Research On Energy Management Optimization And Real-time Application Of Planetary Hybrid Power System Of Delivery Vehicle

With the rapid development of e-commerce in China,the express delivery business has been surging year by year.In order to solve the contradiction between the growing logistics demand and the increasingly severe environmental pollution problem,the hybrid electric delivery vehicle,as a derivative of the concept of "green logistics",came into being.Planetary hybrid power system has been widely used in hybrid electric vehicles due to its prominent advantages in energy saving.At present,the existing domestic and foreign hybrid electric delivery vehicle products mostly adopt series and parallel configurations.Compared with planetary hybrid power system,their fuel saving capacity is limited.The application of planetary hybrid power system to delivery vehicles will further reduce the negative impact of logistics transportation on the environment.The key to give full play to the energy saving advantage of planetary hybrid power system is to rationally and timely optimize the energy distribution of each power sources in the system.The existing energy management strategies that can be applied in real time online are not optimal,and those that can ensure the optimal cannot be applied in real time online.Based on this problem,this paper aims to explore a real-time energy management optimization strategy based on linear quadratic tracker.Firstly,the non-linear mathematical model of the planetary hybrid power system is established according to the expression of the dynamic characteristics of the battery.The average efficiency of the battery is used to represent the input and output characteristics of the battery.The linear mathematical model of the linearized planetary hybrid power system is obtained,which lays a foundation for the development of the energy management strategy in the following chapters.Secondly,based on the dynamic programming algorithm,the global optimal solution of the logistics vehicle under the C-WTVC working condition is solved in this paper,which provides a benchmarking basis for the single-degree-of-freedom strategy of the quadratic tracker.Then,based on the theory of linear quadratic optimal control problem and the linear mathematical model of planetary hybrid power system,the quadratic performance indicators are designed from two aspects of direct fuel saving and indirect fuel saving,respectively,and the optimal control laws are derived,thus two strategies based on quadratic tracker problem are obtained.They are called direct and indirect fuel-saving strategies respectively.The two energy management strategies based on the quadratic tracker are only related to the battery SOC in the process of optimal control,so they are collectively called the single-degree-of-freedom strategy of the quadratic tracker.Finally,in order to verify the control effect of the single-degree-of-freedom strategy of the quadratic tracker proposed in this paper,the off-line simulation verification was carried out on the simulation model based on MATLAB/Simulink.The real-time testing was performed on the hardware-in-the-loop test platform built on d SPACE/Simulator.The weighting coefficients of the single-degree-of-freedom strategy of the quadratic tracker are selected by off-line simulation.At the same time,the off-line simulation verifies that the proposed strategy can meet the vehicle dynamics requirements while obtaining the fuel economy similar to the global optimal solution obtained under the C-WTVC condition.In addition,the proposed strategy can achieve power balance,and it has good adaptability under different initial SOC values of battery.In order to get the effect closer to the real vehicle control characteristics,the control strategy model based on the real vehicle control strategy architecture is adopted to simulate the hardware loop test.The test results show that both the direct and indirect fuel saving strategies have good real-time applicability.