Hi,
Brushless, sensorless motors with three connections are in
fact, not DC motors at all. They are actually permanent
magnet synchronous AC, 3-phase motors.
The commutation is done electronically. Three distinct
semi sinusoidal waveforms (not pure sinewave AC) that come in
at different times (or degrees) will causes the rotor to
rotate with the changing (alternating) magnetic fields of
the stator.
See page 7 of this PDF:
("some sort of 'fixed' sequence to send to the motor")
AN INTRODUCTION TO SENSORLESS BRUSHLESS DC MOTOR
DRIVE APPLICATIONS WITH THE ST72141
http://www.st.com/stonline/books/pdf/docs/7209.pdf
* * *
Read the documents below to understand the problem.
AVR444: Sensorless control of 3-phase brushless DC motors
http://www.atmel.com/dyn/resources/p...ts/doc8012.pdf
ATAVRMC100
http://www.atmel.com/dyn/resources/p...ts/doc7551.pdf
The ATAVRMC100 is an evaluation kit dedicated to brushless DC motor control, for
both Hall effect sensor control and sensorless control using Back ElectroMotive Force.
The kit includes an evaluation board, a 3-phase BLDC motor and a demonstration software.
It allows users to quickly evaluate the capability of the AVR® microcontroller
AT90PWM3 to control high speed brushless DC motor applications.
The kit can also serve as a development platform. Low cost AVR development tools
make debugging easier, and source codes, written in C, can be easily re-used by developers
for their own motor control applications.
* * *
Why do you need this motor?
What is the final application for this motor?
Best regards,
Luciano
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