Research On Control Strategy Of Range Extended Electric Vehicle

Compared to pure electric vehicles, the range extended electric vehicle can better solve bottleneck problems caused by the imperfect battery technology. So the range extended electric vehicle is widely regarded as the new energy vehicle with good market prospects. In order to effectively reduce the energy consumption and improve the performance of the range extended electric vehicle, the vehicle control strategy needs to be further researched.In this paper, the vehicle control strategy for a range extended electric bus has been developed. In order to establish the optimal control strategy, the thought of re-optimization was put forward based on the technology of international forefront. Therefore, the most advanced range extended electric vehicle - BMW i3 was chosen as the research object. Through the road test and chassis dynamometer test, the vehicle control strategy was analyzed, and based on this strategy, the vehicle control strategy of the range extended electric bus was put forward.In terms of the vehicle performance test of BMW i3, based on the characteristics of Beijing city road, the architecture of test system was designed. The energy consumption characteristics of BMW i3 was analyzed under various conditions based on the electricity consumption and fuel consumption data obtained from the test, and the advantages of the BMW i3 control strategy was verified under the city driving condition, then preliminarily on the control strategy of BMW i3 under different driving conditions was researched.To further understand the BMW i3 control strategy, based on the chassis dynamometer test, the research of BMW i3 control strategy was carried out. The driving conditions were designed, which includes constant acceleration, deceleration conditions and driving cycle conditions, and based on the analysis of CAN bus signal, the research methods of vehicle control strategy was put forward. Through the positioning and calibration of the CAN bus signals such as auxiliary power unit signal and power motor signal, the vehicle control strategy was researched based on the identification of correspondence relationship between characteristic points, characteristic curves and the actual control variable, which includes auxiliary power unit control strategies, energy management strategies and engine’s start-stop control strategies.Based on summary of design idea of the BMW i3 control strategy, combined with structure and characteristics of component of the range extended electric bus, the vehicle control strategy was researched and developed, which includes driver intention recognition, vehicle mode switching and power distribution. Through the Matlab/Simulink simulation platform, the developed control strategy was verified. Simulation results show that the developed control strategy can meet requirements of the vehicle driving performance. Under the Chinese typical city bus cycle condition, the vehicle’s fuel consumption is only 24.28L/100km, and compared with multiple operating points control strategy, the Fuel-Saving Rate reaches 19.8%.