Over the last decade,practical digital control of high-frequency switched-mode power converters has moved from proof-of-concept demonstrations to controller chips commercially available from multiple vendors,with appl...Over the last decade,practical digital control of high-frequency switched-mode power converters has moved from proof-of-concept demonstrations to controller chips commercially available from multiple vendors,with applica-tions to point-of-load and isolated DC/DC converters,microprocessor power supplies,power-factor-correction rectifiers,and others.This paper summarizes some of the advances in the area,including approaches to realizations of high-per-formance,high-frequency digital pulse-width modulated(DPWM) controllers,related analysis,modeling and design techniques,as well as performance gains enabled by digital control such as dynamic response and efficiency improve-ments.Examples of experimentally demonstrated results are presented,together with pointers to areas of current and future research and development.展开更多
It is well known that a SMPS （switched-mode power supply） is easy to produce strong EMI （electromagnetic interference） and fails in EMC （electromagnetic compatibility） test for its far field radiation exceeds th...It is well known that a SMPS （switched-mode power supply） is easy to produce strong EMI （electromagnetic interference） and fails in EMC （electromagnetic compatibility） test for its far field radiation exceeds the limits between 30-200 MHz. Based on asymmetry line antenna theory, a novel far field CM （common mode） radiation model, including an equivalent driving source, radiation structure and some key influence factors, is identified and built up for a small flyback power supply. Radiation characteristics of this model are predicted by using Ansoft HFSS software and the model effectiveness is verified by experiment. In the end, the radiation role of some key factors, such as the length of output cable, common mode impedance of AC grid, layout of cable and reflected ground, are studied using simulation in detail.展开更多
In the current practical science, the accuracy in the formability of metal alloys being the goal when using electromagnetic forming (EMF) technology, which is a high-speed processing technology that uses Lorentz force...In the current practical science, the accuracy in the formability of metal alloys being the goal when using electromagnetic forming (EMF) technology, which is a high-speed processing technology that uses Lorentz forces to achieve plastic deformation of sheet metal;according to the previous analysis, the results have shown that in most cases, the Lorentz force acting on the workpiece (metal) is not uniform, there are uneven axial deformations of the metal plates which prevent the rapid advancement of today’s technology. In this article, we presented some advanced analyzes which will lead us to improve the technical solution for the problems of non-uniform axial deformations of the metals in the traditional tube electromagnetic forming technology (EMF). A field shaper is used as a practical forming tool to influence the magnetic field and magnetic pressure distribution, thereby improving the forming ability and result during the electromagnetic forming (EMF) process and we see that induced eddy current control is realized by changing the structural parameters of the magnetic field shaper;which improves the strength and controllability of the magnetic force that acts on the workpiece;thereby a greater radial magnetic pressure can be achieved with field shaper than the case without it;the field shaper regulates the electromagnetic force, the distribution of the magnetic pressure decreases, and the uniform force area of the tube increases which effectively enhances the uniform range of the pipe electromagnetic bulging and the electromagnetic induction coupling between the coil and the metallic workpiece is generally required to produce the Lorentz forces. Using COMSOL Multiphysics® simulation software helped us to accurately represent the real world, simulating multiple physical effects that happened in this model during the process.展开更多
Eutectic Au-12 Ge solder was employed to bond the SiC power devices to a Si3N4/Cu/Ni（P）/Au multilayered substrate.The high-temperature reliability of the bond was investigated in detail at 200,250,300 and 330 ℃,res...Eutectic Au-12 Ge solder was employed to bond the SiC power devices to a Si3N4/Cu/Ni（P）/Au multilayered substrate.The high-temperature reliability of the bond was investigated in detail at 200,250,300 and 330 ℃,respectively.NiGe and Ni5Ge3intermetallic compounds（IMCs） were identified at the Au-12Ge/Ni（P） interface by micro X-ray diffraction（μXRD） and scanning electron microscopy（SEM）equipped with energy dispersive X-ray analysis（EDX）.The growth of the Ni-Ge IMCs was dominated by Ni5Ge3layer,which formed at the Ni5Ge3/NiGe interface by outward diffusion of Ni from the Ni（P） layer.The activation energy of the total Ni-Ge IMCs growth was 66 kJ/mol.The shear strength of the bond was tested at both 25 ℃ and the aging temperatures,respectively.The shear strength decreased slightly after aging at 200 and 250 ℃.The shear strength tested at 250 ℃ was 46 MPa after aging at 250 ℃ for 3000 h.The shear strength aged at 300 and 330 ℃ rapidly decreased with aging time due to the rapid growth of the Ni5Ge3IMC.To slow down the interfacial reaction between the high temperature solder and the Ni（P）layer,an approximately 200 nm-thick Ta/TaN/Ta new diffusion barrier（DB） was deposited on the substrate.Analysis by transmission electron microscopy（TEM） equipped with EDX,reveals that the Ta/TaN/Ta DB was bonded well to the Ni（P） layer and the solder.High temperature storage test at 330 ℃ for1500 h reveals that the bond of the SiC devices maintained its high shear strength of approximately56 MPa without decrease.The new DB effectively suppressed the interfacial reaction between the Au-12 Ge solder and the Ni（P） layer of the substrate.展开更多
