Research On Hardware-in-the-loop Simulation Platform For Electric Variable Transmission (EVT) Based Hev Power Train

In recent years, the HEV has heavily promoted in the market, which promotedthe study of HEV. In HEV, the power coupling is the key and difficult point. As anew kind of electromechanical energy converter, Electric Variable Transmission(EVT) has unlimited potential in HEV and received more attention recently. Thanksto its various energy transformation ways and a variety of work modes, EVT caneasily meet the hybrid requirement of coupling. What’s more, EVT can make theengine operate efficiently by decoupling the engine speed from the wheels.To further study and develop ideal control strategies of EVT based HEV on thetest bench, real driving environment is required. For this purpose, this thesis designsa dSPACE based hardware-in-the-loop simulation platform for the HEV power trainbased on EVT, including a load emulation system, a engine emulaiton system, adriver model and PC monitor interface,etc. All models are established inMATLAB/SIMULINK, and the reliability and accuracy of the designed of platformis verified by the experiments.The driver model is established based on fuzzy control combined with PIcontrol, by imitating humanbeing’s fuzzy judgment to adjust the accelerator pedal.The humanized upper computer monitor interface is established vividly.The load emulation system is designed in two different methods, inverse modelload simulation algorithm and speed closed loop algrithm. The first method issimple, easy to deduce and has a high simulation precision. This load emulationsystem includes a non-inertial load emulation system and a inertial load emulationsystem. The system is built by calculating the road model and the acceleration toemulate the non-inertia resistance and the inertia resistance respectively. A mixeddifferentiator and a FIR fiter are designed to eliminate noise in speed sampling.However acceleration discrimination is difficult and easily infulenced by noise,andspeed closed loop algorithm has the merits of high reliability,strong anti-jammingcapability and dispensed with acceleration discrimination. In order to provide avariety of load emulation theory, this paper designs another load emulation systembased on speed closed loop algorithm. The feasibility and reliability of the two kindsof load system is verified in the experiments.The engine plays a important role in HEV platform. But in troditional testbench, the real engine is used to do lots of experiments,which produces a lot of tailgas, and the use of an engine is limited while safety is not high. This paper designsan all condition engine emulation system. The high controllability motor is usedinstead of the real engine to provide power according to characteristics of the engine. An engine simulation model is built in SIMULINK, including engine dynamictorque model, engine fuel&efficiency model, engine control system model andinput control model. The engine control system model sets up the working conditionof engine. Adopting universal characteristics experiment modeling combined withtheoretical modeling to build models, and the polynomial interpolation is used. Toverify the designed system, engine emulation experimengts are performed finally,which show that this engine emulation system can emulate the engine, includingdynamical torque characteristic and fuel&efficiency. Therefore, this paper providesa new method to the research of test bench of vehicle.