Power Sources and Supplies: World Class Designs

of the relative values of the capacitors. The center voltage is now a “ soft ” value that will

depend on the capacitor values and circuit operation. “ Soft ” operation requires that the

coupling capacitor is used to ensure that the transformer does not saturate. The coupling

capacitor has one-half of the input voltage applied and all of the primary current. This will

require an AC capacitor that is rated for the full AC current of the power supply.

Figure 6.20 shows another method of ensuring that the center voltage of the capacitors

stays symmetrical. A second primary winding (balancing winding) with the same number

of turns is connected ...