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In this paper, we present a new digital resonant current controller that can be applied in single-phase and three-phase alternating current (AC) power converters, based on voltage source inverters (VSI) with pulse width modulation (PWM). Since power converters based on PWM introduce fractional time delays regarding the sampling period (T s), because of the current sampling and PWM command updating techniques that are employed, there is a need to develop analytical tools for precise modelling of these types of delays. To achieve this, the advanced Z-transform is applied in order to model the AC controllers in VSIs with PWM for the general case of a fractional time delay, including power converters with current sampling within a PWM period at any chosen time instance. This new approach to power converter modelling and current sampling allowed us to develop a modified resonant AC current controller for a VSI with RL load, based on the pole-placement parameter tuning method. It includes fractional time delays, which are conventionally employed in the power converter design, in the controller parameter derivations, and introduces the minimal order resonant controller that enables strict placement of all closed-loop control system poles. Simulations and experimental tests are carried out to show the improvements introduced by novel solution in this paper compared with conventional resonant current controllers. In the analysis of dynamic performance and robustness, in this paper conventional indices are applied to compare the proposed controller with a conventional design. • The introduction of the Advanced Z-Transform enables analytical modelling of the plant that includes a fractional time delay. • Novel pole-placement based parameter tuning procedure is presented, which places all closed-loop system poles at required positions. • New controller is compared with existing solution by test runs and conventional dynamic performance and robustness indices. [ABSTRACT FROM AUTHOR]

Precisely controlled digital pulse plays a crucial role in various cutting-edge testing applications. This paper introduces an innovative approach to digital pulse generation utilizing an FPGA transceiver, with the AMD evaluation board ZCU102 serving as a demonstrative platform. In the normal mode, the transmitter generates a serial bit stream, enabling the generation of single or repeated pulses with configurable width and period. In the high precision mode, an internal dedicated phase interpolator enhances the configuration step size for width and period by up to 64 times, providing finer phase shift capability. The demonstration system operates at a line rate of 10 Gbps, achieving a resolution of 100 ps in normal mode and 1.5625 ps in high precision mode. This paper details the design methodology, presents test results for pulse width uncertainty and non-linearity, and showcases achieved period jitter and time interval error jitter as small as around 1 ps. • A novel digital pulse generator is implemented with GTH transceiver in AMD FPGA. • Transceiver can produce digital pulse by controlling the sent bits with low jitter. • Resolution can be further enhanced by phase interpolator in the transceiver. [ABSTRACT FROM AUTHOR]

The high-gain DC converter is a crucial step in the conversion process for raising the voltage from PV panels to the desired voltage level in renewable energy applications. This article proposes a three-phase grid connected PV system with a novel interleaved high gain DC converter fed 3-level Neutral-Point-Clamped (NPC) Inverter. The novel high-gain DC converter consists of an interleaved boost converter (IBC) at its input side, a switched capacitor cell, a passive clamp circuit, and a voltage multiplier unit (VMU). The interleaved arrangement eliminates the input current ripple, and the VMU is utilized to improve the overall voltage gain besides the reverse recovery problem of diodes. The proposed converter is operated at a duty cycle D = 0.6 and a high voltage conversion ratio of 17.5 which is ideal for sustainable energy applications. This paper uses the proposed converter for a grid-connected solar PV system with an NPC inverter controlled using Space Vector Pulse Width Modulation (SVPWM) technique. The SVPWM strategic approach is a prevalent modulation technique for NPC inverter due to its extensibility in choosing the ideal voltage vectors. It uses an active filter, which is more dependable, dynamically better behaved, and capable of operating accurately under distorted grid voltages under varying load conditions. The proposed grid-associated PV system with a novel interleaved converter and 3-level NPC inverter is employed in Matlab/SimPower System and experimentally verified. Power loss and efficiency calculations were performed on the DC converter side, and the efficiency was 96.07%. NPC inverters have a THD of 22.2%. Results from simulations and experiments indicate that the suggested topology can efficiently extricate the maximal amount of power from PV modules and inject energy into the grid system with excellent steady-state and dynamic performance. [Display omitted] • The Incremental & Conductance MPPT method is engaged for tracking MPP. • The grid connected novel DC converter has the high voltage gain of about 17.5 at a nominal duty ratio of D = 0.6. • The novel DC converter is appropriately utilized for 3-level NPC Inverter to generate grid voltage. • The proposed structure is successfully synchronized to the grid by Synchronous Reference Frame Phase Locked Loop (SRFPLL). [ABSTRACT FROM AUTHOR]

Traditional plant protection machinery cannot apply pesticides according to the actual growth demand of crops, which causes a lot of pesticide waste and serious environmental pollution. Based on this, an intelligent variable-rate application system based on 3D LiDAR (light detection and ranging) scanning and PWM (pulse-width modulation) control for maize canopy was developed in this paper. After completing the performance testing, the system was mounted on a lightweight high-clearance self-propelled sprayer by remote controlling with an operating width of 6.0 m, and a ground gap of 2.0 m. And the actual operational performance of the sprayer showed that the prediction error of LiDAR for plant height was within 10%, which illustrated the accuracy of the detection system and the reliability of the variable application based on the plant height change. And the variable-rate system could adjust the spray volume in real-time according to the plant height change. The penetration rate of the upper, middle, and bottom layers maintained a relatively stable state (upper > middle > bottom) at variable-rate application and could reach the normal application level. This study can provide new ideas for efficient pests and diseases control of high stalk crops, especially suitable for small fields, and gives a reference for the structural design of new precise variable-rate application machinery and performance optimization of efficient application technology. • A complete intelligent application system has been developed. • A reliable decision model of application quantity is established. • The intelligentsprayer meets the spraying technology requirements. [ABSTRACT FROM AUTHOR]

Increasing solar-photovoltaic-power penetration necessitates the implementation of flexible power point tracking (FPPT) in solar farms. However, coordinating multiple solar photovoltaic (PV) power generation systems (SPVPGSs) poses a significant challenge due to their inherent intermittency and varying dynamic characteristics, complicating FPPT implementation. To overcome this challenge, this paper proposes a distributed economic model predictive control (DEMPC) scheme to achieve FPPT, while simultaneously enhancing overall economic performance in solar farms. By integrating solar farm control and local control into one optimal control framework, this scheme eliminates the need for power allocation, PV voltage reference calculation, and pulse width modulation. Leveraging the SPVPGS model and soft power constraint, DEMPC controllers are designed to achieve the economic targets of solar farms, which cooperate through a communication network to realize FPPT and economic optimization. Additionally, the strong nonlinearity of SPVPGS causes a non-convex mixed integer nonlinear programming (MINLP) problem, solved by a MINLP algorithm using finite converter switching states. Simulations under step-changed irradiance and power reference, as well as urgent maintenance conditions, demonstrate that the DEMPC-based FPPT scheme significantly outperforms the traditional hierarchical model predictive control-based FPPT scheme, presenting both superior dynamic response and enhanced economic performance in FPPT implementation. • A FPPT strategy based on DEMPC is proposed for solar farms. • A converter-based solar farm model is constructed. • A MINLP algorithm is proposed to solve online non-convex optimization problem. • The proposed scheme enhances dynamic economic performance for solar farms. [ABSTRACT FROM AUTHOR]

