Search

This study presents a comprehensive examination of space vector pulse width modulation (SVPWM) and switching frequency optimal PWM (SFOPWM) for an F‐type multilevel inverter (FTMLI). SVPWM offers a simple, digital implementation for three‐phase, three‐level inverter structures, and carrier‐based SFOPWM allows for maximum use of switching frequency with a simple construction. This approach reveals the underlying relationship between the above two PWM techniques with various amplitude and frequency modulation indices to ensure the performance of FTMLI. A suitable comparative study was carried out to verify the PWM techniques based on the inverter output voltage, total harmonic distortion, switching stress, and filter size. The analytical conclusions are supported by the simulation results and their experimental validation. [ABSTRACT FROM AUTHOR]

To enhance the dynamic performance and robustness of the voltage control system of islanded microgrid inverters, a new control strategy combining integral sliding mode (ISM) control and composite nonlinear feedback (CNF) control is proposed. In ISM control, firstly, a new reaching law is designed to improve movement quality in the reaching phase by improving the power term and introducing the inverse tangent function. Then, to improve disturbance observation accuracy, a variable gain extended state observer is designed by improving the regulation mechanism of the state variables according to deviation control. Using the idea of variable damping, linear and nonlinear feedback are combined into CNF control. Specifically, linear feedback provides a small damping ratio for faster system response, while nonlinear feedback increases the damping ratio to improve steady‐state performance. Simulation results show that the integral sliding mode‐composite nonlinear feedback (ISM‐CNF) control strategy cam balances convergence speed and chattering better and achieves higher steady‐state accuracy than conventional strategies. Moreover, ISM‐CNF control has better robustness to reference voltage variations and disturbances caused by sudden load changes. Therefore, the ISM‐CNF control strategy can accomplish voltage control of islanded microgrid inverters quickly and steadily, effectively suppressing system disturbances and enhancing stability and power quality. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The working conditions of the explosion-proof hoist inverter are particular. During heavy load and frequent lifting, power devices of the inverter will generate considerable power loss, which often leads to overheating or even damage to power devices and reduces the thermal stability of the whole system. This study proposes a quasi-deadbeat model predictive current control (QD-MPCC) strategy based on the neutral point clamped (NPC) three-level inverter. First, the QD-MPCC quasi-beat controller of the induction motor is designed, the digital delay compensation strategy is developed, and a closed-loop flux observer is adopted to improve the flux observation accuracy. Second, the traditional QD-MPCC strategy is improved. The loss model of the NPC three-level inverter applied to the explosion-proof hoist is established. Then the loss result calculated according to the predicted current is taken as the new control target, and the loss is dynamically optimized according to the operating curve. Finally, the robustness of the improved QD-MPCC strategy and its effectiveness in online power-loss management to improve the thermal stability of the system are verified by simulation and experiment. [ABSTRACT FROM AUTHOR]

Wind farms with type IV wind turbines from various manufacturers are being massively put into operation. These wind turbines comply with the requirements of the grid codes of the countries where they are designed and/or manufactured, but do not factor in the specific features of the distribution networks of other countries to which they are connected. The study at issue involves a comparative analysis of the requirements of grid codes of different countries for the stable operation of wind turbines under standard disturbances. The low voltage ride through (LVRT) characteristic makes it possible to prevent wind turbine shutdowns in case of short-term voltage dips of a given depth and duration. The calculations of transient processes indicate that wind turbines may not meet the requirements of the grid code of a particular country for their stable operation. As a result, standard disturbances will block the reactive current injection and the wind turbine will be switched off. This is often caused by the relay protection devices with a time delay of 1–2 s, which are used in distribution networks and implement the functions of long-range redundancy. Excessive shutdowns of wind turbines lead to emergency rises in the loads for the generating units of conventional power plants, aggravating the post-accident conditions and disconnecting consumers of electricity. This article presents a method for checking the LVRT characteristic settings for compliance with the technical requirements for wind turbines. To prevent wind turbine outages, one should either change the configuration of the LVRT characteristic, upgrade the relay protection devices in the distribution network adjacent to the wind farm, or implement group or individual technical solutions at the wind farm. The performance of the proposed technical solutions is confirmed by the calculations of transient processes. [ABSTRACT FROM AUTHOR]

This research seeks to combine a comprehensive analysis of the literature regarding energy efficiency and inverters with an analysis of a configuration of a hybrid energy system including a generator, an inverter and a battery. The inverter's power output is analyzed under the influence of different distribution functions during a robust modulation procedure for achieving optimum energy saving. The modulation is tested on two processing machines independently: (a) an electric discharge machine, and (b) an injection molding machine. Based on the research methodology, problem formulations and the conducted analysis, a novel research software called "Inverter Pro V1" was programmed to analyze the estimations and performance of inverters in an energy system. An optimal levelized cost of electricity was determined given certain systems design and operating hours, and a sensitivity analysis was undertaken that identified a range of energy savings. In the sensitivity and optimization analysis, interactions among the primary decision parameters including the system's capacity, operating time, energy saving, cost of energy and payback period are investigated. It is also found that for each system, the inverter modulation categories with the optimum payback period belong to a modulation of inverter designed according to the Sawtooth function with a 45% duty cycle and switching intervals of 0.35 s. By considering the operating hours of 12.5 h per day, and the calculated system's investment cost of €31,782.158, the optimum payback period is estimated to be 1.7729 year. The study results are to inform policy with regard to assisting sustainable electricity production. [ABSTRACT FROM AUTHOR]

