Charging and discharging protection circuit and charging and discharging protection system

Abstract

The utility model relates to a charge and discharge protection circuit and a charge and discharge protection system, the charge and discharge protection circuit comprises a fuse and an overvoltage protection unit, the first end of the fuse is used for being electrically connected with a charge input end, the second end of the fuse is used for being electrically connected with a battery management system, and the battery management system is used for performing energy management on a cell battery. The first end of the overvoltage protection unit is electrically connected with the first end of the fuse, the second end of the overvoltage protection unit is used for being externally connected with a preset power supply, the third end of the overvoltage protection unit is used for being electrically connected with the battery management system, and the fourth end of the overvoltage protection unit is used for being electrically connected with the battery management system and the grounding end of the cell battery. The overvoltage protection unit is used for receiving a voltage control signal output by the battery management system to control the branch circuit where the overvoltage protection unit is located to be conducted so as to enable the fuse to be fused, and by arranging the overvoltage protection unit, when the charging voltage of the cell battery is too large, the branch circuit where the overvoltage protection unit is located can be controlled to be rapidly conducted so as to enable the fuse to be fused. And the safety of the whole charging process is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of charge and discharge, in particular to a charge and discharge protection circuit and a charge and discharge protection system. Background Art

[0002] As the capacity of facilities and equipment such as energy storage and electric vehicle lithium batteries increases, the charging and discharging currents of lithium batteries are also increasing, and the voltage is getting higher and higher. The active chemical properties of lithium batteries make it very important for lithium batteries to work safely.

[0003] Most of the existing three-terminal fuses use resistor-like heating and then conduct heat to the fuse to blow. When the overcharge protection mechanism is triggered, the heating resistor needs to transfer heat to the fuse body, which takes a long time to blow. In addition, there are defects such as severe heat dissipation in low-temperature environments and the inability to blow, which increases the probability of lithium battery fire and explosion, and the safety needs to be improved.

[0004] The above contents are only used to assist in understanding the technical solution of the present utility model and do not constitute an admission that the above contents are prior art. Utility Model Content

[0005] The utility model provides a charge and discharge protection circuit and a charge and discharge protection system, aiming to improve the safety of the above-mentioned lithium battery charging process.

[0006] In order to achieve the above object, the utility model provides a charge and discharge protection circuit, which includes:

[0007] A fuse, wherein a first end of the fuse is used to be electrically connected to a charging input end, and a second end of the fuse is used to be electrically connected to a battery management system, and the battery management system is used to perform energy management on the battery cell;

[0008] An overvoltage protection unit, wherein a first end of the overvoltage protection unit is electrically connected to a first end of the fuse, a second end of the overvoltage protection unit is used for externally connecting to a preset power supply, a third end of the overvoltage protection unit is used for electrically connecting to a battery management system, and a fourth end of the overvoltage protection unit is used for electrically connecting to a ground terminal of the battery management system and a battery cell, respectively;

[0009] The overvoltage protection unit is used to receive the voltage control signal output by the battery management system and control the conduction of the branch where it is located to make the fuse blow. The voltage control signal is generated by the battery management system when the battery cell is over-voltage.

[0010] In one embodiment, the overvoltage protection unit includes a thyristor surge suppressor and a switch tube control unit, the positive terminal of the thyristor surge suppressor serves as the first end of the overvoltage protection unit, the negative terminal of the thyristor surge suppressor serves as the fourth end of the overvoltage protection unit, the control end of the thyristor surge suppressor is electrically connected to the first end of the switch tube control unit, the second end of the switch tube control unit serves as the second end of the overvoltage protection unit, and the third end of the switch tube control unit serves as the third end of the overvoltage protection unit.

[0011] In one embodiment, the switch tube control unit uses an NPN transistor, the emitter of the NPN transistor is the first end of the switch tube control unit, the collector of the NPN transistor is the second end of the overvoltage protection unit, and the base of the NPN transistor is the third end of the overvoltage protection unit.

[0012] In one embodiment, the switch tube control unit uses an NMOS switch tube, the source of the NMOS switch tube is the first end of the switch tube control unit, the drain of the NMOS switch tube is the second end of the overvoltage protection unit, and the gate of the NMOS switch tube is the third end of the overvoltage protection unit.

