Charging protection circuit and charger

Abstract

The invention relates to a charging protection circuit and a charger. The charging protection circuit comprises a battery voltage sampling module connected with a battery, a reference voltage module, a charging control module and a switch module, the switch module is used for connecting a charging power supply and a battery; a first input end, a second input end and an output end of the charging control module are respectively connected with the battery voltage sampling module, a first end of the reference voltage module and the switch module; the charging control module is used for controlling the switch-on and switch-off of the switch module under the condition that the battery voltage is smaller than the first reference voltage, so that the battery is maintained to be charged in a first charging stage; and under the condition that the battery voltage is greater than the first reference voltage, switching the battery from the first charging stage to a second charging stage, and controlling the switch-on and switch-off of the switch module, so that the battery is maintained to be charged in the second charging stage. The charging protection circuit can protect the battery charging process.

Description

Technical Field

[0001] The present application relates to the technical field of battery charging, and in particular to a charging protection circuit and a charger. Background Art

[0002] Sealed lead-acid batteries have become core energy storage devices in the fields of uninterruptible power supplies, electric vehicles, communication base stations, etc. due to their compact structure, maintenance-free, leak-proof, high safety and significant cost-effectiveness. However, the charging management technology of sealed lead-acid batteries has been lagging behind for a long time, far behind the development pace of its widespread application needs.

[0003] There are many unreasonable aspects in common charging methods. On the one hand, it will lead to excessive polarization of the battery plates, shortening the battery life. On the other hand, if the voltage is not properly controlled, overcharging is likely to occur, and in severe cases, thermal runaway may even occur, causing the battery to fail prematurely. Summary of the invention

[0004] Based on this, it is necessary to provide a charging protection circuit and a charger that can protect the battery charging process.

[0005] In a first aspect, a charging protection circuit is provided, the charging protection circuit comprising: a battery voltage sampling module connected to a battery, a reference voltage module, a charging control module and a switch module;

[0006] The switch module is used to connect the charging power source and the battery. The first input terminal, the second input terminal and the output terminal of the charging control module are respectively connected to the battery voltage sampling module, the first terminal of the reference voltage module and the switch module. When the switch module is connected to the charging power source, the switch module conducts the charging circuit of the charging power source and the battery based on the control of the charging control module.

[0007] A charging control module, used to control the on and off of the switch module when the battery voltage collected by the battery voltage sampling module is less than the first reference voltage generated by the first end of the reference voltage module, so that the battery is charged in the first charging stage;

[0008] Furthermore, when the battery voltage is greater than the first reference voltage, the battery is switched from the first charging stage to the second charging stage, and the switch module is controlled to be turned on and off so that the battery is maintained in the second charging stage for charging; the charging current range of the first charging stage is smaller than the charging current range of the second charging stage.

[0009] In one embodiment, the charging control module includes a charging comparison unit, a charging switching unit and a charging maintenance unit, wherein the first input end of the charging comparison unit is connected to the battery voltage sampling module, the second input end is connected to the first end of the reference voltage module, the output end is connected to the first end of the charging switching unit, and the charging maintenance unit is used to connect the second end of the charging switching unit to the switch module;

[0010] A charging comparison unit, configured to output a first comparison signal to the charging switching unit when the battery voltage is less than the first reference voltage; and output a second comparison signal to the charging switching unit when the battery voltage is greater than the first reference voltage;

[0011] A charging switching unit, configured to output a first-stage charging signal to the charging maintaining unit based on a first comparison signal; and output a second-stage charging signal to the charging maintaining unit based on a second comparison signal;

[0012] The charging maintenance unit is used to control the switch module to turn on the charging power supply and the charging circuit of the battery when the charging power supply is connected; it is also used to control the on and off of the switch module based on the first stage charging signal to maintain the first stage charging process of the battery; and, based on the second stage charging signal, control the on and off of the switch module to maintain the second stage charging process of the battery.

[0013] In one embodiment, the charging comparison unit includes a resistor 1, a resistor 2 and a first operational amplifier;

[0014] The non-inverting input terminal of the first operational amplifier is connected to the battery voltage sampling module, and the inverting input terminal of the first operational amplifier is connected to the first terminal of the reference voltage module;

[0015] The first end of resistor one is connected to the power supply and the first end of the charging switching unit respectively, the second end of resistor one is connected to the first end of resistor two and the second end of the charging switching unit respectively, and the second end of resistor two is connected to the output end of the first operational amplifier.

[0016] In one embodiment, the charging switching unit includes a resistor three, a resistor four, a resistor five, a resistor six, a first switch tube and a second operational amplifier;

[0017] The first end of resistor three and the first end of resistor four are both connected to the power supply, the second end of resistor three is connected to the first end of the first switch tube, the second end of the first switch tube is connected to the output end of the charging comparison unit, the third end of the first switch tube, the second end of resistor four, and the first end of resistor five are all connected to the inverting input end of the second operational amplifier, resistor six is ​​used to connect the non-inverting input end and the output end of the second operational amplifier, and the second end of resistor five is grounded.

[0018] In one embodiment, the charging maintenance unit includes a current limiting subunit and a switch control subunit, the first end of the current limiting subunit is connected to the charging switching unit, the second end of the current limiting subunit and the battery voltage sampling module are connected to the first input end of the switch control subunit, the second input end of the switch control subunit is connected to the second end of the reference voltage module, and the output end of the switch control subunit is connected to the switch module;

[0019] The current limiting subunit is used to increase the input voltage of the first input terminal of the switch control subunit when the charging current is greater than the maximum current of the corresponding charging stage;

[0020] The switch control subunit is used to control the switch module to be turned off so as to cut off the connection between the charging power source and the battery when the input voltage is greater than the second reference voltage output by the second end of the reference voltage module.

[0021] In one embodiment, the current limiting subunit includes a first diode and a resistor seven, and the switch control subunit includes a resistor eight, a resistor nine, a resistor ten and a third operational amplifier;

[0022] The first end of the first diode is connected to the charging switching unit, the second end of the first diode is connected to the first end of the resistor seven, the second end of the resistor seven is connected to the inverting input end of the third operational amplifier, and the inverting input end of the third operational amplifier is connected to the battery voltage sampling module through the resistor nine, the non-inverting input end of the third operational amplifier is connected to the second end of the reference voltage module through the resistor ten, the output end of the third operational amplifier is connected to the first end of the resistor eight, and the second end of the resistor eight is connected to the switch module.

[0023] In one embodiment, the battery voltage sampling module includes a resistor 11, a resistor 12 and a resistor 13, and the resistance value of the resistor 13 is determined based on the threshold voltage at the start of the second charging stage;

[0024] The first end of the resistor 11 is connected to the battery, the resistor 12 is used to connect the second end of the resistor 11 and the first end of the resistor 13, the second end of the resistor 13 is grounded, and the common end of the resistor 12 and the resistor 13 is connected to the charging control module.

[0025] In one embodiment, the switch module includes a resistor 14, a resistor 15, a resistor 16, a second switch tube and a third switch tube;

[0026] The first end of the second switch tube is connected to the first end of resistor 14 and the charging control module, the second end of the second switch tube is connected to the first end of resistor 15, the second end of resistor 15 is respectively connected to the first end of resistor 16 and the first end of the third switch tube, the second end of the third switch tube and the second end of resistor 16 are both connected to the charging power supply, the third end of the third switch tube is connected to the battery, and the third end of the second switch tube and the second end of resistor 14 are both grounded.

