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In order to relieve the problem of bearing wear in high-speed permanent magnet generator, a semi-symmetrical double winding structure with the same number of poles is proposed in this paper. The coupling of the winding magnetic fields enables the rotor to be subjected to a radial electromagnetic force along the direction of overcome gravity, which could effectively extend the service life of the bearings. Firstly, the design principle of the semi-symmetrical double winding structure and the winding MMF are analyzed based on the AC machine winding theory, and the elliptical magnetic field characteristics of the harmonic winding are clarified. Combining the characteristics of order and frequency for harmonic magnetic field, the magnetic fields coupling mechanism of the double winding is revealed, and the analytic model of the power generation and radial electromagnetic force are determined. Secondly, based on rolling contact fatigue theory, the service life improvement of bearing by the double winding structure is certificated. In addition, the magnetic fields of double winding are decoupling calculated by using the finite element method, and the consistency of results between the theoretical analyses and the finite element calculations is determined. Finally, the calculation accuracy of the finite element analysis is demonstrated by experiments on the prototype. [ABSTRACT FROM AUTHOR]

In order to solve the problem of insufficient torque for flux weakening in permanent magnet machines, a novel flux–torque regulation hybrid excitation machine with axial–radial magnetic circuit (FTRHEM) is proposed. To solve the problem that the cogging torque of the proposed machine is caused by multiple factors and the coupling relationship is complicated, an analytical expression for the cogging torque is derived first. Then, the influence of the axial excitation device on the cogging torque is determined. The influence mechanism of the relative position between the axial excitation device and stator on the cogging torque is revealed. A dislocation method is proposed to reduce the cogging torque, and its effectiveness is verified by finite element analysis (FEA). Furthermore, the reduction of the cogging torque in FTRHEM with different pole–slot combinations by this method is comprised and analyzed, which demonstrates the feasibility of the method. Finally, the FEA results are combined with experiments to verify the accuracy of simulations. [ABSTRACT FROM AUTHOR]

The bearingless motor with dual-winding embedded in the stator can not only produce electromagnetic torque and can also produce suspension force to support the rotor suspension, and the design of the dual-winding will directly affect the torque and suspension performance of the motor. It is a complex problem of multi-objective optimization, multi-performance coupling, and multi-parameter collaborative optimization, which is great significance to improve the comprehensive performance of the motor. Firstly, in order to solve the problem of slot space ratio and turns design of dual-winding under the restriction of stator slot space and thermal loading, the calculation formulas of the electromagnetic torque and the suspension force are derived. The influence of dual-winding design on electromagnetic loading, thermal loading, torque and suspension performance are analyzed. The linear variation of electromagnetic torque with the slot space ratio of torque winding is obtained, and the influence of the dual-winding magnetic motive force on suspension force is clarified. Secondly, in order to obtain the dual-winding design scheme with the optimal torque and suspension performance, the performance parameters of the motor are calculated by finite element method and the influence of the slot space ratios of the torque winding on the torque and suspension performance is analyzed. Based on the coupling analysis of the electromagnetic torque and the suspension force in the case of different thermal loading distributions of dual-winding, the dual-winding optimal design of the bearingless motors is given. Finally, the suspension force of a prototype is tested by experiment. [ABSTRACT FROM AUTHOR]

Aiming at the problems of the low output torque and low overload capacity of induction motors caused by the decrease in the main flux at high speeds, the influence of split-winding on motor performance is studied in this paper, and the performance of the motor is optimized by a study of the winding split turns and winding split segments. First, the influences of winding turns and frequency on motor performance parameters are analyzed by an analytical algorithm, and the mechanism of split-winding on motor performance is revealed. Second, the performance of the motor before and after winding splitting is calculated by the finite element method, and the influences of winding splitting on the output torque and overload capacity are clarified. Through the study of the winding split turns and the number of winding split segments, the best speed at the winding split and the optimum number of winding split segments are determined, which provides a basis for the winding split principle when an induction motor is designed with split-winding. Finally, the performance of a prototype before and after a winding split is tested and the accuracy of the finite element calculation is verified. [ABSTRACT FROM AUTHOR]

In order to solve the problem of the decreasing torque density caused by the complex structure of the hybrid excitation machine, a novel flux–torque regulation hybrid excitation machine with axial–radial magnetic circuit is proposed by the authors, which innovatively realises the increase of additional torque and the regulation of the magnetic field by an axial structure. In particular, the additional torque has a certain boost to the output torque under the flux‐weakening condition of the machine. Based on the equivalent magnetic network model, the flux regulation principle of the machine is analysed, and the expressions for the flux linkage and no‐load back electro‐motive force are given to obtain the important factors affecting the flux regulation. Based on the analysis of complex forces generated by the rotating permanent magnet in the coupling magnetic fields, the generation and control principle of the additional torque is expounded. The expression of the additional torque is derived by the Maxwell stress tensor method, which can determine the main influencing factors and these relationships. Finally, the rationality of the proposed hybrid excitation machine structure is verified by experiments. [ABSTRACT FROM AUTHOR]

