFF.
[0074] When all the switching elements 32 on the upper arms 28 are turned ON, a corresponding phase current continuously flows through all the switching elements 32 on the upper arms 28, as shown in Figure 11. On the other hand, when all the switching elements 32 on the lower arms 30 are turned OFF, no phase current flows through all the switching elements 32 on the lower arms 30, as shown in Figure 11. In each switching element section 24U, 24V, and 24W, the phase current supplied from the first generator 20a to the first converter 22a is concentrated in the upper arms 28. As shown in Figures 10A and 10B, the phase current flowing through the switching elements 32 on each upper arm 28 is equal to the phase current supplied from the first generator 20a to the first converter 22a.
[0075] As can be seen from Figures 8B and 10B, according to this embodiment, if a short-circuit failure occurs in the switching element 32 of either upper arm 28, the increase in heat generation of the switching element 32 of the upper arm 28 can be suppressed compared to the comparative example. The same applies to the switching element 32 of the lower arm 30. That is, according to this embodiment, if a short-circuit failure occurs in the switching element 32 of either lower arm 30, the increase in heat generation of the switching element 32 of the lower arm 30 can be suppressed compared to the comparative example. As described above, according to this embodiment, the temperature rise of the switching element 32 can be suppressed.
[0076] [Processing to suppress temperature differences] Figure 12 is a flowchart of the process for suppressing the temperature difference between multiple switching elements 32. Due to individual differences, the rate of temperature rise of each of the multiple switching elements 32 may differ from one another. The calculation unit 64 provided in the control device 62 suppresses the temperature difference between the multiple switching elements 32 by executing the process shown in Figure 12 after the start of the execution of the first control (step S3) shown in Figure 7. The process performed with respect to the first converter 22a will be described below, but the process performed with respect to the second converter 22b is performed in the same manner.
[0077] In step S11, the temperature detection unit 72 acquires signals from each temperature sensor 42 provided in the first converter 22a.
[0078] In step S12, the temperature detection unit 72 compares the temperature T of each of the multiple switching elements 32 with a predetermined first temperature threshold Tth1. The first temperature threshold Tth1 is the upper limit of the allowable temperature of the switching elements 32. The first temperature threshold Tth1 is stored in advance in the storage unit 66. If the temperature T of at least one switching element 32 is greater than or equal to the first temperature threshold Tth1 (step S12: YES), the process proceeds to step S13. On the other hand, if the temperature T of all switching elements 32 is less than the first temperature threshold Tth1 (step S12: NO), the process returns to step S11.
[0079] When the system moves from step S12 to step S13, the control unit 68 turns off all switching elements 32 belonging to the arm that has the switching element 32 that has reached the first temperature threshold Tth1. The control performed by the control unit 68 in step S13 is referred to as the second control.
[0080] For example, if the temperature detection unit 72 detects that any of the switching elements 32 on the upper arm 28 has reached a first temperature threshold Tth1 or higher, the control unit 68 turns off all the switching elements 32 on the upper arm 28 while keeping all the switching elements 32 on the lower arm 30 in the ON state. As a result, the temperature of each switching element 32 that has been turned off decreases, while the temperature of each switching element 32 that remains ON increases. This suppresses the temperature difference between the switching elements 32 on the upper arm 28 and the switching elements 32 on the lower arm 30.
[0081] Similarly, when the temperature detection unit 72 detects that any of the switching elements 32 on the lower arms 30 have reached or exceeded the first temperature threshold Tth1, the control unit 68 turns off all the switching elements 32 on the lower arms 30 while keeping all the switching elements 32 on the upper arms 28 in the ON state. As a result, the temperature of each switching element 32 that has been turned OFF decreases, while the temperature of each switching element 32 that remains ON increases. This suppresses the temperature difference between the switching elements 32 on the upper arms 28 and the switching elements 32 on the lower arms 30.
[0082] The average temperature of the switching elements 32 on the multiple upper arms 28 and the average temperature of the switching elements 32 on the multiple lower arms 30 may each be the temperature T in step S12. In this case, when the temperature detection unit 72 detects that the average temperature of all upper arms 28 has become equal to or greater than the first temperature threshold Tth1, the control unit 68 turns off the switching elements 32 on all upper arms 28. Similarly, when the temperature detection unit 72 detects that the average temperature of all lower arms 30 has become equal to or greater than the first temperature threshold Tth1, the control unit 68 turns off the switching elements 32 on all lower arms 30. This suppresses the temperature difference between the switching elements 32 on the upper arms 28 and the switching elements 32 on the lower arms 30.
