Search

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.

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.

Currently, the commissioning of power plants based on renewable energy sources (RES) using inverters is becoming widespread. However, these power plants do not participate in maintaining the stability of the power system during emergency disturbances, since they are switched off by technological protections when a disturbance occurs. In the future, when power plants based on renewable energy sources become widespread, ensuring the possibility of their participation in maintaining sustainability will significantly increase the reliability of the energy system. A preliminary assessment of the effectiveness of participation in maintaining sustainability should be carried out through computer modeling.THE PURPOSE: To realize the possibility of participation of RES-based power plants in ensuring reliable and sustainable operation of the power system, as well as to realize the possibility of performing a preliminary assessment of the effectiveness of the proposed method.METHODS. In this paper, the application of virtual synchronous generator technology is proposed to realize the possibility of participation of RES-based power plants in ensuring the reliability and sustainability of the power system. Also, a method of modeling the virtual synchronous generator in Matlab software package is proposed.RESULTS. The technology of virtual synchronous generator is proposed, which with the use of inverter, electric energy storage and appropriate control system can provide the increase of dynamic stability of power system. A method of modeling the virtual synchronous generator in Matlab software package is proposed. The results obtained allow us to conclude that the constructed model of a virtual synchronous generator is efficient, maintains the stability of the system and ensures correct control of the inverter, as a result of which the parameters of the electrical network are maintained within acceptable limits. The resulting computer model can be used in further research.CONCLUSION. The technology of virtual synchronous generator allows to imitate in the inverter the inertial and damping characteristics of the traditional synchronous generator, and the proposed computer model will help to evaluate the effectiveness of this technology when implemented in the power system.

In the current distribution network’s energy structure, photovoltaic (PV) occupies a high proportion. However, the access of a high proportion of PV will lead to the phenomenon of reverse power flow in the distribution network, and then the problem of line overvoltage. When the reverse power flow increases, the problem of line overvoltage also worsens, which endangers the normal operation of power system. To solve this problem, this paper starts with the voltage rise theory of distribution network lines. Firstly, through strict mathematical derivation, it compares the influence of main network line parameters and distribution network line parameters on the voltage rise, and summarizes a simple calculation equation for the voltage rise of the distribution network with high proportion PV. Then, according to the mechanism of voltage rise and the principle of inverter control, considering the economy and practicability of the overvoltage suppression strategy, a reverse power flow overvoltage suppression strategy of a system with high proportion PV is proposed. Finally, a PV system model simulating a small village is used to verify the effectiveness of the proposed overvoltage suppression strategy.

In stand-alone photovoltaic (PV) systems, the main goal is to control the current that the inverter feeds to the load. In this paper, the performance of predictive current control (MPCC) is tested and evaluated for a stand-alone photovoltaic (PV) system. Our evaluation spans various current amplitudes and frequencies, aiming to demonstrate its robust performance and practical applicability. The MPCC method employs a discrete-time model of the system, enabling the prediction of future values of the load current for all potential volt-age vectors generated by the inverter. Implementing the MPCC strategy on RL (resistor-inductor) load alimented by a PV inverter offers the advantage of simplified implementation and significantly reduced computing time. Simulation and experimental results are presented to prove the efficiency and practical applicability of the proposed control. Both results conclusively demonstrate the high efficacy of MPCC in managing a stand-alone photovoltaic (PV) inverter across various current amplitudes and frequencies, ensuring reliable and robust performance

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 To improve the reliability of Two-level three phase voltage source inverters, a uniform fault tolerant strategy based on space vector pulse width modulation is proposed for different leg faults. The reconstructed topologies of inverters with different bridge arm faults are different, which makes the basic voltage vector phase of each reconstructed topology inconsistent, resulting in different calculations. Therefore, the coordinate transformation is applied to place the basic voltage vectors of each reconstructed topology on the synchronous stationary αβ coordinate system so that the calculations of the reconstructed topology under different bridge arm faults are unified, thus reducing the complexity of fault-tolerant control. Aiming at the three-phase current asymmetry caused by the neutral point voltage oscillation in inverter topology reconstruction, a transient compensation method of neutral point voltage offset for the α-axis component of the reference voltage vector is introduced to suppress the adverse effects. The compensation method directly offers a neutral point voltage offset value after Clarke transformation and corrects the α-axis component of the reference voltage vector, avoiding the integral calculation in the conventional voltage compensation algorithm. The correctness and effectiveness of the proposed fault-tolerant control strategy are verified experimentally.

