PMSM Sensorless Control System Based on DTC Using FLC and Luenberger-PLL Observer

Starting from the desire to achieve a good control performance of the Permanent Magnet Synchronous Motor (PMSM), but with a relatively medium complexity of the control system, this paper presents a sensorless control structure of a PMSM using the Direct Torque Control (DTC) control strategy. In order to improve the performance of the Luenberger observer used for speed estimation, a Phase Locked Loop (PLL) observer is additionally used which, due to the integral nature of the control system, ensures a better estimation of the PMSM rotor speed. In addition, the classic PI controller used for speed control is continuously adjusted by a Fuzzy Logic Controller (FLC). In contrast to the usual case where the input to the fuzzy controller is given by the speed error and its derivative, this paper proposes a second fuzzy controller which additionally uses an input provided by a load torque observer. The superior performance of the proposed PMSM sensorless control system is demonstrated by numerical simulations in both stationary and dynamic modes.