Induction Cooktop Coil Current Sensing for Vessel Detection

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Solution Overview

Problem

Induction heat cooking apparatuses face challenges in automatically determining whether a cooking vessel is present, leading to inefficient energy use and user confusion regarding burner controls.

Innovation Solution

The apparatus includes a power supply, rectifier, switching units, a comparison unit, and a controller that alternately applies DC voltage to the working coil, senses current, and outputs pulses to determine if a cooking vessel is present based on predetermined reference values, thereby controlling current flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the induction heat cooking apparatus operates without automatic vessel detection, then the device complexity is reduced, but energy is wasted when no cooking vessel is present

Engineering Contradiction:
Improveenergy consumptionVSAvoiddetection system complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical or sensor-based detection systems with an electrical measurement approach. By measuring the current flowing through the working coil and comparing it to a predetermined reference value, the system determines vessel presence without requiring additional mechanical sensors or complex detection mechanisms. This substitution of electrical measurement for mechanical detection reduces device complexity while preventing energy waste.

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

Solution Approach 2:

The working coil itself serves dual purposes: it both heats the cooking vessel and provides the measurement signal for detecting vessel presence. The current flowing through the coil during normal operation contains information about vessel presence, eliminating the need for separate detection systems. This self-service approach allows the existing heating component to perform detection functions, reducing overall system complexity.

Inventive Principle:
Principle #25Self-service

2Ease of operation

If the induction heat cooking apparatus lacks vessel presence detection, then the device complexity is minimized, but user confusion regarding burner controls increases

Engineering Contradiction:
Improveuser interface clarityVSAvoidcontrol system complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces complex user interface elements or separate detection indicators with simple current measurement and comparison. The control system determines vessel presence by comparing measured current against a reference value, providing clear feedback for burner activation without requiring complex display systems or multiple control elements. This electrical measurement approach simplifies both the control system and user interface.

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

Solution Approach 2:

The current measurement system serves multiple functions: it monitors the heating operation and simultaneously determines vessel presence for control decisions. By making the control system multi-functional, the patent improves ease of operation without adding separate detection systems or increasing overall complexity. The same electrical measurement used for power control also provides vessel presence information.

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

3Measurement precision

If the induction heat cooking apparatus uses simple current threshold comparison, then the device complexity is reduced, but the precision of vessel detection may be insufficient

Engineering Contradiction:
Improvevessel detection accuracyVSAvoidcomparison system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex signal processing or multiple-sensor fusion systems with a simple electrical current comparison. By measuring the RMS value of the current flowing through the working coil and comparing it to a predetermined reference value, the system achieves reliable vessel detection without requiring complex processing algorithms or additional sensors. This electrical measurement and comparison approach provides sufficient precision while maintaining low device complexity.

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

This solution allows for accurate detection of a cooking vessel's presence, optimizing energy use by preventing unnecessary heating and enhancing user convenience by activating the correct burner switch.

Implementation Method 1

a rectifier configured to rectify the supplied AC voltage into a direct current (DC) voltage

Methodology Applied
Scientific EffectRectification: Diode

Implementation Method 2

When high-frequency current flows in the working coil or the heating coil, strong lines of magnetic force are generated

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

The lines of magnetic force generated in the working coil or the heating coil generate eddy current upon passing through a cooking vessel. Accordingly, heat is generated in the cooking vessel according to flow of Eddy current

Methodology Applied
Scientific EffectEddy current: Eddy Currents

Data Source

PatentEP3439429B1Induction heat cooking apparatus and operating method thereof
Publication Date: 2022.02.16 LG ELECTRONICS INC
  • EP3439429B1 patent drawingFigure 1~2
  • EP3439429B1 patent drawingFigure 3~4
  • EP3439429B1 patent drawingFigure 5

AI summary

Disclosed herein is an induction heat cooking apparatus including a power supply configured to supply an alternating current (AC) voltage, a rectifier configured to rectify the supplied AC voltage into a direct current (DC) voltage, first and second switching units configured to control switching such that the DC voltage from the rectifier is alternately applied to a working coil, a comparison unit configured to sense current flowing in the working coil and to compare the sensed current with a predetermined reference value to output pulses, and a controller configured to determine whether a cooking vessel is present on the working coil based on the output pulses.