Kind Of Inverter Research Articles

Recent advances in leakage current suppression techniques for three-level inverters

As populations grow, the world is at risk of energy shortages. Therefore, solar energy as a renewable energy source has attracted a great deal of attention, and people focus their attention on photovoltaic inverters. However, the inverter has leakage current issues, which even pose a threat to human safety. Therefore, leakage current suppression technology has become a hot research direction in photovoltaic (PV) grid-connected inverter systems. Firstly, in this paper, the author analyzes the circuit principle and topology of the three-level inverter. Secondly, it explains the causes of leakage current in this kind of inverter and summarizes the existing solutions such as space vector pulse width modulation, changing circuit topology, and adding filters. Finally, the author compared the advantages and disadvantages of these solutions and then gave some suggestions for the future development trend of three-level PV inverters as well as the technical challenges, which will help in the subsequent research.

The Design and Simulation of a Stand-Alone Solar Inverter with Improved Efficiency and Power Quality for Home Appliances

An inverter for solar panels is proposed in this paper. The inverter's various components have been tested with MATLAB Simulink. The output of the inverter has been analysed using MATLAB Simulink to determine whether pure sine waves are being produced. There are two kinds of loads that are employed in-house, inductive and capacitive loads. The outputs of the inverter are connected to the loads, and Irms, THDv, and Vrms have been measured. Additionally, the THDv value can be observed by adjusting the PV array's radiation and temperature. Furthermore, Irms and THDv changes can be accompanied by a change in the load value of inductive capacitance. The inverter's accessories, such as the PV array, Buck Converter, DC-DC, battery charge-controller, and battery connectors, are also tested using MATLAB Simulink. This kind of inverter can be used to illuminate buildings, businesses, and industries. Most household appliances run on alternating current, so to renovate DC to AC, an inverter is rummage-sale.

Development Status of Space Vector Pulse Width Modulation (SVPWM) Control Method for Multi-Level Inverter

Inverter has played an important role in power electronics technology since its invention. The traditional 2-level inverter is most widely used due to its simple structure, but it cannot meet the needs of high-voltage and high-power fields anymore. Thus, three-level and multi-level inverters are invented. Although complicated in structure, these two kinds of inverters can output larger voltage, and the voltage distortion rate and the ripple current are smaller. The emergence of different modulation methods also makes up for the defects of multi-level inverters. The improvement and simplification of the control algorithm of space vector pulse width modulation (SVPWM) make multi-level control less complicated. This paper introduces the current status and trends of SVPWM.

Integrated grid forming-grid following inverter fractional order controller based on Monte Carlo Artificial Bee Colony Optimization

The modern power system is becoming a more inverter dominant system. In inverter dominant systems the grids can be controlled using grid forming and grid following converters. Historically the grids are controlled by the separate operation of such kinds of inverters. But often, for small systems or microgrids, the cost of the system and reliability can be improved only by using a single inverter with two different controllers acting based on grid conditions. In this work, a novel Monte Carlo Artificial Bee Colony (ABC) optimized fractional-order PI controllers have been used to develop a single inverter to operate optimally on both grid-connected and islanding conditions. Monte Carlo simulation has been performed for determining the initial optimal search space for the optimizer. The performance of the proposed controller has been compared with two other different optimization algorithms namely, Particle Swarm Optimization (PSO) and Gray Wolf Optimization (GWO). The performance of the proposed controller has been validated in different scenarios by real-time simulation in OPAL-RT.

General Multi-Frequency Small-Signal Model for Resonant Converters

AbstractResonant converters are periodic time-varying system, one of whose distinctive features is the sideband effect. To be specific, when a small-signal perturbation is injected into the converter, a series of sideband frequency components will occur. The two sideband frequency components around the switching frequency determine the small-signal response of the resonant tank if it has sufficient band-pass filtering. Using complex Fourier series, the relationship between different frequency components can be described with a series of gains. This paper derives all the necessary transfer functions between different frequencies for resonant converters. Combining them together forms a general small-signal model of resonant converters. There are multiple frequency components, i.e., the perturbation frequency and two sideband frequencies in this model, hence the name multi-frequency model. Two kinds of inverters, i.e., the full-bridge and half-bridge structure, and three modulation methods, i.e., the switching frequency control, the duty-cycle control, and the input voltage control are considered in this paper. The experimental results verify the validity of the proposed model.

