A new zero-voltage-transition PWM buck converter

In this paper a new zero-voltage-transition (ZVT) PWM buck converter is presented. An auxiliary circuit (consisting of one active switch and some reactive components) is added to the original buck converter. The auxiliary circuit is inactive during the ON and OFF intervals of the main switch in the normal buck converter. However, the transitions between the two states are controlled by the auxiliary circuit. Prior to turn-on, the voltage across the active switch in the buck converter is forced to zero. Thus, the turn-on losses of the active switch are practically eliminated. At turn-off the auxiliary circuit behaves like a nondissipative passive snubber, reducing the turn-off losses to a great extent. Zero-voltage-transition switching technique almost eliminates switching losses. The active switch operates under ZVT conditions, the passive switch (diode) has a controlled reverse recovery, and the switch in the auxiliary circuit operates under zero-current-switching (ZCS) conditions.