Electric vehicle control device

Abstract

To effectively avoid an overvoltage breakdown of a component, and reduce the size and cost of a control device.SOLUTION: An electric vehicle control device controls an electric vehicle that includes a boost converter that boosts a voltage of a battery and outputs a boosted voltage, an inverter that converts the boosted voltage into an AC voltage, a drive motor that is driven by application of the AC voltage, and a relay circuit that switches between connection and disconnection between the boost converter and the battery. A failure detection unit detects a failure of the boost converter. A rotational speed detector detects a rotational speed of the drive motor. If a failure of the boost converter is detected by the failure detection unit and the rotation speed detection unit when the rotation speed of the drive motor is equal to or higher than a predetermined value, a control unit maintains a connected state of the relay circuit until a charging voltage of the battery reaches a threshold value, and switches the relay circuit to a cut-off state when it is determined that the charging voltage of the battery exceeds the threshold value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for an electric vehicle. [Background technology]

[0002] Electric vehicle control devices that control electric vehicles such as hybrid cars are equipped with a boost converter that boosts the battery voltage and an inverter that converts the boosted voltage into AC voltage, and are configured to control the power supplied to the drive motor. In such control devices, back electromotive force may be generated in the drive motor when the vehicle decelerates, and this back electromotive force may be regenerated into the battery. To prevent damage to the battery or electronic components due to this back electromotive force, techniques are known that perform fail-safe control, such as shutting off a relay circuit or stopping inverter operation (see, for example, Patent Documents 1 and 2).

[0003] When the relay circuit is interrupted, the battery is protected from overcharging, but excessive voltage may be applied to components other than the battery, leading to overvoltage breakdown. Therefore, control is required to prevent overvoltage breakdown of these other components when the relay circuit is interrupted. If such control is performed accurately, it will be possible to use low-voltage components, thereby enabling the control device to be made smaller and less expensive. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-76768 [Patent Document 2] International Publication No. 2016 / 076429 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides an electric vehicle control device that can effectively avoid overvoltage breakdown of components and enable the control device to be made smaller and less expensive. [Means for solving the problem]

[0006] The electric vehicle control device according to the present invention controls an electric vehicle including a boost converter that boosts a battery voltage and outputs the boosted voltage, an inverter that converts the boosted voltage into an AC voltage, a drive motor that is driven by the AC voltage, and a relay circuit that switches between connection and disconnection between the boost converter and the battery. A fault detection unit detects a fault in the boost converter. A rotation speed detection unit detects the rotation speed of the drive motor. If the fault detection unit and the rotation speed detection unit detect a fault in the boost converter when the rotation speed of the drive motor is equal to or higher than a predetermined value, a control unit maintains the connection state of the relay circuit until the charging voltage of the battery reaches a threshold, and switches the relay circuit to a disconnected state when it determines that the charging voltage of the battery will exceed the threshold. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an electric vehicle control device that can effectively avoid overvoltage breakdown of components and enable the control device to be made smaller and less expensive. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing the overall configuration of an electric vehicle control system 1 according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a circuit diagram illustrating the detailed configuration of a PCU 15. [Figure 3] 4 is a timing chart showing the operation of the hybrid vehicle control system 1 of the first embodiment. [Figure 4] 3 is a flowchart showing the operation of the hybrid vehicle control system 1 of the first embodiment. [Figure 5]6 is a flowchart showing the operation of the hybrid vehicle control system 1 of the second embodiment. [Figure 6] The three-phase short control performed by the hybrid vehicle control system 1 of the second embodiment will be described. [Figure 7] 4 is a timing chart showing the operation of a hybrid vehicle control system of a comparative example. [Figure 8] 4 is a graph showing the operation of a hybrid vehicle control system of a comparative example. [Figure 9] 4 is a graph showing the operation of a hybrid vehicle control system of a comparative example. [Figure 10] 4 is a graph showing the operation of a hybrid vehicle control system of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. The accompanying drawings show embodiments and implementation examples according to the principles of the present disclosure, but these are for understanding the present disclosure and are not to be used to interpret the present disclosure in a limiting manner. The description in this specification is merely a typical example and does not limit the scope or application of the present disclosure in any sense.

[0010] Although the present embodiment has been described in sufficient detail to enable those skilled in the art to implement the present disclosure, it should be understood that other implementations and forms are possible, and that changes in configuration and structure and substitutions of various elements are possible without departing from the scope and spirit of the technical ideas of the present disclosure. Therefore, the following description should not be interpreted as being limited thereto.

