Inverter Control Method for Motor Demagnetization Detection
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Solution Overview
Problem
Existing motor control systems face challenges in accurately determining demagnetization when the operating point of a motor varies, as conventional methods are not effective in such dynamic conditions.
Innovation Solution
The method involves specifying local maximum, local minimum, or average values of the torque voltage command value within the voltage command value as a determination target, comparing these values with a demagnetizing threshold, and determining demagnetization based on the comparison result.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional demagnetization detection methods are used, then the detection is simple, but the detection accuracy deteriorates when operating point varies
Solution Approach 1:
The patent applies dynamics by making the demagnetization detection method adaptive to changing operating conditions. Instead of using a fixed threshold, the system dynamically adjusts the detection criteria based on the current operating point (torque and speed conditions). The controller continuously monitors voltage command values and compares them against dynamically determined thresholds that account for operating point variations, enabling accurate demagnetization detection across different motor operating conditions.
Solution Approach 2:
The patent changes the detection parameters from fixed values to variable values that adapt to operating conditions. The system uses multiple voltage command values (Vq1, Vq2, Vq3) corresponding to different operating points and compares them against threshold values that are determined based on the relationship between torque and speed. This parameter adaptation allows the detection system to maintain accuracy across varying operating conditions.
2Measurement precision
If multiple voltage command values are monitored, then demagnetization detection accuracy improves, but system complexity increases
Solution Approach 1:
The patent segments the voltage command value monitoring into distinct components (Vq1, Vq2, Vq3) corresponding to different operating points or time intervals. Each segment is evaluated separately against appropriate thresholds, allowing the system to capture demagnetization effects under various conditions. This segmentation enables comprehensive monitoring without requiring a completely complex unified analysis system.
Solution Approach 2:
The system implements feedback by continuously monitoring voltage command values and using the results to determine demagnetization status. The controller compares monitored values against thresholds and adjusts its determination accordingly. This feedback mechanism allows accurate detection while maintaining manageable complexity through systematic evaluation of multiple parameters.
Data Source
AI summary
A control method of inverter for driving motor including a magnet, comprises detecting a rotation state of the motor by a rotation sensor, detecting current of the motor by a current sensor, calculating, based on a torque command value, a detection value of the rotation state detected by the rotation sensor, and detection current detected by the current sensor, a voltage command value for controlling a voltage of the motor by a controller for controlling the inverter, specifying a value of at least one of a local maximum value, a local minimum value, and an average value of the torque voltage command value included in the voltage command value as a torque determination target command value by the controller, comparing a demagnetizing determination threshold value with the torque determination target command value by the controller, and determining whether or not demagnetization of the magnet occurs in accordance with the compared result.