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Old 07-01-2011, 12:35 AM
valerun valerun is offline
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Default Re: Another DIY DC controller mock

more fun today:
1. swapped 5 Ohm Rg into 20Ohm
2. lowered switching frequency to 5 kHz
3. still 30V pack

took the thing to 600A output, which is 50% of the combined continuous rating for the 2+2 devices I am using. Spiking across the switch is now limited to just +70V. This is linear to the current so I expect ~100V at 1000A. Of course, switching transition is a bit long now - especially on turn ON - to the tune of ~5us.

So I'm thinking to use a 5 Ohm as a turn-on Rg and 20 Ohm as a turn-off Rg. Also want to hook up a shunt to measure current waveform so I can calculate the losses.

Also probably will have to take the switching frequency down a bit more. The only thing is: got to watch out the caps. Have 17000uF on the bus now which should be good for 1000A output at 300V pack voltage at 5kHz.

Some pics attached.

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