Modelling and Design of Advanced High Frequency Transformers

Abstract

Carbon dioxide emission reduction has been a popular topic in recent years because it alleviates the current global warming crisis. Hence, there is an urgent need to adapt current technologies to help reduce carbon dioxide emissions before the global warming situation worsens. Amongst carbon dioxide reduction technologies, Electric Vehicle (EV) and renewable energy technologies are most likely to assist in improving this current status of the environmental issue in coming years. Due to increased interest in energy storage systems, such as EV and renewable energy, there is a pending need to improve the existing DC-DC converters used. The DC-DC converter systems used at present are usually bulky, costly and inefficient due to their low operating frequency. Hence, by increasing the operating frequency of the DC-DC converter, the size of the passive elements can be greatly reduced. Among these passive elements, the transformer occupies the most important role indisputably. A High Frequency Coaxial Transformer (HFCT), with a range of 1 kW to 20 kW was designed and introduced in this dissertation. The operating frequency was raised to between 100 kHz and 300 kHz in order to achieve high power densities and high performance efficiency. However, the coupling capacitance accompanied by an increased operating frequency (which couples high frequency noise between the primary and secondary windings) can cause serious common mode problems. Hence, the Faraday shield was placed between the windings of introduced transformers. This reduces the coupling capacitance and consequently the electromagnetic interference. The shielding effect analysis has been conducted to verify the HFCT performance with the insertion of the Faraday shield.