| 摘要 |
PURPOSE:To prevent the damage by a seizure of the coil or destruction of the output transistor of the brushless motor by a method wherein the locked condition of the motor is detected by a rotation detector, a time measuring instrument and a current feed stopper, and current feed to the coil is stopped automatically. CONSTITUTION:When the motor is locked according to mechanical overload immediately after a switch 17 is made to ON, currents are fed to the coils 1, 2, the capacitor 42 of the time measuring instrument 102 is charged, and when the terminal voltage (c) thereof becomes to larger than Vcc/2, the transistor 58 of the current feed stopper 103 is made to ON. As a result, current feed to the coils 1, 2 is stopped, and the motor continues to be in the stop condition. Because output (a) of a Hall IC 5 stops at either of high potential or low potential, the transistor 36 of the rotation detector 101 is made to ON, and the transistor 40 of the time measuring instrument 102 continues to be in the OFF condition. Namely, a positive feed back loop is constructed of the rotation detector 101, the time measuring instrument 102, the current feed stopper 103, a distributor 100 and the coils 1, 2. |
