Multi-Channel RF Cooking Phase Control for Uniform Heating

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Solution Overview

Problem

Conventional microwave ovens using a single, non-coherent magnetron source for electromagnetic cooking result in non-uniform heating of food due to the lack of control over electromagnetic energy distribution, leading to inefficient cooking processes.

Innovation Solution

A solid-state radio frequency (RF) cooking system with multiple RF feeds that can independently control the phase, frequency, and amplitude of electromagnetic waves, creating coherent wave patterns within the cooking cavity to ensure uniform heating by maintaining a stationary interference pattern.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single magnetron source is used to generate microwaves, then the device complexity is reduced, but the heating uniformity deteriorates

Engineering Contradiction:
Improvesource configurationVSAvoidheating uniformity
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The single magnetron source is segmented into multiple independent RF channels, each with its own phase control. This allows the electromagnetic energy to be distributed more uniformly throughout the cooking cavity by controlling the phase of each channel independently, thereby improving heating uniformity while maintaining manageable system complexity through modular architecture

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention adds the phase dimension to the traditional amplitude-only control of microwave sources. By introducing phase modulation capability to multiple RF channels, the system creates a new degree of freedom for controlling electromagnetic energy distribution, enabling uniform heating patterns without requiring proportional increases in physical complexity

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If mechanical stirrers and turntables are added to improve heating uniformity, then the heating uniformity is improved, but the device complexity and mechanical failure risk increase

Engineering Contradiction:
Improveheating uniformityVSAvoidmechanical components
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention replaces mechanical stirring and rotation systems with an electronic phase control system. By modulating the phase of multiple RF channels, the system creates stationary interference patterns that achieve uniform heating without any moving parts, thereby eliminating mechanical complexity and associated failure modes while maintaining heating uniformity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If a magnetron-based microwave source is used, then the ease of manufacture is improved, but the adaptability and tunability deteriorate

Engineering Contradiction:
Improvesource implementationVSAvoidfrequency tunability
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The invention transitions from fixed-frequency magnetron operation to tunable solid-state RF amplifiers with programmable phase control. This allows the system to adapt to different cooking requirements, frequencies, and power levels by changing operational parameters through software control, significantly improving adaptability while maintaining ease of manufacture through standardized solid-state components

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system achieves uniform and efficient heating by controlling the electromagnetic energy distribution, maximizing the coupling of RF power with the food and allowing for precise adjustment of cooking parameters, resulting in improved cooking consistency and efficiency.

Implementation Method 1

each high-power radio frequency amplifier including at least one amplifying component configured to output a periodic signal that is amplified in power with respect to an input radio frequency common reference signal

Methodology Applied
Scientific EffectElectromagnetic amplification: Electromagnetic Induction

Implementation Method 2

a phase-shifting component configured to modulate the phase of the output periodic signal with respect to the input radio frequency signal

Methodology Applied
Scientific EffectPhase modulation: Phase Modulation

Implementation Method 3

A conventional microwave oven cooks food by a process of dielectric heating in which a high-frequency alternating electromagnetic field is distributed throughout an enclosed cavity. Microwave frequencies at or around 2.45 GHz cause dielectric heating primarily by absorption of energy in water

Methodology Applied
Scientific EffectDielectric heating: Dielectric Heating

Implementation Method 4

creating coherent wave patterns within the cooking cavity to ensure uniform heating by maintaining a stationary interference pattern

Methodology Applied
Scientific EffectElectromagnetic interference: Interference

Data Source

PatentEP3516927B1Method and system for radio frequency electromagnetic energy delivery
Publication Date: 2021.05.26 WHIRLPOOL CORP
  • EP3516927B1 patent drawingFigure 1
  • EP3516927B1 patent drawingFigure 2
  • EP3516927B1 patent drawingFigure 3

AI summary

An electromagnetic energy delivery system includes a set of radio frequency channels. Each channel includes a radio frequency feed, at least one high-power amplifier and a phase-shifting component. Each high-power radio frequency amplifier includes at least one amplifying component configured to output a periodic signal that is amplified in power with respect to an input radio frequency common reference signal. The phase-shifting component is configured to modulate the phase of the output periodic signal with respect to the input radio frequency signal. A controller coupled to the set of radio frequency channels can be configured to cause the output periodic signals from each of the radio frequency channels is to have a time-varying phase difference relative to the common reference signal and a phase difference relative to the other output periodic signals that is constant when averaged over time.