A dual-mode cascaded H-bridge multilevel inverter for improving THD

  • Roy FrancisEmail author
  • D. Meganathan
Original Paper


Conventionally, multilevel inverters utilise multi-carrier pulse width modulation or multi-stepped (staircase) modulation to produce high-power quality waveforms. Though multi-carrier modulation schemes reduce total harmonic distortion (THD), they lead to considerable switching loss at higher modulation indexes. The staircase modulation, which operates at low switching frequencies, has a limitation of excessive high THD at low modulation indexes, making it unsuitable at lower modulation indexes. The proposed modulation technique blends the advantages of multi-carrier pulse width modulation and staircase modulation to improve the THD and reduce the switching losses over a wide range of modulation indexes. The proposed multilevel inverter employs a modified level-shifted multi-carrier modulation at lower modulation indexes and shifts to sinusoidally approximated multi-stepped at moderate and higher modulation indexes. The carrier frequency of the multi-carrier modulation is varied according to the switching loss analysis to further enhance the THD. A 1 KW prototype was built to confirm the practicality of the proposed method.


Asymmetric cascaded H-bridge Field programmable gate arrays Multi-carrier modulation Multi-stepped modulation and switching loss 



The authors express sincere gratitude to Dr. Jaison Mathew, Associate professor, Department of Electrical and Electronics Engineering, Government Engineering College Thrissur, for his invaluable help in the hardware design of the circuit.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Electronics and Communication EngineeringGovernment Engineering CollegeTrichurIndia
  2. 2.Department of Electronics EngineeringAnna UniversityChennaiIndia

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