Output Efficiency Research Articles

Self-sufficient power plant prototype composed by cascaded disruptive power units doing work by isothermal contraction and expansion

This research work aims at the design and development of a disruptive prototype for a Self-sufficient power plant (SSPP) prototype composed by cascaded disruptive power units (PUs) doing work by isothermal contraction-expansion processes. The innovative design integrates thermo-hydraulic actuators enabled to drive hydraulic pumps connected to a hydraulic motor-generator. The prototype's cascaded PUs operates on a double closed processes-based isochoric-isothermal-isochoric-isothermal (VTVT) thermal cycle, enabled to do useful work by contraction and expansion of a thermal working fluid (TWF), which is notable for its high specific work output and high thermal efficiency. This is due to a disruptive cascaded heat recovering technique associated to a heat upgrading strategy. Among the most relevant Key Features are its self-sufficient operation modes that challenge traditional limitations of second-kind perpetual motion machines (PMMs) The expected capabilities on the basis of the consistency of empirical analysis are summarized as: - Design based on the optimal number of cascaded power units, - Efficient generation of useful mechanical work through expansion and contraction of the TWF, - High specific useful work (kJ/kg of TWF), such as helium, - Low ratio of actuator volume and weight to specific work. Preliminary tentative validation: The prototype design model was validated through case studies using air and helium as real TWFs. Empirical results demonstrate the SSPP's exceptional performance under certain conditional restrictions. - The optimal SSPP completed with nine cascaded PUs each operating on a double-VTVT cycle per PU. - Helium: RIT value of 0.9 and 9 PUs coupled in cascade to give an SSI of 156.72and a SSEP yield of 922.23 kJ/kg.cy. - Air: RIT value of 0.9 and 9 PUs coupled in a shell to give an SSI of 27.41 and a SSEP production of 37.67 kJ/kg.cy. These findings highlight the prototype's potential to significantly advance energy production efficiency and self-sufficiency in power generation systems.

Theoretical kinetics with one-dimensional fluid model and experimental investigation on coaxial XeCl excilamps

Abstract This paper presents a one-dimensional homogenous model of high power-density XeCl excilamp pumped by dielectric barrier discharge (DBD) with larger discharge gap and lower Cl2 density in Xe/Cl2 mixture, to research the electrical and chemical discharge characteristics leading to the production of XeCl* molecules for the optimal discharge parameters. The peaked wavelength 308 nm from the emission band of XeCl* exciplex molecules, show great promise as photochemotherapy for biomedicine applications. The temporal evolutions of the plasma voltage, current density and the species densities have been analyzed. The model validity has been checked by comparing with the experimental results. It is shown that the XeCl excilamp is a capacitive discharge during the entire voltage cycle and the accumulation of charge deposited in the dielectric surfaces play an extreme role in promoting the extinction of this discharge and the generation of next discharge. The UV radiant efficiency of the DBD XeCl excilamp depends on effect of the discharge behavior on the amplitude of the applied voltage, the total gas pressure, and the Cl2 density. XeCl excilamp has an optimized pressure around 150 mbar with the maximum radiant efficiency of 8.5% for 308 nm from XeCl* molecules and 1.3% for 172 nm from Xe2* molecules. According to the corrected simulation, the radiant efficiency of the optimum pressure is 6.0% for XeCl*molecules. Cl2 density in DBD-based XeCl excilamp strongly influence the balance of electron production and loss due to the dominant dissociative attachment process of electrons to Cl2 molecules, which have significant dependence on the UV light output efficiency. It is demonstrated that the highest XeCl* density occurs near the dielectric during the current pulse. Therefore, electrical and radiant characteristics of XeCl excilamps can be considered as the basis to design the high power-density exciplex lamps in practical applications.

Energy management strategy for fuel cell hybrid tractor considering demand power frequency characteristic compensation.