Staircase Modulation (SCM) is a popular switching strategy for multilevel inverters (MLI), which is often a preferable alternative to Pulse Width Modulation (PWM) due to its reduced switching losses, especially for MLIs with a relatively high number of voltage levels (N). In some applications, such as motor drives, or when output filters are applicable, SCM may also suit MLIs with moderate N values. While MLIs with Equal DC Sources (EDCS) are more common, MLIs with Unequal DC Sources (UDCS), such as asymmetric Cascaded H-Bridge (CHB) MLIs are known to further reduce the waveforms' Total Harmonic Distortion (THD). The main objective of SCM is to adjust the waveform's fundamental component, while employing some harmonic mitigation strategy, such as THD minimization. Such an optimization approach relies on an accurate THD formulation, which eliminates underestimation errors associated with numerical THD approximations. This paper reveals novel generic analytical formulations of both Phase-voltage THD (PTHD) for single-phase MLIs and Line-voltage THD (LTHD) for three-phase MLIs. The revealed exact formulation approach is derived from Fourier series representation of THD, resulting in simple closed-form PTHD and LTHD expressions, applicable to any MLI topology, with either EDCS or UDCS configurations, and arbitrary value of N (odd and even). Given an arbitrary N value, the proposed formulations can be used to generate symbolic N -level PTHD or LTHD expressions, which are symbolic functions of the Phase Switching Angles (PSA) and (optionally) the DC source Ratios (DCR). The revealed THD formulations are verified and compared against recently introduced time-domain-based THD formulations. It is shown that when both time and frequency-based formulations are employed in THD minimizations to form a novel Hybrid Temporal-Spectral (HTS) Optimal Minimization of THD (OMTHD) approach, even better results can be achieved. The novel OMTHD is deeply explored and verified by both digital simulations and Controller + Hardware in Loop (C-HIL) based real-time experiments using 7- and 8-level three-phase MLI configurations. A downloadable supplemental file containing Maple and MATLAB functions of the proposed THD expressions, as well as pre-calculated sets of optimum variables for different values of N is provided for readers' convenience. [ABSTRACT FROM AUTHOR]

This paper introduces a nine-level (9L) boost inverter topology with reduced peak standing voltage (PSV) across the switches. The topology consists of a single DC source, two capacitors, a switched-capacitor (SC) and a floating capacitor (FC), and eleven power electronics switches. Due to the inherent voltage boosting capability, the proposed inverter is suitable for low-scale voltage applications such as photovoltaic (PV), fuel cell, and single battery-operated electric vehicles (EVs). A sensorless approach is introduced to stabilize the requisite voltage across the FC for any changes in input voltage. A generalized topology is also presented to obtain n-times voltage gain along with a high number of intermediate voltage levels. The PSV of the switches does not exceed the value of the input DC voltage, irrespective of increase in voltage gain. The results show that the voltage across the FC is unaffected by stepped variations in the modulation indices, power factor of load, pulse width modulation (PWM) techniques, and the operating frequency. Furthermore, when the input voltage changes, the voltage across the FC is automatically adjusted to a new requisite value within 0.6 s. The topology works for a wide range of modulation indices (0–1) and loads. A thorough analysis is done to show that the proposed topology is superior to recent topologies. [ABSTRACT FROM AUTHOR]

With the volatile oil prices and the need to reduce the emission of greenhouse gases, renewable energy resources are a very attractive alternative. Africa has a good potential for micro hydroelectric power generation. However, only a small proportion of this potential has been harnessed. As a result, most rural areas in Africa have limited access to electric power. Unfortunately, those rural communities privileged to be connected to the grid also have unreliable and expensive grid power. To meet their energy needs, some of the communities have installed and operate Pico or Micro Hydro Power Plants (MHPPs) based on the Build-Own-Operate (BOO) model. In any power generation plant, a speed governor is required for regulating the frequency of supply under varying load conditions. However, this is the single most expensive component in a MHPP and most of the community owned plants can hardly afford it and thus, have no means of continuously regulating frequency. An Electronic Load Controller (ELC) is a device used to control the sharing of constant generator output power between the consumer and dummy loads and hence, maintain the frequency of a MHPP constant. This replaces the expensive and complex speed governor. In this paper, the design and implementation of an ELC is presented. Magnetostrictive Amorphous Wire (MAW) is used as a frequency sensor. An amplifier and a signal conditioning circuit were designed to convert the analog signal from the MAW to a digital signal that is fed to microcontroller. In addition, optimal Proportional-Integral (PI) gains are determined to serve as reference gains to the microcontroller so as to generate a Pulse Width Modulation (PWM) signal to control the firing angle of the switching circuit of the ELC. The laboratory experimental test results obtained clearly show the effectiveness of the ELC to dump excess power to the damper load when the consumer load changes, and maintain the supply frequency between 49.5 and 50.5 Hz. Also, from the results, it was observed that the MAW sensor was able to measure the frequency effectively with high accuracy when compared to the frequency measurement from the tachometer. This is a key finding of the suitability of MAW sensor application in ELC for MHPPs. The designed controller is cheaper and yet able to control the frequency very effectively when compared to other ELCs and speed governors that are currently on the market. • The measured frequency using the MAW sensor compares well with that obtained using a digital tachometer: This is a key finding or novelty in this paper since the application of MAW sensor for frequency measurement in ELCs for MHPPs has not been reported in literature. • The designed ELC is effective to dump excess power to the damper load when the consumer load is less than the generator capacity. • The stabilising time for the designed ELC (obtained by using a timer) is 1.5 seconds. • The designed ELC is cheaper when compared to other ELCs and speed governors that are currently on the market. [ABSTRACT FROM AUTHOR]

Abstract This paper proposes an active bus voltage limiter with a modified modulation strategy for bi-directional power flow applications. When the motor is braking, the regenerative energy raises the DC bus voltage. Additional shunt resistors are usually used to dissipate the regenerative energy, which is a waste. The active rectifiers, which are also mentioned as PWM (Pulse Width Modulation) rectifiers, can transfer the regenerative power to the power grid but the cost is high and not economic, especially when the regenerative power is comparatively low. This paper investigates the zero-sequence current produced by the active bus voltage limiter and then presents a modified space vector modulation strategy to effectively suppress the zero-sequence current and keep the unity power factor. The analysis about the control strategy of the topology is carried out. And the algorithms for regenerative applications are discussed. An industrial prototype is built to verify the configuration. Highlights • The proposed limiter can transfer the regenerative energy to the power grids. • The model of the zero-sequence current generated in the applications is established. • A modified SVPWM is proposed and the zero-sequence currents are suppressed. • The strategy proposed can be further used when many inverters run in parallel. • An industrial prototype is built and has been used in elevators. [ABSTRACT FROM AUTHOR]

• The PSO algorithm is used to solve the switch angles of MMC staircase modulation which overcomes the problem that the switch angles are difficult to solve. • The precise mathematical model of MMC is established and the output waveform expression of staircase modulation is given and simplified. • iSHE-PWM (improved selective harmonic elimination pulse width modulation) method can increase the number of switching angles and minimize THD. Combined with PSO algorithm it can reduce the MMC output waveform THD and output voltage error. Modular multilevel converter (MMC) is the first topology choice for flexible DC transmission systems. This paper presents a particle swarm optimization (PSO) algorithm aided modulation method to calculate the improved selective harmonic elimination pulse width modulation (iSHE-PWM) switching angles with the aim of reducing the total harmonic distortion (THD) and output voltage error of MMC. The SHE-PWM has more controllable variables compared with the staircase modulation so that it can be used to improve the output current waveform quality. This method retains the advantages of easy to control and low frequency from the staircase modulation. But amplitude of its high-order harmonic is high and this paper improves it. Firstly the mathematical model of MMC is set up and corresponding expressions of THD and voltage error are given. The joint function of THD and voltage error is considered as the fitness function. The PSO algorithm was used to minimize the joint function for solving the optimal switching angles. Finally the proposed method is verified through simulation results showing its potential to successfully solve the problem of difficulty in obtaining the iSHE-PWM switching angles while minimizing the THD and output voltage error of the MMC. [ABSTRACT FROM AUTHOR]

