Subject:
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Re: Controlling a DC motor 3
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 5 May 1998 00:01:06 GMT
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Original-From:
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Mike Vande Weghe <vandeweg@nameconnector.com^saynotospam^>
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Viewed:
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1503 times
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> Within limits, the rate doesn't matter much. What matters is the
> ratio of off time to on time (i.e., the duty cycle). Probably, you
> could change the frequency by an order of magnitude either way and get
> about the same results.
Actually, the frequency is somewhat important. The faster you switch,
the more power will be lost to the switching of the power transistors
and the filtering effect provided by the inductance of the motor. At
the other extreme, frequencies that are too slow will cause the motor to
run sporadically instead of smoothly. For the motors I'm using I ran an
experiment of controlling the motors with a constant power ratio and a
variable frequency, and found that the optimum frequency was around
30Hz. Of course, that number is entirely dependent on the motor design;
smaller motors will need faster frequencies; larger motors will probably
do better with slower frequencies.
- Mike
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Message is in Reply To:
 | | Re: Controlling a DC motor 3
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| (...) Within limits, the rate doesn't matter much. What matters is the ratio of off time to on time (i.e., the duty cycle). Probably, you could change the frequency by an order of magnitude either way and get about the same results. --Will , , __@_/ (...) (27 years ago, 4-May-98, to lugnet.robotics.handyboard)
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