Output Voltage Waveform Research Articles

Quasi-modified-Newton method-based selective harmonic elimination in cascaded H bridge inverters

Multilevel converters have gained significant popularity in medium-voltage and high-power applications due to their numerous advantages over traditional two-level converters. These advantages include reduced harmonic distortion, improved efficiency, and lower stress on power semiconductors. Selective harmonic elimination (SHE) is a modulation method that can be employed with multilevel converters to achieve high-quality output voltage waveforms. In this work, an extension of Broyden’s method, known as the Quasi-Modified Newton Method, is implemented for selective harmonic elimination and accurate calculation of switching angles for a wide range of modulation indices. The proposed method is applied to cascaded H bridge inverters operating at levels 5, 7, and 9. The method offers simplicity, reduced computational burden, and faster convergence, making it easily implementable, reducing total harmonic distortion (THD), and reducing RMSE and MAD errors. The paper includes simulation and experimental results that validate the accuracy and effectiveness of the proposed approach.

A Novel NR-DA-Based ANN for SHEPWM in Cascaded Multilevel Inverters for Renewable Energy Applications

Harmonics is the major power quality problem caused by nonlinear devices, leading to malfunction or operational halt of the system. Low-order harmonics increase vibration and heat generation in motors. Therefore, controlling harmonics in the output waveform is the prime target for industrial applications to avoid economic loss. Selective harmonic elimination pulse width modulation (SHEPWM) is one of the techniques used for eliminating or minimizing selected harmonics in the output voltage waveform. This paper utilizes the Newton-Raphson method and Dragonfly Algorithms to calculate optimum switching angles for a Cascaded H-bridge Multilevel inverter (CHBMLI). The algorithms use non-linear equations to calculate the Switching Angles of MLI. The Dragonfly algorithm requires several iterations to reach an optimum solution. For complex problems, this algorithm becomes computationally expensive and time-consuming. A lookup table addresses the limitation by offline training an Artificial Neural Network (ANN) to generate the optimum switching angle for a given modulation index. Neural Fitting Tool in MATLAB software is used to train the ANN model. The simulation is performed using MATLAB SIMULINK software for both 5-level and 7-level CHBMLI configuration. The Dragonfly algorithm-based ANN achieves THD 8.84% when the modulation index (M) equals 0.8 for a 7-level inverter and THD 14.91% for a 5-level inverter and effectively minimizes third and fifth-order harmonics.

A Five-Level Common-Ground Inverter with Dynamic Voltage Boost and Fewer Elements for Photovoltaic Applications

Transformer-less multilevel inverters (TL-MLIs) are the subject of recent research due to their high-voltage or high-power capacity to convert low-voltage output from renewable energy sources into the desired output. They are also less expensive and smaller than traditional varieties. Nevertheless, leakage current is a common problem with these inverters. The proposed inverter aims to address this issue to the maximum extent possible. In the proposed inverter structure, there is a common ground for the input and output terminals. As a result, the overall common mode voltage (CMV) remains constant. This common ground feature short-circuits the Photovoltaic (PV) source to the grid parasitic capacitor, resulting in negligible leakage current. Furthermore, the proposed inverter boosts output voltage using the least amount of power devices and a single voltage source. The proposed inverter can be used modularly, increasing the number of output levels that can be achieved. The simulation results from MATLAB/Simulink and the conclusion of the mathematical analysis for the proposed inverter are shown. The results also demonstrate the output voltage boost capability, zero leakage current, and an appropriate total harmonic distortion for the output voltage and current waveforms.

