Reduced Switch Inverter-Fed Sensorless PMSM Drive With Multistage MRAS Speed Estimator Based on Stator Flux and Electromagnetic Torque

In this article, a multistage model reference adaptive system (MRAS) speed estimator is formulated based on stator flux and electromagnetic torque (EMT) quantities is proposed for reduced switch inverter (RSI)-fed sensorless permanent magnet synchronous motor (PMSM) drive. The proposed configuration aims to eliminate speed sensor and reduce the switching losses and overall cost of the system. The proposed MRAS speed estimator is developed by utilizing instantaneous value of EMT and stator flux. The proposed speed estimator’s stability is verified using the small signal model technique. The experimental results demonstrate the performance of the proposed scheme for laboratory prototype 400-W PMSM drive. Furthermore, the machine parameter sensitivity is tested to show the robustness of the speed estimator. It is inferred that the estimated position and speed error are 5.1° and 3.8 rad/s during entire speed region at transient condition.