Method for operating an electric vehicle and control device for an electric vehicle
By monitoring motor speed and torque and optimizing tire torque, the problem of wheel lock-up in the electric vehicle recycling function has been solved, achieving efficient recycling and stable control of electric vehicles and improving range.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2024-10-08
- Publication Date
- 2026-05-12
AI Technical Summary
In the recycling function of electric vehicles, the wheels are prone to lock up when the road surface is slippery, and existing technologies are difficult to effectively prevent or reduce the probability of lockup.
By monitoring the motor's speed and torque, the tire torque is optimized. The motor's inverter control device independently prevents or reduces wheel lock-up. The motor speed and torque measurement parameters are used, and the motor speed and torque are adjusted in combination with preset conditions to maintain the tire torque under non-lock-up conditions, thus avoiding premature shutdown of the regenerative torque.
It enables the accurate maintenance of preset recovery torque in the electric vehicle regeneration function, preventing or reducing wheel lock-up, improving driving range, and simplifying communication of the vehicle stability system.
Smart Images
Figure CN122029073A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for operating an electric vehicle and a control device for an electric vehicle. Background Technology
[0002] Regenerative braking can be implemented when an electric vehicle is in operation. If the driver releases the accelerator pedal and does not operate the brake pedal, the vehicle can decelerate via the electric drive system. This regenerative braking function is implemented and controlled within the vehicle's computing unit. This unit reads the accelerator pedal position and sends a target torque to the drive system's inverter. The maximum deceleration of the vehicle can be limited via regenerative braking through the vehicle computing unit and by setting the target torque. In wet road conditions, there is a possibility that the drive wheels may lock up when the tires can no longer transmit torque to the road surface.
[0003] Typically, regenerative braking in vehicles can be monitored using a vehicle stability system computing unit (ESP / ABS), which uses its own sensors to detect wheel lock-up. If a wheel is about to lock up during regenerative braking, the system sends a request to the vehicle computing unit or directly to the inverter to reduce or completely shut down the regenerative torque.
[0004] The drive system of an all-wheel-drive vehicle is described in WO 2013 / 083243 A1. Summary of the Invention
[0005] The present invention provides a method for operating an electric vehicle according to claim 1 and a control device for an electric vehicle according to claim 8.
[0006] The present invention is based on the concept of describing a method for operating an electric vehicle and a control device for an electric vehicle, wherein the recovery operation can be monitored by a vehicle stability system computing device. For this purpose, the recovery function can independently prevent wheel lock-up, or at least reduce the probability of lock-up, wherein only the measured parameters of the motor speed and torque are required, thus the method can be implemented particularly simply in the inverter's computing device.
[0007] According to the present invention, in a method for operating an electric vehicle, it is determined whether regeneration operation is performed on the motor of the electric vehicle during a predetermined monitoring period; a target value of the regeneration torque on the motor is provided or determined by a control device; the rotational speed of the motor during regeneration operation is determined during the predetermined monitoring period; the torque of the motor during regeneration operation is determined during the predetermined monitoring period; the tire torque on at least one drive wheel of the electric vehicle is determined based on the rotational speed and torque of the motor during regeneration operation; the tire torque is optimized according to a preset process (and according to preset conditions), for example by preset setting values for adjusting the motor rotational speed, and the rotational speed and / or torque of the motor is adjusted accordingly, wherein the tire torque is kept outside of lock-up conditions of at least one drive wheel (e.g., changes in motor rotational speed related to changes in regeneration torque).
[0008] Advantageously, this method can achieve the preset or desired recovery torque as accurately as possible, while simultaneously preventing or at least reducing the probability of wheel lock-up.
[0009] According to a preferred embodiment of the method, the method is implemented on the control device of the motor inverter.
[0010] According to a preferred embodiment of the method, the target value of the maximum regenerative torque is preset by the driver. The driver can preset the maximum regenerative torque via the vehicle's computing unit. If wheel lock-up is possible, the maximum regenerative torque is limited by the control device.
[0011] According to a preferred embodiment of the method, the torque is maintained within a predetermined deviation from the target value of the recovered torque.
[0012] According to a preferred embodiment of the method, the tire torque is optimized such that the tire torque has a maximum value based on the wheel slippage of at least one drive wheel.
[0013] According to a preferred embodiment of the method, the tire torque is optimized to achieve a periodic increase and decrease in rotational speed.
[0014] According to a preferred embodiment of the method, the rotational speed is reduced until a state is reached in which subsequent changes in tire torque are reduced or remain constant due to the reduction in rotational speed, and in this case, the rotational speed is subsequently maintained or increased as long as the subsequent tire torque increases, otherwise the rotational speed is reduced again.
