Input DC Source Research Articles

Single-Phase Five-Level Multilevel Inverter Based on a Transistors Six-Pack Module

This article introduces a single-phase five-level multilevel inverter based on six switches and two transformers. The proposed converter requires a single dc input source with low voltage. The disposition of switches makes it possible to build the converter with a transistors six-pack module off-the-shelves, traditionally used to build three-phase inverters, which simplifies the manufacturing process. The converter increases the voltage with two transformers; for that reason, it does not require an auxiliary step-up converter. The use of transformers (with the transformer’s turns ratio) allows for using the same topology for several input voltage levels. To verify the operation of the proposed multilevel inverter, a computer-based simulation was performed with PSIM, a software that considers parasitic components. The results show that the proposed converter can work properly.

Reduced Multisource Switched-Capacitor Multilevel Inverter Topologies

Multisource switched-capacitor multilevel inverters are proper topologies when multiple dc sources are available as renewable energy sources. However, these multilevel inverters have the main drawbacks of requiring a large number of power semiconductors and capacitors and a low boost factor to achieve a large number of voltage levels, which complicate control, reduce performance, and raise the cost. This article presents two configurations for multisource switched-capacitor multilevel inverters. First, a basic multisource switched-capacitor topology is proposed with a small number of capacitors and semiconductors that produce a zero voltage level and a large number of positive voltage levels. The input dc sources are operated in an asymmetric trinary algorithm, while the capacitors are charged/discharged in a binary algorithm using parallel/series modes (without the need for any circuit balancing). Based on the proposed basic topology, two multilevel inverter topologies are proposed, which create bipolar output voltage levels using two different circuits at the output. The first proposed topology uses a standard H-bridge inverter at the output of the basic topology, while the second topology uses an extra switched-capacitor (self-balancing) circuit. The comparison indicates that both the proposed topologies have advantages over most of the reported multisource switched-capacitor multilevel inverters, such as a small number of capacitors, a small number of power semiconductors, low voltage stress, and high boost factor. Furthermore, the proposed topologies decrease the low cost factor in comparison to other topologies. The capacitors' capacitance, power losses, and voltage ripple losses are all measured and evaluated in detail. Theoretical research is validated with the use of laboratory prototypes to validate the performance of the proposed topologies.

Low Frequency Current Ripple Suppression for Two-Stage Single-Phase Inverter Based on Impedance Editing

The instantaneous output power of the two-stage single-phase inverter pulsates at double-line frequency, generating a large amount of second harmonic current (SHC) in the front-end dc-dc converter and input dc source. The SHC is harmful to the system performance. To address the issue, a control strategy based on port-impedance editing, where inductor current feedforward (ICFF) and bus voltage feedforward paths are employed, is proposed to reduce the low frequency ripple in the article. Due to only bandpass filter employed in each feedforward path, the proposed control scheme is relatively easy to be implemented. Under the control strategy, the dc-bus port-impedance of dc-dc converter is increased rapidly at double-line frequency, while staying low impedance for other frequencies. What is more, different ICFF paths are taken into insight to obtain optimized path. Meanwhile, the small signal model of front-end dc-dc converter is established and the design principle of key parameters is provided for the derived control strategy. Furthermore, the dynamic response with bandwidth limitation is also discussed in this article. Finally, a two-stage single-phase inverter prototype was fabricated and tested. The experimental results verify the performance of the proposed strategy with SHC reduction.

Single and Double Input DC Sources Multilevel Inverter Topologies With Reduced Components Counts and Voltage Boosting Property for Grid-Connected Photovoltaic Converters

This article proposes a single-source nine-level multilevel inverter topology that handles a reduced number of components. Moreover, it utilizes the virtual dc sources in terms of the switched capacitors to reduce the number of the active dc source. Those capacitors have a self-charging with naturally balancing capability. The proposed topology can be upgraded to a 19-level configuration. This modification is performed by adding a single supply and a pair of switches. To highlight the good features of the proposed structures, a set of comparative studies are held with other structures based on some of the performance evaluating parameters. The comparison results prove the superiority of the proposed configurations over the other comparative references. A simple method is presented to estimate the boundary for the capacitance of capacitors. The performance of the proposed configurations is validated through the practical prototypes for these structures, which are implemented and tested based on the dSPACE (DS-1103) hardware. For further validation, the proposed topology is integrated with a photovoltaic (PV) system to study its performance with a high output power system.

