A cascaded three‐level buck‐LLC DC/DC converter with high power density for high‐frequency applications

Abstract

In distributed generation systems, converters play a vital role and DC/DC converter technology is constantly being promoted with the increasing demand for electrical equipment in various industries. A cascaded topology of DC/DC converter has been proposed in this paper, named three‐level Buck‐LLC(TL‐BLLC) converter. In the proposed TL‐BLLC, Buck and LLC circuit are cascaded by a switch and a diode, so that the input voltage of the LLC can be adjusted to three levels. The stability of the output voltage of the whole system depends on the three‐level weight, so the LLC works at fixed frequency, which simplifies the control and ensures the efficiency. At the same time, compared with the traditional cascaded Buck‐LLC, this structure can reduce the processing power and reduce the size of passive elements of the previous Buck. Finally, a 980 W experimental prototype was established and the results of the experiment verified the correctness of the theoretical analysis.