Electronics > Power/Renewable Energy/EV's

PWM'ing thousands of amps

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Faringdon:
Hi,
I know this is common activity widespread all over the place, and no industrial secret, so if you have say a 10V battery, and you want 10kA's through a 1 milliohm load, (for 100ms) you turn an IGBT on  and thats that.
But say you want 5000A's (on average) from the same battery and load, do you then like to simply PWM the IGBT on and off at a frequency of a 1kHz or so?
(Add inductive filters to stop the di/dt being so high etc etc)

Andy Chee:
Maybe on a related note, I've always wondered what the power supply of an aluminum smelter looks like (5V DC @ 200kA). 

I doubt they use PWM or any fancy switch mode voltage regulation, they probably just switch taps on a giant transformer or something. 
But the diodes must surely beefy monsters!  And what did they use for rectification before semiconductors?  Did they make mercury arc rectifiers that big?

Faringdon:
Thanks, we are making an RF jammer, so we need to switch thousands of amps on and off.
The load is just the very low inductance coil, which has say a milliOhm of resistance.

Sometimes we just want to switch on and pulse the load for say 100ms with 14000 Amps or so.

The device is also believed to be useful in activating (or indeed deactivating) land mines.
A friend of mine built one in his garage...used to just pulse away from a big cap bank.

When i worked in the security cash box industry we made such a 14000 Amp pulse power supply in a few weeks. We were seeing if it would "gouge" the internal electronics
and open the cash box. So i know this sort of thing is very very common. What say you to a spot of PWM with  a 5000 Amps source?....you know, turning it on and off with a duty cycle so you get on average 2500 Amps.

Zero999:
Is that even legal? I thought radio jamming was against the law.

Why not use a super capacitor and a coil?

Does this have to be reusable or is it a single use item?

Ian.M:
Whoops!  Fire that up anywhere remotely near anyone important and OFCOM can throw you in jail for two years, and/or fine you so much you'll be paying it off for the next fifty years.  If the lads with no sense of humour from three letter agencies take an interest and decide its terrorism related, your future will be even worse, with the possibility of being handed over to the yanks to throw into gitmo!

The only thing that's going to save your ass, is that I doubt you are competent to build a circuit to pulse even 100A well enough not to meltdown within a few milliseconds of first power up!  :popcorn:

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