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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.

The two-stage power converter is currently the most widespread topology for three-phase grid-connected photovoltaic (PV) systems. The PV power is injected to the grid through the regulation of the dc-link voltage. This method is commonly called the voltage control method, whereby the current is controlled indirectly. This paper focuses on the modelling of power converters and the parameter design of proportional-integral (PI) controllers, based on the bandwidth of the inner current loop and the outer voltage loop. It is assumed that the inner loop has a bandwidth that is ten-fold bigger than that of the outer loop, in order to fully decouple the dual loops. The PI parameters are thus determined through this relationship, and two sets of simulations are run to validate the methodology used. Results show that the controllers give highly satisfactory performance even in the presence of transients introduced by rapidly varying irradiance model. [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]

Conventionally, neutral beam injection (NBI) in tokamaks is controlled via engineering parameters such as injection voltage and power. Recently, the high-fidelity real-time NBI code RABBIT has been coupled to the discharge control system of ASDEX Upgrade. It allows to calculate the NBI fast-ion distribution and hence the properties of NBI in real-time, making it possible to control them directly. We successfully demonstrate control of driven current, ion heating and stored fast-ion energy by modifying the injected beam power. A combined ECRH and NBI controller is also successfully tested, which is able to adjust the heating mix between ECRH and NBI to match a certain desired ion heating fraction at given total power. Further experiments have been carried out towards control of the ion heat flux (i.e. ion heating plus collisional heat transfer between ions and electrons). They show good initial success, but also leave room for future improvements as the controller runs into instabilities at too high requests. [ABSTRACT FROM AUTHOR]

An autonomous multilevel single-phase inverter with no applied pulse-width modulation (PWM) and capacitive voltage dividers, the output voltage curve of which is close to a sine-wave shape and corresponds to the contemporary standards of electrical energy quality for 0.38-kV networks is considered. As compared with inverters with the use of PWM, the proposed inverter, owing to the use of low switching frequencies for power semiconductors at a level of the industrial frequency of 50 Hz and due to the optimal use of different-level amplitudes, should not generate significant electromagnetic interference and not cause accelerated wear in the insulation of connected equipment. Studies that have been performed with mathematical and physical models have demonstrated the potentiality of obtaining a voltage with a permissible harmonic coefficient at a level of KHU amounting to about 6.36% for 0.38-kV networks with the use of a three-level autonomous inverter constructed based on a three-core magnetic circuit of the transformer with a passive LC filter containing a sequential resonant circuit. [ABSTRACT FROM AUTHOR]

The operation of a three-phase inverter with output network chokes (a network regulator) in the reactive power compensation mode is considered. The main attention is paid to the comparison of two fundamentally different control systems based on pulse-width modulation and relay modulation. A model of the network regulator is developed, on the basis of which the characteristics of the output current quality and switching losses are obtained depending on the modulation frequency (the width of the hysteresis loop). The operation of the network regulator with a relay digital control system is considered. [ABSTRACT FROM AUTHOR]

This paper proposes a new space vector pulse-width modulation technique for reducing the common-mode voltage (SVPWM2) in a three-level T-type neutral-point-clamped voltage source inverter working under switch-open-circuit fault on a neutral-point-connected switch. Under this circumstance, the space vector diagram of the inverter becomes asymmetrical so that if the conventional reduced common-mode voltage space vector PWM (SVPWM1) patterns are still applied to IGBT drivers, the output waveforms are heavily deformed, thus leading to deteriorated harmonic distortion. Regarding SOC fault tolerant control, there are several traditional methods available. However, they are either costly due to additional hardware expenses or suffer from poor PMW performances using only two voltage level (2L) switching techniques. To address these issues, this paper introduces a cost-effective strategy: a reduced CMV space vector PWM strategy for fault tolerant control. This approach utilizes a hybrid two- and three-level switching principle to enhance PWM performances, resulting in reduced output harmonic distortion, lower voltage stress, and lower switching loss compared to the economical 2L PWM method. The SVPWM2 algorithm is firstly analyzed and synthesized in the $\alpha $ - $\beta $ coordinates and then implemented in MATLAB/Simulink and experimental hardware with TMS320F28377 microcontroller. Simulation and experiment waveforms are further evaluated in terms of total harmonic distortion and weighted total harmonic distortion to validate the effectiveness of the proposed algorithm.

Despite consistent maintenance and monitoring equipment installed in pumped storage hydropower (PSH) facilities, many shafts and electrical component failures are reported, possibly resulting from undetected sources. These sources include undetectable vibrations or, in certain conditions, high-frequency mechanical or electrical harmonics. This paper presents a direct method for plotting Campbell diagrams of large motors supplied by variable frequency drives (VFDs) for torsional analysis purposes in PSH systems. These diagrams display the precise locations where torsional stress components induced by VFDs can interfere with shaft resonance modes. The method simplifies the determination of the magnitude of stimulus forces in the motor airgap that may threaten the shaft. The method has been successfully applied to two-level, three-level neutral-point clamped, and seven-level cascaded H-bridge multilevel inverters, which are commonly used industrially available VFD topologies for pumped PSH plants. The paper also discusses the theoretical motor-pump voltage, current, and torque spectra when driven by a cascaded H-bridge multilevel converter operating with bypassed and faulty cells. The accuracy of the theoretical developments is supported by selected simulations results at different operating points and different fault conditions. Hybrid experimental-numerical VFD-induced harmonic stress analysis is also performed to demonstrate the relevance of the proposed study.

