Electromagnetic induction heating apparatus capable of preventing undesirable states of cooking utensils or vessels

An electromagnetic induction heating apparatus capable of preventing undesirable states of cooking utensils or vessels, said apparatus comprising:

• a top plate for placing an object to be heated such as a cooking utensil or vessel thereon;
• inverter means having a resonating circuit comprising an induction heating coil arranged below said top plate and a resonating capacitor connected to said coil, and an inverter circuit for supplying high-frequency power to said resonating circuit in order to generate a high-frequency magnetic field from said induction heating coil and to induce an eddy current in said object to be heated;
• inverter power level control data generating means for outputting inverter power level control data according to a variation of the repulsion force acting on said object as a function of the high-frequency power from said inverter circuit, the inverter power level control data being data for controlling the level of the high-frequency power from said inverter circuit so as to prevent said object to be heated from floating over a placing surface of said top plate due to the repulsion force;
• and
• control means for feeding back the inverter power level control data from said control data generating means to said inverter circuit;
• wherein said inverter power level control data generating means comprises:
• power variation means, connected to said inverter means, for changing the high-frequency power from low power to high power during a predetermined operation period;
• resonating frequency detecting means, connected to said resonating circuit, for separately detecting a resonating frequency of said resonating circuit in a low-power mode and a high-power mode;
• and
• determination means for receiving detection outputs of the resonating frequency in the low-power mode and the high-power mode detected by said resonating frequency detection means and comparing a difference between the detection outputs with a predetermined reference value when said object to be heated is floated from the placing surface of said top plate by the repulsion force, thereby outputting the inverter power level control data in accordance with the comparison result.