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Reversing the run time requires Rs to be large

user4708725
Expert 1030 points

Evaluation board:  drv8301-hc-evm revd

Lab 10a Overmodulation

The motor has a speed of 300rpm, forward running and output torque of 60mNm. At this time, Rs=0.185 is required.

The motor is running at a speed of 300rpm, reversing operation and output torque of 60mNm. At this time, Rs=0.191 is required.

Regardless of whether the motor is forward or reverse, all procedures are the same, but reverse requires Rs to be large,

Low Starting Torque of Motor in Reverse Operation.I want the same Rs for motor forward and reverse.

 

How to solve this problem?

  • 0
    TI__Guru** 117160 points

    I don't think the requirement of Rs must be critical during the startup since there is only 3% error. You may try anyone or the large value for both states. 

  • 0 in reply to Yanming Luo
    Expert 1030 points

    I have confirmed very well that the resistance of forward and reverse is different.

    This is the conclusion that 5000 different hardware circuits and temperature characteristics are taken into account. Reverse on-load start sometimes fails, and the torque of reverse start is weak. Please give a solution?

  • 0 in reply to user4708725
    TI__Guru** 117160 points

    As replied to your questions in other threads, ensure the board has a similar sensing performance on each board and the resolution tolerance of current/voltage should be less than 1%. You should do the offset calibration also, and enable the force angle.

    Maybe, loads of reverse and forward are not the same during startup as you said since the frictions are not the same for the forward and reverse rotation in most cases. So, please check if the startup load is less than the rated torque of the motor. If not, that will be difficult to meet your requirement, especially, the sensing signals are not good on the hardware board.