This paper investigates the development of pulse width modulation (PWM) schemes for three-phase quasi-Z-source inverters (qZSIs). These inverters are notable for their voltage boost capability, built-in short-circuit protection, and continuous input current, making them suitable for low-voltage-fed applications like photovoltaic or fuel cell-based systems. Despite their advantages, qZSIs confront challenges such as increased control complexity and a larger number of passive components compared to traditional voltage source inverters (VSIs). In addition, most existing PWM schemes for qZSIs lack the capability for independent control of the amplitude modulation index and duty cycle, which is essential in closed-loop applications. This study introduces innovative space-vector PWM (SVPWM) schemes, addressing issues of independent control, synchronization, and unintentional short-circuiting in qZSIs. It evaluates several established continuous and discontinuous PWM schemes, and proposes two novel decoupled SVPWM-based schemes that integrate dead time and in which the shoot-through occurrence is synchronized with the beginning of the zero switching state. These novel schemes are designed to reduce switching losses and improve qZSI controllability. Experimental validation is conducted using a custom-developed electronic circuit board that enables the implementation of a range of PWM schemes, including the newly proposed ones. The obtained results indicate that the proposed PWM schemes can offer up to 6.8% greater efficiency and up to 7.5% reduced voltage stress compared to the closest competing PWM scheme from the literature. In addition, they contribute to reducing the electromagnetic interference and thermal stress of the related semiconductor switches. [ABSTRACT FROM AUTHOR]

Servomotors have found widespread application in many areas, such as manufacturing, robotics, automation, and others. Thus, the control of servomotors is divided into various principles and methods, leading to a high diversity of control systems. This article provides an overview of types of servomotors and their basic principles and control methods. Principles such as digital signal processing, feedback control principle, field-oriented control, and integration with Industry 4.0 are discussed. Based on these control principles, the article presents popular control methods: PWM control, current control, two-loop control, fuzzy-logic control, and programmable control. The article concludes with a comparison of the presented methods on several criteria, and as an example, it includes the results of modeling a servomotor using the fuzzy-logic control method. [ABSTRACT FROM AUTHOR]

A comprehensive proton-exchange membrane fuel cell stack model was developed and integrated with a two-stage DC/DC boost converter. It was directly coupled to a single-phase (two levels—four pulses) inverter without a transformer. The pulse-width modulation signal was used to independently regulate every converter phase. The converter was modelled using a MATLAB®/Simulink® environment and an appropriate voltage control method. The analysis features of the suggested circuit were created and, through established experiments, the simulation results were verified. A single-phase (two levels—four pulses) inverter control circuit was tested and it produced a pure sinusoidal waveform with voltage control. It matches the voltage of the network in terms of amplitude and frequency. A sinusoidal pulse-width modulation approach was performed using a single-phase (two levels—four pulses) pulse-width modulation inverter. The results demonstrated an enhancement in the standard of the output wave and tuned the dead time with a reduction of 63 µs compared with 180 µs in conventional techniques. [ABSTRACT FROM AUTHOR]

The combination of five-level converters with selective harmonic elimination pulse-width modulation (SHEPWM) is a practical need in medium-voltage, high-power applications. However, how to suppress the common-mode voltage (CMV) in this case becomes a difficult problem. Although CMV suppression under high switching frequency (SF) modulations and three-level SHEPWM has been discussed in many studies, these methods are not applicable to five-level SHEPWM. This is partly because the zero-sequence voltage under SHEPWM is difficult to adjust and partly because the solution spaces of three- and five-level SHEPWM are completely different. Moreover, conventional CMV suppression in three-level SHEPWM must sacrifice the switching angles to control the zero-sequence voltage, which makes the equivalent SF increase. Therefore, in this article, we propose a novel CMV suppression method that effectively utilizes the multimode characteristics of five-level SHEPWM. Multimode characteristics refers to the output waveform containing different levels of jump patterns. Therefore, there are a large number of switching angle trajectories in five-level SHEPWM, which outputs the same fundamental voltage with different CMVs. The proposed method uses the special multimode characteristics to reduce the CMV without sacrificing the switching angles. Its effectiveness and feasibility are verified by experiments. [ABSTRACT FROM AUTHOR]

Increasing the number of phases in step-down dc converters allows to increase power and has a positive effect on the energy efficiency of the converters. However, there is a problem of phase-current imbalance in such converters, which leads to uneven loading of the phases and does not allow to achieve the design power and efficiency. The article provides an overview of existing methods for current balancing in multiphase converters, and discusses their advantages and disadvantages. [ABSTRACT FROM AUTHOR]

Using the pulse-width modulation (PWM) is a very convenient and efficient way to generate the approximation of the AC, in the simplest case sinewaves in the embedded test & measurement solutions. Partly, because the on-chip PWM modulator is available in most of the microcontroller and DSP chips. In the current paper improved (compared with conventional PWM) implementation of the binary waveforms is proposed. The idea is based first on the conversion of the desired AC (e.g., sinewave) to quantize in the amplitude domain waveform, to be further converted to the binary pulses with a duty cycle, corresponding to each quantization level. Such an approach is described and analyzed, with several examples of the implementation and application for impedance measurement solutions. The results show the significant improvements of the approximated binary signals both in the frequency and time domain, by optional simple low- or bandpass filtering of the binary signal, over classical PWM, while still preserving simplicity (e.g., number of needed binary signal segments) of the generated waveforms (e.g., compared with delta-sigma bitstreams). The beneficial usage of the proposed approach for the impedance measurement applications is described, as well as to generate excitation waveforms, as well as to be used as reference waveforms for synchronous demodulation of the response signal. It is shown, that for the frequency range of 10 to 70 kHz total harmonic distortion below 2.5% can be achieved by the proposed improved PWM solution. [ABSTRACT FROM AUTHOR]

