Theoretical Research And Implementation Of Isolated Bidirectional DC-DC Converter

With the rapid development of science and technology in recent years,the global demand for energy is increasing rapidly,the traditional energy sources such as oil and coal are increasingly exhausted,and the development and efficient utilization of new energy are the inevitable choice of the world today,It can be used to "cut peak and fill valley" to improve energy utilization rate.Because of its symmetrical structure and high power density,bidirectional full bridge DC-DC converter can be widely used in various energy storage systems as a bridge between power grid and energy storage device.Firstly,this paper introduces the working principle,main topology and control mode of Bidirectional DC-DC converter.By drawing the circuit waveform,according to the key nodes of the waveform,the micro process of isolated bidirectional full bridge DC-DC converter under the traditional phase-shifting control strategy is analyzed in detail,and the system characteristics of the converter under the traditional phase-shifting control strategy are studied comprehensively Including power return characteristics,current stress,soft switch characteristics,dead zone effect and compensation measures.In order to solve the problem of large current stress of inductor when the input and output voltage of traditional phase-shift control is mismatched.Based on the traditional phase-shifting control strategy,an improved phase-shifting control strategy is proposed by increasing the internal phase-shifting angle.The micro process and system characteristics of the improved converter are compared with those of the traditional phase-shifting control method.The comparison shows that under the same power transmission,the current stress of the improved strategy is greatly reduced,the return power is reduced,and the voltage is at the same time The adjustment range becomes more flexible.The simulation model of isolated bi-directional full bridge DC-DC converter is built by saber simulation software.The traditional phase-shifting control and the improved phase-shifting control strategy are simulated and analyzed.The key voltage and current waveforms of each node of the converter and the magnitude of inductance current stress are simulated.Verify the correctness of theoretical analysis.Finally,on the basis of theoretical analysis,the hardware circuit is designed,and a small power experimental prototype based on UCC3895 is built to further verify the effectiveness and feasibility of the theoretical analysis.