Research On Power Management Of PHEV

The automobile industry has been focusing on developing new energy vehicles as a substitute for conventional internal combustion engine vehicles, thanks to more and more severe environment problem and energy shortage. PHEV (Plug-in Hybrid Electric Vehicle) combines the merits of EV, since it has zero emissions during driving only with electric power, with the merits of HEV, since it does not sacrifice any of the practicality of a conventional internal combustion engine vehicle, is considered to be the most potential near-term approach to address those challenges. Traditional EV-CS control strategy has big electricity loss during high output period and low oil energy utilization rate in CS stage. In this thesis, we trying to explore and establish a new energy management control strategy based on rule ideology and numerical simulation analysis software.In this paper, we briefly introduced PHEV research status and compared three different configurations of hybrid powertrain system. We chose series-parallel configuration as our study object, and designed a series-parallel PHEV powertrain system used two mechanical couplers.We matched PHEV powertrain system components parameters, including engine, motor, generator and power battery, according to vehicle dynamic performance. In order to compare the advantages of the control strategy designed in this thesis, we designed another two vehicles which have the same dynamic performance as comparison objects. One is a conventional internal combustion engine vehicle and anther is a PHEV controlled by traditional EV-CS control strategy.We mainly analyzed the current widely used EV-CS control strategy and found that it exists some drawbacks, such as high electricity loss during high output period and low oil energy utilization rate in CS stage. In this thesis, we designed a rule based CD-CS control strategy. In CD stage, we mainly consume electricity power to drive the vehicle, but when vehicle’s required torque is located in engine’s high efficiency operating area, the engine will open to drive the vehicle; In CS stage, we use vehicle’s demand torque and battery SOC as engine running state control parameters, distribute engine’s output torque to powertrain components effectively and maintain battery SOC within a certain range. Therefore, the drawbacks existing in traditional EV-CS control strategy solved.We got fuel economy and gas emissions data based on MATLAB and ADVISOR simulation software. Simulation results show that the CD-CS control strategy designed in this thesis can achieve better fuel economy and low gas emissions compared to traditional EV-CS control strategy. In this thesis, we further analyzed how driving distance, driving cycles impact on PHEV fuel consumption. Simulation results show that PHEV controlled by CD-CS control strategy like other vehicles has different fuel economy when running in different driving cycles, but it can meet the requirements of long-distance travel.Finally, we summarized research contents and innovations in this thesis, and put forward the prospect for further research and discussion.