Multistage Half-Bridge Coilgun: How to charge capacitor banks?

maruiwlt, Mon Nov 19 2012, 06:29AM

Hello all, I'm working on a multistage half-bridge coilgun... I'm using the charging circuit from uzzor's site which is pretty expensive to build, so I was trying to think of a way to use only one charger to service all the capacitor banks.

I came up with the idea pictured below: My thinking is that as long as there is at least one capacitor bank connected to the bridge rectifier's output while the charger is on, the relays will not see any significant voltage across their contacts so I could pretty much use any general purpose relay. This way I can charge each bank one at a time using only one charger.

Does this sound like it would work?


1353306189 859 FT0 Idea
Re: Multistage Half-Bridge Coilgun: How to charge capacitor banks?
Jazzman56, Mon Nov 19 2012, 11:41AM

Maruiwlt

(Not sure if this is true for capacitors but please correct me if i'm wrong )
If you where to charge one capacitor bank then flick the relay onto another (that is at a lower Voltage) the charged capacitors would dump part of there charge into the lower V cap bank until both balance out. i.e may burn your relay out.

Re: Multistage Half-Bridge Coilgun: How to charge capacitor banks?
maruiwlt, Mon Nov 19 2012, 07:10PM

Ahh, I forgot about that... So i would need relays that could handle whatever voltage the caps will be charged to.

What methods have other people used to charge caps for multistage cgs? They all just have their own charging circuit?
Re: Multistage Half-Bridge Coilgun: How to charge capacitor banks?
PSCG, Tue Nov 20 2012, 09:43AM

You could use the method that Another Coilgun has implemented: isolating the capacitor banks via high voltage diodes.

Link (under the "Voltage Charging-Parallel")


Parallelcharging1
Re: Multistage Half-Bridge Coilgun: How to charge capacitor banks?
maruiwlt, Tue Nov 20 2012, 10:07AM

Ahh can't believe I missed that. Definitely gonna look into that method! Thanks!