Induction Heating Inverter Phase Control for Uniform Cooking

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Solution Overview

Problem

Conventional induction heating devices face limitations in flex mode operation due to lack of circuit configuration for reversing or switching current direction, leading to restricted heated regions and inaccurate object detection between working coils, which affects high-output performance and user convenience.

Innovation Solution

An improved induction heating device with a main control unit for individual and coil-set based object detection, and a control signal delivery scheme that allows phase inversion, enabling concurrent operation of multiple working coils at different phases and frequencies, thereby enhancing heating region control and high-power output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If multiple working coils are arranged side by side to operate simultaneously in flex mode, then the heated region coverage is improved, but the heated region becomes concentrated on the edges of the working coils and the object heating is limited to edge regions only

Engineering Contradiction:
Improveheated region coverageVSAvoidheating region distribution uniformity
Core Design Contradiction:
Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent introduces a circuit configuration that allows reversal or switching of current direction to working coils. By inverting the current direction in adjacent working coils, the magnetic field distribution is inverted, which shifts the heated region from edge concentration to more uniform distribution across the entire cooking surface, including central regions between coils.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent implements dynamic control of working coil operation modes, allowing switching between individual coil operation, concurrent operation (flex mode), and inverted concurrent operation. This dynamic adaptability enables the system to optimize heating region distribution based on object position and size, preventing edge concentration and achieving uniform heating across different cooking scenarios.

Inventive Principle:
Principle #15Dynamics

2Device complexity

If object detection is performed individually for each working coil, then the detection process is simple, but the device cannot accurately detect objects located in regions between working coils

Engineering Contradiction:
Improvedetection process complexityVSAvoidobject detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent combines individual coil-based object detection results with coil-set-based detection results. By merging detection data from multiple coils and analyzing the collective response, the system can accurately detect objects located in regions between working coils, overcoming the limitation of individual coil detection while maintaining reasonable system complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent implements a feedback mechanism where detection results from multiple coils are continuously monitored and analyzed. When an object is detected in a region between coils, the system receives feedback from adjacent coils and adjusts the detection algorithm to accurately identify the object's position and enable appropriate flex mode operation.

Inventive Principle:
Principle #23Feedback

3Device complexity

If working coils are controlled with the same phase and frequency in concurrent operation mode, then the circuit control is simple, but the heated region is concentrated on edges and high output performance is limited

Engineering Contradiction:
Improvecircuit control complexityVSAvoidhigh output performance
Core Design Contradiction:
Device complexityVSPower

Solution Approach 1:

The patent allows working coils to operate with inverted phases (180 degrees out of phase) in addition to in-phase operation. By controlling adjacent coils with opposite current directions, the magnetic fields reinforce each other in the regions between coils rather than canceling out, enabling high output performance and uniform heating across the entire cooking surface while maintaining relatively simple circuit control through phase inversion switching.

Inventive Principle:
Principle #13The other way round (Inversion)

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 solution improves object detection accuracy in flex mode, reduces heating time, and increases the precision of heating intensity adjustment, resulting in improved user satisfaction and efficient cooking performance.

Implementation Method 1

when a high-frequency power of a predetermined magnitude is applied to the working coil, an eddy current is generated in the loaded object made of a metal by using a magnetic field generated around the working coil

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

an eddy current is generated inside the bottom of the loaded object. When the resulting eddy current flows in the bottom of the loaded object, the loaded object itself is heated

Methodology Applied
Scientific EffectEddy current: Eddy Currents

Data Source

PatentEP3570635B1Induction heating device having improved control algorithm and circuit structure
Publication Date: 2021.03.31 LG ELECTRONICS INC
  • EP3570635B1 patent drawingFigure 1
  • EP3570635B1 patent drawingFigure 2
  • EP3570635B1 patent drawingFigure 3

AI summary

The present disclosure relates to an induction heating device having an improved control algorithm and an improved circuit structure. In one embodiment of the present disclosure, an induction heating device includes: a first board having, thereon: a first working coil; a first inverter for performing a switching operation to apply a resonant current to the first working coil; and a first control unit configured for controlling an operation of the first inverter; and a second board having, thereon: a second working coil; a second inverter for performing a switching operation to apply a resonant current to the second working coil; and a second control unit configured for controlling an operation of the second inverter, wherein the first control unit is configured for enabling the first and second working coils to operate concurrently at an in-phase or 180-degrees out-of-phase.