非正弦激励下纳米晶铁心损耗的计算方法与实验验证

为了提高复杂激励下电力电子装置中铁心损耗的计算精度,该文提出两种用于计算矩形波叠加直流偏置激励(即非正弦激励)下铁心损耗的计算方法.首先,修正延伸到矩形波激励计算的斯坦梅茨公式(RESE)以适应非正弦激励,并推导出相应的计算式.其次,考虑在非正弦激励下,等效电导率ρ 的非线性,对铁耗分离法做进一步修正.然后,构建磁滞回...     

复杂工况下的电磁性能测量技术

针对电工材料供应商提供的磁性材料中电磁性能数据与实际数据有较大差距的问题,提出基于双爱泼斯坦方圈的加权测量法对复杂工况条件下硅钢片（30Q120）的电磁性能进行测量,即测量等效磁路长度、激磁伏安和硅钢片比损耗在不同频率和不同取样角度下的变化曲线,从而使仿真建模所使用的磁化曲线和损耗曲线更接近硅钢片真实的运行状态,增强仿真计算有效性。通过实验验证了等效磁路长度和硅钢片比总损耗在不同环境温度下的变化趋势,且所获实验结果对实际变压器铁心设计和变压器铁心综合损耗系数评价也具有参考价值。     

纳米晶铁心变压器空载损耗的研究

本文作者首先通过实验实测纳米晶铁心损耗曲线,然后基于纳米晶铁心损耗测试结果进行变损耗系数铁损计算模型的研究,得出纳米晶铁心磁滞损耗、涡流损耗和附加损耗系数随频率变化的修正模型,最后以SCB12-L-800/10干式变压器为例,对比分析了纳米晶铁心变压器空载损耗的解析计算与有限元结果。结果显示,变损耗系数铁损计算模型提高了变压器的铁损的计算精度,并且在相同尺寸下对比纳米晶和23RK100铁心材料下变压器的空载损耗,纳米晶铁心变压器空载损耗仅为硅钢片铁心变压器的9.5%,因此,采用纳米晶料替代传统硅钢片作为变压器铁心可有效降低变压器运行中的空载损耗,有利于提高大功率变压器的效率,降低变压器的体积和重量。     

谐波条件下硅钢片磁特性及换流变压器漏磁场计算

谐波电流作用下,变压器铁心硅钢片的磁特性将发生劣化。本文作者提出一种考虑谐波条件下硅钢片磁性能及损耗性能的换流变压器漏磁场计算方法,给出了不同谐波下27ZH100型号硅钢片B-H特性及B-P特性曲线,基于该曲线对换流变压器在谐波作用下的漏磁场展开了计算,给出了不同谐波励磁下换流变压器油箱及夹件漏磁场分布及损耗值,为换流变压器漏磁场的分析提供了一个新的思路。     

特高压变压器用高磁感取向硅钢片励磁特性

为确定不同类型取向硅钢片应用于特高压变压器时的励磁性能,对普通高磁感和经激光刻痕磁畴细化的2类取向硅钢片试样的单位铁损、磁化特性曲线、激磁功率曲线和磁致伸缩率4项基础磁性能进行了对比测试,对采用2类硅钢片设计成的单相双柱旁轭式特高压变压器铁芯时的空载损耗和空载电流进行了计算,对2类硅钢片制造成的1 000 k V特高压变压器主体变整机的空载损耗、空载电流、励磁特性曲线和空载噪声特性进行了试验研究和分析。结果表明:采用经激光刻痕磁畴细化的国产0.27 mm取向硅钢较同厚度进口高磁感取向硅钢片的样品,单位铁损及特高压变压器整机空载损耗小,空载附加损耗系数相近,而两类硅钢样片的磁化电流和磁致伸缩率与特高压变压器整机空载励磁电流和空载噪声无对等关系。     

