Spherical harmonic coefficients for the potential of a constant-density polyhedron

Recurrent relationships for the definitions of fully normalized spherical harmonic coefficients C?_n,m and S?_n,m are derived and integrated analytically to yield the gravitational potential of a constant-density polyhedron. The algorithm is expressed in a C language computer program.     

供电网络中设备的谐波抗扰性试验

阐述了供电网络谐波的产生及交流电源端口设备谐波抗扰性试验方法和试验等级。     

独立分量分析法在电能质量监测与分析中的应用

介绍了目前的电能监测设备,讨论了电能质量监测与分析方法,分析了傅里叶变换、短时傅里叶变换、Wigner谱分析和小波变换的不足之处,提出可以将独立分量分析法(independentcomponentanalysis,ICA)应用于电能质量的监测与分析中。基于ICA的原理通过2个实验模拟了电网中出现电压跌落、电压上升、欠电压、电压波动、瞬时脉冲等电能质量扰动的情况,对含强噪音与干扰的电网电压进行了监测和分析,并用仿真试验验证了将ICA应用于电能质量监测与分析的正确性和有效性。     

级联型换流器在超导储能系统中的应用

超导储能用大功率换流器的选择直接影响了超导储能系统的工作性能。比较了近年来常用的大功率换流电路的特点,阐述了采用级联型电路作为超导储能用大功率换流器的思路,并给出了级联型模块化的超导储能电路拓扑结构。提出了超导储能装置低延迟电压补偿算法及谐波提取算法,并进行了原理仿真,结果表明超导储能系统采用级联型换流器能够有效地进行有源滤波和电压补偿工作,使电压暂降得到快速补偿,并基本上消除了系统谐波。     

非线性振荡电路的一种分析方法

借助渥尔特拉级数研究了振荡波形接近正弦波的自激振荡问题,并给出了高次谐波分量的求解方法,利用这种方法无需导出振荡电路的微分方程,只需求解由电路所得出的代数方程式.数值计算表明了这种方法的正确性与有效性.     

有源电力滤波器检测滞后补偿误差的分析与建模

分析了DSP数字控制采集处理时间滞后对电力滤波器补偿的影响，论述了时问滞后对补偿结果造成的误差．中由单一失真频率入手，推导出补偿误差理论估计的数学模型，并将其扩展到多重失真频率，导出对确定负载、确定滞后时间的总理论补偿误差的计算公式．用这个公式可以分析由任何因素引起得时间滞后所造成的补偿误差．最后，通过实验对误差模型进行验证．由分析结果表明，时间滞后将在补偿中引起严重的误差；采样频率越低，电力滤波器产生的补偿误差就越大．     

电机定子铁损试验研究与对比分析

通过铁损试验的实例，对铁损试验的磁通进行了分析。指出铁损试验磁通与电机实际运行的磁通二者之间的差异，并分析两磁通存在差异的原因。     

超高功率电弧炉对电网的干扰及防护

超高功率电弧炉在正常生产时会对电网造成不利影响，介绍了莱钢50t电炉工程改造方案的确定及措施、SVC系统保护与连锁。     

Development of Motor Model of Rotor Slot Harmonics for Speed Sensorless Control of Induction Motor

This paper proposes a novel mathematical dynamic model to represent the steady‐state and transient‐state characteristics of rotor slot harmonics of an induction motor for sensorless control. Although it is well known that the rotor slot harmonics originate from the mechanical structure of the induction motor, a mathematical model that describes the relationship between the stator/rotor currents of the induction motor and the slot harmonics has not yet been proposed. Therefore, in this paper, a three‐phase model of the induction motor that depicts the rotor slot harmonics is developed by taking into consideration the magnetomotive force harmonics and the change in the magnetic air gap caused by the rotor slots. The validity of the proposed model is verified by comparing the experimental results and the calculated values. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(3): 63–74, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22478     

Iron Loss Analysis of Permanent Magnet Motors Fed by PWM Inverter

Carrier harmonic losses that consist of iron loss, eddy current loss, and ac copper loss are produced in a permanent magnet machine driven by a PWM inverter. It is already known that a higher motor inductance can lead to lower carrier harmonic losses. This paper investigates the carrier harmonic loss composition of two motors with identical dimensions but different inductances. The results of finite element analysis (FEA) showed that the eddy current loss in the iron core accounts for most of the carrier harmonic loss. It is also shown that the carrier harmonic loss of the iron core is quantifiable using theoretical calculations.