Multipole Resolver Error Correction for Motor Rotation
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Solution Overview
Problem
The existing methods for correcting errors in motor rotation angle calculations using multipole resolvers suffer from significant time lags, leading to inaccurate corrections during abrupt changes in the operating state of motors or inverters, which can result in deteriorated accuracy.
Innovation Solution
A rotation angle calculation apparatus and method that differentiate between transition and normal states by using errors from previous resolver periods, with transition corrections relying on more recent errors and normal corrections using errors from one mechanical period ago, adjusting the extent of error reflection based on state changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If error correction is performed individually for each section (pole) of the multipole resolver, then measurement precision of rotation angle is improved, but time lag increases due to one full mechanical rotation period
Solution Approach 1:
The patent segments the mechanical rotation period into multiple resolver periods corresponding to each pole of the multipole resolver. Error correction is performed independently for each resolver period rather than waiting for a complete mechanical rotation, thereby reducing the time lag while maintaining section-specific correction accuracy.
Solution Approach 2:
The patent performs error correction using data from previous resolver periods before the current resolver period completes. By preparing and applying correction values in advance based on historical data, the system reduces the effective time lag and ensures correction is available when needed.
2Measurement precision
If error correction uses data from one mechanical period ago, then correction accuracy is maintained under normal conditions, but accuracy deteriorates during transition periods when operating state changes abruptly
Solution Approach 1:
The patent dynamically adjusts the error correction strategy based on the detected operating state. During normal operation, correction uses data from one mechanical period ago for stability. During transition periods detected by monitoring voltage or current changes, the system switches to using correction data from the immediately preceding resolver period, making the correction mechanism adaptive to changing conditions.
Solution Approach 2:
The patent changes the time parameter used for error correction based on operating conditions. The correction time window is extended to one mechanical period under normal conditions but shortened to one resolver period during transitions, allowing the system to optimize between accuracy and responsiveness based on real-time parameter changes.
3Speed
If correction uses errors from immediately preceding resolver period during transitions, then responsiveness to state changes is improved, but correction accuracy may decrease due to larger time lag in normal operation
Solution Approach 1:
The patent implements a dynamic correction strategy where the system automatically switches between two correction modes: using immediately preceding resolver period errors during transition states for high responsiveness, and using one mechanical period ago errors during normal states for high precision. This dynamic adaptation resolves the contradiction by selecting the appropriate correction approach based on real-time operating conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses the deterioration in error correction accuracy due to abrupt changes in motor or inverter operating states, ensuring more precise motor control.
Implementation Method 1
The resolver is attached to the rotating shaft of the motor, and generates an electrical signal (analog signal) in accordance with the rotation angle of the motor, based on a change in magnetic flux.
Data Source
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AI summary
A control apparatus (40) using a multipole resolver for calculating the rotation angle of a motor includes an acquisition unit (41), a learning unit (42), a calculation unit (43), and a correction unit (44). The acquisition unit (41) acquires a detected angle θ detected by the multipole resolver. The learning unit (42) learns the waveform of an error Errθ for each pole of the resolver. The calculation unit (43) calculates a motor's rotational acceleration variation α. The correction unit (44) compares the rotation speed variation α with a threshold value α0. Where α < α0, the correction unit (44) performs a normal correction of calculating a corrected angle φ using an error Errθ of one mechanical period (in which the motor makes one full rotation) ago. In contrast, where α > α0, the correction unit (44) performs a transition correction of calculating a corrected angle φ using an immediately preceding error Errθ.