[0027] In one embodiment, the charging protection circuit further includes a charging display module, which includes a current acquisition unit, a current comparison unit and a light emitting diode, wherein the input end of the current acquisition unit is connected to the battery, the output end of the current acquisition unit and the third end of the reference voltage module are both connected to the input end of the current comparison unit, and the output end of the current comparison unit is connected to the light emitting diode;

[0028] When the voltage corresponding to the current collected by the current collection unit is greater than the third reference voltage generated by the third terminal of the reference voltage module, the battery is in a charging state, and the current comparison unit outputs a low-level signal; the low-level signal is used to control the light-emitting diode to be in a light-emitting state;

[0029] When the voltage corresponding to the current collected by the current collection unit is less than the third reference voltage, the battery is in a fully charged state, and the current comparison unit outputs a high level signal; the high level signal is used to control the light emitting diode to be in a non-luminous state.

[0030] In a second aspect, the present application further provides a charger, which includes an embodiment of a charging protection circuit according to any one of the above-mentioned first aspects.

[0031] The charging protection circuit includes: a battery voltage sampling module connected to the battery, a reference voltage module, a charging control module and a switch module; the switch module is used to connect the charging power supply and the battery, the first input end, the second input end and the output end of the charging control module are respectively connected to the battery voltage sampling module, the first end of the reference voltage module and the switch module, when the switch module is connected to the charging power supply, the switch module is based on the control of the charging control module to conduct the charging circuit of the charging power supply and the battery; the charging control module is used to control the on and off of the switch module when the battery voltage collected by the battery voltage sampling module is less than the first reference voltage generated by the first end of the reference voltage module, so that the battery is maintained in the first charging stage for charging; and when the battery voltage is greater than the first reference voltage, the battery is switched from the first charging stage to the second charging stage, and the on and off of the switch module is controlled so that the battery is maintained in the second charging stage for charging; the charging current range of the first charging stage is less than the charging current range of the second charging stage. The circuit charges with adaptive current at different stages of battery charging, which can avoid overcharge phenomenon in constant voltage charging. In addition, by setting the reference voltage module to output the first reference voltage, the relationship between the battery voltage and the first reference voltage is judged based on the first reference voltage. When the battery voltage collected by the battery voltage sampling module is less than the first reference voltage, the charging control module controls the switch module to conduct, and the battery is maintained in the first charging stage with a smaller charging current. Charging with a lower current in this stage can reduce the polarization phenomenon of the electrode material inside the battery, avoid the destruction of the electrode material structure due to high current charging, and thus significantly extend the cycle life of the battery. When the battery voltage collected by the battery voltage sampling module is greater than the first reference voltage, the charging control module controls the switch module to limit the charging power supply to maintain the charging current of the second charging stage greater than the first stage for charging; in this way, the charging time of the battery in the second charging stage can be reduced, and the current range in the charging process can also be limited to protect the rechargeable battery. In other words, the charging protection circuit can reasonably plan the charging current at different stages when the battery is charged, and maximize the charging efficiency under the premise of ensuring battery safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 is a first schematic diagram of a charging protection circuit in an embodiment;

[0034] Figure 2 is a second schematic diagram of a charging protection circuit in one embodiment;

[0035] Figure 3 FIG. 3 is a third schematic diagram of a charging protection circuit in an embodiment.

[0036] Description of reference numerals:

[0037] 10: Charging protection circuit; 11: Battery voltage sampling module; 12: Reference voltage module; 13: Charging control module; 131: Charging comparison unit; 132: Charging switching unit; 133: Charging maintenance unit; 1331: Current limiting subunit; 1332: Switch control subunit; 14: Switch module; 15: Reverse connection protection module; 16: Charging display module; 161: Current acquisition unit; 162: Current comparison unit; 20: Battery. DETAILED DESCRIPTION

[0038] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0040] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0041] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0042] When used herein, the singular forms "a", "an" and " / the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0043] In one embodiment, Figure 1 As shown, a charging protection circuit 10 is provided, and the charging protection circuit 10 includes: a battery voltage sampling module 11 connected to a battery 20, a reference voltage module 12, a charging control module 13 and a switch module 14;

[0044] The switch module 14 is used to connect the charging power source VCC1 and the battery 20. The first input terminal, the second input terminal and the output terminal of the charging control module 13 are respectively connected to the battery voltage sampling module 11, the first terminal of the reference voltage module 12 and the switch module 14. When the switch module 14 is connected to the charging power source VCC1, the switch module 14 conducts the charging circuit between the charging power source VCC1 and the battery 20 based on the control of the charging control module 13.

[0045] The charging control module 13 is used to control the on and off of the switch module 14 when the battery voltage collected by the battery voltage sampling module 11 is less than the first reference voltage generated by the first end of the reference voltage module 12, so that the battery 20 is charged in the first charging stage;

[0046] Furthermore, when the battery voltage is greater than the first reference voltage, the battery 20 is switched from the first charging stage to the second charging stage, and the switch module 14 is controlled to be turned on and off, so that the battery 20 is maintained in the second charging stage for charging; the charging current range of the first charging stage is smaller than the charging current range of the second charging stage, the charging current range of the first charging stage is recorded as the first current range, and the charging current range of the second charging stage is recorded as the second current range.

[0047] For example, the charging current range of the first charging stage may be 1 ampere (A)-3A, and the charging current range of the second charging stage may be 5A-8A.

[0048] In the embodiment of the present application, the charging protection circuit 10 is used to connect the battery 20 with the charging power supply VCC1. When the battery 20 is connected to the charging power supply VCC1, the charging protection circuit 10 can protect the charging process during the process of charging the battery 20 through the charging power supply VCC1. It can be understood that the charging protection circuit 10 can be set in the charger or integrated with the charging power supply VCC1.

[0049] In order to ensure that the charging power supply VCC1 can charge the battery 20 normally, the switch module 14 in the charging protection circuit 10 is used to connect the charging power supply VCC1 and the battery 20. When the switch module 14 is turned on, the charging power supply VCC1 charges the battery 20 normally; when the switch module 14 is turned off, the charging power supply VCC1 cannot charge the battery 20. Among them, the switch module 14 can be implemented by a switch tube, for example, a triode, a metal oxide semiconductor field effect transistor (Metal Oxide Semiconductor Field Effect Transistor, MOS), etc. Alternatively, it can also be implemented by various types of switches, etc. Alternatively, it can also be implemented by some switch chips.

[0050] During the charging process, the battery 20 can be charged with different charging currents at different stages, which can not only avoid the transition polarization of the internal plates of the battery 20, but also avoid the overcharge phenomenon. Based on this, the charging stage of the battery 20 can be divided into the first charging stage and the second charging stage. The first charging stage refers to the beginning of charging the battery 20, and this stage needs to be charged with a smaller charging current. The second charging stage means that part of the charging has been completed. In this stage, it can be charged with a larger charging current, that is, the charging power supply VCC1 is limited to maintain a charging current greater than the first charging stage in the second charging stage for charging; in this way, the charging time of the battery 20 in the second charging stage can be reduced, and the current range during the charging process can also be limited to protect the rechargeable battery. In other words, the charging protection circuit 10 can reasonably plan the charging current at different stages when the battery is charged, and maximize the charging efficiency while ensuring the safety of the battery. For example, the battery 20 can be a lithium-ion battery, a nickel-hydrogen battery, or the like.

