What causes switching losses in power electronics devices?

Switching losses occur during turn-on and turn-off transitions when both voltage and current are non-zero simultaneously. During turn-on, current rises while voltage falls; during turn-off, voltage rises while current falls. The overlap of V and I creates power loss: Psw = 0.5 x V x I x (ton + toff) x fsw. Factors include switching frequency, voltage/current levels, and device characteristics. Soft-switching techniques (ZVS, ZCS) reduce losses by ensuring zero voltage or current at switching instant.