BOOSTING CONVERTER PROVIDED WITH POWER-FACTOR COMPENSATING CIRCUIT

摘要

PROBLEM TO BE SOLVED: To obtain a high power factor by raising/drooping the input current level according to the input voltage and keeping the phase of the input voltage at the same phase as that of the input voltage. SOLUTION: A comparison signal V3 and a sawtooth signal B are compared with each other by a comparator 240, and a switching transistor MT is driven by means of a waveform with modulated pulse width such as a modulation type driving signal GATE. A current detecting parts 220 which has an information related to an input voltage Vin in advance controls the power factor by a resistor Rs, allowing the current and voltage waveform to be at the same phase by means of the input voltage even at the time of no field forward. As a result, a high power fatcor near a unit power fatcor of at least 0.99 of the power factor can be obtained through proportional control, resulting in a simplified circuit structure.