A 50-150 kHz half-bridge inverter for induction heating applications

Abstract

A half-bridge resonant-type IGBT inverter suitable for heating magnetic and nonmagnetic materials at high-frequency is described. A series-parallel arrangement of capacitors is adopted and an optimum mode of operation is proposed. In this mode, the inverter is operated at unity power factor by PLL control irrespective of load variations, with maximum current gain, maximum overall system efficiency, and practically no voltage spikes in the devices at turn-off. The actual performance was tested on a 50-150 kHz prototype rated at 6 kW. The low-cost developed hybrid inverter is characterized by its simplicity of design and operation, yet is versatile in performance. A simplified analysis and detailed experimental results are presented.