Charge

 

It's not a question of regulating the output voltage. If its purpose is to charge the capacitor, then all that would be necessary is to switch it off when it had got there.
More important would be regulating the input current, and that would be much easier with a flyback topology. It may be possible to use a quasi-resonant configuration, but to maintain zvs all the way up to 850V may be tricky.

 

Hello, I want to know how the output voltage of a zvs-based stepup could be regulated so that it is powerful enough to charge a 9500 uf capacitor bank at 850V.

Do you have a schematic of such a stepup? Hard to give you an answer when we don't know what you are talking about.

 

Want

 

i want to charge it into 300 Vdc to 850 Vdc with a Mazilli ZVS flyback driver but intead of the HV secondary I want rewind it for the voltaje of my capacitor bank

That certainly does not tell me very much. Did you not get the memo about schematic diagrams being the lingua franca of electronic design. Your verbal description of the circuit is a poor substitute. I'm afraid I can't help you unless you make a better effort. As it stands I am not at all certain that you can even do what you want to do.

 

After thinking about it a lot, I'm only going to use a rectified microwave transformer and a 120 Vac variac, but could rewind to get 300v 400V 600V 700V 850V all that voltage after rectifying?

 

After thinking about it a lot, I'm only going to use a rectified microwave transformer and a 120 Vac variac, but could rewind to get 300v 400V 600V 700V 850V all that voltage after rectifying?

I'm not sure which transformer you intend to rewind. I think it might be the microwave transformer, but I could be wrong. I'm beginning to feel like a broken record player, but you need to communicate your plan with a schematic diagram so we can understand what you have in mind. Why are you so resistant to this suggestion? I do not understand your reluctance.

 

If You have to ask the questions that You have asked,
and made the unworkable/impractical suggestions that You have,
then You do not have enough Electronics-Education, or experience,
to be playing games with such extremely dangerous Voltage-Levels.

It's quite probable that You could kill yourself, or kill someone else.
.
.
.

 

It might be helpful in this thread to revisit, for the umpteenth time, the immutable rule of power conversion schemes. It is this:

​

The power out will always be less than the power in. Sometimes it will be a good deal less.​

​

You would do well to reexamine your plans to see if there are any potential violations of this immutable rule. Such violations will be a dead giveaway that you need to rethink your plans.

On top of that we still have only a vague idea of your ultimate goal and purpose. Why are you apparently being so obstinate about documenting those plans?

 

Sorry if I misunderstood, my plan is to have a variable DC voltage source to charge a capacitor bank fast enough, I searched the internet and found the zvs but it seemed a bit complex so I decided on a microwave oven transformer and connect the transformer to a variac to have the voltage I need and from that output it is rectified by bridge and charges the capacitor bank. And I wonder if instead of having that 1200V or 2000V output, rewind that transformer to have an output with a bypass of 100 200 300 400 500 600 700 800 Vdc, if possible how would you do it, what gauge would you use and for how many turns of the winding? Can I get a shunt that gives approximately the output voltage with the voltage described? I know that transformer is oversized and generates a lot of heat but it will only be used for a moment.
And I don't have a variac, maybe I'll borrow one but I don't know if they'll lend it to me

 

I think you may have some misconceptions about how things work and some of the terminology. Fast charging of capacitors does not happen with a voltage source. A voltage source only determines the final value. Fast charging is done with a current source. It is current that allows the fast movement of charge on to and off of the plates of a capacitor. When you use a transformer to step up the voltage from say 120 VAC to 1200 VAC, a factor of 10, you cut the available current from say 20 A (North American Standard) to 2 A, also a factor of 10, and this will slow down the charging rate. Right from the get-go you have shot yourself in the foot.

 

People who don’t what they are doing and want to charge a large capacitor to 1000V are often trying to build a rail gun.

 

People who don’t what they are doing and want to charge a large capacitor to 1000V are often trying to build a rail gun.

Now that you mention it the part of the schematic that is blocked out is a RED FLAG! I'm done with this thread.

 

I must have missed the part with the circuit. Using a variac to control the primary input of a microwave oven transformer will allow adjusting the output voltage over the whole range, BUT with no load I find the transformer wants to arc across the output and burn up. And the TS still needs a suitable rectifier rated for a fair amount of current.
REwinding a MO transformer will be difficult because usually they are welded and can not be taken apart to add lots of turns.
and the safety warnings have been inadequate, A 900 volt DC source is certainly able to deliver a fatal shock without overheating a single bit.