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BLDC dq transform

DIJO PAULSON
Intellectual 710 points


Hi,

I am trying to run FOC algorithm on a bldc motor which has a back-emf profile similar to a trapezoid. 

My aim is to reduce torque ripples in the bldc motor using FOC algorithm.

I refered to some IEEE papers where dq model of bldc motor is developed and then torque ripples are eliminated with some current harmonics injection method.

I need to know the practical aspects of this method. 

Please reply as soon as possible.

Regards,

Dijo Paulson

  • 0
    TI__Mastermind 27240 points

    Hi,

    FOC is meant for sinusoidally distributed magnetic field and back emf. If you want to apply it to a trapezoidal bemf machine,the torque will have ripples at 6 times fundamental. In FOC control structure, the current loop generates d and q axis voltages which after inverse park will generate sinusoidal line to line voltages.

    I would assume, to implement your thoughts, you need to generate individual phase current references with harmonic injection and then have a hysteresis based current loop.

    We don't have any example that matches your description or with my thoughts expressed above. Wish you all the best.

    rgds,

    ramesh