Charging wake-up circuit and lithium battery protection equipment

Abstract

The invention provides a charging wake-up circuit and a lithium battery protection device, and relates to the technical field of charging control, the charging wake-up circuit comprises a charging and discharging switch circuit, a low level holding circuit and a voltage difference conduction circuit, the voltage difference conduction circuit comprises a first port to a fourth port and a voltage difference conduction device; the first port is respectively connected with the positive electrode end of the lithium battery and the positive electrode end of the charging device; the second port is connected with one end of the charging and discharging switching circuit and is connected with the negative electrode end of the lithium battery; the third port is connected with the other end of the charging and discharging switching circuit and is connected with the negative electrode end of the charging device; the fourth port is connected with one end of the low-level holding circuit and is connected with a wake-up signal end; when the charging wake-up circuit is connected with the lithium battery and the charging device, a voltage difference conduction device between the first port and the fourth port of the voltage difference conduction circuit is in a conduction state, and the wake-up signal end is in a high level state. According to the invention, when the lithium battery is insufficient in power, charging can be continued without a charging wake-up operation.

Description

Technical Field

[0001] The present invention relates to the technical field of charging control, and in particular to a charging wake-up circuit and a lithium battery protection device. Background Art

[0002] As an important component of the car, the starting battery plays a vital role in the car. It is not only the key energy source for the vehicle to start from a standstill, but also plays a core role in the entire operation of the vehicle. It provides the necessary initial power for the electric motor, helping the vehicle to respond quickly and achieve efficient acceleration. At the same time, the starting battery is also responsible for storing and recovering the energy generated during braking. This regenerative braking system not only improves the efficiency of energy utilization, but also helps to extend the service life of the battery.

[0003] In the past, lead-acid batteries were usually used as starting batteries. Due to the characteristics of high pollution, poor low-temperature performance, low energy density, and short life, lead-acid batteries cannot adapt to the development trend of environmental protection, intelligence, and lightweight. Compared with lead-acid batteries, lithium batteries have the advantages of long life, small size, light weight, good high and low temperature performance, easy intelligent management, and long standby time. More and more cars use lithium batteries as starting batteries.

[0004] However, when the lithium battery voltage is too low, the power-off protection will be triggered. At this time, the battery protection board will not work to stop consuming power, thereby protecting the battery. For lithium batteries that trigger the power-off protection, they cannot be directly charged or connected through the positive and negative poles. The lithium battery needs to be charged and woken up first. Compared with lead-acid batteries, the charging and waking operation of lithium batteries is not only more troublesome, but also requires changing the user's usage habits, resulting in a poor user experience. Summary of the invention

[0005] The present invention provides a charging awakening circuit to solve the problem that a charging awakening operation is required to continue charging after a lithium battery triggers power-off protection.

[0006] In a first aspect, the present invention provides a charging wake-up circuit, which is used to connect a lithium battery and a charging device to charge and wake up the lithium battery; The charging wake-up circuit includes a charging and discharging switch circuit, a low-level holding circuit and a voltage difference conduction circuit, wherein the voltage difference conduction circuit includes a first port to a fourth port and a voltage difference conduction device; the first port is used to connect the positive terminal of the lithium battery and the positive terminal of the charging device respectively; the second port is connected to one end of the charging and discharging switch circuit and is used to connect the negative terminal of the lithium battery; the third port is connected to the other end of the charging and discharging switch circuit and is used to connect the negative terminal of the charging device; the fourth port is connected to one end of the low-level holding circuit and is used to connect the wake-up signal end; the other end of the low-level holding circuit is grounded; When the lithium battery triggers the power-off protection, the charge and discharge switch circuit is in the off state, and the voltage difference conduction device between the first port and the fourth port of the voltage difference conduction circuit is in the off state, and when the charging wake-up circuit is connected to the lithium battery and the charging device, the voltage difference conduction device between the first port and the fourth port of the voltage difference conduction circuit is in the on state, so that the wake-up signal end is in a high level state, and then under the effect of the wake-up signal end being in the high level state, the charge and discharge switch circuit is in the on state.

