FPGA-based fuzzy sliding mode control for sensorless PMSM drive

This paper presents an observer-based fuzzy sliding mode controller for sensorless Permanent Magnet Synchronous Motor (PMSM) drive based on the Field Programmable Gate Array (FPGA) technology. For enhancement of robustness, a sliding mode observer (SMO) is proposed to estimate first the current and back electromotive force (EMF), then to derive the flux angle. These estimated values together with the computed rotor speed of the motor are fed back for the control purpose in both the current loop and the speed loop. To cope with dynamic uncertainty and external load, a fuzzy sliding mode control (FSMC) is designed by incorporating a fuzzy inference mechanism into the proposed sliding mode control scheme to tune the discontinunous gain in the speed control loop. An FPGA chip is designed for implementing the vector-controlled current loop as well as the speed control loop. The very high speed integrated circuit-hardware description language (VHDL) is adopted to describe advantageous behaviors of the proposed control system. By integrating advantages of the sensorless and fuzzy sliding mode control techniques into the speed controller of a PMSM drive, its performance can be substantially enhanced while improving cost-effectiveness and reliability. The validity of the proposed approach is verified through results based on the VDHL Modelsim and Simulink co-simulation method.