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Old 11-22-2015, 11:27 PM   #2345 (permalink)
e*clipse
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Quote:
Originally Posted by P-hack View Post
Yes, lots of compromises, you probably have considered it, but it seems like the liquid cooled volt pack can push 900 amps, and you already have some liquid cooling in your future it seems with these motors (and hotrodding).

But instead of paralleling another pack, I would series it, since those motors prefer high voltage. Another 39 leaf modules will get you to ~650v, considering how many motors you are feeding... It was designed for a ~100hp car, and you are looking for ~400hp, so more batteries is entirely reasonable.

Also it occurs to me that the boost converter approach seems to be limited to hybrids, where you have a engine-generator to power the drive motors when needed. I don't know of any straight EV's that use a boost converter. The hybrid battery mostly fires up the engine and adds some power back on accell from regen. The boost inductor is out of the way of the high power current flow. The boost switches have a very different reality than the inverter switches as well, and have to handle 3x the current on average (with high peak loads and voltages).

I'm currently thinking the boost converter is probably best avoided in an EV, relying on field weakening and other control tricks instead (or motor retermination/reconfiguring, but that won't help your battery hp demands, only more batteries will do that).
Totally agree. Yes, the power output of the pack will have to increase. And yes, I'm adding some pack cooling. In my area, the temperature frequently gets above 100F average. The "tarmac" and parking lot temperatures can see 120F. Under - hood temperatures...

The problem I ran into when I figured a 650V pack was the solution is primarily weight. If I remember correctly, I was facing a 800lb pack, even doing the various pack-lightening tricks I could figure out. This may not seem so bad by lead-acid numbers, but I have a project goal that the car will be lighter than the original.

But, that's just me. I'm curious how others are looking at this issue. Would a controller like this be useful, or just a highly optimized thing for one specific application? Would a mild boost - less than 2X - be useful to others? In this case I'm also trying to design something that other people might want. This is why I'm taking to heart your suggestions about either improving or ditching the boost stage.

- E*clipse
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