Finite Control Set-Model Predictive Speed Control for Induction Motors with Optimal Duration

This paper presents a new speed control method for the induction motor (IM) following the finite control set-model predictive control (FCS-MPC) strategy. It adopts the cascaded control scheme, which consists of an inner model predictive torque control (MPTC) loop and outer model predictive speed control (MPSC) loop using two individual cost functions. This control approach implements a maximum torque per ampere (MTPA) operation in a wide speed range, which includes flux-increased and flux-limited modes. The MPSC produces the required torque to drive the IM at the reference speed. This torque is taken as the input of the inner MPTC, which in turn generates the optimal finite set of control input voltage. The control signals of the two MPC are constrained with the maximum limits of the system. The state feedback is achieved with a standard Kalman Filter, which estimates the non-measured load torque. The proposed control system is implemented and validated in experimental environment. The behaviour of the control system is evaluated by applying reference and disturbance steps to the system in different operational modes.