Abstract
Permanent magnet synchronous motor (PMSM) drives commonly use a mechanical position sensor, and position sensorless control removes this transducer by reconstructing rotor position and speed from electrical measurements. Fractional order operators have been introduced into observers, speed adaptation laws, position reconstruction loops, disturbance compensators, and feedback controllers to shape the estimation and regulation dynamics. This paper combines the operating characteristics of position sensorless PMSM drives and summarizes the application of fractional order methods in this field, including fractional order sliding mode observation, model reference adaptation, flux and back EMF estimation, and position reconstruction based on phase locked and frequency locked loops, as well as the interaction between fractional order controllers and estimated rotor feedback and the digital realization of non-integer order operators. The reviewed literature shows improvements in selected position error, speed response, and harmonic measures under specified machines, operating points, and baselines; however, component-level convergence does not generally establish stability of the complete output-feedback drive, back EMF methods retain an information limitation near standstill, and simultaneous changes to observers, controllers, and tuning procedures impede attribution to the fractional order element. Based on the current status, the development prospects for fractional order sensorless control are discussed, and the conditions under which a fractional-order design can be assessed reproducibly are identified.