Induction Heating Coil Relay Switching for Inverter Reduction

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Solution Overview

Problem

Induction heating cooking apparatuses face inefficiencies due to the need for a large number of inverters to drive multiple heating coils, increasing manufacturing costs and reducing operational efficiency.

Innovation Solution

The apparatus connects multiple heating coils in series to a smaller number of inverters using relays, allowing only the coil under the vessel to be heated, thereby reducing current flow and inverter ratings, while maintaining efficient heating across various positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the amount of heating coils is increased to maximize heating efficiency and enable free cook zone functionality, then heating coverage and versatility are improved, but the amount of inverters required increases, leading to increased device complexity and manufacturing cost

Engineering Contradiction:

Improveheating coverageVSAvoidinverter quantity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Each inverter is designed to be capable of driving multiple heating coils through relay switching, making the inverter universal rather than dedicated to a single coil. This allows a smaller number of inverters to provide heating coverage for multiple zones by dynamically connecting to different coils based on vessel position detection

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically reconfigures the connection between inverters and heating coils using relays controlled by the control unit. Based on detected vessel position, the control unit activates specific relays to connect the appropriate inverter to the appropriate heating coil, enabling adaptive heating coverage without requiring a fixed one-to-one mapping

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If multiple heating coils are connected to multiple inverters in a one-to-one manner, then each coil can be independently controlled, but the current flowing through each coil and inverter increases, requiring higher rated inverters and increasing manufacturing cost

Engineering Contradiction:

Improveindependent coil controlVSAvoidcurrent rating

Core Design Contradiction:

Ease of operationVSPower

Solution Approach 1:

The heating system is segmented into multiple independent heating coils that can be individually activated. Each coil can be independently controlled through relay switching, allowing the system to divide the total heating load across multiple coils rather than requiring one high-power coil to cover all zones

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple heating coils are electrically connected in series between a single inverter output. This merging of coils in series configuration allows the same inverter to drive multiple coils simultaneously, distributing the current load and reducing the required current rating of the inverter while maintaining independent control capability through relay switching

Inventive Principle:

Principle #5Merging (Combining)

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 configuration reduces manufacturing costs, enhances operational efficiency, and improves stability by allowing a larger number of heating coils to be operated with a minimized number of inverters, ensuring effective heating regardless of vessel position.

Implementation Method 1

An induction heating cooking apparatus is a device for cooking food by using heat generated by eddy current loss and hysteresis loss generated in a cooking vessel (or a cooking container) made of metal when an AC magnetic field is applied to the cooking vessel

Methodology Applied

Scientific EffectEddy current loss: Eddy Currents

Implementation Method 2

Methodology Applied

Scientific EffectHysteresis loss: Magnetic Hysteresis

Implementation Method 3

The induction heating cooking apparatus further includes an inverter serving to apply a high frequency current to the heating coil 12

Methodology Applied

Scientific EffectInversion:

Implementation Method 4

a plurality of relays connecting the one or more heating coils corresponding to the heating regions detected by the control unit and the one or more of the inverters

Methodology Applied

Scientific EffectElectromagnetic actuation: Relay

Data Source

PatentUS9271337B2Induction heating cooking apparatus and control method thereof

Publication Date: 2016.02.23 LG ELECTRONICS INC

AI summary

An induction heating cooking apparatus and a control method thereof are provided. A vessel can be effectively heated by using a plurality of heating coils regardless of a position of the vessel. By connecting a plurality of heating coils to a smaller amount of inverters through relays, only a heating coil on which a vessel is placed, among the plurality of heating coils, can be heated. Also, by connecting the heating coils in series, a current flowing in the heating coil can be lowered, and thus, a rated current of the inverter can be lowered. Also, by connecting relays and heating coils such that a larger amount of heating coils are operated, while minimizing the amount of inverters, manufacturing cost can be reduced, operation efficiency can be increased, and stability of the cooking apparatus can be enhanced.