Number Of Power Electronic Switches Research Articles

Three Phase Two-Arm Hybrid Active Filter Using Two Feedforward Loops with Self Tuning Filter for Elimination of 5th and 7th Harmonic Frequency

A novel topology for three-phase three-wire hybrid power filter with two-arm is proposed, this hybrid filter configured by a classical active filter consisting of two-arm bridge using two power electronic switches for each arm and two DC capacitors located in the DC side of the power converter, this topology uses less number of power electronic switches that allow to reduce the manufacturing cost. The active filter connected in series with a passive filter. The nonlinear load is a diode rectifier feeding a (R, C) parallel load. The proposed method is based on self-tuning filter placed in both feedback and feedforward loops dedicated to eliminate the 5th and 7th harmonics frequency. The feedforward loop consists in two branches, one to remove the 5th harmonic and the other one to remove 7th harmonic frequency. The use of self-tuning filter simplifies the control scheme by reducing the number of extraction filters, used in classical feedback and feedforward loops. More, in this case, no phase locked loop is necessary for the feedforward loop. The effectiveness of this new proposed scheme has been verified by computer simulation.

A grid-connected eleven-level power conversion interface

ABSTRACT This paper proposes a grid-connected eleven-level power conversion interface (GCELPCI) for renewable power systems. The proposed GCELPCI is composed of a four-port DC-DC power converter (FPDDPC) and an eleven-level inverter (ELI). The FPDDPC combines a boost power converter and a transformer with a turn ratio of 2:1 to generate multiple combinations of the output voltages for the DC bus voltage of the ELI. The ELI integrates an asymmetric voltage technique on a T-type inverter to further convert the DC output voltages of FPDDPC into eleven-level AC voltage. A sinusoidal current is generated by the proposed GCELPCI through the filter inductor and injected into the power grid. Only nine power electronic switches are used in the ELI to generate an eleven-level AC voltage, the number of power electronic switches is reduced to simplify the power circuit. In addition, the capacity of the filter inductor is reduced. A digital signal processor (DSP) and a complex programmable logic device (CPLD) chip are used as the digital controller to complete a hardware prototype to verify the performance of the proposed GCELI.

A novel extendable multilevel inverter for efficient energy conversion with fewer power components: Configuration and experimental validation

SummaryMultilevel inverters (MLIs) are widely used in various sectors of power electronics. Some major benefits of using MLI are the high‐quality voltage output, harmonic reduction, and efficiency. However, MLIs also bear a range of disadvantages including an excessive number of components, high total standing voltage (TSV), and complicated control scheme. Thus, a novel cross‐switched neutral point clamped (CSNPC) nine‐level inverter is proposed. Many of the suggested MLIs use a large number of DC supplies and additional switches that are not fully utilized and generate high power loss. However, the proposed MLI topology has a smaller number of power electronic switches and DC supplies, leading to higher energy efficiency. Moreover, a simplified high frequency modulation technique, named hysteresis‐band‐based discontinuous pulse width modulation (DPWM) is devised to control the proposed MLI. This modulation scheme has effectively minimized capacitor voltage imbalance. Furthermore, the designed structure is extendable to a modular MLI, without any additional H‐bridge circuit. To verify its benefits over other recent similar types of MLIs, a thorough comparison is presented for the number of components and power losses. The proposed MLI has showed 95.54% efficiency, and the modular CSNPC can achieve a total harmonic distortion (THD) of 6.43%.

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.

Reduced Switch Count Multilevel Inverter with Fault Diagnosis Operation

This paper proposes a reduced switch count multilevel inverter with fault diagnosis operation to overcome the problem of a higher number of switches in a multilevel inverter and fault detection in a multilevel inverter. A multilevel inverter is a power electronic device with low switching losses and low total harmonic distortion that is used in high voltage and high power applications (THD). In a standard inverter, it’s often used to minimise the size and number of passive filters. The H-bridge topology is needed for the proposed model of reduced switch count multilevel inverter (RSC – MLI). It is used to achieve higher power ratings as well as to promote the use of renewable energy sources. It reduces switching errors and the number of power electronic switches, cost and lower order harmonics. As the number of levels and steps in the waveform increase, the harmonics in the output voltage waveform decrease, resulting in an ideal waveform that looks like a sinusoidal waveform, which reduces the harmonics at the output. Switching losses and power losses can be minimised by using a limited number of switches.

