Design And Hardware Implementation Of A Soft-switched Converter For Fuel Cell Applications

Abstract

The focus of this thesis is to design a DC-DC quasi-soft switched boost converter suitable for fuel cell applications. Study of electrical output characteristics of fuel cells was necessary for this purpose. A number of experiments were conducted to study the steady-state and transient response of fuel cell system under various load dynamics. The results of these findings were necessary for the next phase of the project which was to design a reliable and high-performance regulated DC-DC converter. The design goals were realized with a soft-switching boost converter (implementation of zero voltage switching (ZVS) and zero current switching (ZCS) schemes) that employs a simple and effective control scheme. Key benefits of soft-switching such as high efficiency (at high switching frequencies), reduced EMI, and decreased power stress on semiconductor devices were verified. Apart from these benefits, the point that is highlighted is achieving decreased fuel cell output current ripple at higher frequencies. This is of significance because fuel cell systems prefer lower levels of current ripple which ultimately results in prolonged life time of the system. In addition, operating at high frequencies will allow for designing of high power density converters to match the high power density of fuel cells.