Combined Inductor Shielding with Ferrite Bars and Segmented Aluminum
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Solution Overview
Problem
Induction cooking appliances face challenges in efficiently managing magnetic interference and eddy current circulation, which lead to energy loss and overheating of induction coils, affecting performance and efficiency.
Innovation Solution
A combined electromagnetic shield system using ferrite bars and a second material, such as aluminum plates, arranged alternately to provide full magnetic coverage and block undesired macro eddy currents, reducing electromagnetic noise and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If ferrite bars are used to provide magnetic coverage, then magnetic coupling is enhanced, but macro eddy currents are generated causing energy loss and overheating
Solution Approach 1:
The aluminum shielding plate is segmented into multiple isolated islands by introducing non-conductive material between them. This segmentation breaks the continuous eddy current paths into smaller isolated loops, significantly reducing the magnitude of macro eddy currents while preserving the magnetic shielding function of the aluminum plate.
Solution Approach 2:
A non-conductive material is introduced as an intermediary between the aluminum shielding plate and ferrite bars. This intermediary material electrically isolates the aluminum plate into discrete segments, preventing the formation of large-scale eddy currents while allowing the ferrite bars to maintain their magnetic coupling function.
2Object-affected harmful factors
If aluminum plate is used to block eddy currents, then electromagnetic coverage is improved, but magnetic coupling is reduced
Solution Approach 1:
The shielding structure employs different materials with different properties in different locations: aluminum plate segments provide electromagnetic interference blocking in areas where EMI protection is needed, while ferrite bars provide magnetic coupling in areas where magnetic field transmission is required. The non-conductive material strategically placed between aluminum segments allows magnetic field penetration while blocking eddy current formation.
Solution Approach 2:
The shielding system uses a composite structure combining aluminum plate, non-conductive material, and ferrite bars. This composite arrangement leverages the EMI-blocking properties of aluminum while using the non-conductive material to prevent eddy currents, and ferrite bars to maintain magnetic coupling, achieving multiple functions simultaneously.
3Object-affected harmful factors
If continuous aluminum shielding is used, then electromagnetic coverage is maximized, but macro eddy current circulation increases
Solution Approach 1:
The continuous aluminum shielding plate is divided into multiple isolated segments by inserting non-conductive material between them. This segmentation interrupts the continuous eddy current paths, reducing the circulation of macro eddy currents and thereby minimizing heat generation from eddy current losses while maintaining EMI shielding effectiveness.
Solution Approach 2:
The non-conductive material, which might seem to reduce shielding effectiveness by breaking the aluminum continuity, actually converts the harmful continuous eddy current into beneficial isolated current loops. This transformation reduces the magnitude of eddy currents and associated heating while preserving the essential EMI blocking function.
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 shield system enhances magnetic coupling, reduces energy loss, and maintains coil temperature within safe limits, allowing for cost-effective coil design with reduced material usage and improved performance.
Implementation Method 1
a plurality of ferrite bars arranged at least in one plane that configured to provides magnetic coverage
Implementation Method 2
a plurality of second elements made of a second shielding material complementary arranged to the ferrite bars that acts as a secondary shield and provides electromagnetic coverage from induced flux
Implementation Method 3
An electric current is passed through the coil underneath the surface, creating a magnetic current throughout the pot or pan above to produce heat
Data Source
AI summary
An inductive cooking combined shield configured to be arranged below a cooking coil winding may include a plurality of ferrite bars and a plurality of elements made of a second material alternatively arranged in a plane so that to create a complementary electromagnetic shielding that extends from the center of the coil to the perimeter and has a modular structure that allows to block and/or to mitigate undesired macro eddy currents generated by the electromagnetic flux produced by the current flowing inside the winding.