Optimal And Experimental Investigation To Control Strategy Of Hybrid Electric Bus

Energy saving, environmental Protection and safety remain the three subjects in today's world. With the development of modern technology, automobiles are becoming one of the main traffic tools for peoples, but they also consume a large of oils. For example, automobiles consume 45% of the total oil consumption, and produce 70-80 % of the total pollutants in Beijing in 2005. Similarly, the death rate of traffic accidents still keeps the highest record in recent years. So, it is of great significance for us to release the energy pressure and improve the air quality of city by taking efficient measures to reduce emissions of vehicle.One of the most important researches on modern vehicle technologies focuses on how to improve its performances and reduce the fuel consumption and emissions of vehicles. In the past ten year, some new technologies have become the hotspot because it come possible to solve the above problems for electric vehicle, hybrid electric vehicle and fuel cell electric vehicle etc. In a short run, the hybrid propulsion system may become the substitute of low emission vehicle (LEV), ultra-low emission vehicle (ULEV) and zero-emission vehicle (ZEV) because of its potentials in reducing emissions and bettering performances of vehicle.The paper firstly expatiates on the configuration of parallel hybrid electric bus and the characteristics of different driving cycles, and carries out parametric matching of hybrid electric bus. In addition, an orthogonal test method of parameter matching is put forward in this paper, and the characteristics of parallel hybrid propulsion assembles, parameters and control strategies are thoroughly analyzed by use of the basic orthogonal test and synthesis orthogonal test. According to the test results and its analysis of variance, key parameters to the fuel economy are determined for the hybrid propulsion system, and an optimal parameters combination is acquired for the hybrid assembles and its control strategies. Secondly, system modeling in this paper uses a combination modeling method that includes a theory modeling method and a test modeling method. That is to say, different parts adopt different modeling method. For the key parts such as engine, motor, battery and accessories, test models are acquired according to their test data. For the general parts, theory models are adopted. So a simulation model of parallel hybrid electric bus is setup based on the above modeling rules. The model's precision is verified from three guidelines such as the averaging fuel consumption, the transient torque and the transient specific fuel consumption of engine, and the tolerance of test result and simulation result is lower than 3%, so the model precision is acceptable. Thirdly, the paper analyzes the main factors influencing on vehicle performances from use, driving cycle etc. In consideration of the low fuel consumption area and the low emission area, a torque equilibrium control strategy is put forward for the parallel hybrid propulsion system. Meanwhile, simulations and tests are also carried out under the different driving cycles and different control strategies. Results show that the designed torque equilibrium control strategy can better 6.7% for the fuel economy of EQ6110HEV bus. In order to further improve the vehicle performance, the paper also discusses the optimization of control strategy, and put forward an efficiency-fist torque equilibrium control strategy. Furthermore, the fuzzy logic control controller is also designed which uses the battery SOC and the required torque of vehicle Td rv as input variables. Simulation results show that the fuel economy can better 11.9% in comparison with the primary torque equilibrium control strategy. In addition, the effectiveness, adaptability and robustness are verified from the different bus and different driving cycles. At last, the paper expatiates on the debugging test process of the multi-energy control system. The single debugging and the union debugging are separately carried out for the different working modes of the parallel hybrid electric bus by use of the multi-energy controller, and the working modes are further verified by the bench test and the field test for the hybrid electric bus. The test results show that the different working models can normally operate and stably switch. Under the condition of switching the air-conditioner (A/C) off, the test fuel consumption reaches 36 l/100km under the Wuhan city urban driving cycle. In comparison with the fuel consumption 42.9 l/100km of the conventional EQ6110 bus, the fuel-saving rate reaches 19.1%. If adopting the efficiency-first torque equilibrium control strategy, the simulation fuel consumption can reach 33.4 l/100km and the fuel-saving rate gets to 27.3% under the same conditions. So conclusions are that the configuration of EQ6110HEV hybrid propulsion system is reasonable, the torque-balancing control strategy is effective and the results get to the design objects...