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Mismatch losses (ML) problem can directly reduce the power generation of a photovoltaic (PV) array as well as complicate maximum power point tracking (MPPT) algorithms by causing multiple peaks to appear in the P-V characteristic. Hence, PV array reconfiguration techniques have become highly popular to minimize the ML of PV arrays. In this article, an optimal dynamic topology reconfiguration method based on a switching matrix is presented for series–parallel (SP) interconnected PV array to mitigate the ML, thereby maximizing the power generation of the PV array. The design of the switching matrix is presented that enables each string of the PV array to be divided into two sections to carry out the efficient dynamic topology reconfiguration with improved flexibility and scalability. The proposed reconfiguration method is assessed and compared with the SP scheme and the recently developed cross diagonal view method. The effectiveness of the proposed solution for the TCT scheme is also confirmed through simulation experiments. The numerical results indicate that the multiple peaks on P-V curves can be reduced and MPPT can be implemented with a simple control algorithm. Additionally, the maximum power generation improved by 20.13% and 14.39% on average compared to the SP scheme and TCT scheme, respectively, for different mismatch conditions of partial shading and random PV module failures.

SiC MOSFET has superior switching performance over Si IGBT in terms of power loss and temperature characteristics. In order to significantly improve the efficiency and power density of medium voltage drive and high-power converters, this paper proposes a current source gate driver for series connected SiC MOSFETs, forming a universal block of series connected SiC devices with higher voltage rating. Proposed current source gate driver has better gate voltage synchronization performance because of its constant gate current and novel gate driver structure. By implementing synchronized gate voltages, the snubber circuit is designed only for power loop difference, gate displacement current difference, and the snubber can be minimized or even be eliminated. The proposed block has been verified by LTSPICE simulations and multi-pulse test experiments under 200kHz, 2kV, 0~60A condition using three 1.2kV/60A C2M0040120D SiC MOSFETs connected in series.

In this paper, a basic capacitive power transfer (CPT) topology with series-parallel (SP) compensation is developed for load-independent step-up voltage output. There are three main contributions. First, the step-up constant-voltage (CV) output and zero-phase angle (ZPA) property are designed by using an h-parameter modeling method. Second, a current-source rectifier (CSR) is proposed at the secondary side and the working transient is analyzed. Third, the impact of parasitic resistances is investigated, and the output voltage attenuation and system efficiency are analyzed at different loads, coupling coefficients, and quality factors. A 130 W prototype is implemented with 150300mm metal plates. Experiments validate the CV output property with a step-up voltage gain of 2. The peak efficiency is 86.6% at a coupling coefficient of 0.16 and a transfer distance of 4mm.

To integrate large-scale islanded onshore wind power with different sizes, this paper proposes an integration system based on the cascaded hybrid HVDC transmission system, which consists of LCC and several MMCs in series connection at the DC side of the rectifier. A large-scale wind farm is connected with one LCC and one MMC while several medium-scale wind farms are connected with MMCs directly. Owing to the hierarchical integration arrangement, the operating flexibility can be improved with reduced capacity and the number of step-up interfacing transformers. A resilient DC voltage control is proposed for the integration system to adaptively redistribute power among the converters during wind power fluctuations. Firstly, the topology and operating characteristics of the wind power integration system are introduced. Then, a resilient DC voltage control is proposed to ensure stable operation during wind power curtailments. Finally, a simulation model of the hybrid cascaded HVDC transmission system is built in PSCAD/EMTDC to verify the effectiveness. The research results show that the system provides a new option for long-distance transmission of large-scale islanded wind power.

Various advantages are directing the attention to modular multilevel converters (MMCs). Simple ways to balance the voltage difference of MMC modules are strongly desired but an open problem. The modular multilevel series/parallel converter (MMSPC) can be an efficient solution for this problem. However. implementing an effective control method is essential for close-to-optimum operation of MMSPCs. Generally, on the higher level of control, various modulation techniques can control the output, while a scheduler balances the module voltages on a lower control level. This paper proposes a simple yet powerful module scheduling method for MMSPCs. This scheduling method can be combined with many modulation techniques, such as nearest level modulation (NLM). It reduces the control complexity using the sensorless balancing capability, improves efficiency by minimizing the conduction loss, and achieves a compromise between balancing the module voltages and switching loss. Though applicable to other modulation methods, simulation and experiments combine the proposed method with NLM for a comparison with prior-art of scheduling. Based on the presented results and analysis, the algorithm is suited particularly for MMSPCs with low to medium number of modules. The proposed technique achieves 1855% reduction in power loss and 7.5% improvement in capacitor currents compared to other algorithms.

