Electric automobile

Abstract

The invention relates to an electric automobile. An electric vehicle is provided with a battery system having a first battery, a second battery, a series connection line, a parallel connection line, and first to fourth relays, a motor, and a power conversion device having a first inverter unit, a second inverter unit, a first change-over switch, and a second change-over switch. When an abnormality occurs in at least one of first upper branches of each phase of a first inverter unit, a second relay is turned on, a first relay, a third relay, and a fourth relay are turned off, and a first change-over switch and a second change-over switch are turned off. The second end side of the three-phase open winding is neutralized by the second inverter unit, and the motor is driven by the switching operation of the intermediate potential switch of each phase and the first lower branch of each phase.

Description

Technical Field

[0001] This disclosure relates to an electrified vehicle. Background Technology

[0002] Conventionally, an electric vehicle comprising a battery, a driving motor, a first inverter section, a second inverter section, and a first switching switch and a second switching switch has been proposed (see, for example, Japanese Patent Application Laid-Open No. 2018-14829). The driving motor has a three-phase open winding. The first inverter section is connected to the positive and negative terminals of the battery and is also connected to the first end of the three-phase open winding. The second inverter section is connected to the side of the positive and negative terminals opposite to the battery from the first inverter section and is also connected to the second end of the three-phase open winding. The first and second switching switches are located between the first and second inverter sections on the positive and negative terminals. Summary of the Invention

[0003] In such electric vehicles, how to perform limp-home driving when an abnormality occurs in the first inverter section or other parts becomes a problem. The main objective of the electric vehicle disclosed herein is to enable limp-home driving when an abnormality occurs in the first inverter section or other parts.

[0004] To achieve the aforementioned main objectives, the electric vehicle of this disclosure adopts the following technical solution. The first, second, and third electric vehicles of this disclosure all possess:

[0005] A battery system comprising a first battery, a second battery, a first relay, a second relay, a third relay, and a fourth relay. The first positive terminal of the first battery is connected to a positive line, and the second negative terminal of the second battery is connected to a negative line. The first relay is located on the positive line, the second relay is located on the negative line, and the third relay is located on a series line connecting the first negative terminal of the first battery to the second positive terminal of the second battery. The fourth relay is located on a parallel line, which connects the side of the series line closer to the first battery than the third relay to the side of the negative line farther from the second battery than the second relay.

[0006] The motor used for driving has a 3-phase open winding;

[0007] A power conversion device includes a first inverter section, a second inverter section, a first switching switch, and a second switching switch. The first inverter section is connected to the positive and negative lines and to the first end of the three-phase open winding. The second inverter section is connected to the positive and negative lines on a side further away from the battery system than the first inverter section and is connected to the second end of the three-phase open winding. The first and second switching switches are disposed between the first and second inverter sections connected to the positive and negative lines.

[0008] Control device,

[0009] in,

[0010] The first inverter section includes a first upper branch and a first lower branch for each phase, a first capacitor, a second capacitor, and intermediate potential switches for each phase. The first upper branch and the first lower branch for each phase are connected in series with respect to the positive and negative lines for each phase, and their connection points are connected to the first end of the three-phase open winding. The first capacitor and the second capacitor are connected in series with respect to the positive and negative lines, and their connection points are connected to the side of the series connection line closer to the second battery than the third relay. The intermediate potential switches for each phase are respectively located on the intermediate potential lines of each phase that connect the connection points of the first upper branch and the first lower branch of each phase to the connection points of the first capacitor and the second capacitor.

[0011] The second inverter section has a second upper branch and a second lower branch for each phase. The second upper branch and the second lower branch for each phase are connected in series with respect to the positive line and the negative line for each phase, and the connection point between them is connected to the second end side of the three-phase open winding.

[0012] Moreover, in the first electric vehicle disclosed herein,

[0013] When an abnormality occurs at least at one of the first upper branches of each phase, the control device sets the second relay to the ON state and sets the first, third, and fourth relays to the OFF state, and sets the first and second switching switches to the OFF state. The second inverter section neutralizes the second terminal of the three-phase open winding, and the motor is driven by operating the intermediate potential switches of each phase and the switches of the first lower branches of each phase.

[0014] When an abnormality occurs at least at one of the first lower branches of each phase, the control device sets the first and third relays to the ON state, sets the second and fourth relays to the OFF state, sets the first and second switching switches to the OFF state, and neutralizes the second terminal side of the three-phase open windings through the second inverter section, and drives the motor through the switching operation of the first upper branch of each phase and the intermediate potential switch of each phase.

