Phase locked loop control of 50-150 KHz Half Bridge Resonant type Inverter for Induction Heating Applications

摘要

A half-bridge resonant-type IGBT inverter suitablefor heating magnetic and nonmagnetic materials at highfrequencyis described. A series-parallel arrangement of capacitorsis adopted and an optimum mode of operation is proposed.In this mode, the inverter is operated at unity power factorby PLL control irrespective of load variations, with maximumcurrent gain, maximum overall system efficiency, and practicallyno voltage spikes in the devices at turn-off.The actual performance was tested on a 50-150 kHz prototyperated at 6 kW. The low-cost developed hybrid inverter is characterizedby its simplicity of design and operation, yet is versatilein performance. A simplified analysis and detailed experimentalresults are presented.