HCNG Series Hybrid Electric City Bus Powertrain Development And Control

Nowadays, the use of clean fuel and the adoption of new powertrain system are two of the most feasible methods to achieve better fuel consumption and exhaust performance at the same time. The application of them both in one vehicle is widely thought to have more potential. With this background, the MOST (Ministry of Science and Technology, China) and DOE (Department of Energy, US) start a project of HCNG (Hydrogen and Compressed Natural Gas) SHEV (Serial Hybrid Electric Vehicle) development in cooperation. The work of this thesis is part of this project and is responsible for the whole powertrain development and control. The main parts of this thesis include the design and construction of powertrain, the development of control system hardware and substrate software, the development of control algorithm, the powertrain modeling and simulation, the experiment and validation, etc.In the construction of the powertrain, the analysis and selection of engine and generator used in APU are detailedly described. The final selection result is validated. Thereinto, the electrical part of SHEV powertrain is paid with most attention for the generator selection. The most innovative work in this thesis is that one electronically controlled clutch is used in APU (Auxiliary Power Unit) between engine and generator. It is mainly used to disengage the generator from the engine during the starting of engine to minimize the starter load. And it is also used to make the frequent start/stop of engine possible. After the selection of system components, the connection of them and the construction of the whole powertrain are both done mechanically and electrically.The development of control system includes hardware design and software writing. The second part is the point of this thesis. The software of control system is classified into control algorithm and substrate driving code, and these two parts are developed separately in Codewarrior and Matlab Simulink. The interface between them is the code generation function of Matlab RTW. In the control algorithm, APU control is separated from vehicle control algorithm as a special part. The control of APU is based on the APU status; whereas the control of vehicle takes the driver intent, the system power limit and optimal power situation as the most important factors.The forward models, which could be used for vehicle control algorithm debugging, of all the members in SHEV powertrain are developed in these thesis, including engine model, generator & rectifier model, clutch model, battery model, motor model and dynamometer model. The mechanical parts of these models are developed with Matlab SimDriveline, and the electrical parts are made by SimPowerSystems. To make the battery modeling, this thesis develops the resistance, capacitor and inductance modules which support dynamic parameters changing during simulation.Finally, the SHEV powertrain developed in this thesis can work well under the control of the vehicle control algorithm which is also developed here. What is more, the results shown from experiment and the ones gotten from software simulation are accordant.