| 摘要 |
PURPOSE:To protect respective transistors by generating a pulse having small pulse width for a sporadic overcurrent whereas generating a pulse having large pulse width for overload of a motor. CONSTITUTION:Upon occurrence of sporadic overcurrent state, a pulse having small pulse width is generated from a monostable multivibrator 16 and a transistor 10 is turned OFF for the duration of the pulse width. When the motor is overloaded or when the rotational shaft thereof is locked, pulses having small pulse width are generated successively from the monostable multivibrator 16. Consequently, a transistor drive circuit 23 generates power conduction pause command signal having large pulse width thus turning the transistor 10 OFF for the duration of the pulse width. By such arrangement, rational control can be carried out according to sporadic overcurrent, overload of motor or locking of the rotational shaft, and the transistor 10 can be protected. |