Voice-controlled (VC) systems, such as mobile phones and smart speakers, enable users to operate smart devices through voice commands. Previous works (e.g., LightCommands) show that attackers can trigger VC systems to respond to various audio commands by injecting light signals. However, LightCommands only discusses attacks on devices with a single microphone, while new devices typically use microphone arrays with sensor fusion technology for better capturing sound from different distances. By replicating LightCommands’s experiments on the new devices, we find that simply extending the light scope (just as they do) to overlap multiple microphone apertures is inadequate to wake up the device with sensor fusion. Adapting LightCommands’s approach to microphone arrays is challenging due to their requirement for multiple sound amplifiers, and each amplifier requires an independent power driver with unique settings. The number of additional devices increases with the microphone aperture count, significantly increasing the complexity of implementing and deploying the attack equipment. With a growing number of devices adopting sensor fusion to distinguish the sound location, it is essential to propose new approaches to adapting the light injection attacks to these new devices. To address these problems, we propose a lightweight microphone array laser injection solution called LCMA (Laser Commands for Microphone Array), which can use a single laser controller to manipulate multiple laser points and simultaneously target all the apertures of a microphone array and input light waves at different frequencies. Our key design is to propose a new PWM (Pulse Width Modulation) based control signal algorithm that can be implemented on a single MCU and directly control multiple lasers via different PWM output channels. Moreover, LCMA can be remotely configured via BLE (Bluetooth Low Energy). These features allow our solution to be deployed on a drone to covertly attack the targets hidden inside the building. Using LCMA, we successfully attack 29 devices. The experiment results show that LCMA is robust on the newest devices such as the iPhone 15, and the control panel of the Tesla Model Y.

Multilevel inverters (MLIs) have become more popular for medium-voltage and high-power applications. The cascaded H-bridge multilevel inverter (CHBMLI) is one of the three most popular topologies of MLIs. It was more reliable due to its fewer components per level. The number of possible output voltage levels is more than twice the number of DC sources, the most suitable topology for integration with renewable energy sources, easy to design, and has good performance with modularity. The main disadvantage of CHBMLI is the need for separate DC sources for each H-bridge. However, this can be considered as an advantage to be employed in renewable energy applications. This paper provides a review of CHBMLI topologies and pulse width modulation (PWM) techniques, including fundamental and high switching frequency techniques, such as selective harmonic elimination (SHE), space vector modulation (SVM), nearest level modulation (NLM), and Carrier-Based PWM.

Introduction. This research presents a simple single-phase pulse-width modulated 7-level inverter topology for renewable system which allows home-grid applications with electric vehicle charging. Although multilevel inverters have appealing qualities, their vast range of application is limited by the use of more switches in the traditional arrangement. As a result, a novel symmetrical 7-level inverter is proposed, which has the fewest number of unidirectional switches with gate circuits, providing the lowest switching losses, conduction losses, total harmonic distortion and higher efficiency than conventional topology. The novelty of the proposed work consists of a novel modular inverter structure for photovoltaic energy system and electric vehicle applications with fewer numbers of switches and compact in size. Purpose. The proposed system aims to reduce switch count, overall harmonic distortions, and power loss. There are no passive filters required, and the constituted optimizes power quality by producing distortion-free sinusoidal output voltage as the level count increases while reducing power losses. Methods. The proposed topology is implemented with MATLAB/Simulink, using gating pulses and various pulse-width modulation methodologies. Moreover, the proposed model also has been validated and compared to the hardware system. Results. Total harmonic distortion, number of power switches, output voltage, current, power losses and number of DC sources are investigated with conventional topology. Practical value. The proposed topology has proven to be extremely beneficial for implementing photovoltaic-based stand-alone multilevel inverter and electric vehicle charging applications.

Abstract- The space vector pulse-width modulation (SVPWM) is a simple and suitable method for voltage control of three-phase two-level voltage source inverters (VSI)s. However, there are plenty of methods to improve the two-level VSIs performance by adding virtual vectors or sub-sectors to the SVPWM diagram which cause complexity in implementation of SVPWM for VSIs similar to multilevel inverters. Operation in overmodulation mode is the other reason for complexity in conventional SVPWM. This paper proposes a novel modulation method, named as level vector pulse-width modulation (LVPWM), for voltage control of VSIs. The concept of the proposed method is similar to SVPWM but with different vector diagram and dwell times calculations. Unlike the SVPWM, the α and β axes and also their variables are considered separately without gathering in complex variables. The vector diagram has two separated α and β axes each of which contains individual switching vectors and reference vectors. The selection of the vectors to synthesize the reference vectors depends on only the amplitudes of the reference vectors. With lower computational overhead and easy and continuous extension to overmodulation region, the proposed method is a simple solution to the mentioned problems. Simulation and experimental results and harmonics analysis verify the effectiveness of the proposed algorithm.

