Vehicle control device

Abstract

The present invention addresses the problem of appropriately controlling a driving motor when traveling over a bump. This vehicle control device comprises a driving motor that is linked to a vehicle wheel, and an accelerator operation unit that is operated by a driver. The vehicle control device comprises a processor and a memory that are communicatively connected to each other and has a control system that controls the driving motor. As control modes for controlling the driving motor, provided are a torque control mode in which the motor torque is subjected to feedback control, and a speed control mode in which the motor rotational speed is subjected to feedback control. The control system switches the control mode from the torque control mode to the speed control mode if an operation amount of the accelerator operation unit exceeds a switching threshold value, and rotation of the driving motor is stopped.

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device provided in a vehicle. [Background technology]

[0002] BACKGROUND ART Vehicles such as electric vehicles and hybrid vehicles are equipped with a traction motor connected to the wheels (see Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2015-211476 [Patent Document 2] Japanese Patent Application Publication No. 2013-193557 [Patent Document 3] Japanese Patent Application Publication No. 2016-144245 Summary of the Invention [Problem to be solved by the invention]

[0004] When a vehicle goes over a road bump from a stopped state or from a very slow traveling state, it is expected that the driver will gradually increase the motor torque of the traction motor by gently depressing the accelerator pedal. In this case, the rotation of the traction motor will be stopped until the motor torque has increased sufficiently to allow the wheels to go over the bump. However, stopping the rotation of the traction motor causes certain switching elements to continue to be energized. Furthermore, continuing to energize certain switching elements can cause excessive temperature increases in the switching elements, which has led to the target motor torque being limited to suppress the temperature increase. Thus, if the motor torque is limited before the wheels go over the bump to protect components such as the switching elements, it will be difficult for the traction motor to go over the bump even if it has sufficient performance. Therefore, an improvement in this regard is needed.

[0005] An object of the present invention is to appropriately control the traction motor when going over a step. [Means for solving the problem]

[0006] In one embodiment, a vehicle control device is provided in a vehicle, and includes a traction motor connected to wheels and an accelerator operation unit operated by a driver. The vehicle control device includes a control system including a processor and a memory communicably connected to each other and controlling the traction motor. Control modes for controlling the traction motor include a torque control mode in which motor torque is feedback-controlled, and It can be performed when driving over bumps. Feedback control of motor rotation speed No. 1 a speed control mode; a second speed control mode that can be executed when the wheels are spinning and that performs feedback control of the motor rotation speed; There is. The integral term of the feedback control in the first speed control mode is set to be larger than the integral term of the feedback control in the second speed control mode. When the control system detects a motor lock in which the rotation of the traction motor controlled to a powering state is stopped, the control system detects the operation amount of the accelerator operation unit as a reference operation amount, and calculates a switching threshold by adding a predetermined amount to the reference operation amount. When the accelerator operation unit is further operated while the motor lock continues and the operation amount of the accelerator operation unit exceeds the switching threshold, the control system changes the control mode from the torque control mode to the No. 1 Switch to speed control mode. In one embodiment, a vehicle control device is provided in a vehicle, the vehicle control device including a traction motor coupled to wheels, an accelerator operation unit operated by a driver, and a brake device that brakes the wheels. The vehicle control device includes a processor and a memory communicably connected to each other, and a control system that controls the traction motor and the brake device. Control modes for controlling the traction motor include a torque control mode that performs feedback control of motor torque and a speed control mode that performs feedback control of motor rotation speed. When the control system detects a motor lock in which rotation of the traction motor controlled to a powering state has stopped, it detects the operation amount of the accelerator operation unit as a reference operation amount and adds a predetermined amount to the reference operation amount to calculate a switching threshold. When the accelerator operation unit is further operated while the motor lock continues and the operation amount of the accelerator operation unit exceeds the switching threshold, the control system switches the control mode from the torque control mode to the speed control mode. The control system switches the control mode from the speed control mode to the torque control mode when the rotation angle of the traction motor exceeds an angle threshold after switching the control mode from the torque control mode to the speed control mode.The control system operates the brake device to brake the wheels when the rotation angle of the traction motor is equal to or less than the angle threshold and a target motor torque is limited after switching the control mode from the torque control mode to the speed control mode. [Effects of the Invention]

