Electric power conversion system and drive system

Abstract

To provide an electric power conversion system and a drive system capable of detecting an abnormality in an electric conduction path and a current sensor.SOLUTION: An electric power conversion circuit 4 has invertors 8, 9. The invertor 8 is connected to one end of coils 3U, 3V, 3W via an output line 13. The invertor 9 is connected to the other end of the coils 3U, 3V, 3W via the output line 13. The electric power conversion circuit 4 has a first current sensor 121, a second current sensor 122 and a series current sensor 123. The first current sensor 121 detects a current flowing in the output line 13. The second current sensor 121 detects a current flowing in the output line 14. The series current sensor 123 detects a current flowing in the output line 14. A controller 15 uses detection results of the series current sensor 123 to detect whether or not an abnormality occurs in at least one of the first current sensor 121 and the second current sensor 122.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] TECHNICAL FIELD The disclosure herein relates to power conversion devices and drive systems. [Background technology]

[0002] Patent Document 1 discloses a power conversion device including a first inverter connected to one end of a winding of a rotating electric machine and a second inverter connected to the other end of the winding. A current sensor is provided in the connection path connecting the first inverter and the winding. One current sensor is provided for each of the three-phase connection paths. The contents of the prior art documents are incorporated by reference as explanations of the technical elements in this specification. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-177342 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned Patent Document 1, there is a concern that even if an abnormality occurs in a current path such as a connection path or in a current sensor, the abnormality in the current path or the current sensor cannot be detected. From the above-mentioned viewpoints and other viewpoints not mentioned, further improvements are required in power conversion modules.

[0005] One disclosed object is to provide a power conversion device and a drive system that can detect abnormalities in current paths and current sensors. [Means for solving the problem]

[0006] One aspect of the disclosure is A power conversion device (4) that converts power supplied to a rotating electric machine (3), a first inverter (8) connected to one end of a winding of the rotating electric machine via a first path (13); a second inverter (9) connected to the other end of the winding via a second path (14); a first current sensor (121) for detecting a current flowing through a first path; a second current sensor (122) for detecting a current flowing through the second path; an abnormality detection sensor (123, 124) for detecting an abnormality in at least one of the first current sensor and the second current sensor; The power conversion device is provided with:

[0007] According to the above-described power conversion device, the current flowing through the first path is detected by the first current sensor, and the current flowing through the second path is detected by the second current sensor. With this configuration, the occurrence of an abnormality in a current path, such as the first path or the second path, can be detected by the first current sensor or the second current sensor. Furthermore, an abnormality in at least one of the first current sensor and the second current sensor is detected by the abnormality detection sensor. Therefore, it is possible to determine whether the detection result of the first current sensor or the detection result of the second current sensor indicates an abnormality in the current path or the current sensor. In this way, an abnormality in the current path or the current sensor can be detected.

[0008] One aspect of the disclosure is A rotating electric machine (3), a power converter (4) that converts power supplied to the rotating electric machine; A drive system (1) for driving a rotating electric machine by a power conversion device, comprising: a first inverter (8) connected to one end of a winding of the rotating electric machine via a first path (13); a second inverter (9) connected to the other end of the winding via a second path (14); a first current sensor (121) for detecting a current flowing through a first path; a second current sensor (122) for detecting a current flowing through the second path; an abnormality detection sensor (123, 124) for detecting an abnormality in at least one of the first current sensor and the second current sensor; A drive system comprising:

[0009] According to the drive system, like the power conversion device, it is possible to detect abnormalities in the current paths and current sensors.

[0010] The various aspects disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims and in this section are intended to exemplify correspondences with the following embodiments and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by reference to the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 illustrates a power conversion circuit and a drive system. [Figure 2] FIG. 4 is a diagram showing an example of an operating point map of the rotating electric machine. [Figure 3] FIG. 1 is a diagram showing a star-connected drive. [Figure 4] FIG. 10 is a diagram showing an open connection drive. [Figure 5] FIG. 2 is a circuit diagram showing a state in which an external device is connected. [Figure 6] 10 is a flowchart showing the procedure of a rotation control process. [Figure 7] FIG. 10 is a diagram illustrating a reference example. [Figure 8] FIG. 10 is a diagram illustrating a reference example. [Figure 9] FIG. 10 is a diagram illustrating a power conversion circuit and a drive system according to a modified example. [Figure 10] FIG. 10 is a diagram illustrating a power conversion circuit and a drive system according to a modified example. [Figure 11] FIG. 10 is a diagram illustrating a power conversion circuit and a drive system according to a modified example. [Figure 12] FIG. 10 is a diagram illustrating a power conversion circuit and a drive system according to a modified example. [Figure 13] FIG. 10 is a diagram illustrating a power conversion circuit and a drive system according to a second embodiment. [Figure 14] FIG. 10 is a diagram illustrating a power conversion circuit and a drive system according to a third embodiment. [Figure 15] FIG. 10 is a diagram illustrating a power conversion circuit and a drive system according to a fourth embodiment. [Figure 16] 10 is a flowchart showing the procedure of a rotation control process. [Figure 17] FIG. 10 is a diagram illustrating a power conversion circuit and a drive system according to a modified example. [Figure 18] FIG. 10 is a diagram illustrating a power conversion circuit and a drive system according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, several embodiments will be described with reference to the drawings. Note that in each embodiment, corresponding components are designated by the same reference numerals, and redundant description may be omitted. When only a portion of the configuration is described in each embodiment, the configuration of another embodiment previously described may be applied to the remaining portion of the configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations of several embodiments may be partially combined together even if not explicitly stated, provided that there is no particular problem with the combination.

[0013] The power conversion module of this embodiment is applied to, for example, a mobile body using a rotating electric machine as a drive source, such as an electric vehicle (BEV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), an aircraft such as an electric vertical take-off and landing aircraft or a drone, a ship, a construction machine, an agricultural machine, etc.

[0014] (First embodiment) First, the schematic configuration of a drive system for a moving body will be described with reference to FIG.

[0015] <Drive systems for moving objects> As shown in FIG. 1, a drive system 1 for a moving body includes a DC power supply 2, a rotating electric machine 3, and a power conversion circuit 4.

[0016] The DC power supply 2 may be, for example, a rechargeable secondary battery such as a lithium ion battery or a nickel-metal hydride battery. The DC power supply 2 may also be one that converts AC power to DC and outputs it. The DC power supply 2 supplies power to the rotating electrical machine 3. The DC power supply 2 corresponds to a power supply unit.

[0017] The rotating electric machine 3 is a three-phase open-winding type rotating electric machine with an open neutral point. The rotating electric machine 3 has a U-phase winding 3U, a V-phase winding 3V, and a W-phase winding 3W. Hereinafter, the U-phase winding 3U, the V-phase winding 3V, and the W-phase winding 3W may be simply referred to as windings 3U, 3V, and 3W.

[0018] The rotating electric machine 3 functions, for example, as a drive source for a moving body, that is, as an electric motor. If the moving body is a vehicle, the rotating electric machine 3 generates torque for driving drive wheels (not shown). The rotating electric machine 3 is not limited to an electric motor. The rotating electric machine 3 may be a motor generator that functions as both an electric motor and a generator, or may be a generator.

[0019] The power conversion circuit 4 converts power between the DC power source 2 and the rotating electric machine 3. The power conversion circuit 4 corresponds to a power conversion device. The power conversion circuit 4 is a three-phase power conversion device. The drive system 1 is a common power supply system in which a common DC power source 2 supplies power to two inverters 8 and 9 (described later) to drive the rotating electric machine 3. The drive system 1 may include only one common DC power source 2 as illustrated in FIG. 1, or multiple common DC power sources 2. The drive system 1 may include a power supply switch (not shown), such as an SMR, between the DC power source 2 and the power conversion circuit 4. SMR is an abbreviation for System Main Relay. Turning on the power supply switch enables power supply from the DC power source 2 to the rotating electric machine 3, and turning off the power supply switch cuts off the power supply from the DC power source 2 to the rotating electric machine 3.

[0020] <Power conversion circuit> Next, the power conversion circuit 4 will be described with reference to Fig. 1. Fig. 1 shows an example of the power conversion circuit 4. The power conversion circuit 4 shown in Fig. 1 includes power lines 5 and 6, a smoothing capacitor 7, inverters 8 and 9, a changeover switch 10, and snubber circuits 11 and 12.

[0021] The power supply line 5 is a high-potential power line. The power supply line 5 is connected to the positive electrode of the DC power supply 2. The power supply line 5 may be referred to as a positive-side power supply line, P line, etc. The power supply line 5 has a wiring 5A. The wiring 5A is a part of the wiring that constitutes the power supply line 5. The wiring 5A is a part of the power supply line 5 that connects the inverter 8 and the inverter 9. The power supply line 6 is a low-potential power line. The power supply line 6 is connected to the negative electrode of the DC power supply 2. The power supply line 6 may be referred to as a negative-side power supply line, N line, etc. The power supply line 6 has a wiring 6A. The wiring 6A is a part of the wiring that constitutes the power supply line 6. The wiring 6A is a part of the power supply line 6 that connects the inverter 8 and the inverter 9. The power supply lines 5, 6 are configured to include a bus bar that is, for example, a metal plate.

[0022] The smoothing capacitor 7 mainly smoothes the DC voltage supplied from the DC power supply 2. The smoothing capacitor 7 is provided between the power supply lines 5 and 6. The positive electrode of the smoothing capacitor 7 is connected to the power supply line 5 between the DC power supply 2 and the inverters 8 and 9. The negative electrode of the smoothing capacitor 7 is connected to the power supply line 6 between the DC power supply 2 and the inverters 8 and 9. The smoothing capacitor 7 is connected in parallel to the inverters 8 and 9.

[0023] The inverters 8 and 9 are DC-AC conversion circuits. The inverters 8 and 9 are three-phase inverter circuits. The inverter 8 corresponds to a first inverter, and the inverter 9 corresponds to a second inverter. The inverter 8 is configured with upper and lower arm circuits 8HL for three phases. The upper and lower arm circuits 8HL are sometimes referred to as legs. The upper and lower arm circuit 8HL has an upper arm 8H and a lower arm 8L. The upper arm 8H and the lower arm 8L are connected in series between the power supply lines 5 and 6, with the upper arm 8H on the power supply line 5 side.

[0024] The connection point between the upper arm 8H and the lower arm 8L is connected to the winding of the corresponding phase in the rotating electric machine 3 via an output line 13. The inverter 8 has six arms. Each arm is configured with a switching element. The number of switching elements configuring each arm is not particularly limited. There may be one or more. When there are more than one switching elements, the multiple switching elements connected in parallel to each other are turned on and off at the same timing by a common gate drive signal (drive voltage).

[0025] In the example shown in FIG. 1, an n-channel MOSFET 8S is used as the switching element constituting each arm. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. In the upper arm 8H, the drain terminal of the MOSFET 8S is connected to the power supply line 5. In the lower arm 8L, the source terminal of the MOSFET 8S is connected to the power supply line 6. The source terminal of the MOSFET 8S in the upper arm 8H and the drain terminal of the MOSFET 8S in the lower arm 8L are connected to each other.

