CN211908646U

CN211908646U - Input surge-proof circuit

Info

Publication number: CN211908646U
Application number: CN202020152848.7U
Authority: CN
Inventors: 马世豪; 马伍新
Original assignee: Hainan Xingyu Intelligent Control Technology Co ltd
Current assignee: Hainan Xingyu Intelligent Control Technology Co ltd
Priority date: 2020-02-05
Filing date: 2020-02-05
Publication date: 2020-11-10
Anticipated expiration: 2030-02-05

Abstract

The utility model provides an input surge protection impact circuit, including input filter circuit, delay circuit and rectifier filter circuit, still including control circuit and sampling circuit, sampling circuit connects between input filter circuit and control circuit, control circuit links to each other with the delay circuit, control circuit is including first comparator U3A and second comparator U3B. Based on the mutual matching between the sampling circuit and the first comparator U3A and the second comparator U3B, the switching power supply can be protected by the slow start circuit when in an abnormal working state (high voltage or low voltage input), and the consumption of the thermistor R4 in the slow start circuit is stopped when in a normal working state, so that the protection performance of the input surge protection circuit is improved.

Description

Input surge-proof circuit

Technical Field

The utility model belongs to the technical field of switching power supply technique and specifically relates to an input surge protection impact circuit.

Background

With the continuous development of power supply technology, the switching power supply has the advantages of small volume, high efficiency and the like, and is widely applied to the fields of computers, industrial control, communication, consumer electronics and the like. Meanwhile, with the increasingly wide application of the switching power supply, the stability and safety of the switching power supply become the problem of further attention and attention of people. The surge often appears when the power is started, abnormally used or struck by lightning, and in order to avoid the damage caused by the surge, the surge-proof circuit is often arranged when the power is designed.

In the prior art, the surge preventing circuit is usually used for reducing inrush current by connecting a thermistor in series at an input end, and reducing consumption of the thermistor during normal operation of the switching power supply by connecting a controllable short circuit in parallel at two ends of the thermistor, so that the reliability of the surge preventing circuit is further improved. However, how to better control the working time of the thermistor and further protect the switching power supply through the anti-surge circuit is a problem to be solved at present.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to overcome prior art not enough, provide an input surge protection impact circuit.

The utility model provides a its technical problem take following technical scheme to realize:

the utility model provides an input surge protection rush circuit, is including input filter circuit, slow circuit and rectifier filter circuit, still including control circuit and sampling circuit, sampling circuit connects between input filter circuit and control circuit, control circuit links to each other with slow circuit, control circuit is including first comparator U3A and second comparator U3B.

Preferably, the output end of the input filter circuit is provided with a first capacitor CX 2.

Preferably, the sampling terminal of the sampling circuit is disposed at two ends of the first capacitor CX 2.

Preferably, the output terminal of the sampling circuit is connected to the non-inverting input terminal of the first comparator U3A and the inverting input terminal of the second comparator U3B, respectively.

Preferably, the inverting input terminal of the first comparator U3A and the non-inverting input terminal of the second comparator U3B are connected to a reference voltage.

Preferably, the slow start circuit comprises a thermistor R4.

Preferably, the control circuit further comprises a switch tube V7 and a relay JK 1; the grid terminal of the switch tube V7 is connected with the output terminal of the first comparator U3A and the output terminal of the second comparator U3B, the relay JK1 comprises a trigger coil and a contact switch, the trigger coil is connected with the drain terminal of the switch tube V7, and the contact switch is connected with the thermistor R4 in parallel.

Preferably, the rectifying and filtering circuit includes a rectifying bridge D3 and a second capacitor CX 3.

The utility model has the advantages that: based on the cooperation between the sampling circuit and the control circuit, the first comparator U3A and the second comparator U3B are used for judging the double standards of the sampling voltage, so that the thermistor R4 is controlled more accurately and more stably, and the effect of protecting the switching power supply when the working state of the switching power supply is abnormal (low voltage or high voltage) is achieved.

Drawings

Fig. 1 is a schematic structural diagram of the present invention;

fig. 2 is a schematic structural diagram of the sampling circuit of the present invention.

Detailed Description

The embodiments of the present invention will be described in detail with reference to the accompanying drawings:

as shown in the figure, the utility model provides an input surge protection impact circuit, including input filter circuit, delay circuit and rectifier filter circuit, still including control circuit and sampling circuit, sampling circuit connects between input filter circuit and control circuit, control circuit links to each other with the circuit that delays, control circuit is including first comparator U3A and second comparator U3B. It is added that the input end of the input filter circuit is connected with an alternating voltage.

Further, as shown in fig. 1 and fig. 2, a first capacitor CX2 is provided at the output end of the input filter circuit.

Further, as shown in fig. 1 and fig. 2, the sampling end of the sampling circuit is disposed at two ends of the first capacitor CX2, and the sampling circuit is configured to sample a voltage at two ends of the first capacitor CX 2.

Further, as shown in fig. 1 and fig. 2, the output terminal of the sampling circuit is connected to the non-inverting input terminal of the first comparator U3A and the inverting input terminal of the second comparator U3B, respectively.

Further, as shown in fig. 1, the inverting input terminal of the first comparator U3A and the non-inverting input terminal of the second comparator U3B are connected with a reference voltage, a first voltage dividing resistor R52 is connected in series between the inverting input terminal of the first comparator U3A and the reference voltage for dividing the voltage, and the inverting input terminal of the first comparator U3A is inputted with the first reference voltage; a second voltage dividing resistor R33 is connected in series between the non-inverting input terminal of the second comparator U3B and the reference voltage for voltage division, and a second reference voltage is input to the inverting input terminal of the second comparator U3B, and it is necessary to supplement that the first reference voltage value is smaller than the second reference voltage.

