重频大电流下金属化膜脉冲电容器温升累积效应研究

Study on Cumulative Effect of Temperature Rise of Metallized Film Pulse Capacitor Under Repeated Frequency and High Current

电磁发射技术中通常要求脉冲功率电源具有数十千安幅值、数毫秒脉宽的脉冲电流,并且具备重复频率连续发射能力。金属化薄膜电容器因其储能密度高、使用寿命长而被广泛应用于脉冲电源系统。根据脉冲电容器的结构及脉冲电源的工作模式,该文首先建立脉冲电容器的发热及散热模型;然后,在多物理场仿真软件COMSOL Multiphysics 5.6中建立瞬态温度场模型,并结合现有实验结果验证模型有效性,进而讨论重复频率脉冲放电应用中金属化膜脉冲电容器内部温升的累积现象。结果表明:在脉冲放电峰值1 kA、环境温度15℃、金属膜厚4 nm条件下,以12次/min的重复频率、30 s时间间隔连续工作10次后,脉冲电容器芯子最大温升为22.9℃。在此基础上,仿真分析环境温度、重复频率、脉冲电流峰值、电极厚度四方面因素对脉冲电容器温升的影响。该模型给出重频大电流下脉冲电容器内部瞬态发热规律,可为脉冲电容器合理运行和优化设计提供参考。

Electromagnetic emission technology typically requires a pulsed power supply to have a pulse current with an amplitude of tens of kiloamperes and a pulse width of several milliseconds,and to be capable of continuous emission at a repetition rate.Metallized film capacitors are widely used in pulse power supplies due to their high energy storage density and long life.According to the structure of the pulse capacitor and the working mode of the pulse power supply,this paper first establishes the heat generation and heat dissipation model of the pulse capacitor,then establishes the transient temperature field model in the multiphysics simulation software COMSOL Multiphysics 5.6,and combines with the existing experimental results to verify the validity of the model.The accumulation phenomenon of the internal temperature rise of the metallized film pulse capacitor in the repetitive frequency pulse discharge application is discussed.The calculation results show that under the conditions of pulse discharge peak value of 1k A,ambient temperature of 15℃,and metal film thickness of 4nm,the maximum temperature rise of the pulse capacitor core is 22.9℃ after continuous operation for 10 times at a repetition rate of 12 times/min and a time interval of 30s.On this basis,the influence of four factors including ambient temperature,repetition frequency,pulse current peak value and electrode thickness on the temperature rise of the pulse capacitor is analyzed by simulation.The model gives the internal transient heating law of the pulse capacitor under high frequency and high current,which can provide a reference for the reasonable operation and optimal design of the pulse capacitor.