[0015] In this way, limp driving is possible when an anomaly occurs at least at one location in the first upper branch of each phase or at least at one location in the first lower branch of each phase.

[0016] In the second electric vehicle disclosed herein,

[0017] When an open circuit fault occurs at at least one of the first upper branch and the first lower branch of each phase, or when a short circuit fault occurs at at least one of the intermediate potential switches of each phase, the control device sets the first relay and the fourth relay to the ON state, sets the second relay and the third relay to the OFF state, sets the first switching switch and the second switching switch to the ON state, sets the first upper branch and the first lower branch of each phase to the OFF state, sets the intermediate potential switches of each phase to the ON state, and drives the motor through the switching operation of the second inverter section.

[0018] In this way, limp driving can be performed when an open circuit fault occurs at least at one of the first upper branch and the first lower branch of each phase, or when a short circuit fault occurs at least at one of the intermediate potential switches of each phase.

[0019] In the third electric vehicle disclosed herein,

[0020] When an open circuit fault occurs at least at one of the first upper branches of each phase, or when a short circuit fault occurs at least at one of the first lower branches of each phase, the control device sets the first relay, the second relay, and the third relay to the ON state, sets the fourth relay to the OFF state, sets the first switching switch and the second switching switch to the ON state, sets the first upper branch of each phase to the OFF state, sets the first lower branch of each phase to the ON state, sets the intermediate potential switch of each phase to the OFF state, and drives the motor through the switching operation of the second inverter section.

[0021] In this way, limp driving can be performed when an open circuit anomaly occurs at least at one location in the first upper branch of each phase, or when a short circuit anomaly occurs at least at one location in the first lower branch of each phase. Attached Figure Description

[0022] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which the same reference numerals show the same elements, and wherein:

[0023] Figure 1 This is a schematic structural diagram showing the schematic structure of a battery electric vehicle 10 according to an embodiment of the present disclosure.

[0024] Figure 2 This is an illustrative diagram showing an example of limp driving when an anomaly occurs at transistor T11.

[0025] Figure 3 This is an illustrative diagram showing an example of limp driving when an anomaly occurs at transistor T14.

[0026] Figure 4 This is an illustrative diagram showing an example of limp driving in the event of an open-circuit fault at transistor T11.

[0027] Figure 5 This is an illustrative diagram showing an example of limp driving in the event of a short-circuit fault at transistor T14. Detailed Implementation

[0028] Referring to the accompanying drawings, a method (implementation method) for carrying out this disclosure is described. Figure 1 This is a schematic structural diagram showing the general structure of a battery electric vehicle 10 according to an embodiment of the present disclosure. As shown, the battery electric vehicle 10 of the embodiment includes a battery system 11, a motor 28, a power conversion device 29, and an electronic control unit (hereinafter referred to as "ECU") 50 (control device).

[0029] The battery system 11 includes a first battery 12, a second battery 13, and a first relay R1 to a fourth relay R4. The first battery 12 and the second battery 13 are configured as, for example, lithium-ion secondary batteries and nickel-metal hydride secondary batteries with a rated voltage of approximately a first voltage Vs1 (e.g., several hundred V), respectively. In this embodiment, the first battery 12 and the second battery 13 use batteries of the same specification.

[0030] The first positive terminal of the first battery 12 is connected to the positive line 21. The second negative terminal of the second battery 13 is connected to the negative line 23. The first relay R1 is connected to the positive line 21. The second relay R2 is connected to the negative line 23. The third relay R3 is connected to the series line 15, which connects the first negative terminal of the first battery 12 to the second positive terminal of the second battery 13. The fourth relay R4 is connected to the parallel line 16, which connects the side of the series line 15 closer to the first battery 12 than the third relay R3, and the side of the negative line 23 further away from the second battery 13 than the second relay R4.

[0031] Motor 28 is configured as a three-phase AC motor, comprising a rotor in which permanent magnets are embedded in the rotor core and a stator in which three-phase (U-phase, V-phase, W-phase) coils (open windings) are wound on the stator core. The rotor is connected to a drive shaft that is connected to the drive wheel via a differential gear.

