Intelligent charger with online battery diagnosis function

In the battery based applications, the performance of the system highly depends on the reliability of the battery. However, it is difficult to obtain the accurate information about the state-of-health (SOH) of battery during its operation. In this paper a 3kw battery charger with online battery diagnosis function which can estimate the SOH of the battery by using online impedance spectroscopy technique is introduced. For the charger, a phase shift full bridge converter with synchronous rectification has been adopted to implement constant current/constant voltage charge and diagnosis functions. The electrochemical impedance spectroscopy (EIS) is performed after the charge to obtain the information about the internal impedance of the battery module, hence the SOH can be estimated online by observing the impedance variation of the battery over time. All the design procedure of the proposed charger is detailed and the feasibility of the system is verified by the experimental results.