| 摘要 |
<p>PURPOSE:To prevent a field coil or other parts from burning or damaging by suppressing the increase in the field current at the low speed operation time. CONSTITUTION:Output voltages generated at output coils U-W are supplied through a full-wave rectifier 11, an output voltage detector 6 having a resistor 20 and a capacitor 24, a voltage divider, and a constant-voltage diode 12 to a control transistor 12. On the other hand, a half-wave rectified voltage of W-phase is supplied to the anode side of SCR26, and a half-wave rectified voltage of U- phase is supplied to a capacitor 37. Since the discharging period T1 of the capacitor 37 is long at the low speed rotation time, the SCR26 is not turned ON. Thus, the voltage of W phase is superposed on the output of the detector 6, thereby suppressing the increase in the field current. When the rotating speed increases, a discharge period T1 decreases. Accordingly, the SCR26 is turned ON. Thus, it is controlled only by the voltage from the output voltage detector 6.</p> |
