Motor control device and motor control method

Abstract

To suppress rotational vibration at the time of release of the locked state of a parking lock system, and reduce wear of the engaging portion of the parking lock system. A motor control device (80) that controls a drive motor (10) of an electric vehicle that is provided with a parking lock system (2) that holds wheels (35a, 35b) in a state in which they cannot rotate when parking, detects a case in which the locked state of the parking lock system (2) is released; based on the rotational speed of the drive motor (10), forms a positive damping torque in the opposite direction to the direction of rotational vibration of the drive motor (10).

Description

Technical Field

[0001] This invention relates to a motor control device and a motor control method. Background Technology

[0002] A parking lock system is known to keep the wheels in a non-rotating state when a vehicle is parked. This parking lock system is equipped in the drive system of an electric vehicle, locking the rotational elements of the drive system to prevent the wheels from rotating when parked. For example, Patent Document 1 discloses a parking lock system comprising a parking lever, a parking operating lever, and a parking gear; the parking operating lever is oscillating about a shaft via an actuator; a protrusion is provided on the parking gear side of the parking operating lever that can engage with the parking gear; and the system can switch between a state where the protrusion is engaged with the parking gear and a state where engagement is disengaged. The parking gear is connected to the drive shaft and is configured to engage with the protrusion of the parking operating lever; if the parking gear engages with the protrusion, the rotation of the drive shaft is restricted.

[0003] In Patent Document 1, the parking lock system activates an actuator when the gear is shifted from Park (P) to a gear other than P (non-P) and when shifting from non-P to P, respectively, switching the engagement or disengagement of the parking gear with the protrusion of the parking lever. Furthermore, the parking lock system is sometimes used, regardless of gear position, to ensure safety in case of vehicle malfunction or when the ignition switch is off. For example, when a malfunction of a specific component of the vehicle system is detected, or when an ignition switch off signal is detected, the parking lock system engages the parking gear with the protrusion of the parking lever, restricting wheel rotation. In this case, if the drive shaft rotates at high speed, components of the parking lock system may be damaged. In contrast, Patent Document 2 proposes a parking lock system that allows engagement of the parking gear with the protrusion of the parking lever when the vehicle's speed or acceleration is less than a predetermined value.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2023-159723; Patent Document 2: German Patent Application Publication No. 102020211436. Summary of the Invention

[0005] The problem that the invention aims to solve Here, when the vehicle is parked on an inclined surface, the rotational torque required to rotate the wheels due to the vehicle's load causes the drive shaft connected to the wheels to elastically deform, guiding the rotational torque to the parking gear. The greater the inclination angle of the road surface, the greater the rotational torque guided to the parking gear. If the parking lock system is released in this state, the rotational torque attached to the parking gear is released. In the case of electric vehicles, due to the release of this rotational torque on the drive shaft, the rotor of the drive motor and the drive shaft experience rotational vibration (oscillation). If this occurs, the meshing part between the parking gear and the parking lever of the parking lock system may wear.

[0006] The present invention addresses the aforementioned problems by providing a motor control device and method capable of suppressing rotational vibrations when releasing the locked state of a parking lock system and reducing wear on the engaging parts of the parking lock system.

[0007] Methods used to solve problems To address the aforementioned issues, according to a technical solution of the present invention, a motor control device is provided, which controls the drive motor of an electric vehicle. The electric vehicle has a parking lock system that keeps the wheels in a non-rotating state when parked. The motor control device detects when the parking lock system is released and generates an active damping torque in the opposite direction to the rotational vibration of the drive motor based on the rotational speed of the drive motor.

[0008] Furthermore, in order to solve the above-mentioned problems, according to another technical solution of the present invention, a motor control method is provided, which is a motor control method for controlling a drive motor of an electric vehicle, wherein the electric vehicle has a parking lock system that keeps the wheels in a non-rotating state when parked, and the motor control method detects when the parking lock system is released; and based on the rotational speed of the drive motor, an active damping torque is generated in the opposite direction to the rotational vibration of the drive motor.

[0009] Invention Effects As explained above, according to the present invention, rotational vibration when the parking lock system is released from its locked state can be suppressed, and wear on the engaging parts of the parking lock system can be reduced. Attached Figure Description

[0010] Figure 1 This is an explanatory diagram illustrating a structural example of the parking locking system according to an embodiment of the present invention.

[0011] Figure 2 This is an explanatory diagram showing the disengaged and engaged states of the parking control lever and locking wheel of the parking locking system described in this embodiment.

