基于热仿真的低压变频器的设计及研究

发布时间：2018-03-21 12:49

  本文选题：低压变频器　切入点：热设计　出处：《苏州大学》2016年硕士论文　论文类型：学位论文

【摘要】：低压变频器在我国运用非常广泛,而因其体积小,热流密度高,散热空间有限,导致了它的故障率非常高。变频器的功率模块单元具有高发热特性,必须控制其元器件的温度在允许的温度范围内,并要求把积聚在产品狭小空间内的热量有效地散发出去,因此对变频器的散热设计分析和研究有着非常重要的意义。本文以研究紧凑型11KW的低压变频器在高环境温度下可靠和稳定地工作为目标,通过三维结构建模、数学建模、热仿真模拟、工程实验等手段和方法对变频器的散热结构展开了研究。(1)利用传热学的理论基础,建立了变频器系统散热的数学模型,对其热传递过程和散热方式进行了分析,得出了自然对流和强迫空气对流两种不同冷却方式的散热结构设计的方法。并根据散热器的热阻计算方法,对散热器进行了详细的结构设计。(2)对11KW的低压变频器展开了详细的热设计,包括风机的选型和安装方式、功率元器件的布局及整体的散热结构设计,采用新型的风道设计,将主要发热源和PCB板隔离开来,以提高设备的可靠性和寿命。并利用UG软件对变频器的散热结构构建了三维物理模型。(3)根据变频器的散热结构方案,利用Icepak软件构建热仿真模型,用以分析变频器的散热结构对系统整机散热方面的影响。通过有限元仿真模拟得出变频器功率元器件的热点温度;通过Icepak软件的后处理功能,观察变频器内部的风场分布情况、流速矢量图和温度云图,据此来指导和优化变频器的散热结构设计,最终热仿真结果表明变频器在50度的高环境温度下,其内部电抗器的温度为113.8℃(120℃)、散热器的温度为81.7℃(85℃)、DC link电容的温度为68.6℃(75℃),都在允许的温度范围内。(4)对优化后的变频器最终散热方案制作工程样机,按照设计要求在50度的环境温度下对样机进行热测试,并通过热电偶和温度记录仪来实时监测变频器的功率器件在实际工作状态下的温度数值。根据热测试的结果,变频器功率元器件的实际温度测量值(电抗器:114.8℃、散热器:79.4℃、DC link电容:70.3℃)和热仿真的结果(电抗器:113.8℃、散热器:81.7℃、DC link电容:68.6℃)是很接近的,符合工作要求,这也检验了热设计仿真的适用性和正确性。对变频器展开热设计和热仿真的研究,可以快速预测功率元件的温度,并可以根据仿真结果得出变频器内部的热场和风场的分布情况,据此来优化散热结构的设计,这为变频器的研发提供了有效的技术方法。
[Abstract]:Low voltage frequency converter is widely used in our country, but because of its small volume, high heat flux density and limited heat dissipation space, its failure rate is very high. The temperature of its components must be controlled within the permissible temperature range, and the heat accumulated in the small space of the product must be effectively emitted, Therefore, it is of great significance to analyze and study the heat dissipation of the converter. This paper aims to study the reliable and stable operation of the compact 11KW low voltage inverter under high ambient temperature. Based on the theory of heat transfer, the mathematical model of heat dissipation of inverter system is established, and its heat transfer process and heat dissipation mode are analyzed. The design method of cooling structure of natural convection and forced air convection is obtained, and according to the heat resistance calculation method of radiator, Detailed structural design of radiator. (2) detailed thermal design of 11KW low voltage converter, including selection and installation of fan, layout of power components and overall heat dissipation structure, design of new air duct, In order to improve the reliability and life of the equipment, the main heat source is isolated from the PCB board, and the three-dimensional physical model of the heat dissipation structure of the inverter is constructed by using UG software. The thermal simulation model is constructed by using Icepak software to analyze the influence of the heat dissipation structure of the inverter on the heat dissipation of the whole system. Through the finite element simulation, the hot spot temperature of the power components of the converter is obtained, and the post processing function of the Icepak software is obtained. By observing the distribution of wind field, velocity vector diagram and temperature cloud diagram, the heat dissipation structure design of the converter is guided and optimized. The final thermal simulation results show that the converter is at a high ambient temperature of 50 degrees. The internal reactor temperature is 113.8 鈩，

本文编号：1643926