| 摘要 |
PURPOSE:To prevent the voltage in a factory from dropping and an illuminator from keeping on flickering caused by generation of a large electric current at acceleration of a motor by lowering the limiting value of the driving current of the motor only when a rotating speed commanding value for being inputted in a motor exceeds a standard value of the rotating speed. CONSTITUTION:A pedal sensor 30 detects the amt. of stepping-in of a pedal and transmits it to a sewing machine controlling device 32, which transmits a command signal of a rotating speed of a motor corresponding to the amt. of stepping-in to a motor controlling device 34. The motor controlling device 34 performs a signal treatment in such a way that the detecting signal inputted from a motor speed detecting device 26 coincides with the command signal inputted from the sewing machine controlling device 32. In this case, when the command value is larger than the standard value, a signal S1 for an electric current limiting value is switched so as to lower the electric current limiting value and it is inputted into an electric current limiting circuit 40 and it is compared with a signal S4 for a motor current detecting value from a motor driver 38 and limitation of the electric current is performed in such a way that the motor current detecting value does not exceed the electric current limiting value. |
