Diagnostic device and program

Abstract

To provide a diagnosis device and a program capable of appropriately diagnosing an ON failure of a power supply switch.SOLUTION: A diagnosis device 40 is applied to a power system 10 provided with: a power supply 23; an inverter 24 connected to the power supply; a rotary electric machine 21 connected to the inverter; power supply switches RM1 and RM2 installed on a power supply path between the power supply and the inverter; and a voltage sensor 27 for detecting a path voltage being a voltage of the power supply path on an inverter side of the power supply switch. The diagnosis device 40 outputs a shut-off command for shutting off the power supply switches while the inverter control is stopped when a switch diagnosis condition of the power supply switches is satisfied in a conductive state of the power supply switches, to acquire a voltage difference being a difference between detected voltages of the voltage sensor in response to a rotation speed variation of the rotary electric machine generated after the outputting of the shut-off command. Then, an ON failure of the power supply switches is diagnosed based on the voltage difference.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a diagnostic device and a program for diagnosing an ON failure of a power switch. [Background technology]

[0002] In a conventional power supply system including a power supply, an inverter, and a rotating electric machine, a power supply switch (system main relay) that connects or disconnects the power supply and the rotating electric machine is provided in a power supply path that connects the power supply and the inverter. Also, in this power supply system, a device is known that diagnoses whether the power supply switch is welded while the rotating electric machine is being rotated.

[0003] As an example of this type of device, in Patent Document 1, when a power supply abnormality is detected, a shut-off command is output to shut off the power switch, and the inverter is controlled so that the path voltage, which is the voltage of the power supply path on the inverter side of the power switch, becomes a predetermined target voltage, and welding of the power switch is diagnosed based on whether or not this control causes the path voltage to change to the target voltage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-183134 A Summary of the Invention [Problem to be solved by the invention]

[0005] When a rotating electric machine is in a rotating state, a back electromotive force is generated according to the rotation speed of the rotating electric machine. Therefore, in order to set the path voltage to a target voltage by controlling the inverter, it is necessary to control the inverter so as to cancel the back electromotive force of the rotating electric machine, which complicates the configuration and control of the inverter. There is a demand for a technology that can appropriately diagnose an on-fault of a power switch without changing the path voltage by inverter control.

[0006] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a diagnostic device and a program capable of appropriately diagnosing an ON failure of a power switch. [Means for solving the problem]

[0007] A first means for solving the above problem is applied to a power supply system including a power source, an inverter connected to the power source, a rotating electric machine connected to the inverter, a power switch provided in a power supply path between the power source and the inverter, and a voltage sensor for detecting a path voltage, which is the voltage of the power supply path on the inverter side of the power switch, and includes a shutoff command unit that outputs a shutoff command to shut off the power supply switch while stopping control of the inverter when a predetermined switch diagnosis condition is satisfied when the power switch is in a conductive state, an acquisition unit that acquires a voltage difference, which is the difference in detected voltages of the voltage sensors according to a change in the rotation speed of the rotating electric machine after the shutoff command is output by the shutoff command unit, and a diagnosis unit that diagnoses an on-failure of the power switch based on the voltage difference.

[0008] In the above configuration, when a predetermined switch diagnosis condition is satisfied in the conductive state of the power switch, a shutoff command is output to shut off the power switch with the inverter control stopped. Also, a voltage difference, which is a difference between the detected voltages of the voltage sensors according to the change in the rotation speed of the rotating electric machine that occurs after the shutoff command is output, is acquired, and an ON failure of the power switch is diagnosed based on the voltage difference. Here, when the power switch is normal, in the inverter control stopped state, the path voltage on the inverter side after the shutoff command is output (the voltage of the power path on the inverter side of the power switch) depends on the back electromotive force of the rotating electric machine, and when the rotation speed of the rotating electric machine changes after the shutoff command is output, it changes corresponding to the change in the rotation speed. On the other hand, when the power switch has an ON failure, the path voltage on the inverter side after the shutoff command is output does not change corresponding to the change in the rotation speed even if the rotation speed of the rotating electric machine changes after the shutoff command is output. Therefore, by grasping the voltage change corresponding to the change in the rotation speed of the rotating electric machine that occurs after the shutoff command is output, an ON failure of the power switch can be appropriately diagnosed. Furthermore, in the above configuration, the power switch is diagnosed for an on-failure while inverter control is stopped, and switch failure diagnosis can be realized with a simple configuration without causing a voltage change due to inverter control.

[0009] In a second means, in the power supply system, a smoothing capacitor is connected in parallel to the power supply in the power supply path on the inverter side of the power switch, and a discharge processing unit is provided which discharges the smoothing capacitor under a situation in which a decrease in the rotation speed occurs after the shut-off command is output by the shut-off command unit, and the acquisition unit acquires, as the voltage difference, a difference between the detected voltage before the discharge of the smoothing capacitor by the discharge processing unit and the detected voltage after the discharge of the smoothing capacitor under a situation in which a decrease in the rotation speed occurs after the output of the shut-off command.

[0010] By providing a smoothing capacitor in the power supply system, the path voltage can be stabilized. On the other hand, if a smoothing capacitor is provided in the power supply system, it is considered that the smoothing capacitor may hinder monitoring of voltage changes on the inverter side. In this regard, in the above configuration, the smoothing capacitor is discharged under a situation in which the rotation speed of the rotating electric machine decreases after the output of the shutoff command. As a result, after the output of the shutoff command, the path voltage on the inverter side can be set to a voltage corresponding to the rotation speed of the rotating electric machine, and an ON failure of the power switch can be properly diagnosed.

[0011] In the third means, the discharge processing unit causes the smoothing capacitor to discharge so that the path voltage becomes lower than an electromotive force voltage of the rotating electric machine when the discharge of the smoothing capacitor ends.

[0012] When the smoothing capacitor finishes discharging, the route voltage is recharged to the electromotive force voltage of the rotating electric machine. In this case, if the route voltage at the end of the smoothing capacitor's discharge is higher than the electromotive force voltage of the rotating electric machine, it becomes impossible to grasp the voltage change corresponding to the change in the rotation speed of the rotating electric machine. In this regard, the smoothing capacitor is discharged so that the route voltage is lower than the electromotive force voltage of the rotating electric machine at the end of the smoothing capacitor's discharge. This makes it possible to properly grasp the voltage change corresponding to the change in the rotation speed of the rotating electric machine, and thus to properly perform a fault diagnosis of the power switch.

[0013] In a fourth means, the discharge processing unit enables multiple discharges of the smoothing capacitor under circumstances in which a decrease in the rotation speed occurs after the output of the shut-off command, and the acquisition unit acquires the rotation speed and the path voltage before the first discharge of the smoothing capacitor and after each discharge thereafter when the smoothing capacitor is discharged multiple times, and the diagnosis unit calculates an approximation line that linearly approximates the relationship between the rotation speed and the path voltage using three or more combinations of the rotation speed and the path voltage acquired by the acquisition unit, and diagnoses an on-failure of the power switch based on a slope of the approximation line and a variation in the path voltage relative to the approximation line.

[0014] For example, even if the power switch has an on-failure, the path voltage may change due to detection error or noise of the voltage sensor. In this case, the voltage difference may become large, and there is a concern that the on-failure of the power switch may be missed. In this regard, in the above configuration, under a situation in which the rotation speed of the rotating electric machine decreases after the output of a power switch cut-off command, the smoothing capacitor is discharged multiple times, and an approximation line is calculated from the rotation speed and path voltage acquired for each capacitor discharge. In addition, the on-failure of the power switch is diagnosed based on the slope of the approximation line and the variation in the path voltage relative to the approximation line. In this case, the reliability of the slope of the approximation line can be determined based on the variation in the path voltage relative to the approximation line, and the on-failure diagnosis of the power switch can be appropriately performed using the slope of the approximation line.

[0015] In a fifth means, in a situation where a decrease in the rotation speed occurs after the output of the shut-off command, the acquisition unit acquires the rotation speed and the path voltage before and after a first capacitor discharge by the discharge processing unit as first data and second data, respectively, and acquires the rotation speed and the path voltage after a subsequent second capacitor discharge as third data, and the diagnosis unit acquires the first to third data if the rotation speed of the rotating electric machine is higher than a predetermined value at the time the second data is acquired, and diagnoses an on-failure of the power switch using the first to third data, while if the rotation speed of the rotating electric machine is lower than a predetermined value at the time the second data is acquired, acquires the first and second data of the first to third data, and diagnoses an on-failure of the power switch using the first and second data.

[0016] When the smoothing capacitor is discharged multiple times and a power switch ON fault is diagnosed based on an approximation line calculated from the rotation speed and the path voltage for each capacitor discharge and the variation of the path voltage with respect to the approximation line, the accuracy of the fault diagnosis can be improved, but there is a concern that the fault diagnosis takes time because multiple capacitor discharges are required. Also, when the rotating electric machine is in a low rotation state, it is considered that the change in the rotation speed from that point cannot be expected.

[0017] In this regard, if the rotation speed of the rotating electric machine is higher than a predetermined value when the second data is acquired after the first capacitor discharge, the first to third data are used to diagnose an ON failure of the power switch, whereas if the rotation speed of the rotating electric machine is lower than a predetermined value when the second data is acquired, the first and second data are used to diagnose an ON failure of the power switch. This makes it possible to perform an appropriate failure diagnosis while taking into account the rotation state of the rotating electric machine.

[0018] In a sixth means, the power supply system is equipped with a current sensor that detects the power supply current, which is the current flowing through the power supply, and the acquisition unit acquires the detected current of the current sensor after the shut-off command is output by the shut-off command unit, and the diagnosis unit executes a first judgment process to determine whether the voltage difference is greater than a predetermined voltage threshold and a second judgment process to determine whether the detected current is greater than a predetermined current threshold, and when the first judgment process determines that the voltage difference is smaller than the voltage threshold and the second judgment process determines that the detected current is greater than the current threshold, the power supply switch is diagnosed as having an on failure.

[0019] According to the above configuration, a first judgment process using the voltage difference and a second judgment process using the detected current are executed, and if the first judgment process judges that the voltage difference is smaller than a predetermined voltage threshold and the second judgment process judges that the detected current is larger than a current threshold, the power switch is diagnosed as having an on-failure. By diagnosing the on-failure of the power switch using the voltage difference and the detected current, the on-failure diagnosis of the power switch can be performed more appropriately than when the on-failure of the power switch is diagnosed using only the voltage value.

