Search Results (915)

Hybrid stepper (HB) motors are widely used in precision actuation systems such as cryogenic refrigerator robotic arms. Under cryogenic working conditions, the core loss characteristics of magnetic materials change significantly, while conventional core loss models calibrated at room temperature can hardly provide reliable prediction accuracy. In this work, the electromagnetic properties of 35SW1900 non-oriented silicon steel were measured from 25 °C − 100 °C using a BROCKHAUS Epstein frame system. Variations in permeability, core loss and coercivity with magnetic flux density, temperature and frequency were obtained. An improved core loss model was developed by introducing a flux-dependent exponent and dual temperature correction coefficients for hysteresis and eddy current losses. Experiments place the prediction error of the proposed model within 4% under cryogenic conditions. Compared with the classical Bertotti model, the proposed model effectively reduces high-frequency deviation caused by the temperature-dependent material properties and skin effect. The core loss of silicon steel increases by 15–30% at −100 °C compared with room temperature, which is mainly attributed to the decrease in resistivity and the strengthening of domain wall pinning. This paper provides an accurate loss prediction method and design references for HB motors applied in ultralow temperature working conditions. Full article

To address dependence on external power and the limited capability of conventional hydroelectric units to detect low-amplitude vibrations, this work introduces a self-contained, highly accurate monitoring device. The design incorporates a magnetically levitated configuration, with triboelectric films placed on both the upper and lower faces of the floating magnet. Under minor oscillations, magnetic repulsion increases the relative displacement between the friction layers, producing a substantial voltage that permits low-level vibration sensing. A surrounding induction coil responds to the levitated pole’s vertical motion; this motion intersects the magnetic flux, generating a current that provides stable energy for wireless data transmission. Experimental outcomes confirm a detection limit of 0.1 mm. At an amplitude of 1 mm and a load of 1000 Ω, the system achieves a maximum output of 9 mW and a power density of 1.587 W/m², ensuring reliable power. This configuration provides a new pathway for monitoring vibrations in hydroelectric turbine generators. Full article

Interior permanent magnet synchronous motors (IPMSMs) offer performance advantages such as saliency effect, high mechanical strength, and a wide speed regulation range. The magnetic and mechanical properties of the core material significantly influence IPMSM performance. By investigating the effects of different core materials on IPMSM performance, an optimal material combination can be identified to enhance the overall motor performance. This paper takes a $\overline{\mathrm{V}}$-shaped IPMSM for use as a main drive motor in new energy vehicles as the research object. First, the influence of the iron loss characteristics of non-oriented silicon steel (NOSS) on IPMSM performance is analyzed, and the material selection principles for the stator and rotor cores under this condition are summarized. Subsequently, the influence of the magnetic flux density characteristics of NOSS on IPMSM performance is analyzed, and the corresponding material selection principles for the stator and rotor cores are summarized. Furthermore, ultra-high-yield-strength NOSS is applied as the motor core material to reduce the width of the rotor magnetic flux barrier, and the resulting performance advantages for the IPMSM are analyzed. Finally, prototypes of the IPMSM are manufactured and tested to validate the results of the analysis. Full article

Due to the widespread adoption of high-performance electric vehicles (EVs), Interior Permanent Magnet (IPM) machines have achieved significant advancement in the field of electric motors due to their high torque density and efficiency. However, research has been ongoing for many decades to suppress the rare-earth permanent magnet (PM) usage without sacrificing electromagnetic performance while still achieving the required torque, power, and efficiency. In this regard, various EV manufacturers, such as Honda, Toyota, Chevrolet, BMW, and Nissan, have developed different types of IPM topologies; however, the rare-earth PM usage is extensively high, and the torque density is lower. Thus, to reduce the PM consumption and improve the electromagnetic performance, especially torque density, this paper proposes a novel segmented delta-shaped IPM (SΔ-IPM) with a three-notched rotor pole shape having two different specifications and featuring embedded circular flux barriers and an intermediate flux bridge. Secondly, torque performance is analytically discussed, and electromagnetic performance has been evaluated using 2D finite element analysis (FEA). Due to its unique design featuring improved magnetic field shifting, an average torque of 393.7 Nm with torque ripples of 5.1% and a cogging torque of 0.57 Nm has been achieved. Finally, an extensive comparative analysis of the aforementioned ten state-of-the-art industry models has been conducted, which confirms the effectiveness of the proposed design for high torque density with minimum PM usage. Full article