Multilevel inverters (MLIs) have gained traction for their application in high-voltage AC systems and renewable energy. They use fewer DC sources and switches in transformer-based designs to attain the necessary output voltage magnitude. Creating an efficient, high-gain MLI with reduced sources and switches demands meticulous design and substantial effort. This paper introduces a new multilevel inverter design utilizing a toroidal transformer with a reduced number of components. The new topology incorporates ten transistors and a single toroidal transformer. These components are arranged as two H-bridge modules and a bidirectional switch with a transformer to generate nine voltage levels. Notably, the inclusion of three complementary switch pairs in the inverter circuit simplifies the control strategy of the proposed inverter. This configuration enables the inverter to achieve more voltage levels and higher voltage gain using fewer components. Comparison with other existing nine-level inverters highlights the effectiveness of the new design in minimizing the cost function value. The performance assessment of the proposed inverter employs a cost-effective solution. Simulation and experimental results are provided to showcase the practicality and efficiency of the proposed nine-level inverter. [ABSTRACT FROM AUTHOR]

This study proposes a new control strategy for the quasi Z-source two-level three-phase inverter, accurate discontinuous SVM (AD-ZSVPWM). The proposed AD-ZSVPWM control technique enhances the output power quality by reducing total harmonic distortion (THD) and conduction losses. Low THD is achieved by increasing the algorithm's accuracy using a division of six vector states in each switching period and the distribution of six shoot-through states within the period. The conduction losses are reduced by splitting each sector into two subsectors of 30°. The proposed control scheme has the following advantages: reduced THD, low conduction loss, and increased boosting factor. MATLAB/Simulink software is used, and an experimental test is conducted to validate the proposed strategy. PLECS software is utilized to calculate the switching and conduction losses. For experimental verification, a hardware test bench comprising a dSPACE DS1104 board that controls a three-phase quasi Z-source inverter that supplies an R-L load is used. Simulation and hardware results show that the proposed scheme provides improved performance in terms of power quality and power loss reduction. [ABSTRACT FROM AUTHOR]

Grid-connected systems are increasingly becoming essential complements to existing electricity infrastructures in many developed countries. Among renewable energy systems, photovoltaic (PV) panels are the most utilized and efficient. However, integrating PV systems into the main grid presents substantial challenges. To overcome these issues, this paper presents a comprehensive approach through the design, control, and hardware implementation of a cost-effective grid-connected PV (GPV) system. Focusing on practical and economical solutions, this research transcends theoretical simulations by developing a tangible laboratory-scale prototype. This prototype integrates both power and control subsystems to ensure efficient and reliable operation of GPV systems. The power subsystem comprises a three-phase inverter, an LCL filter, and an interface circuit, forming the core hardware for energy conversion and grid connection. The control subsystem incorporates enhanced and advanced control techniques to optimize performance. These include the DSOGI-PLL synchronization algorithm, which guarantees precise grid voltage phase angle detection even when noise and higher-order harmonics are present, facilitating seamless grid integration. Additionally, the Space Vector Pulse Width Modulation (SVPWM) algorithm is employed to control the three-phase voltage source inverter, providing superior DC-link voltage utilization and harmonic performance. A robust current PI controller is also implemented, offering excellent steady-state response and resilience against system parameter variations. The results obtained have proven that the connection of the proposed system can be successfully achieved and implemented. This work promotes the widespread adoption of photovoltaic systems and contributes to global sustainable energy initiatives. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper concentrates on the efficient power outage solution in Nigeria University laboratories using Micro- controller based portable Solar Generator. The design specification include the System Capacity 1000Volts Ampere, modified Sine wave alternating current power, Output Voltage: 220-240 Volts, Output Frequency: 50Hz, battery Bank Capacity: 12Volts/40Ampere-hour, Solar Panel Specification: 30Watts, Pulse width modulator charge controller. During the design a voltage level of 5Volts was fed from preamplifier to the switching Metallic Oxide Silicon Field Effect Transistor that produces the gate current of 0.05 Ampere: Result showed that the oscillator rated output of 5v was obtained at pins 11 and 14 to switch the transistor. Result also showed that the frequency of the oscillator was adjusted and measured until standard frequency of 50Hz was achieved, for the MOSFETs operating at 50Hz and the period of the switching was 0.02sec. The transformer secondary voltage was measured and it gave the expected output of 230v. [ABSTRACT FROM AUTHOR]

A photovoltaic (PV) inverter is a vital component of a photovoltaic (PV) solar system. Photovoltaic (PV) inverter failure can mean a solar system that is no longer functioning. When electronic devices such as photovoltaic (PV) inverter devices are subjected to vapor condensation, a risk could occur. Given the amount of moisture in the air, saturation occurs when the temperature drops to the dew point, and condensation may form on surfaces. Numerical simulation with "COMSOL Software" is important for obtaining knowledge relevant to preventing condensation by using two steps. At first, the assumption was that the device's water vapor concentration was homogeneous to evaluate the amount of liquid water accumulated on the internal walls of the photovoltaic (PV) inverter box. Second, by considering the effect of external wind velocity on moisture transport at the air interface to evaluate water vapor transport outdoors and reduce condensation. General factorial designs are utilized for analyzing the nature of the relationship between the vapor condensation response and the variables. Reducing vapor condensation inside the solar inverter by the effect of external wind speed on diffusion as a process of transporting moister air outside the inverter box is the main solution for this problem. During the movement and assessment of the flow of water vapor, the impact of vapor condensation is reduced. The saturation period was determined by using a Boolean saturation indicator. The saturation indicator was set to 1 when saturation was detected (relative humidity greater than or equal to 1) and 0 otherwise. Calculating the flow and dispersion of moist air as a function of wind speed helped solve the problem. [ABSTRACT FROM AUTHOR]

