Inductive Coil Unit Conductive Layers Buoyancy Elimination
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Solution Overview
Problem
Induction heating of pots made from materials with low magnetic permeability, such as aluminum or copper, is inefficient due to low magnetic flux trapping, leading to reduced heating efficiency and the 'buoyancy problem' where pots slide off the cooking surface due to repulsive magnetic forces, especially in full surface induction heating cooking ranges.
Innovation Solution
The use of conductive layers with a periodical structure, comprising segments arranged symmetrically and cut-outs, placed between the coils and pot, which are designed for full surface induction heating and can accommodate different phase differences between coils, reducing buoyancy forces and preventing overheating by optimizing magnetic absorption and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high power is used to heat pots with low magnetic permeability, then heating efficiency is improved, but buoyancy force increases causing pots to slide off the heating surface
Solution Approach 1:
A conductive layer is introduced as an intermediary component between the induction coil and the pot. This conductive layer absorbs excess magnetic flux and reduces the buoyancy force applied to the pot, while still allowing sufficient energy transfer for effective heating. The conductive layer acts as a mediator that decouples the direct interaction between the high-power coil and the pot, enabling high-power operation without the sliding problem.
2Force
If conductive layers are placed between the coil and pot to reduce buoyancy force, then buoyancy problem is reduced, but the conductive layer overheats causing energy loss
Solution Approach 1:
The conductive layer is divided into multiple segments or zones with different properties. This segmentation allows different portions of the conductive layer to handle different functions: some areas are optimized for magnetic flux absorption to reduce buoyancy, while other areas are designed to minimize heating and energy loss. The segmented structure prevents any single area from overheating while maintaining overall effectiveness.
3Force
If conventional conductive layer structures are used in full surface heaters, then buoyancy is reduced at specific burner locations, but the effect is not uniform across the entire cooking surface
Solution Approach 1:
The conductive layer is designed with a configuration that provides uniform buoyancy reduction across the entire full surface heating area, rather than being optimized for specific burner locations. The structure incorporates multiple functional zones that work together to maintain consistent performance whether the heater operates in single-element mode, dual-element mode, or full-surface mode, making it universally effective across all operating conditions and locations.
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 conductive layers effectively eliminate the buoyancy problem across the entire cooking surface, ensuring efficient and noise-free heating of pots with low magnetic permeability by managing magnetic flux and thermal energy distribution, suitable for both small and large-sized coils and various phase configurations.
Implementation Method 1
The conductive layers are also made of materials with low magnetic permeability and high conductivity, such as aluminum. The reason for this is to avoid the magnetic flux to be absorbed by the conductive layer
Implementation Method 2
The current induced in pots with low magnetic properties, is much lower than pots with high magnetic properties. In an induction heating cooking range using such pots, a small portion of the magnetic flux generated by the coils is trapped by the material of the pot
Implementation Method 3
Since the conductivity of materials such as aluminum and copper, is high, they have a relatively low electrical resistance. Due to low electrical resistance, the induced current is transformed into a very small amount of thermal energy
Data Source
Figure 1
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Figure 4
AI summary
The present invention relates to an inductive coil unit (1) suitable for use in full surface induction heating cooking ranges comprising a glass-ceramic table (3), on which pots (2) made of materials containing aluminum or copper having low magnetic permeability are placed, the coil unit comprising a plurality of coils (4) adjacent to each other and magnetically interacting with each other, arranged on the same alignment so as to cover almost the entire table (3) plane, each driven with the same phase (0°) or with 180° phase difference with respect to its adjacent other, and at least one conductive layer (6) having a plurality of segments (5) and made of a material with low magnetic permeability and high electrical conductivity, preferably of aluminum and placed between the coils (4) and the pot (2), eliminating the buoyancy problem forming during heating of the pots (2).