直流偏磁下不同磁化曲线对变压器铁心损耗仿真的影响

直流偏磁下变压器铁心材料磁化特性采用不同的表述方式,将会产生不同的损耗仿真结果。本文基于爱泼斯坦方圈试验测量了30ZH120取向硅钢片的交流磁滞回环和交流偏磁磁滞回环,详细阐述并解释了交流磁化曲线、直流磁化曲线、平均磁化曲线、交流偏磁磁化曲线和交直流共同作用下磁化曲线的提取方法。从实验数据和理论分析的角度指出了交直流共同作用下磁化曲线与直流磁化曲线是同一条曲线。以两台干式变压器产品模型为例,设计并搭建了使变压器工作在直流偏磁条件的实验电路,测试并仿真计算了直流偏磁下电力变压器铁心的空载损耗。研究表明,计算分析直流偏磁电工设备时,可以用直流磁化曲线描述硅钢片材料的磁性能,为提高直流偏磁下变压器损耗仿真准确性提供了参考依据。     

D23硅钢片损耗曲线的公式化处理

随着计算机辅助设计技术在工程实践中的应用,促进了让计算机代替人来准确而迅速地查取设计中所用到的曲线和图表的迫切性,故需对这些曲线和周表作数学处理。一个良好的数学处理结果是提高计算机程序质量、减少计算量、节约内存和提高计算精度的根本保障。本文介绍用曲线拟合法对中小电机设计中常用的D23型硅钢片损耗曲线的公式化处理结果,以供读者实际使用。众所周知,处于交变磁场中的铁磁材料,其功率损耗分为磁滞损耗和涡流损耗两个部分;处于正弦交变磁场下的硅钢片的比损耗大小,可以用下式来表达:     

从铁心截面到空载损耗参数化计算

空载损耗计算时要经常根据硅钢片的性能曲线查找单位损耗，费时又不完全准确。提出了新的设计思路，运用相关计算软件，精确计算了变压器铁心重量，实现了空载损耗参数化计算。     

材料的导磁性能对永磁机构动态特性的影响

为了提高永磁机构操作性能,研究材料的导磁性能对其动态特性的影响,笔者利用有限元法建立了永磁机构电、磁、机械耦合场数学模型,求解泊松方程、电压方程及运动方程来研究其操动过程。在求解中,分别计算并分析了静铁心采用硅钢片及电工纯铁时永磁机构各参量随时间变化的曲线,结果显示,采用硅钢片的永磁机构具有较好的速度特性及较小的能耗。研制并测试了静铁心采用硅钢片的永磁机构样机,给出了速度曲线及激磁电流波形。与仿真结果比较,表明所得结论准确可靠。     

温度对取向硅钢磁性能的影响

为研究不同环境温度对取向硅钢片磁性能的影响,将25 cm爱泼斯坦方圈置于高低温试验箱中,分别测试了25、50、75、100、125℃下硅钢片30Q120磁性能,包括损耗曲线、磁化曲线、导磁率、矫顽力、剩余磁感应强度等,通过对试验结果的分析,得到了不同环境温度下取向硅钢片的磁性能变化规律,为今后变压器的优化设计提供了参考依据.     

Proposition of new mathematical models with stator core loss factor for induction motor

This paper proposes new mathematical models with stator core (iron)‐loss factor for induction motors intended to generate precise and/or efficient torque via vector control. The proposed models have a structure in which the stator core‐loss resistance is equivalently placed purely in parallel with the stator inductance. It is shown that stator core losses consisting of eddy‐current and hysteresis losses can be properly represented by the parallel resistance, and, in particular, eddy‐current loss by a constant one. The models are composed of three basic vector equations in the general frame of an arbitrary angular frequency, such as fourth‐order differential equations describing motor dynamics, the torque equation, and the energy conversion equation. These basic equations are essential for vector control design taking core loss into consideration. The proposed models are most compact in the sense of the number of both the employed parameters and the interior states of the motor. Compactness is an important factor for modeling and is useful for designing vector control systems. © 2000 Scripta Technica, Electr Eng Jpn, 134(1): 64–75, 2001     

On the variation with flux and frequency of the core loss coefficients in electrical machines

A model of core losses, in which the hysteresis coefficients are variable with the frequency and induction (flux density) and the eddy-current and excess loss coefficients are variable only with the induction, is proposed. A procedure for identifying the model coefficients from multifrequency Epstein tests is described, and examples are provided for three typical grades of non-grain-oriented laminated steel suitable for electric motor manufacturing. Over a wide range of frequencies between 20-400 Hz and inductions from 0.05 to 2 T, the new model yielded much lower errors for the specific core losses than conventional models. The applicability of the model for electric machine analysis is also discussed, and examples from an interior permanent-magnet and an induction motor are included.     