The introduction of suspension winding generates radial suspension force in bearingless permanent magnet synchronous motors (BPMSMs). However, the addition of suspension winding in the stator slots reduces the slot area of the torque winding. This results in a decrease in the motor torque characteristics, while the thermal load increases. Therefore, to obtain the optimal operating performance of the motor, the variations in torque performance and suspension characteristics are studied with the slot area allocation ratio (SAAR) of the dual winding in this paper. First, the expressions for the electromagnetic torque and radial suspension force with SAAR are derived by the Maxwell tensor method. The effects of the winding parameters on the BPMSM performance are determined and the influences of the current and turn number of the dual winding are considered in the expressions. Subsequently, the effects of thermal load on the torque and suspension force are analyzed by the finite element method (FEM). The optimal motor operating performance with the total thermal load constraint is determined. On this basis, the effects of the dual winding SAAR on the torque and suspension force are studied, the coupling relationship between the torque and the suspension force is obtained, and the optimal matching relationship of the torque and the suspension force at different SAAR values are determined. Finally, the accuracy of the analyses is confirmed by performing static and dynamic experiments on a prototype. [ABSTRACT FROM AUTHOR]

Head smut (HS) is one of the most devastating diseases of maize in spring production regions in China. Quantitative trait loci (QTL) for HS resistance were identified in this study to provide theoretical and applied tools for breeding HS resistance in maize. QTL associated with HS resistance were identified in a F2:3 population derived from a T32 (highly resistant genotype) × HC (highly susceptible genotype) cross. Analysis in each of three environments and a collective analysis across all three environments were used to identify QTL in the F2:3 population. A significant difference in HS resistance was found between the inbred lines, 'T32' and 'HC'. Large genetic variation and transgressive segregation in the F2:3 population were observed between the three different sites, Guian (GA), Huaxi (HX), and Pingba (PB). Two stable and novel QTL for resistance to HS were detected in the different environments that were located within the bnlg1014 to umc2224 (qHS1) interval on chromosome 1 and in the umc1006 to umc1857 (qHS6) interval on chromosome 6. Both QTL can be used for further fine mapping, marker-assisted selection breeding, and theoretical studies on HS resistance in maize. [ABSTRACT FROM AUTHOR]

High‐speed permanent magnet synchronous machine is often used as a starter generator for a single‐shaft micro‐gas turbine due to its high efficiency and high‐power density. However, when the machine works in the starting mode, it usually needs a complex control system to start since the machine cannot realise self‐starting. Therefore, here, a dual‐purpose rotor sleeve is proposed for the machine to have the starting ability. Furthermore, the dynamic response speed of the machine also can be improved by optimising the electromagnetic characteristics of the sleeve. Taking a 40 kW, 20,000 r/min surface‐mounted permanent magnet machine as an example, the two‐dimensional finite element model of the machine is established. The start‐up time and locked rotor parameters under different sleeve conductivities are studied by the finite element method. In order to find out the reason for the change of starting performance, the rotor eddy current distribution is studied. Furthermore, the starting torque of the machine is decoupling analyzed, and the influence of sleeve conductivity on various kinds of torques are found to reveal the influence mechanism of sleeve conductivity on starting performance. Finally, the correctness of the model is verified by experiments. [ABSTRACT FROM AUTHOR]

Axial–radial flux type permanent magnet synchronous machine can adjust air gap flux, which provides a new strategy for flux regulation of a permanent magnet motor. In this article, the structure of the ferromagnetic bridge is optimized by analyzing the magnetic circuit structure of Numerical anlysis of an axial-radial flux type fully superconducting synchronous motor (ARFTFSSM). The three-dimensional finite-element model of the motor is established by using the finite-element method, and the changes of air gap flux density and back electromotive force are compared through the finite-element prediction. The results show that the optimized ferromagnetic bridge has better magnetic regulation performance. On this basis, the eddy current distribution and eddy current loss of two kinds of ferromagnetic bridge structures are further compared and analyzed. Finally, the experimental results verify the accuracy of the calculation, and the research results can provide a reference for the further study of hybrid excitation motor. [ABSTRACT FROM AUTHOR]

Due to the high‐frequency output of the high‐speed permanent magnet generator (HSPMG), a rectifier is needed in the application process. However, the different characteristic harmonics generate by the rectifier will seriously affect the electromagnetic and temperature fields of the generator. Taking a 117 kW, 60 000 rpm HSPMG as example, the influence of different harmonic current content and frequency on the generator loss and temperature field are studied. The influences of different harmonic current content and frequency on the rotor eddy current loss and its distribution variation are analyzed. Furthermore, based on the rotor eddy current loss analysis, a 3D temperature and fluid coupling model is established. The temperature distribution of HSPMG under different harmonic content and frequency are studied by using hydrodynamics and heat transfer theory, especially for the permanent magnet (PM) temperature field. The influence laws of different harmonic content and frequency on the loss are obtained, and the sensitive factor of PM temperature rise is found. The study provides optimization suggestions for reducing eddy current loss and preventing PM thermal demagnetization caused by harmonics. [ABSTRACT FROM AUTHOR]

Summary: Because of uneven air‐gap magnetic field caused by open slots in stator cores, motor performance is influenced by harmonic magnetic field in air‐gap. In this paper, a 10‐kV, 1000‐kW line‐start high‐voltage permanent magnet synchronous motor (LS‐HV‐PMSM) is taken as an example to establish finite element models when the magnetic slot wedge relative permeability is different. The influence of using the magnetic slot wedge on a motor's torque ripple, loss, and starting performance is studied. On the basis of the analysis of the torque ripple coefficient, the influence of the magnetic slot wedge relative permeability on torque ripple is obtained. Using the finite element method, the influence of the magnetic slot wedge relative permeability on a motor's loss is studied. It is found that the rotor cage bar eddy‐current loss is changed obviously. The relationship between the rotor cage bar eddy‐current loss and rotor cage bar current density is determined. Furthermore, the influence mechanism of rotor cage bar current density on rotor cage bar eddy‐current loss is revealed. According to the speed change curve, the starting performance of the LS‐HV‐PMSM is analyzed, and the influence of slot leakage reactance on a motor's starting performance is obtained. On the basis of the above analysis, some references are obtained for choosing the magnetic slot wedge with suitable relative permeability when the LS‐HV‐PMSM is designed. [ABSTRACT FROM AUTHOR]