With the continuously challenges of energy and environmental, the development of distributed power generation technologies focused on renewable energy is rapidly advancing. Microgrid based on inverter power source is the important form of distributed generation, but it is difficult to isolate faults selectively and accurately when short circuit fault occurs in grid, and will result in overall shutdown. Aimed at the characteristics of inverter power sources and microgrid structures, a protection method based on equivalent distance for lines of source-grid-storage microgrid is proposed. Realtime information of the fault line is modulated into the terminal frequency by modulation techniques. Subsequently, virtual short-circuit currents are obtained via demodulation techniques, and fault distances are measured through equivalent internal potential. It is verified by theoretical analysis and simulation experiments in four tipical cases, such as single power source circuits, and this method can effectively calculate virtual short-circuit currents. These currents are equevlant to the virtual currents output when traditional rotating motors act as power sources. The proposed method can use the aforementioned virtual short-circuit current to determine the distance between the inverter power source and the fault point.

Leveraging two types of enhanced delay stages to form an oscillation loop, results in a highly reliable CMOS ring oscillator versus external interventions. The idea is investigated via symbolic delay calculations and the HSPICE circuit simulator while 0.18 μm CMOS is exploited. Based on two described inverters, three-ring oscillators are presented. The two ones use only one type of delay stage while the third is combined using two basic inverters and a single current-starved inverter. The basic type inverter is the fastest while is sensitive to power supply and temperature variations. On the other hand, the sensitivity of the current starved inverter is acceptable but this delay stage shows a large delay time, reducing oscillation frequency. This work tries to address this tradeoff between speed and sensitivity by proposing an oscillation loop. The delay times analysis and simulation results verify the robust performance of the proposed oscillator.

As time progresses, electric motors are used for industrial or commercial purposes. The need for a motor that is robust, simple, and easy to maintain has been answered by creating an induction motor that can handle the purpose. At the beginning of its use, induction motors were more often used at constant speeds. Using an inverter becomes one of the solutions at hand to control the induction motor. Nowadays, most inverters are controlled by the SPWM (Sinusoidal Pulse Width Modulation) method. This method can adjust the output voltage and frequency by setting the carrier signal's frequency value and the reference signal's amplitude. A driver circuit is needed to implement an SPWM-based inverter. This driver circuit is needed to isolate the power circuit from the controller. Moreover, this circuit is also used to increase the microcontroller output signal to trigger the IGBT gate switch. The IR2132 and TLP250 drivers are often used in three-phase inverter applications. These drivers have advantages and disadvantages. This paper discusses the capabilities of these two drivers when applied to a three-phase inverter that functions as an induction motor drive. This inverter-controlled induction motor is advantageous because it can be rotated at a nominal speed and frequency.

The research article endeavors to explore the efficient multi-quadrant operations in Electric Vehicles (EV), which emphasizing among the renewable sources and Energy Storage Management Systems (ESMS). This coordination is facilitated through the latest advancements in converter circuits, aiming to enhance efficiency and performance in EV operations. The primary converting circuit, or inverter, is crucial in optimizing the utilization of energy sourced from renewable sources. The coordination among these systems along with the converter, produces harmonics, due to the shifting of operating modes in EV motors in quick sessions because of dynamic real-time road conditions. This research paper presents the design and implementation of Self Balancing Modulated Five-Level Inverter along with a powerful modulation technique and coordinated with the ESMS of electric car application. The proposed 5-Level inverter shows the reduction in torque distortions in an electric vehicle drives over conventional two-stage boost inverter (2SBI) circuits. The designed Five-Level Inverter (FLI) circuit characterized by reduced switching operations, shows a significant reduction in voltage stress gradients on switches and achieves self-balancing of voltages with reduced operating components. The developed three-phase boost single circuit named as SBAM-FLI is connected to the grid integrated renewable energy application and the system is tested at constant and variable torque conditions. A comparative analysis is conducted between the operation of self-balancing modulated FLI with 2SBI based on the obtained results and power loss analysis is performed for the performance evolution in EV applications. The proposed topology is adaptable to both the Trapezoidal and Sinusoidal Back EMF drive mechanisms, which shows significant improvement over conventional inverters. The experimental validation of proposed self-balancing modulated FLI design is presented in this research. The experimental setup was realized using Xilinx block sets and seamlessly integrated with the Basys-3 Artix-FPGA board, consequently, both the experimental and simulation outcomes of the proposed converter topology were validated and provides substantial impact on EV applications.

Grid operations are evolving as a result of the extension of existing huge scope inverter-based power stations and sun oriented (PV) power plants. In light of these alterations, the grid code has been updated to mandate the use of inverter based. In the event of grid failure, power plants should remain online and offer dynamic backup. The term “momentary cessation of operation” is commonly used to describe this characteristic. Very little is known about how PV power plants' temporary shutdowns contribute to the larger issue of unstable power supplies, and very few studies have been published on the topic. While trying to settle this issue, this study offers an ANFIS regulator engineering for PV inverters to work on that ephemeral solidness about coordinated dynamo associated through this network. This examination shows how each direct electric current connect condensers on that solar cell inverter might be utilized to assimilate a piece of the dynamic energy put away in the coordinated machine during the brief delays by utilizing the ANFIS regulator framework introduced. Besides, the recommended approach further develops voltage solidness by infusing responsive power. The viability of the recommended control system is affirmed by the introduced exploratory and reproduced discoveries.