The Analysis and Research of the Integrated, 30 A MOSFET Gate Driver Dedicated to High-Frequency Applications

This paper presents basic properties and laboratory tests of a commercial integrated high-frequency MOSFET gate driver IXRFD631 operating in the frequency range up to 30 MHz. The MOSFET driver has been tested for two operating states: in the idle state (no load) and at the gate load of a DE275-501N16A series MOSFET transistors. The obtained laboratory results were compared with three other commercial integrated drivers: DEIC420, DEIC515 and IXRFD630 (which are the base structures), and two previous solutions from the author (4xUCC27516 and 8xUCC27526). Additionally, this paper presents the characteristics of power losses and efficiency, measurements of switching and propagation times of the tested gate drivers. Also, this paper presents the output voltage waveforms of the integrated driver IXRFD631 for two operating states. The integrated circuit IXRFD631 of the gate driver is characterized by an efficiency of up to 70% for the tested frequency range, the power losses for two operating states (at idle state—15 W, at gate MOSFET load—43 W) and switching times of 2 ns for an operating frequency of 30 MHz.

MPPT algorithm based on metaheuristic techniques (PSO & GA) dedicated to improve wind energy water pumping system performance

This paper presents a comparative study between four techniques recently used to improve the wind energy conversion system (WECS) to water pumping systems. The WECS is a renewable energy source which has developed rapidly in recent years. The use of the WECS in the water pumping field is a free solution (economically) compared to the use of the electricity grid supply. The control of WECS, equipped with a permanent magnet synchronous generator, has the objective of carefully maximising power generation. A comparative study between the proposed Fuzzy Logic Control, optimised using a genetic algorithm and particle swarm optimisation algorithm, and the conventional Perturb and Observe MPPT method using Matlab/Simulink, is presented. The performance of the proposed system has been verified against the generated output voltage, current and power waveforms, intermediate circuit voltage waveform, and generator speed. The presented results demonstrate the effectiveness of the control strategy applied in this work.

Performance Investigation of 17 Level Reduced Switch Count Multilevel Inverter

The primary objective of this paper is to introduce a 17-level multilevel inverter with only eight power switches and three diodes that can be suitable for electric vehicle applications. This setup utilizes three distinct unequal DC sources to create the 17 levels of output voltage waveforms. The modes of operations of the proposed topology have been discussed in detail. The calculation of conduction losses, switching losses, efficiency, total standing voltage, and cost function per level for the suggested inverter has been elaborated. Due to more semiconductor power switches, diodes, capacitors, driver circuits, and DC sources in typical inverters, switching losses, costs, and harmonic distortion are increased. The nearest-level control technique has been utilized to control the switching elements of the recommended configuration. The performance comparison of various multilevel inverter topologies has also been discussed. The suggested multilevel inverter provides a higher efficiency of 98.60%, cost function of 3.6 for a weight coefficient of 1, improved power quality, and higher reliability. A reduction in the power switches significantly reduces the convolution of switching circuitry. The total harmonic distortion produced by this inverter is 3.49%, which comes under the IEEE standard of 5%.

A new method for selecting optimum levels in asymmetric Cascaded H‐Bridge‐Multilevel Inveter with variable DC sources

SummaryIn general, cascaded H‐bridge multilevel inverters (CHB‐MLI) are typically operated with either symmetrical or asymmetrical input DC sources, set at predefined specific ratios such as binary (1:2) or trinary (1:3) in the case of asymmetry, to achieve the desired output voltage waveform. However, if any DC source fails to provide the predefined voltage magnitude, or CHB‐MLIs with unspecified DC source ratios are utilized, the output voltage waveform may exhibit unequal magnitudes between consecutive levels, thereby causing a significant increase in total harmonic distortion (THD). Conventionally, to mitigate this effect, the corresponding H‐bridge is bypassed through zero voltage switching, which leads to an additional burden on the remaining H‐bridges to serve the same load. To reduce the burden on the remaining cells and improve the THD profile of the inverter, this article proposes a novel method for CHB‐MLI with varying DC magnitudes. It aims to enhance the quality of the output voltage waveform by strategically selecting optimum voltage levels rather than utilizing all available levels when CHB‐MLI has unspecified or variable DC sources. This approach can achieve a more balanced distribution of voltage magnitudes across successive levels by eliminating redundant states. Moreover, the proposed technique can reduce switch losses and enhance the converter's efficiency. The proposed method is validated through MATLAB/Simulink software simulations, followed by experimental verification.

