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Old 01-08-2015, 05:07 PM   #1543 (permalink)
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Yes, I think we need to design something based on a real world scenario.

Technically Paul is designing this to allow 208V motors to be operated on 144V packs.

A 208V motor being operated at 300V is never going to draw 400Amps. Not even motor amps. Increasing the voltage will increase HP, but the amps will stay the same.

At 20HP the maximum battery current draw would be about 150Amps. A 18HP motor (50Hz) weights roughly 95KG. Anything above that is casted steel rather than alluminium, which is probably out of the scope for EV conversions.

have a look at joannes graphs on DIY Electric car. I believe his motor is 15HP running at nearly 500VDC.

I run a 10HP 208V motor at 409V and anything above 70A (battery side) is waste.

So perhaps an output of 200Amps at 600V would be more suitable for a high performance conversion, with most staying at 100Amps max.

The question now:

Is it really worth to maintain compatibility with a 144V system for those that are looking for a medium size performance (up to 60KW)? Probably yes!

Is it really worth to mantain compatibility with a 144V system for those looking at high performance (100KW or above)? Probably not!

That would allow a downsize from 400 (initially 600) to 200 input amps.
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