Virtual flux based direct power control of a three-phase rectifier connected to an LCL filter with sensorless active damping

Abstract

This paper proposes a simple method for connecting an LCL filter to a three-phase pulse-width modulation (PWM) rectifier with direct power control space vector modulation (DPC-SVM) strategy. The goal is to improve the transient response and reduce the harmonic distortion, as well as size and cost reduction of the input filter. Since the proposed method is sensorless, the AC line voltage sensors are eliminated and the virtual flux block would be used instead. The cost and size of the filter could be reduced since the LCL-filter has lower inductance values and also the harmonic distortions could be reduced as well. The only drawback of the LCL-filter is producing resonance oscillations due to the resonance frequency of its third-order transfer function. In order to eliminate the oscillations, a simple method of active damping is utilized. Finally, simulation results have shown an excellent dynamic response compared with a three-phase converter that uses a conventional L-filter.