Study On Control Strategy Of Parallel Hybrid Electric Bus

In the background of the global energy and environmental issues having become increasingly prominent, the automotive industry is facing severe challenges. Energy saving, environmental protection and safety are the three main themes of today’s auto industry development. How to improve the vehicle performance to reduce energy consumption and emission is an important part of today’s automotive technology research. Hybrid electrical vehicle has become one of the most practical significant ways to solve energy and emission problems with good fuel economy and lower emissions. Control strategy as the brain of hybrid electric vehicle, commands coordination among two power sources (engine and motor) and other parts. And it is combined with the advantages of traditional vehicle and pure electric vehicle, giving full play to determine the overall performance advantages for hybrid electric vehicle. The research on control strategy of hybrid electric vehicle is carried out from the following several aspects.First of all, the efficiency characteristics of hybrid electric vehicle drive system are researched and the major components as well as the vehicle model are built. In the modeling process, according to the principles of what the key model is based on the test and the general model is based on the theory, a combination of method based on the experimental modeling and theoretical modeling is used, to complete the construction work of the main components in drive system and the vehicle model. For the sake of developing the multi-mode control rules, according to the work state of power battery for hybrid electric vehicle, the battery charge and discharge mode are analyzed.Then, from the points of view of the overall efficiency of drive system, the efficiency of various components such as the engine, motor, battery and transmission in hybrid system is comprehensively considered so as to achieve the optimal overall efficiency and an optimal control method of hybrid electric vehicle is presented. According to the size of the demand torque and range of the battery state of charge (SOC), this method determines the possible operating modes. The engine torque and motor torque are distributed under the maximum efficiency of drive system to make engine and motor output corresponding torque. This is realized by calculating the efficiency of the system under different operating modes respectively, and then comparing the efficiency of drive system in different work modes. And the simulation experiments are conducted to verify the validity of proposed method. At last, in order to realize the target of what according to the actual driving cycle, the control strategy can be automatically adjusted, so a self-learning control strategy optimization method for hybrid electric vehicle is proposed in this. Firstly, according to the vehicle operation data for nearly four years, four typical driving cycles of actual vehicle running are constructed by means of principal component analysis and cluster analysis technology. The data is real-time collected by the independent development of the data acquisition system. Secondly, Aiming at the minimum fuel consumption, the optimal control parameters are determined for each typical driving cycle. The real vehicle driving cycle is on-line fuzzily recognized based on the fuzzy theory and the results are sent to the vehicle controller. Then the optimal control parameters corresponding to driving cycle are called by vehicle controller to achieve the goal of optimization control for hybrid electric vehicle. And the simulation experiments are conducted to verify the validity and accuracy of proposed method.