Three-phase input power supply phase loss detection circuit

Abstract

The invention provides a three-phase input power supply phase loss detection circuit which comprises a signal conversion circuit, a self-locking circuit and an output circuit. The signal conversion circuit is used to convert three-phase power supply input voltage into a level signal. The self-locking circuit is used for locking a high level signal. The output circuit is used for outputting the level signal. The input end of the signal conversion circuit is connected with a three-phase power supply, and the output end is connected with the input end of the self-locking circuit. The output end of the self-locking circuit is connected with the input end of the output circuit. When the three-phase voltage input is normal, the output circuit outputs a low level. If any one of the three-phase voltage of external three-phase alternating current fails or is lost, the output circuit continues to output a high level and latches off. Whether the output level signal detection power supply of the output circuit has phase loss is observed. The three-phase input power supply phase loss detection circuit provided by the invention has the advantages of simple circuit, fast detection, being accurate and reliable, strong anti-interference ability and good application prospect.

Description

technical field [0001] The invention relates to the field of circuit detection, in particular to a phase loss detection circuit of a three-phase input power supply. Background technique [0002] Due to the reasons of the power grid itself or the unreliable power input wiring, the switching power supply sometimes runs with a lack of phase, and the lack of phase operation is not easy to be found. When the power supply is in open-phase operation, one arm of the rectifier bridge has no current, while the other arm will be damaged due to severe overcurrent, and the inverter will work abnormally, so it is necessary to protect the open-phase. [0003] Current transformers or electronic phase loss detection circuits are usually used to detect the lack of phase in the power grid. Due to the high cost and large size of current transformers, electronic phase loss protection circuits are generally used in switching power supplies. However, the general electronic phase loss protection c...

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