[ARM] Sensorless bldc motor initial position detection

[Sudhakar R]

I am working on sensorless bldc motor contorl. the sensor bldc motor we can run the motor by 6 step commutation table since the rotor position is known. But the sensorless bldc motor is different and rotor position is unknown. By using back emf method we can able to run the sensorless bldc motor. my problem is at initial stage there is no back emf and how to define the rotor position.can any one help me to solve this initial position detection for sensorless bldc motor.

 

[KlausST]

Hi,

My idea: Just turn it slowly, timing controlled.

Klaus

 

[BradtheRad]

Per post #2 give power to the coils in sequence (slowly), as though the motor is already running.
Keep it unloaded so you can assume the motor spins freely.
As soon as your circuitry detects rotor position, make a transition electronically to let your circuitry take control of sending power to the coils.

 

[D.A.(Tony)Stewart]

"Texas Instruments offers two solutions as stated in their DRV10983 datasheet (page 17):

https://www.allaboutcircuits.com/electronic-components/datasheet/DRV10983PWPR-Texas-Instruments/

1. Use the DRV10983's initial position detect (IPD) feature to determine the rotor position "based on the deterministic inductance variation, which is often present in BLDC motors."
2. Or, use the align-and-go technique. With this method, a voltage is applied across one of the phases to force the rotor into a known alignment."

 

[Sudhakar R]

Thank you for replay it's very helpful for me.