Nonlinear Controller Design for Hybrid Electric Vehicle

Abstract

In order to deal with global warming, air pollution and continuously depleting conventional energy resources, the concept of Electric Vehicles (EV) has been developed for some years. Hybrid Electric Vehicles (HEVs), in particular, have the potential to contribute to the sustainable development of the transportation sector globally. In this research contribution, Sliding Mode Control (SMC) of HEV has been proposed which has Fuel Cell (FC) as a major source and Ultra-Capacitor (UC) as an auxiliary source of energy. DC-DC converters have been used across both sources to connect them to the Direct Current (DC) Bus and Alternating Current (AC) supply is fed to the traction motor through an inverter connected to the DC-Bus. SMC has been applied to control the switching operation in converters and manage the power-sharing between the two sources. It ensures the rapid tracking of the current references and regulates DC-Bus voltage for higher efficiency. Integral and Double Integral Sliding Mode Controls (ISMC & DISMC) have also been proposed to minimize steady-state error and reduce chattering. This work is further extended to propose adaptive terminal sliding mode control (ATSMC) to adapt the unknown parameters of the system. Moreover, sliding surface coefficients are calculated through Hurwitz Stability Theorem. Nonlinear stability analysis has been done to promise the system stability while simulations are done in MATLAB/SIMULINK environment using the extra-urban driving cycle (EUDC) standard. An energy management algorithm has also been proposed to ensure effective power-sharing between the two sources depending upon their nature to improve the efficiency and life span of the HESS. It dictates the power flow in the HESS while meeting the load demands during varying load conditions, keeping track of the state of charge (SoC) of auxiliary source and ensuring overall system stability. In the simulation results, the proposed controller has been compared with controllers given in the literature to highlight its superiority. The results show negligible overshoots/undershoots, reduced steady-state error. Hardware-in-loop (HIL) test bench is has also been used for the real-time implementation of the proposed controller to analyze its performance.