High voltage (2.5 KV) H-bridge, low current, low frecuency

fernandomierhicks · Mar 5, 2012

Hi:

I need to alter the polarity of a high voltage source connected to a load at around 1 hz.

I have a high voltage (2.5 kv) power supply that has positive and negative outputs that can be floated to any ground reference. I basically need a high voltage H-bridge. Current is minimal, in the order of microamperes.Space is a very important aspect in the design.

Do you have any ideas on how can this be achieved? (High voltage transistors, mosfets etc)

Thanks

Fernando

Windadct · Mar 12, 2012

You have a 2.5KV 1Hz Supply - and want to reverse the polarity? - I have read your post a few times and do not understand what you are asking.

fernandomierhicks · Mar 12, 2012

I have a fixed 2.5 kv supply. The high voltage ground can be floated to any other level basically. How could you do get a -2.5kv +2.5kv square wave from this setup. I was thinking somehting similar to a H-bridge circuit that could handle the 2.5 kV...

(*steve*) · Mar 12, 2012

A high voltage H bridge will give you a 5kV square wave.

The problem will be finding devices to handle the voltage and then (if you're using mosfets/IGBTs) generating an isolated +/-15V signal to turn them on and off.

Maybe you can use some isolated DC-DC converters that have appropriate isolation, and optocouplers to do this.

Way above the voltages I'm comfortable working with...

Windadct · Mar 13, 2012

Hello Again - an H bridge as Direct Inverter or PWM operation could do this, the PWM can regulate the voltage if desired. But the switching devices and controls at this voltage are another issue - not a trivial project and not cheap. I would first try to use a Low Voltage source, and switch at low voltage and then use a step up transformer to get the +/- 2.5 KV.

To get the Square wave using the HV supply to be +/- 2.5 KV, you would need to have series connected Capacitors ( and sharing / bleeder resistors) in the DC link, pull out the neutral point and then use that as the ground reference. ( of course the HV supply is left without a ground reference at all, but the chassis should be OK to ground to the same point if it is indeed a floating output.)