[0032] The power conversion device 29 includes a first inverter section 30, a second inverter section 36, and a first switching switch 40a and a second switching switch 40b. The first inverter section 30 is connected to the positive line 21, the intermediate potential line 22, and the negative line 23, and is also connected to the first end of the three-phase coil of the motor 28. The first inverter section 30 is a T-type three-level inverter. Specifically, it includes six transistors T11 to T16, diodes D11 to D16, two capacitors 31 and 32, three-phase intermediate potential lines 33u, 33v, and 33w, and three-phase intermediate potential switches 34u, 34v, and 34w. The six diodes D11 to D16 are connected in parallel to the six transistors T11 to T16. The three phases refer to the U phase, V phase, and W phase. Transistors T11 to T16 are, for example, MOSFETs or IGBTs. Transistors T11 to T16 are arranged in pairs, with the positive line 21 and the negative line 23 forming the source and sink sides, respectively. The connection points of transistors T11 and T14, T12 and T15, and T13 and T16 are connected to the first terminals of the U-phase, V-phase, and W-phase coils of the motor 28, respectively. Hereinafter, transistors T11 to T13 are sometimes referred to as the "first upper branch," and transistors T14 to T16 as the "first lower branch." Capacitors 31 and 32 are connected in series with respect to the positive line 21 and the negative line 23. Capacitors 31 and 32 are of the same specification. The connection points of capacitors 31 and 32 are connected via the intermediate potential line 22 to the side of the series connection line 15 closer to the second battery 13 than the third relay R3. The three-phase intermediate potential lines 33u, 33v, and 33w connect the connection points of transistors T11 and T14, T12 and T15, and T13 and T16 to the connection points of capacitors 31 and 32, respectively. Three-phase intermediate potential switches 34u, 34v, and 34w are respectively located on the three-phase intermediate potential lines 33u, 33v, and 33w. The three-phase intermediate potential switches 34u, 34v, and 34w can be semiconductor switches, specifically wide-bandgap semiconductor switches using gallium nitride (GaN) or silicon carbide (SiC). The intermediate potential switch 34u can be configured by using two sets of transistors and diodes connected in parallel, or by connecting diodes in series in reverse order. The intermediate potential switches 34v and 34w are configured similarly.

[0033] The second inverter section 36 is connected to the positive line 21 and the negative line 23 on a side further away from the battery system 11 than the first inverter section 30. The second inverter section 36 includes a two-level inverter, specifically comprising six transistors T21 to T26, six diodes D21 to D26 connected in parallel with each of the six transistors T21 to T26, and a capacitor 37. Transistors T21 to T26 are, for example, MOSFETs or IGBTs. Transistors T21 to T26 are arranged in pairs relative to the positive line 21 and the negative line 23, forming a source side and a sink side. The connection points of transistors T21 and T24, T22 and T25, and T23 and T26 are respectively connected to the second terminals of the U-phase, V-phase, and W-phase coils of the motor 28. Hereinafter, transistors T21 to T23 are sometimes referred to as the "second upper branch," and transistors T24 to T26 are referred to as the "second lower branch." Capacitor 37 is connected to the positive line 21 and the negative line 23.

[0034] The first switching switch 40a and the second switching switch 40b are respectively disposed between the first inverter section 30 and the second inverter section 36 of the positive line 21 and the negative line 23. The first switching switch 40a and the second switching switch 40b are respectively constructed using, for example, semiconductor switches. The first switching switch 40a may use, for example, a group of two transistors and diodes connected in parallel with it, or the diodes may be connected in series in reverse order. The second switching switch 40b is constructed similarly.

[0035] ECU50 is equipped with a microcomputer containing a CPU, ROM, RAM, flash memory, input / output ports, and communication ports, as well as various drive circuits and logic ICs. Signals from various sensors are input to ECU50. For example, voltages Vb1 and Vb2, and currents Ip1 and Ip2 are input to ECU50. Voltage Vb1 is the voltage from the first battery 12 of voltage sensor 12V. Voltage Vb2 is the voltage from the second battery 13 of voltage sensor 13V. Current Ip1 is the current from the positive line 21 of current sensor 21i. Current Ip2 is the current from the intermediate potential line 22 of current sensor 22i. ECU50 also receives the rotational position θm of the rotor of motor 28 from rotational position sensor 28a, and the phase currents Iu, Iv, and Iw of each phase of motor 28 from current sensors 28u, 28v, and 28w. The ECU 50 also receives inputs of voltage Vc1 from capacitor 31 (voltage sensor 31V), voltage Vc2 from capacitor 32 (voltage sensor 32V), and voltage Vc3 from capacitor 37 (voltage sensor 37V). The ECU 50 also receives inputs of on / off signals, gear position SP, accelerator pedal opening Acc, brake pedal position BP, and vehicle speed V. The on / off signals are inputs from the power switch. Gear position SP is the gear lever's operating position, received from the gear position sensor. Accelerator pedal opening Acc is the accelerator pedal's depressed position, received from the accelerator pedal position sensor. Brake pedal position BP is the brake pedal's depressed position, received from the brake pedal position sensor. Vehicle speed V is an input from the vehicle speed sensor.

