Research On An Improved Bidirctional Quasi-Z-source DC-DC Converter

In recent years,due to the intensification of the fossil energy crisis such as coal and oil,the clean energy such as wind energy and solar energy are gradually becoming popular.The development and utilization of clean energy not only optimize the energy supply structure,but also promote the development of power electronics technology.The bidirectional DC-DC converter,which can change the direction of power transmission according to actual needs and is functionally equivalent to two unidirectional DC-DC converters,is an important part of the power electronics technology.Therefore,it has broad application prospects in the fields of power quality regulation,the electricity generation of new energy and so on.However,the disadvantages of the traditional bidirectional DC-DC converters such as low boosting capability,large power switching loss,low efficiency,and so on seriously limit the practical application range.In order to meet the needs of industrial development,the bidirectional DC-DC converter needs to be further studied.Based on the shortcomings of traditional bidirectional DC-DC converters,an improved quasi-Z-source network can be applied to bidirectional DC-DC converter is proposed in this thesis.Firstly,the principle of operation in the forward and reverse directions is analyzed,the relations of the input and output voltage are deduced,and the comparison of boosting capability and capacitive voltage stress with the traditional DC-DC converters is made.Secondly,the parameters of inductor,capacitor,power switching IGBT and other component are designed,and the PWM control technology is introduced.Thirdly,the correctness of the theoretical analysis is verified by Matlab simulation and prototype experiments.Finally,the improved bidirectional quasi-Z-source DC-DC converter designed in this thesis is applied to the uninterrupted power supply system of underground battery locomotives.Meanwhile,its specific working process is analyzed and its application value in industry is reflected.The circuit structure of the improved bidirectional quasi-Z-source DC-DC converter researched in this thesis can not only adjust the energy transfer direction,but also can achieve the rise and fall function of voltage in a single working direction;On the basis of the advantages of the traditional bidirectional DC-DC converter,the boosting capability is improved and the conduction time of the switch tube is shortened,thereby the service life of the switching device is prolonged and the practical application range is expanded.