This paper deals with the investigation of the best topology of a five-phase fault-tolerant spoke-type permanent magnet (PM) motor for the propulsion of a multirotor aerial vehicle. This study is carried out through four stages. First, an assessment of the PM configuration effect on motor performance, considering three positions, namely surface PM, spoke-type PM, and V-shape PM. Second, an evaluation of the optimisation formulation problem on motor performance, where three formulations, respectively, involving either electric motor (EM) efficiency, EM efficiency and torque, or EM efficiency and active weight are considered for this purpose. Third, the stator winding configuration effect on performance in healthy and faulty operation mode (OM), e.g., open-circuit fault (OC) and inter-turn short-circuit (ITSC) fault, is also assessed. This evaluation is performed considering two winding configurations, namely fractional slot concentrated winding (FSCW) with single-layer (SL) or dual-layer (DL) winding. Fourth, a modified rotor geometry is proposed, based on the airgap length variation, in order to increase the airgap flux density amplitude and thus improve the motor torque and power densities. A comparative study, in this case, is performed with a classical rotor geometry in order to assess their influence on motor performance in healthy and faulty operation mode (OM). In addition, this paper presents a quantitative comparison of the proposed five-phase motor and a three-phase spoke-type PM motor, where the results, in healthy and faulty OM, show the interest of the proposed multiphase motor. Full article

Outer rotor permanent magnet synchronous motors (ORPMSMs) are widely used in drone and aircraft propulsion due to their high power density. However, conventional arc-shaped designs involve an inherent trade-off between efficiency and torque ripple. Increasing the arc curvature improves the sinusoidal air gap flux density and reduces torque ripple, but it also increases rotor eddy current loss due to larger flux variations, thereby degrading efficiency. This paper investigates the effects of stator and rotor geometries on rotor eddy current loss and torque ripple in ORPMSMs. To address this trade-off, arc- and rectangular-shaped rotor and stator pole shoes are combined to form four design candidates. Their electromagnetic performance is evaluated using finite element analysis. Based on this comparison, a configuration with rectangular rotor and stator pole shoes is selected as the initial design and further optimized using a multi-objective genetic algorithm to simultaneously improve efficiency and torque ripple. The optimized design demonstrates significant improvements, achieving reductions of 56.67% in peak-to-peak torque ripple and 46.89% in rotor eddy current loss compared to the initial design. Full article

This paper proposes a novel arch-shaped-magnet variable-flux memory machine (ASM-VFMM). The proposed machine adopts a dual-layer permanent magnet (PM) rotor structure. In the first layer, an arch-shaped magnet arrangement is utilized to increase the volume of low-coercive-force (LCF) magnets, which contributes to improved magnetic flux adjustment (MFA) performance. The second layer incorporates an asymmetric PM (APM) layout to create a parallel magnetic circuit, enabling further suppression of air-gap flux density at the weakened-flux state. The topological development of the proposed machine is first described, covering the conventional series magnetic circuit (SMC) structure, the intermediary APM structure, and the proposed ASM structure. A theoretical modeling analysis is then conducted for the three machines. This confirms the superiority of the proposed design regarding its MFA capability. A comprehensive electromagnetic performance evaluation is carried out for the proposed machine, alongside comparative assessments of the other two machines. The results show that the proposed design outperforms the other two machines in terms of magnetization performance, MFA range, and on-load magnetization stabilization capability. Notably, the proposed machine exhibits excellent overall efficiency characteristics, especially under high-speed operating conditions. Full article

The planning and design of Extra-High Voltage (EHV) overhead power lines require strict adherence to electromagnetic field exposure limits to ensure public safety. This paper presents a comprehensive analysis of the minimum ground clearance required for standard 400 kV transmission towers to comply with international safety guidelines. A review of legislative frameworks across 37 countries indicates a widespread consensus on limiting values of 5 kV/m for the electric field and 100 $\mathsf{\mu }$T for magnetic flux density. Using analytical methods, the electric and magnetic fields were calculated for four common tower geometries (Cat, Portal, Danube, and Barrel) under varying ground clearances and phase configurations. The results demonstrate that the magnetic flux density is not a limiting factor, as it remains well below safety thresholds even at standard technical clearances. Conversely, the electric field intensity proves to be the critical design constraint, often requiring clearances significantly higher than those dictated by insulation coordination. The study identifies that optimizing the phase sequence in double-circuit towers can reduce the required ground clearance by up to 28%, offering a cost-effective mitigation strategy. These findings provide power line designers with essential decision-making data for the preliminary design phase, enabling the optimization of tower geometry and phase arrangement without the need for computationally intensive simulations. Full article

