Multiple input converter for a battery-ultracapacitor hybrid electric vehicle

Studenteropgave: Kandidatspeciale og HD afgangsprojekt

• Felipe Gonzalez
• Borja Imanol Markinez
4. semester, Energiteknik, Kandidat (Kandidatuddannelse)
The report consists of 8 chapters. First the report begins with an introduction chapter where an introduction to the subject, the objective and problem statement are presented. In the next chapter the system description is presented. The mathematical models and simulations are discussed in Chapter 3 and Chapter 4. The control of the converter is presented in Chapter 5. Chapter 6 describes the design of the converter. In Chapter 7 the laboratory work and results are presented and analyzed. Finally in Chapter 8 the conclusions are taken. The vision of replacing many of the cars on the road with clean commuter vehicles has caused most producers of cars to start building electric cars with as low price as possible. Electric cars use the energy stored in a battery or other type of energy storage systems for vehicle propulsion and provide a clean and safe alternative to the internal combustion engine. Nowadays in many places the governments have start limiting the use of very polluting cars, where only vehicles with very low emissions are allowed to operate. Moreover many governments have start providing financial subsidies and tax reductions to promote the use of electric vehicles (EVs). Making the society aware of a more clean and renewable transportation is a priority for many countries. Response to this governmental promotion is sure to be a major issue among automobile manufacturers around the world [7]. Chapter 3 presents the battery and ultracapacitor. With multiple-input converters the advantages of different sources with different voltage and current characteristics can be combined for an optimal energy use. The integration of different power sources with distinct energy and power density enables the coordination of the advantages of each source and overcome the limitations they may have and the reliability and flexibility of renewable sources are improved. In Chapter 4 is described the model of the converter. First, the buck converter is presented. The mathematical development is made. Afterwards, the implementation in Matlab/ Simulink is done and finally, the results are shown. The same is made for the boost converter. The chapter is concluded with the combination of the buck and boost converter. The new two power direction converter is presented without any control, wich is presented in the Chapter5 of the report. The main task of the Chapter 5 is to analyze and implement closed loop control of the converter. Regulation of the duty cycle value ensures the stable operation of the converter, and keeps the output voltage to the desired voltage. This control is made up of an inner current closed loop, which regulates the inductor current, and an outer close loop necessary for regulating the output voltage. The theoretical analysis shown in the previous chapters, enables developing the converter that would meet the design demands. The main concern is the selection of the switches together with the gate drivers for them. After the converter, together with the control board, was designed and successfully built, its performance should be evaluated through laboratory tests. This chapter summarizes the obtained results. The tests were conducted in such a manor to be able to examine operation of each part separetely. Final test compromised the whole system linked together to check if it can operate together. Therefore in the next sections are presented the measurementes and observations made for separate to the separate components and for the whole setup.
Sprog Engelsk 2009 Department of Energy Technology, Aalborg University
ID: 17643008