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Designing a custom IGBT driver requirements

Jeff Lenk
Intellectual 310 points

We are driving a 68HP 480V ACIM and are looking to use Instaspin Motion. This application requires an encoder for precise control of position and we are planning on using LEM current sensors on two of the phases and dc bus voltage monitoring. The question is if we are using an encoder do we still need to design for having voltage monitoring of the phase voltages? I understand that FAST requires the voltage sensors for sensorless operation but if we are using an encoder are they still needed?

  • 0
    TI__Guru** 119680 points

    Jeff,

    Cool. That's a big motor!

    As you noted the phase voltage measurements and filter are only required for FAST.  If you don't use FAST you don't  get Motor ID, automatic current tuning (although if you know your R & L you simply follow our calculations), nor Rs online (don't care if you aren't using FAST), or Rs Recal.

    Rs Recal is currently used in the position control projects as an initial alignment feature. But you can do this yourself without the feature, just add enough +Id at start-up to align to the closest orthogonal vector and zero out your encoder. 

    Good luck! 

  • 0 in reply to ChrisClearman
    Intellectual 310 points

    Thanks much for that answer I think we will go ahead a design for the additional sensors because we like that functionality!