Seven kinds of magnetic cores are often used in high frequency transformers. They are pot-type magnetic core, RM-type magnetic core, E-type magnetic core, EC, ETD and EER-type magnetic core, PQ-type magnetic core, EP-type magnetic core, toroidal Magnetic core and so on.

1. Pot type magnetic core  The skeleton and winding are almost completely wrapped by the core, resulting in a good EMI shielding effect; the slot core size conforms to the IEC standard, and has good interchangeability in the manufacturing industry; it can provide a simple frame ( PIN) and PCB mounting frame (pin); due to the shape of the tank design, the size of the core and other types is greater than the cost; because its shape is not conducive to heat dissipation, it is not suitable for large power transformer applications.

2. EP core   EP core has a three-dimensional structure with a circular center column. Except for the end contacting the PCB board, the winding is completely wrapped and the shielding is very good; this unique shape is small in two pieces The influence of the air gap formed by the contact surface when the core is assembled, and provides a larger volume and the ratio of the total space utilization.

3. EC, ETD and EER cores   These types of cores are between the E type and the pot type. Like E-type magnetic cores, they can provide enough space, resulting in a large part (the current trend for low-voltage, high-current switching power supplies);The hot shape of the magnetic core is also very good; the central column is cylindrical, which reduces the length of the single-turn winding by 11% compared with the rectangular parallelepiped of the same cross-section, resulting in a reduction of copper loss by 11%. At the same time, the core can provide Higher output power; at the same time, the center column is cylindrical. Compared with the rectangular center column, it also avoids the rectangular edges and corners of the winding insulation winding problem.

4. RM type magnetic core  Compared with the tank type, the two symmetrical sides of the tank type are cut off. This design is more conducive to heat dissipation and the size of the lead; Compared with the shape of the fuel tank, it saves about 40% of the installation space; Needle-free skeleton, can be installed with a pair of pliers;The RM core can be made into a flat shape (the current planar transformer or the winding of the printed circuit board directly designed for the assembly of the core); although the shielding effect is not as good as the tank type, it is still good.

5. PQ cores  PQ cores designed for switching power supply inductors and transformers. The optimized design of the PQ shape of the magnetic core volume, the ratio between the surface area and the winding area; the design enables the use of small cores to provide inductance and possible area enlargement;This design allows for small transformer volume and weight, large output power, and small PCB installation space; it can be fixed with a pair of clips; the effective cross-sectional area design also makes the core magnetic circuit more uniform, so the magnetic core structure is also Make the core structure design smaller than hot spots.

6. E-type magnetic core  Compared with pot-type magnetic core, E-type magnetic core has lower cost and relatively simple assembly. The shape of the core is widely used now, but the disadvantage is that it cannot provide self-shielding; E-type magnetic core can be installed in different It can also be used in several high-power coverage applications.The core can be made into a flat shape, and planar transformers are now a very popular core shape; a skeleton without pins and pin types can also be provided, because it has very good heat dissipation and can be used in stacks, and is generally used for power inductors and transformers. Core shape.

7. Toroidal cores  For manufacturers, toroidal cores are economical. Among comparable cores, its cost is low; due to the use of the skeleton, the additional and assembly costs are equal to zero; it can be used when appropriate The winding machine performs winding; its shielding is also very good.