Detection circuit for detecting input voltage by using flyback switching power supply

Abstract

The utility model relates to a detection circuit utilizing a flyback switching power supply to detect input voltage, which comprises an input module and a winding module connected with the input module, the input voltage enters the detection circuit through the input module, a primary winding end of the winding module is connected with the input module, and a secondary winding end of the winding module is connected with the flyback switching power supply. The voltage dividing module and the filtering module are connected with a secondary winding end of the winding module, the differential amplification module is connected with the filtering module, an output end of the differential amplification module is connected with a voltage detection end, and an input voltage value is obtained through a detection value of the voltage detection end. The negative voltage of the secondary winding of the flyback switching power supply and the reference voltage are subjected to differential amplification through the operational amplifier, the higher the AC input voltage is, the higher the negative voltage generated by the secondary winding is, and the larger the differential output is, so that the magnitude of the input voltage is determined. The voltage of the secondary winding of the flyback switching power supply is detected, primary voltage data can be transmitted to the secondary MCU without additionally arranging primary and secondary coupling devices, and the material cost is reduced.

Description

Technical Field

[0001] The utility model relates to the field of input voltage detection circuits, and particularly to a detection circuit for detecting an input voltage by using a flyback switching power supply. Background Art

[0002] A flyback transformer switching power supply, simply referred to as a flyback switching power supply, means that when the primary coil of the transformer is exactly excited by a DC pulse voltage, the secondary coil of the transformer does not provide power output to the load, and when the excitation voltage of the primary coil of the transformer is turned off, the secondary coil of the transformer provides power output to the load. At present, when detecting the AC input voltage of flyback switching power supply products, it is mostly by connecting a resistor in series on the AC input line, detecting the voltage of the series resistor, and then converting and transmitting the voltage parameter to the secondary MCU through an optocoupler. This method generates relatively large losses and the series resistor generates a large amount of heat.

[0003] Chinese Patent Publication No. CN219496509U provides a flyback transformer input voltage detection circuit structure and an electrical device. The structure includes an input voltage stress module arranged on the secondary side of the flyback transformer for generating a stress voltage along with the change of the input voltage of the flyback transformer; a voltage detection module connected to the input voltage stress module for detecting the stress voltage to output a detection voltage signal to the backend controller. In this application, an input voltage stress module is arranged on the secondary side of the flyback transformer. The input voltage stress module can generate a stress voltage along with the change of the input voltage of the flyback transformer, and then the voltage detection module detects the stress voltage to output a detection voltage signal to the backend controller, so as to realize the function of detecting the input voltage of the flyback transformer, simplify the circuit structure, and reduce the circuit layout difficulty. This patent detects through an optocoupling method after connecting a resistor in series, resulting in relatively large losses and the series resistor generating a large amount of heat. Summary of the Utility Model

[0004] The technical problem to be solved by the utility model is that when detecting the AC input voltage of current flyback switching power supply products, it is mostly by connecting a resistor in series on the AC input line, detecting the voltage of the series resistor, and then converting and transmitting the voltage parameter to the secondary MCU through an optocoupler. This method generates relatively large losses and the series resistor generates a large amount of heat. In view of the above defects of the prior art, a detection circuit for detecting an input voltage by using a flyback switching power supply is provided.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0006] A detection circuit for detecting an input voltage using a flyback switching power supply is constructed, including an input module and a winding module connected to the input module. The input voltage enters the detection circuit through the input module. The primary winding end of the winding module is connected to the input module. The detection circuit further includes a voltage division module and a filtering module connected to the secondary winding end of the winding module, and a differential amplification module connected to the filtering module. The output end of the differential amplification module is connected to a voltage detection end, and the magnitude of the input voltage value can be obtained through the detected value at the voltage detection end.

[0007] Preferably, the input module includes a first field-effect transistor. When the first field-effect transistor is turned on, an induced electromotive force is generated on the primary winding, and an opposite induced electromotive force is generated on the secondary winding.

[0008] Preferably, the voltage division module includes a first voltage division module and a second voltage division module, the filtering module includes a first filtering module and a second filtering module. The first voltage division module is connected to the secondary winding. The first filtering module is arranged between the first voltage division module and the differential amplification module. The output end of the differential amplification module is connected to the second voltage division module and then connected to the second filtering module, and is connected to the voltage detection end through the second filtering module.

[0009] Preferably, the first voltage division module includes a sixth resistor and a sixteenth resistor connected in series. A fifth diode is connected between the first voltage division module and the first filtering module.

[0010] Preferably, the first filtering module includes a ninth capacitor and a tenth resistor connected in parallel. The tenth resistor is connected to the differential amplification module. The differential amplification module is a second differential amplifier, and the tenth resistor is connected to the inverting end of the second differential amplifier.