[0012] Figure 3 This is an explanatory diagram showing the rotational vibrations and impacts that may occur when the parking lock system is released.

[0013] Figure 4 This is an explanatory diagram showing a reference example of rotational vibration that may occur when the parking lock system is released from its locked state.

[0014] Figure 5 This is a block diagram illustrating a structural example of the motor control device described in this embodiment.

[0015] Figure 6 This is a flowchart illustrating the motor control method described in this embodiment.

[0016] Figure 7 This is an explanatory diagram illustrating the operation of the motor control method described in this embodiment. Detailed Implementation

[0017] The following is a reference to the appendix. Figure 1 The preferred embodiments of the present invention will be described in detail below. Furthermore, in this specification and accompanying drawings, repeated descriptions are omitted by assigning the same reference numerals to constituent elements having substantially the same functional structure.

[0018] <1. Drive System of Electric Vehicles> First, an example of the structure of a drive system for an electric vehicle to which the motor control device described in the embodiments of the present invention can be applied will be described.

[0019] Figure 1 This is a schematic diagram illustrating a structural example of a drive system 1 for an electric vehicle. The drive system 1 is a drive system with a drive motor 10 as the driving force source, and includes the drive motor 10, a gearbox 20, and a parking lock system 2.

[0020] The drive motor 10 is a permanent magnet three-phase AC motor, comprising a rotor 13 mounted on a motor shaft 15 that outputs rotational torque, and a stator 11 disposed on the outer periphery of the rotor 13. The drive motor 10 is driven by three-phase AC power supplied from an inverter 19. The inverter 19, controlled by a motor control device 80, converts DC power output from the battery 70 into three-phase AC power and outputs it. The drive motor 10 includes a speed sensor 17 that measures the rotational speed of the motor shaft 15. The speed sensor 17 may be, for example, a rotary transformer, but is not limited to a rotary transformer.

[0021] The motor control unit 80 is configured with a microcomputer and peripheral components to control the drive of the inverter 19. The motor control unit 80 is configured to acquire sensor signals from the speed sensor 17. Furthermore, the motor control unit 80 is communicatively connected to the parking lock control unit 50.

[0022] The gearbox 20 includes a gear mechanism for transmitting rotational torque output via the motor shaft 15, and a differential gear 31 for distributing rotational torque to the left and right wheels 35a and 35b. The gear mechanism includes: a drive gear 21, which is fixed to the motor shaft 15 and rotates synchronously with the motor shaft 15; a driven gear 23, which is fixed to an intermediate shaft 25, meshes with the drive gear 21, and rotates synchronously with the intermediate shaft 25; and an output gear 27, which is fixed to the intermediate shaft 25, meshes with the ring gear 29 of the differential gear 31, and rotates synchronously with the intermediate shaft 25.

[0023] The parking lock system 2 keeps the wheels 35a and 35b in a non-rotating state when the vehicle is parked. The parking lock system 2 includes: a locking mechanism 40, which is assembled in a gearbox 20, the gearbox 20 transmitting the driving torque output from the drive motor 10 to the axles 33a and 33b connected to the left and right wheels 35a and 35b; and a parking lock control device 50, which controls the operation of the locking mechanism 40.

[0024] The locking mechanism 40 includes a locking wheel 41, a parking lever 43, and an actuator 45. The locking wheel 41 has at least one engaging portion on its outer circumferential surface and is concentrically fixed relative to the motor shaft 15, rotating synchronously with the motor shaft 15. The locking wheel 41 can be fixed to a rotating shaft such as an intermediate shaft 25, which is mounted on the path of the driving force transmission route that transmits the rotational torque of the drive motor 10 to the wheels 35a and 35b. The parking lever 43 has a locking portion that engages with the engaging portion of the locking wheel 41 and is supported so as to be displaceable to switch the engagement and disengagement of the locking portion. The actuator 45 displaces the parking lever 43 to switch the engagement and disengagement of the locking portion. The actuator 45 includes a component such as an electric motor that is driven by controlling the supply of electricity, and is an actuator capable of displacing the parking lever 43.

[0025] The parking lock control device 50, comprising a microcomputer and peripheral components, controls the operation of the actuator 45 of the parking lock system 2. The parking lock control device 50 is configured to acquire sensor signals from the speed sensor 17. Furthermore, the parking lock control device 50 is configured to acquire sensor signals from the gear position sensor 3, which detects the position of the gear selected by the driver operating the shift lever or shift switch. Moreover, the parking lock control device 50 is communicatively connected to the motor control device 80.

