金属化膜电容器发热的计算与分析(特选内容)

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毕业设计[ 论文]

题目：电介质薄膜发热的计算与分析

Title ：The Thermal Rating and Analysis of

Dielectric Film

院系：电气与电子工程学院

专业：电气工程及其自动化

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指导教师：

20XX年X 月X 日

摘要：金属化膜电容器在电场作用下，电容器电极电阻和介质损耗（即等效串联电阻）的存在而使电容器发热。其中一部分热量散发到周围环境中去。另一部分热量则使电容器内部的温度升高。这就可能导致电容器的电学性能发生变化。同时，长期受热可使介质加速老化，缩减寿命，严重时可发展为热击穿，导致电容器损坏。另外在脉冲放电下，金属化膜电容器的发热还会影响通流能力和耐压能力，对相关设备的稳定运行有极大的影响。

金属化膜电容器的热计算主要是对既定的产品结构，计算其在一定的运行条件下的温升，通常指电容器达到热平衡后，材料各关键部位到环境的温升，特别是介质最热点到外壳和外壳到环境的温升。

本文首先探讨了金属化膜电容器发热的来源以及影响金属化膜电容器发热的因素，以及在重复频率脉冲的作用下的来源和主导因素；第二步通过建立重复频率脉冲模型；第三步通过构建金属化膜电容器的结构模型来确定传热计算的模型从而运用相应的传热学理论来计算内部温升和外部散热；第四步运用一些典型的具体数值来计算一些具体的金属化膜电容器的发热问题；最后通过对比分析计算结果以及研究已有的资料数据得出有关金属化膜电容器发热的一些基本结论。

关键词：金属化膜电容器温升散热发热功率传热系数

Abstract:When a metalized film capacitor is operating under electric field, capacitor will be heated because of the electrode resistance and dielectric loss(equivalent series resistance). One part of the heat dissipates to the outside, the other part contributes the capacitor internal temperature rise. This may lead to changes in the electrical properties of capacitors. Long-term heat makes media accelerate aging, reduces life expectancy. When serious, it may develop to thermal breakdown and result in damage of capacitors. Heating of metalized film capacitors has a great impact on the through-flow capacity and voltage resistance capacity, and also the stable operation of the equipment.

The thermal rating of a metalized film capacitor is mainly for established product structure. Under specific operating conditions, the temperature rise is often referred to that the capacitor has reached thermal equilibrium, the temperature rise of the the key points to the environment, and in particular the temperature rise is the media's hottest spots to the housing and the housing to the environment.

This article firstly discusses heating sources and factors of metalized film capacitors that affect the heat of metalized film capacitors. Under the effect of repetition frequency pulse, which sources and factors are dominant factors. The second step, through the establishment of repetition frequency pulse model, we calculate the calorific value of capacitor at work. The third step, by building the structure model of metalized film capacitors we determine the heat transfer calculation model to use the heat transfer theory to calculate temperature rise of internal and external heat and other related parameters. The fourth step, using models and the construction of a formula, with some typical numerical the problem to calculate the heat of metalized film capacitors can be solved. Finally, through analysis and calculation of results and study on existing data, we can conclude some basic conclusions of the heating of metalized film capacitors.

Key words: metalized film capacitor temperature rise heat dissipation

the heating power heat transfer coefficient