[0011] [First embodiment] An electric vehicle control system 1 according to a first embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing the overall configuration of the electric vehicle control system 1, and Figure 2 is a circuit diagram showing the detailed configuration of the PCU 15.

[0012] The electric vehicle control system 1 is a system for controlling a hybrid vehicle. The hybrid vehicle is equipped with, for example, an engine 11, a generator motor (MG1) 12, a drive motor (MG2) 13, a battery 14, and an electric compressor 16. The electric vehicle control system 1 includes an ECU (Electric Control Unit) 6, which controls a PCU (Power Control Unit) 15 and the engine 11. The electric compressor 16 is connected to the battery 14 and generates compressed air for operating pneumatic equipment (such as an air conditioner) of the hybrid vehicle.

[0013] The ECU 6 incorporates a microcomputer 51 and is connected to a display device 52. The ECU 6 displays various information on the display device 52 to present the information to the driver of the vehicle. The microcomputer 51 incorporates, for example, a CPU (Central Processing Unit), a non-volatile memory such as a flash memory, and a volatile memory such as a DRAM (Dynamic Random Access Memory). The ECU 6 receives detection signals from various sensors (accelerator sensor, vehicle speed sensor, rotation speed sensor, G sensor, current sensor, voltage sensor, pressure sensor, etc., none of which are shown) required for control. In addition to the detection signals received from the various sensors, the ECU 6 also receives information required for control from other ECUs (not shown).

[0014] The engine 11 is, for example, a gasoline engine, and is equipped with valves that control the intake and exhaust of air into the combustion chamber, injectors that inject fuel into the intake air, spark plugs that generate an electrical discharge in the combustion chamber, etc. An engine gear 21 is provided on a crankshaft 22, which is the output shaft of the engine 11, so as to rotate integrally with the crankshaft 22.

[0015] The generator motor 12 and the drive motor 13 are, for example, permanent magnet synchronous motors (PMSMs). A permanent magnet synchronous motor includes a stator and a rotor. The stator includes a stator core and a coil. When a current flows through the stator coil, magnetic flux is generated that extends in the radial direction of rotation along the teeth. This magnetic flux acts on the permanent magnet of the rotor, generating a rotational force in the rotor.

[0016] The rotor of the generator motor 12 has a rotating shaft 23. A generator motor gear 24 is provided on the rotating shaft 23 so as to rotate integrally with the rotating shaft 23. The generator motor gear 24 is in mesh with the crankshaft 22.

[0017] The rotor of the drive motor 13 has a rotary shaft 25. A drive motor gear 26 is provided on the rotary shaft 25 so as to rotate integrally therewith. The rotary shaft 25 is connected to the drive train of the hybrid vehicle via the drive motor gear 26. The drive train includes an output shaft 31, a counter gear 32, an output gear 33, and a differential gear 34.

[0018] When the hybrid vehicle is running, the drive motor 13 generates power. The power generated by the drive motor 13 is transmitted to the differential gear 34 via the drive motor gear 26, counter gear 32, and output gear 33, and then transmitted from the differential gear 34 via the drive shaft 4 to the drive wheels 5 of the hybrid vehicle. This causes the drive wheels 5 to rotate.

[0019] When the total output required for the generator motor 12 and the drive motor 13 is smaller than the output of the battery 14, the hybrid vehicle runs in EV mode. That is, the engine 11 is stopped, no power is generated by the generator motor 12, and power is supplied from the battery 14 to the drive motor 13 via the PCU 15, which drives the drive motor 13 and causes the hybrid vehicle to run.

[0020] On the other hand, when the total output required for the generator motor 12 and the drive motor 13 exceeds the output of the battery 14, the hybrid vehicle runs in HV mode. That is, the engine 11 is driven and the generator motor 12 operates to generate electricity, thereby converting the power of the engine 11 into AC power in the generator motor 12. The AC power from the generator motor 12 is then supplied to the drive motor 13 via the PCU 15, thereby driving the drive motor 13.

[0021] The battery 14 is a battery pack made up of a combination of a plurality of secondary batteries. The secondary batteries are, for example, lithium ion batteries. The battery 14 outputs, for example, DC power of approximately 200 to 350V.

