Hello.
Which way is used to control speed of brushless DC motor that doesn't have any sensor to find position of rotor.
Very thanks.
You mean "what methods allow commutation of a sensorless BLDC?"
Back EMF sensing is the main and simplest way - you use trapezoidal drive waveform and sense
the voltage on the idle phase to determine rotor angle. The method can only work if the motor
is spinning (fast enough) so there is a back EMF signal.
Speed control is a separate issue, usually done by controlling PWM to the output stages.
Nominal speed of motor is 1200 rpm and I want to control it between 100 until 1200 rpm.
The method can only work if the motor
is spinning (fast enough) so there is a back EMF signal.
So, Is that O.K with this speed.
Very thanks.
How would we know? Maybe? We know almost nothing about this motor.
I mean, what is the minimum speed of motor that can detected by the EMF Sensing method.
It depends on what?My motor nominal speed is 1200 rpm and I want to control it between 100 till 1200 rpm.
How can I understand that the EMF Sensing method is good.
Thanks.
It depends on the voltage levels involved, the amount of switching noise, the quality of the
sense circuitry, how the voltage is filtered and sampled...
You have an oscilloscope?