| 摘要 |
PURPOSE:To prevent the burnout of a drive coil and the damage of an output transistor by detecting the lock state of a motor on the basis of the generated voltage from a generating coil provided to cross a field magnetic flux and stopping the energization of the drive coil. CONSTITUTION:When a motor is locked by a mechanical overload, a current is supplied to drive coils 1, 2 directly after a switch 27 is ON, but when the charging voltage V1 of a capacitor 67 of a time measuring unit 103 becomes larger than the voltage Vcc/2, the transistor 77 of an energization stopper 104 becomes ON. Accordingly, the energization of coils 1, 2 is completely stopped, and the motor continues the stopping state. Since the generating voltage of a generating coil 20 is zero, the output current i1 of the rotation detector 101 is zero, and the transistor 64 of the unit 103 continues OFF. In other words, a positive feedback loop is composed of the detector 101, the unit 103, the stopper 104, the output transistors 9, 10, and drive coils 1, 2. |
