An input voltage slow-down undervoltage protection circuit and method for a switching power supply

Abstract

The invention discloses an input voltage slow-down undervoltage protection circuit and method for a switching power supply. Voltage sampling circuits are arranged at the front end and back end of the rectification unit of the switching power supply, and the outputs of the two voltage sampling circuits are connected to the slow-down undervoltage protection circuit. The voltage protection logic judgment circuit; the slow down undervoltage protection logic judgment is performed through the output of the slow down undervoltage protection logic judgment circuit. The invention protects the input voltage of the switching power supply when the input voltage is slowly falling and undervoltage through the logic judgment circuit of the slow-down undervoltage protection, which improves the interruption time of the switching power supply, and at the same time avoids the problem of output imbalance when the input voltage slowly drops, and improves the input of the switching power supply. Adaptability, which reduces the probability of logic errors or malfunctions of secondary equipment caused by abnormal input voltage.

Description

technical field [0001] The invention discloses a protection circuit and method for slow-dropping and undervoltage protection of the input voltage of a switching power supply, belonging to the technical field of switching power supply protection. Background technique [0002] The substation secondary equipment DC power supply system consists of battery packs, charging modules, insulation monitoring modules, etc., and provides power for relay protection devices, measurement and control devices, circuit breaker operating circuits, and other various signal circuits. The normal operation of the DC power system is related to the correct operation of relay protection and circuit breakers, which will affect the safe operation of substations and even the entire power grid. [0003] When faults such as grounding and battery aging occur in the DC power supply system, the output voltage may be temporarily interrupted and drop slowly (tens of milliseconds to hundreds of milliseconds), wh...

AI Technical Summary

Problems solved by technology

[0007] In order to solve the problem that the undervoltage protection point setting method of the conventional switching power supply is single and cannot meet the requirements of interruption and slow down at the same time, the present invention proposes a switching power supply input voltage slow down undervoltage protection circuit and method, which can realize under the same working conditions, longest interruption

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