[0007] In one possible implementation, the pressure differential conduction circuit includes a first branch and a second branch connected to each other, and the first branch and the second branch both include a pressure differential conduction device; the first end of the first branch is the first port of the pressure differential conduction circuit, and the second end of the first branch is the fourth port of the pressure differential conduction circuit; the first end of the second branch is the second port of the pressure differential conduction circuit, and the second end of the second branch is the third port of the pressure differential conduction circuit.

[0008] In one possible implementation, the first branch includes a first resistor, a second resistor and a first voltage difference conduction device; the first voltage difference conduction device is a PNP type transistor; one end of the first resistor is respectively connected to the emitter of the first voltage difference conduction device and the first end of the first branch, the other end of the first resistor is respectively connected to one end of the second resistor and the base of the first voltage difference conduction device, the collector of the first voltage difference conduction device is the second end of the first branch, and the other end of the second resistor is connected to the second branch.

[0009] In one possible implementation, the second branch includes a third resistor, a fourth resistor and a second voltage difference conduction device; the second voltage difference conduction device is an NPN transistor; one end of the third resistor is the first end of the second branch, the other end of the third resistor is respectively connected to one end of the fourth resistor and the base of the second voltage difference conduction device, the other end of the fourth resistor is respectively connected to the emitter of the second voltage difference conduction device and the second end of the second branch, and the collector of the second voltage difference conduction device is connected to the first branch.

[0010] In one possible implementation, the charge and discharge switch circuit includes a charging switch circuit and a discharging switch circuit; one end of the discharging switch circuit is respectively connected to the second port of the voltage difference conduction circuit and the negative terminal of the lithium battery, the other end of the discharging switch circuit is connected to one end of the charging switch circuit, and the other end of the charging switch circuit is respectively connected to the third port of the voltage difference conduction circuit and the negative terminal of the charging device.

[0011] In a possible implementation, the charging switch circuit includes a first switch and a first diode; the first switch is connected in parallel with the first diode.

[0012] In a possible implementation, the discharge switch circuit includes a second switch and a second diode; the second switch is connected in parallel with the second diode.

[0013] In a possible implementation, the low level holding circuit includes a fifth resistor; one end of the fifth resistor is connected to the fourth port and the wake-up signal end respectively, and the other end of the fifth resistor is grounded.

[0014] In a possible implementation, the wake-up signal terminal is a power enable pin in a power chip.

[0015] In a second aspect, the present invention provides a lithium battery protection device, such as any charging wake-up circuit provided in the first aspect.

[0016] The present invention provides a charging wake-up circuit, which is mainly used in a lithium battery management system and can solve the problem that the lithium battery cannot be directly charged when the power-off protection is triggered due to low power. The charging wake-up circuit includes a voltage difference conduction circuit, which is arranged between the lithium battery and the charging device. By utilizing the voltage difference between the working voltage of the lithium battery and the working voltage of the charging device, the voltage difference conduction device in the voltage difference conduction circuit can be turned on, thereby pulling the wake-up signal end to a high level. In this way, under the action of the high-level signal at the wake-up signal end, the lithium battery can be automatically charged and awakened without the need to perform conventional lithium battery wake-up operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 It is a structural schematic diagram of a charging wake-up circuit provided by an embodiment of the present invention; Figure 2 It is a structural schematic diagram of a voltage difference conduction circuit of a charging wake-up circuit provided by an embodiment of the present invention; Figure 3 The present invention provides a circuit diagram of a charging wake-up circuit. DETAILED DESCRIPTION

[0019] In order to enable people in the technical field to better understand the present solution, the technical solution in the embodiment of the present solution will be clearly described below in conjunction with the drawings in the embodiment of the present solution. Obviously, the described embodiment is an embodiment of a part of the present solution, not all of the embodiments. Based on the embodiments in the present solution, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present solution.

