Passivity-based adaptive backstepping PI sliding-mode position control for synchronous reluctance motor drives

A passivity-based adaptive backstepping PI sliding-mode position control is proposed in this paper for a synchronous reluctance motor (SynRM) drive system. Firstly, a nonlinear model of the SynRM is derived with the lumped uncertainty. Through adaptive backstepping feedback passivation, the whole closed-loop position control scheme is shown to be feedback equivalent to an output strictly passive system with designated control inputs and an extended storage function. An adaptive backstepping PI sliding-mode controller is then designed to control the position such that the chattering phenomenon associated with traditional sliding-mode position controls using signum function can be attenuated within the boundary layer. The maximum torque per ampere (MTPA) condition is satisfied through design of d- and q-axis currents, which serve as the control inputs to the motor. Asymptotic stability of the closed loop system is proven by passivity theory and Barbalat's lemma. Simulation results show good position tracking and performance.