Electric vehicles

Abstract

To output torque required for running even when resuming running by two-phase driving from a vehicle stop state after retreat running.SOLUTION: An electric vehicle comprises: a three-phase electric motor; an inverter that has a plurality of switching elements and drives the three-phase electric motor; a control device that controls the three-phase electric motor; and a rotor angle sensor that detects a rotor angle of the three-phase electric motor and outputs the detected value to the control device. The control device, when detecting an abnormality in one phase of any of the plurality of switching elements during running, executes retreat-running control by which the electric vehicle is stopped so that the rotor angle of the three-phase electric motor during stop of the vehicle is equal to a target rotor angle at which torque of a predetermined value or more can be output when the electric motor is driven in remaining two-phases.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an electric vehicle. [Background technology]

[0002] Patent Document 1 discloses that in an electric vehicle that runs on power output from a three-phase motor, if one phase of an inverter element fails while the vehicle is running, the three-phase motor is driven by the remaining two phases to allow the vehicle to evacuate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO 13 / 008313 Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration described in Patent Document 1, when the vehicle is to be stopped for evacuation travel and then resume travel, the three-phase motor is driven by the remaining two phases. However, in the configuration described in Patent Document 1, the electric vehicle is stopped by inertia during evacuation travel, so the position at which the rotor angle of the three-phase motor stops is determined by inertia. Therefore, depending on the rotor angle of the three-phase motor when stopped, there is a risk that the torque required for travel cannot be output when travel is resumed from a stopped state by driving the two phases.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to provide an electric vehicle that can output the torque required for traveling, even when resuming traveling by two-phase drive from a stopped state after evacuation traveling. [Means for solving the problem]

[0006] The present invention provides an electric vehicle comprising a three-phase motor as a power source for traveling, an inverter having a plurality of switching elements and driving the three-phase motor, a control device for controlling the three-phase motor, and a rotor angle sensor for detecting a rotor angle of the three-phase motor and outputting the detected value to the control device, wherein when the control device detects an abnormality in one phase of the plurality of switching elements while traveling, the control device executes evacuation travel control to stop the electric vehicle so that the rotor angle of the three-phase motor when stopped becomes a target rotor angle that can output a torque of a predetermined value or more when driven by the remaining two phases.

[0007] With this configuration, when the vehicle resumes travelling after being stopped after an evacuation run, the three-phase motor can output the torque required for travelling even when driven by the remaining two phases, thereby preventing a shortage of driving force when travelling is resumed.

[0008] The escape travel control may also include coasting control for decelerating the electric vehicle by coasting by controlling on the switching elements of three phases of an upper arm of the inverter or controlling on the switching elements of three phases of a lower arm of the inverter, calculation control for calculating a difference between a current rotor angle and the target rotor angle while the coasting control is being executed, and torque control for controlling the torque of the three-phase motor based on the difference and stopping the rotor angle at the target rotor angle.

[0009] According to this configuration, by executing the evacuation driving control, the difference between the current rotor angle and the target rotor angle during coasting can be calculated, and the torque of the three-phase motor can be controlled in accordance with this difference so that the rotor angle stops at the target stop position.

[0010] In addition, in the coasting control, the control device may control to turn on the three-phase switching elements of the upper arm and the lower arm, whichever arm includes the switching element in which an abnormality has been detected.

[0011] According to this configuration, by controlling all phase elements on the arm side including the switching element in which an abnormality has been detected to be ON, it is possible to cause the electric vehicle to coast.

[0012] In addition, the control device may calculate a distance from a current rotor angle to the target rotor angle in the calculation control, and calculate a torque of the three-phase motor based on the distance to the target rotor angle in the torque control, and the distance to the target rotor angle may be a value obtained by adding a value obtained by multiplying an angle difference from the current rotor angle to the target rotor angle by a rotation speed of the three-phase motor and 360.

[0013] According to this configuration, during coasting, the torque of the three-phase motor can be controlled based on the distance from the current rotor angle to the target rotor angle so that the rotor angle stops at the target stop position.

[0014] The torque control may also include a correction control in which a torque calculated based on a distance to the target rotor angle is set as a command torque, and a difference between this command torque and an actual torque actually output from the three-phase motor is added to the command torque.

