Inductive Position Sensor PCB Secondary Windings
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Solution Overview
Problem
Inductive position sensors are sensitive to geometric variations such as airgap and eccentricity, which affects their accuracy and linearity.
Innovation Solution
The design of secondary windings on a printed circuit board, where each turn is divided into complementary and successive sectors on opposite faces, with vias connecting these sectors to balance the turn pattern and reduce sensitivity to airgap and eccentricity variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If turns are produced on two distinct layers of the printed circuit board to limit space, then the area occupied on the printed circuit board is reduced, but the sensor becomes sensitive to geometric variations such as airgap and eccentricity
Solution Approach 1:
Each turn is segmented into four portions distributed across two opposite faces of the printed circuit board. The first and second portions are on the first face, while the third and fourth portions are on the second face. This segmentation balances the turn pattern and reduces sensitivity to airgap and eccentricity variations while maintaining compact area usage.
Solution Approach 2:
The turn pattern extends into the third dimension by utilizing both faces of the printed circuit board. Turns pass through the board via vias, creating a balanced three-dimensional structure that compensates for geometric variations. This dimensional approach maintains electrical continuity while achieving geometric balance.
2Measurement precision
If a large number of turns are used to obtain reliable induced currents, then measurement reliability is improved, but the sensor size increases
Solution Approach 1:
By utilizing both faces of the printed circuit board and routing turns through vias, the effective winding area is doubled without increasing the planar footprint. This allows achieving reliable induced currents with a compact sensor size by exploiting the third dimension.
Solution Approach 2:
Multiple portions of each turn are merged into a unified electrical path that spans both faces of the board. The vias connect these portions to form continuous turns, effectively combining space on both faces into a single functional winding structure that achieves reliable signals in a compact volume.
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 design significantly reduces sensitivity to airgap and eccentricity, improving linearity and anchoring the turns, resulting in a two-fold performance gain with linearity improved from 1.5% to 0.5% and airgap sensitivity from 0.5% to 0.3% for an eccentricity of 0.5 mm in a 360° sensor.
Implementation Method 1
The primary winding and the secondary windings of a transformer operating at high frequency... currents induced in the target modify the currents induced in the secondary windings
Implementation Method 2
The coupling between these windings varies with the position of an electrically conductive moving part, which is generally referred to as the target. Specifically, currents induced in the target modify the currents induced in the secondary windings
Data Source
AI summary
An inductive position sensor including at least two secondary windings consisting of a plurality of turns that are formed on two opposite faces of a printed circuit board and divided into first and second sectors. The first and second sectors are divided, in one turn width, into a first portion on one face of the printed circuit board and a second portion on an opposite face. The second portion of the first sector is extended by a first portion of the second sector and the first portion of the first sector is connected to the second portion of the second sector of a neighboring turn. The portions are connected pairwise by a respective via passing through the printed circuit board.