The Design Of Vehicle Control System And Research On Control Strategy For Electric Vehicle

Automotive industry is a pillar industry in modern society. With the continuous increase in automobile production and sales, the shortage of petroleum and environmental pollution become more severe. Therefore, it's an important responsibility to develop and promote the electric vehicle. After years of development, optimal control technology in electric vehicle research plays an increasingly important role.In this paper, use Nissan Bilian minibus as a benchmark. This vehicle assembles CAN Bus and adopts high efficiency motor, high-performance motor drive technology, regenerative braking technology and high-voltage protection technology. Through the new design of the chassis, body, electrical system and other components, develop an electric business vheicle. The main contents include the following parts:(1)Match parameters of motor and battery pack, then do dynamic simulation and driving range simulation with these for electric vehicle. On the basis of designing goal of electric vehicle, calculate the required parameters of motor and battery pack respectively. According to theoretical calculation, a 50kw permanent magnet synchronous motor produced by Dadihe Electric Company in Shen Zhen is chosen. Also, a 330Ah Lithium ion Battery produced by Shen Zhou Yuan Wang is chosen finally. Using the parameters of the motor and the battery to compute and simulate, the design targets are achieved.(2)Do performance test for the selected 50kw permanent magnet synchronous motor and 330Ah lithium-ion battery pack. Through the tests for the motor, obtain the real external characteristic, efficiency characteristic and overload characteristic. Through the tests for the battery, obtain the charging characteristic of different temperatures and discharging characteristic of different temperatures and different discharging rates. These features provide a basis for control strategy of electric vehicle in the subsequent chapters.(3)Design the control program of control system for electric vehicle. Electric vehicle control system includes vehicle controller, motor controller, battery manage system, safty controller, electric vehicle instrument and CAN bus and so on. In this article, define the contents of all signals among these controllers and the way of transmission. Design the point of CAN bus and formulate CAN messages. The vehicle uses TTC200 as vehicle controller in this paper, to achieve the various functions of vehicle controller.(4) Design the vehicle control strategy of electric vehicle. Electric vehicle control strategy includes driving control strategy, braking control strategy, energy manage control strategy and safty control strategy. Driving control strategy includes common mode control strategy, power mode control strategy and economic mode control strategy. The three modes control strategies can be used in different working conditions. Through designing the realationship between acceleration pedal coefficient and load of motor driving coefficient, and from the maximum torque curve of motor at different speed, it can be got motor torque control strategy in different driving conditions. In braking control strategy, vehicle controller judges weather use regenerative braking according to speed of motor and SOC of battery, and with the depth of braking padel to compute required braking force. Then, vehicle controller distributes pneumatic braking force and regenerative braking force properly. In energy manage control strategy, vehicle controller can distribute energy of battery pack properly. In this way, vehicle controller can ensure that the power of electric vehicle and smoothly "back home". With the safety control strategy, safety controller and the vehicle controller monitor high voltage of the electric vehicle and make the leakage protection, to protect the vehicle's electrical safety.(5)Debug the vehicle control system components and the overall for the electric vehicle. After debugging, go on with the vehicle road tests. The aim of the tests is to compare the dynamics and the economy of driving control strategy in the three modes. Through the tests, it can be proved that the acceleration time and the maximum angle ability in power mode are better than that in common mode, and the driving range in economic mode is longer than that in common mode. So it's proved that the three modes of the driving control strategy is feasible, they can improve the dynamical behavior of electric vehicle, and increase the vehicle's driving range.