Variation in switching frequency with operating speed and high torque ripples are two important limitations of the Direct Torque Control or DTC technique. The potentiality of the switching device cannot be fully exploited for variable switching frequency (in the case of lowest frequency) whereas high torque ripples lead to vibrations and acoustic noise in the motor. A five-phase induction motor (FPIM) based on DTC technique is presented here to overcome these drawbacks. A five-level Proportional-Integral (PI) based torque controller using waveform comparison is employed in the drive. The PI controller will process the torque error whose output is then compared simultaneously with four constant frequency triangular waves to achieve constant switching frequency. The gains of PI controller are designed using linear control theory for minimum torque ripples. Stator current distortion due to the presence of auxiliary subspace in the five-phase system is also minimized. The demagnetization of stator flux during low-speed operation is mitigated through the selection of voltage vectors that are present thirty-six degrees within the sector boundaries. Experimental results have been presented for validating the steady state and dynamic performance of proposed DTC technique.

Synchronization of single-phase inverters is a challenging task due to the difficulty of deriving a rotating voltage frame, in the absence of adequate information from the other two phases. Moreover, modern standards, such as the fault ride-through (FRT) directives, require inverter-based distributed generators (IBDGs) to respond as fast as possible to grid disturbances; thus, it is necessary to rely on accurate and fast synchronization algorithms. The scope of this paper is to propose a new synchronization technique, which satisfies three important requirements: a) fast dynamic response, b) adequate double frequency rejection, c) low computational complexity. Our synchronization technique is a flexible method relying on variable-length transfer delay, which calculates network frequency by analyzing voltage angle differentials. To enhance this differentiation process and address potential discontinuities, we introduce Heaviside-based functions. Both simulations conducted in MATLAB/Simulink and experimental trials demonstrate that our proposed synchronization method outperforms the most widely adopted existing techniques in terms of dynamic response and computational efficiency. Due to its excellent dynamic performance, the proposed method can offer a stable FRT capability, with fast detection of the voltage dips and seamless resynchronization following fault clearance, all while preventing DC-link overvoltage issues.

Conventional pre-synchronization control strategies for grid-connected virtual synchronous generator typically involve phase-locked loops, coordinate transformations or other non-linear computations, which may lead to substantial hardware resource consumption, pre-synchronization failures, even potential system instability. Hence, the mathematical relationships between voltage differences and angle differences on both sides before grid-connecting are analyzed. Based on those relationships, a pre-synchronization control strategy is proposed. It achieves smooth grid connection only by simple linear calculations using the filter capacitor voltage and the grid voltage. The difference between the effective values of these two voltage components is processed through a PI controller, with the result serving as a correction value for the output voltage command of the reactive power loop. The instantaneous value difference of the corresponding phase voltages is summed in absolute terms and processed through another PI controller, with the resulting output serving as a correction value for the frequency command of the active power loop. The cutoff frequencies of the two PI controllers are staggered to achieve decoupling. Control parameters are designed through stability analysis. Finally, experimental results validate the effectiveness of the proposed control strategy.

In a multitude of industrial and biomedical applications, the need for arbitrary waveform generators is essential, serving the purpose of load characterization and excitation, among others. Historically, these generators have had limitations in terms of voltage, current, and frequency output, primarily related with constraints associated with the power devices and circuit topologies. However, notable advancements in semiconductor technology have introduced a new era, enabling the creation of highly versatile waveform generators capable of superior performance, and extended operational capabilities. In this article, a versatile AWG based on switched modules is proposed. In contrast to the previous ones, whose implementation was based on linear amplifiers, it enables arbitrary waveform generation, higher efficiency, and very low output impedance. In addition, it is also presented as a novelty that the voltage in each of the modules is different, following a digital to analog converter (DAC) structure, which allows us to obtain a lower total harmonic distortion (THD) in the output waveform than with conventional methods. The design will take advantage of wide band gap devices to be able to switch in the MHz range to achieve a high bandwidth. Furthermore, in addition to the design and implementation of a high-performance generator, a comparative analysis between the conventional and the proposed DAC-based modulation pattern is performed based on a comparative analysis of the THD and switching losses.

