Search Results (14)

When a single-phase grounding fault occurs in resonant ground distribution network, the fault characteristics are weak and it is difficult to detect the fault line. Therefore, a fast fault line selection method based on MCECA-CloFormer is proposed in this paper. Firstly, zero-sequence current signals were converted into images using the moving average filter method and motif difference field to construct fault data set. Then, the ECA module was modified to MCECA (MultiCNN-ECA) so that it can accept data input from multiple measurement points. Secondly, the lightweight model CloFormer was used in the back end of MCECA module to further perceive the feature map and complete the establishment of the line selection model. Finally, the line selection model was trained, and the information such as model weight was saved. The simulation results demonstrated that the pre-trained MCECA-CloFormer achieved a line selection accuracy of over 98% under 10 dB noise, with a remarkably low single fault processing time of approximately 0.04 s. Moreover, it exhibited suitability for arc high-resistance grounding faults, data-missing cases, neutral-point ungrounded systems, and active distribution networks. In addition, the method was still valid when tested with actual field recording data. Full article

A DC converter is the core equipment of voltage conversion and power distribution in a DC distribution network. Its operating characteristics have a profound impact on the flexible regulation of distributed resources in an active distribution network. It is challenging for the existing single-stage conversion topology to meet the requirements of distributed renewable energy connected to a multi-voltage level, medium-voltage grid. It is necessary to study the multistage transform power unit topology further, which can satisfy high reliability, high efficiency, and wide input range. This paper proposes a high-power density DC converter for medium-voltage DC networks with wide voltage levels. It adopts Buck-LLC integrated modular composition. The input ends of the high isolation resonant power unit are connected in series to provide high voltage endurance, and the output ends are connected in parallel to meet the high-power demand and achieve high-power transmission efficiency. The proposed series dual Buck-LLC resonant power unit topology can adjust the duty cycle of series dual buck circuits to meet the needs of different levels of medium-voltage DC power grids. The soft switching problem within the wide input range of all switching tubes is solved by introducing auxiliary inductors, thereby improving energy transmission efficiency. The auxiliary circuit and control parameters are optimized based on the research of each switching tube’s soft switching boundary conditions. Finally, an experimental prototype of a 6.25~7 kW power unit is designed and developed to prove the proposed topology’s feasibility and effectiveness. Great breakthroughs have been made both in theoretical research and engineering prototype development. Full article

This paper describes a new configuration of Cuk and SEPIC (Single-Ended Primary Converter) ZVS-QR (zero-voltage switching quasi-resonant) combination DC-DC converter for bipolar output with a single switch. The proposed topology employs a single ground-referenced power switch, which simplifies the gate drive design with a single L-C resonant network and provides a bipolar output voltage with good regulation, acceptable efficiency and a step-down/up conversion ratio. This configuration provides dual-output voltage by switching the power switch to zero voltage, which is an interesting alternative for many applications where small size, light weight and high power density are very important aspects. In order to verify its performance, a SEPIC–Cuk Combination ZVS-QR prototype with a cost-effective commercial resonant controller was designed and tested. The experimental results show that the proposed combined topology is suitable for Single-Input Dual-Output (SIDO) applications. Full article

The paper presents the design of a single-ended transistor zero-voltage switch (ZVS) parallel resonant DC-DC converter. Due to the use of a resonant inverter in the structure of the DC-DC converter, it is characterized by high efficiency and improved performance. On the other hand, due to the specifics of the power circuit operation, in the work, it is proposed to find the values of some of the elements of the circuit of the electronic converter to be carried out based on the application of optimization. To solve this task, various tools available in Matlab/Simulink have been applied, as well as author’s programs specially developed for the purpose. The use of a hybrid method for the design of power electronic converters, which combines analytical and optimization approaches, is justified in cases where there is no adequate design procedure. With the increase in the complexity of the power topologies and their possible modes of operation, difficulties arise related to their design such as: assumptions and limitations in conducting the analysis and the corresponding methodologies based on this analysis; high order of the differential equations composing the mathematical models; need for highly qualified specialists in the field of design. The proposed approach does not negate the classical design methods based only on analytical ratios determined by analysis of power circuits, but complements and develops them with innovative ones based on the application of computational mathematics and information and communication technologies. Full article

