Archives of Facial Plastic Surgery

Purpose This paper aims to present a novel Marx generator architecture designed to achieve a high repetition rate while minimizing charging losses. The proposed approach demonstrates how inductive charging can enhance efficiency and robustness in pulsed power systems. Design/methodology/approach This study begins with a theoretical analysis of the generator’s operation, followed by validation through numerical simulations and experimental tests. Findings The modified Marx generator achieves significant performance improvements, including a pulse amplitude of 50 kV, a rise time of 4.5 ns and a repetition rate of 50 pps. The results validate the effectiveness of inductive charging in reducing energy losses and improving system reliability. Originality/value This work introduces, simulates and experimentally validates an advanced Marx generator configuration. The findings highlight the potential of inductive charging to overcome the limitations of traditional resistive designs, offering a more efficient and reliable solution for high-frequency pulsed power applications.

Purpose This study aims to propose a comprehensive optimization and scheduling method for the combined heat and power (CHP) systems that takes into account the uncertainties of wind power and demand response. Design/methodology/approach The uncertainty of wind power and the “thermal-electric coupling” characteristics of CHP units have led to an increasing issue of wind power curtailment in CHP systems. With the objective of minimizing the overall scheduling cost of the CHP system, this paper considers the characteristics of interactive loads and wind power uncertainty, and establishes a coordinated optimization scheduling model for the generation-load-storage of the system, based on the inclusion of thermal energy storage devices. Findings During the optimization scheduling process, the proposed method in this paper reduces the scheduling cost by ¥99,900 (approximately 36.3%) compared to traditional methods, and significantly decreases the wind power curtailment rate by 53.7%. These results clearly demonstrate the significant advantages of the proposed method in enhancing the economic efficiency of the system and improving wind power integration. Research limitations/implications However, the planning process did not take into account the impact of unit combinations and grid structures. Practical implications This study proposes a comprehensive optimization and scheduling method for the CHP systems that takes into account the uncertainties of wind power and demand response. The objective function is to minimize the wind curtailment rate’s total scheduling cost, considering the impact of wind power uncertainties and demand response. A coordinated optimization and scheduling model for the generation-load-storage of CHP system is established. Social implications CHP units achieve the coupling of electric and thermal energy, significantly improving energy efficiency. In this study, the planning of the CHP system considers the coupling relationships among multiple energy sources, various devices and the pricing optimization spaces of electric and thermal forms of generation, storage and load-side. This approach has achieved favorable results in terms of economic operation scheduling and wind power accommodation improvement. Originality/value The case method is used to handle the uncertainty of wind power output on the generation side. Demand response is integrated on the load side to adjust user load curves. On the storage side, the thermal-electric coupling constraints of the CHP units are decoupled using thermal energy storage devices, while considering the economic benefits of all three parties involved: the power source, the load and the energy storage.

Purpose Wireless power transfer (WPT) technology is explored as a promising solution for electric vehicle (EV) charging due to its convenience and potential to overcome traditional charging limitations. This study aims to present a novel lightweight magnetic coupler design, square grid structure (SGS), specifically aimed at enhancing interoperability and robustness in the presence of misalignments for primary-side impedance tuning WPT systems adapted for EVs. Design/methodology/approach The proposed coupler design uses the finite element analysis method through ANSYS Electronics Desktop software for optimization. A comprehensive comparative analysis is conducted, focusing on critical magnetic parameters such as coupling coefficient (k), mutual inductance (M) and self-inductance (L) for different air gaps. Three other coupler designs, including circular, rectangular and DD configurations, are considered in the evaluation process. Additionally, the performance of the proposed coupler is assessed through misalignment tolerance in different directions, magnetic flux density (B), magnetic field strength (H), Energy density, Quality factor (Q) with mesh generation and thermal analysis using ANSYS Icepak design software. Findings The study presents findings from the comprehensive analysis, highlighting the performance of the proposed SGS coupler in terms of different key magnetic parameters, misalignment tolerance in different directions and various operational conditions. To verify the result for Practical implementation, MATLAB Simulink demonstrates a remarkable power transfer efficiency (PTE) of 94\%, exceeding alternative coupler designs. These findings emphasize the potential of the lightweight magnetic coupler to enhance the performance and practicality of WPT systems for EVs. Research limitations/implications Although the study offers valuable insights into the proposed SGS coupler design, there might be restrictions due to their hardware design being complex compared to other couplers and particular operating circumstances or environmental elements that were not considered during the investigation. Future studies could investigate these areas, focusing more on the shielding method to provide a more thorough knowledge of the coupler’s functionality. Originality/value This work advances WPT technology by presenting a novel SGS coupler design, which provides a robust and efficient solution for EV charging. The suggested lightweight magnetic coupler’s novelty and value in addressing the growing need for sustainable transportation solutions are highlighted by the significant improvement of 94% PTE.

