1. Chapter 6 The Fundamental Theory of AC Machines

2. AC machine windings
AC rotating machine is composed in synchronous or asynchronous machines. Generally, the single AC machine and 3-phase AC machine are very popular.
Principle
1. Waveforms of EMF and MMF in a machine air-gap should be typically sinusoidal, the harmonic waves are as smaller as possible;
2. In a three phase machine, there are three voltage phases, separated by 120 electrical degrees.

3. Machine Angle --- Space angle in geometry, 360 degrees
Electric Angle & Machine Angle
Machine Angle --- Space angle in geometry, 360 degrees
Electric Angle  Defined as 360 degrees divided by the number of mechanic phases
Number of pole is 2p
Electric Angle = p×360 degree=p× Machine Angle

5. Number of Slot (per pole & per phase)
Slot angle
Number of Slot (per pole & per phase)
Phase band
The zone covered by the slots which belongs to each phase.

6. Composed by homocentric coils with different coil pitch.
Single layer windings
homocentric winding
chains winding
cross winding
Homocentric winding
Composed by homocentric coils with different coil pitch.

7. Eg: An two poles, 3-phase AC machine with 24 slots

9. The pitch of chains winding coils is same and is an odd.

10. Cross windings

11. Double layer windings