Summary: Multilevel inverter is a practical power electronic design that has motivated a great deal of ever‐increasing interest. In this article, a new design of basic module‐based multilevel is proposed. The article conceptualized minimizing the number of power semiconductor devices, losses, and total blocking voltage and hence the cost. The proposed inverter structure consists of both a polarity generator and a level generator unit. To investigate the eminence of the proposed topology, an exhaustive comparative study with other existing topologies is presented. The proposed inverter can be utilized for both symmetrical and asymmetrical configurations. The extended cascaded structure of the proposed topology is discussed for generating a higher level of voltages and five algorithms for asymmetrical configuration are introduced to select input dc voltages. This article presents the operating principle, modulation strategy, total standing voltage calculation, cost function, and losses calculation. The efficacy of the proposed cascaded multilevel inverter has been substantiated experimentally. The proposed structure can be efficiently used in medium‐/high‐voltage applications like electrical drives as well as renewable energy resource‐based grid‐connected systems. [ABSTRACT FROM AUTHOR]

Summary: This paper presents sliding mode pulse‐width modulation (SMPWM) for current‐controlled five‐leg converter (FLC) in wind energy system. The proposed topology substitutes at once two three‐phase converters, classified as back‐to‐back (BTB), by sharing one leg between the permanent magnet synchronous generator (PMSG) and power grid. To overcome the coupling of the two sides, the control of common leg is introduced. SMPWM methodology is designed using system dynamic model and surface decoupling approach to make system tracking desired references. The reference currents are selected to perform control requirements of PMSG wind turbine. The phase currents are controlled simultaneously during normal operation and in the event of unbalanced grid voltages. Different operating conditions are tested under wind variations including a turbulence component. The main objectives are to achieve balanced and sinusoidal currents, as well as smooth active and reactive powers injected into the grid. Simulation results show that FLC can act as BTB converters and demonstrate the effectiveness of the proposed control scheme. [ABSTRACT FROM AUTHOR]

Antimicrobial blue light (aBL) is an effective non-destructive inactivation technique and has received increasing attention. Despite its significance, the existing research has not thoroughly delved into the impacts of irradiance and irradiation time on enhancing energy efficiency during aBL inactivation and the explanation of the enhancement effect of pulse exposure. In this paper, a series of Escherichia coli inactivation experiments with different duty cycles, pulse frequencies, and irradiation times were conducted, and the relative concentrations of reactive oxygen species (ROS) were measured under corresponding conditions. A two-dimensional (2-D) Hom model was proposed to evaluate the effect of irradiance and irradiation time. The results show that, compared to continuous exposure, pulsed aBL (duty cycle = 25%) can save ~37% of the energy to achieve the same inactivation effect and generate a 1.95 times higher ROS concentration. The 2-D Hom model obtains the optimal combination of average irradiance and time according to the desired reduction and shows that the irradiation time has a higher weight than the irradiance (1.677 and 1.083, respectively). Therefore, using pulse exposure with a lower average irradiance for a longer period of time can achieve a better inactivation effect when consuming equivalent energy. The proposed pulse-width modulation dimming approach helps promote the application of the aBL technique. [ABSTRACT FROM AUTHOR]

Currently, residual useful life (RUL) prediction models for insulated-gate bipolar transistors (IGBT) do not focus on the multi-modal characteristics caused by the pulse-width modulation (PWM). To fill this gap, the Markovian stochastic process is proposed to model the mode transition process, due to the memoryless properties of the grid operation. For the estimation of the mode transition probabilities, transfer learning is utilized between different control signals. With the continuous mode switching, fractional Weibull motion (fWm) of multiple modes is established to model the stochasticity of the multi-modal IGBT degradation. The drift and diffusion coefficients are adaptively updated in the proposed RUL prediction model. In the case study, two sets of the real thermal-accelerated IGBT aging data are used. Different degradation modes are extracted from the meta degradation data, and then fused to be a complex health indicator (CHI) via a multi-sensor fusion algorithm. The RUL prediction model based on the fWm of multiple modes can reach a maximum relative prediction error of 2.96% and a mean relative prediction error of 1.78%. The proposed RUL prediction model with better accuracy can reduce the losses of the power grid caused by the unexpected IGBT failures. [ABSTRACT FROM AUTHOR]

The issue of converted voltage distortion by high-power converters at pulse-width modulation (PWM) with a low switching frequency of semiconductor modules is still relevant. Currently, the Programmed Pulse Pattern PWM (PPWM) technique is used extensively that allows pre-eliminating the selected harmonics from the converter's voltage and current spectrum or reducing them to meet the voltage quality standard requirements. A review of scientific publications has shown the insufficiency of available studies on defining and estimating the impact of powerful converters with PPWM. The problem of defining the amplitudes of higher harmonics generated by a converter with PPWM, which are the main cause of electronic equipment failures at the common grid connection point, is particularly relevant. This study considers the behavior of the NPC converter voltage and current spectra at PPWM with the selected harmonic elimination (SHE) for three-level (3L) voltage waveforms. The behavior of up to the 50th non-eliminated harmonics in the NPC converter voltage and current spectra is first shown for a modulation factor changing within 0–1.15 at the pitch of 0.01 for six different SHE PPWM: no. 1–5 and 7; no. 2–5, 7, 11, and 13; no. 3–5, 7, 11, 13, 17, and 19; no. 4–5, 7, 11, 13, 17, 19, 23, and 25; no. 5–5, 7, 11, 13, 17, 19, 23, 25; 29, and 31; no. 6–5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, and 37. The concept proposed herein allows measuring the current consumed amplitudes of NPC converter with SHE PPWM at the low average error of about 6%. The adequacy of the approach used herein to determine the current harmonic amplitudes has been experimentally verified with laboratory equipment. The results are consistent with engineering accuracy. The research work is promising for further study and estimation of the impact of the NPC converter SHE PPWM for more complex multi-pulse grid connection circuits and resonance phenomena. [ABSTRACT FROM AUTHOR]

