Voltage Difference Research Articles

Regeneration of Activated Sludge into SiO2-Decorated Heteroatom-Doped Porous Carbon as Advanced Electrodes for Li-S Batteries.

The regeneration of harmful activated sludge into an energy source is an important strategy for municipal sludge treatment and recycling. Herein, SiO2-modified N,S auto-doped porous carbon (NSC@SiO2) with high conductivity (70 S m-1) is successfully obtained through a simple calcination method of the activated sludge from wastewater treatment. Further, P-doped NSC@SiO2 (NSPC@SiO2) is designed to achieve a higher surface area (891 m2 g-1 vs 624 m2 g-1), a larger pore volume (0.87 cm3 g-1 vs 0.08 cm3 g-1), and more carbon defects. Due to its special structure, NSPC@SiO2 is used as a sulfur host of lithium-sulfur batteries. The results of polysulfide adsorption experiments, S 2p X-ray photoelectron spectra (XPS), Li2S nucleation experiments, polysulfide symmetric cells, measurement of the galvanostatic intermittent titration (GITT), polarization voltage difference, lithium-ion diffusion rate, and Tafel slope verified that NSPC@SiO2 greatly improved the adsorption capacity of polysulfides, lowered the barrier to Li2S formation and the internal resistances of cells, and accelerated Li+ ion diffusion and the reaction kinetics of polysulfide conversion, resulting in the excellent performance of polysulfide capture and superior rate performance and cyclic stability. By comparing NSPC@SiO2 with NSC@SiO2, a higher initial capacity (1377 mAh g-1 vs 1150 mAh g-1 at 0.1C), better rate capacity (912 mAh g-1 vs 719 mAh g-1 at 2C), and low capacity decay (0.094% per cycle within 200 cycles) are obtained. Our work provides direction for the treatment, disposal, and resource utilization of activated sludge.

Generation of Stable Photovoltage in Nonstoichiometric CuBi2O4 Thin-Film Photocathodes

We investigated the effects of stoichiometry on photovoltages and photocurrents in CuBi2O4 thin-film photocathodes grown by pulsed laser deposition under different oxygen partial pressures to manipulate their stoichiometry. While the X-ray diffraction patterns show crystalline phases in the CuBi2O4 thin films, it is found that the Cu/Bi ratio of the CuBi2O4 thin films varied from ~0.3 to ~0.5 which are analyzed by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. The slightly off-stoichiometric CuBi2O4 thin-film photocathode with a Cu/Bi ratio of ~0.44 shows the highest photocurrent density in the CuBi2O4 thin films. More interestingly, the off-stoichiometric CuBi2O4 thin-film photocathode with a Cu/Bi ratio of ~0.44 exhibited a stable open-circuit voltage difference of ~0.2 V RHE without severe degradation over time. On the other hand, the photovoltage of the stoichiometric CuBi2O4 thin-film photocathode with a Cu/Bi ratio of ~0.5 gradually decreased as a function of time. Our results suggest that stoichiometry manipulation can be one of the promising strategies to achieve long-term stable Cu-based oxide photocathodes with the maintenance of a stable photovoltage.

A Fe-Ni-Zn triple single-atom catalyst for efficient oxygen reduction and oxygen evolution reaction in rechargeable Zn-air batteries

The rechargeable Zn-air battery (ZAB) is a promising device for energy storage. A good bifunctional catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays a decisive role in the ZAB. Here, we prepare a Fe-Ni-Zn triple single-atom catalyst (SAC) anchored in the nitrogen-doped porous carbon framework (NC) denoted as SAC(Fe, Ni, Zn)/NC or A-SAC(Fe, Ni, Zn)/NC (ammonia-treated) for the ZAB study. We found that not only Fe-Nx, Ni-Nx, and Zn-Nx act as excellent catalytic sites for ORR and OER, but the synergetic effect by the three adjacent SAC(Fe, Ni, Zn) in the NC enhances the catalytic performance. As a result, the voltage difference (ΔE) of 0.75 V is achieved (half-wave potential of ORR: 0.88 V and the potential of OER at 10 mA cm−2: 1.63 V). In the rechargeable ZAB study, the battery with the A-SAC(Fe, Ni, Zn)/NC has a good specific capacity of 809 mAh/g @ 50 mA cm−2, the excellent power density of 300 mW cm−2 @ 406 mA cm−2 and superior cycle stability (2150 cycles, 358.3 h @ 10 mA cm−2) while the all-soild-state ZAB showed promising power density of 64.5 mW cm−2 and acceptable cycling durability over 25 h@1 mA cm−2. Triple SAC(Fe, Ni, Zn) in the hierarchical porous NC possesses the bifunctional catalytic capability, high ionic diffusivity, and electron conductivity.

