APU Design And Optimization Of Range Extended Electric Bus For Business Use

With car ownership has increased year by year, which makes the energyshortage and environmental pollution problems have become increasingly serious.The development of electric vehicles is imperative. But because of the existenceof the pure electric vehicle power battery energy density is low, short service life,high cost, and other disadvantages. The best electric vehicle model is rangeextended electric vehicle at present. The overall structure of the range extendedelectric vehicle increases the auxiliary power unit (APU) relative to pure electricvehicles. The effect of APU is mainly charge the battery through the enginedrives the generator. Because of the existence of APU, making the rangeextended electric vehicle has long mileage, battery capacity is small, lessenvironment pollution, low cost and other characteristics. APU hardwarestructure and control strategy will directly affect the power battery charging, thebattery life, the maximum distance, the efficiency of the engine and engine life.Therefore, the design scheme of APU is the key to the development of the rangeextended electric vehicle. The technique of APU is not yet ripe, so the research ofAPU has great practical significance. The subject target is research and designfor range extended electric bus APU.In the aspect of hardware, first of all, according the requirements of theelectric bus driving, this paper select engine, generator and power battery forrange extended electric bus. Secondly, according to the characteristics of theengine, generator and battery, this subject design the charging power unit basedon Buck topology; and the charging power unit is simulated, and the simulationresults show that the charging effect theory of the structure is ideal. Finally, thesystem design the control unit based on Infineon XC164CS microcontroller.In the aspect of control strategy, this paper analyzes the characteristics ofthe battery and engine, proposed a piecewise constant current charging control strategy. Using PI control algorithm respectively, segmenting the chargingcurrent and motor speed closed-loop control. The control strategy is theoreticallyable to optimize the running condition of the engine, and the power batterycharging effect.According to the theoretical study of system hardware structure and controlstrategy, the subject actual production prototype and debugging of the prototype.Continuous improvement in the course of the experiment and to improve thesystem performance, power battery charging current control, engine speedcontrol effect ideal, better control power circuit losses and initially verify thefeasibility of the system. The same time, according to the needs of the systemdebugging, design a monitoring system supporting intuitive operational status ofthe monitoring system and start-stop control, enhance the operability of thesystem debugging, and to ensure that the experimental safety.