Tunneling Field-Effect Transistors (TFET) have emerged as promising candidates for integrated circuits beyond conventional metal-oxide-semiconductor field-effect transistors (MOSFET) and could overcome the physical limit, which results in the Subthreshold Swing (SS)

This paper proposes a direct model predictive control method with a fixed switching frequency for stator flux control of a synchronous reluctance machine. Besides ensuring a fixed switching frequency, the main objective is to minimize the ripple of the stator flux. The objective function, which calculates the switching time instants within the switching period based on the stator flux gradients, is formulated as a standard constrained quadratic programming (QP) problem. Instead of using general-purpose QP solvers, an iterative algorithm based on the active-set method with Lagrange multipliers is proposed to solve this particular QP problem while reducing the computational complexity of the proposed algorithm and enabling successful implementation in real-time embedded systems. The proposed method has been successfully implemented on a laboratory model and the results are compared with a conventional indirect model predictive control. The experimental results show better performance in stator flux ripple and lower total stator current distortion factor for the proposed method compared to the conventional method. A 7.5 kW synchronous reluctance motor drive was used for the experimental validation of the proposed control method.

Conventional state-space-based stability assessment method of voltage-source converters (VSCs) can be hindered by the black-box feature. Black box-based state-space model identification method using the terminal admittance/impedance frequency responses has thus been drawing increasing research attentions recently. However, the estimation of out-of-band modes commonly suffers from narrow bandwidth of frequency responses. This article presents, for the first time, the potential identification of several critical out-of-band modes of an artificially created rational function and a grid-connected VSC. This identification is achieved through their band-limited frequency responses using the vector fitting (VF) algorithm. On its basis, a sensitivity index of a partial fraction term is derived to explain the out-of-band modal identification behavior of the VF. The effects of the pole, residue, and fitting frequency interval width on the sensitivity index are further investigated and demonstrated. The numerical analysis shows that, with the help of the proposed sensitivity index, the extrapolation behavior of the VF can be explained, and several invisible out-of-band modes can further be identified or synthesized from a band-limited frequency response. This extrapolation feature may strengthen the curve fitting capability of the VF, i.e., compared to the VSC’s band-limited frequency responses, more modal information can be obtained and further used for eigenvalue-based stability analysis.

Accurate speed measurement and running records are integral to ensure safety and periodic maintenance of vehicles. This paper presents a novel structure of a solid rotary inverter (DAC) sensor for linear speed measurement of vehicles by eliminating reliance on magnets, coils, armatures, and toothed rings. The electromechanical sensor is exited through the vehicle’s DC power from the battery and utilizes a specially designed solid rotary part that is rotated mechanically by the wheel, enabling conversion of the DC into three-phase AC. The frequency of the produced AC voltage is proportional to the rotation speed. The three-phase alternating voltage is then used to run an analog speedometer gauge (a three-phase AC motor) to display the linear speed. The study determines stability analysis and response assessment by modeling a novel electromechanical rotational system and then evaluating its optimal design parameters. Real-time output voltage data from the sensor is acquired using a Rohde & Schwarz RTM 2034 oscilloscope and processed in MATLAB R2022b for frequency analysis. Experimental tests are conducted in a laboratory setting, varying the rotational speed sweep of the sensor from 150 to 450 RPM and translating the results into linear speed. A machine learning regression technique is applied to features such as shaft rotational speed, angular velocity, frequency, and period with linear speed. The obtained results reveal a total harmonic distortion (THD) value of −28.9778 dB (3.557%), meeting the criteria outlined in the IEEE 519–2014 “Recommended Practice and Requirements for Harmonic Control in Electric Power Systems.”

Neutral conductor loss on the upstream network of an electrical installation, as well as unintentional islanding operation, are two critical issues directly related to the safety of both human life and equipment of the electrical installation. Furthermore, another critical issue is meter tampering, which affects the operation and development of national power sectors. The state-of-the-art methods deal with those issues separately, without providing a holistic solution; moreover, they are facing several challenges in the prospect of mass storage installations at buildings. This article introduces a new scheme for the detection of neutral loss at the upstream network, the unintentional islanding conditions, and meter tampering simultaneously. In this context, a suitable technical solution is given by using one low-power H-bridge inverter and a current transformer, along with voltage and current measuring instruments. The detection scheme is based on the injection of a (zero-sequence) 12th harmonic voltage component in series with the utility voltage and the monitoring of the corresponding harmonic current component. The theoretical analysis of the proposed technique is discussed, whereas its effectiveness is validated through simulation and experimental results.

Due to the high efficiency and high performance of permanent magnet synchronous motors are used in various industries, such as aerospace. The main problem of achieving optimal performance control of PM synchronous motors is the heavy burden of control algorithms and large current pulsation. Due to the advantages of simple model predictive control algorithm and no need to set any control parameters, it is applied to the performance control of PM synchronous motors. The mid-point clamped three-level inverter is widely used because of its simple structure and versatility. However, the PM synchronous motor is susceptible to external load disturbances and internal parameter disturbances with large variations, and current harmonics and rotational arterial distance are difficult to control. In order to effectively solve the problem of disturbance disturbances, this paper proposes a functional disturbance observer (FDOB) based on the disturbance observer (DOB), which has the advantages of low order and handling more kinds of disturbances. In this paper, model predictive control and midpoint clamped three-level inverter are used. Compared with the traditional PI control method, the proposed functional disturbance observer plus model prediction control strategy can effectively reduce the disturbance perturbation of the motor, perform disturbance compensation, improve the motor speed response speed, improve the output current quality, enhance the system robustness and other advantages.

