Switch power source and bus capacitor voltage control method used for switch power source

Abstract

The invention provides a switch power source and a bus capacitor voltage control method used for the switch power source. The switch power source includes a rectification unit provided with a DC side and an AC side and used for converting input AC voltage to DC voltage; a bus capacitor; a converter; a monitoring circuit used for detecting whether and judging whether the instant absolute value of the DC voltage is greater than a predetermined voltage; a bus capacitor discharge control circuit used for controlling when the instant absolute value of the DC voltage is greater than predetermined voltage so as to enable the bus capacitor to be charged by the rectification unit to the peak value of the AC voltage and to keep peak value, and controlling the bus capacitor to discharge from the peak value of the AC voltage so as to provide energy to the converter when the instant absolute value of the DC voltage is smaller or equal to predetermined voltage. By adopting the technical scheme provided by the invention, the discharge time of the bus capacitor is reduced and the size of the bus capacitor is reduced, so that the mini size of the switch power source is realized.

Description

technical field [0001] The present application relates to the field of switching power supplies, in particular to a switching power supply with reduced bus capacitance and a bus capacitance voltage control method for the switching power supply. Background technique [0002] figure 1 Schematically shows a circuit block diagram of a known switching power supply, the bus capacitor C_bulk in the switching power supply is connected in parallel with the rectifier bridge 11 and the converter 12 of the subsequent stage, and the bus capacitor C_bulk can be rectified by the voltage rectified by the rectifier bridge 11 Charging can also supply energy to the converter 12 of the subsequent stage. [0003] In recent years, switching power supplies tend to develop in the direction of miniaturization. In order to adapt to this development trend, the switching power supply tends to increase in frequency, and the volume of the magnetic components in the switching power supply (for example, ...

AI Technical Summary

Problems solved by technology

The function of the bus capacitor in the switching power supply is to balance the instantaneous input and output power, so the bus capacitor cannot be miniaturized with the high frequency. As a result, the proportion of the bus capacitor volume in the switching power supply increases with the high frequency. The bigger it becomes, the bottleneck of the miniaturization of the switching power supply

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