Number Of Power Electronic Components Research Articles

New multilevel inverter based on reduced switch basic cell for high voltage levels

AbstractIn this study, to solve total harmonic distortion (THD) and voltage stress on switches, challenges have been made by presenting a new multi‐level inverter (MLI). The proposed topology can operate with both symmetric and asymmetric sources. The proposed topology in symmetric and asymmetric mode with 18 switches can produce 17 and 49 voltage levels, respectively, with THD values of 4.14% and 1.45%, which passes the IEEE harmonic standard. The main advantage of the proposed topology is reducing the number of circuit devices, which reduces the price, volume, and complexity of the circuit by reducing the number of circuit devices. The proposed topology reduces the THD, the number of power electronics components, and voltage stress by increasing the output levels. The proposed topology is compared with other topologies and the advantage of the proposed topology is shown in terms of the number of switches and drivers. In addition, the proposed topology is compared in terms of the cost function. The power losses based on the thermal model of the proposed topology have been analysed and simulated. Simulation and experimental results are presented for different scenarios such as load type, load changes, and modulation index changes to validate the proposed topology.

Design of a 21‐level multilevel inverter with minimum number of devices count

SummaryMultilevel inverters (MLIs) have attracted the attention of researchers for their needs in industrial applications, renewable energy systems, and electric vehicles. MLIs require a large number of power electronic components to synthesize higher levels at the output voltage. However, overuse of power electronic devices increases the complexity, losses, and cost of MLIs. In this study, a new MLI has been proposed with a reduced number of power switches. The basic unit of the proposed MLI comprises only three independent DC sources and 10 switches (eight unidirectional and two bidirectional) to produce 21 levels at the output voltage waveform. The nearest level control (NLC) modulation method has been used to produce gate pulses. Furthermore, three extension topologies have been proposed to generate a higher number of levels, and the extension parameters have been compared with recently introduced and conventional topologies. The comparative study shows that the proposed MLI topology requires fewer components in terms of power electronics parameters than the others. On the other hand, the presented first extension study that can be used for all non‐extendable basic units is one of the prominent values of the study. Simulation studies showing modulation methods, switching patterns, and signal outputs were performed with Matlab/Simulink. A prototype of the proposed main module has been realized and tested in the laboratory with an FPGA processing board. Experimental results have been verified with simulation results, and the performance of the proposed topology has been proven.

A new symmetric modular eleven‐level inverter using single and double source unit for low voltage applications with reduced number of switches

AbstractThis study proposes a modular multilevel inverter for low‐voltage applications, including ac‐coupled renewables and energy storage systems. These inverters require many switches and gate drivers in their structures, which complicates the control system, reduces efficiency, and increases costs. This study introduces a new modular multilevel inverter that can produce five levels of positive voltage using only six power switches and five DC voltage sources. The basic unit is composed of a single‐ and double‐source (SDS) unit. SDS reduces the number of power electronic components, such as the insulated gate bipolar transistors, freewheeling diodes, gate driver circuits, dc voltage sources, and blocking voltage by switches. The proposed topology can boost the number of output voltage levels and decrease the number of switching devices and voltage stress using some combinations of basic submodules. The performance of the proposed 11‐level single‐phase inverter is compared with that of the conventional structures and recent symmetric topologies considering the number of switches, cost, and efficiency. The waveform quality and both the voltage and current harmonic characteristics were determined in accordance with IEEE 519–2014. Finally, an 11‐level prototype was constructed to validate the theoretical analysis, feasibility, and effectiveness of the proposed inverter.

