Current and displacement stiffness are important parameters of axial magnetic bearing(AMB)and are usually considered as constants for the control system.However,in actual dynamic work situations,time-varying force lea...Current and displacement stiffness are important parameters of axial magnetic bearing(AMB)and are usually considered as constants for the control system.However,in actual dynamic work situations,time-varying force leads to time-varying currents and air gap with a specific frequency,which makes the stiffness of appear decrease and even worsens control performance for the whole system.In this paper,an AMB dynamic stiffness model considering the flux variation across the air gap due to frequency is established to obtain the accurate dynamic stiffness.The dynamic stiffness characteristics are analyzed by means of the dynamic equivalent magnetic circuit method.The analytical results show that the amplitude of current and displacement stiffness decreases with frequency increasing.Moreover,compared with the stiffness model without considering the variation of flux density across the air gap,the improved dynamic stiffness results are closer to the actual results.Through the dynamic stiffness measurement method of AMB,experiments of AMB in magnetically suspended molecular pump(MSMP)are carried out and the experimental results are consistent with theoretical analysis results.This paper proposes the dynamic stiffness model of axial magnetic bearing considering the variation of flux density across the air gap,which improves the accuracy of the AMB stiffness analysis.展开更多
The control strategy is presented using passive and active hybrid magnetically suspended flywheels（P＆A MSFWs）,which can help meet the requirements of high precision and high stability for earth-observation satellit...The control strategy is presented using passive and active hybrid magnetically suspended flywheels（P＆A MSFWs）,which can help meet the requirements of high precision and high stability for earth-observation satellites.Compared with the conventional flywheel,P＆A MSFW has more rotation degrees of freedom（DOFs）since the rotor is suspended by magnetic bearings,and thus requires more efficient controllers.A modified sliding mode control law（SMC）to our novel nonlinear and coupled system is presented,which is interrupted by inertia matrix uncertainties and external disturbances.SMC law via Lyapunov method is improved,and a fuzzy control scheme is used to attenuate the chatting and control attitude accuracy and maintain the robustness of SMC.Simulation results are provided to illustrate the efficiency of our model by using our control law.展开更多
Since the first demonstrations of radio-frequency(RF)circuits,the physics of the electromagnetic(EM)field and its regulation and control with codesigned circuits,have become essential competencies of RF circuit design...Since the first demonstrations of radio-frequency(RF)circuits,the physics of the electromagnetic(EM)field and its regulation and control with codesigned circuits,have become essential competencies of RF circuit designers.Leveraging advanced regulation or control methods,numerous high-performance circuits have been developed at RF and millimeter-wave(mm-wave)frequencies.Three main methods of electromagnetic regulation have been widely utilized,namely,the separation of electric and magnetic coupling paths,the manipulation of electromagnetic energy through the coupling of multiple tanks or multiple resonators,and the regulation of electromagnetic fields in air cavities or meta-substrates.The separated coupling paths of electric and magnetic fields provide guidance for designing a high-performance filter topology with a quasielliptical response through additional zeros.The manipulation of the EM field through electrical and magnetic intercouplings of multitanks or multiresonators,such as are used in oscillators,power amplifiers(PAs),etc.,results in remarkable power efficiency,size reduction,and wide bandwidth.The regulation of electromagnetism through an air cavity,patterned substrate,or metasubstrate reduces dielectric losses and size,especially when using a substrate integrated suspended line(SISL)platform.Many excellent circuits have been reported based on SISL with low loss,high integration,and self-packaging.Here,we present state-of-the-art cases that demonstrate the benefits of EM field regulation and control.展开更多
为满足航天用扁平转子磁悬浮飞轮对低功耗磁轴承的需求,提出一类同极性嵌环式永磁偏置径向磁轴承(Radial permanent-magnet-biased magnetic bearing,RPMB),旋转损耗低,工作气隙径向内外双环、轴向同层分布,径向磁力为平面汇交力系,具...为满足航天用扁平转子磁悬浮飞轮对低功耗磁轴承的需求,提出一类同极性嵌环式永磁偏置径向磁轴承(Radial permanent-magnet-biased magnetic bearing,RPMB),旋转损耗低,工作气隙径向内外双环、轴向同层分布,径向磁力为平面汇交力系,具有磁极轴向短、可灵活设计的独特优势。根据全主动、主被动两类磁悬浮飞轮的不同需求,采用磁路分析与有限元仿真的方法,对磁极对齐型、磁极交错型、磁极偏置型三种嵌环式RPMB进行了有针对性的分析与设计,所设计的全主动磁悬浮飞轮,具有轴向长度短、质量小、精度高的优点;所设计的两轴主动磁悬浮飞轮,经优化设计,具有高被动刚度、高电流刚度、电流刚度高稳定性的优点。展开更多
基金Excellent Youth Science Foundation of China(Grant No.51722501)National Natural Science Foundation of China(Grant No.51575025)+1 种基金National Natural Science Foundation of China-Youth Science Foundation(Grant No.61603052)Opening Foundation of State Key Laboratory of Advanced Welding and Joining(Grant No.AWJ-20-R02).
