Double-Frequency Buck Converter

Abstract

Improving the efficiency and dynamics of power converters is a concerned tradeoff in power electronics. The increase of switching frequency can improve the dynamics of power converters, but the efficiency may be degraded. A double-frequency (DF) buck converter is proposed to address this concern. This converter is comprised of two buck cells: one works at high frequency, and another works at low frequency. It operates in a way that current in the high-frequency switch is diverted through the low-frequency switch. Thus, the converter can operate at very high frequency without adding extra control circuits. Moreover, the switching loss of the converter remains small. The proposed converter exhibits improved steady state and transient responses with low switching loss. An ac small-signal model of the DF buck converter is also given to show that the dynamics of output voltage depends only on the high-frequency buck cell parameters, and is independent of the low-frequency buck cell parameters. Simulation and experimental results demonstrate that the proposed converter greatly improves the efficiency and exhibits nearly the same dynamics as the conventional high-frequency buck converter. Furthermore, the proposed topology can be extended to other dc-dc converters by the DF switch-inductor three-terminal network structure.