Preceding-stage EMI filtering protective circuit of driving power source

Abstract

The invention discloses a preceding-stage EMI filtering protective circuit of a driving power source. The preceding-stage EMI filtering protective circuit of the driving power source comprises a fuse, a temperature-sensitive resistor, a surge protection circuit, a differential mode interference suppression circuit, a common mode interference suppression circuit and the like. According to the preceding-stage EMI filtering protective circuit of the driving power source, a multi-stage filtering structure is used for carrying out effective filtration and removal on electromagnetic interference signals entering from a power grid, three voltage dependent resistors with different discharge voltage values are used for carrying out discharge protection on surge voltage, and the fuse and the temperature-sensitive resistor are arranged close to a connection port, can carry out disconnection protection when the overcurrent occurs, and achieves the effect of soft start on the whole driving power source. The preceding-stage EMI filtering protective circuit of the driving power source has the advantages of being simple in circuit, small in size, low in cost, good in reliability, high in inserting loss and the like.

Description

technical field [0001] The present invention relates to EMI filtering and anti-surge circuits. Background technique [0002] The driving power supply mostly adopts the switching power supply type, which is small in size and high in efficiency. However, the high-frequency switching action of the switching power supply brings serious electromagnetic interference problems. At the same time, it is necessary to prevent electromagnetic interference from the outside for the stable and reliable operation of the driving power supply. The EMI filter protection circuit can not only effectively prevent the electromagnetic interference from the outside from affecting the internal circuit of the drive power supply, but also prevent the electromagnetic interference of the drive power supply itself from entering the power grid and causing pollution. [0003] Most of the existing drive power supply EMI filter protection circuits adopt too simple one-stage or two-stage filter structure, the i...

AI Technical Summary

Problems solved by technology

[0003] Most of the existing drive power supply EMI filter protection circuits adopt too simple one-stage or two-stage filter structure, the insertion loss value is not large enough, and the filtering effect on electromagnetic interference is not good enough, which leads to the failure of the drive power supply caused by electromagnetic interference and even causes Accidents of other system failures occur frequently. Electromagnetic interference is divided into conduction type and radiation type, and the most important interference is conduction type. An EMI filter with good insertion loss characteristics can solve most of the problems.

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