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This paper proposes the design of a controller using the artificial neural network (ANN) for a solar photovoltaic (PV)-fed cascaded multilevel inverter (CMLI) to enhance the power quality. The objective of this presented ANN controller is to obtain a maximum output voltage with no filter components. This paper also investigates and eliminates the voltage harmonics that occurred in a solar-fed cascaded 3-stage inverter using various techniques such as pulse width modulation (PWM), digital logic control (DLC), fuzzy logic controller (FLC), and ANN, and the results are compared. Based on the results, the proposed ANN-based controller efficiently reduces harmonics and improves the power quality. This is achieved by solving the harmonic equations and thereby changing the switching angles of each semiconductor to a minimum value. The ANN is trained by a dataset consisting of varying input voltage and switching angles. The simulation was performed using MATLAB/Simulink for different types of controllers like PWM, DLC, FLC, and ANN for the 3-stage inverter. The simulated results are compared with the results obtained from a 3 kWp photovoltaic plant connected to the CMLI. Finally, on the basis of performance analysis, it was confirmed that the ANN-based controller effectively eliminates harmonics and improves the power quality. [ABSTRACT FROM AUTHOR]

This paper presents a mathematical model of 255 kW grid-connected solar photovoltaic (SPV) system. To study the performance characteristics of the grid-connected SPV system, a new hybrid adaptive grasshopper optimization algorithm with the recurrent neural network (AGO-RNN) control technique was implemented. Furthermore, the power quality at the point of common coupling (PCC) has been studied using the conventional (PSO) and proposed AGO-RNN controllers. The characteristics of the PV system were analyzed under varying environmental (variable irradiance and temperature) conditions considering 3 different cases such as (i) standard test conditions (STC), (ii) variable radiation with constant temperature, and (iii) variable radiation with variable temperature. For each case, the total harmonic distortion (THD) has been calculated using the proposed AGO-RNN control technique, and the results were compared with particle swarm optimization (PSO) technique. The 255 kW PV model is initially developed and connected to a three-level NPC inverter, an MPPT-based perturbation and observation algorithm. Later, the PV model is controlled by an AGO-RNN pulse width modulation (PWM) controller and is then integrated to the main grid at PCC. The main advantage of this technique is exploiting the separate DC-DC converter between the SPV module and the inverter. Finally, the proposed grid-connected SPV system was simulated on MATLAB for analyzing the performance of the system based on its I-V and P-V characteristics, inverter voltage, grid power, gird voltage, grid current, power factor, and THD under different environmental conditions. The simulation results demonstrate that the current magnitude and THD of the SPVGC system are improved with the cutting-edge AGO-RNN controller compared to PSO in all three different scenarios, and this value is less than 1.6%, which is within the permitted limits of IEC 61727 standards. [ABSTRACT FROM AUTHOR]

At present, with the development of wireless communication and microcomputer control system, the design and construction level of long-span bridges in China are also improving. How to improve the durability of bridge structure has become a major scientific and technological problem in bridge design and construction. This paper studies a microcomputer control system of bridge dehumidification based on energy consumption optimization and wireless communication. It compares three kinds of dehumidification and anticorrosion methods of bridge engineering, namely, freezing dehumidification system, rotary dehumidification system, and hybrid dehumidification system. In the hardware design of microcomputer control system of dehumidification system, ATmega128 bit main control chip and aluminum designer are used to draw the power circuit. Then, the MCU program of the air dehumidifier is written, and the power of the air dehumidifier is controlled by the PWM signal generated by the timer 0 of the MCU. The air dehumidifier is divided into three tap positions corresponding to three duty cycles, and the power of the air dehumidifier is changed according to the input tap position. [ABSTRACT FROM AUTHOR]

Globally, climate change has increased various environmental concerns, and there is a very high and still ever greater penetration of renewable energy power into energy grids. The intermittent nature of these energy sources has demanded a strong power electronic interface to maintain an uninterrupted power flow to the external load. This paper deals with a novel dual input quasi Z source inverter (qZSI) that can operate with two intermittent sources and perform a single stage power conversion. The novelty of the proposed methodology is the implementation of qZSI with a reduced number of switches, increased voltage gain, and a high boosting factor which results in increased efficiency. A simple boost control-based pulse width modulation (PWM) technique has been adopted, which has been observed after analysis, to have reduced the stress on the switches and simultaneously increased system efficiency. Perturb and observe method-based maximum power point tracking (MPPT) was integrated into the study with the control technique, and its performance was observed using MATLAB/Simulink and further validated with a scale down model. [ABSTRACT FROM AUTHOR]

