Induction Heating Control Method for Cooking Appliance

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Solution Overview

Problem

Induction heating systems face challenges in accurately estimating the temperature of cooking utensils and food contents, particularly in maintaining constant heating conditions, as existing methods fail to provide quantitative measurements.

Innovation Solution

A control method that estimates the temperature of pots, food thermodynamics, and induction coil temperatures using measured power absorption and temperature information, employing a mathematical model tuned by algorithms like the Extended Kalman Filter to compensate for noise and uncertainties, ensuring reliable temperature monitoring and control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If existing temperature estimation methods are used, then the system can operate, but the temperature estimation accuracy is insufficient for quantitative measurement

Engineering Contradiction:
Improvetemperature estimation accuracyVSAvoidquantitative measurement capability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the estimated temperature is continuously compared with actual temperature measurements, and the model parameters are adjusted based on this feedback to improve estimation accuracy over time

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces direct physical temperature measurement mechanisms with an estimation system based on electrical measurements and mathematical modeling, substituting mechanical/physical sensing with computational approaches

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

2Reliability

If multiple temperature measurements are taken to improve estimation reliability, then the reliability improves, but the device complexity and measurement system becomes more complex

Engineering Contradiction:
Improveestimation reliabilityVSAvoidmeasurement system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes existing temperature sensors serve multiple functions: they not only monitor their local temperature but also provide data for estimating temperatures at other locations through the mathematical model, reducing the need for additional sensors

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent introduces a mathematical model as an intermediary that connects limited temperature measurements with the temperatures of interest, allowing estimation of pot and food temperatures from coil and surface temperature measurements

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If the system monitors multiple parameters (power, temperature, mass) to improve cooking control, then the cooking phase control improves, but the computational complexity and processing requirements increase

Engineering Contradiction:
Improvecooking phase controlVSAvoidcomputational complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent performs preliminary calculations by pre-establishing mathematical models and relationships between parameters, so that during operation only simple parameter updates and comparisons are needed rather than complex real-time computations

Inventive Principle:
Principle #10Preliminary action

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 method effectively monitors and controls cooking temperatures and phases, prevents coil damage, and compensates for noise factors, improving induction cooktop performance by providing accurate temperature and mass estimations.

Implementation Method 1

an induction heating system of a cooktop provided with an induction coil

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the induction heating systems it is almost impossible to make a distinction between the heating element, on one side, and the cooking utensil, on the other side, since the cooking utensil itself is an active part of the heating process

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Implementation Method 3

the induction heating systems it is almost impossible to make a distinction between the heating element, on one side, and the cooking utensil, on the other side, since the cooking utensil itself is an active part of the heating process

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2194756B1A method for controlling the induction heating system of a cooking appliance
Publication Date: 2016.07.27 WHIRLPOOL CORP
  • EP2194756B1 patent drawingFigure 1~2
  • EP2194756B1 patent drawingFigure 3~4
  • EP2194756B1 patent drawingFigure 5~6

AI summary

A method for controlling an inductive heating system of a cooking hob provided with an induction coil, particularly for controlling it in connection with a predetermined working condition, comprises assessing the value of power absorbed by the system, measuring a temperature indicative of the thermal status of at least one element of the heating system, feeding the assessed power value to a computing model capable of providing an estimated value of temperature, comparing the measured temperature with the estimated temperature and tuning the computing model on the basis of such comparison.