[0007] According to one aspect of the present invention, the control system switches the control mode from the torque control mode to the speed control mode when the operation amount of the accelerator operation unit exceeds the switching threshold and the rotation of the traction motor is stopped, thereby making it possible to appropriately control the traction motor when going over a bump. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an example of a vehicle equipped with a vehicle control device according to an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram illustrating an example of a vehicle control device. [Figure 3] FIG. 2 is a diagram illustrating an example of the basic structure of each control unit. [Figure 4] FIG. 4 is a diagram showing an example of a driving force map. [Figure 5] FIG. 10 is a diagram showing a situation in which a vehicle approaches a step. [Figure 6] 10 is a flowchart showing an example of a procedure for executing step travel control. [Figure 7] 10 is a flowchart showing an example of a procedure for executing step travel control. [Figure 8] 10 is a flowchart showing an example of a procedure for executing step travel control. [Figure 9] 10 is a timing chart showing an example of an execution state of the step travel control. [Figure 10] 10A and 10B are diagrams illustrating an example of a vehicle traveling situation in bump traveling control. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. In the following description, identical or substantially identical configurations and elements are designated by the same reference numerals and will not be described again.

[0010] [Vehicle configuration] FIG. 1 is a diagram showing an example of a vehicle 11 equipped with a vehicle control device 10 according to one embodiment of the present invention. FIG. 2 is a diagram showing an example of the vehicle control device 10. As shown in FIG. 1, the vehicle 11 is provided with an electric axle 13 that drives rear wheels (wheels) 12. A traction motor 14 and a differential mechanism 15 are incorporated in the electric axle 13. As shown in FIG. 2, the differential mechanism 15 is connected to a rotor 14r of the traction motor 14 via a gear train 16. The rear wheels 12 are connected to axles 17 extending from the differential mechanism 15. In this way, the rear wheels 12 and the traction motor 14 are connected to each other via a power transmission path 18 that includes the gear train 16, the differential mechanism 15, the axles 17, and the like. The power transmission path 18 that connects the rear wheels 12 and the traction motor 14 does not include a slip element such as a torque converter or a clutch that allows relative rotation between the rear wheels 12 and the traction motor 14.

[0011] The traction motor 14, which is an electric motor, is a synchronous motor in which the rotor 14r follows the rotating magnetic field of the stator 14s, i.e., the rotor 14r rotates at a synchronous speed. An inverter 20 is connected to the stator 14s of the traction motor 14, and the inverter 20 is connected to a battery pack 21. The battery pack 21 is provided with a battery module 22 consisting of multiple battery cells, and a battery control unit 23 that monitors the charging and discharging of the battery module 22. The inverter 20 is also provided with multiple switching elements S1 to S6, and is connected to a motor control unit 24 that outputs control signals to these switching elements S1 to S6. The motor control unit 24 generates a rotating magnetic field in the stator 14s and controls the motor torque and rotational speed of the traction motor 14 by turning the switching elements S1 to S6 on and off using PWM control or the like.

[0012] A rotation sensor 25, such as a resolver, that detects the rotation angle of the rotor 14r is connected to the motor control unit 24. Temperature sensors 30, 31, and 32 that detect the temperatures of a U-phase coil 27, a V-phase coil 28, and a W-phase coil 29 that constitute a stator coil 26 are also connected to the motor control unit 24. Temperature sensors 33, 34, 35, 36, 37, and 38 that detect the temperatures of the switching elements S1 to S6 are also connected to the motor control unit 24. The motor control unit 24 can calculate the rotation speed of the rotor 14r using the detection signal of the rotation sensor 25.

