Abstract: Synchronous motor controlling apparatus and method controls power applied to minimize or eliminate speed variations of a synchronous motor due to variations in load imposed the motor. The rotational position of a rotor of the synchronous motor based on the input terminal voltages and currents to the synchronous motor, and the power applied to the motor is adjusted accordingly. Higher harmonics of the input voltages and currents may also be used to detect the position of the rotor. In addition, the apparatus and method also accounts for the varying speed command inputs.

Abstract: This synchronous motor controlling apparatus comprises a current detection section 5a, voltage detection section 5b, position and speed detection section 6, speed difference calculation section 7a, speed controlling section 7b, torque controlling section 7c, multiplication section 7d, phase controlling section 8, and current controlling section 9. The current detection section 5a detects a motor current supplied to the synchronous motor 4. The voltage detection section 5b detects a voltage at a terminal of the synchronous motor 4. The position and speed detection section 6 is determined a motor model therein, receives the motor current and voltage as input, carries out predetermined operation, and detects a rotation speed of a rotor and rotation position of the rotor. The speed difference calculation section 7a calculates a difference between the detected speed and a speed command given from the exterior.

Abstract: When torque control is performed for suppressing speed change within one rotation using a synchronous motor (6) controlled by an inverter (5) for a load having cyclic torque changing, an arrangement is employed which includes inverter control means (8) (10) for controlling the inverter (5) so as to superpose a changing amount upon an amplitude and phase of a current waveform or voltage waveform, so that torque control is realized for reducing low speed vibration of a cyclic intermittent load with maximum efficiency condition and with practical arrangement.