Copyright of Frontiers of Information Technology & Electronic Engineering is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ambipolar organic electrochemical transistors (OECTs) with a single organic mixed ionic‐electronic conductor (OMIEC) have unique advantages by reducing fabrication complexity and cost in complementary logic circuit and bioelectronic applications. However, the design and synthesis of high‐performance ambipolar OMIECs for efficient transport and coupling both cation/anion and electron/hole remain challenging. Herein, a donor–acceptor (D–A)‐typed ambipolar OMIEC polymer (DHF‐gTT) is presented, whose superior ambipolarity stems from the concurrent oligoethyleneglycol‐functionalized D/A units that facilitates cation/anion injection and transport. Additionally, the fluorination of acceptor unit improves both hole/electron transports due to the fully‐locked backbone and promotes electron injection by down‐shifting molecular energy levels. Consequently, DHF‐gTT‐based OECTs achieve balanced figure‐of‐merit (µC*) for both p‐type and n‐type operations (12.4–14.6 F cm−1 V−1 s−1), setting new benchmarks for ambipolar OECTs, in terms of n‐type µC* and electron/hole mobilities. Such ambipolar OECTs enable the inverter to achieve a record‐high gain (102 V/V) and associated n‐type and p‐type molecular detectors to offer real‐time and highly sensitive detection of histamine and hydrogen peroxide detection, respectively. These results indicate the effectiveness of judicious molecular design on achieving high‐performance ambipolar OMIECs, allowing the state‐of‐the‐art single‐component ambipolar OECTs for both highly integrated logic circuit and bioelectronic applications. [ABSTRACT FROM AUTHOR]

In recent years, microgrid technology has been widely studied and applied. However, with times developing, the installed capacity of distributed power generation devices has been improved, and work is being carried out in increasingly complex situations, resulting in a decline in the control performance of microgrids. In view of this, to effectively improve inverter’s control performance, research is conducted on the fusion of Narendra model and adaptive control strategies for real-time voltage correction and compensation in complex situations. Compared to traditional inverters, inverters under research methods have faster voltage recovery speed when encountering load switching, and can recover in about one cycle, with good control performance. In the comparison between the improved inverter adaptive control system and the inverter adaptive system, the improved inverter voltage recovery speed is faster, can be restored within one cycle, and the control effect of the inverter is better. The harmonic rate of the port voltage has decreased from 10.43 to 1.92%. The applicability of the research method was verified. It indicats that the research method can improve inverter’s control effect and solve problems such as voltage deviation, three-phase asymmetry, harmonic pollution, etc. that are easily generated by the output terminal voltage. Simultaneously, research has provided theoretical basis and data support for the research of microgrids. [ABSTRACT FROM AUTHOR]

This paper presents simulation analysis of an inverter made from non-aligned double gate field effect transistors (NADGFETs) in Sub-100 nm regime. The inverter consists of n-channel NADGFET and p-channel NADGFET device with a channel length of 40 nm and 50% non-alignment between gate and source/drain. The response of the inverter was tested by a combination of gate dielectric constant (k) and metal work function (ϕ). Three gate dielectrics namely, SiO2 (k = 3.9), Si3N4 (k = 7.2), HfO2 (k = 24), and three metal work function namely tungsten (ϕ = 4.5 eV), molybdenum (ϕ = 4.75 eV), gold (ϕ = 5 eV), were considered in the NADGFET inverter. This paper defines a kϕ index as characterising parameter to explore the best response from inverter configuration with minimum propagation delay, and minimum power consumption at super-high frequency. The paper proposes to analyse the NADGNFET device, in term of ION current, ION/IOFF ratio, cut-off frequency, and gate delay. And observes that low k material with moderate metal work function gives best response. The work then simulates the inverter and group the results into voltage transfer curve (VTC), transient response, and power dissipation category. The result shows that when inverter was subjected to high frequency, all the kϕ combination responds good, however when the inverter was subjected to super-high frequency, the low value of kϕ combination performs well. Thus, the result concludes that SiO2-M2 combination will be best selection to get minimum propagation delay and dynamic power dissipation by the inverter. The test strategy presented in this paper on the basis of kϕ index can serve as benchmark to test inverter device at super-high frequency. [ABSTRACT FROM AUTHOR]

Rotor bar breakage in induction motors is often detected by analysing the signatures in the stator current. However, due to the alteration of the current spectrum, traditional methods may fail when inverter-fed motors operate with closed-loop control using a cascade structure to regulate the speed. In this paper, the potential of zero-sequence voltage analysis to detect this fault is investigated, and a new index to quantify the severity of the fault based on this signal is proposed. Signals from motors operating under different control strategies and signals from motors powered from the mains are considered to verify the robustness of the proposed fault severity index. As a result, in all the analysed conditions the value of the proposed index for the healthy motor is found to be approximately 0.010, while for the faulty machine it is between 0.110 and 0.252. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Hubei Minzu University (Natural Science Edition) is the property of Journal of Hubei Minzu University (Natural Sciences Edition) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The growth of renewables in public energy networks requires suitable strategies to assess the stable operation of the respective power electronic devices, e.g., inverters. Different assessment methods can be performed with regard to the available knowledge and the assessment objective, e.g., a specific frequency range or the input signal characteristics that are typically classified into small-signal and large-signal disturbances. This paper addresses the limits of the measurement-based small-signal stability analysis in the harmonic frequency range of commercially available single-phase inverters for photovoltaic applications. The harmonic stability is analyzed, and the results for a sinusoidal background voltage and distorted background voltages are assessed based on measurements. The measurements prove that even in the harmonic frequency range, the harmonic stability analysis can only provide a sufficient but not a necessary condition in terms of the statement towards an instable operation. [ABSTRACT FROM AUTHOR]

A hybrid approach is proposed for optimizing distribution systems (DSs) by integrating clean energy sources, specifically photovoltaic (PV) and wind power (WT). The proposed technique combines the mud ring algorithm (MRA) and quantum neural network (QNN), referred to as the MRA‐QNN technique. The primary objective is to minimize power loss and enhance voltage stability. The MRA method generates the control signal of the converter, while the QNN method predicts the control signal based on the MRA output. The effectiveness of the approach is revealed through simulations on standard IEEE 33 bus and 69 bus systems. Implementation in MATLAB shows superior performance compared to existing methods, with lower power loss values. There has been a sustained rise in the system voltage profile (In the WT and PV situations, 0.950. and 93 p.u), as well as a considerable reduction in the active power (AP) losses (to 132.39 kW with PV and 81.23 kW with WT from 362.86 kW). With PV, the entire yearly economic loss is lowered from $158932.68 to just $57996.939, and with WT, it is decreased to $56805.479. With three PVs, the yearly economic loss and active power losses are decreased to 30419.871 $ and 69.449, and 4.27 kW and 1875.930 $, respectively. [ABSTRACT FROM AUTHOR]

