| 摘要 |
PURPOSE:To suppress the production of noise and vibration of a DC motor by setting the energizing current waveform of the motor to a voltage waveform half-wave or full-wave rectified from the AC voltage of a semiconductor switching element and a freewheel diode. CONSTITUTION:When an armature current detection output detected by a resistor 10 is raised over the upper side slice level of a Schmitt trigger 26, transistors 27, 7 are interrupted, the magnetic energy of a motor 9 is discharged through a freewheel diode 11, thereby gradually reducing the armature current. As th armature current decreases, the detected output of the resistor 10 is lowered over the lowerside slice level of the Schmitt trigger 26. Then, the transistors 27, 7 are conducted, and the armature current is again increased. Accordingly, the constant speed control determined by the hysteresis width of the Schmitt trigger 26 is performed by controlling the gate voltage of the FET14 and the output of the OP amplifier 17 by the output of an error amplifer 30. |
