The procedure of the magnetization and phenomenon of magnetic bias in output transformer of high-power ultrasonic cleaning equipment are derived theoretically, the main factors and the reasons of magnetic bias are analyzed by drawing a lot of diagrams including magnetization characteristic, exciting current and magnetic flux. Some methods to eliminate magnetic bias are proposed. Through choosing the MnZn ferrite core material, circuit balance and electrical isolation, the magnetic bias will be rejected, the results show that exciting current is greatly reduced and magnetic bias is vanished. Furthermore, the equipments have stable working temperature and performance. The conversion efficiency is higher than 85%.

ultrasonic cleaning; output transformer; bias magnetization; magnetic saturation