Switched-capacitor voltage boost converter for electric and hybrid electric vehicle drives

This article presents a switched-capacitor (SC) voltage boost converter and its control methods for implementing dc-ac and ac-dc power conversion. The SC converter employs an SC circuit augmented with the main converter circuit to the power source, thus providing unique features that cannot be attained by the traditional voltage-source inverter (VSI) or boost VSI. The additional features include doubling the area of the linear modulation region and eliminating both the large inductor in the boost dc-dc stage and the large filtering capacitor, which leads to a higher energy density and a lower cost. The SC converter concept can be applied to all dc-ac, ac-dc, ac-ac, and dc-dc power conversions. To describe the operating principle and the control, we focus on one example: a bidirectional SC converter for dc-ac and ac-dc power conversion in electric and hybrid electric vehicles. This article is accompanied by a video demonstrating the change of the modulation functions with the value of A.