Avalanche capability degradation of the parallel-connected SiC MOSFETs

Silicon carbide (SiC) MOSFET chips are often connected in parallel in a module to increase the current rating. However, the current capability is degraded due to unbalanced current and temperature distributions which affect the avalanche processes particularly in extreme operating conditions. To obtain the root cause of the degradation and identify the dominant factors, single-pulse avalanche testing is carried out in this study, and TCAD simulation is used for mechanism analysis. It is revealed that electrothermal parameters have different effects on current sharing in different stages of avalanching. The corresponding failure mechanisms are analyzed, and the main cause of avalanche failure with parallel devices is found to be the difference in breakdown voltage. Device with smaller BV shares more current as well as more heat, which fails first eventually. To resolve such issues, proper device screening/paring should be carried out. The findings are helpful for a better understanding of avalanche capability degradation in parallel devices application.

Techno-economic Study by Teaching Learning-based Optimization Algorithm for Optimal Placement of DG Units in Distribution Systems

A significant improvement in system performance can be achieved by placing Distributed Generator (DG) units of the optimal size in optimum network of radial distribution locations. In order to maximize the economic and technological benefits, it is necessary to reduce yearly economic losses. These losses include expenditures associated with installation and operation of the buses as well as power loss and voltage difference between buses. In view of these multi-objective frameworks, the current problem is assessed and the best compromise solution also referred as the Pareto-optimal solution is provided. In the framework of the multi-objective optimization problem, specific equality as well as inequality constraints is investigated. It is shown in this study that a Multi-Objective Teaching-Learning Based Optimization (MOTLBO) algorithm has been proposed to solve the multi-objective problem. For the purpose of evaluating its performance, the proposed method is being deployed on IEEE-33 and IEEE-69 System of radial bus distribution. A comparison with other recent multi-objective algorithms such as OCDE, KHA and LSFSA is also included in this study. It has been revealed that the algorithm proposed can offer superior outcomes concerning power loss, annual economic loss mitigation and voltage profile enhancement.

Three-phase adaptive reclosure technology for half-wavelength transmission lines using residual voltage frequency difference to identify fault existence

• The single-phase reclosing technique should not be used in half-wavelength transmission systems. • The residual voltage of half wavelength transmission system can be used to determine the existence of faults. • The frequency difference of residual voltage can be used to determine the existence of faults. • We propose a complete and feasible three-phase adaptive reclosure scheme for half wavelength transmission system. UHV AC transmission lines use adaptive reclosure technology not only to avoid reclosing in the permanent faults, but also effectively prevent the emergence of reclosing overvoltage, adaptive reclosure is of great significance, and its technical principle is based on the study and judgment of the existence of the fault. The reactive power of half-wavelength transmission lines along the line was self-balanced, no shunt reactor equipment, there is no "beat frequency" phenomenon, and very little information is available after the three-phase trip. In this paper, we analyze the fault traveling wave's frequency characteristics and identify the fault's characteristics based on the residual voltage frequency difference of the line after the three-phase trip. After the disappearance of the line fault, the stable frequency difference obtained by CVT reflects the entire length of the line, which is not affected by the system boundary conditions and can complete the reliable identification of the disappearance of the line fault. The two-terminal criterion is given for the short-line dead zone problem, and then a three-phase adaptive reclosure scheme for half-wavelength transmission lines based on the frequency difference to identify fault disappearance is proposed. Extensive RTDS digital-analog hybrid tests show that the method is correct and robust.

