Explanation Required for High Power Switching Power Supply (3-60v 40 Amps)

[Warpspeed]

If this is your first attempt at building a high power switching power supply, I strongly suggest you keep it all as simple as possible to begin with.
You can always add the PFC stage to it later once the rest of it is going if you wish to do so.

 

[adnan012]

I have designed a 800v Solar VFD 5HP recently.

 

[adnan012]

Can i wind Gate Driver using this this winding technique?

 

[Warpspeed]

Possibly, if the toroid is very high permeability ferrite.

 

[adnan012]

I have few toroides (black color) used in spms as input choke etc. Will they work?

 

[treez]

Yes if they are ferrite, if its a filter inductor, then it could be made of low permeability cool-mu or similar, not like ferrite.
Wind a few turns and asee the inductance, if it gives an AL value of 1000 plus than its likely to be ferrite.

 

[Warpspeed]

I have few toroides (black color) used in spms as input choke etc. Will they work?

Very unlikely, try it and see.
Its probably a grade of power ferrite.
RF ferrite is equally unsuitable, and so are all powdered iron toroids.

The problem will be getting enough inductance as gate drive will be a square wave, and you do not want to see a lot of droop.
Almost no chance of salvaging something suitable, you will need to order in some suitable cores, and even then fitting on enough turns to make it work well enough might be a challenge.

 

[adnan012]

3 turns give 13uH.

At 10kHz, 20 turns of AWG 18 wire the inductance is 365uH.

 

[Warpspeed]

That's actually not too bad.

Depending on the gate drive frequency, you may find you need at least 1mH so probably about 27 turns minimum.
Try it, and see what the output waveform looks like when driven with a 25v peak to peak square waveform.

Conventional wire wrap wire is pretty good stuff to use for this. It has teflon insulation and is fairly thin.
Excellent high voltage insulation and high temperature rating.
And its physically pretty tough, and comes in different colours for multifilar winding.

 

[adnan012]

Is it possible to use IR2109 bootstrap type driver with 2 switch forward converter (sensitive to -ive voltage spikes).

Or use two FOD3120 gate driver with isolated power supplies?

 

[treez]

you cannot use a bootstrap chip for a 2 transistor forward, there is another thread on this..here...

https://www.edaboard.com/threads/340530/

- - - Updated - - -

fod3120
https://www.fairchildsemi.com/datasheets/FO/FOD3120.pdf
you cannot use fod3120, its delays etc are too long. Also 35v/ns isn't much transient immunity.
1EDI20N with a high side power supply would be a possibility though

 

[adnan012]

Where FOD can be used?

I did not get your words

"you cannot use fod3120, its delays etc are too long. Also 35v/ns isn't much transient immunity."

 

[Warpspeed]

Is it possible to use IR2109 bootstrap type driver with 2 switch forward converter (sensitive to -ive voltage spikes).

Yes, it will start up and run fine.
There should not be any -ve voltage spikes if the lower diode is working properly with very short lead lengths.

 

[treez]

FOD3120 is ok for slow igbt drives.

 

[adnan012]

The Bootstrap capacitor will charge through the primary inductor?

 

[treez]

http://www.irf.com/product-info/datasheets/data/ir2109.pdf
IR2109 cannot be used unless used in the method as described in post #31 above....the linked thread there

 

[adnan012]

I think FOD3120 can be used upto 50Khz.

 

[treez]

delay is too long for 50khz, rise time is too slow.
The boot cap wont recharge through the inductor, but supposedly through the lower diode, but this has problems in light load.......as discussed, the linked thread in post #31 discusses this.

 

[Warpspeed]

The Bootstrap capacitor will charge through the primary inductor?

Yes, that is how it starts up initially.

Once its going, there will often be a negative overshoot spike and some ringing from leakage inductance large enough to briefly turn on the lower diode and recharge the bootstrap.
In theory it should not work, but in a real practical running circuit the waveforms are never text book perfect. Some ringing and overshoot will always be there and its usually sufficient. Very little power is needed to recharge the bootstrap.

 

[adnan012]

Can i change the power converter topology to push pull? What about making push pull type gate driver with discrete transistors (with isolated power supply and high speed logic converter like 6n137)