| 摘要 |
PURPOSE:To reduce the base current of a switching transistor of a voltage converter for supplying a variable DC voltage in response to th detected rotating speed value of a brushless motor at the constant speed rotating control time by increasing or decreasing the base current of the transistor when the transistor is ON. CONSTITUTION:The output Vd of a speed detector 17 is compared by a comparator 12 with a triangular wave signal of the prescribed frequency of a triangular wave generator 11, thereby setting a duty transistor Tr13 to ON or OFF in response to the voltage Vd. When the Tr13 is ON, Tr 17 is OFF, and switching Tr20 becomes OFF. When the TR13 is OFF, the current i1 of a constant-current source 15 and the current i2 corresponding to the voltage Vd are supplied to a current mirror which has a diode 16 and a Tr17 and resistors 18, 19, the collector current of the Tr17 becomes the base current of the Tr20, and Tr20 becomes ON. When the Tr20 is ON, the voltage Vs of a DC power source 1 is supplied through an inductance 22 and a condenser 23 to a distributor 5, and when the Tr20 is OFF, a flywheel diode 21 becomes ON, and the stored energy of an inductance 22 is supplied to a load side. |