Soft-Switched Boost–Cuk-Type High Step-Up Converter for Grid-Tied With Half-Bridge Inverter

In this study, a novel two-stage grid-tied high step-up inverter is proposed. The first stage (dc–dc) is a combination of boost and cuk converters as well as a simple dc-link voltage balancing circuit. The balancing circuit is connected in series with the output of the cuk converter to compensate for the output voltage difference between boost and cuk converters. The second stage (dc–ac) comprises a conventional half-bridge inverter. The ground leakage current is eliminated in the proposed topology by the simultaneous grounding of the photovoltaic (PV) module and the grid. A lossless passive snubber with the minimum elements is also proposed and analyzed to provide the soft-switching conditions. In this snubber circuit, the snubber capacitance discharges to the output dc link to decrease the converter circulation losses. The main attributes of the proposed dc–dc converter with lossless passive snubber are the simple structure of the dc–dc converter and snubber circuit, simple control scheme, and high efficiency. Various operation modes of the proposed topology are theoretically analyzed and investigated. The experimental results substantiate the effectiveness and performance of the proposed boost–cuk-based high step-up inverter with the lossless snubber.

Voltage Difference Envelope to the Control Simulating of Connection Frequency of Seamless Shoring

Through the intelligent control of single chip microcomputer and Hall sensor detection technology and signal transmission technology, the frequency, voltage and voltage phase of the shore power and the ship power are detected to form the lowest point of voltage difference envelope, and the seamless connection of the shore power and the ship power is controlled. The load transfer control between the shore power and the ship power realizes the ideal synchronous control of grid-connected closing and load transfer by establishing the ratio control of frequency difference between the shore power and the ship power and power change during load transfer.

2D Resistivity Technique in Exploring Soil Contamination Zones, Kwashe Area, Duhok, North of Iraq

The impacts of leachate on the soil count as one of the main environmental issues, especially near waste dump areas. The Kwashe dumpsite is located in the Semel district, west of Duhok City. Different types of waste had accumulated from medical, construction, and household materials without any barrier or control of the contamination. Wastewater flows on the surface and percolates downward all over the area. Geophysical methods provide high-resolution data to investigate subsurface environmental conditions with no disturbance in the materials. In this study, the 2D resistivity technique by Ohm-Mapper device (G-858G) with a dipole-dipole arrangement was utilized along six resistivity profiles. the system uses one Transmitter to couple an active current signal to the ground and the voltage difference is recorded by one Receiver with separation distances of 2.5, 5.0, 10.0, and 15.0 m. The resistivity data from MagMapper software was transferred to Res2dinvx32 software to create an inversion model for the subsurface. The results showed two main parts: The upper part consists of soil material mixed with recent deposits and fill materials formed of alluvium deposits with resistivity values of 15-50 Ohm.m at a depth between 0.25-3.0 m. The bottom section represents leachate of bowl-shaped anomalies of very low resistivity values of less than 1.0 Ohm.m at various depths. The type of materials in the left and right edges of each of the models represent the main weak zone for leachate infiltration.

Geometry-Dependent Magnetoelectric and Exchange Bias Effects of the Nano L-T Mode Bar Structure Magnetoelectric Sensor.

The geometry-dependent magnetoelectric (ME) and exchange bias (EB) effects of the nano ME sensor were investigated. The sensor consisted of the Longitudinal-Transverse (L-T) mode bi-layer bar structure comprising the ferromagnetic (FM) and ferroelectric (FE) materials and the anti-ferromagnetic (AFM) material. The bi-layer ME coefficient was derived from constitutive equations and Newton's second law. The trade-off between peak ME coefficient and optimal thickness ratio was realized. At the frequency × structure length = 0.1 and 1200, minimum and maximum peak ME coefficients of the Terfenol-D/PZT bi-layer were around 1756 and 5617 mV/Oe·cm, respectively, with 0.43 and 0.19 optimal thickness ratios, respectively. Unfortunately, the bi-layer could not distinguish the opposite magnetic field directions due to their similar output voltages. PtMn and Cr2O3, the AFM, were introduced to produce the EB effect. The simulation results showed the exchange field starting at a minimum PtMn thickness of 6 nm. Nevertheless, Cr2O3 did not induce the exchange field due to its low anisotropy constant. The tri-layer ME sensor consisting of PZT (4.22 nm)/Terfenol-D (18 nm)/PtMn (6 nm) was demonstrated in sensing 2 Tbit/in2 magnetic bits. The average exchange field of 5100 Oe produced the output voltage difference of 12.96 mV, sufficient for most nanoscale magnetic sensing applications.

