Induction Cooking Device Matrix Resonant Circuit Leakage Current Control

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Solution Overview

Problem

Existing induction cooking devices face issues with leakage currents and electromagnetic interference due to the high number of semiconductor switches required to drive multiple induction coils, leading to inefficiencies and increased costs.

Innovation Solution

The induction cooking device employs a configuration with grid diodes connected between row lines and column switches, preventing unwanted current flows and reducing the number of semiconductor switches needed, while using a matrix arrangement of resonant circuit elements to optimize the distribution of oscillating circuits and minimize leakage currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If each induction coil is driven by a semiconductor transistor (quasi-resonant design) or two semiconductor transistors (series resonant circuit), then the induction coils can be controlled individually, but the number of semiconductor switches increases significantly (at least n semiconductors for n induction coils), leading to high costs and increased device complexity

Engineering Contradiction:
Improveindividual coil controlVSAvoidnumber of semiconductor switches
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent divides the control system into row lines and column lines, with resonant circuit elements positioned at intersections. Each row line and column line is controlled by separate semiconductor switches, allowing individual coil control through selective activation of row and column combinations rather than requiring a dedicated switch for each coil.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent merges the control functions by connecting resonant circuit elements to both row lines and column lines simultaneously. The semiconductor switches on row lines and column lines work together to control the current flow to specific coils, combining the control effort and reducing the total number of switches needed compared to individual coil control.

Inventive Principle:
Principle #5Merging (Combining)

2Adaptability or versatility

If multiple semiconductor switches are used to drive multiple induction coils, then individual coil control is achieved, but leakage currents and electromagnetic interference increase due to the high number of switching elements

Engineering Contradiction:
Improveindividual coil controlVSAvoidleakage currents and electromagnetic interference
Core Design Contradiction:
Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the harmful leakage current paths by implementing a configuration where current flows through defined row and column lines with resonant circuit elements at intersections. This structured approach limits current flow to intended paths and reduces unwanted electromagnetic interference compared to systems with numerous independently controlled switches.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The resonant circuit elements act as intermediaries between the row line switches and column line switches. By positioning these elements at the intersections and using them to control current flow, the system reduces direct switching transitions that would generate leakage currents and electromagnetic interference, as the resonant elements naturally limit and shape the current flow.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If a high number of semiconductor switches are used for driving multiple induction coils, then complete control over each coil is achieved, but the cost and device complexity increase significantly

Engineering Contradiction:
Improvecoil control capabilityVSAvoidmanufacturing cost and complexity
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The control system is segmented into row and column control lines, with semiconductor switches distributed along these lines rather than requiring one switch per coil. This segmentation allows the same set of switches to control multiple coils through different row-column combinations, reducing the total switch count and manufacturing complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each semiconductor switch on the row lines and column lines serves multiple functions by controlling current flow to multiple different coils depending on which column or row is activated. A single switch can control current to several different induction coils through different combinations of row and column activations, providing universal control capability with fewer components.

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

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 ensures that only the intended induction coils are excited at any given time, reducing leakage currents and electromagnetic interference, and allows for a more efficient and cost-effective operation by minimizing the number of semiconductor switches required.

Implementation Method 1

induction heating coils, with which pots standing on a hob can be heated

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

resonant (series) resonant circuit and the quasi-resonant parallel resonant circuit

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 3

respective first poles of the connected resonant circuit elements are connected to a respective grid diode, which is connected to the respective second row line end with forward direction to the second row line end

Methodology Applied
Scientific EffectDiode rectification: Diode

Implementation Method 4

resonant circuit elements each having a first pole and a respective second pole... induction heating coils, with which pots standing on a hob can be heated

Methodology Applied
Scientific EffectInduction heating: Induction Heating

Data Source

PatentEP3422815B1Induction cooking device and method for controlling same
Publication Date: 2020.10.21 E G O ELEKTRO GERAETEBAU GMBH
  • EP3422815B1 patent drawingFigure 1
  • EP3422815B1 patent drawingFigure 2
  • EP3422815B1 patent drawingFigure 3

AI summary

The invention relates to an induction cooking device with a plurality of line lines, a plurality of column lines and a plurality of resonant circuit elements, wherein leakage currents are suppressed by a special interconnection of first poles of the resonant circuit elements connected to a line line, at most one respective first pole is directly connected to the respective second line line end.