This paper deals with the control of maximum power production in a grid-connected photovoltaic system. The on-grid system ensures the continuity of electricity supply to consumers. It also offers less investment and operation cost due to the removal of battery requirements normally indispensable to guarantee supply continuity. To maintain the maximum output power production of photovoltaic panels regardless of changes in irradiation, proper control of the boost converter is necessary. The known perturb-and-observe method is explored and modified to improve performance. The modification is proposed by adding the measurement of the current variable to reduce the oscillation around the maximum power point once it is achieved. The connection to an existing single-phase alternating-current power grid is accomplished by implementing sinusoidal pulse-width modulation on the inverter. Phase-angle synchronization between the inverter output and the existing power grid is accomplished by using the phase-lock loop technique. Simulation of the proposed method showed that an improvement of the photovoltaic function up to 98% has been achieved.

In order to extend motor operation range, a self-voltage-boosting AC motor drive is proposed in this paper. Compared with the traditional frontend DC-DC converters, the proposed topology reuses the power switches inherently involved within the three-phase inverter without using any additional active components. By modifying the time distribution of the two zero vectors in traditional seven-segment space vector pulse width modulation (SVPWM) technology, the inductor current and the flying capacitor voltage can be adjusted. The proposed topology has the advantage of a wider operating range without extra cost. Moreover, the performance of the motor drive is not affected. Experimental results demonstrate the correctness of the proposed topology.

The proposal of deep and high sea and the application target of high maneuverability and concealment means that the future power system of underwater vehicles should have higher speed, power density, and efficiency. In the application of underwater high-speed and high-power motors, traditional Si-based power devices face the limitation of switching performance, and there are insufficient chopping times in the commutation cycle of the motor, which brings large torque ripple and loss to the motor. Therefore, in this paper, the power device loss was analyzed first. A simulation model was established in PSpice to compare the loss of SiC metal-oxide-semiconductor field-effect transistor(MOSFET) and insulated gate bipolar transistor(IGBT) at different switching frequencies and temperatures, and the motor torque ripple at different switching frequencies was compared in Simulink. The SiC power device had the advantages of high switching frequency and low switching loss, and then the SiC MOSFET was applied to the high-power and high-speed motor inverter module of underwater vehicles. The software and hardware of the inverter module were designed and compared with the IGBT inverter in terms of efficiency. At the same time, the influence of SiC MOSFET on the motor torque ripple at high frequency was analyzed, which provides a useful reference for SiC MOSFET application in underwater vehicles.

The efficiency of a photovoltaic installation is determined by its performance ratio (PR). This ratio depends on many parameters including orientation, inclination, shading, losses in cables, and number and performance of panels. The topology of the installation is also of great importance. Indeed, the number and location of the converter(s) can also have a significant impact on the PR. This is why choices between a central inverter, string inverters or micro-inverters must be made so as not to degrade the PR. In the scientific literature, it is stated that a photovoltaic installation equipped with a central inverter has a PR of 70–80%. For micro-inverters in theory, it should be higher. The objective of this publication is to compare the PR of installations equipped with a central inverter and string inverters with the PR of those using micro-inverters, based on a statistical study grouping together 200 private installations spread throughout metropolitan France. For a better comparison, 100 installations will use a central inverter or string inverters and 100 other installations will use micro-inverters. For each installation, the data will be averaged over the longest possible periods.

With the advantages of large transmission capacity, low losses, rapid and flexible power regulation, and the ability to achieve non-synchronous networking, High Voltage Direct Current transmission systems are playing an increasingly important role in long distance transmission and grid interconnection. However, under certain circumstances, such as disturbances in the DC transmission system and sudden load changes, the converter based on PI control in DC transmission system suffer from slow response speed and poor stability. In order to improve the stability of the system and the response speed of DC voltage, this paper proposes an adaptive linear active disturbance rejection control (A-LADRC) method. The method is based on the analysis of the relationship between key bandwidth parameters and output quantities in linear active disturbance rejection control and enables adaptive adjustment of the controller bandwidth parameters for fast regulation of the DC voltage and to improve the stability of the DC voltage in the event of disturbances. Finally, the proposed control method is validated by simulation, and the results show that the proposed control method can effectively improve the response speed and robustness of the DC voltage, which has good practical engineering value.