[0026] <2. Locking Mechanism> Next, the locking mechanism 40 of the parking locking system 2 will be described in detail.

[0027] Figure 2 This is a schematic diagram showing the operating state of the locking mechanism 40.

[0028] Furthermore, in this specification, the state in which the rotation of the motor shaft 15 is restricted is referred to as the "locked state". In addition, the state in which the restriction on the rotation of the motor shaft 15 is released is referred to as the "unlocked state".

[0029] The locking mechanism 40 shown in the figure includes a locking wheel 41, a parking lever 43, a cam 46, and an actuator 45. The locking wheel 41 has at least one engaging portion 42 on its outer peripheral surface. The locking wheel 41 is fixed concentrically relative to the motor shaft 15. The parking lever 43 has a locking pawl (locking portion) 44 that can enter and engage with the engaging portion 42 of the locking wheel 41. The parking lever 43 is supported so that it can swing about a rotation axis 43a.

[0030] Cam 46 is fixed to a rotating shaft 47 driven by actuator 45. Cam 46 rotates the rotating shaft 47 via actuator 45, causing it to move forward and backward relative to parking lever 43. Cam 46 moves parking lever 43 toward locking wheel 41, and locking pawl 44 of parking lever 43 engages with locking part 42 of locking wheel 41, thus restricting the rotation of motor shaft 15. On the other hand, when cam 46 has moved away from parking lever 43, locking pawl 44 of parking lever 43 disengages from locking part 42 of locking wheel 41, and the restriction on the rotation of motor shaft 15 is released.

[0031] When the gear is in Park (P), the locking pawl 44 of the parking lever 43 enters the engaging portion 42 of the locking wheel 41, becoming locked. On the other hand, when the gear is in a gear other than Park (nP), the locking pawl 44 of the parking lever 43 disengages from the engaging portion 42 of the locking wheel 41, becoming unlocked.

[0032] The parking lock control device 50 determines the gear position by receiving a sensor signal from the gear position sensor 3, which detects the position of the gear selected by the driver operating the gear shift lever or gear shift switch. Furthermore, the parking lock control device 50 determines the rotational speed of the drive motor 10 based on a sensor signal from the speed sensor 17. When the gear is in parking position, the parking lock control device 50 locks the locking mechanism 40 to restrict the rotation of the motor shaft 15, preventing the wheels 35a and 35b from rotating. Conversely, when the gear is not in parking position, the parking lock control device 50 releases the locking mechanism 40, allowing the motor shaft 15 to rotate and enabling the wheels 35a and 35b to rotate.

[0033] <3. Wear and tear on the locking mechanism> Figure 3 This describes the unlocked state when the electric vehicle is parked on a sloping surface with the vehicle body tilted forward and backward, and the locking pawl 44 of the parking lever 43 disengages from the engaging portion 42 of the locking wheel 41. The rotational torque required to rotate the wheels 35a and 35b due to the vehicle's load is guided to the locking wheel 41 via the axles 33a and 33b and the gear mechanism of the gearbox 20. The rotational torque applied to the locking wheel 41 is released when the locking pawl 44 of the parking lever 43 disengages from the engaging portion 42 of the locking wheel 41, causing rotational vibration in the motor shaft 15 and the rotor 13 of the drive motor 10. Furthermore, the parking lever 43 also oscillates due to the reaction force of the rotating action of the cam 46.

[0034] Previously, the swinging of the parking control lever 43 and the rotational vibration of the locking wheel 41 caused impact at the meshing part of the locking pawl 44 and the locking wheel 41. As a result, the contact surface of the meshing part between the locking pawl 44 of the parking control lever 43 and the locking wheel 41 wore down, and the durability of the locking mechanism 40 may have decreased.

[0035] Figure 4 This refers to the rotational vibration of the rotor 13 of the drive motor 10 when the locking pawl 44 of the parking control lever 43 disengages from the locking part 42 of the locking wheel 41 under the condition that a rotational torque is applied to the locking wheel 41. Figure 4 The example shown represents a rotational vibration below 10 Hz. It can be seen that the rotational vibration occurs because the locking pawl 44 disengages from the engaging part 42, and the rotational vibration decays over time.

[0036] The motor control device 80 described in this embodiment has a structure that can suppress rotational vibrations as described above, and can reduce wear on the locking mechanism 40 of the parking lock system 2.

[0037] <4. Motor Control Device> Next, the motor control device 80 described in this embodiment will be explained.

[0038] Figure 5 This is a block diagram representing the functional structure of the motor control device 80.

