An Integrated Self-Modularized Battery Equalizer and Supercapacitor Charger for Hybrid Electric Vehicle Energy Storage System

This paper proposes a voltage equalizer based on voltage multiplier for the hybrid electric vehicle energy storage system. The battery equalization structure and the supercapacitor charging equalizer are integrated into a circuit with only two switches, three inductors, several energy storage capacitors, and diodes. This integration effectively reduces both the size and cost of the system. The battery equalization topology has a self-modularization feature that enables faster voltage equalization, and the supercapacitor charger has a constant current charging characteristic. The fundamental operation principles of the proposed equalizer are described in detail, and a DC equivalent circuit is derived for analyzing the equalization and charging behaviors. A hybrid array consisting of four batteries and four supercapacitors was designed for experimental verification. The results demonstrate that the proposed method effectively reduced the voltage gap to less than 10 mV after equalization.