Since the as-cast microstructure benefits dynamic recrystallization(DRX)nucleation,the present research is focused on the microstructure evolution associated with the dendrites and precipitates during the thermal defo...Since the as-cast microstructure benefits dynamic recrystallization(DRX)nucleation,the present research is focused on the microstructure evolution associated with the dendrites and precipitates during the thermal deformation of an ingot without homogenization treatment aiming at exploring a new efficient strategy of ingot cogging for superalloys.The as-cast samples were deformed at the sub-solvus temperature,and the DRX evolution from dendritic arms(DAs)to inter-dendritic regions(IDRs)was discussed based on the observation of the fishnet-like DRX microstructures and the gradient of DRX grain size at IDRs.The difference in the precipitates at DAs and IDRs played an essential role during the deformation and DRX process,which finally resulted in very different microstructures in the two areas.A selective straininduced grain boundary bulging(SIGBB)mechanism was found to function well and dominate the DRX nucleation at DAs.The grain boundary was able to migrate and bulge to nucleate on the condition that the boundary was located at DAs and had a great difference in dislocation density between its opposite sides at the same time.As for DRX nucleation at IDRs,the particle-stimulated nucleation(PSN)mechanism played a leading role,and the progressive subgrain rotation(PSR)and geometric DRX were two important supplementary mechanisms.The dislocation accumulation around the coarse precipitates at IDR resulted in progressive orientation rotation,which would generate DRX nuclei once the maximum misorientation there was sufficient to form a high-angle boundary with the matrix.The PSR or geometric DRX functioned at the severely elongated IDRs at the later stage of deformation,depending on the thickness of the elongated IDRs.The uniform microstructure was obtained by the deformation without homogenization and the subsequent annealing treatment.The smaller strain,the lower annealing temperature,and the much shorter soaking time requested in the above process lead to a smaller risk of cracking and a lower consumption of energy during the ingot-cogging process.展开更多
Cogging torque and electromagnetic vibration are two important factors for evaluating permanent magnet synchronous machine(PMSM)and are key issues that must be considered and resolved in the design and manufacture of ...Cogging torque and electromagnetic vibration are two important factors for evaluating permanent magnet synchronous machine(PMSM)and are key issues that must be considered and resolved in the design and manufacture of high-performance PMSM for electric vehicles.A fast and accurate magnetic field calculation model for interior permanent magnet synchronous machine(IPMSM)is proposed in this article.Based on the traditional magnetic potential permeance method,the stator cogging effect and complex boundary conditions of the IPMSM can be fully considered in this model,so as to realize the rapid calculation of equivalent magnetomotive force(MMF),air gap permeance,and other key electromagnetic properties.In this article,a 6-pole 36-slot IPMSM is taken as an example to establish its equivalent solution model,thereby the cogging torque is accurately calculated.And the validity of this model is verified by a variety of different magnetic pole structures,pole slot combinations machines,and prototype experiments.In addition,the improvement measure of the machine with different combination of pole arc coefficient is also studied based on this model.Cogging torque and electromagnetic vibration can be effectively weakened.Combined with the finite element model and multi-physics coupling model,the electromagnetic characteristics and vibration performance of this machine are comprehensively compared and analyzed.The analysis results have well verified its effectiveness.It can be extended to other structures or types of PMSM and has very important practical value and research significance.展开更多
With the increasing requirement for the mechanical vibration and acoustic noise of the permanent magnet synchronous motor(PMSM)drive system,the demand for cogging torque reduction of PMSM has been considerably increas...With the increasing requirement for the mechanical vibration and acoustic noise of the permanent magnet synchronous motor(PMSM)drive system,the demand for cogging torque reduction of PMSM has been considerably increased.To solve the problem of oversized cogging torque of axial flux PMSM,a rotor topology with hybrid permanent magnet is proposed to weaken the cogging torque.Firstly,the expression of the cogging torque of the axial flux motor is derived,and the influence of the pole-arc ratio of the permanent magnet on the cogging torque is analyzed.Secondly,the rotor structure with hybrid permanent magnet is adopted to reduce the cogging torque.According to the analytical analysis,the constraints of the size and pole-arc ratio between the hybrid permanent magnets are obtained,and the two permanent magnets related to the minimum cogging torque are determined.And the analysis results are verified by the finite element simulation.Furthermore,the motor performance with and without the hybrid permanent magnet is compared with each other.Finally,the cogging torque is significantly reduced by adopting a rotor structure with hybrid permanent magnets.展开更多