[0026] A freewheeling diode 8D is connected in antiparallel to each MOSFET 8S. The diode 8D may be a parasitic diode (body diode) of the MOSFET 8S, or may be provided separately from the parasitic diode. The anode terminal of the diode 8D is connected to the source terminal of the corresponding MOSFET 8S, and the cathode terminal is connected to the drain terminal.

[0027] The inverter 9 has the same configuration as the inverter 8. The inverter 9 is configured with upper and lower arm circuits 9HL for three phases. The upper and lower arm circuit 9HL has an upper arm 9H and a lower arm 9L. The upper arm 9H and the lower arm 9L are connected in series between the power supply lines 5 and 6, with the upper arm 9H on the power supply line 5 side.

[0028] The connection point between the upper arm 9H and the lower arm 9L is connected to the winding of the corresponding phase in the rotating electric machine 3 via an output line 14. The inverter 9 also has six arms. Each arm is configured with a switching element. The number of switching elements constituting each arm is not particularly limited. It may be one or more.

[0029] In the example shown in Fig. 1, an n-channel MOSFET 9S is used as the switching element constituting each arm. In the upper arm 9H, the drain terminal of the MOSFET 9S is connected to the power supply line 5. In the lower arm 9L, the source terminal of the MOSFET 9S is connected to the power supply line 6. The source terminal of the MOSFET 9S in the upper arm 9H and the drain terminal of the MOSFET 9S in the lower arm 9L are connected to each other. A freewheeling diode 9D is connected in anti-parallel to each MOSFET 9S.

[0030] As described above, the high-potential terminals (drain terminals) of the upper arms 8H, 9H of the inverters 8, 9 are connected to the power line 5. The low-potential terminals (source terminals) of the lower arms 8L, 9L are connected to the power line 6. A node connecting the upper arm 8H and the lower arm 8L is connected to one end of the corresponding phase winding via an output line 13, and a node connecting the upper arm 9H and the lower arm 9L is connected to the other end of the corresponding phase winding via an output line 14. Specifically, one end of the U-phase winding 3U is connected to a node U1 of the U-phase upper and lower arm circuit 8HL, and the other end of the U-phase winding 3U is connected to a node U2 of the U-phase upper and lower arm circuit 9HL. One end of the V-phase winding 3V is connected to a node V1 of the V-phase upper and lower arm circuit 8HL, and the other end of the V-phase winding 3V is connected to a node V2 of the V-phase upper and lower arm circuit 9HL. One end of the W-phase winding 3W is connected to a node W1 of a W-phase upper and lower arm circuit 8HL, and the other end of the W-phase winding 3W is connected to a node W2 of a W-phase upper and lower arm circuit 9HL.

[0031] The switching elements constituting the inverters 8 and 9 are not limited to the MOSFETs described above. For example, IGBTs may be used. IGBT stands for Insulated Gate Bipolar Transistor. In the case of an IGBT, a freewheeling diode is also connected in anti-parallel.

[0032] The changeover switch 10 is a semiconductor switch. A semiconductor switch has a switching element formed on a semiconductor chip. The switching element is not particularly limited and may have the same configuration as the switching element constituting at least one of the inverters 8, 9, or may have a different configuration. The changeover switch 10 is provided between the inverters 8 and 9 on at least one of the power supply lines 5, 6. When the changeover switch 10 is closed, it connects the high-potential side terminal of the upper arm 9H of the inverter 9 to the smoothing capacitor 7 (DC power supply 2). When the changeover switch 10 is open, it cuts off the connection between the high-potential side terminal of the upper arm 9H and the smoothing capacitor 7 (DC power supply 2). The changeover switch 10 may also be called a switch or an open / close switch.

[0033] The switching element of the changeover switch 10 illustrated in FIG. 1 is a MOSFET. A diode is connected in anti-parallel to the MOSFET. The diode is, for example, a parasitic diode. The changeover switch 10 includes changeover switches 10A and 10B. The changeover switch 10A is arranged on wiring 5A of the power supply line 5. The changeover switch 10A is arranged on wiring 5A so that the drain terminal of the MOSFET is on the inverter 8 side and the source terminal is on the inverter 9 side. In other words, the changeover switch 10A is arranged so that the forward direction of the diode is from the inverter 9 to the inverter 8.

[0034] The changeover switch 10B is arranged on the wiring 6A of the power supply line 6. The changeover switch 10B is arranged on the wiring 6A so that the drain terminal of the MOSFET is on the inverter 9 side and the source terminal is on the inverter 8 side. In other words, the changeover switch 10B is arranged so that the forward direction of the diode is from the inverter 8 to the inverter 9. When the MOSFET is turned on and the changeover switch 10 is closed, the inverter 9 is electrically connected to the smoothing capacitor 7 (DC power supply 2). When the MOSFET is turned off and the changeover switch 10 is opened, the electrical connection between the inverter 9 and the smoothing capacitor 7 is interrupted.

[0035] The snubber circuit 11 is connected in parallel to the inverter 9, i.e., the upper and lower arm circuits 9HL. The snubber circuit 11 reduces the inductance of the upper and lower arm circuits 9HL. In other words, the snubber circuit 11 absorbs a transient high voltage, or so-called switching surge, that occurs when the switching elements (MOSFETs 9S) that make up the upper and lower arm circuits 9HL are switched. This enables the inverter 9 to perform high-speed switching.

[0036] The snubber circuit 11 has at least a capacitor 11C. The snubber circuit 11 may be, for example, a C snubber circuit having a capacitor, or an RC snubber circuit having a capacitor and a resistor. It may also be an RCD snubber circuit having a capacitor, a resistor, and a diode. The snubber circuit 11 shown in FIG. 1 is an RC snubber circuit in which a capacitor 11C and a resistor 11R are connected in series. One end of the snubber circuit 11 is connected to the power supply line 5. Another end of the snubber circuit 11 is connected to a portion of the wiring 5A that connects the changeover switch 10 and the inverter 9. The other end of the snubber circuit 11 is connected to the power supply line 6.

[0037] In the power conversion circuit 4 illustrated in FIG. 1, a snubber circuit 11 is provided for each phase of the upper and lower arm circuits 9HL. The power conversion circuit 4 includes three snubber circuits 11. One end of each snubber circuit 11 is connected to the power supply line 5, and the other end is connected to the power supply line 6. Each snubber circuit 11 includes a capacitor 11C and a resistor 11R. One of the snubber circuits 11 is connected in parallel to the U-phase upper and lower arm circuit 9HL. The other snubber circuit 11 is connected in parallel to the V-phase upper and lower arm circuit 9HL. The other snubber circuit 11 is connected in parallel to the W-phase upper and lower arm circuit 9HL.

[0038] The snubber circuit 12 is connected in parallel to the inverter 8, i.e., the upper and lower arm circuits 8HL. The snubber circuit 12 reduces the inductance of the upper and lower arm circuits 8HL, thereby enabling high-speed switching of the inverter 8. The snubber circuit 12 includes at least a capacitor 12C. The snubber circuit 12 may be, for example, a C snubber circuit, an RC snubber circuit, or an RCD snubber circuit. The snubber circuit 12 shown in FIG. 1 is an RC snubber circuit in which a capacitor 12C and a resistor 12R are connected in series. One end of the snubber circuit 12 is connected to the power supply line 5. The other end of the snubber circuit 12 is connected to the power supply line 6.

[0039] In the power conversion circuit 4 illustrated in FIG. 1, a snubber circuit 12 is provided for each phase of the upper and lower arm circuits 8HL. The power conversion circuit 4 includes three snubber circuits 12. One end of each snubber circuit 12 is connected to the power supply line 5, and the other end is connected to the power supply line 6. Each snubber circuit 12 includes a capacitor 12C and a resistor 12R. One of the snubber circuits 12 is connected in parallel to the U-phase upper and lower arm circuit 8HL. The other snubber circuit 12 is connected in parallel to the V-phase upper and lower arm circuit 8HL. The other snubber circuit 12 is connected in parallel to the W-phase upper and lower arm circuit 8HL.

[0040] As illustrated in FIG. 1, the power conversion circuit 4 may include a control unit (CTR) 15. The control unit 15 may include, for example, a processor 15a, a memory 15b, and a storage 15c. The processor 15a accesses the memory 15b to execute various processes. The memory 15b is a rewritable volatile storage medium. The memory 15b is, for example, a RAM. RAM is an abbreviation for Random Access Memory. The storage 15c is a rewritable nonvolatile memory. The storage 15c may be realized by at least one type of non-transitory tangible storage medium, such as a semiconductor memory, a magnetic medium, or an optical medium. The storage 15c may include multiple types of storage media, such as a ROM and a flash memory. ROM is an abbreviation for Read Only Memory.

[0041] The storage 15c stores a program 15d executed by the processor 15a. The program 15d configures a plurality of functional units by causing the processor 15a to execute a plurality of instructions. The processing performed by the control unit 15 may be realized by software processing in which the processor 15a executes the program 15d described above, or may be realized by hardware processing using a dedicated electronic circuit. It may also be realized by a combination of software processing and hardware processing. The program 15d includes a program for executing a rotation control process, which will be described later.

[0042] The control unit 15 may include, for example, a drive command generation unit and a drive circuit unit (not shown). The drive command generation unit controls the inverters 8 and 9. The drive command generation unit generates drive commands (command signals) for controlling the on / off of the MOSFETs 8S and 9S and outputs them to the drive circuit unit. The drive command generation unit generates drive commands based on drive requests for the rotating electric machine 3, such as torque command values ​​input from a higher-level ECU (not shown), and signals detected by various sensors. The various sensors may include current sensors, rotation angle sensors, voltage sensors, and the like (not shown). The current sensors detect phase currents flowing through the windings 3U, 3V, and 3W of each phase. The rotation angle sensor detects the rotation angle of the rotor of the rotating electric machine 3. The voltage sensor detects the voltage across the smoothing capacitor 7. Current sensors include current sensors 121 to 123 (described later).

[0043] The drive command generation unit controls the changeover switch 10 (10A, 10B). The drive command generation unit generates drive commands for controlling the on / off of the changeover switch 10 and outputs the drive commands to the drive circuit unit. The drive circuit unit is sometimes referred to as a driver. The drive circuit unit can independently control the on / off of the MOSFET 8S, MOSFET 9S, and changeover switch 10 based on the drive commands. For convenience, signal lines for transmitting drive signals from the control unit 15 to each switching element are omitted in FIG. 1.

[0044] <Star connection drive and open connection drive> Next, star connection driving and open connection driving will be described with reference to Figures 2, 3, and 4. Figure 2 shows an example of an operating point map of a rotating electric machine, with the horizontal axis representing rotation speed and the vertical axis representing torque. Figure 3 is a diagram showing star connection driving. Figure 4 is a diagram showing open connection driving. For convenience, the control unit 15 is omitted from Figures 3 and 4.

[0045] As shown in FIG. 2, the driving range of the rotating electric machine 3 is divided into two ranges depending on the rotation speed and torque. One of the driving ranges is the star connection driving range. The star connection driving range is the normal use range. The other driving range is the open connection driving range. The open connection driving range is a range with higher rotation speeds or higher torque than the star connection driving range.

