Study on Input-series and Output-series Buck DC-DC Converter

In recent years, the system integration technology of power electronics has been received more and more attention, and the serial and parallel technology of standard module is one of the main research branches. There are four kinds of basic structures as follows: (a)input parallel and output parallel; (b)input parallel and output series; (c)input series and output parallel; (d)input series and output series. Their standard module can be dc-dc converter, inverter, rectifier and frequency converter.This paper focused on the structure of input series and output series, with the basic dc-dc Buck converter as its standard module. Compared with the basic Buck dc-dc converter, this converter can effectively reduce voltage stress of switches and inductor current ripple when they have the same input and output; and interleaved control technology can reduce output voltage ripple in order to improve the power density of the converter. Therefore, this converter is suitable for the high power occasion of high voltage input and high voltage output.Firstly, this paper introduced the research background and research situation of four kinds of combined converter, and gave the content and significance. Secondly, operating principle and performance characteristics of input series and output series Buck dc-dc converter were analyzed; meanwhile, the relationship between input sharing-voltage and output sharing-voltage was discussed on matching parameters. Thirdly, on the basis of analyzing the factors of influencing the input voltage sharing and out input voltage sharing, this paper studied the feasibility of two control methods: input voltage-sharing and output voltage-sharing. The results showed that the input voltage-sharing method can ensure the output voltage-sharing, but oppositely, it would fail. Finally, the small signal model and decoupling analysis of this converter were obtained by using the input voltage-sharing control method; and then designed its main circuit and control circuit, whose correctness and effectiveness were verified by Saber simulation software. Furthermore, an experimental prototype was made on the basis of simulation verification. The simulation and experimental results verified the correctness of the designed main circuit and effectiveness of the input voltage-sharing strategy.