Control of multi-phase machine in both healthy and post-fault operations has recently gained considerable interest. Finite control set model predictive control (FCS-MPC), in particular, has been proposed to drive multi-phase machines to avoid sophisticated pulse width modulation (PWM) methods. Nevertheless, FCS-MPC generally experiences some technical limitations. One of the widely reported challenges related to FCS-MPC is the weighting factor (WF) design, which is empirically designed and found to be an operating point dependent factor. Thus, assuming a constant WF can result in poor performance. In this paper, the prediction stage of FCS-MPC for asymmetrical six-phase (A6P) induction motor (IM) has been reformulated based on double dq (2dq) modeling approach. Unlike the reported vector space decomposing (VSD)-based FCS-MPC algorithms, the proposed approach results in four control variables (the stator sequence currents i s α 1 , i s β 1 , i s α 2 , and i s β 2 ) which have the same priority. Thus, equal weighting factors could be used in the cost function, which will inherently minimize the effect of the circulating x-y current components. Performance comparison of the proposed method against VSD-based FCS-MPC is investigated. The theoretical findings are experimentally validated using a 1 kW prototype six-phase IM. [ABSTRACT FROM AUTHOR]

In recent years, the energy crisis has prompted widespread attention to electric vehicles (EVs). As a core component of electric drive system in EV, motor controller has a significant impact on vehicle energy consumption. In such situation, this paper proposes a minimum loss modulation method for all power factors and reduces current THD by dead-band compensation. Firstly, the mechanism model of the controller is established for loss calculation, and the relationship between the clamping region and the current peak is analyzed based on the traditional modulation methods. Secondly, a discontinuous pulse width modulation considering power factor angle method (CPFA-DPWM) is proposed to ensure that clamping region always falls at the peak current at all power factors. Furthermore, the adoption of current vector method instead of direct sampling for current polarity determination effectively reduces judgment error and avoids false dead-band compensation. The effectiveness of the proposed method is verified by simulation and thermal measurement experiment. Under China Light-duty Vehicle Test Cycle (CLTC), the controller loss of CPFA-DPWM is reduced by 18.61 % compared to SVPWM. • A general distribution law of clamping intervals in DPWM methods is summarized. • A discontinuous modulation method is proposed to reduce the motor controller losses at arbitrary power factors. • In dead band compensation, the current vector method is used to improve the accuracy of the current polarity judgement. • The CPFA-DPWM can reduce the motor controller loss by 18.61 % under CLTC. • MATLAB/Simulink & PLECS and bench test platform were carried out to verify the proposed control strategy. [ABSTRACT FROM AUTHOR]

This paper presents a control method for modular multilevel converters (MMCs) as an interface between renewable energy sources and the grid. With growing penetration of renewable energy sources in the power grid, the developments in converter technologies and controller designs become more prominent. In this regard, dynamic and steady state analysis of the proposed model for an MMC use in a renewable energy based power system are provided through dc, 1st, and 2nd harmonic models of the converter in dq reference frame. This detailed configuration is then used to accomplish converter modulation and controller design. The first novel contribution of this control method is to provide an accurate pulse width modulation (PWM) strategy based on network and converter parameters, in order to achieve a stable operation for the interfaced MMC during connection of renewable energy sources into the power grid. In addition, the proposed method is able to mitigate the converter circulating current by inserting a second harmonic reference in the modulation process of the MMC, which is the second contribution this paper provides over other control techniques. A capacitor voltage balancing algorithm is also included in this control method to adjust each sub-module (SM) voltage within an acceptable range. Finally, converter’s maximum stable operation range is determined based on the dynamic equations of the proposed model. The functionality of the proposed control method is demonstrated by detailed mathematical analysis and comprehensive simulations with MATLAB/Simulink. [ABSTRACT FROM AUTHOR]

This paper proposes a sensor fault tolerant control (FTC) strategy for electronically-coupled distributed energy resource (DER) units in grid-connected microgrid systems. First, a fault dependent dynamical model of the DER unit incorporating sensor faults is proposed. The FTC strategy is then developed using a sliding mode observer (SMO) which has an inherent robustness property. The rational for using a SMO is the need to detect and reconstruct any fault that may occur in output measurements of the system as a result of sensor failure. The fault signals are reconstructed by using a robust approach that encompasses uncertainties in the system, such as frequency variation. This paper also represents the cyber attack as an unknown sensor fault, and consequently the DER current sensor measurements manipulated by a data integrity attack can be detected and reconstructed. The reconstructed fault signals are then used to modify the faulty sensor measurements, which are fed to the voltage source converter (VSC) controller. This ensures accurate generation of pulse width modulation (PWM) signals and consequently accurate tracking of real and reactive power references. Different case studies are tested on a detailed nonlinear model of the DER system. The impact of faults on the DER performance and the effectiveness of the proposed FTC scheme are evaluated through extensive simulation studies. Experimental verification of the method is provided to further validate the proposed approach. [ABSTRACT FROM AUTHOR]

Owing to rapid depletion of fossil fuels and environmental hazard, different non-conventional sources of energy like wind, geothermal, nuclear, photovoltaic etc, have been taken into consideration for power generation. Environmental familiarness, reduced installation cost, improved power quality, abundant availability of source makes photovoltaic based distributed generation as one of the most popular alternative source of energy production. Improvement in power electronics technology makes synchronization of PV system with grid more viable. Power output from the PV module changes continuously with time depending upon the climatic condition. In order to get maximum output from the PV system different types of MPPT algorithm present in literature are studied and improvement proposed are described in this paper. Furthermore, different types of inverter topologies along with different grid synchronization technique and PWM topologies used to connect the PV system with the 3-phase AC grid are presented. In order to minimize the harmonic content of the inverter output, different types of filters used are presented in the proceeding section. Nextly different commonly used advanced islanding detection techniques for the safety purpose of PV based distribution generation system have been addressed and based on advantages and limitation of anti-islanding techniques, a comparison table has been presented. Afterward based on parameters like input, output voltage & current, MPP range, used standards etc, a comparison table between different commercially available grid tied PV inverters are presented in this paper. Finally, drawbacks of the prevailing grid connected PV system have been discussed. [ABSTRACT FROM AUTHOR]

• An innovative quaternary hybrid light modulation (QHLM) based projection display is proposed. • A quaternary spatial light modulator is constructed by illuminating two parallel digital micro-mirror devices (DMDs) with different light intensities. • The quaternary digit-plane decomposition and the pixel-level alignment of two DMDs are realized. • The prototype is designed and implemented to verify that the QHLM can achieve 16-bit projection at 220 fps. Conventional spatial light modulators (SLM) can only be used for projecting 8-bit or 10-bit images at normal frame rate. Therefore, commercial high dynamic range (HDR) displays typically focus on boosting the contrast while neglecting to raise the bit-depth. Existing methods for high bit-depth display generally rely on stacking two SLMs to modulate the outgoing beam twice, namely multiplicative modulation, resulting in many troubles such as low optical efficiency, difficulty in pixel-level alignment, and complex image rendering algorithm. In this paper, an innovative quaternary hybrid light modulation (QHLM) based projection display is proposed and realized. By illuminating two parallel digital micro-mirror devices (DMDs) with different light intensities, the quaternary digit-planes (QDs) with four gray levels are able to be modulated rapidly. Aiming at this ability, the quaternary pulse width modulation (QPWM) is incorporated with the quaternary light-intensity modulation (QLM) to fundamentally improve the modulation efficiency compared to the binary light modulation mode. Furthermore, the quaternary digit-plane decomposition (QDD) based image splitting algorithm is adopted to split a high bit-depth image into two images that drive two DMDs respectively. The prototype is designed and built to verify the feasibility of the QHLM based projection display. The experimental results demonstrate that the prototype can project 16-bit images at 220 fps. Through additive modulation of two DMDs in parallel, the QHLM entirely avoids the drawbacks of multiplicative modulation. As a completely different technology, the QHLM has a great potential for HDR projection applications. [ABSTRACT FROM AUTHOR]

