Control device for electric vehicle

Abstract

To determine sticking of a second relay.SOLUTION: In a case where the drive circuit and the first relay are controlled such that the voltage of the first capacitor changes in a state where the second relay is controlled to be turned off, when the voltage of the connection line on the voltage conversion device side with respect to the second relay changes following the voltage of the first capacitor, it is determined that the second relay is fixed. Thus, sticking of the second relay can be determined.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] A conventional control device for this type of electric vehicle is proposed for use in an electric vehicle, and includes a motor, a drive circuit (inverter), a power storage device (battery), a capacitor, a first relay (system main relay), a charging relay, and a vehicle connection unit (see, for example, Patent Document 1). The drive circuit drives the motor. The power storage device is connected to the drive circuit via a power line. The power storage device is connected to the drive circuit via a power line. The capacitor is attached to the power line. The first relay is attached to the power line. The charging relay is attached to a charging line that connects the drive circuit side of the power line with the first relay and the vehicle connection unit. The vehicle connection unit is connected to an external power supply side connection unit that is connected to an external power source. This device includes a DC / DC converter that exchanges power between the power line and the auxiliary battery by converting voltage. The DC / DC converter charges the capacitor with the first relay and the charging relay turned off, and determines whether the charging relay is stuck based on the voltage between the charging relay and the vehicle connection unit on the charging line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-89030 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, electric vehicles using control devices have been proposed that include a voltage conversion device having a second capacitor that converts the voltage of power from a charging line and supplies it to a connection line that is connected to the drive circuit side of the power line from the first relay, and a second relay attached to the connection line.In electric vehicles with such a configuration, determining whether the second relay is stuck is recognized as an important issue.

[0005] The main purpose of the control device for an electric vehicle disclosed herein is to determine whether the second relay is stuck. [Means for solving the problem]

[0006] The control device for an electric vehicle according to the present disclosure employs the following means to achieve the above-mentioned main object.

[0007] The control device for an electric vehicle according to the present disclosure includes: a first capacitor attached to the power line; a first relay attached to the power line on the side of the power storage device relative to the first capacitor; a voltage conversion device having a second capacitor that converts voltage and supplies power from a charging line to which external power is supplied, to a connection line connected to the drive circuit side of the power line relative to the first relay; and a second relay attached to the connection line, said control device being used in an electric vehicle and controlling the drive circuit, the voltage conversion device, and the first and second relays, When the drive circuit and the first relay are controlled so that the voltage of the first capacitor changes while the second relay is controlled to be turned off, if the voltage of the connection line on the voltage conversion device side of the second relay changes following the voltage of the first capacitor, it is determined that the second relay is stuck. The gist of this is as follows.

[0008] In the control device for an electric vehicle disclosed herein, when the drive circuit and the first relay are controlled so that the voltage of the first capacitor changes while the second relay is controlled to be turned off, if the voltage on the voltage conversion device side of the second relay in the connecting line changes in accordance with the voltage of the first capacitor, it is determined that the second relay is stuck.

[0009] In the control device for an electric vehicle according to the present disclosure, when the drive circuit is controlled so that the first capacitor discharges and the voltage of the first capacitor decreases while the first and second relays are controlled so that the first relay is turned off and the second relay is turned on, and the drive circuit is then controlled so that the first capacitor is charged and the voltage of the first capacitor increases while the first and second relays are controlled so that the first relay is turned on and the second relay is turned off, if the voltage of the connecting line on the voltage conversion device side of the second relay increases, it is determined that the second relay is stuck. In this way, the control device for an electric vehicle according to the present disclosure can determine that the second relay is stuck.

[0010] In addition, in the control device for an electric vehicle of the present disclosure, when the drive circuit is controlled so that the first capacitor discharges and the voltage of the first capacitor drops while the first and second relays are controlled to be turned off, if the voltage of the connection line on the voltage conversion device side of the second relay drops, it is determined that the second relay is stuck. This makes it possible to determine that the second relay is stuck.

