Induction Heating Noise Compensation via Band-Pass Filtering

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Solution Overview

Problem

Existing induction heating systems face challenges in robustly monitoring and controlling the temperature of cooking vessels due to disturbances such as mains voltage variations, electrical measurement noises, and cooking vessel movements, which compromise the correlation between electrical parameters and temperature, leading to decreased performance and potential system failures.

Innovation Solution

A method involving a noise detection step using a band-pass filter to distinguish noise from actual temperature-related electrical magnitudes, followed by a compensation filter that generates a noise-compensated output signal, ensuring robust control even in the presence of disturbances like pot mismatching and line voltage fluctuations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If electrical parameters are monitored to control temperature, then control capability is achieved, but measurement precision deteriorates due to noise from voltage variations and vessel movements

Engineering Contradiction:
Improvetemperature control capabilityVSAvoidtemperature monitoring accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent segments the control approach by separating temperature control (via electrical parameter monitoring) from temperature measurement (via thermocouple). This allows the system to maintain control capability while obtaining accurate temperature readings independently, resolving the contradiction between control ease and measurement precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a thermocouple as an intermediary device for temperature measurement. This mediator provides accurate temperature data without being affected by the electrical noise that plagues the electrical parameter-based monitoring, thus improving measurement precision while maintaining the existing control capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If additional temperature sensors are added to improve measurement accuracy, then measurement precision improves, but device complexity increases

Engineering Contradiction:
Improvetemperature measurement accuracyVSAvoidsystem structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses a thermocouple as a simple intermediary temperature sensing element that integrates easily into the existing system. This provides accurate temperature measurement without requiring complex sensor arrays or sophisticated measurement circuits, thus improving precision while minimizing complexity increase.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces complex electrical parameter-based temperature measurement with a simple thermal contact method using a thermocouple. This substitution of measurement principle achieves higher accuracy without the complexity of electrical noise filtering and processing required by the original electrical monitoring approach.

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

3Measurement precision

If noise filtering is applied to electrical signals, then measurement precision improves, but response speed deteriorates due to filtering delays

Engineering Contradiction:
Improvesignal accuracyVSAvoidresponse time
Core Design Contradiction:
Measurement precisionVSSpeed

Solution Approach 1:

The patent introduces a thermocouple as an intermediary that directly measures temperature without being subject to electrical noise or filtering requirements. This provides accurate temperature data in real-time without the delays inherent in electrical signal filtering, thus improving precision without sacrificing response speed.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces electrical signal-based temperature measurement (requiring filtering) with direct thermal measurement using a thermocouple. This substitution eliminates the need for noise filtering operations, providing both high precision and fast response simultaneously.

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

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 enhances the robustness of temperature control and monitoring functions by isolating and compensating for noise, allowing for accurate detection of boiling points and preventing system failures, even under real-world conditions with common disturbances.

Implementation Method 1

A method involving a noise detection step using a band-pass filter to distinguish noise from actual temperature-related electrical magnitudes

Methodology Applied
Scientific EffectBand-pass filtering: Filter (electronic)

Implementation Method 2

followed by a compensation filter that generates a noise-compensated output signal

Methodology Applied
Scientific EffectSignal filtering and compensation: Filter (electronic)

Implementation Method 3

The basic structure of an induction heating system consists indeed of a power converter connected to an induction coil

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 4

induction heating systems for domestic and professional kitchen

Methodology Applied
Scientific EffectInduction heating: Induction Heating

Data Source

PatentEP2296435B1Method for detecting and compensating noises in induction heating systems for domestic and professional kitchen and induction heating system using such method
Publication Date: 2015.05.06 WHIRLPOOL CORP
  • EP2296435B1 patent drawingFigure 1~2
  • EP2296435B1 patent drawingFigure 3~4
  • EP2296435B1 patent drawingFigure 5~7

AI summary

A method for detecting and compensating the effects of disturbances in controlling induction heating systems comprises monitoring the temperature of the cooking vessel or its content on the basis of at least one electrical measurement correlated to said temperature. An analysis in time and/or frequency domain of said electrical measurement is carried out in order to detect and compensate the effect of cooking vessel movements and/or mains line voltage fluctuation or similar electrical noises.