[0051] In order to realize charging with different currents at different stages, the charging protection circuit 10 also needs to be provided with a battery voltage sampling module 11, a reference voltage module 12 and a charging control module 13. These three modules are introduced one by one below.

[0052] For the battery voltage sampling module 11, the input end of the battery voltage sampling module 11 is connected to the battery 20, and the output end of the battery voltage sampling module 11 is connected to the first input end of the charging control module 13. When the switch module 14 is turned on and the charging power supply VCC1 charges the battery 20, the battery voltage sampling module 11 can collect the voltage of the battery 20 at the current moment in real time, and input the battery voltage to the first input end of the charging control module 13. Among them, the battery voltage sampling module 11 can be implemented by a resistor sampling circuit or a sampling sensor circuit. For the resistor sampling circuit, the charging voltage of the battery 20 at the current moment can be determined by collecting the voltage on the resistor.

[0053] For the reference voltage module 12, the power supply VCC2 of the reference voltage module 12 can be the charging power supply VCC1 or a fixed power supply. The first end of the reference voltage module 12 is connected to the second input end of the charging control module 13. The function of the reference voltage module 12 is to generate a stable first reference voltage as a reference standard for charging control, and input the first reference voltage to the second input end of the charging control module 13. For different types of batteries 20, the required reference voltage values ​​are different, so a voltage regulating circuit can be set in the reference voltage module 12, and the voltage regulating circuit can adjust the voltage of the power supply VCC2 based on the type of battery 20 to output a first reference voltage suitable for the type of battery 20.

[0054] For the charging control module 13, the first input end of the charging control module 13 is connected to the battery voltage sampling module 11, and is used to receive the battery voltage collected by the battery voltage sampling module 11. The second input end is connected to the first end of the reference voltage module 12, and is used to receive the first reference voltage output by the first end of the reference voltage module 12. The output end of the charging control module 13 is connected to the switch module 14.

[0055] The charging control module 13 mainly compares the battery voltage with the first reference voltage, determines the stage of the battery 20 based on the comparison result, and controls the battery 20 to maintain the charging stage by controlling the on and off of the switch module 14. Specifically, when the battery voltage is less than the first reference voltage, it means that the battery voltage is small and should be charged with a smaller current, then the charging control module 13 controls the battery 20 to be in the first charging stage. When the battery 20 is in the first charging stage. Assuming that the charging current of the battery 20 during the charging process of the first charging stage exceeds the maximum current of the stage, making the charging current too large, the switch module 14 can be controlled to be turned off by the charging control module 13 to reduce the current of the battery 20 charging process. After the switch module 14 is turned off, the charging circuit between the battery 20 and the charging power supply VCC1 is disconnected. Thereafter, based on the charging control module 13 controlling the switch module 14 to be turned on, the charging circuit between the battery 20 and the charging power supply VCC1 is restored to the on state. In this way, in the first charging stage, the switch module 14 can be repeatedly controlled to be turned on and off by the charging control module 13 to maintain the charging current within the first current range, and the charging current of the first charging stage can be reasonably limited according to the current battery voltage to improve the repeated service life of the battery. When the battery voltage is greater than the first reference voltage, it means that the battery voltage at this time is larger than that in the first charging stage, and it should be charged with a larger current. At this time, the charging control module 13 can control the battery 20 to switch from the first charging stage to the second charging stage. Assuming that the charging current of the battery 20 during the charging process of the second charging stage exceeds the maximum current of this stage, so that the charging current is too large, the switch module 14 can be controlled to be turned off by the charging control module 13 to reduce the current of the battery 20 charging process; after the switch module 14 is turned off, the charging circuit between the battery 20 and the charging power supply VCC1 is disconnected. The charging control module 13 controls the switch module 14 to be turned on, and the charging circuit between the battery 20 and the charging power supply VCC1 is restored to the on state. Thus, in the second charging stage, the charging control module 13 can repeatedly control the on and off of the switch module 14 to maintain the charging current within the second current range, and the charging current of the second charging stage can be reasonably limited according to the current battery voltage to increase the repeated service life of the battery. In this way, the charging control module 13 can charge with different currents at different stages, and the first current range is smaller than the second current range. In this way, while limiting the charging current, the charging efficiency can also be correspondingly accelerated. Among them, the charging control module 13 can be implemented by a control chip or a related circuit including a comparison circuit.

[0056] The charging protection circuit 10 comprises: a battery voltage sampling module 11 connected to the battery 20, a reference voltage module 12, a charging control module 13 and a switch module 14; the switch module 14 is used to connect the charging power source VCC1 and the battery 20, and the first input terminal, the second input terminal and the output terminal of the charging control module 13 are respectively connected to the battery voltage sampling module 11, the first terminal of the reference voltage module 12 and the switch module 14. When the switch module 14 is connected to the charging power source VCC1, the switch module 14 conducts the charging circuit between the charging power source VCC1 and the battery 20 based on the control of the charging control module 13; The charging control module 13 is used to control the on and off of the switch module 14 when the battery voltage collected by the battery voltage sampling module 11 is less than the first reference voltage generated by the first end of the reference voltage module 12, so that the battery 20 is maintained in the first charging stage for charging; and, when the battery voltage is greater than the first reference voltage, the battery 20 is switched from the first charging stage to the second charging stage, and the on and off of the switch module 14 is controlled so that the battery 20 is maintained in the second charging stage for charging; the charging current range of the first charging stage is less than the charging current range of the second charging stage. The circuit charges with an adaptive current at different stages of the charging of the battery 20, which can avoid the overcharge phenomenon in constant voltage charging. In addition, by setting the reference voltage module 12 to output the first reference voltage, the relationship between the battery voltage and the first reference voltage is judged based on the first reference voltage. When the battery voltage collected by the battery voltage sampling module 11 is less than the first reference voltage, the charging control module 13 controls the switch module 14 to conduct, and the battery 20 is maintained in the first charging stage with a smaller charging current. Charging with a lower current at this stage can reduce the polarization phenomenon of the electrode material inside the battery 20, avoid the destruction of the electrode material structure due to high current charging, and thus significantly extend the cycle life of the battery 20. When the battery voltage collected by the battery voltage sampling module 11 is greater than the first reference voltage, the charging power supply is limited to maintain a charging current in the second charging stage greater than the first stage for charging. In this way, the charging time of the battery 20 in the second charging stage can be reduced, and the current range during the charging process can be limited to protect the rechargeable battery. In other words, the charging protection circuit 10 can reasonably plan the charging current at different stages when the battery is charged, and maximize the charging efficiency while ensuring the safety of the battery 20.

