Series-parallel Combination Research Articles

Experimental investigation on the low temperature performance of a novel three-pressure air source heat pump

As people’s demand for living comfort grows, the problems of conventional air source heat pumps (ASHPs) become more prominent in low-temperature and high-humidity environments: heating performance attenuation, low defrosting efficiency, and significant impact on indoor thermal comfort during defrosting. Existing literature usually focuses on only one or two of these issues, and few comprehensively cover them. Based on current literature, this paper proposes a novel multi-functional three-pressure ASHP that can cover the above three aspects with a series–parallel combination structure featuring dual compressors and dual cycles. This design enables switching multiple heating and defrosting modes through valve combination and improves performance through two-stage throttling and subcooling. An experimental platform is constructed to evaluate its operational performance. The experimental results show that: (1) In heating modes, the average heating capacity of the three-pressure cycle heating mode is 2897.15 W, and the average COP is 2.47, while these two data of the conventional cycle heating mode are 2393.65 W and 2.4, and the improvement rates of 20.4 % and 2.9 %, respectively. It also extends the high-efficiency heating period of the system, enables rapid heating at start-up, increases compressor suction and discharge pressure, and improvs system stability. (2) In defrosting modes, compared with the conventional defrosting cycle, the three-pressure defrosting cycle raises the condensation temperature faster, reduces the defrosting time from 448 s to 265 s (40.8 % shorter). The auxiliary defrosting cycle has little effect on indoor thermal comfort and less defrosting power consumption, with the power saving rate as high as 44.6 %. Overall, the novel three-pressure ASHP has a unique and innovative structure, significantly optimizing performance under low-temperature and frosting conditions and improving energy efficiency and comfort. The results of this study provide a new solution concept for the future development of ASHPs, offering significant reference value for further development and application.

A Novel High-Gain Switched-Capacitor Multilevel Inverter with Reduced Components for Grid Integration

This paper introduces a novel Multi-Level Inverter (MLI) design which utilizes a single input and leverages capacitor voltages source to generate a four-fold increase in output voltage as the main problem that stays with the inverters is their low boost ability and efficiency while maintaining power quality at the same time. One capacitor is charged to match the input voltage magnitude, while the other two capacitors store twice this magnitude. Through a series-parallel combination with switching operations, all capacitors are effectively charged and discharged within each cycle, ensuring natural voltage balance. A comprehensive comparative analysis is conducted to highlight the advantages of this innovative approach, particularly in terms of component reduction and mitigation of voltage stress. Detailed assessment of power losses within the proposed circuit is undertaken, simulation studies are first carried out while extensive experimentation verifies its operational efficiency under diverse conditions such as varying modulation indices, loads, and supply-side fluctuations with an impressive maximum efficiency of 96.9 % at a 200 W power rating, our research contributes to advancing compact power converters, addressing crucial challenges in modern power electronics applications, and paving the way for enhanced performance and reliability in such systems.

Study of Partial Shading Effect on the Different Photovoltaic Array Arrangements and their Shade Resilience

Due to its ability to directly and cleanly convert solar radiation into electricity, the use of photovoltaic (PV) technology is rapidly increasing. Solar PV panels are connected in various series and parallel configurations to achieve the necessary output voltages and currents. They perform optimally when completely unshaded, but when a series connection is partially shaded (PS), bypass diodes activate and the overall voltage drops, resulting in reduced power generation. The location of bypass diodes, series-parallel combination types, and shading patterns all impact the output power. Therefore, selecting the appropriate PV panel arrangement can potentially increase output under these conditions. This study analyzes the shade resilience ability of series-parallel (SP), Total cross-tied (TCT), Bridge-linked (BL), and Honeycomb (HC) configurations.