[0083] Figure 13 is a flowchart of the process for transitioning from the second control to the first control. The arithmetic unit 64 in the control device 62 executes the process shown in Figure 13 after executing the second control (step S13) shown in Figure 12. The following describes the process performed with respect to the first converter 22a, but the process performed with respect to the second converter 22b is carried out in the same manner.
[0084] In step S21, the temperature detection unit 72 acquires signals from each temperature sensor 42 provided in the first converter 22a.
[0085] In step S22, the temperature detection unit 72 compares the temperature T of each of the multiple switching elements 32 that were turned off in step S13 of Figure 12 with a predetermined second temperature threshold Tth2. The second temperature threshold Tth2 is any temperature lower than the first temperature threshold Tth1. The second temperature threshold Tth2 is pre-stored in the storage unit 66. If the temperature T of each of the multiple switching elements 32 that were turned off is less than or equal to the second temperature threshold Tth2 (step S22: YES), the process proceeds to step S23. On the other hand, if the temperature T of any of the multiple switching elements 32 that were turned off is greater than the second temperature threshold Tth2 (step S22: NO), the process returns to step S21.
[0086] When the process moves from step S22 to step S23, the control unit 68 turns on all switching elements 32. That is, the control unit 68 executes the first control. Thereafter, the calculation unit 64 (temperature detection unit 72 and control unit 68) executes either the process shown in Figure 12 or the process shown in Figure 13.
[0087] The average temperature of the switching elements 32 of the multiple upper arms 28 or the average temperature of the switching elements 32 of the multiple lower arms 30 may be the temperature T in step S22.
[0088] [Mobile body 80 equipped with power supply system 10] Figure 14 is a schematic diagram of the mobile unit 80. As shown in Figure 14, the power supply system 10 is mounted on the mobile unit 80.
[0089] The mobile unit 80 of this embodiment is an electric vertical take-off and landing (eVTOL) aircraft. The mobile unit 80 is equipped with eight VTOL rotors 82. The VTOL rotors 82 generate upward thrust relative to the airframe 84. The mobile unit 80 is equipped with eight electric motors 86. One electric motor 86 drives one VTOL rotor 82. The mobile unit 80 has two cruise rotors 88. The cruise rotors 88 generate forward thrust relative to the airframe 84. The mobile unit 80 is equipped with four electric motors 90. Two electric motors 90 drive one cruise rotor 88.
[0090] Each of the first load device 16a, second load device 16b, third load device 16c, and fourth load device 16d is equipped with two electric motors 86 and one electric motor 90. In addition to the electric motors 86 and 90, each of the first load device 16a, second load device 16b, third load device 16c, and fourth load device 16d may also be equipped with a low-voltage drive device.
[0091] The mobile body 80 is not limited to an aircraft; it may also be a ship, automobile, train, etc.
[0092] [Note] The following additional information is disclosed regarding the above embodiments.
[0093] (Note 1) The power supply system (10) of the present disclosure includes a plurality of switching elements (32), a converter (22a, 22b) that converts a multiphase AC voltage output from a generator (20a, 20b) into a DC voltage, a control unit (68) that controls the converter, and a determination unit (70) that determines whether or not a short-circuit failure has occurred in any of the plurality of switching elements provided in the converter. The converter includes a plurality of switching element sections (24u, 24v, 24w) corresponding to each phase of the multiphase AC voltage, in which upper arm-side switching elements, which are the switching elements on the upper arm (28), and lower arm-side switching elements, which are the switching elements on the lower arm (30), are connected in series with each other. When the determination unit determines that a short-circuit failure has occurred in any of the plurality of switching elements provided in the converter, the control unit may perform a first control that turns on all of the switching elements provided in the converter.
[0094] According to the above configuration, in the event of a short-circuit failure in any of the switching elements, it is possible to avoid problems such as an increase in the amount of heat generated by the generator and demagnetization of the generator, as well as to suppress the increase in the amount of heat generated by the switching elements. Therefore, according to the above configuration, it is possible to suppress the temperature rise of the switching elements.