In this article, the switched capacitor (SC) based high step-up multilevel inverter is proposed with self-balancing capability. The proposed SC inverter topology is to step up the high output voltage from the very low input voltage without any bulky transformer. This proposed inverter generates single-phase AC voltage with a frequency of 50 Hz from a very low DC input voltage of 50 V with any intermediate DC-DC conversion stage. Hence, the proposed SC inverter is highly suitable for fuel cell, photovoltaic (PV) applications, and shunt active power filter (SAPF). To control the SC inverter, a multicarrier pulse width modulation (PWM) technique is engaged in the inverter. The high step-up voltage level can be achieved by the charging and discharging process of the SC. Furthermore, the stress voltage of the switches does not exceed the applied voltage and the total standing voltage of the inverter is greatly reduced without H-bridges. The comparative analysis of the proposed SC inverter is made for the components, peak inverse voltage (PIV), total standing voltage (TSV), boosting ability, and voltage balancing of capacitors. The main theme of the paper is producing a thirteen-level sinusoidal current with acceptable total harmonic distortion (THD) at different loads, low PIV, TSV, high boosting ability, and self-balancing of capacitors with fewer passive components. The whole system is examined by using MATLAB/Simulink. [ABSTRACT FROM AUTHOR]

In this paper, two (series and parallel versions) quasi Z source inverter (qZSI)-based multioutput series-parallel topologies capable of supplying multiple three-phase AC and single boost DC outputs simultaneously are presented. The proposed parallel version topology can supply n number of AC outputs along with one boost DC with constant voltage and variable current. Similarly, the series version topology can give n number of AC including one boost DC output with constant current and variable voltage. The outputs of the proposed topologies can feed directly to DC/AC microgrids and multiple residential loads simultaneously without using any extra adapter/regulator and thereby avoiding local power conversion to meet the load demand. A hybrid pulse width modulation technique with constant frequency is used to operate the proposed topologies. The performance of the proposed topologies is verified by developing the prototypes of 2.18 kW (for parallel version) and 2.02 kW (for series version) for two three-phase AC outputs and one boost DC output. The developed prototypes show measured efficiency of 90.01% for the parallel and 89.95% for the series version topology. [ABSTRACT FROM AUTHOR]

The exploration target at different depths through the ground-airborne frequency domain electromagnetic method (GAFDEM) is detected by transmitting waveforms at different frequencies. When taking these different depths into detail, arbitrarily distributed frequencies are needed. However, the current transmitting waveforms are mostly in a fixed frequency ratio or frequency difference, which fails to meet the requirements of exploration accuracy and efficiency at the same time. Therefore, as a solution to this problem, this paper proposes a transmitting waveform design method based on selective harmonic eliminated pulse width modulation (SHEPWM) technology. In the SHEPWM method, three transmitting waveforms with the desired spectrum are obtained by directly controlling the switching angles of a binary sequence with an artificial neural network algorithm. Firstly, our study puts forward the basic theories and principles of the full-periodic asymmetric SHEPWM waveform. Secondly, the study, through simulation, realizes the pseudorandom, depth-focused, and layer-identification waveform with different detection depths. Finally, the application of the proposed SHEPWM waveform to the geological survey in Kaili City, Guizhou Province, proves the correctness and feasibility of this proposed method. [ABSTRACT FROM AUTHOR]

For six-phase permanent-magnet synchronous motor (PMSM) which has two sets of Y-connected three-phase windings spatially phase shifted by 30 electrical degrees, to increase the utilization ratio of the DC bus voltage, a novel space vector pulse width modulation (SVPWM) algorithm in full modulation range capability based on vector weighted method is proposed in this paper. The basic vector action time of SVPWM method is derived in detail, employing vector space decomposition transformation approach. Compared with the previous algorithm, this strategy is able to overcome the inherent shortcomings of the four-vector SVPWM, and it achieves smooth transitions from linear to overmodulation region. Simulation and experimental analyses demonstrate the effectiveness and feasibility of the proposed strategy. [ABSTRACT FROM AUTHOR]

The harmonics of line to line voltage in two-stage matrix converter (TSMC) with fixed carrier frequency had discrete and high values and produced powerful electromagnetic interference (EMI). In this paper, chaotic carrier frequency modulation technique (CCFMT) was applied in TSMC for the first time to spread sideband range and suppress harmonic peak value. Although this technique could suppress EMI, it would increase the probability of narrow pulses. In order to improve reliability, the rectifier in the two-stage matrix converter uses PWM modulation with zero vector to extend the zero current commutation time, solves the narrow pulse problem, and simplifies the commutation process. At last, an experiment platform was designed and experimental results showed that harmonics of line to line voltage was efficiently suppressed. [ABSTRACT FROM AUTHOR]

