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DRV10987EVM: Motor output power is not sufficient

Daniel Johns
Prodigy 30 points
Part Number: DRV10987EVM
Other Parts Discussed in Thread: DRV10987

I am using the above evaluation module to drive a motor which has a rated power of 46W @ 24V supply. However, the torque the motor provide at max speed (or any speed) is not enough and does not seem to agree with motor specs. For example at the full speed, it draws only around 200mA average current with 24V supply. This is around 5W. The configuration used is as below (this is generated by the TI software). I like to know what kind of issue can cause this.

DRV10987 0x90 0xC1BA
DRV10987 0x91 0x4949
DRV10987 0x92 0x1
DRV10987 0x93 0x52
DRV10987 0x94 0x3BFF
DRV10987 0x95 0x3030
DRV10987 0x96 0x7A

  • 0
    TI__Mastermind 23062 points

    Hi Daniel,

    What is the motor speed at this torque? Is it reaching to the rated speed? Is you motor running on load or no load?

    Also, I am not sure of inertia of your motor, the acceleration configuration looks very high.

    Can you share the R, KE, Rated speed details?

    Thanks and Best Regards,

    Venkatadri S

  • 0 in reply to Venkatadri Shantaram84961
    TI__Mastermind 23062 points

    Hi Daniel,

    Any update on this? Is you motor is on load or no load? I am guessing motor condition could be without load, example if Fan without blade it may need little bit of torque to speed it to maximum. Please let me know.

    Thanks and Best Regards,

    Venkatadri S

  • 0 in reply to Venkatadri Shantaram84961
    Prodigy 30 points

    Apologies for the delay.

    You were exactly right about loading. I completely forgot that the motor was free running when drawing this current. When it is loaded, it pulls 2A before locks. This gives 48W power so it is working at its full rated power.

    I also adjusted various params, so it gives very fast start up speeds. 

    One issue I am still facing though is its torque seem to be very low at say 10% of its speed. Which params should I tune in order increase the torque at low speeds?

    Thanks

    Dan

  • 0 in reply to Daniel Johns
    TI__Mastermind 23062 points

    Hi Daniel,

    Do you have any reference what is expected torque at 10% speed? Motor speed torque characteristics generally nonlinear in case of fan load (Please confirm if it is fan load)

    In order to improve the torque, we have to adjust the lead angle (advance angle) parameters and make sure Kt, Rm are programmed properly.

    Thanks and Best Regards,

    Venkatadri S