[0020] In a seventh embodiment, the power supply system is mounted on a vehicle capable of rotating the rotating electric machine in conjunction with the rotation of the wheels, and is provided with a speed control unit that, when the shut-off command is output by the shut-off command unit, reduces the vehicle's traveling speed to reduce the rotation speed of the rotating electric machine, while canceling the reduced traveling speed state when the diagnosis unit determines that the power switch is normal.

[0021] According to the above configuration, the rotation speed of the rotating electric machine decreases as the vehicle speed decreases, so that a desired voltage drop can be generated on the inverter side. Also, the vehicle running speed can be appropriately controlled each time depending on whether the power switch is normal or has an on-failure.

[0022] In an eighth means, the power supply system is mounted on a vehicle having a gear mechanism that varies the gear ratio in a rotational transmission path between the wheels and the rotating electric machine, and is provided with a gear ratio adjustment unit that increases the gear ratio of the rotating electric machine side relative to the wheel side while the vehicle is traveling after the shut-off command is output by the shut-off command unit, and the acquisition unit acquires as the voltage difference the difference between the detected voltage before the gear ratio is increased by the gear ratio adjustment unit and the detected voltage after the gear ratio is increased.

[0023] In the above configuration, after the cutoff command is output, the gear ratio of the rotating electric machine to the wheel side is increased, which makes it possible to reduce the rotation speed of the rotating electric machine while suppressing a decrease in the vehicle speed, and thus makes it difficult for a driver to feel uncomfortable due to deceleration while the vehicle is traveling.

[0024] In a ninth means, the power supply system rotates a propeller using the rotating electric motor in an aircraft that flies in conjunction with the rotation of the propeller, and is provided with a propeller rotation control unit that reduces the rotation speed of the rotating electric motor along with the rotation speed of the propeller when the shutdown command is output by the shutdown command unit.

[0025] According to the above configuration, in the aircraft, the rotation speed of the rotating electric machine decreases together with the rotation speed of the propeller, thereby causing a desired voltage drop required for fault diagnosis of the power switch on the inverter side.

[0026] In a tenth means, the propeller rotation control unit releases the reduced propeller rotation speed state when, after the shut-off command is output and the diagnosis unit performs a diagnosis, it is determined that the power switch is normal and there is a request to increase the propeller rotation speed.

[0027] According to the above configuration, when the power switch is determined to be normal and there is a request to increase the propeller rotation speed, the state of reduced propeller rotation speed is released, thereby allowing the flight of the aircraft to be preferably restored to the flight state before diagnosis after fault diagnosis of the power switch.

[0028] In an eleventh means, the power supply system is applied to a moving body having a plurality of drive units each having the inverter, the rotating electric machine, the power switch, and the voltage sensor, and in the moving body, movement is possible by driving some of the drive units, and when some of the drive units in a driven state are to be stopped while the moving body is moving, the cut-off command unit determines that the switch diagnosis condition is met for the drive unit to be stopped, and outputs the cut-off command.

[0029] In the above configuration, when a driving unit is stopped from a driving state during the movement of a moving body having multiple driving units, the switch diagnosis condition is determined to be satisfied for the driving unit to be stopped, and a disconnection command is output. In this case, a fault diagnosis can be performed on the driving unit in the stopped state without affecting the moving state of the moving body.

[0030] The twelfth means includes a power control unit that, when some of the drive units are stopped while the moving body is moving and the cut-off command is output by the cut-off command unit for a drive unit to be stopped, outputs a power command value to maintain the moving state of the moving body to the other drive units to which the cut-off command has not been output.

[0031] According to the above configuration, when the drive of any one of the drive units is stopped to perform a fault diagnosis of the power switch, the moving state of the moving body is maintained unchanged before and after the drive is stopped. This makes it possible to perform a fault diagnosis of the drive unit without affecting the moving state of the moving body. [Brief description of the drawings]

[0032] [Figure 1] FIG. 1 is a diagram showing the configuration of a control system. [Diagram 2] 11 is a flowchart showing the procedure of a control process. [Diagram 3] 5 is a flowchart showing a processing procedure of a diagnosis process according to the first embodiment. [Figure 4] This is a timing chart when the main relay is normal. [Diagram 5] This is a timing chart when the main relay has an on-fault. [Figure 6] Graph showing the slope of the path voltage. [Figure 7] 10 is a flowchart showing the processing procedure of a diagnosis process according to the second embodiment. [Figure 8] 13 is a flowchart showing the processing procedure of a diagnostic process according to the third embodiment. [Figure 9] This is a timing chart when the main relay is normal. [Figure 10] This is a timing chart when the main relay has an on-fault. [Figure 11] Graph showing an approximation line. [Figure 12] FIG. 13 is a configuration diagram of a control system according to a fourth embodiment. [Figure 13] 13 is a flowchart showing the processing procedure of a diagnosis process according to the fourth embodiment. [Figure 14] 13 is a flowchart showing the processing procedure of a diagnosis process according to the fourth embodiment. [Figure 15] 10 is a flowchart showing a procedure of a diagnostic process according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] First Embodiment Hereinafter, an embodiment in which a diagnostic device according to the present invention is applied to an on-vehicle control system 10 will be described with reference to the drawings.

[0034] As shown in FIG. 1, the control system 10 is a control system for a hybrid vehicle having an engine 31 and a rotating electric machine 21 as a driving power source. This control system 10 corresponds to a power supply system. An output shaft 32 of the engine 31 is connected to a rotating shaft 22 of the rotating electric machine 21 via a transmission 33. The rotating shaft 22 of the rotating electric machine 21 is connected to an axle 51 connecting left and right wheels 50 of the vehicle via a well-known gear mechanism 34. The driving force of the engine 31 and the rotating electric machine 21 is transmitted to the wheels 50 via the gear mechanism 34, and the wheels 50 rotate. Furthermore, the rotating electric machine 21 rotates in accordance with the rotation of the wheels 50, and the rotating electric machine 21 generates electricity. The electricity generated by the rotating electric machine 21 is stored in a battery 23, which is a power source.

[0035] The battery 23 is connected to the rotating electric machine 21 via an inverter 24, and inputs and outputs electric power between the rotating electric machine 21. The battery 23 is, for example, a lithium ion battery. The rotating electric machine 21 is a three-phase synchronous machine and has U-, V-, and W-phase windings as stator windings. The rotating electric machine 21 is, for example, a permanent magnet synchronous machine.

[0036] The inverter 24 includes three phases of series-connected upper-arm switches QUH, QVH, and QWH and lower-arm switches QUL, QVL, and QWL. In this embodiment, a voltage-controlled semiconductor switching element, specifically an IGBT, is used as each switch. A freewheel diode DA is connected in inverse parallel to each switch.

[0037] In each series connection, the connection point between the low potential side terminal of the upper arm switch QUH, QVH, QWH and the high potential side terminal of the lower arm switch QUL, QVL, QWL is connected to the corresponding winding of the rotating electric machine 21 via a conductive member 25 such as a bus bar. In addition, the high potential side terminal of each upper arm switch QUH, QVH, QWH is connected to the positive terminal of the battery 23 by a positive side power supply path LP. The low potential side terminal of each lower arm switch QUL, QVL, QWL is connected to the negative terminal of the battery 23 by a negative side power supply path LN.

[0038] The control system 10 includes a smoothing capacitor 26. The smoothing capacitor 26 is connected between the positive power supply path LP and the negative power supply path LN, and is connected in parallel to the battery 23.

[0039] The control system 10 includes a first main relay RM1 and a second main relay RM2 serving as power switches. The first main relay RM1 is provided on the positive power supply path LP, closer to the battery 23 than the smoothing capacitor 26. The second main relay RM2 is provided on the negative power supply path LN, closer to the battery 23 than the smoothing capacitor 26. The first and second main relays RM1 and RM2 switch between a conducting state and a non-conducting state between the battery 23 and the rotating electric machine 21.

[0040] A series connection of a precharge relay RP and a resistor RA is connected in parallel to the first main relay RM1. When the precharge relay RP is turned on (closed) at the start of energization between the battery 23 and the rotating electric machine 21, energization is performed via the resistor RA, thereby suppressing an inrush current from flowing between the battery 23 and the rotating electric machine 21. The precharge relay RP and the resistor RA may be provided on the negative electrode side instead of the positive electrode side, or the precharge relay RP and the resistor RA may not be provided on either the positive electrode side or the negative electrode side. In this embodiment, a mechanical relay switch is used as each of the relays RM1, RM2, and RP.

[0041] The control system 10 includes a voltage sensor 27, a current sensor 28, a rotation speed sensor 29, and a vehicle speed sensor 30. The voltage sensor 27 is connected between the positive power path LP and the negative power path LN on the inverter 24 side of the main relays RM1 and RM2, and detects a path voltage VA that is a voltage between the positive power path LP and the negative power path LN, that is, a voltage applied to the smoothing capacitor 26. The current sensor 28 is provided on the positive power path LP on the battery 23 side of the first main relay RM1, and detects a power current IA that is a current flowing to the battery 23. The rotation speed sensor 29 detects the number of rotations NA per unit time of the rotating electric machine 21, that is, the rotation speed. The vehicle speed sensor 30 detects the rotation speed of the wheels 50, that is, the vehicle speed XA that is the traveling speed of the host vehicle. The detection values ​​of each of these sensors are input to a control device 40 included in the control system 10.

[0042] The functions provided by the control device 40 as a diagnostic device can be provided by software recorded in a physical memory device and a computer that executes the software, by software alone, by hardware alone, or by a combination of these. For example, when the control device 40 is provided by an electronic circuit that is hardware, it can be provided by a digital circuit including a large number of logic circuits, or an analog circuit. For example, the control device 40 executes a program stored in a non-transitory tangible storage medium as a storage unit that the control device 40 has. By executing the program, a method corresponding to the program is executed. The storage unit is, for example, a non-volatile memory. Note that the program stored in the storage unit can be updated, for example, via a network such as the Internet.