[0039] The motor control device 80 includes a processing unit 81 and a storage unit 89. The processing unit 81 is configured with a microcomputer. The storage unit 89 is configured with storage media such as RAM (Random Access Memory) and ROM (Read Only Memory). The storage unit 89 stores programs executed by the processing unit 81, various parameters used in the calculation, calculation results, and detection results. A portion of the storage unit 89 is used as the working area of ​​the processing unit 81.

[0040] The processing unit 81 includes a parking lock release determination unit 83, a rotation speed determination unit 85, and an active damping control unit 87. These units are implemented by executing a program, for example, by a microcomputer. However, a portion of the motor control device 80 may also be constructed using hardware such as analog circuitry.

[0041] The parking lock release determination unit 83 determines when the parking lock system 2 has been released from its locked state and switched to an unlocked state. For example, the parking lock release determination unit 83 receives a signal from the parking lock control device 50 indicating that the locked state has been released. The parking lock release determination unit 83 can also determine when the gear has been switched from parking gear P to a gear other than parking gear nP based on the sensor signal from the gear position sensor 3, which detects the position of the gear selected by the driver operating the shift lever or shift switch.

[0042] The rotation speed determination unit 85 determines the rotation speed of the drive motor 10 based on the sensor signal from the speed sensor 17.

[0043] When the parking locking system 2 switches from the locked state to the unlocked state, the active damping control unit 87 performs active damping control based on the rotational speed of the drive motor 10. For example, the active damping control unit 87 controls the drive of the inverter 19 to generate an active damping torque in the opposite direction to the rotational vibration of the drive motor 10.

[0044] The active damping control unit 87 can also perform active damping control only when the rotational torque is directed to the locking mechanism 40 of the parking lock system 2 when the electric vehicle is parked. For example, the active damping control unit 87 can also calculate the tilt angle of the electric vehicle in the forward and backward direction based on the sensor signal of the tilt sensor equipped on the electric vehicle, and allow the execution of active damping control when the tilt angle is above a predetermined threshold.

[0045] <5. Control Methods> Next, the motor control method associated with active damping control performed by the motor control device 80 described in this embodiment will be explained in detail.

[0046] Figure 6 This is a flowchart illustrating an example of a motor control method associated with active damping control executed by the motor control device 80.

[0047] First, after the electric vehicle system is started, the parking lock release determination unit 83 of the processing unit 81 determines whether the parking lock system 2 has been released (step S11). For example, when the parking lock release determination unit 83 receives a signal from the parking lock control device 50 indicating that the lock state has been released, it determines that the parking lock system 2 has been released. The parking lock release determination unit 83 may also determine that the parking lock system 2 has been released based on the sensor signal of the gear position sensor 3, when it detects that the gear has been switched from parking gear P to a gear other than parking gear nP. The gear position sensor 3 detects the position of the gear selected by the driver operating the shift lever or shift switch.

[0048] If the parking lock release determination unit 83 does not determine that the parking lock system 2 has been released (S11 / No), it repeats step S11. On the other hand, if the parking lock release determination unit 83 determines that the parking lock system 2 has been released (S11 / Yes), the active damping control unit 87 determines whether the tilt angle of the electric vehicle in the forward and backward direction, calculated based on the sensor signal from the tilt sensor equipped on the electric vehicle, is above a predetermined threshold (step S13). The predetermined threshold can be set to any appropriate value as the angle at which a predetermined or higher rotational torque can be guided to the locking mechanism 40 of the parking lock system 2 during parking.

[0049] If the forward / backward tilt angle of the electric vehicle is not determined to be above a predetermined threshold (S13 / No), the active damping control unit 87 remains unchanged and the process ends. On the other hand, if the forward / backward tilt angle of the electric vehicle is determined to be above a predetermined threshold (S13 / Yes), the active damping control unit 87 begins to execute active damping control (step S15).

[0050] Next, the rotational speed determination unit 85 detects the rotational speed of the drive motor 10 based on the sensor signal from the speed sensor 17 (step S17). Then, the active damping control unit 87 calculates the active damping torque acting in the opposite direction to the detected rotational vibration based on the rotational speed of the drive motor 10 (step S19). For example, the active damping control unit 87 calculates the rotational torque corresponding to the magnitude of the rotational vibration as the value of the active damping torque.

