Discrete-Time Modeling and Control Based on Field Orientation for Induction Motors

In this article, discrete-time direct and indirect field-oriented controllers (FOCs) for induction motors (IMs) are designed. Based on a discrete-time stationary reference frame model for IMs, which was obtained by means of a variational integrator, the stationary model is oriented to the field. Then, discrete-time FOCs, in the direct and indirect versions, are designed for tracking of reference signals for the rotor velocity and the rotor flux modulus. A simulation study was carried out, and for comparison purposes, discretized continuous-time FOCs were also simulated for three sampling periods. It was put in evidence that the proposed discrete-time controllers performed better than the discretized counterparts when the sampling period was increased. Real-time experiments were carried out for discrete-time direct and indirect FOCs, where their performances were similar to those predicted by simulations.