Electromagnetic cooking device with automatic melt operation and method of controlling cooking in the electromagnetic cooking device

1. An electromagnetic cooking device comprising:

a cavity in which a food load is placed;

a plurality of RF feeds configured to introduce electromagnetic radiation into the cavity for heating the food load; and

a controller configured to:

(a) measure resonances in the cavity;

(b) generate and store a resonance map resulting from the measured resonances, the resonance map is represented in a frequency/phase domain and includes a plurality of efficiency measurements each taken at different frequencies and phase differences;

(c) conditionally repeat steps (a) and (b) to obtain and store a plurality of resonance maps over time;

(d) detect a melting state of the food load based on variations between any of the measured efficiencies in the stored resonance maps; and

(e) adjust a power level of the electromagnetic radiation in response to detection of the melting state.

2. The electromagnetic cooking device of claim 1 , wherein the food load comprises one of chocolate and butter.

3. The electromagnetic cooking device of claim 1 , wherein steps (a) and (b) are repeated after a predetermined period of time.

4. The electromagnetic cooking device of claim 1 , wherein the controller detects that the food load has melted if the variations between the resonance maps satisfy a threshold condition.

5. The electromagnetic cooking device of claim 4 , wherein the threshold condition is satisfied if a rate of variation over time of the resonances falls below a predetermined threshold.

6. The electromagnetic cooking device of claim 4 , wherein step (e) comprises stopping the heating of the food load if the threshold condition is satisfied.

7. The electromagnetic cooking device of claim 1 , wherein the controller outputs a notification upon detection of the heating state.

8. A method of controlling cooking in an electromagnetic cooking device, the electromagnetic cooking device having a cavity in which a food load is placed and a plurality of RF feeds configured to introduce electromagnetic radiation into the cavity to heat the food load, the method comprising the steps of:

(a) measuring resonances in the cavity;

(b) generating and storing a resonance map resulting from the measured resonances, the resonance map is represented in a frequency/phase domain and includes a plurality of efficiency measurements each taken at different frequencies and phase differences;

(c) analyzing forward and backward power at the plurality of RF feeds to calculate efficiency;

(d) determining and monitoring a coefficient of variation of the efficiency;

(e) conditionally repeating steps (a) and (b) based at least on one of the passage of time and a change in the coefficient of variation to obtain and store a plurality of resonance maps over time;

(f) detecting a melting state of the food load based on variations between any of the measured efficiencies in the stored resonance maps; and

(g) adjusting a power level of the electromagnetic radiation in response to detection of the melting state.

9. The method of claim 8 , wherein the coefficient of variation is based on a standard deviation and a mean of the efficiency during a predetermined period of time.

10. The method of claim 9 , wherein the coefficient of variation is determined by computing a quotient between the standard deviation and the mean.

11. The method of claim 8 , wherein step (d) comprises detecting that the food load has melted if the variations between the resonance maps satisfy a threshold condition.

12. The method of claim 11 , wherein the threshold condition is satisfied if a rate of variation over time of the resonances falls below a predetermined threshold.

13. The method of claim 11 , wherein step (e) comprises stopping the heating of the food load if the threshold condition is satisfied or a predefined amount of energy has been applied to the food load.

14. The method of claim 8 , further comprising the step of outputting a notification upon detection of the melting state.

15. A method of controlling cooking in an electromagnetic cooking device, the electromagnetic cooking device having a cavity in which a food load is placed and a plurality of RF feeds configured to introduce electromagnetic radiation into the cavity to heat the food load, the method comprising the steps of:

(a) measuring resonances in the cavity;

(b) generating and storing a resonance map resulting from the measured resonances, the resonance map is represented in a frequency/phase domain and includes a plurality of efficiency measurements each taken at different frequencies and phase differences;

(c) conditionally repeating steps (a) and (b) to obtain and store a plurality of resonance maps over time;

(d) detecting a melting state of the food load based on variations between any of the measured efficiencies in the stored resonance maps; and

(e) adjusting a power level of the electromagnetic radiation in response to detection of the melting state.

16. The method of claim 15 , wherein steps (a) and (b) are repeated after a predetermined period of time.

17. The method of claim 16 , wherein step (d) comprises detecting that the food load has melted if the variations between the resonance maps satisfy a threshold condition.

18. The method of claim 17 , wherein the threshold condition is satisfied if a rate of variation over time of the resonances falls below a predetermined threshold.

19. The method of claim 17 , wherein step (e) comprises stopping the heating of the food load if the threshold condition is satisfied.

20. The method of claim 15 , wherein step (e) comprises stopping the heating of the food load if a predefined amount of energy has been applied to the food load.