| 摘要 |
PROBLEM TO BE SOLVED: To recover a stable region quickly when the load angle enters into an instable region by making a decision that the limit of stable operation is reached when the load angle exceeds a preset value and then increasing the field current. SOLUTION: Load angle (hereinafter referred to δc is monitored at parts number 20, for example, and an F signal is switched from 0 to 1 instantaneously when a set value δ on is exceeded. Absolute value of δc is operated and used for determining the switching time so that it can be used as it is even during recovery. In order to prevent chattering of an F signal in the vicinity of δon, a hysteresis comparator 202 is employed. A level for resetting the F signal is set by the value of δ off. A switch 18 is normally turned to '0' side and switched to '1' when the F signal outputted from the comparator 202 is 1 thus making a switching to the maximum value of an If* field converter. A setter 19 sets a maximum value for the field converter or the field circuit of a motor. |
