Modulation Inverter Research Articles

Performance investigations of five-level reduced switches count Η-bridge multilevel inverter

Introduction. This research paper describes a simple five-level single-phase pulse-width modulated inverter topology for photovoltaic grid applications. Multilevel inverters, as opposed to conventional two-level inverters, include more than two levels of voltage while using multiple power switches and lower-level DC voltage levels as input to produce high power, easier, and less modified oscillating voltage. The H-bridge multilevel inverter seems to have a relatively simple circuit design, needs minimal power switching elements, and provides higher efficiency among various types of topologies for multi-level inverters that are presently accessible. Nevertheless, using more than one DC source for more than three voltage levels and switching and conduction losses, which primarily arise in major power switches, continue to be a barrier. The novelty of the proposed work consists of compact modular inverter configuration to connect a photovoltaic system to the grid with fewer switches. Purpose. The proposed system aims to decrease the number of switches, overall harmonic distortions, and power loss. By producing distortion-free sinusoidal output voltage as the level count rises while lowering power losses, the constituted optimizes power quality without the need for passive filters. Methods. The proposed topology is implemented in MATLAB/Simulink with gating pulses and various pulse width modulation technique. Results. With conventional topology, total harmonic distortion, power switches, output voltage, current, power losses, and the number of DC sources are investigated. Practical value. The proposed topology has proven to be extremely useful for deploying photovoltaic-based stand-alone multilevel inverters in grid applications.

Design and Implementation of an Online Efficiency-Optimized Multi-Functional Compensator for Wind Turbine Generators.

In recent years, the penetration of wind power generation has been growing steadily to adapt to the modern trend of boosting renewable energy (RE)-based power generation. However, the dynamic power flow of wind turbine generators (WTGs) is unpredictable and can have a negative impact on existing power grids. To solve this problem efficiently, this paper presents a multifunctional WTG intelligent compensator (WTGIC) for the advanced power management and compensation of power systems embedded with WTGs. The proposed WTGIC consists of a power semiconductor device (PSD)-based bidirectional three-phase inverter module and an energy storage unit (ESU). In order to reduce system costs and improve reliability, efficiency, and flexibility, various control functions and algorithms are integrated via a modularized all-digital control scheme. In this paper, the configuration of the proposed WTGIC is first introduced, and then the operating modes and related compensation and control functions are addressed. An online efficiency optimization algorithm is proposed, and the required controllers are designed and implemented. The designed functions of the proposed WTGIC include high-efficiency charging/discharging of the ESU, real-time power quality (PQ) compensation, and high-efficiency power smoothing of the WTGs. The feasibility and effectiveness of the proposed WTGIC are verified using case studies with simulations in the Powersim (PSIM) environment and the implementation of a small-scale hardware experimental system with TI's digital signal processor (DSP) TI28335 as the main controller.

Review on single‐phase high‐frequency resonant inverters for current sharing in multiple inverter system

SummarySingle‐phase high‐frequency resonant inverters (SPHFRIs) with high power density, fast dynamic response, and high energy conversion efficiency have been widely studied and used in academia and industry. With the development of the modularization concept, the operation of multiple inverter modules is desirable because it can remove the limitations of cost, heat dissipation, and component volume in single inverter operation. However, a critical challenge in multiple inverter systems is that the both the phase and magnitude of the output voltage of each inverter module must be controllable to eliminate circulating currents between inverter modules. Great efforts have been made to solve this problem from three aspects: topology, modulation, and control strategy. In this paper, modulation strategies and topologies of different inverters are presented and reviewed to provide guidance to researchers working in this field. Firstly, multiple inverter system based on the SPHFRI is described and its advantages and disadvantages are analyzed. An important issue in the study of multiple inverter systems is presented, that is, the suppression of circulating current. Secondly, the circulating currents in a multiple inverter system are analyzed and derived from two aspects: (1) magnitude and phase angle and (2) active and reactive currents. Thirdly, the inverters used in the multiple inverter system are introduced, and their operating principles, advantages, and disadvantages are reviewed. A key comparison of several inverters is presented for the benefit of the readers. Fourth, through PI closed‐loop simulation, the performance of different multiple inverter systems for suppressing the circulating current is compared in two situations: (1) with magnitude discrepancy only and (2) with both magnitude and phase discrepancy. Finally, the advantages and disadvantages of each inverter are summarized, and the state of the art and future trends are presented.