The application of surface permanent magnet synchronous motor (SPMSM) driven by inverter is becoming more and more extensive. However, the voltage harmonics generated by the inverter will have a severe impact on the motor torque ripple. In order to analyze its impact, a 1500 r/min 3 kW SPMSM is taken as an example. Firstly, the two-dimensional finite element model is established, and the accuracy of the model is verified by the experiment. Secondly, the torque ripple is calculated and analyzed. The influences of voltage harmonic amplitude and voltage harmonic initial phase angle on torque ripple are mainly studied, and the variation law is obtained. At the same time, in order to distinguish the influence of higher harmonics on torque ripple, the voltage harmonics is decoupled to get the variation law of torque ripple. Finally, based on the analysis of the current ripple and air gap magnetic density, the influence mechanism of voltage harmonics on torque ripple is revealed. The conclusion is helpful to optimize motor design and improve motor performance. [ABSTRACT FROM AUTHOR]

The line start permanent magnet synchronous motor (LSPMSM) can be used for direct‐on‐line (DOL) starting, so it is easily affected by voltage unbalance. Based on the finite element method (FEM) and analytical method, the influence of voltage unbalance on the steady‐state performance of LSPMSM is studied in this paper. A two‐dimensional finite element model is built, and the armature current, losses and torque ripple as a function of the phase voltage unbalance rate (PVUR) are obtained. The influence mechanism of voltage unbalance on the steady‐state performance of a motor is demonstrated. Finally, a prototype of LSPMSM is manufactured and tested. By comparing the experimental data with the simulation data, the accuracy of the calculation model is verified, and the correctness of the research is proved. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Remanence and coercivity are important parameters to characterize the magnetic properties of permanent magnetic (PM) materials. The variation of PM parameters will lead to the variation of generator output performance. To find out the key PM parameter affecting generator output performance, a 117‐kW, 60 000‐rpm high‐speed permanent‐magnet generator is taken as an example and a 2D finite element model is established. By comparing the calculation results and the test data, the accuracy of the model is verified. By using the field‐circuit coupling method, the mechanism of nonlinear variation of output voltage with the change of load is revealed when the variation degree of remanence and coercivity is consistent. The sensitivities of no‐load electromotive force (EMF), output voltage at rated power, voltage regulation, and overload capability to the variations of PM parameters are studied. Furthermore, the mechanism of PM parameters affecting generator output performance is revealed. The results show that the sensitivity of generator output performance to different PM parameters is different and the influence degree of PM parameters on the generator output performance depends on the permeance of the main magnetic circuit. Finally, the basis for selecting PM parameters is given. The research can assist generator designers to select PM in the design stage. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The permanent magnet thickness (PMT) is an important parameter in the design of the permanent magnet machine, and it directly affects the air-gap magnetic field and performance of generator. In this paper, a 117-kW, 60,000-rpm, high-speed permanent magnet generator (HSPMG) is taken as an example, and a two-dimensional finite element model (FEM) is established. By comparing calculation result and test data, the accuracy of the model is verified. The air-gap flux density waveform is obtained by the FEM, and the waveform is decomposed by the Fourier transform principle. The nonlinear variation law of harmonic content with the increase in PMT is obtained, and the nonlinear variation mechanism of air-gap flux density is revealed. On this basis, the variation law of voltage and voltage regulation with the increase in PMT is given, and the PMT is optimized. In addition, the nonlinear variation law of the loss is determined. The research shows that the purpose of optimizing performance of HSPMG can be achieved by adjusting the PMT. The PMT is finally determined when the generator performance is optimal. The conclusions provide some reference for the research of HSPMG. [ABSTRACT FROM AUTHOR]

The uncontrolled rectifier and controlled rectifier which use fixed switching frequency control strategy are applied usually during the working of a high-power high-speed permanent magnet generator (HSPMG). Even for the controlled rectifier, it will generate harmonics. The electromagnetic performance of the HSPMG is also affected by these harmonics. In this paper, the influences of the fixed switching frequency control strategy on a HSPMG were studied. Based on the Fourier theory, the harmonic currents of the generator were analyzed, and the change of harmonic distribution range and current total harmonic distortion (THD) were obtained. By using an indirect field-circuit coupling method, the influences of the fixed switching frequency control strategy on the losses and torque of the generator were analyzed. The relations between the switching frequency and the losses and torque of the generator were obtained, and the change mechanism of the loss was revealed. The obtained conclusions can provide reference for the optimized choice of the switching frequency of the distributed generation system with the HSPMG. It can also provide support for the HSPMG electromagnetic structural optimization and the optimization of the loss and harmonic on the system level. [ABSTRACT FROM AUTHOR]

