| 摘要 |
PURPOSE:To reduce numbers of sine wave generator and amplitude modulator for driving a motor by one each, by using phase-shifted 2-phase alternating current, and also by employing a 3-phase differential amplifying circuit in an amplifying circuit section for control in a brushless motor control circuit. CONSTITUTION:Respective sine wave signals are generated in sine wave generators 2' and 2'' by a control signal (f) put in from a terminal 1, and these signals undergo amplitude modulation through double balancing type amplitude modulators 3' and 3'' and are impressed onto bases of amplitude-modulated transistors 6' and 6''. The transistors 6' and 6'' are connected to a constant current circuit 8 through resistors 7-7'', respectively, and these constitute a 3-phase differential amplifying circuit. Respective collector currents of the transistors 6' and 6'', which are made to pass by respective output voltage of the modulators 3' and 3'', are equally divided and pass into the resistors 7, 7'' and 7, 7'. And therefore, a torque, which is proportional to a control signal (f) and does not contain torque variation, is obtained from a brushless motor 5. |
