MCT8316Z: MCT unable to drive motor sometimes

Jayam Srivastava

Part Number: MCT8316Z

Hi there,

I have been working on a system which has multiple Motors and they communicate via CAN protocol and MCT8316 (SPI version) is used for driving the motor. The system is working fine but the MCT is sometimes unable to drive the motor (around 1 in a 100 to say in an abstract manner), when I checked, it was not the problem with communication, as it is getting the command which it needs to start the motor. But during continuous testing; MCT misses to start the motor 1 in 100 times approx; while it works fine almost all the rest of time it also doesn't give any specific error on n-fault pin at that point in time.

FYI; We are using constant acceleration and deceleration of 500 and 255 respectively to achieve an RPM of 360.

What could be the reason for this?

Thank you.

Jayam Srivastava

over 2 years ago

0 Aaron Barrera over 2 years ago

TI__Mastermind 26046 points

Hi Jayam,

What is your startup sequence of the motor? Do you apply the PWM signal continuously and use BRAKE or DRVOFF to start/stop the motor, or do you go from 0% duty cycle on PWM to a higher duty cycle with a fixed acceleration?

Is MTR_LOCK_MODE set to mode that reports nFAULT going low?

Thanks,
Aaron

0 Jayam Srivastava over 2 years ago in reply to Aaron Barrera

Prodigy 90 points

Hi there,

We use variable percentage PWM duty cycle to go from 0 to desired with a fixed acceleration and deceleration. the motor lock mode is set to report fault on nFault pin but it dosen't report any fault while this happens.

0 Andrew Liu over 2 years ago in reply to Jayam Srivastava

TI__Mastermind 18916 points

Hi Jayam,

Some of our team members are currently out for travel

But we will review your questions and aim to provide a response soon

Best Regards,
Andrew

0 Jayam Srivastava over 2 years ago in reply to Andrew Liu

Prodigy 90 points

No problem,

Please respond whenever the team is available, we will follow up then.

Thank you.

Jayam

0 Andrew Liu over 2 years ago in reply to Jayam Srivastava

TI__Mastermind 18916 points

Hi Jayam,

Some other questions from our side to evaluate the system:

does your start-up sequence, is your system power-cycling the device between each attempt?
1. I am wondering if maybe some of the functional blocks on the device are not fully awake (after power-down & powering back up) before your test sequence is trying to operate the motor
can you share more details on the outcome of 'misses to start the motor?'
1. I am trying to determine activity on the phase voltage outputs especially - do they stay at fixed voltages, or does it at least attempt to drive the motor?
2. to debug, I suggest that we may need some more information on the system-level performance, on functional blocks such as:
  1. VM, VCP, AVDD, OUTA/B/C, nSLEEP, etc.

Best Regards,
Andrew

0 Aaron Barrera over 2 years ago in reply to Andrew Liu

TI__Mastermind 26046 points

Hi Jayam,

Do you still need assistance? If not please mark as Resolved.

Thanks,
Aaron

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MCT8316Z: MCT unable to drive motor sometimes