Rotor Position Estimation of PMSM for Low and High Rotor Speed

Abstract

In this paper, a sensorless permanent magnet synchronous motor (PMSM) drive was presented based on calculating the back EMF using the reference stator voltages which are the outputs of PI current controllers. Sensorless control estimates the position information necessary for vector control of the motor without estimation of position sensor or encoder. This can provide effects such as increased system reliability, cost and volume reduction. The back EMFs are calculated in a new coordinate based on the estimated speed to minimize the rotor speed estimation error. The estimated rotor position and rotor speed may fail to track the real rotor position and real rotor speed in very low speed, so a compensator was added to the detector to overcome this disadvantage. In order to verify the validity of the proposed sensorless control technique, an experiment was performed on the PMSM and the results showed the fast-dynamic response, low ripples in motor’s currents as well as good performance in tracking speed and power references.