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.