| 摘要 |
PURPOSE:To reduce a power source facility capacity and remove a trouble caused by harmonic current by conforming the current phase of an a.c. power source with the voltage phase and installing a means for controlling the output voltage of a rectifier circuit to a set value. CONSTITUTION:A current-voltage control circuit 17 conducts pulse-width modulation control of switching elements 131-134 of a first rectifier circuit 13 only in radioscopic operation according to the current phase and voltage phase of an a.c. power source and the error between the output voltage of a smoothing capacitor 3 and a set value. The line current of the a.c. power source is conformed with the phase of phase voltage, and the output voltage of the smoothing capacitor 3 is controlled to a set value, then inputted in an inverter circuit 4. On photographing, the switching elements 131-134 are lept in the off/ state, voltage rectified by D1-D4 is smoothed with the smoothing capacitor 3, then inputted in the circuit 4. The current phase of the a.c. power source is conformed with the voltage phase and a sign wave with no distortion is obtained. Thereby, power factor is improved and apparent power is decreased. |