In order to obtain the influence of wye (Y)-and delta (Δ \Delta)-connected winding on line start permanent magnet synchronous motor (LSPMSM), taking a 15 kW LSPMSM as an example, the two dimensional (2-D) finite element method (FEM) and analytical method are used to calculate the motor performance. The influence of 3rd harmonic current in Δ \Delta -connected winding on the motor electromagnetic field is analyzed. The difference of the losses and capacity of starting and overload between the Y- and Δ \Delta -connected winding are studied. Finally, combined with the related experiments, the correctness of the calculation model is verified and the reliability of the research results are proved. [ABSTRACT FROM AUTHOR]

In order to reduce the saturation degree of magnetic flux density at the pole shoe on the right side of the pole in a generator and reduce the pole‐to‐pole leakage, an asymmetric pole shoe structure is proposed in this paper. The influence of the asymmetric pole shoe structure on the generator performance is analyzed. First, a bulb tubular turbine generator with a single unit capacity of 24 MW is taken as an example. The two‐dimensional electromagnetic field model of the generator is established based on finite element analysis software, and the correctness of the model is verified through comparative analyses of the experimental results and simulation data. Second, the magnetic flux density distributions of poles under different pole shoe structure parameters are analyzed, and their distribution characteristics are also discussed. Finally, by studying the generator air gap flux density, average torque, torque ripple, eddy current loss, and core loss when the pole shoe structure is different, the variations of the above parameters along with the increase of the pole shoe depth are obtained. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The axial-radial flux-type synchronous motor with hybrid poles (HPARFTSM) is a new kind of hybrid excitation motor. Besides the advantage of high efficiency, this machine has the flux-regulation capability. Therefore, this machine has wide application prospects in many fields, such as electric vehicles, aerospace, etc. The flux-regulation capability is an important indicator to measure the HPARFTSM. Some factors, such as the parameters of permanent magnets, the width of axial air gap, and the materials of ferromagnetic rings, may affect the flux-regulation capability. It is necessary to study the impacts that these factors have on flux-regulation capability. Taking a 3.5-kW HPARFTSM as an example, the three-dimensional electromagnetic field model was established. The air-gap flux density was numerically solved by finite element method. The calculated results agreed well with the experimental results, which validates the reliability of the computing method. On the basis of aforementioned analyses, the influences of different sensitivity factors on flux-regulation capability were obtained. The conclusions establish the foundation for the optimal design of this kind of machine. [ABSTRACT FROM AUTHOR]

This paper addresses the effect of rotor structure on the magnetic adjusting performance of an axial-radial permanent magnetic machine via the comparative performance investigation on the axial-radial flux type permanent magnet machines with three different structures. By using the three-dimensional time stepping finite-element method, the distributions of the air-gap flux density are obtained when the machine operates with different axial magnetomotive force, and the key factor that affects the magnetic adjusting ability is determined. The variation of the magnetic field is investigated, and the back electromotive forces of the three machines with different structures are also studied. Meanwhile, the eddy current distribution and the eddy current loss in machines with different structures during load operation are analyzed. The theoretical claims are verified by both numerical simulations and experimental tests. [ABSTRACT FROM PUBLISHER]

When the inter turn short circuit (ITSC) fault occurs, the value of the short circuit ring loop current is large. A pulsating magnetic field generated by the loop current has a great influence on the motor inside magnetic field. The motor internal magnetic field is obviously distorted, and the motor output performance is limited. In order to study the influence of the fault on the permanent magnet synchronous motor (PMSM) output performance, first, a PMSM fault model is established based on the FEM. The influence of the fault on the motor electromagnetic field is studied. The motor magnetic field is decoupled and the armature magnetic field harmonic content is obtained by using the Fourier decomposition theory. Second, by using the Maxwell energy method, the output torque, radial force density and electromagnetic force are analyzed. The influence mechanism of the ITSC fault on the torque ripple and the electromagnetic force is revealed. Finally, the prototype test platform is built to study the ITSC fault, and the simulation results are compared with the experimental data. The correctness of simulation research is verified. The conclusions obtained are of the great significance for the PMSM fault analysis. [ABSTRACT FROM AUTHOR]

An alloy sleeve is often used to prevent the damage to rotor magnets caused by the large rotational centrifugal forces within a high speed permanent magnet generator (HSPMG). It should be thick enough to satisfy the mechanical strength needed. The generator main reluctance mainly focuses on the rotor sleeve, so sleeve permeability has much influence on the magnetic circuit and generator performance. Since a finite element simulation for every machine is time consuming and complicated, a simple analytical model of general surface-mounted permanent magnet machines has been established within this paper. Additionally, an analytical method is also given in full, so that optimal sleeve permeability can be obtained for a set of parameters for a given machine. In order to accurately establish the variation of the pole-to-pole leakage flux in the air gap and rotor sleeve of the generator with different permeability sleeves, an iterative method is proposed. The leakage flux, main flux, magnet performance and their relationships with the generator have been studied further, and the influence mechanism of sleeve permeability on the generator performance has been determined. Based on the research of the above influence factors, the optimal sleeve permeability is obtained by using the analytical method. Comparing the results of the analytical method and finite element method, they are in close agreement; hence the rotor sleeve with optimal permeability can improve the generator performance. [ABSTRACT FROM AUTHOR]

