Dual zone industrial induction heater using MOSFET based high frequency hybrid resonant converter

In this paper a converter is described where both series and parallel resonant circuits are used. To minimize the losses, switching instant is chosen at zero current crossover instant. The converter scheme described in this paper consists of four MOSFETs in H-bridge configuration. It is used for industrial induction heating purposes comprising of dual zone heating. The switching frequency lies in the range of 30 kHz to 100 kHz. Maximum efficiency is achieved for operating frequency of 66.66 kHz. Earlier voltage controlled devices like IGBTs, MCTs were tested and found that the system was working perfectly. For above mentioned frequency, IGBT was the better option considering conduction losses. But the cost of power MOSFETs is lower than the same power rating IGBTs and MCTs. So, by considering the overall cost of the dual zone industrial induction heater, slightly greater conduction losses of MOSFETs can be accepted. For the system efficiency optimization, different control strategies are discussed. The two zones have different pipe diameters and output power levels. This paper presents a new approach of dual zone operation depending on the demand of hot fluid flow in the industrial application. It is saving the energy cost when it is operating in under load condition. The circuit is simulated with PSPICE and simulation results are specified at the end.