Anti-backflow charging protection circuit and charger

Abstract

The circuit comprises an NMOS tube, a driving module, a photoelectric coupler and a driving signal regulation and control module, a source electrode of the NMOS tube is connected with a voltage output end of the charger, a drain electrode of the NMOS tube is connected with a positive electrode of a battery, an input end of the driving module is connected with a driving signal output end, and an output end of the driving module is connected with a negative electrode of the battery. The output end of the driving module is connected with the grid electrode of the NMOS tube, the first end of the photoelectric coupler is connected with the control signal output end, the second end is connected with the ground end, the third end is connected with the driving signal output end, the fourth end is connected with the charger voltage output end, and the first end of the driving signal regulation and control module is connected with the positive electrode of a battery. The second end is connected with the charger voltage output end, and the third end is connected with the driving signal output end. The circuit realizes a direct anti-backflow function on a hardware level, and has the characteristics of quicker response and more reliable prevention compared with a control method for realizing anti-backflow through software sampling and threshold judgment.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of charging control technology, especially relates to a kind of anti backfilling charging protection circuit and charger. BACKGROUND

[0002] In the current battery charging application, when the charger output voltage is lower than the battery voltage, the phenomenon of reverse charging of the battery to the charger output capacitor occurs, which can cause the maximum reverse current of the charging MOS tube to be exceeded in a short period of time at the beginning of charging, and further damage the charging MOS tube of the battery pack.

[0003] In the prior art, the difference between the charger output voltage and the battery voltage is usually detected by software, and when the difference is within a certain range, the output switch is closed to achieve the anti-backfilling function. However, due to hardware errors and software detection errors, even if the output switch is closed when the software determines that the output condition is met, the battery voltage may still be higher than the output voltage, ultimately leading to the occurrence of battery current backflow phenomenon. UTILITY MODEL CONTENTS

[0004] The utility model aims at providing a kind of anti backfilling charging protection circuit and charger, the anti backfilling charging protection circuit is only realized the function that output switch can be closed when charger output voltage is higher than battery voltage by specific hardware circuit, at least one of the technical problems of the prior art, such as the error of software detection charger output voltage and battery voltage is large, response speed is slow, and reliability is insufficient.

[0005] To solve the above technical problems, the utility model is realized by the following technical solutions:

[0006] The utility model provides a kind of anti backfilling charging protection circuit, it includes: NMOS pipe, drive module, photoelectric coupler and drive signal control module;

[0007] The source of the NMOS pipe is connected with the charger voltage output end, and the drain is connected with the positive electrode of the battery;

[0008] The input end of the drive module is connected with the drive signal output end, and the output end of the drive module is connected with the gate of the NMOS pipe, for controlling the on or off state of the NMOS pipe;

[0009] The first end of the photoelectric coupler is connected with the control signal output end, the second end is connected with ground end, the third end is connected with the drive signal output end, and the fourth end is connected with the charger voltage output end;

[0010] The first end of the drive signal control module is connected with the positive electrode of the battery, the second end is connected with the charger voltage output end, and the third end is connected with the drive signal output end.

[0011] In one embodiment of the utility model, the drive module includes first resistance, second resistance, first triode, second triode and third resistance;

[0012] The first end of the first resistance and the first end of the second resistance are connected with a bias voltage output end;

[0013] The second end of the second resistance is connected with the input end of the first triode;

[0014] The second end of the first resistance, the control end of the first triode and the control end of the second triode are connected with each other and connected with the input end and the drive signal output end of the drive module;

[0015] The output end of the second triode is connected with a charger voltage output end;

[0016] The output end of the first triode and the input end of the second triode are connected with the first end of the third resistance;

[0017] The second end of the third resistance is connected with the gate of the NMOS tube.

[0018] In one embodiment of the utility model, the drive module further includes a protection unit, the first end of the protection unit is connected with the gate of the NMOS tube, and the second end is connected with a charger voltage output end.

[0019] In one embodiment of the utility model, the protection unit includes a voltage stabilizing diode and a fourth resistance;

[0020] The cathode of the voltage stabilizing diode is connected with the gate of the NMOS tube, and the anode is connected with a charger voltage output end;

[0021] The first end of the fourth resistance is connected with the gate of the NMOS tube, and the second end is connected with a charger voltage output end.

[0022] In one embodiment of the utility model, the first triode is NPN type triode, and the second triode is PNP type triode.

