Study On Energy Management Of Series Hydraulic Hybrid Vehicle

With the development of our country’s economy, more and more people have their own cars, that has brought lots of problems such as environmental pressure and shortage of energy. And not only the city, but also the country will has more cars. So more and more institutions and company have invested on the technology of hybrid vehicle to develop the fuel efficiency.The paper has studied others’ materials, and move forward a step to study on the impacts of hydraulic hybrid vehicle parameter optimization and energy management strategy. The method to study is simulation test. The paper’s main work is as the following:(1) Buiding the simulating model. The chapter is to analyze the longitudinal dynamics and to build the physical models of main parts including engine, hydraulic pump/motor, hydraulic accumulator, reducer, hydraulic relief valve. And the combination of theoretical modeling and experimental modeling to build the models in the environment of Simulink and AMESim.(2) Matching and optimization of main components’ parameters. According to the design requirements, the main parts’ parameters is calculated by using theoretical and experimental formula. The optimization of particle swarm optimization is used to optimize the parameters of hydraulic pump and motor. And the ratio of reducer is amended based on the result of optimization.(3) Controller designing. The controllers of serial hydraulic hybrid vehicle include upper controller and bottom controllers. And the bottom controllers include engine speed controller, load pump torque controller, hydraulic secondary component speed controller. The bottom controllers adopt PI or P controller that has modified to improve the response and to reduce the error.(4) Energy management strategy. The hydraulic accumulator has the properties of high power density and low energy density. Considering the properties of hydraulic system, the combination of thermostat control and fuzzy logical control is used to decrease the fluctuation of engine speed to improve the engine work state and to improve fuel economy.(5) The emulational and experimental analysis. The chapter has built the car model in the environment of Simulink and AMESim. Model the optimization of pump/motor’s volume is done with the Simulink. In AMESim the car model is built with the mechanical library, hydraulic library, signal library and so on. The energy management controller is programming by Modelica language in AMESim/ModelicaEditor. The thermostat control and fuzzy logical control is independently used in the emulational test. After these the modified energy management controller is studied and tested in the emulational analysis. In the high-way driving cycles and city driving cycles, the combination of modified thermostat control and fuzzy logical control has proved to be better in the aspects of engine work state and fuel economy.