Comparison of structure topologies for hybrid filters

The hybrid filter is a combination of a passive filter and a small-rated active filter, which gives a relatively economical approach comparing to a conventional active filter. The initial cost and the operation switching loss of the filter are proportional to the rating of the active filter. Different structures of passive filters in a hybrid filter have different required ratings of the active part of the hybrid filter. Based on the pervious researches, there are many different topologies of a hybrid filter. They can be mainly classified as: series-type, b-shape and parallel-type hybrid filters. In this paper, a comparison among different structure topologies of hybrid filters is performed. The guidelines are given for the selection of hybrid filter topologies. Computed and simulated results show out its validity of the discussion in this paper.