03-14-2012, 08:14 AM
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#5541 (permalink)
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Master EcoModder
Join Date: Apr 2009
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Quote:
Originally Posted by bennelson
They have a couple of DC motors that are rated for pretty high voltage. The Open Revolt will work fine with those motors, but you will have to keep the charged battery pack voltage lower than 200VDC.
You probably wouldn't want to do more than a 156V nominal battery pack. It would still run a Kostov fine, it just won't spin as fast as it would at a higher voltage.
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156V nominal battery is the highest you would want to go with a 144V controller model.
The voltage spikes from switching will destroy parts rated for 200V when you use a nominal voltage over 156V.
-Adam
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03-14-2012, 08:35 AM
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#5542 (permalink)
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PaulH
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Quote:
Originally Posted by teraamper
Hello
I wonder, what is the point of control the +12V from the DC/DC for driving fet's.
If there is not present, the fet's can't open any way.
Is there open the battery contactor, if the alarm UV Fault is present. 
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The 10 mosfets' gate voltage is relative to their source leg. If you didn't have an isolated DC-DC, your microcontroller's ground will be at the same potential as the battery pack ground, which is very noisy. The UV Fault right now just disables the mosfet driver. It would take one like of code to disable the contactor too if you wanted. |
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03-14-2012, 10:09 AM
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#5543 (permalink)
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EcoModding Lurker
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Then this feature is unnecessary, because if the dc/dc is broken, then is no power in the mosfet driver, and I can not open the mosfet or the mosfet's can open by it self. I thik if any alarm UV Fault is present, then the battery contactor should be open.
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PS
I can move the transistor Q3 from the driver section to the battery contactor. On the opto. U9
Last edited by teraamper; 03-14-2012 at 10:30 AM..
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03-14-2012, 01:36 PM
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#5544 (permalink)
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PaulH
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If the DC-DC fails, the voltage would take a finite time to fall. During the time it goes from 9v down to 0v, the mosfet driver would be off. So, the mosfets would be off.
Now, let's say we removed the undervoltage circuit. Let's imagine a situation where the dc-dc started to only put out maybe 4 or 5v for some period of time. During that time, the mosfets would quickly burn up, since it would take forever during the transition period. The PWM would still get through, but they would take forever to turn on, and a huge amount of heat would be burned up inside them.
If the DC-DC instantaneously fell to zero volts, then there's no cause of concern, since the mosfets would be off, because of the pull down resistor from gate to source.
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The Following User Says Thank You to MPaulHolmes For This Useful Post:
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03-14-2012, 02:04 PM
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#5545 (permalink)
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EcoModding Apprentice
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oh hey, i guess it never got posted here, but we totally blew away the competition with our electric machine this year at the SAE Clean Snowmobile Challenge! first place in all but two of the nine events, and first place overall. this controller is great. even let it sit outside overnight for eight hours at probably 15 or 20 degrees, and it worked perfectly the next morning.
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The Following 6 Users Say Thank You to isaac_alaska For This Useful Post:
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03-14-2012, 02:09 PM
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#5546 (permalink)
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PaulH
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I wanted to post it, but thought I should let you, since you guys actually made the dang thing! hurray!!!!!
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03-14-2012, 02:10 PM
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#5547 (permalink)
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EcoModding Apprentice
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03-14-2012, 02:13 PM
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#5548 (permalink)
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EcoModding Apprentice
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Got behind and MISSED coming to see you Isaac ... 
But - great job - I sent some Robotics students there to watch. I heard your sled was super!!
__________________
Dave  ...
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03-14-2012, 02:27 PM
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#5549 (permalink)
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EcoModding Apprentice
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oh well, there's always next year! it should be even better. we are planning to replace the DC motor with a permanent magnet synchronous motor. that should effectively eliminate the rpm limit |
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03-14-2012, 03:34 PM
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#5550 (permalink)
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PaulH
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Isaac, was that you in "the pants"? hehe. Do you have any drag racing videos?
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