A multimodal multi-objective differential evolution with series-parallel combination and dynamic neighbor strategy

Multimodal multi-objective optimization problems (MMOPs), which aim to identify as many optimal solutions as possible and exhibit multiple equivalent Pareto optimal solution sets (PSs) that correspond to the same Pareto optimal front (PF), commonly arise in a wide range of optimization problems in the real world. However, some dominated solutions that exhibit greater diversity in the decision space may be substituted by non-dominated solutions with a higher level of decision space crowding. To tackle this issue, this paper proposes a multimodal multi-objective differential evolution with series-parallel combination and dynamic neighbor strategy (MMODE_SPDN), which can balance convergence, objective space diversity and decision space diversity. Specifically, two archives are initially updated serially followed by the overall update of the parallel structure, in which the serial-first approach can enhance population diversity and the parallel structure can greatly reduce the amount of calculation. In addition, a dynamic neighbor strategy which utilizes adaptive selection among neighbors to generate difference vectors in the decision space and objective space and then adopts the main and auxiliary parent method during the mutation process is proposed. Furthermore, the utilization of an auxiliary archive and the clustering-based special crowding distance (CSCD) method are employed to facilitate the updating of the archive, thereby enhancing diversity. MMODE_SPDN is compared with other multimodal multi-objective optimization evolutionary algorithms (MMOEAs) on numerous test problems and the experimental results demonstrate that MMODE_SPDN exhibits superior performance.

Investigation of Electrical Configuration Topologies for Enhancing the Performance of Solar Photovoltaic Water Pumping System

The numerous solar energies provide humans with clean, environmentally friendly, and abundant energy resources. Electricity shortages and high diesel prices have an impact on rural water irrigation systems and drinking water supplies. Solar energy for water pumping could be an alternative to standard electric and diesel pumping systems. The rising importance of solar photovoltaic water pumping systems (SPVWPS) as a feasible power source in rural, inaccessible, and unconnected areas drives the study. These locations, often in poor nations like India, lack conventional power. Solar energy is converted into electrical energy via photovoltaic (PV) technology, which is then used to power a DC or AC submersible or surface water pump. PV module configurations are crucial in improving a PV system’s performance. Many researchers have studied the solar water pumping design on series parallel combination and acquired the best system efficiency, but the other configurations, Total Cross Tied (TCT) and Bridge Link (BL) have never been employed in a solar water pumping system. This research aims to investigate the experimental comparison of different PV configurations for better system efficiency on different operating parameters. These PV array layouts were considered in a uniform situation. The result shows that power increases with increase in radiation and the flow rate provided by (6Sx2P) configuration is 18,956 l/day of water and calculated the best average pump efficiency.

Design and Implementation of a High-gain Switched-capacitor Step-up Multi-level Inverter with Reduced Components Count

Emergence of compact design power converters for applications such as photovoltaic system, active power filter, and high-frequency AC system has introduced multi-level inverters (MLIs). In the last decade, rigorous research has been carried out to transform multi-input MLIs to single-input step-up type that will be extremely beneficial in different applications. The proposed MLI in this work is a reduced components based switched-capacitor MLI. It consists of one input source and using the capacitor voltage, it can produce a four-time step-up output. One of the capacitors is charged to magnitude the input voltage and the other two capacitors are charged to two-time the input voltage magnitude. The charging of all the capacitors is executed by utilizing them in series-parallel combination with the switching operation. By maintaining charging–discharging effectively within each cycle, the voltages are naturally balanced. A thorough comparison is carried to justify the new development in terms of reduction in number of components and voltage stress. The power loss is estimated in the proposed circuit in detail. Extensive analysis is carried out to verify the operational ability and results are provided under different scenarios such as change in modulation index, load, and supply side variations.

