| 摘要 |
PURPOSE:To prevent a motor from heat generation in case of overload by a method wherein current supply is stopped to the motor when the control signal values to make the motor speed agree with the command speed maintain themselves in a certain value or more for a certain period. CONSTITUTION:The conductivity angle of the motor m the speed of which is under the control of the conductivity angle of the supplied current is controlled by the control signal 11. The detected values from the speed detector 15 of the motor and the command signal from the speed commander 17 are compared in the data processing circuit 16 and then, the control signal 21 to make the speed of the motor m agree with the command speed is put into the signal generation circuit 20 to generate the control signal 11. In the meantime, when the value of the control signal 21 is the setting value or more of the setting device 22, then, the pulse signal is emitted from the comparator 23 and is counted through the counter. When the digital value within the specified period becomes the specified value or more, then, the synchronous generation circuit 25 is halted by the circuits 30 and 28, thus, the circuit 16 is halted to stop the current supply to the motor m. |