[0015] According to this configuration, during coasting, the command torque can be corrected based on the difference between the command torque and the actual torque actually output from the three-phase motor by driving using the remaining two phases.

[0016] Furthermore, the control device may change the distance to the target rotor angle when detecting depression of a brake pedal while the evacuation travel control is being executed.

[0017] According to this configuration, when a braking operation is detected during coasting, the electric vehicle is stopped earlier than the originally planned position, so that the distance to the target rotor angle can be changed.

[0018] In addition, a fuse may be provided in a path electrically connecting the three-phase motor and the inverter, and when the electric vehicle is stopped after executing the evacuation driving control, the control device may execute melting control to melt the fuse corresponding to the phase in which an abnormality has been detected.

[0019] According to this configuration, when the vehicle is stopped after the evacuation run, the fuse blowing control is executed to blow the fuse corresponding to the phase in which the abnormality was detected. This makes it possible to prevent current from flowing through the faulty phase when the vehicle resumes running thereafter, improving safety against current flow.

[0020] Furthermore, when the electric vehicle resumes traveling after the melting control is executed, the control device may execute a traveling control for driving the three-phase motor with the remaining two phases.

[0021] According to this configuration, even when the fuse corresponding to the phase in which an abnormality has been detected is blown, the three-phase motor can output torque by being driven by the remaining two phases. Effect of the Invention

[0022] In the present invention, when the vehicle resumes travelling from a stopped state after an evacuation run, the torque required for travelling can be output from the three-phase motor even if the remaining two phases are used for drive, so that a lack of driving force when travelling is resumed can be suppressed. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram showing a case where a failure occurs in a switching element of one phase of an inverter while an electric vehicle according to an embodiment is running. [Diagram 2] FIG. 2 is a diagram illustrating a drive system mounted on an electric vehicle. [Diagram 3] FIG. 3 is a flow chart showing a vehicle control flow. [Figure 4] FIG. 4 is a diagram for explaining a state during the evacuation travel control. [Diagram 5] FIG. 5 is a diagram for explaining the rotor angle. [Figure 6] FIG. 6 is a diagram for explaining a method of calculating the motor torque. [Figure 7] FIG. 7 is a diagram for explaining a state during fuse blowing control when the vehicle is stopped after an evacuation run. [Figure 8] FIG. 8 is a diagram for explaining a state when the vehicle resumes traveling after being stopped for evacuation traveling. [Figure 9] FIG. 9 is a flow chart showing a vehicle control flow in the first modified example. [Figure 10] FIG. 10 is a diagram for explaining a method of calculating the motor torque in the first modified example. [Figure 11] FIG. 11 is a flow chart showing a vehicle control flow in the second modified example. [Figure 12] FIG. 12 is a diagram for explaining a method of calculating the motor torque in the second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] An electric vehicle according to an embodiment of the present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the embodiment described below.

[0025] Fig. 1 is a diagram showing a case where a failure occurs in a switching element of one phase of an inverter while an electric vehicle of an embodiment is running. Fig. 2 is a diagram showing a drive system mounted on the electric vehicle.

[0026] As shown in Figures 1 and 2, vehicle 1 is an electric vehicle equipped with a motor 2 as a power source for traveling. This vehicle 1 is, for example, a front-wheel drive vehicle in which the front left wheel and the front right wheel are driven by power output from the motor 2. The motor 2 is connected to the left and right drive wheels so as to be capable of transmitting power via a power transmission device such as a transmission or a differential gear mechanism. The vehicle 1 is equipped with a drive system 10 for controlling the torque required for traveling.

[0027] As shown in FIG. 2, the drive system 10 includes a motor 2, an inverter 3, a battery 4, and a control unit 5.

[0028] In the drive system 10, DC power output from a battery 4 is converted into AC power by an inverter 3, and this AC power is supplied from the inverter 3 to the motor 2 to drive the motor 2. At that time, the drive of the motor 2 is controlled by a command signal output from a control unit 5 to the inverter 3. The control unit 5 controls the inverter 3 and the motor 2. The drive system 10 is provided with a smoothing capacitor C. The control device of the vehicle 1 is configured to include at least the control unit 5.

