变压器的基本知识（Basic knowledge of transformer）.docVIP

变压器的基本知识（Basic knowledge of transformer） Basic knowledge of transformer Transformers are used in almost all electronic products. The principle is simple, but according to the different use occasions (different uses), the winding process of transformer will have different requirements. The main functions of transformers are voltage conversion, impedance transformation, isolation, voltage stabilization (magnetic saturation transformer), etc. the core shapes commonly used in transformers are E and C cores. I. The basic principle of transformer Figure 1 is a simplified diagram of the transformer principle, when a sinusoidal AC voltage U1 in the primary coil ends when the wire is I1 alternating current and alternating magnetic flux Phi 1, it along the core through the primary and secondary coils to form a closed. U2 induced potential transformer in the secondary coil, and phi 1 will also induce a self induction of E1 in the primary coil, the direction of E1 and U1 in the opposite direction and the applied voltage was similar, which limits the size of I1. In order to maintain the existence of magnetic flux Phi 1 requires a certain power consumption, and the transformer has a certain loss, even though no secondary load is connected, there is still some of the current in the primary coil, the current US called no-load current. If the secondary load connected to the secondary coil to generate current, I2, and the resulting magnetic flux Phi 2, Phi 2 and phi 1 opposite direction, up against each other, making the total magnetic flux in the core is reduced, so that the primary self induction voltage E1 decreases, the I1 increases, the visible primary current have a close relationship with secondary load. When the secondary load current increases when I1 increases, Phi 1 and phi 1 also increased, part of the increase is just added a part of the 2 offset magnetic flux phi, in order to maintain the total flux in the same amount of iron. If the loss of the transformer is not consi