The attached DC motor tutorial is a little more complete than those found in many text books. Extract follows...
The I2R term represents heat dissipated in the armature, but the very important term EoI is the electrical power that is converted into mechanical power. The mechanical power of the motor is therefore exactly equal to the product of the cemf multiplied by the armature current
P = EoI (5.5)
where
P = mechanical power developed by the motor [W]
Eo = induced voltage in the armature (cemf) [V]
/ = total current supplied to the armature [A]
So if you reduce CEMF, then your mechanical power output, at full speed will decrease.
The I2R term represents heat dissipated in the armature, but the very important term EoI is the electrical power that is converted into mechanical power. The mechanical power of the motor is therefore exactly equal to the product of the cemf multiplied by the armature current
P = EoI (5.5)
where
P = mechanical power developed by the motor [W]
Eo = induced voltage in the armature (cemf) [V]
/ = total current supplied to the armature [A]
So if you reduce CEMF, then your mechanical power output, at full speed will decrease.
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