A Sliding-Mode Observer for MMC-HVDC Systems: Fault-Tolerant Scheme With Reduced Number of Sensors

The modular multilevel converter (MMC) has been widely adopted in different applications, such as high-voltage direct current (HVDC), electric drives and static synchronous compensators. Despite the application, MMC realization requires a high number of power electronic components, sensors, and communication cables. This paper proposes a sliding-mode observer for capacitor voltages of the MMC, using the measurements of arm currents and arm voltages. A linear corrector within the hysteresis band is proposed to reduce the chattering in the observer dynamics. Moreover, guidelines for tuning the observer gain are presented. The SM capacitance value is included as a parameter uncertainty of the observer. The proposal reduces the requirements of voltage sensors and optical links in MMC and allows fault-tolerant operation. The proposed observer performance is evaluated through a simulation of 100 MVA three-phase MMC-HVDC during initialization, steady-state, and submodule failures. The effect of the switching and sampling frequencies on the observer performance is also evaluated. Finally, experimental results validate the proposal in a downscale 3 kVA single-phase MMC prototype.

Symmetric and Asymmetric Configuration of Parallel-Switched d-Type Multilevel Inverter

Total harmonic distortion (THD) and voltage stress across the switches are critical issues in power electronic systems. Although multilevel inverters (MLIs) were initially used to minimize these issues, doing so is challenging when simultaneously attempting to minimize the number of components such as switches, dc sources, and gate drivers. To address this problem, a new pd-type MLI is presented with two back-to-back connected d-type modules with an H-bridge that generates the negative voltage levels. The proposed topology with ten unidirectional switches and four dc sources operates in symmetric and asymmetric configuration to generate 9, 13, and 17 voltage levels. The presented inverter is extended using cascaded connections to attain more output voltage levels, making it usable for the applications with diverse number of dc links for medium- and high-voltage applications. The proposed topology also exhibits small THD, low number of power electronic components, and low total voltage stress across the switches in each cycle. Furthermore, a widely used nearest level control (NLC) modulation technique is used to generate output voltage levels with a minimum amount of THD at the output. Finally, simulations were performed using MATLAB/Simulink and experiments were conducted to validate the performance of the proposed topology.

Design of an Interleaved High Step-Up DC-DC Converter with Multiple Magnetic Devices for Renewable Energy Systems Applications

An interleaved high step-up converter topology based on the coupled inductor (CI) and built-in transformer (BIT) is proposed in this study to provide high step-up voltage gain and high efficiency with a low number of power electronic components for renewable energy applications. The voltage gain is increased by both of the turns’ ratio of CI and BIT, so there is no need to extend duty ratio to obtain high voltage gain. The proposed topology is much more flexible than those with only either CI or BIT. Moreover, the voltage stress across semiconductor devices can be relatively decreased by adjusting the turns’ ratio of the CI and BIT. In addition, the input current ripple can be reduced when the interleaved structure is applied at the input of this converter. Furthermore, turned-OFF and turned-ON zero current switching (ZCS) conditions for the diodes and power MOSFETs are achieved, respectively, thanks to the leakage inductances of the magnetic devices. Hence, due to the control of the falling current rate of the diodes by the leakage inductances, reverse recovery problem is alleviated. Moreover, the energy of the leakage inductances is recycled by the clamp capacitors avoiding high spikes across MOSFETs. As a result, according to the abovementioned advantages of the proposed converter, MOSFETs with low ON-state resistance and diodes with low forward voltage drop can be used to decrease the conduction losses. A 600 W laboratory prototype with 27–400 V voltage conversion at switching frequency 50 kHz is built to verify the performance of the proposed converter. Experimental results confirm the theoretical analysis. The efficiency reaches to 94.6% at full load which is close to the calculated of 95.8%.

Developing a Generalized Multi-Level Inverter with Reduced Number of Power Electronics Components

Reducing the number of components of power electronic converters has been an important research topic over the past few decades. This paper introduces a new structure for a multi-level inverter based on reduced switch basic modules. The proposed basic module requires fewer switches and auxiliary devices. In addition, a lesser number of on-state switches for the synthesis of each voltage level results in less conduction losses, which enhances the converter efficiency. The proposed structure is capable of being implemented in both symmetrical and asymmetrical topologies. This is a merit feature for the proposed topology, which produces high voltage levels with a limited number of elements. The proposed structure is controlled using the fundamental frequency control scheme. The proposed basic module consists of six unidirectional switches and five DC voltage sources, generating five positive voltage levels. The performance of the recommended topology is analyzed from the various circuitry parameters, and a comprehensive comparison carried out with similar recent structures. The presented comparison reveals the advantage of the recommended inverter from different aspects of the circuitry parameters. The suggested structure is simulated using Matlab/Simulink software, and its performance is validated using a laboratory prototype. The results are reported for various steady-state and dynamic conditions.