Fabrication of pouch cell supercapacitors using abundant coal feedstock and their hybridization with Li-ion battery for e-rickshaw application

The environmental concerns and market demands created high demands of electric vehicles (EVs), but still the energy storage systems are lagging behind the fuel-based vehicles. Even though recent development in battery technologies bring forth great opportunities for EVs, the necessity and a good supply chain of electrode materials, does not fulfill the requirement of EVs. In India, battery-operated e-rickshaws face challenges like insufficient charging facility, low driving range, high battery cost, battery replacement, and disposal. To address the power delivery issues, we have designed and developed an indigenous Hybrid Battery Management System (HBMS) using fabricated coal-based supercapacitors and commercial Li-ion batteries for application in an e-rickshaw. For this study, we have fabricated 500 F pouch cell supercapacitors using high quality activated carbon derived from low-grade coal feedstock which shows excellent properties comparable to the commercially available supercapacitors. Five coal-based pouch cell supercapacitors (500 F) were connected through series parallel combination with commercial supercapacitor (Greencap. 500 F) to make a complete supercapacitor pack of 25 F and 54 V suitable for testing in the e-rickshaw (48 V and 1 kW motor). After implementing the developed hybridized battery management system (HBMS) in e-rickshaw, it showed the maximum speed of 45 km/h with additional power gain of 433 W. The analysis of data showed that the application of coal-based supercapacitors along with Li-ion battery had improved the overall performance of the e-rickshaw. Thus, this study has opened up a new venture of using abundant coal powder in fabricating low-cost pouch cell supercapacitor for using in EVs in a sustainable way that can influence the existing commercial battery market.

Design and Performance Evaluation of an Automatic Dimmable Fault-Adaptive LED Driver Circuit

In this paper, an automatic, fault-adaptive, and dimmable LED driver circuit and LED lamp module is designed and simulated. The designed LED driver can automatically operate and dim (18–72) W LED modules assembled with unknown series-parallel combination of 3 W LED chips on universal AC input (Vrms=(90–265) V, 50/60 Hz). The unique feature of the modelled LED driver circuit is its ability to monitor and detect failure of any connected LED chip and then adapt to provide optimised light output from the LED modules under faulty conditions. The proposed LED driver circuit and LED lamp module are simulated in MATLAB Simulink environment to evaluate the electrical performance. The operation of the simulated LED driver circuit from 100 % to 30 % of rated light output and during occurrence of fault is satisfactory and in compliance with IEC61000–3–2:2014 and IEEE Standard P1789. Input power factor of the simulated LED driver ranges from 0.74 to 0.99, THD from 3.33 % to 30.63 %, and output current ripple from 4.6 % to 20 % under operation of all connected LED modules.

Development of Soil Microbial Fuel Cell for Continuous Real-time Monitoring of Soil Data

The planet is getting hotter due to human activities that release greenhouse gases. Promoting renewable energy, which doesn’t emit carbon, can help mitigate global warming. Farmland, which covers a large portion of the Earth’s land area, can also be used as an energy source through the help of indigenous microorganisms in the soil that transform chemical energy into electrical energy with electrolysis. Real-time monitoring of soil nutrients is necessary to obtain an accurate yield from crops. This is achieved with the use of sensors that are powered by the energy generated from the soil. Zinc and copper electrodes are used to generate power, and a combination of 15x6 cells is used to maximize voltage and current generation. The output powers soil sensors like FC-28 and NPK sensors, and the data is sent to the AWS cloud for real-time monitoring of soil parameters. The experimental results show that a single SMFC cell generates 0.6V, while a series-parallel combination generates approximately 9V. By using a current booster circuit, the efficiency of the setup can be further improved. This technology is not yet widely used in the agricultural industry, but it has the potential to help farmers conveniently monitor soil conditions by utilizing the power generated from the soil itself.

Parameter Identification Model and Capacity Analysis of Retired Power Battery

The accuracy and connection mode of the equivalent model of retired power battery cells will affect the size of the combined capacity. To this end, this article analyzes series-parallel combination capacity of retired power batteries. First, because an accurate single equivalent circuit model of retired power batteries is necessary for the capacity analysis of the combination, the forgetting factor recursive least squares (FFRLS) algorithm is used to identify the parameters of the model, and the second-order RC equivalent circuit is selected as the single equivalent circuit model of retired power battery. Then the equivalent circuit model is used as the basis, respectively constructing first-parallel-before-series and first-series-before-parallel power battery combination, and fully and unequally arranged the retired power batteries under the two assemblies. Finally, the capacity and distribution characteristics of the two combinations under different arrangements are verified by simulation. The results show that no matter how the arrangement is changed, the maximum capacity of the first-parallel-before-series retired power battery combination is always better than the first-series-before-parallel combination, and the distribution position of the single retired battery in both combinations under the maximum combination capacity is obtained.

