Star-Connected Magnetoresistive Bridge for Angle Sensor Accuracy
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Solution Overview
Problem
Conventional magnetic angle sensors have limited accuracy and diagnostic coverage due to their reliance on absolute values of output signals, and adding more sensing elements increases cost, complexity, and size while providing only marginal improvements in functional safety.
Innovation Solution
An angle sensor with a sensing element that provides output signals associated with multiple non-orthogonal components of a magnetic field, allowing for improved functional safety checks, increased reliability, and redundancy, while reducing the number of elements and thus the cost and complexity compared to traditional designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If more sensing elements are added to improve functional safety and measurement accuracy, then measurement precision and reliability are improved, but device complexity, size, and cost increase
Solution Approach 1:
The sensing element is segmented into multiple bridge circuits (first bridge, second bridge, third bridge) with different orientations. Each bridge is segmented to sense magnetic field components along specific axes, allowing the system to achieve comprehensive 3D magnetic field measurement through segmentation rather than using a single complex sensing element
Solution Approach 2:
Each bridge circuit serves multiple functions: it acts as a sensing element for magnetic field measurement, provides diagnostic capability through self-check functions, and contributes to both X and Y component measurements when combined with other bridges. This multi-functionality reduces the need for separate dedicated sensing elements
2Reliability
If more sensing elements are added to improve functional safety and measurement accuracy, then reliability is improved, but cost increases
Solution Approach 1:
The bridge circuits incorporate self-check functions that allow them to autonomously detect their own operational status and diagnose faults. The sensing elements perform self-diagnostics without requiring external testing equipment or additional dedicated diagnostic components, reducing system cost while maintaining high functional safety
Solution Approach 2:
The same bridge circuits used for magnetic field sensing also serve as diagnostic elements. The output signals from the bridges provide both measurement information and diagnostic information, eliminating the need for separate diagnostic sensing elements and reducing overall system cost
3Measurement precision
If more sensing elements are added to improve functional safety and measurement accuracy, then measurement precision is improved, but the size of the sensor increases
Solution Approach 1:
Multiple bridge circuits are merged into a single integrated sensing element structure. The first, second, and third bridges are combined within one sensing element, allowing comprehensive 3D magnetic field measurement to be achieved in a compact form factor rather than requiring multiple separate sensing elements that would increase overall size
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 proposed solution enhances the accuracy and diagnostic coverage of functional safety checks and reduces the size and cost of the angle sensor, providing improved reliability and redundancy without the need for additional sensing elements.
Implementation Method 1
a first magnetoresistive element having a first magnetic reference direction along a first reference axis, a second magnetoresistive element having a second magnetic reference direction along the first reference axis
Data Source
AI summary
An angle sensor may comprise a sensing element including a first half bridge, where magnetic reference directions of resistors of the first half bridge are along a first reference axis. The sensing element may include a second half bridge, where magnetic reference directions of resistors of the second half bridge are along a second reference axis. The sensing element may include a third half bridge, where magnetic reference directions of resistors of the third half bridge are along a third reference axis. At least two of the first reference axis, the second reference axis, or the third reference axis may be non-orthogonal to each other.