Study on Broadband Characterization of Metallized Film Capacitor Element
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.
metallized film capacitorsbroadband characteristicsequivalent circuitfrequency-variable parameters
万方数据
维普
