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InstaSpin Autotune Ld / Lq measurement

Joachim Rodler75
Prodigy 40 points


Good Morning,

the autotune in InstaSpin is a very great thing for adapting new motors, but I'm wondering why the measurement results of Ld and Lq are always equal ?

Kind regards

 

  • 0
    TI__Guru** 119670 points

    The ID feature only identifies a single inductance, meaning no saliency, which is effectively true for mist synchronous machines. IF you have a salient motor you can put the two inductances in user.h (or more common is to apply an OnLine loading of values during different operating points). We are not yet able to identify salient inductance yet, and anyways inductance vary over load/current and frequency so there really isn't a static "true" value. 

  • 0 in reply to ChrisClearman
    Prodigy 40 points

    Thanks for the fast response !

    I think that the usual Ld<Lq does not just depend on saliency, more on geomertically effects (e.g. burried magnets).

    So the measured inductance after InstaSpin's autotune represents the average of one phase inductance during a full elektrical rotation, isn't it ?

  • 0 in reply to Joachim Rodler75
    TI__Guru** 119670 points

    Yes, saliency is mostly influenced by placement of rotor magnets. 

    In spruhj1 6.5.7.3 we say it is an average inductance, but in my experience with salient motors what we identify is essentially just the Ls_d.