New High Step-Up Three-Level DC/DC Converter With Parasitical Parameters Self-Balance for AC Module Applications

In this article, a three-level step-up cell (TLSC) with bipolar outputs is proposed, composed of two different step-up cells (SCs) cascaded through the shared two-winding coupled inductor. The bipolar output voltages are impervious to the influence of parasitic parameters and have the ability to self-balance. By combining the TLSC with the classical Sepic converter, a novel single-switch TL step-up dc/dc converter is proposed for ac module applications, with the capability to achieve high voltage gain and bipolar outputs. As a result, the proposed converter inherits the advantages of good self-balancing performance from the TLSC, so that its bipolar output voltages can effectively resist the effect of parasitical parameters, especially switch and coupled inductor. Besides, its coupled inductor is composed of only two windings, replacing the three windings coupled inductor used in other similar converters. This eliminates the requirement for complex winding processes to mitigate the difference in parasitic parameters among different windings. The theoretical analysis and the principal operation of the proposed converter are discussed in detail. Finally, this converter is established to verify its performance.