scholarly journals X-Type Step-Up Multi-Level Inverter with Reduced Component Count Based on Switched-Capacitor Concept

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1987
Author(s):  
Erfan Azimi ◽  
Aryorad Khodaparast ◽  
Mohammad Javad Rostami ◽  
Jafar Adabi ◽  
M. Ebrahim Adabi ◽  
...  
Keyword(s):  
Power Flow ◽  
Input Voltage ◽  
Switching Frequency ◽  
Switched Capacitor ◽  
Level Control ◽  
Voltage Balancing ◽  
Simulink Model ◽  
Wide Range ◽  
Multi Level ◽  
Laboratory Prototype

This paper aims to present a novel switched-capacitor multi-level inverter. The presented structure generates a staircase near sinusoidal AC voltage by using a single DC source and a few capacitors to step-up the input voltage. The nearest level control (NLC) strategy is used to control the operation of the converter. These switching states are designed in a way that they always ensure the self-voltage balancing of the capacitors. Low switching frequency, simple control, and inherent bipolar output are some of the advantages of the presented inverter. Compared to other existing topologies, the structure requires fewer circuit elements. Bi-directional power flow ability of the proposed topology, facilitates the operation of the circuit under wide range of load behaviors which makes it applicable in most industries. Besides, a 13-level laboratory prototype is implemented to realize and affirm the efficacy of the MATLAB Simulink model under different load conditions. The simulation and experimental results accredit the appropriate performance of the converter. Finally, a theoretical efficiency of 92.73% is reached.

scholarly journals Identification of DC Thermal Steady-State Differential Inductance of Ferrite Power Inductors

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3854
Author(s):  
Salvatore Musumeci ◽  
Luigi Solimene ◽  
Carlo Stefano Ragusa
Keyword(s):  
Steady State ◽  
Input Voltage ◽  
Switching Frequency ◽  
Ohmic Losses ◽  
Steady State Temperature ◽  
Wide Range ◽  
Average Current ◽  
Power Inductors ◽  
Saturable Inductor ◽  
Thermal Steady State

In this paper, we propose a method for the identification of the differential inductance of saturable ferrite inductors adopted in DC–DC converters, considering the influence of the operating temperature. The inductor temperature rise is caused mainly by its losses, neglecting the heating contribution by the other components forming the converter layout. When the ohmic losses caused by the average current represent the principal portion of the inductor power losses, the steady-state temperature of the component can be related to the average current value. Under this assumption, usual for saturable inductors in DC–DC converters, the presented experimental setup and characterization method allow identifying a DC thermal steady-state differential inductance profile of a ferrite inductor. The curve is obtained from experimental measurements of the inductor voltage and current waveforms, at different average current values, that lead the component to operate from the linear region of the magnetization curve up to the saturation. The obtained inductance profile can be adopted to simulate the current waveform of a saturable inductor in a DC–DC converter, providing accurate results under a wide range of switching frequency, input voltage, duty cycle, and output current values.

scholarly journals Step-Up Series Resonant DC–DC Converter with Bidirectional-Switch-Based Boost Rectifier for Wide Input Voltage Range Photovoltaic Applications

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3747 ◽  
Author(s):  
Abualkasim Bakeer ◽  
Andrii Chub ◽  
Dmitri Vinnikov
Keyword(s):  
Theoretical Analysis ◽  
Duty Cycle ◽  
Input Voltage ◽  
Voltage Regulation ◽  
Switching Frequency ◽  
Voltage Gain ◽  
Voltage Range ◽  
Dc Voltage ◽  
Wide Range ◽  
Series Resonant

This paper proposes a high gain DC–DC converter based on the series resonant converter (SRC) for photovoltaic (PV) applications. This study considers low power applications, where the resonant inductance is usually relatively small to reduce the cost of the converter realization, which results in low-quality factor values. On the other hand, these SRCs can be controlled at a fixed switching frequency. The proposed topology utilizes a bidirectional switch (AC switch) to regulate the input voltage in a wide range. This study shows that the existing topology with a bidirectional switch has a limited input voltage regulation range. To avoid this issue, the resonant tank is rearranged in the proposed converter to the resonance capacitor before the bidirectional switch. By this rearrangement, the dependence of the DC voltage gain on the duty cycle is changed, so the proposed converter requires a smaller duty cycle than that of the existing counterpart at the same gain. Theoretical analysis shows that the input voltage regulation range is extended to the region of high DC voltage gain values at the maximum input current. Contrary to the existing counterpart, the proposed converter can be realized with a wide range of the resonant inductance values without compromising the input voltage regulation range. Nevertheless, the proposed converter maintains advantages of the SRC, such as zero voltage switching (ZVS) turn-on of the primary-side semiconductor switches. In addition, the output-side diodes are turned off at zero current. The proposed converter is analyzed and compared with the existing counterpart theoretically and experimentally. A 300 W experimental prototype is used to validate the theoretical analysis of the proposed converter. The peak efficiency of the converter is 96.5%.

