Reliability is a persistent challenge in power electronics, with component failures significantly compromising system performance. Capacitors, widely used in power converters for filtering, contribute to approximately...Reliability is a persistent challenge in power electronics, with component failures significantly compromising system performance. Capacitors, widely used in power converters for filtering, contribute to approximately 30% of failures, predominantly due to electrochemical corrosion leading to capacitance degradation and catastrophic breakdowns. This paper presents a novel capacitor-free solid-state power filter(SSPF) for three-phase inverters, offering a transformative approach to mitigate reliability issues associated with conventional inductor-capacitor(LC) and active output filters(AOFs). Unlike AOFs, which depend on compact LC structures, the SSPF eliminates capacitors entirely, circumventing their inherent failure modes. Leveraging advanced solid-state devices and transformer technology, the SSPF achieves superior filtering performance, enhances system reliability, and significantly reduces component count, utilizing half the metal-oxidesemiconductor field effect transistor(MOSFET) switches required by AOFs. This design not only lowers costs but also improves efficiency. Simulation and experimental results demonstrate the SSPF's capability to deliver a sinusoidal output voltage at the fundamental frequency. These attributes position the SSPF as a robust, cost-effective, and innovative solution for modern power electronics applications.展开更多
In electrolytic capacitorless permanent magnet synchronous motor(PMSM) drives, the DC-link voltage will fluctuate in a wide range due to the use of slim film capacitor. When the flux-weakening current is lower than-ψ...In electrolytic capacitorless permanent magnet synchronous motor(PMSM) drives, the DC-link voltage will fluctuate in a wide range due to the use of slim film capacitor. When the flux-weakening current is lower than-ψf/Ld during the high speed operation, the flux-weakening control loop will transform to a positive feedback mode, which means the reduction of flux-weakening current will lead to the acceleration of the voltage saturation, thus the whole system will be unstable. In order to solve this issue, this paper proposes a novel flux-weakening method for electrolytic capacitorless motor drives to maintain a negative feedback characteristic of the control loop during high speed operation. Based on the analysis of the instability mechanism in flux-weakening region, a quadrature voltage constrain mechanism is constructed to stabilize the system.Meanwhile, the parameters of the controller are theoretically designed for easier industrial application. The proposed algorithm is implemented on a 1.5 kW electrolytic capacitorless PMSM drive to verify the effectiveness of the flux-weakening performance.展开更多
Converters rely on passive filtering as a crucial element due to the high-frequency operational characteristics of power electronics.Traditional filtering methods involve a dual inductor-capacitor(LC)cell or an induct...Converters rely on passive filtering as a crucial element due to the high-frequency operational characteristics of power electronics.Traditional filtering methods involve a dual inductor-capacitor(LC)cell or an inductor-capacitor-inductor(LCL)T-circuit.However,capacitors are susceptible to wear-out mechanisms and failure modes.Nevertheless,the necessity for monitoring and regular replacement adds to an elevated cost of ownership for such systems.The utilization of an active output power filter can be used to diminish the dimensions of the LC filter and the electrolytic dc-link capacitor,even though the inclusion of capacitors remains an indispensable part of the system.This paper introduces capacitorless solid-state power filter(SSPF)for single-phase dc-ac converters.The proposed configuration is capable of generating a sinusoidal ac voltage without relying on capacitors.The proposed filter,composed of a planar transformer and an H-bridge converter operating at high frequency,injects voltage harmonics to attain a sinusoidal output voltage.The design parameters of the planar transformer are incorporated,and the impact of magnetizing and leakage inductances on the operation of the SSPF is illustrated.Theoretical analysis,supported by simulation and experimental results,are provided for a design example for a single-phase system.The total harmonic distortion observed in the output voltage is well below the IEEE 519 standard.The system operation is experimentally tested under both steady-state and dynamic conditions.A comparison with existing technology is presented,demonstrating that the proposed topology reduces the passive components used for filtering.展开更多
