Research On Energy Management Strategy Of Hybrid Electric Bus Based On Genetic Algorithm

Compared with the traditional single engine vehicle,the hybrid vehicle has two power sources.The cooperation of power sources can adapt to more operating conditions and achieve better economy and power performance.How to distribute the torque between the two power sources is the core of the energy management strategy of the hybrid vehicle.The research content of this paper is from a plug-in hybrid vehicle The vehicle is delivered with a WP7240 diesel engine,aiming at the lowest fuel consumption of the whole vehicle.Firstly,the whole vehicle model is built in avl-Cruise software as the control target of full-text control strategy.A rule-based control strategy is established to verify the accuracy of the model,and the working mode of the hybrid vehicle is distinguished.Then,the instantaneous energy management strategy based on the equivalent fuel consumption method is modeled.In the vehicle control strategy based on ECMs,the efficiency of the motor and the battery is considered comprehensively.By transforming the energy consumption of the motor into the equivalent energy consumption of the engine,and by different torque value distribution,the fuel consumption of the vehicle can reach a better level.The torque allocation strategy is completed in MATLAB/simulink,and the Simulink compiler is used to compile the control strategy of the vehicle,so that it can be invoked in the MATLAB module of AVL and complete the joint simulation of the vehicle.Finally,considering that the equivalent factor of oil and electricity in ECMs strategy is not a single value function of a certain parameter,but is affected by many factors such as running mileage,initial value of SOC,motor efficiency,battery efficiency,engine efficiency,etc.,it is quite tedious to solve the problem.A new attempt is made to formulate the vehicle energy management strategy by using genetic algorithm.The algorithm takes the vehicle energy consumption as the fitness function,avoiding the influence of the equivalent factor of oil and electricity.According to the collected data,the driving condition of hybrid electric bus is simply predicted,and the predicted condition is applied to optimize the gearshift mechanism of the whole vehicle.The new gearshift mechanism replaces the speed based single parameter gearshift control strategy,and is applied to the energy management strategy based on genetic algorithm.After the control strategy is formulated,DLL files are compiled according to the same method.After the joint simulation,the control strategy based on genetic algorithm is compared with the instantaneous optimization control strategy.The comparison results show that the drop of SOC curve of the bus based on the control strategy of genetic algorithm is lower in the simulation driving process,and the final value of SOC is larger under the same initial value of SOC,which is about 5.8%higher.The comprehensive efficiency of the motor is relatively higher,and the fuel consumption is lower,which is about 1.7%fuel saving.