An InP optical 90°hybrid based on a×4 MMI coupler with a deep ridged waveguide is designed and fabricated.The working principle of the 90°hybrid is systematically introduced.Three-dimensional beam ropag...An InP optical 90°hybrid based on a×4 MMI coupler with a deep ridged waveguide is designed and fabricated.The working principle of the 90°hybrid is systematically introduced.Three-dimensional beam ropagation method(3D BPM)is used to optimize the structure parameters of the 90°hybrid.The designed compact structure is demonatrated to have a low excess loss less than-0.15 dB,a high common mode rejection ratio better than 40 dB,and a low relative phase deviation less than±2.5°.The designed hybrid is manufactured on a sandwitched structure deposited on an InP substrate.The measured results show that the common mode rejection ratios are larger than 20 dB in a range from 1520 nm to 1580 nm.The phase deviations are less than±5°in a range from 1545 nm to 1560 nm and less than±7°across the C band.The designed 90°optical hybrid is suitable well for realizing miniaturization,high-properties,and high bandwidth of coherent receiver.展开更多
The multiplicity of vector combinations for vectors of combined three-level inverters plays an important role, when deciding on the modulation scheme, to obtain minimum switching per inverter vector change, as describ...The multiplicity of vector combinations for vectors of combined three-level inverters plays an important role, when deciding on the modulation scheme, to obtain minimum switching per inverter vector change, as described in the next Section. This is not possible with reduced common-mode three-level inverter structure, obtained with a five-level cascaded H-bridge configuration, as the space vectors locations do not exhibit multiplicity. Moreover, the proposed configuration requires only two power supplies, whereas the scheme with the five-level H-bridge configuration requires six isolated power supplies.展开更多
The multiplicity of vector combinations for vectors of combined three-level inverters plays an important role, when deciding on the modulation scheme, to obtain minimum switching per inverter vector change, as describ...The multiplicity of vector combinations for vectors of combined three-level inverters plays an important role, when deciding on the modulation scheme, to obtain minimum switching per inverter vector change, as described in the next Section. This is not possible with reduced common-mode three-level inverter structure, obtained with a five-level cascaded H-bridge configuration, as the space vectors locations do not exhibit multiplicity. Moreover, the proposed configuration requires only two power supplies, whereas the scheme with the five-level H-bridge configuration requires six isolated power supplies.展开更多
The Electromagnetic Compatibility (EMC) of direct current (DC) motor windings is a system model which is used to reflect the functional characters of the system in the whole EMC specified frequency (150 KHz ~ 30 MHz)....The Electromagnetic Compatibility (EMC) of direct current (DC) motor windings is a system model which is used to reflect the functional characters of the system in the whole EMC specified frequency (150 KHz ~ 30 MHz). For most motor designing process, it is always used to evaluate the inductance of windings in lower or working frequency;however, when analyzing the conducted interference, it is necessary to take some pa-rameters in high frequency into account in building up the EMC model, such as the noticeable capacitance distributed among the windings or between windings and shells. Past research neglected the common-mode current generated by the high frequency interference within motor bearings coupled with shells, since the parasitic capacitance of rotor core comes from armature windings supplied sufficient paths. In EMC model-ing process for DC motor problem, first, test