Battery energy storage systems environmental noise emission

The use of Battery Energy Storage Systems (BESS) in the electricity grid is rapidly growing due to its ability to bridge the gap between times of energy needs and when certain renewable sources are not generating. The use of battery storage helps the grid to remain stable due to its ability to respond quickly to changes in energy demand. Grid-scale battery storage has the potential to significantly assist in the renewable energy transition. Noise has emerged as a key environmental impact challenge in the development of BESS. But why? In our work with BESS, the noise is commonly associated with the battery and inverter modules’ heating and cooling systems, with the use of fans and compressors being the main emitters. However, the noise levels emitted are highly variable and depend on several factors, including operating conditions, ambient temperatures, and speed drives. We will explore the noise emissions of BESS, and key challenges like: —pathways for mitigating noise, including discussion of options at different project stages, ranging from site selection to commissioning. —challenges in accurate noise emission modeling —explore lessons learnt from a project from the design stage to post construction commissioning testing. Including the noise modeling predictions and their accuracy.

Analog and mixed circuit analysis of nanosheet FET at elevated temperatures

In this paper, for the first time, the performance of 3D Nanosheet FETs (NSFETs) is reported in the inversion (INV), accumulation (ACC), and junctionless (JL) modes at elevated temperatures. It is observed that, as the temperature increases from 25 °C to 200 °C, a decrement of 68% in mobility is observed for INV mode. In contrast, an increment of around 29% in mobility is observed for ACC and JL modes owing to the less scattering effects. Various crucial DC and analog/RF figures of merit (FOMs), such as SS, DIBL, gm, f T, etc, are assessed for different temperatures in all three modes. Further, the impact of temperature on circuit performance is demonstrated. From the circuit analyses, at 25 °C, an increment of around 12% in propagation delay is noticed for the JL and ACC mode inverter compared to the INV mode inverter due to higher I ON for INV mode. However, at 200 °C, JL inverter outperforms INV and ACC modes because of an increment in mobility. Moreover, for ring oscillator (RO), an oscillation frequency of 43.39 GHz, 38.9 GHz and 38.8 GHz for INV, ACC and JL mode ROs at 25 °C, whereas oscillation frequencies of 27.08 GHz, 39.2 GHz and 42.88 GHz are noticed for INV, ACC and JL mode ROs at 200 °C respectively. Though JL NSFET offers less intrinsic capacitances, at 25 °C, the frequency of oscillations (f osc) is high for INV mode because of higher I ON. Whereas, at 200 °C, the JL mode outperforms due to the absence of mobility degradation with temperature. These results will give an understanding of this future generation device at both device and circuit levels.

Adaptive neural dynamic surface control of load/grid connected voltage source inverters with LC/LCL filters

Utilizing passive filters such as L, LC and LCL is preferred to cancel out high-frequency harmonics caused by pulse width modulation of voltage source inverters. However, the LC and LCL filters have shown better harmonic attenuation than the conventional L filter. Nevertheless, the control process of LC and LCL filters is more complicated due to their higher-order dynamics. The problem gets more challenging in the presence of uncertainties such as load and grid impedance variations. To overcome these challenges, two novel adaptive neural dynamic surface controllers are proposed for LC and LCL filters in the load and grid-connected modes, respectively. Meanwhile, the issue of computational complexity inherent in the conventional backstepping method is avoided here by utilizing the dynamic surface control technique. Furthermore, the matched and unmatched uncertainties of LC/LCL filters are approximated via multi-input multi-output radial basis function neural networks. Stability of the closed-loop systems is guaranteed by converging the tracking errors to a small neighborhood of the origin. Simulations are given to illustrate the effectiveness and potential of the proposed adaptive neural dynamic surface control methods under the load and grid impedance changes.

