80% chance I'll just be running this open-loop, always following a sine for the 3 phase. Like microstepping does for a stepper for 2 phases. It will work, I just need to generate the 3 channels of PWM 120 degrees apart, and tie that to an axis.
This is the minimal implementation assuming your axis can handle full current stalled and not overheat. A proper implementation would be also PWMing one ore more enable lines, or scaling all three phases, or reading a sensor and balancing current, with the end goal being some kind of adaptive field oriented control. Those could happen, but I think I'll be fine with just open-loop as my application is a direct drive PNP part rotator. AKA... basically zero load beyond rotor inertia, and comparatively slow speeds. I could built it up with the other stuff, but I'm inherently lazy (usually an asset for a programmer actually) and looking for a canned solution before I do so. Or I could just add it to the bldc component I suppose. On Saturday, April 27, 2019 at 5:06:36 PM UTC-4, justin White wrote: > > I run a brushless spindle motor with the BLDC component and a Mesa 8i20. > The waveform depends on the personality selected and usually only starts in > trapezoidal mode if using hall sensors then switches to sinusoidal. I can't > much of the gritty details of setting it up and waveform wasn't a huge > thing when I configured my mill. I had more of a fun time getting the PID > setup than anything, but that's mostly due to the fact that the 8i20 is a > torque mode drive rather than a velocity mode drive. I haven't touched the > config in a while as my mill just runs now. > > I'm not sure what "resembling microstepping" means for a brushless DC > motor. Alot of the BLDC component relies on the feedback. It's best for > running servo's where the drive itself can be dumb and the Linuxcnc > hardware/software can handle commutation based on feedback. There's a few > modes which can run without feedback but the usefullness depends on what > you're doing. > > On Saturday, April 27, 2019 at 4:03:59 PM UTC-4, [email protected] > wrote: >> >> Got a project where I will be doing pwm of the three phases of a bldc >> motor implementing sinesoudial drive for something resembling micro >> stepping. >> I saw the bldc component but it looks to be a trapezoidal implementation. >> Anyone whipped this up before I do? Basically 3 pwm lines following a >> sine wave 120 degrees apart. >> >> Thank you. >> > -- website: http://www.machinekit.io blog: http://blog.machinekit.io github: https://github.com/machinekit --- You received this message because you are subscribed to the Google Groups "Machinekit" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. Visit this group at https://groups.google.com/group/machinekit. For more options, visit https://groups.google.com/d/optout.