In this manuscript, we adopt a copula-based hierarchical dependent approach to analyze the redundancy allocation policy and statistical dependence effect on the reliability of two-parallel-series and series-parallel systems with interdependent subsystems from statistically dependent components and use a Schur-concave copula to model the statistical dependence between the outer subsystems, and an Archimedean copula to characterize the statistical dependence among the inner components. Firstly, we analyze and compare the reliability of different redundancy strategies for a two-parallel-series system in the sense of the usual stochastic order under the number of chosen components that are fixed and randomized. Secondly, we also provide sufficient conditions on the usual stochastic order of two different assembly policies for a two-series-parallel system when the number of chosen components is deterministic and randomized. These results can be conductive to allocate the two-parallel-series and two-series-parallel systems with interdependent subsystems from statistically dependent components in practical scenarios. Finally, some applications of the real-data and the potential managerial implications and future directions are also provided to enhance the system’s reliability.

We represent a flow of a graph G = ( V , E ) as a couple ( C , e ) with C a circuit of G and e an edge of C , and its incidence vector is the 0 ∕ ± 1 vector χ C ∖ e − χ e . The flow cone of G is the cone generated by the flows of G and the unit vectors. When G has no K 5 -minor, this cone can be described by the system x ( M ) ≥ 0 for all multicuts M of G . We prove that this system is box-totally dual integral if and only if G is series–parallel. Then, we refine this result to provide the Schrijver system describing the flow cone in series–parallel graphs. This answers a question raised by Chervet et al., (2018).

In this article, a modular output series-parallel series resonant converter (SRC) differential buck converter is analyzed for high-power, ultra-wide-voltage applications such as battery formation systems and bench-type power supplies where a zero voltage discharging function is required. An independent control method in one module is proposed to increase the efficiency of the converter compared to the conventional complementary control method. In the modular output-series connection, higher efficiency can be achieved by shedding needless modules in the low voltage range. Module shedding and activating techniques are proposed to eliminate current and voltage transients during a mode change under any load condition without the use of additional bypass switches. In addition, when a fault occurs in one module, its effect on the other module is analyzed. A practical solution involving turn- off processes for fail-safe operation is proposed, which reduces current stress and voltage spikes on devices and effect among modules without depending on the external signal from the central controller and the communication delay. A prototype of a modular series-parallel SRC- differential buck converter is implemented to verify the proposed concept.

It is of great importance for physicists and engineers to assess a lifetime distribution of a series-parallel system when its components' lifetimes are subject to a finite mixture of distributions. The present article addresses this problem by introducing a new distribution called "Poisson-geometric-Lomax distribution". Important properties of the proposed distribution are discussed. When the stress is an increasing nonlinear function of time, the progressive-stress model is considered and the inverse power-law model has suggested a relationship between the stress and the scale parameter of the proposed distribution. Based on the progressive type-II censoring with binomial removals, estimation of the included parameters is discussed using maximum likelihood and Bayes methods. An example, based on two real data sets, demonstrates the superiority of the proposed distribution over some other known distributions. To compare the performance of the implemented estimation methods, a simulation study is carried out. Finally, some concluding remarks followed by certain features and motivations to the proposed distribution are presented.

The series connection of a standard three-level active neutral-point-clamped (ANPC) inverter and two cascaded H-bridge (CHB) modules comprising the flying capacitors (FCs) instead of the isolated dc voltage sources forms a seven-level hybrid topology that is referred to as improved ANPC (I-ANPC) converter. This article proposes an active voltage balancing technique for control of this hybrid multilevel inverter. The suggested method is based on a set of effortless logic equations that aim to stabilize the FC voltages within the CHB modules at their requisite reference values as well as to control the output voltage of the overall hybrid converter based on the phase-shifted-carrier pulsewidth modulation strategy. The experimental results obtained from a single-phase I-ANPC inverter's prototype are presented to validate the proposed control technique and its simple logic equations.

Series connection of SiC MOSFET s provides an effective alternative to achieving higher blocking voltage with simpler circuit topologies. However, the voltage imbalance during the switching transient remains a critical issue. Recently, an active $\mathrm{\text{} d }v/\mathrm{\text{} d }t$ control approach utilizing a controllable equivalent Miller capacitor has been proved to be an effective, low-loss, and compact solution. This article renders an improved control circuit with comprehensive modeling and analysis. First, the original circuit is modified with an additional bipolar-junction-transistor and pulsed control signal so that the external capacitor can be fully reset every switching cycle. Second, a simplified model of the active $\mathrm{\text{} d }v/\mathrm{\text{} d }t$ control is derived to unveil the linear correlation between the control voltage and the device $\mathrm{\text{} d }v/\mathrm{\text{} d }t$ during the turn- off transient. Third, a feedback control model is described by difference equations for stability analysis, offering parameter selection guidelines for the control process. Fourth, experimental results with two series-connected SiC MOSFET s under 1.5-kV dc-link voltage are demonstrated to validate the open-loop control model and closed-loop stability. Finally, the control method is expanded to eight series-connected devices under 6 kV to prove its scalability and potential for medium-voltage high-current applications.

