Power Matching Research Articles

LSTM-based drive power matching and its economic analysis

The correlation coefficients of computerised well mining data and motor power, selecting indicators with high correlation as input data, predicting the minimum and maximum power of the unit based on LSTM neural network, and giving the template of drive system matching according to the theory of drive system matching technology formed for different models.

Study on a nonlinear dynamic characteristic of the positive flow pump in its pilot hydraulic cylinder

The displacement of the positive flow pump is controlled by its pilot hydraulic cylinder. The tracking performance of the pump displacement directly affects the energy saving of the hydraulic excavator through power matching. In this article, a nonlinear dynamic characteristic of the positive flow pump in its pilot hydraulic cylinder is studied to improve the mathematical model for controller design. The concept of relative water hammer is first proposed to describe the relative pressure wave acting on the hydraulic piston to illustrate the mechanism of the nonlinearity. Chaotic motion can be generated by the relative water hammer when the hydraulic piston is in a partial stroke. The mathematical model is derived and its critical parameters are analyzed. The simulation and experimental results verify the existence of the relative water hammer and the effect of each critical parameter on the pilot hydraulic cylinder and the positive flow pump.

A Study of an Integrated Analysis Model with Secondary Flow for Assessing the Performance of a Micro Turbojet Engine

The objective of this study is to implement a more realistic integrated analysis model for micro gas turbines by incorporating secondary flow and combustion efficiency into the existing model, which includes main engine components such as the compressor and turbine, and to validate this model by comparing it with test results. The study was based on the JetCat P300-RX, which has a maximum thrust level of 300 N. Simulations were performed using ANSYS CFX, employing the κ-ω SST turbulence model and a mixing plane interface between individual components. The eddy dissipation model (EDM), with a combustion efficiency of 90%, was used as the combustion model. A user subroutine was also applied for the power matching of the compressor and turbine to calculate the fuel flow rate in each iteration. For secondary flow, it was assumed that 3% of the total air flow rate would flow through the secondary path and be applied to the compressor and turbine. Simulations were conducted over a range of 30,000 to 104,000 RPM, with ground conditions evaluated, including altitude-simulated conditions. To validate the analysis model, engine performance metrics such as pressure ratio, air flow rate, fuel flow rate, and exhaust gas temperature (EGT) were compared with test results. The results demonstrated that errors were less than 5% for most engine performance metrics, except for EGT and fuel flow. The discrepancy in EGT was attributed to differences in the sensing methods, while the variation in fuel flow was found to be due to the lubrication system and losses due to the secondary air flow. Consequently, this study confirmed that the integrated simulation model accurately predicts engine performance. The results indicate that the integrated simulation model provides a more realistic prediction of overall engine performance compared to previous studies. Therefore, it can evaluate detailed thermo-fluid properties without the need for component performance maps, enhancing performance evaluation and analysis.

Dynamic power matching for wheel loader based on power reflux hydrodynamic transmission system

Dynamic power matching for wheel loader based on power reflux hydrodynamic transmission system

Research on Variable Speed Variable Displacement Power Unit with High Efficiency and High Dynamic Optimized Matching

For the variable speed variable displacement power unit (VSVDPU), achieving power matching between the permanent magnet synchronous motor (PMSM) and the variable displacement plunger pump (VDPP) is the key to reducing system energy consumption. The control method of adjusting the speed of the PMSM and the displacement of the VDPP is the mainstay of current research and application of the VSVDPU. However, the dynamic properties of the PMSM and VDPP have not been balanced, which affects the control effect of the VSVDPU. This paper proposes a control method of variable speed and variable displacement with low energy consumption and high dynamics. The main idea is based on the efficiency model and dynamic response model of the PMSM and VDPP, and the factors that affect the efficiency and dynamic characteristics of the VSVDPU are analyzed. Guided by the multi-objective optimization algorithm, the optimal combination of speed and displacement under specific working conditions is derived. Simulation and experiment results show that the proposed control method is feasible to improve the efficiency and dynamic characteristics of the VSVDPU.

Millimeter-Wave GaN High-Power Amplifier MMIC Design Guideline Considering a Source via Effect

