Question

1.Just like in a transformer, the three main sources of loss in an electric motor are: 1-Conduction losses (aka joule losses, or I²R losses) from the windings 2- Hysteresis losses in the steel 3- Eddy current losses in the steel core, as well as in any other metals in the rotating field In motor controls, a major source of research (both in industry and academia) is finding ways to reduce those losses in an existing motor just by changing the control scheme. Above, we can see that conduction losses are proportional to the SQUARE of the phase current. Assume Ef and, therefore, the motor speed, are constant. For a given motor torque, what is the optimal angle between Ef and Ia to minimize the stator current and, therefore, conduction losses. It may help to recall that ?m= ?m × ?m.