[0043] The control device 40 acquires each detection value and executes various controls based on the acquired values. Specifically, the control device 40 controls the inverter 24 and controls the open / closed states of the relays RM1, RM2, and RP based on each detection value.

[0044] Furthermore, the control device 40 diagnoses the main relays RM1 and RM2 for a fault when a predetermined switch diagnosis condition is satisfied. For example, if an abnormality occurs in the battery 23 or the inverter 24 while the vehicle is running, causing an overcurrent to flow through the power supply paths LP and LN, the control device 40 diagnoses the main relays RM1 and RM2 for a fault.

[0045] In this embodiment, when it is determined that an abnormality (hereinafter, specific abnormality) has occurred in a device connected to the main relays RM1, RM2, such as the battery 23 or the inverter 24, while the main relays RM1, RM2 are in a closed state (conductive state), it is assumed that the switch diagnosis condition is satisfied, and a shutoff command is output to shut off the main relays RM1, RM2 with the control of the inverter 24 stopped. Also, a voltage difference ΔV that is a difference in the path voltage VA according to a change in the rotation speed NA of the rotating electric machine 21 that occurs after the output of the shutoff command, for example, in a situation where a change in the rotation speed NA of the rotating electric machine 21 occurs after the output of the shutoff command, is obtained, and an on-failure of the main relays RM1, RM2 is diagnosed based on the voltage difference ΔV.

[0046] A flow chart of the control process of this embodiment is shown in Fig. 2. The control device 40 repeatedly executes the control process at a predetermined cycle while the vehicle is traveling.

[0047] When the control process is started, in step S11, it is determined whether or not a specific abnormality has occurred. The control device 40 determines whether or not a specific abnormality has occurred based on, for example, the detection value of the current sensor 28. If a specific abnormality has not occurred, the process proceeds to step S12, and the vehicle is driven normally. Normal driving refers to driving of the vehicle by the driving force of at least one of the engine 31 and the rotating electric machine 21. On the other hand, if a specific abnormality has occurred, the process proceeds to step S13.

[0048] In step S13, control of the inverter 24 is stopped in order to cut off the main relays RM1, RM2 with the current flowing through them set to zero. In the following step S14, a cut-off command to cut off the main relays RM1, RM2 is output. With the inverter control being stopped, the vehicle is prohibited from traveling using the rotating electric machine 21, and travel is performed using engine driving force. In this embodiment, the process of step S14 corresponds to the "cut-off command unit, cut-off command step."

[0049] In step S15, a diagnostic process is executed to diagnose whether or not the main relays RM1 and RM2 have an ON fault. The procedure of the diagnostic process is shown in FIG.

[0050] In step S21, the driving force of the engine 31 is reduced. This reduction in the engine driving force reduces the vehicle speed XA and the rotation speed NA of the rotating electric machine 21. When limiting the driving force of the engine 31 is started, it is preferable to notify the driver of this in order to prevent the driver from feeling uncomfortable due to deceleration of the vehicle.

[0051] In step S22, the path voltage (detected voltage) VA and the rotation speed NA are acquired. In step S22, after the path voltage VA becomes stable after the output of the shutoff command, the path voltage VA and the rotation speed NA are acquired. Hereinafter, the path voltage VA and the rotation speed NA acquired in step S22 are referred to as the first voltage V1 and the first rotation speed N1.

[0052] In step S23, the vehicle speed XA is acquired, and it is determined whether the vehicle speed XA is equal to or lower than a predetermined speed Xth. The predetermined speed Xth is a vehicle speed at which the smoothing capacitor 26 can be discharged by the rotating electric machine 21 while the rotating electric machine 21 is rotating. When the smoothing capacitor 26 is discharged by the rotating electric machine 21, the inverter 24 controls the electric current to be supplied from the smoothing capacitor 26 to the rotating electric machine 21 at a phase at which the rotating electric machine 21 does not generate torque even if the rotating electric machine 21 is supplied with current. The predetermined speed Xth is set to a vehicle speed corresponding to a predetermined rotation speed Nth, which is a maximum value at which the occurrence of vibrations of the rotating electric machine 21 due to the back electromotive force of the rotating electric machine 21 can be suppressed and the path voltage VA can be reduced, even if the smoothing capacitor 26 is discharged by the rotating electric machine 21 while the rotating electric machine 21 is rotating. If the vehicle speed XA is higher than the predetermined speed Xth, step S23 is repeated.

[0053] On the other hand, if the vehicle speed XA is equal to or lower than the predetermined speed Xth, the process proceeds to step S24, where the smoothing capacitor 26 is discharged for a predetermined period while the rotating electric machine 21 is rotating. At this time, the smoothing capacitor 26 is discharged for a period longer than the period required for the path voltage VA to decrease to an electromotive force voltage due to the counter electromotive force of the rotating electric machine 21 (hereinafter, the counter electromotive voltage). This discharge causes the path voltage VA to decrease below the counter electromotive voltage of the rotating electric machine 21. In this embodiment, the process of step S24 corresponds to a "discharge processing unit."

[0054] In step S25, the path voltage VA and the rotation speed NA are acquired after the smoothing capacitor 26 is discharged. At this time, the path voltage VA is acquired in a state where the transient voltage change has converged. In step S25, the second voltage V2 and the second rotation speed N2 are acquired at a timing when the difference between the first rotation speed N1 and the second rotation speed N2 becomes equal to or greater than a predetermined change amount. Hereinafter, the path voltage VA and the rotation speed NA acquired in step S25 are referred to as the second voltage V2 and the second rotation speed N2.

[0055] In step S26, the difference between the first rotation speed N1 and the second rotation speed N2 is calculated as the change amount ΔN of the rotation speed NA. In addition, in step S26, the difference between the first voltage V1 and the second voltage V2 is calculated as the voltage difference ΔV of the path voltage VA before and after the change amount ΔN. The first voltage V1 is the path voltage VA before the discharge of the smoothing capacitor 26, and the second voltage V2 is the path voltage VA after the discharge of the smoothing capacitor 26. Therefore, the voltage difference ΔV can be said to be the voltage difference of the path voltage VA before and after the discharge of the smoothing capacitor 26. In this embodiment, the processes of steps S22, S25, and S26 correspond to the "acquisition unit, acquisition step."

[0056] In step S27, a slope KA of the change in the path voltage VA before and after the change in the rotation speed NA is calculated. The slope KA is the ratio of the voltage difference ΔV of the path voltage VA to the amount of change ΔN in the rotation speed NA, and is expressed as the following (Equation 1) using the detection values ​​V1, V2, N1, and N2.

[0057] KA = ΔV / ΔN = (V2-V1) / (N2-N1) (Equation 1) In step S28, it is determined whether the slope KA calculated in step S27 is equal to or greater than a predetermined slope threshold Kth. If the slope KA is equal to or greater than the slope threshold Kth, the process proceeds to step S29, where the main relays RM1, RM2 are diagnosed as normal. In this case, in step S30, the restriction on the driving force of the engine 31 is lifted to release the reduced state of the vehicle speed XA, and this process is temporarily terminated. In this embodiment, the process of step S28 corresponds to the "diagnosis unit, diagnosis step", and the processes of steps S21, S30 correspond to the "speed control unit".

[0058] On the other hand, if the gradient KA is less than the gradient threshold Kth, the process proceeds to step S31, where it is diagnosed that the main relays RM1 and RM2 have an ON fault. In this case, the process is temporarily terminated while maintaining the limitation on the driving force of the engine 31.

[0059] Returning to FIG. 2, in step S16, it is determined whether or not the main relays RM1, RM2 are diagnosed as having an ON-failure in the diagnosis process of step S15. If the main relays RM1, RM2 are diagnosed as having an ON-failure, the process proceeds to step S17, where the engine 31 is stopped to prohibit the vehicle from traveling, and this process ends temporarily. On the other hand, if the main relays RM1, RM2 are diagnosed as normal, the process proceeds to step S18, where the vehicle continues to travel by the engine 31, and this process ends temporarily. Note that in this embodiment, the diagnosis process is executed on the condition that a specific abnormality has occurred, and even if the main relays RM1, RM2 are diagnosed as normal in step S16, the prohibition of traveling by the rotating electric machine 21 is maintained.

[0060] Next, the procedure of the diagnosis process will be described with reference to Figures 4 and 5. In Figures 4 and 5, (A) shows the transition of the control state of the inverter 24, (B) shows the transition of the cutoff command for the main relays RM1 and RM2, (C) shows the transition of the driving force limit of the engine 31, and (D) shows the transition of the vehicle speed XA. In addition, (E) shows the transition of the rotation speed NA, (F) shows the transition of the discharge of the smoothing capacitor 26, and (G) shows the transition of the path voltage VA.

[0061] As shown in Fig. 4, before time t1, the vehicle speed XA is equal to or higher than a predetermined speed Xth. Furthermore, the main relays RM1 and RM2 are closed, and the rotation speed NA is equal to or higher than a predetermined rotation speed Nth due to the control of the inverter 24. Then, at time t1, it is determined that a specific abnormality has occurred, and the control of the inverter 24 is stopped. After that, at time t2, a cut-off command is output to cut off the main relays RM1 and RM2. In Fig. 4, it is assumed that the main relays RM1 and RM2 are normal, and the main relays RM1 and RM2 are opened by the output of the cut-off command, and the path voltage VA changes from the power supply voltage VB of the battery 23 to the back electromotive voltage.

[0062] When the shutoff command is output, limiting the driving force of the engine 31 is started at time t3 in order to reduce the rotation speed NA of the rotating electric machine 21. When there is concern about an on-failure of the main relays RM1, RM2 due to the occurrence of a specific abnormality, the driving force of the engine 31 is limited and the vehicle speed XA is reduced, thereby ensuring the traveling safety of the vehicle. In addition, the first voltage V1 and the first rotation speed N1 are acquired at time t3. Note that the first voltage V1 is acquired after the path voltage VA becomes stable after the shutoff command is output.

[0063] When the driving force of the engine 31 is limited at time t3, the rotation speed NA decreases as the vehicle speed XA decreases. When the rotation speed NA decreases, the back electromotive force decreases, but the route voltage VA is kept approximately constant by the smoothing capacitor 26.

