Induction cooker and method of operation

A method for operating an induction heating cooker comprising:

• a top panel for mounting a cooking container;
• a heating coil provided under the top panel, for heating the cooking container by induction;
• an inverter for supplying a high-frequency current to the heating coil;
• an electrode provided on a back surface of the top panel adjacent to a periphery of the heating coil;
• an electrostatic capacitance detecting portion configured to supply a high-frequency signal to the electrode and detect an electrostatic capacitance of the electrode;
• a memory portion configured to store the detected electrostatic capacitance as a reference value;
• a control portion that controls the inverter such that heating output of the inverter reaches a first set value;
• and
• a boiling over detecting portion configured to execute a reference value updating process and store the electrostatic capacitance in the memory portion as a reference value when the electrostatic capacitance of the electrode satisfies a predetermined condition, the method comprising:
• after a predetermined delay time, the boiling over detecting portion further executes an output controlling action to reduce the heating output of the inverter to a predetermined second set value or stops a heating action, when a change amount of the electrostatic capacitance of the electrode with respect to the reference value is equal to or greater than an output reducing threshold value,
• wherein the delay time is the time when the change amount of the electrostatic capacitance with respect to the reference value is equal to or greater than the output reducing threshold value, and does not execute the output controlling action when it is determined that the boiling over is not generated during the delay time, and
• wherein the boiling over detecting portion stops the heating action or reduces the heating output to a third set value lower than the second set value when a change rate of the detected electrostatic capacitance is equal to or greater than a predetermined change rate, and
• returns the heating output to the first set value when the change rate of the detected electrostatic capacitance is less than the predetermined change rate, during a change rate detecting period that includes a time when the change amount of the electrostatic capacitance of the electrode with respect to the reference value is equal to or greater than the output reducing threshold value.