Inductive Angle Sensor Common Mode Noise Rejection
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Solution Overview
Problem
Conventional inductive angle sensors suffer from low electromagnetic compatibility (EMC) characteristics due to ineffective common mode noise rejection, requiring complex structures with multiple substrates and high manufacturing costs.
Innovation Solution
The inductive angle sensor employs a simplified structure with symmetrically disposed semicircular receiver coils and a signal processor that adds, subtracts, multiplies, and divides signals to eliminate common mode noise, improving EMC characteristics and reducing substrate count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional inductive angle sensor uses a pair of receiver coils with different structures to measure rotation angle and distance, then measurement functionality is achieved, but the overall structure becomes complicated and manufacturing cost increases
Solution Approach 1:
The patent combines the rotation angle measurement and distance measurement functions into a single receiver coil structure. By using a differential winding configuration where adjacent turns are wound in opposite directions, the coil can detect both rotational position and axial distance variations through the same sensing element, thereby reducing structural complexity while maintaining measurement versatility
Solution Approach 2:
The receiver coil is designed to perform multiple measurement functions simultaneously. The same coil structure measures both the rotation angle of the coupler and the distance between the coupler and sensor substrate, making the sensing element universal and eliminating the need for separate dedicated coils for each measurement parameter
2Measurement precision
If conventional signal processing methods are used with differently structured receiver coils, then signal processing is achieved, but common mode noise is not effectively rejected and EMC characteristics remain low
Solution Approach 1:
The patent employs identical receiver coil structures for both measurement functions, ensuring that both coils experience the same electromagnetic environment and common mode noise. This homogeneity in structure allows the differential signaling to effectively cancel common mode noise, improving EMC characteristics while maintaining measurement precision
Solution Approach 2:
The patent converts the common mode noise, which is normally a harmful interference, into a useful signal cancellation mechanism. By using differential signaling with identically structured coils, the common mode noise appearing on both coils is subtracted out, transforming the harmful noise into a rejected component and improving signal quality
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 approach effectively cancels common mode noise, enhancing EMC and reducing manufacturing costs by simplifying the sensor structure, resulting in accurate angle measurements.
Implementation Method 1
When an oscillation voltage Vosc expressed by the following Math Figure 1 is applied from an oscillator connected to the exciting coil 2
Implementation Method 2
a first received voltage Ax and a second received voltage Bx expressed by the following Math Figures 2 and 3 are obtained from the first and second receiver coils 6 and 8
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention provides an inductive angle sensor with improved common mode noise rejection and a signal processing method of the same, which can improve electromagnetic compatibility (EMC) characteristics and obtain an accurate output value by eliminating common mode noise. The signal processing method includes adding signals obtained from a pair of receiver coils (26,28) by an adder (32), subtracting the signal obtained from one of the pair of receiver coils from the signal obtained from the other receiver coil by a subtracten (33), multiplying the value obtained from the adder by the value obtained from the subtracter by a first multiplier (34), multiplying the value obtained from the subtracter by itself by a second multiplier (35), and dividing the value obtained from the first multiplier by the value obtained from the second multiplier by a divider (38).