Abstract
Considering the aim of having low switching losses, especially in medium-voltage and high-power converters, the pre-programmed pulse width modulation technique is very useful because the generated harmonic content can be known in advance and optimized. Among the different low switching frequency techniques, the Selective Harmonics Elimination (SHE) modulation method is most suitable because of its direct control over the harmonic spectrum. This paper proposes a method for obtaining multiple solutions for selectively eliminating specific harmonics in a wide range of modulation indices by using modified Newton–Raphson (NR) and pattern generation techniques. The different pattern generation and synthesis approach provide more degrees of freedom and a way to operate the converter in a wide range of modulation. The modified Newton–Raphson technique is not complex and ensures fast convergence on a solution. Moreover, multiple solutions are obtained by keeping a very small increase in the modulation index. In the previous methods, solutions were not obtainable at all modulation indices. In this paper, only exact solutions to the low-order harmonics elimination for Cascaded H-bridge inverter are reported for all modulation indices. Analytical and simulation results prove the robustness and correctness of the technique proposed in this paper.
Highlights
The performance of a VSC mostly depends on the type of PWM strategy chosen for its operation.The PWM schemes for power converters can be broadly classified as high switching frequency PWM, such as sine PWM; space vector PWM; and low switching frequency, such as Selective HarmonicsElimination (SHE), Space Vector Modulation (SVM), and selective harmonics mitigations (SHM)schemes [1,2,3,4,5,6,7,8,9,10]
Two different approaches have been proposed for obtaining multiple sets of solutions in a two widedifferent range of modulation
Forapproach obtaining multiple sets of solutions solutions at a particular modulation index, whereas the pattern synthesizing approach ensures in a wide range of modulation indices
Summary
The performance of a VSC mostly depends on the type of PWM strategy chosen for its operation. Among the different low switching frequency techniques, SHE is a pre-programmed modulation method thatwas proposed to eliminate two lower-order harmonics by having additional. The biggest challenge in the implementation of the SHE-PWM technique is solving the set of trigonometric equations with the multiplicity of angles obtained after applying a Fourier series analysis of the output waveforms. These sets of equations are highly non-linear and transcendental in nature and may exhibit multiple solutions, a unique solution, or no solution in a different range of modulation index. The problem is aggravated when the modulation index is low and generally few solutions are obtained This limitation is overcome in the proposed approach,which provides more flexibility and. The cascaded H-bridge multilevel inverter can have several H-bridge cells connected in cascades
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
