Shielding Analysis of Coaxial High Frequency Transformers used for Electric Vehicle On-Board Charging Systems

Abstract

Electric Vehicle (EV) charging can only be conducted at specific places as of the dependence on the charging facilities. External charging facilities are usually bulky and expensive due to the use of low frequency modulation technique. For this reason, EV on-board charging system becomes a popular concept in nowadays due the improvement of high frequency (HF) power electronics [1]. The EV's on-board charging system requires high power density and a HF transformer to fulfill the design requirements of a light-weight, compact, and high power density [2]. This paper introduces a High Frequency Coaxial Transformer (HFCT) with a power efficiency of >99.5% and operates with a frequency of 100 kHz. The power rating of the HFCT can be easily scaled from 2.5 to 20 kW. The electromagnetic interferences are growing by the increased operating frequency, so that an inserted copper Faraday shield is used to deal with this issue. A shielding analysis, with focus on the insertion losses, is undertaken by utilizing Finite Element Method (FEM) based numerical techniques [3-5]