[0020] The term "including" and any other variations in the specification and claims of this solution and the above drawings mean "including but not limited to", and is intended to cover non-exclusive inclusions and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0021] The following is a detailed description of the implementation of the present invention in conjunction with the specific drawings: like Figure 1 As shown, the charging wake-up circuit in the present application can be used to connect a lithium battery and a charging device to wake up the lithium battery, referring to Figure 1 The charging wake-up circuit includes a charging and discharging switch circuit 1, a low-level holding circuit 2 and a voltage difference conduction circuit 3, wherein the voltage difference conduction circuit 3 includes a first port to a fourth port and a voltage difference conduction device; the first port is used to connect the positive terminal of the lithium battery and the positive terminal of the charging device respectively; the second port is connected to one end of the charging and discharging switch circuit 1, and is used to connect the negative terminal of the lithium battery; the third port is connected to the other end of the charging and discharging switch circuit 1, and is used to connect the negative terminal of the charging device; the fourth port is connected to one end of the low-level holding circuit 2, and is used to connect the wake-up signal end; the other end of the low-level holding circuit 2 is grounded.

[0022] When the voltage of the lithium battery is too low, it will trigger the power-off protection, causing the charge and discharge switch circuit 1 to be disconnected. At this time, when the lithium battery that triggers the power-off protection is connected to the charging device, due to the voltage difference between the negative terminal of the lithium battery and the negative terminal of the charging device, and the voltage difference meets the conduction condition of the voltage difference conduction device, the voltage difference conduction device can be turned on, so that the wake-up signal end is in a high level state, thereby controlling the charge and discharge switch circuit 1 to be turned on through the high level state.

[0023] In a possible implementation, the pressure differential conduction circuit 3 includes a first branch 4 and a second branch 5 connected to each other, and the first branch 4 and the second branch 5 both include a pressure differential conduction device; the first end of the first branch 4 is the first port of the pressure differential conduction circuit 3, and the second end of the first branch 4 is the fourth port of the pressure differential conduction circuit 3; the first end of the second branch 5 is the second port of the pressure differential conduction circuit 3, and the second end of the second branch 5 is the third port of the pressure differential conduction circuit 3.

[0024] The voltage difference conduction circuit 3 is used to pull the wake-up signal end to a high level through the voltage difference between the negative terminal of the lithium battery and the negative terminal of the charging device, wherein the connection relationship between the first branch 4 and the second branch 5 is as follows: Figure 2As shown, the first branch 4 is used to pull the wake-up signal end to a high level after the pressure difference conduction device contained in the first branch 4 meets the conduction requirement, and after the second branch 5 collects the voltage difference between the negative terminal of the lithium battery and the negative terminal of the charging device, the pressure difference conduction device contained in the second branch 5 meets the conduction requirement, thereby making the pressure difference conduction device contained in the first branch 4 meet the conduction requirement.

[0025] Figure 3 A circuit diagram of a charging wake-up circuit provided by an embodiment of the present invention, wherein the connection relationship among the charging and discharging switch circuit 1, the low level holding circuit 2 and the voltage difference conduction circuit 3 is as shown in FIG. Figure 3 shown.

[0026] In a possible implementation, the first branch 4 includes a first resistor R13, a second resistor R12 and a first voltage difference conduction device Q6; the first voltage difference conduction device Q6 is a PNP type transistor; one end of the first resistor R13 is respectively connected to the emitter of the first voltage difference conduction device Q6 and the first end of the first branch 4, the other end of the first resistor R13 is respectively connected to one end of the second resistor R12 and the base of the first voltage difference conduction device Q6, the collector of the first voltage difference conduction device Q6 is the second end of the first branch 4, and the other end of the second resistor R12 is connected to the second branch 5.

[0027] See also Figure 3 , with P- as the reference point, the first resistor in this embodiment is Figure 3 The second resistor is R13 in Figure 3 R12 in the first voltage difference conduction device is Figure 3 In Q6, the resistance values ​​of the first resistor R13 and the second resistor R12 are set so that the voltage at point B is 26.3V. At this time, the base-emitter voltage difference of the first voltage difference conduction device Q6 is -0.7V, which meets the conduction condition of the PNP transistor, and the first voltage difference conduction device Q6 is turned on.

[0028] In a possible implementation, the second branch 5 includes a third resistor R11, a fourth resistor R10 and a second voltage difference conduction device Q5; the second voltage difference conduction device Q5 is an NPN transistor; one end of the third resistor R11 is the first end of the second branch 5, and the other end of the third resistor R11 is respectively connected to one end of the fourth resistor R10 and the base of the second voltage difference conduction device Q5, and the other end of the fourth resistor R10 is respectively connected to the emitter of the second voltage difference conduction device Q5 and the second end of the second branch 5, and the collector of the second voltage difference conduction device Q5 is connected to the first branch 4.

