EMI Suppression of a DC–DC Converter Using Predictive Pulsed Compensation

Rising voltages and wide bandgap semiconductors represent the main cause for rising electomagnetic interference (EMI) emissions of dc–dc converters in electric vehicles. Conventional passive filters are the limiting factor for the improvement of the power density and conventional active EMI filters are quite complex. This article presents a method in order to compensate the EMI generated by a dc–dc converter using a simple half-bridge gate-driver IC. The compensation signal is synchronized to the converter's switching events and injected through two capacitors at the converter's input nodes. Unlike analog active EMI filters, this method is able to compensate time delays of the filter's hardware components. This article presents an approach to describe such a compensation system analytically. Therefore, bandwidth and attenuation are determined due to the synchronization error and pulse amplitude. The presented prototype system and the analytical prediction are validated by measurements at the stationary operation of the converter in a CISPR 25 test setup. Finally, the performance of the method during dynamic operation of the converter is evaluated to demonstrate the high EMI suppression effectiveness of pulsed compensation.