A1 Journal article (refereed), original research

Three-Axis Inductive Displacement Sensor Using Phase-Sensitive Digital Signal Processing for Industrial Magnetic Bearing Applications

Open Access publication

Publication Details

Authors: Sillanpää Teemu, Smirnov Alexander, Jaatinen Pekko, Vuojolainen Jouni, Nevaranta Niko, Jastrzebski Rafal, Pyrhönen Olli

Publication year: 2021

Language: English

Related journal or series: Actuators

Volume number: 10

Issue number: 6

eISSN: 2076-0825

JUFO level of this publication: 1

Digital Object Identifier (DOI): http://dx.doi.org/10.3390/act10060115

Permanent website address: https://www.mdpi.com/2076-0825/10/6/115

Open Access: Open Access publication


Non-contact rotor position sensors are an essential part of control systems in magnetically suspended high-speed drives. In typical active magnetic bearing (AMB) levitated high-speed machine applications, the displacement of the rotor in the mechanical air gap is measured with commercially available eddy current-based displacement sensors. The aim of this paper is to propose a robust and compact three-dimensional position sensor that can measure the rotor displacement of an AMB system in both the radial and axial directions. The paper presents a sensor design utilizing only a single unified sensor stator and a single shared rotor mounted target piece surface to achieve the measurement of all three measurement axes. The sensor uses an inductive measuring principle to sense the air gap between the sensor stator and rotor piece, which makes it robust to surface variations of the sensing target. Combined with the sensor design, a state of the art fully digital signal processing chain utilizing synchronous in-phase and quadrature demodulation is presented. The feasibility of the proposed sensor design is verified in a closed-loop control application utilizing a 350-kW, 15,000-r/min high-speed industrial induction machine with magnetic bearing suspension. The inductive sensor provides an alternative solution to commercial eddy current displacement sensors. It meets the application requirements and has a robust construction utilizing conventional electrical steel lamination stacks and copper winding.

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Last updated on 2021-17-09 at 07:20