Rotating Field Sensor Harmonic Cancellation
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Solution Overview
Problem
Rotating field sensors using magnetoresistive elements often experience errors in detecting the angle of a rotating magnetic field due to distortion in output signal waveforms, particularly from second and third harmonic components, leading to inaccuracies in angle detection.
Innovation Solution
The rotating field sensor employs multiple signal generation units with magnetoresistive elements and computing circuits to process signals, reducing error components by canceling out second and third harmonic components through specific phase differences and computations, thereby improving the accuracy of detected angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetoresistive elements are used in bridge circuits to detect the rotating magnetic field, then the sensor can measure the angle of rotation, but the output signal waveform becomes distorted due to second and third harmonic components, reducing measurement precision
Solution Approach 1:
The patent divides the detection system into multiple bridge circuits (at least two bridge circuits) with magnetoresistive elements arranged at different orientations. Each bridge circuit detects a component of the rotating magnetic field, and the combined output allows for mathematical processing to eliminate harmonic distortion components, thereby improving angle detection accuracy despite individual circuit distortions
Solution Approach 2:
The patent employs a processing circuit that receives signals from multiple bridge circuits and performs computational processing to cancel out second and third harmonic components. This feedback-based signal processing approach continuously corrects for waveform distortion by using the phase and amplitude relationships between multiple sensor outputs to reconstruct the true rotational angle
2Measurement precision
If multiple bridge circuits with magnetoresistive elements are used to reduce harmonic distortion, then measurement precision improves, but device complexity increases due to additional components and circuits
Solution Approach 1:
The patent combines multiple bridge circuits and their signal processing functions into an integrated sensor structure. The magnetoresistive elements are arranged in a compact configuration where multiple detection axes share common structural support and signal processing resources, reducing the overall device complexity while maintaining the precision benefits of multiple measurement channels
Solution Approach 2:
The processing circuit is designed to perform multiple functions: it simultaneously processes signals from all bridge circuits, cancels harmonic distortion components, calculates the rotational angle, and can potentially detect other parameters such as rotational speed. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby managing device complexity
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 reduces errors in detected angles by effectively canceling out harmonic components, enhancing the precision of angle detection while simplifying the sensor's structure and reducing the number of required Wheatstone bridge circuits.
Implementation Method 1
each of the two bridge circuits includes four magnetoresistive (MR) elements serving as magnetic detection elements
Data Source
AI summary
A first, a second, and a third computing circuit respectively generate a first post-computation signal with a second harmonic component reduced as compared with first and second signals, a second post-computation signal with the second harmonic component reduced as compared with third and fourth signals, and a third post-computation signal with the second harmonic component reduced as compared with fifth and sixth signals. A fourth and a fifth computing circuit respectively generate a fourth post-computation signal with a third harmonic component reduced as compared with the first and second post-computation signals, and a fifth post-computation signal with the third harmonic component reduced as compared with the second and third post-computation signals. A sixth computing circuit determines a detected angle value based on the fourth and fifth post-computation signals.