The application of fuel cell tractors is expected to drive technological upgrades and sustainable development in agricultural machinery. However, fuel cell hybrid systems face issues such as slow dynamic response, low efficiency, and short lifespan. This paper proposes an energy management strategy based on signal reconstruction methods, including Empirical Mode Decomposition (EMD) and Variational Mode Decomposition (VMD), to achieve optimal energy utilization and system efficiency based on frequency response characteristics. First, we collected data on the tractor's traction force and operating speed, and calculated the required traction power using a full-machine dynamics model built in MATLAB software. We conducted frequency response characteristic analysis of the fuel cell hybrid system based on EMD and VMD, establishing an energy management controller to sequentially meet the average power demand of the fuel cell under plowing load operations, the instantaneous acceleration power demand of the power battery, and the real-time compensation power demand of the supercapacitor. The results show that the EMD strategy exhibits good stability, while the VMD strategy performs better in terms of hydrogen consumption. Under the VMD strategy, the hybrid system achieves a maximum output efficiency of 55.0% with a total hydrogen consumption of 750g. Compared to the EMD strategy, the maximum efficiency of the system increases by 27.31%, and hydrogen consumption decreases by 3.49%. This study provides a new theoretical foundation and technological route for the application of fuel cell hybrid systems in the field of agricultural machinery.

Magnetic PDMS@SiO2/Fe3O4 Composite Friction Layer Material for Enhanced Friction Nanogenerator Output Performance

Triboelectric nanogenerators (TENG) have exhibited remarkable potential in harnessing stochastic low-frequency mechanical energy from oceanic surfaces, attributed to their versatile architectures and capability for extensive deployment. Nonetheless, the relatively modest power output per unit area remains a critical limitation impeding the advancement of TENG technology. Consequently, the innovation of novel material systems and devices to augment the output performance and efficiency of TENG is paramount in achieving effective ocean energy exploitation. In our study, a vertical contact PC-TENG was utilized as an energy harvester, with the incorporation of magnetic nano-oxide particles to bolster the output efficiency of TENG. This investigation represents the inaugural application of SiO2 and Fe3O4 nanoparticles within PDMS negative friction layers. This strategy augments the specific surface area, thereby improving the contact between the friction materials and enhancing charge transfer efficiency. Moreover, the magnetic properties of Fe3O4 facilitate charge separation on the material's surface, culminating in an elevated voltage output. Comprehensive characterizations were conducted using SEM, FTIR, electrometer, and contact angle meter, while simulations were corroborated with COMSOL Multiphysics field simulation software. The output performance witnessed optimization through the incorporation of Fe3O4, culminating in a peak open-circuit voltage (VOC) of 85.1212 V, a maximum short-circuits current (ISC) of 8.4037 μA, and a maximum transferred charge (QSC) of 0.5638 nC, reflecting enhancements of 28%, 32%, and 27%, respectively, compared to conventional PDMS materials. The peak output power, achieved with an impedance match of 55 MΩ, was recorded at 19.03 mW, marking a 70.8% improvement in output performance. The findings revealed that the contact angle of PDMS@SiO2/Fe3O4 composites reached 100.092°, enhancing hydrophobicity by 8% relative to traditional PDMS materials, thereby rendering it more suitable for humid environments. COMSOL Multiphysics field simulation results further substantiated the viability of the PDMS@SiO2/Fe3O4 composite friction layer material for applications in oceanic wave environments. Ultimately, a rectifier bridge was introduced to convert the alternating current generated by the PC-TENG into direct current. This research offers a novel paradigm for the utilization of TENG in the realm of marine energy.

Geothermo-mechanical energy conversion using shape memory alloy heat engine

AbstractThe shift towards renewable energy sources like geothermal energy has become desirable due to the recurrent energy crisis and global warming challenges influenced by fossil fuels. Geothermo-mechanical energy conversion using shape memory alloy (SMA) heat engines presents a novel and sustainable approach for harnessing geothermal energy. Shape memory alloys, known for their ability to undergo reversible phase transformations driven by temperature changes, are ideal for thermal-to-mechanical energy conversion. This paper explores the design and performance of an SMA heat engine that utilizes geothermal heat sources to drive mechanical work. The engine operates by cycling between the high-temperature geothermal environment and a cooler sink, exploiting the shape memory effect to generate mechanical motion. By integrating geothermal energy and SMA technology, this system offers a potential solution for renewable energy generation, with applications in remote or off-grid locations. The paper also investigates output power and the thermodynamic efficiency. A model is formulated and the engine behavior is simulated. A series of experiments are conducted for engine output power and efficiency. The model is compared to the experimental data for validation. The engine developed a maximum power of 3.5, 8.5, and 11.5 watts at 60, 80, and 90 °C respectively. The proposed SMA-based geothermo-mechanical energy conversion system offers a promising solution for efficient, reliable, and scalable geothermal energy harvesting. This research contributes to the development of innovative, efficient geothermal energy conversion technologies, supporting global renewable energy goals and reducing greenhouse gas emissions. This innovative energy conversion mechanism could play a key role in the future of sustainable power generation.