Modeling method for the current control loop of a grid-connected PWM inverter with the LCL output filter was discussed.Firstly,the current control loop with the LCL inverter-side current as feedback was established.Th...Modeling method for the current control loop of a grid-connected PWM inverter with the LCL output filter was discussed.Firstly,the current control loop with the LCL inverter-side current as feedback was established.Then,parameters of PI controller were calculated on the basis of an equivalent controlled object.Finally,Norton equivalent circuit for the current control loop of grid-connected system was derived by integrating one control equation,which connected the PWM inverter output voltage and the LCL inverter-side current,with two circuit equations,separately using the LCL inverter-side current and the injected current as loop currents.With the induced Norton equivalent circuit,system-level resonant and unstable issues on real grid-connected system applied in weak distributed power systems can be easily analyzed.The validity of substituting Norton equivalent circuit for grid-connected system is verified by simulation and experiment.展开更多
Maximum power point tracking(MPPT)systems are being developed to produce switching pulses with proper duty ratios for power switches to exert photovoltaic(PV)panels under maximum instantaneous generated power,usually ...Maximum power point tracking(MPPT)systems are being developed to produce switching pulses with proper duty ratios for power switches to exert photovoltaic(PV)panels under maximum instantaneous generated power,usually through a traditional DC-DC boost converter.The fundamental issue,particularly for micro-grid and small-scale green DC or AC energy applications,is that the voltage supplied by the MPPT boost converter is insufficient.In order to increase resulting MPP voltage,this research proposes a new high-voltage gain DC-DC boost converter for a cascade connection with an MPPT boost converter.Input side of the proposed converter employs a switched-inductor cell to reduce input current source ripples which is a critical problem in PV systems for high-reliability applications.Additionally,a switched-capacitor cell is used at the converter’s output side to boost voltage gain and reduce voltage stress across converter’s power switches,which is a crucial factor for longer life of PV panel and proposed converter components,particularly semiconductor devices.Performance of the converter is assessed while taking into account variations in irradiation and temperature brought on by changing weather conditions.A prototype converter at a laboratory scale is utilized and examined.Outcomes of hardware tests support the findings of theoretical and simulation studies.展开更多
In this paper,common mode(CM)and differential mode(DM)far-field radiation models of a typical digital inverter with cables are built up to predict electromagnetic field strength and analyze field characteristics.The C...In this paper,common mode(CM)and differential mode(DM)far-field radiation models of a typical digital inverter with cables are built up to predict electromagnetic field strength and analyze field characteristics.The CM current model and its analyses are based on the imbalance difference method.It is found out that the voltage between the drain and the source electrodes of upper transistor is the key equivalent source of electromagnetic interference(EMI).Far-field radiation strength of the digital inverter in free space is predicted by using the asymmetrical antenna radiation method and current loop radiation method.The accuracy of these methods is verified by the CST electromagnetic simulation results in the frequency range from 1 MHz to 400 MHz.Furthermore,the radiation models are improved by using the mirror method,which enables to include the reflection effect of the metal ground plane at the electromagnetic compatibility(EMC)test site.Both the results of measurements in a semi-anechoic chamber and the simulation results confirm the proposed electromagnetic radiation prediction method.展开更多
On the basis of a conventional permanent magnet(PM)synchronous generator’s construction,a novel kind of Hybrid Excitation Permanent Magnet Synchronous Generator(HEPMSG)is introduced by inserting exciting winding in t...On the basis of a conventional permanent magnet(PM)synchronous generator’s construction,a novel kind of Hybrid Excitation Permanent Magnet Synchronous Generator(HEPMSG)is introduced by inserting exciting winding in the stator or rotor.Firstly,the construction of HEPMSG is improved with the addition of PM excitation on the ferromagnetic pole,and its working principle and design method are studied in detail.Then,an appropriate exciting current control system is presented considering the characteristics of HEPMSG.Finally,a prototype is made,and test results confirm the analysis and design.展开更多
基金The work presented in this paper has been supported by industrial sponsors of the Colorado Power Electronics Center(CoPEC).The authors would like to acknowledge CoPEC graduate students for significant contributions to the results reported in this paper.
