Rapid detection circuit for power failure of main power supply

Abstract

The utility model relates to a main power failure rapid detection circuit comprising a power failure sampling circuit connected with an input voltage, and a switching power supply input large electrolytic voltage sampling circuit connected with a switching power supply input large electrolytic voltage. The output end of the power-down sampling circuit and the output end of the switching power supply input large electrolytic voltage sampling circuit are both connected with the driving circuit, and the reference voltage circuit is connected with the power-down sampling circuit and the switching power supply input large electrolytic voltage sampling circuit. When the voltage sampling value of the power-down sampling circuit and the voltage sampling value of the switching power supply input large electrolytic voltage sampling circuit are lower than the output value of the reference voltage circuit, a high level is output to drive the drive circuit to be switched on, and the drive circuit is connected with the signal processing circuit and feeds back a comparison value to the MCU for processing. When the main alternating current voltage drops, the voltage of the input large electrolysis also drops, at the moment, the output pin of the operational amplifier can quickly output high level, and the AC power failure state is quickly transmitted to the secondary stage through the optocoupler to be processed, so that the standby power supply can be quickly switched.

Description

Technical Field

[0001] The utility model relates to the field of main power loss rapid detection circuits, and particularly to a main power loss rapid detection circuit. Background Art

[0002] In the traditional switch power supply AC power loss detection circuit, due to the existence of the X capacitor, the detection signal lags behind the voltage drop; when applied to the fire protection industry, due to the lag of the detection signal, the standby power supply switching response time is too long, resulting in the total power output drop, causing the subsequent equipment to reset and restart, resulting in unpredictable risks. Summary of the Utility Model

[0003] The technical problem to be solved by the utility model is that the detection signal of the traditional switch power supply AC power loss detection circuit lags behind the voltage drop, resulting in too long standby power supply switching response time, leading to the total power output drop, causing the subsequent equipment to reset and restart, and easily causing unpredictable risks. In view of the above defects of the prior art, a main power loss rapid detection circuit is provided.

[0004] In order to solve the above technical problems, the technical solution adopted by the utility model is as follows:

[0005] Construct a main power loss rapid detection circuit, including a power loss sampling circuit connected to the input voltage, and a large electrolytic voltage sampling circuit of the switch power supply input connected to the large electrolytic voltage of the switch power supply input. The output ends of the power loss sampling circuit and the large electrolytic voltage sampling circuit of the switch power supply input are both connected to the drive circuit. The detection circuit further includes a reference voltage circuit connected to the power loss sampling circuit and the large electrolytic voltage sampling circuit of the switch power supply input. When the voltage sampling values of the power loss sampling circuit and the large electrolytic voltage sampling circuit of the switch power supply input are lower than the output value of the reference voltage circuit, a high level is output to drive the drive circuit to conduct. The drive circuit is connected to the signal processing circuit and feeds back the comparison value to the MCU for processing.

[0006] Preferably, the power loss sampling circuit includes a rectification module connected to the input voltage, a voltage division module and a filtering module connected to the rectification module. The filtering module is connected to the comparator module, and the comparator module is connected to the reference voltage module. By comparing the input voltage of the comparator module with the voltage value of the reference voltage point of the reference voltage circuit, the output of the comparator module is driven.

[0007] Preferably, the rectification module includes multiple groups of diodes arranged in parallel, the voltage division module includes multiple groups of resistors arranged in series and / or in parallel, the filtering module includes multiple groups of capacitors arranged in parallel, the comparator module is an operational amplifier, the first end of the operational amplifier is connected to the filtering module through a sampling resistor, the second end is connected to the reference voltage circuit, and the output end is connected to the drive circuit.

[0008] Preferably, the switching power supply input large electrolytic voltage sampling circuit includes a voltage dividing module connected to the switching power supply input large electrolytic voltage for sampling, and a filtering module connected to the voltage dividing module. The filtering module is connected to a comparator module, and the comparator module is connected to a reference voltage module. By comparing the input voltage of the comparator module with the voltage value of the reference voltage point of the reference voltage circuit, the comparator module is driven to output.

[0009] Preferably, the voltage dividing module includes multiple groups of resistors arranged in series and / or in parallel. The filtering module includes multiple groups of capacitors arranged in parallel. The comparator module is an operational amplifier. The first end of the operational amplifier is connected to the filtering module through a sampling resistor, the second end is connected to the reference voltage circuit, and the output end is connected to a driving circuit.