Single-Stage MV-Connected Charger Using an Ac/Ac Modular Multilevel Converter

Modular multilevel converters with non-sinusoidal ac voltage output can reduce cost and volume in medium-voltage-connected electric vehicle battery charging applications. The use of full-bridge submodules in such converters enables single-stage ac/ac voltage conversion, allowing a medium-voltage grid to be directly connected to a medium-frequency isolation transformer. The application of a square wave voltage at the medium-frequency transformer’s single-phase port enhances the converter’s efficiency and power density in comparison to a sinusoidal voltage. This paper presents the analysis and modelling of a modular multilevel converter, comparing its operation with sinusoidal and square wave output voltages. A single control scheme for both output voltage waveforms is proposed for the three-phase and single-phase ac currents, circulating currents, and the energy stored in the submodule capacitors. The control strategy of the three-phase and single-phase port currents is verified through simulation and experiments using a scaled-down prototype, thereby validating its suitability for high-power bidirectional battery chargers.

An Interactive Pedagogical Tool for Simulation of Controlled Rectifiers

Active learning approaches, incorporating student engagement through experimentation and problem solving, effectively foster higher-level thinking abilities and enhance academic performance. Interactive tools like simulators align with these methodologies, but commercially available simulators have limitations; particularly, their high cost and lack of customization features pose significant challenges for many educational institutions. This article presents CORES, a web-based educational application designed to simulate controlled rectifier circuits. CORES eliminates the need for intricate circuit assembly and software installation by providing pre-built circuits so that users can concentrate on analyzing circuit behavior by manipulating the thyristor firing angle and load characteristics, while the application generates output voltage and current waveforms under steady-state conditions, minimizing computation time. CORES has proven to be a valuable pedagogical tool, surpassing commercial simulators in terms of accessibility, ease of use, and enriched learning experiences for power electronics students and educators.

Physical reservoir application of random network of gold nanoparticles fabricated by multi-step immersion in gold colloidal solution

We fabricated a random network of gold nanoparticles (RN-GNPs) over 12 NiCr/Au electrodes by using a multi-step immersion method, where a sample was immersed in a gold colloid solution three times. Nonlinear current–voltage characteristics due to the Coulomb blockade were observed at 77 K. For demonstration of physical reservoir applications, input–output characteristics of the RN-GNPs were also measured in a one-input, nine-output terminal configuration. Distorted output voltage waveforms were obtained for a sinusoidal voltage input of 100 Hz. The higher-order harmonic components were confirmed in the frequency spectra of the outputs. The waveform reconstruction task and short-term storage capacity estimation were performed by an echo state network model with ridge regression and linear regression, respectively.

Design and Performance Analysis of Photovoltaic Power Generation Light Emitting Diode Device

This research focuses on an independent photovoltaic power generation system with supercapacitor energy storage as the study subject. The model is simplified, and the photovoltaic power generation light emitting diode (LED) device is designed based on the given parameters. This system selects a Boost-type step-up converter for the supercapacitor charging circuit, capable of achieving Maximum Power Point Tracking (MPPT). The supercapacitor discharge circuit employs an LM2596 series regulator to power the rated load LED (12 V, 1 W), providing good linear regulation capability. In designing other hardware components of the device, the characteristics of a photoresistor are utilized to implement an automatic load switch circuit. An efficient single-chip integrated circuit LM2575 series is used as a regulator to convert the voltage across the supercapacitor terminals to +15 V and +5 V. Considering the need to collect the output voltage of the photovoltaic cell array and the voltage across the supercapacitor terminals, a resistor divider method is used to sample these two voltages. The sampling circuit includes a resistor divider circuit and a linear optocoupler isolation circuit. An HNC-25LTS series Hall current sensor is used for current sampling to measure AC, DC, and pulse signals under electrical isolation conditions. The supercapacitor, solar photovoltaic panel, control unit, and the main circuit for supercapacitor charging and discharging have been assembled in the experiment. Connecting the charging and discharging circuit with the photovoltaic panel and LED, the system provides power to the LED during the night. Under varying light intensity and temperature conditions, the photovoltaic output voltage waveform, PWM waveform, and Boost circuit output voltage waveform remain stable when reaching the MPPT point. The output power with added MPPT control at different times is compared. The results indicate that the designed system has effectively achieved the functionality of MPPT for solar energy.

