High frequency converting the frequency modulation control mannered null direct current

摘要

PROBLEM TO BE SOLVED: To provide a frequency modulation control method in an induction heating apparatus capable of positively preventing resonance of a steel plate even when a rated output of an induction heating coil is increased or the steel plate becomes thin and wide.;SOLUTION: Power supply to the induction heating coil 1 is maintained constant by connecting a power constant control circuit 10 including a phase controller 12 to an inverter 3 raising a frequency of a direct current and supplying high-frequency power to the induction heating coil 1. A direct current voltage supplied to the inverter 3 is fluctuated by a vibration generator 13. As a result, the frequency supplied to the induction heating coil 1 is automatically fluctuated and the resonance of the steel plate can be positively prevented. In the invention of the claim 2, a similar result is obtained by fluctuating an output side voltage of the inverter 3.;COPYRIGHT: (C)2004,JPO