Wind Farm Layout Optimization/Expansion of Real Wind Turbines with a Parallel Collaborative Multi-Objective Optimization Algorithm

The objective of this paper is to study the Wind Farm Layout Optimization/expansion problem. This problem is formulated here as a Multi-Objective Optimization Problem considering the total power output and net efficiency of Wind Farms as objectives along with specific constraints. Once formulated, this problem needs to be solved efficiently. For that, a new approach based on a combination of five Multi-Objective Optimization algorithms, which is named the Parallel Collaborative Multi-Objective Optimization Algorithm, is developed and implemented. This technique is checked on seven test cases; for each case, the goal is to find a set of optimal solutions called the Pareto Front, which can be exploited later. The acquired solutions were compared with other approaches and the proposed approach was found to be the better one. Finally, this work concludes that the proposed approach gives, in a single run, a set of optimal solutions from which a designer/planner can select the best layout of a designed Wind Farm using expertise and applying technical and economic constraints.

A dual‐excitation inductive power transfer system with decoupled transformer for high misalignment tolerance

AbstractThis study delves into the design and optimization of a 4 kW dual‐excitation inductive power transfer system designed to accommodate large misalignments. The system utilizes a bipolar‐solenoid inductive coupled transformer as its coupling mechanism. Detailed simulation and analysis of this coupling mechanism are conducted. Additionally, the system employs a control strategy aimed at optimizing the coordination between output power and efficiency. This control strategy dynamically adjusts the power of the two transmitters, aiming to enhance system efficiency to the maximum extent possible under favourable coupling conditions. Moreover, it ensures that the system's output power remains at or above the rated value even when coupling conditions deteriorate. During the experiment, the system can optimize the output power and efficiency at the same time by using a suitable control strategy when the coils are misaligned. Meanwhile, the system can achieve a minimum efficiency of 81.5% even when the misalignment distance reaches 300 mm (60% of per transmitting coil size). The system and control strategy proposed in this paper can effectively overcome the deterioration of the output characteristics of the wireless power transfer system when misalignment occurs.

Hybrid Functional ITO/Silver Nanowire Transparent Conductive Electrodes for Enhanced Output Efficiency of Ultraviolet GaN-Based Light-Emitting Diodes.

We investigated hybrid functional transparent conductive electrodes (HFTCEs) composed of indium-tin-oxide (ITO) and silver nanowires (AgNWs) for the enhancement of output efficiency in GaN-based ultraviolet light-emitting diodes (UVLEDs). The HFTCEs demonstrated an optical transmittance of 69.5% at a wavelength of 380 nm and a sheet resistance of 16.4 Ω/sq, while the reference ITO TCE exhibited a transmittance of 76.4% and a sheet resistance of 18.7 Ω/sq. Despite the 8.9% lower optical transmittance, the UVLEDs fabricated with HFTCEs achieved a 25% increase in output efficiency compared to reference UVLEDs. This improvement is attributed to the HFTCE's twofold longer current spreading length under operating forward voltages, and more significantly, the enhanced out-coupling of localized surface plasmon (LSP) resonance with the trapped wave-guided light modes.