[0011] Furthermore, in the control device for an electric vehicle disclosed herein, when controlling the drive circuit to change the voltage of the first capacitor, the drive circuit may be controlled so that a d-axis current flows through the motor. In this way, the control device for an electric vehicle disclosed herein can change the voltage of the first capacitor while suppressing torque output from the motor. This allows the control device for an electric vehicle disclosed herein to determine whether the second relay is stuck using a more appropriate method. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing an outline of the configuration of an electric vehicle 20 equipped with a control device according to an embodiment of the present disclosure. [Figure 2] 4 is a flowchart showing an example of a determination routine executed by the ECU 60. [Figure 3] 10 is a timing chart showing an example of the relationship between the state of each relay and voltages V1 and V2. [Figure 4] 10 is a flowchart showing an example of a determination routine executed by the ECU 60 according to another embodiment. [Figure 5] 5 is a timing chart showing an example of the relationship between the state of each relay and voltages V1 and V2 when the determination routine of FIG. 4 is being executed. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic diagram showing the configuration of an electric vehicle 20 equipped with a control device according to an embodiment of the present disclosure. As shown in the figure, the electric vehicle 20 of the embodiment includes a traction motor 22, an inverter (drive circuit) 24, a battery (power storage device) 30, a smoothing capacitor (first capacitor) 34, a system main relay (first relay) SMR, a booster (voltage conversion device) 40, a cutoff relay (second relay) 50, a charging relay 51, and an electronic control unit (control device, hereinafter referred to as "ECU") 60. The ECU 60 mainly serves as the control device for the electric vehicle of the embodiment.

[0014] The motor 22 is configured as a synchronous generator motor and includes a rotor with a permanent magnet embedded therein and a stator around which a three-phase coil is wound. The rotor of the motor 22 is connected to a drive shaft 26 which is connected to drive wheels 28a, 28b via a differential gear 27.

[0015] The inverter 24 is connected to the motor 22 and also to the power line 32. The inverter 24 is configured as a well-known inverter circuit having six transistors and six diodes. The inverter 24 is controlled by the ECU 60.

[0016] The battery 30 is configured as a battery having a plurality of lithium ion secondary cells, and is connected to a power line 32 .

[0017] A smoothing capacitor 34 is attached to the power line 32 .

[0018] The system main relay SMR is attached to the power line 32. The system main relay SMR has a positive-side relay SMRB provided on the positive bus bar of the power line 32, a negative-side relay SMRG provided on the negative bus bar of the power line 32, and a precharge circuit in which a precharge resistor R and a precharge relay SMRP are connected in series to bypass the negative-side relay SMRG. The system main relay SMR is controlled by the ECU 60.

[0019] The booster 40 includes a capacitor (second capacitor) 40c, and boosts the power supplied to the charging line 44 from the vehicle-side connection unit 52 and supplies the boosted power to the connection line 46. The vehicle-side connection unit 52 is configured to be connectable to an equipment-side connection unit 92 that is connected to an external power source 94 of charging equipment 90 installed at a home, a charging station, or the like. The connection line 46 is connected to the inverter 24 side of the system main relay SMR of the power line 32. The booster 40 is controlled by the ECU 60.

[0020] The cutoff relay 50 is attached to the connection line 46. The charging relay 51 is attached to the charging line 44. The cutoff relay 50 and the charging relay 51 are controlled by the ECU 60.

[0021] The ECU 60 includes a microcomputer having a CPU and other components. Signals from various sensors are input to the ECU 60 via an input port. Examples of signals input to the ECU 60 include the rotational position of the rotor of the motor 22 from a rotational position sensor (e.g., a resolver) that detects the rotational position of the rotor of the motor 22, a voltage V1 from a voltage sensor 30a that detects the voltage of the smoothing capacitor 34, a voltage V2 from a voltage sensor 46a that detects the voltage on the booster 40 side of the disconnection relay 50 of the connection line 46 (the voltage on the voltage converter side of the second relay of the connection line), a connection signal from a connection detection sensor 52a that detects the connection between the vehicle-side connection unit 52 and the equipment-side connection unit 92, and a start signal from a start switch 62. The ECU 60 also functions as a drive control device for the electric vehicle 20, and therefore also receives detection values ​​from sensors necessary for drive control of the electric vehicle 20 (e.g., an accelerator pedal position sensor that detects the amount of accelerator pedal depression and a vehicle speed sensor). ECU 60 outputs various control signals via the output port, such as control signals to multiple switching elements of inverter 24, a drive signal to system main relay SMR, a control signal to booster 40, a drive signal to cutoff relay 50, and a drive signal to charging relay 51. When vehicle-side connection unit 52 is connected to equipment-side connection unit 92 of charging equipment 90, a signal line of equipment-side connection unit 92 of charging equipment 90 is connected to a signal line of vehicle-side connection unit 52, enabling ECU 60 to exchange various signals with charging equipment 90.

