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From: John Popelish
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X-Mailer: Mozilla 4.7 [en] (Win98; U)
Subject: Re: Where do they get those MOSFETS?
Date: Sun, 15 Dec 2002 01:36:56 GMT
NNTP-Posting-Date: Sat, 14 Dec 2002 20:36:56 EST
Bob Arnold wrote:
> I have designed/built H-bridge PWM motor controllers with inexpensive
> MOSFETS ($5) and I am now trying to beef up my design to match the
> characteristics of say a Curtis golf cart motor controller (48V @ 650A
> cost:$574) I assume they use an H-bridge configuration using IGBTs or
> MOSFETs, however I cannot see how they can because the components are
> either much to expensive(IGBT) or not capable of withstanding such
> high currents (MOSFETS);
> - IGBT - GA600GD25S - $248 - Vce 250, Ic 1200
> - MOSFET - IXFN200N07-ND - $35 - 70V, 200A (pulse width not obvious)
> - MOSFET - IRFP2907-ND - $6.60 - 75V, 209A (from the datasheet, the
> device can only withstand a 75V pulse of 200A for 100 uS)
> Am I misunderstanding the specs of the Curtis controller? What power
> technology do these (Curtis) controllers use?
I suspect you have a decimal point missing from that spec. 48 volts
times 650 amps is an product of more than 40 horsepower, and would
drain any golf cart battery in a few seconds. I suspect the output
current is more like 65 amps peak (not continuous). That would also
bring the cost for suitable mosfets more in reach. Are you sure they
do not use a single chopper (possibly a darlington) and a reversing
relay? I worked with a 70 amp 24 volt version they made, years ago,
and that was the technology, then.
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