[ARM] BLDC Sensorless startup method

[surendran_raj]

For a sensored bldc motor we can run the motor by 6 step commutation table since the rotor position is known. But for sensorless bldc motor is different that rotor position is unknown. By using back emf method we can able to run the sensorless bldc motor. my doubt is at initial state there is no back emf to define the rotor position.can any one help me to solve this initial startup condition for sensorless bldc motor.

 

[Easy peasy]

you need to apply a short pulse to two phases and then observe back emf ....

--- Updated Dec 27, 2022 ---

you can then tell if the initial pulse was in the correct direction or not, and then work out the next commutation pulse ....

 

[surendran_raj]

you need to apply a short pulse to two phases and then observe back emf ....

--- Updated Dec 27, 2022 ---

you can then tell if the initial pulse was in the correct direction or not, and then work out the next commutation pulse ....

Thanks
I use this circuit to measure the back emf is the circuit use is enough or do you have another method to for back emf