Design of portable multi-channel isolated CNC-regulated power supply

In order to facilitate the testing needs of electronic engineers, a multi-channel isolation adjustable switching regulated power supply controlled by an STM32 single-chip microcomputer is designed [1]. The power supply is programmable and adjustable by a single-chip microcomputer, and the humanized display operation interface is combined with the high efficiency of switching the power supply. It can realize three channels of 30v2a isolated output, and realize one channel of 90v2a or 30v6a output through a relay automatic switching series-parallel combination, to maximize power density. The power supply has the characteristics of high integration, small volume, large power, large adjustable range, high precision, and high efficiency. It can be applied to the debugging and operation of most electronic equipment.

Fragility Study of Buried Pipeline Networks Based on Copula Function

The seismic fragility of water supply networks is an important research component for lifeline engineering in earthquake-prone regions. An accurate computational model was established to rapidly and efficiently assess pipeline damage under seismic excitation. In this study, the fragility of the pipeline network is deduced based on Copula function technology and the series-parallel model. This solves the low accuracy problem caused by simplifying elbow, tee, and other nodes and ignores the correlation between connected components in the fragility calculation of the buried pipeline network. Then, the shaking table tests of the elbow pipe, tee pipe, and scale pipeline network are performed, and the prototype pipeline network’s finite element comparative calculation model is also established. Then, the optimal Copula function for the pipeline network, the Gumbel Copula function, is obtained by calculating the correlation between each component’s seismic demand. It was found that the seismic demand of pipe and elbow components in the sand is higher than that in the clay, while the opposite is valid for the tee component. After that, a two-parameter log-normal distribution is employed to obtain the seismic fragility of three types of components in different soil properties. It was also found that the maximum failure probability can be obtained from the elbow leakage. The fragility of the elbow pipe is greater than that of the tee pipe. The fragility of components is then applied to the fragility calculation of the scale pipeline network by a series-parallel model, and the obtained results are compared with numerical simulations. It is demonstrated that the series-parallel combination calculation-based results have a high safety reserve for the pipeline design.

Efficient integrated 5 × 2 rectenna array for low RF energy recovery

The present study provides a series–parallel combination of connected rectenna arrays using SMS7621-001LF Skyworks Schottky diodes at 5.8 GHz to harvest wireless systems’ power. The proposed configuration is an array of patch antennae with a rectifying circuit, while in the array connection, the rectenna system works with the most optimal conversion efficiency. Based on the results obtained from the fabricated proposed rectenna’s optimal efficiency, an RF power density ranging from 30 to 160 µW/cm2 has been obtained. Also, the conversion efficiency of RF-to-DC power is more than 77%. The measured output DC voltage of 10 elements in a parallel-series connection is 9.1 V, and their output current has been measured at 130 mA. The highest power conversion efficiency in the proposed rectenna system is 75.2 at a power density of 90 µW/cm2. The conversion efficiency is almost constant in this rectenna as the number of elements increases. Also, during this experiment, it was proven that the addition of a rectifier to the receiving antenna has not only a very small effect on the radiation efficiency but also has not much effect on the features of the main beam of the antenna system. The prototype unit cell rectenna and array are fabricated, and their performance is validated using measurements.

