Analysis, design, and control of new high-performance high-power dc/dc step-up converter with a study on non-dissipative snubber

Abstract

Although it is not as widely used as a step-down converter, the step-up converter in its own way finds many applications in areas such as electric vehicles, photovoltaic systems, and uninterrupted power systems, and the power capability requirements are ever increasing. However, it is very difficult to develop a high-power step-up converter with a high voltage conversion ratio due to the high input current problem which causes a serious conduction loss. The dynamic characteristics, including the right half-plane zero, non-uniform low-frequency gain, and narrow bandwidth, are also troublesome making engineers hesitate to involve themselves in developing a high-performance step-up converter. As a solution to these problems, a new phase-shifted parallel-input/series-output dual inductor-fed push-pull converter is proposed. The new converter features a voltage conversion characteristic with a uniform low-frequency gain, high efficiency, low ripple content, low device stress, and stable wide-bandwidth response. This thesis presents the complete analysis, design, control, and experimental verification of the new converter. In the mean time, the non-dissipative snubber, which is essential to high-efficiency operation of the proposed converter, is also investigated. The operation is thoroughly analyzed and the design considerations are presented. Utilizing the results of this thesis, a high-performance high-power step-up power conditioning system, which is well suited not only to a static application but also to a dynamic application such as the electric vehicle, can be successfully realized.