[0029] The motor 2 is electrically connected to the battery 4 via the inverter 3, and is driven by power supplied from the battery 4. The motor 2 and the inverter 3 are electrically connected via three-phase coils (U phase, V phase, W phase). The motor 2 is driven by current flowing through the coils of each phase, and torque is output from the motor 2. This motor 2 is a three-phase motor, and is also a motor-generator (MG) that can function as both an electric motor and a generator.

[0030] The inverter 3 is a power conversion device that drives the motor 2. The inverter 3 is configured with an inverter circuit equipped with six switching elements T1 to T6 so that three-phase current can flow through the coil of the motor 2. The inverter circuit is equipped with a switching element and a diode for each phase, and converts DC power into AC power by the switching operation of the switching elements. The switching operation is an operation in which the switching elements are switched between ON and OFF. Each of the switching elements T1 to T6 is configured with, for example, an insulated gate bipolar transistor. As shown in FIG. 2, the inverter 3 has upper and lower arms 11, 12, and 13 for each phase (U phase, V phase, and W phase), and each of the upper and lower arms 11, 12, and 13 is equipped with two switching elements and two diodes.

[0031] The U-phase upper and lower arms 11 include an upper arm 11a in which a switching element T1 and a diode D1 are connected in parallel, and a lower arm 11b in which a switching element T2 and a diode D2 are connected in parallel, and the upper arm 11a and the lower arm 11b are connected in series. The V-phase upper and lower arms 12 include an upper arm 12a in which a switching element T3 and a diode D3 are connected in parallel, and a lower arm 12b in which a switching element T4 and a diode D4 are connected in parallel, and the upper arm 12a and the lower arm 12b are connected in series. The W-phase upper and lower arms 13 include an upper arm 13a in which a switching element T5 and a diode D5 are connected in parallel, and a lower arm 13b in which a switching element T6 and a diode D6 are connected in parallel, and the upper arm 13a and the lower arm 13b are connected in series.

[0032] Furthermore, in the drive system 10, a fuse 6 is provided in a path that electrically connects the inverter 3 and the motor 2. The fuse 6 is disposed on a path corresponding to the coil of each phase, and melts when a current of a predetermined magnitude or more flows. The fuse 6 includes a first fuse 6a corresponding to the U phase, a second fuse 6b corresponding to the V phase, and a third fuse 6c corresponding to the W phase.

[0033] The first fuse 6a is disposed between the connection point of the U-phase upper arm 11a and the lower arm 11b and the U-phase coil of the motor 2. When the U-phase current exceeds a predetermined value, the first fuse 6a melts. The second fuse 6b is disposed between the connection point of the V-phase upper arm 12a and the lower arm 12b and the V-phase coil of the motor 2. When the V-phase current exceeds a predetermined value, the second fuse 6b melts. The third fuse 6c is disposed between the connection point of the W-phase upper arm 13a and the lower arm 13b and the W-phase coil of the motor 2. When the W-phase current exceeds a predetermined value, the third fuse 6c melts.

[0034] The control unit 5 is composed of an electronic control unit (ECU) that drives and controls the motor 2. The control unit 5 includes a microcomputer having a CPU, RAM, ROM, an input / output interface, and the like. Signals from various sensors are input to the control unit 5. The vehicle 1 is equipped with a rotor angle sensor 7 that detects the rotor angle of the motor 2. A signal is input from the rotor angle sensor 7 to the control unit 5. The control unit 5 performs calculation processing for motor control, such as calculating the rotation speed of the motor 2 (hereinafter referred to as the motor rotation speed) based on the input signal.

[0035] Then, as a result of the calculation, a command signal for controlling the inverter 3 is output from the control unit 5 to the inverter 3. The command signal to the inverter 3 includes a signal for switching a switching element to be controlled in switching operation among the multiple switching elements T1 to T6. In this way, the control unit 5 controls the inverter 3 to control the voltage and current applied to the motor 2.