• A power-decoupled current source inverter (PD-CSI) is proposed for the operation in an unbalanced grid to reduce the current rating of the DC-link inductor. • A model predictive control is proposed for the PD-CSI. It achieves high performance in both stability and rapidity. • A space vector pulse width modulation is proposed for the PD-CSI. It helps to reduce the voltage rating of the ripple storage capacitor. The current source inverter (CSI) is a promising interface between the Photovoltaic (PV) panel and the three-phase AC grid. It boosts the PV panel voltage by a DC-link inductor and converts the maximum available PV power. In an unbalanced grid, double-line-frequency pulsating powers will be generated in the CSI, increasing the rating of the DC-link inductor and impeding the maximum power point tracking (MPPT) operation. To address this issue, a power decoupling (PD) circuit for a three-phase CSI is proposed in this paper. By using the DC-link inductor and active switches multiplex, the proposed PD circuit can reduce the current rating of the DC-link inductor with fewer active switches, and no detrimental power components are introduced to the utility grid. Moreover, to concurrently control multiple objectives without multiple loops, a model predictive control (MPC) method is further proposed for the PD-CSI, achieving a rapid response of PD-CSI. Besides, a space vector pulse width modulation (SVPWM) method is proposed for the PD-CSI to enhance the utilization of DC voltage, helping to reduce the voltage stress of the ripple storage capacitor. The priorities of the proposed topology and the corresponding control and modulation methods are finally verified by comparative experimental results. [ABSTRACT FROM AUTHOR]

Worldwide increasing energy demands promote development of environment-friendly energy sources. As consequences, ocean wave is exploited as an ideal energy source to mitigate greenhouse gas emissions. In this paper, a hydraulic energy-storage wave energy conversion system is constructed, and a mathematical model of main components is built for analysis. Control strategies of generator-side and grid-side are defined for the system, where a Vienna rectifier is applied to converter of generator-side. A two-level space vector plane simplified modulation method for Vienna rectifier is designed for the three-level system and a modulation algorithm is detailed, which has lower complexity compared with traditional three-level space vector pulse width modulation (SVPWM) algorithm. An improved adjusting factor method is proposed to solve the potential imbalance of neutral point caused by uneven charging to the upper and lower capacitors in the three-level structure, which optimizes sector division and inhibits the neutral-point potential offset and fluctuation effectively. Using Matlab/Simulink, the intermittent and continuous power conversion modes of the system under different wave conditions are simulated. The results indicate stable operation of the system, feasible topology scheme, modulation algorithm and control strategy, and effective suppression of AC-side harmonics. [ABSTRACT FROM AUTHOR]

As a main driving force of electric vehicles (EVs), the losses of in-wheel permanent-magnet synchronous motor (PMSM) direct drive system can seriously affect the energy consumption of EVs. This paper proposes a loss optimization control strategy for in-wheel PMSM direct drive system of EVs which optimizes the losses of both the PMSM and the inverter. The proposed method adjusts the copper losses and iron losses by identifying the optimal flux-weakening current, which results in the PMSM achieving the lower losses in the whole operational range. Moreover there are strongly nonlinear characteristics for the power devices, this paper creates a nonlinear loss model for three-phase half-bridge inverters to obtain accurate inverter losses under space vector pulse width modulation (SVPWM). Based on the inverter loss model and double Fourier integral analysis theory, the PWM frequency is optimized by the control strategy in order to maximize the inverter efficiency without affecting the operational stability of the drive. The proposed loss optimization control strategy can quickly find the optimum flux-weakening current and PWM frequency, and as a result, significantly broaden the high efficiency area of the PMSM direct drive system. The effects of the aforementioned strategy are verified by both theoretical analysis and experimental results. [ABSTRACT FROM AUTHOR]

This paper analyzes the influence of the microwave pulse width on the thermal burnout effect of a PIN diode limiting-amplifying system. Based on theoretical analyses and simulation, the relationship of the burnout effect on a PIN diode limiter and a PIN diode limiting-amplifying system is obtained first. By adopting an absorption efficiency factor, the theoretical model of the relationship between the microwave pulse width and the burnout power threshold for the PIN diode limiting-amplifying system is obtained. The proposed theoretical formulas can be determined by using at least two sets of simulation or measurement results to fit the constant coefficients, which can greatly reduce the simulation or experimental costs. The results obtained by the theoretical formulas are in good agreement with the numerical simulation results obtained by our self-designed device–circuit joint simulator, which verifies the correction of the theoretical analyses and modeling. The available microwave pulse width range for the proposed theoretical formulas is from 10 ns to 10 μs. In consideration of the potential threat of microwave pulses, the system-level study results obtained in this paper will be helpful for the design of the radio frequency receivers. [ABSTRACT FROM AUTHOR]

This paper presents a space vector modulation (SVM) based Direct Torque Control strategy (DTC) for induction motor (IM) in order to overcome the drawbacks of the classical DTC. SVM can reduce the high torque and flux ripples by preserving a fixed switching frequency. This technique is known by the closed loop torque SVM-DTC. Moreover, the control scheme performance is improved by inserting a second order sliding mode super twisting controller in the outer loop for speed regulation. This nonlinear technique ensures a good dynamic and high robustness against external disturbance. Furthermore, the IM energy optimization is treated in the second objective of this paper. A proposed model based loss minimization strategy is presented for efficiency optimization. This strategy chooses an optimal flux magnitude for each applied load torque. The proposed optimized SVM-DTC algorithm will be investigated by simulation and real time implementation using Matlab/Simulink with real time interface based on dSpace 1104 signal card. [ABSTRACT FROM AUTHOR]

This paper describes the simulation and implementation of a generic FPGA-based PWM generator with automatic device fault recovery. This PWM generator is applied to multi-switch DC/DC boost converters for fuel cell applications; these converters have gained attention due to its reliability, equally-distributed power losses and reduced part count. In this paper, three different driving schemes for one phase and different legs are described and one driving scheme has been finally chosen. The operation of the proposed PWM generator with simulations and experimental results are shown. This PWM generator with automatic fault recovery, brings more reliability and fault robustness to fuel cell boost converters, making suitable to use in electric vehicle and uninterruptible power supplies (UPS). The method used in the PWM generator described on this paper, allows to change the number of devices working in DC/DC conversion, increasing the switching frequency and the duty cycle of the power switches, ensuring a DC/DC conversion without interruption. [ABSTRACT FROM AUTHOR]

To increase the reliability of motor drive system, many fault diagnosis approaches have been reported with regard to three-phase Pulse Width Modulation Voltage Source Inverter (PWM-VSI). Based on feature engineering and deep neural network, this paper proposes a fault diagnosis approach for the VSI in three-phase Permanent-magnet Synchronous Motor (PMSM) drive. The three-phase current signals are used for the fault diagnosis of VSI. 10 typical signal features are extracted from the three-phase current signals and used as the input of deep neural network. To improve the diagnostic performance, the network structure of the presented deep neural network is designed like a pyramid. Experimental results show that the presented method can detect not only the single open-circuit faults but also the double open-circuit faults in power switches, with high diagnostic accuracy (more than 95%). Besides, comparison results show that the presented method has strong generalization performance. This paper provides theoretical guidance for the fault diagnosis of VSI in PMSM. [ABSTRACT FROM AUTHOR]

The paper describes various modified algorithms of classical sinusoidal pulse width modulation (PWM) serving for a three-phase two-level inverter control. The paper presents the results of a research of 3 PWM versions with varying duty cycle parameters and frequency of the pulse signal modulation. The method is to divide the modulated sinusoidal signal cycle (half-cycle) into intervals in order to change the modulation frequency within the separate sectors of forming the quasi-sinusoidal output voltage waves. In addition, algorithmic ways to compensate the additional losses in the inverter and the induction motor at high modulation frequencies of a discrete control signal are investigated and described in the paper. Calculations and simulations are performed by NI Multisim simulation program and NI LabVIEW visual programming environment. Theoretical studies are performed using the electric drive theories, discrete control systems and spectral analysis. The practical implementation performed by Texas Instruments Stellaris Launchpad using the Energia prototyping platform, field-programmable gate arrays (FPGA) of National Instruments CompactRIO-9074 and NI Single-Board RIO GPIC (sbRIO-9606, NI 9683 (GPIC), LX45 FPGA) using NI LabVIEW software and add-on modules (LabVIEW Real Time, LabVIEW FPGA). The suggested inverter control methods make it possible to reduce the distortion of the output quasi-sinusoidal signal and reduce the power consumption of the DC link while significantly reducing the number of inverter transistor switching in comparison with the classical method without premodulation or technical devices (filter-compensating devices). [ABSTRACT FROM AUTHOR]

