Big DC motor on ebay

[MazdaMatt]

dcb, you bid on it? (o***e?) Good stuff
7 hours remain, i hope it works out for you!

That 200 pound motor could handle a good deal of heat-soak, i expect. You may be able give it some serious peak wattage Get on board with the ReVolt Beta Testing! You could have a complete motor/controller combo for 400 bucks, add in 600 in batteries and you're cruising electric!

[dcb]

o**e, thats me, yup. The motor is just a few towns over. I'll be happy with the stock wattage I'm sure

I would consider a revolt, but I'm wondering about IGBTs too as it was mentioned in this thread: http://ecomodder.com/forum/showthrea...html#post12804

[MazdaMatt]

dcb... one of the loose design aspects of ReVolt is the seperated power and control. Buy the parts for the control board and make your own cap filter and gate driver board. IGBTs have the huge (in my opinion) advantage of being case-mounted (they have mounting holes and isolated copper bases). So you have a control board, a filter/drive board and a bigass IGBT bolted to a heat sink. IGBTs usually have screw or spade connectors, so you're removing about 100 solder joints and all of the problems with turn-on times.


do it... do it... do it... you know you wanna...

[Wherewolf]

A motor last week (about the same size) was a 1 ($100) bid until the very end, then it went for $210.00, so someone's snipin'.

I would be cautious of anything that required a whole new rattlecan paint job to go up for sale as a used motor....but I suppose it's worth $25 dollars in scrap if it's no good.....

Wherewolf

[MazdaMatt]

I'm really rooting for you here... I hope all it needs is a clean up and you're good to go

Why does it say you bid twice?

[dcb]

I upped my bet a little bit. Not much, it is just a tactic. It will get sniped, but it is fun to pretend

I got a nice IGBT I'm looking at too on the cheap: http://www.pwrx.com/pwrx/docs/cm600ha24h.pdf Any thoughts on that?

[MazdaMatt]

I have put a number of hours into researching IGBTs and my answer is.... I have NO idea. It is complicated, to say the least. Was that one, by chance, the 60 dollar "buy it now" lot of used IGBT's with the 25 dollar shipping? I'm really not sure what to choose.

I was thinking though... you might want to get a "2-pack" IGBT so you can do synch rec. That is... if the IGBT has a lower Vdrop than a diode would... not sure.

I was going to start a thread on DIYElectricCar asking if the experts had a sure-fire list of IGBT's or maybe as a place to say "is this one good?" so the experts can comment.

[dcb]

Well this one is like $60 shipped
PRX - IGBT CM600HA-24H Power Module 1200V 600A - eBay (item 290049066472 end time Apr-27-09 14:17:07 PDT)

I guess the "dual" response would be, how much efficiency gain are we talking about, and is it only at full throttle, vs cost/complications, ya know. Is it good enough to get started with, kinda sounds like it will handle 48 volts 300+ amps no problem. Throw some pwm at it and monitor the current I recon.

Also the synch gains are probably frequency dependent.

[Tango Charlie]

Aww, dang. You got outbid. Still cheap, though. C'mon, bid again! j/k

[MazdaMatt]

IF the power loss across an IGBT is LESS than the power loss across a freewheel diode, then the gain from syn.rec. comes during the "off" portion of the PWM and is relative to the current...

Basically, when the driving switch (mosfet bank or igbt) is off, the current still has to flow somewhere (because the motor is a huge inductor), so there is a freewheel diode in there. Typically a mosfet bank will have a lower Vdrop then a diode, so when you turn off the driving switch, you turn on a mosfet in place of the diode. That's sync rec. So if you are pushing huge current, you get huge gains in efficiency.

If you want to K.I.S.S, then just use a freewheel diode and account for the heat.