Whirlpool Corporation
Detecting changes in food load characteristics using Q-factor

Abstract:

An electromagnetic cooking device is provided having a controller and a plurality of RF feeds configured to introduce electromagnetic radiation into an enclosed cavity to heat up a food load. The controller is configured to: select a heating target; generate a heating strategy to determine a sequence of desired heating patterns; cause the RF feeds to output an RF signal to thereby excite the enclosed cavity; monitor the created heating patterns to measure resonances in the enclosed cavity and store a map of efficiency in frequency and phase domains from which the controller identifies resonant modes and Q-factors associated therewith; continue to monitor the created heating patterns and store maps of efficiency in the frequency and phase domains until a specified change is detected in at least one Q-factor; and when the specified change in the at least one Q-factor is identified, stop cooking the food load.