Introduction. This research presents a simple single-phase pulse-width modulated 7-level inverter topology for renewable system which allows home-grid applications with electric vehicle charging. Although multilevel inverters have appealing qualities, their vast range of application is limited by the use of more switches in the traditional arrangement. As a result, a novel symmetrical 7-level inverter is proposed, which has the fewest number of unidirectional switches with gate circuits, providing the lowest switching losses, conduction losses, total harmonic distortion and higher efficiency than conventional topology. The novelty of the proposed work consists of a novel modular inverter structure for photovoltaic energy system and electric vehicle applications with fewer numbers of switches and compact in size. Purpose. The proposed system aims to reduce switch count, overall harmonic distortions, and power loss. There are no passive filters required, and the constituted optimizes power quality by producing distortion-free sinusoidal output voltage as the level count increases while reducing power losses. Methods. The proposed topology is implemented with MATLAB/Simulink, using gating pulses and various pulse-width modulation methodologies. Moreover, the proposed model also has been validated and compared to the hardware system. Results. Total harmonic distortion, number of power switches, output voltage, current, power losses and number of DC sources are investigated with conventional topology. Practical value. The proposed topology has proven to be extremely beneficial for implementing photovoltaic-based stand-alone multilevel inverter and electric vehicle charging applications. [ABSTRACT FROM AUTHOR]

Servomotors have found widespread application in many areas, such as manufacturing, robotics, automation, and others. Thus, the control of servomotors is divided into various principles and methods, leading to a high diversity of control systems. This article provides an overview of types of servomotors and their basic principles and control methods. Principles such as digital signal processing, feedback control principle, field-oriented control, and integration with Industry 4.0 are discussed. Based on these control principles, the article presents popular control methods: PWM control, current control, two-loop control, fuzzy-logic control, and programmable control. The article concludes with a comparison of the presented methods on several criteria, and as an example, it includes the results of modeling a servomotor using the fuzzy-logic control method.

This paper investigates the development of pulse width modulation (PWM) schemes for three-phase quasi-Z-source inverters (qZSIs). These inverters are notable for their voltage boost capability, built-in short-circuit protection, and continuous input current, making them suitable for low-voltage-fed applications like photovoltaic or fuel cell-based systems. Despite their advantages, qZSIs confront challenges such as increased control complexity and a larger number of passive components compared to traditional voltage source inverters (VSIs). In addition, most existing PWM schemes for qZSIs lack the capability for independent control of the amplitude modulation index and duty cycle, which is essential in closed-loop applications. This study introduces innovative space-vector PWM (SVPWM) schemes, addressing issues of independent control, synchronization, and unintentional short-circuiting in qZSIs. It evaluates several established continuous and discontinuous PWM schemes, and proposes two novel decoupled SVPWM-based schemes that integrate dead time and in which the shoot-through occurrence is synchronized with the beginning of the zero switching state. These novel schemes are designed to reduce switching losses and improve qZSI controllability. Experimental validation is conducted using a custom-developed electronic circuit board that enables the implementation of a range of PWM schemes, including the newly proposed ones. The obtained results indicate that the proposed PWM schemes can offer up to 6.8% greater efficiency and up to 7.5% reduced voltage stress compared to the closest competing PWM scheme from the literature. In addition, they contribute to reducing the electromagnetic interference and thermal stress of the related semiconductor switches.

During night flights of unmanned aerial vehicles, determining the location of the device during take-off and landing and the possibility of injury to maintenance personnel from a rotating propeller poses a certain problem. The problem is especially pronounced with a large diameter of rotor blade, which is difficult to highlight with a strobe light. The article describes the design of the rotor blade tip’s illumination system, which can be placed on propellers of any diameter without an additional battery source. This allows not only to make these lighting systems maintenance-free but also to fly in extreme conditions of low temperatures. This novelty will be especially useful when operating in the Arctic, where the polar night lasts for several months and there are very low ambient temperatures. [ABSTRACT FROM AUTHOR]

A prosthetic is a contrived machine of human anatomy that substitutes an off-track torso portion, which helps in regaining functionality. The fundamental purpose of this paper is to design a low-priced robotic limb that offers the basic functionality of a human hand. Mainly, it deals with controlling servo motors, and it is extended to build a prosthetic arm. Servo motors assist in response to arbitrate the locus of the stab. As an outcome, servo motors are utilized to regulate the locus of the items with high precision and are controlled by a signal known as the pulse-width modulator. Hence, the control of the servo motor is made possible by connecting the PWM input to the individual of the Arduino's digital yield pins. Myoware muscle sensors are used in the limb, which will determine the resolved electrical action of power output in volts. This output of the muscle sensor is given to Arduino to regulate the position of the servo motor, resulting in the control of the fingers of an arm. These arms are used majorly in warfare in countries that lost their arms during battles and for persons who met with major road accidents. This arm can be further controlled from different places by using a wireless RF transceiver. [ABSTRACT FROM AUTHOR]

