Research On Bidirectional Isolated DC/DC Converter For Charging Station

With the rapid development of the industry of automobile, the problem ofenvironmental pollution and energy crisis is becoming more and more serious. Therefore,vigorously promoting the development of electric vehicles to promote traffic energytransformation has become the key object to develop of our country and the rest of theworld’s major developed countries. With the rapid development of them, the chargingsystem specifically for electric vehicles in the smart grid has been put forward higherrequirements. These requirements are that higher power density and better dynamicperformance. And at the same time, it not only can control energy flow but also can adjustthe amount of energy. In the charging system specifically for electric vehicles, thebidirectional isolated DC/DC converter not only can control energy flow but also canadjust the amount of energy.So it is an important part of the charging system specificallyfor electric vehicles. Therefore, it has a very good space of development and prospect. Asa result, it is necessary to have an in-depth discussion and research on it.Firstly, this paper introduces the background of research, the principle、applicationand the control mode of the bidirectional DC/DC converter，mainly analyzing thebidirectional isolated DC/DC converter in detail. And the significance and contents of thispaper are briefly discussed.Secondly, the working mode and parameters of the main circuitare analyzed in detail, the loss of the circuit is also analyzed and conducting the simulationanalysis. Then, by introducing the working principle of the battery and several commonlyused charging methods, determines the way of charging of the system, and conducting thesystem modeling and the design of the controller. At last, simulation analysis has beenconducted to verify the correctness of the theory analysis and the feasibility of the controlmethod.In this topic, an experimental prototype of bidirectional full-bridge DC/DC convertertopologies was designed and built. By using an improved dual phase-shifting control, thecyclic energy of the system was reduced, and achieved soft-switching of the switches. Forthe forward charging process, the system achieved a three stage charging by using the control of dual voltage and current closed loop. For the reverse discharge process, thesystem achieved a constant voltage discharge by using the control of single voltage closedloop. In conclusion, the experimental results again validate the correctness of the designand the feasibility of the control method.