Angle Sensor Interference Field Compensation via Offset Sensors
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Solution Overview
Problem
Existing angle sensor devices face challenges in effectively compensating for interference fields without significant design effort or increased cost, particularly in environments with strong electromagnetic interference, such as the automotive sector, where they must tolerate magnetic interference fields up to 3 kA/m.
Innovation Solution
The proposed solution involves an angle sensor device with at least two angle sensors arranged axially or radially offset with respect to the axis of rotation, allowing for algebraic evaluation of their signals to compensate for interference fields, using a magnetic field generating device like a permanent magnet with distinct poles to create a gradient field, and employing xMR sensor topology for precise angle detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferromagnetic hollow cylinder shielding is used to compensate for interference fields, then interference field tolerance is improved, but structural complexity and manufacturing cost increase significantly
Solution Approach 1:
The angle sensor device is divided into multiple independent angle sensors (at least two) that are distributed in space around the axis of rotation. Each sensor independently measures the magnetic field, and their signals are combined through algebraic evaluation to achieve interference field compensation without requiring complex shielding structures.
Solution Approach 2:
Multiple angle sensors are combined in a coordinated arrangement around the rotation axis. Their measurement signals are algebraically evaluated together to extract the useful rotation angle information while canceling out interference field components, achieving compensation through signal integration rather than physical shielding.
2Reliability
If four Hall resistors are arranged in a bridge circuit distributed axially to compensate for interference fields, then interference field tolerance is improved, but chip area and sensor device size increase
Solution Approach 1:
The angle sensors are arranged in a radial distribution around the axis of rotation rather than being concentrated in a single plane. This spatial distribution in multiple dimensions allows interference field compensation while maintaining a compact chip area, as the sensors utilize the circumferential space around the rotation axis.
3Reliability
If two angle measurement sensors with independent magnetic fields are used for compensation, then interference field tolerance is improved, but production cost and manufacturing precision requirements increase
Solution Approach 1:
All angle sensors in the device measure the same rotating magnetic field generated by the single magnetic field generating device. The sensors are universally exposed to the same useful magnetic field conditions, and their identical measurement characteristics enable straightforward algebraic evaluation for interference compensation without requiring complex calibration procedures.
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 configuration enables effective compensation of interference fields, reducing their influence on angle detection, allowing for accurate angle measurement even in high interference environments, and is cost-effective with minimal design complexity.
Implementation Method 1
A magnetic field generating device generates a magnetic field that rotates relative to an angle sensor device
Implementation Method 2
angle sensor device being able to determine the angular orientation of the rotating magnetic field
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
The invention relates to an interference field-compensated angle sensor device (30, 32, 34, 36, 38, 40) for magnetic field-based determination of a rotational angle of an axis of rotation (12), comprising a magnetic field generating device, in particular a permanent magnet (10, 14), and an angle sensor device (50, 52, 54, 56, 58, 60). A magnetic field of the magnetic field generating device (16) rotates relative to the angle sensor device (50, 52, 54, 56, 58, 60). It is proposed that the angle sensor device (50, 52, 54, 56, 58, 60) comprises at least two angle sensors (20) which are arranged in a in an axially and/or radially offset manner relative to the axis of rotation (12) so that an influence of an interference field can be compensated by means of a gradient formation of the angular values or sensor signals (64) of the angle sensors (20). In a secondary aspect of the invention, a method for interference field-compensated angle determination is proposed, in which an angle or sensor value deviation between the angle sensors (20) of the angle sensor device (50, 52, 54, 56, 58, 60) is used for compensation of external interference field.