Modeling of ESR in metallized film capacitors and its implication on pulse handling capability

Metallized film capacitors (MFC) are widely used in pulsed power systems and power electronics applications. The pulse handling capability of MFC is one of important performances and drastically depends on the quality of contact states between the spray and metallization. The equivalent series resistance (ESR) is a significant parameter to the capacitor. This paper presents a model to calculate ESR with consideration of the end contact status. This model shows that ESR at low frequency (∼100 Hz) is more efficient to reflect the end contact status than that at high frequencies (∼10 kHz). Lifetime experiments are designed to demonstrate that MFC with significantly lower ESR enjoy longer pulse lifetime and better pulse handling capability. Thus measured at low frequency (∼100 Hz) can be regarded as a parameter to reflect the disconnections of weak contact in high current densities applications and to evaluate the pulse handling capability.     

基于电荷补偿的金属化膜电容器自愈测试方法

利用金属化膜电容器发生自愈时会引起电容极板间电压下降,并使与其并联的储能电容为其充电以补偿电荷这一原理,设计了一种较为简单、有效的自愈测试方法。该方法利用示波器监测自愈发生时储能电容给被测电容的充电电流作用于采样电阻而形成的脉冲电压信号,以该信号的出现作为判断自愈发生的依据,并根据该信号特性计算自愈能量损失。仿真和实验结果证明,该方法能够较为准确地检测到自愈的发生,并计算出自愈造成的能量损失,30个实际测试样本数据显示,采用该方法计算的自愈能量损失与实际自愈能量损失相比,其误差范围在-3.83%~5.71%内,有较高的准确度。