Electric Drive Creep Control With Brake-Release Torque Feedback
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Solution Overview
Problem
Direct-drive electric vehicles face inefficiencies when operating at low speeds due to the lack of precise control over driveline torque, leading to unstable speed control and potential engine stalling, especially in parking or maneuvering situations.
Innovation Solution
A system comprising a motor and a brake mechanism with a controller that adjusts output torque based on the brake mechanism's state, allowing for gradual vehicle movement when the brake is released, thereby enabling precise control over vehicle speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a direct-drive electric vehicle operates at very low speeds and loads, then the vehicle can maneuver in parking or low speed situations, but the operation becomes extremely inefficient
Solution Approach 1:
The system dynamically changes the motor's operating parameters (torque and speed) based on vehicle conditions. By implementing a speed governor that adjusts torque output according to vehicle speed, the system ensures the motor operates in its efficient range even during low-speed maneuvers, thereby maintaining operational efficiency while enabling low-speed maneuverability
2Ease of operation
If the brake mechanism is released to allow vehicle movement, then the vehicle can move forward or backward, but the lack of torque control causes the vehicle to move faster than desired
Solution Approach 1:
The system implements a feedback control mechanism where the controller continuously monitors vehicle speed and adjusts the motor torque accordingly. When the brake is released, the speed governor receives speed feedback and automatically modulates the torque to maintain the desired slow movement, preventing the vehicle from moving faster than intended
Solution Approach 2:
The system dynamically adjusts the torque output based on real-time vehicle conditions. The speed governor continuously modifies the torque parameter in response to changing vehicle speed, transforming the static brake-release action into a dynamically controlled movement process that maintains precise speed control
3Force
If the motor provides sufficient torque for vehicle movement, then the vehicle can overcome resistance and move, but the speed control becomes unstable at low speeds
Solution Approach 1:
The speed governor implements a feedback control system that continuously monitors vehicle speed and adjusts torque output to maintain stability. By comparing actual speed with target speed and dynamically adjusting torque in response to deviations, the system achieves both sufficient force for movement and stable speed control at low speeds
Data Source
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AI summary
Systems and methods to control the vehicle speed of a vehicle includes a controller communicatively coupled to a motor and a brake mechanism. The controller is structured to receive an indication of a desired change in the vehicle speed, activate a motor speed governor responsive to the brake mechanism being in a released state, adjust an output torque responsive to the vehicle speed, wherein as a load corresponding to the motor increases the vehicle speed decreases.