[0046] When the operating point is in the star connection drive region, the control unit 15 executes star connection drive control. Star connection drive is sometimes referred to as Y drive. The control unit 15 controls the MOSFETs 8S and 9S and the changeover switch 10 so that the windings 3U, 3V, and 3W are in a star connection state. Specifically, as shown in FIG. 3, the MOSFETs of the changeover switch 10 (10A, 10B) are turned off and the changeover switch 10 is opened. The inverter 9 is also neutralized. As shown in FIG. 3, for example, the MOSFETs 9S of the upper arms 9H of all phases may be turned on and the MOSFETs 9S of the lower arms 9L of all phases may be turned off. The MOSFETs 9S of the upper arms 9H of all phases may be turned off and the MOSFETs 9S of the lower arms 9L of all phases may be turned on. The MOSFETs 8S of the inverter 8 are then controlled according to drive requirements, etc.

[0047] FIG. 3 shows one current conduction pattern in star-connection drive. The dashed-dotted arrows in FIG. 3 indicate an example of a current path. FIG. 3 shows the current path when the MOSFET 8S in the U-phase upper arm 8H and the MOSFET 8S in the W-phase lower arm 8L are turned on. In the example shown in FIG. 3, the upper arm 9H of the inverter 9 is turned on and the lower arm 9L is turned off. The current flows in the following order: U-phase upper arm 8H → node U1 → U-phase winding 3U → node U2 → U-phase upper arm 9H → W-phase upper arm 9H → node W2 → W-phase winding 3W → node W1 → W-phase lower arm 8L. In this way, in star-connection drive, current flows without passing through the selector switch 10.

[0048] When the operating point is in the open connection drive region, the control unit 15 executes open connection drive control. Open connection drive is sometimes referred to as H drive. The control unit 15 turns on the MOSFET of the changeover switch 10 (10A, 10B) to close the changeover switch 10. The control unit 15 also opens the neutral point of the inverter 9. By opening the neutral point, an open connection circuit of the U-phase upper and lower arm circuits 8HL, 9HL is formed via the U-phase winding 3U. Similarly, an open connection circuit of the V-phase upper and lower arm circuits 8HL, 9HL is formed via the V-phase winding 3V. An open connection circuit of the W-phase upper and lower arm circuits 8HL, 9HL is formed via the W-phase winding 3W. The control unit 15 regards each phase as an independent open connection circuit and controls the applied voltage for each phase.

[0049] FIG. 4 shows one current conduction pattern in open-connection driving. The two-dot chain arrow in FIG. 4 indicates one example of a current path. FIG. 4 shows the current path when MOSFET 8S in W-phase lower arm 8L and MOSFET 9S in W-phase upper arm 9H are turned on. Current flows in the following order: changeover switch 10 → W-phase upper arm 9H → node W2 → W-phase winding 3W → node W1 → W-phase lower arm 8L. In this way, in open-connection driving, current flows via changeover switch 10.

[0050] As described above, the power conversion circuit 4 is configured to be switchable between star connection drive and open connection drive. The power conversion circuit 4 is configured to be able to execute star connection drive. The power conversion circuit 4 is configured to be able to execute open connection drive. By executing open connection drive instead of star connection drive, it is possible to output a higher rotation speed range or a higher torque range.

[0051] <Charging using a power conversion circuit> Next, charging using the power conversion circuit 4 will be described with reference to Fig. 5. Fig. 5 shows a circuit configuration showing a state in which an external device is connected. In Fig. 5, the external device is shown in a simplified form.

[0052] As shown in FIG. 5, the external device 16 is connected to the power supply lines 5 and 6. The external device 16 is connected in parallel to the DC power supply 2. The external device 16 is an element separate from the elements constituting the drive system 1. The external device 16 may be, for example, an element external to a moving body (vehicle). An example of the external device 16 is a charger. The charger charges the DC power supply 2. The voltage supplied by the external device 16 is lower than the power supply voltage of the DC power supply 2. For example, the DC power supply 2 is 800 V, and the external device 16 (charger) is 400 V. In the rotating electric machine 3 and the power conversion circuit 4, the windings 3U, 3V, and 3W of the rotating electric machine 3 and the upper and lower arm circuit 8HL constituting the inverter 8 function as a boost circuit.

[0053] The external device 16 is connected to the drive system 1 (power conversion circuit 4) while the vehicle is stopped, for example. When the external device 16 is connected, the control unit 15 controls the inverters 8 and 9 and the selector switch 10 to boost the supply voltage of the external device 16 and charge the DC power supply 2. The boost operation may use one phase or multiple phases (multi-phase). The control unit 15 turns off the MOSFET of the selector switch 10. In this state, the control unit 15 turns on the upper arm 9H of the inverter 9 and controls the on / off of the upper and lower MOSFETs 8S of the upper and lower arm circuit 8HL in the corresponding phase.

[0054] External device 16 may be a DC power supply (external power supply) separate from DC power supply 2. The external power supply may be, for example, a secondary battery or may include a DC-AC conversion circuit. DC power supply 2 charges external device 16. The power supply voltage of external device 16 is lower than the power supply voltage of DC power supply 2. In rotating electric machine 3 and power conversion circuit 4, windings 3U, 3V, 3W of rotating electric machine 3 and upper arm 8H of inverter 8 function as a step-down circuit.

[0055] When an external device 16 is connected to the drive system 1, the control unit 15 controls the inverters 8 and 9 and the selector switch 10 to step down the power supply voltage of the DC power supply 2 and charge the external device 16. In the step-down operation, one phase or multiple phases (multi-phase) may be used. The control unit 15 turns off the MOSFET of the selector switch 10. In this state, the control unit 15 turns on the upper arm 9H of the inverter 9 and controls the on / off of the MOSFET 8S of the upper arm 8H of the corresponding phase. The MOSFET 8S of the lower arm 8L of the corresponding phase is turned off. When the MOSFET 8S of the upper arm 8H is turned off, a current flows through the diode of the lower arm 8L of the corresponding phase.

[0056] <Current sensor> As shown in FIG. 1, the drive system 1 has a first current sensor 121, a second current sensor 122, and a direct current sensor 123. The current sensors 121 to 123 detect phase currents flowing through the windings 3U, 3V, and 3W of each phase. The current sensors 121 to 123 are magnetic sensors such as Hall sensors. The magnetic sensors are formed to include a sensor element such as a Hall element. The current sensors 121 to 123 may also be formed to include a resistive element such as a shunt resistor.

[0057] Current sensors 121 to 123 are provided for each of the three phases. First current sensor 121 includes first current sensors 121U, 121V, and 121W. Second current sensor 122 includes second current sensors 122U, 122V, and 122W. Series current sensor 123 includes series current sensors 123U, 123V, and 123W. Current sensors 121U, 122U, and 123U detect the current flowing through U-phase winding 3U in the U phase. Current sensors 121V, 122V, and 123V detect the current flowing through V-phase winding 3V in the V phase. Current sensors 121W, 122W, and 123W detect the current flowing through W-phase winding 3W in the W phase. In this embodiment, the U phase, V phase, and W phase each correspond to a target phase. The U phase is sometimes referred to as the first phase, the V phase as the second phase, and the W phase as the third phase.

[0058] The first current sensor 121 detects the current flowing in the output line 13. The first current sensor 121 is provided on the output line 13 but not on the output line 14. The first current sensor 121 is provided on the output line 13 between the windings 3U, 3V, 3W and the inverter 8. The U-phase first current sensor 121U detects the current flowing in the U-phase output line 13 as the current flowing in the U-phase winding 3U. The V-phase first current sensor 121V detects the current flowing in the V-phase output line 13 as the current flowing in the V-phase winding 3V. The W-phase first current sensor 121W detects the current flowing in the W-phase output line 13 as the current flowing in the W-phase winding 3W. The output line 13 corresponds to the first path, and the output line 14 corresponds to the second path.

[0059] The second current sensor 122 detects the current flowing in the output line 14. The second current sensor 122 is provided on the output line 14 but not on the output line 13. The second current sensor 122 is provided on the output line 14 between the windings 3U, 3V, 3W and the inverter 9. The U-phase second current sensor 122U detects the current flowing in the U-phase output line 14 as the current flowing in the U-phase winding 3U. The V-phase second current sensor 122V detects the current flowing in the V-phase output line 14 as the current flowing in the V-phase winding 3V. The W-phase second current sensor 122W detects the current flowing in the W-phase output line 14 as the current flowing in the W-phase winding 3W.

[0060] Series current sensor 123 is provided on one of output line 13 and output line 14. For example, series current sensor 123 is provided on output line 14 but not on output line 13. Series current sensor 123 is arranged next to second current sensor 122 on output line 14. Like second current sensor 122, series current sensor 123 detects the current flowing in output line 14. Series current sensor 123 is provided on output line 14 between second current sensor 122 and inverter 9. U-phase series current sensor 123U detects the current flowing in U-phase output line 14 as the current flowing in U-phase winding 3U. V-phase series current sensor 123V detects the current flowing in V-phase output line 14 as the current flowing in V-phase winding 3V. W-phase series current sensor 123W detects the current flowing in W-phase output line 14 as the current flowing in W-phase winding 3W.

[0061] Series current sensor 123 detects the current flowing through windings 3U, 3V, and 3W, and is therefore capable of detecting an abnormality in at least one of first current sensor 121 and second current sensor 122. Series current sensor 123 corresponds to an abnormality detection sensor.

[0062] The power conversion circuit 4 has a current path through which a current flows. The current path includes the power lines 5 and 6, the selector switch 10, the output lines 13 and 14, and the windings 3U, 3V, and 3W. Between the first current sensor 121 and the second current sensor 122 and the series current sensor 123, a portion of the output line 13, a portion of the output line 14, and the windings 3U, 3V, and 3W form the current path. Losses such as resistance losses and heat losses are likely to occur in the current paths between the first current sensor 121 and the second current sensor 122 and the series current sensor 123. Losses occurring in the windings 3U, 3V, and 3W are particularly likely to be larger than losses occurring in a portion of the output line 13 or a portion of the output line 14. Because the losses occurring in the windings 3U, 3V, and 3W are relatively large, differences are likely to occur between the detection results of the first current sensor 121, the second current sensor 122, and the series current sensor 123.

[0063] On the other hand, windings 3U, 3V, and 3W are not present between second current sensor 122 and series current sensor 123. Therefore, a difference between the detection results of second current sensor 122 and series current sensor 123 is unlikely to occur.

[0064] The power supply lines 5 and 6 connect the inverter 8 and the inverter 9 without passing through the windings 3U, 3V, and 3W. The power supply lines 5 and 6 correspond to direct paths. In the power supply line 5, the wiring 5A connects the inverter 8 and the inverter 9. The wiring 5A connects the upper arm 8H and the upper arm 9H. The wiring 5A corresponds to the upper direct path. In the power supply line 6, the wiring 6A connects the inverter 8 and the inverter 9. The wiring 6A connects the lower arm 8L and the lower arm 9L. The wiring 6A corresponds to the lower direct path. The power supply lines 5 and 6 electrically connect the DC power supply 2 and the inverters 8 and 9.

