Active EMI-Filter using the Gate-Drivers Power Supply

All Power Electronic circuits suffer under the presence of Electromagnetic Interference (EMI) which are caused by the rapid switching of the power switches, which are used to modulate an average voltage over a switching period. The common strategy to reduce the effects onto connected circuits or the utility grid is to use EMI filters. Advanced strategies use active EMI filters which compensate the EMI influence onto the circuitry by inducing the opposed EMI creating current into the circuit, which ideally results in cancellation. This paper presents a new approach which directly uses the gate control signals to generate these opposed commands. Additionally this approach uses the low voltage driver supply for these commands to reduce the component cost, the needed isolation and complexity of the overall circuitry. The described concepts are underlined with measurements on a downscaled full bridge inverter.