Dual-current-injection CSCC Active Common-mode EMI Filters with High Insertion Loss for DC-DC Converters

Abstract

With the increase in the switching frequency and power density, DC-DC converters encounter more severe electromagnetic interference (EMI) problems. To suppress the common-mode EMI generated by converters, as well as maintain the high-power-density of converters, the active EMI filter (AEF) has attracted increasing interest owing to its small volume. The EMI suppression effect of the common single-stage single-sense single-injection AEF is confined because of the limited insertion loss, and the volume of the multi-stage AEF will be bulky. To solve this problem, this paper proposes a compact dual-current-injection current-sense current-compensation (DCJ-CSCC) AEF to increase the insertion loss in the entire conducted EMI frequency band, as well as considering the volume of the AEF. The structure and operating principle of the proposed AEF are introduced. Finally, taking a boost converter as an example, the effectiveness and advantages of the proposed DCJ-CSCC AEF were verified through a simulation and experiment, the results show that the proposed AEF has a better EMI suppression effect on the entire conducted EMI frequency band with a similar volume compared with existing single-injection feedforward current-sense current-compensation (FF-CSCC) and feedback current-sense current-compensation (FB-CSCC) AEFs. This paper provides a new selection for EMI suppression in DC-DC converters.