High-Power-Density DC–DC Converter Using a Fixed-Type Wireless Power Transmission Transformer with Ceramic Insulation Layer

Abstract

In this study, we propose the use of a short-distance and fixed-type wireless power transmission transformer via a half-bridge LLC resonant converter. A ceramic insulating layer was used instead of an air gap, meaning that the heat generated from the transformer core and the PCB winding was quickly transferred to the external metal case, with the ceramic insulating layer acting as a heat pipe. In order to stabilize the output voltage, we proposed the use of IR photo tunnel technology, and it was applied to two ceramic insulating layers so that the voltage error signal of the secondary output voltage could be transmitted as light to the primary side. As a result, it was possible to physically separate the primary and secondary sides of the power circuit centering on the ceramic insulating layer. The experiment was carried out with the input voltage of 400 V, the output voltage of 54 V, the maximum output power of 1 kW, and the switching frequency of 1.3 MHz or higher. As a result, the maximum operating frequency was 1.83 MHz, and the output voltage stability to the load was 0.49% or lower. The power density of the experimental circuit was 380 W/in3 or higher, and the maximum power conversion efficiency was approximately 93% or higher.

Keywords

• switching frequency characteristics of an experimental converter
• LLC resonant converter
• ceramic isolation transformer
• primary and secondary separable transformer
• IR photo tunnel structure
• high-power-density converter