Hybrid Topologies of Multilevel Converter for Current Waveform Improvement
N. Susheela1, P.Satish Kumar2, B.Sirisha3
1N. Susheela, Department of Electrical Engineering, University College of Engineering(A), Osmania University, Hyderabad, A.P, India.
2P. Satish Kumar, Department of Electrical Engineering, University College of Engineering(A), Osmania University, Hyderabad, A.P, India.
3B. Sirisha, , Department of Electrical Engineering, University College of Engineering(A), Osmania University, Hyderabad, A.P, India.
Manuscript received on March 12, 2013. | Revised Manuscript Received on March 15, 2013. | Manuscript published on March 20, 2013. | PP: 29-37 | Volume-1 Issue-4, March 2013. | Retrieval Number: D0179031413/2013©BEIESP
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© The Authors. Published By: Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: This paper presents different multilevel converter topologies that includes NPC, NPC-CHB, FC, FC-CHB converter. The operating principle of each topology and a review of the most relevant modulation methods are discussed. Multilevel converters offer advantages in terms of the output waveform quality due to the increased number of levels used in the output voltage modulation. This advantage is particularly true for cascade H-bridge (CHB) converters that can be built to produce a large number of levels owing to their modular structure. Nevertheless, this advantage comes at the cost of multiple dc links supplied by independent rectifiers through the use of a multi-output transformer for inverters. This front end complicates the implementation of converters that have a high number of levels. An alternative method of using lower voltage cells with floating dc links to compensate only for the voltage distortion of a neutral-point-clamped and flying capacitor converter is considered for active rectifier applications. The analogy between the floating HBs and the series active filters is used to develop a strategy for the harmonic compensation of the NPC output voltage and the control of the floating dc-link voltages. This simplifies the current control scheme and increases its bandwidth. The proposed topologies have been verified using MATLAB/Simulink. The results show the improvement in the output current waveforms.
Keywords: Current Control, dc link voltage, High-Power applications, Multilevel Converter.