Remote Living > Transportation

Electric Car Controllers

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cdtomlinson:
I am new to this board, but have been researching alternative fuels, especially transportation, for years.  I guess my main issue is why are electric car controllers so expensive?  I know you are controlling a lot of watts of DC power, but still, there must be a way to do it without spending thousands of $$ to get it done.  Basically, all you are doing is deciding what portion of the whole load to send to the motor to make it drive the vehicle, isn't that correct?  Would love to build a car out of my Saturn, but overcoming the controller cost is a major hurdle.

Thanks to all that can help with this.

ghurd:
The problem is not the watts.
The problem is the Amps!

Plus any efficient speed control is switching the amps with PWM.

Reliably and quickly switching large quantities of amps requires very expensive parts.

There are solutions for some of the issues, but every solution comes with more issues.
G-

dnix71:
Used golf carts might be a place to start. You would need more than one to move a Saturn but the parts would be cheap enough to experiment with.

DanG:
Newer style golf carts using 48V systems should be coming off their leases at high-end clubs soon - keep you eyes open...

joestue:
short answer:

they aren't that expensive,  how much silicon do you think you should need to control a half megawatt motor? 
right now you can get the basic series wound motor controller for about one cent per watt.

if you can find the igbt's on ebay or surplus sites for 1/4th the standard price you can build your own and save some serious money.
If you want to take the risk, try paralleling 100, IRFP460 mosfets, as you can get these for about $1.39 a piece, and this would get you a series wound dc motor driver rated to about 350v @ 300 amp for about 400$ in parts, but it won't have regenerative braking.
Alternatively, the same silicon could build you a 25Kw 200-260vac 3 phase induction motor drive, and that would be a lot easier than making a 200Kw buck regulator.
but then you better be able to play around with 50mhz processors just to handle the PID...

an alternative to ^that is find an older totaled honda civic or such hybrid car and buy it off the insurance company. i don't know how much money the older inverters are still getting, but the geico agent i talked to the other day said he's never heard of them ever failing in the vehicle, so i should be able to get it for pretty cheap. (dunno what that means though)

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