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brushless DC motor using AVR MCU


Hello, :)

Has anyone have any idea about driving a three or four phase brushless DC motor that does NOT has hall sensors using an AVR microcontroller?

I got a three phase brushless DC motor that i scavenged from a Dead Hard Disk Drive and some MCUs like ATMEGA8 and 16

Anyone got any idea how to drive it using the back emf as feedback (I think that's the only way to drive a sensorless BLDC motor :-\)?

what I found is you need to measure the back emf from the coils to approximate the rotor position and then time your commutation (current supply),also you need to condition the feedback so that it won't blow up your MCU's ADC !But I don't know how to wire it all up  :o!

any help would be appreciated :)


Microchip has App Notes that cover the hardware details of sensor-less BLDC motor control.

Under "Select an Application" find "Motor control".

These are from Atmel

--- Quote ---AVR443: Sensor-based control of three phase BLDC motor based on tinyAVR and megaAVR devices
(file size: 88858, 8 pages, revision B, updated: 02/2006)
This application note describes the control of a BLDC motor with Hall effect position sensors. The implementation includes both direction and open loop speed control.

--- End quote ---

--- Quote ---AVR444: Sensorless control of 3-phase BLDC motors based on tinyAVR and megaAVR devices
(file size: 251559, 14 pages, revision A, updated: 10/2005)
This application note describes how to implement sensorless commutation control of a 3-phase brushless DC (BLDC) motor with the low cost ATmega48 microcontroller.

--- End quote ---


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