Cascade Sliding Mode Torque Control of a Permenant Magnet Synchronous Motor

This paper presents the direct torque control (DTC) of an interior permanent magnet synchronous motor (IPMSM) based on sliding mode technique. Two adaptive sliding mode controllers are designed; one is used for regulating the motor speed and the other is dedicated for controlling the electromagnetic torque. Consequently, the demerits of classical DTC (large torque and current ripples due to sector changes, low speed problems, and sensitivity to uncertainties) could be avoided in the proposed scheme. The control law of each sliding controller has been designed in such a way that the chattering effects associated with the classical sliding mode are reduced to a great extent. Also, the reaching phase could be eliminated using the idea of total sliding mode control. Moreover, a simple adaptive algorithm is used to estimate the upper bound of lumped uncertainty. The stability analysis of the proposed control system is carried out using Lyapunov stability theorem. The feasibility and effectiveness of the proposed system have been demonstrated through computer simulations. A comparison between the proposed system and conventional techniques has been made in order to confirm the validity of the proposed approach. The superiority of the proposed system has been proved through comparative simulation results.