Analysis of Different Charging methods of Batteries for EV Applications with Charge Equalization

The lithium ion batteries are used in many mod-ern day applications because of their unparalleled advantages over the other battery technologies. In the literature, different charging techniques have been discussed and it is very important to investigate the charging techniques for lithium ion batteries. Moreover for the Electric Vehicle (EV) application, the balancing of a series connected battery string becomes a topic of great importance. The problem of charge imbalance can highly degrade the performance and life expectancy of series connected batteries. With the help of a battery equalization charger, each battery will go through a balanced charging process and receive the same amount of charge regardless of the unique characteristics of each individual battery unit. In this paper Matlab simulink software has been used to investigate the charging characteristics of different algorithms such as constant voltage charging, constant current charging, hybrid constant current constant voltage charging and pulse charging. A bidirectional DC-DC converter is employed to attain a bidirectional power flow. In addition to that a positive negative pulse charging method is employed in order to equalize the state of charge of three individual battery units which were initially at different state of charge levels. A fast charge equalization is achieved with employing a separate controller for switching devices with energy redistribution process.