Calculation of losses in ferro- and ferrimagnetic materials basedon the modified Steinmetz equation

This paper discusses the influence of nonsinusoidal flux waveforms on the remagnetization losses in ferro- and ferrimagnetic materials of inductors, transformers, and electrical machines used in power electronic applications. The nonsinusoidal changes of flux originate from driving these devices by nonsinusoidal voltages and currents at different switching frequencies. A detailed examination of a dynamic hysteresis model shows that the physical origin of losses in magnetic material is the average rate of remagnetization rather than the remagnetization frequency. This principle leads to a modification of the most common calculation rule for magnetic core losses, i.e., to the “modified Steinmetz equation” (MSE). In the MSE, the remagnetization frequency is replaced by an equivalent frequency which is calculated from the average remagnetization rate. This approach allows, for the first time, the calculation of the losses in the time domain for arbitrary waveforms of flux while using the available set of parameters of the classical Steinmetz equation. DC premagnetization of the material, having a substantial influence on the losses, can also be included. Extensive measurements verify the MSE presented in this paper     

空压机用高速永磁电机铁心和磁钢损耗的影响因素

高速电机具有电流频率高、定子铁耗和转子涡流损耗大等特点。针对额定功率10 kW、额定转速100 000 r/min空压机用高速永磁电机,对比分析了平行充磁和径向充磁、脉冲振幅调制(PAM)方波驱动和基于SiC的正弦波驱动时对损耗的影响。分析结果表明,平行充磁气隙磁密谐波小,空载定子铁心损耗比径向充磁低约40%;驱动方式对电机损耗尤其是转子损耗影响较大,正弦波驱动时转子损耗几乎可忽略,方波驱动时转子损耗占比可达总损耗的20%。针对方波驱动转子损耗大的问题,在转子表面增加一层铜屏蔽层,分析结果表明可以有效降低转子涡流损耗。对同一台带压缩机负载的高速电机对比测试了2种驱动器控制下的母线输入的有功功率,验证了驱动方式对电机损耗的影响。     

电工软磁材料旋转磁滞损耗测量及建模

电力变压器和电机中存在旋转铁心损耗是其损耗预测不准的主要原因之一。针对该问题,提出电工软磁材料旋转磁滞损耗测量及建模方法。首先,矢量磁滞损耗分解为切向损耗和法向损耗两部分,分别根据圆形旋转损耗和交变损耗建模。其次,对软磁复合材料和无取向电工钢片进行模型参数辨识,并比较两种材料的损耗特性和模型参数。最后,利用三维磁特性测量装置进行多种励磁模式下的损耗测量,并对比实验结果与模型预测值。结果表明,在旋转复杂激励下,所提出的模型比传统的Steinmetz模型有更高的精度。     

非正弦励磁下磁芯损耗的计算

磁性元件的损耗在开关电源中占相当大的比例,因此磁芯损耗的计算在开关电源设计中相当重要. 文中首先介绍了在正弦励磁下,计算磁芯损耗的Steinmetz 经验公式,然后对修正的Steinmetz 经验公式进行了回顾.修正后的公式可以用来计算非正弦励磁下的磁芯损耗,同时所需参数和修正前的公式一样.最后介绍修正的Steinmetz 经验公式在开关电源领域中的应用.     

