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TMS320F28027F: Best approach to zero-speed start under load (traction application)

Asif Ahmed
Expert 1570 points

Part Number: TMS320F28027F
Other Parts Discussed in Thread: MOTORWARE, DRV8301,

Hey Motorware/InstaSPIN team!

As you all probably know by now, I am designing custom hardware using TMS320F28027F and DRV8301. I have InstaSPIN working well on this board now :-)

This is for a traction application. I want to ensure that I optimize the system for zero-speed startup under load.

My question is - what is the optimal solution for starting under load? I have hall effect sensors on the motor, so those signals are available. I have migrated the code from lab11e of the HV kit to my project, and have 6-step commutation working. However, the transition between BLDC and FAST isn't the smoothest, and there is a jerk each time. Also, after being spoiled with FOC for so long now, the sound of trapezoidal commutation is just ugly :-)

Would using an angle estimation technique based on the hall sensor readings be better? That is, using the hall sensors to seed an angle into the estimator/ForceAngle, and not using 6-step commutation at all?

Any insight into this is appreciated - whether a response/advice to my question(s), or just another way of looking at this problem.

Best,

-asifjahmed

  • 0
    TI__Guru** 117230 points
    For lab11e, to run motor smoothly, you have to set a right duty cycle for six step mode switch to FOC, and set a right integration value for all PIs of FOC also. You are right, six step mode has communication vibration compare to FOC, so you can use Hall sensor to estimate motor speed to generate the angle of rotor, and then set the angle to FAST, this way can improve both startup and switch performance.
  • 0 in reply to Yanming Luo
    Expert 1570 points

    Thanks for your response, Yanming.

    What I'm really asking is more based on the Motorware team's collective experience thus far, for zero-start under load - is it generally more robust to use BLDC commutation with hall sensors and then transition to FAST/FOC? Or is it better to always use FOC, and seed the starting angle to ForceAngle using some estimated angle based on the hall effect sensors?

    -asifjahmed

  • 0 in reply to Asif Ahmed
    TI__Guru** 117230 points
    Using sensored FOC is more robust than sensorless with full load if the motor had hall sensor. ForceAngle and exact can improve startup performance for sensorless. You don't need to use force angle if you want to control motor startup base on hall sensor.
  • 0 in reply to Yanming Luo
    Expert 1570 points

    Thanks, Yanming. Any examples or high-level guidance on how to go about seeding a starting angle into FAST for this method? How to determine an angle estimate from the hall sensors (possibly using code from 11e) and then how to seed that angle estimate into FAST?

    Thanks!

    -asifjahmed