Lithium-ion battery state-of-charge balancing circuit using single resonant converter for electric vehicle applications

The series of energy storage devices, namely battery, super/ultra-capacitor string voltage balancing circuit, based on a single LC energy converter, is presented in this paper. It transfers the excess energy directly from the higher cell to the lower cell in the string. This requires n-4 bidirectional MOSFET switches and a single LC tank for n number of energy storage device strings. This active balancing circuit has high efficiency, fast balancing speed, small size, low cost, and maximum energy recovery. All MOSFET switches are operated in a near-zero current system and controlled by complementary plus wide modulation signals in synchronous trigger patterns. It achieves the zero voltage gap between two nonadjacent cells in a series battery or supercapacitor string and works on cyclic charging and discharging conditions. In this circuit, the resonant frequency is the same as the switching frequency, and the resonant frequency is reduced. The details of theoretical analysis and operation principles are provided. The experimental result of two 4200 mAh Li-ion cell states of charge 95 % (3.958 V) and 66 % (3.712 V), respectively, after 79 min, voltage difference becomes zero (0 V). Furthermore, we conduct our experiment on lead–acid battery and super-capacitor. This balancing circuit is stable and suitable for battery management systems in electric vehicles.

Theoretical investigations of weakly- and strongly-coupled multi-core fibers for the applications of optical submarine communications under power and fiber count limits.

The practical cable design for optical submarine communications has a limited fiber pair count due to the mechanical considerations of cable weight and size. Consequently, multi-core fibers (MCFs) could exhibit higher capacity than conventional single-mode fibers (SMFs) thanks to space division multiplexing (SDM). That is because the power supply to a submarine cable is fed by the voltage difference between shores. Under the power-limited condition, SDM improves the cable capacity by using more paths which outperforms the SMF link whose capacity approximately complies with a logarithmic relationship to optical power. At the same time, fiber nonlinearity can be alleviated by the reduced power density of transmitted light in MCFs, due to the increased spatial diversity and mode coupling among coupled cores. In this work, we theoretically investigate the potentials of MCFs including weakly-coupled multicore fiber (WC-MCF) and strongly-coupled multicore fiber (SC-MCF) as the propagation media for submarine communications across the Atlantic and the Pacific. To fairly compare the performances of SMFs- and MCFs-based submarine cables, the Gaussian noise (GN) model for SDM links is employed to optimize the systematic settings including spatial multiplicity and single span length. Then, we develop an SDM and wavelength division multiplexing (WDM) fiber transmission model based on coupled nonlinear Schrodinger equations (CNSE) to investigate the optical filed coupling effect in MCFs-based cables. The developed transmission model has been self-examined by measuring the inter-core crosstalk (IC-XT) and spatial mode dispersion (SMD), referring to the set values. As indicated by the theoretical analysis, the WC-MCFs cable exhibits a larger capacity than the SMFs cable, when the fiber pair count is limited below 32. Moreover, the SC-MCFs cable outperforms the WC-MCFs cable thanks to the reduced fiber nonlinearity due to the random mode coupling and the assistance of multiple-input and multiple-output digital signal processing (MIMO-DSP). At last, the marginal influences of IC-XT, SMD, and insertion loss of Fan-in and Fan-out couplers are also analyzed for the MCFs cable.

Defective E2 electrode lead gives low-amplitude compound muscle action potential.

Low-amplitude compound muscle action potential (CMAP) suggests a neuromuscular pathology. Low amplitude will also result from a defective E1 electrode or its lead, that is, a technical artifact. The aim of this study was to investigate the effect of a defective E2 electrode lead on the CMAP. The CMAP was recorded using standard nerve conduction methodology and all electrode leads connected properly. Signals were then recorded when either the E1 or the E2 electrode lead was disconnected from the amplifier. This simulated a defective electrode lead. Studies were performed in four nerves of a healthy subject. CMAP amplitude was reduced as expected when E1 was disconnected. Surprisingly, the amplitude fell by more than 65% when the E2 lead was disconnected, although E1 was properly connected. E1 and E2 electrodes contribute to the CMAP. A defective recording electrode lead to E1 or E2 results in a low-amplitude CMAP. The amplitude drop observed with a disconnected E2 lead was far greater than the signal recorded by the E2 electrode. This occurs due to the amplifier's inherent property to reduce the voltage difference between the E1 and E2 inputs. When E2 lead is defective, the CMAP will be an attenuated version of the signal recorded by the E1 electrode, and vice versa. When low-amplitude CMAP amplitude is observed in all conduction studies, technical artifact should be considered before exploring the pathological basis for the abnormal results.

