Introduction to Electrical Power and Power Electronics

91

4

AC and DC Motors

Of the total electrical energy generated worldwide, about 58% is used by all motors

combined, about 7% for lighting, and the remaining 35% for heating and other uses.

Major types of motor are the synchronous motor, induction motor (also known as

asynchronous motor), and dc motor. All have two sets of coils with different cur-

rents, say, I

1

and I

2

. The electromagnetic interaction between two currents produces

motor torque T

m

= KI

1

I

2

. If the motor shaft has a load torque T

Load

< T

motor

, the motor

would accelerate to a speed at which T

Load

= T

motor

, where it would stop accelerating

and run at steady speed. The motor armature ...