Importance

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Abstract

The power converter of this invention accomplishes zero voltage switching at both turn on and turn off transitions of four primary switches (220, 224, 228, and 232). A pair of coupled inductors (242 and 244) serve as both energy storage devices and isolation mechanisms. The stored energy in the coupled inductors (242 and 244) is used to drive the resonant transitions. The availability of stored energy in a coupled inductor for driving a switching transition is dependent on the timing of secondary switches (250 and 252) whereby the turn off of the secondary switches is delayed until the transition of the primary switches is complete. The power converter behaves as a pair of interleaved coupled inductor buck converters with oppositely directed magnetizing currents. During a first half cycle, while one inductor is coupled to the output, the other uncoupled inductor behaves as a current source, setting the primary winding currents for both inductors equal to the magnetizing current of the uncoupled inductor. The inductor which is coupled to the output appears as an output filter capacitor or voltage source to the uncoupled inductor during the first half cycle. During the alternate half cycle the roles of the two inductors are reversed. During the transition from one half cycle to the alternate half cycle the states of the secondary switches (250 and 252) are maintained unchanged until the transition has been completed so that the secondary switch transition is delayed with respect to the primary switch transition thereby making available the energy in the uncoupled inductor for driving the switching transition. The secondary switch connected to the uncoupled inductor is maintained open until the switching transition is complete accomplishing a resonant transition.

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First Claim