Multi-load wireless power transfer systems generally require the configuration of multiple transmitting coils. Using traditional single-output inverters will increase the number of inverters, leading to increased system costs and complex structures. Therefore, this paper proposes a single-input multi-output inverter that can drive multiple transmitting coils simultaneously. Compared with traditional single-output inverters and existing multi-output inverters, the proposed inverter utilizes a topology improvement design and an efficient expansion method. By adding only one inductor, one capacitor, and a small number of power switches, it can generate multiple controllable and stable outputs while ensuring output gain, which is expected to simplify the system structure and improve system performance. This paper first introduces the topology evolution process and operating principle of the proposed inverter. Secondly, a mathematical model is established to analyze its operating characteristics, and its parameter design is carried out. Meanwhile, a comparison with existing multi-output inverters is conducted. Then, the resonant compensation networks are analyzed and selected to match the requirements of different loads. Finally, a simulation model of the proposed inverter is constructed, and an experimental setup is set up. The feasibility and superiority of the proposed inverter are verified through simulation and experiments.

The paper presents the practical design and implementation of a three-level neutral point clamped (TNPC) six-phase inverter rated at 100 kVA. The study initiates with prior work review, whereby most research work done earlier was mainly simulation-based. Based on the simulation results, this paper focuses on the practical aspects of inverter design, such as the development of a power board on an Insulated Metal Substrate, a gate driver board, an interconnect board, and the main control board. An inverter physical prototype has been built and tested at 500 V and 20 kW of output power. The SiC semiconductor technology is the base of the inverter, which represents the main merit of the work. Finally, high power density, compact design, and high efficiency are shown, which are major contributions of the paper. Tests performed proved that the designed converter was operating reliably and efficiently. While a simple Sinusoidal Pulse Width Modulation (SPWM) control algorithm has been implemented, the overall performance of the inverter showed great promise for higher-power applications. Compact and high-efficiency TNPC converters are developed for meeting increasing demands of advanced energy, automotive, and industrial applications.

With the large-scale integration of renewable energy into the grid, traditional short-circuit current (SCC) calculation methods for synchronous generators are no longer applicable to inverter-based non-synchronous machine sources (N-SMSs). Current SCC calculation methods for N-SMSs often use a single-machine multiplication method, which tends to overlook the internal variability of N-SMSs within power plants, leading to low calculation accuracy. To address this issue, this paper first derives an analytical expression for SCC in grid-connected inverters under low voltage ride through (LVRT) control strategies. Then, a single-machine steady-state SCC calculation model is proposed. Based on the classification of N-SMSs, a practical SCC calculation model for renewable power plants is introduced, balancing accuracy and computational speed. The feasibility of the model is validated through simulations. The proposed method enables simple calculations to obtain the steady-state voltage and SCC at the machine terminal, offering strong engineering practicality.

This paper presents a low power emission (EM) pulse generation circuit using n-type amorphous In-Ga-Zn-Oxide (a-IGZO) semiconductor thin-film transistors (TFTs). The low power consumption is achieved by avoiding the shoot-through current paths through an optimized inverter circuit. The proposed circuit consists of 12 TFTs and 2 capacitors including 6 TFTs and 1 capacitor for the inverter circuit to control the pulling-down TFTs. In addition, the wider variance range of the threshold voltage (Vth) from −4 V to 2.5 V is covered by additional 6 TFTs for series-connected two transistor (STT) schemes and two low supply voltages to take into account the negative Vth of depletion-mode TFTs. The simulation of 30 EM circuits is conducted over a 6.1-inch active-matrix organic light-emitting diode display of 120 Hz refresh rate and 3840 × 2160 (UHD) resolution. The power consumption of the EM circuit with the proposed inverter is measured at the low values from 0.836 mW to 0.568 mW over pulse widths from 3 to 2157 horizontal times. It is ensured that the proposed circuit achieves the low power consumption regardless of pulse widths.

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.

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.

Relevance. The article provides a comparative analysis of micro-hydroelectric power stations with a hydraulic unit regulation along a hydrogenerator anchor circuit according to technical and economic efficiency. The authors substantiate the possibility of using intelligent control of the energy balance of inverter micro-hydroelectric power stations for increasing the amount of electricity generated without increase in the installed capacity of the hydraulic unit. This will improve their technical and economic characteristics compared with traditional micro-hydroelectric power plants of the ballast type. This approach allows using intelligent control systems that can regulate power generation depending on the peaks of electricity consumption. For this purpose, inverter micro-hydroelectric power stations are used. They allow more efficient management of energy consumption and accumulation of electricity in batteries. The developed control algorithms make it possible to optimize the operation of micro-hydroelectric power stations, ensuring maximum resource efficiency and reducing the cost of electric energy. Application of these technologies may significantly improve economic indicators of micro-hydroelectric power stations and make them more competitive in the electricity market. The algorithms control the hydraulic unit operation, ensure supply of electric power to consumers and effective use of energy storage batteries depending on electric needs. Aim. Comparative technical and economic analysis of a micro-hydroelectric power station with regulation of the parameters of the generated voltage along the anchor circuit of the hydrogenerator driven by an unregulated hydraulic turbine. Object. Micro-hydroelectric power stations of diversion type with power converters and electricity storage devices. Methods. Computer modeling. Results. The authors have proposed the classification of diversion micro-hydroelectric power stations with hydraulic unit control via the hydrogenerator anchor circuit. The paper demonstrates the technical and economic possibilities of various methods of their construction. The most promising technical solutions for inverter micro-hydroelectric power stations are determined, their energy balances and power equipment control algorithms are optimized.

