This paper proposes a single-phase five-level INVERTER with a modified pulse width-modulated (PWM) control scheme. The modified pulse width-modulation technique is developed to reduce switching losses. Also, the proposed MULTILEVEL INVERTER can reduce the requirement of power switches compared to a conventional CASCADED MULTILEVEL INVERTER. The modes of operation, control signals, and operating principle of the proposed INVERTER are analyzed. The INVERTER is capable of producing five levels of output-voltage (Vs, Vs / 2, 0, − Vs, − Vs/2) from the dc supply voltage. In particular, aspects of total harmonic distortion (THD) for the proposed MULTILEVEL converters are discussed. The hybrid CASCADED H-Bridge INVERTER with very low switching losses is ideal for such operations. The behaviour of the INVERTER has been analyzed with the simulation and experimental results. In this paper a new five level INVERTER with reduced number of switches is proposed and MATLAB/SIMULINK results are presented.

In this paper, a new structure for cascade MULTILEVEL INVERTER is presented which consists of a series connection of several sub-MULTILEVEL units. Each sub-MULTILEVEL unit comprises of eight unidirectional switches, two bidirectional switches, and six DC voltage sources. For the proposed cascade topology, two algorithms are presented to produce all possible levels at the output voltage waveform. The required analysis of the voltage rating on the switches is provided. In order to verify the performance of the proposed INVERTER, the experimental results for a 15-level INVERTER are provided. The experimented 15-level INVERTER is compared with the other presented INVERTERs in literature in terms of the number of DC voltage sources, switches, drivers, and blocked voltage by switches. The results of comparisons indicate that the experimented 15-level INVERTER requires lower power electronic elements. Moreover, the blocked voltage on the switches of the proposed topology is less than other topologies.

In this paper, a new basic unit is proposed for MULTILEVEL INVERTERs. Then, a series connection of the proposed basic unit is used to recommend a new topology for MULTILEVEL INVERTERs. To determine the magnitude of dc voltage sources, a new algorithm is presented. For the proposed algorithm, different performance parameters such as total voltage rating of switches (TVRS), number of gate drivers, and number of required sources are calculated as a function of the number of output voltage levels and are compared with other topologies. The comparison proves that the proposed CASCADED topology requires fewer components and gate driver circuits than most of the other conventional topologies. Moreover, the voltage rating of switches is less than the other topologies which result lower cost and control complexity. Finally, the correctness of the theoretical analysis and the performance of the proposed INVERTER are verified using the laboratory and simulation results under different scenarios.

In low switching frequency strategies, regulated DC sources along with the switching angles increase the system’ s degrees of freedom to effectively mitigate or eliminate harmonics. Utilizing the variable DC sources increase the cost, losses and complexity of the system. This paper presents a new method for CASCADED H-bridge MULTILEVEL INVERTERs based on discrete variable DC source to reduce number of the regulated DC sources. In this paper, an optimization procedure for output voltage regulation is devised based on the discrete variable DC sources, which results in effective reduction of harmonics and improvement of the output voltage quality. In the optimization method, the near optimum values of DC sources and switching angles are obtained using multi objective genetic algorithm. To verify the feasibility of the new solution, a laboratory prototype is implemented based on seven level CASCADED H-bridge INVERTER with three cells in each phase. Simulation and experimental results validate the effectiveness of the proposed method based on the discrete variable DC sources in reduction of harmonics and voltage regulation.

In this paper, several optimum structures of a CASCADED MULTILEVEL INVERTER is proposed. This optimization is based on generation a constant number of output voltage levels by using minimum number of power switches or dc voltage sources or minimum amount of blocked voltage by power switches. In addition, the optimum structure for a constant number of dc voltage sources by using minimum number of power switches is obtained. In these optimizations, all of the presented algorithms to generate a desired sinosuidal waveform of the CASCADED MULTILEVEL INVERTER are considered. Then, the proposed optimum topologies are compared with several conventional CASCADED MULTILEVEL invereters that have been presented in literature. These comparisons are from the number of required power switches, dc voltag sources, variabilty the magnitude of dc voltage source and the value of blocked voltage by switches points of view. The conduction and switching losses of the proposed topologies are calculated. In addition, a 49-level CASCADED INVERTER based on the proposed optimum topologies is designed. Moreover, the designed topologies are compared to each other from the amount of blocked voltage by swithes, the maximum magnitude of output voltage levels and the number of required power electronic devices such as power switches, driver circuits and diodes points of view. Finally, the ability of the optimium topology in generation all voltage levels (even and odd) by using minimum number of power switches is reconfirmed thruogh PSCAD/EMTDC simulation and experimental results on a 49-level INVERTER.