A Bidirectional Grid-Tied ZVS Three-Phase Converter Based on DPWM and Digital Control

In this paper, a bidirectional grid-tied ZVS three-phase converter is proposed. The circuit operation principle in both the rectifier and inverter modes was analyzed. The proposed topology could achieve zero-voltage switching in the six main switches and the auxiliary switch both in the rectifier mode and inverter mode. In addition, the reverse recovery current of body diodes in the main switches was also suppressed. Furthermore, in order to realize the ZVS control scheme under the grid-tied bidirectional power flow condition and reduce the number of switchings, a modified carrier-based discontinuous PWM was proposed to fit the bidirectional switching sequence. Finally, a 3 kW prototype was constructed. Some simulation and experimental results are presented to verify the validity of the proposed circuit topology and PWM control scheme.

EVOLUTION AND DISSEMINATION OF SPECIALIZED STRATEGIES, METHODS, AND TECHNIQUES OF SYNCHRONOUS PULSEWUDTH MODULATION FOR CONTROL OF VOLT-AGE SOURCE INVERTERS AND INVERTER-BASED SYSTEMS

This publication provides a brief historical overview of the development of methods and techniques of pulsewidth modulation (PWM) for voltage source inverters, published mainly in Ukrainian publishing houses and in Ukrainian periodicals. Accent has been done to review of results of investigation of alternative methods and techniques of synchronous space-vector-based multi-zone PWM for inverters with low switching frequency. In particular, in the mentioned publications, the basic strategies, schemes, and algorithms of synchronous multi-zone modulation have been further developed, modernized, modified, and disseminated in relation to new promising topologies of power conversion systems, including: two-inverter-based electric drives with open-end winding of electrical motor; dual three-phase electric drives of symmetrical and asymmetric types; powerful six-phase systems based on four inverters, and two-inverter-based and three-inverter-based photovoltaic installations with multi-winding transformer. It is shown that the developed schemes and algorithms of synchronous space-vector PWM, applied for control of inverter-based systems, provide continuous synchronization and symmetry of basic voltage waveforms of systems during the whole control range including zone of overmodulation of inverters. It provides minimization of even harmonics and undesirable subharmonics (of the fundamental frequency) in spectra of the basic voltages of systems, leading to reducing of losses in systems and to increasing of its efficiency. Based on a comparative analysis of the integral spectral characteristics of the phase and line voltages of systems, recommendations are formulated for the rational choice of schemes and algorithms of synchronous modulation for the relevant installations, depending on the modes of their operation. References 30, tables 2, figures 25.

Voltage-Oriented Control-Based Three-Phase, Three-Leg Bidirectional AC–DC Converter with Improved Power Quality for Microgrids

Renewable energy sources (RESs) and energy storage schemes (ESSs) integrated into a microgrid (MG) system have been widely used in power generation and distribution to provide a constant supply of electricity. The power electronics converters, particularly the bidirectional power converters (BPCs), are promising interfaces for MG infrastructure because they control the power management of the whole MG system. The controller of BPCs can be designed using several different control strategies. However, all the existing controllers have system stability, dynamics, and power quality issues. Therefore, this study demonstrates the development of an LCL-filtered grid-connected bidirectional AC–DC converter’s (BADC) control strategy based on voltage-oriented control (VOC) to overcome these issues. The proposed VOC-based inner current control loop (ICCL) is implemented in synchronous dq-coordinate with the help of proportional-integral (PI) controllers. An observer-based active damping (AD) is also developed in order to estimate the filter capacitor current from the capacitor voltage instead of directly measuring it. This developed AD system helps to damp the resonance effect of the LCL filter, improves system stability, and also eliminates the practical challenges of measuring capacitor current. The proposed controller with AD is able to realize bidirectional power transfer (BPT) with reduced power losses due to the elimination of passive damping and improved power quality, system dynamics, and stability. The mathematical modeling of the suggested system was developed, and the structure of the system model was established in the MATLAB/Simulink environment. The performance of the proposed system was validated with real-time software-in-the-loop (RT-SIL) simulation using the OPAL-RT simulator for a 16 kVA converter system. The real-time (RT) simulation results show that the BADC with the proposed control scheme can provide better dynamic performance and operate with tolerable total harmonic distortion (THD) of 2.62% and 2.71% for inverter and rectifier modes of operation, respectively.

