Position Estimation in Salient PM Synchronous Motors Based on PWM Excitation Transients

Abstract—This paper presents a position and speed estimation algorithm based on magnetic saliency of permanent-magnet syn-chronous motors. The proposed method uses inherent high-fre-quency content of motor pulsewidth-modulation (PWM) excita-tion to measure position-dependent inductance parameters, which are then processed using a simple nonlinear observer to produce the position and speed estimates. To ensure persistent excitation at all operating voltages (speeds), a novel PWM algorithm with full voltage output is developed and presented. The efficiency of the modified excitation was evaluated and compared to the efficiency of the standard position-sensorless motor drive excitation. Experi-mental results are presented as well, showing good algorithm per-formance in a wide speed range, including zero, and for various load torques. Index Terms—Motor drives, permanent-magnet (PM) motors, position estimation, position-sensorless control. I