[0023] In one embodiment of the utility model, the drive signal regulation and control module includes a fifth resistance, a third triode, a sixth resistance and a fourth triode;

[0024] The first end of the fifth resistance is connected with a bias voltage output end;

[0025] The second end of the fifth resistance, the input end of the third triode, the control end of the third triode and the control end of the fourth triode are connected;

[0026] an output terminal of the third triode is connected with a first terminal of the sixth resistor;

[0027] a second terminal of the sixth resistor is connected with a positive electrode of a battery;

[0028] an input terminal of the fourth triode is connected with a voltage output terminal of the charger, and an output terminal of the fourth triode is connected with the driving signal output terminal.

[0029] In an embodiment of the utility model, the third triode and the fourth triode are both NPN type triodes.

[0030] In an embodiment of the utility model, the voltage of the bias voltage output terminal is higher than the voltage of the charger output terminal.

[0031] In an embodiment of the utility model, the optoelectronic coupler comprises a light emitting diode and an NPN type photosensitive triode.

[0032] the anode of the light emitting diode is connected with a control signal output terminal as a first terminal of the optoelectronic coupler, and the cathode is connected with a ground terminal as a second terminal of the optoelectronic coupler;

[0033] the collector of the NPN type photosensitive triode is connected with a driving signal output terminal as a third terminal of the optoelectronic coupler, and the emitter is connected with a charger voltage output terminal as a fourth terminal of the optoelectronic coupler.

[0034] Based on the same utility model concept, another embodiment of the utility model further provides a charger, which comprises the anti-backflow charging protection circuit according to any one of the above embodiments.

[0035] As described above, the anti-backflow charging protection circuit provided by the utility model, including NMOS tube, drive module, photoelectric coupler and drive signal control module, the source of NMOS tube is connected with charger voltage output end, the drain is connected with battery anode, the input of drive module is connected with drive signal output end, is used for receiving drive signal, the output of drive module is connected with the grid of NMOS tube, is used for controlling the conduction or off state of NMOS tube, the first end of photoelectric coupler is connected with control signal output end, the second end is connected with ground end, the third end is connected with drive signal output end, the fourth end is connected with charger voltage output end, the first end of drive signal control module is connected with battery anode, the second end is connected with charger voltage output end, the third end is connected with drive signal output end, is used for adjusting drive signal according to the voltage condition of battery anode and charger voltage output end to ensure that NMOS tube is turned on or off at proper time, prevents the backflow of current.The anti-backflow charging protection circuit adopts specific hardware circuit design to realize the anti-backflow function, compared with the control method of realizing anti-backflow by software sampling, judging threshold, has the characteristics of faster response and more reliable prevention, thereby avoiding the deviation that can be introduced in the software sampling process.In addition, in the case of allowing charging, the system first gives the control signal of opening NMOS tube, the signal cooperates with the above-mentioned anti-backflow charging protection circuit, not only ensures the reliable conduction of NMOS tube, but also realizes better protection of NMOS tube, effectively prevents the excessive forward charging current from flowing through NMOS tube.Of course, any product implementing the utility model does not necessarily need to achieve all the advantages described above. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical scheme of the embodiments of the utility model, the following will briefly introduce the drawings needed to be used in the embodiment description, obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained according to these drawings without creating labor.

[0037] Figure 1 The system block diagram of the anti-backflow charging protection circuit provided by an exemplary embodiment of the present application is provided.

[0038] Figure 2 The circuit schematic diagram of the drive module provided by an exemplary embodiment of the present application is provided.

[0039] Figure 3 The circuit schematic diagram of the drive signal control module provided by an exemplary embodiment of the present application is provided.

[0040] The reference signs are as follows:

[0041] 100 drive module;

[0042] 110 protection unit;

[0043] 200 drive signal regulation module. DETAILED DESCRIPTION

[0044] The other advantages and effects of the present application can be easily understood by those skilled in the art from the content disclosed in the present specification. The present application can also be implemented or applied in other different specific embodiments, and each detail in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0045] It should be noted that the diagrams provided in the following embodiments only schematically illustrate the basic concept of the present application, and only the components related to the present application are shown in the diagrams, not the number, shape and size of the components when actually implemented. The shape, number and proportion of each component when actually implemented can be arbitrarily changed, and the layout pattern of the components can be more complex.

[0046] In the following description, a large number of details are discussed to provide a more thorough explanation of the embodiments of the present application, however, it is obvious to those skilled in the art that the embodiments of the present application can be implemented without these specific details, and in other embodiments, the known structures and devices are shown in the form of block diagrams instead of details to avoid making the embodiments of the present application difficult to understand.

