A Highly Reliable Zeta-Based AC-Link Universal Converter

In this article, a single-stage Zeta-based universal converter is proposed. This converter is capable of stepping up and down the voltage in a wide range. Moreover, this class of converters uses a small inductor along with a very small film capacitor at the link, instead of electrolytic capacitors used in most conventional dc-link converters. Electrolytic capacitors have a shorter lifetime compared to other components of a power electronic converter and their elimination significantly improves the reliability of a converter. The power conversion is carried out in one stage, increasing the efficiency compared to multistage power converters. Due to the small size of the link capacitor, the dynamic response of the proposed converter would be very fast, making the proposed converter suitable for very fast response applications. Furthermore, when isolation is needed, a compact high-frequency transformer can be employed at the link instead of heavy line-frequency transformers to increase the converter's power density. Compared to Ćuk-based universal converters, this topology reduces the link peak voltage on the film capacitor and reduces the size of the filters. This article explains the proposed converter's design and principles of operation, and their performance is evaluated through simulations and experiments.