In this paper, by using a modular hybrid structure, a new topology for symmetric multilevel inverters (MLI) with a small number of semiconductors and low voltage stress across switches is proposed. Despite many other topologies, this topology can inherently produce negative levels and zero levels without using the H-bridge. The voltage stress across a particular switch of the proposed MLI is inversely proportional to the number of the switching of that switch in a voltage period. The proposed structure is based on two types of module, that is, the f-module and the e-module. The e-module uses a capacitive voltage divider to double the number of non-zero levels. The voltages of the capacitors are approximately balanced without complex control methods. The basic structure of the proposed topology is formed by connecting the f-module and the e-module in series with each other, and the cascaded topology is developed by cascading multiple f-modules with an e-module. To investigate the proposed topology and proving its practicability, simulation results with MATLAB/Simulink, investigation of the capacitor voltages, loss calculations and experimental results are presented. A comparative study is also performed to show the merit of the new multilevel inverter over other topologies.
- New modular hybrid multilevel inverter
- Low voltage stress
- Reduced number of semiconductor
In this paper, a new, modular, symmetric topology with a reduced number of semiconductors and low voltage stress across switches is proposed. Two modules which make the proposed topology, i.e. the f-module and the e-module, is described. Two novel topologies based on the mentioned modules are proposed and the output voltages, as well as the voltages of the capacitors, are investigated via simulation. The simulation results show that the average values of the capacitor voltages are close together and their ripple factors are acceptable. Besides, the sensitivity of the average value of the capacitor voltages to load change is low and the proposed topology can balance the capacitor voltages after faults. The comparison results of the proposed topologies with other topologies in different fields shows that the proposed topologies considerably reduced the number of semiconductors and voltage stress of the switches. Finally, the feasibility of the proposed model is proved by experimental results and the experimental results are in good agreement with simulation results.
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