Design of a 900 kHz induction heating unit for fast thermal treatment of a small steel wire

The analysis and design of an induction heating system for the ultrafast heating of a small-diameter steel wire at 900 kHz are presented. The design of the inductor is carried out using the field computation method, which provides the local distribution of the eddy currents and the heating power in the different parts of the magnetic circuit. The feasibility of a 1 MHz resonant power source is considered, and a self-controlled series resonant inverter using bipolar transistors is proposed. This inverter can supply 60 W at unity power factor with an operating frequency from 800 kHz to 1 MHz. The performance of the heating system is illustrated by experimental results.<>