Analysis and Suppression of Common-Mode EMI Using Synchronous Pulsed Compensation in Power Electronics

A common-mode (CM)-conducted electromagnetic interference (EMI) noise, exhibiting characteristics similar to a pulse signal, is produced during the rapid rise and fall of the drain-to-source voltage of the switching device. In order to eliminate the above CM-conducted EMI, a reverse pulse signal, which is denoted by a synchronous pulsed compensation (SPC) signal, is proposed in this article. First, high-frequency equivalent circuits, based on a SiC half-bridge module, are built to determine the time-domain CM-conducted EMI noise. Then, the impact of digital filter circuits with/without SPC signals on CM EMI noise is analyzed through the calculation of insertion loss (IL). In addition, the design of the SPC signal is described in detail. To implement SPC, a digital active EMI filter (DAEF) system is constructed. Next, the overall experimental setup is elaborated upon. The measurements, performed on a 1000-W buck dc-dc converter prototype, finally confirm the SPC method for CM-conducted EMI suppression in the lower-to-medium frequency range.