I am currently working on a high voltage supply for short (50-100ns), quick (<30ns rise time) pulses. The below circuit is my first rough draft for the power supply, I realized that by connecting the MOSFET driver up the way I have, I have de-isolated the HV voltage section of the circuit. My question is, would it be better to keep the HV section of the circuit isolated (main concern: safety) or reference it to the battery's negative terminal (as is below)?

I've been looking into options for pulse transformers to accomplish the isolation task for the low voltage section if I need to go that route, but I haven't been able to find many that are rated at 4KV isolation at the rise times I'm trying to achieve.

Assume that the elements of this circuit will never touch the ground at any point, aside from accidental contact, it should be floating at all times. The chassis the equipment is in is isolated from ground and is referenced to the battery's negative terminal.

Edit: Not shown, but there is a bridge rectifier and smoothing capacitor after the 4kv transformer.

Circuit Block Diagram

  • \$\begingroup\$ How are you expecting the mosfets to cope with an AC supply voltage? \$\endgroup\$ – Andy aka May 18 '15 at 17:53
  • \$\begingroup\$ I forgot to include the bridge rectifier/cap that the transformer connects to, before the MOSFETs. \$\endgroup\$ – Brian May 18 '15 at 18:18
  1. from my experiene (designed 60000 v DC supply) one should never keep it it asolated. i would strongly recommend earthing of the battary and NMOS source.VERY VERY dangerous.
  2. from your ckt diagrom it is NOT clear whether NMOS is subjected to 4KV voltage. VTIngole
  • \$\begingroup\$ Yes, they are subjected to the full 4KV (and rated for it) continuously. So, no isolation would be better in this case, then? \$\endgroup\$ – Brian May 19 '15 at 16:54
  • \$\begingroup\$ 1. Firstly I would still strongly recommend earthing. \$\endgroup\$ – vijay ingole May 20 '15 at 13:08
  • \$\begingroup\$ 2. NMOS devices are voltage triggered and unearth device is likely to pick up stry voltages from HV supply and may mal function. However, nothing like trying...request pl. take care. \$\endgroup\$ – vijay ingole May 20 '15 at 13:10

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