Mirror-Symmetric PCB Windings for Linear Inductive Position Sensing
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Solution Overview
Problem
Inductive position sensors face challenges in achieving linearity and accuracy due to the limitations of traditional transformer designs on printed circuit boards, particularly in compact form factors, where a high number of turns are required for reliable current measurement, but this often results in bulkiness and increased production complexity.
Innovation Solution
The design features secondary windings with turns formed on multiple layers of the printed circuit board, aligned with offsets and connected by vias, arranged in mirror symmetry to improve signal symmetry and reduce residual offsets, allowing for more accurate and linear position measurements without increasing the sensor's bulk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high number of turns are used in secondary windings to obtain reliable induced currents for measurement, then measurement precision is improved, but device volume increases making the sensor bulky
Solution Approach 1:
The patent applies multi-layer PCB technology to arrange secondary windings in three-dimensional space. Turns are distributed across multiple layers (at least two layers) and connected via vias, effectively utilizing the Z-dimension to pack more turns into a compact footprint. This dimensional transition from planar to spatial arrangement increases the number of turns without proportionally increasing the sensor's planar area, resolving the contradiction between measurement precision and device volume.
2Volume of moving object
If turns are arranged on multiple layers with vias to compact the sensor, then device volume is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent employs standard multi-layer PCB manufacturing techniques including vias, trace routing, and layer stacking that are universally applicable in electronics manufacturing. These are conventional processes already widely used in the industry, allowing the compact multi-turn winding structure to be produced using existing manufacturing infrastructure without requiring specialized or complex fabrication steps.
3Volume of moving object
If secondary windings are arranged asymmetrically to fit compact spaces, then device volume is reduced, but linearity and accuracy deteriorate
Solution Approach 1:
The patent deliberately introduces asymmetry in the form of mirror-symmetric pairs of secondary windings. Each pair consists of windings with opposite polarity arranged symmetrically with respect to a separation plane. This controlled asymmetric arrangement allows compact packaging while maintaining magnetic field balance and signal linearity, as the symmetric pairing compensates for the asymmetric spatial configuration.
Solution Approach 2:
The patent optimizes geometric parameters of the windings including turn spacing, layer distribution, via positioning, and winding dimensions. By carefully adjusting these parameters, the design achieves compact volume while maintaining the magnetic coupling characteristics necessary for linear and accurate position sensing. The parameters are tuned to balance compactness with measurement performance.
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 enhances the accuracy and linearity of the inductive position sensor, facilitates easier electronic adjustment, and maintains a compact form factor, making it suitable for precise angular position measurement in applications like electric motors and vehicles.
Implementation Method 1
The operating principle of an inductive sensor is based on the variation in coupling between a primary winding and secondary windings of a transformer operating at high frequency
Implementation Method 2
Specifically, currents induced in the target modify the currents induced in the secondary windings
Data Source
AI summary
An inductive position sensor includes, on the one hand, a primary coil and, on the other hand, at least one secondary coil that includes at least two secondary windings each consisting of a plurality of turns formed on two layers of a printed circuit board. Each of the turns has a first generally concave portion placed on one layer of the printed circuit board and a second generally concave portion placed on another layer of the printed circuit board. Among the first portions and second portions of the turns of the two secondary windings, at least some of these first and second portions are arranged in mirror symmetry on either side of a transverse separation plane, this transverse separation plane being located between the two secondary windings and being orthogonal to the longitudinal direction.