The controlled-type soft-switching technology based on critical conduction mode (CRM) is an effective way to achieve zero voltage switching (ZVS) of switches. However, the high reverse inductor current of the conventional constant boundary conduction mode (CBCM) method leads to high conduction losses. In this paper, the single-phase three-level neutral point clamped (3L-NPC) inverter is taken as an example for analysis, and a minimum reverse inductor current control is proposed. Firstly, the requirement for achieving ZVS of switches is quantitatively analyzed, and the model of the equivalent resonance circuit is built. Accordingly, the theoretical minimum reverse inductor current for achieving ZVS in the fundamental period is derived, which lowers the conduction losses of switches. Then, by establishing the power losses analysis model of the 3L-NPC inverter, the power losses of the proposed scheme and the conventional CBCM method are calculated and compared in detail. Finally, a 1 kW single-phase 3L-NPC inverter prototype is built, and experimental results verify that the proposed method features lower conduction losses than that of the CBCM method. The maximum efficiency of the 3L-NPC inverter is increased by 0.5 percentage point.

This paper presents an extension of a 5-level T-Type inverter to a high-power multi-level inverter that can be implemented in electric vehicles and trucks. The proposed inverter possesses several advantages over standard topologies such as Neutral Point Clamped, Flying Capacitor, and Cascaded H-bridge. The main advantages are a low number of components, an estimated lower price and weight, smaller dimensions, and the implementation of only one DC voltage source per phase. The proposed topology can be implemented for any required odd number of voltage levels. Due to the estimated reduced dimensions and weight, the proposed topology is especially suitable for electric transportation applications. The operation of the proposed topology was validated for 9- and 13-level configurations under PD, POD, and APOD PWMs. The simulation results show the inverter’s practicability for supplying motors of electric trucks.

In case of an asymmetrical fault in PV accessed system， the inverter will simultaneously control the outputs of positive and negative sequence currents. However， there are few studies on inverter fault characteristics considering negative sequence control strategy. Therefore， the solution method for the steady-state short-circuit current of the inverter is firstly derived. Then the short-circuit current characteristics and equivalent negative-sequence impedance characteristics of the inverter output under asymmetrical faults are investigated by considering different negative sequence control strategies. The similarity and difference in the fault characteristics of photovoltaic power generation under different control strategies and different fault types are demonstrated. Finally， a simulation model is built to verify the theoretical analysis results. The results show that the influence of negative sequence control strategy should be fully considered in the study of fault characteristics and protection principle with the integration of new energies.

The article considers the construction of a simulation model of an electrical complex including an asynchronous electric motor with frequency regulation, driving a centrifugal pump. Fluid pumping stations based on centrifugal pumps with asynchronous electric drives controlled by frequency converters are widely used, which makes the work relevant. Obtaining the dynamic characteristics of these drives makes it possible to understand the relationship of energy distribution, as well as to coordinate the operating modes of its main parts. For this purpose, a simulation model of the electric drive of the liquid pumping station is developed. This simulation model is used to carry out numerical experiments of the system, which includes the power channel of the electric drive, as well as the control system. Simintech software product is used as a modeling environment. In the work, transient processes of the coordinates of the electric drive are obtained under the influence of both the hydraulic load and the power supply. The influence of the hydraulic resistance of the pressure pipeline and static back pressure on the mechanical characteristic of the moment of resistance of the electric drive as a whole is shown. The considered approach for calculating the characteristics makes it possible to evaluate the mutual influence of the coordinates of various physical nature of centrifugal pump installations with an asynchronous frequency-controlled electric motor on each other.

This article presents a comparative analysis of the technical and economic efficiency of a derivation-type inverter micro hydro power plant with an energy storage system and an auto-ballasted micro hydro power plant. The authors justify the possibility of saving financial resources by reducing the length of the derivationtype micro hydro power plant's pressure pipeline with an energy storage system. To optimally control the generating and transforming equipment of an autonomous power supply system, a control algorithm is proposed based on criteria for limiting the range of hydrogenerator rotational frequencies and ensuring the rational operating mode of the electric energy storage batteries according to the load's power consumption schedule. The possibility of using the charging current of the electric energy storage battery in combination with traditional resistive ballast to create a braking control moment for the hydrogenerator is justified. The article considers issues related to regulating the rational generated power of the hydrogenerator by aligning the power consumption schedule using electric energy storage systems, which allows reducing the length of the pressure pipeline and, consequently, capital costs. Thus, the article represents a comprehensive analysis of the technical and economic efficiency and optimal control of a derivation-type inverter micro hydro power plant with an energy storage system, which can be used in the design and operation of similar power supply systems.