[0064] When the rotation speed NA drops to a predetermined rotation speed Nth at time t4, the smoothing capacitor 26 is discharged for a predetermined period from time t4 to t5. As a result, the path voltage VA drops to a voltage lower than the back electromotive force of the rotating electric machine 21. When the discharge of the smoothing capacitor 26 is stopped at time t5, the path voltage VA rises due to the back electromotive force of the rotating electric machine 21. When the path voltage VA rises to the back electromotive force of the rotating electric machine 21 at time t6, the second voltage V2 and the second rotation speed N2 are acquired. The second voltage V2 is acquired after the path voltage VA becomes stable after it has risen to the back electromotive force.

[0065] When the second voltage V2 and the second rotation speed N2 are acquired, the slope KA of the path voltage VA is calculated using the respective detection values ​​V1, V2, N1, and N2. In the example shown in FIG. 4, the second voltage V2 is lower than the first voltage V1 as the second rotation speed N2 is lower than the first rotation speed N1. Therefore, as shown in FIG. 6(A), the slope KA is equal to or higher than the slope threshold value Kth. As a result, the main relays RM1 and RM2 are diagnosed as normal, and the driving force limit of the engine 31 is released at time t7, and the vehicle continues to run by the engine 31. As a result, the vehicle speed XA increases, and the vehicle resumes running.

[0066] On the other hand, FIG. 5 shows the transition of each value when the main relays RM1, RM2 have an on-failure. In this case, even if a cutoff command is output, the main relays RM1, RM2 are maintained in the closed state, and the path voltage VA is maintained at the power supply voltage VB of the battery 23. Furthermore, when the discharge of the smoothing capacitor 26 is stopped at time t6, the path voltage VA rises to the power supply voltage VB. Therefore, in the example shown in FIG. 5, the second voltage V2 has a value substantially equal to the first voltage V1, and as shown in FIG. 6(B), the slope KA becomes smaller than the slope threshold value Kth. As a result, the main relays RM1, RM2 are diagnosed as having an on-failure, and the vehicle is prohibited from traveling by the engine 31 at time t7 while the driving force limit of the engine 31 is maintained. Specifically, the driving of the engine 31 is stopped at time t7, and the vehicle is stopped from traveling at time t8.

[0067] According to the present embodiment described above in detail, the following effects can be obtained.

[0068] In this embodiment, when an abnormality occurs in the battery 23, the inverter 24, or the like while the main relays RM1, RM2 are in a closed state, a shutoff command is output to shut off the main relays RM1, RM2 while the control of the inverter 24 is stopped. In addition, a voltage difference ΔV, which is a difference in the path voltages VA according to a change in the rotation speed NA of the rotating electric machine 21 that occurs after the shutoff command is output, is acquired, and an ON-failure of the main relays RM1, RM2 is diagnosed based on the voltage difference ΔV. This makes it possible to appropriately diagnose an ON-failure of the main relays RM1, RM2. In addition, in this embodiment, an ON-failure of the main relays RM1, RM2 is diagnosed while the control of the inverter 24 is stopped, and a switch failure diagnosis can be realized with a simple configuration without causing a voltage change due to inverter control.

[0069] In this embodiment, the smoothing capacitor 26 is discharged under a condition where a drop in the rotation speed NA of the rotating electric machine 21 occurs after the output of the shutoff command. As a result, after the output of the shutoff command, the path voltage VA can be set to a voltage corresponding to the rotation speed NA of the rotating electric machine 21, and the on-fault of the main relays RM1, RM2 can be properly diagnosed.

[0070] In this embodiment, the smoothing capacitor 26 is discharged so that the route voltage VA becomes lower than the back electromotive voltage of the rotating electric machine 21 when the smoothing capacitor 26 finishes discharging. Therefore, it is possible to properly grasp the voltage change corresponding to the change in the rotation speed NA of the rotating electric machine 21, and thus to properly perform the fault diagnosis of the main relays RM1, RM2.

[0071] In this embodiment, when the vehicle speed XA is equal to or lower than a predetermined speed Xth, the rotating electric machine 21 is caused to discharge the smoothing capacitor 26. Therefore, even if the rotating electric machine 21 is caused to discharge the smoothing capacitor 26 while the rotating electric machine 21 is rotating, it is possible to suppress the rotation of the rotating electric machine 21 becoming unstable due to vibration of the rotating electric machine 21 caused by the back electromotive force of the rotating electric machine 21, and to suppress the influence on the running of the vehicle.

[0072] In this embodiment, when outputting a cutoff command for the main relays RM1 and RM2, the rotation speed NA of the rotating electric machine 21 is reduced by a reduction in the vehicle speed XA associated with the restriction of the engine driving force. This allows a desired voltage reduction to occur in the path voltage VA. In addition, when the main relays RM1 and RM2 are diagnosed as normal by the diagnostic process, the reduction in the vehicle speed XA is released by releasing the driving force restriction on the engine 31, so that the traveling speed of the vehicle can be appropriately controlled each time depending on whether the main relays RM1 and RM2 are normal or have an on-failure. Specifically, when the main relays RM1 and RM2 are normal, the driving force restriction on the engine 31 is released, allowing the vehicle to return to proper traveling. In addition, when the main relays RM1 and RM2 have an on-failure, the driving force restriction on the engine 31 is maintained, allowing the vehicle to be stopped safely.

[0073] <Second embodiment> The second embodiment will be described below with reference to Fig. 7, focusing on the differences from the first embodiment. The present embodiment differs from the first embodiment in that the diagnosis process diagnoses an on-fault of the main relays RM1, RM2 based on the power supply current IA in addition to the slope KA of the path voltage VA.

[0074] A flowchart of the diagnosis process in this embodiment is shown in Fig. 7. In Fig. 7, the same processes as those shown in Fig. 3 are denoted by the same step numbers for convenience, and the description thereof will be omitted.

[0075] In the diagnosis process of this embodiment, first, in steps S21 to S28, the slope KA of the path voltage VA (the ratio of the voltage difference ΔV of the path voltage VA to the amount of change ΔN in the rotation speed NA) is calculated, and it is determined whether the slope KA is equal to or greater than a slope threshold value Kth. If the determination in step S28 is affirmative, the process proceeds to step S29, where it is determined that the main relays RM1 and RM2 are normal.

[0076] On the other hand, if the determination in step S28 is negative, the process proceeds to step S41, where the power supply current (detected current) IA is acquired. At this time, the power supply current IA after the output of the cutoff command is acquired. In the following step S42, it is determined whether the absolute value of the power supply current IA acquired in step S41 is equal to or greater than the predetermined current value Ith. If the absolute value of the power supply current IA is less than the predetermined current value Ith, the process proceeds to step S29, where the main relays RM1 and RM2 are diagnosed as normal. On the other hand, if the absolute value of the power supply current IA is equal to or greater than the predetermined current value Ith, the process proceeds to step S31, where the main relays RM1 and RM2 are diagnosed as having an on-failure. The process in step S28 corresponds to the "first determination process", and the process in step S42 corresponds to the "second determination process". In addition, the slope threshold value Kth corresponds to the "voltage threshold value", and the predetermined current value Ith corresponds to the "current threshold value".

[0077] According to the present embodiment described above in detail, a determination using the slope KA and a determination using the power supply current IA are executed, and when it is determined that the slope KA is less than the slope threshold value Kth and the power supply current IA is determined to be equal to or greater than the predetermined current value Ith, the main relays RM1, RM2 are diagnosed as having an on-failure. By diagnosing the on-failure of the main relays RM1, RM2 using the slope KA and the power supply current IA, it is possible to properly perform the on-failure diagnosis of the main relays RM1, RM2 while suppressing erroneous diagnosis of an on-failure, compared to a case where the on-failure of the main relays RM1, RM2 is diagnosed using only the slope KA.

[0078] <Third embodiment> The third embodiment will be described below with reference to Figures 8 to 11, focusing on the differences from the second embodiment. In this embodiment, the difference from the second embodiment is that in the diagnosis process, the capacitor is discharged twice, and three combinations of the path voltage VA and the rotation speed NA are obtained in accordance with the capacitor discharge. Then, an approximate line LK that linearly approximates the relationship between the path voltage VA and the rotation speed NA is calculated using the three combinations of the path voltage VA and the rotation speed NA obtained, and an on-failure of the main relays RM1, RM2 is diagnosed based on the slope of the approximate line LK and the variation of the path voltage VA with respect to the approximate line LK.

[0079] A flowchart of the diagnosis process in this embodiment is shown in Fig. 8. In Fig. 8, the same processes as those shown in Fig. 7 are denoted by the same step numbers for convenience, and the description thereof will be omitted.

[0080] In the diagnosis process of this embodiment, when the second voltage V2 and the second rotation speed N2 are acquired in step S25, the process proceeds to step S51, and it is determined whether or not the second rotation speed N2 acquired in step S25 is sufficiently small. Specifically, it is determined whether or not the second rotation speed N2 is smaller than a reference rotation speed NK. This reference rotation speed NK is set to a rotation speed lower than a predetermined rotation speed Nth used in determining whether or not to discharge the smoothing capacitor 26 in the first discharge of the smoothing capacitor 26. If the second rotation speed N2 is smaller than the reference rotation speed NK, the process proceeds to step S26. That is, the gradient KA of the path voltage VA is calculated from the combination of the first voltage V1 and the first rotation speed N1 and the combination of the second voltage V2 and the second rotation speed N2, and the on-failure of the main relays RM1 and RM2 is diagnosed. The combination of the first voltage V1 and the first rotation speed N1 corresponds to the "first data", and the combination of the second voltage V2 and the second rotation speed N2 corresponds to the "second data".

[0081] On the other hand, if the second rotation speed N2 is greater than the reference rotation speed NK, the process proceeds to step S52, where the smoothing capacitor 26 is discharged for a predetermined period after waiting for the rotation speed NA of the rotating electric machine 21 to drop from the second rotation speed N2 by a predetermined value or more. That is, the smoothing capacitor 26 is discharged for the second time. In the following step S53, the path voltage VA and the rotation speed NA are acquired after the path voltage VA becomes stable after the discharge of the smoothing capacitor 26 in step S52. Hereinafter, the path voltage VA and the rotation speed NA acquired in step S53 are referred to as the third voltage V3 and the third rotation speed N3. The combination of the third voltage V3 and the third rotation speed N3 corresponds to the "third data."

