High-voltage protection device of three-phase input switching power supply

Abstract

The invention discloses a high-voltage protection device of a three-phase input switching power supply. The device comprises two main relays, two starting resistors, an alternating-current input voltage detection and rectified direct-current voltage detection and control circuit and an auxiliary relay circuit, wherein a normally open contact is connected in series in each of the two starting resistors by the auxiliary relay circuit; and each auxiliary relay circuit comprises an auxiliary relay and a positive temperature coefficient (PTC) resistor. According to the invention, through perfect protection of alternating current input high voltage and rectified direct current high voltage, the reliability problem caused by lightning stroke, surge and other abnormalities can be significantly reduced, and the reliability of the charging pile module is significantly improved; and as the PTC is connected in series in the starting resistors, fault isolation under abnormal damage can be further realized, and the reliability is further improved.

Description

[technical field] [0001] The invention relates to the technical fields of three-phase AC input slow start, AC input high voltage protection and DC high voltage protection in switching power supplies, and more specifically relates to a three-phase AC input slow start, AC high voltage and DC high voltage protection device. [Background technique] [0002] At present, for charging pile modules with three-phase AC input in the industry, the three-phase AC input slow start circuit is usually as follows: figure 1 As shown, a relay is connected in series in any two-phase input line of the three-phase input phase A, phase B and phase C, and a resistor is connected in parallel to the main contact of each relay. The rectifier filter capacitor is charged later, so that the auxiliary power supply and control circuit connected to the output filter capacitor are normally powered on and started, and the relays K1 and K2 are closed at the same time at the appropriate time to realize the norm...

AI Technical Summary

Problems solved by technology

[0003] like figure 1 In the slow start circuit shown, when abnormal high voltage is caused by lightning strike, surge or other reasons in the three-phase input A phase, B phase and C phase, the high voltage will jump into the rectified capacitor, although it can be detected by AC input voltage or The voltage on the capacitor after rectification detects abnormal high voltage, which can be used for abnormal shutdown protection and alarm, but this circuit cannot cut off the connection with the input, and cannot control the voltage on the capacitor after rectification within the allowable range, and there may be damage to the power tube or electrolytic capacitor after rectification There have been specific cases of damage due to high voltage in engineering operation; in addition, in engineering operation, such as relay failure or subsequent stage circuit failure, starting resistor R1 or R2 or due to excessive power, it is easy to cause starting resistance (generally Cement resistance) PCB carbonization damage due to overheating or lead to further expansion of failure

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