[0013] In one embodiment, the fuse is also used to blow when the battery cell has an overcurrent.

[0014] In addition, a charge and discharge protection system is also provided, comprising the above-mentioned charge and discharge protection circuit, a battery management system and a battery cell, wherein the battery management system is also electrically connected to the positive terminal of the battery cell;

[0015] The battery management system is used to generate a voltage control signal when the battery cell is over-voltage;

[0016] The charge and discharge protection circuit is used to receive the voltage control signal output by the battery management system, and control the conduction of its own branch according to the voltage control signal to make the fuse blow.

[0017] In one embodiment, the battery management system includes an electrically connected switch control circuit and a battery energy management unit, and a switch control circuit is arranged between the second end of the fuse and the positive end of the battery cell, and the switch control circuit is used to control the charging and discharging of the battery cell.

[0018] In one embodiment, the switch control circuit is a MOS switch unit.

[0019] In one embodiment, the MOS switch unit is an NMOS switch unit.

[0020] The above-mentioned charge and discharge protection circuit includes a fuse and an overvoltage protection unit. The first end of the fuse is used to be electrically connected to the charging input end, the second end of the fuse is used to be electrically connected to the battery management system, the battery management system is used to manage the energy of the battery cell, the first end of the overvoltage protection unit is electrically connected to the first end of the fuse, the second end of the overvoltage protection unit is used to be externally connected to a preset power supply, the third end is used to be electrically connected to the battery management system, the fourth end of the overvoltage protection unit is used to be electrically connected to the ground end of the battery management system and the battery cell respectively, and the overvoltage protection unit is used to receive the voltage control signal output by the battery management system to control the branch where it is located to be turned on, so that the fuse is blown. The voltage control signal is generated by the battery management system when the battery cell is over-voltage. The above-mentioned charge and discharge protection circuit will cause the fuse itself to blow when the charging over-current or the discharging over-current occurs. By setting the overvoltage protection unit, when the charging voltage of the battery cell is too large, the branch where the overvoltage protection unit is located can be controlled to be quickly turned on, thereby discharging the power charge at both ends of the battery cell, generating a large discharge current, thereby causing the above-mentioned fuse to blow quickly (i.e., reaching the melting thermal energy value). Compared with the traditional technical solution of conducting heat to the fuse by heating the heating resistor, it can further ensure that the fuse can blow quickly when the charging over-voltage occurs in a low temperature environment, thereby improving the safety of the entire charging and discharging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic block diagram of the circuit structure of a charge and discharge protection circuit provided by the utility model;

[0022] Figure 2 A schematic block diagram of the circuit structure of another charge and discharge protection circuit provided by the utility model;

[0023] Figure 3 A schematic block diagram of the circuit structure of another charge and discharge protection circuit provided by the utility model;

[0024] Figure 4 The present invention provides a circuit structure schematic block diagram of a charge and discharge protection system.

[0025] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the scheme in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0028] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0029] In addition, if the description of "first", "second", etc. is involved in the utility model, it is only used for descriptive purposes (such as for distinguishing the same or similar elements), and cannot be understood as indicating or implying its relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0030] like Figure 1 As shown, a charge and discharge protection circuit 100 is provided, comprising:

[0031] A fuse 110, wherein a first end of the fuse 110 is electrically connected to a charging input end, and a second end of the fuse 110 is electrically connected to a battery management system 140, and the battery management system 140 is used to perform energy management on the battery cell 120;

[0032] An overvoltage protection unit 130, wherein the first end of the overvoltage protection unit 130 is electrically connected to the first end of the fuse 100, the second end of the overvoltage protection unit 130 is used for an external preset power supply VCC, the third end of the overvoltage protection unit 130 is used for electrically connecting to the battery management system 140, and the fourth end of the overvoltage protection unit 130 is used for electrically connecting to the ground ends of the battery management system 140 and the battery cell 120, respectively.

[0033] The overvoltage protection unit 130 is used to receive a control signal output by the battery management system 140 to control the branch where it is located to be turned on so as to blow the fuse 100. The control signal is generated by the battery management system 140 when the battery cell 120 is overvoltage.

[0034] The second terminal and the third terminal of the overvoltage protection unit 130 are used to receive the voltage control signal output by the battery management system 140, and the fourth terminal of the overvoltage protection unit 130 is equivalent to the ground terminal.

