Reducing CM Conducted EMI in Output Filterless WBG Traction Inverters by Means of a Dummy Leg

The design of traction inverters for electric vehicles poses several challenges, particularly in reducing Common Mode (CM) conducted Electromagnetic Interference (EMI) without the use of bulky input filters. This paper proposes a novel approach based on a small dummy leg, which acts as a source of canceling switching noise. By connecting the dummy leg to the motor chassis through a given impedance, CM current cancellation is achieved when active zero state modulations are employed. To this purpose, the design procedure for the impedance loading the dummy leg is proposed, together with an optimized control method of the dummy leg. Experimental results validate the effectiveness of this approach in a real-case scenario, achieving up to up to 30 dB reduction in the 150 kHz-1MHz range, thus reducing the input filter volume and overall system cost compared to conventional solutions.