[0015] Advantageously, a predetermined adjustment strategy can be implemented to achieve a preset operating mode at a specific operating point.
[0016] According to the present invention, the control device is designed to perform the method according to the present invention.
[0017] According to a preferred embodiment of the control device, the control device is a control device for the inverter of an electric vehicle.
[0018] According to a preferred embodiment of the control device, the control device is connected to or includes a speed sensor and / or torque sensor of the motor.
[0019] The control device can also be characterized by combining the features and advantages mentioned in the method, and vice versa.
[0020] Therefore, the present invention relates to a method for regulating the rotational speed of a motor in an electric vehicle. Furthermore, this method advantageously detects the torque transmitted from the drive tire to the road surface based on existing or derived signals of the motor's torque and rotational speed. Additionally, tire torque can be evaluated and the target rotational speed for speed regulation can be changed so that the transmitted tire torque can reach its maximum value.
[0021] Using this invention, the premature shutdown of regenerative braking torque can be avoided or its probability reduced through the vehicle stability system. Furthermore, the vehicle's driving range can be increased because more energy can be fed back into the vehicle's battery by maintaining regeneration. Wheel lock-up during regeneration can be avoided or its probability reduced.
[0022] Advantageously, this method does not require the use of a vehicle reference speed, thus eliminating the need for wheel speed sensors or acceleration sensors, and therefore, the invention can be implemented inexpensively and simply. Furthermore, it enables simplified communication between the inverter, the vehicle computing unit, and the vehicle stability system.
[0023] For example, the present invention can be used in electric vehicles and hybrid vehicles, wherein there is a direct mechanical coupling between the motor and the drive wheels.
[0024] To achieve speed regulation itself, known methods such as PID control can be employed. When the output signal of the speed regulator, especially the target torque, is greater in absolute value than the predetermined and desired value of the regenerative torque of the vehicle's calculation unit, the target torque output of the speed regulator can be limited to the value calculated by the vehicle's calculation unit.
[0025] To detect wheel torque, the torque of the motor can be directly used, for example, taking into account the gear ratio of the transmission. This is acceptable in recycling because essentially only the driving torque of the motor and the circumferential force of the tire act on the wheel.
[0026] The rotational acceleration of the motor can be calculated using numerical differentiation. If more sophisticated filters are used, such as interference parameter observers, alternative detection of wheel torque can be achieved.
[0027] Further features and advantages of embodiments of the present invention will become apparent from the following description with reference to the accompanying drawings. Attached Figure Description
[0028] The invention will then be described in detail with the aid of embodiments illustrated in the accompanying drawings. Wherein:
[0029] Figure 1 A schematic diagram of a method for operating an electric vehicle according to an embodiment of the present invention is shown;
[0030] Figure 2 A schematic diagram of a method for operating an electric vehicle according to another embodiment of the present invention is shown;
[0031] Figure 3 A schematic diagram of a method for operating an electric vehicle according to another embodiment of the present invention is shown;
[0032] Figure 4 The time curve of the target speed is shown when using tire torque optimization; and
[0033] Figure 5 A block diagram illustrating the method steps of a method for operating an electric vehicle according to an embodiment of the present invention is shown.
[0034] In the accompanying drawings, the same reference numerals denote the same or functionally identical elements. Detailed Implementation
[0035] Figure 1 A schematic diagram of a method for operating an electric vehicle according to an embodiment of the present invention is shown.
[0036] according to Figure 1 In step H1, the motor speed can be determined using a speed sensor, and in step H2, the motor torque can be determined. Tire torque is then detected using the speed and torque in step H3. The tire torque can then be used in step H4, where optimization of the tire torque can be determined and / or set. Subsequently, the target speed associated with the optimized tire torque can be transmitted to the motor speed regulator in step H5. For comparison and to monitor and advantageously adhere to the deviation between the adjusted speed and the initial preset, the speed detected by the speed sensor in step H1 can also be transmitted to the speed regulator in step H5. Then, in step H6, the new target torque can be transmitted to the drive and vehicle, or, if this function is calculated in the inverter, it can be implemented directly by the inverter.
[0037] Figure 2 A schematic diagram of a method for operating an electric vehicle according to another embodiment of the present invention is shown.
[0038] according to Figure 2 After startup, in step M1, the target speed can be temporarily set to the actual speed currently present on the motor. If it is subsequently determined that the target speed should be reduced to change the tire torque (corresponding to step M2), this adjustment can be made, and in the subsequent step M3, wait until the adjustment sets a new target speed. Then, in the subsequent step M4, it can be checked whether the tire torque has increased, and if it has increased (yes), step M2 can be repeated using subsequent cycles M3 to M4. If the tire torque has not increased in step M4, the target speed can be increased or maintained in step M5, and wait in the subsequent step M6 until the adjustment sets a target speed. In the subsequent step M7, it can be checked whether the tire torque has increased, and if it has increased (yes), step M5 can be repeated; if not (no), step M2 can be repeated (using subsequent steps respectively).
