| 摘要 |
The present invention is directed generally to a buck converter that achieves zero voltage switching (ZVS). According to various embodiments, the buck converter comprises a ZVS circuit for storing reverse recovery current from the diode of the buck converter and using the energy from the reverse recovery current to discharge parasitic capacitance of the primary switch of the buck converter prior to turn-on of the primary switch such that the primary switch turns on with substantially zero voltage across the switch. The ZVS circuit may comprise a capacitor, an auxiliary switch connected in series with the capacitor, and an auxiliary inductor connected in parallel with the series-connected capacitor and auxiliary switch. The control circuit controls the primary switch and the auxiliary switch of the ZVS circuit such that (i) the auxiliary switch and the primary switch are not both on at the same time, and (ii) there is a time interval between the end of the on-time of the auxiliary switch and the beginning of the on-time of the primary switch. The time interval (which may be a fixed duration) is of sufficient duration such that the energy from the reverse recovery current substantially discharges the parasitic capacitance of the primary switch during the time interval. Interleaved embodiments of the buck converter are also disclosed.
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