Electric Machine Control Device Beat Signal Rotor Position Correction
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Solution Overview
Problem
Existing methods for controlling electric motors, particularly synchronous motors, face angular position calculation distortions due to non-ideal alignment between sine and cosine tracks emitted by position sensors, leading to incorrect current settings in motor controllers, which are exacerbated by signal noise and eccentricities.
Innovation Solution
A control device and method that generates a beat signal with a deviating frequency, added to the sensor signal to form a sum signal, allowing for the calculation of a correction value based on the minimum of this sum signal, thereby correcting rotor position without normalization and enhancing robustness against signal noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the angular position between sine track and cosine track is not exactly 90 degrees, then angular position calculation is performed, but the calculated angular value is distorted
Solution Approach 1:
The patent applies feedback by calculating the angular deviation between the actual angle and the ideal 90-degree position, then using this deviation information to generate correction factors that adjust the sine and cosine tracks. This closed-loop feedback mechanism continuously compensates for misalignment errors, improving measurement precision while maintaining reliability.
Solution Approach 2:
The patent changes the parameters of the sine and cosine tracks by applying correction factors derived from the angular deviation. These parameter adjustments modify the amplitude and phase of the tracks to compensate for misalignment, thereby eliminating angular value distortion while preserving accurate position calculation.
2Measurement precision
If arc sine or arc cosine function is used to calculate separate angles for sinus and cosine tracks, then correction factor can be obtained, but signal noise and eccentricities impede the normalization process
Solution Approach 1:
The patent converts the harmful effect of signal noise and eccentricities into a beneficial measurement by using the angular deviation itself as the basis for correction. Instead of requiring perfect normalization that would be impeded by noise, the method directly measures the deviation and uses it to generate correction factors, thereby transforming the problematic normalization requirement into a robust deviation-based correction approach.
Solution Approach 2:
The patent introduces an intermediary element - the angular deviation calculation - that mediates between the noisy sensor signals and the final corrected position. By using the deviation as an intermediate measurement, the system avoids direct normalization of noisy signals while still obtaining accurate correction factors through the deviation-based correction process.
3Measurement precision
If normalization of sine track and cosine track is performed to value range +/-1, then angular calculation accuracy is improved, but the process is impeded by signal noise and eccentricities
Solution Approach 1:
The patent extracts the essential correction information - the angular deviation - from the complex normalization process. By taking out only the deviation measurement that is needed for correction, the system avoids the complexity of full normalization while still achieving accurate angular calculation through deviation-based correction factors.
4Object-affected harmful factors
If beat signal is generated and added to sensor signal, then correction value can be calculated without normalization, but additional signal processing steps are required
Solution Approach 1:
The patent applies periodic action by generating a beat signal with a specific frequency that is added to the sensor signal. This periodic beat signal creates a modulated sum signal where the correction information appears as a detectable periodic component, enabling noise-robust correction value extraction through frequency-based signal processing.
Solution Approach 2:
The patent performs preliminary action by pre-generating the beat signal with the appropriate frequency before adding it to the sensor signal. This preliminary preparation of the correction carrier signal enables the subsequent extraction of correction values without requiring complex real-time normalization, thereby improving noise robustness while managing processing complexity.
Data Source
AI summary
The present invention discloses a control device for an electric machine comprising a sensor interface designed to receive a sensor signal from a position sensor of the electric machine, wherein the position sensor is designed to detect the rotor position of the electric machine, a signal generator designed to generate a beat signal that corresponds to the sensor signal with a signal frequency increased by a beat frequency, a summation unit designed to form a sum signal from the sum of the beat signal with the sensor signal, and a correction unit designed to calculate a correction value for the sensor signal on the basis of a minimum of the sum signal. The present invention further discloses a corresponding method and a corresponding motor controller.