A method for correcting the output voltage waveform of single-phase autonomous inverters is considered, which consists in replacing the pulse-width modulation with amplitude modulation by using multiwinding transformers from the standpoint of the theory of structural synthesis of static converters. The efficiency assessment of this method is based on the calculation of the harmonic coefficients, which are minimized when solving optimization problem. [ABSTRACT FROM AUTHOR]

The results of experimental investigations of the glow kinetics of narrowspectrum LEDs based on InGaN-GaN 450 and 520 nm and AlGaInP-GaAs 625 nm structures are presented. The increase and decrease of the light flux intensity under pulsed power are described by exponential dependences containing fast and slow components. The time constants of both components decrease with the increase of the pulse frequency for all three types of LED samples. The time constant of the slow component decreases with the increase of the current and voltage pulse amplitudes. The maximum light output on the frequency dependences of LED energy characteristics is observed at the frequency of 75...100 kHz. Further frequency increase results in the decrease of the LED energy efficiency. The obtained results are explained based on the LED equivalent electrical and energy circuits. [ABSTRACT FROM AUTHOR]

Compared with other topologies, the modular multilevel converter (MMC) has the advantages of higher scalability and lower harmonic distortion. When carrier-based pulse-width modulation approaches are used for the MMC, the number of carriers increases for more sub-modules, and the complexity of the control and the memory required increases as a result. In addition, the synchronization of several carriers is another issue. Due to the unique constructional characteristics of the MMC, circulating currents will be generated internally, causing distortions in the arm currents and, thus, unnecessary converter losses. In this paper, an improved 2N+1 pulse-width modulation approach with low control complexity and a circulating current suppression strategy are proposed. Firstly, the conventional carrier phase-shifted 2N+1 pulse-width modulation approach is improved so that the number of carrier signals adopted in each arm is always two. Secondly, the redundant switching states are used to suppress the circulating current. Finally, the effectiveness of the proposed strategy is verified experimentally. The results show that the proposed method reduces the control complexity while retaining the output performance. Meanwhile, the circulating current can be suppressed. [ABSTRACT FROM AUTHOR]

The relevance of the research is caused by the need to improve the quality factors of output voltage and current of voltage inverters in electric submersible pumps, used in oil production. The main aspects, which allow improving these quality factors are: usage of perspective topologies of power part and modern power semiconductor keys, implementation of new control algorithms. In electric drives, where frequency converters are used, there are negative factors, affecting oil-submersible cable and submersible induction motor functioning. Non-sinusoidal voltages at the frequency converter output lead to increased wear and tear of the supply cable insulation, and also negatively affect the insulation of induction motor windings and reduce the quality indicators of electric drive control systems. Consequently, the search for ways to improve the quality of the output voltage and current of the voltage inverters in electric submersible pumps is a critical task. The main aim of the research is to develop the algorithms to improve the reliability indicators of multilevel converters and upgrade the quality of harmonic composition of the output voltage and current of voltage inverters as part of the electric drive of a submersible oil-producing pump. Object: voltage inverters as a part of electric drive of submersible oil producing pump. Methods and tools: reliability theory, harmonic analysis, functional diagrams, switching functions, topology of electric circuits of power converters, numerical methods for solving differential equations, fast Fourier transform, Matlab Simulink. Results. Significant improvement of current and voltage quality factors in multilevel converters as a part of electric drive of submersible oil-producing pump has been demonstrated. Possible ways to improve reliability indicators by changing the layout option of the circuit topology have been considered, with the probability of no-failure operation increasing from 23,70 to 66,10 % as compared to the classical layout. It is established that regulation of switching frequency depending on operating modes in multilevel inverters will allow controlling rationally dynamic losses and loads on power keys.

Goal. Development of a methodology for calculating the parameters of the active rectifier-voltage source input filter operating with a fixed modulation frequency to ensure electromagnetic compatibility with the supply network acceptable by standards at minimum values of the input inductance and checking its main characteristics on a mathematical model. Methodology. The authors have developed a methodology for calculating the parameters of the input filter of an active rectifier-voltage source. The calculation results are verified on the constructed mathematical model of a frequency converter, the scheme of which is an active rectifier and an autonomous voltage inverter. A series of experiments was carried out on a mathematical model to study the dependence of the total harmonic distortion of current and mains voltage on the value of the input inductance for various parameters of the input filter. Results. The structure and calculation procedure the input filter of an active rectifier operating with a fixed modulation frequency are proposed. The simulation results showed that the inclusion of a filter at the input of the active rectifier significantly improves its electromagnetic compatibility with the supply network in the entire range of variation of the input inductance of the circuit and makes it possible to achieve the values of the total harmonic distortion permissible by the norms. Originality. A structure and a calculation procedure the input filter of an active rectifier-voltage source operating with a fixed modulation frequency are proposed. Practical significance. The dependencies obtained in the article allow us to evaluate the relationship between the parameters of the filter elements and its characteristics among themselves and come to a compromise between them when designing a scheme for specific technical conditions.

