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PMSM torque control through zero speed with InstaSPIN-FOC + quadrature feedback

Erik Norgren
Prodigy 40 points
Other Parts Discussed in Thread: LAUNCHXL-F28069M, BOOSTXL-DRV8305EVM, DRV8305, CONTROLSUITE

I would like to drive a PMSM in torque control mode at and around zero speed. It looks like most solutions are geared towards sensorless control, but I need encoder feedback for the purpose of commutation at zero speed. What are my best options for zero speed torque control? Does InstaSPIN-FOC support encoder (quadrature) feedback for the purpose of overcoming its zero speed limitation? I don't see it documented, but maybe someone has done this? Or is InstaSPIN-MOTION the only option?

Regarding the InstaSPIN-MOTION eval kits, I see LAUNCHXL-F28069M + BOOSTXL-DRV8301EVM is supported, but I need the extra current capability of BOOSTXL-DRV8305EVM. Is LAUNCHXL-F28069M + BOOSTXL-DRV8305EVM supported by InstaSPIN-MOTION?

Thanks in advance,

Erik

  • 0
    TI__Mastermind 26065 points

    Hi Erik,

    We will move your post to instaSPIN forum for better answer. 

    For the current ability, my suggestion is to make basic tests with a light load condition using DRV8305 boostpack (strictly limit the current level) and meanwhile make a customed dock pack board yourself with higher current level MOSFETs and layout.

    Best regards,

  • 0 in reply to Wilson Zuo
    Prodigy 40 points
    Wilson,

    Thanks for directing me to the proper forum. The current capability of BOOSTXL-DRV8305EVM is perfect for our testing. Is BOOSTXL-DRV8305EVM compatible with LAUNCHXL-F28069M and InstaSPIN-MOTION libraries? I only see references to the 8301 part.

    Thanks,

    Erik
  • 0 in reply to Erik Norgren
    TI__Guru** 119560 points
    "LAUNCHXL-F28069M + BOOSTXL-DRV8305EVM supported by InstaSPIN-MOTION?"
    Yes.

    "What are my best options for zero speed torque control? Does InstaSPIN-FOC support encoder (quadrature) feedback for the purpose of overcoming its zero speed limitation? I don't see it documented, but maybe someone has done this? Or is InstaSPIN-MOTION the only option?"

    You would need to use InstaSPIN-MOTION. It would be based on proj_lab12 which uses the encoder for feedback in a speed control loop. What you would do is disable the speed controller and just provide an IqRef like is done in proj_lab05a.

    At that time you wouldn't be taking advantage of really any of the features of IS-FOC or IS-MOTION but it would work. Several other people on this forum have done the same. The other option would be to use the controlSUITE framework, but the project for that is based on the High Voltage Kit: C:\ti\controlSUITE\development_kits\HVMotorCtrl+PfcKit_v2.1\HVPM_Sensored
  • 0 in reply to ChrisClearman
    Prodigy 40 points
    In this case, is FOC disabled? Or does it switch between sensored control and FOC? I am using a magnetic encoder and I'm concerned with sensor latency at higher speeds. FOC should perform better as speeds increase.

    If I wanted to use controlSUITE, is LAUNCHXL-F28377S + BOOSTXL_DRV8305 a documented option?
  • 0 in reply to Erik Norgren
    TI__Guru** 119560 points
    FOC is the control scheme. It means you are Controlling a stator Field Oriented perpendicular to the rotor field. Id controls the orientation and Iq controls the torque magnitude.

    The orientation is determined by the rotor flux angle, either through estimation (FAST observer) or by mechanical sensor (encoder which has been aligned to the rotor field).

    Yes, for torque or velocity control FAST will actually outperform an encoder at all operating points besides the first few Hz and zero speed. So, you could actually start with the encoder and then switch to FAST at some speed (and back to encoder at a low speed). After working through the labs and understanding the software you should be able to figure this out.

    "If I wanted to use controlSUITE, is LAUNCHXL-F28377S + BOOSTXL_DRV8305 a documented option?"

    F28377S does not have InstaSPIN-MOTION support but it DOES have a Servo encoder example project. So yes, you could do encoder torque control with this solution, but it would be more challenging to switch into sensorless mode because you would need to get sensorless running with eSMO (instead of FAST and the IS-FOC control system).
    C:\ti\controlSUITE\development_kits\TIDM-SERVO-LAUNCHXS
  • 0 in reply to ChrisClearman
    Prodigy 40 points
    Thanks for your help Chris,

    I agree, this will probably become very clear once I start testing. I just want to make sure I'm starting down the right path.

    Erik