| 摘要 |
PURPOSE:To prevent the burnout of a coil and the damage of an output transistor by detecting the abnormal lock state of a brushless motor by a rotation detector, a time measuring unit and an energization stopper and automatically stopping the current supply to the coil. CONSTITUTION:When a motor is locked with mechanical overload, an instruction signal 80 varies from 5V to 0V. Coils 1, 2 are energized immediately after the transistors 83, 84 of a rotating stop switch 105 are interrupted, but the condenser 67 of a time measuring unit 103 is charged. When the terminal voltage Va becomes equal to or larger than VCC/2, the transistor 77 of an energization stopper 104 is conducted. As a result, the energization of the coils 1, 2 is completely stopped, and since the generating voltage is zero, the output currents i1, i2 of a rotation detector 101 are zero, and the transistor 64 of the unit 103 continues OFF state. |
