FBG-SMC Magnetic Flux Sensor Material Volume Fraction Study for Healthy and Demagnetized Surface Permanent Magnet Rotor Magnetic Flux Monitoring Applications

This paper presents a study of the design, fabrication and characterization of an integrated fibre optic flux sensing device that combines soft magnetic composite (SMC) material with a Fibre Bragg Grating (FBG) sensor in either a 20% or a 50% SMC material volume fraction. The aim is to evaluate the SMC sensors’ response features when monitoring the magnetic flux of surface permanent magnet (SPM) rotors in electric machines, and how they are affected by the material volume fraction utilized in the design of these sensors. To achieve this purpose two prototype magnetic flux sensors have been developed by integrating FBG sensors into appropriate matrices of SMC material and specialized adhesive. Initial calibration results indicate that the 50% SMC material volume fraction composite magnetic flux sensor exhibits a greater response in Bragg wavelength shift compared to the 20% version when subjected to external magnetic fields. The performance of the sensors was further evaluated in experiments on an SPM rotor test rig operating in different dynamics and magnetization states.