EV Brake Hold Control for Motor Overheat Prevention
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Solution Overview
Problem
In electric vehicles, continuous motor operation to hold the vehicle stationary can lead to increased component temperatures and potential faults, affecting performance and durability, and there is a need to secure the vehicle in such situations.
Innovation Solution
A control system monitors operating parameters of the electric motor and vehicle speed, actuating the brakes when thresholds are met, reducing motor input, and gradually releasing the brakes as motor torque increases to ensure smooth vehicle movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric motor is continuously actuated to hold the vehicle stationary, then the vehicle remains secured on hills or inclined surfaces, but the temperature of the motor and related components increases
Solution Approach 1:
The brake system acts as an intermediary mechanism to replace the electric motor in holding the vehicle stationary. When the vehicle is stopped on an incline, the brake system engages to maintain position, allowing the motor to remain inactive or reduce operation, thereby preventing overheating while maintaining vehicle security.
Solution Approach 2:
The system implements periodic or conditional switching between motor actuation and brake engagement based on operating parameters such as temperature thresholds and vehicle speed. When temperature exceeds a threshold or speed drops below a threshold, the system transitions from motor-based holding to brake-based holding, creating a periodic alternation that prevents continuous motor operation and overheating.
2Reliability
If the electric motor is continuously actuated to hold the vehicle stationary, then the vehicle remains secured, but energy consumption increases
Solution Approach 1:
The brake system serves as an energy-efficient intermediary for stationary vehicle holding. Instead of continuously consuming electrical energy to maintain motor actuation, the system engages the mechanically-actuated brake system to hold the vehicle, dramatically reducing energy consumption while maintaining the same security function.
Solution Approach 2:
The control system periodically evaluates energy consumption thresholds and switches between motor-based and brake-based holding modes. When energy consumption exceeds thresholds or the vehicle is stationary for extended periods, the system transitions to brake-based holding, creating periodic operation that optimizes energy usage while maintaining vehicle security.
3Speed
If the brake is suddenly released to permit vehicle movement, then the vehicle can accelerate quickly, but the transition from brake hold to motor propulsion becomes abrupt and affects driving dynamics
Solution Approach 1:
The brake release process is made dynamic and adjustable rather than fixed or sudden. The control system modulates the brake release rate based on vehicle conditions, motor torque availability, and driver intent, creating a smooth, adaptive transition that maintains good driving dynamics while enabling quick vehicle movement when needed.
Solution Approach 2:
The system uses feedback from vehicle speed sensors, motor torque sensors, and controller signals to continuously adjust the brake release process. By monitoring these parameters in real-time, the system can modulate brake force reduction to achieve smooth transitions, preventing abrupt changes that would degrade driving dynamics while still enabling rapid acceleration when required.
Data Source
AI summary
A method of control in a battery electric vehicle includes monitoring an operating parameter of an electric motor in a propulsion system of a vehicle, monitoring a speed of the vehicle, and actuating, by a vehicle controller, a brake of the vehicle when the operating parameter is beyond an operating parameter threshold and the speed is at or below a speed threshold.