Elyas Zamiri | University of Tabriz (original) (raw)

Papers by Elyas Zamiri

In this paper, a novel configuration of the cascaded multilevel inverters using series connection... more In this paper, a novel configuration of the cascaded
multilevel inverters using series connection of new sub-multilevel
basic blocks is presented. The basic structure of the proposed
sub-multilevel inverter is made of three isolated batteries and eight unidirectional power switches. Hereby, by changing the polarity of
one of such batteries and two power switches, two different modules
of sub-multilevel inverters can be extracted that each of them is
able to be incorporated into two different cascaded structures as
the series basic blocks. Contemporary, to determine the suitable magnitudes of the integrated batteries, two different algorithms for
each topology along with their relevant mathematical analysis have
been also given. In this study, a complete comparison between the
proposed topologies and several recently presented structures has
been conducted. The compiled comparisons can prove the fact that both the proposed cascaded inverters are capable of generating a higher number of output voltage levels with less number of switching counts. Other advantages of these structures are reduction of voltage sources numbers, DC sources variety, value of total blocking voltage, and also conducting losses. In order to demonstrate the correct operation of the proposed structures and presented algorithms, some
experimental results will be also shown

In this paper, a new high step-up DC/DC converter for renewable energy systems is proposed, which... more In this paper, a new high step-up DC/DC converter for
renewable energy systems is proposed, which provides high voltage
gain by using a coupled inductor without having to have high-duty
cycle and high-turn ratio. Moreover, the voltage gain increased by
using capacitors charging techniques. In the proposed converter, the
energy of leakage inductors of the coupled inductor is recycled to
the load. This feature not only reduces stress on main switch but also
increases the converter efficiency. Also, due to the configuration of
the proposed structure, the voltage stress on the main switch is significantly reduced. Since the stress is low in this topology, low voltage
switch with small ON-state resistance value can be used to reduce
the conduction losses. As a result, losses decrease and the efficiency
increases. Meanwhile, the main switch is placed in series with the
source and it can control the flow of energy from source to load.
The operating principles and steady-state analysis of the proposed
converter are discussed in details. Finally, the prototype circuit with
12 V input voltage, 300 V output voltage, and 60 W output power is
operated to verify its performance

In this study a new high step-up dc-dc converter is presented. The operation of the proposed conv... more In this study a new high step-up dc-dc converter is presented. The operation of the proposed converter is based on the capacitor switching and coupled inductor with a single active power switch in its structure. A passive voltage clamp circuit with two capacitors and two diodes is used in the proposed converter for elevating the converter's voltage gain with the recovered energy of the leakage inductor, and for lowering the voltage stress on the power switch. A switch with a low (on) DS R can be adopted to reduce conduction losses. In the generalized mode of the proposed converter, to reach a desired voltage gain, capacitor stages with parallel charge and series discharge techniques are extended from both sides of secondary side of the coupled inductor. The proposed converter has the ability to alleviate the reverse recovery problem of diodes with circuit parameters. The operating principle and steady-states analyses are discussed in detail. A 40W prototype of the proposed converter is implemented in the laboratory to verify its operation.

A high-step-up DC/DC converter for renewable energy systems is proposed. The proposed structure p... more A high-step-up DC/DC converter for renewable energy systems is proposed. The proposed structure provides high voltage gain by using a coupled inductor without the need for high duty cycles and high turn ratios. The voltage gain is increased through capacitor-charging techniques. In the proposed converter, the energy of the leakage inductors of the coupled inductor is reused. This feature reduces the stress on the switch. Therefore, a switch with low ON-state resistance can be used in the proposed converter to reduce losses and increase efficiency. The main switch is placed in series with the source. Therefore, the converter can control the energy flow from the source to the load. The operating principle is discussed in detail, and a steady state analysis of the proposed converter is conducted. The performance of the proposed converter is verified by experimental results.

