Results of an Innovative 100kW Induction Heater Prototype Testing

Industrial induction heating processes can contribute to the European Union (EU) energy saving goal of 20 percent before 2020. Induction manufacturers already propose many efficient solutions available at industrial scale. To improve induction devices for better energy efficiency, EDF R&D set up a French collaborative project called Innovative Solutions for Induction Systems (ISIS) with the financial support of the French National Research Agency (ANR). The objective of ISIS is to promote induction heating as a best available technology (BAT) and to develop innovative solutions to increase its efficiency. This paper reports the ISIS project innovations. The paper also discusses about the efficient heat conversion from the induction heating devices through the use of new auto-adaptive multi-coil power supply with low losses coils. An important aspect of this project is the recovery of fatally lost heat energy (cooling of the inductors). During the prototype testing, first the control algorithms of the multi-coil technology were successfully tested on a 100 kW 3-coils power supply. A homogenization technique is proposed to model a multi-strand coil and to use it in industrial setting. The multi-strand coils are now used only in low power residential applications such as induction cooking. A heat recovery test bench is built and equipped with a predictable function control (PFC) loop to fit with the production fluctuations. This paper also presents an analysis of the U.S. potential market for these new induction heating approaches and their applications in industries. Induction Heating: Background Induction heating is a method of providing fast and consistent heat for manufacturing applications that involve bonding or changing the properties of metals or other electricallyconductive materials. Induction heating may be used to replace a wide variety of conventional process heating methods, such as fossil/electric furnace heating, salt/lead bath heating, flame heating, and a variety of specialized brazing processes. All of these processes heat the outer surface of the workpiece. In contrast, induction heating heats deep inside the workpiece. The induction heating process relies on induced electrical currents within the material to produce heat. The electromagnetic field is produced by applying current with a frequency of 60 Hz to 800 kHz to an inductor coil in proximity to the workpiece. Where the magnetic field intersects a workpiece made from any electrically conducting material, it generates a circulating current, which generates heat. The lower the frequency, the deeper the current penetrates into the workpiece. The basic components of an induction heating system are an AC power supply, induction coil, the workpiece (material to be heated or treated), and the cooling system. Industrial induction heating power supplies cover a wide size range from approximately 1 to 3,000 kW of electric power. The size of the power supply depends on several variables, including the workpiece mass, the required temperature elevation, the specific heat and electrical properties of the workpiece, and the coupling efficiency of the coil design. In addition, thermal losses due to conduction, convection, and radiation must also be considered. 3-1 ©2013 ACEEE Summer Study on Energy Efficiency in Industry T semicond the use interface the coil hours at a T design b heating i simple in coil desig