High Step-Up Converter Based on Coupling Inductor and Bootstrap Capacitors With Active Clamping

As generally acknowledged, the high step-up dc-dc converter is widely used in the sustainable energy system as the front-end stage of the dc-ac converter. Therefore, a high step-up converter combining one coupling inductor and two bootstrap capacitors, together with the active voltage-clamping circuit which pumps portion of the leakage inductance energy to the output, is presented herein. By doing so, the efficiency at light load can be upgraded greatly, and hence tends to be flat between the minimum load and the rated load. In this letter, the basic operating principles of this converter are first illustrated in detail, and second some experimental results are provided to demonstrate the effectiveness of the proposed high step-up converter topology.

I. Introduction

As generally recognized, there are many applications with high-voltage sources fed, such as the dc–dc converter [1], [2] used in the sustainable energy system or the car as the prestage of the dc–ac converter. And, hence, it is indispensable for low voltage to be boosted to high voltage [3]–[5]. In general, the boost converter or the buck-boost converter is widely used in such applications. However, it is not easy for such converters to achieve high-voltage conversion ratios. In theory, the voltage conversion ratios of these two converters can reach infinity, but in actuality about four or five, limited by parasitic component effect and controller capability. Consequently, if the voltage conversion ratio of the converter is desired to be over five, then two-stage converter based on the boost converter or the buck-boost converter is utilized, or different converter topologies [6][18] are created.