When the alternating magnetic flux passes through the conductor, an induced electromotive force is generated in the electric conductor. Under the action of the induced electromotive force, a loop current is generated in the conductor to cause the conductor to generate heat; since the alternating magnetic flux passes through the conductor, And in the conductor induced electromotive force and loop current phenomenon, people call it eddy currents, because the loop current generated by it is not output as energy, but is lost in its own conductor. The eddy current loss of the switching power supply transformer accounts for a large proportion of the total loss of the switching power supply. How to reduce the eddy current loss of the switching power supply transformer is an important part of the switching power supply transformer or switching power supply design. The eddy current loss of the switching power supply transformer accounts for a large proportion of the total loss of the switching power supply. How to reduce the eddy current loss of the switching power supply transformer is an important part of the switching power supply transformer or switching power supply design. The principle of eddy current loss in transformer production is relatively simple, because the transformer core is not only a good magnetically conductive material, but it is also a kind of electrical conductor; when the alternating magnetic force line passes through the electrical conductor, the electrical conductor The induced electromotive force will be generated. Under the action of the induced electromotive force, a loop current will be generated in the electrical conductor to cause the conductor to generate heat; this phenomenon occurs because the alternating magnetic force lines pass through the conductor and generate induced electromotive force and loop current in the conductor. It is called an eddy current because the loop current it produces is not output as energy but is lost to its own conductor. The calculation of the eddy current loss of the single-excited switching power supply transformer and the calculation of the eddy current loss of the double-excited switching power supply transformer are different in method. However, the method used to calculate the eddy current loss of a single-switching switching power supply transformer can be used to calculate the eddy current loss of a double-shocked switching transformer with only a slight change. For example, consider the bipolar input voltage of a double-shocked switching power supply transformer as two unipolar input voltages with different polarities, so that the eddy current loss of a double-shocked switching power supply transformer can be calculated. Therefore, the following only analyzes the eddy current loss calculation of a single-excitation switching transformer. When a DC pulse voltage is applied to both ends of the primary winding of the transformer, excitation current flows through the primary winding of the transformer, and a magnetic field strength H and a magnetic flux density B are generated in the transformer core. Both are determined by the following equation: : In order to reduce the eddy current loss, a conventional transformer iron core is generally designed to be composed of a plurality of thin iron pieces, simply called iron chips, which are stacked on top of each other and insulated from each other. Figure 2-18 shows a ferrite core in a transformer core or a transformer core. We can think of these iron chips as being composed of a very large number of "coils" (shown in dotted lines in the figure) that are tightly bound together; when the alternating magnetic flux lines pass vertically through these "coils", in these "coils" Induced electromotive force and induced currents are generated, and these "coils" lose electromagnetic energy due to the resistance of these "coils". During the action of DC pulses, the mechanism of eddy current and the mechanism of forward voltage output are basically the same. The direction of the magnetic field generated by the eddy current is opposite to the direction of the magnetic field produced by the exciting current. The demagnetizing force is the strongest at the center of the iron chip, and the demagnetizing force at the edge is zero. Therefore, the distribution of the magnetic flux density in the core sheet is not uniform, that is, the magnetic field intensity of the outermost layer is the largest and the center is the smallest. If the eddy current demagnetization is strong, the maximum value of the magnetic flux density may far exceed its average value, which is determined by the amplitude and width of the known pulse. This news source China iron core trading network Customized Laboratory Table Frame Table leg, Table Frame, Workbench Frame, Bed Frame, Chassis Frame, Table, Frame MGX Metalworks Co., Ltd. , https://www.metal-mgx.com
Analysis of Eddy Current Loss in Transformer Core