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.

KEYWORDS:

• Coulomb’s counting technique
• Electric vehicles
• Fast charging
• Multilevel buck converter
• State of Charge
• Stability analysis

ACKNOWLEDGMENT

This work was supported by the Science and Engineering Research Board, Govt. of India [Grant No. SRG/2021/000255].

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Science and Engineering Research Board, Govt. of India: [Grant Number SRG/2021/000255].

Notes on contributors

Krushna B. Ray

Krushna B Ray was born in Uhad, Bhadrak (Odisha) India, in 1997. He received a BTech degree in electrical engineering from the Veer Surendra Sai University of Technology, Burla (Sambalpur), India, in 2018, and an MTech degree in condition monitoring of power apparatus from National Institute of Technology, Hamirpur (H.P.), India. Currently he is working as an executive engineer in Maintenance Department (Projects) at Steel Strips Wheels Limited, Mehsana, Gujarat, India. E-mail: [email protected]

Rajan Kumar

Rajan Kumar was born in Bharari, Dhamtari (Chhattisgarh), India, in 1987. He received his BE degree in electrical and electronics from Chhatrapati Shivaji Institute of Technology, Durg, India, in 2009, and an MTech. degree in power electronics and ASIC design from Motilal Nehru National Institute of Technology, Allahabad, India, in 2012, and a PhD degree in power electronics, electrical machines, and drives from the Indian Institute of Technology Delhi, India, in 2017. He worked with Su-Kam Power Systems Limited Gurugram, India as deputy manager (Research & Development) from June 2017 to April 2019. He also worked as assistant professor in the Department of Electrical Engineering, National Institute of Technology Hamirpur (HP), India from May 2019 to November 2022. He has been working as assistant professor in the Department of Electrical Engineering, National Institute of Technology Kurukshetra (Haryana), India, since November 2022. He has been awarded a Young Scientist by the Department of Science & Technology, India to participate in the 4th BRICS Young Scientist Conclave (2019) held in Brazil. Dr Rajan is the recipient of many prestigious awards, including the best paper award at the 18th National Power System Conference, Guwahati (2014), the Gandhian Young Technological Innovation Award at the office of the President of India, New Delhi (2017), Amit Garg Memorial Research Award for high impact publication in the quality journal at Indian Institute of Technology Delhi (2017), Best Industry Relevant PhD Project award at Indian Institute of Technology Delhi (2018) and HOPE (Help Others ProgrammE) award at first IEEE Industrial Electronics Society Annual On-Line Conference (ONCON) (2022).His current research interests include power electronic converters, electric drives, and solar photovoltaic energy.