| With the progress of The Times,people in today’s world are facing more and more challenges.Among them,the environmental pollution caused by energy shortage and energy loss is particularly serious,so the development of non-polluting renewable energy has become the focus of the world.In the academic and industrial circles at home and abroad,more and more attention has been paid to the development and utilization of solar energy resources in recent years.Photovoltaic power generation,as a renewable energy,has developed rapidly with its advantages of no exhaustion risk,safety and reliability,no pollution emission,high energy quality and wide distribution.However,due to the great indirectness and volatility of its power generation,in order to increase the efficiency of photovoltaic power generation and maintain the stability of operation,it is of great significance to study the photovoltaic grid-connected equipment containing energy storage devices.This paper studies the application technology of bidirectional DC/DC converter in photovoltaic grid-connected system containing energy storage device,and explores the organic combination of energy storage unit,power grid and photovoltaic power supply,so as to provide theoretical support for the efficient utilization of photovoltaic energy.Including DC/DC converter in the energy storage system as the main components of electric energy collection and transmission,due to the widespread use of the shortcomings of two level DC/DC converter performance is more and more obvious,such as its capacity is small,large switch loss,through lack of low current ripple frequency of causing people to delve into new areas of the equipment,so the focus of attention has now shifted to the development of the three level of the DC/DC converter.Three-level bidirectional dc converter has obvious advantages in application compared with two-level converter.It is studied that it can not only bear half of the voltage stress of two-level converter,but also greatly reduce the response time.This determines that the loss of the three-level converter is much less than the loss of the latter,which is also the reason why the three-level bi-directional converter is widely used in the fields of high voltage and low voltage.The three-level DC/DC converter for photovoltaic energy storage in this study has simple structure,strong reliability,and supports the standard of interactive energy transmission with large capacity and high power.In the whole micro-grid energy storage system,this design can efficiently adjust the energy exchange between the dc bus and the battery,which has the advantages of low cost and high efficiency and reliability.This paper describes in detail the three level of bi-directional DC/DC converter topology structure and its working principle,and then the research by the three level bidirectional DC/DC converter applied in photovoltaic system containing stored energy device,on the basis of the pv array and battery energy flows between the various circumstances,thus summarizes nine different way of working,the photovoltaic energy storage closed-loop method and put forward the effective control of the converter,which focuses on the energy management mode circuit,plus the neutral voltage balance control of double closed loop control circuit.Secondly,in order to verify the correctness and feasibility of the converter,the hardware circuit of three-level DC/DC converter based on TMS320F28335 is designed,and the relevant software is designed.Finally,the MATLAB simulation and compare the obtained experimental data analysis,show that the three-level DC/DC converter in the photovoltaic energy storage system running the effectiveness of the method is correct and the control,the control method can solve the three-level DC/DC converter in the interaction energy flow problem in the practical work,and can be very good to solve effectively the problem of offset voltage.Experimental data show that under the modulation method and control mode adopted in the energy storage system,the three-level bi-directional converter has the advantages of efficient completion of bidirectional energy flow,fast unbalanced voltage suppression,stable output voltage,fast dynamic response,and good ability to charge and discharge equipment in the energy storage system. |
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