[0036] The ECU 50 calculates the charge ratios SOC1 and SOC2 of the first battery 12 and the second battery 13, or calculates the electrical angle θe and rotational speed Nm of the motor 28. The charge ratios SOC1 and SOC2 of the first battery 12 and the second battery 13 are calculated based on the states of the first relay R1 to the fourth relay R4 and the currents Ip1 and Ip2 of the positive line 21 and the intermediate potential line 22. The electrical angle θe and rotational speed Nm of the motor 28 are calculated based on the rotational position θm of the rotor. Various control signals are output from the ECU 50. For example, control signals are output from the ECU 50 to the battery system 11, to the first inverter unit 30, to the second inverter unit 36, and to the first switching switch 40a and the second switching switch 40b. The battery system 11 includes the first relay R1 to the fourth relay R4. The first inverter section 30 includes transistors T11 to T16 and three-phase intermediate potential switches 34u, 34v, and 34w. The second inverter section 36 includes transistors T21 to T26.

[0037] In the battery electric vehicle 10 of the embodiment, the ECU 50 sets the required torque Td* for driving based on the accelerator opening Acc and the vehicle speed V. The ECU 50 sets the torque command Tm* of the motor 28 to drive with the set required torque Td*. Further, based on the set torque command Tm*, the ECU 50 basically selects one of the following modes for driving: a two-level H drive mode, a two-level Y drive mode, and a three-level Y drive mode. Here, H drive refers to driving the motor 28 by switching the first inverter section 30 and the second inverter section 36. Y drive refers to neutralizing the side closer to the second inverter section 36 (the second end of the three-phase coil) than the motor 28 and driving the motor 28 by switching the first inverter section 30. Regardless of whether it is a two-level H-drive mode, a two-level Y-drive mode, or a three-level Y-drive mode, for battery system 11, the first relay R1, the second relay R2, and the third relay R3 are all turned on, while the fourth relay R4 is turned off. That is, the first battery 12 and the second battery 13 are connected in series.

[0038] The two-level H-drive mode is explained. In this mode, the first switching switch 40a and the second switching switch 40b are turned on. Furthermore, regarding the first inverter section 30 and the second inverter section 36, the three-phase intermediate potential switches 34u, 34v, and 34w are turned off, and transistors T11 to T16 and T21 to T26 are switched on and off. In this way, the potentials of the first and second terminals of the motor 28 are switched according to two levels (the potential of the positive line 21 and the potential of the negative line 23).

[0039] The two-level Y-drive mode is explained. In this mode, the first switching switch 40a and the second switching switch 40b are set to the off state. Furthermore, regarding the second inverter section 36, one of the three-phase second upper branch (transistors T21 to T23) and the three-phase second lower branch (transistors T24 to T26) is set to the on state, while the other is set to the off state. This neutralizes the side closer to the second inverter section 36 than the motor 28 (the second end of the three-phase coil). Furthermore, since the first switching switch 40a and the second switching switch 40b are set to the off state, transistors T21 to T26 can also be set to the on state. Further, regarding the first inverter section 30, the three-phase intermediate potential switches 34u, 34v, and 34w are set to the off state, and transistors T11 to T16 are switched on and off. In this way, the potential of the first terminal side of the motor 28 is switched according to two levels (the potential of the positive line 21 and the potential of the negative line 23).

[0040] The three-level Y-drive mode is explained. This mode differs from the two-level Y-drive mode in that it drives the switching of the intermediate potential switches 34u, 34v, and 34w of the three phases and transistors T11 to T16 with respect to the first inverter section 30. In this way, the potential of the first terminal side of the motor 28 is switched according to three levels (the potential of the positive line 21, the potential of the connection point of capacitors 31 and 32, and the potential of the negative line 23).

