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Registered Member #1143
Joined: Sun Nov 25 2007, 04:55PM
Location: Vilnius, Lithuania
Posts: 721
Hello, i have some project coming up, and i need 16b HV power supply, capable to change voltage at least at 100KHz (For pockels cell, so it's like 5-10pF capacitive load) Any one know how to do it ? For now i thinking about H bridge from two class A amplifiers, but can i do better ?
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
The guys I'm currently working for have another team trying to build an agile SMPS that can do +-15kV peak at up to 1kHz. They've been at it for a while and there has been a fair amount of magic smoke.
I'd use two vacuum tubes like the 811, 572B, GU81M, 833 or 4PR1000A, connected as a White cathode follower. Wireless filament power for the high-side (ask Marko :) )
You could either run it off 4kV, or build two copies and drive them 180 degrees out of phase.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
I have no idea. The Art Of Electronics shows a series MOSFET stack that could be adapted, but I expect it would have serious problems maintaining even voltage sharing at high frequencies.
Registered Member #1143
Joined: Sun Nov 25 2007, 04:55PM
Location: Vilnius, Lithuania
Posts: 721
Sulaiman wrote ...
Just a quick sanity check .... 2kV pk @ 100kHz across 10pF = 6.28 A pk ..... must the switching be pulse/squarewave ?
I am developing feedback loop with pockels cell. in real life i will have small voltage changes, like 100-200V, I have to control dispersion from PID loop, that it,so i need to have few kv range while surfing in scientific literature i found that for my task i only need +-1Kv, so 1700V JFETS should do the trick
Registered Member #1143
Joined: Sun Nov 25 2007, 04:55PM
Location: Vilnius, Lithuania
Posts: 721
Antonio wrote ...
A 10 pF capacitor at 100 kHz has an impedance of 1/(2*Pi*100000*10e-12)= 159e3 ohms. 2 kV over this results in 12.6 mA. Still not easy, but possible.
Well, idea is this. since JFET will be driven in different phase, total load always will be the same, and equal 20W. this is good for DC power supply, since it will not get into step response and kill my JFET's
Now, how to get clean 20W 1,5KV power supply, i don't think that simple push-pull will be low noise ? Idea use resonant converter with full wave bridge rectifier, and current regulator for that converter which connects to HV DC output and regulate current for resonant circuitry.
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HV DAC +-2KV