In this study, a new type of cascaded modular multilevel inverters (CMMLIs) is presented which is... more In this study, a new type of cascaded modular multilevel inverters (CMMLIs) is presented which is able to produce a considerable number of output voltage levels with a reasonable number of components. Accordingly, each series stage of the proposed CMMLI is comprised of two same basic units that are connected with each other through two unidirectional power switches without aiming any of the full H-bridge cells. In addition, since the potentiality for generating a higher number of output voltage levels in CMMLIs hinges on the magnitude of the dc voltage sources used in each series unit, in the rest of this paper, four different algorithms for determining an appropriate value for the dc sources' magnitude are also presented. In the following, a comprehensive topological analysis between some CMMLI structures reported in the literature and proposed structure along with several simulation and experimental results will be also given to validate the lucrative benefits and viability of the proposed topology.

—In this paper, initially a new dc/dc converter is proposed which can produce boosted multiple dc... more —In this paper, initially a new dc/dc converter is proposed which can produce boosted multiple dc link voltages by using the novel switched-capacitor converter (SCC) and with reduced number of switches. In the proposed SCC, voltage of all capacitors is charged by binary asymmetrical pattern as self-balancing and without using any auxiliary circuits. The proposed SCC will boost the input dc power supply voltage without transformer by switching the capacitors in series and in parallel. Next, a new single phase switched-capacitor multilevel inverter (SCMLI) topology which uses the proposed SCC units as virtual dc links have been proposed. The proposed topologies reduce the number of power switches, diodes, isolated dc power supplies, size, and the cost of the system in comparison with conventional similar topologies. For example, by contribution of proposed SCMLI structure, 49 and 137 output voltage levels are made by only 14 and18 power switches and 3 and 4 isolated dc power supplies, respectively. To confirm the performance of proposed topology, various simulation results by PSCAD/EMTDC software and experimental tests are given.

— One of the important applications of power electronic converters is in low power Renewable Ener... more — One of the important applications of power electronic converters is in low power Renewable Energy Generation Systems (REGS). In this paper a new application for single phase grid connected switched capacitor multilevel inverter in REGS has been proposed. According to control strategy and Seri-parallel switching of semiconductors, it has controllable output voltage amplitude with low total harmonic distortion in compare with similar topologies, and it does not have any complicated algorithm for balancing the capacitors voltage, respectively. In this study, a powerful method for maximum power point tracking (MPPT) under mismatching condition and grid-connected PV principles, based on 5-level inverter extracted from proposed general Switched Capacitor Multilevel Inverter (SCMLI) topology, is recommended. In this case, due to boost inherent capability of proposed SCMLI, the conventional dc/dc converter which usually used in the PV modules array to reinforce the input dc voltage has been removed. Hereby proposed MPPT strategy can track the maximum power of PV module directly on the basis of changing the provided phase difference between the inverter voltage and grid. In the rest of the paper, various simulation results by PSCAD/EMTDC software are presented to show the effectiveness of the proposed technique.

Nowadays, reduction in number of dc voltage sources alongside boosting property of the output vol... more Nowadays, reduction in number of dc voltage sources alongside boosting property of the output voltage with reduced circuit components are counted as the most important topological features for the new structures of multilevel voltage source inverters. Considering the above, this study presents a new configuration of such converters which can produce a step-up 19-level waveform of the output voltage with a contribution of only two same (symmetric) values of dc voltage sources and 12 power switches. The proposed structure is composed of a switched-capacitor (SC) and a floating-capacitor-based (FCB) cell integrated into two isolated sub-units that have been series with each other as an hybridised platform. Herein, the relevant involved switches of the SC and FCB sub-units are modulated on the basis of an hybridised pulse width modulation technique which facilitates a significant degradation in the total power loss dissipation. An appropriate boosting feature with a self-charge balancing capability of all integrated capacitors, reasonable number of required semiconductor devices, higher efficiency and less complexity are other advantages of the proposed step-up 19-level inverter. To verify the precise performance of the proposed topology under different types of loading conditions, apart from the theoretical analysis, several simulation and experimental results will also be presented.