[0029] See also Figure 3 , with P- as the reference point, the third resistor in this embodiment is Figure 3 R11 in the fourth resistor is Figure 3R10 in the second voltage difference conduction device is Figure 3 In Q5, by setting the resistance values ​​of the third resistor R11 and the fourth resistor R10, the voltage at point A is 0.7V. At this time, the base-emitter voltage difference of the second voltage difference conduction device Q5 is 0.7V, which meets the conduction condition of the NPN transistor, and the second voltage difference conduction device Q5 is turned on.

[0030] In a possible implementation, the charge and discharge switch circuit 1 includes a charging switch circuit and a discharging switch circuit; one end of the discharging switch circuit is respectively connected to the second port of the voltage difference conduction circuit 3 and the negative end of the lithium battery, the other end of the discharging switch circuit is connected to one end of the charging switch circuit, and the other end of the charging switch circuit is respectively connected to the third port of the voltage difference conduction circuit 3 and the negative end of the charging device.

[0031] In a possible implementation, the charging switch circuit includes a first switch and a first diode; the first switch is connected in parallel with the first diode.

[0032] In a possible implementation, the discharge switch circuit includes a second switch and a second diode; the second switch is connected in parallel with the second diode.

[0033] See also Figure 3 The direction of the diode in the discharge switch is different from that of the diode in the charge switch. When the charge switch and the discharge switch are disconnected, the charge and discharge switch circuit 1 is in an off state.

[0034] Optionally, the charging switch and the discharging switch may be MOSFETs or relays, or other switching devices that can be controlled by a circuit.

[0035] Optionally, when the first switch is disconnected from the second switch, the first diode is connected in series with the second diode, and the directions of the first diode and the second diode are different.

[0036] In a possible implementation, the low level holding circuit 2 includes a fifth resistor R15; one end of the fifth resistor R15 is connected to the fourth port and the wake-up signal end respectively, and the other end of the fifth resistor R15 is grounded.

[0037] Optionally, the function of the low level holding circuit 2 is to keep the wake-up signal terminal in a low level state when the first voltage difference conduction device Q6 is disconnected.

[0038] In a possible implementation, the wake-up signal terminal is a power enable pin in a power chip.

[0039] In a second aspect, the present invention provides a lithium battery protection device, such as any charging wake-up circuit provided in the first aspect.

[0040] See also Figure 3When the lithium battery does not trigger any protection, the charging switch and the discharging switch are closed, the lithium battery works normally, the positive pole B+ and the negative pole P- can be connected to an external load, the lithium battery discharges normally, and can also be connected to an external charging device, the lithium battery charges normally. When the external charging device is connected, the voltage of B- is consistent with that of P-, the voltage of point A is 0V, the second voltage difference conduction device Q5 is in the off state, the voltage of point B is consistent with that of B+, the first voltage difference conduction device Q6 is in the off state, the wake-up signal terminal Charge_IG is pulled to a low level by the low level holding circuit 2, and the charging wake-up signal is invalid.

[0041] When the lithium battery triggers the power-down protection, the charging switch and the discharging switch are both disconnected, and the lithium battery enters the dormant state. When the positive pole B+ and the negative pole P- are connected to an external load, the lithium battery is still in the dormant state and cannot work normally. When the external charging device is connected, there is a voltage of 10V between B- and P-. By setting the resistance values ​​of the third resistor R11 and the fourth resistor R10, the voltage at point A is 0.7V, and the second voltage difference conduction device Q5 is turned on. By setting the resistance values ​​of the first resistor R13 and the second resistor R12, the voltage at point B is 26.3V. The first voltage difference conduction device Q6 is turned on, and the wake-up signal terminal is connected to B+ and is pulled to a high level. The charging wake-up signal is valid. At this time, the charging wake-up signal controls the charging switch and the discharging switch to be closed through the single-chip microcomputer and the control circuit or other circuit structures, and the lithium battery starts to charge normally.

