Showing 9 results for Multilevel Inverter
R. Naderi, A. Rahmati,
Volume 4, Issue 4 (12-2008)
Abstract
Multilevel PWM waveforms can be decomposed into several multilevel PWM
components. Phase-shifted carrier (PSC) is an efficient decomposition technique. In this
paper, we have first demonstrated the equality of PSC and alternative phase opposition
disposition techniques. Second, we have modified PSC to accommodate other disposition
techniques. Third, we have investigated the effects of using asymmetrical carriers on the
spectrum of the resulting PWM waveform. Fourth, we have proposed a logical algorithm
for decomposing all types of multilevel PWM waveforms.
S. Laali, E. Babaei, Z. Saadatizadeh,
Volume 12, Issue 3 (9-2016)
Abstract
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.
E. Babaei, T. Ahmadzadeh,
Volume 13, Issue 4 (12-2017)
Abstract
First of all, in this paper, the topology and operation of the three-phase three-level Z-source inverter based on neutral-point-clamped (Z-NPC) are studied. Moreover, different combinations of permissible switching states and control signals are explained for this inverter. In this paper, the topology of the three-phase three-level Z-NPC inverter is extended for an n-level state. Also, a combination of allowed switching states with relevant mathematical equations is presented for the proposed n-level Z-NPC inverter. In comparison with multilevel voltage-source inverters (only voltage-boost capability), the proposed multilevel Z-NPC inverter is a single-stage converter and it has a buck-boost capability of voltage. On the other hand, the control of two-stage converters compared to single-stage converters can be more difficult because of existing more active and passive components. In this paper, two new PWM control methods are also proposed for various multilevel Z-NPC inverters. One advantage of the proposed PWM control methods in comparison with conventional PWM control methods is maintaining the charge balance of the dc-link capacitors in neutral point. The correct performance of the proposed multilevel Z-NPC topology and PWM control methods are verified by the obtained results of analysis and simulations performed in the PSCAD software.
S. R. Sadu, P. V. Prasad, G. N. Srinivas,
Volume 14, Issue 1 (3-2018)
Abstract
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 (POD-PWM) 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.
E. Babaei, M. Shadnam Zarbil, E. Shokati Asl,
Volume 15, Issue 1 (3-2019)
Abstract
In this paper, a new topology for cascaded multilevel inverter based on quasi-Z-source 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-Z- source 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.
F. Masoudinia, E. Babaei, M. Sabahi, H. Alipour,
Volume 16, Issue 1 (3-2020)
Abstract
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.
H. Toodeji,
Volume 16, Issue 1 (3-2020)
Abstract
This paper proposes a hybrid switching technique for a domestic PV system with AC-module architecture. In this PV system, independent control of PV modules, which are directly connected to DC terminals of a single-phase cascaded multilevel inverter, makes module-level MPPT possible to extract maximum available solar energy, especially in partial shading conditions. As one of the main contributions, the proposed hybrid method employs a fundamental-based switching technique to decrease power losses, which directly affect the efficiency of solar energy conversion. In addition, fast dynamic response of the introduced hybrid technique lets the PV system to harvest more power in partial shading conditions. Producing a waveform with minimized THD in steady-state conditions is another advantage of the proposed switching technique. In this paper, the advantages of the proposed hybrid method are verified by the simulation of a test PV system with both conventional SPWM and proposed switching techniques in MATLAB/Simulink under various partial shading conditions.
S. Shabani, M. Asadi, A. Zakipour,
Volume 19, Issue 1 (3-2023)
Abstract
In this paper, parasitic capacitors and common mode voltage (CMV) are modeled in a delta connection multilevel cascaded STATCOM. In high frequency and high voltage applications the parasitic capacitors play important role in common mode voltages. In this paper, parasitic capacitors and CMV are modeled in a multilevel cascaded STATCOM and also parasitic currents are calculated, then a method will be proposed to reduce the effects of the parasitic capacitors. The values of parasitic capacitors are calculated by finite element software. Finally, a delta connection 13-level cascaded STATCOM with parasitic capacitors will be simulated in MATLAB Simulink and then simulation results will be presented.
S. M. Ahmed, K. S. Ahmed, Y. M. Shuaib,
Volume 19, Issue 1 (3-2023)
Abstract
This article discusses the operating principle and simulation of closed loop control of a three phase induction motor (IM) powered by five level diode clamped multilevel inverter (DCMLI) using direct torque control (DTC) technique. The main purpose of this article is to regulate the torque and speed of an IM and to decrease total harmonic distortion (THD). In this article, a five-level inverter's direct modulation approach with the dc link voltage self-balancing is presented. To reduce capacitor voltage variation, the redundancies of various switch topologies for the creation of intermediate voltages are also used. The use of LC filter results in lower output voltage and current distortion. A multicarrier PWM control technique is used for DCMLI to provide high quality sinusoidal output voltage with decreased harmonics. This can be obtained by employing Sinusoidal Pulse Width Modulation (SPWM) method for speed and torque control. This demonstrates that the recommended method of controlling the motor's speed and torque is effective. The simulation result reveals that DTC for the five-level inverter fed IM drive gives a rapid dynamic response, lower voltage and current THDs, and much less flux and torque distortion. The simulation is carried out in MATLAB Simulink (R2014).
