A novel soft switching three-phase utility frequency AC to high frequency AC direct power converter with PFC function for industrial IH appliance

This paper presents performance characteristics of a novel soft switching three phase utility frequency AC (UFAC) to high frequency AC (HFAC) direct converter with PFC function for industrial induction heating and melting applications. The proposed ¿simple three phase system¿ consists of single phase UFAC to HFAC direct converter in each phase, three phase low pass filter and IH load. This power converter can regulate the output power under a condition of a constant frequency zero voltage soft switching (ZVS) commutation principle on the basis of unique asymmetrical PWM control scheme. In this paper, the input and output characteristics of proposed direct power converter on the basis of computer aided simulation are illustrated and discussed. Furthermore, Y-connected 3¿ working coils for IH load with the balanced coupling coefficient in each phase is designed and evaluated from an experimental point of view.