[0022] In an electric vehicle 20 equipped with the control device of the embodiment configured as described above, when the start switch 62 is turned on by the user, the ECU 60 turns on the system main relay SMR to put the vehicle into a ready-on state (system-on state). In the connection process for turning on the system main relay SMR, the positive-side relay SMRB and the pre-charge relay SMRP are turned on to pre-charge (charge) the smoothing capacitor 34, and then the negative-side relay SMRG is turned on and the pre-charge relay SMRP is turned off. Note that the pre-charging (charging) of the smoothing capacitor 34 is performed by forming a closed circuit consisting of the positive electrode of the battery 30, the positive-side relay SMRB, the smoothing capacitor 34, the pre-charge relay SMRP, the pre-charge resistor R, and the negative electrode of the battery 30 when the positive-side relay SMRB and the pre-charge relay SMRP are turned on. Then, when the start switch 62 is turned off thereafter, the system main relay SMR is turned off (the positive-side relay SMRB, the negative-side relay SMRG, and the pre-charge relay SMRP are turned off) to put the vehicle into a ready-off state (system-off state).

[0023] When connection detection sensor 52a detects that vehicle-side connection unit 52 is connected to equipment-side connection unit 92 of charging equipment 90 while the vehicle is parked in the ready-off state, ECU 60 turns on positive relay SMRB and negative relay SMRG of system main relay SMR, cutoff relay 50, and charging relay 51. Then, ECU 60 controls booster 40 so that voltage V2 of connection line 46 becomes higher than the voltage of battery 30, and performs external charging, which is charging of battery 30 using DC power from charging equipment 90.

[0024] Next, the operation of the electric vehicle 20 equipped with the control device of this embodiment configured as described above will be described, particularly the operation performed when determining whether the cutoff relay 50 is stuck on when external charging is terminated. FIG. 2 is a flowchart showing an example of a determination routine executed by the ECU 60. This routine is executed when the charge storage rate of the battery 30 reaches a predetermined rate or more during external charging, causing the ECU 60 to send a charge stop signal to the charging equipment 90 and turn off the charging relay 51. While the determination routine of FIG. 2 is being executed, the charging relay 51 is turned off. Note that upon receiving the charge stop signal, the charging equipment 90 stops supplying power from the external power source 94 to the equipment-side connection unit 92. FIG. 3 is a timing chart showing an example of the relationship between the state of each relay and voltages V1 and V2.

[0025] When this routine is executed, the CPU (not shown) of the ECU 60 controls the cutoff relay 50, the positive-side relay SMRB, the negative-side relay SMRG, and the pre-charge relay SMRP so that both the positive and negative sides of the cutoff relay 50 are turned on, the positive-side relay SMRB is turned on, the negative-side relay SMRG is turned off, and the pre-charge relay SMRP is turned off (S100). Then, the ECU 60 executes P-axis current control, which controls the inverter 24 so that a d-axis current flows through the motor 22 (S110). This allows the smoothing capacitor 34 and the capacitor 40c of the booster 40 to discharge without outputting torque from the motor 22 (while suppressing the output of torque from the motor 22). The ECU 60 then inputs the voltage V2 from the voltage sensor 30a (S120). Furthermore, the ECU 60 sets the input voltage V2 to the pre-control voltage Vp2 (S130). In S110, the ECU 60 discharges the smoothing capacitor 34 and the capacitor 40c, so that the voltage V1 of the smoothing capacitor 34 and the voltage V2 on the booster 40 side of the connection line 46 relative to the cutoff relay 50 drop to a value of 0 (time t0), as shown in FIG. 3. Therefore, the pre-control voltage Vp2 is set to a value of 0.

