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Introduction to Space-Vector Theory. A. -C. B. -A. C. Simple induction machine. A. -B. -C. Stator winding. Solid iron. -B. 0 o. 360 o. B. C. -A. Phase A. magnetic axis. ”corresponding” coil. Phase B. magnetic axis. ”corresponding” coil. Phase C. magnetic axis.
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A -C B -A C Simple induction machine A -B -C Stator winding Solid iron -B 0o 360o B C -A
Phase A magnetic axis ”corresponding” coil
Phase B magnetic axis ”corresponding” coil
Phase C magnetic axis ”corresponding” coil
B A C Coils of the three-phase system • the maximum of the magnetomotive force coincides with the magnetic axis of the phase • sinusoidal variation along with the air gap
Magnetomotive force (MMF) in the air gap • with a unit phase current and unit number of windings caused by phase A caused by phase B caused by phase C
MMF produced by three-phase currents at t=0 ia=1 ib=-0.5 ic=-0.5
Here, MMF depends on the time and the position angle sinusoidally Phase currents Total MMF Moves to the positive direction
Space-vector theory assumes sinusoidal spatial behaviour • However, the time-variation of the phase quantities can be arbitrary
Pulsating magnetic fields produce a rotating field • Visualisation for the two-phase and two-pole winding • Can you see the rotation..?