Planar Coil Switching in Induction Cooktops for Uniform Heating

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Solution Overview

Problem

Induction heating cooktops face issues with non-uniform heating of cooking vessels made of different materials and an increase in volume due to the use of multiple heating coils with varying outer diameters or two-layer structures.

Innovation Solution

The cooktop features a coil switching structure with a plurality of working coils alternately wound on the same plane, allowing selective current supply based on vessel material to achieve uniform heating and minimize volume increase.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple heating coils with different outer diameters or two-layer structures are used to heat both magnetic and non-magnetic vessels, then output efficiency for various materials is improved, but temperature non-uniformity occurs at the bottom portion of the heated body and device volume increases

Engineering Contradiction:
Improveoutput efficiencyVSAvoidtemperature non-uniformity
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The heating system is divided into multiple independent heating coils (first heating coil and second heating coil) that can be selectively activated. Each coil is designed with specific characteristics suitable for different vessel types, allowing the system to segment its heating function to match the thermal requirements of magnetic versus non-magnetic vessels.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically selects which heating coil to activate based on the detected vessel material. The control unit switches between the first heating coil (optimized for magnetic vessels) and the second heating coil (optimized for non-magnetic vessels), creating a dynamic adaptation mechanism that maintains temperature uniformity across different material types.

Inventive Principle:
Principle #15Dynamics

2Productivity

If multiple heating coils with different outer diameters or two-layer structures are used to heat both magnetic and non-magnetic vessels, then output efficiency for various materials is improved, but device volume increases

Engineering Contradiction:
Improveoutput efficiencyVSAvoidcooktop volume
Core Design Contradiction:
ProductivityVSVolume of stationary object

Solution Approach 1:

The patent transitions from a vertical two-layer coil arrangement to a horizontal planar arrangement where multiple coils are positioned side-by-side on the same plane. This dimensional change allows multiple heating zones to coexist without increasing the vertical profile, thereby maintaining a compact cooktop volume while supporting multiple vessel types.

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

Solution Approach 2:

The control unit is designed with multi-functionality to detect vessel material properties and automatically select the appropriate heating coil configuration. This universal control mechanism enables a single cooktop design to serve both magnetic and non-magnetic vessels effectively, eliminating the need for separate specialized appliances.

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

3Productivity

If phase difference of current flowing through multiple heating coils is controlled according to vessel material, then output efficiency for both magnetic and non-magnetic vessels is improved, but device complexity increases

Engineering Contradiction:
Improveoutput efficiencyVSAvoidcoil switching structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The system changes the electrical parameter (current phase difference) based on vessel material detection. By adjusting the phase relationship between currents in different coils or selecting different coil configurations, the system optimizes heating efficiency for magnetic vessels versus non-magnetic vessels without requiring complex mechanical adjustments.

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

This design maintains output efficiency for various materials, ensures uniform heating of the cooking vessel's bottom surface, and reduces the overall size of the cooktop.

Implementation Method 1

a working coil module configured to generate magnetic fields so as to heat the cooking vessel

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

generate magnetic fields so as to heat the cooking vessel

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Data Source

PatentEP4723805A2Induction heating cooktop
Publication Date: 2026.04.08 LG ELECTRONICS INC
  • EP4723805A2 patent drawingFigure 1
  • EP4723805A2 patent drawingFigure 2
  • EP4723805A2 patent drawingFigure 3

AI summary

The present disclosure relates to an induction heating cooktop comprising: a glass top plate on which a cooking vessel is placed; a working coil module which generates a magnetic field so as to heat the cooking vessel; and an inverter which is operated to allow a current to flow through the working coil module, wherein the working coil module comprises: a first working coil wound to form a plurality of turns; and a second working coil wound between the turns of the first working coil.