Application of magnetic flux controllers/concentrators to induction heating coils can drastically improve the process efficiency and heat pattern control. Presentation includes: benefits provided by flux controllers, materials available for controllers, application techniques, computer assisted design of induction coils with concentrators, examples of applications. Depending on induction system design, magnetic flux controllers can concentrate heating in a specified area, change heat source distribution and shield a particular part zone or external area preventing unintended eddy current heating. Besides of the coil efficiency improvement and optimal power distribution, magnetic flux controllers reduce the coil current demand from a supplying circuitry thus strongly reducing losses in busswork, cables, transformers and inverter components. Improvement that can be achieved due to magnetic flux controllers is case dependable. 2D and 3D computer simulation allows the designer to predict accurately effect of controllers on the coil parameters and temperature distribution and optimize the whole electromagnetic system. Special attention in presentation is paid to new magnetodielectric materials optimized for induction heating conditions. These materials have high magnetic permeability and saturation flux density, excellent machinability, good chemical and temperature resistance. Concentrators from these materials can work in a wide range of frequencies and specific powers. Examples of magnetic flux controller application include surface hardening of shafts and gears, induction surface hardfacing and brazing. Magnetic Flux Controllers (MFC) are a powerful tool in induction heating technology. Recently, better understanding of their role in different induction heating systems has been obtained through a comprehensive study using computer simulation and experiments. The results of this study show that the proper use of a magnetic flux controller is always beneficial in an induction heating system, while the degree of improvement is case dependable. They can play different roles in induction heating installations and in various applications are called concentrators, controllers, diverters, cores, impeders or screens.
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