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TMS320F28335: Slip estimator calculations

Ajay S
Expert 1280 points
Part Number: TMS320F28335

Tool/software:

Hi team,

do we need to convert all the quantities wr,ids,iqs,imds etc to per unit while doing theta calculation?

what modifications have to made if am using tms320f28335 floating point dsp processor....?

what range exactly theta will vary ? is o to 1 in per unit represents o to 2pi?

iq Wslip, We;

#define CUR_MOD_MACRO(v)                            \
    v.IMDs +=  _IQmpy(v.Kr,(v.IDs - v.IMDs));        \
    Wslip = _IQdiv(_IQmpy(v.Kt,v.IQs),v.IMDs);        \
    We = v.Wr + Wslip;                                \
    v.Theta +=  _IQmpy(v.K,We);                        \
                                                    \
    if (v.Theta > _IQ(1))                            \
       v.Theta -=  _IQ(1);                            \
    else if (v.Theta < _IQ(0))                        \
       v.Theta += _IQ(1);

Thanks, 

Sathish 

  • 0
    TI__Mastermind 23300 points

    Ajay,

    I have requested the correct SME to be assigned to answer your question.

    Yes, 0 to 1 in pu would represent 0 to 2pi.

    Thanks,

    Sira

  • 0
    TI__Expert 3900 points

    Hi Sathish,

    Ajay S said:
    do we need to convert all the quantities wr,ids,iqs,imds etc to per unit while doing theta calculation?

    Yes. You need to convert the variables to per-unit for calculation. 

    Ajay S said:
    what modifications have to made if am using tms320f28335 floating point dsp processor....?

    It seems you don't need to do any modifications.

    Ajay S said:
    what range exactly theta will vary ? is o to 1 in per unit represents o to 2pi?

    Yes. 0 to 1 in pu represents 0 to 2pi.

    Thanks,

    Jiaxin

  • 0 in reply to Jiaxin Teng
    Expert 1280 points

    Hi Jiaxin,           

    For estimating Rotor flux angle , θe= integral(ωr+ωsl)dt,

    where, θe=Rotor Flux angle, ωr=Motor speed, ωsl=Slip speed, dt=time of one switching cycle

    Considering, ωsl=(Rr/Lr)*(Iq_Ref/Id_Ref)

    where, Iq_Ref is obtained as PI Controller output limited to maximum value of Iq of the machine I use and Id_Ref as the reference value obtained via calculation.

    Will this method of approach yield good results?  

    Thanks,
    Sathish

  • +1 in reply to Ajay S
    TI__Expert 3900 points

    Hi Sathish,

    Yes. This is a common method for indirect FOC of induction motor.

    Thanks,

    Jiaxin