The paper presents a model-based design consideration of a series single-ended transistor resonant DC-DC converter with zero voltage switching (ZVS). A characteristic of this converter is that it is highly efficient due to the resonant nature of electromagnetic processes in the power circuit and operation with soft commutations. The manuscript proposes that the determination of some of the circuit elements of the device be carried out with optimization procedures based on the application of artificial intelligence techniques. For this purpose, an objective function is used with additional constraints, such as equalities and inequalities, for both the optimization parameters and the state variables. The use of the proposed method is justified in cases where there is no methodology for the design of the specific power electronic device or there is, but it is too complicated to apply. This is usually due to the increasing complexity of power circuits and their possible modes of operation and the inevitable assumptions and limitations in the analysis and the relevant methodologies based on that analysis. In this way, a natural combination, complement and development of classical design methods with innovative ones based on the application of artificial intelligence techniques is carried out. Full article

This paper presents a model-based and neural network-based innovative design of single-ended transistor resonant DC/AC converters with zero voltage switching (ZVS). A characteristic of the proposed design method is that the determination of the circuit elements of the converter is performed with an automated procedure, as their values are determined by the output of a previously trained neural network. The use of the proposed method is justified in cases where there is no methodology for the design of the specific power electronic device, or such a methodology exists, but it is either too complex or based on a large number of assumptions. This is usually due to the increasing complexity of power circuits, their possible modes of operation, and the inevitable assumptions and limitations in the analyses and methodologies based on them. In this way, a natural combination of classic design methods and innovative processes is developed based on applied techniques for artificial intelligence. Full article

Single-switch quasi-resonant DC inverters are preferred in low-power induction-heating applications for their cheapness. However, they pose difficulties in enforcing soft-switching and show limited controllability. A good design of these converters must proceed in parallel with the characterization of the load and the operating conditions. The control of the switching frequency has a critical relationship to the non-linear behavior of the load due to electro-thermal coupling and geometrical anisotropies. Finite element methods enable the analysis of this kind of multiphysics coupled systems, but the simulation of transient dynamics is computationally expensive. The goal of this article is to propose a time-domain simulation strategy to analyze the behavior of induction heating systems with a quasi-resonant single-ended DC inverter using pulse frequency modulation and variable load. The load behavior is estimated through frequency stationary analysis and integrated into the time-domain simulations as a non-linear equivalent impedance parametrized by look-up tables. The model considers variations in temperature dynamics, the presence of work-piece anisotropies, and current harmonic waveforms. The power regulation strategy based on the control of the switch turn-on time is tested in a case study with varying load and it is shown that it is able to maintain the converter in the safe operation region, handling variations up to of 22% in the equivalent load resistance. Full article

Single-ended resonant converters such as Class-E inverters have been widely considered as a potential topology for small- and medium-power wireless power transfer (WPT) applications, which feature compact circuits, low switching losses, and cost benefits, as they only use a low-side switch with a simple gate driver. However, there remains a practical challenge in the design of voltage stress, efficiency, and power density. In this paper, a single-ended resonant converter with a primary parallel resonant-matching network is investigated to absorb the bulky input-choke inductors of the Class-E inverters into the coil inductance. The analytical expressions for all the converter parameters are derived based on time-domain resonant waveforms, including: (1) analysis of critical zero-voltage switching (ZVS) conditions and (2) power transfer capabilities under the given maximum switch voltage stress. Furthermore, this paper elaborates on the design methodology of the proposed single-ended resonant converters, and an optimal operating point is chosen to ensure soft-switching operation and rated power. Finally, the accuracy of the proposed model is verified by simulation and experimental results. Full article

In this study, a sensitive method for detecting DNA methyltransferase (MTase) activity was developed by combining the effective fluorescence resonance energy transfer (FRET) of cationic conjugated polymers and exonuclease (Exo) III–mediated signal amplification. DNA adenine MTase targets the GATC sequence within a substrate and converts the adenine in this sequence into N6-methyladenine. In the method developed in this study, the methylated substrate is cleaved using Dpn I, whereby a single-stranded oligodeoxynucleotide (oligo) is released. Afterward, the oligo is hybridized to the 3ʹ protruding end of the F-DNA probe to form a double-stranded DNA, which is then digested by Exo III. Subsequently, due to weak electrostatic interactions, only a weak FRET signal is observed. The introduction of the Exo-III–mediated target-recycling reaction improved the sensitivity for detecting MTase. This detection method was found to be sensitive for MTase detection, with the lowest detection limit of 0.045 U/mL, and was also suitable for MTase-inhibitor screening, whereby such inhibitors can be identified for disease treatment. Full article