We introduce an approach based on the Chapman-Kolmogorov equation to model heterogeneous stochastic circuits, namely, the circuits combining binary or multi-state stochastic memristive devices and continuum reactive components (capacitors and/or inductors). Such circuits are described in terms of occupation probabilities of memristive states that are functions of reactive variables. As an illustrative example, the series circuit of a binary memristor and capacitor is considered in detail. Some analytical solutions are found. Our work offers a novel analytical/numerical tool for modeling complex stochastic networks, which may find a broad range of applications.

Obtaining maximum power output even under adverse contributing factors is the main aim of all reconfiguration techniques that have been reported in literature. Although various attempt has been made to harness maximum energy via physical or electrical PV panel reconfiguration techniques. All these reconfiguration techniques increase the value of output power either by physical or electrical relocation of panel within a column or by placing it at a suitable position in the entire PV array. The placement of PV panel or reconnection of the PV panel at a new location is inspired by some optimization algorithm or by some pattern. This paper proposes a new reconfiguration scheme for maximum power output along with effective shade dispersion, lower voltage drops and lesser cost of cables. Paper also attempted to analyse the pragmatic aspect of PV modules connected under different reconfiguration schemes namely Series Parallel (SP), Total Cross Tied (TCT), Odd-Even (OE), Odd-Even-Prime (OEP), LU SHO, Sudoku etc. and evaluates the consequences of its applicability at field. Although the various reconfiguration scheme has reported to increase the output current and thereby the output power but the increase in capital cost of cables, voltage drop and power losses outweighs the increase in output current and power. Also, if the distance between the rooftop PV array and the location of the String Combiner Unit (SCU) is large, then loses will even be more. A comparative analysis of different reconfiguration techniques under various parameters is performed.

The transformerless inverters are more attractive due to their higher efficiency, lower cost, and lighter weight for grid-tied photovoltaic (PV) systems. However, the leakage current can flow through the system because of no galvanic isolation. This undesirable current leads to more losses, electromagnetic interferences, current harmonic distortion, and safety concerns. Therefore, the suppression of the leakage current in transformerless cascaded H-bridge (CHB) based PV systems is investigated in this article. First, the theoretical analysis is presented to model the leakage current for a five-level CHB inverter, and then a new modulation-based method is proposed to suppress this current. In contrast to most existing solutions, the proposed method can be easily generalized through the series connection of five-level CHB blocks. The validity of the proposed solution is verified by several simulations in the power systems computer aided design (PSCAD)/EMTDC environment. Then, experimental results on a five-level and nine-level CHB inverter are presented to confirm the theoretical and simulation results.

The accurate state of charge (SoC) estimator has great significance for ensuring the safety and reliability of Li-ion battery systems. However, the accurate SoC estimation for a series–parallel connected battery pack is a remaining challenge due to the strong inconsistency characteristic caused by cell open-circuit (COC) faults. Therefore, a novel fault-tolerant multimodule SoC estimation method for the series–parallel connected battery pack is proposed. An average module model is used to describe the performance of the battery pack. A bias correction model considering SoC, series resistance, and polarization characteristic inconsistency is developed to describe in-pack modules. A noise adaptive H ∞ filter-unscented H ∞ filter is employed to estimate SoC for the average module. The SoCs of in-pack modules are obtained by an optimized recursive least square method. A correlation coefficient-based method is developed to detect COC fault and isolate the fault module. Finally, several experiments on a 4s-3p battery pack are taken to evaluate and verify the real-time performance, stability, and accuracy of the proposed method. The result shows that both online and offline SoC estimation error is less than 1% for healthy modules, and it is less than 2.5% for the fault module in which one-third capacity is lost randomly.

Droop control has been well adopted for multi-source multi-load DC microgrids (MGs) due to its inherent modularity and reliability by only using local measurements, especially with the most commonly-used voltage-current droop (V-I) mode. While another implementation named current-voltage droop (I-V) mode also can be adopted. With the same value of droop gain in these two modes, a DC MG will have the same steady-state feature, but its dynamic performance of DC voltage control may be different. Our primary motivation is to investigate this phenomenon from the perspective of equivalent RLC circuits. This paper proposes a generic reduced-order modeling method suitable for exploring the dynamic stability of DC voltage control with these two modes. By ignoring fast inner current control dynamic, each droop based DC voltage control unit can be modeled as a RLC parallel circuit in these two modes, which is convenient for modular modeling and extension. In addition, if the inner current control with slow dynamic cannot be ignored in some specific scenarios, a modified RLC model can be still obtained to analyze its influence. Tthe effectiveness of the proposed reduced-order modeling method has been verified by detailed simulation and experiment results.

