A simple unit cell structure for an efficient sketch of series‐connected multilevel inverters

Abstract

This paper develops a simple design of unit cells to be taken in use in series-connected multilevel inverters. The proposed structure not only reduces the part counts efficiently but also increases the number of generated levels in the output voltage. By aggregating the cascaded series-connected units as the basic module, the proposed structure follows one H-bridge circuit. The basic module acts as the initial stage in direct current/alternative current conversion within which all the positive and zero levels are produced. Afterwards, the H-bridge circuit affords the production of symmetric sine-wave by realizing negative levels.To assure the expected operational objectives, we developed three different algorithms to determine the magnitude of input direct current voltage sources. Moreover, to further investigate the proposed structure, different switching algorithms such the fundamental switching frequency and pulse width modulation level shifting approaches are implemented and compared with each other. Extensive numerical and experimental studies are conducted to yield in a suitable evaluation platform. The obtained results demonstrate a superior performance of the proposed structure rather than the conventional topologies.depreciate the satisfactory performance of the proposed structure for low levels output voltages. For these cases, the THD content increases. This point is easily recognized in Figure 22. However, by increasing the number of levels, we obtained a more sinusoidal and clean waveform. Thus, a higher service quality is guaranteed. This in turn increases the count of power electronics devices and Figure 18. Experimental results for the proposed nine-level structure. (a) Basic module voltage (V o1 + V o2 ), (Time/div = 5 ms), and (Voltage/div = 2 V by 1:10 probe). (b) Sinusoidal output voltage waveform. (c) Output current waveform. [Colour figure can be viewed at wileyonlinelibrary.com]

A reliable and efficient single‐phase modular multilevel inverter topology

“…Conventionally, there are three basic multilevel inverters as neutral point clamped (NPC), 1 flying capacitor (FC), 2 and cascaded H bridge (CHB). [4][5][6][7] To synthesize a specific level in the output voltage, the possible switching combinations are limited, and hence, the fault in any part of the inverter leads to complete shutdown of the system. For higher levels in output voltage, the switching device count, loss, and the cost of the system are increased.…”

A multilevel inverter based on cascade connection of submultilevel units with reduced switch count

“…A transformerless cascaded multilevel inverter has been introduced to connect the DG sources to utility grid. In Choupan et al, 15 a simple structure for basic unit is presented to be used in seriesconnected multilevel inverters. In Babaei et al, 7 a general topology for cascaded multilevel inverters using developed H-bridge converters has been studied.…”

A new structure of three‐phase five‐level inverter with nested two‐level cells

“…Multilevel inverters (MLIs) are an attractive solution for various medium‐voltage applications such as industrial drives, FACTs, HVDC, and renewable energy sources . They are also extended for low‐power applications due to the benefits of reduced device stress, electromagnetic interference, and filter size with a capability to synthesize the sinusoidal output voltage waveform with improved harmonic spectrum as compared with the two‐level inverters . The emergence of MLIs started with the discovery of three topologies, namely, (a) diode‐clamped converter (DCC), (b) flying capacitor converter (FCC), and (c) cascaded H‐bride converter (CHBC) .…”