Search Results (143)

In this paper, a robust optimized controller is implemented in the photovoltaic generator system (PVGS). The PVGS is composed of individual photovoltaic (PV) cells, which convert solar energy to electrical energy. To optimize the efficiency of the PVGS under variable solar irradiance and temperatures, a maximum power point tracking (MPPT) controller is necessary. Additionally, the PVGS output voltage is typically low for many applications. To achieve the MPPT and to gain the output voltage, an increasing boost converter (IBC) is employed. Then, two issues should be considered in MPPT. At first, a smooth control signal for adjusting the duty cycle of the IBC is important. Another critical issue is the PVGS and IBC unknown sections, i.e., the total system uncertainty. Therefore, to address the system uncertainties and to regulate the smooth duty cycle of the converter, a robust dynamic sliding mode control (DSMC) is proposed. In DSMC, a low-pass integrator is placed before the system to suppress chattering and to produce a smooth actuator signal. However, this integrator increases the system states, and hence, a sliding mode observer (SMO) is proposed to estimate this additional state. The stability of the proposed control scheme is demonstrated using the Lyapunov theory. Finally, to demonstrate the effectiveness of the proposed method and provide a reliable comparison, conventional sliding mode control (CSMC) with the same proposed SMO is also implemented. Full article

Conventional continuous pesticide application remains prevalent in agriculture, but its limitations in addressing the spatial–temporal variability of biotic stressors have led to excessive chemical inputs and inefficiency. The emergence of precision agriculture has catalyzed significant advancements in variable-rate spray systems to optimize agrochemical deployment through real-time modulation. This technology demonstrates critical advantages in minimizing the environmental footprint while maintaining crop protection efficacy. Our systematic review analyzes three foundational variable-rate spray architectures—pressure-regulated, flow rate-regulated, and pesticide concentration-regulated mechanisms—evaluating their maturity and implementation paradigms. Pressure-regulated technology relies on the pressure–flow relationship to achieve regulation, but there is a narrow range in flow regulation, atomization stability is insufficient, and there are other defects. Flow rate-regulated technology achieves precise control through the dynamic adjustment of the nozzle orifice area or Pulse-Width Modulation duty cycles, but this technology faces mechanical wear, a nonlinear flow–duty cycle relationship, and other challenges. Pesticide concentration-regulated technology is centered on real-time mixing, which can avoid the residue of chemicals but is highly dependent on fluid characteristics and mixing efficiency. This study proposes improvement paths from the perspectives of hardware optimization, control strategy integration, and material innovation. Through the summary and analysis of this paper, we hope to provide valuable references for future research on variable-rate spray technology. Full article

With the growing demand for high-efficiency DC-DC converters with a wide input voltage range for wireless power transmission, four-switch boost converters (FSBBs) are attracting attention due to their low current stress and flexible mode switching characteristics. However, their complex operating modes and nonlinear dynamic characteristics lead to high switching losses and limited efficiency of the system under conventional control. In this paper, an optimization algorithm is combined with the multi-mode control of an FSBB converter for the first time, and a combined optimization and voltage closed-loop control strategy based on the Whale Migration Algorithm (WMA) is proposed. Under the four-mode operation conditions of the FSBB converter, the duty cycle and phase shift parameters of the switching devices are dynamically adjusted by optimizing the values to maximize the efficiency under different operation conditions, with the premise of achieving zero-voltage switching (ZVS) and the optimization objective of minimizing the inductor current as much as possible. Simulation results show that the proposed FSBB switching control strategy combined with the WMA algorithm improves the efficiency significantly over a wide voltage range (120–480 V) and under variable load conditions, and the transfer efficiency is improved by about 1.19% compared with that of the traditional three-mode control, and the maximum transfer efficiency is 99.34%, which verifies the validity and feasibility of the proposed strategy and provides a new approach to the high-efficiency control and application of FSBB converters. Full article

