High-Fidelity Modelling, Parameter Identification, and Co-Simulation of a 4-Wheel Independent Drive and Steer Electric Vehicle with Custom Inverter Design

Abstract

Electric vehicles are revolutionizing ground transportation and promise to disrupt the future of urban mobility. The technological advancements in the design and control of off-road electric vehicles have required the development of high-fidelity models to predict vehicle dynamic responses. High-fidelity modelling in off-road mobility is important for several reasons, including accurate prediction of the vehicle performance prior to road tests, optimization of energy management, and identification of failure modes. In this paper, a high-fidelity vehicle dynamics model is developed for a 4-wheel independent drive/steer scaled electric off-road vehicle using the MapleSim™ software package. The vehicle multibody dynamic model consists of all the mechanical subsystems of the vehicle, including: a) double wishbone suspension, b) independent steering mechanisms, c) independently driven powertrain, and d) the chassis. Experimental parameter identification is performed to identify the parameters of some key subsystems of the vehicle model. Vehicle mechanical subsystem parameters such as the a) vehicle drag frontal area, b) wheel inertia, and c) location of the vehicle centre of gravity are determined. The accuracy of the multibody dynamic model for an off-road electric vehicle heavily depends on the accuracy of the coupled electrical subsystem model. Therefore, to incorporate the electrical subsystem into the system model, the developed vehicle dynamics plant model is imported into <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{MATLAB}^{\mathbf{TM}}/\mathbf{SIMULINK}^{\mathbf{TM}}$</tex> using the Functional Mock-up Interface and an electrical model of the Brushless DC inverter subsystem is developed using custom SPICE based libraries. This co-simulation approach allows electro-mechanical models to be developed from a design-first perspective using electrical and mechanical computer-aided design tools. This leads to a streamlined path for the designer to validate decisions prior to fabrication and assembly.