| 摘要 |
PROBLEM TO BE SOLVED: To accurately judge the out-of-step of a synchronous motor when lightly loaded over a wide operation state. SOLUTION: Expected power that is outputted from a motor is obtained based on the torque command and speed of the synchronous motor. On the other hand, consumption power is detected based on voltage and current being applied to the motor. When a parameter including the deviation or ratio of both of them exceeds a preset threshold, it is judged that out-of-step has occurred. When the deviation between the expected power and the consumption power is to be utilized as parameters, the threshold is set in the relationship with the torque command and the speed. When the ratio of the expected power to the consumption power is to be used as a parameter, the threshold is set in the relationship with the speed, thus accurately judging out-of-step with an extremely light load. |