[0057] The charging control module 13 is an important part for achieving safe charging. Figure 2As shown, the charging control module 13 includes a charging comparison unit 131, a charging switching unit 132 and a charging maintenance unit 133. The first input end of the charging comparison unit 131 is connected to the battery voltage sampling module 11, the second input end is connected to the first end of the reference voltage module 12, and the output end is connected to the first end of the charging switching unit 132. The charging maintenance unit 133 is used to connect the second end of the charging switching unit 132 with the switch module 14;

[0058] The charging comparison unit 131 is used to output a first comparison signal to the charging switching unit 132 when the battery voltage is less than the first reference voltage; and output a second comparison signal to the charging switching unit 132 when the battery voltage is greater than the first reference voltage;

[0059] The charging switching unit 132 is used to output a first-stage charging signal to the charging maintaining unit 133 based on the first comparison signal; and output a second-stage charging signal to the charging maintaining unit 133 based on the second comparison signal;

[0060] The charging maintenance unit 133 is used to control the switch module 14 to turn on the charging circuit between the charging power source VCC1 and the battery 20 when the charging power source VCC1 is connected; it also controls the on and off of the switch module 14 based on the first-stage charging signal to maintain the first-stage charging process of the battery 20; and, based on the second-stage charging signal, controls the on and off of the switch module 14 to maintain the second-stage charging process of the battery 20.

[0061] In the embodiment of the present application, the charging control module 13 can be divided into three parts from a functional perspective, namely a charging comparison unit 131 for comparing the battery voltage and the first reference voltage, a charging switching unit 132 for switching the battery 20 from the first charging stage to the second charging stage according to the comparison result, and a charging maintenance unit 133 for performing current limiting control in different charging stages.

[0062] For the charging comparison unit 131, its input includes the battery voltage collected by the battery voltage sampling module 11 and the first reference voltage generated by the first end of the reference voltage module 12, compares the battery voltage with the first reference voltage, and outputs different comparison signals to the charging switching unit 132 according to the comparison result. Among them, the charging comparison unit 131 can be implemented by a circuit composed of an operational amplifier and other electronic components, and can also be implemented by a control chip.

[0063] In one embodiment, if Figure 3 As shown, the charging comparison unit 131 includes a resistor 1 R1, a resistor 2 R2 and a first operational amplifier U1;

[0064] The non-inverting input terminal of the first operational amplifier U1 is connected to the battery voltage sampling module 11, and the inverting input terminal of the first operational amplifier U1 is connected to the first terminal of the reference voltage module 12;

[0065] The first end of the resistor R1 is connected to the power supply VCC2 and the first end of the charging switching unit 132 respectively, the second end of the resistor R1 is connected to the first end of the resistor R2 and the second end of the charging switching unit 132 respectively, and the second end of the resistor R2 is connected to the output end of the first operational amplifier U1.

[0066] For the charging switching unit 132, a first end of the charging switching unit 132 is connected to the output end of the charging comparison unit 131, and is used to receive corresponding comparison signals at different stages of charging of the battery 20. The charging comparison unit 131 can be a logic circuit composed of a plurality of AND gates, OR gates and inverters. It can also be implemented by an analog switch circuit.

[0067] In one embodiment, the charging switching unit 132 includes a resistor R3, a resistor R4, a resistor R5, a resistor R6, a first switch Q1 and a second operational amplifier U2;

[0068] The first end of resistor R3 and the first end of resistor R4 are both connected to the power supply VCC2, the second end of resistor R3 is connected to the first end of the first switch tube Q1, the second end of the first switch tube Q1 is connected to the output end of the charging comparison unit 131, the third end of the first switch tube Q1, the second end of resistor R4, and the first end of resistor R5 are all connected to the inverting input end of the second operational amplifier U2, resistor R6 is used to connect the non-inverting input end and the output end of the second operational amplifier U2, and the second end of resistor R5 is grounded.

[0069] In the embodiment of the present application, after the input battery voltage and the first reference voltage are compared by the first operational amplifier U1, it can be determined whether the battery 20 is in the first charging stage or the second charging stage based on the level signal output by the first operational amplifier U1. At this time, the first switch tube Q1 can be turned on or off based on the level signal output by the first operational amplifier U1 to adjust the voltage at the non-inverting input terminal of the second operational amplifier U2, thereby controlling the battery 20 to switch from the first charging stage to the second charging stage.

[0070] Specifically, when the battery voltage input to the non-inverting input terminal of the first operational amplifier U1 is less than the first reference voltage input to the inverting input terminal, the first operational amplifier U1 outputs a low-level signal. At this time, it can be determined that the battery 20 is in the first charging stage, that is, the slow charging state. At this time, the first switch tube Q1 is in the off state, and the voltage of the inverting input terminal of the second operational amplifier U2 is determined according to the power supply VCC2, the resistor four R4 and the resistor five R5. The corresponding formula can be expressed as:

[0071] The voltage at the inverting input terminal of the second operational amplifier U2 = VCC2×(R5 / (R4+R5)).

[0072] At this time, the charging current of the battery 20 in the first charging stage can be expressed as: I1=V2 / Rm, wherein V2 represents the voltage at the non-inverting input terminal of the second operational amplifier U2, and Rm represents the current sampling resistor of the battery.

[0073] When the battery voltage input to the non-inverting input terminal of the first operational amplifier U1 is greater than the first reference voltage input to the inverting input terminal, the first operational amplifier U1 outputs a high-level signal. At this time, it can be determined that the battery 20 is in the second charging stage, that is, the fast charging state. At this time, the first switch tube Q1 is in the on state, and the voltage of the inverting input terminal of the second operational amplifier U2 is determined according to the power supply VCC2, the resistor three R3, the resistor four R4 and the resistor five R5. The corresponding formula can be expressed as:

[0074] The voltage at the inverting input terminal of the second operational amplifier U2 = VCC2×(R5 / (R4||R3+R5)), where R4||R3 represents the total resistance value of resistor four R4 and resistor three R3 connected in parallel.

[0075] It should be noted that the voltage at the non-inverting input terminal of the second operational amplifier U2 when the battery 20 is in the second charging stage is greater than the voltage at the non-inverting input terminal of the second operational amplifier U2 when the battery 20 is in the first charging stage.

[0076] At this time, the charging current of the battery 20 in the second charging stage can be expressed as: I2=V2 / Rm. Since the voltage V2 of the non-inverting input terminal in the second charging stage is greater than the voltage of the non-inverting input terminal in the first charging stage, then I2>I1.

[0077] As for the charging maintenance unit 133, it includes a current limiting subunit 1331 and a switch control subunit 1332. The first end of the current limiting subunit 1331 is connected to the charging switching unit 132, the second end of the current limiting subunit 1331 and the battery voltage sampling module 11 are connected to the first input end of the switch control subunit 1332, the second input end of the switch control subunit 1332 is connected to the second end of the reference voltage module 12, and the output end of the switch control subunit 1332 is connected to the switch module 14;

[0078] The current limiting subunit 1331 is used to increase the input voltage of the first input terminal of the switch control subunit 1332 when the charging current is greater than the maximum current of the corresponding charging stage;

[0079] The switch control subunit 1332 is used to control the switch module 14 to be turned off so as to cut off the connection between the charging power source VCC1 and the battery 20 when the input voltage is greater than the second reference voltage output by the second end of the reference voltage module 12 .

[0080] In one embodiment, the current limiting subunit 1331 includes a first diode D1 and a resistor R7, and the switch control subunit 1332 includes a resistor R8, a resistor R9, a resistor R10 and a third operational amplifier U3;

[0081] The first end of the first diode D1 is connected to the charging switching unit 132, the second end of the first diode D1 is connected to the first end of the resistor R7, the second end of the resistor R7 is connected to the inverting input end of the third operational amplifier U3, and the inverting input end of the third operational amplifier U3 is connected to the battery voltage sampling module 11 through the resistor R9, the non-inverting input end of the third operational amplifier U3 is connected to the second end of the reference voltage module 12 through the resistor R10, the output end of the third operational amplifier U3 is connected to the first end of the resistor R8, and the second end of the resistor R8 is connected to the switch module 14.