In this paper, a superhigh-speed permanent-magnet generator (SHSPMG) which has an alloy sleeve on the rotor outer surface is investigated. The purpose of the sleeve is to fix the permanent magnets and protect them from being destroyed by the large centrifugal force. However, the sleeve material characteristics have much influence on the superhigh-speed machine, and therewith, most of rotor eddy-current losses are generated in the alloy rotor sleeve, which could increase the device temperature. Taking a 117-kW 60 000-r/min SHSPMG as an example, the influence of the sleeve on the generator output performance is analyzed when the generator sleeve is made of stainless steel, carbon fiber, copper–iron alloy, and copper. In addition, the eddy-current loss distributions could be gotten, and therewith, the variations of the eddy-current losses in different kinds of sleeves are analyzed. Based on the 3-D coupling field between the fluid and temperature, the temperature distributions were obtained when the sleeve adopts different materials. Moreover, the temperature variations of the permanent magnets are further analyzed. The obtained conclusions may provide some references for the design and analyses of the SHSPMG. [ABSTRACT FROM AUTHOR]

Alloy rotor sleeves are used extensively in high-speed permanent-magnet machines since they could fasten the permanent magnets availably. However, it is inevitable that eddy-current losses will be generated in the sleeve, which may make the permanent magnets overheated. In order to reduce the rotor eddy-current losses, this paper focuses on the influence of the rotor-sleeve electromagnetic characteristics. Taking a high-speed permanent-magnet generator (HSPMG) as an example, the variations of output performance and rotor eddy-current losses were analyzed when the generator adopts the steel sleeve and the copper–iron alloy sleeve, respectively, and therewith, the principles of the variations were exposed. Then, the rotor eddy-current losses were further analyzed when the generator sleeve conductivity was changed. The worst range of the sleeve conductivity was also given, in which the rotor eddy-current losses were the largest. Additionally, the increase of the sleeve permeability could reduce the main magnetic circuit reluctance and improve the operating point of permanent magnets. On the other hand, it can increase the pole-to-pole flux leakage dramatically. So, the generator performance should be analyzed by considering the two factors when the rotor-sleeve permeability was different. [ABSTRACT FROM AUTHOR]

To provide theoretical and applied references for acid phosphatase (APase) activity of maize, this study was to identify quantitative trait locus (QTL) for APase activity in root and rhizosphere soil of maize under low phosphorus (p) stress. The correlation and the QTL of APase activity in root (APR) and APase activity in rhizosphere soil (APS) were studied for the F population derived from the cross 082×Ye107 under low P stress in two sites. Analysis for each environment and joint analysis across two environments were used to identify QTL for the F population. A significant difference in APR and APS was found between 082 (P efficient genotype) and Ye107 (P deficient genotype). A large genetic variation and transgressive segregation of the F population were observed in Beibei and Hechuan. One stable QTL for APR was detected in different environments, which was located in the interval bnlg1350 to bnlg1449 on chromosome 3. Two stable QTLs for APS were detected, which were located in the interval umc2083 to umc1972 on chromosome 1 and in the interval umc2111 to dupssr10 on chromosome 5. The stable QTLs can be used in MAS breeding and theoretical study of maize. [ABSTRACT FROM AUTHOR]

Acid phosphatase (APase) is very important in phosphorus (P) scavenging and remobilization in plants. The aim of this study was the fine mapping of quantitative trait loci (QTL) for APase activity (APA) in maize ( Zea mays L.) leaf. The QTL for APA were studied in the F2:3 population derived from the cross 082 × Ye107 under low P stress in two sites. A significant difference in APA was found between 082 (P-efficient genotype) and Ye107 (P-deficient genotype). Each environment was analyzed to identify the QTL. Six QTL for APA were found, comprising two QTL at Beibei (BB) and four QTL at Hechuan (HC), China. A QTL denoted as AP9 showed a stable expression under different environments on chromosome 9, and explained 10.21 and 16.81 % of phenotypic variation at BB and HC, respectively. For the fine mapping of this QTL, seven individuals selected via marker-assisted selection in the BC3F1 population were used to produce the BC3F2 lines by selfing and to allow recombination within the region containing the target QTL. High-resolution genetic and physical maps were further constructed for the fine mapping of AP9 using 12 simple sequence repeat markers and the BC3F2 population consisting of 1,441 individuals. As a result, the location of AP9 was narrowed down to a 546-kb fragment on chromosome 9. [ABSTRACT FROM AUTHOR]

During the operation of a turbine, the water level drop can cause vibration and damage to the flow components, severely threatening its stability and reliability. Investigating the impact of operational parameters on the internal flow field and flow structures of tidal turbines under low flow conditions is crucial for peak shaving and deployment of tidal power stations. This paper takes a 24MW turbine as the research object, using numerical calculations to analyze the effects of tailwater height on the flow characteristics and structural properties of the unit under low flow conditions. It studies the hydraulic impact on the flow component walls under different operating parameters and verifies the reliability of numerical calculations through vibration and stress tests. The results show that the increase in tailwater level affects the turbine’s flow characteristics, forming large-scale, high-intensity vortices in the internal flow field and causing pressure pulsations near the wall surface. Modal analysis reveals that under different tailwater heights, the maximum modal effective mass exists along the axis of the impeller, with modal frequencies higher than the main frequencies of pressure pulsations. The impeller region corresponds to the turbine chamber wall bearing significant stress, which induces strain. The magnitude of stress and the degree of strain are positively correlated with the tailwater height. The research findings provide guidance for tailwater regulation and stable operation of tidal power stations. [ABSTRACT FROM AUTHOR]

