A Novel Parallel Inductor Type Hybrid Active Power Filter and Its Control Strategy

A topological structure of a parallel inductor type hybrid active power filter for three-phase circuit is proposed and its working principle is analyzed,meanwhile the comparative research on three control strategies for such a topological structure is carried out.By means of equivalent transformation of circuit,the behaviors of the proposed hybrid active power filter under different control strategies are revealed.Firstly,via coupling transformers,the active parts of this hybrid active power filter are in parallel with additional inductors,then the parallel components are connected in series with passive power filter to compose hybrid active power filter,finally the hybrid active power filter is connected in parallel with power network.The additional inductors provide the path for fundamental current of the filter branch and the active filter is controlled as a harmonic current source,thus the fundamental current will be forced to flow into additional inductor while only harmonic currents pass through active filter,thus the capacity of active filter can be effectively decreased,for this reason it makes the active filter suitable for the occasion of high power.The proposed topology and three kinds of control strategies are validated by experiments and simulation with laboratory prototype of the proposed hybrid active power filter,and simulation and experiment results show that the proposed hybrid active power filter can effectively suppress harmonics,besides,among the three control strategies the compound control can provide the best filtering effect.