[0013] The vehicle 11 is provided with a brake device 41 that brakes the front wheels 40 and the rear wheels 12. The brake device 41 includes a master cylinder 43 that generates brake fluid pressure in response to a brake pedal 42, and calipers 45 that brake disc rotors 44 of the front wheels 40 and the rear wheels 12. A brake actuator 46 that controls the brake fluid pressure supplied to each caliper 45 is provided between the master cylinder 43 and the caliper 45. The caliper 45 that brakes the disc rotor 44 is provided with a brake motor 47 that drives a caliper piston (not shown). As a result, even when the brake pedal 42 is not depressed, the caliper piston can be pushed out using the brake motor 47, thereby operating the caliper 45 and braking the disc rotor 44. A brake control unit 48 that outputs control signals to the brake actuator 46 and the brake motor 47 is connected to the brake actuator 46 and the brake motor 47.

[0014] As shown in Fig. 1, an instrument panel 50 installed at the front of the vehicle interior is provided with a meter display 51 that displays various information to the driver. As shown in Fig. 2, a meter control unit 52 is connected to the meter display 51, and the display content of the meter display 51 is controlled by the meter control unit 52. Also, as shown in Fig. 1, an accelerator pedal (accelerator operation unit) 53 that is operated by the driver is provided below the instrument panel 50.

[0015] [Control System] 2, the vehicle 11 is provided with a control system 60 made up of a plurality of electronic control units for controlling the electric axle 13, the brake device 41, etc. The electronic control units that make up the control system 60 include the battery control unit 23, the motor control unit 24, the brake control unit 48, and the meter control unit 52. Another electronic control unit that makes up the control system 60 is a vehicle control unit 61 that outputs control signals to the control units 23, 24, 48, and 52. These control units 23, 24, 48, 52, and 61 are connected to each other so as to be able to communicate with each other via an in-vehicle network 62 such as a CAN.

[0016] The vehicle control unit 61 sets operation targets for the electric axle 13, the brake device 41, etc. based on input information from various control units and various sensors described below. The vehicle control unit 61 then generates control signals according to the operation targets for the electric axle 13, the brake device 41, etc., and outputs these control signals to the motor control unit 24, the brake control unit 48, etc. Sensors connected to the vehicle control unit 61 include a vehicle speed sensor 63 that detects the vehicle speed, which is the traveling speed of the vehicle 11, an accelerator sensor 64 that detects the amount of operation of the accelerator pedal 53, and a brake sensor 65 that detects the amount of operation of the brake pedal 42. A start switch 66 that is operated by the driver when starting up the control system 60 is also connected to the vehicle control unit 61.

[0017] Fig. 3 is a diagram showing an example of the basic structure of each of the control units 23, 24, 48, 52, and 61. As shown in Fig. 3, the control unit, which is an electronic control unit, has a microcontroller 72 incorporating a processor 70 and a main memory (memory) 71. A predetermined program is stored in the main memory 71, and the program is executed by the processor 70. The processor 70 and the main memory 71 are connected to each other so that they can communicate with each other. Note that multiple processors 70 may be incorporated into the microcontroller 72, and multiple main memories 71 may be incorporated into the microcontroller 72.

[0018] The control unit also includes an input circuit 73, a drive circuit 74, a communication circuit 75, an external memory 76, a power supply circuit 77, and the like. The input circuit 73 converts signals input from various sensors into signals that can be input to the microcontroller 72. The drive circuit 74 generates drive signals for various devices, such as the inverter 20 and the brake device 41, based on signals output from the microcontroller 72. The communication circuit 75 converts signals output from the microcontroller 72 into communication signals directed to other control units. The communication circuit 75 also converts communication signals received from other control units into signals that can be input to the microcontroller 72. The power supply circuit 77 supplies a stable power supply voltage to the microcontroller 72, the input circuit 73, the drive circuit 74, the communication circuit 75, the external memory 76, and the like. The external memory 76, which may be a non-volatile memory or the like, stores programs and various data.

[0019] [Required driving force] Fig. 4 is a diagram showing an example of a driving force map. As shown in Fig. 4, the driving force map has characteristic lines L1 to L4 that define the required driving force for each operation amount of accelerator pedal 53 (hereinafter referred to as accelerator opening). That is, when accelerator opening Acc is 0%, vehicle control unit 61 sets the required driving force for vehicle 11 along characteristic line L1, and when accelerator opening Acc is 25%, sets the required driving force for vehicle 11 along characteristic line L2. Furthermore, when accelerator opening Acc is 50%, vehicle control unit 61 sets the required driving force for vehicle 11 along characteristic line L3, and when accelerator opening Acc is 100%, sets the required driving force for vehicle 11 along characteristic line L4.

