1,720,999 research outputs found
High step‐up high step‐down bidirectional DC/DC converter
No full textIn this study, a new high step-up high step-down bidirectional dc-dc converter is proposed. In the proposed converter, the voltage conversion ratio is increased by using two coupled inductors and switched capacitor circuit in both boost and buck operations. The proposed bidirectional converter in comparison with other presented high-voltage gain boost converters with two coupled inductors in the literature has the highest voltage conversion ratio. In this study, the proposed topology is analysed in all operating modes and the current and voltage stresses of all switches, voltage gain and maximum and minimum current through the inductors are calculated for both boost and buck operations. Finally, the accuracy of the obtained analytical results and correct operation of the proposed converter are verified through PSCAD/EMTDC simulation and experimental results
New 8-Level Basic Structure for Cascaded Multilevel Inverters with Reduced Number of Switches and DC Voltage Sources
No full text Multilevel inverters are generally used in medium-voltage and high-power applications. In this paper, a new 8-level basic structure for cascaded multilevel inverters is proposed. Based on proposed basic structure, two different cascaded multilevel topologies are proposed. The proposed cascaded multilevel inverters use less number of power switches, IGBTs and dc voltage sources compared with the conventional multilevel inverters. In order to generate all steps at the output voltage, three different algorithms to determine the amplitudes of dc voltage sources are presented. To reconfirm the performance and correct operation of the proposed topologies, the experimental results for a 15-level inverter are presented. </jats:p
A new topology for cascaded multilevel inverters with reduced number of power electronic switches
No full textIn this paper, a new basic unit for cascaded multilevel inverter is proposed. The proposed basic unit consists of m cells. Each cell can generate three levels. The proposed multilevel inverter is based on series connection of several basic units. The proposed multilevel inverter is investigated at both symmetric and asymmetric topologies. In order to generate all voltage levels at the output, four algorithms to determine the magnitudes of dc voltage sources are proposed. Reduction of number of power switches, driver circuits and IGBTs are some advantages of the proposed cascaded multilevel inverter. Finally, to verify the correctness operation of the proposed inverter, the simulation results of a 27-level inverter based on proposed topology by using PSCAD/EMTDC software are used
Three-Port High Step-Up and High Step-Down DC-DC Converter with Zero Input Current Ripple
Full text linkIn this article, a nonisolated three-port dc-dc converter with high voltage conversion ratio is proposed. In the proposed converter, by changing the place of input voltage source between each of the three ports, three different single-input two-output operation modes are achieved. The input current ripple of the proposed converter is eliminated at the low voltage side for the whole range of duty cycles. The voltage conversion ratios of the proposed converter can be increased by increasing the turns ratio of second winding of coupled inductors. Moreover, the proposed converter has achieved proper output voltage regulations for all output ports, simultaneously. The proposed converter can be utilized in the renewable energy conversion systems such as in photovoltaic and fuel cells. In this article, the voltage conversion ratios of the output ports, the voltage stress on switches, the average currents of switches and inductors, and the required condition for cancelling input current ripple at low voltage side are calculated theoretically. The theoretical results are verified and experimental results for 24 V input voltage and 304 V, 240 V output voltages with 400 W power are extracted for two different operation modes.</p
Four-phase isolated DC-DC converter
No full textThis paper proposes a new four-phase isolated DC-DC converter that can be used in renewable energy sources such as batteries, photovoltaic, and fuel cell systems. This converter is suitable for industrial applications that require high voltage and power. A four-phase high-frequency transformer is used for isolation and increasing voltage. The most important feature of this converter is reducing current ripple of the power source. Moreover, the proposed converter considerably decreases the load voltage ripple. The current passing through the switches and passive elements is low, too. The converter is analyzed in four regions. Each of these regions is distinguished by the maximum number of switches that are simultaneously turned on in each switching period. Finally, the accuracy operation of the proposed converter is reconfirmed by the simulation results
Analysis of Z-source based DC/DC converter in CCM, DCM and BCM operations
No full textDesign of dc/dc converters depends on its analysis in different operating modes. By changing the values of elements and existing conditions, the type of operating modes is changed and may the expected results cannot achieve. Therefore, the operating mode of converter should be determined. In this paper, the comprehensive analysis of Z-source based dc/dc converter in continuous conduction mode (CCM), discontinuous conduction mode (DCM) and boundary conduction mode (BCM) are presented. The voltage and current waveforms of the converter elements are shown in DCM and the minimum value of the inductance for BCM is calculated. The maximum current and voltage stresses on power switch and also the capacitor voltage ripple are calculated. Moreover, designing of the elements is done to determine of optimal operation in CCM. Finally, the simulation results by using PSCAD/EMTDC software are presented to prove the validity of the theoretical subjects
Coupled-inductor based multilevel inverter
No full textIn this paper, a new hybrid coupled inductor multilevel inverter (HCIMLI) is proposed. The common characteristic of the coupled inductor inverters is to provide parallel paths for the output current. Therefore, the switching devices operate in lower current rate compared to the rated output current. By this method, it is possible to use low-current switching devices for the high-current applications. The proposed topology can be developed to generate any number of output voltage levels. This allows designing the proposed topology based on the desired current rating of the switches. Moreover, increasing the number of the levels improves the quality of output voltage and current. In the proposed structure with m units, rated current of the switching devices can be reduced to 1/4m of the rated output current. In the 9-level structure of the HCIMLI, half of the switches operate in a rated current of as low as one fourth of the rated output current. The proposed topology is verified by simulation results performed in PSCAD/EMTDC software environment
A new basic unit for symmetric and asymmetric cascaded multilevel inverter with reduced number of components
No full textThis study suggest a new basic structure for symmetric and asymmetric cascaded topologies with reduced number of power electronic components. This topology generates 10 voltage steps by three unequal dc voltage sources and seven switches. The suggested topology creates just positive and zero voltage steps and it needs to one H-bridge to generate negative voltage levels. Based on the located H-bridge, two different cascaded multilevel topologies are proposed. Also, various methods to specify the magnitudes of dc voltage sources are suggested. The proposed cascaded multilevel inverters in comparison with the conventional cascaded topologies and other new topologies which presented in literature decrease the number of components such as, IGBTs, switches, driver circuits and DC links. PSCAD/EMTDC simulations results of 19-level inverter are presented to reconfirm the correct performance of the suggested topologies
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