University of Minnesota

Mukul Rastogi

Ned Mohan

An apparatus and method for reducing distortion currents present in an alternating current power system supplying power to a load which includes a passive filter and an active filter. In a first embodiment, the passive filter is operably connected to the power system across the load by a switching device. An active filter is then connected across the switching device and operated to draw a current equal to the current through the passive filter. The active filter and the passive filter are thereby connected in series across the load. The active filter is controlled to draw a fundamental frequency component and to provide distortion currents required by the load. In a second embodiment, the active filter is connected in parallel with a first circuit, the parallel combination of which is connected in series with a second circuit across the load. Besides providing distortion currents required by the load, the active filter is controlled to draw a current substantially in phase with the voltage across it in order to provide damping.

Growing community of inventors

Minneapolis, MN, United States of America

Mukul Rastogi