Speed of a Cumulative Compound DC Motor

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SUMMARY

The discussion focuses on the equation for calculating the speed (ω) of a Cumulative Compound DC motor, represented as ω = K(Vt - IA[RA + RF]) / (ΦP + ΦS). Participants seek clarification on the constant K, suggesting it is determined by the motor's geometry. There is debate over whether the terminal voltage (Vt) should be replaced by the armature voltage (Ea) and the nature of the torque-speed curves, which are neither perfectly exponential nor linear, influenced by internal friction and motor design.

PREREQUISITES
  • Cumulative Compound DC Motor principles
  • Understanding of electrical engineering equations
  • Knowledge of torque-speed characteristics
  • Familiarity with motor geometry and constants
NEXT STEPS
  • Research the derivation of constants in DC motor equations
  • Study the impact of armature voltage (Ea) on motor performance
  • Explore torque-speed curve analysis for different motor types
  • Investigate the effects of internal friction on motor efficiency
USEFUL FOR

Electrical engineers, motor design specialists, and students studying DC motor dynamics will benefit from this discussion.

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I came across an equation for the Speed ω in Radians/seconds of a Cumulative Compound DC motor.

ω= K(Vt-IA[RA+RF)/(\PhiP+\PhiS)

  • How would we calculate K in this equation?
  • Shouldn't the Terminal Voltage Vt be replaced by Armature Voltage Ea?
  • I came across a lot of varying torque speed curves. WIll the curve be exponentially decaying or linear?
 
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Maybe you should explain your formula and the used variables, or at least give its source.
My guess: K is some constant given by the geometry of the motor.

I came across a lot of varying torque speed curves. WIll the curve be exponentially decaying or linear?
I don't think that any of these curves are perfectly exponentially or linear. In addition, it might depend on the motor (e.g. how its internal friction depends on the angular velocity).
 

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