[0020] For example, when the accelerator pedal 53 is depressed so that the accelerator opening Acc becomes 50% while the vehicle speed is V1, the vehicle control unit 61 sets the required driving force to Fa. When the accelerator pedal 53 is released so that the accelerator opening Acc becomes 0% while the vehicle speed is V1, the vehicle control unit 61 sets the required driving force to Fb. Then, the vehicle control unit 61 sets the target motor torque of the traction motor 14 to the power running side or the regeneration side so that the set required driving force is obtained.

[0021] That is, when the required driving force is set to the acceleration side by depressing the accelerator pedal 53, the target motor torque of the traction motor 14 is set to the powering side, and the traction motor 14 is controlled to a powering state. On the other hand, when the required driving force is set to the deceleration side by releasing the accelerator pedal 53, the target motor torque of the traction motor 14 is set to the regeneration side, and the traction motor 14 is controlled to a regeneration state. Note that, for ease of explanation, four characteristic lines L1 to L4 are set in the driving force map shown in Figure 4, but the present invention is not limited to this, and it goes without saying that five or more characteristic lines may be set in the driving force map.

[0022] [Bump control] Next, the step travel control executed by the control system 60 will be described. Here, Fig. 5 is a diagram showing a situation in which the vehicle 11 approaches a step 100, and Figs. 6 to 8 are flowcharts showing an example of the procedure for executing step travel control. The flowcharts shown in Figs. 6 to 8 are connected to each other at the locations marked with the symbols A, B, and C. Furthermore, each step of the step travel control shown in Figs. 6 to 8 shows processing executed by the processor 70 that constitutes the control system 60. Furthermore, the step travel control shown in Figs. 6 to 8 is control that is executed by the control system 60 at predetermined intervals after the control system 60 is started up.

[0023] As shown in Fig. 5, a situation in which bump traveling control is executed is a situation in which the driver gently depresses accelerator pedal 53 in order to go over bump 100 in front of the vehicle from a stopped state or a state in which the vehicle is traveling at an extremely low speed. In other words, a situation in which bump traveling control is executed is a situation in which the driver gently depresses accelerator pedal 53, thereby gradually increasing the required driving force and target motor torque, as indicated by arrow X1 in Fig. 4. Also, as shown in Fig. 5, in order to rotate rear wheels 12 and go over bump 100, it is necessary to increase the motor torque of traction motor 14 to a predetermined value or more, but in order to avoid vehicle 11 jumping out due to a sudden increase in torque, it is common for the driver to gradually increase the depression of accelerator pedal 53.

[0024] In this way, when going over bump 100 while gradually depressing accelerator pedal 53, it is expected that rotation of traction motor 14, which is controlled to the powering state, will stop, and the target motor torque will be limited by component protection control intervention. In other words, rotation of traction motor 14 will stop until motor torque increases sufficiently and front wheels 40 go over bump 100, but the stopping of rotation of traction motor 14 is a factor in continuing to energize certain coils 27-29 and switching elements S1-S6. Furthermore, continuing to energize certain coils 27-29 and switching elements S1-S6 is a factor in causing an excessive temperature rise in coils 27-29 and switching elements S1-S6, which is a factor in limiting the target motor torque by component protection control intervention.

[0025] That is, when the temperature of each of the coils 27-29 exceeds a predetermined upper limit, or when the temperature of each of the switching elements S1-S6 exceeds a predetermined upper limit, the target motor torque is limited by component protection control in order to suppress the current flowing through the stator coil 26 and the inverter 20. When the target motor torque is limited by intervention of component protection control in this way, the motor torque required to overcome the bump 100 cannot be ensured, making it difficult to overcome the bump 100 even if the traction motor 14 has sufficient performance. Therefore, the control system 60 executes the following bump traveling control to rotate the traction motor 14 while avoiding intervention of the component protection control, thereby enabling the vehicle to overcome the bump 100.