Bearingless PM-synchronous machine with axial active magnetic bearing fed by zero-sequence current

A novel inverter supply for bearingless PM-synchronous motors with magnetic suspension allows the reduction of the number of power electronic switches. Hence, all six motional degrees of freedom of bearingless AC machines may be controlled via 3-phase inverter topologies. In this paper, instead of a bearingless motor consisting of two half motors, one bearingless motor with an additional radial active magnetic bearing is treated. Bearingless machines with cylindrical rotors in contrast to double cone rotors generate – apart from the electromagnetic torque – only radial magnetic forces. Hence, an axial magnetic bearing is used.For this bearing, there is no need for a feeding converter bridge as the bearing coil is fed by the zero-sequence current of the feeding 3-phase inverters. The bearing coil is placed between the two star points of the motor winding. The zero-sequence current amplitude is adjusted by the 3-phase inverters via pulse width modulation. The feasibility of this kind of axial position control is proven by simulation as well as with an experiment with a 1 kW prototype motor up to 60000 min−1.

A Common DC-Bus-Configured Traction Motor Emulator Using a Virtually Isolated Three-Phase AC-DC Bidirectional Converter

An industrial drive testing, with a `real-machine' can pave way, for some serious issues to test-bench and motor. A slight disturbance in control logic amid testing, can damage the physical machine or drive. Such dangerous testing conditions can be avoided by supplanting real motor with a power electronic converter based `Motor Emulator' (ME) test-bench system. The conventional ME comprises of two-stage three-phase AC-DC-AC conversion with first-stage AC-DC as emulator and second-stage DC-AC as regenerating unit. This two-stage power conversion, require independent control algorithm, burdening control complexity as well as the number of power electronic switches are quite significant. Hence, to economize and downsize conventional multistage ME system, this paper experimentally validates a common DC-bus-configured ME system with only the AC-DC regenerative emulator stage. A virtually isolated bidirectional two-level three-phase AC-DC converter is proposed as the regenerative emulator converter in a common DC-Bus-configured ME system. The Proposed converter's operating principle along with mathematical design and control strategy are also presented. To validate the operation of the proposed converter as a common DC-bus-configured emulator, a permanent magnet synchronous motors (PMSM) of 7.5 kW is emulated and its experimental results are presented here.

Application of grid connected multilevel inverter for renewable energy integration

This study investigates the integration concerns of next-generation renewable energy systems, in which the grid is turning more disseminate and accessible. In this case, the Permanent Magnet Synchronous Generator (PMSG) based wind energy conversion systems are expected to be more beneficial. Provision of power quality improvement such as Harmonic Reduction is the basic key to obtain higher utilization of wind energy. This functionality for future systems leads to lower energy cost, and reliable power system. To incorporate the advanced features, a five level cascaded H – bridge inverter, with reduced number of power electronic switches is progressed in this study, that is configured within the renewable source systems such as solar and wind. The study is carried out on a 10 KW PMSG based wind energy conversion system interfaced to grid. The proposed concept is elucidated through modelling, simulating and analysing in MATLAB/Simulink environment.

UAPFs topologies with UPS features for low and medium voltage applications

Some configurations of universal active power filter (UAPF) with uninterruptible power supplies (UPSs) features for single-phase applications are proposed in this study focus on a reduced number of power electronic switches. All proposed configurations, composed by two-leg converters, compensate for current and voltage harmonics and provide power factor control close to one. Comparisons between the structures are made in terms of converters voltage capabilities, shared-leg, and capacitor currents. The model of the systems, including the equations and control system, is detailed described. Steady-state analysis of the proposed configurations demonstrates the existence of a load angle, which reduces the converters current, increasing the efficiency of the proposed systems. A complete set of simulated and experimental results are presented.

Artificial intelligent controller-based power quality improvement for microgrid integration of photovoltaic system using new cascade multilevel inverter

Nowadays, grid-connected photovoltaic (PV) power system is quite popular in many countries. For grid-connected PV power system, to achieve maximum power and good power quality of the system are considered as big challenges. In order to achieve this, artificial intelligent (AI) controller-based maximum power point tracking (MPPT) algorithm has been investigated for PV system as well as a new cascade multilevel inverter (MLI) is proposed for grid integration of PV system. The proposed cascade MLI has been designed with a smaller number of power electronic switches and it can be operated at asynchronous voltage sources, which is most adaptable for PV system. This proposed inverter can reduce the total harmonic distortion (THD) at output side by means of increasing the output voltage level with this power quality of the system has been improved. The microgrid integration of proposed inverter has been controlled by using AI-based voltage source controller and this proposed system is designed and simulated in MATLAB environment at various weather conditions and loading conditions. Finally, prototype model has been developed in laboratory and evaluating its performance. The simulation results and prototype results were verified with IEEE 1547 standard that proves the proposed system effectiveness.

