DRV10983EVM: Minimum closed loop reliable RPM

Prodigy 10 points

Replies: 2

Views: 40

Part Number: DRV10983EVM

Attempting to drive 22 pole BLDC motor with Kt value 82.  Phase to phase resistance is 7 ohms.

We are driving the motor with the EVM board and have had success with Open to Closed loop transition.

We desire to run the motor at low speeds 30-500 RPM and maintain a reasonable torque throughout the range.

It appears when at 60 RPM or lower the system will run but as soon as a small amount of load is applied, the calculated back EMF starts to rise and the motor faults out on Back EMF calculation.  In the 200-300 range, the motor appears to deliver the torque we desire.

Are there options or settings that can be changed to improve the condition when running at low speeds?

2 Replies

  • Hi Luke,

    Thanks for posting your question in MD forum. The reason for this failure is because when the motor is loaded at 60 rpm, the BEMF voltage is not aligned with the phase current. In this condition, the device will not be able to deliver sufficent current to drive the load and triggers Abnormal Kt fault. This issue can be addressed by adjusting the lead time/advance time. To identify the correct lead time, disable Abnormal Kt fault, load the motor at 60 rpm and read back the estimated Kt. Keep adjusting the lead time till the estimated Kt matches the actual Kt of the motor.

    Regards,

    Vishnu.  

  • In reply to Vishnu Balaraj:

    Hi Luke,

    We haven't heard from you in a while. Do you have any updates? If not then we can close this thread.

    Regards,

    Vishnu.