文摘Over the last decade,practical digital control of high-frequency switched-mode power converters has moved from proof-of-concept demonstrations to controller chips commercially available from multiple vendors,with applica-tions to point-of-load and isolated DC/DC converters,microprocessor power supplies,power-factor-correction rectifiers,and others.This paper summarizes some of the advances in the area,including approaches to realizations of high-per-formance,high-frequency digital pulse-width modulated(DPWM) controllers,related analysis,modeling and design techniques,as well as performance gains enabled by digital control such as dynamic response and efficiency improve-ments.Examples of experimentally demonstrated results are presented,together with pointers to areas of current and future research and development.
文摘It is well known that a SMPS （switched-mode power supply） is easy to produce strong EMI （electromagnetic interference） and fails in EMC （electromagnetic compatibility） test for its far field radiation exceeds the limits between 30-200 MHz. Based on asymmetry line antenna theory, a novel far field CM （common mode） radiation model, including an equivalent driving source, radiation structure and some key influence factors, is identified and built up for a small flyback power supply. Radiation characteristics of this model are predicted by using Ansoft HFSS software and the model effectiveness is verified by experiment. In the end, the radiation role of some key factors, such as the length of output cable, common mode impedance of AC grid, layout of cable and reflected ground, are studied using simulation in detail.
文摘In the current practical science, the accuracy in the formability of metal alloys being the goal when using electromagnetic forming (EMF) technology, which is a high-speed processing technology that uses Lorentz forces to achieve plastic deformation of sheet metal;according to the previous analysis, the results have shown that in most cases, the Lorentz force acting on the workpiece (metal) is not uniform, there are uneven axial deformations of the metal plates which prevent the rapid advancement of today’s technology. In this article, we presented some advanced analyzes which will lead us to improve the technical solution for the problems of non-uniform axial deformations of the metals in the traditional tube electromagnetic forming technology (EMF). A field shaper is used as a practical forming tool to influence the magnetic field and magnetic pressure distribution, thereby improving the forming ability and result during the electromagnetic forming (EMF) process and we see that induced eddy current control is realized by changing the structural parameters of the magnetic field shaper;which improves the strength and controllability of the magnetic force that acts on the workpiece;thereby a greater radial magnetic pressure can be achieved with field shaper than the case without it;the field shaper regulates the electromagnetic force, the distribution of the magnetic pressure decreases, and the uniform force area of the tube increases which effectively enhances the uniform range of the pipe electromagnetic bulging and the electromagnetic induction coupling between the coil and the metallic workpiece is generally required to produce the Lorentz forces. Using COMSOL Multiphysics® simulation software helped us to accurately represent the real world, simulating multiple physical effects that happened in this model during the process.
基金supported by the NEDO(New Energy and Industrial Technology Development Organization,Japan,P09004)projects,Development of Next-Generation Power Electronics Technology
文摘Eutectic Au-12 Ge solder was employed to bond the SiC power devices to a Si3N4/Cu/Ni（P）/Au multilayered substrate.The high-temperature reliability of the bond was investigated in detail at 200,250,300 and 330 ℃,respectively.NiGe and Ni5Ge3intermetallic compounds（IMCs） were identified at the Au-12Ge/Ni（P） interface by micro X-ray diffraction（μXRD） and scanning electron microscopy（SEM）equipped with energy dispersive X-ray analysis（EDX）.The growth of the Ni-Ge IMCs was dominated by Ni5Ge3layer,which formed at the Ni5Ge3/NiGe interface by outward diffusion of Ni from the Ni（P） layer.The activation energy of the total Ni-Ge IMCs growth was 66 kJ/mol.The shear strength of the bond was tested at both 25 ℃ and the aging temperatures,respectively.The shear strength decreased slightly after aging at 200 and 250 ℃.The shear strength tested at 250 ℃ was 46 MPa after aging at 250 ℃ for 3000 h.The shear strength aged at 300 and 330 ℃ rapidly decreased with aging time due to the rapid growth of the Ni5Ge3IMC.To slow down the interfacial reaction between the high temperature solder and the Ni（P）layer,an approximately 200 nm-thick Ta/TaN/Ta new diffusion barrier（DB） was deposited on the substrate.Analysis by transmission electron microscopy（TEM） equipped with EDX,reveals that the Ta/TaN/Ta DB was bonded well to the Ni（P） layer and the solder.High temperature storage test at 330 ℃ for1500 h reveals that the bond of the SiC devices maintained its high shear strength of approximately56 MPa without decrease.The new DB effectively suppressed the interfacial reaction between the Au-12 Ge solder and the Ni（P） layer of the substrate.
