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Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
Well, after a few adjustments I have gotten my buck converter up to almost 5kw with a 780vdc input. I need to add some more diodes to handle higher current. I want to get to 10kw.
Question:
Right now I am using a variac to increase my test voltage. I increased it from 0 to 280v, and this went into a voltage doubler. Each capacitor is 1500uf.
Now the final version won't have the variac; the high voltage will connect directly to the 240v line. I noticed that when I have it set to 140v and I turn on the switch there is a large surge current. The caps on my doubler are acting as a short. I don't think I want to see what happens if I turn it on at the full 280v.
Is my only option to use smaller caps on the doubler? Is there a way to limit the inrush current to the doubler when I turn the unit on?
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
IamSmooth wrote ...
Well, after a few adjustments I have gotten my buck converter up to almost 5kw with a 780vdc input. I need to add some more diodes to handle higher current. I want to get to 10kw.
NICE! mucho kW!
IamSmooth wrote ...
Question:
Right now I am using a variac to increase my test voltage. I increased it from 0 to 280v, and this went into a voltage doubler. Each capacitor is 1500uf.
Now the final version won't have the variac; the high voltage will connect directly to the 240v line. I noticed that when I have it set to 140v and I turn on the switch there is a large surge current. The caps on my doubler are acting as a short. I don't think I want to see what happens if I turn it on at the full 280v.
Is my only option to use smaller caps on the doubler? Is there a way to limit the inrush current to the doubler when I turn the unit on?
yes there is a way i overcame the same problem, though mine topped out at 1.2kW. My solution... to use a R in series with your C bank, then use 5 x RC to calculate your 99% V level, then a relay/transistor/scr is used to switch the R out and your main circuit over to line power.
IamSmooth wrote ...
Is this useful?
I investigated this too, many plumes of smoke later I wouldnt recomend it! i even used this same company, the problem is that the maxiumum throughput current is kinda limited and when they heated up i tended to have problems with them bursting flame, and smoke. they are good for 500 watts or less though, maybe 1+kw, but at 2+ kW ive never had one be reliable.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
If I flipped the switch and connected 240vac to a voltage doubler (two 1500uf caps in series) would this blow a 30 or 50A fuse? I am looking to see if anyone has done this already. Is there any chance of blowing the capacitors if they are rated appropriately for the voltage?
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switching noise/spikes on buck converter
