# US 10,772,165 B2 · System and method for zone cooking according to spectromodal theory in an electromagnetic cooking device

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- Number: US 10,772,165 B2
- Document ID: US10772165B2
- Status: Granted
- Kind: B2
- Application number: 15/910,340
- Filed: 2018-03-02
- Published: 2019-09-05
- Granted: 2020-09-08
- Earliest claimed: 2018-03-02
- Assignees: Whirlpool Corporation
- Applicants: Whirlpool Corporation
- Inventors: Davide Guatta; Mattia Rigo
- Web page: https://patentgrep.com/patent/US10772165B2

## CPC

- H05B 6/686: {Circuits comprising a signal generator and power amplifier, e.g. using solid state oscillators}
- H05B 6/50: for monitoring or control
- H05B 6/52: Feed lines
- H05B 6/645: {using temperature sensors}
- H05B 6/664: {Aspects related to the power supply of the microwave heating apparatus}
- H05B 6/687: {for cooking}
- H05B 6/705: {using microwave tuning}
- H05B 6/707: {using waveguides}
- H05B 6/745: {Rotatable stirrers}
- Y02B 40/00: Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

An electromagnetic cooking device and cooking method to perform zone cooking is disclosed. The method includes scanning a resonant cavity in which a food load has been placed with RF feeds that are coupled to respective high power amplifiers; identifying resonant frequencies and corresponding phases of the RF feeds; storing a resonance map; classifying symmetries in the resonant map; determining paths defining stirring routes between poles of different symmetries; determining midpoints in the paths with a maximum unbalance between reflected powers of the respective high power amplifiers; classifying the unbalance in terms of power steered to the left and right sides of the food load; synthesizing a heating strategy for zone cooking using the classified unbalance; and implementing the heating strategy by causing the plurality of high power amplifiers and RF feeds to introduce electromagnetic radiation at specific selected frequencies and phases into the cavity based on the heating strategy.

## Claims

### Claim 1

A method for controlling a heating distribution of an electromagnetic cooking device comprising:
scanning a resonant cavity of the cooking device in which a food load has been placed with a plurality of radio frequency (RF) feeds that are coupled to a plurality of respective high power amplifiers;
based on the scanning, identifying a plurality of resonant frequencies and corresponding phases of the RF feeds;
creating and storing a resonance map in the frequency phase domain;
classifying symmetries in the resonant map;
determining paths defining stirring routes between poles of different symmetries;
determining midpoints in the paths with a maximum unbalance between reflected powers of the plurality of respective high power amplifiers;
classifying the unbalance in terms of power steered to a first side of the food load with respect to power steered to a second side of the food load;
synthesizing a heating strategy for zone cooking using the classified unbalance; and
implementing the heating strategy by causing the plurality of high power amplifiers and RF feeds to introduce electromagnetic radiation at specific frequencies and phases into the cavity, wherein the specific frequencies and phases are selected in accordance with the heating strategy.

### Claim 2 (depends on 1)

The method according to claim 1, wherein information used for classifying the unbalance may be pre-stored in a look-up table (LUT) and recalled using at least one of: a recipe; a computational electromagnetic engine; and an IR sensor testing of at least one of two asymmetric paths.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the electromagnetic radiation introduced into the cavity is incrementally changed according to the stirring routes.

### Claim 4 (depends on 3)

The method according to claim 3, wherein the incremental change of the electromagnetic radiation achieves a smooth change in the plurality of RF feeds thereby smoothly changing a heating pattern of the resonant chamber over time.

### Claim 5 (depends on 1)

The method according to claim 1, wherein a rate of change of the electromagnetic radiation introduced into the cavity along the stirring routes is controlled.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the first side of the food load is the right side and the second side of the food load is the left side.

### Claim 7 (depends on 1)

The method according to claim 1, further comprising providing a measurement device in configured to measure a plurality of reflected signals from the RF feeds.

### Claim 8 (depends on 7)

The method according to claim 7, further comprising:
measuring an efficiency of the plurality of reflected signals with the measurement device.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the resonant modes identify the frequency and phase of coordinates of end points wherein the stirring route includes coordinate points between the end points.

### Claim 10 (depends on 9)

The method according claim 9, wherein the coordinates correspond to points of the resonant modes in the frequency and phase domain.

