دانلود رایگان مقاله انگلیسی بررسی یک آنالوگ چند مرحله ای تک فاز مبتنی بر سری H / موازی اتصال H-پل - IEEE 2018

Abstract

This paper investigates a multilevel inverter composed of series/parallel-connected H-bridges. The presented structure can be used for applications in which the use of semiconductor switches with low voltage and low current ratings is intended. A comprehensive system model, an overall control strategy to adjust the output voltage with constant magnitude and frequency, and a level-shifted PWM (LS-PWM) strategy based on a voltage vectors unidimensional analysis and a plane analysis are presented. The LS-PWM is capable of mitigating the low-frequency circulating current, thus generating multilevel voltage signals with low harmonic distortion, maximum number of levels, and low dv/dt. In addition, considering a wide range of values of voltages and currents and various power levels, the total converter losses are reduced compared with conventional multilevel converters. Two multilevel conventional inverters with the same number of semiconductor switches are used for comparison. Simulation and experimental results demonstrate the feasibility of the studied converter.

VIII. CONCLUSIONS

A multilevel power converter formed by four series/parallelconnected H-bridges was investigated. The converter can be used for applications in which it is intended to use semiconductor switches with low voltage and low current ratings. The solution presented can be applied to various power levels and it is best used in cases where the relationship between voltage and current has intermediate values. Comparing to conventional topologies in which the H-bridges are connected either in series (S-4HB) or in parallel (P-4HB), the structure with the H-bridges connected in both series and parallel keeps the same harmonic distortion of the output variables of the converter, considering that the average switching frequency is the same. The system model and an overall control, including the LS-PWM strategy to mitigate the low-frequency circulating current were presented, as well as the generation of voltages and currents with low harmonic content. The total losses of the proposed converter can be reduced when compared to the conventional topologies. Therefore, the proposed series/parallel converter appears as an option between classic serial or parallel connections. In terms of costs, the series/parallel converter is cheaper in relation to high-power two-level solution, once it uses low-power-rating semiconductor switches. Simulation and experimental results demonstrated the feasibility of the studied converter.