He does a fairly lengthy discussion of this in the video and describes quite precisely why a FOC is the best option in this application.

Do you have any meaningful input on this, or do you just want to continue talking about other hypothetical scenarios where FOC might not be the best option?

it was nat that part of the comment I was refering to

On the point of torque and power, because the PMAC/BLDC motor is coarser than a stepper motor, it’s going to be a faster motor. For applications where you want direct drive, this is like trying to launch your car in third gear. It can be done, but the performance will suffer until you get up to speed.

For things like 3D printers where you’re constantly slowing down and accelerating from a stop, you will actually spend most of your time going relatively slowly. You’re not extruding at a million miles per hour, and when you are moving rapidly you’re not extruding and not demanding high precision, so the apparent dynamic performance of a BLDC motor is mismatched.

If you gear it down, you face the problem of inertia, because the energy stored in the rotor is proportional to the square of its RPM, so starting and stopping the motor consumes most of your torque.

Not at all. The speed and positioning under FOC depends on the error signal derived from the measured motor state, which means you have to accept some error band around the desired path for the control scheme to operate.

This is analogous to the way a stepper motor deviates from the desired position under load, except with a stepper motor you don’t have to compute anything and it’s already built for good precision without active feedback. If the motor is sized incorrectly and cannot perform the required motion with acceptable error, then you can’t help it with FOC because the motor is still too weak or your demands are unrealistic.

The FOC PMAC motor looks good in demos, but you can’t see with the naked eye whether the performance is really superior. What’s likely, you’re spending months of engineering and fine tuning just to arrive at the same point that you’d have with a simple stepper motor. All at the cost of much more complicated control hardware, more software and code, and more things to troubleshoot with the encoders and sensors.

The main deciding question is rather, whether the characteristic torque and power curve of the stepper motor vs. the coarser PMAC motor is better or worse for the application. One control method in itself is not clearly better. Doing FOC for the sake of doing FOC is not a good idea, but nerds are going to nerd about it anyways because it’s complicated and cool.

You confure tree phases motor with stepper motor…

what a dumb comment