The increasing demand for electrical energy must be balanced with using renewable energy. However, the use of renewable energy requires a system to maximize the conversion of renewable energy into electrical energy. Various topologies have been studied to achieve maximum energy conversion. Two types of inverters, namely step up-down, have been widely used but have their respective limitations. Step-down inverters can only be used in lower output voltage than input voltage conditions with simple control, while step-up inverters can only operate in higher output voltage than input voltage conditions. This paper aims to combine these two converters to have both step-up-down voltage functions, with the goal of expanding the operating range and maintaining the advantages of each type. Thus, a topology called a step-up-down five-level inverter with a simple voltage-controlled capacitor balancing system is proposed in this paper. Finally, the simulation and laboratory tests were done. This inverter operates in step-up-down voltage, and the voltage in capacitors is always balanced to reach the desired level. The voltage control was done to get the constant voltage event the load was changed.

When the digital hysteresis current control (DHCC) strategy is applied to control the uninterruptible power supply (UPS) inverter, here are some issues such as large hysteresis tracking error caused by sampling interval and severe switching frequency swing caused by rapid change rate of inductor current. To address these issues, this paper presents a digital control strategy based on the hybrid digital hysteresis current control (HDHCC) of variable opening time (VOT) and variable falling time (VFT) for UPS inverter. Firstly, the HDHCC structure is established and the working principle of the inverter system is described in detail. Then, the tracking error and switching frequency error of the DHCC are derived. Based on the performance requirement of quasi-constant frequency control of UPS inverter, VOT and VFT control criteria without the dependency of circuit parameters are given. The experimental results demonstrate that the hybrid digital hysteresis control strategy based on VOT and VFT has the advantages of high current tracking accuracy, accurate switching frequency control, small output voltage waveform distortion, and simple implementation.

To better tap into the potential of distributed renewable energy generation, microgrid system has become an emerging technology. As the bridge of microgrids, the inverters can flexibly convert distributed DC power input into AC power output. It is verified that the traditional droop control strategy for microgrid inverters has inherent defects of uneven reactive power distribution. To this end, this paper proposes a droop control strategy as a multi-objective optimization problem while considering the deviations of bus voltage and reactive power distributions of microgrids. Then, the optimization problem is further formulated as a Markov decision process and solved by a deep reinforcement learning (DRL) algorithm called deep deterministic policy gradient to obtain a dynamic optimal droop coefficient control strategy. Simulation results demonstrated that our DRL-based strategy eliminates the uneven reactive power distribution without voltage drop.

The shadow mode-based regular sampling methods are usually used in the digital control of power inverters, which introduce a control delay of one and a half sampling periods. The control delay affects the closed loop bandwidth and the stability of dc–ac inverters. Recently, regular sampling methods based on the immediate mode is emerging and helpful for reducing the digital control delay. When employing the immediate mode, the induced vertical crossings may arouse the duty-cycle loss and dead-band effect during the modulation process, which deteriorate the normal operation of the inverters. Although the duty-cycle loss can be avoided by forcing the PWM signal to flip at the occurrence of vertical crossings, the introduced dead bands still exist. Thus, this paper investigates the phenomenon of vertical crossings and proposes a control algorithm composed of predicting the occurrence of vertical crossings and compensating the dead-band effect for regular sampling methods based on the immediate mode. Finally, experimental results on a single-phase dc–ac inverter prototype are provided to compare the efficacy of different approaches.

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.

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.

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.

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.

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.

Common-mode voltage (CMV) leads to the shaft voltage and shaft current by coupling the capacitor network in the permanent magnet synchronous machine (PMSM), which affects the reliability of the whole motor drive system. Based on the low-CMV modulation strategy for the PMSM drive system, this paper proposed an improved near-state pulse-width modulation (NSPWM) on switching loss. First, the generation mechanism for the switching signals of NSPWM was analyzed, and it was observed that there exists one phase of switches in an inactive state for every sector. Then, to reduce the switching loss of the NSPWM, this paper proposed an improved NSPWM modulation strategy based on power factor angle to adjust switching action, which ensures the switching tubes that have the biggest conduction current have no switching action. In addition, the switching loss analytic formula of the NSPWM was derived to prove the correctness of the proposed method for optimizing switching loss. Finally, the proposed modulation strategy was carried out in the simulation and experimental platform. Under the premise of good steady and dynamic performance, the results show that the proposed modulation strategy has less switching loss.