Comment by zwieback
In my mind the main difference is steppers always taking full current, that's why we tend to switch to traditional servos past a certain size or use hybrid steppers like the MDrive
In my mind the main difference is steppers always taking full current, that's why we tend to switch to traditional servos past a certain size or use hybrid steppers like the MDrive
I used to think this but you can actually drive steppers with FOC (if they have appropriate feedback) and modulate the current based on required torque. It’s open-loop steppers that don’t do this.
You can do this but it's very difficult; the high pole count means it requires extremely precise and high-speed feedback to get good torque control on a stepper motor.
Yeah ain’t that the truth. This is a problem I’ve been fighting at work lately with a trinamic based system. Trinamic should be good but I see it’s touchy to properly phase align a stepper.
If you're micro-stepping a stepper then you're applying different currents to the coils. You can also microstep/openloop a BLDC just like a stepper and you can run a stepper with a closed loop controller just like it's bigger BLDC cousin.
Steppers had a niche in situations where you want to take discrete/accurate steps with very little control circuitry, e.g. printers, disk drivers etc. they're much simpler to work with vs. a closed loop bldc system, require no tuning, less software, etc.