The power output of a photovoltaic (PV) system is inherently dependent on climatic factors. To maximize the energy harvested from PV arrays, maximum power point tracking (MPPT) algorithms are employed. These algorithms dynamically adjust the operating point of the system to extract the maximum available power. However, under partial shading conditions (PSCs), conventional MPPT algorithms often fail to locate the global maximum power point, leading to suboptimal power extraction. In this study, a robust MPPT technique based on sliding mode control (SMC) is proposed to enhance tracking efficiency and optimize power extraction from PV arrays under PSC. Particle swarm optimization (PSO) is incorporated into the MPPT framework, enabling the dynamic tuning of SMC parameters for improved adaptability and performance. The proposed SMC structure is designed to regulate the duty cycle of a boost converter, ensuring effective power conversion. The system is simulated in Matlab/Simulink for various PSCs. The simulation results demonstrate that the PSO-tuned SMC methodology exhibits superior tracking performance, enabling the PV system to rapidly and accurately converge to the true MPP under varying weather and shading scenarios. The findings indicate that the proposed technique enhances the efficiency and reliability of PV energy harvesting in PSCs. Full article

Applications of wireless sensor networks have significantly increased in the modern era. These networks operate on a limited power supply in the form of batteries, which are normally difficult to replace on a frequent basis. In wireless sensor networks, sensor nodes alternate between sleep and active states to conserve energy through different methods. Duty cycling is among the most commonly used methods. However, it suffers from problems like unnecessary idle listening, extra energy consumption, and packet drop rate. A Deep Reinforcement Learning-based B-MAC protocol called (RL-BMAC) has been proposed to address this issue. The proposed protocol deploys a deep reinforcement learning agent with fixed hyperparameters to optimize the duty cycling of the nodes. The reinforcement learning agent monitors essential parameters such as energy level, packet drop rate, neighboring nodes’ status, and preamble sampling. The agent stores the information as a representative state and adjusts the duty cycling of all nodes. The performance of RL-BMAC is compared to that of conventional B-MAC through extensive simulations. The results obtained from the simulations indicate that RL-BMAC outperforms B-MAC in terms of throughput by 58.5%, packet drop rate by 44.8%, energy efficiency by 35%, and latency by 26.93% Full article

The distribution of light within a microalgal culture and the choice of the best wavelengths are considered the most critical aspects in the scale-up of microalgal culture. Several studies have investigated these features, resulting in a substantial body of literature that analyzes the effects in terms of an increase in biomass production or shift in its composition. This work addresses two types of light quality adjustments: the application of flashing light and shifts in light wavelength. The effects on microalgal culture are examined. Later, the application of these light features to photobioreactor design is described. Specifically, three kinds of photobioreactors are examined: (1) reactors designed to minimize light gradients, (2) reactors where the geometry produces a flashing light effect on the cells and (3) reactors that use filters to obtain a shift in the sunlight wavelength. The results showed that both the effect of flashing lights and wavelength shift strongly depends on various parameters such as the alga taken into consideration, the light intensity, the agitation type, growth medium, light intensity and temperature and, regarding the flashing light also, the frequency and the duty cycle. Despite all these specific differences, this work aims to resume and provide specific instruments for choosing operational parameters in microalgal cultivation and in photobioreactor design to achieve targeted outcomes, such as an increase in biomass production or in high-value compound accumulation. Full article

This paper proposes a combined maximum efficiency tracking and improved active disturbance rejection control (ADRC) strategy for an inductive power transfer (IPT) system, addressing issues of reduced efficiency and voltage fluctuations under load variations. The transmission characteristics of the inductor–capacitor–capacitor and series (LCC-S) IPT system are analyzed, and the relationship between transmission efficiency and the secondary DC-DC converter’s duty cycle is derived. Maximum efficiency tracking is achieved by adjusting the secondary converter’s duty cycle via the primary side Buck converter. An improved ADRC controller enhances dynamic voltage regulation by reducing the extended state observer’s order and incorporating model information for better disturbance compensation. Experimental results show that the proposed approach improves average transmission efficiency by 12% and maintains constant output voltage under varying loads. The controller requires fewer parameters than linear active disturbance rejection control (LADRC), with faster responses and smaller voltage fluctuations than PI and LADRC controllers. Full article

