Automotive Motor constants at high current

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SUMMARY

The motor constants KV (velocity constant) and KT (torque constant) do not remain constant at high currents due to magnetic saturation effects in brushless DC (BLDC) motors. As current increases, torque increases linearly with stator current until the stator reaches magnetic saturation, after which the torque per amp begins to decrease non-linearly. Larger stators can handle higher currents before experiencing saturation, impacting performance. Understanding these dynamics is crucial for effective motor design and application.

PREREQUISITES
  • Understanding of motor constants KV and KT
  • Knowledge of brushless DC (BLDC) motor operation
  • Familiarity with magnetic saturation concepts
  • Basic principles of torque and current relationships in electric motors
NEXT STEPS
  • Research the effects of magnetic saturation in electric motors
  • Explore the design considerations for larger stators in BLDC motors
  • Study the relationship between stator geometry and current handling capacity
  • Learn about the implications of non-linear torque characteristics in motor control
USEFUL FOR

Engineers, motor designers, and hobbyists interested in optimizing the performance of brushless DC motors under varying current conditions.

Yoni
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Hi,

This is a general question:

Do the motor constants KV and KT stay constant at high current?

Thanks
 
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Not helping. In wikipedia they only state a linear relationship between torque and current.

My question is if this linear relationship remains at ever increasing currents (and before the wires burn)?
 
You didn't address my question to you yet...
berkeman said:
What changes with high motor current?
Also, which motor type(s) are you asking about? And why would the motor type make a difference? :smile:
 
My understanding is for a given KT in BLDC mode, the torque increases roughly linearly with stator current until the stator reaches magnetic saturation (depending on stator size, material, geometry), at which point, the torque per amp begins to taper off in a "non-linear" fashion. Generally larger physical size stators can handle more current before saturating.
 

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