Page 120 - Power Quality in Electrical Systems

Switch Mode Power Supplies 103

+
V O
V DC –

(a)
V DC

+

V O
–

(b)
Figure 7.4 Other high-frequency DC/DC converters. (a) The
push-pull converter. (b) The forward converter.
electronics since it can be configured to provide line-frequency power-
factor correction. By properly controlling the high-frequency switch, the
first harmonic of the line current is forced to be sinusoidal and in-phase
with the line voltage, improving power factor to be near 100 percent.
These and other DC/DC converter topologies (including the buck con-
verter, the buck-boost, the Cuk converter, the SEPIC converter, the full-
bridge converter, the forward converter, and the push-pull converter) are
commonly used. The push-pull and forward converters are shown in
Figure 7.4. The push-pull and forward DC/DC converters are used in
medium- to high-power applications. 4

4
In the world of DC/DC converters, “medium- and high-power” applications are gen-
erally in the multiple 100s of watts to kilowatts.