[0010] Preferably, a hysteresis comparator is connected between the output end and the second end of the operational amplifier.

[0011] Preferably, the hysteresis comparator includes a diode and a resistor arranged in series.

[0012] Preferably, the reference voltage circuit includes a zener diode. The cathode of the zener diode is connected to a capacitor through a resistor, and the cathode voltage value is the voltage of the reference voltage point. The anode is connected to the reference voltage point through a capacitor and the anode is grounded.

[0013] Preferably, the driving circuit includes two groups of diodes. The anodes of the two groups of diodes are respectively connected to the power-off sampling circuit and the switching power supply input large electrolytic voltage sampling circuit, and the cathodes are connected to each other and connected to the signal transmission circuit.

[0014] Preferably, the signal processing circuit includes a triode connected to the driving circuit. The emitter and collector of the triode are connected to the primary end of an optocoupler, and the secondary end is connected to an MCU.

[0015] The beneficial effects of the present utility model are as follows: Through the input AC voltage undervoltage or power-off sampling circuit, the switching power supply input large electrolytic voltage sampling circuit, and the signal processing circuit. When the main power AC voltage drops, it will cause the voltage of the input large electrolytic to also drop. At this time, the 1st pin and the 7th pin of the operational amplifier will quickly output a high level, and the state of AC power-off will be quickly transmitted to the secondary through the optocoupler for processing, so as to realize the quick switching of the backup power supply. At the same time, multiple groups of resistors are set for voltage division to avoid damage to the circuit due to too high an AC input voltage value. A hysteresis comparator module is connected to the operational amplifier to prevent unstable output of the high level caused by voltage fluctuation at the sampling point voltage. Description of the Drawings

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will further explain the present invention in conjunction with the accompanying drawings and embodiments. The accompanying drawings in the following description are only partial embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings:

[0017] Figure 1 Schematic diagram of the principle of the power-down fast detection circuit of the preferred embodiment of the present invention;

[0018] Figure 2 Schematic diagram of the principle of the power-down adoption circuit of the preferred embodiment of the present invention;

[0019] Figure 3 Schematic diagram of the principle of the switching power supply input large electrolytic voltage sampling circuit of the preferred embodiment of the present invention;

[0020] Figure 4 Circuit diagram of the power-down fast detection circuit of the preferred embodiment of the present invention. Detailed implementation manners

[0021] In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are partial embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0022] A main power-down fast detection circuit of the preferred embodiment of the present invention; as Figure 1 shown, it includes a power-down sampling circuit 10 connected to the input voltage, which is compared with a reference voltage circuit 20 through the power-down sampling circuit. When the sampling voltage of the power-down sampling circuit is lower than the voltage of the reference voltage circuit, a high level is input to drive the drive circuit 40 to conduct, and the electrical signal is transmitted to the signal processing circuit 50 through the drive circuit and then the voltage is output. It also includes a switching power supply input large electrolytic voltage sampling circuit 30 connected to the switching power supply input large electrolytic voltage, which is compared with the reference voltage circuit 20 through the switching power supply input large electrolytic voltage sampling circuit. When the sampling voltage of the switching power supply input large electrolytic voltage sampling circuit is lower than the voltage of the reference voltage circuit, a high level is input to drive the drive circuit 40 to conduct, and the electrical signal is transmitted to the signal processing circuit 50 through the drive circuit and then the voltage is output. The signal processing circuit quickly transmits the power-down state to the MCU for processing, thereby realizing the rapid switching of the backup power supply.

[0023] Specifically, as Figure 2As shown, the power-down sampling circuit 10 (which can also be referred to as the input AC voltage undervoltage circuit) includes a rectification module 100 connected to the input voltage. After rectifying the input voltage through the rectification module, it is transmitted to the voltage division module 101. The voltage division module reduces the input AC voltage and then transmits it to the filtering module 102 for filtering, and then passes it to the comparator module 103. The comparator module compares the filtered voltage sampling value with the voltage value of the reference voltage circuit. When the sampled voltage of the sampling value is lower than the reference voltage value, the comparator outputs a high level and drives the drive circuit 40 to conduct for subsequent electrical signal transmission.

[0024] Furthermore, as Figure 3 shown, the switching power supply input large electrolytic voltage sampling circuit 30 includes a voltage division module 200 connected to the switching power supply input large electrolytic voltage. After filtering the voltage through the filtering module 201, it is transmitted to the comparator module 202. The comparator module compares the filtered voltage sampling value with the voltage value of the reference and reference voltage circuit. When the sampled voltage of the sampling value is lower than the reference voltage value, the comparator outputs a high level and drives the drive circuit 40 to conduct for subsequent electrical signal transmission.

