a Pole voltage waveforms (VA20 and VA40) for modulation index 0.4 (middle trace is A-phase voltage waveform) x-axis: 1 div.=10ms, y-axis: 1 div.= 100V b Normalized harmonic spectrum for pole voltage of Fig. 9a c A-pha...a Pole voltage waveforms (VA20 and VA40) for modulation index 0.4 (middle trace is A-phase voltage waveform) x-axis: 1 div.=10ms, y-axis: 1 div.= 100V b Normalized harmonic spectrum for pole voltage of Fig. 9a c A-phase current and phase voltage for modulation index 0.4 (reference space vector is in inner layer)展开更多
a Pole voltage waveforms (VA20 and VA40) for modulation index 0.4 (middle trace is A-phase voltage waveform) x-axis: 1 div.=10ms, y-axis: 1 div.= 100V b Normalized harmonic spectrum for pole voltage of Fig. 9a c A-pha...a Pole voltage waveforms (VA20 and VA40) for modulation index 0.4 (middle trace is A-phase voltage waveform) x-axis: 1 div.=10ms, y-axis: 1 div.= 100V b Normalized harmonic spectrum for pole voltage of Fig. 9a c A-phase current and phase voltage for modulation index 0.4 (reference space vector is in inner layer)展开更多
换相失败问题(commutation failure,CF)是电网换相换流高压直流输电技术(line commutated converter high voltage directcurrent,LCC-HVDC)面临的固有难题。为了解决该问题,已有文献主要从拓扑结构、控制策略等方面着手,鲜见抵御换相...换相失败问题(commutation failure,CF)是电网换相换流高压直流输电技术(line commutated converter high voltage directcurrent,LCC-HVDC)面临的固有难题。为了解决该问题,已有文献主要从拓扑结构、控制策略等方面着手,鲜见抵御换相失败的新型换流阀研制及试验研究。该文开展基于大功率逆阻型集成门极换流晶闸管(reverse blocking integrated gate commutated thyristor,RB-IGCT)的新型换流阀试验研究及试验等效性分析。首先,阐释新型换流阀抵御换相失败的原理,并针对新型换流阀不同的工作模式,提出对新型电力电子器件的需求。然后,利用现有的型式试验合成回路平台开展适用于传统晶闸管换流阀的运行试验,并分析试验结果,得出大部分试验项目等效性较好而小熄弧角试验和关断试验等效性较差的结论。最后,针对这两项特殊试验提出新的试验方法和试验电路,可为新型换流阀的研发和应用提供一定的技术基础。展开更多
分段并联供电的长定子直线电机在进行定子段供电切换时,电机参数发生改变,在高速运行期间会出现电流超调或断相情况,动子过分段时电机推力波动大。该文仿真分析几种动子过分段供电切换方法的特点,提出一种分段并联供电长定子直线电机定...分段并联供电的长定子直线电机在进行定子段供电切换时,电机参数发生改变,在高速运行期间会出现电流超调或断相情况,动子过分段时电机推力波动大。该文仿真分析几种动子过分段供电切换方法的特点,提出一种分段并联供电长定子直线电机定子段供电切换方法,在电路拓扑中仅需要将同一变流器交替供电的定子段中性点相连接,切换开关采用双向晶闸管,切换策略为在定子段切换过程中各相电流依次过零开通和关断。该方法抑制了切换过程中变流器的电流断续或波动,减小了电机推力波动。通过采用比例–积分–谐振(proportional integral resonance,PIR)控制器,抑制电机电感不平衡带来的电流2倍频波动。以一台双三相永磁同步直线电机为例,进行仿真实验,并验证该方法的有效性。展开更多
Based on ZVZCS （zero voltage zero current switching） full bridge converter technique, a novel inverter welding power supply is designed, in which the secondary side of the transformer adopts passive clamping circuit...Based on ZVZCS （zero voltage zero current switching） full bridge converter technique, a novel inverter welding power supply is designed, in which the secondary side of the transformer adopts passive clamping circuit to reduce voltage stress of rectifying components. This supply can realize power switches ZVS （zero voltage switching ） or ZCS （zero current switching） within a very wide range of load; Only through setting up blocking capacitor in the primary side of transformer, the power transformer＇s bias in the full-bridge converter is suppressed and the primary current can be reset easily. In addition, how to calculate the blocking capacitor and its influence to power supply performance are also subjects discussed in this paper.展开更多
The analysis of WDM (Wavelength-Division Multiplexing) optical network is essential to have the routed wavelength blocking probability with the conversion of wavelength using techniques. In this paper, an enhanced ana...The analysis of WDM (Wavelength-Division Multiplexing) optical network is essential to have the routed wavelength blocking probability with the conversion of wavelength using techniques. In this paper, an enhanced analytical model is proposed to evaluate the blocking performances in topology network and to improve the performances of reduction of blocking probability. The variation of probability is based on the wavelength and load used in the network. The