Novel current control scheme with deadbeat algorithm for three-phase current-source active power filter

Abstract

For an active power filter (APF), the three-phase current source PWM converter is not always used in place of three-phase voltage source PWM converter with voltage regulated DC capacitor. This is due to the difficulty of current control implementation for current source PWM converters. In this paper, an effective method to apply a three-phase current-source PWM converter with a deadbeat controller to an APF is presented. In this APF, the compensation of current harmonics is attained by setting the control purpose, compensating the instantaneous reactive current component in the load current and reducing the ripple in the instantaneous effective current component. In a three-phase current source PWM converter, the time-optimal response of the utility AC grid side input current is two-dimensional finite time settling response, in which two sampling periods are required for a settling time. To cancel this delay, and one more delays caused by the DSP control strategy, a reference value three sampling periods ahead has to be predicted. For this prediction, the reference value detected previously can be useful, because the waveform of harmonic current is periodical in many cases. Finally, it is proven, from an experimental point of view, that the compensating ability of this APF is very high.