[0065] Current sensors 121 and 122 are communicatively connected to control unit 15. Current sensors 121 and 122 output to control unit 15 detection signals corresponding to the currents flowing through windings 3U, 3V, and 3W.

[0066] The control unit 15 performs rotation control, which is control of the rotating electric machine 3. The rotation control includes control of star connection drive and control of open connection drive. The rotation control also includes control of the power conversion circuit 4. The control of the power conversion circuit 4 includes control of the inverters 8 and 9 and control of the changeover switch 10. The control unit 15 performs rotation control by executing a rotation control process. The control unit 15 repeatedly executes the rotation control process at a predetermined control period. The control unit 15 has a function of executing the processing of each step of the rotation control process. The rotation control process will be described with reference to the flowchart of FIG. 6.

[0067] The control unit 15 performs a current detection process in step S101 shown in FIG. 6. In the current detection process, a process for detecting the currents flowing through the windings 3U, 3V, and 3W is performed. In the current detection process, a first detection value I1, a second detection value I2, and a series detection value I3 are detected. The first detection value I1 is a detection value of the current flowing through the output line 13 for each of the three phases. The second detection value I2 and the series detection value I3 are detection values ​​of the current flowing through the output line 14 for each of the three phases. The control unit 15 calculates the detection values ​​I1, I2, and I3 for the U phase, V phase, and W phase, respectively, using the detection signals of the current sensors 121, 122, and 123. The first detection value I1 is the detection result of the first current sensor 121. The second detection value I2 is the detection result of the second current sensor 122. The series detection value I3 is the detection result of the series current sensor 123.

[0068] For example, control unit 15 calculates first detected values ​​I1U, I1V, and I1W using the detection signals of first current sensors 121U, 121V, and 121W. Control unit 15 also calculates second detected values ​​I2U, I2V, and I2W using the detection signals of second current sensors 122U, 122V, and 122W. Control unit 15 calculates series detected values ​​I3U, I3V, and I3W using the detection signals of series current sensors 123U, 123V, and 123W. Detected values ​​I1U, I2U, and I3U are detected values ​​of the current flowing through U-phase winding 3U. Detected values ​​I1V, I2V, and I3V are detected values ​​of the current flowing through V-phase winding 3V. Detected values ​​I1W, I2W, and I3W are detected values ​​of the current flowing through W-phase winding 3W.

[0069] In step S102, the control unit 15 calculates the detection difference Idif using the detection values ​​I1, I2, and I3. The detection difference Idif includes a first detection difference Idif1 and a second detection difference Idif2. The first detection difference Idif1 is the difference between the first detection value I1 and the series detection value I3. The control unit 15 calculates the first detection difference Idif1 for each of the three phases. For example, the control unit 15 calculates the difference between the first detection value I1U and the series detection value I3U as the first detection difference Idif1 for the U phase. The control unit 15 calculates the difference between the first detection value I1V and the series detection value I3V as the first detection difference Idif1 for the V phase. The control unit 15 calculates the difference between the first detection value I1W and the series detection value I3W as the first detection difference Idif1 for the W phase.

[0070] The second detection difference Idif2 is the difference between the second detection value I2 and the series detection value I3. The control unit 15 calculates the second detection difference Idif2 for each of the three phases. For example, the control unit 15 calculates the difference between the second detection value I2U and the series detection value I3U as the second detection difference Idif2 for the U phase. The control unit 15 calculates the difference between the second detection value I2V and the series detection value I3V as the second detection difference Idif2 for the V phase. The control unit 15 calculates the difference between the second detection value I2W and the series detection value I3W as the second detection difference Idif2 for the W phase.

[0071] In step S103, the control unit 15 determines whether the detected difference Idif is greater than a difference threshold JI. The difference threshold JI includes a first difference threshold JI1 and a second difference threshold JI2. The control unit 15 performs a first determination process to determine whether the first detected difference Idif1 is greater than the first difference threshold JI1, and a second determination process to determine whether the second detected difference Idif2 is greater than the second difference threshold JI2. The function of the control unit 15 that executes the process of step S103 corresponds to the sensor determination unit.

[0072] In a first determination process, the control unit 15 uses the first detection value I1 and the series detection value I3 to determine whether an abnormality has occurred in at least one of the first current sensor 121 and the series current sensor 123. In the first determination process, the first current sensor 121 corresponds to the target sensor. In a second determination process, the control unit 15 uses the second detection value I2 and the series detection value I3 to determine whether an abnormality has occurred in at least one of the second current sensor 122 and the series current sensor 123. In the second determination process, the second current sensor 122 corresponds to the target sensor.

[0073] In the first determination process, if the absolute value of the first detection difference Idif1 is greater than the first difference threshold JI1, it is determined that the first detection difference Idif1 is greater than the first difference threshold JI1. The first difference threshold JI1 is a value determined in advance through testing or the like, and is stored in the memory 15b or the like. The first difference threshold JI1 is a value that indicates that the first detection difference Idif1 is abnormally large.

[0074] As described above, a certain difference is likely to occur between the first detection value I1 and the series detection value I3 due to losses occurring in the windings 3U, 3V, and 3W, etc. In other words, even when no abnormality occurs in the power conversion circuit 4, the first detection difference Idif1 is likely to be a value greater than zero. The first difference threshold JI1 is set to a value that corresponds to losses occurring in the windings 3U, 3V, and 3W, etc. The first difference threshold JI1 is set to a value that indicates that the first detection difference Idif1 is within the normal range.

[0075] The first detection difference Idif1 may be greater than the first difference threshold JI1 when at least one of the first detection value I1 and the series detection value I3 is abnormal. The first detection value I1 may be abnormal when an abnormality such as a failure occurs in the first current sensor 121. The series detection value I3 may be abnormal when an abnormality occurs in the series current sensor 123. The first detection difference Idif1 being greater than the first difference threshold JI1 is sometimes referred to as a first detection value abnormality. For example, a first detection value abnormality may occur in at least one of the three phases.

[0076] If the first detection difference Idif1 is not greater than the first difference threshold JI1, the control unit 15 determines that no abnormality has occurred in the first current sensor 121 or the series current sensor 123. If the first detection difference Idif1 is not greater than the first difference threshold JI1 in any of the three phases, the control unit 15 determines that no abnormality has occurred in the first current sensor 121 or the series current sensor 123.

[0077] In the second determination process, if the absolute value of the second detection difference Idif2 is greater than the second difference threshold JI2, it is determined that the second detection difference Idif2 is greater than the second difference threshold JI2. The second difference threshold JI2 is a value determined in advance through testing or the like, and is stored in the memory 15b or the like. The second difference threshold JI2 is a value that indicates that the second detection difference Idif2 is abnormally large.

[0078] The second detection difference Idif2 may be greater than the second difference threshold JI2 when at least one of the second detection value I2 and the series detection value I3 is abnormal. The second detection value I2 may be abnormal when an abnormality such as a failure occurs in the second current sensor 122. When the second detection difference Idif2 is greater than the second difference threshold JI2, this is sometimes referred to as a second detection value abnormality. For example, a second detection value abnormality may occur in at least one of the three phases.

[0079] If the second detection difference Idif2 is not greater than the second difference threshold JI2, the control unit 15 determines that no abnormality has occurred in the second current sensor 122 or the series current sensor 123. Because both the first current sensor 121 and the second current sensor 122 are provided on the output line 14, losses such as resistance loss and heat loss in the output line 14 are unlikely to occur between the first current sensor 121 and the second current sensor 122. Therefore, if no abnormality has occurred in the current sensors 121 and 122, the first detection value I1 and the second detection value I2 will be approximately the same value. In this case, the detection difference Idif will be approximately zero.

[0080] The control unit 15 determines that the detection difference Idif is greater than the difference threshold JI when at least one of the following is determined: the first detection difference Idif1 is greater than the first difference threshold JI1; and the second detection difference Idif2 is greater than the second difference threshold JI2. When it is determined that the detection difference Idif is greater than the difference threshold JI, this indicates that at least one of a first abnormality in the detection value and a second abnormality in the detection value has occurred.

[0081] For example, a first detected value abnormality may occur when an abnormality occurs in the first current sensor 121 or the series current sensor 123 among the current sensors 121, 122, and 123. A second detected value abnormality may occur when an abnormality occurs in the second current sensor 122 or the series current sensor 123 among the current sensors 121, 122, and 123. Furthermore, a first detected value abnormality and a second detected value abnormality may both occur when an abnormality occurs in the series current sensor 123 among the current sensors 121, 122, and 123.

[0082] If the detected difference Idif is not greater than the difference threshold JI for any of the three phases, the control unit 15 determines that no abnormality has occurred in the current sensors 121, 122, and 123, and proceeds to step S104. In step S104, the control unit 15 determines whether or not an abnormality has occurred in the current flow using the detected values ​​I1, I2, and I3. Examples of abnormalities in the current flow include abnormalities that have occurred in the current flow paths, such as the power lines 5 and 6, the selector switch 10, the output lines 13 and 14, and the windings 3U, 3V, and 3W. Examples of abnormalities in the current flow paths include a short circuit, leakage current, and ground fault in the output line 14. The function of the control unit 15 that executes the process of step S104 corresponds to a path determination unit.

[0083] The control unit 15 can determine whether a phase-to-phase short circuit has occurred between the output lines 13 and 14. The control unit 15 can determine whether a phase-to-phase short circuit has occurred in the output line 13 using the first detection value I1. For example, if the first detection value I1W is a normal value while both the first detection values ​​I1U and I1V are abnormal values, the control unit 15 determines that a phase-to-phase short circuit has occurred, in which the U-phase output line 13 and the V-phase output line 13 are shorted. The control unit 15 can also determine whether a phase-to-phase short circuit has occurred in the output line 14 using the second detection value I2. For example, if the second detection value I2 is a normal value while both the second detection values ​​I2U and I2V are abnormal values, the control unit 15 determines that a phase-to-phase short circuit has occurred, in which the U-phase output line 14 and the V-phase output line 14 are shorted. The control unit 15 may also use the series detection value I3 to determine whether a phase-to-phase short circuit has occurred in the output line 14.

[0084] Control unit 15 can estimate the position where the abnormality has occurred in the current path by comparing first detection value I1 with second detection value I2, etc. For example, if an abnormality such as a ground fault occurs in the current path at a position closer to inverter 8 than windings 3U, 3V, and 3W, first detection value I1 may be excessively smaller than second detection value I2. Therefore, when first detection value I1 is excessively smaller than second detection value I2 in at least one target phase, control unit 15 determines that the abnormality has occurred in the current path at a position closer to inverter 8 than windings 3U, 3V, and 3W.

[0085] If a current supply abnormality occurs, the control unit 15 proceeds to step S115 and performs a current supply stop process. In the current supply stop process, a process for stopping current supply to the windings 3U, 3V, and 3W is performed. The control unit 15 can stop the driving of the rotating electric machine 3 by the current supply stop process. However, the current supply stop process does not necessarily stop the driving of the rotating electric machine 3. For example, if it is not possible to stop the moving body, the control unit 15 may continue the supply of current to the windings 3U, 3V, and 3W so that the rotating electric machine 3 operates at the minimum necessary output. In the current supply stop process, a notification process may be performed to notify an occupant or the like of abnormality information regarding the current supply abnormality. In the notification process, the abnormality information is notified to the occupant or the like by sound, image, or the like. The abnormality information includes the location where the current supply abnormality occurred, the type of the current supply abnormality, and the like.

