Bachelor Thesis from the year 2013 in the subject Electrotechnology, grade: Bachelor, Harbin Engineering University (College of Automation), course: Electronics, language: English, abstract: In recent years, with the development of power electronic devices,control theory and the increasing demand of high-quality power supply, power electronics technology has aroused widely attention from scholars. DC-DC power converters are employed in a variety of applications, including power supplies for personal computers, office equipment; spacecraft power systems, laptop, Cell phones, and telecommunications equipment, as well as dc motor drives. In this project a detailed study of zero current switching buck converters is done and also practically implemented in hardware. In addition a mathematical analysis of switching loss occurring in MOSFET's is also presented and a short study of zero voltage switching is also appended. During the hardware implementation the Ton, Toff and operating frequency were found out and thoroughly tuned through the IC555 circuit and various waveforms across inductors, capacitors, load resistor and test points were noted down. In this thesis, the Buck type circuit structure and working principle are analyzed and a DC-DC buck converter is designed. The designed converter uses ZCS scheme and realized the function that the power form is converted from 12V DC voltages to 5 V DC voltages. The output voltage can be adjusted according to the output resistor. The output voltage is stable and the performance of the designed converter is ensured. Simulation study was carried out and effectiveness of the designed converter is verified by simulation results. Finlay design is implemented in hardware and PCB layout as well.