Design and Control of a Bi-directional CLLC Resonant Converter For Low voltage Energy Storage Systems

Abstract

This paper presents the design of a bi-directional CLLC converter with an Integrated transformer for energy storage systems (ESS) applications (48 V batteries). As the distributed energy generation and storage are gaining momentum it Is required to have ESS that can regulate the power bi-directionally, presently the ESS are bulky in size, to enhance the power density and converter efficiency, an integrated transformer is introduced and simulated using 3D Finite Element Analysis (FEA). Essentially, a simple PI-based voltage/current control loop Is implemented on a 32-bit microcontroller (TMS320F28379D). Also, synchronous rectification (SR) Is implemented by controlling the turn-on and turn-off delays on rectifier sides, respectively. The design and control of the CLLC converter are verified through the experimental results. A 300 kHz, 700 W prototype Is built with the peak conversion efficiency of 96.6% while charging and 96.4% while discharging.