conversion is carried out with the support of optical backbone of the inherent flexibility of the network using the proposed IMCA in Sparse-Partial Wavelength Conversion (SPWC) architecture. It reduces the number of converters significantly with efficient process and provides placement scheme of wavelength converters in the network. The proposed model utilizes the network with the assignment and routing of wavelength using dynamic process of assignment algorithm. The proposed model provides dynamic and static routing process with the range limit to have a minimum conversion for the same probabilities of blocking. The proposed system analysis and the simulation results show the better performances in faster coverage, minimum number of conversions, blocking probability improvement for high load.展开更多
文摘a Pole voltage waveforms (VA20 and VA40) for modulation index 0.4 (middle trace is A-phase voltage waveform) x-axis: 1 div.=10ms, y-axis: 1 div.= 100V b Normalized harmonic spectrum for pole voltage of Fig. 9a c A-phase current and phase voltage for modulation index 0.4 (reference space vector is in inner layer)
文摘a Pole voltage waveforms (VA20 and VA40) for modulation index 0.4 (middle trace is A-phase voltage waveform) x-axis: 1 div.=10ms, y-axis: 1 div.= 100V b Normalized harmonic spectrum for pole voltage of Fig. 9a c A-phase current and phase voltage for modulation index 0.4 (reference space vector is in inner layer)
文摘分段并联供电的长定子直线电机在进行定子段供电切换时,电机参数发生改变,在高速运行期间会出现电流超调或断相情况,动子过分段时电机推力波动大。该文仿真分析几种动子过分段供电切换方法的特点,提出一种分段并联供电长定子直线电机定子段供电切换方法,在电路拓扑中仅需要将同一变流器交替供电的定子段中性点相连接,切换开关采用双向晶闸管,切换策略为在定子段切换过程中各相电流依次过零开通和关断。该方法抑制了切换过程中变流器的电流断续或波动,减小了电机推力波动。通过采用比例–积分–谐振(proportional integral resonance,PIR)控制器,抑制电机电感不平衡带来的电流2倍频波动。以一台双三相永磁同步直线电机为例,进行仿真实验,并验证该方法的有效性。
文摘Based on ZVZCS （zero voltage zero current switching） full bridge converter technique, a novel inverter welding power supply is designed, in which the secondary side of the transformer adopts passive clamping circuit to reduce voltage stress of rectifying components. This supply can realize power switches ZVS （zero voltage switching ） or ZCS （zero current switching） within a very wide range of load; Only through setting up blocking capacitor in the primary side of transformer, the power transformer＇s bias in the full-bridge converter is suppressed and the primary current can be reset easily. In addition, how to calculate the blocking capacitor and its influence to power supply performance are also subjects discussed in this paper.
文摘The analysis of WDM (Wavelength-Division Multiplexing) optical network is essential to have the routed wavelength blocking probability with the conversion of wavelength using techniques. In this paper, an enhanced analytical model is proposed to evaluate the blocking performances in topology network and to improve the performances of reduction of blocking probability. The variation of probability is based on the wavelength and load used in the network. The conversion is carried out with the support of optical backbone of the inherent flexibility of the network using the proposed IMCA in Sparse-Partial Wavelength Conversion (SPWC) architecture. It reduces the number of converters significantly with efficient process and provides placement scheme of wavelength converters in the network. The proposed model utilizes the network with the assignment and routing of wavelength using dynamic process of assignment algorithm. The proposed model provides dynamic and static routing process with the range limit to have a minimum conversion for the same probabilities of blocking. The proposed system analysis and the simulation results show the better performances in faster coverage, minimum number of conversions, blocking probability improvement for high load.
