Five-Level Selective Harmonic Elimination PWM Strategies and Multicarrier Phase-Shifted Sinusoidal PWM: A Comparison

Abstract

The multicarrier phase-shifted sinusoidal pulsewidth modulation (MPS-SPWM) technique is well-known for its important advantage of offering an increased overall bandwidth as the number of carriers multiplied with their equal frequency directly controls the location of the dominant harmonics. In this paper, a five-level (line-to-neutral) multilevel selective harmonic elimination PWM (MSHE-PWM) strategy based on an equal number of switching transitions when compared against the previously mentioned technique is proposed. It is assumed that the four triangular carriers of the MPS-SPWM method have nine per unit frequency resulting in seventeen switching transitions for every quarter period. Requesting the same number of transitions from the MSHE-PWM allows the control of sixteen non-triplen harmonics. It is confirmed that the proposed MSHE-PWM offers significantly higher converter bandwidth along with higher modulation operating range. Selected results are presented to confirm the effectiveness of the proposed technique.

Five-level active NPC converter topology: SHE-PWM control and operation principles

“…The five-level SHE-PWM strategy is proposed in [11] where seventeen angles were considered for the first quarter wave cycle of the line-to-neutral voltage waveform as shown in Figure 3. In a generalized form, the set of equations that need to be solved is as follows:…”

“…The ANPC VSC allows a significant improvement of unequal loss distribution among the switches [7], [8]. This paper reports on the suitability of a recently presented novel five-level symmetrically defined SHE-PWM method proposed in [11] through its implementation in the five-level three-phase ANPC converter topology proposed in [6].The paper is organized in the following way: Section 2 presents the five-level ANPC converter topology operational principles and control. The simulation results obtained by implementing a five-level SHE-PWM method in the five-level three-phase ANPC converter topology are presented in section 3 and conclusions are summarized in section 4.…”

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

“…The problem defined by (4)-(6) can be solved using any of the techniques that have been previously applied to the case of the more restrictive quarter-wave symmetry problem, including iterative approaches [6], [7], resultant theory [5], minimization techniques [2], [3], and [15] or genetic algorithms [4], [9], and [10]. Any sets of solutions resulting from the case where the quarter-or half-wave symmetry are followed will also be a solution to the more generalized formulation proposed in this letter.…”

“…It is worth noting that the proposed method is investigated at high modulation indices only; it is implied that the low-modulation indices are satisfied with a three-level SHE-PWM technique which has been addressed in [15]. Therefore, the modulation indices in this letter will be searched from 1 to 2 (i.e., 1 2), although there is no guarantee that solutions will be found for the entire interval.…”

“…Other approaches have also been reported including one where harmonic elimination is combined with a programmed method [4] and another where a criterion based on power equalization between various cascaded connected H-bridge multilevel converters is used to obtain the angles of the harmonic elimination method [14]. More recently, multilevel SHE-PWM defined by the wellknown multicarrier phase-shifted PWM (MPS-PWM) was proposed in [15] where the modulation index defines the distribution of the switching angles. The problem of SHE-PWM is then applied to a particular operating point aiming to obtain the optimum position of these switching transitions that offers elimination to a selected order of harmonics.…”