Position Estimation for Self-Sensing Magnetic Bearings Based on Double Detection of Current Slopes

This paper introduces a new approach to estimate the rotor position of self-sensing magnetic bearings, which works on detecting the current slopes during both positive and negative voltage switching of PWM amplifiers. The position is estimated using the current slopes straightforward. The consideration of double current slopes shows advantages concerning the reduction of the influences of the coil resistance and the induced voltage due to the rotor movement. The current slope is calculated by multiple current sampling, therefore, no additional hardware is needed for the current slope measurement. Experimental results verified the proposed approach.