Vehicle control device, vehicle control method, and vehicle control program

Abstract

A vehicle control device (10) includes: an inverter control unit (32); and a control unit (32a) that, when a motor lock state is detected, executes control to suppress the torque of a rotary electric machine so as to reduce the temperature of a drive unit (152) including the rotary electric machine and an inverter. In the motor lock state, the control unit predicts, as a current concentrated phase, a phase in which the current is concentrated if the motor lock state is released when the current is in a single phase continuous energization state flowing continuously for a specific amount of time or greater to a specific phase among a plurality of phases of the rotary electric machine, and releases the motor lock state when it is determined that the predicted current concentrated phase is different from the specific phase.

Description

Vehicle control device, vehicle control method, and vehicle control program CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims the benefit of priority from patent application serial number 2024-084251, filed May 23, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a vehicle control device, a vehicle control method, and a vehicle control program.

[0003] A motor (hereinafter, a rotating electric machine), which is the power source of an electric vehicle (hereinafter, a vehicle), is driven by passing AC current through multiple phases. When the vehicle starts on a slope, if the rotating electric machine enters a locked state (hereinafter, a motor lock state) where it is barely rotating, the current flow phase does not change, and current concentrates in a specific phase among the U-phase, V-phase, and W-phase. If a current greater than or equal to a threshold value flows continuously through, for example, the U-phase for a specific period of time, there is a risk that an inverter element for controlling the current in the U-phase may overheat.

[0004] Patent Document 1 discloses a device that suppresses temperature rise in inverter elements when a motor lock state occurs. The device in Patent Document 1 limits the output torque when current concentrates in a specific phase. By limiting the output torque, a vehicle traveling on a slope will slide down, causing the rotation angle of the rotating electric machine (hereinafter referred to as the MG angle) to change. This allows current to flow to phases other than the specific phase where current is concentrated, suppressing current concentration in the specific phase. The device in Patent Document 1 releases the limit on the output torque when there is no longer any concern about current concentration in the specific phase.

[0005] JP 2012-170247 A

[0006] However, after detailed investigation by the inventors, the inventors discovered a problem with the device of Patent Document 1: the MG angle is changed when the vehicle rolls over during output torque limitation, resulting in a haphazard change in the MG angle. For example, even if the output torque is limited to prevent current concentration in the U-phase and the vehicle rolls over, the electrical angle remains the electrical angle for supplying current to the U-phase. Furthermore, even after the output torque limitation is lifted and the MG angle changes, the electrical angle may remain the electrical angle for supplying current to the U-phase. In this way, current does not flow in phases other than the U-phase, such as the V-phase and W-phase, and current is concentrated in the same U-phase again, potentially causing the inverter elements to overheat. Thus, the prior art leaves room for improvement in terms of preventing overheating of the drive units, including the inverter elements and rotating electric machine.

[0007] The present disclosure aims to provide a vehicle control device, a vehicle control method, and a vehicle control program that are capable of appropriately performing control to lower the temperature of a rotating electric machine or the like.

[0008] A vehicle control device according to a first aspect of the present disclosure includes an inverter control unit that controls an inverter that drives a rotating electric machine mounted on a vehicle for driving the vehicle, and a control unit that, when a motor lock state in which the rotating electric machine does not rotate when current is applied to the rotating electric machine is detected, executes control to suppress the torque of the rotating electric machine so as to lower the temperature of a drive unit including the rotating electric machine and the inverter. When, during the motor lock state, a single-phase continuous current state occurs in which current flows continuously through a specific phase among multiple phases of the rotating electric machine for a specific period of time or more, the control unit predicts that the phase in which current will be concentrated if the motor lock state is released is a current concentration phase, and releases the motor lock state when it is determined that the predicted current concentration phase is different from the specific phase.

[0009] A vehicle control program according to a second aspect of the present disclosure causes at least one processor to execute processing including: controlling an inverter that drives a rotating electric machine mounted on a vehicle for driving the vehicle; when a motor lock state is detected in which the rotating electric machine does not rotate when current is applied to the rotating electric machine, executing control to suppress the torque of the rotating electric machine so as to lower the temperature of a drive unit including the rotating electric machine and the inverter; when a single-phase continuous current state occurs in which current flows continuously in a specific phase of multiple phases of the rotating electric machine for a specific period of time or more during the motor lock state, predicting a phase in which current will be concentrated if the motor lock state is released as a current concentration phase; and when it is determined that the predicted current concentration phase is different from the specific phase, releasing the motor lock state.

[0010] A vehicle control method according to a third aspect of the present disclosure executes processing including the steps of: at least one processor controls an inverter that drives a rotating electric machine mounted on a vehicle for driving the vehicle; when a motor lock state is detected in which the rotating electric machine does not rotate when current is applied to the rotating electric machine, executing control to suppress the torque of the rotating electric machine so as to lower the temperature of a drive unit including the rotating electric machine and the inverter; when a single-phase continuous current state occurs in which current flows continuously in a specific phase of multiple phases of the rotating electric machine for a specific period of time or more during the motor lock state, predicting a phase in which current will be concentrated if the motor lock state is released as a current concentration phase; and when it is determined that the predicted current concentration phase is different from the specific phase, releasing the motor lock state.

[0011] According to the present disclosure, a vehicle control device, a vehicle control method, and a vehicle control program are provided that can prevent overheating of a drive unit.

