Model predictive direct speed control with finite control set of PMSM-VSI drive systems

Abstract

Servo drives and drives for position control require a high dynamic on speed control. In this paper, Model Predictive Direct Speed Control (MPDSC) is proposed which overcomes limitations of cascaded linear controllers. The novel concept predicts the future current and speed states in discrete steps and it selects plant inputs which depends mainly on the predicted speed error. Secondary control objectives, such as maximum torque per ampere tracking are included. MPDSC uses the finite control set approach which makes it suitable for online predictions with a prediction horizon of a few sample periods. The concept has been implemented and verified by simulation. The overall control behavior is evaluated applying reference and disturbance steps to the system, where MPDSC shows promising results. A solution for disturbance (e.g. load toque) handling is proposed and the effectiveness to avoid control offsets is shown. Furthermore, the dynamic performance and the steady-state behavior of MPDSC is evaluated and discussed.