the impedance of windings by experiments;then, generate the equivalent circuit with overall parameters. At present, it is a difficulty that how to choose the parameters. Most researchers preferred to adopt analytical calculation results, however, it could not reflect the essence of the model since it requires many simplification. Based on this point, this paper adopted ant colony algorithm (ACA) with positive feedback to intelligently search and globally optimize the parameters of equivalent cir-cuit. Simulation result showed that the impedance of equivalent circuit calculated by this algorithm was the same as experimental result in the whole EMC frequency. In order to further confirm the validity of ACA, PSPICE circuit simulation was implemented to simulate the spectrum of common mode Electromagnetic Interference (EMI) of equivalent circuit. The simulation result accords well with the experiment result re-ceived by EMI receiver. So it sufficiently demonstrated correctness of ACA in the analysis of high frequency equivalent circuit.展开更多
To enhance energy interaction among low-voltage stations(LVSs)and reduce the line loss of the distribution network,a novel operation mode of the micro-pumped storage system(mPSS)has been proposed based on the common r...To enhance energy interaction among low-voltage stations(LVSs)and reduce the line loss of the distribution network,a novel operation mode of the micro-pumped storage system(mPSS)has been proposed based on the common reservoir.First,some operation modes of mPSS are analyzed,which include the separated reservoir mode(SRM)and common reservoir mode(CRM).Then,based on the SRM,and CRM,an energy mutual assistance control model between LVSs has been built to optimize energy loss.Finally,in the simulation,compared to the model without pumped storage in the LVS,the SRMand CLRMcan decrease the total energy loss by 294.377 and 432.578 kWh,respectively.The configuration of mPSS can improve the utilization rate of the new energy source generation system,and relieve the pressure of transformer capacity in the LVS.Compared with the SRM,the proposed CRM has reduced the total energy loss by 138.201 kWh,increased the new energy consumption by 161.642 kWh,and decreased the line loss by 7.271 kWh.With the efficiency of the mPSS improving,the total energy loss reduction of CRM will be 3.5 times that of SRM.Further,the CRMcan significantly reduce the reservoir capacity construction of mPSS and ismore suitable for scenarios where the capacity configuration of mPSS is limited.展开更多
This paper presents a 0.6 V 10 bit successive approximation register （SAR） ADC design dedicated to the wireless sensor network application. It adopts a monotonic switching scheme in the DAC to save chip area and pow...This paper presents a 0.6 V 10 bit successive approximation register （SAR） ADC design dedicated to the wireless sensor network application. It adopts a monotonic switching scheme in the DAC to save chip area and power consumption. The main drawback of the monotonic switching scheme is its large common mode shift and the associated comparator offset variation. Due to the limited headroom at the 0.6 V supply voltage, the conventional constant current biasing technique cannot be applied to the dynamic comparator. In this design, a common mode stabilizer is introduced to address this issue in low-voltage design. The effectiveness of this method is verified through both simulation and measurement results. Fabricated with 1P8M 0.13 μm CMOS technology, the proposed SAR ADC consumes 6.3 μW at 1 MS/s from a 0.6 V supply, and achieves 51.25 dB SNDR at the Nyquist frequency and FOM of 21 fJ/conversion-step. The core area is only 120 × 300 μm^2.展开更多
