This paper presents a new soft-switching method for the current-fed full-bridge DC-DC converter that allow zero voltage switching of the input side inverter switches. To achieve this, the secondary side voltage doubler rectifier has to be fulfilled with active switches. Two control channels synchronous with the control signals of the inverter switches are added for driving those switches. Zero voltage switching produce is help with the body diodes that conduct current during soft-switching migrant as a result of the leakage inductance current shaping from the secondary side. Moreover, the converter does not suffer from voltage overshoots thanks to natural clamping from the secondary side. Theoretical guess were verified with simulation.
- Zero-voltage switching
- Current-fed DC-DC converter
- Switching` control method
Fig. 1. Galvanically isolated full-bridge current-fed DC-DC converter with controlled output rectifier stage.
EXPECTED SIMULATION RESULTS:
Fig. 2. Simulated current and voltage waveforms along with control signals of the input and output side switches.
Fig. 3. Experimental current and voltage waveforms.
The novel ZVS method designed for the galvanically isolated full-bridge current-fed DC-DC converter with the controlled output rectifier stage were given. It enables full ZVS in the input side current-fed inverter help with the leakage inductance and body diodes. Moreover, partial ZCS is supply in the secondary side help with the leakage inductance. Simulation study verify the theoretical guess made. Experimental prototype operation was quite similar to the simulation model created in PSIM. Nevertheless, the prototype features oscillations generate by parasitic elements of the circuit and reverse recovery of the body diodes the input side MOSFETs. Further research will be planned towards derivation of design direction that take into account reverse recovery effect and, consequently, result in high efficiency and low parasitic oscillations.
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