Integration of Measurement Vector Insertion With Discontinuous PWM to Improve Saliency-Based Sensorless Drive Position Estimation

Saliency-based position sensorless machine drive with the pulsewidth modulation (PWM) voltage switching frequency injection has advantages of high estimation bandwidth and low acoustic noise. However, multiple currents must be sampled every PWM cycle for spatial saliency calculation. Besides, the switching frequency voltage injection distorts the symmetric PWM voltage pattern. For these saliency-based drives, the PWM injection is the tradeoff between the transient estimation bandwidth and steady state estimation error. This article proposes a modified PWM voltage injection through the measurement vector insertion (MVI) for sensorless position estimation. By integrating the MVI with discontinuous PWM, the proposed injection maintains the symmetric PWM voltage for machine control. This MVI-based PWM (MVIPWM) improves the saliency-based drive among voltage harmonics, current harmonics, and position estimation error. The proposed MVIPWM injection is compared to other PWM injection methods on an interior permanent magnet machine. All advantages of MVIPWM on the saliency-based drive are verified by experimental results.