Performance Analysis of Cement Plant Waste‐Heat Recovery for Power Generation Based on Partial Evaporating Cycle with Ejector

In the cement industry, much waste heat is released into the environment. The organic Rankine cycle is widely utilized to harness waste heat for power generation. However, significant energy is lost in the heat recovery process due to the finite temperature difference between the heat source and working fluid, resulting in low power output andefficiency. To enhance the heat recovery from the cement flue gas and increase power output and overall efficiency, a novel partial evaporating cycle with ejector is proposed and investigated in this study. Pinch point analysis is performed to characterize the heat recovery process in the evaporator. The effects of the evaporating temperature, outlet quality of the evaporator, and exit pressure of the primary expander on system performance are also investigated. Results show that partially evaporating the fluid improves heat matching and reduces the irreversibilities in the evaporator by up to 18.1% when the outlet quality of the fluid is 0.33. Maximum net power of 803.15 kW can be generated with an evaporating temperature of , outlet quality of 0.33, and expander exit pressure of 1054.9 kPa. Additionally, the inclusion of the ejector increases the net power produced by up to 76.07 kW.

Surface Planarization-Epitaxial Growth Enables Uniform 2D/3D Heterojunctions for Efficient and Stable Perovskite Solar Modules.

Two-dimensional/three-dimensional (2D/3D) halide perovskite heterojunctions are widely used to improve the efficiency and stability of perovskite solar cells. However, interfacial defects between the 2D and 3D perovskites and the poor coverage of the 2D capping layer still hinder long-term stability and homogeneous charge extraction. Herein, a surface planarization strategy on 3D perovskite is developed that enables an epitaxial growth of uniform 2D/3D perovskite heterojunction via a vapor-assisted process. The homogeneous charge extraction and suppression of interfacial nonradiative recombination is achieved by forming a uniform 2D/3D interface. As a result, a stabilized power output efficiency of 25.97% is achieved by using a 3D perovskite composition with a bandgap of 1.55eV. To demonstrate the universality of the strategy applied for different perovskites, the champion device based on a 1.57eV bandgap 3D perovskite results in an efficiency of 25.31% with a record fill factor of 87.6%. Additionally, perovskite solar modules achieve a designated area (24.04 cm2) certified efficiency of 20.75% with a high fill factor of 80.0%. Importantly, the encapsulated uniform 2D/3D modules retain 96.9% of the initial efficiency after 1246h operational tracking under 65 °C (ISOS-L-3 protocol) and 91.1% after 862h under the ISOS-O-1 protocol.

Performance evaluation and multi-objective optimization of hydrogen-based integrated energy systems driven by renewable energy sources

This study proposes an integrated energy system using hydrogen storage to realize the efficient utilization of renewable energy sources and reduce the fluctuation when renewable energy is connected to grid. The system utilizes solar and wind energy to realize hydrogen production, desalination, and CCHP. First, the energy, exergy, and economic evaluations for the proposed system are carried out, and then an in-depth analysis of the key operating parameters is performed. The system achieves energy efficiency, exergy efficiency, and cost rate of 48.49%, 19.98%, and 7.969$/h, respectively. And the exergy analysis shows that the main exergy destructions are caused by the parabolic trough solar collector and the transcritical CO2 power cycle. The parametric analysis demonstrates when solar radiation flux and wind speed increase, the exergy efficiency and hydrogen production are increased, but the cost rate is increased accordingly. Finally, two sets of multi-objective optimization schemes are performed combining the artificial neural network with the non-dominant genetic algorithm-Ⅱ(NSGA-II). For the optimized fresh water output, cost rate, and exergy efficiency, it is achieving improvements of 51.73%, 8.4%, and 3.6%, and for the optimized hydrogen production, cost rate, and exergy efficiency, it is increased by 12.53%, 0.564%, and 0.75%, respectively.

Broadband operation of an X-band high-power relativistic traveling wave tube

Wide-band high-power relativistic traveling wave tubes (RTWTs) in X-band have the potential in phased-array antennas, microwave weapons, and so on. Thorough design and optimization are required to achieve wide-band amplification, especially with invariant beam voltage and interaction length. A corrugated circular waveguide is applied as the slow-wave structure for wide bandwidth. The geometric parameters of the structure are initially chosen by cold analysis and then verified by a nonlinear model and the 2D particle-in-cell simulation. The kinematic mismatch is proved to be vital to the wide-band amplification of the device. Optimization is performed so that high output powers in the bandwidth can be achieved with the same interaction length. With the beam voltage of 625 kV and the beam current of 1.92 kA, the optimized RTWT can deliver more than 100 MW from 8.43 to 9.32 GHz, and the corresponding bandwidth is ∼10%. In the frequency range from 8.65 to 9.32 GHz, the output power and efficiency are larger than 170 MW and 14%, respectively.

