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High voltage line-starting permanent magnet synchronous motor (HVLSPMSM) have the advantages of induction motors in terms of ease of operation and maintenance. However, due to the slot structure of the stator and rotor, the electromagnetic force composition is complex, which causes the vibration characteristics of HVLSPMSM to change. In order to analyze the influence of stator–rotor slot combinations on the vibration of HVLSPMSM. In this paper, a 10 kV HVLSPMSM is taken as an example to study. Firstly, the mathematical model of HVLSPMSM is established and the air gap magnetic flux density distribution characteristics are obtained for different stator–rotor slot combinations. The expression of the air gap electromagnetic force density (AEFD) of HVLSPMSM is derived by Maxwell tensor method, and the effect of different stator–rotor slot combinations on AEFD is revealed. Further, based on the theory of stator tooth modulation, the sources of equivalent concentrated forces (ECFs) under for different stator–rotor slot combinations are analyzed and the effect of stator–rotor slot combinations on electromagnetic vibration is determined. Next, the electromagnetic–mechanical coupled model of HVLSPMSM is established, and the electromagnetic and vibration characteristics under different stator–rotor slot combinations are solved, and the effect of stator–rotor slot combinations on motor vibration is obtained. Finally, the electromagnetic experiment is conducted to validate the analysis.

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.

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.

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.

Bearingless permanent magnet synchronous motors can rely on the radial electromagnetic force generated by magnetic field coupling to achieve active suspension. However, the coupling between magnetic fields may lead to the saturation of the magnetic circuit, which affects the stability of motor suspension force and is one of the key problems to be solved for bearingless motors. In order to investigate the effect of magnetic circuit saturation on the suspension performance, firstly, the equation of the radial suspension force is derived by combining the influence of the magnetic circuit saturation on the parameters of the motor. The relationship of the magnetic circuit saturation on the stable and fluctuating components of the radial suspension force is obtained, and the fluctuation mechanism of the suspension force under the saturation state is revealed. Secondly, the radial suspension force in different saturation states of the magnetic circuit is calculated by finite element calculation method. Combining the effect of magnetic flux density on the magnetic permeability, the variation of the magnitude and fluctuating of the suspension force with the magnetic field in different magnetic circuit saturation states is given. Finally, the accuracy of the analytical and finite element calculations is demonstrated experimentally.

The High-speed Solid-rotor Asynchronous Motor Cooled by Natural Gas (HSAMCNG) is suitable for integrated compressors in natural gas pipeline transportation due to its high mechanical strength. However, the natural gas thermal property parameters vary obviously under different pressures, and in order to use the transport medium (natural gas) more rationally to cool the HSAMCNG, it is of great significance to research the effect of variation in different pressure natural gas on the motor heat transfer and to optimize the natural gas flow. Firstly, the temperature distribution characteristics of the 160 kW HSAMCNG at different pressures are comparatively studied and the cooling effect of high-pressure natural gas on the motor is clarified in this paper. Secondly, the influence of high-pressure natural gas thermal property parameters on the temperature distribution of the motor is further analyzed by combining the mechanism of the natural gas thermal property parameters on the convective heat transfer coefficient (h) and Stanton number (St), and the variation characteristics of the motor temperature with the change of the natural gas specific heat are revealed. Finally, the optimal flow of high-pressure natural gas is determined by analyzing the motor temperature variation characteristics with the change of the high-pressure natural gas flow. It provides a theoretical basis for the application of different pressure natural gas to cool driving motors at high speed in natural gas pipeline transportation.

Due to the high starting current and high temperature of the high voltage line-start permanent magnet synchronous motor, it is easy to cause partial demagnetization of the motor, which leads to increase vibration of the motor and seriously affects the operating stability of the motor. Therefore, a 10 kV, 630 kW prototype is used as an example to study the motor vibration problem caused by partial demagnetization fault. Firstly, a new method for analyzing the magnetic field variation under uniform and partial demagnetization faults is proposed. Based on this, The analytical expression for the electromagnetic force wave of HVLSPMSM under partial demagnetization is derived, and the law of electromagnetic force variation of different orders and frequencies under partial demagnetization fault is determined, while the influence of the bilateral slotted structure of the stator and rotor of the HVLSPMSM on the electromagnetic force is also considered in the derivation process. Secondly, the variation characteristics of the magnetic density trajectory are calculated by finite element method under the effects of partial demagnetization fault. It is verified that demagnetization faults cause periodic changes in the magnetic field. The harmonic content of the air-gap magnetic field and the spatial and temporal distribution characteristics of the radial electromagnetic force under uniform and partial demagnetization faults are comparatively analyzed using the finite element method. Finally, through modal analysis and harmonic response analysis, the stator vibration response characteristics caused by partial demagnetization faults are obtained, verifying the accuracy of theoretical derivation and providing a basis for the identification of motor faults.