scholarly journals A Unified Controller for Multi-State Operation of the Bi-Directional Buck–Boost DC-DC Converter

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7921
Author(s):  
Gabriel R. Broday ◽  
Gilney Damm ◽  
William Pasillas-Lépine ◽  
Luiz A. C. Lopes
Keyword(s):  
Feedback Linearization ◽  
Power Flow ◽  
Negative Impact ◽  
Input Voltage ◽  
Operating Conditions ◽  
Modulation Scheme ◽  
Control Loops ◽  
Variable Control ◽  
Wide Range ◽  
The Right

DC grid interfaces for supercapacitors (SCs) are expected to operate with a wide range of input voltages with fast dynamics. The class-C DC-DC converter is commonly used in this application because of its simplicity. However, it does not work if the output voltage (V2) becomes smaller than the input voltage (V1). The non-isolated bi-directional Buck–Boost DC-DC converter does not have this limitation. Its two half-bridges provide a means for controlling the power flow operating in the conventional dual-state mode, as well as multi-state, tri, and quad modes. These can be used for mitigating issues such as the Right Half Plane (RHP) zero that has a negative impact on the dynamic response of the system. Multi-state operation typically requires multi-variable control, which is not easy to realize with conventional PI-type controllers. This paper proposes a unified controller for multi-state operation. It employs a carrier-based modulation scheme with three modulation signals that allows the converter to operate in all four possible states and eight different modes of operation. A mathematical model is developed for devising a multi-variable control scheme using feedback linearization. This allows the design of control loops with simple PI controllers that can be used for all multi-state modes under a wide range of operating conditions with the same performance. The proposed scheme is verified by means of simulations.

scholarly journals Influence of Power Losses in the Inductor Core on Characteristics of Selected DC–DC Converters

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1991 ◽  
Author(s):  
Krzysztof Górecki ◽  
Kalina Detka
Keyword(s):  
Nanocrystalline Material ◽  
Input Voltage ◽  
Load Resistance ◽  
Operating Conditions ◽  
Switching Frequency ◽  
Power Losses ◽  
Boost Converters ◽  
The Core ◽  
Operation Conditions ◽  
Wide Range

The paper presents the results of a computer simulation illustrating the influence of power losses in the core of an inductor based on the characteristics of buck and boost converters. In the computations, the authors’ model of power losses in the core is used. Correctness of this model is verified experimentally for three different magnetic materials. Computations are performed with the use of this model and the Excel software for inductors including cores made of ferrite, powdered iron, and nanocrystalline material in a wide range of load resistance, as well as input voltage of both the considered converters operating at different values of switching frequency. The obtained computation results show that power losses in the inductor core and watt-hour efficiency of converters strongly depend on the material used to make this core, in addition to the input voltage and parameters of the control signal and load resistance of the considered converters. The obtained results of watt-hour efficiency of the considered direct current (DC)–DC converters show that it changes up to 30 times in the considered ranges of the mentioned factors. In turn, in the same operating conditions, values of power losses in the considered cores change from a fraction of a watt to tens of watts. The paper also considers the issue of which material should be used to construct the inductor core in order to obtain the highest value of watt-hour efficiency at selected operation conditions of the considered converters.

scholarly journals An Eleven-Level Switched-Capacitor Inverter with Boosting Capability

Electronics ◽  
2021 ◽  
Vol 10 (18) ◽  
pp. 2262
Author(s):  
Md Reyaz Hussan ◽  
Adil Sarwar ◽  
Irfan Khan ◽  
Mohd Tariq ◽  
Mohammad Tayyab ◽  
...  
Keyword(s):  
Output Voltage ◽  
Detailed Comparison ◽  
Input Voltage ◽  
Voltage Source ◽  
Switched Capacitor ◽  
Level Control ◽  
Voltage Waveform ◽  
Dc Voltage ◽  
Bidirectional Switches ◽  
State Of Art