In this work, a non-isolated DC–DC converter is presented that combines a voltage doubler circuit and switch inductor cell with the single ended primary inductor converter to achieve a high voltage gain at a low duty cycle and with reduced component count. The converter utilizes a single switch that makes its control very simple. The voltage stress across the semiconductor components is less than the output voltage, which makes it possible to use the diodes with reduced voltage rating and a switch with low turn-on resistance. In particular, performance principle of the proposed converter along with the steady state analysis such as voltage gain, voltage stress on semiconductor components, and design of inductors and capacitors, etc., are carried out and discussed in detail. Moreover, to regulate a constant voltage at a DC-link capacitor, back propagation algorithm-based adaptive control schemes are designed. These adaptive schemes enhance the system performance by dynamically updating the control law parameters in case of PV intermittency. Furthermore, a proportional resonant controller based on Naslin polynomial method is designed for the current control loop. The method describes a systematic procedure to calculate proportional gain, resonant gain, and all the coefficients for the resonant path. Finally, the proposed system is simulated in MATLAB and Simulink software to validate the analytical and theoretical concepts along with the efficacy of the proposed model. Full article

Single-ended (SE) resonant inverters are widely used as power converters for high-pressure rice cooker induction, with 1200 V insulated-gate bipolar transistors (IGBTs) being used as switching devices for kW-class products. When voltage fluctuations occur at the input stage of an SE resonant inverter, the resonant voltage applied to the IGBT can be directly affected, potentially exceeding the breakdown voltage of the IGBT, resulting in its failure. Consequently, the resonant voltage should be limited to below a safety threshold—hardware resonant voltage limiting methods are generally used to do so. This paper proposes a sensorless resonant voltage control method that limits the increase in the resonant voltage caused by overvoltage or supply voltage fluctuations. By calculating and predicting the resonance voltage through the analysis of the resonance circuit, the resonance voltage is controlled not to exceed the breakdown voltage of the IGBT. The experimental results of a 1.35 kW SE resonant inverter for a high-pressure induction heating rice cooker were used to verify the validity of the proposed sensorless resonant voltage limiting method. Full article

This paper presents a tightly regulated multi-output isolated converter that employs only an independently regulated synchronous Single-Switched Post-Regulator (SSPR). The proposed converter is a highly accurate single-ended secondary side post-regulator based on a Series Resonant Converter (SRC); furthermore, it has a voltage-doubler characteristic. The proposed post-regulator requires only one auxiliary switch, in contrast with a bulky and expensive non-isolated DC–DC converter. Moreover, the added voltage-doubler can tightly regulate the slave output current. In addition, the voltage-doubler can improve electromagnetic interference characteristics and reduce switching losses arising from the Zero Current Switching (ZCS) operation of all power switches. The validity of the proposed converter is verified using experimental results obtained via a prototype converter applicable to an LED 3D TV power supply. Full article

Although an inductive power transfer (IPT) system can transfer power efficiently in full-load conditions, its efficiency obviously decreases in light-load conditions. To solve this problem, based on a two-coil IPT system with a series-series compensation topology, a single-ended primary-inductor converter is introduced at the secondary side. By adjusting the set effective value of the current in the primary coil, the converter input voltage changes to maintain the equivalent input resistance of the converter in an optimal condition. The system can then transfer the power efficiently with the wide load conditions. Moreover, the system operates at a constant resonance frequency with a high power factor. Both the simulation and experimentation of a prototype with a 10 W IPT system demonstrate the effectiveness of the proposed topology for wireless power transfer. Full article

In this paper, an interleaved high-power zero-current-switching (ZCS) onboard charger (OBC) based on the three-phase single-switch buck rectifier is proposed for application to plug-in electric vehicles (EVs). The multi-resonant structure is used to achieve high efficiency and high power density, which are necessary to reduce the volume and weight of the OBC. This study focuses on the border conditions of ZCS converting with a battery load, which means the variation ranges of the output voltage and current are very large. Furthermore, a novel hybrid control method combining pulse frequency modulation (PFM) and pulse width modulation (PWM) together is presented to ensure a driving frequency higher than 10 kHz, and this will reduce the unexpected inner resonant power flow and decrease the total harmonic distortion (THD) of the input current under a light load at the end of the charging process. Finally, a prototype is established, and experiments are carried out. According to the experimental results, the conversion efficiency is higher than 93.5%, the THD about 4.3% and power factor (PF) 0.98 under the maximum power output condition. Besides, a three-stage charging process is also carried out the experimental platform. Full article