Fabrication and thermoelectric conversion of thermoelectric concrete brick with buried unileg N-type CaMnO3 thermoelectric module inside

To investigate the effect of heat loss reduction due to thermal insulator and thermal interface resistance due to multi-layer structure in order to improve the efficiency of a thermoelectric device, a thermoelectric concrete brick was fabricated using a unileg n-type CaMnO3 thermoelectric module inside. CaMnO3 thermoelectric materials were synthesized by starting materials CaCO3 and MnO2 to produce a unileg n-type CaMnO3 module. Thermoelectric concrete brick consisted of two types: I-layer brick (one layer of concrete thermal insulator) and III-layer brick (three layers of different concrete insulators). The occurring temperature difference, electric current and voltage on the CaMnO3 module and thermoelectric concrete brick were measured in closed and open circuits. The temperature difference, thermal distribution, and output voltage when applying constant temperatures of 100, 200 and 400 °C were measured. Computer simulations of the Finite Element Method (FEM) were performed to compare with the experimental results. The trends of the temperature difference and the output voltage from the experimental and computer simulations were in good agreement. The results of the temperature difference during the hotter side temperature of 200 °C exhibited the temperature difference along the vertical direction of the thermoelectric concrete bricks for both types of the III-layer brick of 172 °C and the I-layer brick of 132 °C are larger than that of the CaMnO3 TEG module without using a thermal concrete insulator of 108 °C. The thermoelectric concrete bricks of the III-layer brick type of 27.70 mV displayed output voltage results being higher than those of the I-layer brick of 26.57 mV and the CaMnO3 TEG module without using a thermal concrete insulator of 24.35 mV. Thermoelectric concrete brick of the III-layer brick type displayed higher electric generation power than the I-layer brick and the CaMnO3 TEG module. Additionally, the results exhibited the capability of thermoelectric concrete brick in the III-layer brick model for electric generation power based on the temperature difference. The TEG concrete brick of I-layer concrete covering the series–parallel combination circuit of 120 modules of the unileg n-type CaMnO3 was constructed and then embedded on the outer surface of the furnace. During the maximum hotter side temperature of 580 °C of the concrete brick, the temperature difference between the hotter side and the cooler side of the brick occurred at 365 °C and the maximum output voltage was obtained at 581.7 mV.

Decentralized DC solar power system for remote areas

The emission of CO2 by industries and automobiles creates a problem like global warming. Especially in areas nearby mega-cities, the concentration of CO2 is increasing by a considerable level. The existing setup of electricity generation is centralized which generates electricity centrally in one place and it is transmitted everywhere. Decentralized DC solar power is the newest innovation in the field of renewable energy especially in solar energy to give more efficiency for casual and residentially applications. By utilizing the series–parallel combination of solar panels we can make our off-grid power system. This off-grid power system is the best power system for those families whose power requirements are less and some villages which are apart from centralized power communities. One approach is to generate power at a place where we need it. As we know that solar panel generates DC Voltage and we can develop a 12 V or 24 V DC system, which does not require conversion from AC to DC. This paper is mainly for Off-grid power generation and awareness for future research in the field of renewable, pure, and Off-grid DC solar power.

Rapid Identification of Interwell Fracture-Cavity Combination Structure in Fracture-Cavity Reservoir Based on Tracer-Curve Morphological Characteristics

Rapid and effective identification of interwell fracture-cavity composite structures is a necessary prerequisite for a detailed and in-depth understanding of interwell connectivity in fracture-cavity reservoirs. Current identification methods and technologies have the problems of being large-scale and low-resolution; in view of these problems, a method is proposed for rapidly identifying interwell fracture-cavity combination structures using tracer-curve morphological characteristics (peak number and characteristics of two wings). Based on concentration models of tracer curves for an interwell single fracture/pipe/cavity, the morphological characteristics of tracer curves were researched in five different series-parallel combination modes consisting of fractures, pipes, and cavities. The tracer curves of fracture-cavity reservoirs are categorized into three types: single sharp peak, single slow peak, and multipeak. Furthermore, a matching relationship between different fracture-cavity combination structures and the morphological characteristics of tracer curves is clarified. The single-sharp-peak curve with basically symmetrical wings reflects that of an interwell single fracture/pipe; the single-slow-peak curve with a steep ascending branch and a slow descending branch (obvious trailing phenomenon) reflects that of an interwell single cavity or fracture/pipe series cavity; the multipeak curve reflects that of an interwell multifracture/pipe/cavity in parallel; according to the flow difference of each branch flow channel, they can be divided into independent multipeak and continuous multipeak forms. Taking tracer monitoring results from a well group in the Tahe oilfield as an example, field application analysis and verification were carried out. The results show that this method is simple and reliable and can provide a fast and effective means for identifying interwell fracture-cavity combination structures. Meanwhile, the research results can lay a foundation for quantitative interpretation modeling of interwell tracers in fracture-cavity reservoirs considering fracture-cavity configuration.