Multicarrier PWM techniques for three phase modular multilevel converter application in MRI systems

This research paper presents about the performance analysis of three phase modular multilevel converter with level shifted (phase disposition pulse width modulation) and phase shifted pulse width modulation (PWM) method. This research not only discusses the significance of different modulation procedures in the context of modular multilevel converters but also carefully evaluates each of their unique performance characteristics. This research is based on the fundamental creation of pulses and patterns that can only be acquired by comparing sinusoidal reference signals with triangular carrier signal. Both levels shifted (phase disposition) and phase shifted PWM procedures are used to calculate the phase output voltage of a converter at 2N+1 level. The output waveform is crucially shaped by these modulation techniques, which also ensure effective energy conversion and lower harmonic content. On the basis of the output voltage waveform's quality, the comparative research is conducted and simulated results were presented.

Comparative Analysis of 5-Level and 7-Level Single-Phase Cascaded H-bridge Multilevel Inverters

The demand for high-performance, efficient, and reliable power electronic systems has been steadily increasing in various industrial applications, including renewable energy systems, electric vehicles, and smart grids. In response to this demand, the Cascaded H-Bridge Multi-level Inverter (CHB-MLI) has emerged as a promising solution, offering advantages such as improved voltage waveform quality, reduced harmonic distortion, and enhanced power handling capabilities. The CHB-MLI is characterized by its modular structure, comprising multiple H-bridge cells cascaded in series. Each H-bridge cell operates with a separate DC power source, enabling the generation of stepped voltage levels at the inverter output. By intelligently controlling the individual H-bridge cells, the CHB-MLI achieves the synthesis of a high-quality multilevel output voltage waveform. The different multi-level inverter topologies are Diode-Clamped MLI, Capacitor-Clamped MLI and Cascaded H-bridge MLI. This paper focused on key aspects like design, simulation, control strategies, performance evaluation, overall comparison and analysis of 5-level and 7-level CHB-MLIs. By addressing these aspects, this paper aimed to contribute to the advancement of power electronics technology and promote the adoption of the CHB-MLI in real-world applications, fostering energy efficiency and sustainability in power conversion systems. Index Terms: Inverter, Multi-level inverter, CHBMLI, switching, SPWM, MCSPWM, gate signal, waveform, harmonics, THD, MATLAB.

Design of LC Filter with Shunt Damping Resistor for Non-linear Load to Reduce the Total Harmonic Distortion in Load Voltage

The electrical power distribution system is the part of a power system, which supplies electrical power to consumers for utilization. Recently the utilization of nonlinear loads has been increasing in distribution system which badly affected the sinusoidal output voltage waveform. Every consumer of electricity demand consistent and sinusoidal voltage waveform to run their loads properly but due to power quality issues such as harmonics, voltage sag, voltage swell, flickering, and interruption of power supply which badly affect the output voltage of the loads may result in equipment damages, and financial loss. This research study discusses the voltage harmonic which is one of the power quality problems. The harmonic is a Non sinusoidal waveform that is generated due to the applications of nonlinear loads which affect the power system reliability, increase the transformer losses, line losses, and frequent faults are generated which results in poor utility revenue, and reduction in production in industries. So, in this research study, the LC filter with a damping resistor is designed to improve the output voltage waveform. The MATLAB simulation model is developed to analyze the performance of the distribution system under linear and nonlinear loads with and without an LC filter circuit and also THD% is analyzed through FFT.