[0012] FIG. 1 is a schematic diagram showing an example of the configuration of a vehicle 100. FIG. 2 is a block diagram showing an example of the hardware configuration of the vehicle control device 10. FIG. 3 is a block diagram showing an example of a sensor group 200. FIG. 4 is a block diagram showing an example of the functional configuration of a CPU 21A of the vehicle control device 10. FIG. 5 is a diagram showing an example of the configuration of a drive unit 152 including a rotating electric machine 150 and an inverter 151. FIG. 6 is a diagram for explaining the lock determination process. FIG. 7 is a diagram for explaining the motor lock execution condition. FIG. 8 is a flowchart for explaining the phase switching determination process. FIG. 9 is a diagram showing the relationship between the MG angle and phase current before and after adjustment. FIG. 10 is a diagram for explaining the calculation method of the MG angle fluctuation amount in step S74. FIG. 11 is a flowchart for explaining the process related to the output torque limit and the release of the output torque limit. FIG. 12 is a timing chart for explaining the operation of the vehicle control device. FIG. 13 is a timing chart for explaining the operation of the vehicle control device. FIG. 14 is a diagram showing the relationship between three phase currents and the temperatures of the inverter elements through which those phase currents flow. FIG. 15A is a diagram for explaining the operation of a vehicle control device according to a comparative example. FIG. 15B is a diagram for explaining the operation of a vehicle control device according to a comparative example. Fig. 15C is a diagram for explaining the operation of a vehicle control device according to a comparative example. Fig. 15D is a diagram for explaining the operation of a vehicle control device according to a comparative example. Fig. 15E is a diagram for explaining the operation of a vehicle control device according to a comparative example. Fig. 16 is a diagram for explaining the operation of a vehicle control device according to a comparative example. Fig. 17 is a diagram for explaining the operation of a vehicle control device according to a comparative example.

[0013] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0014] A vehicle control device 10 according to this embodiment is mounted on a vehicle 100 and configured as a device for controlling the vehicle 100. Prior to describing the vehicle control device 10, the configuration of the vehicle 100 will be described with reference to FIG.

[0015] 1 is a schematic diagram showing an example of the configuration of a vehicle 100. The vehicle 100 is a vehicle that travels based on the driving operation of a driver. However, in cases such as when a wheel comes into contact with a bump, part of the driving operation (e.g., braking) may be automatically performed by a vehicle control device 10. The vehicle 100 includes a vehicle body 101, wheels 111, 112, 121, 122, a rotating electric machine 150, and a battery 160.

[0016] The vehicle body 101 is the main body of the vehicle 100 and is referred to as the "body." The wheel 111 is a wheel provided on the front left part of the vehicle body 101, and the wheel 112 is a wheel provided on the front right part of the vehicle body 101. The wheels 111 and 112, which are front wheels, are provided as driven wheels in this embodiment.

[0017] The wheel 121 is a wheel provided on the rear left side of the vehicle body 101. The wheel 122 is a wheel provided on the rear right side of the vehicle body 101. The rear wheels 121 and 122 are provided as drive wheels in this embodiment. That is, the wheels 121 and 122 rotate by the driving force of the rotating electric machine 150 described below, causing the vehicle 100 to travel.

[0018] In this way, the vehicle 100 of this embodiment is configured as a so-called "rear-wheel drive" vehicle. Alternatively, the vehicle 100 may be configured as a front-wheel drive vehicle or a four-wheel drive vehicle. In the latter case, in addition to the rotating electric machine 150 for driving the rear wheels, a rotating electric machine 150 for driving the front wheels may be separately provided.

[0019] A brake device 131 is provided on the wheel 121, and a brake device 132 is provided on the wheel 122. Both brake devices 131 and 132 are braking devices that apply braking force to the wheels by hydraulic pressure. Such braking devices may be provided not only on the driving wheels but also on the wheels 111 and 112, which are driven wheels. The operation of the brake devices 131 and 132 is controlled by a brake ECU (Electronic Control Unit) 20. The configuration of the brake ECU 20 will be described in detail later.

[0020] The rotating electric machine 150 is a device that receives a supply of electric power from the battery 160 and generates a driving force for rotating the wheels 121, 122, i.e., a driving force required for the vehicle 100 to travel. The rotating electric machine 150 is, for example, a so-called "motor generator." The driving force generated by the rotating electric machine 150 is transmitted to each of the wheels 121, 122 via the powertrain unit 140, causing the wheels 121, 122 to rotate. Note that the exchange of electric power between the battery 160 and the rotating electric machine 150 is performed via an inverter 151.

[0021] The rotating electric machine 150 generates a driving force for accelerating the vehicle 100, and also generates a braking force by regeneration for decelerating the vehicle 100. The braking of the vehicle 100 can be performed by the rotating electric machine 150 or by the brake devices 131 and 132.

[0022] The battery 160 is a storage battery for supplying driving power to the rotating electric machine 150. In this embodiment, as an example, a lithium ion battery is used as the battery 160. Regenerative power generated by the rotating electric machine 150 during braking is supplied to the battery 160 via the inverter 151 and charged into the battery 160.

[0023] The vehicle 100 is provided with a brake ECU 20 separate from the vehicle control device 10. Both the vehicle control device 10 and the brake ECU 20 are configured as computer systems having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. These can communicate with each other bidirectionally via a network provided in the vehicle 100. Details of the hardware configuration of the vehicle control device 10 will be described later.

[0024] The brake ECU 20 performs processing to control the operation of the brake devices 131 and 132 in response to instructions from the vehicle control device 10 .

[0025] The vehicle control device 10 and the brake ECU 20 do not have to be separated into two devices as in the present embodiment. For example, the functions of the brake ECU 20 may be integrated into the vehicle control device 10. When realizing the functions of the vehicle control device 10 described later, the specific device configuration is not particularly limited.

[0026] Next, an example of the hardware configuration of the vehicle control device 10 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing an example of the hardware configuration of the vehicle control device 10. The vehicle control device 10 includes a control unit 21, a communication unit 22, and a storage unit 23.

[0027] The control unit 21 is configured as a device including a general computer. The control unit 21 includes a CPU 21A, a ROM 21B, a RAM 21C, and an input / output interface (I / O) 21D. The CPU 21A, the ROM 21B, the RAM 21C, and the I / O 21D are connected to each other via a bus 21E. The bus 21E includes a control bus, an address bus, a data bus, etc.

[0028] The I / O 21D is connected to a communication unit 22, a storage unit 23, and a sensor group 200. The communication unit 22 is an interface for communicating with external devices such as the brake ECU 20 and the rotating electrical machine 150.

