EV Drive Force Control for Motor Overheat and Torque Stability
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Solution Overview
Problem
Existing drive force control systems for electric vehicles fail to prevent motor temperature rise and maintain running stability when motor temperatures reach restrictive levels, leading to abrupt torque distribution deviations and reduced stability.
Innovation Solution
A drive force control system with a controller that sets upper and restrictive torque limits based on motor temperatures, adjusting torque distribution between front and rear wheels to maintain stability and prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the torque of the rear motor is reduced to the limit torque when the temperature reaches the restrictive temperature, then the motor temperature is protected, but the distribution ratio of torque to front wheel and rear wheel deviates abruptly from the target torque distribution ratio, reducing running stability
Solution Approach 1:
The control device determines an upper limit torque before the motor temperature reaches the restrictive temperature. When the temperature reaches a predetermined level but is still below the restrictive temperature, the torque is limited to this upper limit value, preventing the temperature from rising further while avoiding abrupt torque changes that would affect running stability.
Solution Approach 2:
The control device dynamically adjusts the upper limit torque based on the actual motor temperature. As the temperature changes, the upper limit torque is recalculated and adjusted accordingly, creating a dynamic control system that responds to temperature variations while maintaining smooth torque transitions and preserving running stability.
2Power
If the torque of the front motor is increased to compensate for the reduced rear motor torque, then the required driving torque is maintained, but the torque distribution ratio deviates significantly from the target ratio, reducing running stability
Solution Approach 1:
The control device combines the temperature monitoring function with the torque control function into a unified control strategy. By integrating these functions, the system simultaneously manages motor temperature protection and torque distribution, ensuring that torque adjustments for temperature control do not compromise running stability.
Solution Approach 2:
The control device continuously monitors motor temperature and uses this feedback to adjust the upper limit torque in real-time. This closed-loop control ensures that torque adjustments are made based on actual temperature conditions, preventing both overheating and abrupt torque changes that would affect running stability.
3Reliability
If the torque is abruptly changed when motor temperature reaches restrictive levels, then motor protection is achieved, but running stability is reduced due to significant deviation from target torque distribution
Solution Approach 1:
The control device establishes an upper limit torque before the motor temperature reaches the restrictive temperature. This preliminary action prevents the temperature from reaching dangerous levels while avoiding abrupt torque changes, thereby protecting the motor without compromising running stability.
Solution Approach 2:
The control device creates a buffer zone by setting an upper limit torque that prevents the motor temperature from reaching the restrictive temperature. This cushioning effect allows for gradual temperature management and smooth torque transitions, protecting the motor while maintaining running stability.
Data Source
AI summary
A drive force control system for an electric vehicle configured to prevent a temperature rise in a motor to a restrictive temperature, and to ensure running stability of the electric vehicle when the temperature of the motor reaches the restrictive temperature. The control system comprises: an upper limit torque determiner that employs a torque of the first motor as an upper limit torque when a temperature of the first motor reaches a first predetermined temperature, in a case that the temperature of the first motor is higher than a first predetermined temperature but lower than a first restrictive temperature; a restrictive torque determiner that employs a first limit torque as the upper limit torque of the first motor, in a case that the temperature of the first motor reaches the first restrictive temperature; and a target torque determiner configured to determine a torque of another prime mover based on the upper limit torque of the first motor and a target torque ratio between the front wheel and the rear wheel.