Multilevel buck dc-dc converter for high voltage application

This paper presents a nonisolated multilevel step-down dc-dc converter suitable for high voltage application. The main features of this topology are: low voltage across the semiconductors; low switching losses and reduced volume of output filter. This paper focuses on the five-level structure of the proposed converter, in which the theoretical analysis is carried out and discussed. The five-level proposed dc-dc converter has four capacitors and their voltages should be balanced for its correct operation. Therefore, a capacitor voltage balancing active control is presented and analyzed in detail herein. In order to demonstrate the performance of this converter, experimental results for a prototype of the 700-V input voltage to 450-V output voltage, 5-kW rated power and switching frequency of 20 kHz are reported herein.