Improving electromagnetic compatibility of integrated switching converters for hybrid/electric vehicles

Practical techniques to reduce electromagnetic interference (EMI) for integrated DC/DC converters are discussed in the paper. As application case study a 48 V DC/DC converter for electric/hybrid cars is considered. Firstly, an EMI filter with very low values of inductor is designed to facilitate its integration and to reduce the overvoltage issues. Experimental results prove that the proposed EMI filter design procedure, taking into account the source and terminal impedance, avoids the state-of-art tendency of over-designing EMI filter components. Then, EMI is reduced further by integrating in the DC/DC converter a soft-start technique, which mitigates EMI issues reducing by 3 times the currents spikes at the car's power on.