Regenerative Braking Torque Control for Electric Vehicle Vibration
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Solution Overview
Problem
Existing regenerative brake control systems for electric vehicles often generate vibration in the longitudinal direction of the vehicle body when decelerating, particularly when the regenerative braking force is set high, leading to an uncomfortable stopping experience.
Innovation Solution
A control device for electric motor vehicles that detects the accelerator operation amount and estimates the disturbance torque unrelated to the gradient, correcting this torque value to smoothly decelerate the vehicle by converging the motor torque command to the corrected disturbance torque as the vehicle approaches a stop, thereby reducing longitudinal vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a large regenerative braking force is set, then the deceleration performance is improved, but vibration in the longitudinal direction of the vehicle body is generated when the vehicle speed becomes 0
Solution Approach 1:
The patent applies dynamics by making the regenerative braking force variable rather than constant. The control device dynamically adjusts the regenerative braking force based on real-time vehicle speed detection, transitioning from a larger force during deceleration to a smaller force near stop, thereby resolving the contradiction between deceleration performance and vibration suppression
Solution Approach 2:
The patent changes the parameter of regenerative braking force magnitude based on vehicle speed conditions. By detecting vehicle speed and adjusting the braking force parameter accordingly (larger during deceleration, smaller near stop), the system achieves both good deceleration performance and reduced longitudinal vibration at low speeds
2Loss of energy
If the regenerative braking force is maintained at a high level until stop, then the energy recovery efficiency is improved, but the vehicle produces oscillation and discontinuous negative acceleration at the moment of stopping
Solution Approach 1:
The patent applies preliminary action by preparing to reduce the regenerative braking force before the vehicle comes to a complete stop. The control device detects when vehicle speed approaches zero and proactively adjusts the braking force downward, preventing oscillation and discontinuous negative acceleration while still maximizing energy recovery during the main deceleration phase
Solution Approach 2:
The patent uses feedback by continuously detecting vehicle speed and using this information to adjust the regenerative braking force. The control device monitors the deceleration process in real-time and modifies the braking force based on the detected vehicle state, ensuring smooth deceleration and preventing stop-related oscillations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively minimizes the generation of vibration during regenerative braking, ensuring a smooth deceleration process and maintaining the vehicle's stop state on various road gradients without oscillation, enhancing passenger comfort and vehicle stability.
Implementation Method 1
a regenerative brake control device for electric vehicles... regenerates the motor by a regenerative braking force
Implementation Method 2
the motor torque command value converges to the corrected disturbance torque estimated value in conjunction with the reduction of the rotation speed of the motor
Data Source
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AI summary
a control device for electric motor vehicle using the motor as the traveling driving source and configured to decelerate by a regenerative braking force from the motor detects the accelerator operation amount, calculates the disturbance torque estimated value, and detects or estimates the resistance component unrelated to the gradient from the vehicle state. The control device for electric motor vehicle corrects the disturbance torque estimated value according to the detected or estimated resistance component unrelated to the gradient. The motor is controlled on the basis of the motor torque command value. When the accelerator operation amount is equal to or less than the predetermined value and the electric motor vehicle is just before the stop of the vehicle, the motor torque command value converges to the corrected disturbance torque estimated value in conjunction with the reduction of the rotation speed of the motor.