Time-Domain Minimization of Voltage and Current Total Harmonic Distortion for a Single-Phase Multilevel Inverter with a Staircase Modulation
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Date
2016-10-12
Authors
Srndovic, Milan
Familiant, Yakov
Grandi, Gabriele
Ruderman, Alex
Journal Title
Journal ISSN
Volume Title
Publisher
Energies 2016
Abstract
This paper presents the optimization technique for minimizing the voltage and current total
harmonic distortion (THD) in a single-phase multilevel inverter controlled by staircase modulation.
The previously reported research generally considered the optimal THD problem in the frequency
domain, taking into account a limited harmonic number. The novelty of the suggested approach
is that voltage and current minimal THD problems are being formulated in the time domain as
constrained optimization ones, making it possible to determine the optimal switching angles. In
this way, all switching harmonics can be considered. The target function expression becomes very
compact and existing efficient solvers for this kind of optimization problems can find a solution
in negligible processor time. Current THD is understood as voltage frequency weighted THD that
assumes pure inductive load—this approximation is practically accurate for inductively dominant
RL-loads. In this study, the optimal switching angles and respective minimal THD values were
obtained for different inverter level counts and overall fundamental voltage magnitude (modulation
index) dynamic range. Developments are easily modified to cover multilevel inverter grid-connected
applications. The results have been verified by experimental tests.
Description
Keywords
multilevel inverter, staircase modulation, optimization, total harmonic distortion (THD)
Citation
Srndovic, M.; Familiant, Y.L.; Grandi, G.; Ruderman, A. Time-Domain Minimization of Voltage and Current Total Harmonic Distortion for a Single-Phase Multilevel Inverter with a Staircase Modulation. Energies 2016, 9, 815.