where d is the duty cycle (the time the upper switch is on relative
to the switching period) and “ ” designates the phasor
representation of the fundamental component.
Although this is the most straightforward approach to ac–ac
power conversion, it is problematic in several respects. First,
each switch must be able to block full primary voltage and also
be capable of conducting full secondary current. The fact that
both the blocking voltage and peak current are large implies that