The balanced operational amplifier including its merits and designing methods is discussed by comparing its performance to a conventional differential output amplifier when used in a single balanced stage. A balanced ...The balanced operational amplifier including its merits and designing methods is discussed by comparing its performance to a conventional differential output amplifier when used in a single balanced stage. A balanced OTA circuit design is also presented.展开更多
功率变换器采用脉宽调制时产生的高共模电压CMV(common-mode voltage)会使电机轴电压过高,进而导致高频高幅值轴电流破坏电机绝缘、增加电磁干扰等。为减小中点钳位型NPC(neutral point clamped)三电平变换器的共模电压,提出了基于代数...功率变换器采用脉宽调制时产生的高共模电压CMV(common-mode voltage)会使电机轴电压过高,进而导致高频高幅值轴电流破坏电机绝缘、增加电磁干扰等。为减小中点钳位型NPC(neutral point clamped)三电平变换器的共模电压,提出了基于代数调制框架的共模电压抑制策略:首先,将占空比的确定问题转化为非齐次线性方程组的求解问题;然后,合理地选择调制自由度以实现中点电压NPV(neutral point voltage)平衡控制的目标;其次,根据占空比约束,选择偏置量获取最终占空比;最后,使中间相开关采用反相载波得到新的开关状态组合,实现降低共模电压的目的。所提调制策略无需额外的控制器,实现简单,在保证中点钳位型三电平变换器的中点电压具有良好平衡特性的前提下,可将共模电压降低至直流侧电压的1/6范围内。实验结果验证了所提调制策略的有效性和可行性。展开更多
To characterize the spatial patterns of vertical crustal movement of Chinese mainland,GNSS imaging technology was applied to map the tectonic deformation of the region.In this study,the vertical crustal velocities inf...To characterize the spatial patterns of vertical crustal movement of Chinese mainland,GNSS imaging technology was applied to map the tectonic deformation of the region.In this study,the vertical crustal velocities inferred from GNSS data for Chinese mainland over two decades were rigorously estimated.First,by analyzing the vertical displacement time series from continuous GNSS stations and environmental load data,we found that the annual and semi-annual vertical displacements are highly correlated.This indicates that the vertical seasonal variations on the ground surface are mainly caused by environmental loading.After removing the seasonal variations caused by environmental loads from the GNSS time series,we applied an improved PCA technique to filter out common mode errors.Next,we estimated the optimal noise models for the filtered time series and derived the vertical velocity field of Chinese mainland.Finally,we employed an empirical Spatial Structure Function(SSF)to image the tectonic deformation of Chinese mainland.This method effectively mitigates issues with abrupt circular arc-shaped boundaries in GNSS imaging caused by sparse station networks.The imaging results show that vertical crustal deformation in Chinese mainland generally ranges from-3 to 3 mm/yr,with significant spatial variability.The central and northern parts of Qinghai-Xizang Plateau are identified as primary subsidence zones,indicating that plate boundaries and tectonic compression continue to shape the crustal movement in these regions.The major uplift zones are located in northern and central China,likely linked to regional tectonic activity and plate compression.Subsidence deformation in parts of eastern China appears to be influenced by human activities.展开更多
在三相两电平逆变器中,虚拟空间矢量调制(virtual space vector modulation,VSVM)因其能降低共模电压的幅值和三次谐波而受到广泛关注,但还存在共模电压的谐波成分丰富,且幅值变化和方向变化的发生率较高的问题,为此提出一种改进型VSVM...在三相两电平逆变器中,虚拟空间矢量调制(virtual space vector modulation,VSVM)因其能降低共模电压的幅值和三次谐波而受到广泛关注,但还存在共模电压的谐波成分丰富,且幅值变化和方向变化的发生率较高的问题,为此提出一种改进型VSVM方法。该方法通过分析经典VSVM的矢量合成和共模电压特点,对虚拟矢量和虚拟零矢量所对应的基本矢量进行优化排序,使每个开关周期的共模电压波形相同,均为单个矩形波。进一步分析了所提方法的共模谐波、死区补偿和开关损耗。在逆变器-永磁同步电机系统中进行仿真和实验。结果表明:与经典VSVM相比,所提方法在保持共模电压低幅值的同时,使幅值变化和方向变化的发生率都降低3倍,完全消除基带谐波和边带谐波分量,并使共模电压的高频段峰值平均减小6 dB,且线电流、线电压、转矩和转速等性能依然良好。该方法在不增加系统体积和成本的情况下,能更有效抑制共模干扰,有利于共模滤波器的设计,并为其他共模抑制脉冲宽度调制(pulse width modulation,PWM)方法的研究提供了借鉴。展开更多
Information Commons(信息共享空间)是20世纪90年代末,国外高校图书馆为适应用户需求的变化和研究的需要而建立起来的一种基础设施和新的服务模式,本文先介绍了IC的概念及特点,然后从几个方面介绍了国外图书馆IC的基本情况,最后论述了...Information Commons(信息共享空间)是20世纪90年代末,国外高校图书馆为适应用户需求的变化和研究的需要而建立起来的一种基础设施和新的服务模式,本文先介绍了IC的概念及特点,然后从几个方面介绍了国外图书馆IC的基本情况,最后论述了我国高校图书馆构建IC的策略及注意事项。展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFB0402404)the Beijing Natural Science Foundation,China(Grant No.4194093)the National Natural Science Foundation of China(Grant Nos.61635010,61674136,and 61435002).
