A toroidal transformer (also called a toroidal core transformer or choke) is a transformer that uses a toroidal core, i.e. a "ring-shaped" or "toroidal" core. This design has several advantages over traditional EI type transformers (cores made of a combination of E-shaped and I-shaped pieces):
1. Smaller magnetic leakage: The core of a toroidal transformer is continuous and has no air gaps, which gives them very low magnetic leakage, which reduces interference with surrounding circuits and improves efficiency.
2. High efficiency: Toroidal transformers are more efficient than traditional EI type transformers because the magnetic flux is more concentrated, the magnetic resistance is lower, and they usually have lower iron and copper losses.
3. Smaller size and weight: Due to their high efficiency and compact design, toroidal transformers are usually lighter and smaller than EI type transformers of the same power.
4. Lower radiation: Due to their design, toroidal transformers radiate lower electromagnetic interference (EMI) and do not require additional shielding measures.
5. Good anti-interference performance: The design of toroidal transformers helps to reduce susceptibility to external electromagnetic interference and improve stability.
6. Lower noise levels: Toroidal transformers, due to their continuous core structure, reduce the noise generated by the vibration of the core.
7. Self-demagnetization ability: Due to the continuity of the magnetic circuit, toroidal transformers can use the magnetic material more efficiently, which allows them to eliminate excess flux by themselves.
Despite these advantages, toroidal transformers usually cost slightly more than traditional EI type transformers due to the more complex and expensive manufacturing of toroidal cores. In addition, their winding is more difficult because it must be done through the center of the toroidal core. Despite this, toroidal transformers are still a very popular choice in applications where limited space, high efficiency or low electromagnetic interference are required.