Multilevel inverter with improved basic unit structure for symmetric and asymmetric source configuration

Abstract

An improved multilevel inverter (MLI) topology using a new basic unit structure with a reduced number of components is proposed in this study. Its single compact module is made up of two basic units connected to the left and right sides of a packed H-bridge. The topology produces 9-Level output when operated symmetrically and 17-Level output when operated asymmetrically. Identical magnitude of DC sources is used for the symmetrical operation, while non-identical magnitudes in a trinary sequence are used for the asymmetrical operation. The low-frequency modulation scheme is applied for the switching control where the switching angles are pre-calculated. The mathematical formulations for the switching are also considered to reduce the total harmonic distortion (THD) at the output. The proposed topology is also found to be superior in terms of the required number of switches per output level and total blocking voltage compared to conventional and recently reported MLIs. With these merits, real-time installation of the proposed topology will potentially require lesser space and become cheaper. The feasibility of the proposed topology is validated for its 9-Level and 17-Level operations through experimental verification on output characteristics, THD, blocking voltage, power-sharing and efficiency.

New Asymmetrical Modular Multilevel Inverter Topology With Reduced Number of Switches

“…This configuration's main benefit is using lesser active and passive components to achieve high output levels. Many topologies are recently developed based on the optimal utilization of unequal dc sources by the least number of power components [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30].…”

“…The problem mentioned above has been solved in [17][18][19][20][21][22][23][24][25][26][27][28][29], where the MLIs are developed without using H-bridge that inherently produces both positive and negative voltage levels.…”

Implementation and Analysis of a 15-Level Inverter Topology With Reduced Switch Count

“…It leads to an increment in the total standing voltage (TSV) of the structure as well as an increment in overall topology cost. Based on the reduced switches concept, similar topologies have also been proposed in [17]- [19]. Exemplar topologies employing four dc sources (a) MLI producing 13 levels proposed by Samadei et al [11], (b) 17-level MLI proposed in Samadei et al [12], (c) Alishah et al [14] MLI producing 17 levels, (d) 17-level MLI proposed in Saeedian et al [15].…”

“…Exemplar topologies employing four dc sources (a) MLI producing 13 levels proposed by Samadei et al [11], (b) 17-level MLI proposed in Samadei et al [12], (c) Alishah et al [14] MLI producing 17 levels, (d) 17-level MLI proposed in Saeedian et al [15]. A topology with both symmetrical and asymmetrical operating capabilities generating 9 levels and 17 levels respectively is presented by Hamidi et al [17]. A high level per component ratio topology suggested in [18] and verified for performance and design parameters with multiple dc sources is suitable for PV applications.…”

Three-Phase Six-Level Multilevel Voltage Source Inverter: Modeling and Experimental Validation

“…The aforementioned method has been utilized to propose different three-phase cascaded MLI topologies which are presented in [ 18 , 19 , 20 ]. To further decrease the overall amount of DC supplies and switches in these topologies, a new multilevel inverter configuration has been recently suggested in [ 21 , 22 , 23 , 24 ]. These MLIs were built by utilizing the combination of a twelve-switch three-phase Bridge and a multilevel DC-link.…”