Zero-phase startup circuit

Abstract

The invention discloses a zero-phase startup circuit, which comprises an input positive end, an input negative end, an output end, an input sampling circuit, an anti-jitter circuit and a control circuit, wherein the input end of the input sampling circuit is connected with the input positive end and the output negative end of a zero-phase circuit; the output end of the input sampling circuit is connected with the input end of the control circuit and the output end of the anti-jitter circuit; the output end of the control circuit is the output end of the zero-phase startup circuit; the input end of the anti-jitter circuit is connected with the output end of the zero-phase startup circuit; and the output end of the zero-phase startup circuit is connected with a switch control device of an external post-stage circuit. the zero-phase startup circuit is applicable to all input AC power supplies, in particular, power products applied to a power grid environment, the circuit is simple and reliable, the cost is low, the EMC performance is excellent, the design is flexible, and a protection threshold can be adjusted.

Description

technical field [0001] The invention relates to the field of power supplies, in particular to a zero-phase starting circuit used in automatic power supply systems of three-phase four-wire and feeder grids. Background technique [0002] In the switching power supply of the three-phase four-wire power meter and the feeder automation industry, the power supply will be frequently started and shut down. When the high-voltage phase starts, the voltage and current of the grid will exceed the upper voltage limit that the switching power supply can withstand, which will easily cause damage to the switching power supply or even cause a fire, posing a huge safety hazard; [0003] There are mainly two methods for the existing switching power supply to solve the problem of high grid voltage. One is to increase the input overvoltage protection circuit, and the other is to increase the upper limit of the operating voltage range that the power supply can withstand. Among them, the method o...

AI Technical Summary

Problems solved by technology

Among them, the method of increasing the upper limit of the input voltage of the power supply is mainly to use high withstand voltage devices or multi-stage series-parallel methods. And the volume increases, and when the power supply is started at +90° or -270° high phase voltage, the high voltage current will break down the switching device MOS tube in the power module and cause the power supply to explode, which cannot effectively protect the power supply

[0004] In the three-phase four-wire power meter and feeder grid automation industry, the switching power supply on the market today does not provide protection against the above problems. When the power supply starts with a high phase voltage of +90° and -270°, the electrolytic capacitor and the switching tube are often used. Exceeding the standard hard resistance, there is a huge potential safety hazard

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