[0086] If no abnormal current flow has occurred, the control unit 15 performs normal control to drive the rotating electric machine 3 in steps S105 and S106. In step S105 of the normal control, the control unit 15 sets normal parameters. The normal parameters are control parameters used in the normal control. The control unit 15 sets at least one of the first detection value I1, the second detection value I2, and the series detection value I3 as the control parameter. For example, the control unit 15 sets the second detection value I2 as the control parameter.

[0087] The control unit 15 performs normal drive processing in step S106. In the normal drive processing, processing for driving the rotating electric machine 3 is performed using control parameters. The control unit 15 drives the rotating electric machine 3 using the first detection value I1. The control unit 15 can drive the rotating electric machine 3 by star connection drive or open connection drive. The function of the control unit 15 for executing steps S105 and S106 includes a function for star connection drive of the rotating electric machine 3 and a function for open connection drive of the rotating electric machine 3.

[0088] If the detection difference Idif is greater than the difference threshold JI in at least one of the three phases, the control unit 15 determines that an abnormality in the detection value has occurred, and proceeds to step S107. In step S107, the control unit 15 performs an alert process. The alert process includes a process for notifying that an abnormality has occurred in the current sensors 121, 122, and 123. The alert process notifies the occupants or the like of the abnormality in the current sensors 121, 122, and 123 by sound, image, or the like.

[0089] In steps S108 to S110, control unit 15 performs identification processing to identify the sensor in which the abnormality has occurred. The identification processing is processing to identify in which of first current sensor 121, second current sensor 122, and series current sensor 123 the abnormality has occurred. The function of control unit 15 that executes the processing of steps S108 to S110 corresponds to a sensor identification unit.

[0090] In step S108 of the identification process, control unit 15 calculates first estimated value Ia1, second estimated value Ia2, and series estimated value Ia3 using detected values ​​I1, I2, and I3. For example, if a first detected value abnormality occurs, control unit 15 calculates estimated values ​​Ia1 and Ia3 for the phase of the three phases in which the first detected value abnormality occurred. First estimated value Ia1 is a value obtained by estimating first detected value I1 of one of the three phases from the first detected values ​​I1 of the remaining two phases. Series estimated value Ia3 is a value obtained by estimating series detected value I3 of one of the three phases from the series detected values ​​I3 of the remaining two phases.

[0091] Control unit 15 calculates estimated values ​​Ia1 and Ia3 from detected values ​​I1 and I3 using current correlation information indicating the correlation between the currents flowing through windings 3U, 3V, and 3W. The current correlation information includes the correlation between the currents flowing through U-phase winding 3U, V-phase winding 3V, and W-phase winding 3W. The current correlation information also includes the correlation between the currents flowing through windings 3U, 3V, and 3W and the currents flowing through output line 13 and output line 14. The current correlation information may be a map, an arithmetic expression, a function, or the like. The current correlation information is stored in memory 15b or the like.

[0092] For example, if a first detected value abnormality occurs in the U-phase, control unit 15 calculates a first estimated value Ia1 of the U-phase using a first detected value I1V of the V-phase and a first detected value I1W of the W-phase. Control unit 15 also calculates a series estimated value Ia3 of the U-phase using a series detected value I3V of the V-phase and a series detected value I3W of the W-phase. Control unit 15 calculates the estimated values ​​Ia1 and Ia3 depending on the driving state of rotating electric machine 3.

[0093] When a second abnormality in the detected values ​​occurs, the control unit 15 calculates the estimated values ​​Ia2 and Ia3 for the phase in which the second abnormality occurs among the three phases. The second estimated value Ia2 is a value obtained by estimating the second detected value I2 of one of the three phases from the second detected values ​​I2 of the remaining two phases. The control unit 15 calculates the estimated values ​​Ia2 and Ia3 from the detected values ​​I2 and I3 using current correlation information indicating the correlation between the currents flowing through the windings 3U, 3V, and 3W. For example, when a second abnormality in the detected values ​​occurs in the U phase, the control unit 15 calculates the second estimated value Ia2 of the U phase using the second detected value I2V of the V phase and the second detected value I2W of the W phase. The control unit 15 calculates the estimated values ​​Ia2 and Ia3 according to the driving state of the rotating electric machine 3.

[0094] In step S109, the control unit 15 calculates a first deviation value Ib1, a second deviation value Ib2, and a series deviation value Ib3 using the estimated values ​​Ia1, Ia2, and Ia3. The deviation values ​​Ib1, Ib2, and Ib3 indicate the magnitude of deviation between the detected values ​​I1, I2, and I3 and the estimated values ​​Ia1, Ia2, and Ia3 for the phase in which the abnormal detected value occurred among the three phases.

[0095] When a first detected value abnormality occurs, the control unit 15 calculates the difference between the first detected value I1 and the first estimated value Ia1 for the phase in which the first detected value abnormality occurred as a first deviation value Ib1, and calculates the difference between the series detected value I3 and the series estimated value Ia3 as a series deviation value Ib3. For example, when a first detected value abnormality occurs for the U phase, the control unit 15 calculates the deviation values ​​Ib1 and Ib3 for the U phase. When a second detected value abnormality occurs, the control unit 15 calculates the difference between the second detected value I2 and the second estimated value Ia2 for the phase in which the second detected value abnormality occurred as a second deviation value Ib2, and calculates the series deviation value Ib3. For example, when a second detected value abnormality occurs for the U phase, the control unit 15 calculates the deviation values ​​Ib2 and Ib3 for the U phase.

[0096] In step S110, the control unit 15 identifies an abnormal sensor using the deviation values ​​Ib1, Ib2, and Ib3. The abnormal sensor is the current sensor in which the abnormality occurred among the first current sensor 121, the second current sensor 122, and the series current sensor 123 for the phase in which the abnormal detection value occurred. The control unit 15 determines that the largest value among the first deviation value Ib1, the second deviation value Ib2, and the series deviation value Ib3 is the abnormal deviation value. For example, if the absolute value of the second deviation value Ib2 is larger than the absolute value of the first deviation value Ib1 and the absolute value of the series deviation value Ib3, the control unit 15 determines that the second deviation value Ib2 is the abnormal deviation value.

[0097] The control unit 15 may determine whether each of the first deviation value Ib1, the second deviation value Ib2, and the series deviation value Ib3 is greater than a deviation threshold. The deviation threshold is a value determined in advance through testing or the like and stored in the memory 15b or the like. The deviation threshold is a value indicating that the deviation values ​​Ib1, Ib2, and Ib3 are abnormally large. For example, if the first deviation value Ib1 is greater than the deviation threshold, the control unit 15 determines that the first deviation value Ib1 is an abnormal deviation value. Also, if the second deviation value Ib2 is greater than the deviation threshold, the control unit 15 determines that the second deviation value Ib2 is an abnormal deviation value. If the series deviation value Ib3 is greater than the deviation threshold, the control unit 15 determines that the series deviation value Ib3 is an abnormal deviation value. For this reason, the control unit 15 may determine that more than one of the first deviation value Ib1, the second deviation value Ib2, and the series deviation value Ib3 is an abnormal deviation value.

[0098] The control unit 15 determines that the current sensor used to calculate the abnormal deviation value among the first current sensor 121, the second current sensor 122, and the series current sensor 123 is the abnormal sensor. For example, when a second detection value abnormality occurs for the U phase and the second deviation value Ib2 is larger than the series deviation value Ib3, the control unit 15 determines that an abnormality has occurred in the second current sensor 122 of the U phase. The control unit 15 also determines that the detection value used to calculate the abnormal deviation value among the first detection value I1, the second detection value I2, and the series detection value I3 is the abnormal value.

[0099] In steps S108 to S110, the control unit 15 may identify the abnormal sensor according to a combination pattern of the first abnormal detection value and the second abnormal detection value. For example, when a first abnormal detection value occurs but a second abnormal detection value does not occur, the control unit 15 determines that an abnormality has occurred in the first current sensor 121 but that an abnormality has not occurred in the second current sensor 122 or the series current sensor 123. When a second abnormal detection value occurs but the first abnormal detection value does not occur, the control unit 15 determines that an abnormality has occurred in the second current sensor 122 but that an abnormality has not occurred in the first current sensor 121 or the series current sensor 123. When both the first abnormal detection value and the second abnormal detection value occur, the control unit 15 determines that an abnormality has occurred in the series current sensor 123 but that an abnormality has not occurred in the first current sensor 121 or the second current sensor 122.

[0100] In steps S111 to S114, the control unit 15 performs fail-safe control for driving the rotating electric machine 3 in a situation where an abnormal sensor is present. The control unit 15 sets a fail-safe parameter in step S111 of the fail-safe control. The fail-safe parameter is a control parameter used for the fail-safe control. The control unit 15 sets the non-abnormal value of the first detection value I1 or the second detection value I2 as the fail-safe parameter. For example, when the control unit 15 determines that an abnormality has occurred in the first current sensor 121 for the U phase, the control unit 15 sets the second detection value I2U for the U phase as the fail-safe parameter. In this case, for the V phase and the W phase, either the first detection values ​​I1V, I1W or the second detection values ​​I2V, I2W may be set as the fail-safe parameter. Note that the control unit 15 may also set the series detection value I3 as the fail-safe parameter.

[0101] In step S112, the control unit 15 determines whether open connection driving is necessary. For example, it determines whether the rotating electric machine 3 needs to be driven at high rotation speed or high torque in order to move the moving body. If it is necessary to drive the rotating electric machine 3 at high rotation speed or high torque, the control unit 15 determines that open connection driving is necessary.

[0102] If open connection drive is necessary, the control unit 15 proceeds to step S113 and performs star connection drive processing. In the star connection drive processing, processing is performed to drive the rotating electric machine 3 in a star connection manner using fail-safe parameters. If open connection drive is not necessary, the control unit 15 proceeds to step S114 and performs open connection drive processing. In the open connection drive processing, processing is performed to drive the rotating electric machine 3 in an open connection manner using fail-safe parameters.

[0103] <Summary of the First Embodiment> According to this embodiment, in the target phase, the first current sensor 121 detects the current flowing in the output line 13, and the second current sensor 122 detects the current flowing in the output line 14. With this configuration, the first current sensor 121 and the second current sensor 122 can detect an abnormality in a current path such as the output lines 13 and 14. Furthermore, an abnormality in at least one of the first current sensor 121 and the second current sensor 122 is detected by the series current sensor 123. Therefore, it is possible to determine whether the first detection value I1 or the second detection value I2 is an abnormality in the current path or the current sensors 121 and 122. In this way, an abnormality in the current path or the current sensors 121 and 122 can be detected.

