VOLTAGE RESONANCE TYPE CONVERTER, INDUCTION HEATING TYPE POWER SUPPLY, FIXING APPARATUS AND START OF THE VOLTAGE RESONANCE TYPE CONVERTER

摘要

PROBLEM TO BE SOLVED: To safely activate a voltage resonance type converter and induction heating type power supply. SOLUTION: Prior to starting, a photocoupler 14 is turned on to turn on a transistor 15 connected in parallel to a filter capacitor 7 in order to reduce a voltage of the filter capacitor 7. When a voltage of the filter capacitor 7 is reduced to about zero, a photocoupler 21 turns off and the voltage drop is detected by a control circuit 18. Depending on this detection, the control circuit 18 supplies a switching pulse to the gate of a switching device 10 and thereby the switching operation can be started smoothly and safely from the point near the zero-cross of the power supply.