文摘Current and displacement stiffness are important parameters of axial magnetic bearing(AMB)and are usually considered as constants for the control system.However,in actual dynamic work situations,time-varying force leads to time-varying currents and air gap with a specific frequency,which makes the stiffness of appear decrease and even worsens control performance for the whole system.In this paper,an AMB dynamic stiffness model considering the flux variation across the air gap due to frequency is established to obtain the accurate dynamic stiffness.The dynamic stiffness characteristics are analyzed by means of the dynamic equivalent magnetic circuit method.The analytical results show that the amplitude of current and displacement stiffness decreases with frequency increasing.Moreover,compared with the stiffness model without considering the variation of flux density across the air gap,the improved dynamic stiffness results are closer to the actual results.Through the dynamic stiffness measurement method of AMB,experiments of AMB in magnetically suspended molecular pump(MSMP)are carried out and the experimental results are consistent with theoretical analysis results.This paper proposes the dynamic stiffness model of axial magnetic bearing considering the variation of flux density across the air gap,which improves the accuracy of the AMB stiffness analysis.
文摘The control strategy is presented using passive and active hybrid magnetically suspended flywheels（P＆A MSFWs）,which can help meet the requirements of high precision and high stability for earth-observation satellites.Compared with the conventional flywheel,P＆A MSFW has more rotation degrees of freedom（DOFs）since the rotor is suspended by magnetic bearings,and thus requires more efficient controllers.A modified sliding mode control law（SMC）to our novel nonlinear and coupled system is presented,which is interrupted by inertia matrix uncertainties and external disturbances.SMC law via Lyapunov method is improved,and a fuzzy control scheme is used to attenuate the chatting and control attitude accuracy and maintain the robustness of SMC.Simulation results are provided to illustrate the efficiency of our model by using our control law.
文摘Since the first demonstrations of radio-frequency(RF)circuits,the physics of the electromagnetic(EM)field and its regulation and control with codesigned circuits,have become essential competencies of RF circuit designers.Leveraging advanced regulation or control methods,numerous high-performance circuits have been developed at RF and millimeter-wave(mm-wave)frequencies.Three main methods of electromagnetic regulation have been widely utilized,namely,the separation of electric and magnetic coupling paths,the manipulation of electromagnetic energy through the coupling of multiple tanks or multiple resonators,and the regulation of electromagnetic fields in air cavities or meta-substrates.The separated coupling paths of electric and magnetic fields provide guidance for designing a high-performance filter topology with a quasielliptical response through additional zeros.The manipulation of the EM field through electrical and magnetic intercouplings of multitanks or multiresonators,such as are used in oscillators,power amplifiers(PAs),etc.,results in remarkable power efficiency,size reduction,and wide bandwidth.The regulation of electromagnetism through an air cavity,patterned substrate,or metasubstrate reduces dielectric losses and size,especially when using a substrate integrated suspended line(SISL)platform.Many excellent circuits have been reported based on SISL with low loss,high integration,and self-packaging.Here,we present state-of-the-art cases that demonstrate the benefits of EM field regulation and control.
文摘为满足航天用扁平转子磁悬浮飞轮对低功耗磁轴承的需求,提出一类同极性嵌环式永磁偏置径向磁轴承(Radial permanent-magnet-biased magnetic bearing,RPMB),旋转损耗低,工作气隙径向内外双环、轴向同层分布,径向磁力为平面汇交力系,具有磁极轴向短、可灵活设计的独特优势。根据全主动、主被动两类磁悬浮飞轮的不同需求,采用磁路分析与有限元仿真的方法,对磁极对齐型、磁极交错型、磁极偏置型三种嵌环式RPMB进行了有针对性的分析与设计,所设计的全主动磁悬浮飞轮,具有轴向长度短、质量小、精度高的优点;所设计的两轴主动磁悬浮飞轮,经优化设计,具有高被动刚度、高电流刚度、电流刚度高稳定性的优点。
