Energy Optimal Control Strategy Of Hybrid Electric Vehicle Based On PMP Algorithm

Under the global voice of ‘energy saving' and the current boom in the development of energy storage technology at home and abroad, electric vehicles, especially pure electric vehicles and hybrid electric vehicles, have been growing up as the representative of a new generation of vehicles just in a few years, with its low emissions, high performance and other advantages. Energy optimal control of the whole hybrid electric vehicle power system, as one of the core technologies of electric vehicles, are bound to become a hot target of ‘clean energy' vehicle development and its research. Taking into account of the low power density of lithium-ion battery itself, battery life constrainting factors because of frequent charging/discharging, as well as driving mileage and battery performance, cost and others in a single vehicle driving cycle, hybrid energy storage system as the energy storage device drives hybrid electric vehicle running together with an internal combustion engine, optimal control of hybrid energy storage system is inevitably one part of the whole hybrid electric vehicle control. Therefore, this thesis select hybrid electric vehicle as the object of research, which is embedded Li-SC HESS, put the vehicle fuel consumption function as the control target, it will focus on the study of energy optimal control strategy of hybrid electric vehicle. This research contents mainly include the following aspects:1. Taking lithium-ion battery and super-capacitor as the research object, considering the charging/discharging characteristics, establish the corresponding equivalent circuit models, and analyze the factors of each state of charge(SOC) and current.2. Analyzing the factors of cost, conversion efficiency and the complex degree of the structure, select a reasonable Li-SC HESS topology and bi-directional DC/DC power conversion device, in order to establish the Li-SC HESS equivalent model.3. Study and analyze the structure of hybrid electric vehicle, put the minimum internal combustion engine fuel consumption function as the objective function, and the internal combustion engine torque and speed, hybrid energy storage system SOC and its limit current value as the constraints, etc. Use the Pontryagin minimum principle(PMP) to solve the energy optimal control problem of hybrid electric vehicle. At the same time, use a PSO-PI controller in real-time tracking the co-state parameters of the algorithm based on Pontryagin's minimum principle to short the tracking time.4. In order to further optimize the performance of hybrid energy storage system, this thesis presents a power limit management method to control the hybrid energy storage system internally based on super-capacitor pre-response principle.5. Make some additions and modifications on the base of hybrid electric vehicle prototypes by ADVISOR software, and finally establish hybrid electric vehicle simulation model, which combined with CYC-UDDS conditions simulation to analyze and verify the simulation results.In this thesis, the study on the energy optimal control method of hybrid electric vehicle, lays a theoretical foundation for further more research on the key technologies of electric vehicles.