Low cost input anti-overvoltage protection circuit

An overvoltage protection circuit, a low-cost technology, applied in the field of circuits, can solve the problems of increased circuit cost and volume, inability to protect subsequent circuits, short overvoltage working time, etc., to achieve adjustable overvoltage protection threshold and EMC performance Superior, simple and reliable circuit effect

Active Publication Date: 2018-06-26
MORNSUN GUANGZHOU SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Among them, increasing the upper limit of the input voltage is mainly to use high withstand voltage devices or multi-stage series-parallel connection. The advantage is that the circuit can still work normally when the overvoltage occurs. The cost of the capacitor has increased by about four times, the cost of the switch tube has increased by more than two times, and the overvoltage working time is very short. This method has serious overdesign and wastes resources; another method is to increase the input overvoltage protection circuit. When the grid voltage is too high, the control chip will stop working. This method can only be used in the case of small overvoltage. W

Method used

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  • Low cost input anti-overvoltage protection circuit

Examples

Experimental program
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Effect test

no. 1 example

[0044] figure 2 It is the schematic diagram of the input chopper circuit of the first embodiment of the present invention, including: capacitor C801, rectifier bridge DB801, capacitor C802, varistor RV803, N-channel MOS transistor TR808 and energy storage capacitor C805.

[0045] Capacitors C801 and C802 are safety capacitors, and the Vds of N-channel MOS transistor TR808 is recommended to be above 650V.

[0046] Both ends of the safety capacitor C801 are connected to the L and N terminals of the front-end EMC filter circuit, and are respectively connected to the two AC input terminals of the rectifier bridge DB801: the first input terminal and the second input terminal, and the source of the MOS transistor TR808 (S ) is connected to the negative pole of the rectifier bridge DB801, the drain (D) of TR808 is connected to the negative pole of the energy storage capacitor C805, and connected to one end of RV803 and C802, and the other end of the piezoresistor RV803 is connected ...

no. 2 example

[0059] Figure 4 It is the schematic diagram of the input chopper circuit in the second embodiment of the present invention. The difference from the first embodiment is that the N-channel MOS transistor TR808 is changed to the P-channel MOS transistor TR809, and the connection relationship is adjusted as follows: TR809 The gate of TR809 is connected to the control signal Vg output by the control circuit, the source of TR809 is connected to the positive pole of rectifier bridge DB801, and the drain of TR809 is connected to the positive pole of energy storage capacitor C805. Both ends of RV803 are connected in parallel between source and drain of TR809. The connection relationship of other components remains unchanged. At the same time, the control circuit is properly adjusted and isolated.

[0060] The working principle of the adjusted circuit is the same as that of the first embodiment, and the same effect can be realized.

no. 3 example

[0062] Figure 5 to Figure 8 It is the schematic diagram of the input chopper circuit in the third embodiment of the present invention. The difference from the first embodiment is that the MOS tube TR808 is changed to a relay TR810, and the connection mode of the relay is one of the following four types:

[0063] The first type: the first control terminal of the relay is connected to the control signal Vg output by the control circuit, the second control terminal of the relay is connected to the signal ground of the control circuit, the first switch terminal of the relay is connected to the negative pole of the rectifier bridge DB801, and the second switch of the relay The terminal is connected to the negative pole of the energy storage capacitor C805; the two ends of the RV803 are respectively connected to the first switch terminal and the second switch terminal of the relay.

[0064] The second type: the first control terminal of the relay is connected to the control signal Vg...

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Abstract

The invention discloses a low-cost input anti-overvoltage protection circuit capable of real-time monitoring the magnitude of an AC input voltage and controlling on-off of a switching device in a chopper circuit through a control circuit. When the AC input voltage is increased abnormally, the control circuit can quickly detect and control the switching device in the chopper circuit to be in the on-of state, maintain the energy storage capacitor voltage, so as to quickly and effectively protect a back stage circuit, prevent an energy storage capacitor and a switch tube of the back stage circuitfrom being damaged due to high voltage, and the back stage circuit can continue to work normally. Compared with the prior art, the anti-overvoltage protection circuit of the invention is applicable to the situation and the condition that the power network voltage abnormal overvoltage can occur caused by a grounding fault, and the like, the reaction speed is high, the circuit is simple and reliable, the cost is low, the EMC performance is excellent, the design is flexible, and the protective valve value can be adjusted.

Description

technical field [0001] The invention relates to the field of circuits, in particular to an input anti-overvoltage protection circuit used in a three-phase four-wire and feeder network automatic power supply system. Background technique [0002] In the three-phase four-wire power meter and switching power supply in the feeder automation industry, problems such as ground faults and high-power equipment interference are often encountered, resulting in abnormally high grid voltage for a period of time. At this time, the grid voltage will exceed the switching power supply. The upper limit of the withstand voltage can 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 p...

Claims

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Application Information

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IPC IPC(8): H02H9/04H02M1/32H02M1/44H02M3/156H02H1/00
CPCH02H1/0007H02H9/045H02M1/32H02M1/44H02M3/156H02M1/325H02H9/04H02M7/06H02M7/217
Inventor 罗皓宋建峰程志勇
Owner MORNSUN GUANGZHOU SCI & TECH
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