Active Equalization circuit topology of lithium battery.pptx

Battery Equalization circuit review

1. ACTIVE EQUALIZATION CIRCUIT TOPOLOGY OF LITHIUM-ION BATTERY PACK: A REVIEW Presented At Hybrid International Conference of the Department of Mechatronic Engineering, University of Nigeria, Nsukka.  

2. Introduction The global energy crisis has increased the focus on sustainable energy solutions. Lithium-ion batteries (LIBs) are crucial in electric vehicles (EVs) and energy storage systems. Their advantages include high energy density, low cost, and rechargeability. Inconsistencies in the internal and exterior environments of lithium-ion cells once they are connected as a battery pack can significantly limit the pack's capacity

3. Causes of battery cell imbalances SOC Imbalance Total Capacity Differences Battey Management System Impedance Differences Battery Cell Imbalance s

4. Cell Balancing

5. Overview of Active Equalization Circuits Various active equalization methods: Cell-to-Cell Energy Transfer Cell-to-Pack Energy Transfer Pack-to-Cell Energy Transfer Uses DC/DC converters and selection switches.

6. Cell-to-cell energy flow technique Uses a DC/DC converter with an array of selection switches. Advantage: Faster balancing speed compared to other methods. Challenge: Requires many switching elements, leading to low equalizing efficiency. Optimization efforts focus on improving efficiency and reducing complexity.

7. Cell to pack energy flow technique Uses a single DC/DC converter to transfer energy from an overcharged cell to the entire battery pack. Advantage: High equalization speed due to significant voltage difference. Challenge: Low balancing efficiency caused by transformer losses. Research focuses on improving efficiency while maintaining high speed.

8. Pack to cell energy flow technique Transfers charge from the battery pack to an undercharged cell. The DC/DC converter connects the pack to the identified cell. Similar to the cell-to-pack technique, but in reverse direction. Focus on optimizing efficiency and minimizing energy losses.

9. Comparison of the basic cell equalization circuit design Equalization circuit Equalization Pattern Speed Efficiency Components Control Complexity S C L D T Switched Capacitor (SW) AC2C Slow A √ √ － － － Easy Double tiered SW AC2C Medium A − √ √ － － － Easy Multiple Switched Capacitor DC2C Slow A − √ √ － － － Medium Cuk converter AC2C Medium A √ √ √ － － Complex Buck - boost Converter AC2C Medium A √ － √ － － Complex Single Inductor DC2C Slow A − √ － √ √ － Medium Single Transformer C2P Slow B √ － － √ √ Complex Flyback Converter DC2C Slow A − √ － √ √ － Complex

10. Research Advancements in Battery Equalization Innovations in active equalization circuits. Improved balancing speed and efficiency. Reduced switching losses and component count.

11. Conclusion Battery equalization is vital for LIB efficiency and longevity. Active equalization offers superior performance over passive methods. Ongoing research aims to optimize equalization topologies for improved energy management.