In this work,an IGZO(In-Ga-Zn-O)2T0C DRAM(dynamic random access memory)is demonstrated as a cryogenic memory as low as 77 K.The effects of temperature on the IGZO TFTs electrical properties are investigated.We observe...In this work,an IGZO(In-Ga-Zn-O)2T0C DRAM(dynamic random access memory)is demonstrated as a cryogenic memory as low as 77 K.The effects of temperature on the IGZO TFTs electrical properties are investigated.We observe that the subthreshold swing(SS)is improved from 161 to 99 mV/dec with no penalty of on-state current(ION)@VTH+1 V reduction when temperature decreased from 300 to 77 K.More importantly,the corresponding VTH shift positively from-1 to 0.5 V,indicating a transition from depletion-mode to enhancement-mode of IGZO TFTs,which is crucial for the low power operation and data retention time(DRT)optimization.By integrating this IGZO TFT to 2T0C DRAM,the retention time of the DRAM cell is significantly enhanced to 8000 s at 77 K,more than 5 times longer than the one at 300 K.The optimized data retention time also results from the lower leakage current(6×10^(-18)A/μm)of at 77 K due to the suppress of carriers thermally excitation and tunneling in IGZO channel at cryogenic temperature.Additionally,a large read current margin(I_(data‘1’)/I_(data‘0’))of approximately 103 is achieved across wide temperature range.This study demonstrates the potential of IGZO 2T0C DRAM cells for future cryogenic computing systems.展开更多
为进一步提升电力电子变压器的功率密度、传输效率和可靠性,提出一种开关管数量较少的单级矩阵式电力电子变压器拓扑结构(single-stage matrix-type solid state transformer,SM-SST)。通过将工频全桥与高频半桥共用滤波电容,减少开关...为进一步提升电力电子变压器的功率密度、传输效率和可靠性,提出一种开关管数量较少的单级矩阵式电力电子变压器拓扑结构(single-stage matrix-type solid state transformer,SM-SST)。通过将工频全桥与高频半桥共用滤波电容,减少开关管及电容的数量。无电解电容的矩阵式拓扑结构,提升系统潜在的可靠性和功率密度,并实现源‒荷瞬态功率平衡,从而消除二次纹波功率,且无需电流控制环即可自主完成单位功率因数矫正(power factor correction,PFC)。此外,分析系统在时变直流母线电压下的零电压开关(zero voltage switch,ZVS)特性。综上所述,所提出的SM-SST具有元件少、功率损耗低和功率密度高的优点。最后,搭建1 kW的试验样机,以验证所提方法的正确性和可行性。展开更多
The purpose of this paper is to investigate charging strategies for integrated electrolytic capacitorless onboard chargers(OBC)in electric vehicles(EVs).An integrated OBC shares power converters and inductance with th...The purpose of this paper is to investigate charging strategies for integrated electrolytic capacitorless onboard chargers(OBC)in electric vehicles(EVs).An integrated OBC shares power converters and inductance with the traction system.An electrolytic capacitor is avoided in DC link of this integrated OBC.Thus,volume is reduced and reliability is improved for the power conversion system.In this paper,a charging strategy is proposed for this integrated system with uncontrolled rectification,where active switches are kept off in the power inverter on machine side.Consequently,a virtual DC-link voltage is with a half-wave shape.An extended phase-shift(EPS)operation is proposed for high-frequency DC/DC converters with this charging strategy,respectively.By designing a dedicated modulation and control strategy,sinusoidal charging power and the satisfied grid current are achieved for the system.Both theoretical analysis of operation modes and experimental verification with laboratory prototypes have been presented for the proposed charging strategy.展开更多
基金curruntly supported by the Purdue University Office of Technology Commercialization under Track Code (PRF 71167-01)。
文摘Reliability is a persistent challenge in power electronics, with component failures significantly compromising system performance. Capacitors, widely used in power converters for filtering, contribute to approximately 30% of failures, predominantly due to electrochemical corrosion leading to capacitance degradation and catastrophic breakdowns. This paper presents a novel capacitor-free solid-state power filter(SSPF) for three-phase inverters, offering a transformative approach to mitigate reliability issues associated with conventional inductor-capacitor(LC) and active output filters(AOFs). Unlike AOFs, which depend on compact LC structures, the SSPF eliminates capacitors entirely, circumventing their inherent failure modes. Leveraging advanced solid-state devices and transformer technology, the SSPF achieves superior filtering performance, enhances system reliability, and significantly reduces component count, utilizing half the metal-oxidesemiconductor field effect transistor(MOSFET) switches required by AOFs. This design not only lowers costs but also improves efficiency. Simulation and experimental results demonstrate the SSPF's capability to deliver a sinusoidal output voltage at the fundamental frequency. These attributes position the SSPF as a robust, cost-effective, and innovative solution for modern power electronics applications.
基金supported in part by the Research Fund for the National Natural Science Foundation of China under Grant 52125701, 52007039, 51877054in part by the Key areas R&D Program of Guangdong Province China under Grant 2021B0101310001。
文摘In electrolytic capacitorless permanent magnet synchronous motor(PMSM) drives, the DC-link voltage will fluctuate in a wide range due to the use of slim film capacitor. When the flux-weakening current is lower than-ψf/Ld during the high speed operation, the flux-weakening control loop will transform to a positive feedback mode, which means the reduction of flux-weakening current will lead to the acceleration of the voltage saturation, thus the whole system will be unstable. In order to solve this issue, this paper proposes a novel flux-weakening method for electrolytic capacitorless motor drives to maintain a negative feedback characteristic of the control loop during high speed operation. Based on the analysis of the instability mechanism in flux-weakening region, a quadrature voltage constrain mechanism is constructed to stabilize the system.Meanwhile, the parameters of the controller are theoretically designed for easier industrial application. The proposed algorithm is implemented on a 1.5 kW electrolytic capacitorless PMSM drive to verify the effectiveness of the flux-weakening performance.
