Induction heating is the process of heating an electrically conducting object (usually a metal) by electromagnetic induction, through heat generated in the object by eddy currents. An induction heater consists of an electromagnet and an electronic oscillator that passes a high-frequency alternating current (AC) through the electromagnet. The rapidly alternating magnetic field penetrates the object, generating electric currents inside the conductor, called eddy currents. The eddy currents flowing through the resistance of the material heat it by Joule heating. In ferromagnetic materials like iron, heat may also be generated by magnetic hysteresis losses. The frequency of current used depends on the object size, material type, coupling (between the work coil and the object to be heated) and the penetration depth.

Induction heating is the best method of providing fast, precise, clean, energy efficient, controllable and repeatable heat for a wide variety of manufacturing processes which involve bonding or changing the properties of metals or other electrically-conductive materials. Induction heating allows you to rapidly heat the object of your application while limiting contamination. The process relies on induced electrical currents within the material to produce heat. Induction heating provides a solution for applications such as cooking, brazing, hardening, preheat and post heating, shrink-fitting, annealing, soldering and many others.

The power of induction heating can range from sub-kilowatts to tens of kilowatts, depended on workpiece sizes.  The resonant frequencies of medium frequency and high frequency heating are in the range of 5-30kHz and 100-450kHz respectively. Medium frequency heating is often used for large size workpieces ( e.g. diameter > 50mm ), which need a deep penetration depth. High frequency heating is for small size or thin workpieces.

Home-used induction stoves, for example, are just a few kilowatts and operate at medium frequencies. 

Most solutions of induction stoves use IGBTs currently.  Due to frequency limitation and high conduction loss, the stoves would have to use a large coil and heatsink with air cooling, which makes it difficult to seal the power board and prevent grease from getting in the circuit and fan. High voltage SiC MOSFETs would provide a clean solution to operate the circuit at higher switching frequency and reduce the coil’s copper use. More importance is that the fan can be eliminated and the whole power board can be sealed in an Aluminum case, which not only lower the BOM cost, but improves the appliance’s reliability as well.

SiC MOSFETs aim to improve current IGBT-based solutions

For tens of kilowatt induction heating, power factor collection is required. Following is a typical induction heating power circuit. 

High Power Induction Heating Solution

Uncooled  operation  of  high temperature  and  high power  SiC  electronics  would  enable revolutionary  improvements  to  induction  heating  systems.  SiC  high power  solid state  switches will  also  enable  large  efficiency  gains  in  electric  power  management  and  control. Silicon Carbide electronic devices have demonstrated the ability to function under extreme high temperature, high frequencies and high power. The applications of SiC devcies will enable major enhancements and improvements in the field of induction heating where high frequency and high power are a requirement.