Specifically, in the utility model discloses an embodiment, judge the required input voltage's of circuit normal work scope according to actual conditions, change the voltage value of first reference voltage and second reference voltage through changing the resistance of first divider resistance R52, second divider resistance R33 for first reference voltage is the minimum input voltage that circuit normal work required, second reference voltage is the required maximum input voltage of circuit normal work.

Further, as shown in fig. 1, the slow-start circuit includes a thermistor R4, and the thermistor R4 is used for reducing the inrush current.

Further, as shown in fig. 1, the control circuit further includes a switching tube V7 and a relay JK 1; the grid terminal of the switch tube V7 is connected with the output terminal of the first comparator U3A and the output terminal of the second comparator U3B, the relay JK1 comprises a trigger coil and a contact switch, the trigger coil is connected with the drain terminal of the switch tube V7, and the contact switch is connected with the thermistor R4 in parallel.

Further, as shown in fig. 1, the rectifying and filtering circuit includes a rectifying bridge D3 and a second capacitor CX 3.

Specifically, in an embodiment of the present invention, when the input voltage is too low, that is, the voltage across the first capacitor CX2 is too low, the output end of the first comparator U3A outputs a low level, the output end of the second comparator U3B outputs a high level, the switching tube V7 is turned off, and the thermistor R4 is in an operating state to protect the circuit; when the input voltage is too high or the alternating current commercial power is suddenly added, because second electric capacity CX 3's instantaneous electric conductivity, first electric capacity CX2 both ends voltage is too high, at this moment, the output high level of first comparator U3A, the output low level of second comparator U3B, switch tube V7 ends, and thermistor R4 is in operating condition and protects the circuit. When the input voltage is normal, the output end of the first comparator U3A and the output end of the second comparator U3B both output high levels, the switch tube V7 is conducted, at the moment, the trigger coil of the relay JK1 connected with the switch tube V7 is conducted, the contact switch is closed, and the thermistor R4 is short-circuited and stops working.

The utility model provides an input surge protection impact circuit's working process as follows:

alternating current mains supply is input from an input end of the input filter circuit, and is output after sequentially passing through the slow start circuit and the rectification filter circuit, the sampling circuit is connected between the input filter circuit and the control circuit, the control circuit is connected with the slow start circuit, the sampling circuit samples the voltage at two ends of a first capacitor CX2 in the input filter circuit, and then the voltage is respectively compared with a first reference voltage and a second reference voltage through a first comparator U3A and a second comparator U3B, after comparison, the first comparator U3A and the second comparator U3B output level to a grid end of a switch tube V7 for driving, when the input voltage is too high or too low, the switch tube V7 is in a cut-off state, and the thermistor R4 works to protect the circuit; when the input voltage is normal, the switch tube V7 is in a conducting state, the thermistor R4 stops working, the temperature of the thermistor is reduced, the resistance value is increased, and the thermistor R4 is started again to work until the voltage fluctuates and deviates from a normal value. Based on the mutual cooperation of the modules, the switching power supply can be protected by the thermistor R4 when in an abnormal working state (high-voltage or low-voltage input), and the thermistor R4 stops being consumed when in a normal working state, so that the protection performance of the input surge-proof circuit is improved.

It should be emphasized that the embodiments described herein are illustrative and not restrictive, and thus the present invention is not limited to the embodiments described in the detailed description, but also falls within the scope of the present invention, in any other embodiments derived by those skilled in the art according to the technical solutions of the present invention.

Claims

1. The utility model provides an input surge protection impact circuit, including input filter circuit, slow start circuit and rectification filter circuit, its characterized in that: the circuit is characterized by further comprising a control circuit and a sampling circuit, wherein the sampling circuit is connected between the input filter circuit and the control circuit, the control circuit is connected with the slow start circuit, and the control circuit comprises a first comparator U3A and a second comparator U3B.

2. The input surge protection circuit of claim 1, wherein: the output end of the input filter circuit is provided with a first capacitor CX 2.

3. The input surge protection circuit of claim 2, wherein: the sampling end of the sampling circuit is arranged at two ends of the first capacitor CX 2.

4. The input surge protection circuit of claim 1, wherein: the output end of the sampling circuit is respectively connected with the non-inverting input end of the first comparator U3A and the inverting input end of the second comparator U3B.

5. The input surge protection circuit of claim 1, wherein: the inverting input end of the first comparator U3A and the non-inverting input end of the second comparator U3B are connected with a reference voltage.

6. The input surge protection circuit of claim 1, wherein: the slow-start circuit comprises a thermistor R4.

7. The input surge protection circuit of claim 6, wherein: the control circuit also comprises a switch tube V7 and a relay JK 1; the grid terminal of the switch tube V7 is connected with the output terminal of the first comparator U3A and the output terminal of the second comparator U3B, the relay JK1 comprises a trigger coil and a contact switch, the trigger coil is connected with the drain terminal of the switch tube V7, and the contact switch is connected with the thermistor R4 in parallel.

8. The input surge protection circuit of claim 1, wherein: the rectifying and filtering circuit comprises a rectifying bridge D3 and a second capacitor CX 3.