This paper proposes a mechanically reconfigurable multi-polarization antenna based on a 3D-printed anisotropic dielectric polarizer, offering wide bandwidth, high gain, and extremely low cost. The working mechanism of the dielectric polarizer is analyzed, demonstrating its ability to efficiently convert linear polarization (LP) to circular polarization (CP) over a wide frequency range. Furthermore, the polarizer exhibits subwavelength characteristics. For a given duty cycle, its phase response depends only on the height and is independent of the aperture size. This property enables miniaturized and customized designs of the polarizer’s aperture size. Subsequently, the polarizer is placed above a Ku band waveguide and standard horn antennas. The results show that by rotating the dielectric polarizer and adjusting the positions of the antennas, right-handed CP (RHCP), left-handed CP (LHCP), and dual LP radiation switching can be achieved in the 12.4–18.0 GHz band, verifying the quad-polarization reconfigurability. Additionally, the polarizer significantly enhances the gain of the waveguide antenna by approximately 9.5 dB. Furthermore, due to the low-cost 3D printing material, the manufacturing cost of the polarizer is exceptionally low, making it suitable for applications such as anechoic chamber measurements and wireless communications. Finally, the measurement results further validate the accuracy of the simulations. Full article

The diverse array of sensors deployed on meteorological observation towers, tasked with the observation of meteorological gradients, requires distinct power supplies and effective power regulation. In this article, a multi-frequency, multi-receiver (MFMR) inductively coupled power transfer (ICPT) system using a time-sharing frequency strategy is proposed, which enables coupled power transfer to multiple nodes through only one cable. The time-sharing frequency control (TSFC) method is introduced to produce time-sharing multi-frequency currents. By incorporating a controllable resonant capacitor array at the transmitter, the system can operate at various resonance frequencies over specific intervals, allowing it to supply power to multiple loads with unique resonance frequencies. First, an in-depth analysis of the power transmission characteristics of MFMR-ICPT systems is conducted, with the three-frequency, three-receiver (TFTR) ICPT system circuit serving as an example. The frequency cross-coupling effects are then analyzed, and the TSFC method is explained. Finally, experiments are conducted on a TFTR-ICPT system. The results demonstrated that independent power regulation of multiple loads could be achieved by adjusting the duty cycle of different frequency input voltages through the time-sharing frequency strategy. The system achieved a total power output of 38.7 W, with an efficiency of 64.8%. Full article

Electrolysis, which uses direct current, is the most common way to produce hydrogen gas. However, its efficiency is very low, about 70%. The method used when current pulses are used by electrolysis is called pulse electrolysis. According to other studies, this method can increase the efficiency of the production of hydrogen gas by the electrolysis of water. The main objective of this paper is to present a prototype of a converter that provides current pulses with specific parameters. This converter can produce positive and negative pulse-modulated current pulses of defined amplitude and duty. Also, the number of positive and negative pulses in one working cycle is adjustable. This converter’s design enables us to research pulse water electrolysis, its electrical behavior, and the possibilities of increasing the efficiency of the electrolysis process. While this paper focuses on the development of the prototype for future research, the technology could be extended to other applications requiring precise current pulse control. Full article

This article proposes a robust dual-vector model predictive control (RDVMPC) strategy for high-power three-level inverters, specifically designed to optimize current harmonics. By extending the concept of total harmonic distortion (THD) to the entire time domain, the current deviation is redefined, and a novel cost function is formulated. The proposed strategy incorporates dual-vector control to maintain a fixed switching frequency while optimizing the sequences and duty cycles of the vectors to further mitigate THD. A novel ultra-local model is employed to eliminate dependency on precise system parameters, with unknown components accurately estimated through an extended state observer (ESO) equipped with an adaptive bandwidth gain mechanism. This mechanism dynamically adjusts to enhance disturbance rejection under parameter variations and suppress noise under steady-state conditions. The efficacy of the proposed method is substantiated through simulations and experimental validation on a 10 kW T-type inverter, demonstrating significant improvements in harmonic reduction and overall system performance. Full article

This paper aims to demonstrate the energy efficiency improvements in a boost converter using supercapacitors and the Perturb and Observe (PO) control method, particularly in the context of photovoltaic (PV) systems under partial shading conditions. Supercapacitors, known for their high energy density and rapid charge/discharge capabilities, are integrated into the boost converter circuit to mitigate voltage fluctuations and enhance energy storage efficiency. The PO control method is utilized to dynamically adjust the duty cycle of the MOSFET, ensuring the output voltage remains stable at the desired level of 70 V, with an input voltage range of 30 V to 60 V. This study employs simulation techniques to evaluate performance improvements, focusing on energy efficiency and system stability when supercapacitors are used as filtering elements alongside advanced control strategies in PV systems experiencing partial shading. Simulation results indicate a significant reduction in voltage ripple and enhanced overall system efficiency, achieving a stable output voltage of exactly 70 volts. Specifically, the efficiency of the boost converter without a supercapacitor and Zener diode is 8.36%, while the configuration with a supercapacitor and Zener diode achieves 16.09% efficiency. Most notably, the configuration with a supercapacitor and without a Zener diode achieves an efficiency of 50.29%. The findings conclude that integrating supercapacitors and the PO control method in boost converters for PV applications substantially enhances energy efficiency and system stability, even under partial shading conditions. Full article

