Motor Output Torque Estimation Using a Luenberger Observer
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Solution Overview
Problem
Existing methods for obtaining the actual output torque of a motor in new energy vehicles are ineffective, complex, or inaccurate, particularly in controlling three-phase permanent-magnet synchronous motors and induction motors.
Innovation Solution
A method involving the collection of motor parameters such as rotation speed, current, and flux linkage, followed by inputting these into a preset status observer, specifically a Luenberger observer, to determine the actual output torque accurately and efficiently, without additional parameter collection modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor sampling method is used to obtain actual output torque, then measurement can be implemented, but additional parameter collection modules and sensors are required, increasing device complexity and cost
Solution Approach 1:
The motor controller utilizes its own existing sampling modules to collect rotation speed and current parameters, and through internal calculation obtains flux linkage and electromagnetic torque. This self-service approach eliminates the need for additional external sensors or parameter collection modules, reducing device complexity while maintaining measurement capability
Solution Approach 2:
The patent introduces a status observer as an intermediary computational module that processes readily available parameters (rotation speed and electromagnetic torque) to derive the actual output torque. This intermediary approach allows accurate torque measurement without direct physical sensing, avoiding additional hardware complexity
2Ease of manufacture
If power balancing or flux linkage estimating methods are used, then torque calculation can be performed, but accuracy is insufficient for reliable control and protection
Solution Approach 1:
The status observer implements a feedback mechanism where the estimated actual output torque is continuously refined by comparing system state predictions with actual measurements. This feedback loop significantly improves measurement precision compared to open-loop estimation methods like power balancing or basic flux linkage estimation
Solution Approach 2:
The patent replaces direct mechanical torque sensing with an electrical parameter-based computational approach. By substituting physical torque sensors with electrical measurements (current, voltage, flux linkage) and mathematical modeling (status observer), the system achieves high accuracy while simplifying the physical measurement system
3Measurement precision
If additional parameter collection modules are added to obtain accurate torque, then measurement accuracy improves, but device complexity and cost increase
Solution Approach 1:
The existing sampling modules in the motor controller are made multi-functional, serving both their original purposes and the additional function of collecting parameters for torque calculation. This universality eliminates the need for dedicated torque measurement hardware, maintaining accuracy while avoiding complexity multiplication
Solution Approach 2:
Instead of directly measuring actual output torque with additional sensors, the system creates a computational copy of the torque value through the status observer. This virtual copy is derived from existing electrical parameters and provides the same measurement function without additional physical hardware
Data Source
AI summary
Embodiments of this application provide a torque obtaining method and device, a motor controller, and a readable storage medium. The torque obtaining method includes: obtaining a rotation speed of a motor; obtaining a current of the motor; obtaining a flux linkage of the motor; determining an electromagnetic torque of the motor based on the current and the flux linkage; and inputting the rotation speed and the electromagnetic torque into a preset status observer, and obtaining an observed value of an actual output torque of the motor, where the observed value is output by the status observer. The obtaining method is intended to obtain the actual output torque effectively, simply, and accurately.