Patent ID: 8421395

Claim:
A synchronous motor comprising: a housing within which windings and a rotor of the synchronous motor are disposed, said rotor being rotatably mounted at an inner side of the winding; a three-phase inverter for supplying three-phase AC voltages of variable amplitude and frequency to the windings on the basis of a gate drive signal from a gate drive circuit; position sensors for detecting the magnetic poles of the synchronous motor; a detection means for detecting input current, a value equivalent to the input current or input power and converting the input current, the value or the input power to the corresponding digital quantity; a motor speed calculation means for digitally calculating the speed of the synchronous motor on the basis of the outputs of the position sensors; a digital communication reception means for receiving through communication a digital speed command value, a digital input current command value or a digital input power command value from outside the synchronous motor; a digital feedback control means for adjusting the AC voltages and frequency of the output of the three-phase inverter in such a manner that the synchronous motor speed, the input current or the input power approaches the speed command value, the input current command value or the input power command value, respectively; and a digital communication transmission means for transmitting the digital signals representing the synchronous motor speed, the input current or the input power to outside the synchronous motor, wherein: the three-phase inverter, the gate drive circuit, the position sensors, the detection means, the motor speed calculation means, the digital communication reception means, the digital feedback control means, and the digital communication transmission means are disposed within the housing, the three-phase inverter, the position sensors, the detection means, the motor speed calculation means, the digital communication reception means, the digital feedback control means, and the digital communication transmission means are disposed one substrate, and the substrate includes a plane parallel with the rotating plane of the rotor and disposed so as to overlap a direction of a rotational axis of the rotor.