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SENSORLESS FIELD ORIENTED CONTROL OF BRUSHLESS ...

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Figure C.6 –Short-pitched windings: (a) concentrated; (b) distributed.<br />

Each of the four windings shown above is a different approximation to a sinusoidal winding. But,<br />

an additional degree of freedom exists because the interconnection of the windings does not<br />

matter so long as it is additive (the only sensible choice) [27, p.552]. This is essentially the<br />

difference between the traditional lap and concentric windings. For example, Figure C.6-b is a lap<br />

winding but would yield the same result as the concentric winding shown in Figure C.7-a.<br />

Figure C.7 – Concentric winding of Figure C.6-b: (a) phase-A only; (b) all phases.<br />

It might be noted that the winding of Figure C.7-a looks somewhat like the stepped winding of<br />

Figure C.4 that was said to be more difficult and expensive to manufacture. The difference (each<br />

phase does not have coilsides in each slot) is revealed when the other phases are drawn in, as<br />

shown in Figure C.7-b. Each slot contains the coilsides of only two phases, whereas the three-<br />

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