常用的变压器铁芯一般都是用硅钢片制做的.硅钢是一种合硅(硅也称矽)的钢,其含硅量在0．8~4．8%.由硅钢做变压器的铁芯,是因为硅钢本身是一种导磁能力很强的磁性物质,在通电线圈中,它可以产生较大的磁感应强度,从而可以使变压器的体积缩小.
The commonly used transformer cores are usually made of silicon steel sheets. Silicon steel is a kind of silicon-bonded (silicon) steel whose silicon content is 0.8-4.8%. The core of transformer is made of silicon steel because it is a magnetic material with strong magnetic conductivity. In the current coil, it can produce greater magnetic induction intensity, which can reduce the volume of transformer.
我们知道,实际的变压器总是在交流状态下工作,功率损耗不仅在线圈的电阻上,也产生在交变电流磁化下的铁芯中.通常把铁芯中的功率损耗叫“铁损”,铁损由两个原因造成,一个是“磁滞损耗”,一个是“涡流损耗”.
As we know, the actual transformer always works in the AC state, and the power loss not only occurs in the resistance of the coil, but also in the iron core under the alternating current magnetization. Usually the power loss in the iron core is called "iron loss". The iron loss is caused by two reasons, one is "hysteresis loss" and the other is "eddy current loss".
磁滞损耗是铁芯在磁化过程中,由于存在磁滞现象而产生的铁损,这种损耗的大小与材料的磁滞回线所包围的面积大小成正比.硅钢的磁滞回线狭小,用它做变压器的铁芯磁滞损耗较小,可使其发热程度大大减小.
Hysteresis loss is a kind of iron loss caused by hysteresis in the process of magnetization of iron core. The magnitude of this loss is proportional to the area surrounded by hysteresis loops of materials. The hysteresis loops of silicon steel are narrow and the hysteresis loss of iron core used as transformer is small, which can greatly reduce its heating degree.
既然硅钢有上述优点,为什么不用整块的硅钢做铁芯,还要把它加工成片状呢?
Since silicon steel has the above advantages, why not use the whole piece of silicon steel as the core, but also process it into sheets?
这是因为片状铁芯可以减小另外一种铁损──“涡流损耗”.变压器工作时,线圈中有交变电流,它产生的磁通当然是交变的.这个变化的磁通在铁芯中产生感应电流.铁芯中产生的感应电流,在垂直于磁通方向的平面内环流着,所以叫涡流.涡流损耗同样使铁芯发热.为了减小涡流损耗,变压器的铁芯用彼此绝缘的硅钢片叠成,使涡流在狭长形的回路中,通过较小的截面,以增大涡流通路上的电阻;同时,硅钢中的硅使材料的电阻率增大,也起到减小涡流的作用.
This is because the sheet core can reduce another kind of iron loss - "eddy current loss". When the transformer works, there is alternating current in the coil, and the flux produced by it is of course alternating. This variable flux generates induced current in the core. The induced current generated in the core circulates in the plane perpendicular to the direction of the flux, so it is called eddy current. Eddy current loss also makes the core hot. In order to reduce it. Small eddy current loss, the core of transformer is made up of insulated silicon steel sheets, which makes the eddy current in the narrow loop pass through a smaller section to increase the resistance of the eddy current circuit. At the same time, silicon in the silicon steel increases the resistivity of the material and also plays a role in reducing the eddy current.
用做变压器的铁芯,一般选用0．35mm厚的冷轧硅钢片,按所需铁芯的尺寸,将它裁成长形片,然后交叠成“日”字形或“口”字形.从道理上讲,若为减小涡流,硅钢片厚度越薄,拼接的片条越狭窄,效果越好.这不但减小了涡流损耗,降低了温升,还能节省硅钢片的用料.但实际上制作硅钢片铁芯时.并不单从上述的一面有利因素出发,因为那样制作铁芯,要大大增加工时,还减小了铁芯的有效截面.所以,用硅钢片制作变压器铁芯时,要从具体情况出发,权衡利弊,选择最佳尺寸.
The cold-rolled silicon steel sheet with thickness of 0.35mm is usually used as the core of transformer. According to the size of the core, it is cut into shape sheet and then overlapped into "day" shape or "mouth" shape. In principle, if the eddy current is reduced, the thinner the thickness of silicon steel sheet is, the narrower the spliced strip is, and the better the effect is. This not only reduces eddy www.zhijia.org.cnwww.zhidiaojia.org.cnwww.qibijizhamen.com.cnwww.juanyangqibij.cn www.qingwuji.net.cnwww.yasiban.cncurrent loss, reduces temperature rise, but also saves the material used for silicon steel sheet. When making the core of silicon steel sheet, we should not only start from the advantages mentioned above, because it will greatly increase the working hours and reduce the effective cross-section of the core. Therefore, when making the core of transformer with silicon steel sheet, we should consider the advantages and disadvantages and choose the best size according to the specific conditions.