### Claim 11

An electromagnetic cooking device comprising:
an enclosed cavity configured to receive a food load;
a plurality of high power amplifiers configured to amplify a first radio frequency (RF) signal and a second RF signal thereby supplying the RF signals to the enclosed cavity;
a plurality of RF feeds for receiving the RF signals from the plurality of high power amplifiers to introduce electromagnetic radiation corresponding to the RF signals into the enclosed cavity; and
a controller in communication with the plurality of amplifiers, the controller configured to:
scan the enclosed cavity with using the plurality of RF feeds;
based on the scan, identify a plurality of resonant frequencies and corresponding phases of the RF feeds;
create and store a resonance map in the frequency phase domain;
classify symmetries in the resonant map;
determine paths defining stirring routes between poles of different symmetries;
determine midpoints in the paths with a maximum unbalance between reflected powers of the plurality of respective high power amplifiers;
classify the unbalance in terms of power steered to a first side of the food load with respect to power steered to a second side of the food load;
synthesize a heating strategy for zone cooking using the classified unbalance; and
implement the heating strategy by causing the plurality of high power amplifiers and RF feeds to introduce the electromagnetic radiation at specific frequencies and phases into the cavity, wherein the specific frequencies and phases are selected in accordance with the heating strategy.

### Claim 12 (depends on 11)

The electromagnetic cooking device according to claim 11, wherein information used by the controller for classifying the unbalance may be pre-stored in a look-up table (LUT) and recalled using at least one of: a recipe; a computational electromagnetic engine; and an IR sensor testing of at least one of two asymmetric paths.

### Claim 13 (depends on 11)

The electromagnetic cooking device according to claim 11, further comprising:
a measurement device in communication with the controller, wherein the measurement device is configured to measure a plurality of reflected signals from the RF feeds.

### Claim 14 (depends on 13)

The electromagnetic cooking device according to claim 13, wherein the controller is further configured to:
measure an efficiency of the plurality of reflected signals with the measurement device.

### Claim 15 (depends on 14)

The electromagnetic cooking device according to claim 14, wherein based on the efficiency, the controller is further configured to identify a plurality of resonance frequencies.

### Claim 16 (depends on 15)

The electromagnetic cooking device according to claim 15, wherein the controller is further configured to select the resonant modes based on the plurality of resonance frequencies.

### Claim 17 (depends on 11)

The electromagnetic cooking device according to claim 11, wherein the resonant modes identify the frequency and phase of coordinates of the stirring route.

### Claim 18 (depends on 17)

The electromagnetic cooking device according to claim 17, wherein the coordinates correspond to points of the resonant modes in the frequency and phase domain.

### Claim 19

An electromagnetic cooking device comprising:
an enclosed cavity configured to receive a food load;
a plurality of high power amplifiers configured to amplify a first RF signal and a second radio frequency (RF) signal thereby supplying the RF signals to the enclosed cavity;
a plurality of RF feeds for receiving the RF signals from the plurality of high power amplifiers to introduce electromagnetic radiation corresponding to the RF signals into the enclosed cavity; and
a controller in communication with the plurality of amplifiers, the controller configured to:
scan the enclosed cavity using the plurality of RF feeds;
based on the scan, identify a plurality of resonant frequencies and corresponding phases of the RF feeds;
create and store a resonance map in the frequency phase domain;
classify symmetries in the resonant map;
determine paths defining stirring routes between poles of different symmetries;
determine midpoints in the paths with a maximum unbalance between reflected powers of the plurality of respective high power amplifiers;
classify the unbalance in terms of power steered to a first side of the food load with respect to power steered to a second side of the food load, wherein information used for classifying the unbalance may be pre-stored in a look-up table and recalled using at least one of: a recipe; a computational electromagnetic engine; and an IR sensor testing of at least one of two asymmetric paths;
synthesize a heating strategy for zone cooking using the classified unbalance; and
implement the heating strategy by causing the plurality of high power amplifiers and RF feeds to introduce the electromagnetic radiation at specific frequencies and phases into the cavity, wherein the specific frequencies and phases are selected in accordance with the heating strategy.

### Claim 20 (depends on 19)

The electromagnetic cooking device according to claim 19, further comprising:
a measurement device in communication with the controller, wherein the measurement device is configured to measure a plurality of reflected signals from the RF feeds.