[0082] In the embodiment of the present application, no matter the battery 20 is in the first charging stage or the second charging stage, when the second operational amplifier U2 outputs a high level signal, it indicates that the charging voltage of the battery 20 exceeds the maximum voltage corresponding to the charging stage. At this time, the first diode D1 and the resistor R7 pull up the battery voltage at the inverting input terminal of the third operational amplifier U3. Once the battery voltage is greater than the second reference voltage, the third operational amplifier U3 outputs a low level signal, and the second switch tube Q2 and the third switch tube Q3 are both turned off. At this time, the charging current of the battery 20 will gradually decrease to 0, avoiding excessive current of the battery 20 during the charging process, and improving the safety of the battery 20 charging process.

[0083] The charging control module 13 includes a charging comparison unit 131, a charging switching unit 132 and a charging maintenance unit 133. The first input end of the charging comparison unit 131 is connected to the battery voltage sampling module 11, the second input end is connected to the first end of the reference voltage module 12, and the output end is connected to the first end of the charging switching unit 132. The charging maintenance unit 133 is used to connect the second end of the charging switching unit 132 to the switch module 14; the charging comparison unit 131 is used to output a first comparison signal to the charging switching unit 132 when the battery voltage is less than the first reference voltage; and output a second comparison signal to the charging switching unit 133 when the battery voltage is greater than the first reference voltage. The charging comparison unit 131, the charging switching unit 132, is used to output a first-stage charging signal to the charging maintenance unit 133 based on the first comparison signal; and, based on the second comparison signal, output a second-stage charging signal to the charging maintenance unit 133; the charging maintenance unit 133 is used to control the switch module 14 to conduct the charging circuit of the charging power source VCC1 and the battery 20 when the charging power source VCC1 is connected; and, based on the first-stage charging signal, control the on and off of the switch module 14 to maintain the first-stage charging process of the battery 20; and, based on the second-stage charging signal, control the on and off of the switch module 14 to maintain the second-stage charging process of the battery 20. The circuit realizes charging in a slow charging mode with a small current in the first charging stage and charging in a fast charging mode with a large current in the second charging stage through the coordinated work of the charging comparison unit 131, the charging switching unit 132 and the charging maintenance unit 133, which can ensure that the battery 20 is always within the safe current range during the entire charging process, avoid damage to the battery caused by excessive current, and make the battery 20 safer during the charging process.

[0084] Next, the specific contents of the battery voltage sampling module 11 are introduced through an embodiment. Figure 3 As shown, the battery voltage sampling module 11 includes a resistor 11 R11, a resistor 12 R12 and a resistor 13 R13, and the resistance of the resistor 13 R13 is determined based on the threshold voltage at the start of the second charging stage;

[0085] The first end of the resistor R11 is connected to the battery 20, the resistor R12 is used to connect the second end of the resistor R11 and the first end of the resistor R13, the second end of the resistor R13 is grounded, and the common end of the resistor R12 and the resistor R13 is connected to the charging control module 13.

[0086] In the embodiment of the present application, the battery voltage sampling module 11 includes three resistors, of which resistor 11 R11, resistor 12 R12 and resistor 13 R13 are voltage divider resistors, which are mainly used to divide the collected battery voltage to prevent the battery voltage from being too high and causing damage to subsequent electronic components. The battery voltage collected by the battery voltage sampling module 11 can be expressed as:

[0087] Sampled battery voltage = (Vbat / (R7+R8+R9)) × R9

[0088] Wherein, Vbat represents the voltage at the output end of the battery, Figure 3 Vbat+ represents the positive output terminal of the battery, and Vbat- represents the negative output terminal of the battery.

[0089] For different types of batteries 20 (e.g., nickel-metal hydride batteries, lithium-ion batteries, polymer batteries, etc.), their charging characteristics and threshold voltages when starting the second charging stage are different. Since the resistance value of the resistor 13 R13 can be flexibly adjusted according to the threshold voltage of different batteries, the battery voltage sampling module 11 can be widely adapted to various types of batteries.

[0090] The battery voltage sampling module 11 includes a resistor 11 R11, a resistor 12 R12 and a resistor 13 R13, the resistance of the resistor 13 R13 is determined based on the threshold voltage at the start of the second charging stage; the first end of the resistor 11 R11 is connected to the battery 20, the resistor 12 R12 is used to connect the second end of the resistor 11 R11 and the first end of the resistor 13 R13, the second end of the resistor 13 R13 is grounded, and the common end of the resistor 12 R12 and the resistor 13 R13 is connected to the charging control module 13. The resistance of the resistor 13 R13 is determined based on the threshold voltage at the start of the second charging stage, which enables the battery voltage sampling module 11 to meet the sampling requirements of different types of batteries 20 and can be suitable for voltage sampling of different types of batteries 20.

[0091] The above embodiments are all introductions to the charging control module 13. Based on this, in order to protect the charging process of the battery 20 even if the battery 20 is reversely connected, in one embodiment, Figure 3 As shown, the charging protection circuit 10 further includes a reverse connection protection module 15, and the reverse connection protection module 15 includes a second diode D2;

[0092] A first end of the second diode D2 is connected to a common end of the resistor eleven R11 and the resistor twelve R12, and a second end of the second diode D2 is grounded.

[0093] In the embodiment of the present application, when the positive and negative poles of the battery 20 are reversely connected and the battery 20 is charged by the charging power supply VCC1, the charging protection circuit 10 can limit the charging current through the reverse connection protection module 15 to ensure that the battery 20 will not be burned when the battery 20 is reversely connected. Specifically, when the battery 20 is reversely connected, based on the unidirectional conductivity of the second diode D2, the second diode D2 will prevent the reverse current from flowing from the ground end to the common end of the resistor eleven R11 and the resistor twelve R12. In this way, the battery voltage collected by the battery voltage sampling module 11 can be limited, so that the battery voltage is less than the first reference voltage generated by the first end of the reference voltage module 12, the first operational amplifier U1 outputs a low level, the first switch tube Q1 is not turned on, and the charging power supply VCC1 can continue to charge the battery 20 with a small current. If the charging current exceeds the current threshold, that is, the voltage at the non-inverting input terminal of the second operational amplifier U2 is greater than the voltage at the inverting input terminal, then the second operational amplifier U2 outputs a high-level signal to control the switch module 14 to turn off, that is, the path between the charging power supply VCC1 and the battery 20 is cut off, so that the battery 20 will not be burned during the charging process, thereby realizing reverse connection protection of the battery 20.

[0094] The charging protection circuit 10 further includes a reverse connection protection module 15, which includes a second diode D2; a first end of the second diode D2 is connected to the common end of the resistor R10 and the resistor R11, and a second end of the second diode D2 is grounded. By connecting the reverse connection protection module 15 including a diode, the risk of component damage caused by reverse current can be effectively avoided, ensuring that the battery 20 will not be burned in the case of reverse connection, thereby extending the service life of the battery 20.

