Design and Development of Low Cost Mdeium Frequency Inverter for Induction Heating

Abstract

A Induction heating is a non-contact heating process. It uses high frequency electricity to heat materials that are electrically conductive. Since it is non-contact, the heating process does not contaminate the material being heated. It is also very efficient since the heat is actually generated inside the work piece. This can be contrasted with other heating methods where heat is generated in a flame or heating element, which is then applied to the work piece. For these reasons induction heating lends itself to some unique application in industry. Another desirable characteristics of induction heating is its ability to heat only a small portion of work piece.

For induction heating, high frequency is used. For this we require an inverter with switching devices which working on high frequency. MOSFET, IGBT, SCR etc. are used as a switching device in the inverter. Also control circuit is required to drive these switching devices. The cost of these switching devices is high. So overall cost of the inverter is increased. Also due to control circuit, overall circuit of inverter becomes very complex.

The main aim of the project is to design a low cost medium frequency inverter for induction heating. Transistors are used as switching device in inverter. As transistors are cheaper than other switching devices, cost of the inverter is reduced. This is a self oscillating inverter, so no control circuit is required to drive the transistor. Also due to absence of control circuit, complexity, size and cost of inverter is reduced.