Control circuit for restraining phase shift full-bridge secondary side voltage oscillation

Abstract

The invention discloses a control circuit for restraining phase shift full-bridge secondary side voltage oscillation, the control circuit at least comprises a rectifier bridge, a transformation mechanism, an active clamping drive circuit and an active clamping circuit, wherein the transformation mechanism comprises a resonant inductor Lr and a transformer, and one end of the resonant inductor Lr is connected with the rectifier bridge; a primary side coil Lm of the transformer is connected with the other end of the resonant inductor Lr, a secondary side of the transformer is connected with theactive clamping drive circuit and the active clamping circuit; and the output end of the active clamping drive circuit is connected with the active clamping circuit. Compared with the existing technology, the control circuit for restraining phase shift full-bridge secondary side voltage oscillation, provided by the invention, has the following advantages: reducing circuit cost; being capable of overcoming a problem that the conventional method of adding diode clamping at the primary side only can clamp oscillation generated by an externally added resonant inductor and a rectifier tube junctioncapacitor and cannot restrain oscillation generated by leakage inductance of the transformer and the rectifier tube junction capacitor, eliminating loss of resonant energy on a primary loop and improving system efficiency.

Description

technical field [0001] The invention relates to the field of electricity, in particular to a switching power supply control circuit, in particular to a control circuit for suppressing voltage oscillation at the secondary side of a phase-shifted full bridge. Background technique [0002] Compared with traditional power supplies, switching power supplies have the advantages of small size, light weight, high efficiency, and high operating frequency, so they have received widespread attention and research. In the field of switching power supplies, phase-shifted full-bridge converters are favored by everyone in medium and high-power applications. Among them, the leakage inductance of the transformer can be used as the resonance generated by the resonant inductor and the parasitic capacitance of the power tube, which can realize the zero-voltage switching of the switch tube, and effectively improve the conversion efficiency of the phase-shifted full-bridge topology. [0003] Howe...

AI Technical Summary

Problems solved by technology

[0004] However, the method of adding a clamping diode on the primary side can only be applied to a topology with a separate resonant inductor, not suitable for a topology where the resonant inductor is integrated with the main transformer, and there is a loss of duty cycle and narrowing of the soft switching range , the circulation loss caused by clamping diodes on the primary side, etc., affects the improvement of the efficiency of the phase-shifted full-bridge topology

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