Research And Development On Key Technologies Of Photovoltaic Charging Pile For Electric Vehicle

At present,the global economy has been developing rapidly.But the environment is seriously damaged and the energy is overexploited.All of these have led to the transformation of many industries.The development of the automobile industry is inseparable from the exploitation and utilization of petroleum energy.Facing the tremendous pressures that are the crisis of global oil and the exhaust emissions from automobiles polluting the environment,the automobile industry must find a new mode of energy that can be harmony with the environment.Electric vehicles and renewable energy generation technology(solar power generation)are two important ways to solve the energy crisis and environmental problems.Therefore,this paper studies the charging system of photovoltaic electric vehicle based on micro grid in order to achieve integrated application of electric vehicle and renewable energy.So as to achieve synergy effect.In this paper,the photovoltaic grid charging pile based on micro grid is studied.The two parts of photovoltaic power generation system and two-way charging pile system are studied.This article combines the background significance of current research.Based on the background significance of current research,this paper deeply understands the research status of photovoltaic power generation,micro-grid technology and the development of charging pile,and deeply studies the photovoltaic power generation technology,micro-grid technology and electric vehicle charging pile technology.The photovoltaic power generation subsystem in the photovoltaic charging pile is analyzed and designed.The working principle,classification,composition and structure of the photovoltaic power generation system are deeply studied.This paper analyzes the main control method of photovoltaic power generation technology-maximum power point tracking control method,so as to design the 5 kW photovoltaic power generation subsystem in the photovoltaic charging pile.The design scheme and the selection and design of the equipment in the photovoltaic power generation system are given.The three level AC/DC converter of photovoltaic charging pile system is studied in this paper.A three level AC/DC topology is proposed,and a mathematical model of three level AC/DC is established.A simplified SVPWM algorithm for three level space is adopted.The three level vector sector and three level action time and order are judged.The control strategy of three level AC/DC current inner loop design and voltage outer loop design is also proposed.In order to verify the correctness of the design,a simulation model of 25KW three level PWM rectifier is established.Finally,the three level bidirectional DC/DC of photovoltaic charging pile system is studied.Based on the study of the working principle of double half bridge three-level bidirectional DC/DC converter,a three-level bidirectional DC/DC topology is proposed.The characteristics of the three level bidirectional DC/DC converter are analyzed.It includes two parts:power flow characteristic analysis and soft switching realization condition.In addition,the two most popular two level control methods in the three level bidirectional DC/DC converter are analyzed and compared.They are pulse width modulation and phase shift modulation respectively.Through the analysis and comparison of the two methods,the conclusion of the choice of control mode is given.It is pointed out that the phase shifted modulation is superior to the pulse width modulation.Based on the theory of three-level bidirectional DC/DC converter,PSIM is used to simulate the converter and verify the theoretical analysis of soft-switching conditions.In this paper,a simulation system is built to verify the theoretical basis and control strategy.The simulation results show that the photovoltaic DC/DC can meet the requirements of converting the output voltage of the photovoltaic array into the DC-side voltage of the inverter.Simultaneously,the simulation results show that the three-level AC/DC converter and three-level bidirectional DC/DC converter designed in this paper are reasonable and feasible.