[0036] As shown in FIG. 1, the control unit 5 executes evacuation travel control when a failure (for example, a short circuit failure) occurs in a switching element of one phase of the inverter 3 while the vehicle is traveling. The evacuation travel control is a control executed as a fail-safe against an element failure in the inverter 3, and is a control for safely stopping the traveling vehicle 1. For this reason, the vehicle 1 is provided with an element failure detector (ON failure detector) that detects an ON failure occurring in the switching elements T1 to T6 of the inverter 3. That is, the drive system 10 is provided with an element failure detector that detects an ON failure occurring in the switching elements T1 to T6 of the inverter 3. Then, when an abnormality occurs in the inverter 3, a detection signal is output from the element failure detector, and the signal is input to the control unit 5. In this way, the control unit 5 can determine whether an element failure has occurred in the inverter 3 based on the detection signal from the element failure detector. Here, an example of vehicle control executed by the control unit 5 is shown in FIG. 3.

[0037] 3 is a flow chart showing a vehicle control flow. The control shown in FIG. 3 is repeatedly executed by the control unit 5 while the vehicle 1 is traveling.

[0038] The control unit 5 determines whether or not an ON failure has occurred in a switching element of any one phase of the inverter 3 while the vehicle is running (step S101). In step S101, it is determined whether or not an ON failure has occurred in any one phase of the switching elements T1 to T6 of the inverter 3. In other words, it is determined whether or not an abnormality has occurred in any one of the six switching elements T1 to T6. The control unit 5 can determine the presence or absence of an ON failure in a switching element based on a detection signal from an element failure detector.

[0039] If none of the switching elements T1 to T6 of the inverter 3 has an ON fault during running (step S101: No), this control routine ends.

[0040] If an ON failure occurs in a switching element of any one phase of the inverter 3 while traveling (step S101: Yes), the control unit 5 controls the switching elements of all phases in the upper arm of the inverter 3 to be ON (step S102). In step S102, the control unit 5 starts evacuation traveling control.

[0041] In step S102, as shown in FIG. 4, the evacuation travel control is started, and the switching elements of all phases of the upper arm, whichever arm includes the faulty switching element, are controlled to be ON. In this case, the faulty switching element is identified before the switching elements of the upper arm are controlled to be ON in all phases in step S102. That is, when the control unit 5 detects an abnormality in the inverter 3, it determines whether the arm of the faulty switching element (hereinafter, sometimes referred to as the faulty arm) is the upper arm or the lower arm, and determines whether the phase of the faulty switching element (hereinafter, sometimes referred to as the faulty phase) is the U phase, the V phase, or the W phase. This determination process makes it possible to identify which element of the six switching elements T1 to T6 is the faulty element. This determination process (discrimination process) is performed, for example, in the determination process in step S101, after the affirmative determination in step S101, or in the process in step S102. Then, in step S102, the switching elements of all phases of the faulty arm are controlled to be ON. That is, in the failed arm, the elements are controlled to be ON in the phases other than the failed phase. In this manner, the control unit 5 starts the evacuation running control in step S102, and controls the switching elements of the upper arm to be ON in all phases, thereby decelerating the vehicle 1 by coasting. The evacuation running control includes control for decelerating the vehicle 1 by coasting (hereinafter referred to as coasting control). Therefore, in step S102, the coasting control is executed, and the vehicle 1 coasts.

[0042] In this control flow, an example will be described in which the faulty element is the switching element T1. In other words, when it is determined that an ON fault has occurred in a switching element of one phase of the inverter 3, the upper arm element of the U phase is identified as the faulty element. Therefore, the control unit 5 controls the switching elements of all phases to ON, targeting the upper arm including the faulty element.

