Research On Integrated Forward Power Conversion Technology Of Input Series Transformer

With the gradual increase in the types of various electrical equipment,various high-voltage input occasions are increasing.Using multiple circuit units in series on the input side can effectively reduce the voltage stress of each device of the high-voltage converter.This article proposes an implementation scheme of input series forward converter based on transformer integration mode for high-voltage input medium and low power occasions.This type of converter consists of N(N?1)double-switch forward circuits connected in series on the input side,and each series circuit shares an integrated power transformer and n(n?1)output circuits.All switch tubes of the converter are turned on and off at the same time,and the coupling effect of each primary winding of the integrated transformer is used to realize the natural balance of the input voltage of each series circuit,and the input voltage equalization effect is not affected by the output circuits of the converter.The article first takes the number of input series circuits N=2 and the number of output circuits n=1 as examples.Under ideal conditions,an in-depth analysis of the working process of the proposed converter in a switching cycle is carried out and compared with the conventional double-switch forward The basic elements of the converter design are summarized.Secondly,the simplified equivalent circuit model of the converter is established based on the coupling of the primary windings of the integrated transformer during the on and off phases of the switch tube,and the Equivalent circuit model,under the assumption that the input voltage difference between each series circuit,the input voltage equalization process of each series circuit is analyzed,and the input voltage change of each series circuit is revealed during the process of returning to the voltage equalization state.Rules,clarify the causes of circulating currents between the series circuits in the process;next,combine the error characteristics of the main device parameters of each series circuit and the non-synchronization of the switching off time of each series circuit to change the converter.The generation mechanism of the input voltage difference between series circuits is analyzed in depth.On this basis,the goal is to reduce the input voltage difference between the series circuits and the circulating flow in the voltage equalization process,and summarize the optimization of the key circuit parameters of each series circuit Design method.Finally,based on the relevant analysis in the article,an experimental prototype of the proposed input series transformer integrated forward converter is built.The experimental prototype consists of three double-switch forward circuits connected in series on the input side.There are four secondary sides of the integrated transformer.No.DC output circuit.Using the experimental prototype built,the two cases of input series circuit number N=2 and N=3 are systematically studied.The experimental results verify the feasibility of the method proposed in this paper and the correctness of the theoretical analysis.