Simple High Side IGBT Switch
You can use a IGBT for the high side switch.

But you need a supply with a voltage higher than 100V to drive your IGBT. I usually do it with a separated and isolated supply just for the gate driver (a small switched supply), there are some on chip solutions for that (Power Convertibles HPR 105 for example). The supply's GND is tied to the IGBT emitter. Then you have a voltage to drive your IGBT.