[0047] In order to solve the problems of large error, slow response speed and insufficient reliability when the software detects the output voltage of the charger and the battery voltage in the prior art, the present application provides a reverse flow prevention charging protection circuit, which is suitable for the fields of automobile charging piles, garden tools and household appliances. The circuit realizes the reverse flow prevention function through specific hardware circuit design, and under the condition of allowing charging, the circuit cooperates with software control to ensure that the positive NMOS tube can be turned on in a low-loss and reliable manner.

[0048] Please refer to Figure 1As shown, in an example embodiment of the present application, the reverse charge protection circuit comprises an NMOS tube Q1, a driving module 100, an optoelectronic coupler U1 and a driving signal control module 200. The source of the NMOS tube Q1 is connected with a charger voltage output terminal VO, and the drain is connected with a battery positive terminal VBAT+. The input terminal of the driving module 100 is connected with a driving signal output terminal GATE. The output terminal of the driving module 100 is connected with the gate of the NMOS tube Q1, for controlling the on or off state of the NMOS tube Q1. The first terminal of the optoelectronic coupler U1 is connected with a control signal output terminal CTRL, the second terminal is connected with a ground terminal VSS, the third terminal is connected with the driving signal output terminal GATE, and the fourth terminal is connected with the charger voltage output terminal VO. The first terminal of the driving signal control module 200 is connected with the battery positive terminal VBAT+, the second terminal is connected with the charger voltage output terminal VO, and the third terminal is connected with the driving signal output terminal GATE.

[0049] It should be noted that, in the present embodiment, the NMOS tube Q1 is an enhancement mode NMOS tube, which is turned on when the gate-source voltage Vgs is greater than the threshold voltage Vth. The NMOS tube Q1 is used as an electronic switch to control the on-off of the battery charging circuit. It should be noted that, in the present embodiment, the NMOS tube Q1 is a single NMOS tube. Of course, in other embodiments, a plurality of NMOS tubes of the same type and parameters can be connected in parallel to realize the parallel connection of the NMOS tubes. Even if one of the NMOS tubes fails, the other NMOS tubes can still work, improving the fault tolerance of the circuit.

[0050] In addition, the optoelectronic coupler U1 comprises a light-emitting diode and an NPN type photosensitive transistor. It should be noted that the light-emitting diode and the NPN type photosensitive transistor are integrated in the optoelectronic coupler U1. The anode of the light-emitting diode is connected with the control signal output terminal CTRL as the first terminal of the optoelectronic coupler U1, and the cathode is connected with the ground terminal VSS as the second terminal of the optoelectronic coupler U1. The collector of the NPN type photosensitive transistor is connected with the driving signal output terminal GATE as the third terminal of the optoelectronic coupler U1, and the emitter is connected with the charger voltage output terminal VO as the fourth terminal of the optoelectronic coupler U1. The control signal CTRL is a control signal for switching the NMOS tube Q1. When the control signal CTRL is high, the light-emitting diode of the optoelectronic coupler U1 is turned on, the third and fourth terminals of the optoelectronic coupler U1 are turned on, the voltage of the driving signal output terminal GATE is pulled to the same potential as the charger voltage output terminal VO, and the NMOS tube Q1 is not turned on. On the contrary, when the control signal CTRL is low, the NMOS tube Q1 is turned on.

[0051] Please refer to Figure 2 As shown in the figure, in an example embodiment of the present application, the driving module 100 comprises a first resistor R1, a second resistor R2, a first transistor T1, a second transistor T2 and a third resistor R3, a first end of the first resistor R1 and a first end of the second resistor R2 are connected with a bias voltage output terminal VCC_G_EFT, a second end of the second resistor R2 is connected with an input end of the first transistor T1, a second end of the first resistor R1, a control end of the first transistor T1 and a control end of the second transistor T2 are connected with each other and connected with a driving signal output terminal GATE as an input end of the driving module 100, an output end of the second transistor T2 is connected with a charger voltage output terminal VO, an output end of the first transistor T1 and an input end of the second transistor T2 are connected with a first end of the third resistor R3, a second end of the third resistor R3 is connected with a gate of the NMOS tube Q1.

[0052] Please continue to refer to Figure 2 As shown in the figure, in an example embodiment of the present application, the driving module 100 further comprises a protection unit 110, a first end of the protection unit is connected with the gate of the NMOS tube Q1, and a second end is connected with the charger voltage output terminal VO. Specifically, the protection unit 110 further comprises a voltage stabilizing diode D1 and a fourth resistor R4, a cathode of the voltage stabilizing diode D1 is connected with the gate of the NMOS tube Q1, and an anode is connected with the charger voltage output terminal VO, a first end of the fourth resistor R4 is connected with the gate of the NMOS tube Q1, and a second end is connected with the charger voltage output terminal VO.

