應用於磁浮泵偏心量估測之雙軸渦電流位移感測系統開發

Abstract

本研究對於磁浮泵應用中對於高精度、微型化位移感測的需求，設計並開發一套雙軸渦電流位移感測系統，應用於即時量測轉子於二維平面的偏心位移。傳統渦電流感測器常受限於空間、靈敏度與干擾影響，無法有效應用於磁浮泵內部狹窄結構與動態環境。本文從理論模型出發，導入截斷區域特徵函數展開法與有限元素分析，經過驗證後建立阻抗模型並針對理論缺失的交流電阻進行補償，根據結果可知所使用之數值模型能良好應用，後續進一步整合粒子群最佳化演算法進行線圈幾何參數設計，進而獲得最佳性能的設計組合。本系統採用橋式雙探頭架構，搭配解調電路與儀表放大器進行訊號處理，將帶有位移訊號之交流訊號轉為直流電壓輸出，再透過位移估測模型估測轉子在平面內之位置資訊。本研究開發一套具實用性之高性能微型渦電流位移感測系統，亦建立一套可廣泛應用於其他渦電流感測場合的理論設計流程，提供高精度位移感測領域中快速且表現良好的設計方法。 實驗結果顯示，所設計之探頭大小外徑小於5mm，渦電流感測系統在1毫米的量測範圍內可達到小於2.5 µm 的解析度，靈敏度可達約2 V/mm，非線性度約為1.35%。在動態測試中亦能穩定追蹤轉子平移行為，同時具備良好重複性。

This study addresses the demand for high-precision and miniaturized displacement sensing in magnetically levitated pump applications by designing and developing a dual-axis eddy current displacement sensing system capable of real-time measurement of rotor eccentric displacement in a two-dimensional plane. Traditional eddy current sensors are often limited by spatial constraints, insufficient sensitivity, and susceptibility to interference, making them unsuitable for use within the compact structure and dynamic environment of magnetic levitation pumps. Starting from theoretical modeling, this study incorporates the Truncated Region Eigenfunction Expansion (TREE) method along with finite element analysis (FEA) to establish a validated impedance model. To address deficiencies in the theoretical model, compensation for AC resistance is introduced. Furthermore, the geometric parameters of the sensing coil are optimized using a Particle Swarm Optimization (PSO) algorithm, resulting in an optimal design configuration with enhanced performance. The developed system adopts a bridge-type dual-probe architecture, integrated with synchronous demodulation circuitry and an instrumentation amplifier for signal processing. The AC signal carrying displacement information is converted into a readable DC voltage output, which is then interpreted using a displacement estimation model to determine the rotor’s position within the plane. This research successfully develops a practical, high-performance, and miniaturized eddy current displacement sensing system, and also establishes a generalizable theoretical design framework applicable to various eddy current sensing applications. It provides a rapid and efficient design methodology for achieving high-precision displacement sensing. Experimental results demonstrate that the proposed sensing system achieves a resolution of less than 2.5µm within a 1 mm measurement range, with a sensitivity of approximately 2 V/mm and a linearity error of around 1.35%. In dynamic testing, the system is capable of reliably tracking rotor translation, exhibiting excellent repeatability and strong noise immunity.