Study On The 48V Mild Hybrid Power System Of The Vehicle

In 2014,the country officially released the fourth phase of the "Method and Indicators for Evaluating Fuel Consumption of Passenger Cars." This standard stipulates that the average fuel consumption of passenger cars will be reduced to 5.0L/100 km by 2020.Under the increasingly stringent fuel consumption and emission regulations,it is basically impossible to achieve new fuel consumption and emission targets by increasing the fuel efficiency of the engine.Therefore,automotive hybridization and pure electrification are the best solutions.However,the ultimate goal of pure electrification cannot be popularized in the short term because of high costs and endurance.The automotive 48 V electrical system as a mild hybrid system,compared with the high pressure hybrid system(battery voltage greater than 100V),can achieve most of the energy saving effect with lower cost.This paper uses a traditional car as a prototype to design a 48 V mild hybrid power system,and establishes a simulation model and a control strategy model for a joint simulation study.First of all,the functions of the 48 V vehicle can be analyzed.It is determined that the12V/48 V dual voltage scheme is adopted,and the structural arrangement of the 48 V mild hybrid power system is compared to determine the structural scheme of the mild hybrid system using P2.Secondly,the main components of the mild hybrid system(motors,power batteries,etc.)are selected and analyzed,and the parameters of the main components are matched and designed according to the knowledge of the automotive dynamics and automotive theory.Thirdly,a logic-threshold control is adopted to formulate a 48 V vehicle control strategy.The control car can drive in various modes such as a motor single drive mode,an engine single drive mode,a hybrid drive mode,a regenerative brake mode,and a running power generation mode.A simulation model of control strategies is established based on MATLAB/Simulink.Finally,a vehicle model is established based on Cruise software,and simulation and dynamic simulation are performed through the joint simulation module with control strategy,and compared with the prototype vehicle simulation results.The simulation results show that the 48 V vehicle designed in this paper has better fuel economy and emission performance under the premise of ensuring power performance compared with traditional automobiles,at the same time,it verifies the feasibility of the control strategy formulated in this paper.It provides a reference for further study of mild hybrid power system.