SOC-Based Fast and Stable Charging Control Using Multilevel DC-DC Buck Converter for EVs

Abstract

In order to abate the carbon emission in the environment, electric vehicles (EVs) are being adopted across the world. Fast charging of EVs is now a point of prime concern for manufacturers. An efficient and reliable technique for rapid charging of an electric vehicle battery using a multilevel buck converter is proposed in this paper. Three-stage charging infrastructure is proposed: medium rate of charging for 0–20% SOC (State of Charge), rapid charging for 20–80% SOC, and slow charging for 80–100% SOC. The proposed approach is devised in order to extend the battery’s life expectancy. The SOC level is estimated using Coulomb’s counting method. In order to incorporate the technique, an algorithm is set to control the switching of the different levels of a three-level-buck converter. In addition, a proportional–integral (PI) controller-based current control mechanism is proposed to ensure fast and safe charging with an estimated value of charging current. The state of charge of the battery is used to estimate the overall charging current, to be supplied jointly by the three buck converters of the multilevel converter. The conduction losses are significantly reduced by the proposed multilevel structure. In order to inspect whether the proposed system is stable, a stability analysis is carried out using a Bode Plot. MATLAB/SIMULINK is used to validate the outcomes of the proposed system using a 48 V, 100 Ah Li-ion battery. A comparative analysis is presented to demonstrate the suitability of the proposed charging solution.