The variation of stator winding turns will directly affect the key parameters of a motor, such as winding resistance and winding reactance, which further affect the steady-state performance of the motor. In order to get excellent steady-state performance from line-start permanent magnet synchronous motors (LSPMSMs) under different load powers, taking an 11 kW LSPMSM as an example, the finite element method (FEM), combined with the steady-state phasor diagram and torque angle characteristic, are used in this paper for the optimal design of the stator winding turns of the prototype. The correctness of the model is verified by comparing the experimental data with the calculated data. First, the influences of different stator winding turns on the no-load, back-induced electromotive force (EMF), as well as on inductance and overload ability are studied, and the variation mechanism is obtained. In addition, from the perspective of the torque angle characteristic, the influence of the change in synchronous inductance caused by the number of turns on the steady-state power angle is studied. Second, the variation of the current and power factors with turn number is obtained by studying the steady-state power angle and end voltage. Based on the coupling relationship between the no-load back EMF and the power angle, the mechanism of non-linear variation of current and power factor is revealed. Finally, the variation of the number of turns on the core loss and eddy current loss is analyzed under various operating conditions, and the variation mechanism is revealed, based on the armature reaction theory. [ABSTRACT FROM AUTHOR]

High-speed surface-mounted permanent magnet synchronous machine is often used in micro gas turbine generation system due to its high rotor strength and high efficiency. The electrical machine in this kind of generation system needs to integrate two functions of starter and generator. Therefore, its comprehensive performance, including starting performance and generating performance, has become a comprehensive standard to measure machine performance. In this paper, a 40 kW, 20,000 r/min high-speed machine is taken as an example, the influence of magnets magnetization direction on the machine comprehensive performance is studied. The machine models with different magnets magnetization directions are established by using finite element method and the correctness of the models is verified by comparing the experimental data with the finite element calculation data. On this basis, the influence of different magnetization directions on the performance of the machine, such as generation loss, torque ripple, output voltage, start-up time and maximum starting ability, is analyzed. Furthermore, based on the Fourier decomposition of air gap flux density and the decoupling analysis of starting torque, the influence mechanism of magnetization direction on the performance of the machine is revealed. The presented results provide a reference for the selection of a suitable magnetization direction for high-speed surface-mounted permanent magnet machines. [ABSTRACT FROM AUTHOR]

The motor losses are directly affecting the efficiency of the high voltage induction motor (HVIM). It is an important parameter of the motor design. In order to analyze the influencing factors of the HVIM losses, a 10 kV, 1000 kW HVIM is taken as an example to establish a 2D finite element model. The correctness of the model has been verified by the comparison of experimental data and calculated data. The finite element calculation method is adopted to numerically solve the electromagnetic parameters of the prototype. Based on electromagnetic parameters, the influence of the rotational speed of the HVIM on the core loss is analyzed, and the variation of the rotational speed on the core loss is obtained. Secondly, the influence degree of load rate on the core loss of HVIM is determined. Finally, the variations of different material characteristics on losses are studied. In addition, the effects of different speed and load rate on the copper loss of the HVIM are also studied. The analysis of this paper provides reference and engineering practical value for the optimization design of HVIM. [ABSTRACT FROM AUTHOR]

As the main power source of the industrial production and mining industry, the health of high-voltage induction motor (HVIM) has attracted extensive attention. The loop current (LC) of the inter-turn short-circuit (ITSC) fault seriously endangers the stability of HVIM. A comparative analysis is made of HVIM in this paper when the motor works under fault conditions. The purpose of this study is to analyze the influence of ITSC fault on motor performance when the LC is considered and the LC is not considered. In this paper, a 10 kV, 1000 kW HVIM is taken as an example to establish finite element calculation model. By comparing finite element calculation data and test data, the model correctness is verified. Based on the correctness model, the fault models are established. The three-phase current unbalances, torque ripple and losses are studied when the motor works under the different fault conditions. By comparing the three-phase current unbalance, torque ripple and loss of the motor when the LC is considered and the LC is not considered. The influence mechanism of the ITSC fault on three-phase current unbalance, torque ripple and losses are revealed. Based on the above analysis, some references are given for ITSC fault diagnosis and fault degree identification. [ABSTRACT FROM AUTHOR]

In order to better start and control the surface-mounted permanent magnet synchronous motor (SMPMSM), the inverter is widely used in the SMPMSM. However, a large number of voltage harmonics are generated by the inverter, which can directly affect motor loss and temperature. In order to analyze its influence, taking a 3 kW, 1500 r/min SMPMSM as an example, a 2-D finite-element model is established. The correctness of the model is verified by comparing the experimental data with the calculated results. First, the coupling method of the electromagnetic field and temperature field is used to analyze the electromagnetic field and the temperature field of the SMPMSM, and the data of loss and temperature rise are obtained. Based on these calculation results, the influence of voltage harmonic on SMPMSM is analyzed quantitatively. Second, when the voltage harmonics contained different harmonic orders and amplitudes, the core loss, eddy current loss, and temperature rise are studied. The variations of losses and temperature rise are obtained. Finally, the change mechanism of eddy current loss is revealed by studying the eddy current density. The conclusions of this paper can provide reliable theoretical guidance for improving the motor performance. [ABSTRACT FROM AUTHOR]

