METHODS AND DEVICES FOR DETECTING THE INPUT VOLTAGE AND DISCHARGING THE RESIDUEVOLTAGE

摘要

The present invention relates to power conversion systems, specifically, it relates to a device for detecting the DC voltage rectified from the AC power supply voltage in an AC-DC converter, primarily used to determine whether the DC input voltage is under a brown-out level and to monitor whether the AC power supply is removed and to discharge the residue DC voltage generated in a high frequency filter capacitor, which is used to filter high frequency noise signals of the AC power supply, during the removal of the AC power.

主权项

1. A device for detecting input voltages and discharging residue voltages, comprising:
a detection unit receiving a rectified DC input voltage, and according to fluctuations of the input voltage, generating a detection voltage signal having different logic levels; a triangle signal generator having a first capacitor, wherein in any one cycle of the input voltage at a moment the detection voltage signal changes from a first state to a second state, the first capacitor begins to charge, and in a following consecutive cycle of said any one cycle at a moment the detection voltage signal changes from the second state to the first state, the first capacitor begins to discharge; a reset signal generator having a second capacitor, wherein the second capacitor charges synchronously with the first capacitor and begins to discharge in the following consecutive cycle at a moment the detection voltage signal changes from the first state to the second state g, wherein the reset signal generator compares a varying voltage of the first capacitor and a varying voltage of the second capacitor and according to a comparison result triggers generation of a reset signal; an AC power removal and brown-out status determination unit comprising a counter, wherein within a preset period when the counter does not receive a first state reset signal and the voltage of the first capacitor is not lower than the voltage of the second capacitor, the AC power removal and brown-out status determination unit generates a brown-out detection signal indicating the input voltage at brown-out status; and when the voltage of the first capacitor is lower than the voltage of the second capacitor within the preset period, the AC power removal and brown-out status determination unit generates a power removal signal indicating the removal of the AC power supply.