Induction Coil Coverage Control for Stray Field Management
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Solution Overview
Problem
Inductive surface hobs with under-covered induction coils generate stray electromagnetic fields, leading to unintended heating of non-ferromagnetic utensil parts and interference with temperature sensors, resulting in inaccurate temperature control and potential user safety issues.
Innovation Solution
A method to determine the coil coverage of each induction coil under a cooking utensil and adjust power accordingly, either reducing or ceasing operation of under-covered coils to minimize stray fields and ensure accurate temperature sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fewer but larger induction coils are used to reduce manufacturing costs, then manufacturing cost is reduced, but coil coverage decreases leading to increased stray fields and sensor interference
Solution Approach 1:
The patent applies dynamics by making the coil power operation adjustable and adaptive. The control system dynamically modifies the power output of individual induction coils based on real-time sensor feedback, transitioning from static full-power operation to dynamic controlled operation. This allows the system to reduce power on coils causing stray field issues while maintaining cooking performance where needed.
Solution Approach 2:
The patent implements feedback by using temperature sensors on the cooktop surface to detect abnormal heating patterns caused by stray fields. The control system receives this sensor information and adjusts coil power accordingly, creating a closed-loop control system that continuously monitors and corrects stray field heating and sensor interference issues.
2Object-affected harmful factors
If multiple small induction coils are used to improve coil coverage, then stray field heating is reduced, but manufacturing cost increases
Solution Approach 1:
The patent applies parameter changes by modifying the power output parameter of induction coils based on their coverage characteristics. Instead of changing the physical size or number of coils, the system adjusts the electrical power parameter dynamically, allowing larger coils to operate at reduced power when coverage is insufficient, thereby avoiding stray field issues without requiring more coils.
3Productivity
If induction coils operate at full power to maintain cooking performance, then cooking efficiency is maintained, but temperature sensor accuracy deteriorates due to stray field interference
Solution Approach 1:
The patent uses feedback from temperature sensors to detect when stray field interference is affecting measurement accuracy. The control system receives temperature data, identifies abnormal readings caused by electromagnetic interference, and adjusts coil power to eliminate the interference while maintaining cooking performance through compensatory heating from other coils.
Solution Approach 2:
The patent applies preliminary anti-action by proactively reducing coil power when sensor interference is detected, preventing further degradation of temperature measurement accuracy. The control system takes corrective action before the interference can significantly impact cooking control or safety.
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
Reduces stray field heating and sensor interference, maintaining accurate temperature control and user safety by optimizing power distribution across the cooking zone.
Implementation Method 1
an inductive surface cooking surface (1) with a plurality of induction coils (11)
Implementation Method 2
the induction coils (11) located beneath the position can be assigned to the cookware. The induction coils can then be operated by the inductive surface hob or its control system at the desired power, thus jointly forming the cooking zone for the cookware
Implementation Method 3
This also includes installing sensors on or in the cooking utensils, for example, to detect the temperature of the food being cooked and transmit this sensor information, particularly wirelessly, to external devices such as the hob or its control unit
Data Source
Figure 1~2
AI summary
The invention relates to a method for operating an inductive cooking system (1, 2), wherein the cooking system (1, 2) comprises an inductive surface cooktop (1) with a plurality of induction coils (11) and at least one cooking vessel (2) arranged on the inductive surface cooktop (1), the method comprising at least the steps of: • Determining (400) the coil coverage of each induction coil (11) located below the cooking vessel (2), • Comparing (500) the coil coverage of each induction coil (11) located below the cooking vessel (2) with a predetermined limit value, and, • if the coil coverage of an induction coil (11) located below the cooking vessel (2) falls below the limit value, • Operating (600) this induction coil (11) at a predetermined reduced power or • Not operating (700) this induction coil (11).