The Multi-domain Modeling And Simulation Of Pure Electric Vehicle Based On Modelica

The research on Pure Electric vehicle(PEV) has become the focus of the new era with increasly serious environmental problems. As a typical complex multi-disciplinary system, Development of pure electric vehicle system involving multiple disciplines, such as machinery, electronics, control, thermodynamics etc. Its multi-domain modeling process not only requires model to be close to the practice of the system but also put forward higher requirements to the integration ability of the model. However, the current modeling and simulation research on PEV still focus on a single field, which make it difficult to deal with the coupling relations between different areas and realize seamless integration, these all impact the credibility of the system simulation. In order to improve the comprehensive performance of pure electric vehicles and get more accurate simulation results, it is necessary to take advantage of collaborative simulation to complete the modeling and simulation of the whole sysytem and realize the integration of the multiple areas on a unified modeling environment.This thesis will focus on the actual physical structure of a kind of pure electric vehicle, and conducts a system-level modeling and simulation of PEV with a unified multi-domain modeling language-Modelica, which is suitable for complex system modeling. The following studies are carried out in this thesis:(1) On the basis of analyzing the common battery modeling method, a PNGV equivalent circuit battery model which is suitable for PEV battery modeling is proposed to accurately simulate the actual prototype of the power system of PEV. The parameters of PNGV battery model are obtained according to the test data, and the complete battery model is constructed with full consideration of the influence of temperature effect on the battery performance; According to the mathematical model of permanent magnet synchronous motor the equivalent circuit model is established, on the basis of fully considering of the essect of the various losses and temperature, the model of PMSM is built based on Modelica, which fully considers the complex coupling relationship between machine, electric, magnetic, thermal, and other disciplines. Taking advantage of mechanical and dynamic components provided by Modelica library, hydraulic brake system, double wishbone independent suspension and plate spring suspension are modeled. In addition, the multi-body tires model is constructed according to the magic formula, which all show the huge advantage of Modelica in modeling of vehicle multibody dynamics system.(2) A consistent bus signal and interface sysytem is bulit, which made it possible for the interaction of the data and the intersection of different domain models. The driving intention is expressed according to the accelerator-pedal position, brake-pedal position and steering wheel angle signal. Besides, the vehicle control unit which consists on regenerative braking, moment distribution and state control is modeled with Modelica Electrical library.(3) With the integrating of the sub-system model, the overall PEV simulation model is framed., and dynamic performance, following condition performance, economy performance and safety performance is carried out according to relevant national standards.Results show that the model simulation data and real vehicle experiment data are basically identical, and it further demonstrates the feasibility and effectiveness of the PEV multi-domain modeling and simulation method based on Modelica language, which provides a more efficient way to improve the performance and shorten the development cycle of PEV.