[0029] The storage unit 23 is configured as a non-volatile external storage device such as a hard disk, etc. The storage unit 23 stores a vehicle control program 23A.

[0030] The CPU 21A is an example of a computer. The term "computer" as used herein refers to a processor in a broad sense, and includes a general-purpose processor (e.g., the CPU 21A) or a dedicated processor (e.g., a GPU: Graphics Processing Unit, an ASIC: Application Specific Integrated Circuit, an FPGA: Field Programmable Gate Array, a programmable logic device, etc.).

[0031] The vehicle control program 23A may be stored in a non-volatile, non-transitory recording medium or distributed via a network and appropriately installed in the vehicle control device 10, thereby being stored in the storage unit 23. The vehicle control program 23A may also be appropriately updated via so-called OTA (Over The Air).

[0032] Examples of non-volatile non-transient recording media include CD-ROMs (Compact Disc Read Only Memory), magneto-optical disks, HDDs (Hard Disk Drives), DVD-ROMs (Digital Versatile Disc Read Only Memory), flash memories, memory cards, etc.

[0033] Vehicle 100 may be provided with a large number of sensors for measuring various physical quantities. Fig. 3 is a block diagram showing an example of a sensor group 200. Sensor group 200 may include a wheel speed sensor 201, an acceleration sensor 202, a current sensor 203, an exterior camera 204, an accelerator sensor 205, an external temperature sensor 206, and a gradient sensor 207. Sensor group 200 may also include a brake sensor 208, a parking sensor 209, a yaw rate sensor 210, a rotation speed sensor 211, and a cooling sensor 212.

[0034] The wheel speed sensor 201 is a sensor for measuring the number of rotations per unit time of the wheel 111, etc. Although the wheel speed sensor 201 is provided individually for each of the four wheels 111, 112, 121, and 122, in FIG. 3 , the wheel speed sensor 201 is schematically depicted as a single block. A signal indicating the number of rotations measured by the wheel speed sensor 201 is input to the vehicle control device 10. The vehicle control device 10 can grasp the traveling speed of the vehicle 100 based on this signal.

[0035] The acceleration sensor 202 is a sensor for detecting the acceleration of the vehicle 100. The acceleration sensor 202 is attached to the vehicle body 101. The acceleration sensor 202 is configured as a six-axis acceleration sensor that can detect the accelerations of the vehicle body 101 in the front-rear, left-right, and up-down directions, as well as the rotational accelerations of pitching, rolling, and yawing.

[0036] The acceleration acquired by the acceleration sensor 202 includes an acceleration GX along the traveling direction of the vehicle 100 (i.e., the longitudinal direction) and an acceleration GY along the lateral direction of the vehicle 100. The acceleration GX is also called "longitudinal acceleration," and the acceleration GY is also called "lateral acceleration." Both of these are acquired as numerical values ​​in units of "G," which is the acceleration of gravity, such as "0.5 G." Signals indicating the respective accelerations detected by the acceleration sensor 202 are input to the vehicle control device 10.

[0037] The current sensor 203 is a sensor for detecting the value of the drive current flowing through the rotating electric machine 150. A signal indicating the value of the drive current detected by the current sensor 203 is input to the vehicle control device 10. The vehicle control device 10 can determine the magnitude of the drive force generated by the rotating electric machine 150 based on the value of the input drive current.

[0038] The exterior camera 204 is a camera that captures images of the surroundings of the vehicle 100, and is, for example, a CMOS (Complementary Metal Oxide Semiconductor) camera. Image data captured by the exterior camera 204 is input to the vehicle control device 10. By processing the images, the vehicle control device 10 can determine the presence and shape of obstacles (e.g., steps such as wheel chocks) around the vehicle 100.

[0039] Note that vehicle 100 may be provided with other sensors in addition to exterior camera 204 or instead of exterior camera 204 as sensors for detecting the conditions around vehicle 100. Examples of such sensors include a light detection and ranging (LIDAR) sensor and radar.

[0040] The accelerator sensor 205 is a sensor that detects the amount of accelerator pedal operation, i.e., the accelerator opening degree. A signal indicating the amount of accelerator pedal operation detected by the accelerator sensor 205 is input to the vehicle control device 10.

[0041] The external temperature sensor 206 is a sensor that detects the temperature outside the vehicle 100. A signal indicating the external temperature detected by the external temperature sensor 206 is input to the vehicle control device 10.

[0042] The gradient sensor 207 is a sensor that detects the gradient of the road surface on which the vehicle 100 is traveling. A signal indicating the gradient detected by the gradient sensor 207 is input to the vehicle control device 10.

[0043] The brake sensor 208 is a sensor that detects the brake hydraulic pressure of the brake devices 131, 132. A signal indicating the brake hydraulic pressure detected by the brake sensor 208 is input to the vehicle control device 10.

[0044] The parking sensor 209 is a sensor that detects the on / off state of the parking brake of the vehicle 100. A signal indicating the on / off state detected by the parking sensor 209 is input to the vehicle control device 10.

[0045] The yaw rate sensor 210 is a sensor for detecting the yaw rate of the vehicle 100. A signal indicating the yaw rate detected by the yaw rate sensor 210 is input to the vehicle control device 10.

[0046] The rotation speed sensor 211 is a sensor for detecting the rotation angle and rotation speed of the rotating electric machine 150. A signal indicating the rotation speed detected by the rotation speed sensor 211 is input to the vehicle control device 10.

[0047] The cooling sensor 212 is a sensor for detecting the temperature of the cooling water that cools the drive unit 152. The drive unit 152 may include the rotating electric machine 150 and the inverter 151. The cooling water cools the inverter 151, for example. A signal indicating the temperature detected by the cooling sensor 212 is input to the vehicle control device 10.

