Effects of dielectric material properties on metalized film capacitor performance

The effects of dielectric constant and in-plane thermal conductivity of capacitor film on the maximum temperature rise per unit power dissipation or K/W in a DC-link capacitor were studied based on finite element computations which were compared with analytical approximations. The K/W was found to scale with the dielectric constant and the in-plane thermal conductivity according to a power-law relationship with an exponent of 0.9 and -0.65, respectively. While losses induced by film metallization usually dominate heat generation within a capacitor, conduction losses due to electrical conductivity higher than 10
^-13
S/m become significant.