[0026] Next, the ECU 60 controls the cutoff relay 50, the positive side relay SMRB, the negative side relay SMRG, and the pre-charge relay SMRP so that the positive side of the cutoff relay 50 is turned off, the negative side of the cutoff relay 50 is turned on, the positive side relay SMRB is turned on, the negative side relay SMRG is turned off, and the pre-charge relay SMRP is turned on (S140). Then, the ECU 60 inputs the voltage V2 from the voltage sensor 30a (S150). The ECU 60 determines whether the input voltage V2 has increased from the pre-control voltage Vp2 (S160). Since the ECU 60 turns on the positive side relay SMRB and the pre-charge relay SMRP in S140, power from the battery 30 is supplied to the smoothing capacitor 34 via the power line 32, and the smoothing capacitor 34 is pre-charged (charged). At this time, the voltage V1 of the smoothing capacitor 34 increases from a value of 0 (time t1), as shown in FIG. 3 . The ECU 60 controls the disconnection relay 50 so that its positive side is turned off and its negative side is turned on. Therefore, when the positive side of the disconnection relay 50 is normal, the connecting line 46 is interrupted and no current flows from the connecting line 46 to the booster 40. As a result, the capacitor 40c is not charged, and the voltage V2 on the booster 40 side of the connecting line 46 from the disconnection relay 50 remains constant at zero, as shown by the solid line in FIG. 3 . If an abnormality occurs in which the positive side of the disconnection relay 50 is fixed on, the positive side of the disconnection relay 50 remains on without being turned off, as shown by the dashed line in FIG. 3 . At this time, the negative side of the disconnection relay 50 is on, so the connecting line 46 is not interrupted and current flows from the connecting line 46 to the booster 40. The capacitor 40c is charged, and the voltage V2 rises in accordance with the voltage V1, as shown by the dashed line in FIG. 3 . By checking the voltage V2 in this way, it is possible to determine whether or not an abnormality has occurred in the positive electrode side of the cutoff relay 50 being fixed on. Therefore, S160 is a process for determining whether or not an abnormality has occurred in the positive electrode side of the cutoff relay 50 being fixed on.

[0027] When the voltage V2 has not risen from the pre-control voltage Vp2 in S160, the ECU 60 determines that the voltage V2 does not follow the voltage V1, and determines that the positive side of the cutoff relay 50 is normal (S170). When the voltage V2 has risen from the pre-control voltage Vp2 in S160, the ECU 60 determines that the voltage V2 follows the voltage V1, and determines that the positive side of the cutoff relay 50 is stuck on (S180). This makes it possible to determine whether the positive side of the cutoff relay 50 is stuck on. Furthermore, because the determination of whether the positive side of the cutoff relay 50 is stuck on is made without outputting torque from the motor 22 in S100 to S180, it is possible to determine whether the positive side of the cutoff relay 50 is stuck on using a more appropriate method.

[0028] Next, in a process similar to S100, the ECU 60 controls the cutoff relay 50, the positive-side relay SMRB, the negative-side relay SMRG, and the pre-charge relay SMRP so that both the positive and negative sides of the cutoff relay 50 are turned on, the positive-side relay SMRB is turned on, the negative-side relay SMRG is turned off, and the pre-charge relay SMRP is turned off (S190). Then, in a process similar to S110, the ECU 60 executes P-axis current control (S200). This discharges the smoothing capacitor 34 and the capacitor 40c of the booster 40 without outputting torque from the motor 22. Furthermore, in a process similar to S120, the ECU 60 inputs the voltage V2 (S210). Furthermore, in a process similar to S130, the ECU 60 sets the input voltage V2 to the pre-control voltage Vp2 (S220). In S200, the capacitor 40c of the booster 40 is discharged, so the pre-control voltage Vp2 is set to zero.

