An Input-Series Output-Independent Full-Bridge Dual Active Bridge Converter with Soft-Switching Characteristics for Charging and Balancing Electric Vehicle Battery Stacks

摘要

In this paper a multifunctional configuration for charging and balancing a battery stack, using modular converter design approach is proposed. Battery stacks consist of multiple cells to reach the desire voltage level and are conventionally charged altogether. The author proposes that the battery stack is divided into Battery Groups (BGs) that can be independently charged, controllably discharged under load and also balanced. The equations that describe the converter reference current for any state of operation and also permit minimization of the required sensors in the system, are presented. Mathematical modeling and detailed characteristic curves are derived based on the charging profile of the selected battery. The proposed control method relies on Pulse Frequency Modulation (PFM) and Phase Shift Modulation (PSM) to maintain Zero Voltage Switching (ZVS) and accomplish the desired output. The main advantages are the soft-switching characteristics, the flexibility in variable voltage and power levels due to modular design, and the online equalization of the batteries during charging and discharging.