Zero-voltage switch flyback-type DC-DC power supply conversion device

Abstract

The invention relates to a DC-DC power supply conversion device, in particular to a zero-voltage switch (ZVS) flyback-type DC-DC power supply conversion device with efficient conversion, efficient light-load conversion and low standby power consumption. An auxiliary switch and an absorption capacitor are additionally arranged on the flyback circuit; the auxiliary switch and the absorption capacitor are connected in series so as to form an auxiliary branch circuit; the auxiliary branch circuit can be connected in parallel to the two ends of the primary winding of a transformer or alternatively connected in parallel to the two ends of a primary-side switch; and the auxiliary switch is conductive for a determined period of time before the primary-side switch is conductive. Compared with the prior art, the energy of the circuit leakage inductor can be absorbed and transferred to the output terminal and a soft switch for realizing the primary-side switch, so that the invention can greatly improve the circuit efficiency; the parasitic oscillation caused by the leakage inductor can be suppressed, so that the EMI (electromagnetic interference) characteristics of the circuit can be improved; and the circuit can be controlled more easily, thereby improving the light-load circuit efficiency and reducing the idle-load energy loss.

Description

technical field [0001] The patent of the present invention relates to a DC / DC power conversion device, especially a zero-voltage switch flyback DC-DC power conversion device with high efficiency conversion, high efficiency conversion under light load and low standby power consumption. Background technique [0002] DC / DC conversion is one of the most basic forms of electrical energy conversion. Due to its simple topology and few components, the flyback converter is widely used in low-power DC / DC conversion, usually below 100-200W. The loss of the flyback converter mainly includes the loss of the primary switch, the loss of the transformer, the loss of the snubber circuit and the loss of the secondary rectifier. These losses are also closely related to the control mode of the flyback converter. [0003] Usually, the transformer of a flyback converter is the main component for storing and transmitting energy. Due to the existence of leakage inductance, a large spike voltage is...

AI Technical Summary

Problems solved by technology

Similarly, when the primary switch is turned off, the leakage inductance of the transformer generates parasitic oscillation in the parallel capacitance Cds of the primary switch. Since there is no external loss resistance, the attenuation of the oscillation depends on the parasitic resistance of the line, and the amplitude and time of the parasitic oscillation are relatively long , leading to poor electromagnetic interference (EMI) performance of the line

Therefore, an additional such as the attached figure 1 RCD clamp snubber circuit shown in, but introduces additional loss

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