A novel source-current detection type active filter equivalent to load-current detection type

Active filters can be classified as load-current and source-current detection types. The viewpoint that the former type acts in open loop, while the latter acts in closed loop, is quite common. However, in this paper, by taking into consideration the current control loop of the active filter, it is revealed that both the load-current and the source-current detection types are equivalent, i.e., they can be transformed into each other. The source-current detection type active filter is, however, superior when considering the disturbance caused by the non-ideal characteristic of current sensors. The source-current detection type active filter proposed in this paper needs no fast current control loop, as usually needed in the conventional active filters, its structure is simple, and selective or total harmonic cancellation can be obtained. Stabilization of the proposed active filter is also discussed, and experiment is carried out to verify the feasibility of the designed active filter.