Purpose This study aims to introduce an effective optimization algorithm for finding the suitable penetration of renewable distributed generators (RDGs) in the power system. The target of this research is to minimize the total costs, including the cost of emissions, the cost of purchasing electricity from the primary grid and the cost of branch power losses. Design/methodology/approach Energy valley optimizer (EVO) is applied to solve the optimization problem for determining the integration of photovoltaic units and wind turbine units in the system. This study considers the time variation of load demand and output power of units to improve the quality of the found solution. Simulation results are collected for evaluating the performance of the used methods in the same conditions. Findings The results indicated the huge economic and technical benefits from adopting the optimal solution of placement and sizing of RDGs in the power system. Besides, the outstanding efficiency of EVO is also proven through comparison with sunflower optimizer, drawer algorithm, osprey optimization algorithm, genetic algorithm, particle swarm optimization and artificial bee colony algorithm. Originality/value The mathematical models for the objective function and the constraints are appropriately described for the optimization problem. A simulation program for applying the optimization algorithms to the above problem is developed in the MATLAB software. The simulation results demonstrated the excellent benefits not only economically but also technically for the hybrid distribution system.

Purpose This paper aims to investigate and analyze the air-gap field modulation (AGFM) effect on torque contribution in a 6-slot/4-pole high-speed permanent magnet (HSPM) machine. To further illustrate the torque generation mechanism, the torque contribution is quantified using the Maxwell stress tensor (MST) method. Design/methodology/approach First, a simplified permanent magnet (PM) magnetomotive force model is established to identify the effective main-order working field harmonics. Then, the MST method is used to determine the average torque contributions of the effective main-order working field harmonics. Finally, the influences of various stator and rotor parameters on the AGFM effect are analyzed and optimized to enhance the torque density. Findings Apart from the fundamental harmonics, the AGFM harmonics contribute non-negligible average torque on the HSPM machine, and the optimized machine has higher torque density. Finally, a prototype of the 10 kW HSPM machine is manufactured and experimented with to validate the effectiveness of the theoretical analysis. Originality/value In this paper, the torque generation mechanism of the HSPM machine is investigated and analyzed. Meanwhile, the AGFM effect of the HSPM machine with different design parameters is analyzed and optimized to enhance the torque density.

Purpose The purpose of this paper is to investigate the moving boundary conditions on the sliding armature and rail (A/R) interface. As the computational domains involve both moving and stationary conductors, Lagrangian description and backward difference schemes are adopted for spatial and temporal discretization, arising discontinuities in variables. The proposed formulation can compute the current distribution under high velocities (∼km/s) without numerical oscillations and avoids mesh re-generation, saving computational resources. Design/methodology/approach The governing equations in Lagrangian description, backward difference schemes and derivations of moving boundary conditions are shown in detail. The interface matrix is explicitly enforced on the whole domain matrix and pseudocodes are presented for implementation. Moreover, shifted interpolated quantity method is proposed to deal with unevenly sized mesh, which can calculate acceleration scenarios and save computation resources under high velocities. Comparative calculations with previous methods under low velocities are conducted to verify the correctness of computational and physical models. Findings The current distributions with constant velocities are consistent with previous two-dimensional and low-velocity studies, further verifying the correctness of the method. The three-dimensional high-velocity results show that the current tends to concentrate near the trailing edge of A/R interface and diffuses into the bulks over time, with higher velocity contributing to less significant current diffusion. The velocity skin effect precedes the magnetic diffusion, conductivity and other factors that influence the current distribution. Originality/value The proposed methods can compute the current distributions in railgun under velocity accelerated to over 2,000 m/s, and the results provide more comprehensive understandings of the current evolution process under velocity skin effect in railgun.