Aiming at the low accuracy of discrete fourier transform (DFT) frequency estimation, a new fast detection method was proposed based on DFT output zero-crossing. The DFT output characteristics of the signal were analyzed firstly. The zero-crossing time of the DFT real part (or imaginary) was calculated accurately by using the fourth order Newton interpolation method. The system frequency could be obtained by the time difference between two zero-crossing points. The results of simulation analysis and experimental verification showed that the method had higher frequency estimation accuracy and less harmonic disturbance, and only needed 1.78 cycles to achieve frequency estimation, which was suitable for power system with real time requirement. [ABSTRACT FROM AUTHOR]

The cooling performance of the machine with the closed liquid cooling system is excellent. However, the electromagnetic characteristics of the oil separator which sealing the cooling oil in the stator side can have a significant impact on the performance of the machine. In this paper, a liquid cooling structure with the magnetic oil separator is proposed. Taking the 20 000 rpm high‐speed permanent magnet generator as an example, the influence of the electromagnetic parameters of the magnetic oil separator on the generator output performance is studied by the analytical calculation and the finite element method, and the mechanism of the nonlinear variation of the generator output performance with the permeability of the oil separator is obtained. The influence of the oil separator on the air‐gap magnetic field and electromagnetic force is analyzed, and the reduction mechanism of the different permeability of the oil separator on the harmonic magnetic field and radial force is revealed. The vibration acceleration response of the generator stator is obtained through the modal and harmonic response analysis, it is confirmed that the magnetic oil separator has the effect of reducing vibration. In addition, the 3‐D temperature field calculation model of the generator is established, the influence of the thermal parameters of the oil separator on the internal heat exchange of the generator is studied, and the temperature distribution is obtained. Finally, experiments on the electromagnetic performance and temperature rise of the prototype are carried out to verify the correctness of the theoretical analysis. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

We constructed an F2:3 population of 180 individuals from a cross between the maize genotypes 082 (high phosphorus use efficiency) and Ye107 (low phosphorus use efficiency). We used the population to perform quantitative trait loci (QTL) mapping for eight ear traits (ear diameter [ED], ear length [EL], ear weight [EW], ear kernel weight [EKW], row number per ear [ERN], bald tip length [BTL], kernel number per row [RKN] and number of seeds per plant [NSP]) in three low‐phosphorus environments. A total of 36 QTL for ear traits were detected in at least one of three single environments and were located on all maize chromosomes except for chromosome 10; the explained phenotypic variation ranged from 5.91% to 12.80%. The QTL JAqEKW5‐1, JAqEL3‐1, JAqEW1‐1, JAqBTL1‐1 and JAqNSP5‐2 were identified and stably expressed in single‐environment and joint‐environment analyses. Some novel QTL that have not been reported previously were also detected. Most of the identified QTL had stable effects in all low‐phosphorus environments, suggesting that they may be useful for molecular breeding to develop low‐phosphorus tolerant maize varieties. [ABSTRACT FROM AUTHOR]

Due to its simple and robust structure with no windings or PMs on the rotor, the doubly salient motor has been studied in recent years for potential use. However, relatively low torque density and high torque ripples are the main obstacles to its development. To simultaneously improve the torque characteristics and enhance the flux regulation capability, a novel 18/11-pole hybrid excitation doubly salient motor (HEDSM) with a new winding structure is proposed in this paper, with the structure and working principle described. The influence of parameters is analyzed, based on which the motor is optimized. After that, the working performance, including the flux linkage, the back-EMF, the torque characteristic, the flux regulation capability, and motor losses, are investigated in detail by finite element analysis. By comparing the novel HEDSM with the traditional doubly salient electromagnetic motor (DSEM), excellent torque performance and flux regulation capability are revealed. [ABSTRACT FROM AUTHOR]

Three-phase current unbalance is a common winding fault of the motor, which will bring local overheating, cause security risks and economic losses, accurate temperature rise calculation and thermal flux characteristics analysis of the motor working in three-phase current unbalance are necessary and challenging. However, little research has been conducted on the thermal characteristics and analysis methods for the permanent magnet synchronous linear motor (PMSLM) working in three-phase current unbalance. To address this problem, a multilayer composite flat wall model contained heat source of the primary is proposed firstly to analysis the heat transfer characteristics of the PMSLM caused by three-phase current unbalance qualitatively. Then, the heat transfer and temperature distribution characteristics of the PMSLM are obtained by calculating the fluid-thermal coupling model of the PMSLM directly. What's more, the effect of current grade on heat transfer is analyzed by comparing the heat transfer characteristics of the PMSLM working in four different three-phase current balance cases. Finally, the qualitative analysis and fluid-thermal analysis results are verified experimentally with a PMSLM adopting four different three-phase current unbalance conditions. Thermal analysis of the PMSLM working in three-phase current unbalance makes it is possible to prevent local heat accumulation and avoid unexpected interruptions for the redundant motor system and the fault tolerant motor system. • A multilayer composite flat wall model contained heat source of the primary is proposed in this paper. Based on this, the heat flux and average temperature of the primary that with three-phase unbalanced current can be analyzed. The temperature distribution characteristics and thermal flux transfer of a PMSLM working in three-phase current unbalanced fault is calculated by establishing the simplified fluid model and coupling fluid-thermal field model, which is useful for analyzing the thermal characteristics of the PMSLM detailedly. Besides, the thermal characteristics of the PMSLM working in 4 different three-phase current balance cases are compared. This work can be used to analysis the thermal characteristics of the PMSLM changing with the excited unbalanced current density. [ABSTRACT FROM AUTHOR]

