| 摘要 |
PURPOSE:To contrive to enhance power efficiency and controlling performance of the brushless DC motor by a method wherein electric charge stored between the base and the emitter of a motor coil driving switching transistor is discharged forcibly. CONSTITUTION:A base current I1 having the pulse duration corresponded to a speed detecting signal Vd obtained by a speed detector 8, a comparator 14 and a base current suplier 15 makes the switching transistor 11 to perform ON, OFF action. The pulse current I3 of a base electric charge discharger 16 is inputted complementarily (alternately) with the pulse current I1 of the base current supplier 15 to a current mirror circuit (a diode 54, a transistor 55, resistors 56, 57), the output current I2 thereof is enlarged in an instant, and discharges base storage electric charge of the switching transistor 11. Accordingly, substratial storage time delay of the switching transistor 11 is reduced sharply, and fall time is also shortened. |
