determining a first target frequency of a first working coil corresponding to a first heating area and a second target frequency of a second working coil corresponding to a second heating area;

determining a first final driving frequency of the first working coil and a second final driving frequency of the second working coil based on the first target frequency and the second target frequency;

determining a high-power working coil and a low-power working coil among the first working coil and the second working coil based on the first final driving frequency and the second final driving frequency;

acquiring a temperature value of the high-power working coil, when an absolute value of a difference between the first final driving frequency of the first working coil and the second final driving frequency of the second working coil is equal to or greater than a predetermined noise avoidance value, and when a final driving frequency of the low-power working coil differs from a target frequency of the low-power working coil;

determining whether the temperature value of the high-power working coil satisfies a predetermined output change condition;

setting a required power value of the high-power working coil to a predetermined minimum power value when the temperature value satisfies the predetermined output change condition; and

determining the first final driving frequency of the first working coil and the second final driving frequency of the second working coil again,

wherein the predetermined minimum power value is lower than a power value corresponding to a target frequency of the high-power working coil.