文摘An InP optical 90°hybrid based on a×4 MMI coupler with a deep ridged waveguide is designed and fabricated.The working principle of the 90°hybrid is systematically introduced.Three-dimensional beam ropagation method(3D BPM)is used to optimize the structure parameters of the 90°hybrid.The designed compact structure is demonatrated to have a low excess loss less than-0.15 dB,a high common mode rejection ratio better than 40 dB,and a low relative phase deviation less than±2.5°.The designed hybrid is manufactured on a sandwitched structure deposited on an InP substrate.The measured results show that the common mode rejection ratios are larger than 20 dB in a range from 1520 nm to 1580 nm.The phase deviations are less than±5°in a range from 1545 nm to 1560 nm and less than±7°across the C band.The designed 90°optical hybrid is suitable well for realizing miniaturization,high-properties,and high bandwidth of coherent receiver.
文摘The multiplicity of vector combinations for vectors of combined three-level inverters plays an important role, when deciding on the modulation scheme, to obtain minimum switching per inverter vector change, as described in the next Section. This is not possible with reduced common-mode three-level inverter structure, obtained with a five-level cascaded H-bridge configuration, as the space vectors locations do not exhibit multiplicity. Moreover, the proposed configuration requires only two power supplies, whereas the scheme with the five-level H-bridge configuration requires six isolated power supplies.
文摘The multiplicity of vector combinations for vectors of combined three-level inverters plays an important role, when deciding on the modulation scheme, to obtain minimum switching per inverter vector change, as described in the next Section. This is not possible with reduced common-mode three-level inverter structure, obtained with a five-level cascaded H-bridge configuration, as the space vectors locations do not exhibit multiplicity. Moreover, the proposed configuration requires only two power supplies, whereas the scheme with the five-level H-bridge configuration requires six isolated power supplies.
文摘The Electromagnetic Compatibility (EMC) of direct current (DC) motor windings is a system model which is used to reflect the functional characters of the system in the whole EMC specified frequency (150 KHz ~ 30 MHz). For most motor designing process, it is always used to evaluate the inductance of windings in lower or working frequency;however, when analyzing the conducted interference, it is necessary to take some pa-rameters in high frequency into account in building up the EMC model, such as the noticeable capacitance distributed among the windings or between windings and shells. Past research neglected the common-mode current generated by the high frequency interference within motor bearings coupled with shells, since the parasitic capacitance of rotor core comes from armature windings supplied sufficient paths. In EMC model-ing process for DC motor problem, first, test the impedance of windings by experiments;then, generate the equivalent circuit with overall parameters. At present, it is a difficulty that how to choose the parameters. Most researchers preferred to adopt analytical calculation results, however, it could not reflect the essence of the model since it requires many simplification. Based on this point, this paper adopted ant colony algorithm (ACA) with positive feedback to intelligently search and globally optimize the parameters of equivalent cir-cuit. Simulation result showed that the impedance of equivalent circuit calculated by this algorithm was the same as experimental result in the whole EMC frequency. In order to further confirm the validity of ACA, PSPICE circuit simulation was implemented to simulate the spectrum of common mode Electromagnetic Interference (EMI) of equivalent circuit. The simulation result accords well with the experiment result re-ceived by EMI receiver. So it sufficiently demonstrated correctness of ACA in the analysis of high frequency equivalent circuit.
基金sponsored by the State Grid Corporation of China Technology Project(Research on Key Technologies and Equipment Development of Micro Pumped Storage for Distributed New Energy Consumption in Distribution Networks,5400-202324196A-1-1-ZN).
文摘To enhance energy interaction among low-voltage stations(LVSs)and reduce the line loss of the distribution network,a novel operation mode of the micro-pumped storage system(mPSS)has been proposed based on the common reservoir.First,some operation modes of mPSS are analyzed,which include the separated reservoir mode(SRM)and common reservoir mode(CRM).Then,based on the SRM,and CRM,an energy mutual assistance control model between LVSs has been built to optimize energy loss.Finally,in the simulation,compared to the model without pumped storage in the LVS,the SRMand CLRMcan decrease the total energy loss by 294.377 and 432.578 kWh,respectively.The configuration of mPSS can improve the utilization rate of the new energy source generation system,and relieve the pressure of transformer capacity in the LVS.Compared with the SRM,the proposed CRM has reduced the total energy loss by 138.201 kWh,increased the new energy consumption by 161.642 kWh,and decreased the line loss by 7.271 kWh.With the efficiency of the mPSS improving,the total energy loss reduction of CRM will be 3.5 times that of SRM.Further,the CRMcan significantly reduce the reservoir capacity construction of mPSS and ismore suitable for scenarios where the capacity configuration of mPSS is limited.