Linear Matrix Inequality-Based Multivariable Controller Design for Boost Cascaded Charge-Pump-Based Double-Input DC–DC Converter

An analysis and controller design of double-input dc–dc converter (DIDDC) is introduced in this article. This converter is integrated with buck and boost converters at the front-end and a charge pump on the back-end. Salient features of this topology are as follows: (i) ripple content is low in source currents, (ii) both the dc sources are connected through an inductor, which gives rise to a smooth source current waveform, (iii) both the sources supply power to load either in standalone or simultaneously together, and (iv) two control–loops (one for source current regulation, while the second one for load voltage regulation) are sufficient enough to ensure power transfer/management from dc sources to load. To ensure power management on the input dc sources while keeping a stable closed-loop converter system, a multivariable diagonal controller is designed. The first diagonal controller performs the load voltage regulation task, while the second controller regulates input of source-2 dc current. From the control point of view, the double-input single-output converter becomes a two-input two-output control problem and exhibits control–loop interactions due to the power flow from two different sources to load through common elements. The impact of off-diagonal elements’ interactions is accounted by using decouplers. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> robust control theory and linear matrix inequality (LMI) principles are adopted to design reliable controllers. The structured controller of fixed order (PID) is designed by enforcing the necessary type LMIs. To demonstrate the feasibility and effectiveness of multivariable controllers of the DIDDC, a 60/24 V to 48 V, 150 W, 50 kHz topology prototype is constructed, and the power management aspects are investigated experimentally. Load voltage regulation, source current regulation, load sharing on the input dc sources, and power management aspects of LMI-based controllers were tested extensively for all possible disturbances. In all these test cases, the closed-loop double-input converter system is stable and robust in rejecting a variety of disturbances created.

A Switched Capacitor-Based 13-Level Inverter With Reduced Switch Count

In this article, a 13-level switched capacitor multilevel inverters (SC-MLI) based single-phase inverter is proposed in which desired levels of output ac voltage are realized with reduced number of switch counts. The proposed inverter requires 12 switches, three diodes, one input dc source, and three capacitors. The requirement of less number of switches reduces the requirement of gate drivers, which enhances power density of converter. The second challenge in SC-MLI is to maintain self-voltage balancing across the capacitors. The self-voltage balancing capability becomes poor at low values of modulation index. The capacitors connected in proposed SC-MLI are capable to maintain the self-voltage balancing without requiring auxiliary circuits or complex control strategies. The operation of capacitors is self-balanced at all regions of modulation index values. The comparison of the proposed SC-MLI is carried out with state-of-art SC-MLIs discussed in the literature using the parameters like peak inverse voltage and total standing voltage. The switches connected in the proposed 13-level SC-MLI undergoes less voltage stress as compared to the SC-MLI configurations discussed in the literature. The proposed SC-MLI is highly competent to achieve good power quality and is capable to ensure voltage balancing of capacitors even at low values of modulation index. The validation of the proposed inverter topology is carried out using a laboratory prototype. The efficiency of the converter claimed using the simulation results is observed to be 96.2% while the efficiency evaluated using the experimental results is 94.1% at 500 W.

An integrated single‐phase boosting voltage inverter with two parallel DC/DC converters

AbstractAn integrated single‐phase DC/AC power converter with step up is an interesting alternative of two‐stage architecture. This paper presents a single stage step up inverter with two inputs to simplify the hardware structure and reduce the number of power components. This circuit arrangement can be derived by combining two parallel boost DC/DC converters and a split‐capacitor, reducing the cost and power conversion stage. And, the proposed inverter can output AC voltage higher than the input DC voltage only through single‐stage conversion, which can satisfy the applications such as photovoltaic power generation systems. Moreover, the two input DC sources can provide power to the load port together or separately, with great flexibility. Furthermore, the proposed converter has the inherent feature of shoot‐through immunity, which can further improve the reliability of the system. This article discusses the operating modes and stable performance of the inverter in detail. Finally, an experimental prototype is built to verify the validity of the proposed topology and theoretical analysis.