Fast recovery, high sensitivity, high selectivity, and room temperature (RT) sensing characteristics of NO gas sensors are essential for environmental monitoring, artificial intelligence, and inflammatory diagnosis of asthma patients. However, the conventional semiconductor-type gas sensors have poor sensing characteristics that need to be solved, such as slow recovery speeds (>360 s), low sensitivity (3.8), and high operating temperatures (>300 °C). We propose here a memristor-based NO gas sensor as a gasistor (gas sensor + memory resistor) with SnO2, Ta2O5, and HfO2 films, which successfully demonstrated the feasibility of fast reaction/recovery (

The introduction of doubly fed induction generators (DFIGs) has facilitated the utilization of wind energy to a great extent and constituted distributed generation (DG) systems in remote places. Therefore, long transmission lines are required to interconnect with the utility grid and, consequently, different short-circuit faults interrupt this transmission. Use of different fault current limiters (FCLs) minimizes the effect of faults and allows normal operation with minimum interruption in power flow. In this study, a series-parallel resonance-type fault current limiter (SPRFCL) is presented for enhancing the low-voltage ride-through (LVRT) capability of DFIG-based wind farms. The SPRFCL preserves the nominal voltage and power quality within the permissible limit during normal operation and during disturbances irrespective of the type of fault. The effectiveness of the proposed SPRFCL is validated by simulating both symmetrical and asymmetrical faults. Alongside the SPRFCL, two state-of-the-art FCLs—the parallel resonance-type fault current limiter (PRFCL) and the capacitive bridge-type fault current limiter (CBFCL)—are considered to investigate and compare the relative performances. Several graphical and numerical studies assure the efficacy of the proposed SPRFCL in wind farm application in multiple aspect. Moreover, the stunning total harmonic distortion (THD) values with the proposed technique signifies the excellency over its competitors. Additionally, the sub-synchronous resonance (SSR) analysis confirms the supremacy of SPRFCL for series compensated lines.

Series–parallel directed graphs have been generalized in various directions. Some of these generalizations control the structure of certain emerging induced subdigraphs called N ’s. They allow an efficient recognition by decomposition trees. We introduce another class of directed acyclic digraphs generalizing series–parallel directed graphs with less structure of induced N ’s. We show that they still can be efficiently recognized by a decomposition approach. In contrast, however, to the other mentioned generalization this decomposition is not unique and does not lead to a tree but a planar graph.

PV-TEG PV–TEG hybrid system is widely discussed nowadays, as an alternative way to maximize solar radiation energy which is from both of its light and heat. In recent years, the idea of using thermoelectric generators (TEGs) to extract energy from heat waste has increased with applications varying from milliwatts to kilowatts. To form a circuit, numbers of TEG modules can be connected in series and/or parallel configuration to produce the required voltage and/or current. In the PV-TEG PV–TEG​ systems, due to operating environments, each TEG module’s power generation is subject to temperature mismatch. There is also considerable variability in the electro-thermal output and mounting pressure of each TEG module in a circuit, resulting in a significant inconsistency. Therefore, when each TEG in the array is active, a varying electrical operating point will occur at which peak energy can be obtained and problems with lower power output will occur. In this work, an individual TEG module test method was used to measure and analyze data from specific types of TEG, and a record of the maximum power output under different temperature variations is obtained. Then, the performance of the TEG system is measured and evaluated with a test bench where the modules are attached at different backside areas of generic PV panels. The non-uniform heat distribution condition created in the experiment showed an average 33 % drop in power production from the maximum power that would be available in case each TE series circuit operates under uniform heat distribution. This experimental finding demonstrates the problem and the outcomes discussed in this paper validated a thorough examination of the effect of nonuniform operating temperatures on a range of thermoelectric generator’s energy output.

In this paper, a MATLAB based Simulink model of a Series-Parallel Hybrid Electric Vehicle is presented. With the advent of Industry 4.0, the usage of Big Data, Machine Learning, Internet of Things, Artificial Intelligence, and similar groundbreaking domains of technology have usurped manual supervision in industrial as well as personal scenarios. This is aided by the drastic shift from orthodox and conventional Internal Combustion Engine based vehicles fuelled by fossil fuels in the order of petrol, diesel, etc., to fully functional electric vehicles developed by renowned companies, for example Tesla. Alongside 100% electric vehicles are hybrid vehicles that function on a system based on the integration of the conventional ICE and the modern Electric Propulsion System, which is referred to as the Hybrid Vehicle Drivetrain. Designs for modern HEVs and EVs are developed on computer software where simulations are run and all the essential parameters for the vehicle’s performance and sustainability are run and observed. This paper is articulated to discuss the parameters of a series-parallel HEV through an indepth MATLAB Simulink design, and further the observations are presented. Keywords: ICE (Internal Combustion Engine), HEV (Hybrid Electric Vehicle), Drivetrain, MATLAB, Simulink, PSD (Power Split Device), Vehicle Dynamics, SOC (State-of-Charge)

Partial shading conditions considerably reduces the power generation for conventional PV array connection. This problem can be diminished effectively by repositioning the PV panels. In this paper, ...

