ABSTRACT
AC machines with three or more phases (n ≥ 3) operate utilizing the principle of rotating Ÿeld,* which is created by spatially shi³ing individual phases along the circumference of the machine by an angle that equals the phase shi³ in the multiphase system of voltages (currents), used to supply such a multiphase winding. Such machines are of either synchronous or induction type. All rotating Ÿelds in multiphase machines, caused by the fundamental harmonic of the supply, rotate at synchronous speed, governed with the stator winding frequency. When the rotor rotates at the same speed, the machine is of synchronous type. When the rotor rotates at a speed di¦erent from synchronous, the machine is called asynchronous or induction machine.