基金supported by the National Natural Science Foundation of China(No.61204033)the Natural Science Foundation of Jiangsu Province(No.BK2012214)
文摘This paper presents a 0.6 V 10 bit successive approximation register （SAR） ADC design dedicated to the wireless sensor network application. It adopts a monotonic switching scheme in the DAC to save chip area and power consumption. The main drawback of the monotonic switching scheme is its large common mode shift and the associated comparator offset variation. Due to the limited headroom at the 0.6 V supply voltage, the conventional constant current biasing technique cannot be applied to the dynamic comparator. In this design, a common mode stabilizer is introduced to address this issue in low-voltage design. The effectiveness of this method is verified through both simulation and measurement results. Fabricated with 1P8M 0.13 μm CMOS technology, the proposed SAR ADC consumes 6.3 μW at 1 MS/s from a 0.6 V supply, and achieves 51.25 dB SNDR at the Nyquist frequency and FOM of 21 fJ/conversion-step. The core area is only 120 × 300 μm^2.
文摘The balanced operational amplifier including its merits and designing methods is discussed by comparing its performance to a conventional differential output amplifier when used in a single balanced stage. A balanced OTA circuit design is also presented.
文摘功率变换器采用脉宽调制时产生的高共模电压CMV(common-mode voltage)会使电机轴电压过高,进而导致高频高幅值轴电流破坏电机绝缘、增加电磁干扰等。为减小中点钳位型NPC(neutral point clamped)三电平变换器的共模电压,提出了基于代数调制框架的共模电压抑制策略:首先,将占空比的确定问题转化为非齐次线性方程组的求解问题;然后,合理地选择调制自由度以实现中点电压NPV(neutral point voltage)平衡控制的目标;其次,根据占空比约束,选择偏置量获取最终占空比;最后,使中间相开关采用反相载波得到新的开关状态组合,实现降低共模电压的目的。所提调制策略无需额外的控制器,实现简单,在保证中点钳位型三电平变换器的中点电压具有良好平衡特性的前提下,可将共模电压降低至直流侧电压的1/6范围内。实验结果验证了所提调制策略的有效性和可行性。
基金National Natural Science Foundation of China(42274012,42004001)the Science and Technology Innovation Project of Anhui Surveying and Mapping Bureau(2025-KJ-08)+1 种基金the Open Fund of Wuhan Gravitation and Solid Earth Tides,National Observation and Research Station(WHYWZ202107)the Fundamental Research Funds for the Central Universities(JZ2022HGTB0268)。
文摘To characterize the spatial patterns of vertical crustal movement of Chinese mainland,GNSS imaging technology was applied to map the tectonic deformation of the region.In this study,the vertical crustal velocities inferred from GNSS data for Chinese mainland over two decades were rigorously estimated.First,by analyzing the vertical displacement time series from continuous GNSS stations and environmental load data,we found that the annual and semi-annual vertical displacements are highly correlated.This indicates that the vertical seasonal variations on the ground surface are mainly caused by environmental loading.After removing the seasonal variations caused by environmental loads from the GNSS time series,we applied an improved PCA technique to filter out common mode errors.Next,we estimated the optimal noise models for the filtered time series and derived the vertical velocity field of Chinese mainland.Finally,we employed an empirical Spatial Structure Function(SSF)to image the tectonic deformation of Chinese mainland.This method effectively mitigates issues with abrupt circular arc-shaped boundaries in GNSS imaging caused by sparse station networks.The imaging results show that vertical crustal deformation in Chinese mainland generally ranges from-3 to 3 mm/yr,with significant spatial variability.The central and northern parts of Qinghai-Xizang Plateau are identified as primary subsidence zones,indicating that plate boundaries and tectonic compression continue to shape the crustal movement in these regions.The major uplift zones are located in northern and central China,likely linked to regional tectonic activity and plate compression.Subsidence deformation in parts of eastern China appears to be influenced by human activities.
