SparkFun Forums

[free-bee]

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:
1. The speed of the motor depends on the voltage applied to the leads.
2. 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.

[Jman]

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.

[DanV]

Look at this link for more information:
http://ww1.microchip.com/downloads/en/a ... 00857a.pdf
That link walks a person through using a PIC to control that type motor. Could be adaptable to Arduino.

And, additionally, googling something like "bldc motor control " will reveal a wealth of information on the subject.
Learn to use Google!

[free-bee]

I managed to find the PDF: http://cache.freescale.com/files/product/doc/AN1916.pdf

2.1.4 Speed Control
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.