I have in hand a 220V:600V isolated transformer and a HV bridge rectifier and I'd like to charge a 250uF capacitor with adjustable voltage from 200V to 500V. My idea is to use a switch between the supply and the capacitor and open it when the capacitor reaches the desired voltage (that will be monitored using a microcontroller), like this:
My questions are:
Is IGBT suitable for this? Would it require a snubber if I open it during the charging period? The secondary inductance of the transformer would result in transient voltage when I open the switch?
To control the IGBT I would need to provide a voltage in the gate that is referenced to the HV of the capacitor? Using an optocoupler for example, it would require a power supply that the GND is connected to the emitter of the IGBT, is that correct?
GTO or SCR would be better choices in this case? I also could charge it to the maximum peak voltage of the transformer (850V) and then discharge the capacitor using another switch. Any thoughts?