Purpose Compared with the time-consuming numerical method and the complex lumped parameter thermal network method to solve the steady-state heat distribution of the permanent magnet (PM) linear motor, there is no analytical method based on the thermal partial differential equations. This paper aims to propose a two-dimensional (2-D) analytical model for predicting the steady-state temperature distribution of PM linear motors to improve the prediction accuracy and speed up the calculation. Design/methodology/approach Based on the complex Fourier series theory and Cauchy’s product theorem, this paper presents for the first time a general analytical solution for 2-D temperature field in Cartesian coordinates. Then, by combining the electromagnetic field finite element model (FEM), the copper loss, iron loss and PM eddy current loss are used as the heat sources of the thermal analytical model. Finally, the solution to the temperature field is obtained by solving the system equations under boundary and interface conditions. Findings The analytical results are in good agreement with those from the thermal FEM, and the calculation speed is significantly faster than that of the thermal FEM. Originality/value The multilayer model proposed in this paper can consider heat conduction, convection and radiation. It is not only suitable for PM linear motors but also has significant application value for the thermal analysis of electromagnetic devices modeled in 2-D Cartesian coordinates.

Purpose The purpose of this paper is to explore how fractional derivatives affect the transient and steady-state behaviour of nonlinear transmission lines. This problem is of significance for high-frequency design of systems such as high-speed sampling systems and radar systems. Design/methodology/approach This paper shall consider the transient and steady-state responses of nonlinear transmission lines when fractional derivatives are considered. A lumped-parameter model is considered and the product-integration implicit trapezoidal rule shall be used for simulations. Findings The important observation is that small deviations of the order of the derivative from an integer order can have a significant effect on the transient and steady-state behaviour. This includes a change in the speed of the wave on the transmission line and on its damping. Originality/value The work is novel as it uses a lumped-parameter model with nonlinear capacitors and explores the effect on the dynamical behaviour when fractional derivatives are present. This is in contrast to the typical approach of using a partial differential equation derived under certain assumptions such as the nature of the nonlinear capacitor.

Purpose This paper aims to an analytical investigation of a consequent poles (CP) permanent magnet machine, to enhance the accuracy of the predicted air gap flux density and thus of the machine performance. Design/methodology/approach The machine under study is obtained by the substitution of the poles machines (PMs) that corresponds to south poles, of a conventional surface PM (SPM) machine, by iron pieces of same geometry. First, the analytical model of the air gap flux density generated by a SPM topology is presented. To fit the CP concept, such model has been rearranged based on a virtual SPM machine. Then, an improved prediction of the CP machine air gap flux density is addressed by the incorporation of a south pole rotor correction function. Findings An improved prediction of the consequent pole PM machines air gap flux density is addressed by the incorporation of a south pole rotor correction function. Originality/value The paper proposes an original approach to enhance the prediction of the air gap flux density of consequent pole machines despite the different magnetic permeability of the north and south poles.

Purpose This paper aims to investigate the reliable thickness, and more generally, the geometric and material parameter determination of thin electrically conductive and diamagnetic coatings on conductive and ferromagnetic substrates, e.g. steel, using eddy current testing (ECT). Design/methodology/approach The analytical model of an ECT coil arrangement known from the literature is analyzed to evaluate the numerical simulation performed by a Finite Element (FE) program. The latter is used to investigate the influence of the sheet edge on the measurement result. Finally, a measurement setup is presented and the unknown geometric and material parameters are estimated from measurement data of different sample sheets at different air gaps. Findings Generally, valid mesh rules are found for a very accurate FE analysis of eddy current problems with large air gaps. The influence of large air gaps on the parameter estimation is emphasized. Moreover, the formulated hypotheses can be widely confirmed by measurements. Research limitations/implications In this paper, electrical steel sheets coated with a conductive oven-cured ink are used. This sample configuration creates a discrete transition between the substrate and the coating as present in the analytical modeling approaches. Furthermore, the ferromagnetic substrate’s nonlinear B-H curve is not considered in the analytical model so far. Originality/value The analytical model is known from the literature. However, real practical measurements have not been carried out with the discussed setup. Furthermore, well-known literature on eddy current measurements usually only considers constant and very small air gaps.

Purpose Recent progress in additive manufacturing methods alleviated manufacturing constraints on devices. Topology optimization (TO) methods can leverage these reduced limitations and this paper aims to study the use of these algorithms in induction heating for injection molding. Design/methodology/approach In this paper, TO is used to reduce the volume of ferrite in an injection molding tool while aiming at maximizing the performance of the device. Characteristics of the proposed solution such as efficiency and power density are compared to the ones of the original device. Findings The study shows that it is possible to reduce significantly the amount of ferrite used without impacting the efficiency. The thermal performances of the proposed solution present also slight improvements compared to the original solution. Originality/value Optimization algorithms are important for understanding how to design efficient electrical devices. In this paper, the application of TO for injection molding applications presents a new perspective in designing such components.

