PERFORMANCE OPTIMIZATION OF BATTERY BALANCING SYSTEM BASED ON MULTIWINDING TRANSFORMER AND SINGLE INDUCTOR WITH FUZZY LOGIC CONTROL METHOD

• Main Author: Yusiran
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/70249
• Institution: Institut Teknologi Bandung

Lithium-ion battery is an energy storage that is widely applied to electric vehicles and other needs such as energy storage battery systems (BESS), because of its advantages in energy density, long life and low environmental pollution. Battery cells are usually connected in series to reach the operating voltage because the voltage of one cell is not enough to meet the power demand. However, variations in internal resistance, capacity differences, aging and changes in the ambient temperature of the cells cause inconsistencies in the battery, which has a bad impact on performance and battery lifetime. One of the phenomena that often occurs due to inconsistencies in the battery is an imbalance in the voltage and charge conditions of the battery. Efforts are being made to overcome this imbalance by developing a battery balancing system. The battery balancing method is divided into two, namely passive and active balancing methods. Based on the type of component, the active balancing method is classified into three, namely the capacitor-based, inductor-based and transformer-based balancing methods. The active balancing method based on multiwinding transformer has many advantages in terms of speed balancing, high efficiency, easy isolation and simple control system. However, this method has limitations on the number of cells that can be equilibrated. The concept of modularization was developed to overcome the weakness of this method. The development of a modular battery balancing system based on multiwinding transformers has been carried out a lot, but still needs improvement. The balancing speed between modules is not optimal, the transformer design is difficult to uniform, and the use of a large number of balancing components between modules is a problem that must be solved. In this study, a modular battery balancing system topology based on a single inductor and multiwinding transformer is proposed. In particular, the voltage equalization topology based on this modular balancer consists of an intra-module balancer based on a multiwinding transformer circuit and an intermodular balancer based on a single inductor. A control algorithm based on fuzzy logic (FLC) is applied to the inter-module balancer with the difference between the module voltage and the module average voltage being used as the input variable and the duty cycle as the output variable. Meanwhile, the intra-module control uses a fixed duty cycle. Balancing is not done simultaneously at the beginning so that this control method can be used on non-uniform transformers. The simulation model was created in Matlab/Simulink 2021a and experiments using 4 cells LG HG2 18560 3000 mAh battery were carried out to verify the performance of the balancing system. The experimental results show that the FLC method can save the balancing time between modules by 31.26% compared to the control method with a fixed duty cycle. Even the balancing current between modules reaches 341 mA. The proposed control system also makes the voltage difference after the balancing process very small, it can reach zero voltage gap (ZVG) below 5 mV. The efficiency of the proposed battery balancing system is 86.95%.