Improved Position Estimation Method for SRM Considering Current Measurement Errors

Abstract

Saturation and current measurement errors will decrease the accuracy of rotor position estimation for switched reluctance motor (SRM). To avoid the drawbacks, a rotor position estimation method based on the unsaturated inductance reconstruction is proposed considering current measurement errors. Firstly, the incremental, apparent and unsaturated inductances are analyzed. The unsaturated inductance is calculated with the similar triangle solution in normal condition during the linear inductance rising region. To avoid the pulse injection, the linear regression algorithm is used to calculate the virtual unsaturated inductance in the linear inductance falling region of adjacent phase. Then the complete rotor position in each electric period is obtained by combining the estimated position of three phases. Secondly, the influence of current measurement errors on rotor position estimation is analyzed. The offset error is directly avoided by detecting the zero-value region of phase currents. The scaling error is compensated by balancing the amplitudes of three phase unsaturated inductances. The proposed method does not need additional hardware and can avoid the influence of saturation and current measurement errors simultaneously. Experimental results validate the effectiveness of the proposed method.