Summary:...
When converting electrical power to mechanical power, DC motors experience some losses like all machinery (note that in generators, mechanical power is converted to electrical power, and the losses experienced are the same). Although there are many ways that manufacturers and experts can count losses, a common method is to divide them into five columns: mechanical, magnetic, copper, carbon brushes, and stray losses.
Because mechanical loss and magnetic loss are approximately proportional to the rotation speed of a DC motor, they can be gathered together and are called rotation loss.
Mechanical loss
As the name implies, mechanical losses are caused by the movement of the motor. These include the loss of motor bearings, the loss between the carbon brushes and the commutator, and the resistance to the rotor caused by the turbulence of the surrounding air.
Magnetic loss (iron core loss or iron loss)
These losses are related to the magnetic circuit of the motor. Magnetic loss includes hysteresis loss caused by the change in the polarity of the magnetic flux in the iron core, and eddy current loss, which is caused by the change in the polarity of the magnetic flux. The magnetic loss is fixed, if the magnetic field current and speed are fixed.
Copper loss (electronic loss or winding loss)
These losses can also be referred to by multiple names, including the term "I2R losses" because they are caused by the magnetic field and the impedance of the armature winding.
Carbon brush loss
During the commutation, some loss occurs between the inverter and the carbon brushes. The amount of carbon brush loss depends on the voltage drop between the contact point and the armature current. Please note that the loss of carbon brushes is sometimes included in the stray loss category.
Stray load loss
Losses that cannot be easily classified are called "stray loads" categories. Because the armature reacts to the short-circuit current during commutation and flux distortion.
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