[0026] <Step Driving Control: Flowchart> As shown in FIG. 6, in step S10, it is determined whether the accelerator pedal position Acc is greater than 0%, i.e., whether the accelerator pedal 53 is being operated. If it is determined in step S10 that the accelerator pedal 53 is being operated, the process proceeds to step S11, where the traction motor 14 is controlled in a torque control mode. One of the control modes for controlling the traction motor 14 is a torque control mode in which the motor torque of the traction motor 14 is controlled toward a target motor torque, i.e., a torque control mode in which the motor torque is feedback-controlled. In this torque control mode, for example, a driving force map shown in FIG. 4 is used to set a target motor torque based on the accelerator pedal position, and the motor torque of the traction motor 14 is controlled toward this target motor torque. Note that, in order to feedback-control the motor torque, the current flowing through the stator coil 26 is fed back to the control system 60, and the control system 60 controls the inverter 20 to converge this current to a current value corresponding to the target motor torque.

[0027] When the traction motor 14 is controlled in the torque control mode, the process proceeds to step S12, where it is determined whether or not a motor lock has occurred in the traction motor 14. This motor lock refers to a state in which the traction motor 14, which is controlled to a powering state, stops rotating, that is, a state in which the rotor 14r stops while current is being applied to the stator coil 26. As shown in FIG. 5, when the vehicle 11 goes over a bump 100, there is a risk that a motor lock will occur in the traction motor 14. Note that in step S12, it is determined that a motor lock has occurred, for example, if the accelerator opening Acc is greater than 0% and the rotor 14r stops rotating, and this state continues for a predetermined time. Alternatively, in step S12, it may be determined that a motor lock has occurred if the stator coil 26 is energized and the rotor 14r stops rotating, and this state continues for a predetermined time.

[0028] If a motor lock is detected in step S12, the process proceeds to step S13, where the accelerator opening Acc at the time the motor lock was detected is detected and set as a reference opening (reference operation amount) Ax1. That is, the reference opening Ax1 is the accelerator opening Acc at the time the motor lock was detected. Next, in step S14, a predetermined value (predetermined amount) α is added to the reference opening Ax1 to calculate a switching threshold Ax2 (Ax2 = Ax1 + α), and in the following step S15, it is determined whether the current accelerator opening Acc exceeds the switching threshold Ax2.

[0029] If it is determined in step S15 that the current accelerator pedal position Acc is equal to or smaller than the switching threshold value Ax2, that is, if the accelerator pedal 53 has not been depressed further beyond the predetermined value α since the motor lock detection time, the process proceeds to step S16. In step S16, it is determined whether the motor lock is continuing. If it is determined in step S16 that the motor lock is not continuing, the vehicle 11 is not in a situation where it will go over the step 100, and the routine is terminated while maintaining the torque control mode. On the other hand, if it is determined in step S16 that the motor lock is continuing, it is assumed that the vehicle 11 is in a situation where it will go over the step 100, and the process proceeds to step S15, where it is again determined whether the current accelerator pedal position Acc exceeds the switching threshold value Ax2.

[0030] If it is determined in step S15 that the current accelerator pedal position Acc exceeds the switching threshold value Ax2, that is, if the accelerator pedal 53 has been depressed further beyond the predetermined value α since the motor lock detection time, the driver is operating the accelerator to overcome the bump 100, and the process proceeds to step S17. As shown in FIG. 7, in step S17, the rotation angle of the traction motor 14, i.e., the rotation angle Rra of the rotor 14r (hereinafter referred to as the rotor rotation angle), is reset, and in the following step S18, the traction motor 14 is controlled in the speed control mode. That is, as shown in steps S15 and S17, when the accelerator pedal position Acc exceeds the switching threshold value Ax2, the control mode of the traction motor 14 is switched from the torque control mode to the speed control mode.

