Issues with constant-power control - EVAL-M1-05F804R with EVAL-M1-101T

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alex-d
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Hello. I am using power stage board EVAL-M1-05F804R  with controller EVAL-M1-101T  #EVAL-M1-101T to run a motor.

My goal is to run the motor at a set power, so I've added a power-control script from page 18 of this documentation.

The issue is this: the method of powering on the power stage board (by either gradually increasing the applied voltage or instantly supplying the desired voltage) can cause the motor to run at a higher power than targeted.

I set the script to run the motor at a consistent power of ~30 Watts, varied the methods of powering on the circuit board, and recorded the differences between actual power and calculated power:

alexd_0-1705071779311.png

PowerRslt is from the power-control script (see page 18 of this documentation), and represents the power usage. For the sake of visibility, I converted PowerRslt variable from counts to Watts. 

Some observations:

  • Despite the major changes in motor performance, the current, voltage, and power as shown in MCEDesigner all remained consistent
  • Power as measured by my supply ranged from 28 to 50+ Watts, but the power as calculated by the script stayed around 30
  • I am confident my power supply is accurate in there being major fluctuations, as I am able to observe a physical performance difference in the motor from try-to-try
  • A power cycle on the power stage board is the only way to reset the different performances

My questions:

  • Why are there differences between power as measured by iMotion, and power as measured by power supply?
  • What steps can I take to prevent or lessen these differences in performance?

I have attached the MCEWizard file I have used. Please let me know if you need clarification on my script or testing process. Thank you.

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1 Solution
SarkarSushru
Moderator
Moderator
Moderator
50 replies posted 50 sign-ins 10 solutions authored

Hi ,

  • Please monitor the values of IdFilt, IqFilt, Vd and Vq, and calculate the motor power using the formula:

 

SarkarSushru_1-1705312340242.png

  • Please mention how the supply current and voltages are measured. Are the current and voltage values stable while measuring? Please make sure if the power measured by iMotion and actual power measured simultaneously.
  • Small deviation between the supplied power and the motor output is expected due to various losses. Please account for any other losses.
  • Some oscillations in speed of the motor is expected depending on the load conditions, in case of constant power operation.

 

Please let us know if you have any further query.

Thank you,

Sushruti

View solution in original post

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1 Reply
SarkarSushru
Moderator
Moderator
Moderator
50 replies posted 50 sign-ins 10 solutions authored

Hi ,

  • Please monitor the values of IdFilt, IqFilt, Vd and Vq, and calculate the motor power using the formula:

 

SarkarSushru_1-1705312340242.png

  • Please mention how the supply current and voltages are measured. Are the current and voltage values stable while measuring? Please make sure if the power measured by iMotion and actual power measured simultaneously.
  • Small deviation between the supplied power and the motor output is expected due to various losses. Please account for any other losses.
  • Some oscillations in speed of the motor is expected depending on the load conditions, in case of constant power operation.

 

Please let us know if you have any further query.

Thank you,

Sushruti

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