[0029] Next, the ECU 60 controls the cutoff relay 50, the positive side relay SMRB, the negative side relay SMRG, and the pre-charge relay SMRP so that the positive side of the cutoff relay 50 is turned on, the negative side of the cutoff relay 50 is turned off, the positive side relay SMRB is turned on, the negative side relay SMRG is turned off, and the pre-charge relay SMRP is turned on (S230). Then, the ECU 60 inputs the voltage V2 from the voltage sensor 30a (S240). The ECU 60 determines whether the input voltage V2 has risen from the pre-control voltage Vp2 (S250). Since the ECU 60 turns on the positive side relay SMRB and the pre-charge relay SMRP in S230, power from the battery 30 is supplied to the smoothing capacitor 34 via the power line 32, and the smoothing capacitor 34 is pre-charged (charged). At this time, the voltage V1 of the power line 32 rises from a value of 0 (time t3), as shown in FIG. 3 . The ECU 60 controls the disconnect relay 50 so that the positive side is on and the negative side is off. Therefore, when the negative side of the disconnect relay 50 is normal, the connecting line 46 is interrupted and no current flows from the connecting line 46 to the booster 40. Therefore, the capacitor 40c is not charged, and the voltage V2 remains constant at zero, as shown by the solid line in FIG. 3 . If an abnormality occurs in which the negative side of the disconnect relay 50 is fixed on, the negative side of the disconnect relay 50 remains on without being turned off, as shown by the dashed-dotted line in FIG. 3 . In this case, the connecting line 46 is not interrupted, and current flows from the connecting line 46 to the booster 40, charging the capacitor 40c. As shown by the dashed line in FIG. 3 , the voltage V2 rises in accordance with the voltage V1. By examining the voltage V2 in this manner, it is possible to determine whether an abnormality in which the negative side of the disconnect relay 50 is fixed on has occurred. Therefore, S250 is a process for determining whether or not an abnormality has occurred in which the positive electrode side of the cutoff relay 50 is fixed ON.

[0030] When the voltage V2 has not risen from the pre-control voltage Vp2 in S250, the ECU 60 determines that the voltage V2 does not follow the voltage V1, determines that the negative side of the cutoff relay 50 is normal (S260), and ends this routine. When the voltage V2 has risen from the pre-control voltage Vp2 in S250, the ECU 60 determines that the voltage V2 follows the voltage V1, determines that the negative side of the cutoff relay 50 is stuck on (S270), and ends this routine. This makes it possible to determine whether the negative side of the cutoff relay 50 is stuck on. Furthermore, because the determination of whether the negative side of the cutoff relay 50 is stuck on in S190 to S270 is made without outputting torque from the motor 22, it is possible to determine whether the negative side of the cutoff relay 50 is stuck on in a more appropriate manner.

[0031] According to the electric vehicle 20 equipped with the control device of the present embodiment described above, when the inverter 24 and the system main relay SMR are controlled so that the voltage V1 of the smoothing capacitor 34 changes while the cutoff relay 50 is controlled to be turned off, if the voltage V2 on the booster 40 side of the capacitor 40c of the connecting line 46 changes to follow the voltage V1, it is determined that the cutoff relay 50 is stuck, and it is possible to determine that the cutoff relay 50 is stuck.

[0032] Furthermore, in an electric vehicle 20 equipped with the control device of this embodiment, when the inverter 24 is controlled so that the smoothing capacitor 34 discharges and the voltage V1 of the smoothing capacitor 34 drops while the system main relay SMR and the cutoff relay 50 are controlled so that the system main relay SMR is turned off and the cutoff relay 50 is turned on, and then the inverter 24 is controlled so that the smoothing capacitor 34 is pre-charged (charged) and the voltage V1 of the smoothing capacitor 34 rises while the system main relay SMR and the cutoff relay 50 are controlled so that the system main relay SMR is turned off and the cutoff relay 50 is turned off, when the voltage V2 on the booster 40 side of the capacitor 40c of the connecting line 46 rises, it is determined that the cutoff relay 50 is stuck, and it is possible to determine that the cutoff relay 50 is stuck.