This paper presents the modeling and controlling the power of Quasi Z-Source cascaded H-bridge multilevel inverter for grid connected photovoltaic systems. The Quasi Z-Source inverter is an inverter that provides buck / boost output along with DC-AC conversion in a single stage. This topology has numerous advantages which makes it reliable and suitable for PV applications. Due to the impedance network and the cascaded H-bridge structure, it provides high gain, reduced total harmonic distortion (THD) and high reliability in PV systems. In this paper, a five level cascaded H-Bridge Quasi Z-source inverter has been considered for which the impedance network has been designed. Phase Shifted Inverted Sine carrier pulse width modulation has been implemented along with shoot- through control for controlling the switches of the inverter. The closed loop power control scheme has been implemented in two stages. In the PV input side, each string voltage is controlled by adjusting the shoot-through states of the inverter using Independent Maximum Power Point Tracking Control. DC link voltage of each bridge has been balanced by using DC link voltage control. Both of these controlling actions result in the control of grid injected power. A 2kVA PV inverter has been designed and built using MATLAB/SIMULINK and the hardware has been completed for the open loop control. The simulation and open loop hardware results are discussed. [ABSTRACT FROM AUTHOR]

This paper introduces a new HT-type module for both symmetrical and asymmetrical multilevel inverters (MLIs) with reduced power electric components. The proposed module comprises of two back to back T-type inverters connected with four cross-connected switches. This MLI addresses two major drawbacks associated with the conventional and other recently proposed MLIs which are the high voltage stress of switches and higher power component counts. The structure of the proposed device is designed combining the beneficial features of both T-type inverter and cross-switched inverter. The 1st feature allows the module to produce negative voltage levels deprived of any extra H-bridge circuit and thus decreasing the overall voltage stress significantly. The latter feature allows the device to utilize reduced number of switches to produce higher voltage levels. A comprehensive comparative analysis is additionally established between other MLI topologies to confirm the superiority of the HT-type MLI. From this analysis, it is found that the proposed MLI has successfully overcome the issues associated with other MLIs, it was able to produce the results following industrial standards and it outperformed other MLIs in different aspects such as power components count, cost, efficiency and dynamic performance. Selective harmonic elimination pulse width modulation (SHE-PWM) and nearest level control (NLC) algorithm is considered in this manuscript to generate the output results from the proposed HT-type module. All the details about the operating principle and modulation techniques utilized for the proposed MLI module are stated and validated by both simulation and experimental results. [ABSTRACT FROM AUTHOR]

Due to the difficult topography and bad weather conditions across large distances, dc line breakdown is a serious danger to the safety of high-voltage direct-current systems (HVDC). Thus, there is a need of an accurate and reliable fault location method to safely isolate the dc grid in the occurrence of a dc fault. Traveling wave (TW) fault location techniques have gained in popularity over the decades, with the expectation that power networks will become considerably more credible and accurate throughout. However, in the existing traveling wave based location, the signal processing methodology for extracting the wave front consumes too many computer resources, necessitating the development of a new location method with a fast response and high accuracy. In this paper, a new algorithm of TW based on high pass filter is proposed, it can differentiate the TW peak more easily by removing the oscillation in a signal. To ensure more accuracy double ended method (Type D) is used to obtain the location for the fault. The theory behind this new algorithm is presented in detail. High pass filter is designed for this purpose and its validity tested on point to point (P2P) dc simulation model which is created in PSCAD software to gather the voltage data from both terminals during transient. Following that the proposed fault location algorithm is executed in the MATLAB environment to get the fault location results. A comparison of the proposed algorithm with two popular methods namely the wavelet transforms (WT) and the single ended method highlights the superiority. • A high pass filter based traveling wave extraction method is firstly applied for fault localization. • A P2P system is built in PSCAD for location estimation under different fault conditions. • In comparison with other methods, the proposed one is fast, accurate and robust. [ABSTRACT FROM AUTHOR]

• Developed a nonlinear model of droop-controlled sources, established a system-level model of direct current microgrids. • Proposed a low-conservation constrained region of attraction-based stability analysis method. • Those new achievements are verified by case studies and have been proved to be effective in expanding the existing knowledge base. Large-signal stability of direct current (DC) microgrids (MGs) are required to be seriously considered when more power converters are penetrated. For DC MGs suffering from large disturbances, the power electronics at both source and load sides are operated within the voltage and current limits to ensure the stability and safety. However, no existing methods have been developed to address the non-conservative stability analysis of a DC MGs with physical variable constraints. To this end, a comprehensive is developed in this paper to analyze the large-signal stability of typical DC MGs with voltage/current and pulse-width modulation duty cycle constraints, with a low level of conservatism. First, the system-level model of a DC MG is established as the basis of stability analysis. Then, a workflow based on the Lyapunov theory and numerical integration is developed to evaluate the large signal stability with physical variable constraints. The developed stability analysis method has less conservatism than the existing methods with only one moderate computational cost. The effectiveness of the proposed strategy is validated by case studies based on a single-bus direct current microgrid. [ABSTRACT FROM AUTHOR]

• The proposed space vector modulation (SVM) method for active power decoupling quasi-Z-source inverter (APD-qZSI) is easy to implement. • Compared with the SPWM, the proposed SVM method has smaller storage capacitance and a wider normal operation range. • The APD method under the proposed SVM method is effective for suppressing the 2ω ripple power and reducing the qZS inductance and capacitance. The double-line frequency ripple power of the single-phase quasi-Z source inverter (qZSI) will result in a large designed qZS impedance on the dc side, which can be greatly reduced by the coupled-type active power decoupling (APD) method. However, the traditional sinusoidal pulse width modulation (SPWM) for the APD-qZSI needs extravagant APD storage capacitance and may cause abnormal operation under low load conditions. Classical space vector modulation (SVM) has higher flexibility and dc-link voltage utilization, but it cannot be directly applied to the APD-qZSI. In this paper, a simplified SVM method for the coupled-type APD-qZSI is proposed, where the switching time sequence is transformed to carrier-based pulse width modulation, so the shoot-through control of the qZSI is easy to implement. Next, the passive component parameters and normal operation range of the traditional SPWM and the proposed SVM are analyzed and compared. The proposed SVM has a smaller APD storage capacitance but a slightly larger ac side filter inductance. In addition, the decreased current of the APD branch under SVM can help suppress the abnormal operation of the inverter, so the APD-qZSI can operate at a lower load condition. Finally, experimental results validate the effectiveness and superiority of the proposed SVM method. [ABSTRACT FROM AUTHOR]

Linear switched impulsive systems (SIS) are characterized by ordinary differential equations as modes dynamics and state jumps at the switching time instants. The presence of possible jumps in the state makes nontrivial the application of classical averaging techniques. In this paper we consider SIS with pulse width modulation (PWM) and we propose an averaged model whose solution approximates the moving average of the SIS solution with an error which decreases with the multiple of the switching period and by decreasing the PWM period. The averaging result requires milder assumptions on the system matrices with respect to those needed by the previous averaging techniques for SIS. The interest of the proposed model is strengthened by the fact that it reduces to the classical averaged model for PWM systems when there are no jumps in the state. The theoretical results are verified through simulations obtained by considering a switched capacitor electrical circuit. [ABSTRACT FROM AUTHOR]

This paper proposes a double source double diode double switch (DSDDDS) multilevel inverter to generate positive voltage and a connecting polarity changing circuit of an H-bridge inverter to generate negative voltage. By connecting the jth number of basic units in series, the desired level is obtained. Various algorithms, such as Natural, Binary, Trinary, and Quasi-Linear sequences, and two proposed algorithms are discussed to determine the magnitude of DC voltage sources in order to generate more stepped levels with fewer switches. The proposed multilevel inverter eliminates the need to turn on additional power switches for different levels, which is the main advantages of this topology. The proposed multilevel inverter is compared to conventional switched diode multilevel inverters in terms of switch count, number of ON state switches per level, driver circuits, and total standing voltage. Real-time results from the OPAL-RT test bench and simulation have validated the proposed inverter. [ABSTRACT FROM AUTHOR]