A maximum power point tracking of a photovoltaic system connected to a three-phase grid using a variable step size perturb and observe algorithm

Purpose. The production of electricity from solar energy is necessary because of the global consumption of this energy. This article’s study is based on increased energy extraction by improving maximum power point tracking (MPPT). From different MPPT techniques proposed, the perturb and observe (P&O) technique is developed because of its low implementation cost and ease of implementation. Methods. A modified variable step-size P&O MPPT algorithm is investigated which uses fuzzy logic to automatically adjust step-size to better track maximum power point, compared with the conventional fixed step-size method. The variable step P&O improves the speed and the tracking accuracy. This controller is implemented on a boost DC-DC power converter to track the maximum power point. The suggested controlled solar energy system includes a boost converter, a voltage-source inverter, and a grid filter. The control scheme of a three-phase current-controlled pulse-width modulation inverter in rotating synchronous coordinate d-q with the proposed MPPT algorithm and feed-forward compensation is studied. Results. The photovoltaic grid-connected system controller employs multi-loop control with the filter inductor current of the inverter in the inner loop to achieve a fast dynamic response and the outer loop to control bus voltage for MPPT, the modeling, and control of three phase grid connected to photovoltaic generator is implemented in the MATLAB/Simulink environment and validated by simulation results.

Comparisons of Loss Reduction Techniques Based on Pulsewidth Modulation and Model Predictive Control for Three-Phase Voltage Source Inverters

Due to the lack of comparative studies between discontinuous pulse-width modulation and model predictive control methods for reducing switching losses in two-level three-phase voltage source inverter, a comparative analysis of a generalized discontinuous pulse-width modulation and two model predictive control approaches for reducing switching losses is studied in this paper. Both generalized discontinuous pulse-width modulation and two model predictive control approaches are described and conducted in the simulation and experiment. The output performance is obtained by these methods after conducting in various conditions, including switching frequency, output power, and load conditions. It is validated that the generalized discontinuous pulse-width modulation control scheme achieves a better control performance at steady-state, while two model predictive control schemes have better transient-state performance with a superior dynamic. Additionally, the generalized discontinuous pulse-width modulation approach achieves better reducing switching losses performance and has slightly higher efficiency than that of two model predictive control approaches.

Assessment of Energy Conversion in Passive Components of Single-Phase Photovoltaic Systems Interconnected to the Grid

This paper presents a mathematical analysis of how energy return in grid-connected single-phase photovoltaic systems affects the sizing of passive components. Energy return affects the size of the link capacitor, making it larger than reported in the literature. One of the main points of this article is that an inverter connected to the grid using a DC–DC converter with an appropriate link capacitor is analyzed. The energy return is caused by the value (in Henry units) of the L-filter, which is also analyzed in this paper. The analysis shows that there is a link between the value of the L-filter and the voltage of the DC bus. The analysis assumes two conditions: (1) the DC bus voltage is always higher than the peak value of the grid sinusoidal voltage, and (2) there is a unity power factor at the connection point between the grid and the L-filter. To operate in an open loop, a compensation phase angle is calculated and introduced in the single-phase inverter modulation; this phase angle compensates the phase shift caused by the L-filter, avoiding the use of a phase-locked-loop (PLL) control system. The L-filter ripple current is evaluated by Fourier analysis, and the DC bus ripple voltage is evaluated by considering the energy returned to the link capacitor. The results of the analyses are compared with existing methods reported in the literature. The results also show that, to minimize the value of the L-filter, the DC voltage must be almost equal to the maximum voltage of the grid. Equations to assess the value of the DC-link capacitor and the L-filter in function of their ripples are developed. The results were verified with simulations in Simulink and experimentally.

