No, you need to know the stator pole alignment relative to the encoder if you want to use the quadrature encoder for commutating the motor or else it will lock-up. I'm not talking about using the encoder for servoing for the shaft position. I'm talking about actually commutating the windings to spin the motor.ill be using a fairly decent optical encoder along with back emf for startup calibration, im not too concerned about pole allignment. the hard part will be writing code to control it in a closed loop, since apparently ill be starting from scratch as nobody has ever built a servo before it seems.
thanks for that list
That's my understanding as well, but it tends to have been adopted for simple motors that require external electronics.May I ask what kind of motor we're discussing here? To me, a "brushless DC" (BLDC) motor has always meant an AC motor (of some sort) with integrated electronics to make it behave like a DC motor. This is, you apply volts and it spins - as in the 12V computer fans we are all familiar with.
With Electronically commutated motors such as BLDC and AC versions, the motors are virtually identical, the difference is in the commutation, BLDC (brushless DC) because only two of the three windings are energized at any one time, similar to a DC motor turned inside out, hence BLDC.That's my understanding as well, but it tends to have been adopted for simple motors that require external electronics.
No, a stepper is something else. More like a PM synchronous motor.Thanks for the clarification Mr Jenkins. So we're talking about a permanent magnet three-phase motor, rather than a three phase induction motor such as would be used for fixed-speed or variable-speed-but-not-including-stopped operation. Because, I imagine, you can't run an induction motor down to 0 frequency.
So would it be correct to say that this kind of BLDC motor could also be described as a three-pole permanent-magnet stepper motor? Presumably they're driven with a PWM synthesised sine wave, which seems like a similar technique to micro-stepping a stepper motor. Is that correct?