[0031] One of the control modes for controlling the traction motor 14 is a speed control mode in which the rotational speed of the rotor 14r is controlled toward a predetermined target rotational speed (e.g., 100 rpm), i.e., a speed control mode in which the rotational speed of the rotor 14r (motor rotational speed) is feedback-controlled. In this speed control mode, the rotational speed of the rotor 14r (hereinafter referred to as the rotor rotational speed) is fed back to the control system 60, and the control system 60 controls the inverter 20 so that this rotor rotational speed converges to the target rotational speed. Note that the target rotational speed used in the speed control mode may be a fixed value or may be a variable value that varies depending on the accelerator opening, etc.

[0032] As described above, if the accelerator pedal 53 is depressed further beyond the predetermined value α after the motor lock detection, the control mode of the traction motor 14 is switched from the torque control mode to the speed control mode in step S18. This controls the traction motor 14 toward the target rotation speed (e.g., 100 rpm). Therefore, even if the motor lock occurs and the accelerator opening Acc is maintained, the motor torque is increased according to the difference between the target rotation speed and the rotor rotation speed. This allows the motor torque to be increased without the driver having to further depress the accelerator pedal 53, enabling the traction motor 14 to rotate so as to overcome the bump 100. Furthermore, since the rotating magnetic field of the stator 14s can be rotated in conjunction with the rotation of the rotor 14r, the current is not continuously applied to certain switching elements S1 to S6, and the intervention of the component protection control described above can also be suppressed.

[0033] Next, in step S19, it is determined whether the rotor rotation angle Rra exceeds a predetermined angle threshold Rx1. If the rotor rotation angle Rra exceeds the angle threshold Rx1 in step S19, this indicates that the front wheels 40 have gone over the bump 100 due to the rotation of the traction motor 14. Therefore, the process proceeds to step S20, where the rotor rotation angle Rra is reset, and then to step S21, where the control mode of the traction motor 14 is switched from the speed control mode to the torque control mode. In this way, by switching the control mode of the traction motor 14 to the torque control mode, the traction motor 14 can be controlled in accordance with the accelerator opening Acc after the front wheels 40 have gone over the bump 100, allowing the vehicle 11 to travel without causing any discomfort to the driver.

[0034] On the other hand, if it is determined in step S19 that the rotor rotation angle Rra is equal to or less than the angle threshold Rx1, this indicates that the traction motor 14 is not rotating sufficiently, that is, the front wheels 40 have not yet overcome the step 100. For this reason, as shown in FIG. 8 , the process proceeds to step S22, where it is determined whether component protection control, which limits the target motor torque, is being executed. If it is determined in step S22 that component protection control is being executed, the process proceeds to step S23, in order to cancel the component protection control, where brake hold control is executed to push out the caliper pistons by the brake motor 47, and the motor torque of the traction motor 14 is controlled to 0 Nm.

[0035] In this way, by controlling the motor torque of the traction motor 14 to "0 Nm," power supply to the inverter 20 and the stator coil 26 is cut off, so that the temperatures of the inverter 20 and the stator coil 26 can be reduced and the component protection control can be released. Moreover, even when the motor torque of the traction motor 14 is controlled to "0 Nm," the vehicle can be prevented from moving by brake hold control. Then, when the motor torque is controlled to "0 Nm" in step S23, the process proceeds again to step S22, where it is determined whether component protection control is being executed.

[0036] If it is determined in step S22 that component protection control is not being executed, the process proceeds to step S24, where it is determined whether the motor torque of the traction motor 14 has reached a predetermined upper limit value Tmax. If it is determined in step S24 that the motor torque has reached the upper limit value Tmax, it is difficult for the traction motor 14 to traverse the step 100, and the process proceeds to step S25, where a message indicating that it is difficult to traverse the step 100 is displayed on the meter display 51 for the driver. Note that if it is determined in step S22 that component protection control is not being executed and if it is determined in step S24 that the motor torque has not reached the upper limit value Tmax, the process proceeds to step S18, where control of the traction motor 14 in the speed control mode continues, as shown in FIG. 7.