[0082] In step S54, the slope KA and variation ΔK of the path voltage VA are calculated using the detection values ​​V1, V2, V3, N1, N2, and N3. Specifically, an approximate line LK is calculated by linearly approximating the relationship between the path voltages V1 to V3 and the rotation speeds N1 to N3, and the slope of the approximate line LK is calculated as the slope KA of the path voltage VA. The approximate line LK is calculated, for example, by the least squares method. In addition, the variation of the path voltages V1 to V3 with respect to the approximate line LK is calculated as the variation ΔK. The variation ΔK of the path voltages V1 to V3 with respect to the approximate line LK is, for example, the total value of the voltage deviation amount (voltage difference) of each of the path voltages V1 to V3 with respect to the approximate line LK.

[0083] In step S55, it is determined whether the slope KA calculated in step S54 is equal to or greater than the slope threshold Kth. If the slope KA is equal to or greater than the slope threshold Kth, the process proceeds to step S29, where the main relays RM1 and RM2 are diagnosed as normal. On the other hand, if the slope KA is less than the slope threshold Kth, the process proceeds to step S56.

[0084] In step S56, it is determined whether the variation ΔK calculated in step S54 is equal to or less than a predetermined variation threshold ΔKth. If the variation ΔK is greater than the variation threshold ΔKth, the reliability of the slope KA calculated in step S54 is low, and the accuracy of the determination result in step S55 is low, so the process proceeds to step S29, where it is determined that the main relays RM1 and RM2 are normal. On the other hand, if the variation ΔK is equal to or less than the variation threshold ΔKth, the reliability of the slope KA calculated in step S54 is high, and the accuracy of the determination result in step S55 is high, so the process proceeds to step S41.

[0085] Next, the procedure of the diagnosis process will be described with reference to Figures 9 and 10. (A) to (G) in Figures 9 and 10 are the same as (A) to (G) in Figures 4 and 5. In Figures 9 and 10, the process from time t1 to t6 is the same as Figures 4 and 5, and therefore a duplicated description will be omitted.

[0086] In Fig. 9, the main relays RM1 and RM2 are assumed to be normal, and when the second voltage V2 and the second rotation speed N2 are acquired at time t6, it is determined whether or not the second rotation speed N2 is greater than the reference rotation speed NK. In the example shown in Fig. 9, the second rotation speed N2 is greater than the reference rotation speed NK. Therefore, when the rotation speed NA of the rotating electric machine 21 decreases from the second rotation speed N2 by a predetermined value at time t11, the smoothing capacitor 26 is discharged for a predetermined period from time t11 to t12. When the discharge of the smoothing capacitor 26 is stopped at time t12, and the path voltage VA rises to the back electromotive voltage of the rotating electric machine 21 at time t13, the third voltage V3 and the third rotation speed N3 are acquired.

[0087] When the third voltage V3 and the third rotation speed N3 are acquired, the slope KA and the variation ΔK of the path voltage VA are calculated using the respective detection values ​​V1, V2, V3, N1, N2, and N3. In FIG. 9, the path voltages V1 to V3 decrease with the decrease in the rotation speeds N1 to N3. Therefore, as shown in FIG. 11(A), the slope KA is equal to or greater than the slope threshold Kth. In addition, the path voltages VA and the rotation speeds NA of the three combinations are located near the approximation line LK, and the variation ΔK with respect to the approximation line LK is equal to or less than the variation threshold ΔKth. Therefore, the main relays RM1 and RM2 are diagnosed as normal based on the slope KA and the variation ΔK of the path voltage VA.

[0088] Even if the main relays RM1 and RM2 are normal, the path voltage VA may change due to a detection error or noise of the voltage sensor 27, and for example, the third voltage V3 may become a voltage value larger than the slope of the second voltage V2. In this case, as shown in FIG. 11B, the slope KA is less than the slope threshold Kth. On the other hand, the path voltages VA and the rotation speeds NA of the three combinations are separated from the approximate straight line LK, and the variation ΔK calculated as the sum of the voltage deviation amount VS1 of the first voltage V1 with respect to the approximate straight line LK, the voltage deviation amount VS2 of the second voltage V2 with respect to the approximate straight line LK, and the voltage deviation amount VS3 of the third voltage V3 with respect to the approximate straight line LK becomes larger than the variation threshold ΔKth. In other words, even if the slope KA is less than the slope threshold Kth, the reliability of the slope KA is low, and therefore the main relays RM1 and RM2 are diagnosed as normal. This makes it possible to suppress erroneous diagnosis of an on-failure and properly perform on-failure diagnosis of the main relays RM1 and RM2.

[0089] On the other hand, Fig. 10 shows the transition of each value when the main relays RM1, RM2 have an on-failure. In this case, when the discharge of the smoothing capacitor 26 is stopped at time t12, the route voltage VA rises to the power supply voltage VB, and the third voltage V3 has substantially the same value as the first voltage V1 and the second voltage V2. Therefore, as shown in Fig. 11(C), the slope KA is less than the slope threshold Kth. In addition, the route voltage VA and the rotation speed NA of the three combinations are located near the approximation line LK, and the variation ΔK with respect to the approximation line LK is equal to or less than the variation threshold ΔKth. Therefore, based on the slope KA and variation ΔK of the route voltage VA, the main relays RM1, RM2 are diagnosed as having an on-failure.

[0090] According to the present embodiment described above in detail, the following effects can be obtained.

[0091] In this embodiment, in a situation where a drop in the rotation speed NA of the rotating electric machine 21 occurs after output of an interruption command for the main relays RM1, RM2, the smoothing capacitor 26 is discharged multiple times, and an approximation line LK is calculated from the rotation speed NA and the path voltage VA acquired for each capacitor discharge. Also, an on-fault of the main relays RM1, RM2 is diagnosed based on a slope KA of the approximation line LK and a variation ΔK of the path voltage VA with respect to the approximation line LK. In this case, the reliability of the slope KA of the approximation line LK can be determined based on the variation ΔK, and an erroneous diagnosis of an on-fault of the main relays RM1, RM2 can be suppressed, and an on-fault of the main relays RM1, RM2 can be properly diagnosed.

[0092] When discharging the smoothing capacitor 26 multiple times and diagnosing an on-fault of the main relays RM1, RM2 based on an approximation line LK calculated from the rotation speed NA and the path voltage VA for each capacitor discharge and a variation ΔK of the path voltage VA with respect to the approximation line LK, it is possible to improve the accuracy of the fault diagnosis, but there is a concern that the fault diagnosis takes time because multiple capacitor discharges are required. Also, when the rotating electric machine 21 is in a low rotation state, it is considered that a change in the rotation speed from that point on cannot be expected.

[0093] In this regard, in the present embodiment, if the second rotation speed N2 acquired after the first capacitor discharge is higher than the reference rotation speed NK, the three combinations of rotation speeds NA and route voltages VA are used to diagnose the ON faults of the main relays RM1, RM2, whereas if the second rotation speed N2 is lower than the reference rotation speed NK, the first voltage V1 and the first rotation speed N1 and the second voltage V2 and the second rotation speed N2 are used to diagnose the ON faults of the main relays RM1, RM2. This makes it possible to perform an appropriate fault diagnosis while taking into account the rotation state of the rotating electric machine 21.

[0094] <Fourth embodiment> In this embodiment, a power supply system mounted on a propeller-type electric flying object will be described. Fig. 12 is a schematic diagram showing the configuration of a control system 60 as a power supply system for the flying object in this embodiment. In Fig. 12, the control system 60 has a battery 61, multiple propeller units 70, and a control device 80. The battery 61 is the power source for the flying object, and supplies power to each propeller unit 70 via a power line 62. The flying object flies with the rotation of the propeller 71 of each propeller unit 70. In this embodiment, the flying object corresponds to a "moving object."

[0095] The propeller unit 70 includes a propeller 71, a rotating electric machine 72 that rotates the propeller 71, an inverter 73 that adjusts the input and output of power to the rotating electric machine 72, and a power switch 75 provided on a positive power supply path 74 extending from the power line 62. The rotating electric machine 72 is a rotating electric machine having a multi-phase stator winding, similar to the rotating electric machine 21 described above, and the inverter 73 is a power conversion circuit having a plurality of switching elements for each phase, similar to the inverter 24 described above. The power switch 75 constitutes a main relay, and switching between a conducting state and a non-conducting state between the battery 61 and the inverter 73 is performed by turning the power switch 75 on and off. In each propeller unit 70, a smoothing capacitor 76 and a voltage sensor 77 are connected to the inverter 73 side of the power switch 75. The voltage sensor 77 detects the voltage across the positive power supply path 74 as a path voltage VA.

[0096] In Fig. 12, the power switch 75 is provided only in the positive path out of the positive and negative paths, but the power switch 75 may be provided in both the positive path and the negative path. Also, although not shown in Fig. 12, a series connection of a precharge relay and a resistor may be connected in parallel to the power switch 75 (see Fig. 1).

[0097] Although not shown, each propeller unit 70 has a current sensor that detects the power supply current flowing through the positive power supply path 74, and a rotation speed sensor that detects the number of rotations NA per unit time of the rotating electric machine 72, i.e., the rotational speed.

[0098] Each propeller unit 70 has the same configuration, and is individually controlled by the control device 80. The control device 80 appropriately controls the open / closed state of the power switch 75 in each propeller unit 70, controls the rotation of the propeller 71, etc., based on flight requirements and detection information from each of the above-mentioned sensors.

[0099] The flying object of this embodiment is capable of flying in the vertical direction and the horizontal direction. For example, the flying object moves in the vertical direction during takeoff and landing, and moves in the horizontal direction during movement to the destination. In this case, each propeller unit 70 may be used according to the flight situation, and the propeller units 70 may include a propeller unit 70 for vertical flight and a propeller unit 70 for horizontal flight. The propeller unit 70 for vertical flight may also be called a propeller unit 70 for takeoff and landing. However, it is also possible to drive the propeller unit 70 for vertical flight and the propeller unit 70 for horizontal flight simultaneously. For example, in the propeller unit 70 for vertical flight, the rotation axis of the propeller 71 may be provided in a direction extending in the vertical direction or in a substantially vertical direction, and in the propeller unit 70 for horizontal flight, the rotation axis of the propeller 71 may be provided in a direction extending in the horizontal direction or in a substantially horizontal direction.

