Overlapping E-Core Position Sensor for Low-Cost Rotor Feedback
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Solution Overview
Problem
Magnetic bearing systems require multiple expensive position sensors for accurate rotor position measurement, which increases costs and complexity, especially when detecting temperature changes and five degrees of freedom.
Innovation Solution
A modular inductive position sensor using E-shaped ferromagnetic cores with overlapping teeth, wound coil bobbins, and a frame, connected in a bridge configuration to provide linear output voltages for rotor position measurement in x, y, and z directions, allowing for low-cost, high-accuracy position feedback without mechanical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple separate inductive proximity sensors are used to measure rotor position in five degrees of freedom, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple proximity sensing functions into a single integrated sensor assembly. The sensor assembly includes a common housing containing multiple inductive proximity sensors that simultaneously measure radial positions at both ends of the rotor and axial position, eliminating the need for separate sensor packages and reducing overall system complexity while maintaining five-degree-of-freedom measurement capability
2Measurement precision
If bridge connection between proximity sensors is used to enable more accurate measurement, then measurement precision is improved, but quantity of sensors needed increases
Solution Approach 1:
The patent implements bridge connections between multiple proximity sensors within a single integrated sensor assembly. The housing contains sensors arranged to form bridge circuits that enable differential measurement, improving accuracy through the bridge configuration while consolidating multiple sensing functions into one compact unit rather than requiring separate sensor packages
3Ease of operation
If complete packages including sensors and mechanical constructions are used, then ease of operation is improved, but cost increases
Solution Approach 1:
The patent integrates multiple sensors, mechanical mounting structures, and housing into a single complete package that is pre-assembled and ready for installation. The sensor assembly includes a common housing with all necessary mechanical constructions for mounting the sensors in the correct positions, providing ease of installation while reducing overall system cost through integrated design and elimination of separate packaging requirements
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 solution provides a cost-effective, robust, and accurate position measurement system capable of sustaining high temperatures and electromagnetic interference, suitable for high-speed electric motors, with scalable design for different rotor sizes.
Implementation Method 1
A low-cost modular inductive position sensor uses a plurality of E-shaped ferromagnetic cores and corresponding windings to provide non-contact position measurements
Implementation Method 2
Each E-shaped ferromagnetic core has a plurality of teeth including a stator tooth, wherein the plurality of E-shaped ferromagnetic cores are stacked to define offset sensing elements
Data Source
AI summary
A position sensor includes a plurality of E-shaped ferromagnetic cores arranged to define a circular opening therethrough to receive a shaft. Each E-shaped ferromagnetic core has a plurality of teeth, wherein adjacent E-shaped ferromagnetic cores of the arranged plurality of E-shaped ferromagnetic cores have an overlapping tooth. The position sensor further includes a frame surrounding the arranged plurality of E-shaped ferromagnetic cores, with the E-shaped ferromagnetic cores coupled to the frame.