In this paper, a new topology of multilevel inverter (MLI) is designed with a fewer number of components and low total harmonic distortion (THD) for high-power photovoltaic (PV) systems. The key limitations of conventional MLI topologies are high total harmonic distortion (THD) and the use of a large number of switching components due to which the cost of the overall inverter is high. In conventional MLI, THD can be significantly reduced by the addition of a large value filter element at the input side; however, it will result in increased size and cost. Thus, achieving a pure sinusoidal AC at the output and to maintain a low THD level is a major issue in conventional MLIs. The proposed MLI has the advantage of decreasing the output THD by using a modified form of the cascaded H-Bridge structure and sine pulse width modulation technique. The proposed inverter consists of 6 unidirectional switches and 2 bidirectional switches, and there is no extra requirement for additional voltage balancing capacitors or clinching diodes. The individual switching states and SPWM operation for generating the gate pulses of the proposed MLI are discussed in detail. Relevant waveforms are plotted, equations are derived, and mathematical analysis is carried out. A steady-state analysis of the proposed MLI demonstrates an output voltage with 17 levels while using only four DC sources. Simulation results of the proposed MLI for single-phase and three-phase structures are obtained, and comparison is carried out with existing MLI topologies which shows that the proposed MLI has significantly low THD and better performance. From the results, it is clear that the proposed MLI has a THD of 3.52% in comparison with four conventional MLIs whose THDs are 6.1%, 6.63%, 7.3%, and 9.93%. Moreover, the proposed MLI generates 17 voltage levels by using only 08 switching devices, whereas the conventional MLIs use more than 10 switching devices for the generation of 15 voltage levels. [ABSTRACT FROM AUTHOR]

Communication is one of the most important foundations in the Internet of Things. Although some cutting-edge technologies, such as 5G, have greatly empowered edge computing, electromagnetic interference and pollution make them impracticable in many environments. The visible light communication (VLC) is a new type of wireless communication technology with appealing benefits not presented in radio communications. VLC allows a lamp or other light source to not only serve as illumination but also simultaneously transmit data. Although traditional VLC multiplexing technologies have been able to achieve a high-speed data transmission rate, they require all receivers to use the same modulation means. In many scenarios, various-type receivers coexist; it is costly to incorporate multiple senders to implement adaptive content distribution in on-demand services. In this paper, we propose a new type of VLC multiplexing system, which realizes end-edge data transmission through pulse position modulation (PPM), pulse width modulation (PWM), and pulse amplitude modulation (PAM) simultaneously. Therefore, one edge server can serve multiple types of end-users without interference. In order to evaluate the performance of the system, we conduct experiments with different settings of communication distance, communication angle, and different environmental light conditions. For three modulations, the proposed system can achieve a transmission speed three times as that for a single modulation, and reach the accuracy rate of up to 99% within the proper communication range. [ABSTRACT FROM AUTHOR]

This paper focuses on the design and development of a reconfigurable three-degree-of-freedom articulated robot for conducting pick-and-place tasks. To implement the system, an Android platform for the manual control of an articulated robot using wireless Bluetooth technology was developed. This application allows the user to manually reconfigure the robot following the requirements of the integrated system via a user-friendly display. The articulated robot comprises four motors, three of which are used for positioning and orientation and finally used to carry out the pick-and-place task. An Arduino Un R3 board is used to control the movement of the links via a pulse width modulation method. We introduce a set of conveniently composed kinematic and dynamic mathematical models for positioning the robot's arms and, in our results and discussion section, calculate and report the torque required to move each joint. [ABSTRACT FROM AUTHOR]

Model predictive control (MPC) method has been widely used to reduce the computational complexity of the traditional space vector pulse width modulation (SVPWM). However, for a neutral-point clamped three-level Z-source converter, the performance of the normal MPC strategy would highly depend on the computation processing rate because of the multiple times optimization calculation. In this paper, an improved MPC strategy has been developed, with a voltage prediction being designed to replace the current prediction, the calculation of the roll optimization could be effectively simplified significantly, and then the digital execution efficiency would be improved. Besides, in order to obtain a fixed output harmonic frequency, a combination of this improved MPC and SVPWM has been studied and the shoot-through state insertion for the Z-source also has been analyzed in detail. Lastly, comparison experiments have been carried out to make verification of this improved modulation mechanism. [ABSTRACT FROM AUTHOR]