[0100] The propeller unit 70 for vertical flight may have a different maximum output from the propeller unit 70 for horizontal flight. For example, the propeller unit 70 for vertical flight may have a relatively large maximum output, and the propeller unit 70 for horizontal flight may have a relatively small maximum output. However, the opposite is also possible.

[0101] The flying object is capable of flying with the propellers 71 of some of the propeller units 70 among the multiple propeller units 70 being driven to rotate, and during takeoff, landing, and low-speed flight, the flying object is capable of flying with only the rotation of some of the propellers 71. Furthermore, if an abnormality occurs in some of the propeller units 70 in the flying object, the rotation of the propeller 71 in that abnormal propeller unit 70 is stopped, and the flying object can continue flying with the rotation of the propellers 71 in the remaining propeller units 70.

[0102] Furthermore, the control device 80 has a function of diagnosing a fault in the power switch 75 when a predetermined switch diagnosis condition is met. For example, when the rotation of the propellers 71 in some of the propeller units 70 is stopped during flight of the aircraft, in other words, when the rotation of the propellers 71 in the propeller units 70 in the driven state becomes unnecessary, it is determined that the switch diagnosis condition is met for that propeller unit 70, and a fault diagnosis of the power switch 75 is performed.

[0103] More specifically, when the aircraft transitions from a takeoff state to a horizontal flight state, the propeller unit 70 for vertical flight is stopped from the driven state. At this time, it is preferable that the switch diagnosis condition is satisfied for the propeller unit 70 for vertical flight, and the propeller unit 70 is set as the target of the fault diagnosis. Alternatively, when the aircraft transitions from a horizontal flight state to a landing state, the propeller unit 70 for horizontal flight is stopped from the driven state. At this time, it is preferable that the switch diagnosis condition is satisfied for the propeller unit 70 for horizontal flight, and the propeller unit 70 is set as the target of the fault diagnosis. In addition, when the flight speed of the aircraft is reduced, some of the propeller units 70 that are being driven are stopped. At this time, it is preferable that the switch diagnosis condition is satisfied for the propeller unit 70 to be stopped, and the propeller unit 70 is set as the target of the fault diagnosis. The propeller unit 70 to be diagnosed does not have to be one, and it is also possible to simultaneously diagnose two or more propeller units 70.

[0104] In addition, when an overcurrent flows through the positive power supply path 74 in each propeller unit 70 due to an abnormality in the inverter 73 or the like, it is possible to determine that the switch diagnosis condition is met and perform a fault diagnosis of the power supply switch 75.

[0105] In this embodiment, when the power switch 75 is in a closed state (conducting state) and a switch diagnosis condition is satisfied, a shutoff command is output to shut off the power switch 75 with control of the inverter 73 stopped. In addition, in a situation in which a change in the rotation speed NA of the rotating electric machine 72 occurs after the output of the shutoff command, a voltage difference ΔV in the path voltage VA before and after the change in the rotation speed NA is obtained, and an on-failure of the power switch 75 is diagnosed based on the voltage difference ΔV.

[0106] A flowchart of the control process of this embodiment is shown in Fig. 13. The control device 80 repeatedly executes this control process for each propeller unit 70 at a predetermined cycle while the aircraft is flying.

[0107] When the control process is started, in step S61, it is determined whether or not the diagnostic conditions are satisfied for the propeller unit 70 to be diagnosed this time, and if the diagnostic conditions are satisfied, the process proceeds to the following step S62. In step S62, the control of the inverter 73 is stopped. This stops the powering of the propeller 71 by the rotating electric machine 72, and the propeller rotation speed starts to gradually decrease, and the rotation speed of the rotating electric machine 72 decreases. At this time, the rotation speed of the propeller 71 gradually decreases with a predetermined inertial force. Alternatively, the propeller 71 may rotate by inertia due to the wind received after the powering drive is stopped. In the following step S63, a shutoff command is output to shut off the power switch 75.

[0108] Then, in step S64, the path voltage (detected voltage) VA is acquired as the first voltage V11 in the propeller unit 70, and the rotation speed NA is acquired as the first rotation speed N11. At this time, it is preferable that the first voltage V11 and the first rotation speed N11 are acquired after the path voltage VA becomes stable after the output of the shutoff command.

[0109] Thereafter, in step S65, while the rotating electric machine 72 is rotating, the smoothing capacitor 76 is discharged for a predetermined period. At this time, the smoothing capacitor 76 is discharged for a period longer than the period required for the path voltage VA to decrease to the electromotive force voltage (counter electromotive voltage) due to the counter electromotive force of the rotating electric machine 72. This discharge causes the path voltage VA to decrease below the counter electromotive voltage of the rotating electric machine 72. In step S65, the capacitor discharge may be performed on the condition that the rotation speed of the rotating electric machine 72 is equal to or lower than a predetermined value. In other words, the capacitor discharge may be performed on the condition that the rotation speed of the rotating electric machine 72 is such that the counter electromotive voltage is smaller than the predetermined voltage.

[0110] In step S66, the path voltage VA after the capacitor discharge is acquired as the second voltage V12, and the rotation speed NA is acquired as the second rotation speed N12. At this time, the second voltage V12 and the second rotation speed N12 are preferably acquired after the transient change in the path voltage VA has converged. In step S67, the difference between the first rotation speed N11 and the second rotation speed N12 is calculated as the change amount ΔN in the rotation speed NA, and the difference between the first voltage V11 and the second voltage V12 is calculated as the voltage difference ΔV in the path voltage VA.

[0111] Then, in step S68, it is determined whether or not the power switch 75 has an on-failure based on the change in rotation speed and voltage before and after the capacitor discharge. If it is determined that the power switch 75 does not have an on-failure (i.e., the power switch 75 is normal), this process ends, but if it is determined that the power switch 75 has an on-failure, the process proceeds to step S69.

[0112] Specifically, in step S68, the slope KA of the change in the path voltage VA before and after the change in the rotation speed NA is calculated from the amount of change ΔN in the rotation speed NA and the voltage difference ΔV in the path voltage VA, and based on the slope KA, it is determined whether the power switch 75 has an on-failure. If the slope KA is equal to or greater than a predetermined value, the power switch 75 is deemed to be normal, and the process is terminated. If the slope KA is less than the predetermined value, the power switch 75 is deemed to have an on-failure, and the process proceeds to step S69.

[0113] In step S69, the malfunction information for the currently diagnosed propeller unit 70 is stored in memory, and then the process ends. After that, it is preferable to prohibit the use of the currently diagnosed propeller unit 70.

[0114] In this embodiment, when some of the propeller units 70 are stopped during flight of the aircraft, and a cut-off command is output for the propeller units 70 to be stopped, a power command for maintaining the flying state of the aircraft is output to the other propeller units 70 to which the cut-off command has not been output. Specifically, the control device 80 executes the process of FIG. 14. This process may be rewritten as the process of FIG. 13 and executed.

[0115] In FIG. 14, in step S71, it is determined whether or not the diagnostic condition is satisfied for the propeller unit 70 to be diagnosed this time, and if the diagnostic condition is satisfied, the process proceeds to the following step S72. In step S72, a power command value required for the propeller unit 70 not to be diagnosed to maintain flight of the aircraft is calculated, and the power command value is output to the propeller unit 70 being driven. In addition, in step S73, control of the inverter 73 is stopped for the propeller unit 70 to be diagnosed this time. As a result, the propeller speed is reduced in the propeller unit 70 to be diagnosed this time, while the flight of the aircraft can be continued by driving the propeller units 70 other than that propeller unit 70.

[0116] Thereafter, in step S74, a shutoff command is output to shut off the power switch 75, and in the following step S75, a diagnosis is made for an on-failure of the power switch 75. At this time, it is preferable that the same processes as steps S64 to S68 in FIG. 13 are performed.

[0117] Then, in step S76, it is determined whether the power switch 75 is normal. If it is determined that the power switch 75 is normal, the process proceeds to step S77. In step S77, it is determined whether there is a request to increase the propeller rotation speed of the currently diagnosed propeller unit 70. If it is determined that there is a request to increase the propeller rotation speed, the process proceeds to step S78, where the power command value of each propeller unit 70 in a state in which the currently diagnosed propeller unit 70 is re-driven is calculated again, and the power command value is output to each propeller unit 70. In the following step S79, the drive of the currently diagnosed propeller unit 70 is resumed. Note that, if it is determined in step S77 that there is no request to increase the propeller rotation speed of the currently diagnosed propeller unit 70, the process ends as it is.

[0118] If the power switch 75 has an ON failure and the result in step S76 is negative, the process proceeds to step S80. In step S80, the use of the propeller unit 70 currently being diagnosed is prohibited, and then the process ends.

[0119] As described above, the present embodiment can provide the following excellent effects.

[0120] In an aircraft, when a command to turn off the power switch 75 is output, the propeller rotation speed decreases along with the rotation speed of the rotating electric machine 72, thereby causing the desired voltage drop required for fault diagnosis of the power switch 75 on the inverter 73 side.

[0121] In addition, if the power switch 75 is determined to be normal and there is a request to increase the propeller rotation speed, the reduced rotation speed state of the propeller 71 is released. This allows the flight of the aircraft to be suitably restored to the flight state before the diagnosis after the failure diagnosis of the power switch 75.

[0122] When some of the propeller units 70 are stopped from a driven state during flight of an aircraft equipped with multiple propeller units 70, it is determined that the switch diagnosis conditions are satisfied for the propeller units 70 to be stopped, and a shutoff command is output. In this case, the success or failure of the diagnosis conditions is determined according to the flight state of the aircraft, for example, the timing when the aircraft transitions from a takeoff state to a horizontal flight state, and a shutoff command for the power switch 75 is output. Therefore, a fault diagnosis can be performed on the propeller units 70 that are stopped from being driven, without affecting the flight status of the aircraft.

[0123] When the drive of some of the propeller units 70 is stopped during flight of the aircraft, and a cut-off command is output for the propeller units 70 to be stopped, a power command value for maintaining the moving state of the aircraft is output to the other propeller units 70 to which the cut-off command has not been output. As a result, when the drive of any of the multiple propeller units 70 is stopped in order to perform a fault diagnosis of the propeller unit 70, the flight state of the aircraft is maintained without change before and after the drive is stopped. As a result, a fault diagnosis of the propeller units 70 can be performed without affecting the flight status of the aircraft.