—In this paper, a novel platform for the single phase switched-capacitor multilevel inverters (SC... more —In this paper, a novel platform for the single phase switched-capacitor multilevel inverters (SCMLIs) is presented. It has several advantages over the classical topologies, such as an appropriate boosting property, higher efficiency, lower number of required dc voltage sources, and other accompanying components with less complexity and lower cost. The basic structure of the proposed converter is capable of making nine-level of the output voltage under different kinds of loading conditions. Hereby, by using the same two capacitors paralleled to a single dc source, a switched-capacitor (SC) cell is made that contributes to boosting the value of the input voltage. In this case, the balanced voltage of the capacitors can be precisely provided on the basis of the series– parallel technique and the redundant switching states. Afterward, to reach the higher number of output voltage levels, two suggested SC cells are connected to each other with a new extended configuration. Therefore, by the use of a reasonable number of required power electronic devices, and also by utilizing only two isolated dc voltage sources, which their magnitudes can be designed based on either symmetric or asymmetric types, a 17-and 49-level of the output voltage are obtained. Based on the proposed extended configuration , a new generalized version of SCMLIs is also derived. To confirm the precise performance of the proposed topologies, apart from the theoretical analysis and a complete comparison, several simulation and experimental results are also given.

This paper presents a new family of cascaded multilevel inverters (CMLIs) which can generate a co... more This paper presents a new family of cascaded multilevel inverters (CMLIs) which can generate a considerable number of output voltage levels with minimum number of required accompanying switching devices. Conceptually, each stage of proposed CMLI is composed of using a novel capacitor-based unit including two floating capacitors, one embedded dc voltage source and three power switches. In this case, the balanced voltage of integrated capacitors can be precisely provided as self-voltage balancing without using any auxiliary circuits, close loop systems and intricate modulation techniques. In addition, to reach different number of output voltage levels, four different algorithms pertaining to the symmetrical, binary asymmetrical, trinary asymmetrical and also hybrid patterns for determining the magnitude of isolated dc voltage sources are presented. Hereby, proposed hybrid structure is capable of working under mixed switching frequency without aiming the conventional full H-Bridge cell. Therefore, a high quality of output waveforms with reduced switching devices as well as power loss dissipation can be alternatively achieved. To confirm the validity of proposed CMLI, a complete comparison with several recently presented topologies besides several simulation and experimental results based on trinary asymmetrical and hybrid evolved structures will be also given.

Because of many features of multilevel inverters, its applications in industries are not negligib... more Because of many features of multilevel inverters, its applications in industries are not negligible. This paper proposes a new topology for multilevel inverters that has been obtained from series blocks of sub multilevel inverter. One of the issues in this kind of inverters is quantity of switches. The proposed inverter consists of fewer number of power electronic switches which leads to lower switching loss, weight, and cost in comparison with conventional inverters. Another advantage of this structure is its modular capability. In this paper, three algorithms are considered to determine the size of DC voltage source and eventually accuracy of proposed inverter has been approved by PSCAD/EMTDC software.

Multilevel inverters with less number of components and power supplies play important role in mos... more Multilevel inverters with less number of components and power supplies play important role in most of power electronic applications. In this paper, a new switched capacitor multilevel inverter (SCMLI) is presented which can generate more output voltage levels with less number of components and one required dc power supply in contrast to some of existing topologies. This structure uses a new switched capacitor converter (SCC) which includes several capacitors that can be charged by binary asymmetrically algorithm as self-balancing. At the next, proposed SCMLI is connected to another SCMLI unit as hybrid form and then, the output voltage levels are increased with good quality using hybrid modulation technique. Several simulation results by PSCAD/EMTDC software and comparisons in different aspects such as number of required switches, capacitors, number of components that are in current path and total blocked voltage is given to confirm the effectiveness of proposed topology.

—The aim of this paper is to present a new 6 structure for switched-capacitor multilevel inverter... more —The aim of this paper is to present a new 6 structure for switched-capacitor multilevel inverters 7 (SCMLIs) which can generate a great number of voltage 8 levels with optimum number of components for both sym-9 metric and asymmetric values of dc-voltage sources. The 10 proposed topology consists of a new switched-capacitor 11 dc/dc converter (SCC) that has boost ability and can charge