Abstract This study presents a comprehensive examination of space vector pulse width modulation (SVPWM) and switching frequency optimal PWM (SFOPWM) for an F‐type multilevel inverter (FTMLI). SVPWM offers a simple, digital implementation for three‐phase, three‐level inverter structures, and carrier‐based SFOPWM allows for maximum use of switching frequency with a simple construction. This approach reveals the underlying relationship between the above two PWM techniques with various amplitude and frequency modulation indices to ensure the performance of FTMLI. A suitable comparative study was carried out to verify the PWM techniques based on the inverter output voltage, total harmonic distortion, switching stress, and filter size. The analytical conclusions are supported by the simulation results and their experimental validation.

Abstract In recent years, microgrid technology has been widely studied and applied. However, with times developing, the installed capacity of distributed power generation devices has been improved, and work is being carried out in increasingly complex situations, resulting in a decline in the control performance of microgrids. In view of this, to effectively improve inverter’s control performance, research is conducted on the fusion of Narendra model and adaptive control strategies for real-time voltage correction and compensation in complex situations. Compared to traditional inverters, inverters under research methods have faster voltage recovery speed when encountering load switching, and can recover in about one cycle, with good control performance. In the comparison between the improved inverter adaptive control system and the inverter adaptive system, the improved inverter voltage recovery speed is faster, can be restored within one cycle, and the control effect of the inverter is better. The harmonic rate of the port voltage has decreased from 10.43 to 1.92%. The applicability of the research method was verified. It indicats that the research method can improve inverter’s control effect and solve problems such as voltage deviation, three-phase asymmetry, harmonic pollution, etc. that are easily generated by the output terminal voltage. Simultaneously, research has provided theoretical basis and data support for the research of microgrids.

Summary: The paper designs a novel efficient three‐phase voltage source inverter with performance optimization. When auxiliary circuits connected in parallel with every bridge arm are involved in working process of the designed inverter, main switches will realize zero‐voltage switching in the wide load range, which is beneficial for further decline of the loss of main switches. Furthermore, the optimized duty cycle of the gate drive signal of auxiliary switches is used to restrict circuiting current loss. Besides, when the designed inverter works in a dead zone, the resonance will occur in the auxiliary circuits to cause the output phase voltage to vary from zero or the DC supply voltage to the DC supply voltage or zero as soon as possible, which is beneficial for further decline of the output phase voltage error and the suppression of dead effect. The paper provides relevant analysis on each working status within a switching period along with design requirements. By analyzing test waveforms, it affirms that main switches realize zero‐voltage switching. The efficiency of the designed inverter reaches 98.8% at rating condition. The experiment affirms that the designed inverter has an edge over another two inverters for comparison in performance optimization. [ABSTRACT FROM AUTHOR]

Summary: The paper designs an efficient three‐phase soft‐switching inverter with asymmetric auxiliary circuits, which is beneficial for further miniaturization and efficiency optimization. Only two auxiliary switches, one resonant inductor, and three resonant capacitors make up simple asymmetric auxiliary circuits of each phase, contributing to the reduction of power loss and hardware cost. As soon as the simple auxiliary circuits get involved in the operation of the designed inverter, main switches can realize zero‐voltage switching within the entire load range. The reduction of power loss of auxiliary circuits and main switches is conducive to further efficiency optimization. The paper expounds every operating status during one switching period. The relevant experimental waveforms make known that switching devices can realize soft‐switching. The efficiency reaches 99% at rated operation status of the designed inverter, confirming that the designed inverter has superiority over comparison objects in the experiment with regard to the efficiency. Thus, the structural simplification of auxiliary circuits is an effective method for further miniaturization and efficiency optimization. [ABSTRACT FROM AUTHOR]

The flux observer method is widely utilized as a sensorless control technique in which the stator or rotor flux of IPMSM can be measured with a closed-loop observer or an integrator. However, DC-offset (DCoff), the ramp signal, and harmonics are consistently present in the acquired rotor flux because of an unidentified starting value, errors in the integral computation's current detection, and the inverter's nonlinearity. The aforementioned interference signals will drastically reduce the sensorless control efficacy. This work introduces an enhanced flux estimator with a negative feedback loop and PI controller to overcome the DC drift problem resulting from a pure integrator and a low-pass filter. Moreover, an optimal design approach of flux estimator structures with a broad range of speeds for Interior permanent magnet synchronous motor (IPMSM) drives is proposed, which utilizes an integrated topology of the voltage and current models incorporating a DC-offset PI-correction loop, actual and estimated flux magnitude's correction error. The flux vector's initial inaccuracy is eliminated, together with the DCoff and drift in the acquisition channel. A phase-locked-loop state estimator is utilized to derive the speed and position from the actual and estimated flux. The effectiveness and superiority of the suggested approach were proven by simulation and experimental findings for the IPMSM drives, which displayed high dynamic performances over varying scenarios. This reliable approach, including sensorless control, is suitable for all AC motors with sinusoidal flux distributions over a wide speed range. [ABSTRACT FROM AUTHOR]

The growth of renewables in public energy networks requires suitable strategies to assess the stable operation of the respective power electronic devices, e.g., inverters. Different assessment methods can be performed with regard to the available knowledge and the assessment objective, e.g., a specific frequency range or the input signal characteristics that are typically classified into small-signal and large-signal disturbances. This paper addresses the limits of the measurement-based small-signal stability analysis in the harmonic frequency range of commercially available single-phase inverters for photovoltaic applications. The harmonic stability is analyzed, and the results for a sinusoidal background voltage and distorted background voltages are assessed based on measurements. The measurements prove that even in the harmonic frequency range, the harmonic stability analysis can only provide a sufficient but not a necessary condition in terms of the statement towards an instable operation.

