| 摘要 |
PURPOSE:To reduce the torque ripple of a motor by calculating the counterelectromotive force obtained from a bridge circuit formed of an armature, a transistor and a resistor together with a reference voltage corresponding to the output torque, thereby controlling the armature current. CONSTITUTION:A bridge circuit is formed of a 3-phase Y-connected commutator motor 1 used for a magnetic recorder/reproducer, transistors 29a-29d, 30, 26 and a resistor 32, the transistor 26 is controlled by the output of the bridge circuit, the voltage between the collector and the emitter is inputted to a differential amplifier 8, thereby obtaining a signal proportional to the counterelectromotive force. The signal is supplied to a divider 7 together with a reference voltage responsive to the output torque, the output of which divider is in turn applied through an operational amplifier 6 to the transistors 29, 30, thereby controlling the bases of the transistors. Accordingly, the armature current is controlled so that the product of the armature current and the counterelectromotive force becomes always equal to the reference voltage, thereby reducing the ripple torque. |