[0041] Next, the operation of the battery electric vehicle 10 according to the embodiment will be explained, in particular, the operation in the case of limp driving due to an abnormality at the power conversion device 29 will be explained. First, the case of an abnormality at the first switch 40a and the second switch 40b will be explained. When an open circuit abnormality occurs at at least one of the first switch 40a and the second switch 40b, the first switch 40a and the second switch 40b will be set to the off state. As a result, the above-mentioned two-level Y drive mode and three-level Y drive mode can be executed for limp driving. In addition, when a short circuit abnormality occurs at at least one of the first switch 40a and the second switch 40b, the first switch 40a and the second switch 40b will be set to the on state. As a result, the two-level H drive mode can be executed for limp driving.

[0042] Next, the abnormal situations occurring at the second inverter section 36 will be explained. There are cases where a short circuit occurs at least at one of the three phases of the second upper branch (transistors T21 to T23) of the second inverter section 36, and at least one of the three phases of the second lower branch (transistors T24 to T26) experiences an open circuit. In these cases, the first switching switch 40a and the second switching switch 40b are set to the open state, the three phases of the second upper branch are set to the on state, and the three phases of the second lower branch are set to the open state. Additionally, there are cases where an open circuit occurs at least at one of the three phases of the second upper branch, and at least one of the three phases of the second lower branch experiences a short circuit. In these cases, the first switching switch 40a and the second switching switch 40b are set to the open state, the three phases of the second upper branch are set to the open state, and the three phases of the second lower branch are set to the on state. Therefore, it is possible to perform limp driving by executing two-level Y-drive mode and three-level Y-drive mode.

[0043] Next, we will explain the situation where an abnormality occurred at the first inverter section 30. First, we will explain the situation where an abnormality (short circuit abnormality, open circuit abnormality) occurred at at least one of the three phases of the first upper branch (transistor T11 to transistor T13) of the first inverter section 30. Figure 2This is an explanatory diagram illustrating an example of limp driving in the event of an anomaly at transistor T11. As shown, when an anomaly occurs at transistor T11, relays R1, R3, and R4 are set to the off state, and relay R2 is set to the on state. Therefore, only battery 13 of battery 12 and battery 13 is connected to the first inverter section 30 side, and the first upper branch of the three phases connected to the positive line 21 (transistors T11 to T13) is disconnected from the battery system 11 (first battery 12). Furthermore, similar to the two-level Y-drive mode and the three-level Y-drive mode described above, switches 40a and 40b are set to the off state, and the side closer to the second inverter section 36 than the motor 28 is neutralized. Figure 2 In this configuration, the second upper branch of the three phases (transistors T21 to T23) is turned on, while the second lower branch of the three phases (transistors T24 to T26) is turned off. Furthermore, transistors T12 and T13 are turned off. Then, the intermediate potential switches 34u, 34v, and 34w of the three phases and transistors T14 to T16 are switched on. Thus, the intermediate potential switches 34u, 34v, and 34w of the three phases function as a replacement for the first upper branch of the three phases (transistors T11 to T13), enabling the first inverter unit 30 to operate as a two-level inverter. In this way, limp-riding can be achieved using power from the second battery 13. Here, the case of an abnormality occurring at transistor T11 is described, but the same considerations can be made for abnormalities occurring at either transistor T12 or T13, or at multiple transistors from T11 to T13.

[0044] Next, it will be explained that an abnormality (short circuit abnormality, open circuit abnormality) occurred at least one of the three lower branches (transistors T14 to T16) of the three phases of the first inverter section 30. Figure 3This is an explanatory diagram illustrating an example of limp driving in the event of an anomaly at transistor T14. As shown, when a short-circuit anomaly occurs at transistor T14, the second relay R2 and the fourth relay R4 are set to the open state, and the first relay R1 and the third relay R3 are set to the closed state. Therefore, only the first battery 12 of the first battery 12 and the second battery 13 is connected to the first inverter section 30 side, and the first lower branch of the three phases connected to the negative line 23 (transistors T14 to T16) is disconnected from the battery system 11 (second battery 13). Furthermore, similar to the two-level Y-drive mode and the three-level Y-drive mode described above, the first switching switch 40a and the second switching switch 40b are set to the open state, and the side closer to the second inverter section 36 than the motor 28 is neutralized. Figure 3 In this configuration, the second upper branch of the three phases (transistors T21 to T23) is turned on, while the second lower branch of the three phases (transistors T24 to T26) is turned off. Furthermore, transistors T15 and T16 are turned off. Then, the intermediate potential switches 34u, 34v, and 34w of the three phases and transistors T11 to T13 are switched on. Thus, the intermediate potential switches 34u, 34v, and 34w of the three phases function as a replacement for the first lower branch of the three phases (transistors T14 to T16), enabling the first inverter unit 30 to operate as a two-level inverter. In this way, limp-riding can be achieved using power from the first battery 12. Here, the case of an abnormality occurring at transistor T14 is described, but the same consideration can be made if an abnormality occurs at one of transistors T15 or T16, or if an abnormality occurs at multiple transistors from T14 to T16.

