Patent ID: 8796602

Claim:
An induction heating device comprising: a resonance circuit having a resonance frequency comprising: a heating coil magnetically coupling a load and having a fixed number of turns; and a resonant capacitor having a fixed capacitance; an inverter that includes switching elements forming a full-bridge circuit, and supplies electric power to the resonance circuit; a heating output controller for driving the switching elements and controlling heating output of the heating coil; a rectifier for rectifying a commercial alternating current; a power factor improvement part for boosting rectified output from the rectifier, supplying an output voltage to the inverter, and improving a power factor of the commercial alternating current; and a load material detector for detecting a level of conductivity and a level of magnetic permeability of a material of the load, wherein the heating output controller switches a drive frequency of the switching elements between a first frequency corresponding to a frequency equal to the resonance frequency of the resonance circuit and a second frequency corresponding to 1/n times the resonance frequency of the resonance circuit (n being an integer greater than or equal to two) according to the level of conductivity and the level of magnetic permeability of the load material detector, and the power factor improvement part changes a magnitude of the output voltage supplied to the inverter according to the level of conductivity and the level of magnetic permeability determined by the load material detector.