[0053] It should be noted that the first transistor T1 is an NPN type transistor, the second transistor T2 is a PNP type transistor, the first resistor R1 is a base pull-up resistor, which is used to pull up the base voltage of the first transistor T1 and the second transistor T2 to the voltage of the bias voltage output terminal VCC_G_EFT, and the second resistor is a collector current limiting resistor, which is used to limit the current flowing through the first transistor T1. The voltage of the bias voltage output terminal VCC_G_EFT is set relative to the voltage of the charger output terminal VO, and in this embodiment, the voltage of the bias voltage output terminal VCC_G_EFT is higher than the voltage of the charger output terminal VO, which is used to provide stable and reliable power supply for the driving module 100. The third resistor R3 is an output current limiting resistor, which is used to limit the output current of the driving module 100. It is worth noting that, taking the first resistor R1 as an example, a plurality of resistors can be selected to be combined in series or parallel as an equivalent replacement of the first resistor R1 without changing the overall impedance characteristics in the circuit, and the same method is applicable to other resistors in the anti-backflow charging protection circuit.

[0054] Please refer to Figure 3 As shown in the figure, in an example embodiment of the present application, the drive signal regulation module 200 includes a fifth resistor R5, a third transistor T3, a sixth resistor R6 and a fourth transistor T4, a first end of the fifth resistor R5 is connected with a bias voltage output terminal VCC-G_EFT, a second end of the fifth resistor R5, an input end of the third transistor T3, a control end of the third transistor T3 and a control end of the fourth transistor T4 are connected, an output end of the third transistor T3 is connected with a first end of the sixth resistor R6, a second end of the sixth resistor R6 is connected with a positive electrode of a battery VBAT+, an input end of the fourth transistor T4 is connected with a charger voltage output terminal VO, and an output end of the fourth transistor T4 is connected with the drive signal output terminal GATE.

[0055] It should be noted that, in the present embodiment, the third transistor T3 and the fourth transistor T4 are both NPN type transistors. The bias voltage output terminal VCC-G_EFT supplies power to the collector of the third transistor T3, the base of the third transistor T3 and the base of the fourth transistor T4 through the fifth resistor R5. When the voltage of the charger voltage output terminal VO is less than the voltage of the positive electrode of the battery VBAT+, most of the current flowing through the fifth resistor R5 flows through the fourth transistor T4, and the third transistor T3 is approximately not conductive. At this time, the level of the drive signal output terminal GATE is close to the level of the charger voltage output terminal VO, and the NMOS tube Q1 is not conductive. As the voltage of the charger voltage output terminal VO gradually rises, when the voltage of the charger voltage output terminal VO is greater than the voltage of the positive electrode of the battery VBAT+, most of the current flowing through the fifth resistor R5 flows through the third transistor T3, and the fourth transistor T4 is approximately not conductive. At this time, the drive signal of the drive signal output terminal GATE is input to the drive module 100, and the NMOS tube Q1 is conductive.

[0056] Based on the same utility model concept, another embodiment of the present application also provides a charger, the charger includes a controller and the anti-backflow charging protection circuit of any of the above embodiments, wherein the controller can be a microcontroller (Microcontroller Unit, MCU), which has a control signal output terminal CTRL for sending a control signal to the optoelectronic coupler U1. Since the charger provided by the present embodiment and the anti-backflow charging protection circuit provided by any of the above embodiments belong to the same utility model concept, they at least have the same beneficial effects, and here, they will not be described one by one.

[0057] In summary, the utility model provides a kind of anti reverse filling charging protection circuit, including NMOS tube Q1, drive module 100, photoelectric coupler U1 and drive signal control module 200, the source electrode of NMOS tube Q1 is connected with charger voltage output terminal VO, drain electrode is connected with battery anode VBAT+, the input of drive module 100 is connected with drive signal output terminal GATE, for receiving drive signal, the output of drive module 100 is connected with the grid of NMOS tube Q1, for controlling the on or off state of NMOS tube Q1, the first end of photoelectric coupler U1 is connected with control signal output terminal CTRL, second end is connected with ground terminal VSS, third end is connected with drive signal output terminal GATE, fourth end is connected with charger voltage output terminal VO, the first end of drive signal control module 200 is connected with battery anode VBAT+, second end is connected with charger voltage output terminal VO, third end is connected with drive signal output terminal GATE, for adjusting drive signal according to the voltage condition of battery anode VBAT+ and charger voltage output terminal VO, to ensure that NMOS tube Q1 is turned on or off at appropriate time, prevent current reverse flow.The anti reverse filling charging protection circuit adopts specific hardware circuit design to realize anti reverse flow function, compared with the control method for realizing anti reverse flow by software sampling, judging threshold, has the characteristics of faster response speed and more reliable prevention, to avoid the deviation possibly introduced in software sampling process.In addition, in the case where charging is allowed, the system first gives the control signal of opening NMOS tube, the signal cooperates with the above-mentioned anti reverse filling charging protection circuit, not only ensures the reliable conduction of NMOS tube, but also realizes better protection to NMOS tube, effectively prevents excessive forward charging current from flowing through NMOS tube.In addition, the device working cooperatively can activate main circuit through communication signal, greatly simplifies the device activation process, so that the system can automatically activate main circuit when needed, without manual intervention, not only guarantees the continuity of the reliability of the device, but also enables the product to meet more use scenarios, thereby improving the user experience of humanization.