A Single Stage Sepic Converter for Electric Vehicles Charging

This proposed system is about bidirectional power flow for charger of an E-Vehicles. The charger connected with PV source is designed, modelled, and implemented. In this topology, the output charging current is regulated by DC-DC converter. The bidirectional interleaved isolated SEPIC converter is proposed in this paper for charging the electric vehicle. The multi-step constant current charging method is used for charging operation. This reduces the number of power electronic components, which in turn minimizes the power loss. Simulation is carried out in MATLAB/Simulink, and the results are obtained, which shows that battery can be charged with this topology.

A current‐limiting DC circuit breaker with power flow control capability

Power flow controller (PFC), fault current limiter (FCL) and DC circuit breaker (DCCB) are important equipment in the DC grid. There are a large number of power electronic components in these equipment, resulting in high cost. In order to reduce the use of additional components, a current-limiting DC circuit breaker with power flow control capability is proposed here, which integrates the PFC, FCL, and DCCB into one equipment. Further, the main breaker in the proposed circuit breaker is shared by all lines connected to a DC bus to reduce cost. The topology and operating principle of the circuit breaker are introduced. Theoretical analysis and parameter design are carried out. Besides, the proposed circuit breaker is verified in PSCAD/EMTDC. Finally, the performance and cost are compared with existing schemes. The simulation results show that the proposed circuit breaker can effectively realize power flow control, current limiting and fault isolation at a lower cost.

A new generalized cross-connected switched capacitor multilevel inverter topology with high output voltage gain for single phase solar PV unit

Switched capacitor multilevel inverters are gaining much attention these days due to their merits like voltage boosting and voltage balancing characteristics. A Cross Connected Switched Capacitor Multilevel Inverter (C2SC-MLI) topology is proposed in this work. It can synthesize thirteen levels in the terminal voltage waveform and with a voltage boost ratio of 1:3. The topology is extendable by adding additional “n” modules in series. The number of levels (NLevel) and the voltage gain can be increased up to 4i+9 and 1:(i+2) respectively by connecting ‘i’ such ‘n’ modules. The topology also has inherent voltage balancing ability. To prove the advantage of proposed topology it is compared with recent switched capacitor multilevel inverter topologies and conventional multilevel inverter topologies in terms of number of power electronic components required, cost and voltage gain. The performance of proposed topology is validated using simulation in MATLAB and with an experimental prototype rated 0.1 kW fed by a solar PV emulator under steady state and dynamic loading conditions.

A New Analytical Approach for Fast and Accurate Dynamic Simulation of MMC-HVDC System

The Speed of execution along with acceptable accuracy of the simulation is crucial for Modular Multilevel Converter based High Voltage Direct Current (MMC-HVDC) systems in offshore applications. The high number of power electronic components in the MMC-HVDC system poses a challenge to solve them using the existing methods, based on average models, with required speed and accuracy. This paper presents a method to simulate all the submodules of the MMC-HVDC system, which enables to study of the dynamics in the subsea cable, submodules, and at the system level. MMC-HVDC system in a standard three-phase CIGRE benchmark configuration is modeled to validate the analytical method. It is compared with PSCAD simulations (based on Dommel’s method) and validated both in steady state and in transient conditions of the MMC-HVDC system. The results indicate that the analytical method is accurate, and the execution time is lower compared to PSCAD based on Dommel’s method.