The purpose of this research is to determine which factors contribute to extending the read range of transponders equipped with different coupling-circuit topologies operating within selected RFID frequency bands. The analysis covered transponders that varied in both the configuration of their coupling circuits and their geometric dimensions. To accomplish this, transponder models were created using the EMCoS Studio electromagnetic simulation environment. Each model was subjected to simulations that yielded the mutual inductance and the voltage induced at the chip terminals. This study examines how the impedance of the embroidered antenna, the impedance of the chip’s coupling circuit, and the magnetic flux density affect the resulting chip voltage. In several of the investigated configurations, the peak chip voltage appeared outside the frequency range normally associated with RFID systems. The frequency at which this maximum occurred was dependent on the mutual inductance value. Understanding how individual parameters influence mutual inductance makes it possible to shift the voltage peak into a target operating band. Numerical simulation results, combined with the transponder’s mathematical model, enabled the calculation of the mutual inductance and the terminal voltage—quantities that directly determine the achievable read range. This study focuses on factors such as the resonant frequencies of the antenna and coupling circuit, their impedances, and the characteristics of the magnetic field. The findings show that tuning these parameters can affect not only the location of the voltage maximum, but also its amplitude. This effect introduces additional complexity in designing and selecting suitable transponder configurations. Full article

The Axial Flux Permanent Magnet Synchronous Motor (AFPMSM) has gained significant attention as a core power source for next-generation industrial sectors, including electric vehicles, wind turbines, robot joints, and drone propulsion motors, due to its high power density from a short axial length and large radial dimensions. Despite these structural advantages, cogging torque caused by magnetic interaction between the stator teeth and permanent magnets remains a critical drawback, inducing noise and vibration. While conventional Soft Magnetic Composite (SMC) core methods facilitate 3D flux paths, they suffer from low magnetic permeability, insufficient mechanical strength, and manufacturing complexity. To address these issues, this study proposes a stepped structure model utilizing electrical steel sheets to effectively reduce cogging torque. This structure features radial stacking of identical electrical steel sheets with varying widths, where each layer’s center is incrementally shifted in the rotational direction. This configuration achieves an effect analogous to continuous skewing without specialized 3D machining. To validate the proposed design, 3D Finite Element Analysis (FEA) was conducted. Results demonstrate that the peak-to-peak cogging torque was reduced to approximately 86% of the conventional model’s value, while maintaining the back-EMF reduction rate within 5%. By presenting a novel skewing technique, this research provides a practical alternative for high-precision and high-power AFPMSM. Full article

This paper presents the results of numerical calculation of steady-state magnetorheological fluid flow in the gap of an eccentric seal subjected to an external radial magnetic field. A coupled problem combining magnetic field analysis and laminar viscoplastic flow with Bingham rheology is solved to obtain pressure and velocity distributions within the seal gap, from which the hydrodynamic reaction forces of the fluid film and the rotor friction torque are determined. A parametric study was conducted in the ranges of rotor angular velocity ω = 100–400 rad/s, relative eccentricity ε = 0–0.9, and magnetic flux density B₀ = 0–0.5 T at the pressure differential Δp = 2 atm. Analysis of the results shows that increasing the magnetic flux density from 0 to 0.5 T leads to an increase in the seal reaction force from 12 N to 642 N and the friction torque from 0.35 N·m to 11.23 N·m. The most intensive growth of both characteristics is observed in the range B₀ = 0–0.3 T, beyond which saturation occurs as the MRF yield stress reaches its plateau value. An optimal control range of B₀ = 0.1–0.2 T was determined, ensuring maximum seal energetic efficiency as quantified by the load capacity-to-friction torque ratio, which is maximized at 70 N/(N·m). Based on the obtained results, the consequences of using magnetorheological seals on the performance of the rotor system are discussed, including the analysis of the sealing effect on rotor-dynamic stability. Within the proposed optimal range, it is shown that an increase in magnetic flux density leads to a sign reversal of the horizontal reaction F₂, while the monotonic growth of the ratio |F₂|/F₁ indicates an intensification of cross-coupling and a corresponding reduction in the rotordynamic stability margin at higher values of B₀. Full article

