Research On Online Energy Compensation Control Of PHEV Based On Driving Cycle Error

Plug-in hybrid electric vehicle(PHEV)is a new energy vehicle between an electric vehicle(EV)and a hybrid electric vehicle(HEV).In addition to the advantages of EV and HEV,PHEV can also be charged by external power grids because of its large battery capacity,it can increase the pure electric mileage and reduce the fuel consumption of the cehicle,and it has been received high attention from Governments,auto manufacturers,universities and research institutions around the world.PHEV can show advantages in energy saving and emission reduction,and it is inseparable from the vehicle energy management strategy.Therefore,researching the real-time and efficient energy online control method of plug-in hybrid electric vehicle is an important realistic significance for further improving the fuel economy of the vehicle.Based on the Natural Science Fund and the enterprise commissioned projects,this project takes a parallel plug-in hybrid electric vehicle as the research object,and aims to improve the fuel economy of the vehicle,the energy online compensation control method of PHEV based on driving cycle error is studied.Firstly,the difference between the driving cycle error(DCE)and the driving cycle recognition error during vehicle driving is analyzed.The DCE characteristic parameters are selected,and the DCE mathematical expression and its online calculation method are given.Secondly,the control property deviation(CPD)of the vehicle energy management system is defined,and the CPD mathematical model is established.The unified expression of the relationship between the CPD and the DCE is derived,and the method for constructing the relationship between the DCE and the CPD is given when the relationship function cannot be formalized.Thirdly,a fuzzy controller of energy compensation is designed to compensate the energy online distribution of PHEV,and its input and output variables,membership funct ion and fuzzy control rule table are determined.The battery’s power is divided into paritions,and the positive or negative value of the compensation power is judged according to the CPD.The power compensation distribution weight is determined according to the current driving mode of the vehicle,and then the compensation powers of the engine and the EM motor are obtained,and collaboratively working with the power allocated by the main control strategy to realize the energy distribution control of the whole vehicle.Finally,the online calculation methodof the DCE and the energy compensation control method are verified respectively.The test results show that: For those energy management strategies,such as RB,DP,and ECMS etc,the fuel consumption of the vehicle can be further reduced by the energy online compensation control method of PHEV based on driving cycle error,and then the energy management performance of PHEV is enhanced effectively.