Parallel / modular converter system designs

• Main Author: Wu, Xiaoxuan
• Other Authors: Tseng, King Jet
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/61490
• Institution: Nanyang Technological University

The Final Year Project A1504-131 Parallel / Modular Converter System Designs is to develop a plug in charging system for lithium-ion batteries (LIB) on-board an electric vehicle (EV). Traditionally, the rechargeable battery in an electric vehicle is charged as one whole piece. However, in this project, the battery is separated into four parallel modules while charging. Fast charging technology is adopted to shorten charging time. The design of battery charging system on-board an EV is separated into three subsystems: three-phase AC to DC rectifying subsystem, buck converter subsystem, and LIB module subsystem. To simplify the model, it is assumed that ideal 3-phase AC power (50Hz, 415V) is supplied to the charging system. A transformer is used to step down the input three phase line-to-line voltage. An uncontrolled full bridge rectifier rectifies the three-phase power source to a DC output, which supplies power to DC to DC converters. Four modular buck converters are connected to the four battery modules and charge them independently. The main focus of this project is to design and model a battery module with capacity fade characteristics and a controlled buck converter. Three subsystems are tested independently before they are integrated to the complete battery charging system. Simulation results of integrated system are also discussed. The modular battery charging system enables differential charging of individual battery modules without stressing the battery.