Easy-to-assemble and high quality-factor ESIW filter with post-based soldered inverters in X-band

Empty Substrate Integrated Waveguide (ESIW) devices maintain a compromise between the advantages of classical waveguide technologies, such as high quality factor and low losses, and the advantages of planar ones, like low cost and easy compact integration. Compared with SIW, since ESIW is not dielectric filled, additional advantages are achieved, such as lower insertion losses and resonators with higher quality factor. In recent years several filters and folded filters have been designed in ESIW, using all of them resonators based on irises. An alternative to the use of irises is H-plane cylindrical posts. Although cylindrical posts have been widely used in other technologies like Rectangular Waveguide, SIW or AFSIW, it is the first time that this kind of inverters has been used in ESIW. In this paper, the use of posts in ESIW is proposed and validated through the design and manufacture of a bandpass filter in X-band. Posts are soldered to top and bottom layers after ESIW is assembled, being this kind of filters easier to manufacture and more robust than those based on irises. The designed filter achieves return losses higher than 12 dB and insertion losses lower than 1.6 dB (considering microstrip-to-ESIW transitions) and a quality factor of 918.74.

H5-ZVR Single-Phase Grid-Tied Inverters for Photovoltaic Application

The majority of companies are shifting to renewable energy sources as non-renewable fuels are increasingly depleting. Solar energy is a dependable form of green energy. The solar energy after converting to AC through an inverter it is possible to inject into the grid to support distributed power generation system. Transformerless grid-tied inverters have become popular due to their lightweight and reduced cost. The leakage current does exist in this kind of inverter that deteriorate the performance of the inverter. This paper presents a novel H5-ZVR, H5-ZVRD and H5-ZVRS topologies to address the leakage current issue. These inverters take the benefit of hybrid technology, where H5 inverters are integrated with HB-ZVR topologies. To operate the inverter at its highest performance an appropriate hybrid pulse width modulation is also presented. The inverters are simulated in MATLAB to verify the operation and it is found that the leakage current of the inverters is considerably reduced as compared to HB-ZVR topologies. The leakage current of H5-ZVR, H5-ZVRD and H5-ZVRS are found to be 10 mA, 7.3 mA and 7.3 mA respectively and THD of these modules are 1.03%, 0.91% and 0.91% respectively. Also, the topologies present good common mode and differential mode characteristics.

Finite‐Control‐SetModel Predictive Control for Asymmetrical CascadedH‐BridgeMultilevelGrid‐ConnectedInverter with Flying Capacitor

The multilevel inverter is the most advanced power conversion system, whose main advantage is to improve power quality and efficiency. Cascaded H‐bridge (CHB) multilevel inverter is a kind of inverter that can be selected in the field of motor drive systems, electric vehicles and photovoltaic grid‐connected power generations. However, the CHB multilevel inverters require a great deal of independent direct current (dc) power supplies, which makes the realization of these inverters very complicated in practical applications. In this article, model predictive control for CHB inverter with flying capacitors is proposed to improve the above drawbacks. Simulation and experimental results show that voltage balance of the flying capacitor can be maintained and simultaneously the output voltage of the inverter normally. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

A MULTILEVEL INVERTER WITH REDUCED SWITCH COUNT ANALYSED BY VARIOUS SWITCHING TECHNIQUES

This paper is mainly aims at comparing the reduced switch inverter with general switching and three PWM techniques. Reducing switch count helps to gets cost cut down of inverter by large scale. This also makes compact, logic easy and also easy control. These kinds of inverters are very useful for low power rating or medium power ratings[1]. But high power rating requirements we have to use normal inverters. Here in this paper we are testing the proposed model by 4 different techniques. Such as normal switching and 3 of level shift PWM techniques.

Sensorless Model Predictive Force Control with a Novel Weight Coefficients for 3-Phase 4-Switch Inverter Fed Linear Induction Motor Drives

The sensorless model predictive force control (SMPFC) is a strong method for controlling the drives of three-phase 4(6)-switch inverter linear induction motors. This kind of inverter can be employed for fault tolerant control in order to solve the problem of open/short circuit in 6-switch inverters (B6). This paper proposed a method for the SMPFC of a linear induction motor (LIM) with a 4-switch inverter fed along with DC-link voltage offset suppression. Numerical simulations have been performed on several different LIMs in MATLAB software for determine the weight coefficients of the stator flux and the reduced of the capacitor voltage offset. Then, a relationship has been extracted for determining the weight coefficients of the stator flux and DC-link voltage in the cost function of the SMPFC. Using weight coefficients in the cost function, the B4 inverter voltage vectors under the DC-link capacitor voltage swing were obtained for the exact prediction. The balance among the currents was improved by determining the appropriate value for the weight coefficient of the reduced of the capacitor voltage offset. Simulation results were provided for the validation of the suggested control method.

