I have been building boost converters. My current revision is working well at about 300 W, 55 V in to 86 V out. The main problem I now face is that the output capacitor is getting quite hot.
If I leave the boost converter running for 10 minutes or so the output capacitor (330 μf, 200 V, 105°C) becomes too hot to touch, at a guess I would say 80 to 90°C, where I think it claims 105°C. I don't really want to push it to its limits.
What is the reason radial electrolytic capacitors get hot? Does it have to do with the speed they are charged and discharged?
What would be an appropriate fix to the issue? Would it be to have more capacitors sharing the load?