An Unified Active Equalizer Circuit For Simultaneous Cell to Cell and Module to Module Voltage Balancing in a Battery Pack

Abstract

Use of battery packs are quite popular in applica-tions like electric vehicles renewable energy system, data center etc. However these battery packs encounter in imbalanced cell voltage caused by the manufacturing tolerance, aging effect and non-uniform operating conditions. Such imbalance results in decreased available capacity, fast deterioration, and even safety problems. To address this cell balancing equalizer circuit is used. However simultaneous cell to cell and module to module equalization technique have not been extensively explored much. In this regard here an unified active equalizer circuit is proposed for simultaneous cell to cell and module to module voltage balancing in battery pack. Here a multi port isolated converter is developed for bidirectional power flow while balancing the cell to cell and module to module voltage. Voltage-based equalization decision logic is used to determine the source cell, destination cell, source module and destination module. Where Energy transfer is achieved through transformer windings using PWM-controlled bidirectional MOSFET switches.The theoretical analysis of dif-ferent modes is done its efficacy has been verified with MATLAB Simulink.