A Research On Comprehensive Shift Schedule For Pure Electric Bus

Since the first car was produced100years, it has brought about great convenience inour lives and improves the quality of life. However, with the development of theautomotive industry, it also induces huge problems, such as air pollution, global energycrisis. As a representative of clean-energy vehicles, pure electric vehicle has manyadvantages, such as environmental friendly, energy-saving and high energy efficiency.Thus developing electric vehicle is an effective way to solve problems caused by the car.Comparing to America and European, developing pure electric bus is morecompliance with national conditions of China than electric car. There are three reasons.First, the bus is running in fixed-route, so charging facilities can be established only atseveral stops, which effectively solve problems of charging sites wide distribution, largeinvestment. Second, the bus has large space, thus motor, battery and drive system can layout easily. Last but not least, the bus can accommodate a lot of people with good socialand practical significance.As a power source of electric bus, drive motor has wide operating range comparingto traditional combustion engine. Moreover, it has the characteristics of constant torque atlow speed and constant power at high speed. However, the drive motor of electricalvehicle equipped fixed gear ratio final drive often works in low efficiency region. Inaddition, this type of vehicle requires high performance of the motor. Not only is itnecessary to provide a larger instantaneous torque in constant torque area to accelerate orclimbing but also provides a high speed in constant power region to reach high-speed.Therefore multi-speed transmissions are needed to reduce the requirements of drive motorand battery.With property shift schedule, the drive motor in pure electric bus equippedmulti-speed transmission always works in an ideal area to improve the power andeconomy of vehicle. Therefore, it has important significance to research shift schedule ofit. This paper focuses on shift schedule of electric bus and the researches are as follow. 1) Simulation model of power train of pure electric busFirstly, the power transmission system of pure electric bus is introduced. Then thedynamics of the bus are analyzed according to the theory of automobile. At last, thesimulation model of drive motor, transmission and vehicle are established by experimentaland theoretical analysis.2) Research on power and economic shift schedule of pure electric busAs the core technology of the automatic transmission control strategy, the shiftschedules decide power, economy and comfort of the pure electric vehicle. This paperanalyzes the impact of the shift points on power according to initial acceleration time.Then dynamic shift schedule is built based on the principle of maximum acceleration. Theeconomic evaluation is got after researching factors that affect driving range. Theneconomy shift schedule is proposed according to the principle of optimum motorefficiency.3) Comprehensive shift schedule based on driving intentions and driving conditionsAs a subjective sense of the driver’s intention, it is difficult to describe with theprecise mathematical model. So this paper selects fuzzy reasoning to identify driver’sintentions. After analyzing pure electric vehicle driving characteristics, based on principalcomponent analysis, a bus route driving conditions is developed. Then a comprehensiveshift schedule based on different driving conditions and the driver’s intentions isestablished.4) Experimental study of pure electric busThe automatic transmission control system for vehicle test is developed and the shiftschedules proposed for pure electric bus are verified. Finally, the analysis results areobtained.