Parameter Matching And Control Strategy Of Hybrid Power System With Composite Bower Supply

At present,the power system for hybrid electric vehicle(HEV)is most single power battery.However due to the battery lower specific power,the ability to high current charge and discharge and recovery of braking energy is limited.So this will cause the battery life is short;Its use-cost is high;Its contribution to the energy saving and emission reduction is small.In order to make up for the shortage of power battery,this paper would use the hybrid power system composed of power batteries and ultracapacitors.The hybrid power system makes full use of the advantages of the battery higher specific power and the ultracapacitors higher specific energy,so as to prolong the service life of power battery and save energy,reduce emissions.The paper took parallel hybrid electric vehicle(PHEV)as the object of study.In order to improve fuel economy,decrease emission and improve driving,the parameter matching and control strategy of hybrid power system with composite power supply had been designed.The simulation model of hybrid electric system with hybrid power had been established.Based on the analysis of the charge and discharge capacity and efficiency for composite power supply,the numerical model of power battery,ultracapacitor and DC/DC converter had been designed.The multi-objective optimization model with fuel economy,emissions and driving based on a non-dominated sorting based algorithm ?(NSGA-?)had been designed.According to the technical indicator and NEDC driving cycle,the total power demand of engine and motor be calculated.Then,according to the rule control of hybrid power system and the fuzzy control of composite power supply system,the parameters of engine,motor,battery and super ultracapacitor had been determined.The multi-objective optimization model with fuel economy,emissions and driving for hybrid power system with composite power supply had been designed.Based on NSGA-?,the vehicle parameters had been optimized.Then multiple sets of different target optimal solution was obtained.Comparing with the single power battery system,hybrid power system with composite power supply based on NSGA-? was effective in prolonging the battery life,improving the vehicle fuel economy,reducing emissions,and improving comfort.Dynamic Programming model based on NSGA-? for hybrid power system with composite power supply had been established.First of all,Dynamic Programming model for hybrid power system with composite power supply was established,taking state of charge of the power battery and ultracapacitor as state variable,taking the torque distribution ratio of engine and motor and the power distribution ratio of the power battery and ultracapacitor as control variable,taking the engine fuel economy performance and the engine emission performance as objective function,simplifying the dimensions based on coarse grid and interpolation method.Then each stage of cost matrix was calculated through the reverse and the global optimal solution was calculated through positive sequence.By analyzing the simulation results of dynamic programming,the working rules of engine,motor,battery and ultracapacitor had been proposed.The rule control of hybrid power system and the fuzzy control of composite power supply system were improved.By comparing the optimal system based on NSGA-? and the single power battery system,hybrid power system with composite power supply had a big improvement in three indicators: fuel economy,emissions and comfort.So that the accuracy and effectiveness of the simulation and part of hybrid power system with composite power supply improved by dynamic programming based on NSGA-? had been verified by experiment results.