Hello all,
I wish to know what information can be determined by driving a DC motor with a sine wave (no DC offset) for testing?
I would expect, that the motor would go in one direction on the positive peaks then reverse to the other direction once the sine when into the negative, and so on.
The frequency of this sine could be varied, effects observed, what would this tell me?
How about once the motor is connected into the gear system and is now under load?
If you're testing it as part of a control system design and if the motor and all the stuff it is attached to behaves as a linear system then you can adequately characterize the system by looking at the gain and phase shift of the signal at a variety of frequencies. For a _purely_ linear system you can _completely_ characterize the system by getting all frequencies from DC to infinity, but this is a bit hard to do in practice so you generally try for enough frequencies over a wide enough range.
A permanent magnet motor will oscillate (or try to) at the frequency of the AC. A series wound, or "universal", will run as if it's getting DC, at the RMS value of the AC. If it's a "brushless DC", with control circuitry, then all bets are off.
Good Luck! Rich
No, the bets are not off. The BLDC circuitry won't want reverse polarity.
Rene
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