Model of an electric vehicle powered by a PV cell — A case study

Abstract

The paper presents a model of an electric vehicle with a thin flexible photovoltaic cell installed on the roof. The vehicle's model consists of the following sub-models: a set of batteries (LiFePO4), an electric machine, converters, resistance to motion and the gearbox model. Based on the analysis of an equivalent schematic for a photovoltaic cell, equations have been derived which account for the losses that occur in a real-life object. A simulation model has been developed in the Matlab&Simulink program while using the results of the analysis conducted for the physical models of the above-mentioned components of the electric vehicle - photovoltaic cell system. The driving cycle has been adopted on the basis of the road conditions while accounting for the changes in irradiance during the drive from Jelenia Góra to Olsztyn. While using the derived equations of the vehicle's movement, the equivalent schematic diagram of the power transmission system (the description of the vehicle's movement which has been accomplished while using a system of d'Alambert's equations), the system of equations for an electric machine, the set of equations for the battery (using the Peukert's relationship) and the system of equations for the photovoltaic cell, we have been able to present the driving cycle (which accounts for fast charging along the driven route in a situation when the battery charging level went below 0.2), the vehicle's inertia, the sum of the resistance to motion, moment of resistance to motion, the electric motor's angular velocity, the voltage in the electric motor, the battery's voltage (current), change of voltage on the battery's terminals, change of state of charge of the battery, change of SEM of the battery as well as changes of values of the current, voltage and power in a photovoltaic cell. The paper presents the influence that a photovoltaic cell mounted on a vehicle's roof has on its range. The results presented in this paper provide practical information regarding the properties of an electric vehicle equipped with roof-mounted photovoltaic cell.