电流的

The conclusion is gained that measured waveform and simulated waveform of un-faulted feeder lines are anastomotic and have great comparability, but those of faulted feeder line has much difference compared with its simulated waveform.

比较各馈线零序电流的实测波形和由测后模拟方法所求解的波形发现：健全馈线零序电流的实测波形和由测后模拟法所求解的波形相吻合，具有极强的相似性；而故障馈线零序电流的模拟波形是在假设其正常工作的条件下获取的，实测波形和模拟波形差异较大。

Improve the accuracy of the initial rotor position estimator by using the Fourier series expansion.

在永磁同步的马达启动方面，则透过送出不同向量空间角度的定子电压向量脉冲所量测到的d轴定子电流的大小来估测转子的初始位置，并利用d轴定子电流在空间向量角度以2π为周期的特性，应用傅立叶级数分析做曲线拟合的方式提高转子位置估测解析度，以提高转矩/电流比节省不必要的功率浪费。

The article focuses on the teaching of circuitry,from the basic concept,discusses the direction of the voltage or the electric current in different situations such as Ohm′s law,Kirchhoff′s law,Superposition theorem and so on.

结合在多年的教学，本文针对不同的情况电压和电流的方向做了探讨。1电流电压的实际方向和参考方向习惯上把电流的方向定义为正电荷运动的方向或负电荷运动的相反方向，而把电压的实际方向定义为电位降的方向。

The technique made full use of the characteristic of PR controller which can realize zero steady-state error in AC input signal in stationary frame. In the method, the active and reactive current component in the vector control strategy were transformed in the stationary frame to achieve the objective of keeping the DC-link voltage constant, adjusting the power factor and decoupling the active and reactive power. Compared with conventional double close-loop proportional integral controller, the PR technique is better in harmonic compensation without the complex rotating frame transformation and the couple or feedback voltage which is easily influenced by temperature and circuit parameters. The control algorithm is easy to be realized while the robustness and power quality is improved.

该方法充分利用了PR控制器能够在静止坐标系下对交流输入信号无静差控制的优势，将矢量控制策略下的有功电流和无功电流分量转换到静止坐标系下进行调节，实现网侧变换器维持直流电压稳定和调节功率因数的控制任务和双馈电机有功、无功功率的解耦控制，与传统的双闭环PI控制相比，该策略无需繁琐的坐标旋转变换，不存在受温度及电路参数影响的耦合项和前馈补偿项，且易于实现对系统低次谐波电流的补偿，减小了控制算法实现难度，提高了控制系统的鲁棒性和电网电能质量。

That is, the motor winding capacitance in series with the Deputy, due to the role of the capacitor, so that Kim winding current phase ahead of the main winding current in phase 90 °, in accordance with the basic theory of motor learning: When the space two winding axis position is 90 °, and the flow of two windings of the current phase and poor 90 °, its synthesis must be for the rotating magnetic field, magnetic field, so that motor up and running.

这种电动机就是将电容与副绕组串联，由于电容器的作用，使副相绕组中电流的相位超前于主绕组中电流的相位90°，按照电机学的基本理论：当空间两绕组轴线位置为90°，且流入两绕组中的电流相位又差90°时，其合成磁场必为旋转磁场，从而使电机启动和运转。

A low frequency rolling bearing fault diagnosis method based on local projective noise reduction;2. According to characteristics of both the vibration signals and the stator currents when appering a fault in the rolling bearing of the induction motor,Park vector module signal of the three-phase current is calculated,and the envelope of vibration signals from the rolling bearing of the motor is analyzed.

根据感应电机轴承发生故障时的振动信号特性以及定子电流特性，求出三相电流的Park矢量模信号，并将其与电机滚动轴承振动信号经解调处理后的包络信号进行融合分析，可以从振动信号与电流信号的融合谱图中有效地提取轴承故障特征信息，并将其作为故障识别的依据。

The resonant phenomenon of Bridgeless Boost PFC with split inductor s is analyzed using experiments, simulation and equivalent circuit methods.

通过实验、仿真和等效电路模型分析方法对分立电感无桥Boost PFC电路电感电流上叠加有高频谐振电流的现象做出了详细的分析和研究，指出高频谐振是PFC分立电感与电路的寄生电容组成LC振荡回路所引起的，确定了谐振电流的路径和谐振频率的大小。

According to the analysis of reasons of transformer mal-operation in Pingdingshan Electric Power Bureac for years , and according to the present situation of transformer protection studies and applications at home and abroad. This paper points out the shortcomings of discrimination between internal faults and magnetizing inrush, the problems existing in differentiating the slight faults of turn-to-turn in transformer are also advanced. On the base of the electromagnetic characteristics of transformer, the relations between fluxional differential current and voltage of source side analyzed, all the operating states of transformer simulated by EMTP/ATP, the criterion of magnetizing inrush in transformer is got. Through the wavelet analysis of current waveform, using the intense reaction of wavelet transform to the little change of signal, the internal faults of transformer are distinguished by testing local extremum.

本文根据平顶山市电业局历年来变压器保护误动的原因分析，并根据国内外变压器保护使用和研究的现状，指出了现有变压器保护在区分变压器励磁涌流和内部故障方面以及在判断变压器匝间轻微故障方面存在的问题和不足；从变压器电磁特性出发，分析了电源侧电压和电流微分之间的关系，利用电磁暂态仿真程序对变压器各种运行状态进行了仿真，并以此建立了判断变压器是否含有励磁涌流的判据；通过对电流波形的小波分析，利用小波变换对信号微小变化极强的反映能力，通过检测电流的局部极值点来区分变压器运行状态，并作为上述判据的补充。

In the research on the backward-wave oscillation suppression the startoscillation current which is derived from Two-wave theory approximately is given up. Four typical un-uniform slow wave structures start-oscillation current equations are derived by backward-wave amplifing gain expressions with the Two-wave theory. Then the start-oscillation current rates I〓/I〓 between ununiform circuit and uniform circuit of the four structures have been got.

在返波抑制问题的研究中，从二波理论出发，抛弃了二波理论中从起振条件出发来得到起振电流近似表达式的方法，而是利用二波理论的基本关系式分别推导出了四种典型实用的非均匀输出线路的返波增益表达式，采用计算返波增益的方法来得到四种非均匀输出线路的起振电流与均匀输出线路起振电流的比值I〓/I〓。

This paper deals mainly with the stray current distribution in running tunnel of metro by means of analytical method of equivalent circuit diagram and the analytical method ,and discusses the influence of resistance of rail to ground and the resistance of track on the variation of stray current.

利用等效电路分析法和解析法分析了地铁区间隧道中杂散电流的分布，探讨了轨地过渡电阻值以及走行轨阻抗对杂散电流变化的影响，得出轨地过渡电阻的降低和走行轨阻抗的增大是区间隧道中产生杂散电流的主要原域。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。