The paper considers recent trends in the development of electrically operated hydraulic drive. The main requirements to the dynamic characteristics of variable axial piston pumps with electric control and the need for search of ways of their improvement are specified. The investigation results show the dynamic characteristics of the process to control electro-hydraulic axial piston pump capacity at different parameters of pulse width modulation (PWM) signal. The regularity between PWM-signal frequency and the time of establishing the proper pump displacement was found. The paper stresses the need for more detailed study of this fact and its usage for the optimization of variable pump regulation speed in order to be applied in electro-hydraulic flow control systems. [ABSTRACT FROM AUTHOR]

• A unique series compensation strategy has been implemented in PV-wind system to mitigate stator harmonics produced by switching at the rotor side, dependent on rotor speed. Also, at low wind speeds and wider voltage variations, it supplies voltage to cater to the demand of the grid. • The SHEPWM technique has been employed for various switching strategies to control a wider range of harmonics injected with a minimum number of switching pulses, used online using the piecewise mixed model. This is achieved using just three triggering angles, which give equivalently good results as seven switches, hence with reduced switching losses and higher efficiency. The minimum possible THD was found to be 1.8% using the recent Search and Rescue (SAR) based optimization technique, which is within the suggested international standards such as IEEE 1547, IEC, and CIGRE WG 36-05. • A laboratory prototype has also been made to investigate the simulations whose results were found out to be satisfactory justifies its applications for the practical purposes. This paper provides a framework for a PV-DFIG-based microgrid-connected system to eliminate lower-order harmonics and optimise higher-order harmonics. Also, at low wind speeds and wider voltage variations, it supplies voltage to cater to the demand of the grid. A unique series compensation strategy has been implemented to mitigate stator harmonics produced by switching at the rotor side, dependent on rotor speed. The SHEPWM technique has been employed for various switching strategies to control a wider range of harmonics injected with a minimum number of switching pulses, used online using the piecewise mixed model. This is achieved using just three triggering angles, which gives equivalently good results as seven switches, hence with reduced switching losses and higher efficiency. So, the SHEPWM technique has been utilised to control these harmonics using the least number of switches per cycle. Various search-based optimization techniques have been compared to determine the best performance for the problem statement, and the minimum possible THD was found to be 1.8% using the recent Search and Rescue (SAR) based optimization technique, which is within the suggested international standards such as IEEE 1547, IEC, and CIGRE WG 36-05. A comparative analysis has been carried out with different literature and it was found that the SAR-based SHEPWM gives better results when undergoing proposed series compensation in order to achieve the objective of the present paper. A laboratory prototype has also been made to investigate the simulations whose results were found to be satisfactory. [ABSTRACT FROM AUTHOR]

This paper presents fast test protocols for ageing IGBT modules in power cycling conditions, and a monitoring device that tracks the on-state voltage V CE and junction temperature T J of IGBTs during ageing test operations. This device is implemented in an ageing test bench described in previous papers, but which has since been modified to perform fast power cycling tests. The fast test protocols described here use the thermal variations imposed on IGBT modules by a test bench operating under Pulse Width Modulation conditions. This test bench reaches the maximal values of power cycling frequencies attainable with a given module packaging in order to optimize test duration. The measurement device monitors V CE throughout the ageing test that is needed to detect possible degradations of wire bonds and/or emitter metallization. This requires identifying small V CE variations (a few dozen mV). In addition, the thermal swing amplitude of power cycling must be adjusted to achieve a given ageing protocol. This requires measuring junction temperature evolution on a power cycle, which is carried out by means of V CE measurement at a low current level (100 mA). Experimental results demonstrate the flexibility of this test bench with respect to various power cycling conditions, as well as the feasibility of the proposed on-line monitoring methods. [ABSTRACT FROM AUTHOR]

• An asymmetrical multilevel inverter with reduced number of components is proposed. • Cascaded operation with binary based isolated sources generates higher output level. • Boost converters regulates the voltages from PV panels using voltage feedback control. • Low switching frequency modulation helps to reduce harmonics and switching losses. In this paper, a new basic structure of asymmetrical multilevel inverter with optimum number of components for photovoltaic (PV) renewable energy system is proposed. The aim is to reduce the number of components required to achieve a high number of output levels compared to older topologies. The inverter configuration comprises of two basic units connected to a packed H-Bridge. Cascaded operation of the inverter configuration is feasible for higher level generation. The magnitudes of the DC sources are selected in binary sequence to maximize the number of output levels. Solar panels with proportional-integral (PI) controlled DC-DC converters are used as the DC sources. The switch modulations are achieved by pre-defined switching angles which are calculated to minimize total harmonic distortion (THD) in the AC output waveforms. This method is used instead of the classic pulse width modulation (PWM) technique to reduce the total switching loss and the required processing power in generating the switching signals. Compared to the conventional multilevel inverter topologies, the proposed inverter is a better choice in terms of the number of components. It also achieves a good balance between the number of components and total blocking voltage. Hence, its installation will require smaller space and cost. Another merit of the proposed topology is that it produces AC output with low THD at high efficiency. The efficacy of the proposed asymmetrical 31-level inverter topology is simulated using MATLAB/Simulink and is further verified through experimental analysis. [ABSTRACT FROM AUTHOR]

In this paper the Selective Harmonic Elimination Pulse Width Modulation (SHE-PWM) technique with considering controllable DC link voltages is implemented in the cascaded multilevel inverter. The novelty of this work is the method of mathematical modelling of SHE-PWM with respect to variable voltage of DC links. With respect to variable voltage of DC links, the number of degrees of freedom are increased compared to ordinary SHE techniques with constant voltage of DC links. One of the issues in SHE-PWM technique is solution of nonlinear equations under various operating conditions of the converter. In the proposed formulation, the resulted nonlinear equations are solved only one time for entire reachable range of output voltage amplitude, which leads to considerable reduction of computational burden. Also, the THD of output voltage waveform remains constant at minimum value for different operating points. The theoretical results of proposed technique are verified by the simulation and scale-down experimental setup of a cascaded 7-level inverter. [ABSTRACT FROM AUTHOR]

• Applying a simple passive snubber and clamp circuit. • Providing soft switching condition for all semiconductor elements. • The suggested passive snubber is load independent. • Reaching high efficiency (92% at full load) and high gain (23.2). • Simple control strategy. • Suitable to apply as an interface circuit between DC link and loads in PV applications. This paper introduces a soft switching full bridge interleaved Flyback DC-DC converter with high gain. Half bridge Flyback converter will cause many problems in comparison with full bridge structure such as high-volume split capacitors and complex control for charging and discharging them for proper operation. By applying full bridge interleaved structure, the output current ripple can be reduced, and more power can be supplied to the load. Besides, the greatest way for reducing the weight, size and volume of the converter is applying soft switching methods. As well, the switching frequency is increased to boost the power density. To reduce switching losses, clamp circuit with a passive lossless snubber is applied in the suggested full bridge interleaved Flyback converter. In the proposed topology, soft switching conditions for all semiconductor elements are achieved by the passive snubber. It absorbs the stored energy in parasitic elements at the turn-off instant. The main superiority of the proposed topology in comparison with many other similar converters is that its passive snubber is load independent. A 110 W prototype of the topology is implemented. The experimental results confirm the aforementioned advantages of the converter such as high efficiency (92% at full load) and high gain (23.2). [ABSTRACT FROM AUTHOR]

