Metallized film capacitor is widely used in such electrical equipment as converter valves and,under the influence of rapid operation of power electronic switches,will be subjected to high-frequency shocks,it is therefore necessary to study the characteristics of the capacitor in a wide frequency range.In this paper,the single capacitor elements is taken as the study object.The impedance characteristics of capacitor elements in the range of 20 Hz～2 MHz are measured by using a digital bridge.An equivalent circuit model is set up by a combination of data fitting and experimental measurements and the impedance characteristics and equivalent circuit parameters at different frequencies are analyzed.The study results show that at low frequencies(<150 kHz),the equivalent circuit model with constant parameters can accurately describe the impedance characteristics and internal physical processes of the capacitor element,while at high frequencies(>150 kHz),the current distribution in different areas inside the capacitor element will change,resulting in a frequency change of such parameters as equivalent inductance and equivalent resistance of the element,which causes a change in the impedance characteristics.The results of this paper can provide guidance for analyzing the degradation mechanism of capacitor under high-frequency shocks.
关键词
金属化膜电容器/宽频特性/等效电路/频变参数
Key words
metallized film capacitors/broadband characteristics/equivalent circuit/frequency-variable parameters
维普
万方数据