[0095] (Note 2) In the power supply system described in Appendix 1, a temperature detection unit (72) is provided for detecting the temperature of each of the switching elements, and the control unit, after executing the first control, executes a second control that controls the converter based on the temperature detected by the temperature detection unit, and in the second control, if the temperature detection unit detects that the temperature (T) of at least one of the plurality of upper arm side switching elements has become equal to or greater than a predetermined temperature threshold (Tth1), all of the plurality of lower arm side switching elements are turned on and all of the upper arm side switching elements are turned off, and in the second control, if the temperature detection unit detects that the temperature of at least one of the plurality of lower arm side switching elements has become equal to or greater than the temperature threshold, all of the plurality of upper arm side switching elements are turned on and all of the lower arm side switching elements are turned off.
[0096] According to the above configuration, the temperature difference between the switching element on the upper arm and the switching element on the lower arm is suppressed.
[0097] (Note 3) The power supply system described in Appendix 1 may include a power storage device (50a, 50b, 50c, 50d) that can be charged by the DC voltage supplied from the converter, and a circuit breaker (54a, 54b, 54c, 54d) disposed between the power storage device and the converter that can interrupt the power supply from the power storage device to the converter.
[0098] According to the above configuration, it is possible to prevent the supply (reverse flow) of power (current) from the energy storage device to the power generation device.
[0099] (Note 4) In the power supply system described in Appendix 3, the interruption unit may be a switching device (60) that switches between connection and interruption in response to a switching signal from the control unit.
[0100] (Note 5) In the power supply system described in Appendix 3, the interruption unit may be a diode (56) that allows current from the converter to the energy storage device and blocks current from the energy storage device to the converter.
[0101] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values or mathematical formulas are used in the description of the embodiments described above. [Explanation of Symbols]
[0102] 10...Power supply system 20a...First generator (generator) 20b...Second generator (generator) 22a...First converter (converter) 22b...Second converter (converter) 24u, 24v, 24w... Switching element section 28...Upper arm 30...Lower arm 32…Switching elements (upper arm switching element, lower arm switching element) 50a...First energy storage device (energy storage device) 50b...Second energy storage device (energy storage device) 50c...Third energy storage device (energy storage device) 50d...Fourth energy storage device (energy storage device) 54a, 54b, 54c, 54d... Backflow prevention device (shutdown section) 56... Diode 60... Contactor (switching device) 68...Control unit 70...Determination unit 72...Temperature detection section T...Temperature Tth1…First temperature threshold (temperature threshold)
Claims
1. A converter that includes multiple switching elements and converts the multiphase AC voltage output from a generator into a DC voltage, A control unit that controls the converter, A determination unit that determines whether or not a short-circuit failure has occurred in any of the plurality of switching elements provided in the converter, Equipped with, The converter comprises a plurality of switching element sections, each corresponding to a phase of the multiphase AC voltage, in which an upper arm-side switching element (the switching element on the upper arm) and a lower arm-side switching element (the switching element on the lower arm) are connected in series with each other. A power supply system in which, when the determination unit determines that a short-circuit failure has occurred in any of the plurality of switching elements provided in the converter, the control unit can perform a first control to turn on all of the switching elements provided in the converter.
2. In the power supply system according to claim 1, It includes a temperature detection unit that detects the temperature of each of the switching elements, After executing the first control, the control unit executes a second control that controls the converter based on the temperature detected by the temperature detection unit. In the second control, when the temperature detection unit detects that the temperature of at least one of the plurality of upper arm-side switching elements has risen above a predetermined temperature threshold, all of the plurality of lower arm-side switching elements are turned on, and all of the upper arm-side switching elements are turned off. In the second control, when the temperature detection unit detects that the temperature of at least one of the plurality of lower arm-side switching elements has risen above the temperature threshold, all of the plurality of upper arm-side switching elements are turned on, and all of the lower arm-side switching elements are turned off, in a power supply system.
3. In the power supply system according to claim 1, A power storage device that can be charged by the DC voltage supplied from the converter, A circuit breaker is provided between the energy storage device and the converter, which is capable of interrupting the power supply from the energy storage device to the converter. A power supply system equipped with the following features.
4. In the power supply system according to claim 3, The power supply system is characterized in that the interruption unit is a switching device that switches between connection and interruption in accordance with a switching signal from the control unit.
5. In the power supply system according to claim 3, A power supply system in which the interruption unit is a diode that allows current from the converter to the energy storage device and blocks current from the energy storage device to the converter.