[0037] <Step Driving Control: Timing Chart> Next, the above-mentioned bump traveling control will be described with reference to a timing chart. Fig. 9 is a timing chart showing an example of an execution state of bump traveling control, and Fig. 10 is a diagram showing an example of a traveling state of the vehicle 11 during bump traveling control. Fig. 10 shows the vehicle 11 corresponding to times t1 to t3 in Fig. 9, as well as the vehicle 11 corresponding to time t5 in Fig. 9. The distance Rx1' shown in Fig. 10 is the travel distance of the rear wheels 12 when the rotor rotation angle Rra reaches the angle threshold Rx1. The timing chart shown in Fig. 9 also shows a state in which the accelerator pedal 53 is gradually depressed from a stopped state approaching a bump 100, and thereafter the front wheels 40 of the vehicle 11 go over the bump 100.

[0038] 9, at time t1, the driver gradually depresses the accelerator pedal 53, and the accelerator opening degree Acc gradually increases (symbol a1). At this time, the traction motor 14 is controlled in the torque control mode (symbol b1), and therefore the motor torque Tm of the traction motor 14 increases in accordance with the accelerator opening degree Acc (symbol c1). Subsequently, at time t2, the traction motor 14 is controlled in a powering state (symbol c2), and the rotor rotation speed Nr remains at "0 rpm" (symbol d1) for a predetermined period of time, and therefore it is determined that a motor lock has occurred (symbol e1).

[0039] In this way, when a motor lock is detected (symbol e1), the accelerator pedal position Acc at the time of detection is detected as the reference position Ax1 (symbol a2), and a predetermined value α is added to the reference position Ax1 to calculate a switching threshold Ax2. Next, as shown at time t3, when the accelerator pedal position Acc exceeds the switching threshold Ax2 (symbol a3), the control mode of the travel motor 14 is switched from the torque control mode to the speed control mode (symbol b2). As a result, as shown at time t4, the motor torque is increased based on the difference ΔN between the target rotation speed Nr1 and the rotor rotation speed Nr (symbol c3). Furthermore, by increasing the motor torque (symbol c3), the rotor rotation speed Nr and the rotor rotation angle Rra gradually increase (symbols d2, f1).

[0040] Then, as shown at time t5, when the rotor rotation angle Rra exceeds a predetermined angle threshold Rx1 (symbol f2), the control mode of the traction motor 14 is switched from the speed control mode to the torque control mode (symbol b3). In other words, the situation in which the rotor rotation angle Rra exceeds the angle threshold Rx1 is when the front wheels 40 go over a step 100, as shown at time t5 in FIG. 10. In this way, after going over the step 100, the torque control mode is used to control the traction motor 14 with a target motor torque corresponding to the accelerator opening Acc. Note that if the rear wheels 12 stop at the step 100 and a motor lock of the traction motor 14 is detected again, the speed control mode is again used to control the traction motor 14. Furthermore, as shown in FIG. 9, when the rotor rotation angle Rra exceeds the angle threshold Rx1, the rotor rotation angle Rra is reset to "0°."

[0041] As described above, when the accelerator pedal position Acc exceeds the switching threshold Ax2 (symbol a3) while the traction motor 14 is in a motor lock state, the control mode of the traction motor 14 is switched from the torque control mode to the speed control mode (symbol b2). This allows the motor torque to be increased based on the difference ΔN between the target rotation speed Nr1 and the rotor rotation speed Nr (symbol c3), and the traction motor 14 can be rotated to go over the bump 100. In other words, since the power transmission path 18 connecting the rear wheels 12 and the traction motor 14 is not provided with a slip element such as a torque converter, there is a risk of motor lock occurring when going over the bump 100. However, even in this case, the traction motor 14 can be rotated appropriately. Furthermore, in the speed control mode of this embodiment, the integral term in the proportional-integral control is set to be large, for example, in order to quickly increase the motor torque in accordance with the difference ΔN between the target rotation speed Nr1 and the rotor rotation speed Nr. That is, the speed control mode, which is one of the control modes, is implemented not only in the bump control but also in the slip control when the wheels spin. (Second speed control mode) The speed control mode in the step running control is (First speed control mode)is set so that the integral term of