[0048] 5 is a diagram showing an example configuration of a drive unit 152 including a rotating electric machine 150 and an inverter 151. The rotating electric machine 150 includes a stator 153, a rotor 154, a current sensor 203, and a rotation speed sensor 211. The rotating electric machine 150 is a three-phase motor generator, and the stator 153 has windings 155U, 155V, and 155W of multiple phases. The winding 155U is a U-phase winding, the winding 155V is a V-phase winding, and the winding 155W is a W-phase winding. The current sensor 203, for example, detects the current flowing through the winding 155V and the current flowing through the winding 155W. The rotation speed sensor 211 is, for example, a resolver, and detects the rotation angle and rotation speed of the rotor 154.

[0049] The inverter 151 has six power elements 156Uu, 156Ud, 156Vu, 156Vd, 156Wu, and 156Wd. Hereinafter, unless there is a need to distinguish between the six power elements 156Uu, 156Ud, 156Vu, 156Vd, 156Wu, and 156Wd, the six power elements 156Uu, 156Ud, 156Vu, 156Vd, 156Wu, and 156Wd will be referred to as "power elements 156." Each power element 156 is, for example, a power transistor. The power elements 156Uu and 156Ud are U-phase power elements, the power elements 156Vu and 156Vd are V-phase power elements, and the power elements 156Wu and 156Wd are W-phase power elements. The power elements 156Uu and 156Ud are bridge-connected to the winding 155U, the power elements 156Vu and 156Vd are bridge-connected to the winding 155V, and the power elements 156Wu and 156Wd are bridge-connected to the winding 155W.

[0050] The inverter 151 has one temperature sensor 157. The temperature sensor 157 is provided in one of the multiple power elements 156. In this embodiment, as an example, the temperature sensor 157 is provided in the power element 156Vu and detects the temperature of the power element 156Vu. Note that although the example in which the temperature sensor 157 is provided in the power element 156Vu is given here, the temperature sensor 157 may be provided in a power element 156 other than the power element 156Vu. Furthermore, the temperature sensor 157 may be provided in the power element 156 with the strictest heat resistance conditions among the six power elements 156. For example, if the inverter 151 has a heat dissipation mechanism, the power element 156 with the strictest heat resistance conditions corresponds to the power element with the smallest heat dissipation energy by the heat dissipation mechanism. These power elements may be considered as inverter elements.

[0051] Next, an example of the functional configuration of the CPU 21A of the vehicle control device 10 will be described with reference to Fig. 4. Fig. 4 is a block diagram showing an example of the functional configuration of the CPU 21A of the vehicle control device 10. The CPU 21A functions as each functional unit shown in Fig. 4 by reading and executing a vehicle control program 23A stored in the storage unit 23 (see Fig. 2). The CPU 21A includes a command torque calculation unit 31 and an inverter control unit 32.

[0052] The command torque calculation unit 31 selects and controls the torque of the rotating electric machine 150 (see FIG. 1 ). The command torque calculation unit 31 includes a torque control unit 31a that calculates the torque of the rotating electric machine 150 based on detection information from the sensor group 200, a target torque selection unit 31b, and a gradient estimation unit 31c. The target torque selection unit 31b may select, for example, as the target torque, either a torque that suppresses slip and stably transmits driving force to the road surface, or a torque that corresponds to the driver's intention, and output the selected target torque as a command torque for vector control. The gradient estimation unit 31c detects the gradient based on the detection value detected by the gradient sensor 207 and outputs the detected gradient value to the control unit 32a.

[0053] The inverter control unit 32 controls the inverter 151 that drives the rotating electric machine 150. The inverter control unit 32 also executes protection control processing to protect the drive unit 152 (see FIG. 1 ) including the rotating electric machine 150 and the inverter 151 by preventing overheating of the drive unit 152. Specifically, when the inverter control unit 32 detects a motor lock state and a temperature rise of the drive unit 152 including the rotating electric machine 150 and the inverter 151 is expected, the inverter control unit 32 may execute control to suppress the torque of the rotating electric machine 150 so as to lower the temperature. The motor lock state may be interpreted as a locked state in which the rotating electric machine 150 does not rotate when current is applied to the rotating electric machine 150, for example, when the vehicle 100 starts on a slope.

[0054] The inverter control unit 32 includes a control unit 32a, a torque mediation unit 32b, and a vector control unit 32c.

[0055] When the control unit 32a detects a motor lock state in which the rotating electric machine 150 does not rotate when current is applied to the rotating electric machine 150, the control unit 32a limits the torque of the rotating electric machine 150 so as to lower the temperature of the rotating electric machine 150 and the drive unit 152 including the inverter 151. The control unit 32a includes a lock determination unit 32a1 and a torque control unit 32a2.

[0056] When the lock determination unit 32a1 detects a motor lock state, that is, when current is concentrating in a specific phase due to the motor lock state, the lock determination unit 32a1 sets the lock determination to 1 in order to limit the output torque. Then, when there is no longer any concern about current concentration in a specific phase, the lock determination unit 32a1 sets the lock determination to 0 in order to release the limit on the output torque.

[0057] The lockup determination unit 32a1 outputs a lockup determination value, which is the result of these determinations, to the torque control unit 32a2. If the lockup determination value is 1, the torque control unit 32a2 outputs a command to limit the output torque of the rotating electric machine 150 to the torque arbitration unit 32b. If the lockup determination value is 0, the torque control unit 32a2 outputs a command to release the output torque limit of the rotating electric machine 150 to the torque arbitration unit 32b. The torque arbitration unit 32b arbitrates the command torque from the target torque selection unit 31b in accordance with the lockup determination value, and outputs the arbitrated command torque to the vector control unit 32c. The vector control unit 32c executes torque control commensurate with the torque command value, which is the value of the command torque.

[0058] (Example 1 of Control by Lock Determination Unit 32a1) The lock determination unit 32a1 may predict a phase in which current will concentrate if the motor lock state is released as a current concentration phase, and release the motor lock state if it determines that the predicted current concentration phase is different from the specific phase. This makes it possible to prevent only the inverter element of the specific phase from overheating due to repeated current concentration in the same phase.