A Novel 17-Level Reduced Component Single DC Switched-Capacitor-Based Inverter With Reduced Input Spike Current

Multilevel inverters (MLIs) have become common and resourceful as a result of the fast advancement of technology in the areas of high-voltage and high-power applications, among other things. Recently, MLIs have received a great deal of attention recently, due to the growing need to harness environmentally friendly energy. With reduced power electronics switches, diodes, and a voltage boost gain factor of 8, this article presents a single-phase 17-level switching capacitor inverter design. The proposed inverter uses single dc voltage source, two diodes, 14 power electronics switches, and three capacitors. The different mode of operation of topology is explained in detail, including their self-voltage balancing technique. Additionally, an inductor is used in the capacitor charging loop to avoid current spikes caused by the input dc source while charging the capacitor quickly, thereby increasing capacitor life expectancy significantly. Compared to previously the proposed single-input MLIs, the proposed inverter has a lower semiconductor switch count and a lower cost function value that are its distinguished feature. The performance of the topology is verified by MATLAB/Simulink, and furthermore, a laboratory prototype is utilized, which confirms the feasibility of the proposed topology.

A Novel Single-Phase Multilevel High-Gain Inverter With Low Voltage Stress

This article proposes a high performance with 13-step, switched-capacitor multilevel inverter (SCMLI). The gain factor of 6 is achieved, along with self-voltage balancing of capacitors. The suggested structure can be cascaded to generate any number of voltage steps with the inherent property of generating both positive and negative voltage steps. All the power switches withstand voltages lower than 50% of maximum output voltage. The number of power switches, the number of dc input sources, the voltage stress on the switches, and the power losses are reduced. Also, the presented inverter has a minimum cost function compared to the other similar structures. The performance of the proposed 13-step converter has been validated by the simulation, extracted by PSCAD/EMTDC, and also the experimental results, obtained from an implemented laboratory prototype.

Seven‐level triple boost self‐balanced switched‐capacitor inverter

AbstractSwitched‐capacitor multi‐level inverters (SCMLIs) have become more popular in recent years due to their unique advantage of voltage boosting capability. A seven‐level triple boost SCMLI is proposed in this paper. The proposed topology consists of 10 switches, one diode, three self‐balanced capacitors, and a DC source. The voltage stress on each switch is less than or equal to twice the input DC source voltage. Further, 4 out of 10 switches are switched at the fundamental frequency. The maximum conducting switches at each level is less than or equal to 4. The capacitors are self‐balanced without using any voltage sensors or external circuits. A detailed comparison has been given with the existing seven‐level triple boost SCMLI to show the superiority of the proposed topology. The seven‐level triple boost SCMLI is simulated using MATLAB/SIMULINK tool. The proposed model is verified at low‐ and high‐frequency switching, sudden changes in output load, and different modulation index values. The results are verified experimentally with the help of a prototype model developed in the laboratory using dSPACE 1104.

A Novel Switched Capacitor Precharging Method for Three-Phase Induction Motor Drive Applications Utilizing the Winding Inductance

Three-phase (3-φ) induction motor drives operated with switched capacitor (SC) inverter circuits offer superior harmonic performance and voltage boosting. The SC network, however, generally requires additional circuitry to precharge the capacitor(s) to prevent inrush current. To obviate the requirement of the extra circuit, an innovative SC precharging scheme is presented, which utilizes the winding inductance of the motor. The inverter circuit is so operated that the motor winding inductance first stores electrical energy from the input dc source and then releases it to the SC. These two actions are continued till the SC is precharged to a voltage equal to the magnitude of the input dc source. The circuit operation during the precharging is similar to the operation of a conventional buck-boost type dc–dc converter. The precharging action is so designed that the voltage of the SC cannot increase further. Therefore, the proposed scheme does not need any voltage sensor. The operation of the circuit during precharging is analyzed extensively to develop a mathematical background for the given method. It is shown that by manipulating the switching frequency during the precharging the precharging time can be controlled as per the user requirements. Various claims are validated using computer simulations and experiments. All the results are presented.

