EV Regenerative Braking Control for Towing Load Deceleration
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Solution Overview
Problem
Existing electric vehicle control methods fail to accurately adjust motor torque when the total mass of the vehicle changes, leading to longer stop distances and potential acceleration vibrations during deceleration.
Innovation Solution
A control method for electric vehicles that acquires the total mass, estimates disturbance torque, and adjusts motor torque based on a calculated torque command value, converging it to the disturbance torque as the vehicle slows, using regenerative braking to ensure smooth deceleration and maintain a stopped state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If stop control is executed based on vehicle body speed estimated by transmission characteristic from motor rotation velocity, then smooth deceleration without acceleration vibration can be realized, but stop distance becomes longer than expected when total mass of the vehicle changes
Solution Approach 1:
The control device dynamically adjusts the transmission characteristic parameters based on the actual total mass of the vehicle. When the total mass changes (e.g., due to load capacity increase or trailer tow), the system updates the transmission characteristic from motor rotation velocity to vehicle body speed to match the actual vehicle conditions, thereby maintaining accurate stop distance control while preserving smooth deceleration performance
Solution Approach 2:
The system changes the parameters of the transmission characteristic model according to the detected total mass of the vehicle. By adjusting the transmission characteristic parameters to reflect the actual vehicle mass, the control device ensures that the estimated vehicle body speed accurately corresponds to the motor rotation velocity, preventing excessive stop distance while maintaining smooth deceleration without acceleration vibration
2Device complexity
If torque command value is calculated based on fixed transmission characteristic, then control simplicity is maintained, but accuracy deteriorates when vehicle mass changes
Solution Approach 1:
The transmission characteristic parameters are adjusted based on the detected total mass of the vehicle. This parameter adaptation allows the system to maintain accurate speed estimation and torque control without requiring a completely different control architecture, thus balancing control simplicity with measurement precision
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
This approach allows for precise control of motor torque, reducing stop distances and preventing acceleration vibrations, ensuring smooth deceleration on various road gradients without lengthening stop times even when the vehicle's mass changes.
Implementation Method 1
deceleration is performed by a regenerative braking force of the motor
Implementation Method 2
converging the torque command value to the disturbance torque as an estimated vehicle body speed decreases
Data Source
AI summary
A control method for an electric vehicle in which a motor is used as a traveling drive source and deceleration is performed by a regenerative braking force of the motor, the electric vehicle including a towing unit configured to tow a separate object, the method including: acquiring an accelerator operation amount; acquiring a total mass of the electric vehicle; estimating a disturbance torque acting on the electric vehicle; acquiring an angular velocity of a rotary body; estimating a vehicle body speed of the electric vehicle; calculating a torque command value for the motor; measuring a load applied to the towing unit; correcting the total mass of the electric vehicle based on the measured load applied to the towing unit and the torque command value; controlling a torque generated in the motor based on the torque command value; and converging the torque command value to the disturbance torque.