Study On The Control System Of The Auxiliary Power Unit Of Hybrid Electric Vehicle

There are two serious problems against the continual development of Chinese automotive industry. One is environmental pollution, the other is deficiency of petroleum resources. Hybrid electric vehicle (HEV) employing two power sources-internal combustion engine (ICE) and electric motor (EM), has been accepted world-widely as one of the most promising methods to solve these two problems. In Japan, the United States and European countries, governments and automobile manufactures have invested a lot to develop HEVS, HEV components and the key HEV technologies. Ongoing research shows that HEV is the most competitive approach to these two serious problems. For the time being, it has made pleasing achievement. The Ministry of Science and Technology of China has also set the development of HEVs and HEV components as one of the most important sub-projects in the 863 Program. Jilin University takes on one project of Tianjin Science and Technology Committee-the development of engine matching and powertrain system of HEV, together with Automobile Technology Center of China. The thesis is about this technology of the project, the development of the control and CAN (Controller Area Network) communication system of Auxiliary Power Unit (Engine-Generator set, APU for short).Series hybrid electric vehicles use an APU to provid main vehicle drive power, so the control strategy and algorithm of APU will have direct influence on the vehicle power, fuel efficiency and emission characteristic. The thesis analizes and chooses the control strategy and algorithm, works out the control and communication program, develops the hardware of the control and communication system. Therefore, to study control strategy, design the software and hardware of the control and communication system and validate against tests, providing a theoretic method to develop control system of APU and design the APU scenario, are the main research content of this thesis.Firstly, the thesis discussed the basic configurations and powertrain of series hybrid electric transit bus, brought forward methods to design and evaluate components parameters and control parameters, finished parametric design of hybrid powertrain according to performance index of SHEV. Based on the parametric confirmation, the thesis analizes the control strategy and operating mode of SHEV. There are two basic modes for the HEV, power-tracking mode and load-leveling mode, which emphasize particularly on control strategy separately. Based on the test study on these two modes by simulation, the author integrates the two modes and syncretizes the advantages of these two sides, which makes vehicle performance index meet the requirements. The introduction deepens our understanding and mastering of SHEV control strategy principle, and at the same time provides method and reference for the development and design of the control strategy of APU.Secondly, the thesis discusses the control strategy and operating mode of APU. There are two basic operating modes for APU, the lowest fuel consumption point control and the lowest fuel consumption line control, which emphasize particularly on the control strategy separately, choosing the high efficiency region of engine according to the equal fuel consumption graph in the operating area of SOFIM8140.43C engine. Based on the simulation results, the author integrates the two modes, which ensures that the engine operates constantly in the low fuel consumption and emission region and avoids frequent start, battery charges and discharges in a shallow circulation, which are beneficial to the engine and battery. The confirmation of the control strategy and algorithm of APU provides a theoretic method to the design of the control software.Thirdly, the thesis chooses the control scheme and method according to the control strategy of APU system and works out and develops the corresponding software and hardware of the control and communication system. The block-diagrams of start mode, idle mode, stable mode and stop mode of APU are worked out and the method of P...