| 摘要 |
PURPOSE:To improve the input power factor by providing a power-factor improving capacitor which is charged from a commercial power source through a rectifying circuit and an inverter and whose polarity is reversed by the resonance action of the inverter. CONSTITUTION:A power-factor improving capacitor C3 is connected in parallel to the series circuit of a diode D5 with an inductor L1, and the inductor L1 and capacitor C3 constitute a resonance circuit. A resistor R1, a capacitor C4, and a diode AC switch (diac) DA1 constitute a starting circuit, and a capacitor C4 is charged through the resistor R1. When its charged voltage reaches the breakdown voltage of the diode AC switch DA1, the diode AC switch DA1 is turned on, base current is supplied to a transistor Tr1 from a capacitor C4, and an inverter INV begins to oscillate. The polarity of the capacitor C3 is reversed by utilizing the resonance action of the inverter INV, and its electric charges are returned to the input current. This reduces the higher harmonic components of the input current, and improves the input power factor. |