[0095] Next, the specific contents of the switch module 14 are introduced through an embodiment. Figure 3 As shown, the switch module 14 includes a resistor 14 R14, a resistor 15 R15, a resistor 16 R16, a second switch tube Q2 and a third switch tube Q3;

[0096] The first end of the second switch tube Q2 is connected to the first end of the resistor fourteen R14 and the charging control module 13, the second end of the second switch tube Q2 is connected to the first end of the resistor fifteen R15, the second end of the resistor fifteen R15 is respectively connected to the first end of the resistor sixteen R16 and the first end of the third switch tube Q3, the second end of the third switch tube Q3 and the second end of the resistor sixteen R16 are both connected to the charging power supply VCC1, the third end of the third switch tube Q3 is connected to the battery 20, and the third end of the second switch tube Q2 and the second end of the resistor fourteen R14 are both grounded.

[0097] When the charging power supply VCC1 is connected to the charging protection circuit 10, the third switch tube Q3 is not turned on, the battery voltage input to the inverting input terminal of the third operational amplifier U3 is 0V, the second reference voltage input to the non-inverting input terminal is greater than the battery voltage, and the output terminal of the third operational amplifier U3 outputs a high-level signal. At this time, the second switch tube Q2 is closed, the third switch tube Q3 is turned on, and the charging power supply VCC1 can charge the battery 20. During the normal charging process of the battery 20, the battery voltage is less than the second reference voltage, the third operational amplifier U3 continues to output a high-level signal, and the second switch tube Q2 and the third switch tube Q3 are both turned on. When the battery 20 is abnormally charged (the charging current is too large), the battery voltage is greater than the second reference voltage, the third operational amplifier U3 outputs a low-level signal, the second switch tube Q2 and the third switch tube Q3 are both turned off, and the charging current of the battery 20 gradually decreases to 0. When the charging current of the battery 20 is 0, the battery voltage is less than the second reference voltage. At this time, the second switch tube Q2 and the third switch tube Q3 can continue to be turned on. This can be repeated to enable the battery 20 to be charged with different charging currents in different charging stages.

[0098] The switch module 14 includes a resistor 14 R14, a resistor 15 R15, a resistor 16 R16, a second switch tube Q2 and a third switch tube Q3; the first end of the second switch tube Q2 is connected to the first end of the resistor 14 R14 and the charging control module 13, the second end of the second switch tube Q2 is connected to the first end of the resistor 15 R15, the second end of the resistor 15 R15 is respectively connected to the first end of the resistor 16 R16 and the first end of the third switch tube Q3, the second end of the third switch tube Q3 and the second end of the resistor 16 R16 are both connected to the charging power source VCC1, the third end of the third switch tube Q3 is connected to the battery 20, and the third end of the second switch tube Q2 and the second end of the resistor 14 R14 are both grounded. By setting two switch tubes, the circuit can be turned on during the charging process to ensure that the charging power source VCC1 can charge the battery 20. In addition, the switch module 14 is connected to the current limiting subunit 1331, and the switching action of the two switch tubes prevents the charging current of the battery 20 from being too large to cause damage to the battery 20, thereby ensuring the safety of the charging process.

[0099] For the reference voltage module 12, if Figure 3 As shown, the reference voltage module 12 includes a resistor 17 R17, a resistor 18 R18 and a resistor 19 R19, and the resistor 17 R17 is a sliding rheostat, and its resistance value can be adjusted based on different battery 20 requirements;

[0100] The first end of resistor R17 is connected to the power supply VCC2, the second end of resistor R17 is respectively connected to the first end of resistor R18 and the inverting input end of the first operational amplifier U1, the second end of resistor R18 is connected to the first end of resistor R19, and the second end of resistor R19 is grounded.

[0101] For the reference voltage module 12, the reference voltage module 12 inputs the first reference voltage to the inverting input terminal of the first operational amplifier U1 through the common terminal of the resistor 17 R17 and the resistor 18 R18. The resistor 10 R10 is connected to the third terminal of the resistor 17 R17, and the reference voltage module 12 inputs the second reference voltage to the non-inverting input terminal of the third operational amplifier U3 through the resistor 17 R17 and the resistor 10 R10. The reference voltage module 12 can also input the third reference voltage to the non-inverting input terminal of the fourth operational amplifier U4 through the common terminal of the resistor 18 R18 and the resistor 19 R19.

[0102] It should be noted that the power supply VCC2 can be provided directly by a power supply, or can be obtained by voltage conversion through the charging power supply VCC1. Figure 3 For the AC power supply AC, a transformer T can be connected between the AC power supply AC+ and AC-. After the transformer T transforms the voltage of the AC power supply, it is divided into two branches. In one branch, the output end of the transformer T is connected to the switch module 14 in the charging protection circuit 10 through the third diode D3, the fourth diode D4 and the first capacitor C1. The third diode D3 and the fourth diode D4 form a rectifier circuit to convert the AC power provided by the AC power supply AC into DC power, wherein the first capacitor C1 is used for filtering, and is connected to the second end of the resistor R16 and the second end of the third switch tube in the figure. In another branch, the fifth diode D5, the second capacitor C2, the third capacitor C3 and the voltage stabilizing chip U5 form a reference voltage circuit to provide power supply VCC2 for different modules (reference circuit structures of different modules). For example, the voltage required for the power supply VCC2 is 5V, 8V, etc. It should be noted that the voltage stabilizing chip U5 includes three ports a, b, and c. The a port is connected to the fifth diode D5 and the second capacitor C2 respectively, the b port is connected to the power supply VCC2 and the third capacitor C3 respectively, and the c port is grounded. Port a is the input voltage port (LINEVOLTAGE), port b is the voltage regulator (Voltage Regulator, VRGE), and port c is the ground terminal (COMMON).

[0103] In one embodiment, Figure 2As shown, the charging protection circuit 10 further includes a charging display module 16, which includes a current acquisition unit 161, a current comparison unit 162 and a light emitting diode LED. The input end of the current acquisition unit 161 is connected to the battery 20, the output end of the current acquisition unit 161 and the third end of the reference voltage module 12 are both connected to the input end of the current comparison unit 162, and the output end of the current comparison unit 162 is connected to the light emitting diode LED;

[0104] When the voltage corresponding to the current collected by the current collection unit 161 is greater than the third reference voltage generated by the third terminal of the reference voltage module 12, the battery 20 is in a charging state, and the current comparison unit 162 outputs a low-level signal; the low-level signal is used to control the light-emitting diode LED to be in a light-emitting state;

[0105] When the voltage corresponding to the current collected by the current collection unit 161 is less than the third reference voltage, the battery 20 is in a fully charged state, and the current comparison unit 162 outputs a high level signal; the high level signal is used to control the light-emitting diode LED to be in a non-luminous state.

[0106] In the embodiment of the present application, the current acquisition unit 161 includes a current sampling resistor Rm, and the current comparison unit 162 includes a fourth operational amplifier U4 and a resistor 20 R20. The first end of the current sampling resistor Rm is connected to the non-inverting input end of the second operational amplifier U2 and the negative electrode of the battery 20, the second end of the current sampling resistor Rm is connected to the inverting input end of the fourth operational amplifier U4, the non-inverting input end of the fourth operational amplifier U4 is connected to the common end of the resistor 18 R18 and the resistor 19 R19, the output end of the fourth operational amplifier U4 is connected to the first end of the resistor 20 R20, the second end of the resistor 20 R20 is connected to the first end of the light emitting diode LED, and the second end of the light emitting diode LED is connected to the power supply VCC2.

