Thermal Analysis of Metallized Film Capacitors Used in Motor Drive Controller

An important function of the capacitors is to absorb ripple current. Loss occurs when ripple current enters the capacitor. This loss heats the capacitor core. Because the metallized film capacitor has a temperature resistance value, the capacitor has an upper limit of absorption ripple current. In this paper, the thermal performance of a kind of metallized film capacitor is tested. The weak point of temperature distribution is in the terminals, especially in the large current. The water-cooling method is more effective than natural cooling method in reducing the temperature of the metallized film capacitor. The thermal resistance of the capacitor decreases by 72.4%. The ripple current rating of capacitor increases from 180 Arms to 398 Arms. With the increase of the temperature of cooling water, the temperature increased gradually. The thermal resistance of the capacitor is a complex parameter based on the change of ambient temperature. The effect of temperature reduction is not obvious in the range of experimental flow.