A new parallel hybrid filter configuration minimizing active filter size

Conventional parallel hybrid active filters suffer from the problem of heavy current ratings of devices used in the inverter. In general, this problem has been solved by adjusting the turn ratio of a matching transformer. However, adjusting the transformer to a high turn ratio may not be possible for high voltage power systems due to their requirements for high voltage insulation. In this paper, a new configuration is proposed for a parallel hybrid active filter. In the proposed hybrid active filter, the active filter is connected to the passive filter inductor in parallel through a matching transformer with the aim of reducing the current rating of the inverter. As a result, the fundamental component of the current flowing through the passive filter is divided by the parallel paths of two inductors located at the inverter side and passive filter side, respectively. Hence, the current rating of the inverter can be reduced. Additionally, a harmonic elimination method is suggested for the proposed active filter. Through computer simulations and experiment, we have verified the effectiveness of the proposed topology