Research On Interleaved Parallel DC-DC Converter Based On Coupled Inductors

With the vigorous development of marine resources,the problem of power supply for underwater equipment has become more and more serious.As a clean and sustainable power source,seawater batteries have the advantages of high specific energy,safety,and low cost.However,in practical applications,open seawater batteries cannot be used in series,and the output voltage of a single seawater battery is low,which requires adding a high boost ratio DC-DC converter at the back end of the seawater battery to boost its output voltage to meet electricity demand of marine equipment,and high conversion efficiency must be ensured while achieving high boost.Based on the application of seawater batteries in low power applications,this paper discusses and summarizes the characteristics of isolated and non-isolated DC-DC converters proposed by domestic and foreign researchers.Considering the output characteristics of seawater batteries,a new method is proposed.Interleaved parallel DC-DC converter based on coupled inductors.The converter can achieve high boost ratio and high efficiency under the condition of non-limit duty cycle,and has the advantages of small input current ripple and low power device stress.This paper analyzes the working principle and working mode of the converter,and flexibly applies the volt-second balance and ampere-second balance principles to deduce the boost ratio of the converter and the voltage and current stress of switches,diodes and other devices;secondly,considering the influence of the equivalent parasitic parameters of switches,diodes and other devices,the voltage gain of the converter is deduced again;then,the small signal modeling and closed-loop feedback network design are carried out by using the state space averaging method,and the simulation results are verified.The working principle and steady-state characteristics of the converter;finally,according to the design parameters in Chapter 4,a test prototype with an input voltage of 1.2～1.4V,an output voltage of 24 V and an output power of 10 W is built.The experimental results show that the converter designed in this paper can achieve a boost ratio of up to 20 times,the highest conversion efficiency can reach91.2%,and the voltage stress of each power device is small,and the switch tubes and diodes have achieved soft switching.