[0124] In the fourth embodiment, an aircraft is assumed as the moving body, and a plurality of propeller units 70 are assumed as the plurality of drive units, but this configuration may be changed. For example, an electric vehicle may be assumed as the moving body, and a plurality of wheel units may be assumed as the plurality of drive units. The wheel units may be, for example, in-wheel motors in which a rotating electric machine is integrated into a wheel. In this case, the electric vehicle is enabled to run by driving some of the wheel units among all the wheel units. For example, the electric vehicle may have a front wheel unit and a rear wheel unit, and be enabled to run by driving at least one of the front and rear wheel units.

[0125] When the control device stops some of the wheel units in a driven state while the electric vehicle is traveling, the control device determines that the switch diagnosis condition is satisfied for the wheel unit to be stopped, and outputs a power switch cut-off command.The control device then obtains a voltage difference, which is the difference between the detected voltages according to the change in the rotation speed of the rotating electric machine that occurs after the cut-off command is output, and diagnoses an on-failure of the power switch based on the voltage difference.

[0126] In addition, when some of the wheel units are stopped while the electric vehicle is traveling and a cut-off command is output for the wheel units to be stopped, it is preferable to output a power command to maintain the traveling state of the electric vehicle to the other wheel units to which the cut-off command has not been output.

[0127] <Other embodiments> Each of the above embodiments may be modified as follows.

[0128] In the above embodiment, for example, a configuration is shown in which the slope KA of the path voltage VA is used to diagnose an on-failure of the main relays RM1, RM2, but this is not limiting. For example, the voltage difference ΔV of the path voltage VA before and after a change in the rotation speed NA may be used to diagnose an on-failure of the main relays RM1, RM2. Specifically, the on-failure of the main relays RM1, RM2 may be diagnosed based on whether or not the voltage difference ΔV of the path voltage VA before and after a change in the rotation speed NA is equal to or greater than a predetermined voltage difference threshold ΔVth. In this case, when the amount of change ΔN of the rotation speed NA before and after the change in the rotation speed NA is large, the voltage difference threshold ΔVth may be set to be larger than when it is small.

[0129] In the second embodiment, an example is shown in which the on-failure of the main relays RM1 and RM2 is diagnosed based on the gradient KA of the path voltage VA and the power supply current IA after the output of the cutoff command, but the present invention is not limited to this. Furthermore, the power supply current IA before the output of the cutoff command may be acquired, and the on-failure of the main relays RM1 and RM2 may be diagnosed using the current change between the power supply current IA before the output of the cutoff command and the power supply current IA after the output of the cutoff command. Specifically, when the gradient KA of the path voltage VA is less than the gradient threshold Kth and the absolute value of the power supply current IA after the output of the cutoff command is equal to or greater than a predetermined current value Ith, it may be further determined whether or not the current change of the power supply current IA before and after the output of the cutoff command is greater than a predetermined change threshold. Then, when the current change is smaller than the change threshold, it is preferable to diagnose that the main relays RM1 and RM2 have an on-failure. Furthermore, when the current change is greater than the change threshold, it is preferable to diagnose that the main relays RM1 and RM2 are normal.

[0130] In the third embodiment, an example was shown in which the combination of the path voltage VA and the rotation speed NA was obtained three times, but the number of times the combination of the path voltage VA and the rotation speed NA was obtained is not limited to three, and may be four or more times. In this case, when the number of times the combination of the path voltage VA and the rotation speed NA is obtained is large, the variation threshold value ΔKth may be set to be large compared to when the number of times is small.

[0131] In the above first to third embodiments, the method of limiting the driving force of the engine 31 has been exemplified as a method of reducing the rotation speed NA of the rotating electric machine 21 after the output of a discharge command, but the present invention is not limited to this. For example, the gear mechanism 34 may be configured to be able to change the gear ratio GA of the rotating shaft 22 with respect to the axle 51, and the gear ratio GA of the rotating shaft 22 with respect to the axle 51 may be increased when the rotation speed NA is reduced. In this embodiment, the axle 51 corresponds to the "rotation transmission path."

[0132] A flowchart of diagnostic processing in another embodiment is shown in Fig. 15. In Fig. 15, the same processes as those shown in Fig. 3 are denoted by the same step numbers for convenience, and descriptions thereof will be omitted.

[0133] In this embodiment, the first voltage V1 and the first rotation speed N1 are obtained in step S22 without limiting the driving force of the engine 31, and the process proceeds to step S91. In step S91, the gear ratio GA is increased while the vehicle is traveling after the output of the shutoff command. The increase in the gear ratio GA reduces the rotation speed NA of the rotating electric machine 21. In the following step S25, the second voltage V2 and the second rotation speed N2 are obtained. Therefore, in step S26, a voltage difference ΔV in the path voltage VA before and after the increase in the gear ratio GA is calculated. In this embodiment, the process of step S91 corresponds to a "gear ratio adjustment unit."

[0134] In this embodiment, since the rotation speed NA of the rotary electric machine 21 can be reduced while suppressing a decrease in the vehicle speed XA, it is possible to reduce the occurrence of an uncomfortable feeling caused by deceleration while the vehicle is traveling.

[0135] The switch diagnosis condition is not limited to the occurrence of a specific abnormality. For example, when periodically diagnosing an ON failure of a power switch, the establishment of a periodic diagnosis condition, such as the lapse of a predetermined diagnosis period, may be regarded as the switch diagnosis condition.

[0136] Furthermore, in addition to the occurrence of a specific abnormality, the satisfaction of a periodic diagnosis condition may be regarded as a switch diagnosis condition. In this case, when the diagnosis process is executed on the condition that a specific abnormality has occurred, it is preferable to maintain the prohibition of the vehicle from being driven by the rotating electric machine 21 even if the main relays RM1 and RM2 are diagnosed as normal in step S16 of the diagnosis process. On the other hand, when the diagnosis process is executed on the condition that a periodic diagnosis condition has been satisfied, the prohibition of the vehicle from being driven by the rotating electric machine 21 may be lifted if the main relays RM1 and RM2 are diagnosed as normal in step S16 of the diagnosis process. This makes it possible to switch whether or not to permit the vehicle to be driven by the rotating electric machine 21 depending on the type of the switch diagnosis condition.

[0137] When the present invention is realized as an on-board power supply system, it can be applied to a hybrid vehicle that can run independently using the engine 31 and rotates together with the rotating electric machine 21 and the wheels 50. In this case, the connection structure between the engine 31 and the rotating electric machine 21 in the hybrid vehicle is not limited to the above embodiment, and the present invention can be applied to a hybrid vehicle having a well-known connection structure.

[0138] The diagnostic apparatus and the method described herein may be implemented by a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the diagnostic apparatus and the method described herein may be implemented by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the diagnostic apparatus and the method described herein may be implemented by one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. The computer program may also be stored in a computer-readable non-transitory tangible recording medium as instructions executed by the computer.

