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From: |
"Martin Helsing" <martin.helsing-at-earthlink.net> |
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Subject: |
RE: Mechanical Speed Control [TANKS] |
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Date: |
Fri, 8 Jun 2007 09:57:17 -0400 |
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Reply-To: |
tanks-at-rctankcombat.com |
And that is why I ask first and not call the fire department later ...
Frank P. wrote:
At the current loads required for our purposes, "a lot of heat" is
better stated as "a pretty serious amount of heat". Aside from the
wasted battery energy (which is significant), the problems caused by the
heat itself will have to be overcome. Furthermore, as you reduce the
voltage seen by the motors, they start to lose torque (our friend).
People used to use resistor motor controls in warships in the early
days, but even there the disadvantages make them impractical.
An ESC constantly hits the motor with full voltage (thereby maintaining
torque) and limits speed by turning off the voltage completely, thereby
conserving energy and reducing heat generation. The heat generated by
an ESC is due to the FETs switching on and off, but it is no where near
as much heat as a resistor would generate.
Thanks,
Martin