[0059] (Control Example 2 by Lock Determination Unit 32a1) The lock determination unit 32a1 may adjust the angle of the rotating electric machine 150 to a current concentration phase different from the specific phase by adding the angle fluctuation amount of the rotating electric machine 150 when the torque command value is increased at a constant rate of change to the current angle of the rotating electric machine 150. By adjusting the MG angle to a phase different from the current concentration phase, the thermal load can be distributed to inverter elements of multiple phases. Note that a specific method for adjusting the MG angle will be described later.

[0060] (Control Example 3 by Lockup Determination Unit 32a1) The lockup determination unit 32a1 may calculate the angle fluctuation amount described above based on the gradient of the road surface on which the vehicle 100 is traveling. Calculating the MG angle fluctuation amount from the gradient increases the accuracy of the running resistance and improves the accuracy of the MG angle fluctuation amount. A specific example of a method of calculating the MG angle fluctuation amount using the gradient will be described later.

[0061] (Control Example 4 by Lockout Determination Unit 32a1) When detecting an accelerator hill-hold operation, the lockout determination unit 32a1 may adjust the angle of the rotating electric machine 150 to a current concentration phase different from the specific phase by adding an angle fluctuation amount of the rotating electric machine 150 to the current angle of the rotating electric machine 150. Furthermore, when detecting further depression of the accelerator pedal after detecting an accelerator hill-hold operation, the lockout determination unit 32a1 may adjust the angle of the rotating electric machine 150 to the specific phase. The accelerator hill-hold operation is a process of operating the accelerator pedal provided on the vehicle 100 to keep the vehicle 100 stopped so that the torque of the rotating electric machine 150 and the load torque acting on the rotating electric machine 150 are balanced. This allows current to flow through inverter elements that are not overheated during an uphill start when the accelerator is further depressed from the accelerator hill-hold state. This prevents the temperature of the overheated inverter elements from reaching the current concentration determination threshold and causing output torque restrictions, improving hill-climbing performance.

[0062] Next, the operation of the vehicle control device 10 will be described with reference to Figures 6 to 14. Figure 6 is a diagram for explaining the lock determination process.

[0063] (Overview of lock determination process) When current is concentrated in a specific phase due to a motor lock state, the CPU 21A sets the lock determination to 1 to limit the output torque, and when there is no longer any concern about current concentration in a specific phase, sets the lock determination to 0 to release the limit on the output torque.

[0064] For example, if a current is concentrated in a specific phase (e.g., the U phase) due to a motor lock state, the CPU 21A sets the lock determination to 1. The CPU 21A then predicts a phase (e.g., the V phase or the W phase) where current will be concentrated if the motor lock state is released as the current concentration phase. If the CPU 21A determines that the predicted current concentration phase (e.g., the V phase or the W phase) is different from the specific phase (e.g., the U phase), it sets the lock determination to 0, thereby releasing the motor lock state. Releasing the motor lock state releases the output torque restriction, so that, for example, current flows in the predicted current concentration phase, the W phase. According to the control disclosed herein, the phase in which current is concentrated switches in the order of the U phase, the W phase, the V phase, and so on, thereby preventing the inverter elements of the specific phase from overheating due to current concentrating only in the specific phase.

[0065] The process of limiting the output torque (FIG. 11) will be described later.

[0066] (Details of Lock Determination Process) In step S1, the CPU 21A determines whether the absolute value of the motor rotation speed is less than the determination threshold. If the absolute value of the motor rotation speed is greater than the determination threshold, the CPU 21A executes the process of step S2. If the absolute value of the motor rotation speed is less than the determination threshold, the CPU 21A executes the process of step S6.

[0067] In step S2, the CPU 21A determines whether the command torque is equal to or greater than the continuous allowable torque. If the command torque is equal to or greater than the continuous allowable torque, the CPU 21A executes the process of step S3. If the command torque is less than the continuous allowable torque, the CPU 21A executes the process of step S6.

[0068] In step S3, the CPU 21A determines whether the motor current is equal to or greater than the determination threshold. If the motor current is equal to or greater than the determination threshold, the CPU 21A executes the process of step S4. If the motor current is less than the determination threshold, the CPU 21A executes the process of step S6.

[0069] In step S4, the CPU 21A determines whether the conditions in steps S1 to S3 have been met continuously for a predetermined period of time or more. If these conditions have been met continuously for a predetermined period of time or more, the CPU 21A executes the process of step S5. If these conditions have not been met continuously for a predetermined period of time or more, the CPU 21A executes the process of step S6.

[0070] In step S5, the CPU 21A turns on the lock determination, that is, enables the lock determination, because there is a concern that the rotating electrical machine 150 in the motor lock state may overheat. As a result, the CPU 21A limits the output torque of the rotating electrical machine 150.

[0071] In step S6, the CPU 21A determines whether the previous lock determination is ON, that is, whether the motor was locked in the previous process. If the previous lock determination is ON, the CPU 21A executes the process of step S7. If the previous lock determination is OFF, the CPU 21A executes the process of step S9.

[0072] In step S7, the CPU 21A executes a phase switching determination process. After executing the phase switching determination, the CPU 21A executes the process of step S8. The phase switching determination will be described in detail later.

[0073] In step S8, the CPU 21A determines whether the switching flag is 1. When the switching flag is 1, this may be interpreted as a state in which current is not repeatedly concentrating and flowing in a specific phase, i.e., a state in which there is no concern about overheating of the rotating electric machine 150. When the switching flag is 0, this may be interpreted as a state in which current is repeatedly concentrating and flowing in a specific phase, i.e., a state in which there is a concern about overheating of the rotating electric machine 150. When the switching flag is 1, the CPU 21A executes the process of step S9, and when the switching flag is 0, the CPU 21A executes the process of step S5.

[0074] In step S9, the CPU 21A sets the lock determination to OFF because there is no concern about overheating of the rotating electrical machine 150. In other words, the lock determination is disabled.

[0075] The motor lock execution conditions will be described with reference to Fig. 7. If the previous lock determination value was OFF (NO in step S6) and the current lock determination value is OFF, it is possible to predict that current will not repeatedly concentrate in a specific phase, and therefore the CPU 21A sets the lock determination to OFF (step S9).

