Search

Static encephalopathy of childhood with neurodegeneration in adulthood/β-propeller protein-associated neurodegeneration is a neurodegenerative disorder with brain iron accumulation caused by the variants of WDR45, a core autophagy-related gene that encodes WD repeat domain phosphoinositide interacting protein 4. However, the pathophysiology of the disease, particularly the function of WDR45/WD repeat domain phosphoinositide interacting protein 4 in iron metabolism, is largely unknown. As no other variants of core autophagy-related genes show abnormalities in iron metabolism, the relation between autophagy and iron metabolism remains to be elucidated. Since iron deposition in the brain is the hallmark of static encephalopathy of childhood with neurodegeneration in adulthood/β-propeller protein-associated neurodegeneration, iron chelation therapy has been attempted, but it was found to worsen the symptoms; thus, the establishment of a curative treatment is essential. Here, we evaluated autophagy and iron metabolism in patient-derived cells. The expression of ferritin and ferric iron increased and that of ferrous iron decreased in the patient cells with WDR45 variants. In addition, the expression of nuclear receptor coactivator 4 was markedly reduced in patient-derived cells. Furthermore, divalent metal transporter 1, which takes in ferrous iron, was upregulated, while ferroportin, which exports ferrous iron, was downregulated in patient-derived cells. The transfer of WDR45 via an adeno-associated virus vector restored WD repeat domain phosphoinositide interacting protein 4 and nuclear receptor coactivator 4 expression, reduced ferritin levels, and improved other phenotypes observed in patient-derived cells. As nuclear receptor coactivator 4 mediates the ferritin-specific autophagy, i.e. ferritinophagy, its deficiency impaired ferritinophagy, leading to the accumulation of ferric iron-containing ferritin and insufficiency of ferrous iron. Because ferrous iron is required for various essential biochemical reactions, the changes in divalent metal transporter 1 and ferroportin levels may indicate a compensatory response for maintaining the intracellular levels of ferrous iron. Our study revealed that the pathophysiology of static encephalopathy of childhood with neurodegeneration in adulthood/β-propeller protein-associated neurodegeneration involves ferrous iron insufficiency via impaired ferritinophagy through nuclear receptor coactivator 4 expression reduction. Our findings could aid in developing a treatment strategy involving WDR45 manipulation, which may have clinical applications.

Niemann–Pick disease type C1 (NPC1) is a fatal congenital neurodegenerative disorder caused by mutations in the NPC1 gene, which is involved in cholesterol transport in lysosomes. Broad clinical manifestations of NPC1 include liver failure, pulmonary disorder, neurological deficits, and psychiatric symptoms. The main cause of death in NPC1 patients involves central nervous system (CNS) dysfunction; there is no essential treatment. We generated a tyrosine-mutant adeno-associated virus (AAV) 9/3 vector that expresses human NPC1 under a cytomegalovirus (CMV) promoter (AAV-CMV-hNPC1) and injected it into the left lateral ventricle (5 μL) and cisterna magna (10 μL) of Npc1 homo-knockout (Npc1−/−) mice. Each mouse received total 1.35 × 1011 vector genome on days 4 or 5 of life. AAV-treated Npc1−/− mice (n = 11) had an average survival of >28 weeks, while all saline-treated Npc1−/− mice (n = 11) and untreated Npc1−/− mice (n = 6) died within 16 weeks. Saline-treated and untreated Npc1−/− mice lost body weight from 7 weeks until death. However, the average body weight of AAV-treated Npc1−/− mice increased until 15 weeks. AAV-treated Npc1−/− mice also showed a significant improvement in the rotarod test performance. A pathological analysis at 11 weeks showed that cerebellar Purkinje cells were preserved in AAV-treated Npc1−/− mice. In contrast, untreated Npc1−/− mice showed an almost total loss of cerebellar Purkinje cells. Combined injection into both the lateral ventricle and cisterna magna achieved broader delivery of the vector to the CNS, leading to better outcomes than noted in previous reports, with injection into the lateral ventricles or veins alone. In AAV-treated Npc1−/− mice, vector genome DNA was detected widely in the CNS and liver. Human NPC1 RNA was detected in the brain, liver, lung, and heart. Accumulated unesterified cholesterol in the liver was reduced in the AAV-treated Npc1−/− mice. Our results suggest the feasibility of gene therapy for patients with NPC1.