This paper presents the comparative study of three phase twenty five level diode clamped and CASCADED H-bridge MULTILEVEL INVERTERs. The comparison is made in respect of requirement of devices, quality of output voltage and reduction of total harmonic distortion at the MULTILEVEL INVERTER terminals. In this work multicarrier sinusoidal pulse modulation control methods of Phase disposition (PD-PWM), phase opposition disposition (PODPWM) and Alternative Phase Opposition Disposition (APOD-PWM) pulse width modulation control strategies are applied for both diode clamped and CASCADED H-bridge MULTILEVEL INVERTERs and compared its total harmonic distortion. The performance of both diode and CASCADED H-bridge MULTILEVEL INVERTERs is investigated and compared. Based on simulation results it is observed that the output voltage of the CASCADED H-bridge MULTILEVEL INVERTERs is better as compared to the diode clamped MULTILEVEL INVERTER. The proposed MULTILEVEL INVERTERs are simulated using MATLAB/Simulink software.

MULTILEVEL INVERTERs are a new generation of DC-AC converters at medium and high voltage and power levels. In this paper, a new single-phase CASCADED MULTILEVEL INVERTER is presented. For this purpose, a basic cell is first presented and then by series connection of these cells, the new MULTILEVEL INVERTER structure is presented. The proposed new cell is only capable of generating positive voltage levels, and therefore, to produce zero and negative voltage levels, the proposed structure is constructed based on H-bridge module. A comprehensive comparison is carried out between the proposed MULTILEVEL INVERTER with the classical and recently introduced structures in terms of the number of switching devices, the number of drivers, the total blocking voltage of the switches as well as the loss and efficiency. The accuracy of the proposed INVERTER’ s performance is simulated in Matlab/Simulink in symmetric and asymmetric topologies fora 21-level and 37-level output voltage respectively, and then evaluated by the laboratory prototype.

In this paper, a new topology for CASCADED MULTILEVEL INVERTER based on quasi-Zsource converter is proposed. In the proposed topology the magnitude of output DC voltage is not limited to the sum of magnitude of DC voltage sources. Moreover, the reliability of the circuit due to capability of short circuit by Z-source network is increased. The quasi-Zsource converter in different modes is analyzed and the voltage gain is obtained. Also, the values of quasi-Z-source network components are designed. In the proposed topology, the number of DC voltage sources, the number of switches, installation area and cost in comparison with conventional MULTILEVEL INVERTERs are significantly reduced. Three algorithms to determine the magnitude of DC voltage sources are proposed. Then the optimal structures for the minimum number of switches and DC voltage sources to generate the maximum voltage levels are presented. Moreover, the control method for the proposed topology is described. To verify the performance of the proposed topology, simulation and experimental results of proposed topology are presented.

A new CASCADED MULTILEVEL transformerless INVERTER topology is introduced in this paper for connecting DG sources to power utility. Usual transformerless circuits are designed based on current injection capability, current harmonic minimization, and some physical constraints like isolation between DG and the network. The proposed circuit of this paper can compensate the current harmonic of the nonlinear load (as in APFs) and inject maximum possible active power as a DG source interface, simultaneously. A fuzzy controller is proposed to adjust the optimal set point of INVERTER between compensating mode and maximum active power injection mode. Proposed scheme is simulated in MATLAB/SIMULINK to evaluate the circuit performance both in the maximum active power injection mode, and harmonic compensation mode. Then a 1 kw single phase prototype of the circuit is used for experimental evaluation of the paper. Both simulative and experimental results prove that such a circuit can inject a well-controlled current with desired harmonics and THD, while having a smaller switching frequency and better efficiency, related to previous 3-phase INVERTER schemes in the literature.