[0022] The AC power generated by the generator motor 12 is supplied to the drive motor 13 via the PCU 15 to power the hybrid vehicle, and is also converted to DC power and used to charge the battery 14. The PCU 15 is configured to include, for example, an inverter 41, an inverter 42, a boost converter 43, a system main relay circuit 44, a discharge resistor Rd, and a smoothing capacitor Cd.

[0023] As shown in Fig. 2, inverters 41 and 42 include three phases of series-connected upper-arm switches Q1, Q3, and Q5 and lower-arm switches Q2, Q4, and Q6. Each switch Q1 to Q6 is a voltage-controlled semiconductor switching element, such as an IGBT (Insulated Gate Bipolar Transistor) or a power MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). Freewheel diodes are connected in anti-parallel to the upper and lower-arm switches Q1 to Q6.

[0024] By controlling the switching of the arm switches Q1 to Q6 of the inverter 41, the AC power generated by the generator motor 12 is converted into DC power by the inverter 41 and supplied to the power line PL. Also, by controlling the switching of the arm switches Q1 to Q6 of the inverter 42, the DC power is converted into AC power and supplied to the drive motor 13, and the regenerative power from the drive motor 13 is converted into DC power and supplied to the power line PL.

[0025] As shown in FIG. 2, the boost converter 43 is configured by connecting an upper switching element TU and a lower switching element TL in series. Each switching element is a voltage-controlled semiconductor switching element, such as a power MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor). A reactor L1 is connected to the connection point between the upper switching element TU and the lower switching element TL, and a filter capacitor C1 is connected in parallel to the battery 14. By controlling the switching of the upper switching element TU and the lower switching element TL, the boost converter 43 boosts the voltage of the battery 14 and supplies it to the power line PL, and also reduces the DC voltage of the power line PL and supplies it to the battery 14. A discharge resistor Rd and a smoothing capacitor Cd are connected to the power line PL in parallel with the upper switching elements TU and TL.

[0026] The system main relay circuit 44 is, for example, composed of SMRB, SMRG, and SMRP. As described above, when a failure of the boost converter 43 is detected, SMRB is opened upon receiving a signal from the ECU 6, thereby isolating the battery 14 from the PCU 15 to protect it.

[0027] When the charging voltage (remaining capacity) of the battery 14 drops below a predetermined value, the generator motor 12 operates to generate electricity while the engine 11 is running, regardless of whether the drive motor 13 is running or stopped. At this time, AC power from the generator motor 12 is converted to DC power by the inverter 41, and the DC power output from the inverter 41 is stepped down by the boost converter 43. The stepped-down DC power is supplied to the battery 14, and the battery 14 is charged.

[0028] When the vehicle is decelerating, the drive motor 13 is operated in a regenerative manner, and the power transmitted from the drive wheels 5 to the drive motor 13 is converted into AC power. The PCU 15 converts the AC power supplied from the drive motor 13 to the inverter 42 into DC power, and the DC power output from the inverter 42 is stepped down by the boost converter 43. The stepped-down DC power is then supplied to the battery 14, thereby charging the battery 14.

[0029] The connection / disconnection of the system main relay circuit 44 is controlled in accordance with a control signal from the ECU 6. That is, the ECU 6 in this embodiment serves as a control unit that controls the connection / disconnection of the system main relay circuit 44.

[0030] The ECU 6 includes, by means of a built-in program, an engine control unit 61, a PCU control unit 62, a failure detection unit 63, a rotation speed determination unit 64, a battery charge amount determination unit 65, and a duration measurement unit 66. The engine control unit 61 controls the engine 11 in accordance with the detection results of various sensors (not shown). The PCU control unit 62 controls the PCU 15 in accordance with the detection results of various sensors (not shown).

[0031] The failure detection unit 63 detects a failure of the boost converter 43 based on the measurement results of a current sensor, a voltage sensor, etc. (not shown). The voltage Vvl on the input side (low voltage side) is compared with the voltage Vvh on the output side (high voltage side), and when the two are substantially the same (Vvl ≒ Vvh), it can be determined that a failure has occurred in the boost converter 43. The rotation speed determination unit 64 determines whether the rotation speed Ne of the drive wheels 5 is equal to or greater than a threshold value Nth according to the detection result of a rotation speed sensor (not shown).