This paper proposes a fuzzy PI controller to control the speed of a permanent magnet synchronous motor (PMSM). The structure of the system includes the speed loop controller (SLC) and the current loop controller (CLC). The speed loop controller is the fuzzy PI and standard model (SM). The CLC includes vector control and the space vector pulse width modulation (SVPWM). It compiles two closed-loop control systems for the PMSM. This research uses a very high-speed integrated circuit hardware description language (VHDL) to implement the proposed algorithm and embed it into Matlab/Simulink for simulation. Based on the PMSM parameter, this article tests the controller's correctness with some of the load cases by changing the combined inertia and viscous friction of rotor and load. After success in simulation, the system is tested again by experiment on the FPGA kit. The simulation and experiment results show that when the load changes, the PMSM speed is still stable. The novelty of this research is that it compares two kinds of controllers between simulation and experiment results. [ABSTRACT FROM AUTHOR]

In this paper, the problem of finite-time tracking is investigated for switched buck power converters based on the pulse width modulation (PWM) technique. For the continuous model, an equivalent continuous controller is solved by the backstepping technique, such that all signals are finite-time stable. PWM-based finite-time tracking with the equivalent control input is proposed for the switched buck converter, such that the tracking error converges to an arbitrarily small neighborhood of the origin in finite time, and the origin of the closed-loop system is practically finite-time stable. Simulation results are given to demonstrate the effectiveness of the proposed schemes. [ABSTRACT FROM AUTHOR]

Use of multilevel inverters with induction machines has become popular in most energy conversion and management systems. The present paper discusses the behavior of the dual stator-winding induction machine (DSIM) for the power source, which is a power supply with Neutral Point Clamped (NPC). Multilevel inverter with PWM technique control is analyzed. The DSIM control is obtained by the PWM technique to multicarrier PWM technique and after a comparative study of various characteristics of the DSIM taking into account the different electrical offsets between the two stars (0°, 30°, 60°). The gap between the two stars was considered, and it is impacted on torque and rates harmonic distortion of circulation currents. [ABSTRACT FROM AUTHOR]

This paper proposes a novel 3-phase asymmetric 3-level T-type NPC inverter and studies its PWM performance using a virtual space vector pulse width modulation control strategy. Firstly, the mathematical model and characteristics of this economical topology are described. Then, a virtual space vector approach is proposed to build a space vector diagram for designing SVPWM control. Similar to the conventional 3-level NPC inverter, the asymmetric inverter can also work with the neutral point voltage self-balancing in a fundamental period, which enables employment of this topology in various applications. Finally, simulation and experiment results under different load conditions have shown good output performance of the asymmetric 3-level topology. Similar tests are also performed on both conventional 2-level and 3-level inverters for comparison. For an almost similar number of different voltage vectors in the space vector diagram, the asymmetric 3-level topology can compete with conventional 3-level inverters for low-cost applications. The obvious benefit of the asymmetric 3-level inverter is a smaller number of switches devices while it can achieve output performance similar to that of the conventional 3-level. The comparative investigation also shows that the total loss given by SVPWM for the asymmetric 3-level configuration is lower than that of the traditional 3-level inverter. [ABSTRACT FROM AUTHOR]

This paper presents a simplified strategy in neutral-point (NP) potential balance of the neutral-point-clamped (NPC) three-level three-wire active power filter (APF). By introducing a simplified carrier-based pulse width modulation (CB-PWM) strategy and analysing the occurrence mechanism of NP potential unbalance, we proposed a NP potential balancing control strategy based on the simplified strategy. With this strategy, the NP current in a sampling period can be calculated through the detection of compensating current of APF. The three phase's duration time of reference voltage can also be computed through detecting the voltage fluctuation of upper and lower capacitors accurately, according to the law of charge conservation. Experiment results show that this proposed approach with simplified computation can effectively achieve NP potential balance. [ABSTRACT FROM AUTHOR]

Hybrid frequency control strategies are used to eliminate the problem of current inversion in multilevel cascaded asymmetrical H-bridge inverters. Unfortunately, this technique results in unbalanced power at the inverter output. The improved hybrid PWM modulation strategy helps to regulate power balances within a reasonable range at high and low voltages, by adjusting the conduction angle of the cells in high frequencies. However, as the conduction angle of a high-voltage cell increases, the fundamental amplitude of the inverter output voltage decreases, since waveforms with absolute values greater than 2 E cannot be perfectly modulated. Based on mathematical models of the conduction time for each level synthesis method, a new modulation strategy is proposed to solve the problems associated with the two strategies mentioned above. This new high-frequency modulation strategy adopts a combination of pulse-width modulation (PWM) and step modulation to combine control of the high-voltage and low-voltage units. At given intervals, the control voltage signals of the low-voltage unit are exchanged. Finally, the power of each unit is balanced and the basic amplitude of the inverter output voltage is not affected. Finally, the MATLAB/Simulink simulation model and experimental platform verify the feasibility of this strategy. [ABSTRACT FROM AUTHOR]

