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Unread 05-05-2009, 19:35
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Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
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Re: Sensorless back_emf speed controller

Chris,
Don't forget that the coast/brake mode only affects the turn on of the two lower pairs of FETs when the PWM goes to a value that would represent "off" i.e. no direction. During that time, the two FET groups (six FETs in all) would present a short to the motor. Effectively, this is about 6-8 mohm at the output of the JAG. The Jag also produces a charge pulse to charge up the cap in the voltage doubler of the FET driver chip periodically.
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Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
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Storming the Tower since 1996.