Magnetic Angle Sensor Diversity for Accuracy Drift
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Solution Overview
Problem
Magnetoresistive angle sensors, particularly GMR and TMR sensors, face accuracy drift issues at high magnetic fields and temperatures, necessitating improved accuracy for automotive safety applications, where ensuring the validity of sensed angle values is critical.
Innovation Solution
A magnetic angle sensor design incorporating multiple Wheatstone bridge circuits with diverse magnetoresistive elements, including those with varying meander stripe widths to achieve higher magnetic anisotropy, providing enhanced accuracy by ensuring saturation mode operation and estimating magnetic field strength through signal ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If GMR and TMR sensors are used to achieve 360-degree angle uniqueness, then angle measurement range is improved, but accuracy drift occurs at high magnetic fields and temperatures
Solution Approach 1:
The patent changes the magnetic anisotropy parameter by introducing magnetoresistive elements with different stripe widths (first stripe width for sine bridge, second stripe width for cosine bridge). This parameter change enables the sensor to maintain accurate measurements across high magnetic fields and temperatures while achieving 360-degree angle uniqueness, resolving the accuracy drift problem of conventional GMR and TMR sensors.
2Measurement precision
If AMR angle sensors are used to achieve high accuracy, then measurement precision is improved, but angle uniqueness is limited to 180 degrees
Solution Approach 1:
The patent creates a composite magnetoresistive bridge structure combining elements with different stripe widths and magnetic anisotropy characteristics. This composite approach integrates the high accuracy benefit of AMR sensors with the extended 360-degree measurement capability of GMR/TMR sensors, achieving both precision and versatility simultaneously.
3Measurement precision
If multiple Wheatstone bridge circuits with diverse magnetoresistive elements are used to enhance accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the magnetoresistive bridge into distinct functional elements: sine bridge elements with first stripe width and cosine bridge elements with second stripe width. This segmentation allows each element to be optimized for its specific function while maintaining overall system accuracy, managing complexity through functional decomposition.
Solution Approach 2:
The diverse magnetoresistive elements serve multiple functions: they provide both sine and cosine bridge outputs for 360-degree angle measurement and simultaneously compensate for accuracy drift at high magnetic fields and temperatures. This multi-functionality reduces the need for additional separate compensation mechanisms, managing overall 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
The solution enhances angle accuracy and reliability by minimizing angle errors and ensuring high accuracy measurements across a range of magnetic field strengths, meeting stringent automotive safety standards.
Implementation Method 1
GMR and TMR sensors are based on magnetoresistive elements having a free layer, which aligns its magnetization with an external magnetic field, and a reference layer, which is not affected by the external magnetic field. The magnetization of the free layer rotates with respect to the reference layer, resulting in a change of the resistance of the magnetoresistive elements.
Implementation Method 2
A magnetic angle sensor design incorporating multiple Wheatstone bridge circuits with diverse magnetoresistive elements, including those with varying meander stripe widths to achieve higher magnetic anisotropy, providing enhanced accuracy by ensuring saturation mode operation
Data Source
AI summary
A magnetic angle sensor including a first Wheatstone bridge circuit having a plurality of first magnetoresistive elements; and a second Wheatstone bridge circuit having a plurality of second magnetoresistive elements, wherein the plurality of second magnetoresistive elements have diversity with respect to the plurality of first magnetoresistive elements.