Ring-type transformers are a major type of electronic transformers, featuring high electrical efficiency, iron cores with no air gaps, and a stacking factor that can exceed 95%. They have minimal leakage flux and electromagnetic radiation, small physical dimensions, light weight, variable with the core, very low iron loss, and low iron core temperature rise. They are widely used in household appliances and other high-technology electronic devices with strict technical requirements, primarily serving as power transformers and isolation transformers. Ring-type transformers are already available in a complete series internationally and are widely used in computers, medical equipment, telecommunications, instruments, and lighting.