[0032] A battery charge amount determination unit 65 determines the charging voltage Vbt of the battery 14 according to a detection signal from a voltage sensor (not shown), and determines whether the charging voltage Vbt is equal to or greater than a maximum value Vmax. A duration measurement unit 66 measures the elapsed time T from when the voltage of the power line PL became equal to or greater than a predetermined value.

[0033] As described above, the hybrid vehicle control system 1 of this embodiment has the system main relay circuit 44 to protect the battery 14 from overcharging, and is configured to shut off the system main relay circuit 44 when a failure or the like is detected in the boost converter 43. However, in this embodiment, the system main relay circuit 44 shuts off when the rotation speed determination unit 64 detects that the rotation speed Ne of the drive wheels 5 is equal to or greater than the threshold value Nth, and the charging voltage Vbt of the battery 14 is equal to or greater than the maximum value Vmax.

[0034] Here, a comparative example of this embodiment will be described. The hybrid vehicle control device of the comparative example has the same configuration as this embodiment except for the software built into the ECU 6. The operation of the hybrid vehicle control device of the comparative example (operation of fail-safe control) will be described with reference to the timing chart of FIG.

[0035] 7, voltage Vdd indicates a power supply voltage (e.g., 12 V) for operating the hybrid vehicle, and signal Sigbt is a start instruction signal that instructs ECU 6 to PCU 15 to start arm switches (IGBTs) in inverters 41 and 42. Signals SMRB and SMRG are switching instruction signals that instruct ECU 6 to PCU 15 to switch ON / OFF SMRB, SMRG, and SMRP of system main relay circuit 44.

[0036] The system voltage Vsys is a system voltage generated in an ECU (not shown) built into the PCU 15, and the signal Ssd is a signal that notifies the ECU 6 that the PCU 15 is ready for a shutdown operation.

[0037] The signal Sbc indicates whether an ECU (not shown) built into the PCU 15 is ready to control the inverters 41 and 42. When the signal Sbc is "ON," the inverters 41 and 42 and the boost converter 43 are ready to switch, and when the signal Sbc is "OFF," the switching operation is stopped. The signals Smg1, Smg2, and Sbr are signals that transmit from the PCU 15 to the ECU 6 whether the generator motor 12, the drive motor 13, and the boost converter 43 are in a normal state or an error state, respectively. The signal Sinv2 is a signal that indicates the state (normal control / shutdown) of the inverters 41 and 42.

[0038] In the hybrid vehicle control device of the comparative example, if a failure of the boost converter 43 is detected at time t1, for example, the signals SMRB and SMRG are immediately switched from "ON" to "OFF," and the SMRB and SMRG (or SMRP) of the system main relay circuit 44 are switched to open. This disconnects the battery 14 from the PCU 15, and the system voltage Vsys also gradually decreases from the boost target voltage. In addition, the signals Smg1, Smg2, Sbr, and Sinv2 are also switched from "0" (normal) to "1" (disconnected / unrecoverable). Thereafter, the power switch is switched OFF at time t2, which switches the power supply voltage Vdd to 0 V and the signal Sigbt to OFF, completing the fail-safe operation.

[0039] However, if system main relay circuit 44 is immediately shut off after a failure in boost converter 43 is detected, as in the comparative example, there is a problem that this may cause overvoltage breakdown of components connected to power line PL. This point will be described with reference to Figs. 8 to 10.

[0040] FIG. 8 is a graph showing an example of the change in the voltage across the filter capacitor C1 after the system main relay circuit 44 is shut off. When a fault (e.g., a fault in the upper switching element TU) in the boost converter 43 is detected and the system main relay circuit 44 is immediately shut off, the voltage across the filter capacitor C1 rises due to regenerative energy, which is the difference between the power generated by the generator motor 12 and the power consumed by the drive motor 13. In addition, residual energy stored in the reactor L1, the generator motor 12, the drive motor 13, the smoothing capacitor Cd, and the like is released, further increasing the voltage across the filter capacitor C1. Furthermore, deceleration of the hybrid vehicle generates a back electromotive force in the drive motor 13, which is regenerated in the power line PL, further increasing the voltage across the filter capacitor C1. Thus, even after the system main relay circuit 44 is shut off, the voltage across the power line PL continues to rise due to various factors.