[0025] Furthermore, as Figure 4 shown, the reference voltage circuit 20 includes a fifteenth resistor R15 connected to the power supply. The other end of the fifteenth resistor R15 is connected to the cathode of the first voltage stabilizing diode U1. The anode of the first voltage stabilizing diode U1 is grounded, and the anode is connected to the reference voltage point VREF1 through the fifth capacitor C5, and the cathode is directly connected to the reference voltage point VREF1. The voltage value of the reference voltage point VREF1 is compared with the voltage sampling value. In the present invention, the voltage value of the reference voltage point is 2.5V. Therefore, when the voltage sampling value of the power-down sampling circuit or the switching power supply input large electrolytic voltage sampling circuit is lower than 2.5V, a high level is output to make the drive circuit conduct.

[0026] Furthermore, as Figure 4As shown in the figure, the rectification module 100 includes a fourth diode D4 and a fifth diode D5 connected to both ends of the alternating current. The fourth diode and the fifth diode are connected in parallel and are both connected to the voltage division module 102. The voltage division module includes a seventeenth resistor R17, an eighteenth resistor R18, and a twentieth resistor 20 connected in series, and a twenty-fourth resistor R24, a twenty-seventh resistor R27, and a twenty-eighth resistor R28 connected to the twentieth resistor. The twenty-fourth resistor, the twenty-seventh resistor, and the twenty-eighth resistor are connected in parallel. One end of the twentieth resistor is connected to the filtering module 103. The filtering module includes a sixth capacitor C6, a seventh capacitor C7, and an eighth capacitor C8 connected in parallel. After filtering the voltage through three groups of capacitors, the electrical signal is transmitted to the sampling resistor R22 and then to the second pin of the second operational amplifier U2A. The third pin of the second operational amplifier is connected to the reference voltage circuit to compare the voltage value of the sampling resistor R22 with the voltage of the reference voltage point VREF1. When the voltage of the sampling resistor is lower than the voltage of the reference voltage point, the first pin of the second operational amplifier outputs a high level and is then transmitted to the drive circuit. When driving the eleventh diode, the ninth triode is turned on, and then the optocoupler U5A is driven, and the main power-off signal or undervoltage signal is quickly transmitted to the MCU through the optocoupler, and the MCU processes it again. In order to prevent the high level from being unstable due to the voltage fluctuation at the sampling point, a hysteresis comparator formed by connecting the eighth diode D8 and the thirty-fifth resistor R35 in series is connected between the first pin and the third pin of the second operational amplifier U2A, and the sampling value is more stable.

[0027] Further, as Figure 4 shown, the voltage division module 200 includes a fiftieth resistor R50, a fifty-first resistor R51, and a fifty-second resistor R52 connected in series. The other end of the fiftieth resistor is connected to a sixty-first resistor R61 and a sixty-second resistor R62 connected in parallel to achieve voltage division, and is subjected to old filtering with a twenty-fourth capacitor C24. One end of the twenty-fourth capacitor is connected to the fiftieth resistor, and the other end is grounded. After filtering the voltage through the filtering module, the electrical signal is transmitted to the sampling resistor R54 and then to the sixth pin of the second operational amplifier U2B. The fifth pin of the second operational amplifier is connected to the reference voltage circuit to compare the voltage value of the sampling resistor R54 with the voltage of the reference voltage point VREF1. When the voltage of the sampling resistor is lower than the voltage of the reference voltage point, the seventh pin of the second operational amplifier outputs a high level and is then transmitted to the drive circuit. In order to prevent the high level from being unstable due to the voltage fluctuation at the sampling point, a hysteresis comparator formed by connecting the thirteenth diode D13 and the sixty-sixth resistor R66 in series is connected between the seventh pin and the fifth pin of the second operational amplifier U2B, and the sampling value is more stable.

