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Field oriented control in a BLDC motor with trapezoidal shaped back emf

DIJO PAULSON
Intellectual 710 points
Other Parts Discussed in Thread: TMDSCNCD28069MISO, TMDSHVMTRINSPIN, MOTORWARE

Hello there,

I am doing a project on BLDC motor to use it as a traction motor in a hybrid electric vehicle. The motor which I am using is having a trapezoidal shaped back emf.I read from many articles and journals that field oriented control is not appropriate for a trapezoidal BLDC motor. I want to know the practical aspects of this type ofcontrol. Also please suggest whether Vector control can bring a significant torque ripple reduction in this motor.

Dijo Paulson

  • 0
    TI__Guru** 114905 points
    Hi Dijo,

    Our expert has been contacted. He should reply soon.
  • 0 in reply to Rick Duncan
    Intellectual 710 points
    Thank you Rick,

    I am using TMDSHVMTRPFCKIT and BLWS235D 160V, 3000 RPM BLDC motor. Is Vector control possible with this motor ? Please reply as soon as possible.

    Dijo Paulson
  • 0
    TI__Guru** 118010 points

    FOC can certainly be applied to a trapezoidal Bemf motor. However, you won't quite be maximizing the torque production capability of the motor. There are other benefits to FOC though.  Most applications that are using a trapezoidal motor do so to achieve highest start-up torque, so some of these customers are using a 6-step commutation approach to start the machine, and then transition into FOC for higher speeds (when peak torque production isn't necessary) where they prefer better dynamic response and lowered torque ripple.

    Yes, you can try FOC on the motor you have.

    Also recommend InstaSPIN-FOC for experimentation.  You can use the same EVM you have, just add TMDSCNCD28069MISO as the controlCARD and you will have the same set-up as TMDSHVMTRINSPIN EVM.

  • 0 in reply to ChrisClearman
    Prodigy 115 points

    Hi Chris,

    We are working on a similar project with 48V 3KW BLDC motor with trapezoidal B-EMF. Given we have option to apply both 6 step trapezoidal commutation and FOC with TI's motor control solutions, our primary concern is to achieve high efficiency for the motor we have by wisely choosing one of the two available commutation strategies.

    Can please help us with the pros and cons of using trapezoidal and FOC with our BLDC motor and guide us in choosing appropriate one for achieving higher efficiency.

    Will using FOC with our BLDC motor reduce torque ripples at the cost of efficiency? 

    I hope for a quick reply 

  • 0 in reply to Manuj Agrawal
    TI__Guru** 109960 points
    FOC has a better torque control than trapezoidal control, and FOC can be easily implement on trapezoidal BEMF BLDC. For instaSPIN-FOC based F28027F, you can refer to the guide in motorware which can be downloaded from TI web.

    The similar post as below.
    e2e.ti.com/.../2284540