[0045] Then, it is explained that a short circuit abnormality occurred at at least one of the three-phase intermediate potential switches 34u, 34v, and 34w. Figure 4This is an explanatory diagram illustrating an example of limp-driving when a short circuit occurs at at least one of the three-phase intermediate potential switches 34u, 34v, and 34w. As shown, a short circuit sometimes occurs at at least one of the three-phase intermediate potential switches 34u, 34v, and 34w. In this case, the first relay R1 and the fourth relay R4 are turned on, while the second relay R2 and the third relay R3 are turned off. Transistors T12 to T16 are turned off, and the three-phase intermediate potential switches 34u, 34v, and 34w are turned on. This neutralizes the side of the motor 28 closer to the first inverter section 30. Additionally, the first switching switch 40a and the second switching switch 40b are turned on. Furthermore, the transistors T21 to T26 of the second inverter section 36 are switched on and off. In this way, limp-driving can be performed using power from the first battery 12. Alternatively, instead of setting the second relay R2 and the fourth relay R4 to the off state while setting the first relay R1 and the third relay R3 to the on state, the fourth relay R4 can be set to the off state while setting the first relay R1, the second relay R2, and the third relay R3 to the on state.

[0046] Furthermore, it indicates that an open-circuit fault occurred at at least one of the three-phase intermediate potential switches 34u, 34v, and 34w. In this case, the three-phase intermediate potential switches 34u, 34v, and 34w are set to the open state. This allows for limp-drive operation in both two-level H-drive mode and two-level Y-drive mode.

[0047] Sometimes, an abnormality (short circuit abnormality, open circuit abnormality) occurs at least at one of the three phases of the first upper branch (transistor T11 to transistor T13) in the first inverter section 30. In this case, in the above embodiment, the first relay R1, the third relay R3, and the fourth relay R4 are set to the off state, while the second relay R2 is set to the on state. Further, the first switching switch 40a and the second switching switch 40b are set to the off state. Further, the neutral point is made on the side closer to the second inverter section 36 than the motor 28. Then, further, the intermediate potential switches 34u, 34v, and 34w of the three phases and transistors T14 to T16 are switched (see reference). Figure 2Additionally, sometimes an abnormality (short circuit abnormality, open circuit abnormality) occurs at least at one of the three phases of the first lower branch (transistor T14 to transistor T16) in the first inverter section 30. In this case, the second relay R2 and the fourth relay R4 are set to the open state, while the first relay R1 and the third relay R3 are set to the closed state. Further, the first switching switch 40a and the second switching switch 40b are set to the open state. Further, the neutral point is made on the side closer to the second inverter section 36 than the motor 28. Then, further, the switching drive is set to the intermediate potential switches 34u, 34v, and 34w of the three phases and transistors T11 to T13 (see reference). Figure 3 However, in the event of an open-circuit fault at at least one of the first upper branch and the first lower branch of the three phases, control can be applied in the same manner as in the event of a short-circuit fault at at least one of the intermediate potential switches 34u, 34v, and 34w of the three phases (see reference). Figure 4 ).

[0048] Sometimes, an abnormality (short circuit abnormality, open circuit abnormality) occurs at least at one of the three phases of the first lower branch (transistor T14 to transistor T16) in the first inverter section 30. In this case, in the above embodiment, the second relay R2 and the fourth relay R4 are set to the off state, while the first relay R1 and the third relay R3 are set to the on state. Further, the first switching switch 40a and the second switching switch 40b are set to the off state. Further, the neutral point is made on the side closer to the second inverter section 36 than the motor 28. Then, further, the intermediate potential switches 34u, 34v, and 34w of the three phases and transistors T11 to T13 are switched (see reference). Figure 3 However, if a short circuit occurs at the first lower branch of the three phases of the first inverter section 30, the following control can also be performed.

