Modeling And Design Of A Level-2 Onboard Lithium-Ion Battery Charging System For ECADO Four-Wheel Electric Vehicle

Abstract

Electric vehicles are considered as one of the most suitable solutions to minimize both fossil fuel consumption and emission of greenhouse gases. However, the charging mechanism, battery design, and charging-discharge time are important factors that need to be taken into consideration, when designing electric vehicles. They also determine the success and acceptance of the vehicles in the car market. According to the current research trend, a level-two onboard battery charging system is favored as compared to other charging architectures, even if it has a slow charging time when compared with the offboard charging system. To achieve improved performance levels, the battery charging system needs to have a charger integrated with the battery management system. In this regard, an interleaved boost and LLC resonant converter-based isolated onboard battery charger which is integrated with the lithium-ion battery charging management system is implemented in this research for Ethiopia can do four-wheel electric vehicle. The charging system is modeled mathematically. Also, for implementation purposes, the corresponding models are done using MATLAB software tools. Different power factor correction stage converters and isolated DC-DC converter topologies are implemented and the performance of each is evaluated. Accordingly, the interleaved boost converter is used for power factor correction and minimizing total harmonic distortion of the charging system due to its incredible performance capability. In the back-end, a multi-resonant full-bridge LLC converter is adopted for galvanic isolation and dc voltage regulation, due to their excellent performance compared to other converter topologies. This research also includes a battery management system that is only related to charging an electric vehicle to demonstrate how battery management system manages the charging system. The battery management system monitors cells, controls the charging system to charge in the Constant Current-Constant Voltage charging algorithm, estimates the state of charge, and protects the charging system from damage. A 7.6kW charger is designed to charge the battery pack with an output voltage range of 320V to 420V. As a result, the designed electric vehicle charger achieved a unity power factor, total harmonic distortion of 3.17, and the LLC converter maintain ZVS and ZCS for the overall charging stage. This implementation makes the overall battery charging system to have excellent performance.