This paper proposes a high-performance indirect control scheme for torque ripple minimization in the switched reluctance motor (SRM) drive system. Firstly, based on the nonlinear torque-angle characteristic of SRM, a novel torque sharing function is developed to obtain the optimal current profiles such that the torque ripple is minimized with reduced copper losses. Secondly, in order to track current accurately and indirectly achieve high-performance torque control, a robust current controller is derived through the Lyapunov stability theory. The proposed robust current controller not only considers the motor parameter modeling errors but also realizes the fixed frequency current control by introducing the pulse width modulation method. Further, a disturbance-observer-based speed controller is derived to regulate the motor speed accurately, and the load torque is considered an unknown disturbance. The simulations and experiments on a 1.5 kW SRM prototype are carried out to demonstrate the effectiveness of the proposed high-performance indirect torque control strategy. Results verify the superiority of the proposed strategy with respect to the torque ripple suppression, system efficiency, and antidisturbance. [ABSTRACT FROM AUTHOR]

The paper describes the development of a microsatellite attitude determination and control subsystem (ADCS) and verification of its functionality by software-in-the-loop (SIL) method. The role of ADCS is to provide attitude control functions, including the de-tumbling and stabilizing the satellite angular velocity, and as well as estimating the orbit and attitude information during the satellite operation. In Taiwan, Air Force Institute of Technology (AFIT), dedicating for students to design experimental low earth orbit micro-satellite, called AFITsat. For AFITsat, the operation of the ADCS consists of three modes which are initializationmode, detumbling mode, and normal mode, respectively. During the initializationmode, ADCS collects the early orbitmeasurement data from various sensors so that the data can be downlinked to the ground station for further analysis. As particularly emphasized in this paper, during the detumbling mode, ADCS implements the thrusters in plus-wide modulation control method to decrease the satellite angular velocity. ADCS provides the attitude determination function for the estimation of the satellite state, during normal mode. The three modes of microsatellite adopted Kalman filter algorithm estimate microsatellite attitude. This paper will discuss using the SIL validation ADCS function and verify its feasibility. [ABSTRACT FROM AUTHOR]

This paper designs a hybrid speed controller in which a Sine Triangle Pulse Width Modulated (SPWM) inverter is used below the base speed and a square wave inverter is employed above the base speed. The two inversion techniques complement each other for their advantages and disadvantages below and above the base speed. This paper proposes a unique strategy for the transition between SPWMand square wave by simply setting the frequency of the carrier signal equal to zero. Theproposed methodology in a way uses only one inversion technique and realizes a seamless transition fromthe SPWMto square wave compared to conventional method in which modes are simply switched from SPWMto square wave and vice versa when the speed changes above and below the base speed, respectively. Computer simulations show that the proposed technique has smoother torque transition and thus a better speed response compared to conventional approach of inverter mode switching around the base speed. The performance of proposed hybrid approach is also validated on a small prototype induction motor through experimental results. [ABSTRACT FROM AUTHOR]

This paper further studies the pth moment exponential stability of stochastic pulse-width-modulated (PWM) feedback systems with distributed time-varying delays. We establish several globally exponential stability criteria for such PWM feedback systems by using Lyapunov-Krasovskii functional and then present an upper bound of the parameter of PWM when the system is stable and such system has stronger anti-interference performance than the system without time-varying delays. Furthermore, we present two examples to show the effectiveness and conservativeness of the theoretical results. [ABSTRACT FROM AUTHOR]

Multilevel inverters have great scope in current developments of grid-connected solar PV systems. Two-level inverters are the simplest kind of multilevel inverter available (MLI). As the number of output levels is raised, the total harmonic distortion decreases. In classic MLI topologies, more electronic components are utilized to get higher-level outputs, which raise the cost, complexity, and volume of typical MLI installations. By reducing the design components, the cost of the system will be reduced. Furthermore, the two- and three-level inverters produce constant dv/dt output, which increases the stress on the power switches. This research proposes an asymmetric MLI topology that is suitable for PV applications and utilizes less number of DC sources and switches. The proposed inverter is controlled by selective harmonic elimination-based pulse width modulation (SHEPWM) to eliminate the lower-order dominant harmonics. The nonlinear equations produced by the SHEPWM are solved for the switching angles of the proposed inverter using the Newton-Raphson (NR) method and particle swarm optimization (PSO) method for various modulation indexes. The performance of the proposed inverter is analyzed based on the total harmonic distortion (THD) of the output for different operating levels of the inverter by comparing similar topologies in the literature. The THD obtained by the NR method is 7.3% and by using PSO is 4.23% at 0.9 modulation index. [ABSTRACT FROM AUTHOR]

