Digital Sliding Mode Torque Control for Induction Servo Drives

This paper describes a sliding mode torque controller for voltage source inverter fed squirrel cage induction motors. Flux imposition is achieved through reactive torque control. The inverter switching commands are derived from the active and reactive torque comparator outputs and from the equivalent machine voltage. The theory of sliding mode control is used to describe the behaviour of the control structure. The torques are determined using a state space observer. All mathematical analysis is done by using complex variables representing the space vectors. A fully digital realization of the control method, based on dedicated hardware, is studied.