Apparatus and method for driving synchronous motor

摘要

The synchronous motor driving apparatus (2) including position sensors (9) provided in the synchronous motor, a current polarity detection circuit (13) for detecting the polarities of the currents in the respective phase windings (8) of the synchronous motor, an inverter (3) driving the synchronous motor, a motor speed calculation unit (48) calculating the rotational speed (Ér) of the synchronous motor depending on the output signals from the position sensors (9), a speed control unit (47) outputting a first voltage adjusting component (q-axis current command value Iq*) to cause the rotational speed of the synchronous motor to approach a speed command value (É*) and a phase control unit (45) outputting a second voltage adjusting component (d-axis current command value Id*) to cause the phase differences between the phases of the position sensor signals and of the currents in the respective phase windings of the synchronous motor to become a predetermined value.