Angular Position Sensor With Offset Windings
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Solution Overview
Problem
Existing angular position sensors with magnetic coils struggle to accurately determine the position over 360° due to signal repetition and electromagnetic interference, which affects precision and susceptibility.
Innovation Solution
A compact angular position sensor design featuring a first electric track with concentric half-windings and a second electric track with offset, reversed half-windings, along with a moving magnetic target, which generates differential voltages U2 and U3 to calculate the angular position using the atan(U3/U2) relation, minimizing electromagnetic emissions and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a planar excitation coil and secondary coils are used to determine angular position, then the sensor structure is simple and compact, but the measurement precision deteriorates because signals are repeated several times over one revolution making it impossible to determine the exact position of the target
Solution Approach 1:
The excitation coil is divided into multiple independent windings (first winding, second winding, third winding) with different spatial orientations and offset positions. Each winding generates a magnetic field component that, when combined, creates a unique magnetic field pattern at each angular position around the full 360° range, eliminating signal repetition and enabling precise position determination.
2Reliability
If an excitation coil generates a magnetic field for position detection, then the sensor can function, but electromagnetic emissions disturb other electronic equipment and the coil picks up interfering electromagnetic fields
Solution Approach 1:
Different windings are positioned at specific locations with different orientations (one winding centered, two windings offset by distance d1 along perpendicular axes). This spatial distribution creates localized magnetic field regions that are less susceptible to external electromagnetic interference and reduce the overall electromagnetic emission footprint of the sensor.
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 sensor accurately determines the angular position of a rotating object with high precision (0.2 to 0.5 degrees) while reducing electromagnetic susceptibility and emissions, complying with EMC standards.
Implementation Method 1
the excitation coil generates, when supplied with electric current, a magnetic field in the secondary coils. This magnetic field is then modulated by the presence of a target... which moves opposite the coils to create a coupling between coil primary and secondary coils
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
The present invention relates to an angular position sensor, comprising at least one first electrical track (1), at least one second electrical track (2), and at least one mobile magnetic target (3) opposite the first electrical track (1) and the second electrical track (2) and rigidly connected to a rotating object. The electrical track (1) comprises a first winding (11) consisting of turns that are centered relative to the rotational axis (O) of the rotating object and of the target (3), and the electrical track (2) comprises a second winding (21) consisting of turns, the center of which is offset by a distance dl relative to the center (O) of the turns of the first winding, and at least one third winding (22) consisting of turns, the center of which is offset by a distance dl relative to the center (O) of the first winding along an axis (5) that is perpendicular to the rotational axis of the rotating object and of the target and to an axis that passes through the center (O) of the first winding and of the second winding.