Sensorless speed control of PMSM drive using nonlinear sliding mode observer with position estimation based on quadrature PLL

This article presents a novel technique to improve the system response utilizing a sensorless Nonlinear Sliding Mode Observer and a Quadrature Phase-Locked Loop (NLSMO and QPLL) controller. Rather than using a conventional PI controller, a Sliding Mode Controller (SMC) and an Extended State Observer (ESO) are used to compute the speed. Speed controller (PI based) requires fine tuning to operate PMSM drive in all speed ranges, whereas using the SMC + ESO method can compute it, based on some parameters calculated for wide speed ranges. The SMC + ESO approach assimilates the concept of sliding surface function control and the system state variables. The QPLL provides advantage in position estimation which reduces loop filter requirements. The NLSMO + QPLL technique allows synchronization to be achieved and maintained with a lower-order filter. An NLSMO + QPLL helps reducing the increased chattering caused by high switching gain. To counter the chattering problem and improve the estimation accuracy, the method incorporates an anti-disturbance property. To support the theoretical analysis, simulation and experimental results are presented.