An 11-level switched-capacitor multilevel inverter (SCMLI) with 2.5 times boosting feature is presented in this paper. It can produce an 11-level output voltage waveform by utilizing 14 switches, 3 capacitors, 2 diodes, and 1 DC source. Only nine driver circuits are needed as the topology has three pairs of complementary switches and two bidirectional switches. It has inherent capacitor self-balancing property as the capacitors are connected across the DC voltage source during several states within a fundamental cycle to charge the capacitors to the input voltage. A detailed comparison shows the effectiveness of the proposed topology in terms of the number of switches, number of capacitors, number of sources, total standing voltage (TSV), efficiency, and boosting ability with the state-of-art recently proposed circuits. Subsequently, the performance of the proposed SCMLI is validated experimentally utilizing the nearest level control (NLC), a fundamental frequency-based switching technique.

scholarly journals Optimal Modulation Techniques of a DAB Based Isolated Bidirectional Single-stage Single-phase AC-DC Converter

2021 ◽  
Author(s):  
Dibakar Das ◽  
Kaushik Basu ◽  
Sayan Paul
Keyword(s):  
High Frequency ◽  
Power Flow ◽  
Degrees Of Freedom ◽  
Single Phase ◽  
Single Stage ◽  
Switching Frequency ◽  
Switching Loss ◽  
Two Stage ◽  
Wide Range ◽  
Bidirectional Power Flow

A bidirectional single-phase AC to DC converter with high-frequency isolation finds a wide range of applications, including charging electric vehicles in the vehicle to grid applications. A conventional two-stage solution, where an AC-DC front-end rectifier is connected to an isolated DC-DC converter, suffers from poor efficiency due to hard switching of the AC-DC stage and poor reliability due to the existence of an electrolytic capacitance at the interstage DC link. A Dual Active Bridge (DAB) based single-stage AC-DC converter with a potential of bidirectional power flow can overcome the problems of a two stage solution. A rich literature exists in search for finding an efficient modulation strategy for this converter. This paper presents two constant switching frequency modulation strategies that support bidirectional power flow at any power factor utilizing all three degrees of freedom in modulation, also known as triple phase-shift modulation (TPS). One of the strategies minimizes RMS high-frequency transformer current over the line cycle, and the other one optimizes peak current. Hence, the conduction loss and the component stress over the entire line cycle are minimized. ZVS conditions are met for all high-frequency switching devices for the whole operating region, while the AC side converter is line frequency switched, incurring negligible switching loss. AC line current waveforms are of high quality and free from low-frequency harmonics. UPF operation is of importance for single-phase power conversion. All possible modes that the converter will experience over a line cycle for UPF operation are elaborated through detailed analysis. The proposed strategies are validated through experiment and simulation with 230 V, 50 Hz AC grid, 400 V DC, UPF, and output power of 1.2 kW.

scholarly journals CASCADE TOPOLOGIES FOR THE ASYMMETRIC MULTILEVEL INVERTER BY NEW MODULE TO ACHIEVE MAXIMUM NUMBER OF LEVELS

2016 ◽  
Vol 17 (2) ◽  
pp. 83-93 ◽  
Author(s):  
Emad Samadaei ◽  
Seyyed Asghar Gholamian ◽  
Abdolreza Sheikholeslami ◽  
Jafar Adabi
Keyword(s):  
Cost Benefit ◽  
Multilevel Inverter ◽  
Experimental Results ◽  
Switching Frequency ◽  
Level Control ◽  
High Quality ◽  
Multilevel Inverters ◽  
Experimental Prototype ◽  
Wide Range ◽  
Base Module

ABSTRACT:  Multilevel inverters have been introduced as useful devices to connect between DC-AC systems. They are high quality output and cost benefit systems with a wide range of applications. Asymmetric multilevel inverters are a type of multilevel inverters with unequal DC link to create more voltage levels through fewer components. This paper presents new topologies of cascade multilevel inverter by a new module with a reduced component. Base module produces 13 levels by two types of unequal DC sources and 10 switches. Modular can be used to produce more and higher voltages levels. The designing of proposed multilevel inverter makes some preferable index with better quality than similar modular multilevel inverters, such as less semiconductors and DC sources, low switching frequency, creating of negative levels without any additional circuit, and module in cascade connections. Also, two cascade topologies are presented in the modular connections of the proposed module to achieve high and significant number of levels. Nearest level control (NLC) method as a switching technique is used in step changing levels for topologies to get more quality and lower harmonics. The presented module and cascade topologies are simulated by MATLAB/Simulink and are implemented by the experimental prototype in laboratory to validate the performance of proposed topologies in which simulated and experimental results show a good performance with the high quality output.

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