变压器是变换交流电压、电流和阻抗的器件，当初级线圈中通有交流电流时，铁芯（或磁芯）中便产生交流磁通，使次级线圈中感应出电压（或电流）。变压器由铁芯（或磁芯）和线圈组成，线圈有两个或两个以上的绕组，其中接电源的绕组叫初级线圈，其余的绕组叫次级线圈。在发电机中，不管是线圈运动通过磁场或磁场运动通过固定线圈，均能在线圈中感应电势，此两种情况，磁通的值均不变，但与线圈相交链的磁通数量却有变动，这是互感应的原理。变压器就是一种利用电磁互感效应，变换电压，电流和阻抗的器件。
The transformer is the device transform AC voltage, current and impedance, when there is communication through the primary coil current, the core (or core) will be generated in the exchange flux, the secondary coil induces a voltage (or current). A transformer consists of an iron core or a magnetic coil. The coil has two or more than two windings. The winding of the power supply is called the primary coil, and the other winding is called the secondary coil. In generator, no matter whether the coil movement is moving through magnetic field or magnetic field, it can induce the electric potential in the online loop through the fixed coil. In the two cases, the value of flux is constant, but the number of magnetic flux intersected with the coil is variable, which is the principle of mutual inductance. A transformer is a device that uses the effect of electromagnetic mutual inductance to transform the voltage, current and impedance.