[0033] Furthermore, in the electric vehicle 20 equipped with the control device of this embodiment, when the inverter 24 is controlled so as to change the voltage V1 of the smoothing capacitor 34, the inverter 24 is controlled so as to cause a d-axis current to flow through the motor 22, thereby making it possible to determine whether the cut-off relay 50 is stuck in a more appropriate manner.

[0034] In the embodiment described above, the ECU 60 executes the determination routine illustrated in Fig. 2, but instead of the determination routine of Fig. 2, the ECU 60 may execute a determination routine of another embodiment illustrated in Fig. 4. Fig. 4 is a flowchart showing an example of a determination routine of another embodiment executed by the ECU 60. Fig. 5 is a timing chart showing an example of the relationship between the state of each relay and the voltages V1 and V2 when the determination routine of Fig. 4 is executed.

[0035] When the determination routine of FIG. 4 is executed, the ECU 60 inputs the voltage V2, as in S120 (S300). Next, the ECU 60 sets the pre-control voltage Vp2, as in S130 (S310). Immediately after starting this routine, both the smoothing capacitor 34 and the capacitor 40c are charged. Therefore, the pre-control voltage Vp2 is equal to the voltage of the battery 30. After setting the pre-control voltage Vp2, the ECU 60 controls the cutoff relay 50, the positive side relay SMRB, the negative side relay SMRG, and the pre-charge relay SMRP so that the positive side of the cutoff relay 50 is turned off, the negative side is turned on, the positive side relay SMRB is turned on, the negative side relay SMRG is turned off, and the pre-charge relay SMRP is turned off (S320). Furthermore, the ECU 60 executes the P-axis current control, as in S110 (S330). Then, the ECU 60 inputs the voltage V2 (S340), as in S120. When the ECU 60 inputs the voltage V2, it determines whether the input voltage V2 has dropped from the pre-control voltage Vp2 (S350). When S320 and S330 are executed, the smoothing capacitor 34 is discharged, and the voltage V1 drops (time t4). At this time, if the positive side of the cutoff relay 50 is normal, the connection line 46 is cut off, and no current flows from the connection line 46 to the booster 40. Therefore, the capacitor 40c is not discharged, and the voltage V2 is maintained at a voltage equal to the voltage of the battery 30, as shown by the solid line in FIG. 5. If an abnormality occurs in which the positive side of the cutoff relay 50 is fixed on, the positive side of the cutoff relay 50 remains on without being turned off, as shown by the dashed-dotted line in FIG. 5 (time t4). At this time, because the negative side of the cutoff relay 50 is on, the connecting line 46 is not cut off and current flows from the connecting line 46 to the booster 40, the capacitor 40c is discharged, and as shown by the dashed line in Figure 5, voltage V2 drops following voltage V1 (time t4). By checking voltage V2 in this way, it can be determined whether or not an abnormality has occurred in which the positive side of the cutoff relay 50 is fixed on. Therefore, S340 is a process for determining whether or not an abnormality has occurred in which the positive side of the cutoff relay 50 is fixed on.

[0036] When the voltage V2 has not dropped from the pre-control voltage Vp2 in S340, the ECU 60 determines that the voltage V2 is not following the voltage V1, and determines that the positive side of the cutoff relay 50 is normal (S350). When the voltage V2 has dropped from the pre-control voltage Vp2 in S340, the ECU 60 determines that the voltage V2 is following the voltage V1, and determines that the positive side of the cutoff relay 50 is stuck on (S360). This makes it possible to determine whether the positive side of the cutoff relay 50 is stuck on. Furthermore, in S300 to S360, it is determined whether the positive side of the cutoff relay 50 is stuck on without outputting torque from the motor 22, so it is possible to determine whether the positive side of the cutoff relay 50 is stuck on using a more appropriate method.