To reduce the iron loss and noise of a three-phase reactor composed of grain-oriented (GO) steel plates, two types of core structures are proposed in this article. In the first type, the ordinary brick core model is improved to a hybrid one composed of GO and nonoriented steel plates, and in the second type, the T-joint part of the ordinary oblique-joint core model is improved to a straight joint. To show the effectiveness of the improved models, the iron loss and displacement distributions in the four core structures are evaluated using the 2-D magnetic field and mechanical analyses. In these analyses, the magnetic characteristics of the anisotropic cores are considered in detail. Namely, in the magnetic field analysis, the ${B}$ – ${H}$ curves in the arbitrary directions are considered. In the iron loss calculation, the rotational iron loss is calculated using the iron loss curves in the arbitrary directions. Moreover, the methods of calculating the displacements due to electromagnetism and magnetostriction considering the anisotropic ${B}$ – ${H}$ curves and magnetostriction in the arbitrary directions are proposed. It is shown that the iron losses and displacements of the two proposed core structures can be reduced compared with the ordinary ones. Moreover, the second proposed model is the most attractive one because both the iron loss and displacement are smaller than the other models.

Introduction Metachromatic leukodystrophy (MLD) refers to leukodystrophy caused by the accumulation of sulfatide from arylsulfatase A (ARSA) gene mutations. Sulfatide also accumulates in various organs, including the peripheral nerves, kidney, and gallbladder. Proliferative changes in the gallbladder have been reported in several patients, while gallbladder cancer is reported in only two adult MLD cases. We report what is likely the first pediatric case of MLD with gallbladder cancer. Case report The patient was a 5-year-old girl diagnosed with MLD using head magnetic resonance imaging and detecting a homozygous mutation of c.302G>A (p.Gly101Asp) in ARSA. Abdominal bloating was observed at the age of 4 years; CT revealed a giant tumor in the gallbladder and massive ascites. Cholecystectomy was performed and pathological examination revealed adenocarcinoma. Measurement of serum sulfatide revealed increased levels compared to the average healthy range. Discussion Rapidly increased ascites and large polyps which are reported as risk factors for cancer were characteristic in our MLD case. When such lesions are detected, they should be removed immediately because of the possibility of cancer, even in a pediatric patient.

Cerebellar hypoplasia and atrophy (CBHA) in children is an extremely heterogeneous group of disorders, but few comprehensive genetic studies have been reported. Comprehensive genetic analysis of CBHA patients may help differentiating atrophy and hypoplasia and potentially improve their prognostic aspects.Patients with CBHA in 176 families were genetically examined using exome sequencing. Patients with disease-causing variants were clinically evaluated.Disease-causing variants were identified in 96 of the 176 families (54.5%). After excluding 6 families, 48 patients from 42 families were categorized as having syndromic associations with CBHA, whereas the remaining 51 patients from 48 families had isolated CBHA. In 51 patients, 26 aberrant genes were identified, of which, 20 (76.9%) caused disease in 1 family each. The most prevalent genes were CACNA1A, ITPR1, and KIF1A. Of the 26 aberrant genes, 21 and 1 were functionally annotated to atrophy and hypoplasia, respectively. CBHA+S was more clinically severe than CBHA-S. Notably, ARG1 and FOLR1 variants were identified in 2 families, leading to medical treatments.A wide genetic and clinical diversity of CBHA was revealed through exome sequencing in this cohort, which highlights the importance of comprehensive genetic analyses. Furthermore, molecular-based treatment was available for 2 families.

A fault current limiter is an effective mean of limiting fault currents. The simultaneous use of three single-phase current limiters requires significant amounts of ferromagnetic material and space. This article proposes a three-phase saturated-core fault current limiter (T-SCFCL) that employs a common yoke and a permanent magnet to mitigate the restrictions of material and space. T-SCFCL delivers good performance for single-phase, two-phase, and three-phase faults. In this configuration, flux flowing through the permanent magnets is generated by a three-phase unbalanced current, thereby reducing the loss in eddy current and improving stability while significantly reducing the volume of the core. An algorithm is provided for use in the design of the FCL structure. A simulation was conducted based on the finite element method and a prototype manufactured and tested to verify effectiveness. The results prove that the proposed method is efficient.

