Research On Isolated Bidirectional Dc/dc Converter With Double Phase Shift Control

With the development of the world economy and the improvement of people's quality of life,the global energy situation has become more and more serious.The development and utilization of renewable energy has gradually become a research hotspot.In the field of new energy power generation systems and electric vehicles,isolated bidirectional DC converters are used as power electronic interface devices between the different DC busbars,enabling bidirectional transmission of energy between energy storage devices and charge-discharge devices.In this paper,after analyzing the advantages of the dual active bridge converter compared with other common isolated bidirectional DC converter topologies,the dual active bridge converter is selected as the main circuit topology of the isolated bidirectional DC converter.The working principles,current characteristics and power characteristics of the isolated bidirectional DC converter are described.Secondly,the control method of the isolated bidirectional DC converter is studied in detail.Analysis of converter operating modes for isolated bidirectional DC converters using single phase shift control and dual phase shift control is also carried out.The inductor current stress and power transmission characteristics of the converter under different control modes are compared and analyzed.The reason why the inductor current stress is larger during the operation of the converter under single phase shift control is explained.Then,aiming at reducing the current stress in the working process of the isolated bidirectional DC converter,the control strategy of the isolated bidirectional DC converter is designed by combining the dual phase shift control with the current stress optimization control.In order to reduce the starting current of the converter,after analyzing the traditional optimization control method,a startup current optimization control strategy based on double phase shift control is proposed to improve the traditional optimization control method.It can make the duty ratio of the output voltage of the transformer primary and secondary sides of synergistically change with the given voltage,so the inductor current during startup can be reduced.In order to reduce the current stress of the converter under light load or voltage mismatch,the Lagrange method is used to establish the optimal function to obtain the optimal control parameters,and the optimal control strategy of steady-state current stress is established based on the two different dual phase shifting controls.Finally,the experimental prototype of isolated bidirectional DC converter is built,and the converter is tested under laboratory conditions.Through the analysis and collation of the experimental results,the effectiveness of the proposed optimal control strategy in reducing the current stress is verified,and the correctness of the theoretical analysis and design is verified.