IPMSM Rotor Polarity Detection During Resolver Offset Calibration
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Solution Overview
Problem
Current methods for determining the polarity of a rotor in interior permanent magnet synchronous motors during resolver offset calibration are prone to errors due to harmonics, spikes, and noise, which can lead to incorrect position feedback and safety risks.
Innovation Solution
A method that involves obtaining an estimated d-axis current based on an alternating voltage signal, determining maximum and minimum values over time periods, and integrating only those values that meet a defined condition to robustly determine the rotor polarity, thereby reducing the impact of noise and inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the maximum and minimum values of d-axis current are used to determine rotor polarity, then the polarity determination can be performed, but the result is unreliable due to harmonics, spikes, and noise in the measured current
Solution Approach 1:
The measurement process is divided into multiple time periods, and the polarity determination is based on aggregated results from multiple measurements rather than a single measurement. This segmentation approach allows filtering out transient errors and noise by comparing multiple independent measurements.
Solution Approach 2:
The system uses feedback by comparing the determined polarity with the resolver offset calibration result. The polarity determination is validated against the calibration data, and any inconsistencies trigger re-measurement or correction, ensuring reliable final output.
2Ease of operation
If high-frequency signal injection is used for resolver offset calibration, then the calibration can be performed without rotating the motor, but the polarity information cannot be obtained from the same measurement
Solution Approach 1:
The high-frequency signal injection process is designed to serve dual purposes: both resolver offset calibration and polarity determination. By analyzing the d-axis current response during the same injection process, the system extracts both the offset calibration data and the polarity information without requiring separate measurement operations.
Solution Approach 2:
The patent merges the polarity determination measurement with the resolver offset calibration measurement into a single unified process. Both pieces of information are obtained simultaneously from the same high-frequency signal injection and d-axis current measurement, eliminating the need for separate operations.
Data Source
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AI summary
The present invention relates to a method (100) for determining polarity of a rotor in an interior permanent magnet synchronous motor for use in a resolver offset calibration operation. The method (100) comprises: obtaining (S102) an estimated d axis current based on an alternating voltage signal injected into the motor; determining (S104), for each of a plurality of subsequent time periods, a maximum and minimum value of the estimated d axis current; determining (S106), for each time period, whether the corresponding maximum and minimum value fulfils a defined condition; integrating (S108) the maximum and minimum values of the plurality of time periods that fulfil the defined condition, thereby forming a sum of the maximum and minimum values fulfilling the defined condition; and determining (S110) the polarity of the rotor based on the sum.