Research On Power Matching And Performance For Pure Electric Vehicle With Two-Speed AMT

Compared to other types of new energy vehicles, the stability of high torque output at low speed and the high efficiency of constant power at high speed, making pure electric cars dominate on dynamic property and economy performance. However, most pure electric car assembled single-stage transmission, which makes the motor operate at critical point frequently, thus reducing the power output efficiency.Based on the above background and supported by the National Science and Technology Support Program(797215019), as the target of improving the drive motor ’s efficiency and vehicle’s economic performance, the paper put forward the two-speed AMT research and development for the pure electric car. In this paper, research has carried out on power matching for the pure electric vehicle drive system, design of two-speed AMT Shift execution mechanism, shift schedule formulation, the gear ratio selection and optimization, the main contents are as follows:1. Analyze the advantage of AMT application in pure electric vehicles, summarize the research status of multi-gears in domestic and overseas. Formulate a two-speed ratio optimization research route based on the existing multi-speed ratio optimization methods. The conclusion is that: pure electric vehicles using multi-gear transmission is a trend in improving vehicle dynamics and extending the driving range.2. Put the drive motor’s demand parameters as the power matching calculation basis, ascertain the ratio range of two-speed AMT then select a manual gearbox as the modified prototype. Design the structural of gear selecting and shifting executing mechanism and manufacture an experimental prototype. Based on the sliding mode control theory, this paper compile the shifting position control algorithm, and make the shifting static test for the two-speed AMT. The results shows that: An improved position control method is put forward, which need less time and have higher accuracy degree.3. Develop a shift schedule for the pure electric vehicle with two-speed AMT, and build the vehicle model by the Simulink simulation platform. Using the simulation model to analyze the vehicle’s economic performance of two-speed AMT with different gear ratio combinations in the same NEDC conditions, ultimately, obtain the best economic ratio combination. Through compared with the 2-speed AMT of optimal combination ratio and the fixed speed ratio transmission in NEDC conditions and the typical Chinese urban conditions, analyze the result of the simulation. By the working conditions simulation results show that : compared to the single-speed transmission, the two-speed AMT with optimized gear ratios has significantly improved in the dynamic property and economy performance; from the vehicle economic performance point of view, two-speed AMT is more suitable for urban conditions.