Quote:
Originally Posted by learnerguy
Hi all,
Can you please guide me with making a 10 to 20 Kw controller for use in motorcycles.
What parts do I have to downgrade and will it be ecnomically viable ?
I am following Paul's instructions on instructables .
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My un-informed opinion, and a few un-informed assumptions
- 20 kw = 26.8 hp (I need this for torque)
- 5,000 rpm for a decent small AC motor (it should be higher)
- 2 pole motor (3600 rpm at 60 Hz)
- 72V pack
72V pack is about 50 VAC or 50V rms
20,000W / 50V = 400 amps. For short periods of acceleration. Maybe 5 HP for cruising is under 90 amps. That's still over 2C on your battery pack if it is 40 A-h. Less than 30 minutes of cruising ... much better in town!
I chose a motorcycle that I have heard of - a yamaha XT660 - and used the gear ratios. !st gear gets you about 100 lbs pushing the bike and you down the street. Decent for acceleration. 5th gear is 5000 rpm for 80 mph. Also decent.
The controller is only putting out 100 Hz at 5000 rpm. It can put out much more. 400A IGBTs should be fine since it will take .. not much time ... likely under 2 seconds? .. to accelerate through any one gear. A decent chill plate would get the heat away from your IGBTs. Or you could use a big set of fins ... depends on what speed you would normally drive. air-cooled does not do well under 20 mph.
The parts that Paul is recommending for the board are in the ?$125 - 150? range if memory serves. That is not a big portion of the cost. The ring cap and the IGBTs are expensive. The chill plate .. is sort of expensive depending on if you do it yourself or have to pay someone.
Paul - does smaller DC/DC for the separate IGBT drivers drop significant price? Or maybe smaller caps? I wouldn't think so.
My opinion - leave the controller board the same - reliable and tested - trim cost by using smaller power electronics with lower max voltage, a lower voltage rated cap, and maybe leave the 3rd phase off the current as Paul suggested. There are not many spare pins on the controller for doing pre-charge and interlocks. You may want to use an arduino or some other separate MPU to annunciate any problems and do the interface with the user.
Are you planning to do a production run? Is that why you want to minimize costs? If you are making under 10 I would expect any changes may end up costing instead of saving.
YMMV ... and it's only my opinion ..