Zero-voltage switching modular equalization system for series super-capacitor string

This paper presents a zero-voltage-switching modular equalization for series super-capacitor string in a large energy storage system. The zero-voltage working scheme is analyzed based on Power Simulation (PSIM) to verify its validity. An equalization system test for 16-super-capacitor cells is conducted under voltage-imbalanced conditions. The power flow model, switching patterns, and zero-voltage gap are discussed. The simulation and experimental results are presented, indicating that the equalization not only inherits the advantages of traditional inductor-based super-capacitor equalization system, but also brings some merits, such as flexible, low switching loss, and highly modularized.