searching a brushless DC startup procedure

[endrophie]

Hello,

if you have a look to a modern brushless controller for radio
controlled flying models you can see

- that the motor has a very short startup time until the right moving
(about 100-200ms)

- that no initial alignment for a known position is done

- that a backward rotation only about 30 - 60 ms after starting is
recogniced and the motor is running in the right direction

- that because of the used 8 bit Microcontrollers there is no extrem
complex algorithm possible

- that the controller works probably in voltage controll

Does anywhere have information about the used startprocedure or a
webside/usegroup where mor information is available?

Best regards

Endrophie

 

endrophie wrote:

ste controller must work in sensorless mode. The problem is, that
when
you have a very slow rotation speer, the BEMF has a littly amplitude.
And if you a starting sequenze to the motor, it should rotate
reliable
in the right direction.

Six-stepping works reliably at low speed without feedback.
The six-step sequence dictates the direction of rotation.

So it must be possible to detect near zero
speed the direction and the rotor position (but without any
strategies
who need the current).

What else can you measure apart from voltage and current?
You would need to mount a sensor on the shaft.