1. Structure: The toroidal transformer is composed of a toroidal magnetic core and two windings directly wound on the magnetic core. The EI transformer consists of an E-shaped and I-shaped magnetic core and two windings that are wound around the core by an insulating sheet.
2. Efficiency: Because the toroidal transformer windings are all surrounded in the magnetic core, the magnetic flux path is short and the magnetic resistance is small, so it has high efficiency. However, the winding of the EI transformer is only partially surrounded by the magnetic core, and the magnetic flux path is longer than that of the toroidal transformer, and the magnetic resistance is larger, so certain energy loss will be generated.
3. Size: Compared with EI transformers, annular transformers are smaller in volume, lighter in weight, and more suitable for space-limited occasions.
4. Sound: Under normal circumstances, because the annular transformer flux path is closed, the noise and vibration generated by the annular transformer are very small. In contrast, the magnetic flux path of the EI transformer is not completely closed, and it is easy to produce buzzing and vibration during operation.
5. Cost: The manufacturing process and material cost of the ring transformer in the production process are high, so the cost is relatively high. EI transformers are relatively cheap.
In summary, annular transformers and EI transformers are different in terms of structural design and performance, and what type of transformer is selected depends on the requirements and constraints of the specific application.