基于极性变化直流电压源的铁磁元件铁心剩磁通测量方法

剩磁通可能给变压器带来较大的励磁涌流,影响测量互感器的测量精度。然而目前对于变压器的铁心剩磁通测量还没有规范的方法。为了便捷地测量铁心剩磁通,提出一种采用极性变化的直流电压源来测量铁磁元件铁心剩磁通和剩磁系数的方法。该方法采用半桥电路获得极性变化的直流电压,并施加在绕组两端,使铁心分别达到正、负饱和点。绘制整个过程中的磁通与电流关系曲线,即可得到铁心的部分饱和磁滞回线,根据获得的饱和磁滞回线来计算铁心剩磁通和剩磁系数。并且在电流互感器上开展实验,测得在正、负饱和剩磁点和退磁后的磁通零点的剩磁通平均值分别为4.001m Wb、-3.844m Wb和0.048m Wb。结果表明,该方法具有较高的准确性和稳定性,而且需要的退磁电源功率小,方便携带。

Residual Flux Measuring Method on the Core ofFerromagnetic Components Based on Alternating Polarity DCVoltage Source

Residual flux may cause strong inrush current on transformers and affect measuring accuracy of current transformer (CT). Nowadays, measurement of residual flux of transformer core, however, is not standardized. Owing to the convenience of residual flux measurement, alternating polarity DC voltage source, which is used for characterizing residual flux and magnetic remanence coefficient of ferromagnetic core, is demonstrated in this paper. By applying alternating polarity DC voltage generated by half-bridge circuit on windings, negative and positive saturation points of ferromagnetic core are reached, respectively. The saturated part of hysteresis loop is obtained via plotting magnetic flux-current curve during the whole process. Residual flux and magnetic remanence coefficient are then calculated based on the obtained hysteresis loop. In addition, investigation was conducted on the current transformer, and residual flux was measured on positive and negative saturation points along with zero flux point. The average values are 4.001mWb, ?3.844mWb and 0.048mWb, respectively. These results show high accuracy and stability of this method. Besides, the rated power of demagnetization voltage source is low which makes the demagnetization devices more portable.