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.

The suspension performance is an important evaluation index of the bearingless motor, which is the key to avoiding shutdown caused by stator and rotor collisions, as well as the safe and stable operation of the motor. In this paper, an Accurate Decoupling Mathematical Analysis Method for Multi-harmonic Magnetic Field Based on Maxwell Tensor Method. On the basis of the mathematical analysis model of the suspension performance and the analysis of the air gap multi-magnetic field, the weight classification of the influence of coupling magnetic field on radial suspension force is studied. The spatial distribution and temporal variation of the suspension force and its fluctuation are analyzed according to the coupling relationship involving the constant, fluctuating components and the space-time vector in the space-time vector expression of the suspension force, and the relationship between the space–time coupled magnetic field and the suspension performance is obtained. Further combined with numerical analysis, the effect of polar arc eccentricity on suspension performance is analyzed, the optimal eccentricity for suspension performance is found, and the effect of the harmonic magnetic field of permanent magnets on the fluctuation of levitation force is verified. Finally, the prototype is made, the experimental platform was built, and the experimental platform is constructed to test the static and the dynamic performance of the prototype.

Owing to the stator open slot structure of the high-voltage motor, the magnetic field distribution in the motor will be uneven, and the performance of the motor will deteriorate. When the slots are embedded with magnetic material slot wedges, the magnetic field of the motor will be changed. In this article, taking a 10 kV/1000 kW high-voltage induction motor (HVIM) as the prototype, the two-dimensional finite element models are established, the effect of magnetic slot wedge (MSW) on HVIM was analyzed. First, by establishing the air-gap permeance function, the influence of magnetic slot wedge on the air gap magnetic field is analyzed, the influence mechanism of magnetic slot wedge on tooth harmonic magnetic field is revealed. In addition, the effect of magnetic slot wedge on excitation inductance, slot leakage resistance, and winding inductance of HVIM is analyzed in detail, the variation of parameters with different relative permeability of slot wedge is summarized, the changes in the motor starting performance had further discussed. Finally, the influence of the slot wedge permeability on motor losses is studied, the distribution of core loss is obtained by establishing the motor segmenting model, and the various mechanisms of core losses in different regions are revealed. The findings provide the guidelines and theoretical basis for the rational selection of magnetic slot wedges.

With the vigorous development of electronics and the increasingly prominent problem of environmental pollution, it is particularly important to exploit environmentally friendly electronic devices. Transient electronics represent a kind of device that once the specified functions have completed can completely or partially disappear through physical or chemical actions. In this work, we introduce a novel guar gum-cellulose aerogel (GCA) membrane based on natural biomaterials and successfully use it as an electrolyte film to fabricate a degradable zinc-ion battery (DZIB). All components of the prepared DZIBs can be successfully degraded or disintegrate in phosphate-buffered saline (PBS) containing a solution of proteinase K after approximately 40 days. This electrolyte film has a high ionic conductivity of approximately 4.73 × 10−2S cm−1and a good mechanical stress property. When applied to DZIB, the production of zinc dendrites can be restrained, leading to the battery showing excellent electrochemical performance. The battery exhibits a specific capacity of 309.1 mA h g−1at a current density of 308 mA g−1after 100 cycles and a steady cycling ability (100% capacity retention after 200 cycles). More importantly, the electrochemical performance of DZIB is better than that of transient batteries reported in the past, taking a solid step in the field of transient electronics in the initial stage.

When the high-speed permanent magnet starter-generator (PMSG) is operating, the permanent magnets will be affected by high centrifugal forces. It is necessary to add a sleeve to protect the rotor and interference fit with the permanent magnet. However, the performance of the high-speed PMSG will be significantly influenced by the electromagnetic characteristics of the sleeve material. In this paper, a high-speed permanent magnet starter-generator for the micro-gas turbine is used as an example, and the two-dimensional finite element model is established. The correctness of the model is verified by comparing the experimental data with the calculated data. Taking 10,000 r/min as the ignition speed, the differences of motor starting performances when using different sleeve materials are compared. Secondly, decoupling the complex coupling torque in the starting process, the influence of material electromagnetic characteristics on the asynchronous torque and braking torque is determined, and the influence mechanism of material electromagnetic characteristics on the torque characteristics of high-speed PMSG is revealed. In addition, the effects of the sleeve materials on the output performance and loss of the high-speed PMSG are determined, and influence mechanism is revealed. On the basis, a sleeve multiplexing scheme is proposed to improve the starting performance while reducing the eddy current losses in the generating state. The results of the study provide reference and theoretical value for the optimization of high-speed permanent magnet starter-generator.

