Bidirectional Active EMC Filter for Industrial Power Converters

Size and cost of EMC filters of power converters can be reduced using active circuits. In this work we demonstrate the filter performance of a bidirectional active EMC filter in an industrial 75kW power converter driving a motor. The active filter is bidirectional since it suppresses EMC noise on either side of the filter. The voltage noise source on the grid side stems from magnetic coupling between input and output of the converter. For a purely passive EMC filter, grid side noise needs to be filtered by large inductors. We show that the active filter which is based on current sensing and current injection strongly reduces the magnetic filter components required.