Research On Energy Efficiency Oriented Dual-motor Electric Vehicle Powertrain Coupled Design And Control Strategy

With the sustained increase of car ownership, the oil, natural gas and other fossil fuels become more and more exhausted, and haze, water pollution become increasingly prominent. Electric vehicles have fewer emissions, low noise, high energy efficiency and high degree of electrification, which are gradually accepted by the majority of consumers, and are in line with the future direction of automotive development. However, the mileage of existing electric vehicle is limited by battery technology. So, it's important to improve the mileage of electric vehicles with the limited battery capacity. This paper relies on a Chongqing Automobile Co., Ltd. funded project ——research on energy-efficient electric vehicle drivetrain, which propose a novel dual-motor drivetrain coupling system. And the control strategy of the system is studied in-depth to improve the energy efficiency of electric vehicles, after that the recharge mileage of electric car can be improved.Firstly, the energy consumption constitution of electric vehicles is analyzed, and the main drivetrain energy consumption model is established based on the motor efficiency in driving cycles. Then, the dual-motor system energy consumption model is proposed, which is used to analyze the energy saving mechanism and provide support to dual-motor system design and provide theoretical support to dual-motor power distribution.Secondly, a new dual-motor drivetrain coupling system is proposed to meet the high efficiency, which relies on a new type mode-converter, and can achieve a single-motor drive mode, speed and torque coupling drive modes. Then the dynamic analysis of four operating modes of dual-motor drivetrain is analyzed, which show that the system can be efficient and reliable to meet the needs of the variety of driving cycles.Thirdly, the dual-motor drivetrain parameters are preliminary matched based on the standard driving cycles. Then the dual-motor operating modes are preliminary divided according to the matching results. Combined with the motor efficiency MAP, the driving cycle energy consumption objective function of the dual-motor drivetrain system is established based on the operating modes. And in terms of dynamic performance, the acceleration time objective function is established combined with multi-mode driven. Using multi objective particle swarm optimization algorithm to solve the models based on typical driving cycle information, and the results show the dynamic and economy performance have a certain degree of improvement.Fourthly, in order to obtain the basic torque of electric vehicle, the accelerator opening and the load factor curve is established based on driving cycles information. After that, the dual-motor system energy-efficient compensation strategies are proposed considering the driver information, gradient information, battery information and motor information. Equivalent driving force diagram is obtained according to the optimized parameters, and the four operating modes of dual-motor drivetrain are divided based on the principle of minimum energy consumption. Then the dual-motor torque and speed distribution strategy tables are established on this basis, in order to achieve the dual-motor torque and speed efficient distribute by the manner of look-up table.Finally, to evaluate the dynamic and economic performance of the dual-motor drivetrain vehicle, the MATLAB/Simulink simulation model is established. Comparing to the single-motor drivetrain performance, the results show that the dual-motor drivetrain has better dynamic and economic performance.