[0041] As shown in Fig. 9, the back electromotive force Vmg of the drive motor 13 is proportional to the vehicle speed Vc of the hybrid vehicle. When the vehicle speed Vc reaches Vc1, the back electromotive force Vmg reaches V1 (for example, 500 V). Fig. 10 is a graph showing the relationship between the back electromotive force Vmg of the drive motor 13 and the upper limit (withstand voltage) of the time that a voltage is continuously applied to components connected to the power line PL. As shown in Fig. 10, when the back electromotive force Vmg is less than V1, the components connected to the power line PL will not be destroyed even if the back electromotive force Vmg is continuously applied for a long period of time (region 1: continuous withstand voltage).

[0042] When the back electromotive force Vmg exceeds V1, components connected to the power line PL may be destroyed even if the back electromotive force Vmg is continuously applied for a short period of time (e.g., several tens of seconds) (region 2: short-term withstand voltage). As the back electromotive force Vmg increases, the withstand voltage decreases. For example, as shown at point A in Figure 10, when the back electromotive force Vmg reaches V2 (e.g., 600 V) and the continuous voltage application time reaches approximately 120 seconds, the components connected to the power line PL may be destroyed by overvoltage or may catch fire.

[0043] In order to solve the problems of the comparative example, the hybrid vehicle control system 1 of this embodiment executes the operations described below. Fig. 3 is a timing chart showing the operations of the hybrid vehicle control system 1 of this embodiment, and Fig. 4 is a flowchart.

[0044] Even if the failure detection unit 63 detects a failure of, for example, the boost converter 43 at time t1 (Yes in step S10 of FIG. 4), it does not immediately shut off the system main relay circuit 44, but first notifies the driver of the vehicle via, for example, the display device 52 that a system abnormality (such as a failure of the boost converter 43) has occurred and that the driver should operate the vehicle brakes to decelerate the vehicle (step S11). The driver can actuate the brakes to decelerate the vehicle in response to this notification, which can contribute to a reduction in the back electromotive force of the drive motor 13. Note that instead of or in addition to the abnormality notification via the display device 52, automatic brake control or the like can also be executed.

[0045] Then, the ECU 6 determines whether the rotation speed Ne determined by the rotation speed determination unit 64 is equal to or greater than a predetermined value Nth (step S12), and further determines whether the charging voltage Vbt determined by the battery charge amount determination unit 65 is equal to or greater than a maximum value Vmax (step S13).

[0046] If the determination in step S13 becomes positive, for example, at time t4, the ECU 6 generates a control signal to open the system main relay circuit 44, thereby opening the system main relay circuit 44 (step S14). On the other hand, if the determination in step S13 is negative, the system main relay circuit 44 is maintained ON (connected state) until the determination in step S13 becomes positive (step S15). As a result, regenerative energy from the drive motor 13, residual energy, back electromotive force of the drive motor 13, etc. continue to be charged into the battery 14 even after a failure of the boost converter 43, thereby suppressing an increase in the voltage of the power line PL. Note that even if the charging voltage Vbt does not reach the maximum value Vmax, the system main relay circuit 44 may be switched to open if the elapsed time since the voltage of the power line PL became equal to or higher than a predetermined value exceeds a predetermined value.

[0047] As described above, according to the hybrid vehicle control system 1 of the first embodiment, even after a failure of the boost converter 43 is detected, the system main relay circuit 44 remains connected without being interrupted until the battery 14 is charged to a predetermined level. This suppresses a voltage rise in the power line PL and suppresses overvoltage breakdown of components connected to the power line PL. Therefore, according to the first embodiment, overvoltage breakdown of components can be effectively avoided. This allows low-voltage components to be used as components connected to the power line PL, enabling the size and cost of the control device to be reduced. Conversely, it allows a motor that generates a high back electromotive force to be used as the drive motor 13, which is expected to improve vehicle performance.

[0048] [Second embodiment] Next, a hybrid vehicle control system 1 according to a second embodiment will be described with reference to FIGS.

[0049] The overall configuration of the hybrid vehicle control system 1 of the second embodiment is substantially the same as that of the first embodiment (FIGS. 1 and 2), so a duplicated description will be omitted. The operation of the hybrid vehicle control system 1 of the second embodiment will be described with reference to the flowchart of FIG. 5. Steps S10 to S15 are the same as those of the first embodiment, so a duplicated description will be omitted.