[0139] The technical ideas extracted from the above-described embodiments will be described below. [Configuration 1] Power supply (23,61) and an inverter (24, 73) connected to the power supply; a rotating electric machine (21, 72) connected to the inverter; a power switch (RM1, RM2, 75) provided in a power path between the power source and the inverter; a voltage sensor (27, 77) for detecting a path voltage which is a voltage of the power supply path on the inverter side relative to the power supply switch; The present invention is applied to a power supply system (10, 60) having a shutoff command unit that outputs a shutoff command to shut off the power switch while stopping control of the inverter when a predetermined switch diagnosis condition is satisfied in a conductive state of the power switch; an acquisition unit that acquires a voltage difference that is a difference between the detected voltages of the voltage sensors in response to a change in the rotation speed of the rotating electric machine after the shutdown command unit outputs the shutdown command; a diagnosis unit that diagnoses an on-failure of the power switch based on the voltage difference; A diagnostic device (40, 80) comprising: [Configuration 2] In the power supply system, a smoothing capacitor (26, 76) is connected in parallel to the power supply in the power supply path on the inverter side relative to the power switch, a discharge processing unit that discharges the smoothing capacitor in a situation where a decrease in the rotation speed occurs after the cutoff command is output by the cutoff command unit, The diagnostic device according to configuration 1, wherein the acquisition unit acquires, as the voltage difference, a difference between the detected voltage before the discharge processing unit discharges the smoothing capacitor and the detected voltage after the discharge processing unit discharges the smoothing capacitor in a situation in which a decrease in the rotation speed occurs after the output of the shut-off command. [Configuration 3] 3. The diagnostic device according to claim 2, wherein the discharge processing unit discharges the smoothing capacitor so that the path voltage becomes lower than an electromotive force voltage of the rotating electric machine when the discharge of the smoothing capacitor ends. [Configuration 4] The discharge processing unit enables discharging of the smoothing capacitor multiple times under a situation in which a decrease in the rotation speed occurs after the output of the cutoff command, the acquisition unit acquires the rotation speed and the path voltage before a first discharge of the smoothing capacitor and after each subsequent discharge of the smoothing capacitor when the smoothing capacitor is discharged a plurality of times; The diagnostic device according to configuration 2 or 3, wherein the diagnosing unit calculates an approximation line that linearly approximates a relationship between the rotation speed and the path voltage using three or more combinations of the rotation speed and the path voltage acquired by the acquiring unit, and diagnoses an on-failure of the power switch based on a slope of the approximation line and a variation of the path voltage with respect to the approximation line. [Configuration 5] the acquisition unit acquires, under a circumstance in which a decrease in the rotation speed occurs after the output of the shutoff command, the rotation speed and the path voltage before and after a first capacitor discharge by the discharge processing unit as first data and second data, respectively, and acquires the rotation speed and the path voltage after a subsequent second capacitor discharge as third data; The diagnostic device according to configuration 4, wherein the diagnostic unit acquires the first to third data and diagnoses an on-failure of the power switch using the first to third data if the rotation speed of the rotating electric machine is higher than a predetermined value at the time when the second data is acquired, and acquires the first and second data of the first to third data and diagnoses an on-failure of the power switch using the first and second data if the rotation speed of the rotating electric machine is lower than a predetermined value at the time when the second data is acquired. [Configuration 6] The power supply system includes a current sensor (28) that detects a power supply current that is a current flowing through the power supply, The acquisition unit acquires a detected current of the current sensor after the shutdown command is output by the shutdown command unit, The diagnosis unit includes: a first determination process for determining whether the voltage difference is greater than a predetermined voltage threshold, and a second determination process for determining whether the detected current is greater than a predetermined current threshold, The diagnostic device according to any one of configurations 1 to 5, wherein when the first determination process determines that the voltage difference is smaller than the voltage threshold value and when the second determination process determines that the detected current is larger than the current threshold value, the diagnostic device diagnoses that the power switch has an on-failure. [Configuration 7] the power supply system is mounted on a vehicle in which the rotating electric machine is capable of rotating in accordance with rotation of wheels (50); The diagnostic device according to any one of configurations 1 to 6, further comprising a speed control unit that, when the shutoff command is output by the shutoff command unit, reduces the vehicle's traveling speed to reduce the rotation speed of the rotating electric machine, and, when the diagnostic unit determines that the power switch is normal, cancels the reduced state of the traveling speed. [Configuration 8] the power supply system is mounted on a vehicle having a gear mechanism (34) that varies a gear ratio in a rotation transmission path between wheels (50) and the rotating electric machine, a gear ratio adjusting unit that increases a gear ratio of the rotating electric machine side to the wheel side during vehicle traveling after the cutoff command is output by the cutoff command unit, The diagnostic device according to any one of configurations 1 to 6, wherein the acquisition unit acquires, as the voltage difference, a difference between the detected voltage before the gear ratio is increased by the gear ratio adjustment unit and the detected voltage after the gear ratio is increased. [Configuration 9] the power supply system rotates a propeller (71) using the rotating electric machine in an aircraft that flies in accordance with the rotation of the propeller, The diagnostic device according to any one of configurations 1 to 6, further comprising a propeller rotation control unit that reduces the rotation speed of the rotating electric machine together with the rotation speed of the propeller when the shutdown command is output by the shutdown command unit. [Configuration 10] The diagnostic device according to configuration 9, wherein the propeller rotation control unit releases the reduced state of the propeller rotation speed when, after the shutoff command is output and the diagnosis unit has performed, it is determined that the power switch is normal and there is a request to increase the propeller rotation speed. [Configuration 11] The power supply system is applied to a moving body including a plurality of drive units each including the inverter, the rotating electric machine, the power switch, and the voltage sensor, and the moving body is capable of moving by driving some of all of the drive units; The diagnostic device according to any one of configurations 1 to 6, wherein when some of the plurality of drive units in a driving state are to be stopped while the moving body is moving, the cut-off command unit determines that the switch diagnosis condition is satisfied for the drive unit to be stopped, and outputs the cut-off command. [Configuration 12] The diagnostic device of configuration 11 further comprises a power control unit that outputs a power command value for maintaining the moving state of the moving body to the other drive units to which the shutdown command has not been output when the drive of some of the drive units is stopped while the moving body is moving and when the shutdown command unit outputs the shutdown command for the drive units to be stopped. [Explanation of symbols]

[0140] 10...control system, 23...battery, 24...inverter, 27...voltage sensor, 40...control device, RM1...first main relay, RM2...second main relay.

Claims

1. A power source (23, 61); an inverter (24, 73) connected to the power supply; A rotating electric machine (21, 72) connected to the inverter; a power switch (RM1, RM2, 75) provided in a power path between the power supply and the inverter; a voltage sensor (27, 77) for detecting a path voltage which is a voltage of the power supply path on the inverter side relative to the power supply switch; The present invention is applied to a power supply system (10, 60) including: a shutoff command unit that outputs a shutoff command to shut off the power switch while stopping control of the inverter when a predetermined switch diagnosis condition is satisfied in a conductive state of the power switch; an acquisition unit that acquires a voltage difference that is a difference between the detected voltages of the voltage sensors in response to a change in the rotation speed of the rotating electric machine after the shutdown command unit outputs the shutdown command; a diagnosis unit that diagnoses an on-failure of the power switch based on the voltage difference; A diagnostic device (40, 80) comprising:

2. In the power supply system, a smoothing capacitor (26, 76) is connected in parallel to the power supply in the power supply path on the inverter side relative to the power switch, a discharge processing unit that discharges the smoothing capacitor in a situation where a decrease in the rotation speed occurs after the cutoff command is output by the cutoff command unit, 2. The diagnostic device according to claim 1, wherein the acquisition unit acquires, as the voltage difference, a difference between the detected voltage before the discharge of the smoothing capacitor by the discharge processing unit and the detected voltage after the discharge of the smoothing capacitor in a situation in which a decrease in the rotation speed occurs after the output of the shut-off command.

3. 3. The diagnostic device according to claim 2, wherein the discharge processing unit discharges the smoothing capacitor so that the path voltage becomes lower than an electromotive force voltage of the rotating electric machine when the discharge of the smoothing capacitor ends.

4. The discharge processing unit enables discharging of the smoothing capacitor multiple times under a situation in which a decrease in the rotation speed occurs after the output of the interruption command, the acquisition unit acquires the rotation speed and the path voltage before a first discharge of the smoothing capacitor and after each subsequent discharge of the smoothing capacitor when the smoothing capacitor is discharged a plurality of times; 3. The diagnostic device according to claim 2, wherein the diagnosing unit calculates an approximation line that linearly approximates a relationship between the rotation speed and the path voltage using three or more combinations of the rotation speed and the path voltage acquired by the acquisition unit, and diagnoses an on-failure of the power switch based on a slope of the approximation line and a variation of the path voltage with respect to the approximation line.

5. the acquisition unit acquires, under a circumstance in which a decrease in the rotation speed occurs after the output of the shutoff command, the rotation speed and the path voltage before and after a first capacitor discharge by the discharge processing unit as first data and second data, respectively, and acquires the rotation speed and the path voltage after a subsequent second capacitor discharge as third data; 5. The diagnostic device according to claim 4, wherein if the rotation speed of the rotating electric machine is higher than a predetermined value at the time when the second data is acquired, the diagnostic unit acquires the first to third data and diagnoses an on-failure of the power supply switch using the first to third data, and if the rotation speed of the rotating electric machine is lower than a predetermined value at the time when the second data is acquired, the diagnostic unit acquires the first and second data of the first to third data and diagnoses an on-failure of the power supply switch using the first and second data.

6. The power supply system includes a current sensor (28) for detecting a power supply current that is a current flowing through the power supply; The acquisition unit acquires a detected current of the current sensor after the shutdown command is output by the shutdown command unit, The diagnosis unit includes: a first determination process for determining whether the voltage difference is greater than a predetermined voltage threshold, and a second determination process for determining whether the detected current is greater than a predetermined current threshold, 2. The diagnostic device according to claim 1, wherein when the first determination process determines that the voltage difference is smaller than the voltage threshold value and when the second determination process determines that the detected current is larger than the current threshold value, the power switch is diagnosed as having an on-failure.

7. The power supply system is mounted on a vehicle in which the rotating electric machine is capable of rotating in accordance with the rotation of wheels (50), The diagnostic device according to any one of claims 1 to 6, further comprising a speed control unit that, when the shutoff command is output by the shutoff command unit, reduces the vehicle's traveling speed to reduce the rotation speed of the rotating electric machine, and, when the diagnostic unit determines that the power switch is normal, cancels the reduced state of the traveling speed.

8. The power supply system is mounted on a vehicle having a gear mechanism (34) that changes a gear ratio in a rotation transmission path between wheels (50) and the rotating electric machine, a gear ratio adjusting unit that increases a gear ratio of the rotating electric machine side to the wheel side during vehicle traveling after the cutoff command is output by the cutoff command unit, The diagnostic device according to any one of claims 1 to 6, wherein the acquisition unit acquires, as the voltage difference, a difference between the detected voltage before the gear ratio is increased by the gear ratio adjustment unit and the detected voltage after the gear ratio is increased.

9. The power supply system rotates a propeller (71) using the rotating electric machine in an aircraft that flies in accordance with the rotation of the propeller, The diagnostic device according to claim 1 , further comprising a propeller rotation control unit that reduces a rotation speed of the rotating electric machine together with a reduction in a rotation speed of the propeller when the cutoff command is output by the cutoff command unit.

10. 10. The diagnostic device according to claim 9, wherein the propeller rotation control unit releases the reduced state of the propeller rotation speed when, after the shutoff command is output and the diagnosis unit has performed, it is determined that the power switch is normal and there is a request to increase the rotation speed of the propeller.

11. The power supply system is applied to a moving body including a plurality of drive units each including the inverter, the rotating electric machine, the power switch, and the voltage sensor, and the moving body is capable of moving by driving some of all of the drive units; The diagnostic device according to claim 1, wherein when some of the plurality of drive units in a driven state are to be stopped while the moving body is moving, the cut-off command unit determines that the switch diagnosis condition is satisfied for the drive unit to be stopped, and outputs the cut-off command.

12. 12. The diagnostic device according to claim 11, further comprising: a power control unit that outputs, when the drive of some of the drive units is stopped while the moving body is moving and the cut-off command is output by the cut-off command unit for the drive units to be stopped, a power command value for maintaining the moving state of the moving body to the other drive units to which the cut-off command has not been output.

13. A power source (23, 61); an inverter (24, 73) connected to the power supply; A rotating electric machine (21, 72) connected to the inverter; a power switch (RM1, RM2, 75) provided in a power path between the power supply and the inverter; a voltage sensor (27, 77) for detecting a path voltage which is a voltage of the power supply path on the inverter side relative to the power supply switch; A computer-executable program for use in a power supply system (10, 60) comprising: a shutoff command step of outputting a shutoff command to shut off the power switch while stopping control of the inverter when a predetermined switch diagnosis condition is satisfied in a conductive state of the power switch; an acquisition step of acquiring a voltage difference which is a difference between the voltages detected by the voltage sensors in response to a change in the rotation speed of the rotating electric machine after the output of the shutoff command in the shutoff command step; a diagnosis step of diagnosing an on-failure of the power switch based on the voltage difference; A program that includes:

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