With the advancement of digital hydropower stations, the requirements of real-time, high-precision industrial soft measurement of key power equipment operating status are attracting more and more attention. However, it is difficult to transfer energy to the monitoring sensor in strong electromagnetic environments. In this paper, a high-efficiency, high-power-density magnetic field energy harvester is proposed for monitoring sensors in hydropower stations, which captures the energy from the magnetic flux leakage of a hydroelectric generating set. Efficient magnetic energy capture is achieved by modeling material properties and optimizing the receiver’s magnetic core parameters via a Genetic Algorithm. The theoretical analysis of charging characteristics is given, and a Maximum Power Point Tracking (MPPT) control circuit is proposed, realizing high-efficiency energy conversion. Finally, an experimental planet is built. Under 70–130 Gs power-frequency magnetic fields, the system delivers 2.8–5.1 V open-circuit voltage, 66 mW maximum load power, and 6.5 mW/cm³ power density. Full article

The increasing deployment of shared transmission corridors for High-Voltage Alternating Current (HVAC) and High-Voltage Direct Current (HVDC) systems has intensified the need to evaluate electromagnetic compatibility in hybrid overhead line configurations. This study presents an analytical methodology to estimate the electric field magnitude and magnetic flux density generated by hybrid HVAC–HVDC transmission lines under steady-state operating conditions. The electric field is determined using the Maxwell potential matrix combined with the image method, while the magnetic field is obtained from a formulation based on the Biot–Savart law. Two representative case studies were analyzed with identical electrical operating conditions but different transverse conductor arrangements to evaluate the influence of geometry on the electromagnetic environment of the corridor. The results show that variations in the spatial configuration of the conductors produce noticeable changes in the location and magnitude of the electric and magnetic field maxima across the right-of-way. These findings demonstrate that conductor geometry plays a key role in the electromagnetic behavior of hybrid corridors and should be considered in the design and assessment of HVAC–HVDC transmission systems. Full article

This paper presents the design, prototype realization, and experimental validation of an inductive wireless power transfer (WPT) platform for static charging of electric vehicles. The study integrates magnetic-coupler design, resonant power-stage realization, and occupied-area magnetic-field assessment within a prototype-oriented engineering framework. The realized Tx/Rx magnetic assembly has dimensions of approximately 700 × 800 × 60 mm per coil, an inductance of about 60 μH, a coupling factor of about 0.45, and estimated coil losses of around 2%. The proposed system belongs to the 35 kW class, while the realized prototype was experimentally validated at a nominal 30 kW operating level, with peak capability up to 45 kW for 1 min. Experimental evaluation was carried out for air gaps up to about 100 mm, with measured transfer efficiency in the range 80–92% and favorable operation around 30 kW and a vertical air gap of approximately 70 mm. Representative occupied-area magnetic-flux-density measurements remained below the adopted 27 μT reference level under the reported operating conditions. The results confirm the practical feasibility of the proposed static EV charging platform and support its engineering relevance for high-power inductive charging applications. Possible extension toward on-route charging is discussed only as future work. Full article

This study presents a systematic topological progression and multi-objective optimization of a Permanent Magnet-assisted Non-overlapping Winding Line-Start Synchronous Reluctance Motor (PMaNWLS-SynRM) for industrial applications. To explicitly highlight the core contribution, the research establishes a rigorous comparative framework evaluating the transition from a conventional 4-pole/36-slot distributed winding (DW) to a 2 × 12-slot non-overlapping winding (NW) architecture. Baseline results demonstrate that the NW configuration shortens end-turns, successfully reducing total electromagnetic losses from 417 W to 349 W and improving steady-state efficiency from 93.7% to 95.1%. To overcome the inherent starting limitations of pure synchronous reluctance machines, an aluminum squirrel-cage is integrated to enable robust direct-on-line (DOL) synchronization, while NdFeB permanent magnets are embedded within the rotor flux barriers to mitigate asynchronous spatial harmonics and elevate torque density. Finite element analysis (FEA) confirms this magnetic assistance raises the average synchronous torque to 65.8 Nm while suppressing absolute torque ripple to 1.37 Nm. Finally, an evolutionary genetic algorithm is deployed across 440 iterative configurations to resolve geometric multi-physics conflicts. The finalized optimized design achieves a 13.2 kW output power at 1800 rpm, maximizing average torque to 70.12 Nm and strictly dampening absolute torque ripple to an industry-acceptable 1.04 Nm. Operating with an aggregated total loss of 1382 W, the optimized PMaNWLS-SynRM yields a 90.5% operational efficiency, definitively validating its suitability as an ultra-premium IE4/IE5 alternative to conventional induction motors. Full article