Film capacitors are versatile components that can be designed into power electronics for industries ranging from consumer and renewables to automotive, aerospace and military. These capacitors come with very specific advantages including non-polarity, a high insulation resistance, low dielectric losses and self-healing capability.
In that case, the capacitor will be used for decoupling. Film capacitors are particularly well adapted for this use, because the main criteria for DC link capacitor is the ability to withstand rms current. It means that DC link capacitor can be designed on rms current value. So, it will be easy to find a capacitance value close to this value.
Film capacitors are not recommended as a one-for-one replacement of aluminum electrolytics. Film capacitors are not recommended as one-for-one replacements of aluminum electrolytic capacitors. There are considerable mechanical and electrical differences. Switching from one technology to the other requires a new inverter topology.
Metallized film capacitors are made of two metallized films with plastic film as the dielectric. A very thin (~ 0.03 μm ) vacuum-deposited aluminum metallization is applied to one or both sides to serve as electrodes.
There are two different types of plastic film capacitors, made with two different electrode configurations: Film/foil capacitors or metal foil capacitors are made with two plastic films as the dielectric. Each is layered with a thin metal foil, usually aluminum, as the electrodes.
The dissipation factor for film/foil capacitors is lower than for metallized film capacitors, due to lower contact resistance to the foil electrode compared to the metallized film electrode. The dissipation factor of film capacitors is frequency-, temperature- and time-dependent.