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Turns ratio change

HV power supply...160kV/15mA

400vdc pfc rail; Multiplier, 10 stage: I've changed my primary turns from 19 T to 15 T and changed secondary turns so ratio stays the same, yet I am unable to acheive same output voltage- It's a 10 stage cockroft-walton multiplier. I would have thought that I would not need to change tuning, just to expect larger Ipri. HV switcher f=25kHz. I'm only able to get 140kv at this current. I believe I am within my 'resonance' window... Can someone give a clue? (I'm a tech, not an engineer... )

TIA

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me
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You might be saturating the transformer core.

I can't guess enough about the system topology to tell how other parameters (frequency) might have changed due to your modification. But a quick rule of thumb is that a transformer core is good for a certain number of volts per turn (assuming a fixed frequency).

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Paul Hovnanian     mailto:Paul@Hovnanian.com
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Paul Hovnanian P.E.

Thanks, Paul

I got diverted to another 'emergency'... Primary current usually shows a large increase when saturation occurs, and I don't see that. Give me a few days to get over this situation and will try to get more clues. One thing I have done before is increase secondary tuning capacitance, but I don't like doing that... (Too many HV gotcha's, physically)

The front-end seems robust enough, staying at 400vdc. freq is rock solid. Right now I am leaning toward some insufficiency in the brick(multiplier). Mebee AC caps or something... sigh

Thanks!

Reply to
me

Post some more details on the power supply. When you mention 'tuning' there are lots of things that can interact to affect performance. There are a number of power supply wizards lurking here that might spot the problem.

Did you by any chance measure a few points before and after the modification? The input voltage to the multiplier would be an interesting point.

Change in operating frequency (if any) might also be of interest.

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Paul Hovnanian     mailto:Paul@Hovnanian.com
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"There\'s something vewy scwewy going on awound here." -- Elmer Fudd
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Paul Hovnanian P.E.

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