Thermal Design And Structure Optimization For High Power Series PV String Inverter

Photovoltaic inverter is an important part of photovoltaic power generation system.With the continuous reduction of the cost of the cascade inverter,the availability becomes higher and higher,so it’s gradually replacing the centralized inverter,widely using in ground power stations.The size of the pv string inverter becomes smaller and smaller,the integration becomes higher and higher,the heat flow density is also increasing,its structural design becomes more and more difficult.In this paper,aiming at the problem of how to effectively improve its unit power,the whole structure of high-power series photovoltaic inverter is designed to meet the requirement of heat dissipation.For high design heat dissipation performance requirements of PV string inverter,Analysis of heat dissipation factors of the whole machine,the method of forced air cooling is proposed,The system structure is designed to protect the internal components of each module unit to operate normally at the maximum allowable temperature.Use the thermal analysis software module to analyze the product system in detail,Based on the results of thermal analysis,the structure of high power tandem inverter is optimized.Using the experimental simulation product working environment to test the prototype heat,obtain the actual temperature data of components,to verify the accuracy of the thermal design scheme.The research content of this thesis mainly includes:The first chapter describes the purpose and significance of studying thermal design and structure optimization of photovoltaic connected inverter,summarizes the development status and future trend of photovoltaic inverter and thermal design.Then,introduce the research content and the organizational framework of this thesis.In the second chapter,a design method of forced air cooling system for high power group series inverter based on heat transfer is proposed.This paper discusses the thermal design method of high power group series inverter from four aspects:heat transfer method selection based on heat transfer theory,structural design method of forced air cooling radiator,selection calculation and location determination method of network side fan,and analysis of heat dissipation key factors of forced air cooling system to generate the initial forced air cooling system scheme.In the third chapter,we describe the generation method of high-power series pv string inverter Overall structure design method.Determining the initial integrated structure of the box according to the structure arrangement of net side and machine side.A three-dimensional geometrical modeling of high-power serial inverter is constructed to demonstrate the generality of the generation method for the overall structure design of high-power tandem inverter,the goal of 80kw power of a single series inverter is realized.In the fourth chapter,a thermal simulation method based on FloTHERM is proposed to optimize the thermal performance of high-power series pv string inverter.The process of thermal simulation and the key steps in the simulation process are described.Based on the simulation results of 80kW series inverter virtual model,the structure optimization is carried out for the parts with unsatisfactory heat dissipation performance on the network side and machine side.The optimized 3d model was used for thermal simulation to analyze the improved effect.In the fifth chapter,describe the prototype construction and thermal test analysis of 80kW pv string inverter.According to the final structure design scheme,the prototype of 80kW series inverter is built,analyze the main performance parameters of the prototype at 50℃.The effectiveness of the general process of heat design and structural optimization of high-power cluster inverter based on modern thermal simulation technology is verified.The sixth chapter summarizes the main research results of this thesis,and prospects the follow-up research and improvement work.