Design and Analysis of Partial shading of the PV System Integrated with High-Frequency Inverter and Rectifier Operation for the Electric Vehicle

Solar photovoltaic cells are in high demand for sustainable energy generation because of their capacity to provide direct power. As a result, DC-DC converters that can enhance the output voltage and do so reliably while eliminating changes in solar panel outputs are required. Inconsistencies in sun-light availability, ambient temperature, and shadows, among many other considerations, cause the fluctuations. Compared to the typical DC-DC Boost converter, the suggested converter architecture has a higher efficiency of over 95%. In a resonant inductive coupled power transmission system for an electric vehicle, this research demonstrates partial shading of a 250-W PV solar-powered interfaced with a high-frequency resonant full-bridge inverter. The suggested system’s DC input is provided by a PV panel. The ratio of DC Input sources supplied to the high-frequency inverter is 1:3. For a fixed modulation of 0.7, the step modulated for a high-frequency inverter uses a pre-calculated switching angle. Due to a very high-frequency AC connection, the suggested system is more efficient than a traditional system of 50 Hz inverter operation and multiple-output transformer architecture. Zero Voltage Switching (ZVS) is ensured in this study, which decreases switching losses. In the MATLAB/ SIMULINK environment, the suggested approach has been validated. The research aims to investigate and illustrate the effect of partial shading with and without a bypass diode on the I (V) and P (V) properties of solar panels. Hence, the suggested approach’s performance is compared to the present method in terms of parameters, and 95 percent efficiency may be attained. When compared to shaded and unshaded situations, this paper displays greater feature modifications.

PWM Control of N-Phase Interleaved Active Front-End Boost Stage-Based Impedance Source Inverter

Non-isolated high gain inverters, such as impedance source inverters (ZSI), are suitable for applications with limited input dc source voltage, e.g., microinverters. High gain in these inverters is attributed to the front-end boost stage (FBS). High step-up ratio results in very high input current as the power rating of the inverter goes up. This leads to significant conduction loss in the non ideal elements of the inverter, specifically in the FBS, thereby degrading the efficiency. Paralleling and interleaving the FBS is a feasible solution to achieve higher efficiency. This demands for a generalized pulsewidth modulation (PWM) scheme, which can enable paralleling of multiple interleaved FBSs. In this article, a novel PWM scheme is proposed to implement <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> -phase interleaving of active FBS-based ZSIs. The PWM scheme ensures synchronized operation between the “ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> ” interleaved FBS and the single inverter stage. As case studies, the PWM scheme is implemented in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> -phase interleaved current fed switched inverter, switched boost inverter, and quasi switched boost inverter. Steady-state operation of these topologies with three interleaved phases is verified using PLECS simulation. Operation of an interleaved current fed switched inverter with three interleaved phases is verified experimentally using a 200-W proof of concept prototype.

Development of multilevel inverter with reduced switch counts and limited sources for electric vehicles

A new topology with a reduced number of switches with minimum cost, less switching complexity, and adaptable to different dc source voltage ratios of 1:2 (binary) and 1:3 (trinary), with reliable and extended/cascaded operation in both symmetric and asymmetric mode, has been developed for EV applications. Pulses are generated for the proposed configuration using Nearest Level Control. The proposed inverter is compared with another recent topologies based on various factors, such as total switches, number of gate drivers, and total standing voltage. An asymmetrical multilevel inverter of type II configuration selects dc sources based on binary and trinary algorithms. To increase the stepped output levels, the basic unit is extended by three different structures: series, cascading, and packed unit cell connections. The dc-link capacitor voltage is boosted with the help of bidirectional multilevel-boost converter with a low input dc source, which is commonly used in electric vehicle applications. In addition to the simulation of the proposed configuration using MATLAB, it has also been validated with an experimental setup developed.

Nine-Level Nine-Switch Common-Ground Switched-Capacitor Inverter Suitable for High-Frequency AC-Microgrid Applications

Voltage source multilevel inverters with reduced leakage current, single-stage voltage step-up feature, compact design, and an efficient performance are a promising technology for high-frequency ac (HFac) microgrids feeding through renewable energy sources. This article proposes a novel single-source common-grounded (CG) step-up nine-level (9L) inverter, which can be applied in HFac microgrid applications. The proposed CG-based boost inverter is comprised of only nine switches (9S) and three self-balanced capacitors. Using the switched-capacitor (SC) technique, a double voltage boosting feature within a single power processing stage is achieved, while the leakage current concern is eliminated due to a CG-based configuration between the input dc source and the null of the grid. With the help of an <i>LC</i> input filter, the input current profile is free from large discontinuous inrush spikes. The working principles of the proposed 9L9S-CGSC inverter are discussed in this article. The modulation and closed-loop control strategy, as well as a comparative study, are presented. Finally, the open and closed-loop grid-tied performances of the proposed topology are evaluated by both simulation and experimental results obtained from a 1.2-kW laboratory-built prototype.

