On Sat, 24 Apr 2010, Andy Pugh wrote: > As a supplementary question for the distant future: If you are driving > such a motor with three-phase PWM at a software-calculated phase angle > then am I right to assume that you wouldn't use the current encoder > angle as the PWM phase angle, as then all you do it hold the motor in > its current position, but would instead add or subtract a "lead > angle"? I can imagine trying to do that in HAL and having the encoder > angle wrap correctly being fun in HAL.
Yes the encoder position is the rotor position(after the right startup and mod math), if you drive by rotating this vector, you will end up with a low res 3 phase stepmotor which is not what you want. For simple voltage mode sinusoidal 3 phase drive, What you do is take this reference, and offset the three phase PWM angle +90 or -90 degrees from the reference angle depending on which way you wish to drive(and use the PID to control the PWM magnitude). > > I see that there are Clarke transform components in HAL, but I am > unclear how you would use them for this so assume they are for > something else? Clark is for FOC, not much use unless you are measuring stator currents... inverse Park+inverse Clark might be usable for simple voltage mode control but its kind of the long way around... > > -- > atp > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
