Patent attributes
A zero voltage switching (ZVS) technique for use in isolated and non-isolated switching power converters and regulators, e.g. based upon buck, boost, buck-boost, and double-clamped topologies is disclosed. During a reverse energy phase of the converter operating cycle, energy is transferred in reverse from the load or the clamp capacitor to the inductor, allowing the current in the inductor to increase in magnitude with a reverse polarity, building up reverse energy. The reverse energy may be used for charging and discharging parasitic and other circuit capacitances for ZVS. The reverse energy phase is adjusted based upon circuit operating conditions, so that the amount of energy stored in the inductor L at the end of the reverse energy phase is approximately equal to, but preferably no greater than, that required to turn the switches ON at substantially zero voltage. Thus full ZVS may be achieved under a wide variety of operating conditions without incurring unnecessary losses. The reverse energy phase may be adjusted on the fly in response to changing operating conditions, e.g. using feedback control, or a look-up table. Alternatively, the reverse energy phase may be factory or field programmed for operation under specific conditions.