This article presents a self-balancing technique for voltage sharing of series-connected insulated gate bipolar transistors (IGBTs). Each series IGBT is augmented with an auxiliary switch, which operates in complementary to the main one, and a capacitor in series. When gate signal delays, based on the capacitor voltage feedbacks, are applied to the series modules, the voltage sharing can be balanced. The delays are generated with local controllers without DSP/field-programmable gate array, regardless of the parasitic element distribution, thermal characteristics of the devices, or current amplitudes. Since there is no resistive element in the auxiliary branch, the balancing circuit is low loss. The circuit and the operation modes are provided in detail and illustrated with simulation models. Experimental results with ten series modules at different voltage levels are presented to demonstrate the principle of control, and the performance of the proposed technique.

Series connection of SiC power MOSFET is an attractive approach to expand the blocking voltage of SiC devices, whereas the dynamic voltage balancing among the series-connected devices is the most critical challenge of the technique. In this article, a simple, fast, and cost-effective dynamic voltage balancing circuit of the series-connected SiC MOSFETs is proposed to suppress the voltage imbalance among the devices. The proposed circuit is composed of a resistor-capacitor (RC) snubber with a coupled inductor to effectively sense the voltage imbalance and add a compensated signal to the gate driving voltage. In the article, the operation principle of the proposed method is described in detail and the parameter selection of the circuit is given. Then the optimized layout of the circuit in a typical half-bridge SiC power module is proposed to reduce the stray parameters introduced by the coupled inductor effectively. The proposed method is verified by experiments under different conditions. Compared with a purely RC snubber balancing strategy, the capacitor can be significantly reduced. Since only passive components are required in the feedback loop, the proposed method demonstrates a reliable and straightforward approach to achieve equal voltage sharing of the series-connected devices.

The paper aims are to determine the bi-objective reliability-cost problem of a series-parallel system by employing an interactive approach. Multi-objective optimization is a design methodology that optimizes a combination of objective functions orderly and concurrently. The fuzzy membership functions have been designated to settle the contrary nature of the objectives. Based on these functions and the moment of the objectives in the form of the weight vector, a crisp optimization design is formed. Lastly, the inherited problem is determined with the aid of the PSO (Particle Swarm Optimization) algorithm and confronted with the genetic algorithm. The solution resembling the various choices of the decision-makers towards the evaluation of their decision are listed. A decision-maker can pick an immeasurable one according to his requirement to reach at the aspired goal.

Aiming at the problem that the downtime is simply assumed to be constant and the limited resources are not considered in the current selective maintenance of the series-parallel system, a three-objective selective maintenance model for the series-parallel system is established to minimize the maintenance cost, maximize the probability of completing the next task and minimize the downtime. The maintenance decision-making model and personnel allocation model are combined to make decisions on the optimal length of each equipment’s rest period, the equipment to be maintained during the rest period and the maintenance level. For the multi-objective model established, the NSGA-III algorithm is designed to solve the model. Comparing with the NSGA-II algorithm that only considers the first two objectives, it is verified that the designed multi-objective model can effectively reduce the downtime of the system.

Partial shading condition (PSC) is one of the criteria that reduce the output power generated by photovoltaic (PV) system. It affects the overall performance and efficiency of standalone and grid-connected PV systems. This paper analyzes the performance of conventional PV configurations such as series (S), series parallel (SP), total cross tied (TCT), bridge link (BL) and honey comb (HC) along with conventional hybrid PV configurations such as series parallel–total cross tied (SP–TCT), bridge link–total cross tied (BL–TCT), honey comb–total cross tied (HC–TCT) and bridge link–honey comb (BL–HC) under different PSC. This paper has also proposed four novel hybrid PV configurations such as alternate-total cross tied–series parallel (A-TCT–SP), alternate-total cross tied–bridge link (A-TCT–BL), alternate-total cross tied–honey comb (A-TCT–HC) and alternate-bridge link–honey comb (A-BL–HC) to mitigate the mismatching loss and to optimize the output power. A detailed analysis of effect of PSC on TCT PV configuration is carried out in this paper. 6 × 6 Conventional, Hybrid and novel hybrid PV array configurations are simulated under different PSC using Matlab/Simulink software. Open-circuit voltage, short-circuit current, maximum output power, maximum current, maximum voltage, mismatching loss, fill factor and efficiency are the parameters that are assessed and compared for conventional and hybrid PV array configurations.

