Control method for improving dynamic performance of power supply and prolonging input power-down retention time

Abstract

The invention relates to a control method for improving the dynamic performance of a power supply and prolonging the input power-down retention time, and the method comprises the following steps: monitoring an input voltage in real time, and obtaining an input voltage sampling signal; judging whether the input end of a power supply is powered down or not according to the input voltage sampling signal; if yes, adjusting switching frequencies of a switching tube of the primary side switching circuit and a switching tube of the secondary side rectifying circuit to stabilize the output voltage; when the switching frequency of the switching tube of the primary side switching circuit and the switching tube of the secondary side rectifying circuit reaches a set value, judging whether the gain needs to be continuously increased or not; if yes, performing intelligent control on a switch tube of the secondary rectification circuit. Intelligent control is carried out through the switch tube of the secondary side rectification circuit, the gain of the resonant converter is improved, the input power failure retention time is prolonged, and in addition, the dynamic performance of a power supply can be improved.

Description

technical field [0001] The invention relates to the technical field of power supplies, more specifically, to a control method for improving the dynamic performance of the power supply and prolonging the hold time of input power failure. Background technique [0002] At present, for the application of isolated DC power supply, most of them adopt the two-stage transformation mode, such as figure 1 shown. The front stage adopts non-isolated conversion from alternating current (AC) to direct current (DC), a typical rectification topology such as PFC (Power factor correction); the latter stage adopts direct current to direct current (DC-DC) due to the danger of high voltage. The isolation conversion topology, such as LLC, phase-shifted full bridge and other typical topologies. Among them, the resonant line topology such as LLC uses an isolation transformer (N1:N2) and a resonant line to control the output voltage by adjusting the frequency. The primary side uses a half-bridge o...

AI Technical Summary

Problems solved by technology

However, the voltage of the input capacitor will gradually decrease with the increase of time after the input is powered off, and a higher gain of the resonant converter K=N1*Vo / (N2*Vin) is required to maintain the stability of the output. At the same time, When the input voltage recovers, the capacitor voltage will have a large mutation, which will cause a large overvoltage of the output voltage

The existing solution is to add a boost circuit behind the input capacitor in the topology, so that the input voltage of the DC-DC converter can still be guaranteed to be stable when the input capacitor voltage is reduced, but this method increases the cost of the converter and increases Large volume, reduced power density

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