Circuit for realizing AC input voltage limiting by means of switch mode

Abstract

The invention discloses a circuit for realizing AC input voltage limiting by means of a switch mode. The circuit comprises an input circuit module, a rectifier circuit module, a comparison circuit module, a field effect transistor drive circuit module, a switch circuit module and an output circuit module, wherein the input circuit module inputs the AC input voltage, and outputs the AC input voltage to the comparison circuit module after rectification of the rectifier circuit module, and then eventually outputs the AC input voltage through the output circuit module; the field effect transistor drive circuit module and the switch circuit module are connected to a power supply loop between the comparison circuit module and an output end line module; the comparison circuit module is provided with a voltage comparison function by means of setting of a voltage-regulator tube; a voltage signal being less than a voltage comparison threshold value can switch on a load power supply loop; and a voltage signal being greater than the voltage comparison threshold value enables the comparison circuit module to output a switch-on signal so as to drive on / off of MOS switch tubes which are connected with an original power supply loop in serial and to disconnect the power supply loop. The circuit for realizing AC input voltage limiting by means of a switch mode has the advantages of being small in volume, being high in efficiency, being low in caloric power, and being very low in cost.

Description

technical field [0001] The invention relates to the technical field of electrification control and protection equipment at the back stage of protection, in particular to a circuit for realizing AC input voltage limitation by means of a switch, which is used in photovoltaic, rail transit and other occasions where the AC power supply fluctuates greatly. Background technique [0002] In the application of photovoltaic system, when the low-voltage side switch of the box transformer is tripped, the electrification control and protection equipment in the photovoltaic area is powered by the photovoltaic inverter at this moment. However, due to the sudden operation of the photovoltaic inverter in island mode, the output AC will instantly rise to 450VAC for 3 cycles, thereby breaking down the power supply input circuit of the electrified control and protection equipment, causing equipment damage and economic losses, and making the photovoltaic system Run out of protection. [0003] ...

AI Technical Summary

Problems solved by technology

However, due to the sudden operation of the photovoltaic inverter in island mode, the output AC will instantly rise to 450VAC for 3 cycles, thereby breaking down the power supply input circuit of the electrified control and protection equipment, causing equipment damage and economic losses, and making the photovoltaic system run out of protection

[0003] In rail transit applications, electrification control and protection equipment is powered by the mains. In some applications, when the design of the box transformer transformer is unreasonable, the fluctuation of the primary voltage due to load changes will directly affect the secondary voltage, and the secondary voltage will rise to about 320VAC. , lasting about 30 minutes, long-term overvoltage operation will break down the power supply input circuit of the electrification control protection equipment, causing equipment damage and economic losses, and making the rail transit system run out of protection

[0004] The conventional protection method is to incorporate a silicon chain at the front end of the electrified control and protection equipment, and limit the input voltage through the linear voltage stabilization method of the silicon chain. The disadvantages are large size, low efficiency, severe heat generation, and high cost

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