[0043] Also, the control unit 5 calculates the distance to the target rotor angle during coasting (step S103). The target rotor angle is a target stop position of the rotor angle when the vehicle 1 stops. The control unit 5 executes the evacuation running control during running to safely stop the vehicle 1, and controls the motor torque so that the rotor angle at the time of stopping becomes the target rotor angle, taking into consideration that the vehicle 1 will start running again after stopping. That is, the control unit 5 executes, as the evacuation running control, a coasting control that turns on the elements of all phases of the upper arm, and a stop position control that controls the torque of the motor 2 to control the stop position of the rotor angle. That is, the evacuation running control includes a stop position control. Then, when the vehicle resumes running from a stopped state after the evacuation running, the motor 2 is driven by the remaining two phases that are not faulty. Therefore, when the motor 2 is driven by the remaining two phases, the target rotor angle is set so that the rotor angle is capable of outputting a torque of a predetermined value or more. In this case, the target rotor angle can be set according to the faulty phase. For example, when a U-phase switching element has an ON failure, the angle range of the target rotor angle that can be set is determined, so the control unit 5 can specify the failed phase and then set the target rotor angle within that range according to the failed phase. This target rotor angle can be set by selecting a predetermined value within a certain angle range, for example, within a range of about 20°. Furthermore, within the range of 0 to 360 for one rotor rotation, there are multiple candidate ranges that can be set for the target rotor angle. Then, in step S103, the stop position control is started, the current rotor angle is specified based on a signal from the rotor angle detection sensor, and the distance from the current rotor angle to the target rotor angle is calculated.

[0044] A method for calculating the distance to the target rotor angle will be described with reference to FIG. 5. In FIG. 5, the target rotor angle is described as the target value, and the current rotor angle is described as the current value. As shown in FIG. 5, the control unit 5 calculates the difference (angle difference) between the current rotor angle and the target rotor angle as an angle difference within the range of 0 to 360. Then, the control unit 5 calculates the distance to the target rotor angle based on this difference and the motor rotation speed. Specifically, it can be obtained by the formula "distance to the target rotor angle = (angle difference between the target value and the current value) + 360 × N". N is the motor rotation speed. In this way, the distance to the target rotor angle is a value obtained by adding the angle difference from the current rotor angle to the target rotor angle within the range of 0 to 360 to the product of the motor rotation speed and 360. In step S103, the distance to the target rotor angle at the start of the evacuation travel control is calculated. That is, in step S103, the stop position control for stopping the rotor angle at the target stop position is started, and the distance to the target rotor angle is calculated. The stop position control includes a calculation control for calculating a difference between a current rotor angle and a target rotor angle, and a calculation control for calculating a distance to the target rotor angle.

[0045] The control unit 5 also calculates the amount of movement of the rotor angle (step S104). In step S104, the amount of movement of the rotor angle after the start of the evacuation travel control is calculated. As shown in FIG. 6, the control unit 5 sets the distance to the target rotor angle at the start of the evacuation travel control (time t1), and calculates the amount of movement A of the rotor angle thereafter (time t2). At this time, the amount of movement of the rotor angle at time t1 is zero, and the distance to the target rotor angle calculated at time t1 is set as the target value. Then, the control unit 5 calculates the amount of movement A of the rotor angle at time t2, thereby being able to calculate the difference B between the distance to the target rotor angle (the target value calculated at time t1) and the amount of movement A (the value calculated at time t2). This difference B can be regarded as the distance to the target rotor angle at time t2. That is, the control unit 5 can obtain the distance to the target rotor angle at the present time by calculating the difference B according to the amount of movement A in step S104.

[0046] The control unit 5 also calculates the motor torque based on the distance to the target rotor angle (step S105). In step S105, the command torque of the motor 2 is calculated using the difference between the current rotor angle and the target rotor angle. As shown in FIG. 6, the control unit 5 calculates the motor torque by PI control based on the difference B calculated at time t2. That is, the control unit 5 can calculate the motor torque using the distance to the target rotor angle obtained in step S104. In this case, the control unit 5 generates a command torque of the motor 2 based on the distance to the target rotor angle, and executes torque control to control the output torque of the motor 2 to achieve this command torque. This torque control is a control for stopping the rotor angle at the target stop position. That is, the stop position control includes torque control for controlling the motor torque to stop the rotor angle at the target stop position. The control unit 5 executes torque control and outputs a switching signal according to the command torque to the inverter 3.

[0047] Then, the control unit 5 determines whether the vehicle 1 has stopped (step S106). In step S106, it is determined whether the vehicle 1 has stopped based on signals input from various sensors to the control unit 5. As shown in Fig. 6, the control unit 5 determines that the vehicle 1 has stopped at time t3. In addition, during steps S102 to S106, the control unit 5 continues to execute the evacuation travel control.

