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Resonant Switching Converter

IP.com Disclosure Number: IPCOM000050257D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Patterson, BE: AUTHOR

Abstract

In the resonant switching power converter circuit shown in the figure, the primary windings of inductors L1 and L2, together with capacitor C1, form two resonant circuits. The secondary windings of L1S and L2S serve as flyback windings to deliver energy to the load. Multiple switching transistors Q1-Q4, driven by external pulses, serve as a switch to develop the resonant currents through L1P and L2P. Transformer T1 provides current feedback for Q1-Q4.

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Resonant Switching Converter

In the resonant switching power converter circuit shown in the figure, the primary windings of inductors L1 and L2, together with capacitor C1, form two resonant circuits. The secondary windings of L1S and L2S serve as flyback windings to deliver energy to the load. Multiple switching transistors Q1-Q4, driven by external pulses, serve as a switch to develop the resonant currents through L1P and L2P. Transformer T1 provides current feedback for Q1-Q4.

The circuit operation begins by assuming that the input voltage, Vin, has been applied and capacitor C1 is charged to Vc max. When transistors Q1-Q4 are turned on, the energy stored in C1 is fed through inductor L2P. As C1-L2P form a resonant circuit, the current i2 through L2P is sinusoidal in nature and then decays toward zero. During the decay portion of i2, energy is delivered to the load, via a flyback action, and to C1. The energy returned to C1 charges C1 in the reverse sense.

When the capacitor voltage decays below the input voltage, diode D1 becomes forward biased and current il begins to flow in inductor LiP. However, because of the phase of Vc relative to i2 and from design considerations, L1P is delayed approximately 90 degrees behind i2. During the sinusoidal rise of i1, C1 is placed under the influence of both the decaying portion of i2 and rising i1. At the time when i2 has decayed to approximately zero, the two influences cancel and Vc reaches a maximum. After peaking, i1...