Force ripple and cost reduction are two of the main challenges in optimising the design and increasing the market uptake of permanent magnet synchronous linear motors (PMSLM). Two mover configurations are compared in depth; one made entirely from rare‐earth materials while another consisting of a hybrid (rare‐earth/ferrite) magnet layout. First, the rare‐earth PMSLM is optimised and designed. Based on the same design and simulation methods, a hybrid PM materials with structure PMSLM is then proposed, optimised and designed using NdFeB at the centre pole‐section and ferrite at the edges. The two configurations of the PMSLM and their relative merits/demerits are compared using the simulation results of the flux density distribution in the air gap, back electromotive force (EMF), and cogging force. The hybrid‐magnet structure PMLSM has a better magnetic performance, and the force ripple is reduced by around 1%. Furthermore, the magnet material cost of the hybrid‐magnet PMLSM is reduced by nearly 25% compared with the original PMLSM. Finally, a prototype of the rare‐earth and hybrid‐magnet PMSLM is manufactured and tested to validate the modelling techniques and the results. [ABSTRACT FROM AUTHOR]

Summary: The structure of the rotor magnetic circuit has an obvious effect on the eddy current loss of the rotor of the high voltage line start permanent magnet synchronous motor. In this paper, a 10 kV to 1000 kW high voltage line start permanent magnet synchronous motor is taken as an example. The two‐dimensional electromagnetic field model of the motor with V‐shaped permanent magnet arrangement is established by using the finite element method. The no‐load back EMF and armature current of the motor are calculated, and the correctness of the model is verified. On this basis, this paper proposes a sector permanent magnet structure, compares the difference between the air gap flux density and the rotor eddy current loss of the two magnetic circuit structures, analyzes the advantages and disadvantages of the above magnetic circuit structure on the harmonic effect of the air gap flux density of the motor. The mechanism of the influence of different magnetic circuit structures on the eddy current loss of the rotor is revealed, which provides a reference for the design of a high voltage line start permanent magnet motor. [ABSTRACT FROM AUTHOR]

A new approach has been proposed to evaluate the influence of the transverse edge effect of high-temperature superconducting (HTS) linear induction motor (LIM) in this paper. Taking a 3.5 kW single-sided HTS LIM for an example, the cross-flux density distributions were analyzed by analytical method. Based on results mentioned above, a new transverse coefficient was proposed to evaluate the influence of the transverse edge effect on the cross-flux density distribution. The influences of the motor configurations and parameters on the transverse coefficient were also investigated. The 3-D finite-element method was adopted to verify the accuracy of the presented analytical method. [ABSTRACT FROM PUBLISHER]

Capacitive deionization (CDI), known as an emerging, environment-friendly, energy-efficient and cost-effective technology, has gained tremendous attention and shown great application potential in brackish water desalination. However, the limited electrical double layer (EDL) capacitance and desalination capacity of conventional carbon-based electrodes seriously affect its practical application. Here, we prepared a flexible, self-supporting, zinc oxide-modified N-doped porous carbon nanofiber membrane (ZnO@N-PCNM) as capacitive deionized electrode materials. The prepared carbon membrane possesses a large specific surface area (488.6 m2 g−1) due to the interconnected and hierarchical multi-layer pores, which can provide more adsorption sites and good electronic/ion conductivity. In addition, benefiting from the high N-doping (10.9%) and the loading of Zn, the prepared ZnO@N-PCNM electrode shows a specific capacitance of 253.62 F g-1 in 3 M KOH electrolyte at a scanning rate of 5 mV s−1. As electrode materials for CDI, the ZnO@N-PCNM delivers an outstanding electrosorption capacities of 32.87 mg g−1, 23.81 mg g−1 and 20.85 mg g−1 at a low pressure of 1.8 V for heavy metal ions Pb2+, Cu2+, and Cd2+, respectively. These results mean that the prepared ZnO@N-PCNM membrane has great potential for Hybrid capacitive deionization practical applications. [Display omitted] • ZnO modified N-doped porous carbon nanofiber membrane (ZnO@N-PCNM) is synthesized by electrospinning technology. • The hierarchical pore structure can effectively enhance ion diffusion and EDL capacitance. • The ZnO@N-PCNM shows a specific capacity of 253.62 F g-1 and an electrosorption capacities of 32.87 mg g−1 for Pb2+. [ABSTRACT FROM AUTHOR]

Vanadium oxides (VO x) and their related compounds have been received extensive attentions because of their special chemical and physical properties, which make them have a wide range of practical applications. VO x can offer high pseudocapacitance for energy storage due to its high electrochemical activity. Herein, 0D (nanoparticles), 1D (nanowires), 2D (nanosheets) & 3D (nanodonuts) VO x were successfully synthesized with assistance of glucose by a facile one-step hydrothermal method. The relationship between the structure and the electrochemical properties of VO x was investigated in detail. Among all the morphologies, the donut-like VO x displays the best pseudocapacitive performance under our reported conditions, with a specific capacitance as high as 225.8 F g−1 at a scan rate of 2 mV s−1. The synergy effect between multiple vanadium oxidation states (mixed-valence) and the donut-like geometry contributes to electrochemical properties. That is, the mixed-valence offers theoretical specific capacitance and the unique donut-like structure provides a more active surface and supported high-speed ionic and electronic transmission channels. The good electrochemical performance of the 0-3D VO x nanostructures indicates their high potential as electrode materials for supercapacitors. [Display omitted] [ABSTRACT FROM AUTHOR]