Composite Non-Linear Control of Hybrid Energy-Storage System in Electric Vehicle

Zhangyu Lu,Xizheng Zhang

doi:10.3390/en15041567

Abstract

The underlying circuit control is a key problem of the hybrid energy-storage system (HESS) in electric vehicles (EV). In this paper, a composite non-linear control strategy (CNC) is proposed for the accurate tracking current/voltage of the fully-active HESS by combining the exact feedback linearization method and the sliding mode variable structure control technology. Firstly, by analyzing the circuit characteristics of HESS, the affine non-linear model of fully-active HESS is derived. Then, a rule-based energy management strategy (EMS) is designed to generate the reference current value. Finally, the HESS is linearized by the exact feedback linearization method, and the proposed CNC strategy is developed combined with sliding mode variable structure control technology to ensure fast response, high performance, and robustness. At the same time, the stability proof based on the Lyapunov method is given. Moreover, the performance of the CNC strategy is thoroughly investigated and compared with simulation studies with the traditional PI control and a modified sliding mode control, and its effectiveness under different driving conditions is fully verified.

Highlights

With the rapid growth of global vehicle ownership, energy shortages and environmental pollution have become increasingly serious, which has a serious negative impact on the sustainable and healthy development of the vehicle industry
The battery energy-storage system of an electric vehicles (EV) has the disadvantages of low power density and short cycle life, which will lead to insufficient power during vehicle driving and increase the maintenance cost of vehicle energy sources [1]
A simple multimode hybrid energy-storage system (HESS) was designed for EVs, and an adaptive sliding mode control strategy with hysteresis control was presented combined with the practical application, which effectively improves the system efficiency and ensures the safety of the battery [19]

Summary

Introduction

With the rapid growth of global vehicle ownership, energy shortages and environmental pollution have become increasingly serious, which has a serious negative impact on the sustainable and healthy development of the vehicle industry. The exact feedback linearization method and the sliding mode variable structure control technology have been widely studied. For the HESS composed of the fuel cell/battery/supercapacitor, a terminal sliding mode control strategy with adaptive law was presented to realize the stable tracking of the current and maintain voltage stability [18]. A simple multimode HESS was designed for EVs, and an adaptive sliding mode control strategy with hysteresis control was presented combined with the practical application, which effectively improves the system efficiency and ensures the safety of the battery [19]. The exact feedback linearization method and the sliding mode variable structure control technology were combined, and a composite non-linear control strategy was proposed for the underlying circuit control of the fully-active HESS.

The Circuit Model

The Composite Non-Linear Strategy

Non-Linear Coordinate Transformation

Findings

Simulation and Analysis