A sensorless stable V/f control of SPMSM based on constant power factor control with a novel MTPA tracking

Abstract

The paper presents a sensorless stable V/f control strategy of surface permanent magnet synchronous motor (SPMSM), where the maximum torque per ampere (MTPA) condition is satisfied by controlling the d-axis current to zero. However, to directly control the d-axis current, it is necessary to know the exact rotor position, which is not possible in sensorless V/f control. Based on this fact, a constant power factor (CPF) control loop in voltage vector reference frame dvqv with a novel MTPA tracking according to a look-up table (LUT) was developed. The LUT was created based on a set of experimental measurements to store the motor power factor where MTPA is reached. The proposed stable V/f control strategy shows an accurate MTPA tracking of SPMSM in the entire operational range verified by experiments.