[0048] If the vehicle 1 is not stopped (step S106: No), this control routine returns to step S104. Thus, while the process of step S104 and the process of step S105 are repeatedly performed, the control unit 5 continues to execute the stop position control. That is, during steps S102 to S105, the inverter 3 remains in a state in which the elements of all phases of the upper arm are controlled to be ON, as shown in FIG.

[0049] When the vehicle 1 stops (step S106: Yes), the control unit 5 controls the upper arm element of the faulty phase to ON, and controls the lower arm elements of the other phases to ON (step S107). When the vehicle 1 stops, the control unit 5 ends the evacuation travel control. In other words, the coasting control and the stop position control end. Then, in step S107, the control unit 5 executes the fuse blowing control.

[0050] In step S107, fuse blowout control is started, and as shown in FIG. 7, the upper arm element of the faulty phase is controlled to be ON, and the lower arm elements of the remaining two normal phases are controlled to be ON. As a result, an overcurrent flows through the first fuse 6a corresponding to the faulty phase U-phase. In short, the faulty switching element T1 is controlled to be ON, and the remaining two phases control the switching elements T4 and T6 constituting the arm opposite to the faulty phase to be ON. As a result, an overcurrent can be caused to flow through the fuse 6 corresponding to the faulty phase. Moreover, the torque generated during fuse blowout control is a torque that periodically becomes positive and negative, as plotted by the white dots in FIG. 5.

[0051] The control unit 5 determines whether the fuse 6 of the faulty phase has been blown (step S108). In step S108, it is determined whether the fuse 6 corresponding to the faulty phase among the fuses 6a, 6b, and 6c provided in each phase has been blown. In this control flow, since the faulty phase is the U phase, it is determined whether the first fuse 6a corresponding to the U phase has been blown.

[0052] If the fuse 6 of the faulty phase is not blown (step S108: No), this control routine returns to step S107.

[0053] If the fuse 6 of the faulty phase is blown (step S108: Yes), the control unit 5 drives the motor 2 with the two phases other than the faulty phase (step S109). In step S109, when the vehicle 1 transitions from a stopped state to a running state, the control unit 5 executes running control to cause the motor 2 to output torque.

[0054] In step S109, travel control is started, and the motor 2 is driven by the remaining two phases with the fuse 6 corresponding to the faulty phase blown, as shown in Fig. 8. In the example shown in Fig. 8, since the U phase is the faulty phase, the motor 2 is driven by the remaining two phases, the V phase and the W phase, with the first fuse 6a blown. The torque generated by driving with these two phases is a positive torque, as plotted by black dots in Fig. 5. After the process of step S109 is performed, this control routine ends.

[0055] As described above, according to the embodiment, a target value of the rotor angle is set in consideration of the case where the vehicle 1 starts running again after stopping during evacuation running, and the motor torque is controlled so that the rotor angle can be stopped at the target value. As a result, if an abnormality occurs in the switching element of the inverter 3, the rotor angle can be stopped at the target stop position when the vehicle 1 starts running for evacuation. This makes it possible to output the torque required for running, even when running is resumed by two-phase drive from a stopped state after evacuation running.

[0056] In the above embodiment, the case where the upper arm element of the U phase has failed has been described, but the present invention is not limited to this. That is, the failed phase is not limited to the U phase, but may be the V phase or the W phase. Furthermore, the failed arm is not limited to the upper arm, but may be the lower arm. In short, the configuration in which the upper arm elements of the inverter 3 are controlled to be ON in all phases during coasting control (step S102) has been described, but the present invention is not limited to this. During coasting control, the control unit 5 may control the lower arm elements of the inverter 3 to be ON in all phases. For example, the control unit 5 controls the elements of all phases to be ON by controlling the arm including the switching element in which an abnormality is detected during traveling, out of the upper arm and the lower arm, as the control object. Therefore, when the switching element in which an abnormality is detected is the upper arm (when the failed arm is identified as the upper arm), the control unit 5 controls the upper arm elements to be ON in all phases. Alternatively, when the switching element in which an abnormality is detected is the lower arm (when the failed arm is identified as the lower arm), the control unit 5 controls the lower arm elements to be ON in all phases. In this way, in coasting control, the control unit 5 can control the switching elements of all phases of the upper arm to be ON, or control the switching elements of all phases of the lower arm to be ON.

