MOSFET resonant DC-DC converter circuit diagram with high efficiency

Published:2011/7/27 22:44:00 Author:Nicole | Keyword: DC-DC converter, MOSFET | From:SeekIC

The figure is a MOSFET resonant DC-DC converter circuit. Luo Aiye circuit works through transformer magnetic saturation and make triode fliped. In this circuit, transformer works in nonsaturated mode, it changes with arc through the grid feedback voltage of MOSFET, and to make MOSFET fliped by reducing the grid voltage. When it isconnected to input power supply,VT1 and VT2 are added grid bias by resistors R1 and R2, due to the inhomogeneity of grid voltage UTH (threshold voltage) when MOSFET is conduction, so the lower of UTH turns on firstly. Assuming VTI turns on firstly, there are resonance current flowing between the capacitor C1 and primary coil 2 × Np, it is produced by LC, and C1 is connected to the both ends of transformer primary coil. This current adds resonance voltage to the drain-source of other MOSFET pipe VT2. Since the resonant voltage drops in the grid feedback loop Nf, so it reaches 0V soon. When it is lower than the grid threshold of MOSFET VTl, VTl is off. However, the resonant voltage across OV and reverse negative, the grid of VT2 is positive biased and to be conducted. Of course, the grid voltage of VTl is negative, VTl keeps cut-off state at this time.



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