[0050] After the system main relay circuit 44 is opened in step S14, the ECU 6 determines whether the voltage Vvl on the input side (low-voltage side) of the boost converter 43 has reached a predetermined value V1 or more (step S16). If the determination in step S16 is affirmative, the duration measurement unit 66 measures (counts) the duration T after the voltage Vvl has exceeded the predetermined value V1, and determines whether the duration T has reached a threshold value Tth or more (step S17). The threshold value Tth can be set to a value corresponding to the short-term withstand voltage described with reference to FIG. 10.

[0051] If the determination in step S17 is affirmative (Yes in step S17), the ECU 6 starts three-phase short control for the inverters 41, 42 (step S18). As shown in FIG. 6, the three-phase short control alternately turns on the upper arm switches Q1, Q3, and Q5 and the lower arm switches Q2, Q4, and Q6 to allow a return current to flow through the inverters 41, 42. The return current suppresses a rise in the voltage of the power line PL. The rotation speed Ne of the drive motor 13 is monitored, and if it is less than a threshold value Nth, the three-phase short control can be terminated. Because the three-phase short control heats up the drive motor 13 and can cause an irreversible decrease in maximum output due to demagnetization, it is preferable to shorten the execution time of the three-phase short control. If the rotation speed Ne decreases due to the running resistance of the drive motor 13 or the driver's braking control, the execution time of the three-phase short control can be shortened accordingly.

[0052] Furthermore, by performing three-phase short control, negative torque is generated in the drive motor 13, which may cause the drive motor 13 to suddenly decelerate. To prevent this, three-phase short control can be performed intermittently using pulse width modulation (PWM). Whether or not to perform PWM can also be determined based on, for example, the distance between the hybrid vehicle and another vehicle traveling behind it. Furthermore, the decision to start three-phase short control can also be made based on the voltage value of the power line PL instead of the duration T.

[0053] [others] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0054] For example, although the above embodiment has been described as an example of a series hybrid vehicle control device, the present invention can also be applied to a parallel hybrid vehicle control device. Furthermore, the present invention is not limited to hybrid vehicle control devices, but can be applied to all vehicles equipped with a battery and a drive motor, such as plug-in hybrid vehicles (PHEVs) and electric vehicles (BEVs). [Explanation of symbols]

[0055] 1...Hybrid vehicle control system 4...Drive shaft 5...Drive wheels 11...Engine 12...Generating motor 13...Drive motor 14...Battery 16...Electric compressor 21...Engine gear 22...Crankshaft 23...Rotation axis 24...Generator motor gear 25...Rotation axis 26...Drive motor gear 31...Output shaft 32...Counter gear 33...Output gear 34...Differential gear 41, 42...Inverter 43...Boost converter 44...System main relay circuit 51...Microcomputer 52...Display device 61...Engine control unit 62...PCU control unit 63...Failure detection unit 64...Rotation speed determination unit 65...Battery charge amount determination unit 66...Duration measurement section C1: Filter capacitor Cd: Smoothing capacitor L1...Reactor Rd…discharge resistance TL: Lower switching element TU: Upper switching element Q1~Q6...Arm switches

Claims

1. An electric vehicle control device for controlling an electric vehicle including a boost converter that boosts a voltage of a battery and outputs the boosted voltage, an inverter that converts the boosted voltage into an AC voltage, a drive motor that is driven by the AC voltage applied thereto, and a relay circuit that switches between connection and disconnection between the boost converter and the battery, a failure detection unit that detects a failure of the boost converter; a rotation speed detection unit that detects the rotation speed of the drive motor; a control unit that, when a failure of the boost converter is detected by the failure detection unit and the rotation speed detection unit while the rotation speed of the drive motor is equal to or higher than a predetermined value, maintains a connected state of the relay circuit until a charging voltage of the battery reaches a threshold value, and switches the relay circuit to a disconnected state when it is determined that the charging voltage of the battery will exceed the threshold value; An electric vehicle control device comprising:

2. further comprising an elapsed time measurement unit that measures an elapsed time from when the voltage on the input side of the boost converter reaches a predetermined value after the relay circuit is switched to an interrupted state, The electric vehicle control device according to claim 1 , wherein the control unit executes three-phase short control on the inverter when the elapsed time is equal to or greater than a predetermined time.

3. The electric vehicle control device according to claim 1 , further comprising a notification unit that, when the failure detection unit detects a failure in the boost converter, notifies a driver of the electric vehicle of that fact.

4. The electric vehicle control device according to claim 2 , wherein the control unit intermittently executes the three-phase short control by pulse width modulation.

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