This article proposes an improved topology for an isolated bidirectional resonant DC-DC converter for electric vehicle (EV) onboard chargers. As opposed to the conventional capacitor-inductor-inductor-inductor-capacitor (CLLLC) resonant converter, the proposed converter's resonant circuit is composed of a capacitor-inductor-inductor-inductor (CLLL) structure, whose inductances, except the capacitor, can be fully integrated with the leakage and mutual inductances of the high-frequency transformer (HF). Therefore, this offers a smaller size, lower costs, minimal power loss, and eventually higher efficiency. Again, the proposed converter design is based on wide bandgap (WBG) transistor switches that operate at MHz-level switching frequency to achieve high power density, high efficiency, and high compactness. A discrete-time proportional integral derivative (PID) controller has been designed using the phase-shifted pulse width modulation (PSPWM) technique to assure closed-loop control of the proposed CLLL converter. The PID controller parameters have been optimized using both the genetic algorithm (GA) and particle swarm optimization (PSO) algorithm and a comparative analysis has been presented between the two algorithms. To achieve fast switching with very little switching loss, the converter is simulated with several wide bandgap (WBG) switching devices. A performance comparison with conventional Si-based switching devices is also provided. A precise power loss model of the semiconductor switches has been devised from the manufacturer's datasheet to achieve a perfect thermal design for the converter. A 5 kW CLLL converter with an input range of 400–460 V direct current (DC) and an output range of 530–610 V DC, and a switching frequency of 1 MHz has been designed and investigated under various loading scenarios. Gallium nitride (GaN) switching device-based designs achieved the highest levels of efficiency among the switching devices. The efficiency of this device is 97.40 percent in charging mode and 96.67 percent in discharging mode. [ABSTRACT FROM AUTHOR]

Multistability is a universal nonlinear feature for many areas of physics and technology; for most applications, it is an undesired feature leading to uncertainty of the system's functioning, and therefore, it should be controlled. We deal with the model of a multistable chopper-fed DC electric drive and study the control of multistability by the periodic modulation of a PWM (pulse-width modulation) carrier signal. The effect of utilizing sinusoidal modulation has been studied employing brute-force bifurcation diagrams as well as those obtained by numerical continuation, symbolic analysis of periodic modes, and normal form approximation of border-collision bifurcation. The result is formulated in terms of the acceptable amplitude of the modulation while the effect of phase shift is taken into account. As an alternative, a modified modulation in the form of the absolute value of the sine wave has been studied; the latter is characterized by a simpler bifurcation structure. Additionally, we propose an implementation of the adaptive control with the objective to drive the system away from a "nonnominal" mode. It has been demonstrated that such a transition should use smooth attenuation of the modulation signal to ensure the desired "nominal" operation of the system. [ABSTRACT FROM AUTHOR]

This paper proposes an improved multiloop control strategy for a three-phase four-leg voltage source inverter (VSI) operating with highly unbalanced loads in an autonomous distribution network. The main objective is to balance the output voltages of the four-leg inverter under unbalanced load conditions. The proposed control strategy consists of a proportional-integral (PI) voltage controller and a proportional current loop in each phase. The voltage controller and the current control loop are, respectively, used to regulate the instantaneous output voltage and generate the pulse width modulation (PWM) voltage command with zero steady-state tracking error and fast transient response. A voltage decoupling feedforward path is also used to enhance the system robustness. Since the outer voltage loop operates in the synchronous reference frame, tuning and stability analysis of the PI controller is far from being straightforward. In order to cope with this challenge, the stationary reference frame equivalent of the voltage controller in the rotating frame is derived. Subsequently, a systematic design based on a frequency response approach is provided. Simulation results are also carried out using the DIgSILENT PowerFactory software to verify the effectiveness of the suggested control strategy. [ABSTRACT FROM AUTHOR]

Interdependency of switching voltage and time creates a dilemma/obstacle for most resistive switching memories, which indicates low switching voltage and ultra-fast switching time cannot be simultaneously achieved. In this paper, an ultra-fast (sub-100 ns) yet low switching voltage resistive switching memory device (“nanometallic ReRAM”) was demonstrated. Experimental switching voltage is found independent of pulse width (intrinsic device property) when the pulse is long but shows abrupt time dependence (“cliff”) as pulse width approaches characteristic RC time of memory device (extrinsic device property). Both experiment and simulation show that the onset of cliff behavior is dependent on physical device size and parasitic resistance, which is expected to diminish as technology nodes shrink down. We believe this study provides solid evidence that nanometallic resistive switching memory can be reliably operated at low voltage and ultra-fast regime, thus beneficial to future memory technology. [ABSTRACT FROM AUTHOR]