Reconfigurable Multilevel Inverter With Fault-Tolerant Ability

The cascaded H-bridge multilevel inverter (CMI) is one of the most popular converters, especially in renewabale energy applications. Beyond offering some significant benefits, this inverter suffers from the drawback of employing great number of components which reduces the reliability of the inverter. Thus, designing a scheme to enhance reliability in this kind of inverter is of crucial importance. In this paper, a fault-tolerant structure for the cascaded H-bridge multilevel inverter is designed. Failure rates of the switches and diodes are calculated. Then, by using the Markov method, reliability and mean time to failure (MTTF) of the mentioned inverter, before and after employing the suggested scheme, are evaluated. In order to prove proper performance of the suggested scheme, a laboratory built prototype is employed. The results show that employing the suggested scheme significantly enhances reliability and MTTF of the inverter.

Investigation of a cascaded H-bridge photovoltaic inverter under non-uniform insolation conditions by hardware-in-the-loop test

In this paper, the cascaded H-bridge (CHB) multilevel inverter is employed as a grid connected inverter. This kind of inverter has interesting features compared to conventional inverters, including better efficiency, lower THD, lower common mode current injection, and better waveform quality. Using a series connection of H-bridge cells in this topology, a high modularity is achieved and a stepwise voltage waveform is synthesized at the ac side, leading to lower filter size and complexity. This topology processes the electric power in one stage and does not need any step-up voltage transformer for grid connection. The dynamic performance of control system is studied through simulations and is compared with the conventional approach. In addition, a new voltage estimation approach is proposed to reduce the number of voltage sensors compared to existing methods. The simulation results are presented for a 1.5 kW grid connected 7-level CHB inverter and then the hardware-in-the-loop implementation of the CHB inverter is presented to verify the performance of control system.

Comparison of Various Strategies in DTFC Based Multilevel NPC Inverter Fed Induction Drive for Torque Ripple Reduction

Multilevel inverters have become popular in recent years in high power applications; they provide an effective solution for increasing power and minimizing the harmonics of AC waveforms. The fast response and robust method of conventional direct torque control are used in variable speed drives for the reduction of torque ripple. However, major problems occur at steady-state notable torque, flux, and current pulsations in direct torque control drives. This paper presents various strategies in the direct torque and flux control of induction motors for the reduction of torque ripple based on a multilevel neutral point clamped (NPC) inverter. This kind of inverter is used to achieve better harmonic reductions than the traditional two-level voltage source inverters and the related control scheme serves to minimize semiconductor losses. The performance of an induction motor depends upon a mathematical model that comprises the variations in parameters, common-mode voltage, noise, flux variation, and levels of harmonics in a machine. Here, the torque ripples and voltage saturations are the most substantial problems in electrical drive applications. To overcome this problem, the direct torque and flux control (DTFC) technique based on multilevel NPC inverter topology is developed. Moreover, the various control strategies-based DTFC is proposed for the minimization of torque ripple in IM drives. An improved control scheme is used to optimize the regulation of torque and speed with less torque response. This paper proposes the comparative study of the THD analysis of different control techniques (PI, fuzzy, ANFIS) that is effectively used for harmonic moderation in the design of different NPC multilevel inverter; this goal is achieved as shown from the comparison of simulation results using the MATLAB/SIMULINK environment.

Radio Networks Predictive Control of a T-type Inverter in Wind Energy

A new controlling method of three level inverters is proposed in this paper. Three-level T inverters are widely used in industry for high-power, medium-voltage power conversion and drives. Topics related to power losses due to commutation and quality of the output current is relevant issues in this power range. The neutral-point balancing problem in this topology is another subject that has been studied in recent years. Among the most common control methods for this converter, the literature states are non linear techniques, like hysteresis control, and linear methods, like the use of PI controllers in conjunction with pulse width modulation. The general predictive control scheme is applied here to the inverter. The behavior of the system is predicted for each possible switching state of this kind of inverter. The switching state that minimizes a given cost function is selected to be applied during the next sampling interval following the same strategy.