With the continuous expansion of power grid capacity, the problem of short-circuit current exceeding the standard is becoming increasingly serious. Fault current limiter is a promising solution and is gradually becoming a research hotspot. In this study, fault current limiters are classified into four categories. And saturated-core fault current limiters are emphatically introduced, including its working principle and comparison with the other three categories. Saturated core fault current limiters are divided into four branches according to the ways leading the core saturated. A comprehensive review of the research activities and emerging technologies of saturated-core fault current limiters for AC power systems is presented in this study. The working principle and typical structure of DC-biased-, permanent-magnet-, superconducting- and hybrid-type saturated-core fault current limiters are introduced. The advantages and disadvantages of four types of saturated core fault current limiters are compared in detail from the aspects of current-limiting performance, iron core size and DC magnetomotive force. Real grid application examples of some types of devices are presented, as well as new progress in the techniques, are covered and discussed in detail. One may find the content of this study helpful as a detailed literature review or as practical technical guidance.

Large fault direct current with fast rising speed has always been a significant threat to high voltage direct current systems. Fault current limiters (FCLs) are one of the most promising solutions. However, the biased permanent magnets (PM)s in traditional FCLs have large magnetic reluctance that causes FCLs to have small inductance changing ratios when a fault occurs. In this study, a novel three-limb topology of a saturated iron core-type fault current limiter (TSFCL) is proposed and a central PM bias limb is inserted to force flux flow through this limb. Therefore, the inductance changing ratio is greatly enhanced and the steep rising trend of fault current will be restrained effectively. The operating principles and characteristics of the TSFCL are analyzed to verify the deductions. Moreover, different lengths and cross-sectional areas of the inserted PM are tested and optimization study is carried out. The results show that the clipping inductance has a 55% increase compared with a traditional two-limb model. Moreover, compared with the existing smoothing reactor and traditional two-limb model, proposed topology can decrease the fault current by 45% and 16% within 5 ms, respectively. Finally, a typical HVDC system was built and the effectiveness of proposed TSFCL was verified.

Soft magnetic composites (SMCs) are composed of ferromagnetic particles surrounded by electrical insulation. To establish a homogenization technique for the magnetic field analysis of an electrical machine with an SMC core, we have already proposed a method to evaluate the effective permeability and iron loss of the SMC core using a cell model of one particle taking into account the nonlinear magnetic characteristics and eddy currents. However, the measured eddy current loss cannot be represented by using the proposed method. In this article, a 3-D eddy current analysis method modeling the anomalous eddy current loss due to the movement of domain walls in the cell model is developed based on the Pry and Bean magnetic domain model. The effect of the non-uniformity of the domain structure on the anomalous eddy current loss is investigated. It is shown that the measured eddy current loss can be almost represented by adding the anomalous eddy current loss to the classical one.

The large current generated by a direct start of the super-large-capacity high-voltage induction motor would have a huge impact on the power grid as well as the motor itself. Traditional soft starters have the shortcomings of discontinuous adjustment, voltage sags, sudden torque mutation, secondary current impact and high cost. To resolve this issue, the authors propose a novel coupled autotransformer and magnetic-control (CATMC) soft-start method. The structure of the new CATMC soft starter combines the functions of the autotransformer and magnetic control reactor via an innovative electric and magnetic circuit design. In this study, the authors analyse the magnetic circuit structure and working principles of the CATMC soft starter. Then, to validate its principle and performance, the authors conduct a simulation study using ANSYS software and design and test an 18 MW/10 kV CATMC soft starter prototype. The simulation results demonstrate that the CATMC soft starter effectively avoids secondary current impact and constrains the motor starting current to

A 7-week-old girl with a normal birth history suddenly developed respiratory distress while feeding. Cardiopulmonary resuscitation was initiated at home after she had a cardiac arrest and was continued in the emergency room but all efforts at resuscitation proved unsuccessful and she died 2 h after presentation. Investigations performed in the emergency room revealed that she had a significantly high white blood cell count and severe anaemia. The cause of death was identified as KMT2A-rearranged infantile acute lymphoblastic leukaemia based on cytogenetic tests. She had no abnormalities at the 4-week check-up; however, she developed a skin nodule on her abdomen thereafter, and the family did not consult a doctor for fear of contracting COVID-19. Early detection and diagnosis could have changed the prognosis of the patient. The present case highlights the negative impact of the reduction of outpatient consultations during the COVID-19 pandemic.

