The Research On The Optimization Control Method Of Isolated Bidirectional DC-DC Converter

As the ideal access way of distributed power supply and energy storage device,DC distribution network can reduce energy conversion link and filter device,which has become a research hotspot.As the interface circuit between the buses in the DC distribution network,the Isolated Bidirectional DC-DC Converter has the distributed,modular and plug-and-play hardware and software structure.The series connection technology is used to raise the voltage level through the high voltage side.Improve the power level,so as to achieve energy conversion and electrical isolation,to improve the Isolated Bidirectional DC-DC Converter conversion efficiency for the DC power distribution network of energy efficient transmission is of great significance.In this paper,by analyzing the principle of backflow power and power loss of Isolated Bidirectional DC-DC Converter under Dual-Phase-Shifting control,a minimum backflow power phase-shifted control method and an efficiency optimization control method are proposed.Firstly,the circuit topology and working principle of the Isolated Bidirectional DC-DC Converter are analyzed.The mathematical model of the transmission power of the converter under the traditional phase-shifting control is established.The working mode of the Isolated Bidirectional DC-DC Converter under the traditional phase-shifting control method is described in detail.Secondly,the principle of backflow power generation in Isolated Bidirectional DC-DC Converter is analyzed,and the mathematical model of the power supply side backflow power and the load side backflow power under dual-phase-shift control is established.Compared with the Dual-phase-shift control method,the minimum backflow power phase-shifted control method is proposed.The control method can control point achieve minimum backflow power operation thus effectively reducing the current stress and improving efficiency.Thirdly,the principle of power loss of switching devices and transformer is analyzed,and the mathematical model of switching loss,on-state loss and transformer loss is established.On this basis,efficiency optimization control method is proposed.Compared with the dual-phase-shift control method,the efficiency optimization method can realize the converter operating at the only operating point,achieving the minimum power loss and the highest efficiency.Finally,the control methods are verified in a Isolated Bidirectional DC-DC Converter porotype.Experimental results show that the proposed minimum backflow power phase-shift control method is simple and easy to implement under different operating conditions,and the control point can achieve the minimum backflow power,effectively reducing the current stress and improve efficiency.The proposed efficiency optimization control method can control the converter work in the point of least power loss and highest efficiency.