Control principles of micro-source inverters used in microgrid

Since micro-sources are mostly interfaced to microgrid by power inverters, this paper gives an insight of the control methods of the micro-source inverters by reviewing some recent documents. Firstly, the basic principles of different inverter control methods are illustrated by analyzing the electrical circuits and control loops. Then, the main problems and some typical improved schemes of the ωU-droop grid-supporting inverter are presented. In results and discussion part, the comparison of different kinds of inverters is presented and some notable research points is discussed. It is concluded that the most promising control method should be the ωU-droop control, and it is meaningful to study the performance improvement methods under realistic operation conditions in the future work.

A Novel Multi-Functional Grid-Connected Inverter of Renewable Energy Resources

On the basis of analyzing the synthesis application of p-q (instantaneous reactive power) theory and unit vector template, a multi-functional grid-connected inverter (MFGCI) with auxiliary services on power quality enhancement in micro-grid (MG) is presented. The novel control strategy for achieving maximum benefits from these MFGCI when installed in AC MG access to 3-phase 4-wire distribution systems by isolated transformer at the point of common coupling (PCC). This kind of inverter can not only deliver the power generation of renewable energy sources (RESs), but also can perform as active power filter (APF) at their PCC as well as can improve the efficiency of inverter and decrease the hardware investment. Finally, both feasibility and effectiveness of this new topologies and control strategies of MFGCI are verified by PSCAD/EMTDC.

Data Transmission Optimization Based on Memobus RTU Communication Protocol

The article introduces the constitution and message format of Memo bus RTU Communication Protocol, and provides a method for data transfer optimization through by the analysis of the communication protocol format. This method is fit on the inverter and controller which is based on the Memo bus RTU communication protocol and utilized theRS-485 port while the data being transported. By Considering this kind of inverter's distribution, this paper puts forward a method which is based on dividing by functional data block, able to sequence rankly criterion of the function data block, and able to transport date block divided by the function, thereby, this method decreases the redundancy enormously, elevates the system response speed, and solves the technical problem of controller PID output port's real time remote control to multiple inverters.

Research and Implementation of Single Switch Voltage Clamped Hybrid DC-DC Converter

Recently, micro-inverter has received great attention due to its excellent performance under local shade condition. However, this kind of inverter needs large DC-DC voltage gain to implement grid-connected power generation for single photovoltaic module. This paper presented a new single switch high voltage gain DC-DC converter, which is consist of a double output voltage Boost converter and a flyback converter. The outputs of both converters are connected in series to supply power for the load, so the proposed converter has high voltage gain. Moreover, the input circuit is shared by the boost converter and the flyback converter in this new converter, which facilitates the converter structure and improves the converter efficiency by recycling the transformer leakage energy. The double output voltage boost converter can reduce the turn ratio of the flyback transformer and it can decrease the leakage inductance of transformer and diode voltage stress. In addition, the clamp capacitor can limit the power device voltage stress and simplify the circuit design. The paper analysis the operation process of presented converter and gives the detailed deduction of relevant formula to guide the converter design. Experimental results verify the presented converter.

New Multilevel Mixed Topology Development to Improve Inverter Robustness for Domestic Photovoltaic Installations

Multilevel inverters are well used in grid connected domestic photovoltaic applications because of their ability to generate a very good quality of waveforms, reducing switching frequency, and their low voltage stress across the power devices. However, this kind of inverter has to be modified to both limit common-mode currents and improve the robustness of the system. This paper presents a new mixed 5-level inverter that meets these challenges. The operating principle of the converter is proposed. Several experimental measurements are described to validate this new concept. The output voltage and current and the THD of the output voltage are particularly discussed.

Series Igniters Effects in Metal Halide Lamps Operation With High Frequency Ballasts: Study and Minimization

The use of high frequency (HF) square waveforms is a possible metal halide (MH) lamps supply method which can be implemented by means of non-resonant electronic inverters. This strategy can successfully avoid acoustic resonances appearance in such kind of lamps (theoretically, in a perfect square waveform, no power modulation is found). The main drawbacks of this kind of inverters are the electromagnetic interference emissions and the parasitic effects of the series igniters. This effect can spoil the square waveforms on the lamp, hence injecting HF harmonics in the lamp supply power spectrum, eventually leading to acoustic resonances appearance. In this paper, this effect is studied, in order to limit the values of the parasitic elements of the series igniter compatible with a proper operation of the HF inverter. Once these values are estimated, such an igniter has been built and tested, thus obtaining a practical HF (100 kHz) square waveform inverter with series igniter for 35-W MH lamps