A new approach for harmonic filtering in high power applications

This paper presents a new approach to harmonic filtering in high power applications. Harmonic filtering is based on the hybrid filter that is connected in parallel with the nonlinear load. The hybrid filter consists of an active filter that is connected in a series with the passive LC shunt circuit using a coupling transformer. The presented hybrid filter is controlled by a technique that suppresses the harmonic contents of the supply current of the nonlinear load. The control method presented is based on dynamically varying impedance. The method is designed especially for high power applications because the power rating of the needed active filter is remarkably smaller than that of the load. The computer simulations of the three-phase nonlinear load are presented in order to validate the functionality of the method.