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TMS320F280041C: stopping time

Viktorija Cecil
Mastermind 18501 points

Part Number: TMS320F280041C

Team,

My customer is working on TMS320F280041C motor control design. He would like to know how to improve stopping time in software, under load conditions. 

Once motorVars.flagRunIdentAndOnLine = 0; measured stopping time is 10s, customer needs to reach 3s or less. 

Thanks

Viktorija

  • 0
    TI__Guru** 117140 points

    The stopping time depends on the inertia and friction of the motor/system. You have to add a braking function if you want to shorten the time.

    The simple way is to turn on all three bottom switches, in which case the energy is dissipated as heat within the motor heating it up.

  • 0 in reply to Yanming Luo
    TI__Mastermind 18501 points

    Yanming, 

    Shorting the motor is last resort. They attempted it while on power supply, and after motorVars.flagRunIdentAndOnLine was set to zero in the Expressions window their motor stopped very quickly (<1sec), power supply went to 10A current limit, all FETs on the board got shorted... Did it have anything to do with being on a PS instead of a battery? Should they always use a battery as power source when testing stopping time?

    How can customer add regenerative braking function?  Code snippets would be helpful.

    Thanks

    Viktorija

  • 0 in reply to Viktorija Cecil
    TI__Guru** 117140 points

    They might try to turn on all three bottom switches and turn off all three high switches, in which case the energy is dissipated as heat within the motor heating it up. A separate Dc voltage monitor and dissipation of excess energy in a resistor may be one way to dissipate the energy, utilize the brake resistor to suppress the DC-Link voltage and current.

    To implement a regenerative braking function that needs an additional convert circuit to feedback the energy from the motor to the power supply. We don't have any example code from the motor control side. I would recommend some engineering textbooks to look at that should have a more detailed implementation method.