High-frequency transformers are subject to excitation with a changing duty cycle during operation. Due to magnetic relaxation, the duty cycle of the rectangular wave affects the magnetization time of nanocrystalline alloy for the core material, which affects whether the transformer can reach the saturation operating point. Based on the micromagnetic theory, a three-dimensional model of the nanocrystalline alloy is established, and rectangular wave excitation with different duty cycle D is applied to the micro-model. The influence of D on the magnetization process is analyzed in terms of the hysteresis loss P_v and magnetic moment deflection angular velocity ω. The results indicate that when D = 0.5, P_v is the smallest, and when D increases or decreases, P_v increases. Furthermore, P_v remains the same under the rectangular wave excitation that satisfies the sum of different duty cycles of 1. Regarding ω, the smallest value occurs at the rising edge of the excitation when D = 0.1, while the largest value occurs when D = 0.9. During the falling edge stage, ω is smallest when D = 0.9 and largest when D = 0.1. These results demonstrate that the duty cycle D influences the magnetization time of the material. Due to magnetic relaxation, changing the magnetization time determines whether the material can reach saturation magnetization. Therefore, there is a critical state, which is defined as the critical duty cycle D_c. The results show that for D < 0.5, the range of D_c1 is between 0.2 and 0.21, and for D > 0.5, the range of D_c2 is between 0.8 and 0.81. Increasing the amplitude of the excitation source causes a decrease in D_c, while increasing the frequency causes an increase in D_c. Full article

This paper proposes a model predictive control (MPC)-based approach for optimizing the performance of a photovoltaic (PV) system. The proposed method employs finite voltage-set maximum power point tracking (FVS-MPPT), ensuring precise duty cycle adjustment for a boost converter in the PV system considering the environmental changes in irradiation and temperature. Additionally, MPC is implemented for the grid-side converter to determine the optimal switching vector, ensuring precise control of active power via reference d-axis current and the elimination of reactive power by setting the reference q-axis current to zero. This approach optimizes the converter’s performance, maintaining a stable DC-link voltage while ensuring efficient grid integration. To ensure proper synchronization with the grid, a phase-locked loop (PLL) is utilized to provide the necessary grid voltage angle for dq frame transformation. Simulation results highlight the efficiency of the proposed MPC strategy, with the PV-side converter showing a robust response by dynamically adjusting the duty cycle to maintain optimal performance under varying irradiation and temperature conditions. Furthermore, the grid-side converter ensures precise control of active power and eliminates reactive power, enhancing the overall system’s stability and efficiency during grid interactions. A functional comparison of simulation results between the conventional P&O algorithm and the FVS-MPPT approach is presented, demonstrating the enhanced performance of the proposed technique over the conventional method including the total harmonic distortion for both techniques. Full article

This paper presents a novel driving torque control strategy for the front and rear independently driven electric vehicle (FRIDEV) to reduce energy consumption and enhance vehicle stability. The strategy is built on a comprehensive vehicle model that integrates vertical load transfer, tire slip dynamics, and an electric system model that accounts for losses in induction motors (IMs), permanent magnet synchronous motors (PMSMs), inverters, and batteries. The torque control problem is framed with a nonlinear model predictive control (MPC) method, utilizing state-space equations as representations of vehicle dynamics. The optimization targets adjust in real-time based on road traction conditions, with the slip rate of front and rear wheels determining the torque control strategy. Active slip control is applied when slip rates exceed critical thresholds, while under normal conditions, torque distribution is optimized to minimize energy losses. To enable online real-time implementation, an improved sparrow search algorithm (SSA) is designed. Simulations in MATLAB/Simulink confirm that the proposed online strategy reduces energy consumption by 2.3% under the China light-duty vehicle test cycle-passenger cars (CLTC-P) compared to a rule-based strategy. Under low-adhesion conditions, the proposed online strategy effectively manages slip ratios, ensuring stability and performance. Improved SSA also enhances computational efficiency by approximately 44%–52%, making the online strategy viable for real-time applications. Full article