In some special applications of NPC three-level inverters, such as mine hoist, there exist special conditions of overloading during the whole hoisting process and large overload in starting stage, during which the power-loss calculation of power devices and thermal control are important factors affecting the thermal stability of inverters. The principles of SVPWM and DPWM were described in this paper firstly, based on which the dynamic power losses of the two modulations of hoist in single period were calculated. Secondly, a thermal equilibrium dynamic control based on DPMW dual-mode modulation was proposed, which can switch the modulation dynamically according to the change of dynamic power loss to realize dynamic control of power loss and thermal equilibrium of inverter. Finally, simulation and experiment prove the effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

In the transmission and distribution of energy, circuit breaker plays a very important role. In order to fulfill the current market/user demands, they must be capable of promptly identifying the problem and isolating the problematic areas. According to the extinguishing medium used, circuit breakers are divided into the following categories: air blast, SF6, vacuum, and oil. Among others, permanent magnet (PM) based vacuum circuit breaker is also gaining popularity with each passing day and has become a crucial control and protection equipment in the modern power systems. This study proposes the pulse width modulation (PWM) intelligent control strategy for PM vacuum circuit breaker closing/opening capacitance, group charging, and movement process. For the practical implementation of this idea, dual CPUs are utilized for PM vacuum circuit breaker intelligent control components, by taking STM32F103RBT6 as the core and combining peripheral hardware circuit. PWM pulse output drives IGBT to fulfill the closing/opening capacitance group intelligent charging. On the other hand, PM circuit breaker closing/opening motion displacement signals and coil current feedback achieve closed-loop for PWM intelligent control. The experimental results show that the proposed intelligent control component and PWM intelligent control strategy effectively improve the PM circuit breaker intelligent charging and motion dynamic characteristics. [ABSTRACT FROM AUTHOR]

The main objective of this work is to study the behaviour of the solar PV systems and model the efficient Grid-connected solar power system. The DC-DC MPPT circuit using chaotic pulse width modulation has been designed to track maximum power from solar PV module. The conversion efficiency of the proposed MPPT system is increased when CPWM is used as a control scheme. This paper also proposes a simplified multilevel (seven level) inverter for a grid-connected photovoltaic system. The primary goal of these systems is to increase the energy injected to the grid by keeping track of the maximum power point of the panel, by reducing the switching frequency, and by providing high reliability. The maximum power has been tracked experimentally. It is compared with parallel boost converter. Also this model is based on mathematical equations and is described through an equivalent circuit including a PV source with MPPT, a diode, a series resistor, a shunt resistor, and dual boost converter with active snubber circuit. This model can extract PV power and boost by using dual boost converter with active snubber. By using this method the overall system efficiency is improved thereby reducing the switching losses and cost. [ABSTRACT FROM AUTHOR]

This paper presents a synchronous current control method for a three-level neutral point clamped inverter. Synchronous reference frame control based on two decoupled proportional-integral (PI) controllers is used to control the current in direct and quadrature axes. A phase disposition pulse width modulation (PDPWM) method in regular symmetrical sampling is used for generating the inverter switching signals. To eliminate the harmonic content with no phase errors, two first-order low pass filters (LPFs) are used for the dq currents. The simulation of closed-loop control is done in Matlab/Simulink. The Vertex-5 field programmable gate array (FPGA) in Labview/CompactRio is used for the implementation of the control algorithm. The control and switch pulse generation are done in independent parallel loops. The synchronization of both loops is achieved by controlling the length of waiting time for each loop. The simulation results are validated with experiments. The results show that the control action is reliable and efficient for the load current control. [ABSTRACT FROM AUTHOR]

Pulse-width pulse-frequency (PWPF) modulators arewidely used in spacecraft thruster control. Their dynamic characteristic is still lack of effective analysis tools. This paper presents a fractional describing functionmethod to describe the frequency characteristics of PWPF. A frequency-dependent gain and phase shift are clearly described by fractional-order expression, and the fractional-order behaviors depict the nonlinear properties of PWPF modulators. This fractional describing function method can also be applied to other kinds of modulators. [ABSTRACT FROM AUTHOR]

This paper proposes a zero-voltage-transition (ZVT) pulse-width-modulated (PWM) synchronous buck converter, which is designed to operate at low voltage and high efficiency typically required for portable systems. A new passive auxiliary circuit that allows the main switch to operate with zero-voltage switching has been incorporated in the conventional PWM synchronous buck converter. The operation principles and a detailed steady-state analysis of the ZVT-PWM synchronous converter implemented with the auxiliary circuit are presented. Besides, the main switch and all of the semiconductor devices operate under soft-switching conditions. Thus, the auxiliary circuit provides a larger overall efficiency. The feasibility of the auxiliary circuit is confirmed by simulation and experimental results. [ABSTRACT FROM AUTHOR]