Synergy between ionic thermoelectric conversion and nanofluidic reverse electrodialysis for high power density generation

Nanofluidic reverse electrodialysis (NERD) is a promising method for the collections of salinity gradient energy. However, further improving the performance is necessary for the commercial applications, while only optimizing the nanopore structure and concentration ratio is hard to achieve the propose due to the tradeoff between high selectivity and low resistance in NERD systems. Based on ionic thermoelectric (i-TE) materials, which possessing huge Seebeck coefficient and natural ion channels, using the i-TE membrane and low-grade heat energy to introduce an additional driving force of temperature difference is proposed for the acceleration of ionic migrations. Results show that the effect of temperature difference is equivalent to overlaying an additional voltage difference, and then the synergy between i-TE conversion and NERD significantly enhances both the power density and efficiency. For the temperature differences of 10 K and Seebeck coefficient of 10 mV K−1, the power densities can be enhanced from 11.72 W/m2 to 23.4–93.8 W/m2, and the efficiencies can also be increased to nearly the upper limit of 0.5. Our study provides new roadmap for improving the NERD performance and the utilizing the low-grade heat energy.

Multiscale statistical quantum transport in porous media and random alloys with vacancies

We have developed a multiscale self-consistent method to study the charge conductivity of a porous system or a metallic matrix alloyed by randomly distributed nonmetallic grains and vacancies by incorporating Schrödinger’s equation and Poisson’s equation. To account for the random distribution of the nonmetallic grains and clusters within the alloy system, we have used an uncorrelated white-noise Monte Carlo sampling to generate numerous random alloys and statistically evaluate the charge conductance. We have performed a parametric study and investigated various electrical aspects of random porous and alloy systems as a function of the inherent parameters and density of the random grains. Our results find that the charge conductance within the low-voltage regime shows a highly nonlinear behavior against voltage variations in stark contrast to the high-voltage regime where the charge conductance is constant. The former finding is a direct consequence of the quantum scattering processes. The results reveal the threshold to the experimentally observable quantities, e.g., voltage difference, so that the charge current is activated for values larger than the threshold. The numerical study determines the threshold of one quantity as a function of the remaining quantities. Our method and results can serve to guide future experiments in designing circuital elements, involving this type of random alloy system.

Tailored Heterojunction Active Sites for Oxygen Electrocatalyst Promotion in Zinc-Air Batteries.

Rechargeable zinc-air batteries (ZABs) are promising energy storage systems due to their low-cost and safety. However, the working principle of ZABs is based on oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), which display sluggish kinetic and low stability. Herein, this work proposes a novel method to design a heterogeneous CoP/CoO electrocatalyst on mesopore nanobox carbon/carbon nanotube (CoP/CoO@MNC-CNT) that enriched active sites and synergistic effect. Moreover, the well-defined heterointerfaces could lower the energy barrier for intermediate species adsorption and promote OER and ORR electrochemical performances. The CoP/CoO@MNC-CNT electrocatalyst presents a high half-wave potential of 0.838V for ORR and a small overpotential of 270mV for OER. The ZABs-based CoP/CoO@MNC-CNT air-cathode shows an open-circuit voltage of 1.409V, the long-term cycle life of 500h with a small voltage difference change of 7.7%. Additionally, the flexible ZABs exhibit highly mechanical stability, demonstrating their application potential in wearable electronic devices.

Fault Location in Distribution Network by Solving the Optimization Problem Based on Power System Status Estimation Using the PMU

Fault location is one of the main challenges in the distribution network due to its expanse and complexity. Today, with the advent of phasor measurement units (PMU), various techniques for fault location using these devices have been proposed. In this research, distribution network fault location is defined as an optimization problem, and the network fault location is determined by solving it. This is done by combining PMU data before and after the fault with the power system status estimation (PSSE) problem. Two new objective functions are designed to identify the faulty section and fault location based on calculating the voltage difference between the two ends of the grid lines. In the proposed algorithm, the purpose of combining the PMU in the PSSE problem is to estimate the voltage and current quantities at the branch point and the total network nodes after the fault occurs. Branch point quantities are calculated using the PMU and the governing equations of the π line model for each network section, and the faulty section is identified based on a comparison of the resulting values. The advantages of the proposed algorithm include simplicity, step-by-step implementation, efficiency in conditions of different branch specifications, application for various types of faults including short-circuit and series, and its optimal accuracy compared to other methods. Finally, the proposed algorithm has been implemented on the IEEE 123-node distribution feeder and its performance has been evaluated for changes in various factors including fault resistance, type of fault, angle of occurrence of a fault, uncertainty in loading states, and PMU measurement error. The results show the appropriate accuracy of the proposed algorithm showing that it was able to determine the location of the fault with a maximum error of 1.21% at a maximum time of 23.87 s.

