A new modified low chattering fast terminal sliding mode control for non-isolated minimum-phase power converter

Abstract

Through modification of the strongest global fast terminal sliding mode control (GFTSMC) previously reported in the literature, a new sliding surface is proposed in this paper. Among all the FTSMC structures evaluated so far, the new surface exhibits the least chattering and the best error convergence trajectory with the addition of the logarithmic expression. The effectiveness of the low chattering GFTSMC (LCGFTSMC) is demonstrated on the non-isolated minimum-phase DC-DC power converter known as the Buck converter based on the direct SMC theory. In the direct SMC, hysteresis modulation (HM), which results in a fluctuating switching frequency, is replaced by parabolic modulation (PM), which offers a constant switching frequency. Dynamic results are obtained and compared for both modulations, taking into consideration one of the factors that cause the system’s switching frequency to fluctuate. Furthermore, and most importantly, the PM approach is compared to one of the techniques presented in the literature for fixed switching frequency, which is another significant part of this study. Because the closed loops offered for fixed switching frequencies have never been compared to each other prior to this work. A series of simulation and experimental tests have been carried out on the new sliding surface and the PM, and the results show that both provide remarkable dynamic responses compared to their counterparts.