[0037] Next, the ECU 60 controls the cutoff relay 50, the positive side relay SMRB, the negative side relay SMRG, and the pre-charge relay SMRP so that both the positive and negative sides of the cutoff relay 50 are turned on, the positive side relay SMRB is turned on, the negative side relay SMRG is turned off, and the pre-charge relay SMRP is turned on (S370). Since the ECU 60 turns on the positive side relay SMRB and the pre-charge relay SMRP in S370, power from the battery 30 is supplied to the smoothing capacitor 34 via the power line 32, and the smoothing capacitor 34 is pre-charged (charged). At this time, the voltage V1 of the power line 32 rises from a value of 0 (time t5), as shown in FIG. 5. As shown by the solid line in FIG. 5, the voltage V2 is maintained at a voltage equal to the voltage of the battery 30 when the positive side of the cutoff relay 50 is normal. As shown by the dashed line in Figure 5, when the positive side of the cut-off relay 50 is fixed on, the connecting line 46 is not cut off, so current flows from the connecting line 46 to the booster 40, charging the capacitor 40c, and voltage V2 rises following voltage V1, as shown by the dashed line in Figure 5.

[0038] Next, the ECU 60 inputs the voltage V2, as in S120 (S380). Furthermore, the ECU 60 sets the pre-control voltage Vp2 to the input voltage V2 (S390). Therefore, the pre-control voltage Vp2 is equal to the voltage of the battery 30. After setting the pre-control voltage Vp2, the ECU 60 controls the cutoff relay 50, the positive side relay SMRB, the negative side relay SMRG, and the pre-charge relay SMRP so that the positive side of the cutoff relay 50 is turned on, the negative side is turned off, the positive side relay SMRB is turned on, the negative side relay SMRG is turned off, and the pre-charge relay SMRP is turned off (S400). Furthermore, the ECU 60 executes the P-axis current control, as in S110 (S410). Then, the ECU 60 inputs the voltage V2, as in S120 (S420). The ECU 60 determines whether the input voltage V2 has decreased from the pre-control voltage Vp2 (S430). When steps S400 and S410 are executed, the smoothing capacitor 34 is discharged. When the negative side of the cutoff relay 50 is normal, the connecting line 46 is interrupted, and no current flows from the connecting line 46 to the booster 40. Because the capacitor 40c is not discharged, the voltage V2 is maintained at the voltage of the battery 30, as shown by the solid line in FIG. 5 (time t6). When an abnormality occurs in which the negative side of the cutoff relay 50 is fixed on, the negative side of the cutoff relay 50 does not turn off but remains on. When the negative side of the cutoff relay 50 is turned on, the connecting line 46 is not interrupted, and current flows from the connecting line 46 to the booster 40, the capacitor 40c is discharged, and the voltage V2 drops following the voltage V1. By checking the voltage V2 in this way, it is possible to determine whether or not an abnormality in which the negative side of the cutoff relay 50 is fixed on has occurred. Therefore, S430 is a process for determining whether or not an abnormality has occurred in which the positive electrode side of the cutoff relay 50 is fixed ON.

[0039] If the voltage V2 has not dropped from the pre-control voltage Vp2 in S430, the ECU 60 determines that the voltage V2 is not following the voltage V1, determines that the negative side of the cutoff relay 50 is normal (S440), and ends this routine. If the voltage V2 has dropped from the pre-control voltage Vp2 in S430, the ECU 60 determines that the voltage V2 is following the voltage V1, determines that the negative side of the cutoff relay 50 is stuck on (S450), and ends this routine. This makes it possible to determine whether the negative side of the cutoff relay 50 is stuck on. Furthermore, since the ECU 60 determines whether the negative side of the cutoff relay 50 is stuck on without outputting torque from the motor 22 in S370 to S450, it is possible to determine whether the negative side of the cutoff relay 50 is stuck on using a more appropriate method.

[0040] In the above-described embodiment, the P-axis current control is executed in S110 and S200 to control the inverter 24 so as to change the voltage V1 of the smoothing capacitor 34. However, as a method of controlling the inverter 24 so as to change the voltage V1 of the smoothing capacitor 34, when a certain amount of torque output from the motor 22 is permitted, the inverter 24 may be controlled so as to drive the motor 22 with a certain amount of torque output.

[0041] In the above-described embodiment, in S140 and S230, the positive electrode side relay SMRB is turned on, the negative electrode side relay SMRG is turned off, and the precharge relay SMRP is turned on to precharge (charge) the smoothing capacitor 34. However, when the electric vehicle 20 does not include a precharge circuit, that is, when the electric vehicle 20 does not include the precharge relay SMRP, the negative electrode side relay SMRG may be turned on instead of the precharge relay SMRP.

