Background: In multi-level inverters (MLI), as the number of levels increases, there is a
proportionate increase in the count of the semiconductor devices that are employed.
Methods: An asymmetrical multi-level inverter topology using a bidirectional switch is presented,
which employs a lesser number of power electronic devices to produce fifteen levels at the output
voltage. The Nearest Level Modulation (NLM) technique is used to generate the switching pulses
and reliability analysis is performed using Markov reliability methodology. The operating principle
of the proposed MLI and its performance abilities are verified through MATLAB/Simulink and a
prototype is developed to provide the experimental results.
Results: Total Harmonic Distortion (THD) is computed for the proposed MLI for different types of
loads in the simulation environment as well as in the developed hardware prototype. The fifteen level
is achieved by using only 9 switches and 3 DC sources in comparison to the 28 switches and 6
DC sources required by the traditional cascaded H-bridge inverter.
Conclusion: The simulation and hardware results confirm the suitability of the proposed fifteen level
MLI as the total component count and the requirement of DC sources reduces considerably.
Keywords: MLI, asymmetrical, reliability analysis, Nearest Level Modulation (NLM), Total Harmonic Distortion (THD),
cascaded H-bridge inverter.
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