The fluctuating force from the dynamic system applied to the piezoelectric material gives electric energy as an output. In the present work, the effect of pressurizing the diaphragm type piezoelectric elements at the same time and at a different time (depicting the condition of in-phase and out-of-phase) has been studied. Furthermore, to combine the outputs, the use of series and parallel circuitry has been studied before the rectification (AC to DC) and after the rectification. The material of the piezoelectric used in the experiments was lead zirconate titanate (PZT). The maximum power output of 362.8 µW is obtained when the two piezoelectric elements were pressurized in-phase by a cyclic force of amplitude 400 mA and 17 Hz frequency, their signals rectified and then combined through the parallel circuit. The high power output is at the natural frequency of the mechanical system.

We consider a sequential decision model over multi-tier supply chain networks and show that in particular, for series parallel networks, there is a unique equilibrium. We provide a linear time algorithm to compute the equilibrium and study the impact and invariant of the network structure to the total trade flow and social welfare.

Wind power is one of the most important renewable energy sources that is widely used in many developed and developing countries. However, it is generally stated in the literature that providing accurate forecasts for large‐scale planning purposes is not a simple task, especially by single models. It is the main reason for this fact that why researchers in recent years have sought to propose hybrid models for increasing the accuracy of predictions. In general, choosing the appropriate type and the number of components, as well as the proper type of hybridization methodology, are the most effective factors in the performance of the developed hybrid models. Although in the literature, numerous attempts have been made in order to answer these questions, there is no general consensus on this matter. For this reason, the main idea of this paper is to concurrently combine different hybrid methodologies as well as different single models in order to benefit from the advantages of these models and methodologies, simultaneously. In this way, three well‐known and widely used hybrid methodologies, including the preprocessing, the series, and the parallel methodologies, are combined together by incorporating the linear/nonlinear and certain/uncertain components. In addition, in the proposed model, a new process is proposed based on the complex/uncertain modelling to model the preprocessing phase residuals, which have been ignored in the modelling procedures. In this way, in the first stage of the proposed model, the data is preprocessed by the Kalman filter as a preprocessing approach in order to divide data into two groups of trend and residual patterns. The trend data provided in the previous step, with the original data, are simultaneously considered input data of an autoregressive integrated moving average as the certain linear model and a multilayer perceptron as the certain nonlinear model for certain linear and nonlinear modeling of patterns. This step is repeated for the residual data by the series hybridization of models in the previous stage by the fuzzy models for the uncertain linear and nonlinear modelIng of patterns. Finally, each component's weight is optimally calculated by the least square algorithm, and then the results are combined together in a parallel process. Empirical results of two benchmarks of wind domain indicate that the proposed method has averagely improved the performance of its component used separately, parallel‐based hybrid models, and series‐based hybrid models 46%, 22%, and 19%, respectively, for predicting wind power time series.

A complex non series–parallel system of (m, $${n}_{c}$$ , l) order is developed by introducing ‘l’ additional components linked to arbitrary non-adjacent ith and jth components of ‘m’ parallel subsystems each containing $$\left\{{n}_{c};1\le c\le m\right\}$$ components connected in series. The efforts have been made to determine the best possible structure of the components in order to develop highly reliable system. The logic diagram technique is used to form maximal number of effective duplication paths between IN and OUT terminals according to the flow of information. Each path contains components whose successful operation can lead to successful operation of the system. The path which dominates over any other path is discarded keeping in view of the fact that this path has no effect on reliability of the system. The expressions for reliability and mean time to system failure are derived for the system by considering Rayleigh failure laws using path tracing method. An illustration is given to justify the application of the present work.

The series connection of SiC MOSFETs is an attractive way to expand the voltage of SiC devices. However, the voltage imbalance is among the most critical challenges to overcome. In this letter, an active voltage balancing method suitable for two devices connected in series is proposed. Specifically, a multiwinding coupling inductor with low number of turns is applied to achieve voltage deviation sampling and high-quality signal isolation. The sampled signal is further conditioned by a controlled current source and injected into the gate–source voltage. Owing to the high output impedance of the current source, the voltage balancing circuit is independent of the normal switching of SiC MOSFETs under balanced conditions. The operation principle, parameter design, and implementation are given in detail.

We have fabricated CZTSSe solar cells with H2S sulfo-selenization processes and investigated the electronic structure at the PN hetero- and back contact junctions by impedance spectroscopy. By decoupling each junction’s impedance spectroscopic responses, we systematically characterized the built-in potential of two local junction interfaces. A developed equivalent circuit model has been optimized for decoupling each junction’s property at different frequency bands. Modeling and numerical simulations were conducted with the in-house MATLAB modeling suites connected to external simulators of Sentaurus TCAD and LEVM/LEVMW software to estimate the impact of each junction component to impedance spectra. The optimized model is comprised of a parallel circuit combination with resistance and capacitor-like elements (constant phase elements), connected to one inductive element. The conversion efficiency of CZTSSe devices is 6.2% with bandgap energy 1.13 eV based on external quantum efficiency measurements. From the equivalent circuit model, the built-in potential of the hetero-junction is characterized as 956 meV, which is ~ 3% smaller than an ideal case from TCAD, 987 meV. Conversely, the built-in potential of the back contact junction is 476 meV. The apparent built-in potential is estimated as 480 meV from the Mott-Schottky equation.

