Electric Vehicle Motor Torque Control for Backlash Vibration Suppression
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Solution Overview
Problem
Existing control devices for electric vehicles face challenges in effectively suppressing vibrations caused by backlash and resonance, particularly when the torque is zero, leading to inadequate vibration suppression and potential promotion of vibrations.
Innovation Solution
A control device for electric vehicles that adjusts the torque generated by the motor based on rotational torque commands and vibration suppression control torque commands, with a vibration suppression control gain calculation unit that reduces the torque when specific conditions are met, such as vehicle stop or shift range changes, to prevent vibration promotion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If vibration suppression control torque is always applied to rotational variation of motor, then vibration component caused by resonance is suppressed, but when torque is almost zero, vibration caused by backlash is promoted rather than suppressed
Solution Approach 1:
The patent applies dynamics by making the vibration suppression control torque dynamic rather than static. The control torque is adjusted based on the magnitude of the torque command value - using full suppression torque when torque is large, and reducing or eliminating suppression torque when torque is small. This dynamic adjustment prevents the promotion of backlash vibrations at low torque conditions while maintaining resonance suppression at high torque conditions.
Solution Approach 2:
The patent changes the parameter of vibration suppression control torque based on the torque command value magnitude. When the torque command value is small (below a predetermined threshold), the vibration suppression control torque is reduced or set to zero. When the torque command value is large, the full vibration suppression control torque is applied. This parameter change resolves the contradiction by adapting the suppression torque to the operating condition.
2Stability of the object's composition
If restriction is imposed on vibration component suppression torque, then stabilization of control is achieved, but appropriate vibration suppression torque cannot be applied when vibration caused by backlash is generated
Solution Approach 1:
The patent makes the vibration suppression control dynamic by adjusting the suppression torque based on real-time torque command values. Instead of imposing a fixed restriction, the system dynamically determines the appropriate suppression level - applying full suppression when needed for stability and reducing suppression when torque is small to avoid promoting backlash vibrations. This dynamic approach maintains control stability while preventing vibration promotion.
3Reliability
If torque is reduced when predetermined condition is satisfied, then vibration promotion is prevented, but vibration suppression control may be insufficient during normal operation
Solution Approach 1:
The patent applies local quality by differentiating the vibration suppression control based on the local condition of torque magnitude. Instead of applying uniform suppression control across all operating conditions, the system applies different levels of suppression - full suppression when torque is large (normal operation), and reduced or zero suppression when torque is small (low-load condition). This localized approach ensures appropriate vibration control for each operating regime.
Data Source
AI summary
Provided are a control device for an electric vehicle and a control method for an electric vehicle capable of appropriately suppressing a vibration. In the control device for an electric vehicle according to the present invention, when a torque is controlled that is generated by a motor configured to generate a torque for braking or driving a drive wheel via a speed reduction mechanism and a drive shaft coupled to the speed reduction mechanism, the torque generated by the motor is controlled based on a rotational torque command value based on an accelerator operation or a brake operation by a driver, and a vibration suppression control torque command value for suppressing a vibration component caused by a resonance of the vehicle. Then, when a predetermined condition is satisfied, the torque generated by the motor is reduced.