*Article* **Comparative Evaluation of Wide-Range Soft-Switching PWM Full-Bridge Modular Multilevel DC–DC Converters**

#### **Jingwen Chen, Xiaofei Li, Hongshe Dang \* and Yong Shi**

School of Electrical and Control Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China; chenjw@sust.edu.cn (J.C.); lxiaofei1214@163.com (X.L); shiyong@sust.edu.cn (Y.S)

**\*** Correspondence: danghs@sust.edu.cn

Received: 26 December 2019; Accepted: 27 January 2020; Published: 31 January 2020

**Abstract:** This paper discusses some wide-range soft-switching full-bridge (FB) modular multilevel dc–dc converters (MMDCs), and a comparative evaluation of these FB MMDCs is also presented. The discussed topologies have all merits belonging to conventional FB MMDCs, e.g., smaller voltage stress on the primary switches, no added primary clamping devices and modular primary structure. In addition, the primary switches in each converter can obtain zero-voltage switching (ZVS) or zero-current switching (ZCS) in a wide load range. Two presented topologies are selected as examples to discuss in detail. The proposed FB MMDCs are assessed and evaluated based on performance, components and topology structure indices, such as soft switching characteristics, current stress, power loss distribution, number of added devices, complexity of structure and added cost. Experimental results are also included to verify the feasibility and advantages of the new topologies.

**Keywords:** full bridge (FB); modular multilevel dc-dc converters (MMDCs); zero-voltage switching (ZVS); zero-current switching (ZCS)
