A Model-Based System Engineering Approach for the Virtual Prototyping of an Electric Vehicle of Class L7

This study is aimed at creating an accurate mathematical model concerning an electric vehicle of class L7. This category includes quadricycles having a mass less than 400 kg, batteries excluded, and power below 15 kW. To this end, an electromechanical model with three degrees of freedom is developed in the Matlab-Simulink virtual environment employing the Simscape library. In the mechanical model developed in this investigation, the main degrees of freedom considered are the forward advancement, the vertical displacement, and the angular pitch. Furthermore, two additional degrees of freedom are also included in the dynamical model in order to take into account the suspension displacements as well as the dynamic effects induced by the stiffness and damping characteristics of the tires. The behavior of the contact force generated by the interaction of the tires with the road profile is described by using the Pacejka Magic Formula. On the other hand, the propulsion unit is modeled considering three different configurations: the first scheme is composed of a central electric engine having a fixed gearbox and a mechanical differential; the second design solution is similar to the previous one but is equipped with a two-speed gearbox; finally, the third configuration consists of two separate electric engines. In all the design configurations mentioned before, the vehicle can be controlled by providing the driver inputs, by controlling the cruising speed, or by ensuring that the vehicle follows a specific driving cycle. By means of a comparative analysis performed between the three different design configurations, the proposed virtual model allows for identifying which design solution is the most appropriate, thereby reducing the time required in the design phases and also simplifying the entire process development. In conclusion, it can be stated that the virtual prototype developed in this work is able to satisfactorily predict the dynamical behavior and the energy consumption of the L7 class vehicle of interest.