Efficiency Considerations of LLC Resonant Converter for Induction Heating Application

Abstract

Due to the high efficiency, high power density and low EMI provided by the LLc resonant converter, it has been widely used by researchers in many fields such as induction heating (IH). This converter is based on a resonant circuit consisting of a capacitor (Cr) and two inductors Lr, Lm operating in wide output load regulating ranges for the purpose of achieving good efficiency for very high power systems using a high operating frequency. This paper aims to present a half-bridge LLC resonant converter based on power supplies for IH applications. The analysis contains five components: half bridge inverter, resonant tank, high frequency transformer, rectifier and coil. The switching bridge generates a square waveform to excite the LLC resonant tank, which will produce a resonant sinusoidal current which is transferred to the secondary of the converter through a high-frequency transformer. as it scales the voltage up or down according to the output requirements. The load represented by the equivalent circuit of the coil and work-piece is fed by the current transformed by the rectifiers. This paper provides an improved knowledge of the control of the output power for high-temperature applications through numerical simulation Considering that the load parameters and resonant frequency vary substantially throughout the system operation. The results of testing demonstrated that the proposed scheme and assembly has good efficiency, and it is well suited for magnetic induction heating systems.