It is observed
from
Fig.
5
that
regardless of the switching
frequency,
because the on-time
of
the
active power switches
is
equal
to
one-half of
the
resonant period, the active power
switches always tum-off
when
the
resonant current
is equal
to
zero. Furthemiore, certain frequencies
a1 low
zero current
turn-on
of the switches.
In
the
case
of
low
target output
voltages or
light
loads,
the switching frequencies may
be low
enough
to
allow
a
discontinuous current
so
the switches tum
on
at zero current transie