A Research of Transformer Design and Leakage Inductance Reduction Method for High Step-up DC-DC Converter

Abstract

DC-DC converters, which are mainly used for voltage step-up or step-down, are usually required to be insulated between input and output. In this case, transformers are almost the only method to be used, and in this case, the transformers are called as solid-state transformer (SST), power electronics transformer (PET), electronic power transformer (EPT), power electronic traction transformer and high frequency transformer (HFT). The strong points of the transformers in power electronics are no direct electrical connection between two side, easy voltage regulation just by adjusting the turn ratio, smaller size, and weight possibility in the high frequency operation, etc. Also, the transformer is a key component in the conversion system, as it is related to power transfer. These are why it has been treated and researched widely in power electronics field [41]. This thesis contains the basic theory of transformer, operation principle of full-bridge DC-DC converters, initial design approach and key parameter estimations using mathematical equations and simulations. Plus, experimental analysis and comparisons are also included. The simulation tool used in this paper is MATLAB, Simulink and Ansys, Maxwell. Ansys, Maxwell is used for estimating important parameters such as magnetizing and leakage inductance. One of the main goals of this paper is to design an optimum prototype transformer for a conversion system, and in this process, settling design sequency and optimization are included. The other one is to find a different approach to reduce leakage inductance in case of a limited design condition. Lastly, the designed prototype transformer will be applied to the 3.7kW DC-DC converter, automotive application ver.1.