I,  What is magnetic material?

We know that most switching power supply transformers are used ferrite cores, the ferrite is a ceramic ferromagnetic material, it is a crystal composed of a mixture of iron oxide and other manganese-zinc oxides. Because of its high electrical resistivity, the eddy current loss of the ferrite is very low. Ferrite cores can be wound into coils to form inductors or transformers, which are widely used in instrumentation, communication equipment and household appliances.

II, How to distinguish different cores?

Ferrite core has many kinds structures, because it is sintered by powder compact, it’s easy to process into various shapes, such as column, I-shaped, hat-shaped, single-hole, double-hole, four-hole, U-shaped, pot-shaped, E-shaped, EI-shaped, EC-shaped, RM-shaped, PQ-shaped, EP-shaped. We are roughly divided into the following categories according to the shape.

Pot type ferrite core

Pot ferrite core has the advantage that the coil on the center column of the bobbin is almost surrounded by ferrite material, which effectively reduces the radiated magnetic field and is suitable for low EMI or RFI applications. The main disadvantage is that the slot is very narrow, so it’s difficult to use a transformer with a large input and output current. Even if the power is low, if the input voltage is high, do not choose the pot core, but it’s suitable for driving signal transformer in the full bridge topology.

EE type ferrite core

EE ferrite core is the most widely used, because there is no restriction on the introduction of the narrow gap introduced by the winding, the coil is not surrounded by ferrite, which is good for heat dissipation. The disadvantage is that it will bring a large EMI-RFI magnetic field. According to the center column, it can be divided into two types: circular and square. The average length of each coil of the former is 11% lower than the latter end, and the coil impedance is also 11% less, so the former has less copper loss and temperature rise than the latter.

RM type ferrite core

RM ferrite core is between the POT type and EE type. It’s more effective than the POT core. It is suitable for high power output power and multi-output power. The EE core has a larger incision for larger size or multiple strands of wire in and out of the coil. It can effectively reduce the core temperature rise.

PQ type ferrite core

PQ ferrite core volume is the best ratio between the surface of the radiation and the winding area of the collecting coil. Since the iron loss is proportional to the core area, the thermal radiation capability is proportional to the radiated surface area, so the temperature rise of the PQ core is minimal for a given output power. In addition, because the ratio of volume to coil winding area is the best, the transformer volume ratio will be the smallest under the same output power, which is more suitable for low power flyback transformers.

UU/UI type ferrite core

UU ferrite core mainly used for high voltage or super high power transformers, rarely used in applications where the power is less than 1KW. Since the winding size is large and the number of turns of the coil is large, the window area of the UU core is larger than that of the EE core having the same core area. However, since the magnetic flux path of the UU core is long and the primary and secondary coupling are not as good as the EE core, the transformer with this type of core has a large leakage inductance.

Ferrite cores of various shapes and sizes are used for inductors and high power supply transformers in high-quality communication markets, pulse transformers, high frequency transformers, and noise filters.

The above classifications come from our production experience, and there are many types cores that are not covered. If you want to know more detailed information, please feel free to contact us. We can manufacture final transformer and inductor for customers.

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