Electric Motor Torque Control Under Diverging Current Error
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Solution Overview
Problem
Existing electric motor vehicle control systems face the risk of losing control due to unattainable target electric currents, leading to potential safety hazards and inconvenience, as they are calibrated for maximized performance without considering variability in operating conditions.
Innovation Solution
A control process that determines a target torque, associates it with control targets, acquires feedback signals, and adjusts to a safety target torque when error divergence is detected, using a proportional-integrative control law to induce convergence and replace the error with a safety error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the target torque is maximized according to the characteristic curve for improved performance, then the motor vehicle performance is improved, but the error between actual and target current may diverge leading to loss of control
Solution Approach 1:
The control system dynamically adjusts the target torque based on real-time monitoring of current error convergence. When error divergence is detected, the system transitions from maximum performance mode to a reduced torque mode, making the control target adaptive to actual system conditions rather than fixed according to the characteristic curve
Solution Approach 2:
The system implements feedback by continuously monitoring the error between actual and target current during closed-loop control. This feedback mechanism detects when the error begins to diverge and triggers a response (reducing target torque) to restore control stability, creating a closed-loop safety mechanism
2Reliability
If speed limiter or stop is inserted to ensure safety when error diverges, then the safety is improved, but the convenience and productivity are significantly reduced
Solution Approach 1:
Instead of applying the extreme measure of stopping or speed limiting, the system applies a partial action by reducing the target torque to a lower but still functional level. This partial reduction is sufficient to restore error convergence and maintain control while allowing the vehicle to continue operating without interruption
Solution Approach 2:
The system prepares a reduced target torque value in advance as a safety cushion. When error divergence is detected, this pre-prepared alternative control target is immediately activated, providing a smooth transition that prevents complete loss of control without requiring abrupt stopping or speed limiting
Data Source
AI summary
A process for controlling an electric motor is disclosed. The process includes determining a target torque to be delivered by the electric motor, associating the target torque with a control target for a control input of the electric motor according to a mapping between the target torque and the control target, acquiring a feedback signal of the control input, controlling the electric motor with an error between the feedback signal and the control target, identifying a critical condition where the error diverges, determining a safety control target corresponding to a safety target torque according to the mapping, where the safety target torque is reduced relative to the target torque, and replacing the error when the critical condition is identified with a safety error between the feedback signal and the safety control target.