Electric Motor Torque Control for Wheel Stability
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Solution Overview
Problem
Wheel stability control systems in electric vehicles face limitations due to inaccurate sensor information, leading to underperformance in maintaining traction and preventing wheel spin, especially during acceleration and deceleration.
Innovation Solution
A wheel stability control system that determines the angular speed of the electric motor, calculates the electrical moment, and adjusts the power delivery to maintain optimal acceleration and deceleration based on preloaded optimal curves, eliminating the need for a wheel angular speed sensor and enhancing traction control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wheel stability control systems use traditional wheel angular speed sensors to determine vehicle behavior, then the system can detect wheel speed, but the information becomes inaccurate when wheels lose traction, leading to underperformance in maintaining traction and preventing wheel spin
Solution Approach 1:
The patent introduces an intermediary calculation method that uses motor parameters (angular speed, input current, input voltage, phase angle) as a mediator to determine vehicle speed and acceleration. This intermediary approach bypasses the unreliable wheel speed sensor data during traction loss, allowing the control system to maintain accurate vehicle state information even when wheels spin or lose grip on the road surface.
Solution Approach 2:
The patent replaces the mechanical sensor-based measurement system with an electrical calculation system. Instead of relying on mechanical wheel speed sensors that directly contact the wheels, the system uses electrical parameters from the motor control system to calculate vehicle speed and acceleration through mathematical relationships, thereby eliminating the source of measurement inaccuracy during traction loss.
2Reliability
If the system adjusts electrical moment to maintain optimal acceleration and deceleration, then wheel stability and traction are improved, but the complexity of power management increases
Solution Approach 1:
The patent makes the power system multi-functional by having the electrical moment calculation serve multiple purposes: it determines vehicle acceleration, compares against optimal values from lookup tables, and controls motor power delivery all within the same control framework. This universal approach consolidates what could be separate complex systems into a unified control algorithm, reducing overall system complexity while maintaining wheel stability.
Solution Approach 2:
The patent implements preliminary action by pre-calculating and storing optimal acceleration and deceleration values in lookup tables during system initialization. This allows the real-time control system to simply compare current motor acceleration against pre-determined optimal values rather than performing complex optimization calculations during dynamic driving conditions, significantly reducing computational complexity while maintaining stability control effectiveness.
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 solution provides accurate vehicle speed determination and optimal power management, ensuring high-performance acceleration and deceleration while maintaining road traction, thereby preventing wheel spin and instability.
Implementation Method 1
A power system including an electric motor and a drive inverter determines the angular speed, the input current, the input voltage, and a phase angle between the input current and the input voltage for the electric motor
Implementation Method 2
Additional mechanical torque is applied by the hydraulic braking system
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
A wheel stability control system for an electric vehicle including an electric motor, a drive inverter, and an electronic control unit (ECU) including a computer readable, non-transitory memory (memory) and an electronic processing unit (EPU). The memory stores information including an optimal acceleration and deceleration curve and the electrical characteristics of the electric motor. The EPU calculates the electrical moment of the electric motor from inputs from the drive inverter and the electrical characteristics of the electric motor. The ECU compares the electrical moment and the angular speed of the motor with the optimal acceleration and deceleration curve, and if the acceleration or deceleration of the electric motor is out of a predetermined range when compared to the optimal acceleration and the optimal deceleration, it reduces the electrical moment applied by the electric motor.