Resolver Correction Device Phase Difference Maintenance
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Solution Overview
Problem
Existing resolver correction devices face challenges in maintaining a predetermined phase difference of 90 degrees between phase shifters at varying motor rotation speeds, leading to detection errors in rotation angle and speed due to frequency modulation, and require proportional correction of shift amount setting values which is not always accurate.
Innovation Solution
A resolver correction device with a first and second phase shifter, an add circuit, excitation signal supply, phase difference detection, shift amount searching, and storage circuits to dynamically adjust shift amounts for each frequency, creating a correction table to maintain a 90-degree phase difference accurately across different rotation speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shift amount setting value is corrected proportionally to rotation speed, then phase difference can be maintained at high rotation speeds, but detection accuracy decreases at low rotation speeds where the relationship is not proportional
Solution Approach 1:
The patent implements dynamic adjustment of shift amount setting values based on the actual operating frequency of the resolver. Instead of using a fixed proportional correction, the system continuously adapts the shift amounts to maintain the 90-degree phase difference across the entire frequency range from low to high rotation speeds, thereby resolving the contradiction between reliability at high speeds and precision at low speeds
Solution Approach 2:
The patent changes the correction approach from a simple proportional relationship to a frequency-dependent parameter adjustment. By measuring the actual frequency of the detection signals and adjusting the shift amount setting values accordingly, the system maintains accurate phase difference across varying rotation speeds, improving both reliability and measurement precision simultaneously
2Device complexity
If proportional correction is applied to shift amount setting value, then correction process is simple, but detection error increases when frequency modulation is large
Solution Approach 1:
The patent introduces a feedback mechanism where the actual frequency of the detection signals is measured and used to adjust the shift amount setting values. This closed-loop approach ensures that the phase difference remains accurate even under large frequency modulation, improving measurement precision without excessively increasing device complexity
Solution Approach 2:
The patent performs preliminary calibration to establish the relationship between frequency and optimal shift amount setting values. This pre-characterization allows the system to quickly adjust to frequency changes without complex real-time calculations, balancing simplicity and accuracy
Data Source
AI summary
To provide a correction method of resolver correction device and resolver correction device that can reduce rotation angle (the rotation speed) detection error caused by resolver. An excitation signal supply circuit supplies an excitation signal of an excitation frequency to the resolver during a normal operation, for supplying the excitation signals of a plurality of frequencies including the excitation frequency to the first phase shifter or the second phase shifter during a calibration operation. A shift amount searching circuit searches the first shift amount setting value for each frequency of the excitation signal such that the first shift amount becomes 45 degrees, and the second shift amount setting value for each frequency of the excitation signal such that the second shift amount becomes 135 degrees, while referring to the detection result of the phase difference detection circuit during the calibration operation, and stores in the correction table.