Magnetic Sensor Harmonic Cancellation via Tilted Magnetoresistance Elements
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Solution Overview
Problem
Existing magnetic sensors for angle of rotation detection suffer from erroneous detection due to harmonic components in output signals, necessitating a solution to reduce these harmonic components for improved accuracy.
Innovation Solution
A magnetic sensor system comprising a detecting magnetoresistance element and a canceling magnetoresistance element, where the tilt angle between their magnetic sensing directions is set within a predetermined range, allowing for differential signal processing to minimize harmonic components, particularly the third harmonic, in the output signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single magnetoresistance element is used for angle detection, then the device structure is simple, but harmonic components cause erroneous detection
Solution Approach 1:
The sensor is divided into multiple magnetoresistance elements (detecting element and canceling element) with different magnetic sensing directions. The detecting element senses the magnetic field in one direction while the canceling element senses it in a different direction, allowing harmonic components to be separated and eliminated through differential processing.
Solution Approach 2:
The canceling magnetoresistance element acts as an intermediary that specifically detects harmonic components. By positioning this element at a specific tilt angle relative to the detecting element, the harmonic signals are captured and can be subtracted from the detecting element's output, leaving only the fundamental angle information.
2Measurement precision
If multiple magnetoresistance elements are arranged to reduce harmonics, then detection accuracy improves, but the device complexity increases
Solution Approach 1:
The key parameter optimized is the tilt angle between the magnetic sensing directions of the detecting and canceling elements. By setting this angle to specific values (60°, 90°, or 120°), the sensor achieves optimal harmonic cancellation with minimal element count. This parameter optimization allows effective harmonic reduction using only one additional element rather than requiring multiple complex elements.
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
The magnetic sensor system effectively reduces harmonic components in the output signals, enhancing the accuracy of angle of rotation detection by eliminating significant third harmonic components.
Implementation Method 1
a first detecting bridge circuit to output a first cosine wave signal and a second detecting bridge circuit to output a first sine wave signal
Data Source
AI summary
The problem to be overcome by the present disclosure is to reduce harmonic components included in output signals. A magnetic sensor includes a detecting magnetoresistance element and a canceling magnetoresistance element. A tilt angle formed by a magnetic sensing direction of the canceling magnetoresistance element with respect to a magnetic sensing direction of the detecting magnetoresistance element falls within a predetermined range. The predetermined range is defined by reference to either n×α/3 or n×α/3+α/2, where α is an angle of rotation of a rotator corresponding to one cycle of a fundamental harmonic included in output signals of the detecting magnetoresistance element and n is a natural number equal to or greater than 1.