[0011] Preferably, the non-inverting end of the second differential amplifier is grounded through a seventeenth resistor.

[0012] Preferably, the second voltage division module includes an eleventh resistor and a fifteenth resistor connected in series. One end of the fifteenth resistor is grounded.

[0013] Preferably, the second filtering module includes a twelfth resistor, and a seventh capacitor and an eighth capacitor connected in series. The twelfth resistor is connected in parallel with the seventh capacitor and the eighth capacitor.

[0014] The beneficial effects of the present utility model are as follows: By differentially amplifying the negative voltage of the secondary winding of the flyback switching power supply and the reference voltage through an operational amplifier, the higher the AC input voltage, the higher the negative voltage generated by the secondary winding, and the larger the differential output, thereby determining the magnitude of the input voltage. Moreover, by detecting the voltage of the secondary winding of the flyback switching power supply, it is possible to transmit the primary voltage data to the secondary MCU without additionally increasing the primary-secondary coupling device, reducing the material cost. There is also no need to serially connect a detection resistor on the line, reducing power loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will further explain the present utility model in conjunction with the drawings and embodiments. The drawings in the following description are only partial embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings:

[0016] Figure 1 It is a circuit block diagram of the detection circuit of the preferred embodiment of the present utility model;

[0017] Figure 2 It is the specific circuit diagram of the detection circuit of the preferred embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] In order to make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present utility model. Obviously, the described embodiments are partial embodiments of the present utility model, rather than all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present utility model.

[0019] A detection circuit for detecting the input voltage using a flyback switching power supply in the preferred embodiment of the present utility model; as Figure 1 shown, it includes a voltage input module 10, a winding module 20 connected to the voltage input module, a first voltage division module 30 connected to the winding module, a first filtering module 40 connected to the first voltage division module, a differential amplification module 50 connected to the first filtering module, a second voltage division module 60 connected to the differential amplification module, a second filtering module 70 connected to the second voltage division module, and an ADC pin 80 connected to the second filtering module. By comparing the voltage of the ADC pin with the input voltage to form a characteristic curve or a list, the voltage value of the primary input can be obtained by detecting the voltage of the ADC pin.

[0020] Specifically, as Figure 2As shown, the input voltage of the input module 10 is input through the Vin pin, grounded through the parallel-connected second capacitor C2 and third capacitor C3, and connected to one end of the transformer winding T1. The input voltage is grounded through the second resistor R2, second diode D2, first field-effect transistor Q1, and twentieth resistor R20 connected in series. The two ends of the transformer winding T1 are respectively connected to the second resistor R2 and the second diode D2, and the first capacitor C1 is connected in parallel across the two ends of the second resistor. The Vin pin is also connected to the first resistor R1 and third resistor R3 connected in series, and connected to one end of the transformer winding T1C through the fourth resistor R4 and third diode D3 connected in series, with the other end grounded. The third resistor R3 is connected to the VCC pin of the first control module U1 and grounded through the eleventh capacitor C11. The COMP pin of the first control module U1 is grounded through the twelfth capacitor C12 and also grounded through the eighteenth resistor R18 and fifteenth capacitor C15 connected in series. The GATE pin of the first control module U1 is connected to the first field-effect transistor Q1 through the fifth resistor R5 and fourth diode D4 connected in series, and is also connected to the first field-effect transistor Q1 through the ninth resistor R9. The ninth resistor R9 is connected to the thirteenth resistor R13 and twentieth resistor R20 and then grounded. The CS pin of the first control module U1 is grounded through the fourteenth resistor R14 and twentieth resistor R20 and is also directly grounded through the thirteenth capacitor C13. The FB pin of the first control module U1 is grounded through the fourteenth capacitor C14, is also directly connected to the seventh resistor R7, and is also grounded through the twenty-first resistor R21.

[0021] Further, as Figure 2As shown, the winding module 20 uses a transformer module T1. The primary winding T1A is connected to the input module, and the secondary winding T1B is connected to the first voltage division module 30. The first voltage division module includes a sixth resistor R6 and a sixteenth resistor R16 connected in series; the secondary winding is also connected to a first diode D1, and through the first diode, it is connected to a fourth capacitor C4, a fifth capacitor C5, and a sixth capacitor C6 connected in parallel and grounded, as well as to the other end of the secondary winding T1B. The voltage after voltage division is conducted through a fifth diode D5 and then connected to a first filtering module 40. The first filtering module includes a tenth resistor R10 connected to the fifth diode D5, and a ninth capacitor C9 connected to the fifth diode D5. The ninth capacitor C9 is connected in parallel with the tenth resistor R10. After filtering, the voltage is transmitted to a differential amplification module 50 through the tenth resistor R10. The differential amplification module uses an operational amplifier U2A, whose inverting terminal is connected to the first filtering module, and the non-inverting terminal is grounded through a seventeenth resistor R17. The voltage output after differential amplification by the operational amplification module is divided by a second voltage division circuit 60 composed of an eleventh resistor R11 and a fifteenth resistor R15. The eleventh resistor R11 and the fifteenth resistor R15 are connected in series and grounded. The output voltage of the second voltage division module is output to an ADC pin 80 after passing through a second filtering module 70. The second filtering module includes a twelfth resistor R12 connected to the eleventh resistor R11, and is connected to the ADC pin through a seventh capacitor C7 and an eighth capacitor C8 connected in series. The output voltage of the ADC pin can be detected accordingly.

