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an investigation of dual stator winding induction machines

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Definition 3.2:<br />

If E is the electric field in the area, O is the boundary <strong>of</strong> the area S, then from<br />

Stoke's theorem, the following property c<strong>an</strong> be established:<br />

∫<br />

O<br />

E ⋅ dl = 0<br />

(3.3)<br />

Definition 3.3: Ampere's Law<br />

Ampere's law is the fundamental basis on which we begin our electric machine design<br />

<strong>an</strong>d <strong>an</strong>alysis. It c<strong>an</strong> be expressed as:<br />

∇ 0<br />

× B = µ ⋅ J<br />

(3.4)<br />

where, B is the magnetic flux density, J is the current density <strong>an</strong>d µ 0 is the<br />

permeability <strong>of</strong> free space.<br />

Doing integration on both sides <strong>of</strong> equation (3.4) over <strong>an</strong> arbitrary finite open surface:<br />

∫<br />

S<br />

∇ ×<br />

∫<br />

B 0<br />

S<br />

⋅ ds = µ J ⋅ ds<br />

(3.5)<br />

By Stoke's theorem, the left side <strong>of</strong> equation (3.5) c<strong>an</strong> be altered to the form:<br />

∫<br />

S<br />

∫<br />

∇ × B ⋅ ds = B ⋅ dl<br />

(3.6)<br />

O<br />

The right side <strong>of</strong> equation (3.5) is obviously proportional to the current flowing<br />

through the surface S . Then a simple format <strong>of</strong> the integration <strong>of</strong> Ampere's law c<strong>an</strong> be<br />

expressed as:<br />

∫ B ⋅ dl = µ 0I<br />

(3.7)<br />

O<br />

If the behavior <strong>of</strong> the magnetic field in the material bodies is considered, the usual<br />

format <strong>of</strong> the integration <strong>of</strong> Ampere's law c<strong>an</strong> be expressed as:<br />

88

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