Improved modified a multi-level inverter with a minimum total harmonic distortion

Renewable energy sources are developed as a result of the increased demand for electrical power. The nature of the solar energy source is DC. The DC source for many applications needs to be converted to AC. The inverter is used to convert the power from DC to AC. Total harmonic distortion (THD) is a significant concern with inverters. Multi-level inverters are used to reduce the THD. The stair output voltage of the multi-level inverter not only reduces the THD but also reduces the switches' stresses, so a low voltage rating can be used for the switches. In this paper, a modified inverter topology is introduced in which the number of switches is reduced for the same number of output voltage levels, which leads to reducing the losses and the cost. To reduce the THD, different amplitudes for the carrier signals that control the switches in each level are suggested. Another method to reduce the THD by using different capacitor values across the input DC source is presented. The MATLAB/Simulink is used to show the validity of the suggested modified topology and the modifications.

Regenerative Passive Snubber Circuit for High-Frequency Link Converters

This letter presents a passive snubber circuit for high-frequency link cycloconverters, which typically suffer from voltage oscillations across matrix-stage semiconductor devices. The proposed passive snubber allows for effective damping of the oscillations and reduction of the peak voltage stress. It is based on an auxiliary transformer and a diode bridge rectifier, which are rated only for a fraction of total converter power regenerated back to the input dc source. The performance of the circuit was verified with 350 Vdc/230 Vac, 1 kW SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MOSFET</small> -based experimental prototype and a reduction of the peak voltage overshoot from 2.24 to 1.55 times the nominal was achieved, without negative impact on the converter overall efficiency. As a result, the blocking voltage rating of the matrix-stage semiconductors can be reduced from 900 to 650 V.

A Novel Dual Buck and Boost Transformer-Less Single-Phase Grid-Tied Inverter

Conventional dual buck and boost inverter with a single input dc source (DBBI-SIDS) has the satisfactory performance of high efficiency, low total capacitance, and no leakage current. Nevertheless, the main current will flow through the two individual capacitors of the inverter, which may reduce their lifetimes. In this article, a new DBBI-SIDS will be proposed, where two extra <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> switches at line frequency are adopted to be instead of the two individual capacitors of the conventional DBBI-SIDS. Different from the conventional DBBI-SIDS, the new inverter works in the pure full bridge mode. The detailed principle of operation is presented through equivalent circuits. The static characteristics and the control strategy of the proposed inverter will be also introduced in detail. A 110-V/50-Hz/550-W prototype has been developed in the laboratory, where experimental results have verified the desired performance of the proposed inverter.

Multilevel Inverter Topology having Reduced Number of Input DC Sources and Switches

Multilevel Inverter Topology having Reduced Number of Input DC Sources and Switches

Topological review of hybrid RES based multi‐port converters

Depletion of natural resources like gas, oil, coal along with environment pollution increased the popularity of the Renewable Energy Sources (RES). Power Electronic converters are utilized for conversion of power from RES to coordinate the stand-alone load and utility grid. MPPT control is also established by these converters to supply the standalone or grid-connected load despite of the RES's unpredictable nature. In order to reduce the number of switches used for integrating RES to drive loads, Multi-port converters are developed. These converters have the capability to supply more than one load simultaneously. Furthermore, more number of RESs are connected using these converters in order to drive common loads. Available literatures do not explain in detail regarding various types of multi-output converters, their advantages, disadvantages, application area and control techniques used in order to drive these converters. In this context, a review of recent advances in multi-port DC-DC converters for different application using hybrid RESs is carried out. Initially in literature, few DC-DC converters are connected in parallel, series configuration and used as multi-port converters. Multi-stage conversion is realized using DC-AC-DC conversion. Advantages of conventional converters are integrated in order to develop derived multi-output converters. These multi-port converters have the capability to drive both DC and AC loads from a single DC input source. The converters share common power electronics equipment while generating both DC and AC power simultaneously. Furthermore, these multi-port converters also use single step power conversion process which reduces the overall system loss. As these hybrid multi-port converters use lesser number of power electronic switches, the control complexity of these converters reduces compared to the conventional converters connected in cascaded or parallel manner to drive loads. A detailed review of these multi-port converters with respect to topologies, and operating principle, diverse reliability and effectiveness are presented in this paper. This survey helps designers to select the appropriate RES-based multi-port converters for their respective applications.