Vibration of the electric machine occurs mechanical causes that damage of bearing, balancing of rotor, eccentricity. Displacement measurement sensor need to measure this vibration and mostly contactless eddy-current sensor used to measure. But eddy-current sensor is sensitive to magnetic field so it’s inappropriate in magnetic bearing or permanent magnet synchronous motor. Therefore, to complement some limiting condition, hall sensor use to measure vibration.
In this paper, using hall sensor that detect magnetic field, it measure the position of rotor containing permanent magnet. Linear hall sensor can express sinusoidal wave function and rotor position information is contained in the amplitude. in the paper, Amplitude extraction algorithm is suggested to estimate to rotor position through extract this amplitude. Algorithm performance is confirmed through comparison between simulation result and experimental result
We are consist of amplitude extraction algorithm to radial direction position measurement of rotor. In various amplitude extraction algorithm, algorithm using Discrete Sine and Cosine Transform(DSCT) is realized and performance of this algorithm are verified through Matlab simulation.
We made experimental system that copy from revolution movement of rotor and radial direction displacement. Then, we used dSPACE and Matlab/Simulink for rotating speed control of rotor and data acquisition. Also, noncontact eddy-current sensor added to experimental system and this sensor system evaluated, thereby its output data is compared with output data of hall sensor algorithm. First, to confirm output characteristics of linear hall sensor, we conducted sensor calibration to identify measurable linear range. Then we performed static and dynamic case experiment. As a result, sensor system using linear hall sensor to measure radial direction position of rotor have a measurable linear range of ±1 millimeters and about sensitivity of 11.8V/mm. Also, when it has 0.167 maximum ratio of rotating frequency and revolution frequency, rotor movement that has eccentricity of rotor, amplitude extraction algorithm can extract amplitude information in hall sensor signal. Due to variable window size, this affect to performance of amplitude extraction algorithm.
We need to additional research to robust amplitude extraction algorithm for change rotating and revolution frequency and sensing system need to decrease output noise of hall sensor. Due to disagreement of rotating axis and manufacturing error, experimental system occurred vibration. we need an additional study to resolve this problems.