[0107] If the input voltage of the non-inverting input terminal of the fourth operational amplifier U4 is greater than the input voltage of the inverting input terminal, the fourth operational amplifier U4 outputs a high-level signal, and the third reference voltage generated by the third terminal of the reference voltage module 12 is greater than the voltage corresponding to the current collected by the current acquisition unit 161. At this time, the battery 20 is fully charged and the light-emitting diode LED is in a non-luminous state.

[0108] If the input voltage of the non-inverting input terminal of the fourth operational amplifier U4 is less than the input voltage of the inverting input terminal, the fourth operational amplifier U4 outputs a low-level signal, and the third reference voltage generated by the third terminal of the reference voltage module 12 is less than the voltage corresponding to the current collected by the current acquisition unit 161. At this time, when the battery 20 is in a normal charging process (including the battery 20 being in the first charging stage and the second charging stage), the light-emitting diode LED is in a light-emitting state.

[0109] The charging protection circuit 10 further includes a charging display module 16, which includes a current acquisition unit 161, a current comparison unit 162 and a light emitting diode LED. The input end of the current acquisition unit 161 is connected to the battery 20, the output end of the current acquisition unit 161 and the third end of the reference voltage module 12 are both connected to the input end of the current comparison unit 162, and the output end of the current comparison unit 162 is connected to the light emitting diode LED; when the voltage corresponding to the current collected by the current acquisition unit 161 is greater than the third reference voltage generated by the third end of the reference voltage module 12, the battery 20 is in a charging state, and the current comparison unit 162 outputs a low-level signal; the low-level signal is used to control the light emitting diode LED to be in a light-emitting state; when the voltage corresponding to the current collected by the current acquisition unit 161 is less than the third reference voltage, the battery 20 is in a fully charged state, and the current comparison unit 162 outputs a high-level signal; the high-level signal is used to control the light emitting diode LED to be in a non-light-emitting state. By setting up a charging display module 16, the current in the battery 20 is collected by the current collection unit 161 in the charging display module 16, and the voltage corresponding to the collected current is compared with the third reference voltage. Based on the comparison result, it is possible to accurately determine whether the battery 20 is full, and then use the on and off state of the light-emitting diode LED in the charging display module 16 to show the user whether the battery 20 is full, so that the user can understand the charging status of the battery 20 more intuitively.

[0110] Next, the working process of the charging protection circuit 10 is described in detail through a specific embodiment.

[0111] When the AC power source AC is connected, the third switch tube Q3 is not turned on, the battery voltage input to the inverting input terminal of the third operational amplifier U3 is 0V, and the output terminal of the third operational amplifier U3 outputs a high level. The high level signal turns on the second switch tube Q2 and the third switch tube Q3. At this time, the AC power source AC is rectified by the transformer T to form a charging power source VCC1 to charge the battery 20. The charging voltage of the battery 20 is relatively small, and the battery 20 is in the first charging stage. At the same time, the fourth operational amplifier U4 outputs a low level signal, and the light-emitting diode LED is in a light-emitting state.

[0112] When the battery 20 is in the first charging stage, the battery voltage input to the inverting input of the third operational amplifier U3 is less than the second reference voltage input to the non-inverting input, and the second switch tube Q2 and the third switch tube Q3 are in the on state. The first reference voltage input to the inverting input of the first operational amplifier U1 is greater than the battery voltage input to the non-inverting input, the first operational amplifier U1 outputs a low-level signal, and the first switch tube Q1 does not work. At this time, the voltage at the inverting input of the second operational amplifier U2 is VCC2×(R5 / (R4+R5)). For the current limiting process of the first charging stage, when the charging current of the battery 20 is higher than the maximum current of the first charging stage, the voltage at the non-inverting input of the second operational amplifier U2 is greater than the voltage at the inverting input, and a high-level signal is output, which will pull up the battery voltage at the inverting input of the third operational amplifier U3. In this way, the output of the third operational amplifier U3 outputs a low-level signal. The second switch tube Q2 and the third switch tube Q3 are both turned off. After the charging current of the battery 20 gradually decreases to 0, the battery voltage input to the inverting input terminal of the third operational amplifier U3 is less than the second reference voltage input to the non-inverting input terminal, and the second switch tube Q2 and the third switch tube Q3 are in the on state. In this way, the charging current of the battery 20 in the first charging stage can be limited.

[0113] When the battery voltage slowly rises to a certain voltage threshold (the voltage threshold is determined by the resistance value of the resistor thirteen R13), similarly, the battery voltage input to the inverting input of the third operational amplifier U3 is less than the second reference voltage input to the non-inverting input, and the second switch tube Q2 and the third switch tube Q3 are in the on state. The first reference voltage input to the inverting input of the first operational amplifier U1 is less than the battery voltage input to the non-inverting input, the first operational amplifier U1 outputs a high-level signal, and the first switch tube Q1 is turned on. At this time, the voltage at the inverting input of the second operational amplifier U2 is VCC2×(R5 / (R4||R3+R5)). For the current limiting process of the second charging stage, when the charging current of the battery 20 is higher than the maximum current of the second charging stage, the voltage at the non-inverting input of the second operational amplifier U2 is greater than the voltage at the inverting input, and a high-level signal is output, which will pull up the battery voltage at the inverting input of the third operational amplifier U3, so that the output of the third operational amplifier U3 outputs a low-level signal. The second switch tube Q2 and the third switch tube Q3 are both turned off. After the charging current of the battery 20 gradually decreases to 0, the battery voltage input to the inverting input terminal of the third operational amplifier U3 is less than the second reference voltage input to the non-inverting input terminal, and the second switch tube Q2 and the third switch tube Q3 are in the on state. In this way, the charging current of the battery 20 in the second charging stage can be limited.

[0114] When the battery 20 completes the charging process of the first charging stage and the second charging stage and the battery 20 is fully charged, the light emitting diode LED switches from a light emitting state to a non-light emitting state.

[0115] It should be noted that, among the reference voltages output by the reference voltage module 12 , the third reference voltage is greater than the second reference voltage, and the second reference voltage is greater than the first reference voltage.

[0116] In addition, continue to refer to Figure 3 , Vbat represents the positive output terminal of the battery, and Vbat- represents the negative output terminal of the battery. A fuse FU and a sixth diode D6 can also be set between the resistor R11 in the battery voltage sampling module 11, the third end of the third switch tube Q3 in the switch module 14 and the positive output terminal of the battery.

[0117] When a short circuit occurs in the charging protection circuit 10 or the battery connected thereto, the short circuit current will increase sharply instantly. The fuse FU will melt rapidly under the high temperature generated by the short circuit current, thereby cutting off the connection between the charging protection circuit 10 and the battery 20, preventing the short circuit current from causing serious damage to the battery and the circuit components in the charging protection circuit 10, and avoiding safety accidents such as overheating, fire, and even explosion caused by the short circuit.

[0118] In another embodiment, a charger is provided. The charger includes the charging protection circuit 10 involved in the above embodiment.

[0119] Optionally, the charger can be fixed at a set position and kept connected to the charging power source VCC1. For this situation, reference can be made to the charging pile of a new energy vehicle. Optionally, the charger can also be a portable charger, such as a charger for an electric vehicle, a mobile phone charger, etc.