[0042] In the embodiment described above, the electric vehicle 20 is equipped with the booster 40. However, instead of the booster 40, any device that has a capacitor and converts the voltage of power from the charging line 44 to which power is supplied from an external source and supplies the power to the connecting line 46, such as a device that can boost the voltage of power supplied to the charging line 44 and supply the power to the connecting line 46, and that can boost the voltage of power not supplied to the connecting line 46 and supply the power to the charging line 44, may be used.

[0043] In the above-described embodiment, the electric vehicle 20 is configured to have a motor 22 for driving, but instead, for example, it may be configured as a hybrid vehicle having a motor and an engine, or as a fuel cell vehicle having a motor and a fuel cell.

[0044] In the above-described embodiment, the battery 30 is used as the power storage device, but instead, a capacitor or the like may be used.

[0045] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be described below. In the embodiment, the motor 22 corresponds to the "motor," the inverter 24 corresponds to the "inverter," the battery 30 corresponds to the "power storage device," the smoothing capacitor 34 corresponds to the "first capacitor," the system main relay SMR corresponds to the "first relay," the booster 40 corresponds to the "voltage conversion device," the cutoff relay 50 corresponds to the "second relay," and the ECU 60 corresponds to the "control device."

[0046] The correspondence between the main elements of the embodiments and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the embodiments are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the embodiments are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0047] The above describes the forms for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0048] The present disclosure is applicable to industries such as the manufacturing industry of control devices for electric vehicles. [Explanation of symbols]

[0049] 20 electric vehicle, 22 motor, 24 inverter, 26 drive shaft, 27 differential gear, 28a drive wheel, 28b drive wheel, 30 battery, 30a voltage sensor, 32 power line, 34 smoothing capacitor, 40 booster, 40c capacitor, 44 charging line, 46 connection line, 46a voltage sensor, 50 cut-off relay, 51 charging relay, 52 vehicle side connection part, 52a connection detection sensor, 60 electronic control unit (ECU), 62 start switch, 90 charging equipment, 92 equipment side connection part, 94 external power supply, R pre-charge resistor, SMR system main relay, SMRB positive side relay, SMRG negative side relay, SMRP pre-charge relay.

Claims

1. a first capacitor attached to the power line; a first relay attached to the power line on the side of the power storage device relative to the first capacitor; a voltage conversion device having a second capacitor that converts voltage and supplies power from a charging line to which power is supplied from an external source to a connection line connected to the drive circuit side of the power line relative to the first relay; and a second relay attached to the connection line, the electric vehicle control device controlling the drive circuit, the voltage conversion device, and the first and second relays, When the drive circuit and the first relay are controlled so that the voltage of the first capacitor changes while the second relay is controlled to be turned off, if the voltage of the connection line on the voltage conversion device side of the second relay changes following the voltage of the first capacitor, it is determined that the second relay is stuck. Control device for electric vehicles.

2. 2. The control device for an electric vehicle according to claim 1, In the case where the drive circuit is controlled so that the first capacitor is discharged and the voltage of the first capacitor drops while the first and second relays are controlled so that the first relay is turned off and the second relay is turned on, and then the drive circuit is controlled so that the first capacitor is charged and the voltage of the first capacitor rises while the first and second relays are controlled so that the first relay is turned on and the second relay is turned off, when the voltage of the connection line on the voltage conversion device side of the second relay rises, it is determined that the second relay is stuck. Control device for electric vehicles.

3. 2. The control device for an electric vehicle according to claim 1, When the drive circuit is controlled so that the first capacitor is discharged and the voltage of the first capacitor drops while the first and second relays are controlled to be turned off, if the voltage of the connection line on the voltage conversion device side of the second relay drops, it is determined that the second relay is stuck. Control device for electric vehicles.

4. 3. The control device for an electric vehicle according to claim 1 or 2, When the drive circuit is controlled so that the voltage of the first capacitor changes, the drive circuit is controlled so that a d-axis current flows through the motor. Control device for electric vehicles.

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