A Power Conversion Technique with Hierarchical Equalization Charging Topology for LiFePO₄ Batteries

Area of Science:

• Electrical Engineering
• Energy Storage Systems
• Battery Management

Background:

• Series-connected battery systems require effective equalization to ensure optimal performance and longevity.
• Traditional equalization methods can be slow and inefficient for large battery packs.

Purpose of the Study:

• To propose and validate a novel Hierarchical Equalization Charging Topology (HECT) for series-connected battery systems.
• To enhance the speed and efficiency of battery charge balancing.
• To accurately monitor individual cell voltages within battery modules.

Main Methods:

• The proposed HECT integrates an equalizer-within module (EWM) using a buck-boost converter and an equalizer-between modules (EBM) using a flyback converter.
• A dedicated control architecture enables precise voltage monitoring of each cell.
• Experimental validation was performed using a system of 12 LiFePO4 batteries.

Main Results:

• The HECT demonstrated rapid charging balance among a large number of cells.
• The system requires fewer circuit elements compared to conventional methods.
• Battery voltage deviation was reduced by approximately 50% in experimental tests.
• Accurate cell voltage monitoring was achieved.

Conclusions:

• The proposed HECT scheme effectively achieves rapid and accurate charge balancing in series-connected battery systems.
• The HECT offers improved performance, reduced component count, and faster balancing speeds.
• This topology presents a viable solution for enhancing the performance of energy storage systems.