The acquisition, alignment, and tracking system is an important part of airborne laser communication and is the prerequisite and guarantee for the normal communication link. In order to solve the problem of automatic tracking of laser communication links in the airborne environment, the rapid capture, alignment, and tracking of beams between terminals are realized. This article proposes a stepping motor as a control servo system and a four-quadrant detector as an automatic tracking method for the detection unit. The pulse width modulation signal controls the rotation speed of the stepping motor and combines the position distribution of the light spot on the four-quadrant detector to achieve high-precision beam tracking. On this basis, indoor simulation experiments are carried out. After many experiments, the tracking accuracy is better than 2.5 μrad, which shows that the system can be applied to airborne laser communication, and it is verified that this method has good automatic tracking performance for airborne laser communication. [ABSTRACT FROM AUTHOR]

Selective harmonic elimination pulse-width modulation (SHEPWM) is a widely adopted method to eliminate harmonics in multilevel inverters, yet solving harmonic amplitude equations is both time consuming and not accurate. This method is applied here for a 7-level cascaded multilevel inverter (CMLI) with erroneous DC sources. To meet the seven harmonic amplitude equations, two notches are applied with the use of higher switching frequency than nominal. These notches can be placed in six different positions in the voltage wave, and each was assessed in a separate manner. In order to solve the equations, a hybrid algorithm composed of genetic algorithm (GA) and Newton–Raphson (N-R) algorithm is applied to achieve faster convergence and maintain the accuracy of stochastic methods. At each step of the modulation index (M), different positions for the notches are compared based on the distortion factor (DF2%) benchmark, and the position with lowest DF2% is selected to train an artificial neural fuzzy interface system (ANFIS). ANFIS will receive the DC sources' voltages together with required M and will produce one output; thus, eight ANFISs are applied to produce seven firing angles, and the remaining one is to determine which one of the notches' positions should be used. Software simulations and experimental results confirm the validity of this proposed method. The proposed method achieves THD 8.45% when M is equal to 0.8 and is capable of effectively eliminating all harmonics up to the 19th order. [ABSTRACT FROM AUTHOR]

In this article, a modified single-phase five-level photovoltaic inverter is proposed with a single DC voltage source and six semiconductor switches. Compared with the presented inverters, the introduced topology has the advantage of decreased device count and the first switching frequency for high blocking voltage switches. The proposed PV inverter is implemented without clamping diodes and transformers, which leads to a decrement in size and, consequently, the weight of the converter. In addition, for the proposed topology, space vector pulse width modulation (SVPWM) is deployed that reduces the complexity of multilevel modulation. In order to obtain the optimal output voltage of the inverter, the deadbeat controller is suggested as a rapid dynamic, low-computation digital control method. This closed-loop inverter is implemented in TMS320f28335 digital signal controller to evaluate the performance of the proposed inverter under nonlinear and linear loads. Simulation and laboratory prototype results show that IEC 62040-3 harmonic constraints is met for the proposed photovoltaic inverter in standalone applications. [ABSTRACT FROM AUTHOR]

In the grid-connected inverter based on the deadbeat current control, the filter inductance variation and single update PWM affect the distortion of the grid current, stability, and dynamic of the system. For this, a double update PWM method for the deadbeat current controller in three-phase grid-connected system is proposed, which not only effectively decreases the grid current distortion and control delay, but also improves the system stability and dynamic response speed due to reducing the characteristic root equation order of the closed-loop transfer function. The influence of the filter inductance deviation coefficient on the system performance is analyzed. As a conclusion, the corresponding filter inductance deviation coefficient in the system critical stability increases with increase in the parasitic resistance of the filter inductance and line equivalent resistance and decreases with increase in the sampling frequency. Considering the system stability and dynamic response, the optimal range of the control parameters is acquired. Simulation and experimental results verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

A PV power-generation system with a phase-shift pulse-width modulation (PWM) technique for high step-up voltage applications is proposed. The proposed power-generation system consists of two stages. In the input stage, all power switches of the full-bridge converter with phase-shift technique can be operated with zero-current switching (ZCS) at turn-on or turn-off transition. Hence, the switching losses of the power switches can be reduced. Then, in the DC output stage, a voltage-do ubler circuit is used to boost a high dc-link bus voltage. To supply a utility power, a dc/ac inverter is connected to induce a sinusoidal source. In order to draw a maximum power from PV arrays source, a microcontroller is incorporated with the perturbation and observation method to implement maximum power point tracking (MPPT) algorithm and power regulating scheme. In this study, a full load power of 300 W prototype has been built. Experimental results are presented to verify the performance and feasibility of the proposed PV power-generation system. [ABSTRACT FROM AUTHOR]