An Iterative-Based Dead-Time Compensation Method for Integrated Interleaved Boost-LLC Converter

This paper proposes an iterative-based dead-time compensation method to help integrated interleaved boost-LLC converter (IIBLLC) converter achieve higher frequency. By adjusting switching frequency and compensating dead time, the converter can operate in quasi-resonant mode and the rectification control signal is synchronized with the primary side. In quasi-resonant mode, smaller current RMS results in lower conduction losses and the advantages of realizing ZCS on the secondary side can be preserved. Finally, a 400 W / 850 kHz IIBLLC prototype with 36 – 60 V input and 12 V output is demonstrated, which achieves a peak efficiency of 96.2%. The experimental results show that the LLC operates in quasi-resonant mode, and the efficiency and power density are improved.

I. Introduction

The isolated DC-DC converter used in fuel cell power systems, data center power architecture, electric vehicles, and renewable energy generation systems faces various challenges to achieve high efficiency and high power density. In various DC-DC converters, LLC resonant converter has attracted much attention in this field for its excellent soft switching performance and low EMI [1] - [3]. In general, traditional LLC resonant converter adjusts output voltage or widens the input voltage range by Pulse Frequency Modulation (PFM). However, PFM may incur some undesired problems, such as wide switching frequency variations, efficiency sacrifice, difficulties in magnetic element optimization, and complexity of high-frequency synchronous rectifier (SR) strategy [4] - [5]. Therefore, it is very necessary to improve LLC resonant converter to satisfy the wide input voltage range while maintaining high efficiency and high power density.