Numerous reviews are available in the literature on PV inverter topologies. These reviews have intensively investigated the available PV inverter topologies from their modulation techniques, control strategies, cost, and performance aspects. However, their compliance with industrial standards has not been investigated in detail so far in the literature. There are various standards such as North American standards (UL1741, IEEE1547, and CSA 22.2) and Australian and European safety standards and grid codes, which include IEC 62109 and VDE. These standards provide detailed guidelines and expectations to be fulfilled by a PV inverter topology. Adherence to these standards is essential and crucial for the successful operation of PV inverters, be it a standalone or grid-tied mode of operation. This paper investigates different PV inverter topologies from the aspect of their adherence to different standards. Both standalone and grid-tied mode of operation-linked conditions have been checked for different topologies. This investigation will help power engineers in selecting suitable PV inverter topology for their specific applications. [ABSTRACT FROM AUTHOR]

In the inverter circuit, the speed at which the MOSFET is impacted by the presence of a parasitic inductor within the printed circuit board (PCB) leads to a delay in the switching process. Furthermore, the parasitic inductor within the circuit can easily form an LC oscillation with the parasitic capacitor of the MOSFET. These two issues result in an inconsistency between the actual output of the MOSFET and the driving signal waveform, leading to distortion in the sinusoidal pulse width modulation (SPWM) waveform and an increase in total harmonic distortion (THD). It is a common practice to mitigate gate oscillation by introducing a resistor at the gate of the MOSFET. However, elevating the resistance leads to deceleration in the charging process of the MOSFET's parasitic capacitor, consequently causing an increase in the switching delay, and thereby increasing THD. Therefore, an effective strategy to reduce THD is proposed in this paper, while augmenting the gate resistance, computing the MOSFET switching delay, and applying corrective compensation. In this way, the inherent issues of the switch are addressed, resulting in inverter output waveforms that closely resemble sine waves and reduced THD. Through a combination of simulation and empirical experimentation, the efficacy of the proposed approach in significantly reducing THD in the inverter's output waveform has been empirically substantiated. [ABSTRACT FROM AUTHOR]

Recently, fault diagnosing supervised classifiers have been widely proposed to diagnose both electric and mechanical faults in induction motors (IM). However, many of them require a large amount of data, which implies a great effort required for processing fault-related features and building the training set. Furthermore, in real-world datasets, it is required to deal with highly skewed data distributions, also known as class imbalance, which is a limiting issue and can misguide the tuning of machine learning algorithms. Resampling techniques based on a synthetic generation of minority class observations aim to address this problem. Last but not least is the fact that inverter-fed IM introduces undesired harmonics in the monitoring signal altering the diagnosis patterns. This diagnosis scheme is evaluated on experimental imbalanced data oriented to deal with the diagnosis of a rotor in situations where it is fed with an inverter. The results show how this imbalanced approach determines the actual diagnosis performance on a small amount of data. The experimental results demonstrate that balanced training sets built with class balancing techniques improve the classifier and therefore its performance for diagnosing incipient rotor faults in inverter-fed IM with studied and interpretable features recently proposed in this field of study. [ABSTRACT FROM AUTHOR]

Aiming at the rich bifurcation and chaotic characteristics in the inverter with proportion integral derivative (PID) controller, the discrete iterative model of such an inverter was derived based on the stroboscopic mapping theory; the nonlinear evolution and the cause of instability in this inverter are analyzed. It was observed that the low‐frequency oscillation following instability was due to the Hopf bifurcation, which will decrease the power supplied quality by the inverter. To address the potential issue of the system instability caused by nonlinear behaviors, an improved exponential time‐delay feedback control scheme was proposed. The controlled object's output current first subtracted its own delay a period of time to form a difference term, which was subsequently fed into an exponential link to make difference with the constant 1. The resulting value was then fed into a proportional link to obtain the control term, which was applied to the PID controlled inverter in a feedback manner. Moreover, the range of the feedback proportional coefficient was solved via the Jury criterion. Finally, the effectiveness of this scheme was verified through the comparative simulations, demonstrating that this scheme can not only increase the stability domain for each parameter by more than 50% in the PID controlled inverter but also stabilize the quasi‐periodic behavior due to the low scale oscillation caused by the Hopf bifurcation at the switching frequency. [ABSTRACT FROM AUTHOR]

The current inverter control strategies have limitations in suppressing grid resonance, especially in complex grid environments with high penetration of renewable energy sources. These strate-gies often focus on suppressing resonance at a single frequency point, but their effectiveness is constrained when dealing with multi-band resonance or dynamically changing grid conditions. The study investigates the application of parallel-operated inverters in the grid, particularly their impact on grid stability. A novel active damping strategy is developed to enhance the grid's dynamic response and suppress grid resonance. The effectiveness of the control strategy is verified through simulation by establishing Norton equivalent circuit models for multiple in-verters. Fast Through simulation, this study comprehensively evaluates the performance and adaptability of the strategy under various conditions. Results demonstrate that implementing the active damping strategy increases the inverter output power from 9.5 kW to 10 kW, an im-provement of 5.26%. System response time is reduced from 50 ms to 30 ms, and post-stabilization fluctuations decrease to 1.5%. These data conclusively prove the effectiveness of the control strategy in enhancing grid stability and reducing resonance effects. The findings underscore the potential of active damping strategies in improving grid performance and in-verter efficiency. However, further research and optimization are necessary to assess the adapt-ability of these strategies under different grid conditions. [ABSTRACT FROM AUTHOR]

