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DRV10975 Braking

Niklas Hagman
Prodigy 110 points
Other Parts Discussed in Thread: DRV10975, DRV10983

Hi Texas Instruments,

I’m using the DRV10975 in an application where I have programmed the EEPROM with the spin-up profile for my BLDC. Start and stop of the BLDC is done by controlling the supply voltage for the device. The set-up works great except from one operating mode, which is when the chip is trying to start the BLDC when it is freewheeling at very low speed.  The motor I ‘am using have an extremely low voltage constant 6.58mV/Hz, I’m assuming the BEMF is too low at these speeds to detect the position of the rotor.

My question is: can the breaking command be used without using reverse drive to assure the motor brake to a stand still for low speed (before the rotor position can be estimated with BEMF)?  Or is the solution to increase the AlighnTime to brake the motor to a standstill if the rotor is not detected?

 

Regards,

Niklas

  • 0
    TI__Guru** 114905 points
    Hi Niklas,

    Our experts have been notified and should reply soon.
  • 0 in reply to Rick Duncan
    TI__Expert 3010 points

    Hi Niklas,

    DRV10983 enters Braking or Reverse drive state when direction of motor spin is changed. Reverse drive can be disabled by unchecking ‘Enable Reverse Drive’ option on GUI or by resetting bit ‘RvsDrEn’ in SysOpt1 register. Braking is applied for time ‘Brake Done Threshold’ when speed drops below ‘Reverse Drive/Brake Threshold’

    If motor is restarting in same direction, then Initial speed detect option can be used to reduce startup time. It can be enabled by checking ‘Enable Initial Speed Detect’ box in GUI or by setting ‘ISDEN’ bit in SysOpt 1 register

    Regards,

    Krushal