Building ESC for Sensorless Brushless DC motor

[allahjane]

Hi there,

I got this Brush less DC motor out of an dead HDD ..after making certain measurements and experiments,I found out that it is Sensorless Three phase motor with a ground connection at center i.e the coils are arranged in Star Formation!

I read about this type of motors and found out that since its sensor less it needs to detect the back emf on each coil to track rotor location and change supply phase appropriately. I tried to run it using atmega16 with L293D driver, shifting phase at regular intervals through 3 of 4 half bridges but none worked! There's lot of vibration and very low efficiency.

Can anyone please explain me how do i use the atmega 16 to run the motor? how do i get the back emf feedback to the atmega?

[waltr]

Microchip has a few App Notes that explain how to drive these BLDC motors.
Well worth reading no matter which processor you are using.

http://www.microchip.com/wwwcategory/TaxonomySearch.aspx?show=Application%20Notes&ShowField=no