Motor Torque Shift Timing for Regenerative Braking Resonance
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Solution Overview
Problem
Existing vehicle systems experience shock due to torque fluctuation during regenerative driving in resonance regions, particularly in high-torque electric vehicles and low-speed conditions, leading to discomfort in ride quality.
Innovation Solution
A vehicle system with a control unit that predicts the rotation speed of electric motors and determines the start time for shifting torque to a predetermined limit value, implementing gentle torque limiting and compensation to avoid sudden changes in torque, thereby reducing vibrations and noise in resonance frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If torque is rapidly changed by switching torque commands, then noise suppression is achieved, but ride comfort deteriorates due to shock
Solution Approach 1:
The control unit predicts the future rotation speed of the motor and determines the start time of shift control based on this prediction. By acting in advance before the motor enters the resonance region, the system smoothly transitions torque before noise becomes problematic, avoiding both noise and shock.
Solution Approach 2:
The control system uses feedback from the current rotation speed and torque state to predict future conditions and adjust torque commands accordingly. This closed-loop control ensures that torque changes are optimized for both noise suppression and ride comfort based on real-time motor state.
Data Source
AI summary
A vehicle system includes: a plurality of drive sources that generate torque for braking and driving a drive wheel of a vehicle; and a control unit that controls the torque. At least one of the drive sources is an electric motor, and the control unit predicts a rotation speed of the electric motor after a current rotation speed, and determines, based on the predicted rotation speed, a start time of shift control for changing the torque to a predetermined torque limit value.