[0076] If the previous lock determination value was ON (YES in step S6) and the current lock determination value is OFF, and it is predicted that current will not repeatedly concentrate in a specific phase, there is no risk of overheating of the rotating electric machine 150, so the CPU 21A sets the lock determination value to OFF (step S9). This releases the output torque limit of the rotating electric machine 150.

[0077] When the previous lock determination value was ON (YES in step S6) and the current lock determination value is OFF, if it is predicted that current will repeatedly concentrate in a specific phase, there is a concern that the rotating electrical machine 150 may overheat, so the CPU 21A measures the lock determination and sets it to ON (step S5). As a result, the output torque of the rotating electrical machine 150 is continuously limited.

[0078] Next, the phase switching determination process of step S7 will be described with reference to Fig. 8 to Fig. 10. Fig. 8 is a flowchart for explaining the phase switching determination process. Fig. 9 is a diagram showing the relationship between the MG angle and phase current before and after adjustment. Fig. 10 is a diagram for explaining the method of calculating the MG angle fluctuation amount in step S74.

[0079] In step S71, the CPU 21A obtains the MG electrical angle (MG angle).

[0080] In step S72, the CPU 21A selects a phase (for example, the U phase) in which current concentration is not to occur, based on the MG angle.

[0081] In step S73, the CPU 21A calculates an MG angle range in which current will not be concentrated in the selected phase. Assume that a U-phase current exceeding the current concentration determination threshold is concentrated in the U-phase inverter element of the upper arm, as shown in Fig. 9 . In this case, when the MG angle (e.g., 220°) through which this phase current flows, i.e., the MG angle before angle adjustment, is within the MG angle range, the CPU 21A calculates an MG angle that will at least be outside the MG angle range.

[0082] In step S74, the CPU 21A calculates the MG angle fluctuation amount (Δθ) while the output torque limit is released, as shown in Fig. 9. Δθ may be calculated and predicted according to equation (1). (Assumptions for predicting Δθ) - Command torque is constant - When the output torque matches the running resistance, the MG does not rotate.

[0083] Running resistance may be calculated using only gradient resistance. M represents the weight of the vehicle 100. G represents gravitational acceleration. α represents gradient. V represents the vehicle speed. SWR represents the tire radius. τds_req represents the driver requested torque (output of the target torque selection unit 31b) in the drive shaft (DS). Kds represents the drive shaft stiffness [rad / Nm]. The command torque (output of the torque mediation unit 32b) is calculated by command torque = limit rate × τds_req. ΔT is the amount of fluctuation in the torque command as shown in Figure 10. Figure 10 shows the accelerator opening, torque command value, and MG electrical angle (MG angle). Δθ is the MG electrical angle (MG angle) Δθ shown in Figure 10. １ and Δθ ２ It may be interpreted as the sum of the torque fluctuation amounts during the release of the output torque limit.

[0084]

[0085] In step S75, the CPU 21A calculates the MG angle after the output torque limit is released, as shown in FIG. 9 , by adding the MG angle fluctuation amount to the MG angle range. The MG angle after the output torque limit is released may be interpreted as the MG angle after angle adjustment. The MG angle after angle adjustment shown in FIG. 9 allows, for example, a W-phase current to flow through the W-phase inverter element of the lower arm. Note that the MG angle after angle adjustment is not limited to this, and may also be an angle at which a phase current flows through any of the inverter elements of the U-phase of the lower arm, the W-phase of the lower arm, the V-phase of the upper arm, and the W-phase of the upper arm.

[0086] In step S76, the CPU 21A determines whether the MG angle calculated in step S75 is outside a specific electrical angle range. If the MG angle is outside the specific electrical angle range, the CPU 21A executes the process of step S77 to switch the energized phase. If the MG angle is not outside the specific electrical angle range, the CPU 21A executes the process of step S78 to maintain the current energized phase.

[0087] In step S77, the CPU 21A sets the switching flag to 1. This switches the energized phase, for example, from the U phase to the W phase (see FIG. 9 ), thereby preventing the U-phase current from concentrating in the U-phase inverter element of the upper arm.

[0088] In step S78, the CPU 21A sets the switching flag to 0 in order to maintain the current energized phase.

[0089] 11 is a flowchart illustrating the process of limiting the output torque and releasing the output torque limit. In the present disclosure, the process of limiting the output torque as overheat protection control may be executed when the concern about overheating is not resolved, and the process of releasing the limit on the output torque at a constant rate may be executed when the concern about overheating is resolved.

[0090] In step S31, the CPU 21A determines whether the lock determination result is ON. If the lock determination result is ON, the CPU 21A executes the process of step S32. If the lock determination result is not ON, the CPU 21A executes the process of step S33.

[0091] In step S32, the CPU 21A sets the limit rate to a negative value and executes the process of step S334. In step S33, the CPU 21A sets the limit rate to a positive value and executes the process of step S34.

[0092] In step S34, the CPU 21A updates the limit rate by adding the limit rate to the predetermined limit rate. In steps S35 and S36, the CPU 21A sets the minimum and maximum values ​​(min, max) of the predetermined limit rate, and in step S37, the CPU 21A calculates the output torque by multiplying the load factor by the required torque.

[0093] 12 and 13 are timing charts for explaining the operation of the vehicle control device 10. Fig. 12 and 13 show an example of operation when adjusting the angle of the rotating electric machine 150 mounted on the vehicle 100 stopped on a slope.

[0094] 12 and 13 show, from top to bottom, the accelerator opening, the torque command value, the MG electrical angle (MG angle), and the result of the lock determination. The horizontal axis represents time. The period from time t0 to t1 represents the period when the vehicle is stopped on a slope, the period from time t1 to t2 represents the period when the output torque is limited, the period from time t2 to t3 represents the period when the output torque limit is released, and the period from time t3 to t4 represents the period when the vehicle is stopped on a slope.

