A Controllable Voltage Equalizer with State of Charge Prediction for Supercapacitors in Large Current Applications

Abstract

The voltage imbalance of cells will reduce supercapacitor stack storage efficiency, and even cause permanent damage. To address this issue, a controllable voltage equalizer with state of charge prediction is proposed in this paper. First, the voltage equalizer is designed by using the controlled multiple-output DC-DC converter to provide a large equalization current. Then, a dynamic linear-recursive model is introduced to predict the state of each supercapacitor. Using the state of charge prediction, a control strategy is proposed to regulate the cells' charging current. The proposed voltage equalizer can obtain the complete balance of capacitor voltage in large current applications. The simulation and experiment results validate the efficiency of the proposed voltage equalizer.