LSTM-Based Stacked Autoencoders for Early Anomaly Detection in Induction Heating Systems

Due to the contactless operation of cookware on induction heating systems, the temperature of the cookware is measured remotely using thermal sensors placed on the center of the coil. Hence, the measurement error of these sensors increases if the cookware placement is not centered on the top of the coil. Therefore, this study presents a new data-driven anomaly detection method to detect overheated cookware using the thermal sensor of the case temperature of the inverter module. This method utilizes the long short-term memory (LSTM)-based autoencoder (AE) to learn from large training data of temperatures of cookware and the inverter. The learning of the LSTM-AE model is achieved by minimizing the residual error between the input and reconstructed input data. Then, the maximum residual error can be set to be a threshold value between the normal and abnormal operation. Finally, the learned LSTM-AE model is tested using new testing data that include both normal and abnormal cases. The testing results revealed that the LSTM-AE model can detect cookware overheating by using the inverter temperature only. In addition, the LSTM-AE model can detect the faults in the inverter side, such as poor air ventilation and a faulted cooling fan. Furthermore, we utilized different deep learning algorithms, such as the recurrent neural network (RNN) and the fully connected layers, in the internal layers of the AE. The results demonstrated that the LSTM-AE could detect anomalies earlier than the other models.

Grid-Connected Solar PV System with Maximum Power Point Tracking and Battery Energy Storage Integrated with Sophisticated Three-Level NPC Inverter

In this research, a solar photovoltaic system with maximum power point tracking (MPPT) and battery storage is integrated into a grid-connected system using an improved three-level neutral-point-clamped (NPC) inverter. An NPC inverter with adjustable neutral-point clamping may achieve this result. To achieve this result, a modernized NPC inverter is used. Using the three-level vector modulation approach, the correct AC voltage may be generated when DC voltage conditions are present in an unbalanced situation involving an NPC inverter. A higher degree of precision is made possible by this. In-depth information on the many possible NPC inverter designs and modulation strategies was provided. By incorporating the necessary sophisticated algorithms into the NPC inverter, the necessary solar PV-MPPT functionality is made available, allowing for the regulation of power transfer among the solar PV system, the battery, and the grid. Modified INC method is proposed which has a tracking efficiency of 99.5% for varying irradiance. The use of sufficiently sophisticated algorithms makes this a reality. Using simulation with MATLAB/Simulink, we were able to examine an NPC inverter’s performance in several setups. Several amounts of solar irradiation were used to test the battery’s charging and discharging capabilities. The probe turned out to be fruitful. Laboratory testing ensures that the proposed method works by simulating real-world conditions.

Fabrication of Multi-Bit SRAMs Using Quantum Dot Channel (QDC)-Quantum Dot Gate (QDG) FET

This paper presents fabrication of multi-state inverters incorporating SiOx-cladded Si quantum dot in the channel and gate region of driver, load, and access transistors. Experimental characteristics are presented exhibiting 3-state behavior in Quantum-dot Channel (QDC)-Quantum-dot Gate (QDG) FETs having Si quantum dots. It is shown that QDC-QDG-FETs-based enhancement mode inverter configurations are the building blocks of a multi-bit static random access memory (SRAM). QDC-QDG-FETs exhibiting four states can also be used to implement compact 4-state logic and nonvolatile memories or random access nonvolatile memories.

Auxiliary Power Supply System with Parallel-Connected DC–AC Inverters for Low-Floor Light Rail Vehicle

This research proposes a roof-mounted auxiliary power supply (APS) system for 600 VDC low-floor light rail vehicles (LRVs). The proposed APS system consists of five parallel-connected dc–ac inverter modules (modules 1–5). Inverter modules 1 and 2 are three-phase dc–ac inverters for the compressor motors of the air conditioning system, and inverter modules 3 and 4 are three-phase dc–ac inverters for the air pump motors of the air supply system. Inverter module 5 is a single-phase dc–ac inverter for the 220 VAC power supply of onboard electric loads. Simulations and experiments were carried out under variable load torques and output frequencies for modules 1–4 and under full and no resistive loads for module 5. The measured total input current and total input power of the proposed APS system under the full-load condition are 114.36 A and 68.84 kW. The total efficiency of the proposed APS system (modules 1–5) is 97.05%. The proposed APS system is suitable for 600 VDC low-floor LRVs. The novelty of this research lies in the use of five parallel-connected inverter modules, as opposed to the three-phase output transformer or isolated dc–dc converter in the early and conventional APS systems. Specifically, the proposed APS system requires neither a three-phase output transformer nor an isolated dc–dc converter.

