Abstract: A method for operating an induction cooktop having multiple induction heating coils includes monitoring a characteristic of the heating coils indicative of audible noise generated by simultaneous operation of multiple induction heating coils. Upon indication of audible noise from the monitored characteristic, an operating characteristic of at least one of the induction heating coils is varied so as to change the audible noise into a pre-defined, stored audible noise pattern that is desirous to a consumer or user of the cooktop.

Abstract: Systems and methods for detecting vessel presence and circuit resonance for an induction heating apparatus are disclosed. A detector circuit generates an output signal based on a feedback signal corresponding to a signal, such as current, flowing through an induction heating coil. The output signal has a duty cycle corresponding to the proximity of operating frequency of the induction heating apparatus to resonance. Changes in the duty cycle of the output signal can be monitored to determine the presence or absence of a vessel on the induction heating coil.