Model predictive control (MPC) performance depends on the accuracy of the system model. Moreover, the optimization algorithm of MPC requires numerous online computations. These inherent limitations of MPC hinder its application in power electronics systems. This paper proposes a two-part solution for these challenges for a three-phase inverter with an output LC filter. The first part of the control scheme is a linear and modified model-free approach based on the auto-regressive structure (ARX) with exogenous input. The second part is the computationally efficient optimization algorithm based on the active set method to solve the optimization problem of the MFPC. The objective of the control scheme is to regulate the output voltages of the inverter in the presence of constraints. The constraints are the maximum admissible filter current and optimal duty cycle to avoid any damage to the system. To validate the performance of the proposed control scheme, simulations and hardware-in-loop (HIL) real-time investigations have been performed, comparing the results of the proposed approach with the model-based predictive control. The results showcase the computational efficiency and effectiveness of the MFPC approach, demonstrating its potential for overcoming the limitations of traditional MPC in power electronics systems. [ABSTRACT FROM AUTHOR]

In recent years, small-scale microgrids have become popular in the power system industry because they provide an efficient electrical power generation platform to guarantee autonomy and independence from the power grid, which is a critical feature in cases of catastrophic events or remote areas. On the other hand, due to the short distances among multiple distribution generation systems in small-scale microgrids, the interconnection couplings among them increase significantly, which jeopardizes the stability of the entire system. Therefore, this work proposes a novel method to design decentralized robust controllers based on a retrofit model predictive control scheme to tackle the issue of instability due to the short distances among generation systems. In this approach, the retrofit model predictive controller receives the measured feedback signal from the interconnection current and generates a control command signal to limit the interconnection current to prevent instability. To design a retrofit controller, only the model of a robust closed-loop system, as well as an interconnection line, is required. The model predictive control signal is added in parallel to the control signal from the existing robust voltage source inverter controller. Simulation results demonstrate the superior performance of the proposed technique as compared with the virtual impedance and retrofit linear quadratic regulator techniques (benchmarks) with respect to peak-load demand, plug-and-play capability, nonlinear load, and inverter efficiency. [ABSTRACT FROM AUTHOR]

This study introduces a novel uninterruptible power supply (UPS) configuration that integrates active power filter (APF) capabilities within a single-phase matrix converter (SPMC) framework. Power disruptions, particularly affecting critical loads, can lead to substantial economic damages. Historically, conventional UPS systems utilized dual separate converters to function as a rectifier and an inverter, without incorporating any power factor correction (PFC) mechanisms. Such configurations suffered from diminished power density, compromised reliability, and spatial limitations. To address these issues, this research proposes an enhanced UPS design that incorporates APF features into the SPMC. The focus of this investigation is on the efficiency of alternating current (AC) to direct current (DC) conversion and the reverse process utilizing this advanced UPS model. The SPMC is selected to supplant the rectifier and inverter units traditionally employed in UPS architectures. A novel integrated switching strategy is formulated to facilitate the operation of the UPS in either rectifier (charging) or inverter (discharging) modes, contingent upon the operational state. The performance and efficacy of the devised circuit design and switching technique are substantiated through simulations conducted in MATLAB/Simulink 2019 and empirical evaluations using a test rig. The findings demonstrate that the voltage generated is sinusoidal and synchronized with the supply current, thereby minimizing the total harmonic distortion (THD) and enhancing both the power factor and the transition efficiency of the UPS system between its charging and discharging states. [ABSTRACT FROM AUTHOR]

This paper introduces the concept of a intelligent energy storage system (IESS) due to the limitations of heterogeneous energy storage systems in providing reliable, long-term power to dynamic loads. Dynamic loads, such as induction or DC motors, draw large currents during start-up, leading to accelerated aging of battery storage systems. By integrating an ultra capacitor with battery blocks, the sudden energy demands of these loads can be met, preventing excessive strain on the batteries. The study proposes an experimental approach to explore the advantages of a IESS that combines an ultra capacitor with a battery, storing energy generated from a stand-alone photovoltaic (PV) system. The performance of this hybrid system is tested under three different load conditions, and the results are verified. A prototype setup, including a PV module, converter, control unit, and load, is developed to compare the input and output voltage and current of the inverter, both with and without ultra capacitor batteries. Results show that, battery performance is optimized and the noted reduction in the drain rate is approximatly 22% with the use of the ultracapacitor. Increasing the ultra capacitor's capacity could further reduce battery drain significantly. [ABSTRACT FROM AUTHOR]

Inverters are important interfaces between micropower sources and consuming loads. However, the varying inductors and capacitors, modeling errors, measurement errors, and external disturbances would lead to degradation of the inverters' performances when conventional linear control is adopted, causing instability problems. To address it, a disturbance-rejection passivity-based nonlinear control strategy is proposed for the inverters of micropower sources. The proposed method innovatively introduces an extended high-gain state observer into the passivity-based controller to achieve online observation and elimination of complex influencing factors such as external disturbances, time-varying parameter uncertainties, and modeling errors, thus ensuring the global stability of the inverter under various disturbances. The design details on the passivity-based controller and the extended high-gain state observer are elaborated. The effectiveness and feasibility of the proposed control strategy are verified by the experiments performed by a 15 kVA inverter designed in the lab. The results show that the proposed control is able to ensure the inverter's stable operation under the following conditions: constant power load, the filter inductance and capacitance reduce up to 33% and 96%, and the input voltage varies more than 22%. [ABSTRACT FROM AUTHOR]