A new approach to calculating core losses in the SRM

In switched reluctance motors (SRM), the flux waveforms are nonsinusoidal and different parts of the magnetic circuit have different waveforms. This paper presents a new approach of taking account of these flux waveforms in the calculation of core losses. Relations between the fluxes of different parts of the magnetic circuits are given in the form of matrix equations, where the fluxes are expressed in terms of normalized flux pulses. Rewriting the eddy-current loss term in the Steinmetz equation in terms of the square of dB/dt and combining it with the matrix equations, eddy-current losses for the complicated flux waveforms of the stator and rotor yokes are calculated. The effect of PWM is taken into account by considering the PWM voltage waveform as dB/dt. From the matrices, it is easy to count how many times full and minor hysteresis loops occur at each pole and yoke segment. The effect of the minor loop is taken into account based on experimental results. The proposed approach gives a systematic procedure for core loss calculation. The derived equations are simple and useful in the design of SRM     

方波激励下纳米晶体铁心损耗模型建立与验证

为了实现电力机车小型化轻量化的发展要求,国内外专家考虑通过采用提高变压器的工作频率减小变压器整体的体积和质量。铁心作为高频变压器的关键部件,可以准确计算铁心损耗,对中高频变压器的设计和优化具有重要作用。针对高频变压器铁心通常是工作在方波或脉宽调制(PWM)波等非正弦激励下的特点,对传统Steinmetz损耗计算模型进行了优化改进,给出了考虑磁密的变化率及波形系数对损耗的影响的Steinmetz改进损耗模型。同时,为了提高损耗模型在不同特征频率下的通用性,进一步对损耗模型系数的非线性进行研究,给出了模型系数随频率变化的非线性函数。最后,利用有限元计算结果同实物测量结果进行比较,证明了所提损耗模型在方波激励下对纳米晶体铁心计算的准确性。     

双向全桥DC-DC变换器中大容量高频变压器绕组与磁心损耗计算

精确预估非正弦波激励下高频变压器绕组与磁心损耗、研究不同模态下变压器损耗的变化趋势,对于电力电子变压器(PET)精细化设计至关重要。在对PET中间级——隔离式双向全桥DC-DC变换器工作原理进行分析的基础上,建立变换器的近似等效电路模型,得到一种适用于隔离式双向全桥DC-DC变换器中高频变压器绕组损耗计算方法。在计算方波、梯形波电压激励下的磁心损耗时,推导出修正的Steinmetz经验公式简化解析计算式,引入仅与占空比和上升时间有关的修正系数,据此可直接利用正弦波激励下的损耗系数,快速获取典型工作模态下磁心损耗。设计制作一台1.2k V/0.3k V/5k V·A非晶合金磁心高频变压器试验模型,将所提方法的计算结果与有限元仿真和试验测量结果对比,验证了所提方法的有效性。     

The efficiency of the electric motor of a subsurface pump with reciprocating action and losses in a leading-in cable

The interdependence of loss in an alternating-current converter-fed motor with a frequency and level of supply voltage for an alternating-current converter-fed reciprocating action motor is shown in this work. The equations for efficiency of a supply cable with a length up to 3 km are presented. The influence of a step-down transformer and frequency converter on the losses was considered. It is determined that the line losses are commensurable with the motor losses. In this case, the line efficiency can be matched with the load and the efficiency reduced up to 50%. In addition, the transmission of practically maximum power to the motor is provided. The possibility of using the line losses for warming up a liquid is shown. In the case of a need to warm up a liquid warming, the current of the motor should have the rated value and the voltage frequency should be minimum. To decrease the losses in the line and in the motor, it is necessary to increase the voltage frequency to the rated value. Thus, it is determined whether the voltage frequency should be reduced or increased at the rated motor current. The expressions to calculate the necessary number of the modules of motor at the set well depth are presented. It is shown that, for depths 1, 2, and 3 km, it is possible to use the standard voltages of 380, 660, and 1000 V, respectively. With increasing well depth, the number of motor modules rises, which leads an increase in the voltage proportional to the well depth. An interdependence of the supply voltage of several motor modules with a well depth up to 10 km is obtained.