A Self-Sensing Active Magnetic Bearing Based on a Direct Current Measurement Approach

Sensors

Andries C. Niemann¹  George van Schoor¹ 

[1] School of Electrical, Electronic and Computer Engineering, North-West University, 11 Hoffman Street, Potchefstroom 2531, South Africa;

关键词: self-sensing;    active magnetic bearing (AMB);    direct current measurement (DCM);    position estimation;    magnetic suspension;    duty cycle;   

DOI  :  10.3390/s130912149

来源: mdpi

【 摘 要 】

Active magnetic bearings (AMBs) have become a key technology in various industrial applications. Self-sensing AMBs provide an integrated sensorless solution for position estimation, consolidating the sensing and actuating functions into a single electromagnetic transducer. The approach aims to reduce possible hardware failure points, production costs, and system complexity. Despite these advantages, self-sensing methods must address various technical challenges to maximize the performance thereof. This paper presents the direct current measurement (DCM) approach for self-sensing AMBs, denoting the direct measurement of the current ripple component. In AMB systems, switching power amplifiers (PAs) modulate the rotor position information onto the current waveform. Demodulation self-sensing techniques then use bandpass and lowpass filters to estimate the rotor position from the voltage and current signals. However, the additional phase-shift introduced by these filters results in lower stability margins. The DCM approach utilizes a novel PA switching method that directly measures the current ripple to obtain duty-cycle invariant position estimates. Demodulation filters are largely excluded to minimize additional phase-shift in the position estimates. Basic functionality and performance of the proposed self-sensing approach are demonstrated via a transient simulation model as well as a high current (10 A) experimental system. A digital implementation of amplitude modulation self-sensing serves as a comparative estimator.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.