Research On Bi-Directional DC/DC Converter Based On The V2G Technology

In recent years, it has become increasingly concerned about the emerging direction of new energy and smart grid. V2G technology is an integral part of the future smart grid, as the interaction technology between electric vehicles and the grid. It is related to the emerging technology of power grid, power scheduling, power electronics, chemical batteries and other fields. Power electronics technology has a very important role in V2G field, and bi-directional power flow between the grid and electric vehicle put higher requirements to the power electronic devices.The introduction section briefly describes the basic concept of V2G technology, application fields, as well as the status and trends of V2G technology development at home and abroad. In this section, a simple analysis of the topologies of power electronic devices in V2G technical applications as well as the advantages and disadvantages of the various topologies is given. The section also presented the combination of a two-stage topology and finally elaborated the significance of the research.The second chapter is focused on the bi-directional DC/DC converter of the topology. Firstly, the basic principle and operation mode of the circuit is analyzed. Secondly, the basic parameters of the circuit are calculated and selected, and then PWM driver is designed as well as the sampling circuit. The circuit is partly simulated by Saber software and the auxiliary power allocation scheme is simply introduced. Finally, the two-stage topology is verified by the system simulation in MATLAB and PLECS platform. The stability and cutting board simulation waveforms of the bi-directional DC/DC circuit are discussed in detail.In the third chapter, small signal models and the analog controller design is presented. At first, the small signal model diagram of the basic Buck and Boost circuits are given. Then, the small signal models of forward phase-shifted full-bridge and reverse full-bridge Boost circuit are given. On this basis, the compensator of the control loop is designed, and the simulation of the dynamic performance and steady state performance is carried out. The fourth chapter focused on the study of digital control. At first, the commonly used types of DSP and a comparison are introduced. Then, DSP28335controller is determined as the choice. The control strategy of PWM generation is given. At last, the analog controller in the third chapter is discretized to obtain the control variables in the actual program. Chapter5discussed the efficiency problem of the bi-directional DC/DC converter. The power loss of the positive charge mode and the reverse discharge mode is calculated and various components of the main power are analyzed. Finally, the experimental prototype physical map and some experimental waveforms are given.