[0051] Next, the active damping control unit 87 drives the switching element of the inverter 19 to generate active damping torque (step S21). Then, the active damping control unit 87 determines whether the termination condition has been met (step S23). For example, the active damping control unit 87 determines that the termination condition has been met when the amplitude of the rotational vibration of the drive motor 10 becomes less than a predetermined threshold. Alternatively, the active damping control unit 87 may determine that the termination condition has been met after a predetermined time has elapsed.

[0052] If the termination condition is not determined to be met (S23 / No), the active damping control unit 87 returns to step S17 and continues active damping control. On the other hand, if the termination condition is determined to be met (S23 / Yes), the active damping control unit 87 stops the execution of active damping control (step S25), thus ending the process.

[0053] Figure 7 This refers to the rotational vibration of the rotor 13 of the drive motor 10 when active damping control is performed and the locking pawl 44 of the parking operating lever 43 disengages from the locking part 42 of the locking wheel 41 while a rotational torque is applied to the locking wheel 41. Figure 7 The example shown represents rotational vibration below 10 Hz. It can be seen that although rotational vibration occurs due to the disengagement of the locking pawl 44 from the engaging portion 42, it is related to... Figure 4 The example shown decays in a short time compared to vibration.

[0054] <6. Effects> As explained above, the motor control device 80 of this embodiment detects when the parking lock system 2 is released from its locked state and generates an active damping torque in the opposite direction to the rotational vibration of the drive motor 10 based on the rotational speed of the drive motor 10. Therefore, even when the locking state is released while the rotational torque is directed to the locking wheel 41 during parking of the electric vehicle, the rotational vibration of the rotor 13 and motor shaft 15 of the drive motor 10 is suppressed, reducing the impact applied to the engagement portion of the locking wheel 41 of the parking lock system 2 and the locking pawl 44 of the parking operating lever 43. Consequently, wear on the engagement portion of the locking wheel 41 and the locking pawl 44 of the parking operating lever 43 is reduced, improving the durability of the parking lock system 2.

[0055] Furthermore, the motor control device 80 described in this embodiment acquires information about the road surface tilt and performs active damping control when the tilt of the electric vehicle in the longitudinal direction exceeds a predetermined threshold. Therefore, when the rotational torque guided to the locking wheel 41 is small when the electric vehicle is parked, and when the rotational vibration of the rotor 13 and motor shaft 15 of the drive motor 10 is small when the locking state is released, the execution of active damping control is stopped, thereby reducing the load and power consumption of the motor control device 80.

[0056] The above is with reference to the appendix. Figure 1 The preferred embodiments of the present invention have been described in detail, but the present invention is not limited to such examples. It should be understood that, obviously, anyone with ordinary knowledge in the art to which this invention pertains will be able to conceive of various modifications or alterations within the scope of the technical concept set forth in the claims, and these, of course, also fall within the technical scope of this invention.

[0057] Explanation of reference numerals in the attached figures 1: Drive System 2: Parking Locking System 3: Gear position sensor 10: Drive motor 15: Motor shaft 17: Speed ​​sensor 19: Inverter 20: Gearbox 41: Locking wheel 42: Card-connecting part 43: Parking lever 44: Locking claw 45: Actuator 46: Cam 50: Parking lock control device 80: Motor control device 83: Parking Lock Release Determination Department 85: Rotational Speed ​​Determination Unit 87: Active damping control unit.

Claims

1. A motor control device (80) for controlling a drive motor (10) of an electric vehicle, the electric vehicle having a parking lock system (2) that keeps the wheels (35a, 35b) in a non-rotating state when parked. The motor control device (80) is characterized in that, The locking status of the aforementioned parking locking system (2) is detected when it is released; Based on the rotational speed of the aforementioned drive motor (10), an active damping torque is generated in the opposite direction to the rotational vibration of the aforementioned drive motor (10).

2. The motor control device as described in claim 1, characterized in that, Obtain information about the slope of the road surface; When the tilt of the aforementioned electric vehicle in the longitudinal direction exceeds a predetermined threshold, control that generates the aforementioned active damping torque is executed.

3. The motor control device as described in claim 1, characterized in that, The locking wheel (41) of the aforementioned parking locking system (2) is located on the motor shaft (15) of the aforementioned drive motor (10).

4. A motor control method for controlling a drive motor (10) of an electric vehicle, the electric vehicle having a parking lock system (2) that keeps the wheels (35a, 35b) in a non-rotating state when parked. The motor control method is characterized in that... Perform the following actions: The locking status of the aforementioned parking locking system (2) is detected when it is released; Based on the rotational speed of the aforementioned drive motor (10), an active damping torque is generated in the opposite direction to the rotational vibration of the aforementioned drive motor (10).

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