A duty-cycle-shifted pulse-width modulation controlled half-bridge zero-voltage
switching DCDC converter has a primary side, a secondary side and a transformer
coupling the primary side to the secondary side. The primary side has first and
second primary switches coupled to a primary winding of the transformer and an
auxiliary branch having one side coupled to a junction of the first and second
primary switches and a second side coupled to common. The auxiliary branch includes
a grounded auxiliary switch that is switched on when one of the first and second
primary switches is on to trap leakage inductance energy of the transformer when
that primary switch is turned off and thereafter switched off to release the trapped
leakage inductance energy to provide a zero voltage switching condition for the
other primary switch. The one of the first and second primary switches that is
on when the auxiliary switch is switched on may be controlled with duty-cycle-shifted
pulse width modulation to provide a zero current switching condition for that primary switch.