[0095] The period from time t4 to t5 in Fig. 13 represents a period during which the output torque is limited, similar to the period from time t1 to t2. The period from time t5 to t6 in Fig. 13 represents a period during which the output torque limit is released, similar to the period from time t2 to t3.

[0096] At time t0, there is no concern about current concentration in a specific phase, so the lock determination is 0. If current subsequently concentrates in a specific phase due to an accelerator hill-hold operation, the lock determination changes from 0 to 1 at time t1. This initiates output torque restriction, causing the vehicle 100 to roll down, and as the vehicle 100 moves slightly, the rotor of the rotating electrical machine 150 rotates in a specific direction, causing a change in the MG angle.

[0097] At time t2, if it is determined (predicted) that no current will concentrate in a specific phase, the lock determination is released. That is, the lock determination changes from 1 to 0. This releases the output torque limit, causing the rotor of the rotating electric machine 150 to rotate in the direction opposite to the specific direction described above, and the MG angle changes. Thereafter, by time t3, the MG angle fluctuation amount is calculated, and at time t3, the MG angle is adjusted to an angle that does not repeatedly cause current to concentrate in a specific phase. Then, current continues to be supplied to the rotating electric machine 150 at the adjusted MG angle.

[0098] By adjusting the MG angle in this way so as to prevent current from concentrating in a specific phase, the MG angle from time t0 to t1, the MG angle from time t3 to t4, and the MG angle from time t6 onwards are set to different values, as shown in Figure 13. In other words, the MG angle changes so that current does not concentrate in only a specific phase.

[0099] 14 is a diagram showing the relationship between three phase currents and the temperatures of the inverter elements through which those phase currents flow. According to the control disclosed herein, the MG angle can be changed so that current does not concentrate in only a specific phase. Therefore, the current concentration phase is sequentially switched from the U phase to the W phase and then to the V phase before the U-phase element temperature (e.g., the temperature of the U-phase inverter element in the upper arm) reaches its short-term heat resistance temperature (185°C). This allows the heat generated in a specific inverter element to be distributed to multiple inverter elements.

[0100] 15 to 17 are diagrams illustrating the operation of a vehicle control device according to a comparative example. FIGS. 15A to 15E show the relationship between the MG angle and phase current. The vehicle control device according to the comparative example changes the MG angle as the vehicle 100 slides down when the output torque is limited, so the MG angle changes naturally. For example, when current is concentrated in the U-phase as shown in FIG. 15A, if the output torque is limited to avoid current concentration in the U-phase, the vehicle 100 slides down, causing the MG angle to change as shown in FIG. 15B.

[0101] However, as shown in Fig. 15C, the electrical angle after the change may remain the electrical angle at which current is supplied to the U-phase. Therefore, even after the MG angle has changed, current may still be concentrated in the same U-phase.

[0102] If the output torque limit is subsequently released, the MG angle changes as shown in Fig. 15D. However, as described above, the electrical angle after the change may remain the electrical angle at which current is supplied to the U-phase. Therefore, even after the output torque limit is released, current may still be concentrated in the same U-phase, as shown in Fig. 15E.

[0103] Figure 16 shows the MG electrical angle (MG angle) when current is concentrated in the U-phase as shown in Figure 15. Figure 17 shows the relationship between the phase currents and the temperatures of the inverter elements through which those phase currents flow in a comparative example. As shown in Figure 17, even if the output torque is limited before the U-phase element temperature reaches the short-term heat resistance temperature (185°C), current flows through the U-phase again before the U-phase element temperature has completely dropped, so the U-phase element temperature remains high. This can shorten the life of the U-phase element.

[0104] As described above, the drive control device of the present disclosure predicts a phase where current will concentrate if the motor lock state is released as a current concentration phase, and can release the motor lock state if it determines that the predicted current concentration phase is different from the specific phase. Because a phase other than the specific phase can be predicted as a phase where current will concentrate if the motor lock state is released before the actual release of the motor lock state, the current-carrying phase can be immediately switched when the motor lock state is released. Therefore, even if current is concentrated in the U phase, for example, the current-carrying phase after the motor lock state is released can be changed to the V phase or W phase other than the U phase. This prevents the inverter element of the specific phase from overheating due to current concentrating only in the U phase.

[0105] Although the present embodiment has been described above, the present disclosure is not limited to the above-described embodiments, and various modifications and applications are possible within the scope of the gist of the present disclosure.

[0106] Furthermore, the configuration of the vehicle control device 10 described in the above embodiment (see Figure 2) is one example, and it goes without saying that unnecessary parts may be deleted or new parts may be added within the scope of the present disclosure.

[0107] Furthermore, the processing flow of the vehicle control program 23A described in the above embodiment is also an example, and it goes without saying that unnecessary steps may be deleted, new steps may be added, or the processing order may be rearranged within the scope of the present disclosure.

[0108] The controller and methods described herein may be implemented by a special-purpose computer having a processor programmed to perform one or more functions embodied in a computer program. Alternatively, the apparatus and methods described herein may be implemented by a special-purpose computer having a processor configured with dedicated hardware logic circuitry. Alternatively, the apparatus and methods described herein may be implemented by one or more special-purpose computers configured by a combination of a processor executing a computer program and one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium.

[0109] The following notes are provided regarding the technology of the present disclosure.

[0110] (Supplementary Note 1) A vehicle control device (10) comprising: an inverter control unit (32) that controls an inverter (151) that drives a rotating electric machine (150) for driving a vehicle that is mounted on a vehicle (100); and a control unit (32a) that, when detecting a motor lock state in which the rotating electric machine does not rotate when current is supplied to the rotating electric machine, executes control to suppress the torque of the rotating electric machine so as to lower the temperature of a drive unit (152) including the rotating electric machine and the inverter, wherein, when a single-phase continuous current state occurs in which current flows continuously in a specific phase of a plurality of phases of the rotating electric machine for a specific period of time or more during the motor lock state, the control unit predicts, as a current concentration phase, a phase in which current will concentrate if the motor lock state is released, and, when it is determined that the predicted current concentration phase is different from the specific phase, releases the motor lock state.