A Novel Cascaded Asymmetrical Multilevel Inverter With Reduced Number of Switches

In this article, a new cascaded multilevel inverter has been presented. In order to produce all voltage levels in output voltage waveform, eight different algorithms are proposed to determine the magnitude of dc voltage sources. This topology is able to increase the number of output voltage levels by using lower number of power electronic switches, driver circuits, power diodes, and dc voltage sources. In addition, the low amount of blocked voltage by power electronic switches is another advantage of the proposed inverter. Comparison results with other recently presented topologies in the literature are provided in terms of power electronic switches, blocking voltage, and number of dc voltage sources. Compared to other topologies, the proposed topology utilizes less number of driver circuits, insulated-gate bipolar transistors, and dc voltage sources. To approve the practicability of the proposed inverter, a prototype of the proposed topology for 57 level has been implemented. The operation and performance of the proposed topology in generating the positive and negative levels is verified through the experimental results on a 57-level inverter.

Fault Localization Strategy for Modular Multilevel Converters Under Submodule Lower Switch Open-Circuit Fault

The modular multilevel converter (MMC) is an attractive option for high-voltage and high-power applications. Fault localization is one of the most important challenges for the MMC consisting of a large number of power electronic switches. Existing literature has not provided a complete fault localization strategy for the MMC under submodule (SM) lower switch open-circuit fault, which only considers the MMC in inverter mode and neglects the MMC in rectifier mode. This article proposes a fault localization strategy for the MMC under SM lower switch open-circuit fault, which is suitable for the MMC not only in inverter mode but also in rectifier mode. This article analyzes the MMC fault characteristics under SM lower switch open-circuit fault, which considers the MMC in inverter and rectifier mode, respectively. Based on two modes' common fault characteristic that the capacitor is charged all the time during the period when the arm current is positive, the faulty SM can be effectively located by the proposed fault localization strategy. The proposed strategy is not only implemented in simulation with professional tool PSCAD/EMTDC but also verified with a downscale MMC prototype in the laboratory. The results confirm the effectiveness of the proposed strategy.

Hardware Implementation of an Enhanced Seven Level H Bridge Inverter with Reduced Switch Configuration

There are various boundaries in extracting power through Renewable energy sources. To reduce the insufficiency and high power demand we need to look up power extracting Techniques. To take out power through divergent sustainable power source assets for example solar energy, Photo Voltaic cell, Wind energy, Multilevel inverter is used .It orchestrates the preferred ac production from a number of dc input sources. The primary focal point of the paper is develop the productivity of level inverter and get better the nature of yield voltage by way of diminish number of power electronic switches. Here MOSFETs are used as switches. In this Paper, Simulation along with hardware design of 7-level cascaded Multi-level inverter and reduced switch multilevel inverter are presented.

Fault Diagnosis and Tolerance Control of Five-Level Nested NPP Converter Using Wavelet Packet and LSTM

The five-level nested neutral-point-pilot (NPP) topology, as a new structure for converters, bears the advantages of a high power density, robustness, and flexibility and is therefore suitable for high-voltage and high-power applications. For a multilevel converter, as the number of power electronic switches increases, the risk of switch failure increases, together with the complexity of fault detection and tolerance control. The requirements for a higher operational stability and reliability continue to grow. However, studies on fault tolerance for multilevel converters are limited. In this paper, a fault diagnosis and tolerance solution for a five-level nested NPP converter is proposed. For the fault diagnosis, a deep learning method integrating the wavelet packet transform and long short-term memory is presented. Both open- and short-circuit switch failures can be precisely detected and located without the requirement of a large sample set. Two software-based control strategies for fault tolerance are adopted, and low-cost hardware reconfigurations are also implemented to prevent failure expansion and ensure continuous operation. Furthermore, the voltages of dc-link capacitors and flying capacitors are effectively balanced with the improved algorithm even when a failure occurs. Finally, the effectiveness of the fault-tolerant strategy are proven by simulations and experiments.

A novel center-tapped transformer based multilevel inverter with common DC source

In this paper, a novel multilevel inverter topology is proposed which uses lesser switches and anti-parallel diodes are eliminated in the circuit configuration of the multilevel inverter. Optimal switching strategy for the inverter using three different Space Vector Pulse Width Modulation (SVPWM) techniques is analyzed based on the power quality indices. The proposed model is simulated and tested using MATLAB/Simulink. Owing to the switching techniques used the harmonic content at the output of the inverter is mitigated which results in a lesser value of total harmonic distortion. Reduced number of power electronic switches results in lesser power loss. The performance of the proposed system is validated with simulation results of conventional multilevel inverters and pulse width modulation control methods. The results for various performance parameters such as efficiency, switching loss, voltage magnitude, and total harmonic distortion are analyzed.