A Novel Cascaded Symmetric and Asymmetric Multilevel Inverter Topology with Minimum Number of Power Electronics Components

A Novel Cascaded Symmetric and Asymmetric Multilevel Inverter Topology with Minimum Number of Power Electronics Components

A switch-source cell-based cascaded multilevel inverter topology with minimum number of power electronics components

Multilevel inverters are a new generation of DC–AC converters at medium and high voltage and power levels. In this paper, a new single-phase cascaded multilevel inverter is presented. For this purpose, a new basic cell is presented at first. Then, the new multilevel inverter structure is yielded by series connection of these cells. The proposed new cell is only capable of generating positive voltage levels, and therefore, to produce zero and negative voltage levels, the proposed structure is constructed based on H-bridge module. In order to reduce the maximum blocking voltage especially on H-bridge switches, the cascaded connection of the proposed converter is investigated. A comprehensive comparison is carried out between the proposed multilevel inverter with the classical and recently introduced structures in terms of the number of switching devices, the number of drivers, the total blocking voltage of the switches as well as the loss and efficiency. The accuracy of the proposed inverter’s performance is simulated in MATLAB/Simulink in symmetric and asymmetric topologies for a 17-level and 23-level output voltage respectively, and then evaluated by the laboratory prototype.

Distributed power management with adaptive scheduling horizons for more electric aircraft

A more electric aircraft is expected to have low emissions, decreased fuel consumption, high efficiency, and low maintenance costs. To fully enjoy those benefits, major technical obstacles must be overcome first. In terms of power management, an increasing number of power electronic components used in aircraft power systems and their ever-increasing functional sophistication will lead to high modeling and computational complexities, making real-time power management a daunting challenge. To address this challenge, in this paper we will first propose a novel architecture for real-time power scheduling, which allows a user to easily incorporate fault diagnosis, stability analysis and power scheduling together, and then present a locally tactical power scheduling strategy based on a Lagrangian relaxation, which allows a user to adopt different computation techniques to undertake local computations within sub-systems in parallel to ensure good scalability of the distributed strategy. Moreover, the power scheduling is calculated based on an adaptive scheduling horizon to further reduce the computational complexity. Simulations are carried out to illustrate the effectiveness of our proposed distributed architecture, in particular, the optimality of the solution and the balanced computational complexity.

Optimal design of a cascaded rectangular‐type and circle‐type multilevel inverters with a new switching technique

Multilevel inverters (MLIs) are extensively used in industrial and renewable energy applications. They are a promising solution for the effective transformation of dc to ac. Researchers are developing auspicious topologies to mitigate the use of an output filter, which reduces cost and complexity. Hence, it is necessary to develop a topology that is capable of increasing output voltage levels with an optimum number of power electronic components. However, in developed topologies, a large number of switches, gate driver circuits, and dc sources are used. To solve this problem, a new MLI structure is introduced. The proposed structure is cascaded to form cascaded rectangular-type and circle-type topologies capable of engendering maximum output voltage levels and incorporating an optimum number of switches, gate driver circuits, and dc-sources. Moreover, conventional switching techniques have become more complex, while generating a staircase output contains a large number of levels. Therefore, this study proposes a novel switching technique that is easy to implement in MLIs with large output voltage levels. To show the competency of the proposed topology, a comprehensive comparison is performed with various structures. At the end of this study, validation of the proposed switching technique and topology is verified by simulations and experimentations.

Analysis and Design Method of Multiple-Output Switched-Capacitor Voltage Regulators With a Reduced Number of Power Electronic Components

This paper presents a study of compact multiple-output switched-capacitor voltage regulators (MOSCVRs). Two methods to produce multiple outputs with an SCVR and their effects on performance – power efficiency and cross-regulation, are examined with output impedance analysis. Moreover, to help a circuit designer to implement a compact MOSCVR, a design method to determine the number of outputs and their conversion ratios is also proposed in this work. To verify this method, we demonstrate the design of an example compact MOSCVR. The MOSCVR is capable of simultaneously producing four different output voltages from a single input power supply with only two flying capacitors and twelve switches. The study presented in this work provides not only comprehensive insight but also guidance to find the suitable topology of a compact MOSCVR.

