| 摘要 |
PURPOSE:To detect an accurate phase independently of a frequency by using the characteristic of a 3-phase AC to detect a maximum voltage point. CONSTITUTION:In a making phase detecting circuit 1 in a power factor adjuster equipped in a 3-phase AC power source, a diode matrix circuit 12 where only positive-side rectifiers of a specific phase are dropped out from 3-phase full wave rectifying circuits is connected in secondary sides of transformers 11 whose primary sides are subjected to delta connection and secondary sides are subjected to star connection. If a waveform where the positive-side waveform of a specific phase is dropped out in an unrectified component is obtained by 3-phase full wave rectifying circuits, a minimum point of the rectified output wave of the specific phase is detected because the zero point of said waveform coincides with a maximum voltage point of the specific phase, and a phase advance capacitor is made by this detection output. |
