Parallel Hybrid Electric Vehicle Control System Research

The problem of energy shortage and environmental pollution has been paid more and more attention.These two major problems have become an important factor restricting the sustainable development of society.To meet the driver's torque requirements,traditional fuel cars only use engine to provide driving-force,which can not ensure that the engine works as far as possible in the fuel economy area.Pure electric vehicle has the characteristic of zero emission,but the current power battery is low energy density and high cost that seriously restr ict the large-scale application of pure electric vehicle.Hybrid electric vehicle takes engine as the main energy source and motor as an auxiliary power source.Hybrid electric vehicle through the coordination effect of the motor can not only ensure the en gine usually run in the fuel economy region,but also can overcome the demand of large capacity battery,which is the most market prospects.The development of high performance hybrid control unit and high efficient energy management strategy are important technical problems in the research and development of hybrid electric vehicles.The configuration of powertrain is classified and then the advantages and disadvantages of various configurations are analyzed in detail.By comparing the commonly used control strategies and analyzing the characteristics of each,this paper adopts the logic threshold algorithm and improves it.According to the actual demand of hybrid electric vehicle,the hybrid control unit is designed based on freescale 32 bit microcontroller,which includes a chip power supply circuit?analog input circuit?digital input circuit?CAN communication module?pulse input module and power output module.The electrical and environmental tests of controller samples are carried out referring to the relev ant national standard.Energy management strategy is studied aiming at single axis parallel hybrid electric vehicle.In order to make engine work in the high efficiency area as much as possible,the strategy of working mode switching ?clutch control?CVT speed ratio control and torque control are formulated.The driver model?clutch model?CVT model?brake model?engine model and motor model are constructed respectively in the power system simulation software CRUISE with the combination of theory and practice.The vehicle model and the control strategy in SIMULINK is combined to verify the rationality of the proposed control algorithm.Hardware-in-loop experiment is the research content for evaluation function of control system.The bottom driver module is added before and after the control strategy model,and the embedded code is generated through the SIMULINK automatic code generation technology.Then it is downloaded to the controller by the compiler S32 Design Studio.Controller area network(CAN)has its unique advantages in data transmission speed and data transmission stability.At present,CAN bus technology is widely used among control units in vehicle.As the structure and function of the vehicle control system are more and more complex,the fault diagno sis technology based on CAN bus has been paid more attention.By studying the requirements of network layer data transceiver and the application layer diagnostic function module of the ISO15765,we compile the underlying software code of the controller and design the upper monitor of diagnostic instrument.