Performance evaluation of different photovoltaic array configurations under partial shading

In Partial Shading Conditions (PSCs), Photo Voltaic (PV) systems often experience notable output power and efficiency reductions due to weather variations. This study is dedicated to determining the most effective PV array configuration under partial shading. Various configurations, including Series Parallel (SP), Total Cross Tied (TCT), Bridge Linked (BL), Honey Comb (HC), Double Tied (DT), and hybrid connections, are simulated and evaluated under PSCs. Nine shading patterns, such as vertical, horizontal, centre-wise, upper triangular, cross-wise, expansive, arbitrary, L-shaped, and diagonal, are examined using a 6 × 6 array of PV Configuration. Performance analysis is based on parameters such as open circuit voltage (Voc), short circuit current (Isc), Global Maximum Power Point (GMPP), maximum voltage (Vm), maximum current (Im), Fill Factor (FF), Mismatch Loss (ML)/Power Loss (PL), and efficiency (η). Additionally, hybrid configurations like Alternate- Total Cross Tied -Bridge Linked (ALT-TCT-BL), Alternate -Total Cross Tied -Double Tied (ALT-TCT-DT), and Alternate -Total Cross Tied -Triple Tied (ALT-TCT-TT) are investigated and compared with existing configurations. Hybrid configurations with fewer cross-ties are recommended to simplify circuit complexity. MATLAB/Simulink software is employed for simulation, using a Sunpower SPR-E18-295-COM panel. Comparative analysis confirms that hybrid configurations exhibit higher efficiency for various shading patterns than existing configurations, equal or at par with the TCT connection. For eight connections and nine shading scenarios along with zero (no) shading conditions, eighty distinct combinations have been analysed, and on comparative analysis with contemporary work, the optimal output is obtained from the connections considered under PSCs. For all the shading patterns considered, the proposed work fetches maximum efficiency compared to the contemporary work, and it ranges between 13.61 % and 17.84 % for different shading patterns. The maximum value of efficiencies for horizontal, vertical, diagonal, centre-wise, expansive, arbitrary, upper triangular and L-shaped shading patterns is 13.77 %, 17.24 %, 17.84 %, 15.66 %, 13.61 %, 17.21 %,17.35 % and 15.11 % respectively. The hybrid configuration achieves higher efficiency than current methods for all shading patterns and configurations, with improvements in efficiency ranging from 2.1 % to 42.22 % across all cases.

Enhancing output characteristics of semi-active flapping airfoil energy capture device via flexible deformation strategy

ABSTRACT A concentrated-torsion flexible airfoil model is established to enhance the output characteristics of the flapping airfoil energy capture device in this work. The effect of the damping ratio C 2*, spring ratio K 2* of the torsion spring, and mass ratio M A * of the tail airfoil on the dynamic characteristics is investigated systematically. The numerical simulation results show that compared with the rigid airfoil, the time-averaged power coefficient and output efficiency of the optimized flexible airfoil (C 2* = 4, K 2* = 0.5, and M A * = 0.7) are increased by 91.85% and 63.45%, respectively. Remarkably, the output efficiency of the optimized flexible airfoil is 32.15%. The reason for the enhanced performance is that the passive deformation can ensure the airfoil generates a stronger vortex and delays the shedding of the vortex. In addition, the experimental test results (with a 36.29% performance enhancement) further demonstrate the effectiveness of using the concentrated-torsional flexible deformation strategy in enhancing the energy output characteristics of the flapping airfoil.

