| 摘要 |
PROBLEM TO BE SOLVED: To prevent a voltage across both terminals of a smoothing capacitor from increasing abnormally, for example, if a dimmer lamp is on when an input current distortion is reduced by a simple circuit configuration and at the same time the oscillation frequency of an inverter circuit is increased. SOLUTION: A pulsive current Id is allowed to flow from a rectifier DB at a high frequency, and input current harmonic distortion is reduced and power factor is improved with a simple circuit configuration according to the relationship among three voltages of a voltage Vc4 across the terminals of a capacitor C4, a voltage Vdc across the terminals of a smoothing capacitor C1, and a pulsation current DC voltage Vin and a high-frequency operation of an inverter circuit consisting of switching elements Q1 and Q2 and diodes D1 and D2 that are connected inversely in parallel with each both terminals of the switching elements Q1 and Q2. Then, the capacitance value of the capacitor C4 is set in a direction for setting the current waveform of an input current Iin to nearly sinusoidal waveform near the center value of the variable range of the oscillation frequency of the inverter circuit. |