To reduce the iron loss of a three-phase reactor composed of grain-oriented (GO) silicon steel plates, we proposed two reactor models. One applies oblique joints between the legs and the yokes, and the other applies butt joints composed of non-oriented (NO) silicon steel plates at the L and T joint parts. The proposed models are aimed to relax the flux concentration inside the iron cores that occurs due to the anisotropic magnetic characteristics of GO silicon steel plates. The effectiveness of the proposed models are investigated through magnetic field and iron loss analyses considering the anisotropic magnetic characteristics of the iron cores. It is found that the flux concentration in the yoke can be relaxed in both proposed models. And iron loss of the proposed model with NO steel plates at the L- and T-shaped joints can be reduced about 12% compared with the ordinary one.

Local high iron loss may occur due to the deviation of magnetic flux from the rolling direction of electrical steel in the T-joint area of the transformer core. In this paper, to reduce the iron core loss in the T-joint region, a hybrid iron core model using nonoriented and grain-oriented magnetic materials is proposed. Three-dimensional magnetic field analysis considering the nonlinearity and laminated structure of the original and proposed iron core models is carried out by using the finite element analysis. The flux and iron loss distributions of the original and the hybrid cores are compared. The results show that approximately 2% iron loss reduction can be achieved by using the proposed hybrid structure.

BackgroundCongenital central hypoventilation syndrome (CCHS) is a rare disease characterized by sleep apnea. Anoxia often occurs soon after birth, and it is important to prevent anoxia-mediated central nervous system complications; however, data on the relationship between respiratory management and the prognosis for intellectual development of patients with CCHS is not well yet investigate.MethodsWe performed a retrospective chart review cohort study of patients with CCHS in Japan. We investigated the risk and prognostic factors for developmental outcomes and examined the disease in terms of its symptoms, diagnosis, complications, and treatment.ResultsOf the 123 patients with CCHS included in the survey, 88 patients were 6 years old and older. They were divided into two group based on their intelligence quotient. Those treated using positive-pressure ventilation via tracheostomy in the first three months of life had a better developmental prognosis than those managed via tracheostomy after three months of age and those treated by ventilation using mask (OR = 3.80; 95% CI: 1.00–14.37, OR = 4.65; 95% CI: 1.11–19.37). There was no significant difference in physical development (P = 0.64).ConclusionsThe best respiratory treatment for patients with CCHS is ventilation via tracheostomy, initiated ideally before the age of three months.

Background: Congenital central hypoventilation syndrome (CCHS) is a rare disease characterized by sleep apnea. Anoxia often occurs soon after birth, and it is important to prevent anoxia-mediated central nervous system complications; however, data on the relationship between respiratory management and the prognosis for intellectual development of patients with CCHS is scarce. Methods: We performed a retrospective chart review cohort study of patients with CCHS in Japan. We investigated the risk and prognostic factors for developmental outcomes and examined the disease in terms of its symptoms, diagnosis, complications, and treatment. Results: Of the 123 patients with CCHS included in the survey, 88 patients were 6 years old and older. They were divided into two group based on their IQ. Those treated using positive-pressure ventilation via tracheostomy in the first three months of life had a better developmental prognosis than those managed via tracheostomy after three months of age and those treated by ventilation using mask (OR = 3.80; 95% CI: 1.00–14.37, OR = 4.65; 95% CI: 1.11–19.37). There was no significant difference in physical development (P = 0.64). Conclusions: The best respiratory treatment for patients with CCHS is ventilation via tracheostomy, initiated ideally before the age of three months.