Waveform Optimization Control of an Active Neutral Point Clamped Three-Level Power Converter System

Currently, the escalating integration of renewable energy sources is causing a steady weakening of grid strength. When grid strength is weak, interactions between inverters or those between inverters and grid line impedance can provoke widespread oscillations in the power system. Additionally, the diverse DC voltage application characteristics of power converter systems (PCS) may lead to over-modulation, generating narrow pulse issues that further impact control of the midpoint potential balance. Existing dead-time elimination methods are highly susceptible to current polarity judgments, rendering them ineffective in practical use. PCS, due to inherent dead-time effects, midpoint potential imbalances in three-level topologies, and narrow pulses, can elevate low-order harmonic content in the output voltage, ultimately distorting grid-connected currents. This is particularly susceptible to causing resonance in weak grids. To enhance the output voltage waveform of PCS, this article introduces a comprehensive compensation control strategy that combines dead-time elimination, midpoint potential balance, and narrow pulse suppression, all based on an active neutral point clamped (ANPC) three-level topology. This strategy gives precedence to dead-time elimination and calculates the upper and lower limits of the zero-sequence available for midpoint potential balance while fully compensating for narrow pulses. By prioritizing dead-time elimination, followed by narrow pulse suppression and finally midpoint potential balance, this method decouples the coupling between these three factors. The effectiveness of the proposed method is validated through semi-physical simulations.

Hierarchical Control of AC/DC Hybrid Microgrid Based on Primary Model Predictive Optimization and Secondary Switching Control

The fluctuating characteristics of renewable energy generation in hybrid AC/DC microgrids, combined with timevarying loads, can result in high total harmonic distortion (THD) and distorted output voltage and current waveforms. To address these issues, a faster and more comprehensive primary and secondary hierarchical control method is required. In this paper, a faster model predictive optimization algorithm is introduced as a primary control method to predict operational states in advance, maintain a low THD state, and reduce the impact on power quality. Then, a secondary switching control is added to correct frequency and power allocation errors caused by primary control, recover microgrid voltage and frequency to their rated values, and ensure stable reactive power. Finally, simulation and comparison results prove the proposed method's effectiveness and applicability.

Dual‐input step‐up switched‐capacitor multilevel inverter with reduced voltage stress on devices

SummaryThis paper proposes a single‐phase dual‐input step‐up switched‐capacitor multilevel inverter that employs three capacitors, 15 switches, and two diodes to provide 13 voltage levels and triple‐voltage boosting factor in its symmetric form and 37 levels with voltage boosting factor of 3.6 in its asymmetric version. This high boosting factor is accomplished without utilizing any transformer. For each output voltage level, there exists flow paths for both the positive and negative load current directions, which makes the proposed inverter capable of supplying any load type with variety of power factors (zero to unity). The voltage balancing of the capacitors takes place naturally, which tackles the need to auxiliary charge‐balancing circuits or control mechanisms. The proposed inverter can generate negative levels without the end‐side H‐bridge. Moreover, the voltage stress on the semiconductor devices is less than the peak output voltage. The increased number of levels and sinusoidal‐like waveform of the output voltage waveform enhances the quality and lowers the harmonic content of the load voltage and current waveforms, even for resistive loads. As the result, the load‐side filter can be downsized or removed. This paper employs the fundamental frequency method (FFM) as the switching technique, which is simple to implement and also operates the switches at low frequencies, leading to lower switching losses. The ascendancy of proposed inverter over similar counterparts has been investigated through comprehensive comparative analysis. Moreover, the correct performance of the proposed inverter at different modulation indices, and load types as well as during dynamic load changes has been verified by simulation and experimental analysis.

