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Topic: 3-phase brushless motor. Why are these stators wound like this?? (Read 401 times) previous topic - next topic

pulse_wid

I have a motor controller that works fine on some small dvd player motors, but after unsuccessfully trying to run this motor I opened it up and unwound the motor and realized that the stators are wound in a row rather than alternating, i,e abc, abc, abc, etc. How could this motor run even if you had the right controller for it? It seems like the stators would be pushing and pulling the rotor, wouldn't it be fighting itself? The 5V motor is from a 2.5"  hard drive. There are three wires that run the motor.



raschemmel

Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,
DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter


raschemmel

Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,
DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

MarkT

Typical windings are one pole-pair per a-b-c stator section, so the magnetic vector
is synchronous to the rotating field generated by the stator.

The deep requirement is that the rotor spinning induces AC waveforms in the windings
such that the three terminals are roughly sinusoidal and 120 degrees apart (balanced
3-phase).  Motors are automatically generators too, sometimes its easier to think of
what happens when generating.

There are lots of more complicate stator schemes.
[ I won't respond to messages, use the forum please ]

Chagrin

Are the stator phases all wound in the same direction (clockwise/counterclockwise) or do they alternate? I'm betting they alternate, and knowing that the rotation of the winding affects the polarity of the electromagnetic field I assume that would answer your questions as to why it's not actually fighting itself.

MarkT

Depends on the winding pattern, the simple abcabc pattern is all the same way(*),
but more complex patterns have inverted sense windings, and these are denoted
by a change of case, such as aBcAbC

(*) relative to the relevant terminal for that phase.

Its common to connect all the windings of one phase in series, although parallel
is also possible (but the motor constant can be too low then).  When connecting
windings in parallel the turns count must be accurately matched though.
[ I won't respond to messages, use the forum please ]

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