[0022] In use, the input voltage is input through the Vin pin. When the first field-effect transistor Q1, as a switching transistor, conducts, an induced electromotive force with positive on the top and negative on the bottom is generated on the primary winding T1A. In order to suppress the increase in magnetic flux, an induced electromotive force with negative on the top and positive on the bottom is generated on the secondary winding T1B, that is, the voltage at the VIN_S point of the secondary winding is less than the SGND reference voltage. The greater the primary input voltage, the smaller the voltage at the VIN_S point relative to GND. Since the negative voltage at the VIN_S point is divided by the sixth resistor R6 and the sixteenth resistor R16, then passes through the fifth diode D5 (a unidirectional conduction diode), and is filtered by the ninth capacitor C9 and the tenth resistor R10 and then connected to the inverting terminal of the second operational amplifier U2. The non-inverting terminal of the second operational amplifier U2 is connected to SGND through the seventeenth resistor R17. The voltage output after the second operational amplifier U2 performs differential amplification is divided by the eleventh resistor R11 and the fifteenth resistor R15, and then filtered by the seventh capacitor C7, the twelfth resistor R12, and the eighth capacitor C8, and is transmitted to the ADC pin of the secondary MCU for detection. By comparing the voltage detected by the ADC pin of the MCU with the primary input voltage of the switching power supply to form a characteristic curve or a list, the primary input voltage can be obtained from the voltage detected by the ADC. Thus, by detecting the voltage of the secondary winding of the flyback switching power supply, without the need to additionally increase the primary-secondary coupling device, the primary voltage data can be transmitted to the secondary MCU, reducing the material cost. And there is no need to serially connect a detection resistor on the line, reducing power loss.

[0023] It should be understood that the present invention is described through some embodiments. As is known to those skilled in the art, without departing from the spirit and scope of the present invention, various changes or equivalent replacements can be made to these features and embodiments. Additionally, 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 detection circuit for detecting an input voltage using a flyback switching power supply, comprising an input module and a winding module connected to the input module. The input voltage enters the detection circuit through the input module. The primary winding end of the winding module is connected to the input module, and is characterized in that: The electrical inspection circuit further includes a voltage division module and a filtering module connected to the secondary winding end of the winding module, and a differential amplification module connected to the filtering module. The output end of the differential amplification module is connected to the voltage detection end, and the magnitude of the input voltage value can be obtained through the detection value of the voltage detection end.

2. The detection circuit according to claim 1, wherein: The input module includes a first field-effect transistor. When the first field-effect transistor is turned on, an induced electromotive force is generated on the primary winding, and an opposite induced electromotive force is generated on the secondary winding.

3. The detection circuit according to claim 1, wherein: The voltage division module includes a first voltage division module and a second voltage division module. The filtering module includes a first filtering module and a second filtering module. The first voltage division module is connected to the secondary winding. The first filtering module is arranged between the first voltage division module and the differential amplification module. The output end of the differential amplification module is connected to the second voltage division module and then connected to the second filtering module, and is connected to the voltage detection end through the second filtering module.

4. The detection circuit according to claim 3, characterized in that: The first voltage division module includes a sixth resistor and a sixteenth resistor connected in series. A fifth diode is connected between the first voltage division module and the first filtering module.

5. The detection circuit according to claim 3, wherein: The first filtering module includes a ninth capacitor and a tenth resistor connected in parallel. The tenth resistor is connected to the differential amplification module. The differential amplification module is a second differential amplifier, and the tenth resistor is connected to the inverting end of the second differential amplifier.

6. The detection circuit according to claim 5, characterized in that: The non-inverting end of the second differential amplifier is grounded through a seventeenth resistor.

7. The detection circuit according to claim 3, wherein: The second voltage division module includes an eleventh resistor and a fifteenth resistor connected in series. One end of the fifteenth resistor is grounded.

8. The detection circuit according to claim 3, characterized in that: The second filtering module includes a twelfth resistor, and a seventh capacitor and an eighth capacitor connected in series. The twelfth resistor is connected in parallel with the seventh capacitor and the eighth capacitor.

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