An Improved Transformer for LLC Resonant Inverter for Induction Heating Applications

A new trend in power converters is to design a planar transformer that aims for low profile. However, at high frequency, the planar transformer AC losses become significant due to the proximity and skin effects. In this paper the most important factors for planar transformer (PT) design including winding loss, core loss, leakage inductance, and stray capacitance have individually been investigated. The tradeoffs among these factors have to be analysed to achieve optimal parameters. We will show a strategy to reduce losses in the primary coil of the transformer. The loss analysis of th PT was verified by the Finite Element Method (FEM) Simulations (ANSOFT MAXWELL FIELD SIMULATOR 2D) and could be utilized to optimize the transformer design procedure. Finally, the proposed PT has been integrated into an LLC Resonant Inverter for Induction Heating Application to test at high signal levels.