Patent ID: 7239061
Filing Date: 2007-07-03
Classification: H02K

Abstract:
1. A switching pattern AC induction motor comprising a machine base, a stator and a rotor, said stator including a core of cylinder shape, stator teeth being disposed on the internal surface of said stator core in equal angles and extending inward along a radial direction with stator grooves penetrating along an axial direction between the teeth; the number of the stator grooves or teeth being determined by the following equation: Z=2*M*P*Q, where M being the number of phases of the excitation voltages, P being the number of pairs of stator poles, and Q being the number of grooves or teeth per pole per phase; excitation windings being disposed in the stator grooves, and the rotor of the motor being of a squirrel cage structure, wherein: said excitation windings on the stator of the motor being excited by a sine wave switching AC pulse modulated excitation voltages, and the number K of the metal conducting bars in the rotor ‘squirrel cage’ being twice of the number P of pairs of the stator poles, i.e. K=2P wherein, the sine wave switching AC pulse modulated excitation voltages are generated by performing pulse width modulation or pulse amplitude modulation on two phases of continuous modulating sine wave voltages with phase difference of 90° or three phases of continuous modulating sine wave voltages with phase difference of 120° with equal virtual values and frequencies, together with a pulse square wave voltage having a waveform of symmetric square wave with a duty factor of 50% of which the frequency (F 2 ) is within the frequency range of voice or ultrasonic and much larger than the frequency (F 1 ) of said continuous modulating sine wave voltages.