On Abolishing Symmetry Requirements in the Formulation of a Five-Level Selective Harmonic Elimination Pulse-Width Modulation Technique

Abstract

Abstract-Selective harmonic elimination pulse width modulation (SHE-PWM) techniques offer a tight control of the harmonic spectrum of a given voltage waveform generated by a power electronic converter along with a low number of switching transitions. These optimal switching transitions can be calculated through Fourier theory, and for a number of years quarter-wave and half-wave symmetries have been assumed when formulating the problem. It was shown recently that symmetry requirements can be relaxed as a constraint. This changes the way the problem is formulated, and different solutions can be found without a compromise. This letter reports solutions to the switching transitions of a five-level SHE-PWM when both the quarter-and half-wave symmetry are abolished. Only the region of high-modulation indices is reported since the low-modulation indices region requires a unipolar waveform to be realized. Selected simulation and experimental results are reported to show the effectiveness of the proposed method. Index Terms-Five-level inverter, inverter control, non-symmetrical pulsewidth modulation (PWM), selective harmonic elimination (SHE).

A Survey of Low Switching Frequency Modulation Techniques for Medium-Voltage Multilevel Converters

“…For multilevel waveforms, quarter-wave and half-wave symmetries are usually introduced [57]- [58]. On the other hand, non-symmetrical waveform selection leads to increased complexity as well as computation burden and thus seldom used [59]. The next step is to identify all the possible multilevel waveforms for a given number of switching angles.…”

Elimination of lower order harmonics in Voltage Source Inverter feeding an induction motor drive using Evolutionary Algorithms

“…They are extensively used in engineering design problems. The 5th and 7th harmonics are eliminated in the five level SHE PWM converters by optimal switching transition through the Fourier theory (Dohidah, Agelidis, & Rao, 2006).…”

Selective Harmonic Elimination PWM Control Scheme on a Three-Phase Four-Leg Voltage Source Inverter

“…An evaluation of SHE-PWM techniques for single-and three-phase two-level topologies was reported in [23]. There are many other articles dealing with the techniques for algorithms to obtain the solutions (switching angles) of trigonometric transcendental equations set [24]- [30] for various converter topologies [31]- [35] and for other optimizations [36]- [38].…”