The high-speed electrical machine as a critical power conversion unit in the micro gas turbine generation system needs to integrate the functions of starter and generator, which makes the control system of the machine more complex. In order to simplify the control system and improve the starting speed of the generation system with the help of the intrinsic starting ability of the machine, a high-speed starter–generator with multilayer composite solid rotor is proposed. The machine with the proposed solid rotor can realize self-start when it works in starting mode. Taking a 40 kW 20,000r/min high-speed permanent magnet machine as an example, the finite element model of the machine is established. The influence of driving voltage on the machine starting performance is analyzed and the start-up time, locked rotor parameters of the machine under different driving voltages are further studied. Furthermore, in order to reveal the influence mechanism of driving voltage on the machine starting performance, the starting torque is decoupled and the influence of driving voltage on the decoupled torques is studied. Finally, the machine prototype is tested, and the correctness of the finite element model is verified by comparing the experimental data with the finite element calculation data.

ABSTRACTThis paper presents a study on the influence of different rectifiers on a super-high-speed permanent magnet generator (SHSPMG), which is used in a micro-gas turbine distributed generation system. Taking a 117 kW, 60,000 r/min SHSPMG as an example, the influence of PWM and uncontrolled rectifiers on the generator performances were studied comparatively. The current harmonics and its total harmonic distortion were analysed firstly, and the variation characteristics of voltage and current harmonics were obtained. Based on the 2-D electromagnetic analysis model, the losses of the generator with different rectifier load were studied, especially for the rotor losses, and the mechanisms of the losses variation were determined. By using the method of the 3-D coupling field between fluid and temperature, the temperature distributions of the SHSPMG connected with the PWM and uncontrolled rectifiers were calculated, respectively, and the influences of the different rectifiers on the generator temperature field were studied. It could be found that the PWM rectifier has the advantages of reducing generator losses and optimizing temperature distribution.

Background: In recent years, many patents have been dedicated to increasing the rated power factor of generators. However, hydro-generators often encounter uncontrollable factors, such as dry season, power network adjustment, and so on, resulting in low power factor operation. In other words, the generator is often in a low power factor operating state. In order to provide data reference for power plant in regulating power factor, it is necessary to analyze the performance of generator in low power factor operation. Objective: The performance of the generator is analyzed when the power factor decreases, and the influence of low power factor operation on the generator is obtained. Methods: Taking a 24MW bulb tubular turbine generator as an example, a 2D transient electromagnetic field model is established. The correctness of the model is verified by comparing the test data and the simulation data. The torque, eddy current loss and air gap flux density of the generator under different power factor are calculated. Results: When the power factor deceases from 0.99 to 0.85, the air gap flux density increases from 0.713 T to 0.749 T, the torque ripple increases from 150.5 kNm to 179.9 kNm, and the rotor eddy current loss increases from 17.48 kW to 18.15 kW. Conclusion: The results show that the torque ripple and eddy current loss will increase with the decrease of power factor when the generator lagging phase operation. The torque ripple and eddy current loss increase by 3.8 % and 1 % respectively with the power factor decrease by 0.02 % with power factor between 0.99 and 0.85.

The stator–rotor slot combination is an important parameter in the design of high-voltage induction motor (HVIM). The different design of the stator–rotor slot combination will have an effect on the performance of the HVIM, such as torque, air-gap flux density, loss and so on. In order to analyze its influence, 10 kV, 1000 kW HVIM is taken as an example and the finite element model is established. The correctness of the model is verified by experiments. Firstly, based on the finite element method, the electromagnetic field of HVIM with different rotor slots is solved, and performance parameters of the HVIM are obtained. Based on these parameters, the air-gap magnetic density, overload capacity, average torque and torque ripple of the HVIM are studied, and the distribution rules under the different number of rotor slots are obtained. In addition, the difference of stator core loss and rotor eddy current loss of different rotor slots is analyzed, and the variation mechanism of loss change is revealed. Finally, the performance parameters of the HVIM with different rotor slots are compared, and the reasonable number of rotor slots is obtained. The conclusion of this paper provides reliable theoretical guidance for improving motor performance.

With the development of electric electron technology and controlling technology, controller for driving permanent magnet synchronous motors is used widely. The using of a controller can expand the motor speed range and improve motor runtime performances. However, the output current of a controller contains lots of time harmonics that will have bad influences on motor torque and losses. In order to analyze the influences of the time harmonics on the motor performances, different time harmonic currents were injected into the motor armature. Taking a 750 W, 250 r/min permanent magnet synchronous motor with hybrid magnet poles (HPPMSM) as an example, the 2-D finite model was established. On this basis, the torque ripple and eddy current losses of permanent magnets with different time harmonics were obtained. The influences of time harmonics on motor torque ripple and eddy current losses were determined, and the impacting mechanism was revealed. The analyses may be helpful for the optimal design of HPPMSM.