A millimeter-wave (mmWave) gallium nitride (GaN) high-power amplifier (HPA) monolithic microwave-integrated circuit (MMIC) was implemented, considering a source via effect. In this paper, we introduce guidelines for designing GaN HPA MMICs, from device sizing to meeting high-power specifications, power matching considering source via effects, schematic design of three-stage amplifier structures, and electromagnetic (EM) simulation. Based on the results of load pull simulation and small-signal maximum stable gain (MSG) simulation, the GaN high-electron-mobility transistor (HEMT) size was selected to be 8 × 70 μm. However, since the source via model provided by the foundry was significantly different from the EM results, it was necessary to readjust the power matching considering this. Additionally, when selecting the source via size, the larger the size, the easier the matching, but since the layout of the peripheral bias circuit is not possible, a compromise was required considering the actual layout. To prevent in-band oscillation, an RC parallel circuit was added to the input matching circuit, and low-frequency oscillation was solved by adding a gate resistor on the PCB module. The proposed PA was fabricated with a commercial 0.1 μm GaN HEMT MMIC process. It exhibited 38.56 to 39.71 dBm output power (Pout), 14.2 to 16.7 dB linear gain, and 14.1% to 18.2% power-added efficiency (PAE) in the upper Ka band. The fabricated GaN power amplifier MMIC shows competitive Pout in the upper Ka band above 33 GHz.

Upgrading the Compressor Stage of the CAT250TJ Micro Gas Turbine Engine

AbstractDue to their simplicity and relative ease of manufacture, single-stage centrifugal and mixed flow micro gas turbine (MGT) engines are preferred in thrust-based remotely piloted aerial vehicles. A single-stage mixed-flow compressor upgrade for the 200 N CAT250TJ MGT engine is numerically evaluated and presented. An in-house developed mean line application and commercial CFD software is used for the design and performance evaluation of the proposed upgrade configurations. The CAT250TJ – Gen1 engine features a single-stage centrifugal compressor, annular combustor, and single stage axial turbine. Apart from an upgraded impeller, a new crossover diffuser configuration is introduced to replace the wedge-type, straight outlet diffuser configuration of the Gen1 engine. The new single vane crossover diffuser configuration provides a design point total-to-total efficiency and pressure ratio increase of 8.3% and 12.1%, respectively. A disadvantage of a single-vaned crossover diffuser compared to legacy diffusers is a narrower operating range. To alleviate this issue, various combinations of tandem and splitter vane crossover diffuser configurations are proposed. These provide an enhanced operating range, comparable with the operating range displayed by the Gen1 configuration. A turbine power matching analysis is additionally completed to ensure proper compressor integration. Gas turbine cycle software is used to evaluate the on-engine performance of the upgraded compressor configurations. It is shown that the new baseline, single vane crossover diffuser configuration provides a 10.74% increase in design point static thrust.

Artificial Neural Networks for Power Match Modeling and Verification With a Novel D-Band Vector Load—Pull Bench

Artificial Neural Networks for Power Match Modeling and Verification With a Novel <i>D</i>-Band Vector Load—Pull Bench

Study on a high-performance heat-driven thermoacoustic heat pump

Heat-driven thermoacoustic heat pump (HDTAHP) is a promising heating technology with high reliability. Current HDTAHP face the challenge of being relatively inefficient and not capable of further improvement. This study aims to address this problem by introducing an innovative energy matching tube (EMT) into the conventional thermoacoustic heat pump to realize more reasonable acoustic power matching between the engine and heat pump units, further greatly improve the system efficiency. The key reason for the limited performance of HDTAHP is first explored and lies in the constraints that exist between temperatures. Through Sage modeling and calculations, the comparison between the proposed system and the conventional thermoacoustic heat pump system verifies that the introduced EMT can dramatically increase the system performance. At a heating temperature of 700 K, the overall Coefficient of Performance (COPh) of the system is improved by 43.7 % compared to the conventional thermoacoustic heat pump without EMT. The performance under different working temperatures is then investigated and demonstrated a strong adaptability of the proposed system under different heating temperature objectives. The comparison with existing thermoacoustic-Stirling heat pumps further indicate the high-performance improvement by EMT and promising potential of thermoacoustic heat pumps in domestic heating domain.

Theoretical and experimental comparison of gear systems: Planetary mechanical transmission and coaxial magnetic gear

Gear systems in today’s industry are one of the critical pillars providing power transformation and matching speed and torque to application requirements. Reliability, high efficiency, and low operating costs are desirable due to the prevalence of gearboxes. This paper provides a comparative analysis of selected mechanical and magnetic gears, using a specific example to point out the advantages and disadvantages of contactless power conversion. After determining the essence of the operation of the magnetic gear on the base model, two magnetic gear optimization cases are presented, testifying to the application potential. An analysis of the stress distribution in the area of the teeth of the mechanical gearbox and the most stressed element of the magnetic gear - the modulator, was carried out. The effects of temperature and load on losses were measured and simulated, and ultimately, the efficiency characteristics of the two gears were also compared.

