Sensorless position control of active magnetic bearings based on high frequency signal injection method

This paper proposes a novel method to estimate the position of suspended body that hovers due to the electromagnetic force. The position information of the suspended body can be extracted from the coil currents, which contain the high frequency components due to the injected high frequency voltage without any additional hardware. The control of coil currents and the position of suspended body is performed with the digital controller using DSP. The effectiveness of the position estimation and control strategy without displacement sensors has been verified by simulation and experimental results.