As a kind of emergency power supply in military field, the high-speed permanent magnet generator (HSPMG) has attracted wide attention to its healthy condition. The loop current (LC) of the inter-turn short-circuit (ITSC) fault seriously endangers the generator unit operation stability and power supply reliability. In order to study the influence of pulsating magnetic field produced by LC on the electromagnetic field, the two-dimensional finite element model (FEM) of the 117 kW, 60000 rpm HSPMG is established. By comparing calculation result and test data, the accuracy of the model is verified. The field-circuit coupling method is used to reveal the change mechanism of magnetic field symmetry when ITSC fault occurs. By comparing the spatial distribution of the air-gap flux density, the relationship among the spatial distribution of the air-gap flux density, the elliptical rotating magneto-motive force (MMF) and the current phase angle is determined. The variation of the amplitude of the air-gap flux density space harmonic under different fault degree is studied, and the fault characteristics of ITSC fault are obtained, which provides a reference for ITSC fault diagnosis and fault degree identification. In addition, the research also laid a theoretical foundation for the next analysis of the loss and temperature field.

AbstractThe 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.

Background: Damper bar is an important component to ensure the security and stability operation of generator. Some patents have been proposed in recent years to deal with generator vibration. Based on the damages of damper bars appeared in many hydropower units, the influences of damper bar material on generator operating characteristics are analyzed. Objective: This study aims to find the suitable material for damper bars to improve the reliable operation of generator. Methods: In this research, a 24-MW bulb tubular turbine generator is taken as an example. The two dimensional model is established by using finite element software, and through the comparative analysis of test results and simulation data, the correctness of the model is verified. The analysis and handling of the electromagnetic parameters are based on the finite element method. Results: The brass, copper iron alloy and copper, three kinds of materials are selected to study the effects of damper bar material on the air gap magnetic field and the saturation degree of the pole shoe magnetic density. At the same time, the influences of damper bar material on the generator losses, torques and eddy current are discussed. Conclusion: The application of copper iron alloy material can reduce the saturation degree of the pole shoe magnetic density, pole-to-pole leakage, eddy current and torque ripple of the generator.

ABSTRACTAiming at the problem of the permanent magnet synchronous motor (PMSM) vibration, noise and poor control precision caused by the cogging torque, the influence of different pole shapes on the motor electromagnetic field was studied. Based on the FEM, the effects of two types of the magnetic poles with different eccentricity on the magnetic field and induced electromotive force (EMF) are studied. The relationship between the magnetic poles shapes, the magnetic field and the induced EMF is obtained. Secondly, based on the Fourier decomposition theory, the air gap flux density harmonic content and the induced EMF are studied. The influence mechanism of the magnetic pole shape on the air gap flux density and the induced EMF is revealed. Finally, the cogging torque of the PMSM with different magnetic poles is studied, and the influence of different magnetic pole shape on the cogging torque is obtained. By optimising the shape of the magnetic pole, the maximum fluctuation amplitude of the cogging torque is reduced by 80.4%. The motor cogging torque can be effectively weakened by the PM eccentric design. This work lays a theoretical foundation for the study of cogging torque.

Background: The safe and stable operation of large-capacity hydro-generators is of great significance to the power grid. However, due to the armature reaction and the stator slots of the hydroelectric generator, the torque ripple of the generator is usually large. Long time running under the condition of large torque ripple will cause damage to the generator components and even threaten the safety of the power grid. Objective: To study the factors affecting the torque ripple of the hydro-generator and reduce the torque ripple. Methods: A 24 MW bulb tubular hydro generator is taken as an example, a two-dimensional transient electromagnetic field model was established, and the correctness of the model was verified by experiments. The causes of armature reaction and cogging effect on motor torque are analyzed. The effects of these two factors on torque ripple are studied respectively. The torque ripple under different working conditions is calculated, and the main factors causing and increasing torque ripple during normal operation of hydro generator are determined. Results: The torque ripple increases approximately linearly with the increase of the 7th and 11th harmonic contents, while it increases nonlinearly with the increase of the 5th harmonic contents. When the excitation current increases from 720 A to 960 A, the torque ripple is increased by 11.4 kN•m. In addition, when the excitation current increases from 720A to 840A (Rated excitation current of the generator is 840A), the torque ripple increases greatly, the torque ripple increases by 6.6 kN•m. When the excitation current exceeds the rated excitation current, due to the influence of magnetic saturation, the increasing extent of torque ripple gradually decreases. When the excitation current increases from 840A to 960A, the torque ripple increases only by 4.8kN•m. Conclusion: Due to the armature reaction, the harmonic magnetic potential will be generated in the generator, which will affect its torque ripple. The torque ripple of the generator will increase obviously with the increase of harmonic content. When the generator is in no-load operation, the slot effect is the main cause of the torque ripple. In the actual operation of the generator, it usually needs to adjust the excitation current to make the generator meet the requirements of various working conditions.

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.

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.

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.

Due to an unfortunate oversight the acknowledgment has been omitted.

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.