[0104] According to this embodiment, both the first current sensor 121 and the second current sensor 122 detect the current of the target phase. With this configuration, by comparing the first detection value I1 with the second detection value I2, it is possible to determine whether an abnormality in the current path has occurred at a position on the first current sensor 121 side or a position on the second current sensor 122 side with respect to the windings 3U, 3V, and 3W. Therefore, when an abnormality in the current path occurs, the nature of the abnormality can be estimated.

[0105] According to this embodiment, series current sensor 123 detects the current flowing through output line 14 in the target phase. With this configuration, it is possible to detect an abnormality in first current sensor 121 or second current sensor 122 by calculating the difference between series detection value I3 and first detection value I1 or second detection value I2. This improves the accuracy with which series current sensor 123 detects an abnormality in current sensors 121 and 122.

[0106] According to this embodiment, the first current sensor 121, the second current sensor 122, and the series current sensor 123 detect currents for each of the three phases as a target phase. With this configuration, it is possible to detect abnormalities in the current paths and the current sensors 121 and 122 for each of the three phases in the control of the rotating electric machine 3. This improves the accuracy with which the current sensors 121, 122, and 123 detect abnormalities in the current paths and the current sensors 121 and 122.

[0107] According to this embodiment, the control unit 15 uses the first detection value I1 and the series detection value I3 in at least one phase to determine whether an abnormality has occurred in at least one of the first current sensor 121 and the series current sensor 123. In this configuration, it is possible to detect in which phase the abnormality has occurred in the first current sensor 121 or the series current sensor 123 by calculating the first detection difference Idif1 from the detection values ​​I1 and I3, for example.

[0108] Furthermore, in at least one phase, the control unit 15 uses the second detection value I2 and the series detection value I3 to determine whether an abnormality has occurred in at least one of the second current sensor 122 and the series current sensor 123. In this configuration, it is possible to detect in which phase the abnormality has occurred in the second current sensor 122 or the series current sensor 123 by calculating the second detection difference Idif2 from the detection values ​​I2 and I3, for example.

[0109] According to this embodiment, when an abnormality occurs in the current sensors 121, 123 in one of the three phases, the control unit 15 uses the detection values ​​I1, I3 in the remaining two phases to identify whether the abnormality has occurred in the first current sensor 121 or the series current sensor 123 in the one phase. In this configuration, the control unit 15 can notify an operator or the like of information such as which of the first current sensor 121 and the series current sensor 123 should be resolved. This reduces the workload of the operator when performing work to resolve the abnormality in the power conversion circuit 4.

[0110] Furthermore, when an abnormality occurs in the current sensors 122, 123 in one of the three phases, the control unit 15 uses the detection values ​​I2, I3 in the remaining two phases to identify whether the abnormality has occurred in the second current sensor 122 or the series current sensor 123 in the one phase. In this configuration, the control unit 15 can notify an operator or the like of information such as which of the second current sensor 122 and the series current sensor 123 should be resolved.

[0111] According to this embodiment, the control unit 15 uses at least one of the first detection value I1 and the second detection value I2 to determine whether or not an abnormality has occurred in the current path including the output lines 13 and 14. Therefore, a configuration can be realized in which the first current sensor 121 and the second current sensor 122 detect an abnormality in the current path.

[0112] 7 and 8 show reference examples of power conversion circuits. Fig. 7 shows an example of a current conduction pattern when star-connected driving is performed in the reference example. Fig. 8 shows a current conduction pattern with timing different from that in Fig. 4 when star-connected driving is performed. In the reference example, the symbols of related elements shown in this embodiment are indicated by adding r to the end.

[0113] The control unit performs star connection drive while switching between multiple current conduction patterns. The control unit performs star connection drive using, for example, a PWM control method. PWM is an abbreviation for Pulse Width Modulation. The multiple current conduction patterns include the zero vector current conduction patterns shown in Figures 7 and 8. The current conduction pattern shown in Figure 7 is a zero vector pattern in which all upper arms 8Hr of the inverter 8r are turned on and all lower arms 8Lr are turned off. The current conduction pattern shown in Figure 8 is a zero vector pattern in which all lower arms 8Lr of the inverter 8r are turned on and all upper arms 8Hr are turned off. The power line 5r has a wiring 5A11r connecting the inverter 8 and the selector switch 10r and a wiring 5A12r connecting the selector switch 10r and the inverter 9r.

[0114] As shown in Figures 7 and 8, in the power conversion circuit 4r of the reference example, the snubber circuit 11r connected in parallel to the inverter 9r is connected to a wiring 5A12r of the power line 5r that connects the selector switch 10r and the inverter 9r. One end of the snubber circuit 11r is connected to the wiring 5A12r of the power line 5r, and the other end is connected to the power line 6r. For convenience, Figures 7 and 8 omit the smoothing capacitor and the snubber circuit connected in parallel to the inverter 8r. Furthermore, the snubber circuit 11r is common to each phase of the inverter 9r.

[0115] In the examples shown in Figures 7 and 8, inverter 9r is neutralized by turning on all three upper arms 9Hr of inverter 9r. In this state, as shown in Figure 7, when all three upper arms 8Hr of inverter 8r are turned on, the voltage across capacitor 11Cr becomes approximately equal to the supply voltage of DC power supply 2r, i.e., power supply voltage Vdc. Furthermore, as shown in Figure 8, when all three lower arms 8Lr of inverter 8r are turned on, the voltage across capacitor 11Cr becomes approximately 0 V (zero volts).

[0116] As described above, star connection driving is performed while switching between multiple current patterns, so the voltage across capacitor 11Cr of snubber circuit 11r fluctuates during star connection driving. The voltage across capacitor 11Cr fluctuates between 0 V and Vdc. As a result, capacitor 11Cr is charged and discharged during star connection driving, resulting in low power conversion efficiency. Resistor 11Rr of snubber circuit 11r consumes the energy stored in capacitor 11Cr and generates heat. This heat affects capacitor 11Cr.

[0117] In contrast to this reference example, in this embodiment, in which the changeover switch 10B is provided on the wiring 6A, the MOSFET of the changeover switch 10B is off, i.e., the changeover switch 10B is in an open state, during star connection driving. Therefore, the potential on the negative side of the capacitor 11C provided in the snubber circuit 11 becomes a floating potential. Therefore, fluctuations in the voltage across the capacitor 11C can be suppressed during star connection driving. In other words, charging and discharging of the capacitor 11C can be suppressed. This improves power conversion efficiency. Furthermore, the effect of heat generated by the resistor 11R due to charging and discharging can be suppressed on the capacitor 11C. This is suitable not only for open connection driving but also for star connection driving.

[0118] <Modification> In the present embodiment, an example has been shown in which the changeover switch 10 is provided on each of the wiring 5A and the wiring 6A, but this is not limiting. The changeover switch 10 may be provided on only one of the wiring 5A and the wiring 6A. For example, as shown in FIG. 9, the changeover switch 10 may be provided on the wiring 5A but not on the wiring 6A.

[0119] In the present embodiment, an example has been shown in which a changeover switch 10 and a snubber circuit 11 are provided for each phase of the upper and lower arm circuits 9HL, but the present invention is not limited to this. For example, as shown in Fig. 10 and Fig. 11, one changeover switch 10 and one snubber circuit 11 may be provided for each of the three-phase upper and lower arm circuits 9HL that constitute the inverter 9.

[0120] In the present embodiment, an example has been shown in which one end of the snubber circuit 11 is connected to the inverter 9 on the power line 5 without passing through the changeover switch 10, but the present invention is not limited to this. For example, as shown in FIGS. 10 and 12 , one end of the snubber circuit 11 may be connected to the inverter 9 on the power line 5 via the changeover switch 10. That is, one end of the snubber circuit 11 may be connected between the changeover switch 10 and the inverter 8 on the wiring 5A. For example, the power line 5 has a wiring 5A1 that connects the inverter 8 and the changeover switch 10, and a wiring 5A2 that connects the changeover switch 10 and the inverter 9. In this configuration, one end of the snubber circuit 11 is connected to the wiring 5A1 of the wiring 5A1 and the wiring 5A2.

[0121] (Second embodiment) This embodiment is a modification based on the previous embodiment, and the description of the previous embodiment can be used. In the previous embodiment, the changeover switch 10 is provided on the power lines 5 and 6, but this is not limiting. In this embodiment, the changeover switch 10 does not have to be provided on the power lines 5 and 6.

[0122] <Power conversion circuit> FIG. 13 shows a power conversion circuit 4 according to this embodiment. The power conversion circuit 4 shown in FIG. 13 does not have a changeover switch 10. In this power conversion circuit 4, the rotating electric machine 3 can be driven in an open connection mode, but cannot be driven in a star connection mode. In normal control and fail-safe control that can drive the rotating electric machine 3, the control unit 15 has a function to drive the rotating electric machine 3 in an open connection mode, but does not have a function to drive the rotating electric machine 3 in a star connection mode.

[0123] (Third embodiment) This embodiment is a modification based on the previous embodiment, and the description of the previous embodiment can be used. In the previous embodiment, the series current sensor 123 is provided on the output line 14, but this is not limiting. In this embodiment, the series current sensor 123 may be provided on the output line 13.

[0124] <Power conversion circuit> FIG. 14 shows a power conversion circuit 4 according to this embodiment. In the power conversion circuit 4 shown in FIG. 14, a series current sensor 123 is provided in output line 13 between windings 3U, 3V, and 3W and inverter 8. Series current sensor 123U detects the current flowing in U-phase output line 13 as the current flowing in U-phase winding 3U. Series current sensor 123V detects the current flowing in V-phase output line 13 as the current flowing in V-phase winding 3V. Series current sensor 123W detects the current flowing in W-phase output line 13 as the current flowing in W-phase winding 3W.

[0125] (Fourth embodiment) This embodiment is a modification based on the previous embodiment, and the description of the previous embodiment can be used. In the previous embodiment, the series current sensor 123 is provided on the output line 14 as an abnormality detection sensor, but this is not limited to this. In this embodiment, the abnormality detection current may be provided on the power supply lines 5 and 6.

[0126] <Power conversion circuit> FIG. 15 shows a power conversion circuit 4 according to this embodiment. In the power conversion circuit 4 shown in FIG. 15, a switching current sensor 124 is provided on the power supply lines 5 and 6. The switching current sensor 124 is included in the drive system 1. The switching current sensor 124 detects the current flowing through the power supply lines 5 and 6. The switching current sensor 124 is a magnetic sensor such as a Hall sensor, similar to the current sensors 121, 122, and 123. Note that the switching current sensor 124 may be formed to include a resistive element such as a shunt resistor.

[0127] In this embodiment, the power conversion circuit 4 does not have a series current sensor 123. The switching current sensor 124 can detect an abnormality in at least one of the first current sensor 121 and the second current sensor 122 by detecting the current flowing through the power supply lines 5 and 6. The switching current sensor 124 corresponds to an abnormality detection sensor.

[0128] The switching current sensors 124 are provided on the wiring 5A and the wiring 6A, respectively. The switching current sensors 124 include a high-potential side switching current sensor 124P and a low-potential side switching current sensor 124N. The switching current sensor 124P detects the current flowing through the wiring 5A. The switching current sensor 124P is provided on the wiring 5A between the inverter 9 and the selector switch 10A. The switching current sensor 124P corresponds to an upper sensor. The switching current sensor 124P may also be provided on the wiring 5A between the inverter 8 and the selector switch 10A.