[0058] The above embodiments only exemplarily illustrate the principles and effects of the utility model, and are not used to limit the utility model. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the utility model. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical thought disclosed by the utility model should be covered by the claims of the utility model.

Claims

1. A reverse charging protection circuit, characterized by comprising: The application relates to a charging device for a battery, which comprises an NMOS tube, a driving module, a photoelectric coupler and a driving signal regulating module. The source of the NMOS tube is connected with a charger voltage output end, and the drain is connected with a positive pole of a battery. The input end of the driving module is connected with a driving signal output end, the output end of the driving module is connected with the gate of the NMOS tube, and the driving module is used for controlling the on or off state of the NMOS tube. The first end of the photoelectric coupler is connected with a control signal output end, the second end is connected with a ground end, the third end is connected with the driving signal output end, and the fourth end is connected with the charger voltage output end. The first end of the driving signal regulating module is connected with the positive pole of the battery, the second end is connected with the charger voltage output end, and the third end is connected with the driving signal output end. The driving module comprises a first resistor, a second resistor, a first triode, a second triode and a third resistor.

2. The back-charge-preventing protection circuit according to claim 1, wherein The first end of the first resistor and the first end of the second resistor are connected with a bias voltage output end. The second end of the second resistor is connected with the input end of the first triode. The second end of the first resistor, the control end of the first triode and the control end of the second triode are connected with each other and connected with the input end and the driving signal output end of the driving module. The output end of the second triode is connected with the charger voltage output end. The output end of the first triode and the input end of the second triode are connected with the first end of the third resistor. The second end of the third resistor is connected with the gate of the NMOS tube. The driving module further comprises a protection unit, the first end of the protection unit is connected with the gate of the NMOS tube, and the second end is connected with the charger voltage output end.

3. The back-charge-filling prevention protection circuit according to claim 2, characterized in that, The protection unit comprises a voltage stabilizing diode and a fourth resistor.

4. The back-charge-preventing protection circuit according to claim 3, wherein The cathode of the voltage stabilizing diode is connected with the gate of the NMOS tube, and the anode is connected with the charger voltage output end. The first end of the fourth resistor is connected with the gate of the NMOS tube, and the second end is connected with the charger voltage output end. The first triode is an NPN type triode, and the second triode is a PNP type triode.

5. The back-charge-filling prevention protection circuit according to claim 2, characterized in that, The driving signal regulating module comprises a fifth resistor, a third triode, a sixth resistor and a fourth triode.

6. The back-charge-filling prevention protection circuit according to claim 1, wherein, The first end of the fifth resistor is connected with a bias voltage output end. The second end of the fifth resistor, the input end of the third triode, the control end of the third triode and the control end of the fourth triode are connected. The output end of the third triode is connected with the first end of the sixth resistor. The second end of the sixth resistor is connected with the positive pole of the battery. The input end of the fourth triode is connected with the charger voltage output end, and the output end of the fourth triode is connected with the driving signal output end. The third triode and the fourth triode are both NPN type triodes.

7. The back-charge-filling prevention protection circuit according to claim 6, characterized in that, The voltage of the bias voltage output end is higher than the voltage of the charger output end.

8. The back-charge-filling prevention protection circuit according to claim 6, characterized in that, The photoelectric coupler comprises a light emitting diode and an NPN type photosensitive triode.

9. The back-charge-filling prevention protection circuit according to claim 1, wherein, The anode of the light emitting diode is connected with the control signal output end as the first end of the photoelectric coupler, and the cathode is connected with the ground end as the second end of the photoelectric coupler. ​ The collector of the NPN type photosensitive triode is connected with a driving signal output end as a third end of the photoelectric coupler, and the emitter is connected with a charger voltage output end as a fourth end of the photoelectric coupler.

10. A charger characterized by comprising: The charger comprises the anti-backflow charging protection circuit according to any one of claims 1-9.

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