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Old 11-24-2015, 02:08 AM   #2364 (permalink)
e*clipse
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Quote:
Originally Posted by MPaulHolmes View Post

As for the boosting, where is the 3x current coming from? I have 2 intended uses in mind for the super cheapo AC TO-247 controller with boosting. First, I just wanted to allow higher RPM under load. I have a 200amp 300uH inductor, and my simulations seemed to show that things stay under relative control in that situation. There is a ton of capacitance (to keep things cheap, I am using a bunch of 450v electrolytic caps. heck it worked for the 500amp controller), which I hope will allow for a dual use as a solar MPPT/ 3 phase grid tie. And if you don't want to go to jail, you could instead use it as a MPPT/ 3 phase "not grid tie" sort of thing. I bet there are people who would want 3 phase power at their house, and who have maybe 12 lead acid batteries laying around. Well, maybe there aren't but I'm going to pretend that.
Ok - I want one of those. I could power my lathe & mill with my solar system

I've done some calcs about boost converter design using some TI app notes, and the numbers work out very well. In a nutshell:
Input voltage minimum: 468V (144 Leaf cells in series at a minimum 3.25V)
Output voltage: 650V
Output current: 115A ( 75kW - obviously 50kW or whatever would be lower )
boost duty cycle: 33.75%
switching frequency 10kHz (also worked out for 25kHz)
inductance: 273uH ( running @ 25kHz, it's 109uH )
Max switch current: 202A (well under the maximum of 300A )
Output ripple voltage: 13V ( 2% of the 650V bus )
Output Capacitance 298uF ( running @ 25kHz, it's 119uF) Both available from SBE.
Using a low inductance bus an a ultra-low ESR capacitor, the ripple due to the capacitor is completely negligible.


In fact, a 200A, 300uH inductor would be almost perfect. Do you have any specs on it?

Also, do you know if the DSPIC 6010A/6015 will run the PWM with two different switching frequencies? It might be best to run the booster at a higher frequency than the inverter, depending on the switches used.

- E*clipse
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