[0129] The switching current sensor 124N detects the current flowing through the wiring 6A. The switching current sensor 124N is provided on the wiring 6A between the inverter 9 and the changeover switch 10B. The switching current sensor 124N corresponds to a lower sensor. The switching current sensor 124N may also be provided on the wiring 6A between the inverter 8 and the changeover switch 10B.

[0130] The switching current sensor 124 is communicably connected to the control unit 15. The switching current sensor 124 outputs to the control unit 15 a detection signal corresponding to the current flowing through the windings 3U, 3V, and 3W.

[0131] In this embodiment, the rotation control process will be described with reference to the flowchart in Fig. 16. The control unit 15 performs a current detection process in step S201 shown in Fig. 16. The current detection process includes a process for detecting the current flowing through the windings 3U, 3V, and 3W, and a process for detecting the current flowing through the wirings 5A and 6A. The current detection process detects a first detection value I1, a second detection value I2, and a switching detection value I4. The switching detection value I4 is a detection value of the current flowing through the power supply lines 5 and 6. The control unit 15 calculates the switching detection value I4 using a detection signal from the switching current sensor 124. The switching detection value I4 is a detection result of the switching current sensor 124.

[0132] For example, the control unit 15 calculates the switching detection values ​​I4P and I4N using the detection signals of the switching current sensors 124P and 124N. The detection value I4P is the detection value of the current flowing through the wiring 5A. The detection value I4N is the detection value of the current flowing through the wiring 6A.

[0133] In steps S202 to S204, control unit 15 performs an abnormality determination process to determine whether or not an abnormality has occurred in current sensors 121, 122, and 124. In the abnormality determination process, it is determined whether or not an abnormality has occurred in at least one of first current sensor 121, second current sensor 122, and switching current sensor 124. In addition, in the abnormality determination process, it is identified which of first current sensor 121, second current sensor 122, and switching current sensor 124 has the abnormality. The functions of control unit 15 that execute the processes of steps S202 to S204 correspond to a sensor determination unit and a sensor identification unit.

[0134] In step S202, the control unit 15 calculates an estimated value Ic using the detected values ​​I1, I2, and I4. The estimated value Ic is a current value for confirming that the current sensors 121, 122, and 124 are normal. In other words, the estimated value Ic is a value for determining whether or not an abnormality has occurred in the current sensors 121, 122, and 124. The control unit 15 estimates the estimated value Ic using the detected values ​​I1, I2, and I4. The estimated value Ic is a value estimated from at least one of the detected values ​​I1, I2, and I4. The function of the control unit 15 that executes the processing of step S202 corresponds to a current estimation unit. The estimated value Ic corresponds to an estimation result from the current estimation unit.

[0135] The estimated value Ic includes a first estimated value Ic1, a second estimated value Ic2, and a switching estimated value Ic4. The first estimated value Ic1 includes first estimated values ​​Ic1U, Ic1V, and Ic1W. The first estimated values ​​Ic1U, Ic1V, and Ic1W are estimated values ​​of the currents flowing through the output line 13 in the U phase, V phase, and W phase, respectively. The control unit 15 uses four of the five detected values, namely, the first detected values ​​I1U, I1V, and I1W and the switching detected values ​​I4P and I4N, to calculate the first estimated value Ic1 by estimating the remaining detected value. For example, the first estimated value Ic1U is calculated using the four detected values, namely, the first detected values ​​I1V and I1W and the switching detected values ​​I4P and I4N.

[0136] The second estimated value Ic2 includes second estimated values ​​Ic2U, Ic2V, and Ic2W. The second estimated values ​​Ic2U, Ic2V, and Ic2W are estimated values ​​of the currents flowing through the output line 14 in the U phase, V phase, and W phase, respectively. The control unit 15 uses four of the five detected values, namely, the second detected values ​​I2U, I2V, and I2W and the switching detected values ​​I4P and I4N, to calculate the second estimated value Ic2 by estimating the remaining detected value. For example, the second estimated value Ic2U is calculated using the four detected values, namely, the second detected values ​​I2V and I2W and the switching detected values ​​I4P and I4N.

[0137] Control unit 15 calculates estimated value Ic from detected values ​​I1, I2, and I4 using current correlation information indicating the correlation between the currents flowing through output lines 13 and 14 and wirings 5A and 6A. The current correlation information includes correlations between the currents flowing through U-phase winding 3U, V-phase winding 3V, W-phase winding 3W, wiring 5A, and wiring 6A. The current correlation information also includes correlations between the currents flowing through windings 3U, 3V, and 3W and the currents flowing through output line 13 and output line 14. Examples of current correlation information include maps, arithmetic expressions, and functions. The current correlation information is stored in memory 15b, etc.

[0138] In step S203 of the abnormality determination process, the control unit 15 calculates a deviation value Ie using the detected values ​​I1, I2, and I4 and the estimated value Ic. The deviation value Ie is the difference between the detected values ​​I1, I2, and I4 and the estimated value Ic. The deviation value Ie includes a first deviation value Ie1, a second deviation value Ie2, and a switching deviation value Ie4. The first deviation value Ie1 includes first deviation values ​​Ie1U, Ie1V, and Ie1W. The first deviation values ​​Ie1U, Ie1V, and Ie1W are the differences between the first estimated values ​​Ic1U, Ic1V, and Ic1W and the first detected values ​​I1U, I1V, and I1W. The second deviation value Ie2 includes second deviation values ​​Ie2U, Ie2V, and Ie2W. The second deviation values ​​Ie2U, Ie2V, Ie2W are the differences between the second estimated values ​​Ic2U, Ic2V, Ic2W and the second detected values ​​I2U, I2V, I2W. The switching deviation values ​​Ie4 include switching deviation values ​​Ie4P, Ie4N. The switching deviation values ​​Ie4P, Ie4N are the differences between the switching estimated values ​​Ic4P, Ic4N and the switching detected values ​​I4P, I4N.

[0139] In step S204, the control unit 15 determines whether the deviation value Ie is greater than the deviation threshold Je. If the absolute value of the deviation value Ie is greater than the deviation threshold Je, the control unit 15 determines that the deviation value Ie is greater than the deviation threshold Je. The deviation threshold Je is a value determined in advance by testing or the like, and is stored in the memory 15b or the like. The deviation threshold Je is a value that indicates that the deviation value Ie is abnormally large. The deviation value Ie may become greater than the deviation threshold Je when an abnormality such as a failure occurs in the first current sensor 121, the second current sensor 122, or the switching current sensor 124.

[0140] The control unit 15 determines whether each of the first deviation values ​​Ie1U, Ie1V, Ie1W, the second deviation values ​​Ie2U, Ie2V, Ie2W, and the switching deviation values ​​Ie4P and Ie4N is greater than the deviation threshold Je. If at least one of the first deviation values ​​Ie1U, Ie1V, Ie1W, the second deviation values ​​Ie2U, Ie2V, Ie2W, and the switching deviation values ​​Ie4P and Ie4N is greater than the deviation threshold Je, the control unit 15 determines that the deviation value Ie is greater than the deviation threshold Je. In this case, the control unit 15 determines that an abnormality has occurred in at least one of the first current sensors 121U, 121V, 121W, the second current sensors 122U, 122V, 122W, and the switching current sensors 124P and 124N.

[0141] On the other hand, if none of the first deviation values ​​Ie1U, Ie1V, Ie1W, the second deviation values ​​Ie2U, Ie2V, Ie2W, and the switching deviation values ​​Ie4P, Ie4N is greater than the deviation threshold value Je, the control unit 15 determines that the deviation value Ie is not greater than the deviation threshold value Je. In this case, the control unit 15 determines that no abnormality has occurred in any of the first current sensors 121U, 121V, 121W, the second current sensors 122U, 122V, 122W, and the switching current sensors 124P, 124N.

[0142] If the deviation value Ie is not greater than the deviation threshold Je, the control unit 15 proceeds to step S205. In step S205, the control unit 15 determines whether or not a current flow abnormality has occurred using the detection values ​​I1, I2, and I4. The function of the control unit 15 that executes the process of step S205 corresponds to the path determination unit. The control unit 15 can detect abnormalities such as a short circuit that has occurred in the power lines 5 and 6, or an abnormality that has occurred in the selector switch 10, by comparing the switching detection value I4P with the switching detection value I4N, for example.

[0143] If a power supply abnormality occurs, the control unit 15 proceeds to step S215 and performs power supply stop processing similar to step S115 in the first embodiment. If a power supply abnormality does not occur, the control unit 15 performs normal control in steps S206 and S207 similar to steps S105 and S106 in the first embodiment.

[0144] In step S204, if the deviation value Ie is greater than the deviation threshold value Je, the control unit 15 determines that an abnormality has occurred in the current sensors 121, 122, 124, and proceeds to step S208. In step S208, the control unit 15 performs an alert process similar to step S107 in the first embodiment.

[0145] In steps S209 to S214, the control unit 15 performs fail-safe control for driving the rotating electrical machine 3 in a situation where an abnormal sensor is present. In step S209 of the fail-safe control, the control unit 15 determines whether the second current sensor 122 is normal. The second current sensor 122 is sometimes referred to as a three-phase sensor.

[0146] If the second current sensor 122 is normal, the control unit 15 proceeds to step S210 and performs parameter unchanged processing. The parameter unchanged processing is processing for not changing the fail-safe parameters from the normal parameters. The fail-safe parameters are control parameters used for fail-safe control. The control unit 15 sets the first detection value I1 as the fail-safe parameter. The control unit 15 sets the control parameter that was set as the normal parameter in step S206 out of the detection values ​​I1, I2, and I4 as the fail-safe parameter.

[0147] If the second current sensor 122 is not normal, the control unit 15 proceeds to step S211 and performs a parameter change process. The parameter change process is a process for changing the fail-safe parameters from the normal parameters. The control unit 15 sets at least one of the detected values ​​I1U, I1V, I1W, I2U, I2V, I2W, I4P, and I4N that is not an abnormal value as the fail-safe parameter.

[0148] After setting the fail-safe parameters in steps S210 and S211, the control unit 15 performs the same processes as steps S112 to S114 in the first embodiment in steps S212 to S214.

[0149] When performing normal control, the control unit 15 may set all of the detection values ​​I1, I2, and I4 as control parameters. When at least one of the detection values ​​I1, I2, and I4 is an abnormal value, the control unit 15 may set all of the detection values ​​I1, I2, and I4 that are normal values ​​as fail-safe parameters.

[0150] According to this embodiment, the switching current sensor 124 detects the current flowing through the power lines 5 and 6. In this configuration, the first detection value I1, the second detection value I2, and the switching detection value I4 are used to calculate the first estimated value Ic1, the second estimated value Ic2, and the switching estimated value Ic4, thereby detecting that an abnormality has occurred in the first current sensor 121 or the second current sensor 122. This improves the accuracy with which the switching current sensor 124 detects an abnormality in the current sensors 121 and 122.

