Cooking Device Switching Unit for Inverter Power Control

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Solution Overview

Problem

Existing cooking appliances with inverters lack flexibility and efficiency in power management, particularly in interrupting and establishing line paths to efficiently heat multiple cooking elements with a single inverter, leading to inefficiencies and potential flicker issues.

Innovation Solution

A cooking appliance device with a switching unit, comprising at least one bipolar transistor with an insulated gate electrode, that interrupts and establishes a line path during specific time intervals corresponding to half a period of the power grid voltage, allowing for efficient power control and flexible operation of multiple heating elements with a single inverter, while minimizing flicker and ensuring even power delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single inverter supplies power to multiple heating elements through a switch, then cost is reduced and flexibility is improved, but switch service life is reduced due to frequent switching under load

Engineering Contradiction:
ImprovecostVSAvoidswitch service life
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The control device interrupts the line path to the switch before the heating element is activated, and re-establishes it after deactivation. This preliminary action ensures the switch operates only when necessary and under optimal conditions, reducing wear and extending service life while maintaining the cost benefits of using a single inverter for multiple heating elements

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the line path is interrupted during the entire time interval including switch activation, then switch wear is reduced, but heating efficiency is reduced due to current interruption delays

Engineering Contradiction:
Improveswitch service lifeVSAvoidheating efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The line path is interrupted before the heating element is activated and re-established immediately after deactivation. This timing ensures the switch operates under optimal conditions with minimal load stress, extending service life while maintaining heating efficiency by ensuring continuous power availability when needed

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The control device ensures the line path to the heating element remains established continuously during the heating process, interrupting it only briefly before activation and after deactivation. This maintains continuous useful action for heating while minimizing switch wear through strategic timing of interruptions

Inventive Principle:
Principle #20Continuity of useful action

3Adaptability or versatility

If switching occurs at any point in the power grid cycle, then flexibility is maximized, but flicker is generated affecting power quality

Engineering Contradiction:
Improveswitching flexibilityVSAvoidflicker
Core Design Contradiction:
Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The control device is configured to interrupt and re-establish the line path at specific points in the power grid voltage cycle, specifically at the zero-crossing points. This periodic action synchronized with the grid frequency eliminates flicker and maintains power quality while still providing the flexibility to control multiple heating elements through the single inverter system

Inventive Principle:
Principle #19Periodic action

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 achieves high flexibility and efficiency in heating, reduces flicker, and extends the service life of switches by gently managing current flow and compensating for reaction time deviations, resulting in a cost-effective and efficient cooking appliance design.

Implementation Method 1

current flowing through the switch during the cooking process and the current being used to inductively heat a cookware

Methodology Applied
Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Implementation Method 2

the current being used to inductively heat a cookware

Methodology Applied
Scientific EffectInduction Heating: Induction Heating

Data Source

PatentEP2876974B1Cooking device
Publication Date: 2018.01.31 BOSCH SIEMENS HAUSGERATE GMBH
  • EP2876974B1 patent drawingFigure 1
  • EP2876974B1 patent drawingFigure 2a~2b
  • EP2876974B1 patent drawingFigure 3~5

AI summary

The invention relates to a cooking appliance, in particular a cooktop appliance, with at least one switching unit (10) by means of which at least one conductor path can be interrupted and re-established, through which a current generated by a mains voltage flows during at least one operating process and which leads to a first switch (S1), and with at least one control device (14) which, during the operating process, interrupts the conductor path by means of the switching unit (10) for at least one first total time interval (t), and which, during the operating process, causes the conductor path to be re-established immediately before and immediately after the first time interval (t), wherein switching of the first switch (S1) begins and ends during the first time interval (t). To achieve high flexibility and/or efficiency, it is proposed that the first time interval (t) corresponds to at least half a period of the mains voltage.