[0042] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A charging wake-up circuit, characterized in that: The charging wake-up circuit is used to connect the lithium battery and the charging device to charge and wake up the lithium battery; The charging wake-up circuit includes a charging and discharging switch circuit, a low-level holding circuit and a voltage difference conduction circuit, wherein the voltage difference conduction circuit includes a first port, a second port, a third port, a fourth port, and a voltage difference conduction device; the first port is used to connect the positive terminal of the lithium battery and the positive terminal of the charging device respectively; the second port is connected to one end of the charging and discharging switch circuit and is used to connect the negative terminal of the lithium battery; the third port is connected to the other end of the charging and discharging switch circuit and is used to connect the negative terminal of the charging device; the fourth port is connected to one end of the low-level holding circuit and is used to connect the wake-up signal end; the other end of the low-level holding circuit is grounded; When the lithium battery enters the power-off protection state, the charge and discharge switch circuit is in the disconnected state, and the voltage difference conduction device between the first port and the fourth port of the voltage difference conduction circuit is in the disconnected state, and when the charging wake-up circuit is connected to the lithium battery and the charging device, the voltage difference conduction device between the first port and the fourth port of the voltage difference conduction circuit is in the on state, so that the wake-up signal end is in a high level state, and then under the effect of the wake-up signal end being in the high level state, the charge and discharge switch circuit is in the on state.

2. The charging wake-up circuit according to claim 1, characterized in that: The voltage difference conduction circuit comprises a first branch and a second branch connected to each other, and the first branch and the second branch both comprise a voltage difference conduction device; The first end of the first branch is the first port of the voltage difference conduction circuit, and the second end of the first branch is the fourth port of the voltage difference conduction circuit; The first end of the second branch is the second port of the voltage difference conduction circuit, and the second end of the second branch is the third port of the voltage difference conduction circuit.

3. The charging wake-up circuit according to claim 2, characterized in that: The first branch includes a first resistor, a second resistor and a first voltage difference conduction device; the first voltage difference conduction device is a PNP type transistor; One end of the first resistor is respectively connected to the emitter of the first voltage difference conduction device and the first end of the first branch, the other end of the first resistor is respectively connected to one end of the second resistor and the base of the first voltage difference conduction device, the collector of the first voltage difference conduction device is the second end of the first branch, and the other end of the second resistor is connected to the second branch.

4. The charging wake-up circuit according to claim 2, characterized in that: The second branch includes a third resistor, a fourth resistor and a second voltage difference conduction device; the second voltage difference conduction device is an NPN transistor; One end of the third resistor is the first end of the second branch, the other end of the third resistor is respectively connected to one end of the fourth resistor and the base of the second voltage difference conduction device, the other end of the fourth resistor is respectively connected to the emitter of the second voltage difference conduction device and the second end of the second branch, and the collector of the second voltage difference conduction device is connected to the first branch.

5. The charging wake-up circuit according to claim 1, characterized in that: The charge and discharge switch circuit includes a charge switch circuit and a discharge switch circuit; One end of the discharge switch circuit is connected to the second port of the voltage difference conduction circuit and the negative terminal of the lithium battery respectively, the other end of the discharge switch circuit is connected to one end of the charging switch circuit, and the other end of the charging switch circuit is connected to the third port of the voltage difference conduction circuit and the negative terminal of the charging device respectively.

6. The charging wake-up circuit according to claim 5, characterized in that: The charging switch circuit includes a first switch and a first diode; the first switch is connected in parallel with the first diode.

7. The charging wake-up circuit according to claim 1, characterized in that: The discharge switch circuit includes a second switch and a second diode; the second switch is connected in parallel with the second diode.

8. The charging wake-up circuit according to claim 1, characterized in that: The low level holding circuit comprises a fifth resistor; One end of the fifth resistor is connected to the fourth port and the wake-up signal end respectively, and the other end of the fifth resistor is grounded.

9. The charging wake-up circuit according to claim 1, characterized in that: The wake-up signal terminal is a power enable pin in the power chip.

10. A lithium battery protection device, characterized in that: The lithium battery protection device comprises a charging wake-up circuit as claimed in any one of claims 1 to 9.

Images