Ring chromosome 20 syndrome is an epileptic and neurodevelopmental encephalopathy that occurs in children, characterised by a triad of refractory frontal lobe seizures, recurrent non-convulsive status epilepticus and frontal lobe-dominant paroxysmal discharges. However, details of other clinical features associated with ring chromosome 20 syndrome remain unknown. Here, we report two patients with ring chromosome 20 syndrome who had praxis-induced reflex seizures. Case 1 was an 11-year-old girl who presented with seizures triggered by specific activities such as mental and written calculations, writing, decision-making, recall, sudden changes in routine or ambient temperature and bathing. During calculations, left frontal lobe-dominant, 3-Hz slow-wave bursts were observed on EEG. Lacosamide effectively suppressed her tonic seizures. Case 2 was a six-year-old boy who presented with seizures triggered by specific activities such as calculations, recall and bathing. During calculations, frontal lobe-dominant, 3-Hz spike and slow-wave bursts were observed on EEG. Although his epilepsy was refractory, gabapentin reduced the frequency of focal seizures. In both cases, the hyperexcitability in the frontal lobe may have spread to the motor cortex and precipitated praxis-induced seizures. Therefore, in addition to the known characteristic triad, praxis-induced reflex seizures may also be a feature of ring chromosome 20 syndrome.

To investigate the noise reduction of an electrical machine, the deformation and vibration of the cores are evaluated by using the coupled magnetic and mechanical analyses [1]. In these analyses, the local force calculated by using the flux distribution obtained from the magnetic field analysis is required in the mechanical analysis. In the local force calculation [2], the Maxwell stress tensor is usually used. The Maxwell stress tensors are often represented by the Minkowski and Chu models with linear and nonlinear energy expressions, respectively. In the nonlinear magnetic field analysis, the volume forces, which move the magnetic bodies, obtained from both models coincide with each other, whereas their local forces, which deform the magnetic bodies, are different. Therefore, more investigation is required to clarify the suitable expression of the Maxwell stress tensor. In this paper, to clarify the proper expression of the Maxwell stress tensor for the local force calculation of a nonlinear magnetic body, the Maxwell stress tensors are derived from the Fleming’s left hand rule because the volume current density can be used to determine the magnetization in the nonlinear magnetic body. As a result, a new Maxwell stress tensor is derived. The surface force obtained from the new Maxwell stress tensor is compared with those obtained from the ordinary Minkowski and Chu models, and the equivalent magnetizing current method [3] to show the effectiveness and validity of the proposed Maxwell stress tensor.

In this paper, an excess loss modeling method of the laminated iron core is proposed. The 1-D single sheet silicon steel plate analysis is combined with the 3-D solid-core analysis to model the laminated structure. The modeling is improved by including the domain wall bowing due to pinning effect, which is considered as the main cause of excess loss. The domain wall bowing due to pinning is considered in the 1-D steel plate analysis because the excess loss generated by the flux density in the parallel direction of the stack is dominant compared with that in the perpendicular direction. In the 1-D analysis, an initial bowing flux distribution along the thickness direction of one lamination is introduced. The results of iron losses show that the hysteresis and eddy current losses vary with the flux and eddy current distribution in the laminated iron cores. Finally, the 1-D–3-D combined method is applied to a single-phase reactor; the magnetic flux and eddy current distribution are analyzed in detail. The eddy currents generated by the parallel flux are increased, hence, the skin effect of flux in the parallel direction of laminations is enhanced; thus, the hysteresis and eddy current losses are increased and the iron loss is increased by 8%.

A novel direct current system fault current limiter (DCSFCL) based on the principle of nonlinear magnetization was proposed to limit fast rising fault current of the dc system. Different materials were also tested to find the iron core material. However, the existing material is not able to obtain both two necessary indexes, namely, a large saturation point and fast demagnetization speed. Hence, the performance is not satisfactory using a single material. In order to obtain the best performance for the DCSFCL, mixed materials were applied to combine the advantages of different soft magnetic materials. Furthermore, magnetic valves were also added to the original DCSFCL topology, which is an effective method to optimize the clipping performance and reduce the usage of materials. The 2-D models were built and finite-element analyses were carried out to verify these assumptions. Compared with a traditional smoothing reactor, the proposed new model not only limits the fault current by 55.4%, but also reduces the usage of both magnetic material and permanent magnets by over 20%.