Optimizing the noise control in a two-layer conduit

In the modern world, noise pollution is a major concern due to its prevalence. This work focuses on optimizing noise control in a two-layer conduit. A conduit comprises an inlet and double-outlet zones (DOZ). The upper walls of the DOZ are lined with perforated absorbent material while the lower walls are layered with fibrous. Mathematically, the physical problem is formulated with a field wave equation together with rigid and impedance boundary conditions in the respective zones. Such governing boundary value problem (BVP) leads to the Sturm-Liouville (SL) category in which standard orthogonality relations (OR) are indispensable. The system of the linear equations of the BVP is acquired with semi-analytical Mode-Matching (MM) approach by implementing the continuity conditions of sound pressures and velocities at the matching junction with the aid of OR. These systems are truncated and solved numerically with computation learning to obtain the reflected and transmitted modal amplitudes in respective zones. Due to the lining's perforated upper walls, fibrous lower walls, and reversal in the DOZ, the analysis of the reflected and transmitted powers versus frequencies is significantly observed and is shown in graphical findings. The algebraic derivation is validated by satisfying the conservation law of power flux and matching continuity conditions for impedance, perforated, and fibrous lined boundaries.

Design of a Compact 2-6 GHz High-Efficiency and High-Gain GaN Power Amplifier.

In this paper, a novel wideband power amplifier (PA) operating in the 2-6 GHz frequency range is presented. The proposed PA design utilizes a combination technique consisting of a distributed equalization technique, multiplexing the power supply network and matching network technique, an LR dissipative structure, and an RC stability network technique to achieve significant bandwidth while maintaining superior gain flatness, high efficiency, high gain, and compact size. For verification, a three-stage PA using the combination technique is designed and implemented in a 0.25 μm GaN high-electron-mobility transistor (HEMT) process. The fabricated prototype demonstrates a saturated output power of 4 W, a power gain of 21 dB, a gain flatness of ±0.6 dB, a power-added efficiency of 39-46%, and a fractional bandwidth of 100% under the operating conditions of drain voltage 28 V (continuous wave) and gate voltage -2.6 V. Moreover, the chip occupies a compact size of only 2.51 mm × 1.97 mm.

Compressor speed control for optimizing energy matching of PV-driven AC systems during the cooling season

Photovoltaic-driven air conditioning (PVAC) systems innovatively utilize PV power for building cooling, reducing PV power fluctuation impact on the utility grid. This study introduced a novel PVAC system that optimizes the energy matching between PV generation and air conditioning electricity demand through directly controlling of the compressor speed in accordance with the real-time PV power generation. A PID control method was employed to regulate the compressor speed of PVAC, and three control strategies were proposed and successfully implemented during the experiments. The system's efficiency was evaluated using metrics such as the self-consumption rate (SCR), self-sufficiency rate (SSR), real-time zero energy proportion (RZEP), and the mean absolute error (MAE) of indoor temperature. The results of this study confirm that the proposed control method significantly enhances the power matching between the PV power generation and the air conditioning electricity demand. Implementing the recommended strategy, SCR increased from 0.53 to 0.625 and SSR from 0.716 to 0.808, all while maintaining indoor thermal comfort. Moreover, the proposed approach mitigates the impact of distributed PV generation on the utility grid and potentially diminishes energy storage needs, which can contribute to a lower system investment requirements and operating costs.

Development of a bionic multi-chamber hydraulic cylinder for improving energy efficiency

Most hydraulic drive systems for robots are configured with one single pump and multiple cylinders, which suffers from low energy efficiency in the case of driving the variable loads. To solve the problem, this paper presents a multi-chamber hydraulic cylinder based on the bionic muscle drive mechanism. Firstly, the mechanical structure is designed, the mathematical models are derived, the mechanism of high energy efficiency is analyzed. Then, the simulation of load matching control is carried out, which shows the high energy efficiency improvement and the good position tracking. Finally, the multi-chamber hydraulic cylinder prototype is developed for experimental study, and output forces, output displacement, energy consumption, and friction characteristics are researched. The theoretical analysis and experimental research show that the bionic multi-chamber hydraulic cylinder can realize the power matching between the single power source and the variable loads in the hydraulic system, which provide a novel idea for the energy efficient hydraulic equipment.

Power matching based current limitation method for grid forming converter under large disturbances

Grid forming (GFM) converter mimics the operational characteristics of the synchronous generator, serves as a voltage source that provides voltage and frequency support to the power system. However, due to its voltage source nature, the current of the GFM converter is highly determined by the external system, increasing the risk of overcurrent under large disturbances and potential damage to the converter. The conventional current reference limitation suffers from synchronization instability, which causes the converter to lose synchronization. To address this issue, this paper proposes a novel power matching based current limitation method, which maintains the synchronization of the GFM converter and also avoids overcurrent issues. Specifically, when a large disturbance occurs, considering the maximum output power of the GFM converter, the reference power of the converter is corrected using the frequency to match the output power in real time. Therefore, the output power of the converter is always its maximum value, with the current constrained to the maximum level allowed, avoiding overcurrent and instability. Finally, the superiority of the proposed method is verified by experiment and simulation.