For socialized animals,such as prinlates,emotions arc the expression of internal states,which may be recognized by others to adjust an in dividual's potential actions(Girard and Bellone 2020).Facial expressions ar...For socialized animals,such as prinlates,emotions arc the expression of internal states,which may be recognized by others to adjust an in dividual's potential actions(Girard and Bellone 2020).Facial expressions are therefore important signals in communication(e.g.,happy or in pain)and can help individuals understand potential meanings between each other(Dolensek et al.2020).Facial expressions can be expressed and processed freely and are useful in social interactions and bonding(Waller et al.2016).展开更多
Presented the methods to obtain the cogging force of permanent magnet linear synchronous motors(PMLSMs), analyzed the characteristics of the cogging force, and provided a basis for reducing the effect of the cogging f...Presented the methods to obtain the cogging force of permanent magnet linear synchronous motors(PMLSMs), analyzed the characteristics of the cogging force, and provided a basis for reducing the effect of the cogging force. 2-dimensional finite element method(2D FEM) was used to solve the whole motor when its mover was at dif- ferent position, so that the relation was derived between the cogging force and the mover position. The analysis results show that the cogging force between the two ends of the primary iron-core and the secondary permanent magnets (PMs) is sinusoidal function of the mover position under certain conditions only. Two proposed methods, namely direct and indirect methods, are applied to calculate the cogging force between the primary iron-core teeth and the secondary PMs. The agreement of the two methods is validated.展开更多
In this paper,a magnetic field modulation model considering the influence of phase angles is established for the analysis and weakening of the cogging torque of the permanent magnet synchronous wind generations.Compar...In this paper,a magnetic field modulation model considering the influence of phase angles is established for the analysis and weakening of the cogging torque of the permanent magnet synchronous wind generations.Compared with the existing analytical model,the modulation effect of the magnetic field harmonics and phase angle on the cogging torque components is analyzed in the new model.Firstly,flux density model with phase angle characteristics is derived,and the relationship of the cogging torque and magnetic field harmonic is analyzed using energy method.Then,based on the magnetic modulation mechanism,the impact of the phase angle and magnetic field harmonics on the coupling relationship among cogging torque components is analyzed.All cogging torque components are classified as a combination of multiple positive and negative harmonic components,and the contribution characteristics of the components are determined by the harmonic combination and phase angle characteristics.Based on the finite element model(FEM),the magnetic field modulation model of the cogging torque is proved.On the basis of the conclusions obtained,it is further explained that the suppression mechanism of rotor-step skewing is a mutual complementary effect of the positive components and negative cogging components,and the main harmonic is effectively offset by selecting the seasonable of segment number and skewed angle of rotor.Finally,in order to verify the validity of the analysis method,the no-load line back EMF and cogging torque of optimized prototype is tested,and the experimental results agree well with the FEM results.展开更多
基金supported by the Natural Science Foundation of Shaanxi Province of China(No.2023-JC-QN-0466)the National Natural Science Foundation of China(Nos.52305421 and 52175363)+1 种基金the General Research Fund of Hong Kong(No.15223520)the project No.1-ZE1W from the Hong Kong Polytechnic University.
摘要Since the as-cast microstructure benefits dynamic recrystallization(DRX)nucleation,the present research is focused on the microstructure evolution associated with the dendrites and precipitates during the thermal deformation of an ingot without homogenization treatment aiming at exploring a new efficient strategy of ingot cogging for superalloys.The as-cast samples were deformed at the sub-solvus temperature,and the DRX evolution from dendritic arms(DAs)to inter-dendritic regions(IDRs)was discussed based on the observation of the fishnet-like DRX microstructures and the gradient of DRX grain size at IDRs.The difference in the precipitates at DAs and IDRs played an essential role during the deformation and DRX process,which finally resulted in very different microstructures in the two areas.A selective straininduced grain boundary bulging(SIGBB)mechanism was found to function well and dominate the DRX nucleation at DAs.The grain boundary was able to migrate and bulge to nucleate on the condition that the boundary was located at DAs and had a great difference in dislocation density between its opposite sides at the same time.As for DRX nucleation at IDRs,the particle-stimulated nucleation(PSN)mechanism played a leading role,and the progressive subgrain rotation(PSR)and geometric DRX were two important supplementary mechanisms.The dislocation accumulation around the coarse precipitates at IDR resulted in progressive orientation rotation,which would generate DRX nuclei once the maximum misorientation there was sufficient to form a high-angle boundary with the matrix.The PSR or geometric DRX functioned at the severely elongated IDRs at the later stage of deformation,depending on the thickness of the elongated IDRs.The uniform microstructure was obtained by the deformation without homogenization and the subsequent annealing treatment.The smaller strain,the lower annealing temperature,and the much shorter soaking time requested in the above process lead to a smaller risk of cracking and a lower consumption of energy during the ingot-cogging process.
基金supported in part by the National Natural Science Foundation of China under Grant 51737008.
