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Registered Member #1818
Joined: Thu Nov 20 2008, 02:02PM
Location:
Posts: 2
Hi guys. I was looking for a charger for my 450v bank when I came across WilliamN's design @
I'm using the same circuit, only with a 100uH coil and IGBT IRG4PF50W 900V 50A. I'm not using a TVS diode across the IGBT and it's getting hot but my main problem is I'm only getting 330v out of it @ 12v input. I'm wondering what exactly needs to be changed to get me to 450v+ or what I'm doing wrong. Also, will a TVS diode stop my IGBT from getting hot?
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Well, it says on his schematic that he had heating problems before adding the TVS. Just wanted to point that out :).
Also, you can add a voltage comparator to adjust reference voltage, like Uzzors': The charge time for a 4700µF, 430V bank is 30 seconds, meaning 15W of output power. Also, an led lights when reference voltage is reached.
Registered Member #95
Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308
You can try playing with frequency and duty cycle, but other than that there's not much you can do. Theo output power from these simple chargers is quite limited, and eventually you'll reach a point where losses and output power meet, and the voltage stops increasing.
Registered Member #1497
Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801
Don't forget that trying to squeeze more power out of a boost converter ends up overheating the inductor. I tried to overvolt my boost converter (based off of Uzzors design) and the inductor got too hot to touch at 3A...
If you are left hungry for even more power you might consider a flyback (custom wound) converter. I lost the link to a pretty good one but there have been dozens of discussions on boost converters so just skim through a few of them.
Registered Member #1818
Joined: Thu Nov 20 2008, 02:02PM
Location:
Posts: 2
Well I'm limited to 12v so I dont think I'll be overvolting it. I just rewound another inductor and I should be around 200uH now. Gonna try adjusting the freq/duty to get higher.
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555 based boost converter / cap charger