[0049] Figure 5This is an explanatory diagram illustrating an example of limp-driving in the event of a short-circuit fault at transistor T14. As shown, when a short-circuit fault occurs at transistor T14, transistors T15 and T16 are turned on, while transistors T11 through T13 are turned off. Additionally, relays R1, R2, and R3 are turned on, relay R4 is turned off, and the three-phase intermediate potential switches 34u, 34v, and 34w are turned off. This neutralizes the side closer to the first inverter section 30 than the motor 28. This neutral point is connected to the negative line 23. Then, transistors T21 through T26 of the second inverter section 36 are switched on and off. In this way, limp-driving can be performed using power from the first battery 12 and the second battery 13. Here, the case of a short-circuit fault occurring at transistor T14 has been explained. However, the same consideration can also be given to cases where a short-circuit fault occurs at one of transistors T15 or T16, or at multiple transistors from T14 to T16. Alternatively, the same consideration can also be given to cases where an open-circuit fault occurs at at least one of transistors from T11 to T13.

[0050] The above description describes the methods for implementing this disclosure using embodiments, but this disclosure is not limited to such embodiments in any way, and can of course be implemented in various ways without departing from the spirit of this disclosure.

[0051] This disclosure can be applied to industries such as electric vehicle manufacturing.

Claims

1. An electric vehicle, comprising: A battery system comprising a first battery, a second battery, a first relay, a second relay, a third relay, and a fourth relay. The first positive terminal of the first battery is connected to a positive line, and the second negative terminal of the second battery is connected to a negative line. The first relay is located on the positive line, the second relay is located on the negative line, and the third relay is located on a series line connecting the first negative terminal of the first battery to the second positive terminal of the second battery. The fourth relay is located on a parallel line, which connects the side of the series line closer to the first battery than the third relay to the side of the negative line farther from the second battery than the second relay. The motor used for driving has a 3-phase open winding; A power conversion device includes a first inverter section, a second inverter section, a first switching switch, and a second switching switch. The first inverter section is connected to the positive and negative lines and to the first end of the three-phase open winding. The second inverter section is connected to the positive and negative lines on a side further away from the battery system than the first inverter section and is connected to the second end of the three-phase open winding. The first and second switching switches are disposed between the first and second inverter sections connected to the positive and negative lines. Control device, in, The first inverter section includes a first upper branch and a first lower branch for each phase, a first capacitor, a second capacitor, and intermediate potential switches for each phase. The first upper branch and the first lower branch for each phase are connected in series with respect to the positive and negative lines for each phase, and their connection points are connected to the first end of the three-phase open winding. The first capacitor and the second capacitor are connected in series with respect to the positive and negative lines, and their connection points are connected to the side of the series connection line closer to the second battery than the third relay. The intermediate potential switches for each phase are respectively located on the intermediate potential lines of each phase that connect the connection points of the first upper branch and the first lower branch of each phase to the connection points of the first capacitor and the second capacitor. The second inverter section has a second upper branch and a second lower branch for each phase. The second upper branch and the second lower branch for each phase are connected in series with respect to the positive and negative lines for each phase, and the connection points are connected to the second end of the three-phase open winding. When an abnormality occurs at least at one of the first upper branches of each phase, the control device sets the second relay to the ON state and sets the first, third, and fourth relays to the OFF state, and sets the first and second switching switches to the OFF state. The second inverter section neutralizes the second terminal of the three-phase open winding, and the motor is driven by operating the intermediate potential switches of each phase and the switches of the first lower branches of each phase. When an abnormality occurs at least at one of the first lower branches of each phase, the control device sets the first and third relays to the ON state, sets the second and fourth relays to the OFF state, sets the first and second switching switches to the OFF state, and neutralizes the second terminal side of the three-phase open windings through the second inverter section, and drives the motor through the switching operation of the first upper branch of each phase and the intermediate potential switch of each phase.