[0120] The above content is a further detailed description of the embodiments of the present application in combination with specific / preferred implementation methods, and it cannot be determined that the specific implementation of the embodiments of the present application is limited to these descriptions. For ordinary technicians in the technical field to which the embodiments of the present application belong, without departing from the concept of the embodiments of the present application, it can also make several substitutions or modifications to these described implementation methods, and these substitutions or modifications should be regarded as belonging to the protection scope of the embodiments of the present application. In the description of this specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the various technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered as the scope recorded in this specification.

[0121] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0122] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A charging protection circuit, characterized in that: The charging protection circuit comprises: a battery voltage sampling module connected to the battery, a reference voltage module, a charging control module and a switch module; The switch module is used to connect the charging power source and the battery, the first input end, the second input end and the output end of the charging control module are respectively connected to the battery voltage sampling module, the first end of the reference voltage module and the switch module, and when the switch module is connected to the charging power source, the switch module conducts the charging circuit of the charging power source and the battery based on the control of the charging control module; The charging control module is used to control the on and off of the switch module when the battery voltage collected by the battery voltage sampling module is less than the first reference voltage generated by the first end of the reference voltage module, so that the battery is charged in the first charging stage; And, when the battery voltage is greater than the first reference voltage, the battery is switched from the first charging stage to the second charging stage, and the on and off of the switch module is controlled so that the battery is maintained in the second charging stage for charging; the charging current range of the first charging stage is smaller than the charging current range of the second charging stage.

2. The circuit according to claim 1, characterized in that The charging control module comprises a charging comparison unit, a charging switching unit and a charging maintenance unit, wherein the first input end of the charging comparison unit is connected to the battery voltage sampling module, the second input end is connected to the first end of the reference voltage module, and the output end is connected to the first end of the charging switching unit, and the charging maintenance unit is used to connect the second end of the charging switching unit to the switch module; The charging comparison unit is used to output a first comparison signal to the charging switching unit when the battery voltage is less than the first reference voltage; and output a second comparison signal to the charging switching unit when the battery voltage is greater than the first reference voltage; The charging switching unit is used to output a first-stage charging signal to the charging maintaining unit based on the first comparison signal; and output a second-stage charging signal to the charging maintaining unit based on the second comparison signal; The charging maintenance unit is used to control the switch module to conduct the charging circuit between the charging power supply and the battery when the charging power supply is connected; and is also used to control the conduction and shutdown of the switch module based on the first stage charging signal to maintain the first stage charging process of the battery; And, based on the second stage charging signal, the switch module is controlled to be turned on and off to maintain the second stage charging process of the battery.

3. The circuit according to claim 2, characterized in that The charging comparison unit includes a resistor 1, a resistor 2 and a first operational amplifier; The non-inverting input terminal of the first operational amplifier is connected to the battery voltage sampling module, and the inverting input terminal of the first operational amplifier is connected to the first terminal of the reference voltage module; The first end of the resistor 1 is connected to the power supply and the first end of the charging switching unit respectively, the second end of the resistor 1 is connected to the first end of the resistor 2 and the second end of the charging switching unit respectively, and the second end of the resistor 2 is connected to the output end of the first operational amplifier.

4. The circuit according to claim 2, characterized in that The charging switching unit includes a resistor three, a resistor four, a resistor five, a resistor six, a first switch tube and a second operational amplifier; The first end of the resistor three and the first end of the resistor four are both connected to the power supply, the second end of the resistor three is connected to the first end of the first switch tube, the second end of the first switch tube is connected to the output end of the charging comparison unit, the third end of the first switch tube, the second end of the resistor four, and the first end of the resistor five are all connected to the inverting input end of the second operational amplifier, the resistor six is ​​used to connect the non-inverting input end and the output end of the second operational amplifier, and the second end of the resistor five is grounded.

5. The circuit according to any one of claims 2 to 4, characterized in that: The charging maintenance unit comprises a current limiting subunit and a switch control subunit, wherein a first end of the current limiting subunit is connected to the charging switching unit, a second end of the current limiting subunit and the battery voltage sampling module are both connected to a first input end of the switch control subunit, a second input end of the switch control subunit is connected to a second end of the reference voltage module, and an output end of the switch control subunit is connected to the switch module; The current limiting subunit is used to increase the input voltage of the first input terminal of the switch control subunit when the charging current is greater than the maximum current of the corresponding charging stage; The switch control subunit is used to control the switch module to turn off when the input voltage is greater than the second reference voltage output by the second end of the reference voltage module, so as to cut off the connection between the charging power supply and the battery.

6. The circuit according to claim 5, characterized in that The current limiting subunit includes a first diode and a resistor seven, and the switch control subunit includes a resistor eight, a resistor nine, a resistor ten and a third operational amplifier; The first end of the first diode is connected to the charging switching unit, the second end of the first diode is connected to the first end of the resistor seven, the second end of the resistor seven is connected to the inverting input end of the third operational amplifier, and the inverting input end of the third operational amplifier is connected to the battery voltage sampling module through the resistor nine, the non-inverting input end of the third operational amplifier is connected to the second end of the reference voltage module through the resistor ten, the output end of the third operational amplifier is connected to the first end of the resistor eight, and the second end of the resistor eight is connected to the switch module.

7. The circuit according to any one of claims 1 to 4, characterized in that: The battery voltage sampling module includes a resistor 11, a resistor 12 and a resistor 13, and the resistance value of the resistor 13 is determined based on the threshold voltage at the start of the second charging stage; The first end of the resistor 11 is connected to the battery, the resistor 12 is used to connect the second end of the resistor 11 and the first end of the resistor 13, the second end of the resistor 13 is grounded, and the common end of the resistor 12 and the resistor 13 is connected to the charging control module.

8. The circuit according to any one of claims 1 to 4, characterized in that: The switch module includes a resistor 14, a resistor 15, a resistor 16, a second switch tube and a third switch tube; The first end of the second switch tube is connected to the first end of the resistor 14 and the charging control module, the second end of the second switch tube is connected to the first end of the resistor 15, the second end of the resistor 15 is respectively connected to the first end of the resistor 16 and the first end of the third switch tube, the second end of the third switch tube and the second end of the resistor 16 are both connected to the charging power supply, the third end of the third switch tube is connected to the battery, and the third end of the second switch tube and the second end of the resistor 14 are both grounded.

9. The circuit according to any one of claims 1 to 4, characterized in that: The charging protection circuit further includes a charging display module, which includes a current acquisition unit, a current comparison unit and a light emitting diode, wherein the input end of the current acquisition unit is connected to the battery, the output end of the current acquisition unit and the third end of the reference voltage module are both connected to the input end of the current comparison unit, and the output end of the current comparison unit is connected to the light emitting diode; When the voltage corresponding to the current collected by the current collection unit is greater than the third reference voltage generated by the third terminal of the reference voltage module, the battery is in a charging state, and the current comparison unit outputs a low-level signal; the low-level signal is used to control the light-emitting diode to be in a light-emitting state; When the voltage corresponding to the current collected by the current collection unit is less than the third reference voltage, the battery is in a fully charged state, and the current comparison unit outputs a high-level signal; the high-level signal is used to control the light-emitting diode to be in a non-luminous state.

10. A charger, characterized in that: The charger comprises the charging protection circuit according to any one of claims 1 to 9.

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