Inductive Angle Sensor Coil Topology for Interference Resistance
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Solution Overview
Problem
Existing rotation angle sensors face challenges with high susceptibility to electromagnetic interference, cross-sensitivity to installation tolerances, and limited angular resolution due to external magnetic fields and complex signal processing requirements.
Innovation Solution
A rotation angle sensor design featuring a stator element with a transmission coil and receiving coils arranged on a printed circuit board, where the receiving coils encircle the axis of rotation, inducing AC voltages that depend sinusoidally on the rotation angle, allowing for robust, cost-effective, and interference-resistant angle measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnet and magnetic field sensor are used to measure rotation angles, then the rotation angle can be determined via magnetic field vector measurement, but the sensor becomes highly susceptible to interference from external magnetic fields such as those from nearby power cables
Solution Approach 1:
The patent replaces the magnetic field-based measurement system with an inductive coupling system using transmitting and receiving coils. This substitution eliminates the use of magnets and magnetic field sensors, thereby removing the susceptibility to external magnetic field interference while maintaining the capability to measure rotation angles through inductive coupling between coils
Solution Approach 2:
The patent introduces an evaluation unit as an intermediary that processes the signals from the receiving coils. This evaluation unit calculates the rotation angle based on the signal amplitudes and phase differences, providing a robust method that is not affected by external magnetic fields and can accurately determine rotation angles even in electrically noisy environments
2Measurement precision
If eddy current effect is used with a metallic target and sensor coils, then rotation angle can be determined via frequency change, but the sensor exhibits high lateral sensitivity to installation tolerances and temperature influences
Solution Approach 1:
The patent replaces the eddy current-based measurement system with an inductive coupling system using transmitting and receiving coils. This substitution eliminates the metallic target and eddy current effects, thereby removing the high lateral sensitivity to installation tolerances and temperature influences while maintaining accurate rotation angle measurement capability
Solution Approach 2:
The patent changes the measurement principle from frequency-based eddy current measurement to amplitude and phase-based inductive coupling measurement. By measuring the amplitude and phase of signals induced in receiving coils by a transmitting coil, the system achieves rotation angle determination that is less sensitive to installation tolerances and temperature variations
3Measurement precision
If planar conductor loops short-circuited on a target are used, then a signal resembling a square wave is generated depending on rotation angle, but the steep edges of such signals limit the angular resolution and require laborious conversion
Solution Approach 1:
The patent changes the signal waveform from square wave to sinusoidal by using transmitting and receiving coils with inductive coupling. The sinusoidal signals generated have smooth edges that improve angular resolution and can be easily processed by the evaluation unit to determine rotation angles, eliminating the need for complex signal conversion algorithms
Solution Approach 2:
The patent replaces the planar conductor loop system with an inductive coupling system using transmitting and receiving coils. This substitution generates sinusoidal signals instead of square waves, improving angular resolution and simplifying the evaluation process while maintaining rotation angle detection capability
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 design provides a precise, interference-resistant, and cost-effective rotation angle sensor with improved signal-to-noise ratio and reduced tolerance sensitivity, enabling accurate angle detection even in harsh electromagnetic environments.
Implementation Method 1
the transmitting coil induces at least two angle-dependent alternating voltages in the receiving coils
Data Source
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AI summary
A rotational angle sensor (10) comprises a stator element (12) with a transmitter coil (20) and at least one receiver coil (22), wherein the transmitter coil (20) and the at least one receiver coil (22) are arranged on a circuit board (18). The rotational angle sensor (10) comprises a rotor element (14) mounted to rotate about an axis of rotation (A). The rotational angle sensor (10) has a measuring range (β). According to the invention, the at least one receiver coil (22) substantially completely encloses the axis of rotation (A) in a circumferential direction (U), wherein the at least one receiver coil (22) is formed by a plurality of adjacent partial windings (50a-f), wherein each partial winding (50a-f) is formed from sections of two circular-arc-shaped conductor paths (42) curved to the left and two circular-arc-shaped conductor paths (40) curved to the right, each conductor path having the same radius of curvature, wherein a first conductor path (40) curved to the right extends through three points, - through a first point (P1), which lies on a first circle (91); - through a second point (P2), which lies on a third circle (93) and is rotated with respect to the first point (P1) in the circumferential direction by a quarter of the measuring range (β), - through a third point (P3), which lies on a second circle (92) and is rotated with respect to the first point (P1) in the circumferential direction by half the measuring range (β), wherein the conductor paths (42) curved to the left take the form of mirror images of the conductor paths (40) curved to the right.