What is the difference between a dc motor and a 3 phase ac motor?
Since it is obvious that a DC motor is energized by DC power and an AC motor is energized by AC power, I will try to explain what is not quite so obvious. “… analysis of a DC machine shows that associated with both the rotor and stator are magnetic flux distributions which are fixed in space and that the torque-producing characteristic of the DC machine stems from the tendency of these flux distributions to align. An induction machine, in spite of many fundamental differences, works on exactly the same principle; one can identify flux distributions associated with the rotor and stator, which rotate in synchronism and which are separated by some torque-producing angular displacement.” Fitzgerald, Kingsley, Umans “Electric Machinery” 4th ed In a DC machine, the flux of the stator is completely stationary. The flux of the rotor tends to rotate as the rotor turns, but as soon as the rotor turns sufficiently to engage the next commutator segment, the flux distribution is reset to the origin