Simulation of a system to simultaneously recover CO2 and sweet carbon-neutral natural gas from wet natural gas: A delve into process inputs and units performances

The growing need for carbon-neutral energy solutions necessitates the development of efficient systems for carbon dioxide (CO2) recovery and the production of sweet carbon-neutral natural gas (CNNG) from wet natural gas. Despite existing approaches, limitations in process optimization, solvent efficiency, and output purity persist. This study aims to address these gaps by simulating a system for simultaneous recovery of CO2 and CNNG using an integrated three-stage process, modeled in Aspen Plus V8.8. The unique aspect of this work lies in employing the ENRTL-RK base model, coupled with sensitivity analyses to optimize input parameters across 13 interconnected process units, including compressors, heat exchangers, and extraction columns. Key innovations include the novel configuration of units, yielding a recovery efficiency of 95.94% for CNNG and a CO2 purity of 93.185% at optimal conditions, surpassing conventional methods. The performance of the monoethanolamine (MEA) solvent was enhanced by careful adjustment of input parameters, improving its absorption efficiency by 12% compared to standard operational settings. Sensitivity analysis revealed critical parameters such as feed pressure and solvent flow rate as primary drivers for maximizing output efficiency. This study also provides a detailed quantitative assessment of power requirements, with a compressor brake horsepower (BHP) of 18,2605 watts at 110 bar discharge pressure. It addresses the existing research gap by introducing a systematic approach to process optimization, significantly improving the purity and recovery of CNNG and CO2 while minimizing energy consumption. The results not only demonstrate the viability of this process but also provide a foundation for further refinement in sustainable gas processing technologies.

Part-load performance analysis of a modular biomass boiler with a combined heat and power industrial Rankine cycle and supplementary sCO2 Brayton cycle

Abstract The addition of a supplementary high efficiency cycle integrated with an existing steam power cycle may increase energy efficiency and net generation. In this paper, part load performance and operation of a modular biomass boiler with an existing industrial Rankine steam heat and power cycle and supplementary supercritical CO2 (sCO2) Brayton cycle is analysed. The aim is to leverage the high efficiency of the sCO2 cycle by retrofitting sCO2 heaters in the existing biomass boiler, increasing net power output and thermal efficiency. With nominal load performance previously investigated, understanding part-load performance and operation is vital to determine cycle feasibility. A quasi-steady-state one dimensional thermofluid network model was used to simulate the integrated cycle performance for loads ranging from 100% to 60%. The model solves the mass, energy, momentum, and species balance equations, capturing detailed component characteristics. Two control methodologies are explored for the sCO2 Brayton cycle, namely inventory control and inventory control combined with throttling valve control. Inventory control is selected as the better performing control strategy for load following, maintaining high thermal efficiency across partial loads. At 60% load, the sCO2 compressor operates near the pseudo-critical point, leading to a sharp decrease in sCO2 cycle capacity, which requires careful management of inventory control. Two sCO2 heater configurations are investigated, namely a single convective-dominant heater, and a dual heater configuration with a radiative and a convective heater. The single heater configuration is preferred to minimise adverse impacts on the Rankine cycle superheaters.

Methane Desorption-Diffusion Behaviors in Micropores of Coal under Different Water Displacement Pressures.

Hydraulic fracturing not only enhances the flow conductivity of coal seams but also transforms the CH4 adsorbed in coal seams into free CH4 and then outputs it via the desorption-diffusion process, thus improving the output quantity and efficiency of CH4. In this paper, taking the coal from Changping mine in Shanxi as the research object, the 3D macromolecule model of coal was established by using analytical test experiments, and the molecular dynamics simulation method of desorption and diffusion was applied to study the characteristics of methane desorption rate and diffusion behaviors under different driving water pressures through the parameters of gas-water concentration distribution, desorption and diffusion rates, and the interaction energies between the coal and the gas-liquid. The results show that the water drive can increase the desorption rate of methane. With the increase of methane adsorption pressure, the desorption effect of water drive becomes stronger and then weaker. The desorption effect of water drive was best when the methane adsorption pressure was 5 MPa and the pressure difference was 2 MPa. Generally, the water drive promoted the methane diffusion, but if the water drive time was too long, it formed a water plug, and the water drive methane inhibited the diffusion. In shallow reservoirs, water drive can obviously promote the desorption-diffusion of methane. The binding energy between CH4 molecules is mainly composed of the repulsive force, while that between water molecules is mainly the adsorption force. In the binding energy between CH4 molecules and coal structures, the van der Waals (VDW) force accounts for 99% of the effect; in the binding energy between water molecules and coal structures, the electrostatic force contributes 84% to ∼88% thereto. The VDW force is significantly influenced by the pressure, while the electrostatic force is slightly affected. As the water displacement differential pressure is increased, the binding energy between CH4 molecules and coal structures decreases.

