In this article, influences of input current frequency in an induction heating system were studied by using numerical methods. We used finite element method to solve the governing equations. Obtained results say that this parameter has great influences on the distribution and the amount of generated heat in different parts of induction heating systems. These results also will help us to select the best frequency range for different applications.
Induction heating is one of the most popular heating processes for electrical conductive materials (usually a metal) by electromagnetic induction. Induction heating provides many advantages such as: quick heating, high production rates, ease of automation and control, safe and clean working. This process has many applications in material processing, such as heat treating, joining, welding, brazing, soldering, melting and crystal growth. An induction heating installation has three important parts: a source of high-frequency alternating current, an induction coil (RF-coil) and a workpiece (metallic material) to be heated (figure 1).
In induction heating process, an induction coil surrounds the workpiece and an electrical alternative current passes through it. This current produces a time-varying magnetic field in the surrounding environment (Ampere’s law) that generates an electric field (Faraday’s law). These fields penetrate the metallic parts of system, such as workpiece and induction coil. The penetration depth depends on electrical conductivity, relative magnetic permeability and frequency of input current. As a result of electric field penetration, eddy currents will be produced in the workpiece and other metallic parts. Then electrical resistance of material leads to Joulean heating (I2R) of the material in the form of temporal and spatial volumetric heating.
Mathematical modelling combined with computer simulation is a powerful tool for induction heating design and optimization, induction coil design, equipment selection, as well as education and business presentations. The traditional approaches to induction heating system development were based on a pure “trial and error” method. These traditional methods for induction coil and process design were time consuming and expensive due to having to manufacture and modify several inductors. These methods were also limited in applied cases and could not provide the developer with a good understanding of what is going on in a given induction heating system or information on why a given induction system worked or did not work properly. Today, more and more induction heating designers are shifting their development process from traditional empirical methods to computer simulation or a combination of both. Computer simulation provides induction process designers with a wealth of information on the system dynamics. It also can be used to explain, demonstrate and predict the process sensitivity to changes of an induction system. The early mathematical...