Magnetoresistive Sensor Angle Determination via Dual Half-Bridge Segmentation
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Solution Overview
Problem
Magnetoresistive sensors used for angular detection in automotive applications suffer from high offset and offset drift over temperature, leading to angular errors that require sophisticated compensation.
Innovation Solution
A sensor system utilizing two half-bridges with magnetoresistive resistors, one with and one without barber-pole stripes, and a modulation unit with coils generating magnetic fields in x- and y-directions, allowing for improved magnetic field angle determination by maximizing signal amplitude and eliminating offset errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two Wheatstone bridges rotated by 45° are used for angular detection, then the sensor can measure magnetic field angle, but the offset is relatively high and drifts over temperature
Solution Approach 1:
The sensor is divided into two separate half-bridges with different orientations (0° and 45°), each contributing to the overall measurement. This segmentation allows the system to process signals from multiple orientations and eliminate offset errors through differential measurement, resolving the contradiction between measurement capability and offset stability.
Solution Approach 2:
The invention changes the operational parameters by using two different bridge orientations (0° and 45°) and processing their signals differently. By analyzing the amplitude ratio and phase difference between the two bridges, the system can determine the magnetic field angle while compensating for offset drift, thus improving both measurement precision and offset stability.
2Measurement precision
If two Wheatstone bridges rotated by 45° are used, then angular detection is enabled, but sophisticated offset compensation is required
Solution Approach 1:
The sensor system performs self-compensation by using the differential measurement between two half-bridges with different orientations. The offset errors are automatically eliminated through the measurement process itself, without requiring external compensation circuits or complex calibration procedures, thus reducing device complexity while maintaining angular detection precision.
3Measurement precision
If magnetoresistive sensors with barber-pole stripes are used, then magnetic field angle measurement is achieved, but signal amplitude is limited
Solution Approach 1:
The invention merges the measurement capabilities of two half-bridges with different orientations (0° and 45°) to achieve both accurate angle measurement and maximized signal amplitude. By combining the signals from both bridges and analyzing their amplitude ratio, the system overcomes the signal amplitude limitation of individual magnetoresistive sensors while maintaining measurement precision.
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 provides accurate magnetic field angle determination by maximizing signal amplitude and eliminating angular errors due to offset, reducing the need for complex compensation techniques.
Implementation Method 1
a first coil for generating a magnetic modulation field in an x-direction, a second coil for generating the magnetic modulation field in a y-direction and an oscillator for exciting the first coil and the second coil in an alternating manner for generation of the magnetic modulation field
Implementation Method 2
a first half-bridge, a second half-bridge and a modulation unit for modulating the magnetic field in two directions, wherein the first half-bridge has a first and a second magnetoresistive resistor with barber-pole stripes
Data Source
AI summary
Magnetoresistive sensors are commonly used for angular detection in many automotive applications. According to an exemplary embodiment of the present invention, a sensor is provided in which a first half-bridge has magnetoresistive resistors with barber-pole stripes and in which a second half-bridge has magnetoresistive resistors without barber-pole stripes. One of the resistors without barber-pole stripes is rotated with respect to the other three resistors by 90°. This may provide for an improved angle determination with reduced angular errors due to offset.