A Power Boosting Method for Wireless Power Transfer Systems Based on a Multilevel Inverter and Dual-Resonant Network

With the deepening of research on wireless power transfer (WPT) technology, there is an urgent need to improve the output power of WPT systems. Therefore, this paper proposes a power boosting method based on a multilevel inverter and dual-resonant network. The system adopts a five-level inverter whose output voltage contains rich fundamental and harmonic components. The transmitting side adopts a dual-resonant compensation network, and, through its parameter configuration, the system can be in a resonant state at both the fundamental and third harmonic frequencies. The receiving side adopts two receiving channels which can simultaneously receive power at both frequencies, thus boosting the output power. Firstly, the overall structure and operating principle of the system are introduced. Then, the relationship between the system output power and efficiency with the inverter modulation parameters is obtained and the strategy for selecting the optimal operating points of the inverter is designed by comprehensively considering the THD of the inverter output voltage and the efficiency of the system. Furthermore, the proposed system is simulated in a Matlab/Simulink platform. Finally, an experimental setup is created to verify the proposed method. The results show that, compared with the single-channel WPT system, the proposed method can enhance the output power from 160 W to 310 W with a boosting coefficient of nearly double and with the highest efficiency exceeding 92%.

A Decoupled Modulation Strategy for Constant Voltage/Current Wireless Charging System Under High Coils Misalignment

ABSTRACTOutput fluctuation and lower transmission efficiency under load and mutual inductance variation are hot concerned in the wireless charging system for power batteries. In this paper, a decoupled tracking strategy is proposed to realize constant voltage (CV) or current (CC) output and high transmission efficiency. The circuit model of series–series compensation network is built, and corresponding transmission characteristics can be derived. First, the load and mutual inductance value can be estimated by measuring the primary electrical information, including the inverter output voltage, current, and the phase error between them. Then load‐independent voltage or current output characteristics under coils misalignment can be maintained by tracking the optimal switching frequency of inverter part. In addition, the value of output voltage or current can be adjusted flexibly for different operation occasions by the employment of pulse‐width modulation. As a result, the load‐independent output characteristics realization and output adjustment can be decoupled. Based on only the primary measuring information, the CV/CC output can be maintained via the proposed hybrid control strategy when the coils misalignment and load variation happen, increasing the robustness of whole wireless power transfer (WPT) system. Furthermore, the soft switching of all power switches in the inverter part can be realized to reduce the switching loss. Compared with previous research, the proposed wireless charging system has a higher power density and a simplified control strategy. Finally, an experimental platform with 60‐V charging voltage and 3.6‐A charging current is built to verify the feasibility of the proposed sys‐tem and control method.

A New Magnetic Coupler with High Misalignment Tolerance and Inherent Constant Current–Constant Voltage for Underground Wireless Charging

In an underground inductive power transfer (IPT), it is inevitable to produce the phenomenon of misalignment between the transmitter and the receiver, which will reduce the output current, voltage and output efficiency of the whole IPT system. Aiming to solve this problem, a universal hybrid coupler is proposed, which can still stabilize the output in the expected range and has the ability of anti-misalignment when the X and Z directions are misaligned. The coupler is composed of a BP coupler and Γ type network. The secondary edge of the coupler introduces a Γ network, which decouples the two main coils on the same side of the receiver from the auxiliary coil and reduces the complexity of the system. The coupler can effectively reduce the coupling fluctuation caused by physical movement between the downhole transmitting end and the receiving end, thereby ensuring the stable output of the coupler. As a widely used IPT system, it can access the rest of the circuit topology whose output is independent of the load and achieve misalignment-tolerant output. Finally, based on the proposed hybrid IPT coupler theory, a 500 W misalignment-tolerant coupler prototype was built, and the compensation topologies were configured as series–series (SS) and series/inductance/capacitance/capacitor (S/LCC) structures. When the X and Z direction is misaligned, the constant current and voltage independent of the load can be output by switching the compensation topology. The experimental results are the same as the theoretical analysis.