A while back, I posted about wanting to make a controller board for a three-phase BLDC motor with Arduino. But then I read a paper stating two things:
The speed of the motor depends on the voltage applied to the leads.
The torque of the motor depends on the current through the stator coils.
So I had an idea. What if instead of an Arduino reading the hall sensors and operating the H-Bridge, I just build a circuit using only logic gates to read the sensors and operate the H-Bridge? I could then use an external voltage/current driver to control the speed/torque of the motor.
The sensors wont provide feedback until you start the motor. You need an initialization step.
Review motor controls, such as soft starters. With 3 phase AC motors you can control them via voltage or current. Voltage being VFDs and current being Softstarters. They typically provide a initialization step such as a start and they use CTs or HAL sensors to provide feedback for regulation.
Unfortunately, I am a beginner so I would have to look at PWM works on the Beagle board. I would guess that feature is what I would start with.
Commutation ensures proper rotor rotation of the BLDC motor, while the motor speed depends only on the
amplitude of the applied voltage.
I figured that if I could build a commutation circuit of only logic gates, it should be a lot cheaper than a microcontroller, mostly because I already a big collection thereof. The only limitation would be that the motor can only spin in one direction, which really isn’t an issue in my application.
I was also aiming for a design that uses one single power rail. I do know I have a power supply that I can readily use for this.