文摘Converters rely on passive filtering as a crucial element due to the high-frequency operational characteristics of power electronics.Traditional filtering methods involve a dual inductor-capacitor(LC)cell or an inductor-capacitor-inductor(LCL)T-circuit.However,capacitors are susceptible to wear-out mechanisms and failure modes.Nevertheless,the necessity for monitoring and regular replacement adds to an elevated cost of ownership for such systems.The utilization of an active output power filter can be used to diminish the dimensions of the LC filter and the electrolytic dc-link capacitor,even though the inclusion of capacitors remains an indispensable part of the system.This paper introduces capacitorless solid-state power filter(SSPF)for single-phase dc-ac converters.The proposed configuration is capable of generating a sinusoidal ac voltage without relying on capacitors.The proposed filter,composed of a planar transformer and an H-bridge converter operating at high frequency,injects voltage harmonics to attain a sinusoidal output voltage.The design parameters of the planar transformer are incorporated,and the impact of magnetizing and leakage inductances on the operation of the SSPF is illustrated.Theoretical analysis,supported by simulation and experimental results,are provided for a design example for a single-phase system.The total harmonic distortion observed in the output voltage is well below the IEEE 519 standard.The system operation is experimentally tested under both steady-state and dynamic conditions.A comparison with existing technology is presented,demonstrating that the proposed topology reduces the passive components used for filtering.
文摘In this work,an IGZO(In-Ga-Zn-O)2T0C DRAM(dynamic random access memory)is demonstrated as a cryogenic memory as low as 77 K.The effects of temperature on the IGZO TFTs electrical properties are investigated.We observe that the subthreshold swing(SS)is improved from 161 to 99 mV/dec with no penalty of on-state current(ION)@VTH+1 V reduction when temperature decreased from 300 to 77 K.More importantly,the corresponding VTH shift positively from-1 to 0.5 V,indicating a transition from depletion-mode to enhancement-mode of IGZO TFTs,which is crucial for the low power operation and data retention time(DRT)optimization.By integrating this IGZO TFT to 2T0C DRAM,the retention time of the DRAM cell is significantly enhanced to 8000 s at 77 K,more than 5 times longer than the one at 300 K.The optimized data retention time also results from the lower leakage current(6×10^(-18)A/μm)of at 77 K due to the suppress of carriers thermally excitation and tunneling in IGZO channel at cryogenic temperature.Additionally,a large read current margin(I_(data‘1’)/I_(data‘0’))of approximately 103 is achieved across wide temperature range.This study demonstrates the potential of IGZO 2T0C DRAM cells for future cryogenic computing systems.
文摘为进一步提升电力电子变压器的功率密度、传输效率和可靠性,提出一种开关管数量较少的单级矩阵式电力电子变压器拓扑结构(single-stage matrix-type solid state transformer,SM-SST)。通过将工频全桥与高频半桥共用滤波电容,减少开关管及电容的数量。无电解电容的矩阵式拓扑结构,提升系统潜在的可靠性和功率密度,并实现源‒荷瞬态功率平衡,从而消除二次纹波功率,且无需电流控制环即可自主完成单位功率因数矫正(power factor correction,PFC)。此外,分析系统在时变直流母线电压下的零电压开关(zero voltage switch,ZVS)特性。综上所述,所提出的SM-SST具有元件少、功率损耗低和功率密度高的优点。最后,搭建1 kW的试验样机,以验证所提方法的正确性和可行性。
文摘The purpose of this paper is to investigate charging strategies for integrated electrolytic capacitorless onboard chargers(OBC)in electric vehicles(EVs).An integrated OBC shares power converters and inductance with the traction system.An electrolytic capacitor is avoided in DC link of this integrated OBC.Thus,volume is reduced and reliability is improved for the power conversion system.In this paper,a charging strategy is proposed for this integrated system with uncontrolled rectification,where active switches are kept off in the power inverter on machine side.Consequently,a virtual DC-link voltage is with a half-wave shape.An extended phase-shift(EPS)operation is proposed for high-frequency DC/DC converters with this charging strategy,respectively.By designing a dedicated modulation and control strategy,sinusoidal charging power and the satisfied grid current are achieved for the system.Both theoretical analysis of operation modes and experimental verification with laboratory prototypes have been presented for the proposed charging strategy.
