I added an option to the Smart BLDC Commutator in the Makeatronics Store. You can now order a fully assembled board! Hopefully this will be useful to those of you who would like a BLDC driver but don't want to get dirty with SMD soldering.
More surface mount assemblies will be in the store in the coming weeks, so keep checking back.
Hello,
ReplyDeleteI was searching on the web to see if someone had the idea of using bldc motors to make a 3d printer and I found your blog. It's a really intersting idea, I hope your are still working on it.
I saw that you want to do position control using hall sensors to commute the motor.
This won't allow you much precision on the position.
However you can use magnetic encoders, it works by measuring the angle of a magnet put on the shaft of the motor so you don't need to have direct contact. They are cheap and pretty accurate : http://www.sensimatech.com/products/magalpha-ma300/.
Then there is a algorithm called field oriented control that allows to control precisely the torque of the bldc, either using a sensor for position control (close to 0 speed) or sensorless for high speed control (used for propellers for example).
The difficult part is to make the software and tune it for your motor. But there exist board for doing this and help for the tuning.
Hope this gives you insights :)
Yes, with hall sensors you will never get finer control than the angular offset of the rotor magnets. But if attached to a speed reducer/torque multiplier (i.e. lead screw) the resolution gets multiplied by the gear ratio.
DeleteThere are breakouts on the board for a quadrature encoder. But controlling position to higher resolution would require lots more control logic, splitting the current between two phases to hold the rotor in a "in-between" position. This board doesn't have the wiring to support that since it would require independent PWM of each phase coil (currently one PWM drives all coils).
Yes, with hall sensors you will never get finer control than the angular offset of the rotor magnets. But if attached to a speed reducer/torque multiplier (i.e. lead screw) the resolution gets multiplied by the gear ratio.
DeleteThere are breakouts on the board for a quadrature encoder. But controlling position to higher resolution would require lots more control logic, splitting the current between two phases to hold the rotor in a "in-between" position. This board doesn't have the wiring to support that since it would require independent PWM of each phase coil (currently one PWM drives all coils).