RESEARCH ARTICLE Nonlinear control of hybrid energy storage system for hybrid electric vehicles Muhammad Asghar Majeed 1 | Muhammad Gufran Khan 2 | Furqan Asghar 3 1 School of Electrical Engineering, The University of Faisalabad, Faisalabad, Pakistan 2 Department of Electrical Engineering, FAST-National University of Computer and Emerging Sciences Chiniot- Faisalabad, Chiniot, Pakistan 3 Department of Energy System Engineering, University of Agriculture Faisalabad, Faisalabad, Pakistan Correspondence Muhammad Asghar Majeed, School of Electrical Engineering, The University of Faisalabad, Faisalabad, Pakistan. Email: engr_asghar1@yahoo.com Peer Review The peer review history for this article is available at https://publons.com/publon/ 10.1002/2050-7038.12268. Summary Rapidly evacuating fossil fuels, oil, natural gas assets, and environmental effects has made the hybrid electric vehicles more effective than conventional vehicles. There are a larger number of researches that have been carried out on fuel cell– based electric vehicles. This paper presents the nonlinear control that deals with hybrid energy storage system (HESS) for hybrid electric vehicles. HESS consists of two sources: a fuel cell and supercapacitor. Fuel cell acts as the main source while supercapacitor as the auxiliary source. These two sources are associated with bus bar link via power electronic circuitry to harness the power from these sources at single platform. A nonlinear control technique with merging effects of sliding mode and backstepping control is applied to attain the following con- trol goals: (a) better DC bus voltage regulation, (b) reference tracking of fuel cell current and supercapacitor current, and (3) global stability of proposed system. The main reason behind applying the sliding mode–based backstepping control is because of nonlinearities present in the nature of the system. The simulation has been performed on Matlab/Simulink to ensure the fast convergence, better DC voltage regulation, and error-free reference tracking with zero initial over- shoot to meet all the control objectives. KEYWORDS backstepping-based sliding mode control, hybrid electric vehicles, hybrid energy storage system, nonlinear control 1 | INTRODUCTION Vehicles become an integral part of the modern era because they provide comfortable and faster traveling. Unfortu- nately, conventional vehicles are consuming nonrenewable resources and play a major role in global warming. Global warming and fossil fuel shortage have been two critical issues for humans in present times. It causes a huge challenge for all industries including automotive in this century. Consumption of crude oil is increasing very quickly. The US Department of Energy states that 69% of crude oil is being consumed for transportation purpose, which is over LIST OF SYMBOLS AND ABBREVIATIONS: i fc , average value of fuel cell current; i sc , average value of supercapacitor current; V dc , average value of DC bus voltage; μ 1 , control signal for buck converter; μ 23 , control signal for buck-boost converter; μ n , nominal control; μ s , switching control; σ, input to direct control; ρ, sensitivity; ε, boundary layer value; K p1 , proportional gain for buck converter; K i1 , integral gain for buck converter; K p2 , proportional gain for buck-boost converter; K i2 , Integral gain for buck-boost converter; M t , total mass; A, front area; C x , aerodynamic drag constant; C r , rolling resistance; g, gravitational acceleration; ρ air , air density; η efficiency , efficiency. Received: 5 November 2018 Revised: 26 September 2019 Accepted: 29 October 2019 DOI: 10.1002/2050-7038.12268 Int Trans Electr Energ Syst. 2019;e12268. wileyonlinelibrary.com/journal/etep © 2019 John Wiley & Sons, Ltd. 1 of 17 https://doi.org/10.1002/(ISSN)2050-7038