An Active EMI Filter in Grounding Circuit for DC Side CM EMI Suppression in Motor Drive System

In this article, an active electromagnetic interference (EMI) filter is designed to reduce the dc side common mode (CM) EMI in motor drive system. Different from the traditional passive EMI filter which is added in the main circuit, the designed active EMI filter (AEF) in this article is added in the grounding circuit which is connected between motor frame and the ground and it can be decoupled from the main circuit. By properly setting the components value, the dc side CM EMI can be suppressed while maintaining a low motor frame voltage. The structure of the AEF is simple and the volume of the AEF can be kept small. The operation principle of the AEF is introduced first and the performance of this AEF is evaluated through simulation. Experiment results verified the effect of this AEF that it can suppress the dc side CM EMI and the motor frame voltage can be kept low.