Remaining Useful Life Prediction for Lithium-Ion Batteries Based on the Partial Voltage and Temperature

Remaining useful life (RUL) prediction is vital to provide accurate decision support for a safe power system. In order to solve capacity measurement difficulties and provide a precise and credible RUL prediction for lithium-ion batteries, two health indicators (HIs), the discharging voltage difference of an equal time interval (DVDETI) and the discharging temperature difference of an equal time interval (DTDETI), are extracted from the partial discharging voltage and temperature. Box-Cox transformation, which is data processing, is used to improve the relation grade of HIs. In addition, the Pearson correlation is employed to evaluate the relationship degree between HIs and capacity. On this basis, a local Gaussian function and a global sigmoid function are utilized to improve the multi-kernel relevance vector machine (MKRVM), whose weights are optimized by applying a whale optimization algorithm (WOA). The availability of the extracted HIs as well as the accuracy of the RUL prediction are verified with the battery data from NASA.

Many-objective optimal power flow problems based on distributed power flow calculations for hierarchical partition-managed power systems

It is more and more challenging to obtain the global optimal power flow (OPF) information of a whole system with the developing trend of power systems toward hierarchical partition-managed ones. Traditional centralized OPF problems are not adaptive to modern partition-managed power systems because of the emergence of distributed sources and multi-stakeholders and the protection of their private data. This paper extends the traditional OPF to a many-objective optimization problem which is helpful to the independent power flow calculation (PFC) of the various subregions in partition-managed networks. To address the coordination of various regions, the individual distributed PFC problem is transformed into a whole optimization problem through node tearing and line disconnection methods, and then the pattern search algorithm is employed to address its solution. Then, the distributed PFC is integrated into the improved NSGA-III (I-NSGA-III) approach to solve the entire many-objective OPF (Ma-OPF) for partition-managed power systems. The effectiveness and feasibility of the proposed distributed approach are demonstrated in multiple benchmarks of IEEE 30/39/118-bus systems and a practical partitioned power system in Guizhou Province of China. The results show that the average voltage difference between distributed PFC and centralized PFC is within 1.12% while the phase angle difference is within 0.44%. In the application of OPF problems, the proposed distributed approach shows the high ability to yield approximate solutions of the original I-NSGA-III with centralized PFC. It is also found from the simulation that the distributed approach shows competitive performance compared to other considered centralized PFC-based evolutionary algorithms and weighted interior point method while it does not require complete information about various regions and is beneficial to the privacy protection of multi-stakeholders.

Photovoltaic MPPT algorithm based on adaptive particle swarm optimization neural-fuzzy control

Since the BP neural network has poor performance and unstable learning rate in the maximum power point tracking (MPPT) algorithm of photovoltaic (PV) system, an adaptive particle swarm optimization BP neural network-fuzzy control PV MPPT algorithm (APSO-BP-FLC) is proposed in this paper. First, the inertia weight, learning factor and acceleration factor of particle swarm optimization (PSO) are self-updating, and the mutation operator is adopted to initialize the position of each particle. Second, the APSO algorithm is used to update the optimal weight threshold of BP neural network, where the input layer is irradiation and temperature, and the output layer is the maximum power point (MPP) voltage. Third, the fuzzy logical control (FLC) is employed to adjust the duty cycle of Boost converter. The inputs of FLC are voltage difference and duty ratio D(n-1) at the previous time, and the output is duty ratio D(n). Moreover, D(n-1) is optimized by |dP/dU| to improve the search range of FLC. The irradiation, temperature and MPP voltage of PV cell are adopted as the datasets for simulation in a city in Shaanxi province, China. Simulation results show that the proposed MPPT algorithm is superior to the APSO-BP, FLC and perturbation and observation (P&O) algorithm with tracking performance, steady state oscillation rate and efficiency. In addition, the efficiency of proposed MPPT algorithm is improved by 0.37%, 6.2%, and 6.8% as compared to APSO-BP, FLC and P&O algorithm.