A novel technique to control the speed of BLDC motor and to maintain the power quality fed directly from the grid using a single stage Direct Matrix Converter (DMC) instead of using back to back converters is presented in this paper. The main advantage of using the DMC is the reduction of switches at the converter stage to nine as compared to twelve in case of back to back converters and hence results in a reduction of losses. Also, the system becomes robust with the removal of the bulky dc-link storage capacitor and provides all silicon solution to the controller part of the motor. The use of SVM at the grid side of the converter gives an improved input power factor with low distortion. The indirect modulation method of matrix converter gives the flexibility to apply closed-loop hysteresis current control at the load side of the converter for efficient speed control of the motor. The simulation results verify the efficiency and effectiveness of the proposed technique carried out in MATLAB/Simulink platform. [ABSTRACT FROM AUTHOR]

• Design of flying capacitors. • Multilevel inverters with flying capacitors. • A comparative analysis of the design of flying capacitors. This paper presents a methodology for the design of flying capacitors for multilevel inverters. It is based on the harmonic representation of the switching functions, so that it is possible to design the flying capacitors for different operation points. Experimental results are provided to verify the presented analysis. The proposed methodology is developed for the five-level Flying Capacitor Converter and for the five-level Stacked Multicell Converter, but it can be expanded for both types of converter with a higher number of output voltage levels or for other topologies. [ABSTRACT FROM AUTHOR]

• Sensorless control method to establish a DC-link voltage. • Removal of the outer control loop to reduce the inverter control complexity. • Modelling and control of the grid-connected inverter. • Implementation of incremental conductance based MPPT algorithm to search an operating point for the boost converter. In this paper, a novel control approach for a grid-connected photovoltaic system (GCPVS) has been proposed. This novel approach introduces a sensorless DC-link voltage control for two-stage three-phase GCPVS. The two-stage system with the proposed control approach includes an intermediate (DC-DC boost) converter and pulse width modulation (PWM) strategy based voltage source inverter (VSI). In the first-stage control, the intermediate converter is incorporated with the maximum power point tracking (MPPT) technique. The incremental conductance MPPT technique is implemented to enhance the voltage level of the PV array under variable irradiance condition. Further, the second-stage control of VSI deals with DC-link voltage regulation (outer-loop) and current control (inner-loop) matching with the conventional scheme. Distinctively, the proposed scheme avoids the outer-loop and controls the inner-loop. Hence, the reduction of DC-link high voltage sensor minimizes the cost as well as the size of the system. However, the DC-link voltage will remain maintained through the power balancing. Hence, the removal of the outer-loop controller enhances the system stability and the dynamic response of the system under variable irradiance conditions. The proposed GCPVS is simulated in MATLAB/Simulink using sim power tools to verify the system performance and the dynamic behaviour at different irradiance levels of the system. [ABSTRACT FROM AUTHOR]

Using variable blank holding force, which is conventionally achieved by hydraulic or mechanical drive, can effectively reduce defects in the forming process. To overcome the obstacles of low response and high complexity of conventional drives, this paper proposes a holding system for variable blank holding force driven by the electro-permanent magnet. Focusing on the variable electromagnetic force, a control method based on grading voltage pulse width modulation and mode matching is addressed. The model of the transient electromagnetic force is first established, the relationship between electromagnetic force and current is obtained, and the migration law of the working point of the magnet with the change of current is analyzed. Then, the grading voltage pulse width modulation control, which regulates current by the pulse width and its amplitude, is developed for continuously increasing or decreasing force control. When force variations occur, mode matching is introduced to identify the working point and allocate matching parameters for better control. To validate the feasibility of the control method, the co-simulation based on Simulink-Simplorer-Maxwell and the experiment bench are built. Results of electromagnetic force show that the step response time is 0.13 s and the mean relative error is less than 1% for a given variable blanking force. The control method can reduce the thickness variations of sheet metal by 14–20% compared to the existing electro-permanent magnet blank holder. This work assists in realizing the loading of variable blank holding force driven by electromagnetics to improve the forming quality of parts. [Display omitted] • Transient model was built for the electromagnetic blank holding system. • Grading voltage PWM control was developed for quickly tracking of the system. • Mode matching was introduced for accurate control of the system. • Response and accuracy of the system was validated by experiments. • Better forming quality was revealed compared with the existing control. [ABSTRACT FROM AUTHOR]

In this paper, it is a kind of challenge to simplify the conventional pulse width modulation (PWM) algorithms for a three-level neutral-point-clamped inverter. Thus, the unified duty-cycle modulation (UDM) algorithm is presented. It is more attractive than the carrier-based PWM (CBPWM), space-vector PWM (SVPWM), and unified PWM algorithms with a simpler calculation by utilizing the usefulness of the SVPWM algorithm to synthesize the duty cycles in time-domain and the CBPWM algorithm to synthesize the duty cycles in frequency-domain with the lesser conditions and the blankness of the lookup tables, switching sequence design, and zero-sequence component finding. Besides, it is outstanding with three outcomes: (1) comprehensive mathematical models of the dwell times, (2) permanent mathematical models of the duty cycles in time-domain, and (3) simplified PWM algorithm, which has a better workflow with the reduction of the computation burden. As it is very easy to implement as the sinusoidal PWM technique while its performance is equivalent to the SVPWM algorithm, this makes the proposed UDM algorithm a good candidate to optimize between the performance and the cost. Both the simulation and experimental results can confirm the feasible practicability and performance. The comparison with the conventional algorithms can evidently emphasize the superiority. [ABSTRACT FROM AUTHOR]

Pulse-width modulation has the advantages of fast projection speed and high precision. However, when it is used to measure the three-dimensional (3D) shape of complex surfaces, it suffers from harmonic interference caused by slight defocusing and is sensitive to pixel oversaturation. To achieve high-speed and accurate 3D measurement of complex surfaces using this method, in this paper, a complementary double pulse-width-modulation (CDPWM) is proposed and used to generate ideal phase-shift fringe patterns. In our method, a triangular carrier signal with a zero phase is first used to generate a set of double pulse-width-modulation (DPWM) patterns, and then a triangular carrier signal with a phase of π / 2 is used to generate another set of DPWM patterns. Then, the CDPWM is obtained by fusing these two sets of DPWM patterns. We demonstrate that CDPWM can tremendously suppress harmonic interference so that in practical applications, a smaller defocus can be used to robustly reconstruct complex surfaces. Moreover, it is proved that the patterns corresponding to the π / 2 phase are the compensation patterns of the patterns corresponding to the zero phase, which enables CDPWM to eliminate or reduce the pixel oversaturation effect caused by a surface with a high dynamic range. Through experiments on simulated and real data, the proposed method is shown to substantially improve the phase quality and measurement accuracy over a wide range of fringe periods (e.g., from 18 to 912 pixels), especially when the defocus level is low. Different camera exposure times are used to demonstrate the robustness of the proposed method to oversaturated pixels. Furthermore, we measured a set of ice surfaces and a metal surface containing both low- and high-reflection areas. The projector was set to a slight defocus, which better preserved the binary characteristics of the patterns it projected. The measurement results proved our method can significantly improve the measurement accuracy of surfaces with complex reflection characteristics. • A complementary double pulse-width-modulation (CDPWM) is proposed. • CDPWM has a strong ability to eliminate high-order harmonics. • CDPWM can realize HDR surface 3D measurement. • Extensive and diverse experiments show that our method has obvious advantages. [ABSTRACT FROM AUTHOR]

The radio frequency spectrum, which has been steadily getting smaller, is under pressure from growing cellular data traffic. A more dependable communication channel is required. To setup the communication medium, VLC uses LED illumination. In order to increase network throughput, the goal of this study is to analyze and model signal conditioning techniques in the visible spectrum. VLC technology offers synchronized illumination of LED lamps as well as wireless broadband connectivity. Using the real-valued O-OFDM baseband signal, optical orthogonal frequency division multiplexing (O-OFDM) offers a viable modulation option for very-low-bit-rate (VLC) systems to modulate the optical carrier's instantaneous power to attain gigabit data rates. However, one important design difficulty preventing VLC from being commercialized is how to combine industry-favored pulse width modulation (PWM) dimming technology while retaining a dependable, broadband connection. In this paper, Reverse Polarity optical orthogonal frequency division multiplexing (RPO-OFDM) is proposed as a new signal format for combining the fast O-OFDM contact signal with the comparatively slow PWM dimming signal, as both signals contribute to the illuminative brightness of the LED. The average SNR, additional testing demonstrates that the suggested method outperforms the Asymmetrically clipped optical OFDM (ACO), Optimized Flipped Optical (OFO) and DC biased optical OFDM (DCO), and algorithms in similar operating conditions. [ABSTRACT FROM AUTHOR]