基金Project(51307009)supported by the National Natural Science Foundation of ChinaProject(12JJ4045)supported by Hunan Provincial Natural Science Foundation,China+2 种基金Project(2011KFJJ003)supported by the Key Laboratory for Power Technology of Renewable Energy Sources of Hunan Province,ChinaProject(2011kfj14)supported by the Fund of Key Laboratory of Hunan Province about Power System Operation and Control,ChinaProject(454.13S-20)supported by the Enterprises’Postdoctoral Funds of Pudong Area of Shanghai,China
文摘Modeling method for the current control loop of a grid-connected PWM inverter with the LCL output filter was discussed.Firstly,the current control loop with the LCL inverter-side current as feedback was established.Then,parameters of PI controller were calculated on the basis of an equivalent controlled object.Finally,Norton equivalent circuit for the current control loop of grid-connected system was derived by integrating one control equation,which connected the PWM inverter output voltage and the LCL inverter-side current,with two circuit equations,separately using the LCL inverter-side current and the injected current as loop currents.With the induced Norton equivalent circuit,system-level resonant and unstable issues on real grid-connected system applied in weak distributed power systems can be easily analyzed.The validity of substituting Norton equivalent circuit for grid-connected system is verified by simulation and experiment.
文摘Maximum power point tracking(MPPT)systems are being developed to produce switching pulses with proper duty ratios for power switches to exert photovoltaic(PV)panels under maximum instantaneous generated power,usually through a traditional DC-DC boost converter.The fundamental issue,particularly for micro-grid and small-scale green DC or AC energy applications,is that the voltage supplied by the MPPT boost converter is insufficient.In order to increase resulting MPP voltage,this research proposes a new high-voltage gain DC-DC boost converter for a cascade connection with an MPPT boost converter.Input side of the proposed converter employs a switched-inductor cell to reduce input current source ripples which is a critical problem in PV systems for high-reliability applications.Additionally,a switched-capacitor cell is used at the converter’s output side to boost voltage gain and reduce voltage stress across converter’s power switches,which is a crucial factor for longer life of PV panel and proposed converter components,particularly semiconductor devices.Performance of the converter is assessed while taking into account variations in irradiation and temperature brought on by changing weather conditions.A prototype converter at a laboratory scale is utilized and examined.Outcomes of hardware tests support the findings of theoretical and simulation studies.
基金Supported by the National Natural Science Foundation of China(52077046)Guangdong Natural Science Foundation(2020A1515010913)Shenzhen Science Technology Plan(JSGG20201201100406017).
文摘In this paper,common mode(CM)and differential mode(DM)far-field radiation models of a typical digital inverter with cables are built up to predict electromagnetic field strength and analyze field characteristics.The CM current model and its analyses are based on the imbalance difference method.It is found out that the voltage between the drain and the source electrodes of upper transistor is the key equivalent source of electromagnetic interference(EMI).Far-field radiation strength of the digital inverter in free space is predicted by using the asymmetrical antenna radiation method and current loop radiation method.The accuracy of these methods is verified by the CST electromagnetic simulation results in the frequency range from 1 MHz to 400 MHz.Furthermore,the radiation models are improved by using the mirror method,which enables to include the reflection effect of the metal ground plane at the electromagnetic compatibility(EMC)test site.Both the results of measurements in a semi-anechoic chamber and the simulation results confirm the proposed electromagnetic radiation prediction method.
基金supported by the National High Technology Research and Development Program of China Key Project (No.Z37-03).
文摘On the basis of a conventional permanent magnet(PM)synchronous generator’s construction,a novel kind of Hybrid Excitation Permanent Magnet Synchronous Generator(HEPMSG)is introduced by inserting exciting winding in the stator or rotor.Firstly,the construction of HEPMSG is improved with the addition of PM excitation on the ferromagnetic pole,and its working principle and design method are studied in detail.Then,an appropriate exciting current control system is presented considering the characteristics of HEPMSG.Finally,a prototype is made,and test results confirm the analysis and design.
