SENSORLESS FIELD ORIENTED CONTROL OF BRUSHLESS ...

manufactured compared to the stepped winding, but do to its complexity in analysis it is not
further discussed.
The traditional methods used to approximate a sinusoidal winding in induction motors and gridtied
synchronous machines are to use full pitch windings that are distributed, short-pitched
(chorded) windings, or a combination of the two. In all techniques, the winding is symmetrical
about the phase axis, all coils have the same span and number of turns, and all coils are connected
in series. The CFP winding is shown in Figure C.5-a. The distributed full-pitch winding is shown
in Figure C.5-b. It consists of the same two coils as the CFP but the coil axes have been offset
from zero by plus-and-minus one slot pitch. For symmetry, each coil has N/2 turns.
Figure C.5 – Full-pitch windings: (a) concentrated; (b) distributed.
The fundamental coil does not have to span a full pole pitch. In the case that it does not it is called
a short-pitched or chorded winding (it may also be called a fractional pitch winding but that
terminology is avoid here to avoid confusion with fractional slot construction). A short-pitched
winding is shown in Figure C.6-a. Each coil is one slot pitch less in span than those in Figure C.5.
In Figure C.6-b are the same four coils but their axes have been offset from one another. For
symmetry, each coil has N/4 turns.
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