Multilevel inverter topology based on series connected switched sources

 ABSTRACT:

A new topology for multilevel DC–AC conversion is presented in this study. It consists of isolated symmetric input DC sources alternately connected in opposite polarities through power switches. The structure allows synthesis of multilevel waveform using reduced number of power switches as compared to the classical topologies. The working principle of the proposed topology is explained with the help of a single-phase five-level inverter. Simulation studies are carried out in MATLAB/Simulink environment and experimental validations are obtained on a laboratory prototype. An exhaustive comparison of the proposed topology against the classical cascaded H-bridge topology indicates reduction in number of power switches, losses, installation area and converter cost.

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

 This paper proposes a novel topology for MLIs to reduce the number of power switches as compared to the classical topologies. It consists of floating input DC sources, which contribute individually or in series with other sources for synthesis of multilevel waveform. All input DC sources are symmetrical and no bidirectional power switches are required. Comparisons carried out in the paper show that the proposed topology requires lesser number of power components as compared to the classical topologies. For ‘N’ number of output levels, the proposed topology uses ‘N + 1’ power switches whereas classical topologies use ‘2(N − 1)’ power switches. However, reduction in number of switches leads to increased power rating of ‘N − 3’ switches. Conduction losses in the proposed topology are expected to be lesser. Comparison with the classical CHB topology also indicates that the proposed topology is relatively more economical. However, requirement of isolated input DC sources may restrict the usage of the proposed topology to specific applications. Simulation studies are performed on five-level inverter based on proposed structure and a laboratory prototype is executed for it. Satisfactory responses are observed in the prototype. It is also seen that in the event of source failure, it continues to operate with remaining sources.

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