[0151] (Other embodiments) The disclosure in this specification and drawings, etc. is not limited to the exemplified embodiments. The disclosure encompasses the exemplified embodiments and modifications thereto by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and / or elements shown in the embodiments. The disclosure can be implemented in various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure encompasses the omission of parts and / or elements from the embodiments. The disclosure encompasses the substitution or combination of parts and / or elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. Some disclosed technical scopes are defined by the claims, and should be interpreted as including all modifications within the meaning and scope equivalent to the claims.

[0152] The disclosure in the specification, drawings, etc. is not limited by the claims. The disclosure in the specification, drawings, etc. encompasses the technical ideas described in the claims, and extends to more diverse and broader technical ideas than the technical ideas described in the claims. Therefore, various technical ideas can be extracted from the disclosure in the specification, drawings, etc. without being bound by the claims.

[0153] When an element or layer is referred to as being "on," "coupled," "connected," or "bonded," it may be directly on, coupled, connected, or bonded to the other element or layer, and intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly coupled," "directly connected," or "directly bonded" to another element or layer, no intervening elements or layers are present. Other language used to describe relationships between elements should be construed in a similar manner (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.).

[0154] As used in this specification, the term "and / or" includes any and all combinations of one or more of the associated listed items, i.e., reference to A and / or B means at least one of A and B, and may include A only, B only, or both A and B.

[0155] Spatially relative terms such as "inside," "outside," "back," "below," "low," "top," "top," and the like are used herein to facilitate the description of one element or feature's relationship to other elements or features, as illustrated. Spatially relative terms may be intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were turned over, elements described as "below" or "directly below" other elements or features would then be oriented "above" the other elements or features. Thus, the term "bottom" can encompass both an orientation of top and bottom. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used in this specification would be interpreted accordingly.

[0156] In each of the above embodiments, the current sensors 121, 122, and 123 may be provided in any of the multiple phases. For example, as shown in FIG. 17 , as long as the first current sensor 121 and the second current sensor 122 are each provided in at least one target phase, the first current sensor 121 and the second current sensor 122 may be provided in different phases. Furthermore, as long as the first current sensor 121 and the series current sensor 123 are each provided in at least one target phase, the first current sensor 121 and the series current sensor 123 may be provided in different phases. The first current sensor 121 provided in the target phase corresponds to the target sensor. Furthermore, as long as the second current sensor 122 and the series current sensor 123 are each provided in at least one target phase, the second current sensor 122 and the series current sensor 123 may be provided in different phases. The second current sensor 122 provided in the target phase corresponds to the target sensor.

[0157] In each of the above embodiments, the series current sensor 123 may be provided on either the output line 13 or the output line 14 in different phases. The series current sensor 123 may be provided on the output line 13 in two of the three phases, and on the output line 14 in the remaining phase. For example, the series current sensors 123U and 123V may be provided on the output line 13, while the series current sensor 123W may be provided on the output line 14. Furthermore, the series current sensor 123 may be provided on both the output line 13 and the output line 14 in at least one phase.

[0158] In each of the above embodiments, the switching current sensor 124 may be provided on at least one of the power supply line 5 and the power supply line 6. For example, as shown in FIG. 18 , the switching current sensor 124 may be provided on only one of the power supply line 5 and the power supply line 6.

[0159] In each of the above embodiments, the control unit 15 may use any of the first detection value I1, the second detection value I2, the series detection value I3, and the switching detection value I4 to control the rotating electric machine 3. The control unit 15 may use any of the detection values ​​I1, I2, I3, and I4 to calculate the control parameters. For example, the control unit 15 may calculate an average value of the first detection value I1 and the second detection value I2 and set this average value as the control parameters. In this configuration, when an abnormality occurs in one of the first current sensor 121 and the second current sensor 122, the control unit 15 may set the detection value detected by the non-abnormal current sensor as the control parameters.

[0160] In each of the above embodiments, the drive system 1 may have a 3×n rotating electric machine 3. This drive system 1 has a 3×n power conversion circuit 4 to drive the 3×n rotating electric machine 3, where n is a natural number. For example, in the drive system 1, the 3×n power conversion circuit 4 is realized by connecting n three-phase inverters 8, 9 in parallel to the n×3-phase rotating electric machine 3.

[0161] In each of the above embodiments, the wiring 5A, 6A may directly or indirectly connect the inverter 8 and the inverter 9. For example, the wiring 5A, 6A may electrically connect the inverter 9 and the DC power supply 2 without passing through the inverter 8. In this configuration, the wiring 5A, 6A also indirectly connects the inverter 8 and the inverter 9 via the DC power supply 2.

[0162] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, with the subsequent clause referring to the preceding clause as an alternative. Furthermore, some clauses may be written in a multiple dependent form, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0163] (Technical thought 1) A power conversion device (4) that converts power supplied to a rotating electric machine (3), a first inverter (8) connected to one end of a winding of the rotating electric machine via a first path (13); a second inverter (9) connected to the other end of the winding via a second path (14); a first current sensor (121) that detects a current flowing through the first path; a second current sensor (122) that detects a current flowing through the second path; an abnormality detection sensor (123, 124) for detecting an abnormality in at least one of the first current sensor and the second current sensor; A power conversion device comprising:

[0164] (Technical thought 2) the first current sensor detects a current flowing through the first path in a target phase that is at least one phase of the plurality of phases; The power conversion device according to Technical Idea 1, wherein the second current sensor detects a current flowing through the second path in the target phase.

[0165] (Technical Thought 3) The power conversion device according to Technical Idea 2, wherein the abnormality detection sensor detects a current flowing in at least one of the first path and the second path in the target phase in order to detect an abnormality in at least one of the first current sensor and the second current sensor.

[0166] (Technical Thought 4) the first current sensor detects a current flowing through the first path in each of the three phases; the second current sensor detects a current flowing through the second path in each of the three phases; The power conversion device according to any one of Technical Concepts 1 to 3, wherein the abnormality detection sensor detects a current flowing in at least one of the first path and the second path in each of three phases.

[0167] (Technical Thought 5) a direct path (5, 6) connecting the first inverter and the second inverter without passing through the winding; The power conversion device described in any one of technical ideas 1 to 4, wherein the abnormality detection sensor detects the current flowing in the direct path in order to detect an abnormality in at least one of the first current sensor and the second current sensor.

[0168] (Technical Thought 6) A power conversion device described in any one of technical ideas 1 to 5, which is equipped with a sensor determination unit (S103; S202 to S204) that determines whether an abnormality has occurred in at least one of the target sensor and the abnormality detection sensor using the detection result of the target sensor, which is at least one of the first current sensor and the second current sensor, and the detection result of the abnormality detection sensor.

[0169] (Technical Thought 7) The power conversion device according to Technical Idea 6 is provided with a sensor identification unit (S108 to S110; S202 to S204) that, when the sensor determination unit determines that an abnormality has occurred in at least one of the target sensor and the abnormality detection sensor in one of the three phases, identifies in which of the target sensor and the abnormality detection sensor in the one phase the abnormality has occurred, using the detection results of the target sensor and the abnormality detection sensor in each of the remaining two phases.

[0170] (Technical Thought 8) A power conversion device described in any one of technical ideas 1 to 7, which is equipped with a path determination unit (S104; S205) that uses at least one of the detection results of the first current sensor and the detection results of the second current sensor to determine whether an abnormality has occurred in a current path including the first path and the second path.

[0171] (Technical Thought 9) A rotating electric machine (3), a power converter (4) that converts the power supplied to the rotating electric machine; A drive system (1) that drives the rotating electric machine using the power conversion device, a first inverter (8) connected to one end of a winding of the rotating electric machine via a first path (13); a second inverter (9) connected to the other end of the winding via a second path (14); a first current sensor (121) that detects a current flowing through the first path; a second current sensor (122) that detects a current flowing through the second path; an abnormality detection sensor (123, 124) for detecting an abnormality in at least one of the first current sensor and the second current sensor; A drive system comprising: [Explanation of symbols]

[0172] 1...drive system, 2...DC power supply, 3...rotating electric machine, 3U, 3V, 3W...winding, 4...power conversion circuit, 5, 6...power supply line, 8, 9...inverter, 10...changeover switch, 13, 14...output line, 121...first current sensor, 122...second current sensor, 123...series current sensor, 124...switching current sensor.

Claims

1. A power conversion device (4) that converts power supplied to a rotating electric machine (3), a first inverter (8) connected to one end of a winding of the rotating electric machine via a first path (13); a second inverter (9) connected to the other end of the winding via a second path (14); a first current sensor (121) for detecting a current flowing through the first path; a second current sensor (122) for detecting a current flowing through the second path; an abnormality detection sensor (123, 124) for detecting an abnormality in at least one of the first current sensor and the second current sensor; A power conversion device comprising:

2. the first current sensor detects a current flowing through the first path in a target phase that is at least one of the multiple phases; The power conversion device according to claim 1 , wherein the second current sensor detects a current flowing through the second path in the target phase.

3. 3. The power conversion device according to claim 2, wherein the abnormality detection sensor detects a current flowing in at least one of the first path and the second path in the target phase to detect an abnormality in at least one of the first current sensor and the second current sensor.

4. the first current sensor detects a current flowing through the first path in each of three phases; the second current sensor detects a current flowing through the second path in each of the three phases; 4. The power conversion device according to claim 1, wherein the abnormality detection sensor detects a current flowing in at least one of the first path and the second path for each of three phases.

5. a direct path (5, 6) connecting the first inverter and the second inverter without passing through the winding; The power conversion device according to any one of claims 1 to 3, wherein the abnormality detection sensor detects a current flowing in the direct path in order to detect an abnormality in at least one of the first current sensor and the second current sensor.

6. The power conversion device according to any one of claims 1 to 3, further comprising a sensor determination unit (S103; S202 to S204) that determines whether an abnormality has occurred in at least one of the target sensor and the abnormality detection sensor using the detection result of the target sensor, which is at least one of the first current sensor and the second current sensor, and the detection result of the abnormality detection sensor.

7. 7. The power conversion device according to claim 6, further comprising a sensor identification unit (S108 to S110; S202 to S204) that, when the sensor determination unit determines that an abnormality has occurred in at least one of the target sensor and the abnormality detection sensor in one of the three phases, identifies in which of the target sensor and the abnormality detection sensor in the one phase the abnormality has occurred, using the detection results of the target sensor and the abnormality detection sensor in each of the remaining two phases.

8. A power conversion device according to any one of claims 1 to 3, further comprising a path determination unit (S104; S205) that determines whether an abnormality has occurred in a current path including the first path and the second path using at least one of the detection results of the first current sensor and the second current sensor.

9. A rotating electric machine (3), a power conversion device (4) that converts the power supplied to the rotating electric machine; A drive system (1) comprising: a first inverter (8) connected to one end of a winding of the rotating electric machine via a first path (13); a second inverter (9) connected to the other end of the winding via a second path (14); a first current sensor (121) for detecting a current flowing through the first path; a second current sensor (122) for detecting a current flowing through the second path; an abnormality detection sensor (123, 124) for detecting an abnormality in at least one of the first current sensor and the second current sensor; A drive system comprising:

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