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Glassman HV Supply

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Steve Conner

Sat Dec 11 2010, 03:40PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

radhoo wrote ...

However, given my not-so-advanced electronics skills/knowledge, my questions were more related to a more practical approach. You gave me lots of ideas with pros and cons, but unfortunately I don't have the experience to pick and use one.

Unfortunately, in spite of all this advanced techno babble, I don't think any of us know what all the pins on the Glassman driver board do.

I'm not going to give you a step-by-step guide to making this thing work, and I don't think anyone else is either. I don't know what driver is best for it, but the driver is the easy bit. To make a successful regulated supply you need to understand negative feedback, control theory, Bode plots, compensation, load step tests, and all that sort of stuff.

If you're impatient and want results quick, just hook that sucker up to a ZVS and stand well back.

Pinky's Brain

Sat Dec 11 2010, 05:41PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
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Posts: 837

GeordieBoy wrote ...

Can it?!?! I thought you had to chop the primary current to make it go through the ferrite transformer?

Sorry wasn't thinking clearly ... you're right the current can't be continuous for the flyback ... but you don't have to chop off the current for forward converter though, that's what the two switch forward converter is all about. Instead of dumping in a snubber, using the current in the leakage induction to charge the input capacitor and reversing the voltage across the transformer resetting the core. Win win.

radhoo

Sat Dec 11 2010, 06:46PM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

Steve McConner wrote ...

To make a successful regulated supply you need to understand negative feedback, control theory, Bode plots, compensation, load step tests, and all that sort of stuff.
If you're impatient and want results quick, just hook that sucker up to a ZVS and stand well back.

Thanks for landing back on Earth.
What about using a PWM signal and a power transistor or half bridge, instead of a ZVS?

Wouldn't that give me more options in regards to controlling the output, maybe based on the feedback?

jpsmith123

Fri Dec 31 2010, 07:02PM

Registered Member #1321 Joined: Sat Feb 16 2008, 03:22AM
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Posts: 843

Wow! There's a lot of good info in this thread...a lot of food for thought.

It's encouraging to see this kind of commercial equipment with no messy oil or potting needed. (Although the HV secondary coil has most likey been vacuum impregnated with varnish and baked).

I wonder how many turns there are on those coils?

According to the link Steve posted, they're running those things somewhere between 30 and 70 khz.

I know there are winding techniques that can reduce the capacitance, but with such a large single coil (I'm guessing it must have at least 500 or 600 turns), it's nevertheless surprising to me that they can run it higher than 10 kHz, let alone 30 to 70 kHz.

radhoo

Sat Jan 01 2011, 07:02PM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

the secondary has about 800 Turns. It probably puts out only a few kilovolts.

I will use the multipliers without oil, for an output of 60KV. the soldering is very clean without sharp edges.

What I currently need is a way to adapt the driver to compensate the load on the output. I also have one original driver board that I might be able to use. I have 4 half wave multipliers and another one from a different supply with 2 flybacks and a full wave multiplier. Should I have some time for this, will get some nice results.

Arcstarter

Sat Jan 01 2011, 11:27PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

radhoo wrote ...

the secondary has about 800 Turns. It probably puts out only a few kilovolts.

I will use the multipliers without oil, for an output of 60KV. the soldering is very clean without sharp edges.

What I currently need is a way to adapt the driver to compensate the load on the output. I also have one original driver board that I might be able to use. I have 4 half wave multipliers and another one from a different supply with 2 flybacks and a full wave multiplier. Should I have some time for this, will get some nice results.

You could simply use PWM with an op amp sampling a voltage from a resistive divider. To help put it into perspective, something like this

but instead of a shunt regulator and opto, an op amp to adjust the duty%.

jpsmith123

Sun Jan 02 2011, 04:58AM

Registered Member #1321 Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843

800 turns? Oh baby...

That makes it even more amazing to me that they're running it at 30 kHz or higher.

BTW what kind of power output are we talking about?

And what kind of loads do you anticipate hooking it up to?

Th3_uN1Qu3

Sun Jan 02 2011, 06:24PM

Registered Member #2614 Joined: Sat Jan 09 2010, 08:57AM
Location: Bucharest, Romania
Posts: 26

Steve McConner wrote ...
To make a successful regulated supply you need to understand negative feedback, control theory, Bode plots, compensation, load step tests, and all that sort of stuff.

I'm doing some spreadsheets for precisely that. :) They will address designing a switchmode supply from the ground up - turns calculators, wire tables, peak currents, all that stuff. So far it only deals with the two transistor forward converter since it is my favorite type of switcher, but i will extend it to half bridge too since i deal with them often. Flyback, me not so sure. Haven't built one before, though i do have a fair share of gapped cores so maybe i should give it a shot.

The compensation part is always tricky but since "cookbook" equations do exist, plugging those into a handy easy to use spreadsheet seems like a good idea. Or maybe it's just me - if i have to do the same calculation more than 2 times over, i plug it in a spreadsheet and have it compute it for me.

radhoo

Sat Mar 26 2011, 09:08PM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

finally up and running, see

a negative output multiplier and a positive one, put together for maximum potential difference

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