Study of Sensorless Field-Oriented Control of SPMSM Using Rotor Flux Observer & Disturbance Observer Based Discrete Sliding Mode Observer

This paper presents the development of position sensorless field-oriented control (FOC) algorithms for surface mount permanent magnet synchronous motors (SPMSMs). Position estimation is achieved using two methods: Rotor Flux Observer (FO) and Sliding Mode Observer (SMO). An application of Disturbance observer-based Sliding Mode Observer (D-SMO) for FOC of PMSM, which overcomes the limitations of conventional SMO for discrete-time implementation, is also introduced. Both sensorless methods are mathematically evaluated and analyzed using only two current sensors, providing cost and reliability advantages over additional voltage and position sensing circuitry. The methods are validated via computer simulations and hardware implementations on three 24V, 100W, SPMSM motors satisfactorily.