[0057] Furthermore, the vehicle 1 is not limited to a front-wheel drive vehicle, and may be a rear-wheel drive vehicle. Furthermore, the vehicle 1 may be an electric vehicle that is capable of autonomous driving without operation by a driver.

[0058] Also, variations of the above-described embodiments can be constructed.

[0059] Now, vehicle 1 in the first modified example will be described with reference to Figures 9 and 10. In the first modified example, it is taken into consideration that, during evacuation travel, one switching element of inverter 3 fails, and therefore even if the motor torque is calculated, the torque cannot be output according to the command torque.

[0060] 9 is a flow chart showing a vehicle control flow in the first modified example. Note that steps S201 to S205 and S207 to S210 shown in FIG.

[0061] When the control unit 5 of the first modified example calculates the motor torque in step S205, it calculates the difference between the command torque and the actual torque of the motor 2, integrates this difference, and adds it to the command torque (step S206). In step S206, as the torque control, correction control is performed to correct the command torque based on the actual torque. In other words, the torque control includes correction control. As shown by the dashed dotted line in Fig. 10, the control unit 5 generates a corrected command torque by integrating and adding the difference between the command torque and the actual torque, and controls the output torque of the motor 2 based on this corrected command torque.

[0062] According to this first modified example, when coasting with one phase of a switching element failing, the difference between the actual torque and command torque of motor 2 is added to the command torque, and motor 2 is controlled by the corrected command torque, thereby stopping the rotor angle at the target stop position.

[0063] 11 and 12, a vehicle 1 in a second modified example will be described. The second modified example is a further modified example of the first modified example, and takes into consideration that, during evacuation travel, the distance to stop is shortened due to braking by the driver, and the vehicle stops before reaching the target rotor angle. Note that a description of the same configuration as the above-mentioned first modified example will be omitted.

[0064] 11 is a flow chart showing a vehicle control flow in the second modified example. Note that steps S301 to S306 and S309 to S312 shown in FIG. 11 are similar to steps S201 to S210 shown in FIG.

[0065] In the second modified example, when the control unit 5 adds the difference between the command torque and the actual torque to the command torque in step S306, it determines whether or not the brake pedal is depressed (step S307). In step S307, it is determined whether or not the driver is depressing the brake pedal based on a signal from the brake stroke sensor.

[0066] If the brake pedal is depressed (step S307: Yes), the control unit 5 changes the target rotor angle (step S308). In step S308, the distance to the target rotor angle is changed. When the control unit 5 detects a brake operation during the stop position control, the control unit 5 changes the distance to the target rotor angle so as to shorten it by one rotation of the motor 2, as shown in FIG. 12. That is, the distance to the target rotor angle is reduced by one rotation in accordance with the brake depression force.

[0067] If the brake pedal is not depressed (step S307: No), the control routine proceeds to step S308.

[0068] According to the second modified example, when the brake pedal is depressed during the stop position control, the rotor angle can be stopped at the target stop position by changing the distance to the target rotor angle. [Explanation of symbols]

[0069] 1 vehicle 2 Motors 3 Inverter 4 Battery 5. Control section 6. Fuse 7 Rotor Angle Sensor 10 Drive System 11a, 12a, 13a Upper arm 11b, 12b, 13b Lower arm T1~T6 Switching elements

Claims

[Claim 1] A three-phase motor that is the power source for running the vehicle; an inverter having a plurality of switching elements and driving the three-phase motor; A control device for controlling the three-phase motor; a rotor angle sensor that detects a rotor angle of the three-phase motor and outputs the detected value to the control device; An electric vehicle comprising: When an abnormality is detected in one phase of the plurality of switching elements while the vehicle is traveling, the control device executes an evacuation travel control for stopping the electric vehicle so that a rotor angle of the three-phase motor when the vehicle is stopped becomes a target rotor angle that can output a torque equal to or greater than a predetermined value when driven by the remaining two phases. An electric vehicle characterized by:

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