SWITCHING CONTROL CIRCUIT OF BOOST CONVERTER FOR CONTROLLING SOFT SWITCHING POWER FACTOR

摘要

PURPOSE: A switching control circuit of boost converter for controlling soft switching power factor is provided to reduce a switching loss due to a soft switching on switching each elements. CONSTITUTION: A rectifying part(21) rectifies an input common voltage and output it. A boost converter(22) improves a power factor at the rectified voltage. A soft switching part(23) decreases a loss by doing a soft switching operation. A current detecting part(24) detects currents which flow into the converter. An input voltage detecting part(25) detects voltages which flow into the converter. An output voltage detecting part(26) detects output voltages which generate during a load operation. A power factor control part(10) generates a switching signal for controlling the power factor to be output into the switches of the converter and the switching part. A duty signal determining part(20) changes a frequency duty based on the signal from the control part. An oscillating part(30) receives the output voltage of the duty signal determining part to generate a frequency. A switching period selecting part(40) receives the output signal of the oscillating part to determine driving periods of switching elements. A switching driver(50) receives the output signal of the switching period selecting part to drive the switching elements.