A three-phase asymmetrical dual active bridge (TP-ADAB) dc–dc converter with series/parallel-reconfigurable output (SPRO) is proposed for wide output range and constant peak power applications. The three outputs of the TP-ADAB converter are able to be connected in series or parallel to achieve wide output voltage range. The output voltage range, maximum output voltage/current of each power module, as well as the power rating of devices, are reduced significantly. Moreover, automatic voltage sharing in output series mode and current sharing in output parallel mode is achieved by adopting the three-phase structure. Furthermore, soft-switching of all power switches is achieved in a wide operation range. Operation principles, output characteristics, soft-switching performances, and control strategy of the proposed TP-ADAB converter are analyzed in detail. Experimental results of a 3 kW prototype are provided to verify the effectiveness and feasibility of the proposed converter.

The dynamic response of the model, which is the series connection of a planar four-bar mechanism and a spatial RSSR mechanism, is analyzed considering revolute joint clearance and friction. A non-holonomic constraint equation is proposed to solve the Euler angles. The dynamic equations are established by combining the Lagrange equation with the modified contact model and the LuGre friction model. A dynamic solution program based on the coordinate partitioning method is designed to solve the dynamic equations. The paper verifies the correctness and applicability of the solution program by comparing the numerical calculation results with Adams simulation. Compared with the results of eccentricity, it is found that the maximum penetration is very sensitive to the change of the slider speed rather than the clearance. The equivalent damping coefficient proposed by authors not only represents whether a collision occurs, but reflects the hysteresis caused by damping. The macroscopic manifestation of the up and down oscillation of eccentricity is the swing of the contact point. Besides, the system quickly changes from the collision into the stable state due to considering friction, and the peak value of each collision reduces greatly. Therefore, when the clearance is unavoidable, the clearance joint should be coated with a material with a large friction coefficient and not easy to wear.

This paper attempts to come up with a proposed configuration of Multilevel inverters with a lesser number of switches that are smaller in size, lesser in cost and with a higher efficiency. Designing an inverter topology with a lesser number of switches and proper control technique is the major challenge. cascaded H-Bridge (CHB) topology are more popular among the existing configurations of multilevel inverters (MLI). Even though it can produce more levels, it needs to accommodate a huge number of switches for higher levels. The focus of this paper is to reduce the number of components for the same voltage level of cascaded H- Bridge configuration. In addition to that, generating the gating pulses for the switches is difficult when there is an asymmetry in the switches. A new symmetrical series/parallel configuration is proposed with reduced switch count and the pulse width modulation (PWM) technique is implemented with digital logic to generate the required gating pulses for the switches. The total harmonic distortion (THDI) of the output current is reduced with this PWM technique. The simulation has been carried out in MATLAB/Simulink software for both R (resistive) and R-L (resistive -inductive) loads.

This study discusses the planning in making a centrifugal pump installation with a combination of two series, namely series and parallel. The concept of discussion refers more to the upgrading of the installation system and calculates the estimated processing time needed to test the performance of the results of the installation that has been made. From the results of the research, it was found that for the preparation of series series installation it takes ± 8.5 minutes including the cutting process of materials and component installation, while the time required in making the installation of parallel circuits ± 28 minutes so that the total manufacturing of the two types of series takes 36, 5 minutes. In terms of performance generated from each installation obtained at full aperture where for the series of head series the value obtained is 37.6 m with a flow capacity of 3.25 l / s while for the head value on the parallel pump obtained by 27.7 m with a capacity flow of 3.75 l / s and this pump operates at 2900 rpm. So it can be seen from the results of the head and flow capacity obtained values ​​indicate good pump performance and ready to be used as a practical tool in the laboratory.

In this article, we consider residual lives of series-parallel and parallel-series systems with independent subsystems consisting of dependent homogeneous components with the joint distribution of ...

The fractionation system of industrial hydrocracking aims to fractionate the feedstocks to highly-valued distillates according to different boiling ranges. Therefore, the operation optimization for the system can effectively increase output and profits of factory. However, there is a complicated series-parallel structure between the distillation columns, which makes it very difficult to optimize the system. In this study, a two-stage optimization method for the series-parallel fractionation system of industrial hydrocracking is proposed. Firstly, the fractionation system is divided into an optimal structure through a phased calculation method to cut down unnecessary computation. Then, an adaptive logic of computing resource and a new sampling and evaluation strategy are adopted in candidate adaptive state transition algorithm (CASTA) to solve the optimization problem. CASTA can balance the computation resource and speed up optimization speed. Benchmarks are provided to illustrate the effectiveness of the proposed CASTA. Moreover, the two-stage optimization method was successfully used in the operation optimization of the series-parallel fractionation system of industrial hydrocracking, and achieved more efficient results than other optimization algorithms.