[0042] The present invention is not limited to the above-described embodiment and may be modified in various ways without departing from the spirit and scope of the present invention. In the above description, the control system 60 is configured using multiple control units 23, 24, 48, 52, and 61. However, this is not limiting. For example, the control system 60 may be configured using a single control unit. The vehicle 11 is not limited to the electric vehicle shown in the figure, but may also be a fuel cell vehicle or a series hybrid vehicle. In the above description, the rear wheels 12 are driven by the electric axle 13. However, this is not limiting. The front wheels 40 may be driven by an electric axle, or both the front wheels 40 and the rear wheels 12 may be driven by two electric axles. Furthermore, a traction motor may be provided for each rear wheel 12, a traction motor may be provided for each front wheel 40, or a traction motor may be provided for each front wheel 40 and each rear wheel 12. In the above description, the accelerator pedal 53 is used as the accelerator operation unit, but the present invention is not limited to this and may be a lever-type accelerator operation unit that is manually operated by the driver. [Explanation of symbols]

[0043] 10 Vehicle control device 11 vehicles 12 Rear wheel (wheel) 14. Traction motor (synchronous motor) 14r rotor 18 Power transmission path 53 Accelerator pedal (accelerator operation part) 60 Control System 70 processors 71 Main memory (memory) Tm Motor torque Nr rotation speed (motor rotation speed) Acc Accelerator opening (amount of operation) Ax1 standard opening (standard operation amount) Ax2 switching threshold α Predetermined value (predetermined amount) Rra rotation angle Rx1 angle threshold

Claims

1. A vehicle control device provided in a vehicle, a traction motor connected to the wheels; an accelerator operation unit operated by a driver; a control system including a processor and a memory communicatively connected to each other, the control system controlling the traction motor; and Control modes for controlling the travel motor include a torque control mode that performs feedback control of motor torque, a first speed control mode that can be executed when traveling over bumps and that performs feedback control of motor rotation speed, and a second speed control mode that can be executed when wheels are spinning and that performs feedback control of motor rotation speed, an integral term of the feedback control in the first speed control mode is set to be larger than an integral term of the feedback control in the second speed control mode, The control system includes: When a motor lock state in which the rotation of the traveling motor controlled to a powering state has stopped is detected, an operation amount of the accelerator operation unit is detected as a reference operation amount, and a switching threshold is calculated by adding a predetermined amount to the reference operation amount; and switching the control mode from the torque control mode to the first speed control mode when the accelerator operation unit is further operated while the motor lock is continued and the operation amount of the accelerator operation unit exceeds the switching threshold. Vehicle control device.

2. A vehicle control device provided in a vehicle, a traction motor connected to the wheels; an accelerator operation unit operated by a driver; A braking device for braking the wheels; a control system including a processor and a memory communicatively connected to each other, the control system controlling the traction motor and the brake device; and The control modes for controlling the traction motor include a torque control mode for feedback-controlling motor torque and a speed control mode for feedback-controlling motor rotation speed, The control system includes: When a motor lock state in which the rotation of the traveling motor controlled to a powering state has stopped is detected, an operation amount of the accelerator operation unit is detected as a reference operation amount, and a switching threshold is calculated by adding a predetermined amount to the reference operation amount; switching the control mode from the torque control mode to the speed control mode when the accelerator operation unit is further operated while the motor lock is continued and the operation amount of the accelerator operation unit exceeds the switching threshold; The control system includes: switching the control mode from the speed control mode to the torque control mode when the rotation angle of the traveling motor exceeds an angle threshold value after switching the control mode from the torque control mode to the speed control mode; after switching the control mode from the torque control mode to the speed control mode, when the rotation angle of the traction motor is equal to or less than the angle threshold value and the target motor torque is limited, actuating the brake device to brake the wheels. Vehicle control device.

3. 3. The vehicle control device according to claim 1, a power transmission path connecting the wheels and the traction motor to each other is not provided with a sliding element that allows relative rotation between the wheels and the traction motor; Vehicle control device.

4. 3. The vehicle control device according to claim 1, The traction motor is a synchronous motor that rotates a rotor at a synchronous speed. Vehicle control device.

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