Purpose Power transformers are vital components of an electrical network. A defective transformer can cause instability and blackouts in parts of the network. An accurate classification of different transformer faults results in a relatively accurate fault diagnosis and timely corrective actions. It is possible to increase productivity and reduce costs by using fault detection of power transformers through the analysis of gases dissolved in oil. The proposed technique is a suitable tool to help the utilities and engineers in charge of preventive maintenance by reducing the costs of different fault diagnosis tests for power transformers. Design/methodology/approach In this paper, the IEC 60599 standard along with clustering and classification methods are used to classify power transformer’s fault types. K-means and Fuzzy C-means clustering methods are used for clustering, and the support vector machine (SVM) method is used for classification of different types of faults in ‎power ‎transformers. The performance of K-means and SVM methods is improved by using the Grasshopper Optimization Algorithm (GOA). The efficiency of the proposed methods is evaluated using real field data of power transformers. The purpose of this study is to propose hybrid methods including K-means-GOA clustering and SVM-GOA classification for accurate fault diagnosis. These methods have been used for the first time in fault diagnosis determination of power transformers through gas analysis. The Silhouette criteria is used in this paper to compare the efficiency of different clustering methods. Findings Simulation results of the paper are based on the gas chromatography data related to 266 different real power transformers. They show the high accuracy and high-performance speed of intelligent clustering and classification methods compared to conventional ones. This analysis would be helpful in performing the required maintenance check and plan for repairs. Originality/value The applicability and efficiency of the proposed hybrid K-means-GOA and SVM-GOA models are verified for transformer fault detection using the experimental diverse data set including 266 set of real field test parameters of power transformers.

Purpose The purpose of this paper is to present the performance requirements for the all-electric high lift motors and the inductance calculation process for the fractional slot concentrated winding. Design/methodology/approach This paper presents the research work related to all-electric aircraft high lift motors and the inductance calculation process of fractional slot concentrated winding. Firstly, this paper introduces the performance requirements for the high lift motor and summarizes the general process for calculating the inductance in fractional slot motors. Secondly, the analytical model of winding armature total inductance is obtained by the winding function method. Thirdly, a straightforward calculation method is employed for determining the total slot leakage inductance. Finally, the accuracy of the inductance calculation and controllability of the motor are confirmed through finite element model and motor control strategies. Findings In the fractional slot concentrated winding, the armature total inductance is equal to the armature self-inductance plus the armature mutual inductance. The slot leakage inductance is divided into the slot leakage self-inductance and the slot leakage mutual inductance. This allows inductance to be obtained quickly without finite element model. Originality/value This paper provides the inductance results of analytical and finite element simulation; the control strategy is employed to verify the conformity of the design requirements and control performance under the rated conditions. The implementation of double verification assures the practicality and effectiveness of the high lift motor.

Purpose This paper aims to facilitate reliable online diagnosis of early faults in the stator winding inter-turn short circuits of induction motors (IMs) under various operating conditions. Design/methodology/approach A novel fault characteristic component, the characteristic current amplitude, is proposed for the fault. Defined as the product of short-circuit coefficient and short-circuit current, the characteristic current is derived from the positive and negative-sequence components of the stator-side current and voltage. Findings Simulation models of the IMs pre- and postfault, along with an experimental platform for the motor’s inter-turn short circuit, were established. The characteristic current amplitude proves more robust against voltage unbalance and load variations, which offers enhanced reliability and sensitivity for early fault diagnosis of inter-turn short circuit in IMs stator windings. Originality/value A novel feature is proposed. Compared with negative-sequence current, which is considered as a traditional fault feature, the characteristic current amplitude exhibits a greater robustness against the imbalanced conditions, which simultaneously possesses the attributes of both reliability and expeditiousness in fault detection.

Purpose This study aims to propose a new connection technique of bypass diode (BD) in photovoltaic (PV) array, which reduces the circulating current (CC) within PV modules as well as conduction loss in partial shaded condition (PSC). Design/methodology/approach Linearized circuit model of PV panel is proposed for calculating the CC and power loss of novel BD arrangements in PV array. From the analysis the best BD arrangement is applied in series parallel, TCT and honeycomb (HC) PV array structure for simulation and hardware verification. The hardware verification is performed in a 3 × 3 PV array, where individual panel capacity is 200 W. Findings The proposed BD arrangement reduces the power loss due to CC under PSC by almost 3% compared to conventional BD structure in a PV array. Originality/value The proposed BD arrangement is simple and useful in large PV power plants to reduce the CC-based extra power loss under PSC.