铁磁元件铁心损耗的低频测量方法

变压器出厂实验需要测量其空载励磁特性、空载损耗和负载损耗。空载损耗主要是铁损耗,测量空载损耗时往往要施加一个容量较大的工频电源。为了减小实验电源容量,使测量设备便携化,提出一种采用低频电源代替工频电源测量铁磁元件铁心损耗的低频测量法。该方法通过施加几个频率的低频电压,测量低频下的铁损耗PFe,得到不同频率的E/f(电动势/频率)-PFe曲线,再通过样条插值法计算频率不同、E/f相等时的铁损耗,根据最小二乘原理计算折算至工频下的铁损耗。并在单相变压器和电流互感器中开展实验,采用15,20,25 Hz的折算结果与工频50 Hz实测结果的相对误差ε5%,相对误差标准差σε0.9。结果表明,该方法折算准确度高、稳定性好,并减小了实验电源容量。

Core Loss Measurement of the Ferromagnetic Components Using Low-Frequency Method Frequency Power Supply

Transformers will have measured no-load excitation characteristics, no-load loss and load loss for factory tests.Generally, a large capacity of industrial-frequency (IF) power supply is needed to measure the no-load loss which mainly consists of core loss.In order to reduce the capacity of testing power supply and make the test equipment portable, a low-frequency power supply rather than IF power supply which was used for core loss measurement of ferromagnetic components, was demonstrated in this paper.By applying several low frequencies voltages, the cure of E/f-PFe(electromotive force/frequency-core loss) via calculating core loss under low-frequency can be first obtained.Core loss under low-frequency of different frequency at constant value of E/f were then calculated through spline interpolation method.Lastly, the converted core loss under IF was determined based on least square method.In addition, experiments were conducted on the current transformer (CT) and single phase power transformer, comparing conversion results which using 15,20,25 Hz with directly measured results under IF, the relative error ε is below 5% and standard deviation of relative error σε is less than 0.9, respectively.These results show that this method possesses high conversion accuracy and stability and reduces the capacity of testing power supply obviously.