Active power optimization control of speed closed-loop engine for energy saving in hydraulic excavator

ABSTRACT Most hydraulic excavators use passive power control to adjust the engine speed according to the load torque to achieve power matching, which has very limited effectiveness in energy saving. In this paper, an active power optimization control of speed closed-loop engine is proposed to improve its tracking performance for the dynamic energy-saving operating points. The inertia movement of the engine during variable speed control is analyzed to determine the kinetic energy requirements for different start and end operating points. An RBF-based neural network controller is designed based on power optimization to actively compensate the strong hysteresis of the engine speed relative to the optimal torque. The simulation and the experimental results show that the proposed control method has a much faster response for the energy-saving operating points, which reduces the energy consumption by 9.28% and 5.56% without adding any energy storage devices to the hydraulic excavator.

An efficient and eco-friendly heat-driven thermoacoustic refrigerator with bypass configuration

Developing high-efficiency and environmentally friendly cooling technology is crucial for sustainable life. Heat-driven thermoacoustic refrigerator (HDTR) is an emerging cooling technology characterized by no moving components, eco-friendly working substances, and high reliability. This study reports an innovative efficient HDTR with bypass configuration, which employs eco-friendly and economical working substances, the nitrogen and water. The bypass configuration enables good matching of acoustic power between the engine and cooler units at high heating temperatures, thus enhancing the efficiency. In addition, the employment of liquid resonator significantly reduces the working frequency and reduces the loss. An experimental investigation is performed on the onset characteristics and operating performance of the proposed system. The results show that a highest coefficient of performance (COP) of 0.49 and a cooling power of 726 W are achieved at the heating, ambient, and cooling temperatures of 500, 35, and 7 °C, respectively, exhibiting a high level for the HDTRs employing nitrogen. This work supplies an effective way to the efficiency enhancement of the HDTRs, indicating substantial potential of the proposed HDTR in eco-friendly air-conditioning applications.

An online energy optimization method for urban rail flexible traction power supply system based on spatiotemporal matching of train power

An online energy optimization method for urban rail flexible traction power supply system based on spatiotemporal matching of train power

Sustainable heat-driven sound cooler with super-high efficiency

&lt;p&gt;Sustainable cooling technologies with high efficiency are increasingly vital in modern life. Characterized by eco-friendly working substances and no mechanical moving components, the heat-driven thermoacoustic refrigerator (HDTR) makes it a really sustainable choice. However, its practical application has been hindered by its relatively low efficiency. This work reports a breakthrough in thermally-powered sound cooling technology: a super-efficient HDTR. The system incorporates an innovative configuration, ensuring efficient acoustic power matching between the engine and cooler units at high heating temperatures, thereby significantly boosting efficiency. Our experimental findings are exhilarating: the HDTR achieves an unprecedented coefficient of performance (COP) of 1.34 at heating, ambient, and cooling temperatures of 550 ��C, 35 ��C, and 7 ��C, respectively, along with a cooling power of 2.37 kW. To the best of our knowledge, under approximate temperature spans, this COP surprisingly increases by 240% compared to the best result previously reported for HDTRs without using the novel configuration. These results represent a significant advancement in HDTR technology, showing a tremendous potential of the HDTR as an emerging, sustainable cooling technology, particularly for heat-driven room-temperature refrigeration applications.&lt;/p&gt;

Deep Boosting Learning: A Brand-new Cooperative Approach for Image-Text Matching.

Image-text matching remains a challenging task due to heterogeneous semantic diversity across modalities and insufficient distance separability within triplets. Different from previous approaches focusing on enhancing multi-modal representations or exploiting cross-modal correspondence for more accurate retrieval, in this paper we aim to leverage the knowledge transfer between peer branches in a boosting manner to seek a more powerful matching model. Specifically, we propose a brand-new Deep Boosting Learning (DBL) algorithm, where an anchor branch is first trained to provide insights into the data properties, with a target branch gaining more advanced knowledge to develop optimal features and distance metrics. Concretely, an anchor branch initially learns the absolute or relative distance between positive and negative pairs, providing a foundational understanding of the particular network and data distribution. Building upon this knowledge, a target branch is concurrently tasked with more adaptive margin constraints to further enlarge the relative distance between matched and unmatched samples. Extensive experiments validate that our DBL can achieve impressive and consistent improvements based on various recent state-of-the-art models in the image-text matching field, and outperform related popular cooperative strategies, e.g., Conventional Distillation, Mutual Learning, and Contrastive Learning. Beyond the above, we confirm that DBL can be seamlessly integrated into their training scenarios and achieve superior performance under the same computational costs, demonstrating the flexibility and broad applicability of our proposed method.