A seven-bus ac–dc hybrid nanogrid system for futuristic buildings (FBs) and its related control strategy are proposed in this article. The nanogrid has one ac bus and six dc buses which can be operated simultaneously and power from any bus can be transferred seamlessly to the other buses. Further, two dc buses and the ac bus are designed to operate both in the grid connected as well as in stand-alone mode. The other two dc buses are meant for interfacing solar photovoltaic (PV) system and the battery storage. The remaining two dc buses are configured to negotiate loads at medium voltage levels. The reconfigurable feature of some of the buses enhances the applicability of the nanogrid for powering a wide range of home appliances. The battery bus and the PV bus are designed for low voltage rating to minimize the series connection of batteries and PV modules, respectively. Further, the requirement of lower number of series connected modules for the PV array minimizes the effect of shading which is normally experienced in case of roof top installations. The system is also made transformerless, thereby reducing its size, volume, and weight as compared to the schemes involving line frequency transformers. The viability of the proposed nanogrid system is validated by performing detailed experimental studies on a laboratory scale 1.2-kW nanogrid system developed for the purpose.

Medium-voltage (MV) dc collection system is a promising solution for future integration of large-scale renewables at remote places. This requires a high-power dc–dc converter to step up the voltage and connect with the high voltage direct current transmission line. In this article, a novel modular high-power dc–dc converter is proposed, with the combination of half-bridge and full-bridge submodules (SMs), as well as thyristors and diodes. It alternatively configures the SMs into parallel connection with the MV side to effectively share high current stress while series connection with the high voltage side to share the high voltage stress. It presents attractive features such as high device utilization rate, low cost, high step-up ratio, high efficiency, and small footprint. The circuit structure, operation principle, and the control schemes are discussed. Simulation results demonstrate the effectiveness, and the experimental results from a scaled down prototype further prove the proposed concept.

Slow dynamic response sources, such as fuel cells, are frequently used with faster units, such as batteries and ultracapacitors. In this context, this article gathers the advantages of two energy management techniques to propose the droop k -sharing function. In droop control, energy management is easily implemented using the virtual resistances concept, eliminating the need for fast communication links between the sources. The k -sharing function improves the performance of microgrids with slower sources assigning a preestablished dynamic behavior using a low-pass filter, while the storage unit absorbs the fast transients. Additionally, the k -sharing function also enables the storage unit to share power at a steady state. Therefore, the main advantage of the proposed energy management algorithm is that the control loops of each power source are not coupled to each other, which is accomplished by designing the k -sharing function similarly to the droop technique, eliminating the need for high-speed links of communication and improving the microgrid speed response during fast changes of load. The effectiveness of the proposed function and the theoretical analysis are evaluated using a dc microgrid composed of an H-1000 fuel cell manufactured by Horizon Fuel Cells and three Zippy Compact 5000 25 C Li-Ion batteries in series connection.

This project presents a comparative study between power generation using piezoelectric transducers available in the literature and the proposed model design. The parallel and series-connected piezoelectric transducers arrangement in this project, when subjected to mechanical stress (footsteps), generates an electric charge. The power generated from piezoelectric transducers will be given as input to bridge rectifier and chopper for conversion to dc quantity and its amplification respectively. This energy will be stored in a Li-ion battery. The paper mainly highlights aspects of improvement of power generation by optimizing circuit design and adapting output enhancement and amplification. Comparative analysis of power generated from predecessor circuit designs and output voltage obtained from current circuit design is validated and presented

Variable driving conditions can cause an integrated starter generator hybrid powertrain to switch between multiple drive modes. The addition of a permanent magnet synchronous motor (PMSM) gives hybrid powertrains complex electromechanical coupling characteristics. The effects of excitation sources, such as the engine and PMSM, may cause unstable behavior in the drive system, such as speed fluctuations during mode switches due to electromechanical coupling characteristics. Although traditional mode switch strategies and methods have achieved measurable results, they are difficult to improve. To solve this problem, we first considered the combination and separation of the clutch and establish a nonlinear model of mode switches for series–parallel hybrid electric vehicles. Then, we predicted the instability boundary of the drive system during mode switches. Experimental results indicated that the proposed instability boundary has higher accuracy. Numerical results showed that the three-mode switches have different thresholds of instability for the clutch structure gap. The decrease in electromagnetic torque and the increase in load excitation amplitude will improve the critical value of the clutch structure gap. The increase in load excitation frequency causes the critical value of the clutch structure gap to drop first and then rise.

High-voltage solid state pulse modulators are designed to handle voltage levels, which are several times the order of individual device voltage ratings, necessitating series connection of switches....