Browsing by Keyword "selective harmonic elimination (SHE)"
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Item (2N+1) Selective Harmonic Elimination-PWM for Modular Multilevel Converters: A Generalized Formulation and A Circulating Current Control Method(2018-01) Pérez-Basante, Angel; Ceballos, Salvador; Konstantinou, Georgios; Pou, Josep; Andreu, Jon; De Alegría, Iñigo Martínez; POWER ELECTRONICS AND SYSTEM EQUIPMENTThe performance of modular multilevel converters (MMCs) in medium-voltage applications, where the number of required submodules is not high, can be improved utilizing low switching frequency modulations such as (2N+1) selective harmonic elimination-pulse width modulation (SHE-PWM), which provides tight control of lower order harmonics and low switching losses. This paper proposes a calculation method, which is based on a novel formulation, to solve the SHE-PWM problem. In particular, MMCs with (2N+1) phase output voltage levels are considered, obtaining a (2N+1) SHE-PWM waveform. This method utilizes a unique system of equations that is valid for any possible waveform. Therefore, it is able to calculate simultaneously, without predefined waveforms, both the switching patterns and the associated firing angles that solve the (2N+1) SHE-PWM problem. Consequently, the search process is simplified and optimized. Furthermore, this paper also proposes a circulating current control technique, which can be applied along with (2N+1) SHE-PWM without disturbing the phase output voltage. Simulation results and experimental tests obtained with a single-phase laboratory prototype prove the validity of the novel (2N+1) SHE-PWM implementation method and the proposed circulating current control technique.Item DC-Link Neutral Point Control for 3L-NPC Converters Utilizing Selective Harmonic Elimination-PWM(2022-09-01) Sanchez-Ruiz, Alain; Mazuela, Mikel; Fernandez-Rebolleda, Hector; Ceballos, Salvador; Perez-Basante, Angel; Ibanez-Hidalgo, Irati; Zubiaga, Markel; Pou, Josep; Beniwal, Neha; Konstantinou, Georgios; POWER ELECTRONICS AND SYSTEM EQUIPMENTSelective harmonic elimination-pulsewidth modulation (SHE-PWM) is a modulation technique widely used to improve the efficiency and harmonic content in medium-voltage high-power converters. Among these converters, the three-level neutral-point-clamped (3L-NPC) converter is one of the most utilized topologies. However, the 3L-NPC converter requires a proper balancing of dc-link capacitor voltages. This article presents a control technique, based on pulse shifting method, to regulate the neutral point voltage when SHE-PWM is utilized. The proposed technique performs well with any power factor and it can also be directly applied to T-type converters and easily extrapolated to other multilevel topologies. The proposed method is experimentally validated in a scaled-down power converter and a full-scale medium-voltage 3L-NPC converter.Item A Universal Formulation for Multilevel Selective-Harmonic-Eliminated PWM with Half-Wave Symmetry(2018-03-26) Pérez-Basante, Angel; Ceballos, Salvador; Konstantinou, Georgios; Pou, Josep; Kortabarria, Inigo; De Alegria, Inigo Martinez; POWER ELECTRONICS AND SYSTEM EQUIPMENTSelective-harmonic-eliminated pulsewidth modulation (SHE-PWM) can be utilized to improve the efficiency of multilevel voltage-source converters due to its ability to provide low switching frequency and tight control of low-order harmonics. In addition, SHE-PWM with half-wave (HW) symmetry provides a higher number of solutions than quarter-wave (QW) symmetry, and therefore, the waveform design can be improved. This work proposes a universal formulation, which can be utilized with HW symmetry, that provides a unique system of equations valid for any possible multilevel waveform. Thereby, without using predefined waveforms, this formulation provides the ability to search simultaneously both the firing angles and the switching patterns, simplifying significantly the search process and providing a high number of solutions. With the aim of selecting the optimum sets of firing angles, the solutions provided by HW and QW symmetries are compared, based on several metrics of harmonic performance, for particular test cases. Experimental results also validate the universal formulation with HW symmetry.