Soft magnetic composite (SMC) is composed of ferromagnetic particles surrounded by electrical insulation. SMC has advantages such as isotropic magnetic characteristics, low eddy current loss, and easy to be manufactured into complex shapes compared with electrical steel sheets. In this paper, to establish the homogenization technique for the magnetic field analysis of an electrical machine using SMC, a method to evaluate the effective permeability and iron loss taking account of nonlinear magnetic characteristics and eddy currents is proposed by using a cell model composed of one particle of SMC. Then, the effects of the frequency and particle size on the effective permeability and iron loss are investigated numerically. Finally, the effective permeability and iron losses of an actual SMC are calculated, and they are compared with measured results to verify the proposed method. It is shown that theoretically proper results are obtained by using the proposed method. The calculated iron losses coincide well with the measured ones below 10 kHz, whereas the calculated effective permeability is smaller than the measured one due to different effective gap lengths.

Short-chain enoyl-CoA hydratase (ECHS1) is involved in amino acid and fatty acid catabolism in mitochondria and its deficiency causes Leigh syndrome or exercise-induced dystonia. More than 60 patients with this condition have been reported till date. The accumulation of intermediate metabolites of valine is assumed to be responsible for the cytotoxicity. Since protein restriction, including valine reportedly improves neurological symptoms, it is essential to consider the possible incidence of and diagnose ECHS1 syndrome in the earlier stages. This study reported the liquid chromatography with tandem mass spectrometry (LC-MS/MS) urine and plasma metabolite analysis in six cases, including four new cases with ECHS1 deficiency. The values of urine cysteine/cysteamine conjugates from valine metabolites, S-(2-carboxypropyl) cysteine/cysteamine from methacrylyl-CoA, and S-(2-carboxyethyl) cysteine/cysteamine from acryloyl-CoA were separated between six patients and six normal controls. The LC-MS/MS analysis revealed that these metabolites can be used for the early diagnosis and evaluation of diet therapy.

It is necessary for companies supplying reclaimed oil to analyze polychlorinated biphenyls (PCBs), because there is a possibility of the presence of contaminants due to trace-level PCBs in the reclaimed oil. However, common analysis methods of PCBs are time-consuming and complicated. Fast-GC triple stage quadrupole mass spectrometer with the 13-component quantitation method is an official method for analyzing PCBs in insulating oil in Japan. This method is extremely fast and simplified. The purpose of this study involves an investigation of the aforementioned fast and simple method for potential use in the analysis of reclaimed oil. Furthermore, it was attempted to combine the method with sample preparation involving only hexane dilution. The effect of sample dilutions corresponding to 100, 300, and 500 times was evaluated for reducing the matrix effect. The matrix effect was suppressed at a dilution ratio equal to or exceeding 300 times. Calibration curves of four points, namely 0.01, 0.05, 0.1, and 0.5 ng/mL, (ignored origin) by using an internal standard method were prepared for the 13 components. The square of regression coefficient (R2) values of all calibration curves exceeded 0.997. This method was adopted for the analysis of reclaimed oil containing 0.5 μg/mL PCBs, which corresponds to the judgment criteria, and accurate quantitation (accuracy value, 94.0–102%) and good repeatability (%RSD, 3.6%) were obtained. Furthermore, the required sensitivity was maintained even when 800 samples were analyzed without a cleaning ion source and an exchanging analysis column.

The saturated-core fault current limiter (SFCL) is an effective device for limiting fault current. This paper proposes and analyzes a novel bridge-type SFCL (BSFCL) that uses a permanent magnet (PM) to reduce dc bias while improving the stability of the PM. The bridge structure in the BSFCL consists of four coils and a fault-limiting reactor which is used to limit fault current. The ac and the dc share coils to help reduce energy loss. The iron core uses air-gap branches to offer paths for ac flux, which reduces eddy current in the PMs and enhances their stability. The operating principle and characteristics of the BSFCL were analyzed using the electromagnetic coupling method. To investigate the effects of parameters on the performance of the BSFCL, various finite-element analysis simulations were performed by Maxwell. Experimental results of a 220 V prototype verify the effectiveness of the BSFCL.

