Study On The Control System For Auxiliary Power Unit Of Extended-range Electric Vehicle

The Extended-Range Electric Vehicle(EREV),with a long driving range,combines the advantages of conventional vehicles and electric vehicles due to its wonderful performance on dynamic and economy. The EREV,especially appropriate to urban traffic,is considerd as the first choice for the upgrade of city bus.Based on the characteristics of urban traffic conditions, the matching on power and selection on parts for the power system of EREV is carried on in this paper aiming to improve the power and economy. The traffic in city is always provided with characteristics such as more idle conditions, frequent starts and stops, lower average speed as well as less power demand, so a control strategy taking above factors into account is designed. In this strategy, a more economical region for the auxiliary power unit(APU) is determined and two kinds of tracks are proposed. The APU designed in this paper is controlled in dual-closed-loop way. The control in coordination on engine and generator is studied and the rational control method is proposed.On the basis of the APU controller, the designation of APU controller, including the hardware and software, is accomplished. The hardware designation mainly includes the microprocessor selection and the peripheral circuit construction, and in the software designation, the display interface, the function and the program to control the APU is compiled. In the design process, the reliability and electromagnetic interference are fully considered and appropriate measures are adopted. The APU controller communicates with other controllers in controller area network(CAN), only exchanging with the ECU of engine in analog signals.To verify the rationality of control strategy and the validity of the control logic, the experiment bench is constructed. The experiment bench,divided into three parts,mainly includes the displaying part, the control part and the bench with its accessory. After constructing the experiment bench, two experiments are accomplished. Firstly, the speed control of APU is carried on. The PID parameters are obtained and necessary analysis on PID parameters is done. Secondly, the comprehensive control experiment for APU is finished. The relevant control logic is verified, and the APU shows a good performance.