2. An electric vehicle, comprising: A battery system comprising a first battery, a second battery, a first relay, a second relay, a third relay, and a fourth relay. The first positive terminal of the first battery is connected to a positive line, and the second negative terminal of the second battery is connected to a negative line. The first relay is located on the positive line, the second relay is located on the negative line, and the third relay is located on a series line connecting the first negative terminal of the first battery to the second positive terminal of the second battery. The fourth relay is located on a parallel line, which connects the side of the series line closer to the first battery than the third relay to the side of the negative line farther from the second battery than the second relay. The motor used for driving has a 3-phase open winding; A power conversion device includes a first inverter section, a second inverter section, a first switching switch, and a second switching switch. The first inverter section is connected to the positive and negative lines and to the first end of the three-phase open winding. The second inverter section is connected to the positive and negative lines on a side further away from the battery system than the first inverter section and is connected to the second end of the three-phase open winding. The first and second switching switches are disposed between the first and second inverter sections connected to the positive and negative lines. Control device, in, The first inverter section includes a first upper branch and a first lower branch for each phase, a first capacitor, a second capacitor, and intermediate potential switches for each phase. The first upper branch and the first lower branch for each phase are connected in series with respect to the positive and negative lines for each phase, and their connection points are connected to the first end of the three-phase open winding. The first capacitor and the second capacitor are connected in series with respect to the positive and negative lines, and their connection points are connected to the side of the series connection line closer to the second battery than the third relay. The intermediate potential switches for each phase are respectively located on the intermediate potential lines of each phase that connect the connection points of the first upper branch and the first lower branch of each phase to the connection points of the first capacitor and the second capacitor. The second inverter section has a second upper branch and a second lower branch for each phase. The second upper branch and the second lower branch for each phase are connected in series with respect to the positive and negative lines for each phase, and the connection points are connected to the second end of the three-phase open winding. When an open circuit fault occurs at at least one of the first upper branch and the first lower branch of each phase, or when a short circuit fault occurs at at least one of the intermediate potential switches of each phase, the control device sets the first relay and the fourth relay to the ON state, sets the second relay and the third relay to the OFF state, sets the first switching switch and the second switching switch to the ON state, sets the first upper branch and the first lower branch of each phase to the OFF state, sets the intermediate potential switches of each phase to the ON state, and drives the motor through the switching operation of the second inverter section.

3. An electric vehicle, comprising: A battery system comprising a first battery, a second battery, a first relay, a second relay, a third relay, and a fourth relay. The first positive terminal of the first battery is connected to a positive line, and the second negative terminal of the second battery is connected to a negative line. The first relay is located on the positive line, the second relay is located on the negative line, the third relay is located on a series line connecting the first negative terminal of the first battery and the second positive terminal of the second battery, and the fourth relay is located on a parallel line. The side of the series line closer to the first battery than the third relay is connected to the side of the negative line farther from the second battery than the second relay. The motor used for driving has a 3-phase open winding; A power conversion device includes a first inverter section, a second inverter section, a first switching switch, and a second switching switch. The first inverter section is connected to the positive and negative lines and to the first end of the three-phase open winding. The second inverter section is connected to the positive and negative lines on a side further away from the battery system than the first inverter section and is connected to the second end of the three-phase open winding. The first and second switching switches are disposed between the first and second inverter sections connected to the positive and negative lines. Control device, in, The first inverter section includes a first upper branch and a first lower branch for each phase, a first capacitor, a second capacitor, and intermediate potential switches for each phase. The first upper branch and the first lower branch for each phase are connected in series with respect to the positive and negative lines for each phase, and their connection points are connected to the first end of the three-phase open winding. The first capacitor and the second capacitor are connected in series with respect to the positive and negative lines, and their connection points are connected to the side of the series connection line closer to the second battery than the third relay. The intermediate potential switches for each phase are respectively located on the intermediate potential lines of each phase that connect the connection points of the first upper branch and the first lower branch of each phase to the connection points of the first capacitor and the second capacitor. The second inverter section has a second upper branch and a second lower branch for each phase. The second upper branch and the second lower branch for each phase are connected in series with respect to the positive and negative lines for each phase, and the connection points are connected to the second end of the three-phase open winding. When an open circuit fault occurs at least at one of the first upper branches of each phase, or when a short circuit fault occurs at least at one of the first lower branches of each phase, the control device sets the first relay, the second relay, and the third relay to the ON state, sets the fourth relay to the OFF state, sets the first switching switch and the second switching switch to the ON state, sets the first upper branch of each phase to the OFF state, sets the first lower branch of each phase to the ON state, sets the intermediate potential switch of each phase to the OFF state, and drives the motor through the switching operation of the second inverter section.

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