Zero-voltage switch forward direct-current direct-current converter and control method thereof

Abstract

The invention discloses a zero-voltage switch forward direct-current direct-current converter which comprises a functional module M, an output isolation transformer, a primary side MOS transistor Q1 and an MOS transistor Q2; the output isolation transformer comprises a primary winding Np, a secondary winding Ns and a reset winding Nt, and the output isolation transformer is provided with an excitation inductor Lm; and the functional module M has the following two functions: one function is to control the conduction and cutoff of the primary side MOS transistor Q1, and the other function is tocontrol the conduction and cutoff of the MOS transistor Q2 according to the change of the resonance reset current or voltage. The invention further discloses a control method of the zero-voltage switch forward direct-current direct-current converter. No matter whether the output current is in an interrupted mode or a continuous mode, the output isolation transformer can be reset in a resonance mode.

Description

technical field [0001] The invention relates to a zero-voltage switch forward DC-DC converter and a control scheme thereof. Background technique [0002] In the flyback DC-DC converter, due to the effect of the output voltage, its isolation output transformer automatically completes the reset function, while in the forward DC-DC converter, it lacks the reset function of its isolation output transformer, and it needs to provide additional circuitry to help with reset. There are currently several reset methods that can be used, such as RCD circuits, reset windings, active degaussing resets, and resonant resets. Among them, the active degaussing reset and resonance reset can make the isolated output transformer work in the first and third quadrants. This is beneficial to further reduce the volume of the isolation output transformer. [0003] Active degauss reset (eg figure 1 shown) can also make the forward converter work in the zero-voltage switching (ZVS) conduction mode ...

AI Technical Summary

Problems solved by technology

[0005] Under the condition of discontinuous current mode, if the freewheeling duration of the output inductor current is less than the resonant reset time, the isolated output transformer cannot effectively resonantly reset due to the open circuit of the freewheeling diode D2

When the output current of the forward DC-DC converter is required to vary in a wide range, the forward DC-DC converter will inevitably work in the discontinuous current mode, and this resonant reset method cannot effectively ensure the isolated output Transformer Resonant Reset

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