Finite-control-set model predictive direct torque control with extended set of voltage space vectors

Abstract

The finite-control-set model predictive direct torque control (FCS-MPDTC) is a novel and promising control scheme for permanent magnet synchronous motors (PMSMs). An important feature of FCS-MPDTC is that the eight possible voltage space vectors or switching combinations of the power converters are directly taken into account as the control input of the system. Due to the considerable torque and flux ripples, to improve the performance of FCS-MPDTC, this paper presents an extended set of twenty modulated voltage space vectors with fixed duty ratio. To mitigate the computational burden caused by increased number of voltage space vectors, a pre-selective scheme is designed for the proposed FCS-MPDTC to filter out the impractical voltage vectors instead of evaluating all twenty voltage space vectors. The drive system efficiency of conventional direct torque control (DTC), conventional FCS-MPDTC and proposed method are investigated. A stator current minimisation scheme is also proposed to further increase the system efficiency.