Sensorless Motor Controller Axis Error Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing position sensor-less vector control methods for permanent magnet motors with large electric time constants experience restricted frequency estimation and excessive current generation during acceleration or deceleration, leading to reduced operation efficiency.
Innovation Solution
The method uses current command values instead of detected current values to estimate axis error, and generates a command value for axis error based on the speed command value, controlling the estimated frequency to reduce axis error to zero, thereby improving operational efficiency for both small and large electric time constant motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If detected current values are used to estimate axis error in position sensor-less vector control, then control operation is stable for motors with small electric time constant, but frequency estimation response is restricted for motors with large electric time constant
Solution Approach 1:
The patent changes the parameter used for axis error estimation from detected current values to current command values. This parameter substitution resolves the contradiction because current command values are available immediately without measurement delay, providing fast frequency estimation response for large electric time constant motors while maintaining control stability through the established estimation algorithm.
2Productivity
If speed command value is abruptly changed, then acceleration or deceleration operation is achieved, but excessive current is generated due to large axis error and operation efficiency is lowered
Solution Approach 1:
The patent implements feedback control by continuously estimating axis error using current command values and feeding this information back to correct frequency estimation. This feedback mechanism dynamically reduces axis error during acceleration and deceleration operations, preventing excessive current generation and maintaining high operation efficiency while achieving rapid speed changes.
Solution Approach 2:
The patent performs preliminary axis error estimation using current command values before excessive current can be generated. By having the estimation mechanism ready and using command values that are available in advance, the system can proactively correct axis error during acceleration or deceleration, preventing the harmful effect of excessive current rather than reacting after it occurs.
Data Source
AI summary
Current command values are used instead of detected current values to estimate axis error by calculation. An axis error command value is generated according to a speed command value, and a difference between the generated axis error command value and the estimated axis error value is used to control an estimated frequency value.