An Enhanced Hybrid Grid Connected Photovoltaic System Using Voltage Oriented Controller and Class D Chopper

The performance of a shunt interconnection made from a PV system, a three phase grid voltage supply, and a DC shunt motor (DC load) is investigated The PV system participates with maximum powers to the overall interconnection active power flow. It uses a class D chopper circuitry controlled properly by a typical maximum power point tracker (MPPT) controller. The grid has the role of supplying active power in case of any power deficiency needed by the DC motor load. Similarly, it has also the role of absorbing active power in case of any additional power generated by the PV system and not needed by the DC load. This is done by using an AC/DC power electronic converter. The AC/DC power electronic converter operates either under rectifier or inverter modes. The AC/DC power electronic converter is also operated under the next two conditions: 1-the reactive power expected at the grid voltage bus should be nearly null, 2-harmonics currents often encountered in the grid line currents waveforms should be tolerable. The two latter conditions are fulfilled by using the principle of voltage oriented control (VOC) technique. The performance of the investigated interconnection is simulated in Matlab/Simulink platform. Quite satisfactory results are obtained. The satisfaction about the obtained simulation results persists on being able to integrate easily the PV system with the AC grid while extracting maximum power from the PVG and having a unity power factor at the AC grid bus and less encountered harmonics in the ac line currents.

Novel SVPWM Method Based on Zero-Voltage Notch of Resonant DC-Link Inverter

In order to decrease the switching loss of the auxiliary circuit of the resonant DC link (RDCL) inverter and improve the voltage utilization and system efficiency, this paper presents a new space vector pulse width modulation (SVPWM) method based on the zero-voltage notch of the resonant DC link inverter. This resonant DC link inverter reduces the current stress in the main circuit by paralleling auxiliary switch. And this method makes the operation of the auxiliary resonant circuit (ARC) less frequent, thus reducing the losses of the ARC and therefore improving the system efficiency. At the same time, this method analyzes and compensates for the missing voltage vectors based on the ideal output voltage, so that the inverter output voltage vector under this modulation is the same as the ideal SVPWM output voltage vector. Compared with the original modulation of RDCL inverter, this method does not change the switching sequence, the switching times, and the action time of the vector, while reducing the switching ripple. The effectiveness and feasibility of the modulation strategy is verified in the paper through theoretical analysis as well as experiments.

I-V Characteristics Measuring System for PV Generator based on PDM Inverter

This paper presents a new method to characterize photovoltaic panels. The power electronic converter used is a Pulse Density Modulation (PDM) inverter. In this method, the inverter plays two roles: First, it is a DC inductor emulator. Second, it allows assembly between inductive and capacitive load methods. The PDM inverter is adapted to operate at very high switching frequency. In this application, it avoids the difficulties of making DC inductors with high DC current and its control remains very simple. This is an asset for increasing the power, power density and rapidity of tracers based on this method. The main disadvantage of this method, compared to methods based on DC-DC converter, is the use of twice as many semiconductor components. But this disadvantage can be compensated by a gain on reactive components. The simulations and experimental results of the proposed system are shown.

ВЛИЯНИЕ ИНВЕРТОРНОГО РЕЖИМА ЗАРЯДНЫХ СТАНЦИЙ ЭЛЕКТРОМОБИЛЕЙ НА КАЧЕСТВО ЭЛЕКТРОСНАБЖЕНИЯ ПОТРЕБИТЕЛЯ В ЭНЕРГОСИСТЕМЕ

Recently, issues of increasing the environmental friendliness of technological productions, increasing the exergetic component and energy saving issues have become particularly relevant. Therefore, when organizing and designing electrical supply systems, a more correct solution is the use of an inverter-battery backup power supply system. Such a system will ensure reliable and uninterrupted operation of consumers in the building. The paper considers the solution of the problem of designing the inverter mode of the power supply system for connecting the charging station of electric vehicles to the substation of the city of Novosibirsk. The connected charger of an electric vehicle, being a non-linear load, leads not only to an increase in the load on the power grid infrastructure, but can also be a source of power supply. They can also cause a deterioration in the quality of electricity due to the generation of harmonic distortion. Therefore, special attention is paid to the influence of the inverter mode of electric vehicle charging stations on the quality of power supply to the consumer in the power system. A simulation simulation of the charging station was performed using the MATLAB Simulink software package