[0039] Figure 2 The process of optimizing the target rotational speed is shown.
[0040] Tire torque optimization is achieved through dynamic adaptation to the target speed. When optimization is activated, the target speed is first set to the actual speed value. A separate curve then periodically switches between increasing and decreasing the target speed.
[0041] Figure 3 A schematic diagram of a method for operating an electric vehicle according to another embodiment of the present invention is shown.
[0042] Figure 3 The optimization of tire torque is illustrated. A curve showing the relationship between tire torque and slip on the drive wheel is shown. In step N1, the target speed can be reduced within a specific range, increasing slip and thus increasing tire torque. This may occur until the maximum value of tire torque is reached, i.e., the target speed is further reduced until then. If the target speed is further reduced within another range N2, the tire torque decreases with even greater slip because the maximum value of tire torque is exceeded. In another step / range N3, the target speed can be increased again, and the tire torque can be increased again, and the slip can be decreased until the maximum value of tire torque is reached again. In range N4, the maximum value of tire torque is exceeded again, and a further increase in the target speed reduces tire torque again, after which step N1 can be performed. Here, the important switching condition is the detected response of tire torque to changes in the target speed.
[0043] Figure 4 The time curve of the target speed is shown when using tire torque optimization.
[0044] Figure 4An exemplary curve of the target rotational speed versus time is shown in the method according to the invention, during the optimization of tire torque.
[0045] The shape of the speed curve can largely depend on how the target speed increment is chosen. Figure 3 The increment can be selected such that, depending on the optimized operating state, the increment can lead to an increase or decrease in wheel slippage.
[0046] Figure 5 A block diagram illustrating the method steps of a method for operating an electric vehicle according to an embodiment of the present invention is shown.
[0047] In this method, S1 determines whether regeneration operation is performed on the motor of the electric vehicle during a predetermined monitoring period; S2 provides or determines a target value of the regeneration torque on the motor; S3 determines the rotational speed of the motor during regeneration operation during the predetermined monitoring period; S4 determines the torque of the motor during regeneration operation during the predetermined monitoring period; S5 determines the tire torque on at least one drive wheel of the electric vehicle based on the rotational speed and torque of the motor during regeneration operation; S6 optimizes the tire torque according to a preset process, and adjusts the rotational speed and / or torque of the motor based on this, wherein the tire torque is kept outside the lock-up condition of at least one drive wheel.
[0048] Although the present invention has been fully described above with reference to preferred embodiments, the present invention is not limited thereto, but can be modified in various ways and methods.
Claims
1. A method for operating an electric vehicle (10), comprising the steps of: - Determine (S1) whether recycling operation is performed on the motor of the electric vehicle during the predetermined monitoring period; - Provide (S2) or obtain the target value of the regenerative torque on the motor; - Determine (S3) the rotational speed of the motor during the recycling operation during the predetermined monitoring time period; - Calculate (S4) the torque of the motor during the recycling operation during the predetermined monitoring time period; - Calculate (S5) the tire torque on at least one drive wheel of the electric vehicle based on the rotational speed and torque of the motor during the recycling operation; - The tire torque is optimized according to a preset process (S6), and the speed and / or torque of the motor are adjusted accordingly (S7), wherein the tire torque is kept outside the lock-up condition of the at least one drive wheel.
2. The method according to claim 1, wherein the method is implemented on the control device of the inverter of the motor.
3. The method according to claim 1 or 2, wherein, The target value of the recovered torque is preset by the driver.
4. The method according to any one of claims 1 to 3, wherein, The torque is maintained within a predetermined deviation from the target value of the recovered torque.
5. The method according to any one of claims 1 to 4, wherein, The tire torque is optimized such that the tire torque has a maximum value based on the wheel slip of the at least one drive wheel.
6. The method according to claim 5, wherein, The tire torque is optimized to achieve a periodic increase and decrease in the rotational speed.
7. The method according to claim 6, wherein, The rotational speed is reduced until a state is reached in which subsequent changes in tire torque are reduced or remain constant due to the reduction in rotational speed, and in this state, the rotational speed is subsequently maintained or increased whenever the subsequent tire torque increases; otherwise, the rotational speed is reduced again.
8. A control device (SE) for an electric vehicle, the control device being designed to perform the method according to any one of claims 1 to 7.
9. The control device (SE) according to claim 8, wherein the control device is a control device for the inverter of the electric vehicle.
10. The control device (SE) according to claim 8 or 9, wherein the control device is connected to or includes the speed sensor and / or torque sensor of the motor.