Electric Motor Controller Traction Control via Speed Estimation
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Solution Overview
Problem
Conventional electric vehicles face challenges in maintaining traction during braking and acceleration due to wheel slip and lock, which reduces energy efficiency and vehicle control, especially in regenerative braking systems, and existing solutions require complex sensing arrangements.
Innovation Solution
An electric motor controller system that uses torque demands, signals from a two-axis accelerometer, and motor speed to estimate vehicle speed, allowing for traction control without individual wheel speed sensing, and switches between closed and open loop modes to adjust torque demands and reduce traction loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking torque is increased to improve energy efficiency, then energy recovery increases, but wheel slip occurs causing loss of traction
Solution Approach 1:
The system continuously monitors wheel speed and compares it with estimated vehicle speed to detect slip conditions. When slip is detected, the control system provides feedback to adjust the regenerative braking torque, reducing it to prevent further slip while maximizing energy recovery within safe operating limits.
Solution Approach 2:
The regenerative braking torque is made dynamically adjustable based on real-time traction conditions. The system transitions between different torque levels depending on whether slip is detected, allowing optimal energy recovery when traction is good and preventing slip when torque becomes excessive.
2Measurement precision
If wheel speed sensors are installed on individual wheels to detect slip, then traction control precision improves, but device complexity increases
Solution Approach 1:
The system extracts the wheel speed sensing function from dedicated sensors and implements it through the existing motor controller's measurement capabilities. The motor controller already measures motor speed, and this measurement is used in conjunction with accelerometer data to estimate vehicle speed and detect slip without requiring separate wheel speed sensors.
Solution Approach 2:
The motor controller is designed to perform multiple functions: motor control, vehicle speed estimation, slip detection, and regenerative braking management. By making the controller universal, the system eliminates the need for separate dedicated sensors and control units, reducing overall device complexity while maintaining measurement precision.
3Adaptability or versatility
If sophisticated sensing systems are used to detect road conditions, then adaptation to different surfaces improves, but device complexity increases
Solution Approach 1:
The system uses data already being collected for motor control purposes (motor speed, torque demands) combined with accelerometer measurements to infer road conditions and slip characteristics. This self-service approach allows the system to adapt to different road surfaces without requiring additional specialized sensors for road condition detection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables effective traction control by reducing wheel slip and lock during acceleration and braking, enhancing energy efficiency and vehicle handling without the need for complex sensor systems, allowing for seamless integration into existing vehicles.
Implementation Method 1
signals from a two-axis accelerometer
Data Source
Figure 1
Figure 2
Figure 2
AI summary
An electric motor controller adapted to provide anti-lock braking of an electric traction motor for an electric vehicle is disclosed herein. The electric motor controller comprises a torque demand input for receiving a torque demand input signal based on a request from an operator of the electric vehicle and a torque demand adjuster adapted to adjust the torque demand input signal and to provide an adjusted torque demand signal. The torque demand adjuster is configured to adjust the torque demand signal such that the motor is controlled to reduce the difference between a motor speed and an estimated speed of the electric vehicle.