This paper presents the unique design and processing conditions of a micro-CAES device that generates, stores and delivers electrical energy with highly efficient total energy conversion. The micro-CAES installation is divided into six parts, where air, the energy carrier, is compressed, stored, heated and expanded in appropriate sections. We focus mainly on the post-preparation section, where the air mass flow is pulse heated and controlled by Pulse Width Modulation (PWM), and the expansion section, where multiple piston drives are used to achieve maximum energy conversion efficiency or the required amount of electricity to be fed into the grid. We discover that the controllability of expansion process performance is improved by exploiting the inertia of the following elements in multiple reciprocating engines: piston, piston rod, connecting rod, crank, and crankshaft, connected with air injection dynamics and pulse heating by Thermal Energy Storage (TES). Furthermore, we investigate the efficiency using our own zero-dimensional mathematical model illustrating the complex dynamics of air processing. The mathematical model was compared with experimental data for the single-drive air expander, showing qualitatively and quantitatively satisfying model reliability. Moreover, we performed a sensitivity analysis to determine the best number of reciprocating drives involved in the expansion section and the best operating conditions. The use of the PWM function of mass flow of air supplied the expander with an index of 0.5 together with pulsating air heating in the expander installation, including three- reciprocating drives, allows a maximum total energy conversion efficiency of 81%. The presented piston drive expander seems to be a promising solution for micro-CAES in residential and industrial applications, especially where additional low-temperature waste heat is available, and an intermittent control strategy is implemented. [Display omitted] • Original construction of the air expander includes multi-piston-drives. • The micro-CAES with air preheat and PWM control strategy ware implemented. • Obtained maximum efficiency of piston-drive micro-CAES is 81%. • Generated electrical power could be control with overall efficiency change up to 10%. [ABSTRACT FROM AUTHOR]

In this paper, a hybrid technique is proposed for analyzing the performance of buck converters with fractional-order proportional integral derivative (FOPID) controllers. The hybrid approach is a combination of Capuchin Search Algorithm (CapSA) and Golden Jackal Optimization (GJO). The update behavior of Golden Jackal Optimization2 is enhanced with Capuchin Search Algorithm (CapSA) therefore it is called the improved GJO (IGJO) technique. The power converters are hard to manage based on their nonlinear nature and therefore the search for smart and effectual controllers is ongoing and continual. In current years, fractional order controllers have shown greater efficiency in power electronic systems. The IGJO technique is used to establish the optimum design of a fractional-order proportional integral derivative (PID) controller for the buck converter. The FOPID controller parameters are considered to diminish several performance metrics, with a particular focus on the Integral Squared Error (ISE). The proposed method is performed in the MATLAB, and its execution is analyzed by using the existing methods. From the simulation result, the proposed method reduces the error more effectively than existing methods. • A hybrid approach for analyzing the performance of buck converters with fractional PID controller is proposed. • The proposed hybrid approach is the combination of CapSA and GJO. • The IGJO technique is used to establish the optimal design of FOPID controller for buck converter. • The proposed model is performed on MATLAB/Simulink platform, and its execution is evaluated using recent algorithms. • From the simulation, the proposed approach reduces the error effectively than existing methods. [ABSTRACT FROM AUTHOR]

High level of mental stress will lead to negative psychological and health consequences, such as insomnia, depression, and cardiovascular disease, which will increase the suicide rate and affect social stability. Mental stress has been proved to be related to biomarkers cortisol and skin conductance, and reflects the complementary advantages of stress monitoring. Based on electrochemistry and electrophysiology analysis technology, combined with microelectronic design and biosensors, this paper constructed an integrated physiological and biochemical sensing system, and an intelligent user interaction system. Firstly, a molecularly imprinted biosensor with gold nanoparticles (AuNPs), prussian blue (PB), and polypyrrole (PPy), achieved highly sensitive detection of cortisol in the range of 1–10000 ng/mL and demonstrating good specificity. The cortisol detection unit used differential pulse voltammetry (DPV) method by dual power amplifier chip AD8674, which was a precision operational amplifier with low noise, low input bias current, and unit gain stability. Then, the skin conductance detection unit was mainly composed of a pulse width modulation (PWM) drive circuit, which was designed to achieve a 100 Hz voltage output. The integrated system was designed with microcontroller module, transimpedance amplifier (TIA) module, power management module, signal transmission module, cortisol and skin conductance detection module, which was suitable for constructing precision voltage control and weak current signal conditioning. Finally, based on the software and hardware platform of smartphones, an intelligent analysis system was developed to improve the portability and user interaction convenience. Our system achieved the physiological and biochemical joint detection for the first time, showing enormous application potential in future multimode sensing monitoring. • Integrated physiological and biochemical sensing system. • Electrochemistry and electrophysiology combined with microelectronic design and biosensors. • Intelligent user interaction system on smartphone. • Application potential in future multimode sensing monitoring. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents methods for solving the polynomial system which is called the composite sum of powers. It is shown that these polynomial equation can be reduced to a single-variable polynomial equations by exploiting the modified Newton’s identities. In this paper we generalize this identity and solve it via Padé approximation theory and the related theory of formal orthogonal polynomials (FOPs). Because the solution forms the roots of FOPs we present several interesting computational procedures, such as the use of three-term reccurence formulas, determinantal formulations and the computation of the eigenvalues of tridiagonal matrices. The computation of this special polynomial system arise in practical engineering task of solving optimal odd symmetry single-phase pulse-width modulated (PWM) problem. [Copyright &y& Elsevier]

Abstract: In order to improve the control performance of boost converter with large signal disturbance, a composite PWM control strategy for boost converter operating in continuous condition mode (CCM) was proposed in this paper. The parasitical loss of Boost converter was analyzed and a loss compensation strategy was adopted to design feed-forward tracker for converter. The composite PWM controller consisted of the tracker and PID controller. Simulation and experiment results validated the validity of the control strategy presented in this paper. [Copyright &y& Elsevier]

Selective Harmonics Elimination Pulse width modulation (SHE PWM) presents an alternative modulation technique to operate medium voltage medium and high power converters as it reduces the switching losses. SHE PWM generates high-quality output waveform at the low switching frequency. Its application to multilevel converters furthers leads to improvement in output waveforms with lower switching losses, lesser dv/dt and lowers switching devices ratings. In this Paper SHE PWM for an asymmetrical cascaded H-bridge multilevel inverter under unequal DC voltage condition for fundamental and multiple switching cases are investigated. More harmonics can be eliminated by considering multiple switching's. The Solution of the Nonlinear transcendental SHE equation is obtained using an advanced derivative free numerical technique which. The method is simple in implementation with fast calculations per iteration as it avoids the evaluation of Jacobian and its matrix. Also the need for precise initial guess in the proximity of actual solution is not needed as an identity matrix of the size of designed variable serves the purpose. Different inequality in the dc voltages is taken to eliminate the lower order harmonics from the output. Only exact solutions for the switching angles which ensure the complete elimination of targeted harmonics are reported. Simulation and Hardware results are presented to confirm the validity of the proposed technique. • SHE PWM for an asymmetrical CHB MLI under unequal DC Sources for different switching cases are given. • The Solution of transcendental SHE equation is obtained using derivative free numerical technique. • Simple in implementation with fast calculations as it avoids the evaluation of Jacobian matrix. • The need for initial guess in the proximity of actual solution is not needed in the proposed technique. • Inequality in the dc voltages is considered to eliminate the lower order harmonics in output. [ABSTRACT FROM AUTHOR]