共查询到20条相似文献,搜索用时 84 毫秒
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变压器铁心剩磁的一种估算方法 总被引:1,自引:0,他引:1
从变压器励磁涌流产生的机理出发,分析变压器的饱和过程。通过理论推导和大量仿真试验得出变压器在不同合闸角度下的饱和电流,估算出在去磁阶段内以及剩磁阶段内饱和电流与剩磁及合闸角的经验公式,进而得出变压器铁芯内剩磁的实用计算公式。 相似文献
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引言在电力系统中,开关动作和系统暂态效应引起的电涌在变压器初级线圈中产生很大的冲击电流,保护继电器能检测出这种冲击电流并引起跳闸动作。非线性磁滞特性和铁心的饱和特性可以为正确决定保护继电器的动作提供重要的参考和信息。铁磁质电磁现象的数学模型主要取决于 相似文献
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剩磁现象的客观存在直接影响着某些试验项目,如电压比试验、大型变压器直流电阻测量、空载试验等。本文还叙述了在进行上述试验时克服剩磁影响的措施和方法。 相似文献
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变压器空载合闸或切除故障合闸都伴随着励磁涌流的出现,励磁涌流的大小受合闸角、剩磁、系统阻抗参数等因素的影响。提出了一种消除单相变压器励磁涌流的策略,利用预充磁装置改变变压器铁心中的磁通,当接近极限磁滞回线的剩磁时,控制断路器的合闸,从而消除励磁涌流。通过理论推导,确定了预充磁装置电容大小与电容电压之间的关系、铁心的充磁程度以及对应的相位。最后,以某单相变压器为例,利用Simulink仿真,验证了该策略。 相似文献
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针对变压器在空载情况下副边电压,电流数据未知,励磁电感不易获取的缺陷,提出了利用变压器磁滞回线上的离散数据点求励磁电感的方法。该方法具体步骤是首先根据变压器空载时原边的电压电流采样数据点找出此时关于磁链与电流的函数关系(磁滞回线),然后由磁滞回线上关于磁链和电流的离散数据点找出算法求励磁电感。通过ATP和Matlab软件相结合,仿真出了磁滞回线和相对应的励磁电感,得出了磁滞回线和励磁电感变化情况与理论分析相符。此方法可以求出空载时的励磁电感。 相似文献
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基于磁通补偿的高压大容量可控电抗器 总被引:1,自引:0,他引:1
研究了一种新型的基于磁通补偿的高压大容量可控电抗器(CRMFC).对于带气隙的变压器,控制它的二次侧电流,使其与一次侧电流反相(或同相),那么,可以在变压器的一次侧端口得到随着一、二次侧电流大小比例变化的电抗值.为了提高电抗器的电压等级和容量,将变压器设计成多绕组的结构形式.文中从理论上证明了多绕组共同工作与双绕组的等效性,讨论了该可控电抗器合适的工作区间,并提出了适合此类可控电抗器的控制方法.在此基础上,研制成功了6kV、800kVar的实验样机,并进行了大量的实验.实验结果证明,该电抗器具有低谐波、快响应、大范围连续可调和低损耗等优点. 相似文献
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本文分析了一种特殊类型的变磁通移相自耦变压器的原理,采用相对漏磁链法对该变压器的阻抗计算进行了分析,并推导出最终的阻抗计算方法和计算公式。 相似文献
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在基于磁偶极子解析模型的漏磁检测正演问题中,已有文献关于磁荷在缺陷壁上均匀分布的假设不成立。磁化后的缺陷材料相当于磁媒质,考虑到材料的非线性,磁荷在整个缺陷材料内及缺陷壁上非均匀分布。所以,该文从磁化后整个缺陷材料区域中磁化强度的分布出发,将单位体积内的磁偶极矩的矢量和等效为一个磁偶极矩,并作为磁场源点。从磁偶极子模型出发,推导出任意单元的磁媒质在场点处产生的磁场的积分公式,将整个缺陷材料的积分问题转换为对若干单元进行积分后的叠加。对于任一单元的积分问题,采用数值积分方法求解,并将该方法扩展到整个源区单元,最终整理得到任一场点处磁场的计算方程。通过COMSOL多物理场仿真软件搭建缺陷材料的漏磁场仿真模型,将仿真结果与计算结果进行对比分析,验证该方法的有效性。 相似文献
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Basic Design Method for SPMSM Based on Air‐Gap Magnetic Flux Density Distribution Focusing on Image Magnetic Pole 下载免费PDF全文
TAKAHIRO SUGIYAMA 《Electrical Engineering in Japan》2017,200(4):53-67
This paper presents a basic design method for the surface‐mounted permanent magnet synchronous motor (SPMSM) for both distributed and concentrated windings. The design is based on the air‐gap magnetic flux density distribution focusing on the image magnetic pole. The calculus equation of the air‐gap magnetic flux density distribution is analytically derived by supposing the magnetic pole is located on the magnet surface and image planes. In this study, a three‐phase and double‐layer stator winding SPMSM that has a linear demagnetizing characteristic magnet, such as a ferrite or rare‐earth magnet is considered. From the required specifications and design conditions, the design target values of the parameters that appear in the voltages equations of the d–q axis coordinate system are calculated. Then, the relational equations for the torque constant, d‐axis inductance, copper loss, and the maximum current density are presented as a function of three design parameters under id = 0 control. They are the stator stack length, the number of coil turns in series in a phase, and the slot bottom length. Hence, this approach reduces the SPMSM basic design to the problem with these design parameters has to be solved. The proposed method makes it possible to address the concentrated winding as a special case of the distributed winding. The FEA results confirm the validity of the proposed basic design method for both distributed and concentrated windings. 相似文献
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Voltage model has been widely used in the field of motor control due to the advantages of the simple structure and less parameters required. A novel motor flux estimator based on phase-locked loop and proportional-integral (PI) regulator is proposed in this paper. This estimator calculates the set point of the torque component of electromotive force (EMF) through synchronous frequency and flux. Then, errors between the set point and the actual value of the EMF torque component are corrected by PI regulator to estimate the flux. This method avoids the problem of the saturation brought by the traditional integrator and the problem of the initial phase error. It also solves the magnitude and phase error problems at low speed in the flux estimator based on the low-pass filter. Finally, the simulation and the experiments are implemented on a cycloconverter-fed motor drive system to verify the effectiveness of this method. Simulation results show that this algorithm works very well at 0.2 Hz, and experimental results show that this algorithm can work well at 0.5 Hz. Meanwhile, this algorithm could detect the initial position of the rotor of separately excited synchronous motor. 相似文献