Dual-Motor EV Drive Switching with Torque Shock Compensation
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Solution Overview
Problem
Existing electric vehicle control systems experience torque discontinuity when switching between driving states, leading to unpleasant torque shocks for the driver.
Innovation Solution
The electric vehicle control method employs two drive motors, with drive control switching based on required drive force. A torque fluctuation amount is calculated based on the rotation speed of the second motor during switching control, and the first torque command value is corrected accordingly to mitigate torque discontinuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If switching control is performed by disconnecting the clutch on the stopped motor side, then drive force switching between front-wheel drive and rear-wheel drive is achieved, but torque discontinuity is generated causing uncomfortable torque shocks
Solution Approach 1:
The control device calculates the torque fluctuation amount that will occur during clutch switching in advance, and corrects the torque command value of the other motor before switching occurs. This preliminary correction prevents torque discontinuity by ensuring the total torque remains constant during the transition.
Solution Approach 2:
When one motor stops and its clutch disconnects, the other motor's torque command value is increased by the calculated torque fluctuation amount. This compensatory increase counterbalances the torque loss from the disconnecting clutch, maintaining smooth total torque delivery to the drive wheels.
2Loss of energy
If one motor is stopped to reduce energy consumption, then energy efficiency is improved, but torque discontinuity occurs during switching
Solution Approach 1:
Before stopping one motor to save energy, the control device calculates the torque fluctuation that will occur and pre-adjusts the torque command value of the remaining motor. This ensures that when the clutch disconnects, the other motor is already prepared to compensate, preventing torque shocks while enabling energy-efficient single-motor operation.
Solution Approach 2:
The control device dynamically adjusts the torque command value parameter of the operating motor based on the rotation speed of the stopped motor and the calculated torque fluctuation amount. This parameter correction ensures smooth torque transition during switching between single-motor and dual-motor operation modes.
Data Source
AI summary
An electric vehicle control method including using a first motor and a second motor as travel drive sources, performing drive control on the first motor by transmitting a first torque command value to a first inverter, and performing drive control on the second motor by transmitting a second torque command value to a second inverter, and performing switching control of switching, based on a required drive force, the drive control on the second motor by the second inverter between an ON state in which the drive control is performed and an OFF state in which the drive control is stopped, wherein a torque fluctuation amount generated in the second motor during the switching control is calculated based on a rotation speed of the second motor, and the first torque command value is corrected based on the torque fluctuation amount.