Common mode noise modeling and its suppression in ultra-high efficiency full bridge boost converter

In this paper, common mode noise modeling of low-voltage high-current isolated full bridge boost dc-dc converters intended for fuel cell application is presented. Due to the tightly coupled primary and secondary windings of the transformer, such converter has inherently large capacitive coupling between input and output which is normally associated with high common mode noise generation. In this work, common mode noise sources in the converter are identified, and a common mode noise model is developed. Based on the established noise model, a practical CM filter is designed to comply with the CISPR-A requirements. Finally, a 3kW dc-dc converter including filters has been built and tested to verify the theoretical model. Experimental results confirm the theoretical analysis of the converter.