摘要Cogging torque and electromagnetic vibration are two important factors for evaluating permanent magnet synchronous machine(PMSM)and are key issues that must be considered and resolved in the design and manufacture of high-performance PMSM for electric vehicles.A fast and accurate magnetic field calculation model for interior permanent magnet synchronous machine(IPMSM)is proposed in this article.Based on the traditional magnetic potential permeance method,the stator cogging effect and complex boundary conditions of the IPMSM can be fully considered in this model,so as to realize the rapid calculation of equivalent magnetomotive force(MMF),air gap permeance,and other key electromagnetic properties.In this article,a 6-pole 36-slot IPMSM is taken as an example to establish its equivalent solution model,thereby the cogging torque is accurately calculated.And the validity of this model is verified by a variety of different magnetic pole structures,pole slot combinations machines,and prototype experiments.In addition,the improvement measure of the machine with different combination of pole arc coefficient is also studied based on this model.Cogging torque and electromagnetic vibration can be effectively weakened.Combined with the finite element model and multi-physics coupling model,the electromagnetic characteristics and vibration performance of this machine are comprehensively compared and analyzed.The analysis results have well verified its effectiveness.It can be extended to other structures or types of PMSM and has very important practical value and research significance.
基金supported by the Natural Science Foundation of Hubei Province(No.2019 CFB759)。
摘要With the increasing requirement for the mechanical vibration and acoustic noise of the permanent magnet synchronous motor(PMSM)drive system,the demand for cogging torque reduction of PMSM has been considerably increased.To solve the problem of oversized cogging torque of axial flux PMSM,a rotor topology with hybrid permanent magnet is proposed to weaken the cogging torque.Firstly,the expression of the cogging torque of the axial flux motor is derived,and the influence of the pole-arc ratio of the permanent magnet on the cogging torque is analyzed.Secondly,the rotor structure with hybrid permanent magnet is adopted to reduce the cogging torque.According to the analytical analysis,the constraints of the size and pole-arc ratio between the hybrid permanent magnets are obtained,and the two permanent magnets related to the minimum cogging torque are determined.And the analysis results are verified by the finite element simulation.Furthermore,the motor performance with and without the hybrid permanent magnet is compared with each other.Finally,the cogging torque is significantly reduced by adopting a rotor structure with hybrid permanent magnets.
基金This study was supported by the Key Program of the National Natural Science Fund(31730104)National Natural Science Foundation of China(31801981)+5 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDB31020302)National Key Program of Research and Development,Ministry of Science and Technology(2016YFC0503200)Innovation Capability Support Program of Shaanxi(2020KJXX-008)Foundation of Shaanxi Academy of Sciences of China(2016K-20,2018K-16-04,2019ZY-JCTJ-06)Key Research and Development Program of Shaanxi Province of China(2018PT-04)One Institute One Brand Foundation of Shaanxi Academy of Sciences(2020k-01).
摘要For socialized animals,such as prinlates,emotions arc the expression of internal states,which may be recognized by others to adjust an in dividual's potential actions(Girard and Bellone 2020).Facial expressions are therefore important signals in communication(e.g.,happy or in pain)and can help individuals understand potential meanings between each other(Dolensek et al.2020).Facial expressions can be expressed and processed freely and are useful in social interactions and bonding(Waller et al.2016).
基金Supported by the National Natural Science Foundation of China (60474043)
摘要Presented the methods to obtain the cogging force of permanent magnet linear synchronous motors(PMLSMs), analyzed the characteristics of the cogging force, and provided a basis for reducing the effect of the cogging force. 2-dimensional finite element method(2D FEM) was used to solve the whole motor when its mover was at dif- ferent position, so that the relation was derived between the cogging force and the mover position. The analysis results show that the cogging force between the two ends of the primary iron-core and the secondary permanent magnets (PMs) is sinusoidal function of the mover position under certain conditions only. Two proposed methods, namely direct and indirect methods, are applied to calculate the cogging force between the primary iron-core teeth and the secondary PMs. The agreement of the two methods is validated.
基金supported in part by the National Natural Science Foundation of China under Grant 52077142the Research Foundation of Zhengzhou Electric Power College under Grant ZEPCKY2024-01 and ZEPCKYRC01。
摘要In this paper,a magnetic field modulation model considering the influence of phase angles is established for the analysis and weakening of the cogging torque of the permanent magnet synchronous wind generations.Compared with the existing analytical model,the modulation effect of the magnetic field harmonics and phase angle on the cogging torque components is analyzed in the new model.Firstly,flux density model with phase angle characteristics is derived,and the relationship of the cogging torque and magnetic field harmonic is analyzed using energy method.Then,based on the magnetic modulation mechanism,the impact of the phase angle and magnetic field harmonics on the coupling relationship among cogging torque components is analyzed.All cogging torque components are classified as a combination of multiple positive and negative harmonic components,and the contribution characteristics of the components are determined by the harmonic combination and phase angle characteristics.Based on the finite element model(FEM),the magnetic field modulation model of the cogging torque is proved.On the basis of the conclusions obtained,it is further explained that the suppression mechanism of rotor-step skewing is a mutual complementary effect of the positive components and negative cogging components,and the main harmonic is effectively offset by selecting the seasonable of segment number and skewed angle of rotor.Finally,in order to verify the validity of the analysis method,the no-load line back EMF and cogging torque of optimized prototype is tested,and the experimental results agree well with the FEM results.