This manuscript proposes a novel approach for determining phase and neutral-current-ripple RMS in grid-connected four-leg inverters with the neutral inductor. The harmonic pollution is determined for any arbitrary pulse width modulation (PWM) technique and a generic value of the neutral inductor. Thanks to the proposed approach, it is possible to describe the neutral inductor in a parametric way with respect to phase inductors and obtain a wide range of results, ranging from a direct neutral connection (no neutral inductor) to a conventional three-phase inverter (no fourth wire) for any value of modulation index and common mode injection. The results permit one to compare different design choices in multiple scenarios effectively. The findings were validated by numerical simulations and experimental tests employing the most popular PWM techniques, such as space vector PWM (SVPWM) and discontinuous PWM (DPWM). [ABSTRACT FROM AUTHOR]

This study presents the characteristics and performance of a motor at the operating point based on pulse-width modulation (PWM). PWM is used in modulating the output voltage of a three-phase inverter. The PWM technique has advantages and disadvantages depending on the system size and operating range. For example, some discontinuous pulse-width modulation (DPWM) techniques are advantageous in low-cost systems because they can reduce the number of switches. Some PWM techniques are complicated for software construction and require a lot of computation. In this paper, PWM techniques were constructed by using the offset voltage injection method. Therefore, the construction of the PWM technique is simplified by the method. In an experimental setup, an interior permanent-magnet synchronous motor (IPMSM) and a three-phase inverter were implemented to test motor control performance depending on the PWM technique. In addition, the current control characteristics and inverter efficiency were analyzed and compared depending on the speed and load of the motor. According to the results of this paper, it is possible to compare the motor and inverter control characteristics using various types of PWM rapidly. Additionally, it will help to select an appropriate PWM technique for a specific system. [ABSTRACT FROM AUTHOR]

Currently, design solutions have almost exhausted the possibilities of further increasing the power and efficiency of Brushless Direct Current (BLDC) motors. The main limitation of the power increase with the existing dimensions is the permissible operating temperature of the enamel insulation of the winding wire and the heating of neodymium magnets. The article analyzes the temperature dependences of BLDC motor components depending on the materials used. In addition, ways of modernization of BLDC motors with the help of new materials and structural solutions are being considered. All the theoretical approaches considered have been implemented in practice; their effectiveness has been proven by experiments. A new design of the BLDC motor rotor allowing improving the heat sink of the neodymium magnets used, which has an overall impact on their magnetic strength and lifecycle, is discussed. The article explores the use of new materials for various components of a BLDC motor to improve its thermal, mechanical, and magnetic characteristics. The main goal of the ongoing modernization is to increase the power and service life of the BLDC without changing their dimensions, which is very important when using them in UAVs. [ABSTRACT FROM AUTHOR]

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In vehicle-to-grid (V2G) applications, dual active bridge (DAB) converters are commonly used as the power interface because they offer high efficiency, galvanic isolation, and bidirectional power flow. For the DAB control strategy, phase-shift control is the mainstream, especially the single-phase-shift (SPS) method because of its ease of implementation. However, due to the phase shift, a DAB converter operated under this control method has relatively high backflow power, resulting in poor efficiency. The SPS control method has the drawback of high backflow power, especially at light loads. Thus, this paper proposes a new dual-mode control scheme to improve the light load efficiency of DAB converters by taking advantage of the pulse-width modulation (PWM) strategy in combination with the conventional SPS strategy for DAB converters based on load conditions. In other words, when the DAB converter operates under light load conditions, the PWM control strategy is used to avoid considerable backflow power. A prototype DAB converter with a power rating of 1 kW under a switching frequency of 100 kHz interfacing a DC bus (400 V) and a battery pack (50 V) is designed and implemented to verify the feasibility of this control strategy. A detailed analysis of the working principle and design parameters of the proposed converter is provided in this paper. Experimental results show that the highest efficiency of the proposed converter at light loads (10–200 W) was 96.2% for the forward power conversion and 97.3% for the backward power conversion. [ABSTRACT FROM AUTHOR]

Featured Application: Provide a robust-control design technique for pulse-width-modulated power converters in continuous conduction mode using low-cost analog circuits. In this paper, a simplified double-integral sliding-mode control method for pulse-width-modulated dc-ac buck conversion is introduced. The control equation is derived based on the equivalent control method, in which the control-oriented model is developed using the averaged dynamics of the power converter in continuous conduction mode. In contrast with the conventional sliding-mode control schemes, the complexity of adding a capacitor current sensor, variable ramp voltage, and other relevant components is avoided. Furthermore, the control equation is translated into a simple electronic circuit with minimal added components, which reduces the practical implementation cost. The proposed control method rejects large disturbances, tracks the reference signal, and maintains a constant switching frequency. Systematic design procedure, control parameters selection, and stability conditions are presented. The design methodology is verified via simulating the proposed control circuit using Simscape Electrical in MATLAB. The control method is also compared with the conventional double-integral sliding-mode control scheme under load disturbances. The results show that the simplified control approach provides a fast transient response and robust tracking performance. [ABSTRACT FROM AUTHOR]

This paper proposes a novel topology, named a single-phase active switched-capacitor embedded quasi-Z-source inverter (ASC-EqZSI), and two pulse-width modulation (PWM) methods, namely, PWM1 and PWM2 methods for the proposed ASC-EqZSI topology to improve the boost capability and reduce switching loss. The boost capability can be improved by using an additional non-shoot-through (NST) state, referred to as the NST2 state, besides conventional shoot-through (ST) and NST states. In the NST2 state, the switch in the impedance network is switched on to boost the dc-link voltage while generating the ac output voltage. A PWM1 method is suggested to control both the NST2 and ST time intervals with one carrier signal for improving the boost capability. A PWM2 method aims to reduce the commutation count of the switches and diodes in the proposed topology while maintaining the enhanced boost capability. The switching loss can be reduced by almost 40%. A comparative analysis between the proposed topology with the PWM2 method and five other topologies with an active switched Z-network is performed. The proposed topology with the PWM2 method has a higher ac voltage gain and efficiency with fewer components. Simulation and experimental results are carried out to validate the performances of the proposed topology and PWM methods.

