Speed of a Cumulative Compound DC Motor

mobin.abrar

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

ω= K(V_t-I_A[R_A+R_F)/([itex]\Phi[/itex]_P+[itex]\Phi[/itex]_S)

• 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?

mfb

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 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).