The permanent-magnet-biasing saturated core fault current limiter (PMFCL) is one of the most promising devices to limit the fault current. To improve the biasing ability of permanent-magnets (PMs) and reduce the cost of PMFCL, this paper proposes a novel compact permanent-magnet-biased fault current limiter (CPMFCL). The three-limb structure can reduce the size and cost; the optimal small-section structure can improve the biasing ability of PMs and reduce the usage amount of PMs. First, the principle, equivalent magnetic circuit, and small-section optimized structure are introduced. To validate the principle and performance of CPMFCL, various finite element analysis simulation and optimization study are performed in Maxwell-3D. A 220 V/10 A CPMFCL prototype is designed and tested. The simulation and experimental results demonstrate that, compared with traditional PMFCLs, the CPMFCL has the advantages of smaller size, better biasing capacity of PMs, lower possibility of demagnetization, and excellent fault clipping performance.

The application of fault current limiter is an effective method to limit fault current. The saturated-core fault current limiter (SFCL) is one of the promising devices. However, its commercialization is limited by the high demands for the ferromagnetic material and the dc source generating magneto motive force. This paper proposes a novel three-phase compact SFCL (CSFCL) in which a common core and a permanent magnet are used to solve the mentioned challenges. The common core can significantly reduce the amount of required ferromagnetic material. The basic operating principle of CSFCL is introduced based on the analysis of the CSFCL’s magnetic circuit and equivalent electrical circuit. Finite-element analysis (FEA) simulations were performed by ANSOFT to validate the effectiveness of the CSFCL’s fault clipping performance.

When a magnetically shielded room (MSR) to shield leakage fluxes of electric machines is designed by using magnetic field analysis, it is difficult to represent the leakage magnetic field of an electric machine accurately. In this paper, a method of modeling it using a simple solid model with multiple magnetization vectors is proposed. In this method, the magnetization vectors are determined by an inverse technique to represent a real leakage flux distribution. First, the proposed method is explained and verified using a simple 2-D linear magnetostatic one-phase transformer model. Then, the method is applied to a 3-D model and the effect of selected measured surface on representation of leakage flux is investigated. Finally, an experimental verification is carried out. It is shown that the proposed method can represent the leakage magnetic field with small number of magnetizations. The leakage flux only in the region behind the measured surface can be represented, and it is verified by experiment. Moreover, the shielding performance of MSR can be evaluated by using the proposed solid model with suitable permeability.

The saturated core fault current limiter (SFCL) is one of the most effective methods for limiting fault current. A permanent magnet (PM)-biased SFCL (PFCL) can reduce dc bias current and additional energy consumption. However, the thermal stability of NdFeB PMs in PFCL poses a major challenge. This paper proposes a novel hybrid-type SFCL (HSFCL) topology that can reduce this risk. In the HSFCL, a hybrid PM/dc coil is designed to saturate the core, and a fault-limiting reactor is used to guarantee fault-clipping performance. The new structure provides air-gap branches for the time-varying magnetic field produced by alternating current, which reduces the eddy current in the PMs and enhances their stability. Electromagnetic coupling is used to analyze the operating principles and characteristics of HSFCL. Finite-element analysis simulations were performed using Maxwell and compared with verification experiments, proving that HSFCL is efficient in fault clipping and PM reliability enhancement.

Eddy-current loss of NdFeB permanent magnets (PMs) is widely analyzed in PM motors. This paper proposes a coupled 2-D transient finite-element analysis (FEA) of the saturated core fault current limiter (SCFCL) and 3-D analytical model of PMs to evaluate eddy-current loss in SCFCL. The comparison between the result from coupled method and that from 3-D FEA verifies the applicability of the coupled method in analyzing eddy current loss of PMs in SCFCL. The 3-D analytical model of PM is applied to analyze the effect of segmentation on the reduction of PM's eddy-current loss. And the results show that segmentation along width has a better performance, which is also verified by 3-D FEA.