DC magnetic deviation in the matching transformer of a series active filter, and its suppression

This paper deals with a series active filter for harmonic‐current compensation of a large‐capacity diode rectifier with a capacitive load. Flux saturation may occur in a series matching transformer for connecting the series active filter to the ac side of the diode rectifier. This paper develops an analog controller of a dc magnetizing current flowing in the matching transformer, along with a model for the controller, to avoid the flux saturation. Operating characteristics of the controller are theoretically and experimentally discussed, taking into account both an offset voltage in the controller and an error in a current sensor. Finally, this paper discusses a relation between magnetizing characteristics of the matching transformer and the amplitude of the magnetizing current. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 144(2): 63–72, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10188