[0111] (Appendix 2) The vehicle control device according to Appendix 1, wherein the control unit adjusts the angle of the rotating electric machine to the current concentration phase different from the specific phase by adding an angle fluctuation amount of the rotating electric machine when a torque command value is increased at a constant rate of change to the current angle of the rotating electric machine.

[0112] (Supplementary Note 3) The vehicle control device according to Supplementary Note 2, wherein the control unit calculates the angle variation amount based on a gradient of a road surface on which the vehicle is traveling.

[0113] (Appendix 4) The vehicle control device described in Appendix 2, wherein the control unit, when detecting an accelerator hill-hold operation in which the vehicle is kept stopped by operating an accelerator pedal provided on the vehicle so that the torque of the rotating electric machine and the load torque acting on the rotating electric machine are balanced, adjusts the angle of the rotating electric machine to the current concentration phase different from the specific phase by adding an angle fluctuation amount of the rotating electric machine to the current angle of the rotating electric machine, and when detecting further depression of the accelerator pedal, adjusts the angle of the rotating electric machine to the specific phase.

[0114] (Supplementary Note 5) A vehicle control program (23A) that causes at least one processor (21A) to execute processing including: controlling an inverter (151) that drives a rotating electric machine (150) for driving a vehicle (100) that is mounted on the vehicle; when a motor lock state in which the rotating electric machine does not rotate when current is applied to the rotating electric machine is detected, executing control to suppress the torque of the rotating electric machine so as to lower the temperature of a drive unit (152) that includes the rotating electric machine and the inverter; when a single-phase continuous current state occurs in which current flows continuously in a specific phase of multiple phases of the rotating electric machine for a specific period of time or more during the motor lock state, predicting a phase in which current will concentrate if the motor lock state is released as a current concentration phase, and when it is determined that the predicted current concentration phase is different from the specific phase, releasing the motor lock state.

[0115] (Supplementary Note 6) A vehicle control method that executes processing including: at least one processor (21A) controls an inverter (151) that drives a rotating electric machine (150) for driving a vehicle that is mounted on a vehicle (100); when a motor lock state in which the rotating electric machine does not rotate when current is applied to the rotating electric machine is detected, executes control to suppress the torque of the rotating electric machine so as to lower the temperature of a drive unit (152) that includes the rotating electric machine and the inverter; when a single-phase continuous current state occurs in which current flows continuously in a specific phase of multiple phases of the rotating electric machine for a specific period of time or more during the motor lock state, predicts a phase in which current will concentrate if the motor lock state is released as a current concentration phase, and when it is determined that the predicted current concentration phase is different from the specific phase, releases the motor lock state.

Claims

1. A vehicle control device (10) comprising: an inverter control unit (32) that controls an inverter (151) that drives a rotating electric machine (150) for driving a vehicle that is mounted on a vehicle (100); and a control unit (32a) that, when detecting a motor lock state in which the rotating electric machine does not rotate when current is supplied to the rotating electric machine, executes control to suppress the torque of the rotating electric machine so as to lower the temperature of a drive unit (152) including the rotating electric machine and the inverter, wherein, when a single-phase continuous current state occurs in which current flows continuously in a specific phase of the multiple phases of the rotating electric machine for a specific period of time or more during the motor lock state, the control unit predicts that the phase in which current will concentrate if the motor lock state is released is a current concentration phase, and releases the motor lock state when it is determined that the predicted current concentration phase is different from the specific phase.

2. The vehicle control device described in claim 1, wherein the control unit adjusts the angle of the rotating electric machine to the current concentration phase different from the specific phase by adding the amount of angle fluctuation of the rotating electric machine when the torque command value is increased at a constant rate of change to the current angle of the rotating electric machine.

3. The vehicle control device according to claim 2, wherein the control unit calculates the amount of angle fluctuation based on the gradient of the road surface on which the vehicle is traveling.

4. A vehicle control device as described in claim 2, wherein, when an accelerator hill-hold operation is detected in which the vehicle is kept stopped by operating an accelerator pedal provided on the vehicle so that the torque of the rotating electric machine and the load torque acting on the rotating electric machine are balanced, the control unit adjusts the angle of the rotating electric machine to the current current concentration phase different from the specific phase by adding the angle fluctuation amount of the rotating electric machine to the current angle of the rotating electric machine, and when an additional depression of the accelerator pedal is detected, the control unit adjusts the angle of the rotating electric machine to the specific phase.

5. A vehicle control program (23A) that causes at least one processor (21A) to execute processing including: controlling an inverter (151) that drives a rotating electric machine (150) for driving a vehicle (100) that is mounted on the vehicle; when a motor lock state in which the rotating electric machine does not rotate when current is applied to the rotating electric machine is detected, executing control to suppress the torque of the rotating electric machine so as to lower the temperature of a drive unit (152) including the rotating electric machine and the inverter; when a single-phase continuous current state occurs in which current flows continuously in a specific phase of multiple phases of the rotating electric machine for a specific period of time or more during the motor lock state, predicting a phase in which current will concentrate if the motor lock state is released as a current concentration phase, and releasing the motor lock state if it is determined that the predicted current concentration phase is different from the specific phase.

6. A vehicle control method in which at least one processor (21A) controls an inverter (151) that drives a rotating electric machine (150) for driving a vehicle (100) and is mounted on the vehicle; when detecting a motor lock state in which the rotating electric machine does not rotate when current is supplied to the rotating electric machine, the processor executes control to suppress the torque of the rotating electric machine so as to lower the temperature of a drive unit (152) including the rotating electric machine and the inverter; when, during the motor lock state, a single-phase continuous current state occurs in which current flows continuously in a specific phase of the multiple phases of the rotating electric machine for a specific period of time or more, the processor predicts the phase in which current will concentrate if the motor lock state is released as a current concentration phase, and when it is determined that the predicted current concentration phase is different from the specific phase, the processor releases the motor lock state.

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