| 摘要 |
PROBLEM TO BE SOLVED: To satisfactorily perform a vector control operation by solving the problem that when a synchronous motor is in a low-speed region, the induced voltage in the synchronous motor is dropped, that the estimated accuracy of a magnetic axis is degraded, and that when the vector control is performed in a low-speed region, the magnetic axis is lost making vector control operation impossible. SOLUTION: Sensorless vector control is performed, by using the rotational speed and the rotor position of the synchronous motor 6. While it is assumed that a d-axia as a true magnetic axis exists in a phase which is deviated from a γ-axis by a load angle θe, a positive current is made to flow to the γ-axis. Thereby, a torque which is proportional to iγ sin θe and which advances in the direction of the γ-axis is generated in the magnetic axis. Thereby, errors in a d-q axis as a true magnetic axis and a γ-δ axis as a control axis are eliminated. Even when a load is applied, the γ-δ axis as the control axis is made to coincide with the d-axis as the magnetic axis of the synchronous motor, and the vector control can be performed satisfactorily. |
