I. Introduction
Power electronics has undergone much evolution in the last decades [1]. The trends of higher electrification levels and control for commercial, industrial, transportation, and medical applications created a significant increase in its role [2]. Three-phase ac–dc current source converters (CSCs) have been gaining attention in several applications, typically where a single-stage nonisolated converter is able to perform active power factor correction and tight control of the dc-side current. An example of a five-level CSC (5L-CSC) circuit is shown in Fig. 1, where higher performance than a three-level topology can be achieved regarding physical dimensions and efficiency mainly due to potentially lower current efforts and better losses distribution. It can be seen that two conventional three-level six-switch CSCs are connected at their dc ports through two interphase transformers , with . This transformer is used with the aim of dividing the current between the two converters and limit the circulating currents among them. The polarity of the transformer is reversed in order to cancel the local average transformer core flux. Fully separated inductors could also be used in place of the interphase transformers (IPTs) and dc-side inductors while resulting in similar waveforms at the ac- and dc-side ports.