Considerations of Physical Design and Implementation for 5 MHz-100 W LLC Resonant DC-DC Converters

Abstract

Recently, high power-density, high power-efficiency, and wide regulation range isolated DC-DC converters have been required. This paper presents considerations of physical design and implementation for wide regulation range MHz-level LLC resonant DC-DC converters. The circuit parameters are designed with 3–5 MHz-level switching frequency. Also, the physical parameters and the size of the planar transformer are optimized by using derived equations and finite element method (FEM) with Maxwell 3D. Some experiments are done with prototype LLC resonant DC-DC converter using gallium nitride high electron mobility transistors (GaN-HEMTs); the input voltage is 42–53 V, the reference output voltage is 12 V, the load current is 8 A, the maximum switching frequency is about 5 MHz, the total volume of the circuit is 4.1 cm3, and the power density of the prototype converter is 24.4 W/cc.

A review on unidirectional converters for on-board chargers in electric vehicle

“…Despite many merits of high switching frequency such as less volume, it has many problems such as increasing EMI, switching loss, and less efficiency (Tao et al, 2019). To overcome these problems, softswitching technologies are preferred which are ZVS, ZCS, and LLC (Chen, 2011;Hariya et al, 2016). The drawback of PSFFB is the loss of ZVS function at light load and the duty cycle problem (Wang et al, 2017).…”

Onboard Charging DC/DC Converter of Electric Vehicle Based on Synchronous Rectification and Characteristic Analysis

“…Although the increase of switching frequency greatly reduces the volume of equipment, it also brings about problems such as increasing switching loss, decreasing efficiency, and increasing electromagnetic interference. In order to solve these problems, soft switching technologies such as ZVS, ZCS, and LLC have emerged [6,7]. The application of this technology in conventional switching power supply topology can reduce switching loss and noise interference of power switching devices in the high-frequency state of the converter, which can further improve efficiency and power density and reduce volume and weight of converter.…”