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DRV10987: Motor Startup Problem

Nishanth M32
Intellectual 295 points
Part Number: DRV10987

Hi,

Sometimes DRV is not starting to drive the motor. During that time, if i try to rotate the motor shaft manually means, it is starts to run otherwise DRV is not at all trying to drive the motor without slight manual push. Once it starts there will be no issues at all until motor input PWM stops. If I try to read the Status register data during that time it gives vale 0x00. Speed pin is also 25KHZ/80Duty Cycle. Why this problem is happening is that any layout issues or Schematic values?

Help me out of this problem… 

i2c_writen(0x90,0x00,0x3E);  

i2c_writen(0x91,0x5E,0x3A);

i2c_writen(0x92,0x1C,0xDC);

i2c_writen(0x93,0x43,0x87);  

i2c_writen(0x94,0x3F,0xAF); 

i2c_writen(0x95,0xA1,0x77); 

i2c_writen(0x96,0x2B,0x69);

Regards,

Nishanth M

  • 0
    TI__Mastermind 24405 points

    Hi Nishanth,

    Thanks for posting your question in MD forum. I don't see anything out of the ordinary in the schematic. is Vdd 3.3V? Are you able to read back register values from the device? Can you try increasing the open loop and align current? I'm guessing the device is not providing sufficient current during motor startup. 

    Regards,

    Vishnu.

  • 0 in reply to Vishnu Balaraj
    Intellectual 295 points

    Hi Vishnu,

    Thanks for the reply....

    is Vdd 3.3V  --> 5V (VREG & VDD is shorted through Jumper)

    Are you able to read back register values from the device? --> YES

    open loop and align current --> Its already maximum value of OPEN LOOP 1.6A & Align Current 1.2A 

    I'm guessing the device is not providing sufficient current during motor startup.  --> Power Supply which is fed to 26V/2.4A

    The problem is only at startup, once its starts there will be no problem, when i try to give the load in the motor Power source is able to give up to 2.4A and DRV also driving very fine.

    At initial very Slight touch in the motor shaft its starts running....Why the problem is happening...? Help me t solve this. 

    Regards,

    Nishanth M

  • 0 in reply to Nishanth M32
    TI__Mastermind 24405 points

    Hi Nishanth,

    Can you read the fault register (address 0x00) and see which fault is getting triggered? Also, can you share the below details?

    1. Motor phase to phase resistance

    2. Motor Back EMF constant 

    3. Motor startup current

    4. Motor nominal current.

    5. Motor maximum speed

    6. Number of pole pairs

    Regards,

    Vishnu.

  • 0 in reply to Vishnu Balaraj
    Intellectual 295 points

    Hi,

    Thanks for the reply...

    Can you read the fault register (address 0x00) and see which fault is getting triggered? --> Fault Register data : 0x00

    Also, can you share the below details?

    1. Motor phase to phase resistance  1.0864E:

    2. Motor Back EMF constant :412.16

    3. Motor startup current: 1.6A

    4. Motor nominal current.: Max: 1.2A with Load

    5. Motor maximum speed: 380RPM

    6. Number of pole pairs : 18 Poles

    Kind Regards,

    Nishanth M

  • 0 in reply to Nishanth M32
    TI__Mastermind 24405 points

    Hi Nishanth,

    Can you try the following recommendations? 

    1. Disable IPD and try Align and go. Align and go startup method is more reliable and needs no tuning.

    2. Program the phase to center tap resistance to 0.5432 ohms.

    3. Reduce the first order acceleration constant A1 and second order A2 to lower value say 0.9 Hz/s and 1.6 Hz/s^2.

    4. Set align time to 1.3 sec or 2.7 sec.

    Is the unit of Kt in mV/Hz?

    Regards,

    Vishnu.