A Thyristor Inverter for Medium-Frequency Induction Heating

This paper is concerned with the development of a current-fed-type inverter suitable for induction heating and melting applications in the medium-frequency (1-5 kHz) range. The control circuitry, load power factor control, thyristor turn-off control, and protection techniques are discussed. A simple and reliable starting scheme has been developed which provides reliable start-up with all practical loads. The starting circuit has a main and an auxilliary part. The necessity of one or both of these starting circuits is discussed. Experimental results from a prototype unit are presented. The performance of the equipment has been found quite satisfactory.