The paper carries out the research on a novel two‐level voltage source inverter to further improve the output power quality of the inverter under the premise of efficient operation. Main switches can realize zero‐voltage switching in a wide load range to ensure the efficient operation of the designed inverter. Total harmonic distortion (THD) of the output current at low output frequencies can be improved by the modification of resonant tanks in the designed inverter. In the dead time, the modified resonant tanks can result in a shorter duration of nonlinear changes in the output phase voltage at lower load current, which is beneficial for reducing the output voltage error caused by dead time. The improved power quality at low output frequencies is conductive to the use of the designed inverter in the drive system of the low‐speed AC motor. The paper expounds every operating status during a switching period. The experiment manifests that switches realize soft switching. The efficiency of the designed inverter reaches 98.6% at rated operation state, which is 0.3% and 0.5% more than that of two comparison objects, respectively. Moreover, when the output frequency reduces to 5 Hz, the THD of the output current is only 2%, which is also less than that of comparison objects. Hence, the designed inverter has advantages in the efficiency and the output power quality. [ABSTRACT FROM AUTHOR]

In wind energy systems, increasing system efficiency by maximizing the usage of wind speed has become an important issue. In this study, a single-phase grid-connected Maximum Power Point Tracking (MPPT) system that does not use a speed sensor or any motor control algorithm under variable wind speeds is proposed. In the proposed system, a Permanent Magnet Synchronous Generator (PMSG) is chosen as the generator, and a diode rectifier circuit is used at its output. To achieve the necessary DC bus voltage for grid connection at variable speeds, a DC-DC boost converter is included. The system is simplified by not using any motor control techniques and by employing PI and PR controllers for regulation. Additionally, the use of a diode rectifier instead of a controlled rectifier at the PMSG output reduces the system's cost and size. The proposed MPPT system, with a nominal power of 2kW and a bus voltage of 400V, was tested in simulation studies. The results demonstrated the system's performance and accuracy. [ABSTRACT FROM AUTHOR]

This paper proposes a hybrid COA‐QNN approach for an interleaved KY converter with closed‐loop control for a single‐phase grid‐connected photovoltaic (PV) system. The proposed strategy combines both Cheetah Optimizer algorithm (COA) and Quantum Neural Network (QNN), and it is commonly named the COA‐QNN technique. The interleaved KY converter is connected in the converter side. The primary goal of the COA‐QNN technique is to enhance PQ while maximizing PV electricity being transferred to the grid. The proposed COA is utilized to identify the optimal closed‐loop controller enhancements for on‐grid solar photovoltaic systems. The QNN is used to predict the optimal control parameter. The PV‐interleaved KY converter is managed by a predictive control mechanism to carry out both tasks of PQ enhancement. By then the COA‐QNN technique is implemented on the MATLAB platform and compared with existing methods. Finally, the proposed method shows better results in all methods, such as GWO, FF optimization and combined GWO‐FF. [ABSTRACT FROM AUTHOR]

Electrification of vehicles intensifies their cooling demands due to the requirements of maintaining electronics/electrical systems below their maximum temperature threshold. In this paper, passive cooling approaches based on heat pipes have been considered for the thermal management of electric vehicle (EV) traction systems including battery, inverter, and motor. For the battery, a heat pipe base plate is used to provide high heat removal (180 W per module) and better thermal uniformity (<5°C) for the battery modules in a pack while downsizing the liquid cold plate system. In the case of Inverter, two phase cooling system based on heat pipes was designed to handle hot spots arising from high heat flux (~100 W/cm)–for liquid cooling and provide location independence and a dedicated cooling approach-for air cooling. For EV motors, heat pipe-based systems are explored for stator and rotor cooling. The paper also provides a glimpse of development on high-performance microchannel-based cold plate technologies based on parallel fins and multi-layer 3D stacked structures. Specifically, this work extends the concept of hybridization of two-phase technology based on heat pipes with single-phase technology, predominately based on liquid cooling, to extend performance, functionalities, and operational regime of cooling solutions for components of EV drive trains. In summary, heat pipes will help to improve and extend the overall reliability, performance, and safety of air and liquid cooling systems in electric vehicles. Graphic Abstract [ABSTRACT FROM AUTHOR]

This paper presents an inverter-based active feedback transimpedance amplifier (IAF-TIA), in which an active feedback is applied to a voltage-mode inverter-based TIA, and therefore, the controlled positive regeneration process enables the proposed IAF-TIA to achieve the limiting operations for input currents greater than 100 μApp. However, the active inverter feedback mechanism might be prone to instability, hence mandating a very careful optimization of the loop gain. For this purpose, a diode-connected NMOS transistor is employed as a switch in the feedback path with its gate connected to the input, which helps not only to mitigate the corresponding issue but also to accommodate large input currents up to 1.5 mApp. The proposed IAF-TIA implemented in a standard 180 nm CMOS process demonstrates a 70.5 dBΩ transimpedance gain, 1.21 GHz bandwidth, 4.3   pA / Hz noise current spectral density, 63.5 dB input dynamic range, and 23.6 mW power dissipation from a single 1.8 V supply. The chip core occupies an area of 180 × 50 μm2, including an on-chip P+/N-well/Deep N-well avalanche photodiode as an optical detector. [ABSTRACT FROM AUTHOR]

In this paper, a simple carbon nanotube field effect transistor (CNTFET)-based inverter has been simulated and the impacts of changing various design and process parameters on its characteristics and performance have been analysed using HSPICE. The 32 nm CNTFET model of Stanford University has been used here for the simulation of the inverter. The simulation results and the voltage transfer characteristics (VTC) curve of the inverter have been extracted for (i) different channel lengths, (ii) top gate di-electric material thickness (tox), (iii) pitch value (iv) the number of tubes in CNTFET channel region and (v) chirality of the CNT. It has been observed that the VTC curve changes significantly with different values of these parameters. Some important output parameters like maximum dc current, power, rise time, fall time, average propagation delay, etc. have been measured in each case. Changes in maximum power consumption value due to the change in different parameter values are observed through plotted graphs. Output dc current vs. input voltage graphs have been plotted for different chirality of the tubes, the number of the tubes, and pitch values between n-type CNTFET and p-type CNTFET of the inverter. [ABSTRACT FROM AUTHOR]

