Switch mode power supply transformer - has several windings on magnetic core and gives nonlinear dynamic impedance

摘要

The transformer has a primary winding (22a, 22b) divided: in two sub windings (22a, 22b). The primary winding (22a, 22b) is connected to the switching transistor of the switch-mode power supply unit. It also has a first secondary winding (20) which supplies an operating voltage to the power unit. A second secondary winding (28) gives a power voltage for use by the equipment connected to the power supply unit. The windings (22a, 22b, 20, 28) are wound onto a core (21). The first half (22a) of the primary winding is followed by the operating voltage secondary winding (20), and the second half (22b) of the primary winding, then the power voltage secondary winding (28). Two electrostatic screens (35, 36) separated by an insulating layer (37) are also wounds before winding the power voltage secondary winding (28).