Isolated bi-direction DC-DC converters are widely used for energy storage systems (ESS) of DC microgrids. Particularly, a current-fed isolated bi-directional DC-DC converter (CF-IBDC) receives much attention due to its merits such as the naturally attenuated current ripple on the battery side. However, high efficiency cannot be obtained at the light and heavy load conditions under the conventional control methods. In this paper, a hybrid switching modulation is proposed to improve the power conversion efficiency of the CF-IBDC under light and heavy load conditions. The duty cycle of the secondary sides and the phase shift angle are independently controlled according to the amount of the transferred power. The control strategy is based on the optimization of zero-voltage switching (ZVS) conditions and the minimization of the circulating current in the power converter. Using the proposed control algorithm, the ZVS capability can be obtained under the entire load condition, and the circulating current can be minimized under the single phase-shift modulation (SPSM). Experimental results with a 1-kW laboratory prototype CF-IBDC validate the effectiveness of the proposed modulation algorithm.

Antimicrobial blue light (aBL) is an effective non-destructive inactivation technique and has received increasing attention. Despite its significance, the existing research has not thoroughly delved into the impacts of irradiance and irradiation time on enhancing energy efficiency during aBL inactivation and the explanation of the enhancement effect of pulse exposure. In this paper, a series of Escherichia coli inactivation experiments with different duty cycles, pulse frequencies, and irradiation times were conducted, and the relative concentrations of reactive oxygen species (ROS) were measured under corresponding conditions. A two-dimensional (2-D) Hom model was proposed to evaluate the effect of irradiance and irradiation time. The results show that, compared to continuous exposure, pulsed aBL (duty cycle = 25%) can save ~37% of the energy to achieve the same inactivation effect and generate a 1.95 times higher ROS concentration. The 2-D Hom model obtains the optimal combination of average irradiance and time according to the desired reduction and shows that the irradiation time has a higher weight than the irradiance (1.677 and 1.083, respectively). Therefore, using pulse exposure with a lower average irradiance for a longer period of time can achieve a better inactivation effect when consuming equivalent energy. The proposed pulse-width modulation dimming approach helps promote the application of the aBL technique.

Currently, residual useful life (RUL) prediction models for insulated-gate bipolar transistors (IGBT) do not focus on the multi-modal characteristics caused by the pulse-width modulation (PWM). To fill this gap, the Markovian stochastic process is proposed to model the mode transition process, due to the memoryless properties of the grid operation. For the estimation of the mode transition probabilities, transfer learning is utilized between different control signals. With the continuous mode switching, fractional Weibull motion (fWm) of multiple modes is established to model the stochasticity of the multi-modal IGBT degradation. The drift and diffusion coefficients are adaptively updated in the proposed RUL prediction model. In the case study, two sets of the real thermal-accelerated IGBT aging data are used. Different degradation modes are extracted from the meta degradation data, and then fused to be a complex health indicator (CHI) via a multi-sensor fusion algorithm. The RUL prediction model based on the fWm of multiple modes can reach a maximum relative prediction error of 2.96% and a mean relative prediction error of 1.78%. The proposed RUL prediction model with better accuracy can reduce the losses of the power grid caused by the unexpected IGBT failures.

The issue of converted voltage distortion by high-power converters at pulse-width modulation (PWM) with a low switching frequency of semiconductor modules is still relevant. Currently, the Programmed Pulse Pattern PWM (PPWM) technique is used extensively that allows pre-eliminating the selected harmonics from the converter’s voltage and current spectrum or reducing them to meet the voltage quality standard requirements. A review of scientific publications has shown the insufficiency of available studies on defining and estimating the impact of powerful converters with PPWM. The problem of defining the amplitudes of higher harmonics generated by a converter with PPWM, which are the main cause of electronic equipment failures at the common grid connection point, is particularly relevant. This study considers the behavior of the NPC converter voltage and current spectra at PPWM with the selected harmonic elimination (SHE) for three-level (3L) voltage waveforms. The behavior of up to the 50th non-eliminated harmonics in the NPC converter voltage and current spectra is first shown for a modulation factor changing within 0–1.15 at the pitch of 0.01 for six different SHE PPWM: no. 1–5 and 7; no. 2–5, 7, 11, and 13; no. 3–5, 7, 11, 13, 17, and 19; no. 4–5, 7, 11, 13, 17, 19, 23, and 25; no. 5–5, 7, 11, 13, 17, 19, 23, 25; 29, and 31; no. 6–5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, and 37. The concept proposed herein allows measuring the current consumed amplitudes of NPC converter with SHE PPWM at the low average error of about 6%. The adequacy of the approach used herein to determine the current harmonic amplitudes has been experimentally verified with laboratory equipment. The results are consistent with engineering accuracy. The research work is promising for further study and estimation of the impact of the NPC converter SHE PPWM for more complex multi-pulse grid connection circuits and resonance phenomena.