Switching power supply safety control system

Abstract

The invention discloses a safety control system for a switching power supply. The safety control system comprises a voltage comparison circuit, a reference voltage selection circuit and a control circuit, the voltage comparison circuit comprises a voltage input module and a comparator, the positive input end of the comparator is connected with an input voltage, the negative input end of the comparator is connected to the output end of the voltage input module, and the input end of the voltage input module is connected with a reference voltage; the reference voltage selection circuit comprises a reversible counter module and a decoder module, and the output end of the reversible counter module is connected with the input end of the decoder module; the control circuit comprises a positive slope detection module, a line removal detection and discharge control circuit module and a timer module, the output end of the positive slope detection module is connected with the line removal detection and discharge control circuit module and the timer module, and the output end of the timer module is connected with the line removal detection and discharge control circuit module. The output end of the discharge control circuit module is connected with the timer module and the positive slope detection module.

Description

technical field [0001] The invention belongs to the technical field of switching power supply control systems, and in particular relates to a switching power supply safety control system. Background technique [0002] The AC-DC switching power supply is a high-frequency power conversion device, and its input is AC power; for its input filter capacitor, the safety agency requires it to discharge after removing the AC line voltage, and there are relevant safety regulations. [0003] The commonly used resistor network discharge scheme will cause a large loss of input power in each mode. The use of active input filter capacitors can effectively reduce the input power loss. The traditional technical solutions generally use capacitors for suppressing power supply electromagnetic interference, and no external discharge resistor network is required. Under normal circumstances, corresponding judgment conditions are required when the capacitor discharges, and the continuous discharge...

AI Technical Summary

Problems solved by technology

Usually, corresponding judgment conditions are required when the capacitor is discharged, and the discharge process continues, which will cause the device temperature to be too high; therefore, there is an urgent need for a solution to effectively detect the condition of removing the AC line, and at the same time discharge the input filter capacitor Periodic control to ensure operator safety and ensure equipment reliability

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