The Implementation of Space Vector PWM in 36-Pulse D-STATCOM for Power Quality Improvement

Introduction: This paper addresses the ongoing challenge of harmonics reduction in power systems, particularly focusing on Flexible AC Transmission Systems (FACTS) devices. Instead of employing a conventional multilevel converter, an alternative configuration is proposed: a 36-pulse gate turn-off thyristor-based converter (GTO-VSC). This converter comprises three 12-pulse Voltage Source Converters (VSCs) as fundamental units, operating collectively on the frequency mode of GTO switching control within a Distribution Static Synchronous Compensator (D-STATCOM). The D-STATCOM dynamically compensates reactive power in the system. The 36-pulse configuration results in AC output voltage waveforms containing harmonics such as the 35th, 37th, 71st, 73rd, etc., leading to higher total harmonic distortion (THD) levels. background: Reduced number of switches in flexible AC transmission. Method: In response, the paper presents a new model featuring a 3-level, 36-pulse, 25kV, ±3MVAr STATCOM configured with 12-pulse GTO-VSCs. This model incorporates PWM gate switching and employs a PI-control methodology to optimize harmonics in simulation, specifically targeting harmonics at the 35th, 37th, 71st, 73rd, etc., orders using Sim Power Systems toolbox in Math Works software. Result: The compensator's operational performance is controlled through switching angle optimization, which minimizes harmonics, regulates voltage, and manages reactive power in the electrical transmission system. Conclusion: The simulation results demonstrate that the proposed model is acceptable for enhancing the flexibility and performance of the FACTS device in mitigating harmonics in power systems.

Multilevel Inverter with Enhanced THD Value used in Grid Connected Applications

In this work, the relationships among pulse width modulation (PWM), sinusoidal pulse width modulation (SPWM), and space-vector pulse width modulation (SVPWM) for three-phase inverters will be analyzed to better comprehend their differences. detailed comparison of the three modulation schemes under study’s Total Harmonic Distortion (THD). High-power applications are increasingly concentrating on converter technology. This growing importance may be attributed to its improved output waveforms over the 3- carrier-based sinusoidal pulse width modulation (SPWM). To control and modulate multi-level inverters, many techniques are employed. These methods are categorized based on how frequently they switch. The ripple current rating, capacitance value, and voltage balance in the DC bus capacitors are all impacted by the pulse width modulation techniques. It is crucial to select the modulation method based on the current control requirements, as this determines the output voltage waveform’s harmonic content. SVPWM is gradually becoming more and more popular in industries because of its improved dc bus utilization and ease of digital realization. This work examines PWM, Sinusoidal, and SVPWM feeding a load connected to RL. Three different methodologies’ performances are compared as these methods are investigated through simulation with MATLAB/SIMULINK software.

Power quality investigation with multilevel inverter by photovoltaic-fed dynamic voltage restorer

ABSTRACT In this research endeavor, a novel approach has been presented to enhance the power quality through a Photovoltaic (PV)-based Dynamic Voltage Restorer (PV-DVR). The proposed work is designed to address voltage fluctuations, flicker, and harmonics within medium or low voltage micro-grid systems. Unlike existing DVR systems that often neglect injected harmonics and converter losses, in the proposed work there is an integration of a PV-fed multilevel inverter system employing Selected Harmonic Elimination and Moderation-based Pulse Width Modulation (SHEAM-PWM). This innovative configuration, coupled with a DC – DC boost converter and a series injection transformer, not only aims to alleviate voltage stress on devices but also optimizes the number of switches to minimize switching losses. The proposed setup successfully reduces the overall voltage Total Harmonic Distortion (THD) to a significant extent, delivering superior dynamic performance. To determine optimal switching angles for the SHEAM-PWM technique, ensuring the elimination or mitigation of the maximum number of harmonics from the output voltage waveform, we employ the Biogeography-Based Optimization (BBO) approach. The computation of these angles is performed offline to eliminate lower-order harmonics, and the results are stored in the microcontroller’s memory using mixed model equations for online applications. The efficacy of our proposed method is demonstrated through both simulation and experimental validation in a real-time laboratory system. The simulation and experimental results obtained underscore the potential utility of our technique for Dynamic Voltage Restorer (DVR) applications, particularly those requiring low harmonic injection. The proposed method introduces a comprehensive and innovative solution for power quality enhancement, combining PV technology, multilevel inverter systems, and advanced optimization techniques. The proposed PV-DVR system exhibits promising results, showcasing its potential for practical implementation in residential micro-grid systems with a focus on minimizing harmonics and ensuring efficient grid compensation.