Abstract:

Fly-Buck topology is evolved from the conventional synchronous rectifier buck topology, and an isolated power output can be obtained without an additional feedback loop, thus using this topology could simplify the design process of low power isolated auxiliary power supply. In this paper, based on the Fly-Buck topology circuit, the working principle of Fly-Buck topology is analyzed, and then the theoretical analysis is proved to be correct by circuit simulations. Finally, a power supply prototype based on Fly-Buck topology circuit has been designed for the half-controlled bridge regulation circuit of digital generator. Experimental results including the second side output characteristics validate the feasibility and practicality of this topology. In this paper, it was especially analyzed and studied that the effects of Fly-Buck topology's operating mode on the second side output regulation performance when the primary load is light or empty. The simulation and experiment results show that Fly-Buck topology could ensure a good regulation performance of the secondary side output and follow the primary output by operating in forced continuous mode.

Key words: Fly-Buck, synchronous rectifier buck topology, auxiliary power supply, forced continuous mode