| 摘要 |
PURPOSE:To reduce the power loss of a brushless DC motor and protect the DC motor when the motor is locked by controlling the base current of an output transistor on the basis of the detection signal of the voltage generated at the coil of the motor and detecting the locked state of the motor. CONSTITUTION:When a motor rotates at a high speed, the voltage generated at a coil 1 becomes, when a coil 2 is energized, high, a diode 32 and transistors 37, 38 become ON, the difference between the output current i1 and a constant current I0 is produced by a current subtractor 105 to become a current i2, which is amplified to a current i3 through current amplifiers 106, 107. Accordingly, the current i3 decreases at the high speed rotating time, thereby reducing the base currents of output transistor 9, 10. Then, the coils 1, 2 are energized immediately after a switch 11 is ON when the motor is locked, but a condenser 70 of a time measuring instrument 103 is charged, and when the terminal voltage V3 becomes higher than VCC/2, a transistor 61 of an energization stopper 104 becomes ON, thereby completely stopping the energization of the coils 1, 2. |