A New Generalized Multilevel Converter Topology Based on Cascaded Connection of Basic Units

In this paper, a new single-phase multilevel converter (MLC) topology based on the cascade connection of novel basic units is presented. The proposed basic unit generates 17-level output voltage waveform and can be extended for higher voltage levels by using a simple cascade connection. Both the proposed basic unit and cascaded topologies are compared with other state-of-the-art MLC topologies. From the comparison results, it will be shown that the proposed topology has several advantages such as the reduced number of power electronic components, lesser number of dc sources, and blocking voltage. Moreover, the proposed MLC has reduced power losses and improved efficiency. The operability and feasibility of the proposed converter are validated through extensive simulation and experiments. Finally, the corresponding results affirming the predominance of the proposed topologies are presented.

PWM Technique for Single Phase Asymmetrical Hybrid Multilevel Inverter for Non-linear and Dynamic loads

A two level VSI has output voltage either equal to positive or negative source voltage. This inverter has more ripple. In order to reduce the ripple content more number of switches are needed to produce many number of stepped voltage waveform. This improves the quality of power. This switching losses depends on the frequency of operation so when a two level inverter is operated at high frequency, the switching losses are predominant. This limits the use of such inverters. Hence, being replaced by Multilevel inverters. They have attracted academician and industry personal for medium and high-power power control. Such attractive features are available in hybrid multilevel inverter. Hence, these are preferred. They provide multi-level operation by using hybrid sources. Moreover, the number of power electronics components needed are less than conventional CMI for same voltage level. Thus, such inverters have more efficiency. In the proposed techniques, an asymmetrical hybrid multilevel inverter has been simulated using MATLAB Simulink. The results obtained have been presented for three different types of load.

Generalized Cascaded Symmetric and Level Doubling Multilevel Converter Topology with Reduced THD for Photovoltaic Applications

In this paper, two different converter topologies for a basic new switched capacitor diode converter with a reduced number of power electronics components, suitable for grid connected photovoltaic applications were proposed. The two different structures of switched diode multilevel converter proposed were: (i) cascaded switched diode and (ii) cascaded switched diode with doubling circuit. The switched-diode multilevel converter was compared with other recent converters. In addition, a new dc offset nearest level modulation technique was proposed. This proposed dc offset technique offers low voltage total harmonic distortion (THD) and high RMS output voltage. The proposed modulation technique was compared with conventional nearest level modulation (NLM) and modified NLM control techniques. The performance of the proposed dc offset modulation technique was implemented using a FPGA Spartan 3E controller and tested with a novel switched capacitor-diode multilevel converter. However, to prove the authenticity of the switched-diode multilevel converter and modulation technique, a laboratory-based prototype model for 7-level and 13-level converters was developed.

A Grid-Connected Smart Extendable Structure for Hybrid Integration of Distributed Generations

In this paper, a novel grid-connected smart and plug-and-play type extendable structure named unified multiport power electronic converter (UMPEC) for hybrid integration of distributed generation (DG) systems is presented. The proposed structure contains two types of connector ports. The first one is a set of AC connectors, which can be easily used to connect different types and numbers of AC-based DGs along with grid and loads. The second one is a set of DC connectors, which can interface DC-based DGs and storage units. Compared with the conventional and recently invented multi-stage power electronic topologies, the proposed structure enjoys less number of power electronic components, compactness, and plug-and-play capability of integrating AC and DC-based DGs. Considering shared components between different ports and their imposed boundaries on the operation of the UMPEC, a modified sequential space vector modulation is addressed, which makes it possible to control different ports independently, without compromising with maximum power harnessing from individual sources, which is another salient feature of this work. The proposed structure operation and performance is verified using a three DC and two AC connectors version, where wind and photovoltaic systems are independently interfaced to the grid.