Adaptive Control Design of Interleaved Three-Phase LLC Resonant Converter with Phase-Shedding Technique

Abstract

High efficiency and high power density are becoming increasingly popular in the design requirements of power supplies. In modern power electronics, resonant converters, especially LLC resonance structures are receiving much attention because of their ability to increase the working frequency to reduce the size of passive components while still ensuring high efficiency. Currently, the multi-phase resonant LLC converter is being researched and developed to increase the power capacity and power density of DC/DC converters. In addition, the multi-phase configuration can also perform phase-shedding to improve efficiency under low-load operations. This paper presents a control method using model-based adaptive control (MRAC) to adjust the parameters of the PI controller to improve the dynamic response and quality of the output voltage of the converter in case of converter's parameter change and phase shedding.  The adaptive controller responded well and obtained consistently standard results of a 48V voltage source with output voltage ripple is smaller than 200mV and overshoot is smaller than ± 1% over the full operating range. An experimental model of a 3-phase LLC converter with the output power of 3600W is built to verify the design.