In view of the problems of large volume, high cost and complex structure of the existing multilevel inverter topology, a 13 level inverter based on switched capacitor is proposed. The proposed topology is composed of a DC input power supply, 3 capacitors and 14 switching devices, which realizes a 13 level output with 6 times boost. The proposed topology has lower cost and smaller volume, reduces the harmonic content of the system output, and realizes the inverter without H - bridge to reduce the voltage stress of the switch tube. The proposed inverter can achieve capacitor voltage self - balancing without any auxiliary method, which simplifies the complexity of control. The superiority of the proposed topology is verified by comparison with other traditional multilevel inverters. Simulation and experimental results verification on the simulation and prototype platform prove that the inverter has good performance in both steady and dynamic conditions. [ABSTRACT FROM AUTHOR]

Health status detection for motor drive systems includes detecting the working status of the motor and diagnosing open-circuit (OC) faults in the inverter. This paper proposes a generalized-layer-added principle component analysis (GPCA) to determine the load-up/load-shedding status of a motor and diagnose faults in its inverter. Most current methods for detecting OC faults are constrained by changes in the current amplitude and frequency, potentially leading to misjudgments during load-up/load-shedding transient states. The proposed method addresses this issue. Initially, this paper employs a homogenization method to process current data, eliminating the impact of transient processes during motor load-up/load-shedding states on inverter fault diagnosis. Subsequently, the fast Fourier transform (FFT) is used to extract the frequency domain characteristics of the data. If the PCA method is trained with a singular matrix, this can lead to an unreliable result. This paper introduces a generalization layer based on the PCA method, leading to the GPCA method, which enables training with singular matrices. The GPCA method is then developed to compute data features. By presetting thresholds and utilizing the prediction error value and contribution rate index of the GPCA method, the relevant state of the motor drive system can be determined. Finally, through simulations and experiments, it has been demonstrated that the method, using data from the stable working state, can effectively detect the working status of a motor and diagnose OC faults in its inverter, with a diagnostic time of 0.05 current cycles. [ABSTRACT FROM AUTHOR]

The variable DC link direct torque control (DTC) for induction motors was proposed in this paper utilizing an artificial neural network (ANN). Variable DC-link voltage is utilized as the inverter's controlling input to improve the induction motor's performance. By injecting the dynamically variable dc-link voltage, inverter switching losses are decreased and inverter efficiency is increased. Two significant limitations are the torque ripple in DTC and the speed regulation of induction motors at low speeds. The driveline of an electric vehicle is modeled, and the suggested control is put into practice to enhance low-speed speed regulation, high dynamic performance, and minimal torque ripple. With variable DC-link voltage based on ANN, an improvement in torque and speed is made possible. Additionally, the suggested strategy minimizes the current ripples. To verify the improved efficacy of the electric driveline under various operating scenarios, a proposed control of the electric driveline is implemented using MATLAB SIMULINK, and the results are compared with the conventional scheme. The recommended speeds for the three speed ranges are as follows: 300 rpm for low speed, 900 rpm for medium speed, and 1275 rpm for high speed. The torque ripples decreased from 0.39 to 0.24 in the low-speed region, 0.38 to 0.24 in the medium-speed region, and 0.36 to 0.24 in the high-speed region while the motor was operated at a constant load torque of 2 N-m. The torque ripples decreased from 0.4 to 0.274 in the low speed region, 0.4 to 0.274 in the medium speed zone, and 0.2 to 0.274 in the medium speed region when the motor operated at various speed regions with a constant load. The main effect of running the motor at different load torques, such as 1.5 N-m, 2.5 N-m, and 2.0 N-m, is shown in Table 9 and numerical data of torque ripples is presented in Table 9. [ABSTRACT FROM AUTHOR]

One way to increase the power of Brushless Direct Current (BLDC) motors is to switch to ferrite stator cores and increase the Pulse Width Modulation (PWM) frequency of Electronic Speed Controllers (ESC). This is particularly important in UAVs, where the weight of BLDC motors and their specific power are critical. The main problem when operating at high PWM frequency is that all parallel-connected MOSFETs should turn on quickly and in perfect synchronism. Nonsynchronization of transistors leads to thermal or electrical breakdown. The paper proposes new circuit solutions that ensure synchronous operation of high-power MOSFET transistors in the output stages and allow increasing the PWM frequency of Electronic Speed Control controllers (ESC) to 150-200 kHz. The use of ferrite cores in stators will significantly increase the power of BLDC motors while maintaining the same dimensions. Increasing the PWM operating frequency also allows multi-pole BLDC and PMSM motors to operate at higher speeds. The paper reveals a comprehensive methodology for constructing high-frequency ESC controllers for UAVs when switching to ferrite stator cores of BLDC motors. A special contribution is the description of the protective cascade circuits and the Battery Elimination Circuit (BEC) for powering the microprocessor part from a high-voltage current source. [ABSTRACT FROM AUTHOR]

This paper deals with the phenomenon of torsion oscillations in railway vehicle drive systems. The main goal is to reduce the risk of presence of torsional oscillations in wheelset drive, eventually to propose systems to effectively identify and eliminate torsional oscillations of wheelsets. Therefore, a simulation wheelset drive model including a detailed model of the asynchronous traction motor control was built. The results of computer simulations show that the torsional oscillations can be effectively eliminated by avoiding the resonance states between the excitation frequencies given by pulse width modulation of the inverter and the eigenfrequencies of the mechanical part of the drive. Furthermore, it was found that the presence of torsional oscillations of the wheels can be detected based on the traction motor current ripple. The wheelset drive model was subsequently implemented in a simulation model of a four-axle locomotive. A new algorithm of an anti-slip protection system that utilizes motor currents was implemented in the model. Simulations show that such an anti-slip protection system can prevent the occurrence of undesired large amplitude of wheelset torsional oscillations. The models and simulation results are presented in detail in the paper. [ABSTRACT FROM AUTHOR]