Energy harvesting from pedestrian movement using piezoelectric material

With the lapse of time, attempts are being made to find out alternative materials as sources of energy to meet the increasing energy demand. Present work aims at energy harvesting from pedestrian movement over piezoelectric material with or without rubber strips. Pedestrian data have been collected from six locations of Agartala city, India. To get more power, mechanical damping is kept low using piezo embedded rubber strips. Piezoelectric materials embedded with rubber strips yield better results than that without rubber strips. Piezoelectric materials connected in Series Parallel Combination (SPC) give better results compared to Parallel Series Combination (PSC). Sensitivity analysis shows that pressure level and walking speed significantly affect the voltage generation. The energy generated by this process can be stored up in super capacitors that meet minor energy requirements such as lighting a small powered LED light on the roadside, charging mobile phones etc.

The Manufacturing Planning of Installation Series-Parallel Combination Centrifugal Pump Testing Equipment

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.

Design of Energy Storage Photovoltaic Power Generation Device and Neural Network Method for Photovoltaic Power Prediction

The series-parallel combination of the photovoltaic array can meet the needs of different applications such as high power or low power with the continuous optimization of photovoltaic cell materials and the increasing improvement on efficiency of photovoltaic cell. This exploration takes the independent photovoltaic power generation (PPG) device as the research goal. The system includes a photovoltaic array, Boost rectifier, single-phase photovoltaic inverter, battery and bi-directional DC/DC converter. Single-phase photovoltaic inverter is employed for the AC load power supply, and a lead-acid battery is adopted for energy storage. Buck mode and Boost mode are modeled respectively based on the analysis of the converter topology, and the designed model is employed to control the converter. Back propagation neural network (BPNN) is introduced to analyze the factors which can affect the output power of PPG. In experiment, the effective value of output voltage, output voltage, and current waveform of single-phase inverter are analyzed. The analysis results show that the output voltage changes suddenly with the load, and the device can be followed again within a few milliseconds, which means that the device has good dynamic performance. The corresponding output frequency fluctuates at a small amplitude (±1%) when the output voltage is above 220 V. Meanwhile, the distortion of the output waveform is less than 1%. The ripple coefficient of the output voltage is less than 1% when the operating mode of PPG (boost and Buck) is changed. The neural network is introduced to select the appropriate parameters (irradiation intensity, relative humidity, ambient temperature and wind speed), and the results show that the environmental temperature exerts a great influence on the output power of PPG.

Assessing The Change In Voltage In Citric Fruit Lemon Due To Ageing

In this study citric fruit lemon was used for generation of electricity. The lemon fruit can be used as such or in crushed form. In order to achieve higher voltages, we connected more number of fruits in series. For higher magnitude of current we have to connect lemon in parallel and for increased voltage and current we have to connect lemon in series parallel combination. Here we used citrus fruits, wires and electrodes for performing the experiment. The out is connected to LED to check the output. Output voltage is measured in various conditions using Multimeter. The various conditions under study are raw lemon, ripe lemon, aged lemon. The assumption was due to ageing the magnitude of voltage and current decreases. It is found that raw and ripe lemon gives better output voltage compared to aged lemon. More the age of the lemon lesser is the magnitude of voltage. This method can be used not only for power generation using citric fruit lemon but also after power generation it can be used as natural manure. More over this method does not cause any pollution or global warming. As the magnitude of the current and voltage is small the output can be used for working of devices which operates in low voltage and current thereby reducing the usage of pollution causing batteries.