[0028] Further, as Figure 4As shown, the drive circuit 40 includes the eleventh and twelfth diodes D11, which adopt two groups of diodes. The anodes of the two groups of diodes are respectively connected to the output terminals of the second comparator U2A and the second comparator U2B. The cathodes of the two groups of diodes are connected to each other and then connected to the signal processing circuit 50. The signal processing circuit is connected to the drive circuit through the seventy-first resistor R71 to input the output electrical signal of the drive circuit, and is connected to the base of the ninth triode Q9. The collector of the ninth triode is connected to the power supply through the sixty-eighth resistor R68, and is connected to one end of the primary of the fifth drive optocoupler U5 through the seventy-ninth resistor R79. The emitter of the ninth triode is connected to the other end of the primary of the fifth drive optocoupler U5, and the emitter of the ninth triode is grounded, and the base is grounded through the seventy-second resistor R72. The secondary of the fifth drive optocoupler U5 is connected to the control terminal of the MCU. In this way, the signal of the main power failure or voltage drop is quickly transmitted to the MCU through the optocoupler, and the MCU processes it, so as to realize the quick switching of the backup power supply.

[0029] It should be understood that the present invention is described through some embodiments. Those skilled in the art know that without departing from the spirit and scope of the present invention, various changes or equivalent replacements can be made to these features and embodiments. In addition, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A main power failure fast detection circuit, comprising a power failure sampling circuit connected to an input voltage, and a switching power supply input large electrolysis voltage sampling circuit connected to a switching power supply input large electrolysis voltage, wherein the output ends of the power failure sampling circuit and the switching power supply input large electrolysis voltage sampling circuit are both connected to a driving circuit, characterized in that: The detection circuit also includes a reference voltage circuit connected to the power-off sampling circuit and the switching power supply input large electrolytic voltage sampling circuit. When the voltage sampling values ​​of the power-off sampling circuit and the switching power supply input large electrolytic voltage sampling circuit are lower than the output value of the reference voltage circuit, a high level is output to drive the driving circuit to turn on. The driving circuit is connected to the signal processing circuit and feeds back the comparison value to the MCU for processing.

2. The detection circuit according to claim 1, characterized in that: The power-off sampling circuit includes a rectifier module connected to the input voltage, and a voltage divider module and a filter module connected to the rectifier module. The filter module is connected to the comparator module, and the comparator module is connected to the reference voltage module. The comparator module output is driven by comparing the input voltage of the comparator module with the voltage value of the reference voltage point of the reference voltage circuit.

3. The detection circuit according to claim 2, characterized in that: The rectifier module includes multiple groups of diodes arranged in parallel, the voltage divider module includes multiple groups of resistors arranged in series and / or in parallel, the filter module includes multiple groups of capacitors arranged in parallel, and the comparator module is an operational amplifier. The first end of the operational amplifier is connected to the filter module through a sampling resistor, the second end is connected to the reference voltage circuit, and the output end is connected to the drive circuit.

4. The detection circuit according to claim 1, characterized in that: The switching power supply input large electrolytic voltage sampling circuit includes a voltage dividing module connected to the switching power supply input large electrolytic voltage sampling, and a filtering module connected to the voltage dividing module, the filtering module is connected to the comparator module, and the comparator module is connected to the reference voltage module. The comparator module output is driven by comparing the input voltage of the comparator module with the voltage value of the reference voltage point of the reference voltage circuit.

5. The detection circuit according to claim 4, characterized in that: The voltage divider module includes multiple groups of resistors arranged in series and / or in parallel, the filter module includes multiple groups of capacitors arranged in parallel, and the comparator module is an operational amplifier. The first end of the operational amplifier is connected to the filter module through a sampling resistor, the second end is connected to the reference voltage circuit, and the output end is connected to the drive circuit.

6. The detection circuit according to claim 3 or 5, characterized in that: A hysteresis comparator is connected between the output terminal and the second terminal of the operational amplifier.

7. The detection circuit according to claim 6, characterized in that: The hysteresis comparator includes a diode and a resistor connected in series.

8. The detection circuit according to claim 1, characterized in that: The reference voltage circuit comprises a voltage stabilizing diode, the cathode of the voltage stabilizing diode is connected to the capacitor via a resistor, and the cathode voltage value is the voltage of the reference voltage point, the anode is connected to the reference voltage point via a capacitor, and the anode is grounded.

9. The detection circuit according to claim 8, characterized in that: The driving circuit comprises two groups of diodes, the anodes of the two groups of diodes are respectively connected to the power-off sampling circuit and the switching power supply input large electrolysis voltage sampling circuit, and the cathodes are connected to each other and to the signal transmission circuit.

10. The detection circuit according to claim 1, characterized in that: The signal processing circuit comprises a transistor connected to the driving circuit, the emitter and collector of the transistor are connected to the primary end of the optocoupler, and the secondary end is connected to the MCU.

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