A Generalized Switching Strategy and Capacitor Sizing Algorithm for Granular Multilevel Converters

The granular multilevel converter (GMC) is a multilevel converter built by hybridizing a conventional two-level converter with an asymmetrical cascaded H-bridge converter. Addition of each additional H-bridge submodule doubles the number of the GMC output voltage steps. Thus, with a small number of power electronic switches and associated gate drive signals and circuits, a GMC can offer a high-quality ac voltage to meet the stringent requirements of high-performance drives and grid-tied converters in low and medium voltages. This paper proposes: 1) a generalized switching strategy to control the output voltage as well as capacitor voltages of H-bridge submodules for a GMC with an arbitrary number of submodules $n$ (this proposed strategy is scalable, which allows for easy modification of the voltage rating or the number of the voltage steps of the GMC) and 2) a systematic analysis for optimal sizing of the submodule capacitors to minimize the required total energy of the installed capacitors. Simulation and experimental case studies evaluate the performance of the proposed switching and capacitor sizing algorithms.

Hybrid distribution transformer based on a bipolar direct AC/AC converter

Dynamic states in the power grid - deep voltage sags and swells, voltage fluctuation - can cause faults and defects in sensitive loads and in consequence financial losses. This study presents a voltage conditioner based on a direct PWM AC/AC converter with matrix chopper cooperating with a distribution transformer, called a hybrid distribution transformer (HDT). In comparison with other solutions of hybrid and smart distribution transformers, the proposed HDT is characterised by having a simple construction and small number of power electronic switches, a wide range and continuously variable voltage control character, and good dynamic properties, in combination with a high reliability. The study contains a detailed operational description and the experimental test results of a 1 kVA rated power laboratory model. The experimental tests were conducted in a closed control-loop with a peak detector unit in a feedback path, as well as with various types of voltage perturbation with linear and non-linear loads. In addition, some of the properties of the proposed HDT have been compared with other similar hybrid and smart distribution transformers described in the literature.

Wind Farm Grid Integration Architecture using Unified Expandable Power Converter

This paper proposes a novel unified expandable low switch power electronic converter architecture for grid integration of direct drive variable speed wind turbine (VSWT) system using permanent magnet synchronous generator (PMSG). The proposed unified expandable power converter can interface two or more bidirectional output ports, such as wind generators, energy storages, and grid. The size of the power converter is compact because of fewer number of power electronic switches and protection devices, and its architecture is easily expandable to accommodate more outputs, i.e., in this case, the wind turbines. A generalized sequential space-vector modulation technique is developed based on the operational principle of the proposed converter to control the outputs autonomously in order to track the maximum power point for individual VSWTs-driven PMSGs. It is expected that the proposed approach will reduce the cost of power electronic converters in a wind farm, compared to both ac- and dc-link-based topologies, which are available for the moment.

Optimum structure of a generalized three-phase reduced switch multilevel inverter

This study presents a new generalized three-phase multilevel converter based on the combinations of half-bridge modules along with a three-phase T-Type multilevel inverter. The proposed topology reduces the number of switches and associated gate-driver circuits that attains much higher number of output voltage levels. The optimized structure of the proposed three-phase inverter topology has been developed to obtain the maximum number of output voltage levels of the inverter with a minimum number of power electronic switches and the DC voltage sources. The operation, control and performance analysis of the proposed generalized multilevel inverter have been considered here. A nearest level control (NLC) technique is adopted to generate the gating signal for the proposed three-phase hybrid inverter. A laboratory prototype of a specimen three-phase low power fifteen-level inverter have been designed using twenty four switches and nine voltage sources. The conduction losses of the proposed fifteen level inverter is around 14.71watt/phase compared to 23.26watt/phase in an asymmetrical cascaded inverter. The exhaustive simulations of the proposed three-phase inverter are performed using MATLAB/SIMULINK and the results are verified experimentally and presented for the different modulation index.

Nine-level Inverter based Solar Power Generation for Micro Grid Application

This paper mainly focuses on to design a nine- level inverter for power generation using solar system to produce a nearly sine wave with reduced total harmonic distortion. The input from PV array is boosted using a dc-dc boost converter and fed into the nine-level inverter as three independent voltage sources. The capacitor selection circuit converts the three output voltage sources into a four-level dc voltage and it is further converted into nine-level ac voltage by full bridge converter. Hence the proposed system generates a sinusoidal output which is in phase with the utility voltage. The advantages of the proposed system is, it uses only nine power electronic switches, which results in reduced voltage stress and reduced total harmonic distortion without using any filter in utility side. Whereas, traditional system uses 16 power electronic switches and four independent dc voltage sources to produce a nine-level output voltage. By using minimum number of power electronic switches, the proposed system is compact and robust. Keywords: Capacitor Selection Circuit, Nine-level AC Voltage, Nine-level Inverter, Sinusoidal Output, Total Harmonic Distortion