Induction Heating Using Three-Phase Variable Frequency Converter

Abstract

There are numerous methods for melting of metal, out of which, induction heating is the most convenient one. It is a process in which an object (metal) is heated by the principle of electromagnetic induction. In the conventional method of heating that is by using single-phase power supply, there is a zero instantaneous power twice a cycle which results in low efficiency and discontinuous method of heating; therefore, by using three-phase power supply, there is a smooth power delivery and faster operation of heating, as three-phase system has a continuous power throughout the complete alternating cycle, and one of the major advantages of using three-phase supply system is that both melting of metal and stirring action take place in a single unit. It is a method which is not widely used in industries, they generally use single-phase supply for melting, and for stirring of melted metal, different method is employed. By using three-phase supply at a frequency of 1 kHz and maintaining the V/F ratio constant, speed control of induction motor at a smoother rate is also possible. Thus, by controlling speed, the metal can be heated at required temperature, and the method also results in efficient heating.