| 摘要 |
PURPOSE:To reduce the fallen value of rotation of an apparatus, even when abnormality occurs, and to return said apparatus quickly to the state of operation before said abnormality occurred, by providing said apparatus with two control systems so as to change one control system to the other one, when abnormality occurs in said one control system. CONSTITUTION:An apparatus is provided with a normal A control system and a stand-by B control system. In the middle of a passage through which a signal from rate-of-change controllers 30A, 30B is inputted to voltage controllers 31A, 31B and frequency controllers 36A, 36B, there is a switch 51 to select one of said A and B systems. During operation of the A system, that is, while the B system is standing by, a B phase controller 33B always synchronizes a clock and pulse oscillation timing built in itself with a phase from the input side voltage of an AC-to-DC converter 22 and stands by so as to be capable of operating immediately when a phase command from a current controller 32B comes. In this manner, the fallen value of rotation of a motor can be reduced, even if the control system is changed to the stand by system. |
