A Comparison of Predictive Current Control Schemes for MV Induction Motor Drives

In medium-voltage drives the switching frequency is limited to a few hundred Hz, necessitating control and modulation schemes capable of producing low levels of current and torque distortions at low switching frequencies. Model Predictive Direct Current Control (MPDCC) has emerged as a promising scheme for medium-voltage induction-motor drives. By forecasting the trajectory of the stator currents over a timespan known as the prediction horizon, MPDCC regulates the stator currents within a set of hysteresis bounds while minimising the inverter switching frequency. Despite the recent surge in popularity of predictive control, such schemes in the field of power electronics and drives were proposed already in the early 1980's. Forced Machine Current Control (FMCC) is an early predictive current control scheme which shares several similarities with MPDCC. However, a comprehensive review and comparison of FMCC with the modern MPDCC scheme has never been carried out. Through simulation, it is shown that the steady state performance of MPDCC and FMCC is similar when the prediction horizon of the former is limited. However, when the prediction horizon is extended, the performance of MPDCC is shown to be superior to FMCC, the horizon of which is inherently restricted.