[0035] When the charging or discharging overcurrent occurs in the charging and discharging protection circuit 100, the fuse itself blows. By setting the overvoltage protection unit 130, when the charging voltage of the battery cell 120 is too large, the branch where the overvoltage protection unit 130 is located can be controlled to be quickly turned on, thereby discharging the power charge at both ends of the battery cell 120, generating a large discharge current, thereby causing the fuse 110 to blow quickly (i.e., reaching the melting heat energy value). Compared with the traditional technical solution of conducting heat to the fuse by heating the heating resistor, the resistance wire is omitted, which can further ensure that when the charging and discharging overvoltage occurs in a low temperature environment, the fuse 110 can be quickly and spontaneously blown (microsecond melting time), which greatly reduces the probability of explosion of the battery cell 120 and improves the safety of the entire charging and discharging process.

[0036] In one embodiment, Figure 1 As shown, the overvoltage protection unit 130 includes a thyristor surge suppressor 132 and a switch tube control unit 134, the positive terminal of the thyristor surge suppressor 132 serves as the first terminal of the overvoltage protection unit 130, the negative terminal of the thyristor surge suppressor 132 serves as the fourth terminal of the overvoltage protection unit 130, and the control terminal of the thyristor surge suppressor 132 is electrically connected to the first terminal of the switch tube control unit 134.

[0037] The second end of the switch control unit 134 serves as the second end of the overvoltage protection unit 130 , and the third end of the switch control unit 134 serves as the third end of the overvoltage protection unit 130 .

[0038] In the present embodiment, a thyristor surge suppressor 132 and a switch tube control unit 134 are provided. Since the thyristor surge suppressor 132 is similar to the principle of a thyristor, which is equivalent to a positive feedback circuit composed of a PNP switch tube and an NPN switch tube, the more carriers are excited by the PN junction, the larger the on-state current is, and the smaller the on-state internal resistance is. Therefore, when the switch tube control unit 134 receives the control signal output by the battery management system 140, it generates a corresponding current control signal and outputs it to the thyristor surge suppressor 132. The control end of the thyristor surge suppressor 132 receives the current control signal and is turned on. At this time, the branch where the thyristor surge suppressor 132 is located is turned on, thereby discharging the power supply charge at both ends of the battery cell 120, generating a large discharge current, thereby causing the above-mentioned fuse 110 to melt quickly (i.e., reaching the melting heat energy value), which greatly reduces the possibility of explosion of the battery cell 120.

[0039] Among them, since the thyristor surge suppressor 132 is a current-controlled device, the thyristor surge suppressor 132 has the characteristic of large conduction current. Therefore, when the branch is turned on, it can quickly discharge the power charge at both ends of the discharge cell battery 120, generate a large discharge current, and can instantly make the fuse 110 reach its own melting thermal energy value and melt, and the low-temperature reliability is greatly enhanced. Compared with the traditional technical solution of conducting heat to the fuse by heating the heating resistor, it can further ensure that the fuse 110 can be quickly melted when the charging and discharging overvoltage occurs in a low-temperature environment, thereby improving the safety of the entire charging process.

[0040] The thyristor surge suppressor 132 may also be replaced by a MOS switch tube. However, when a MOS switch tube is used, the overcurrent carrying capacity of the MOS switch tube is required to be extremely high, which results in a surge in the overall hardware cost.

[0041] In one embodiment, Figure 2 As shown, the switch tube control unit 134 adopts an NPN transistor, the emitter of the NPN transistor is the first end of the switch tube control unit 134, the collector of the NPN transistor is the second end of the overvoltage protection unit 130, and the base of the NPN transistor is the third end of the overvoltage protection unit 130.

[0042] In this embodiment, the switch tube control unit 134 further adopts an NPN-type transistor, which is a current-controlled component, and the base of the NPN transistor only needs a very small current to be controlled. Therefore, through the cooperation between the NPN transistor and the thyristor surge suppressor 132, the battery management system 140 can quickly control the NPN transistor to be turned on, and then the NPN transistor can control the thyristor surge suppressor 132 to be turned on quickly, so that the thyristor surge suppressor 132 can quickly discharge the power charge at both ends of the battery cell 120, generate a large discharge current, and instantly make the fuse 110 reach its own melting heat energy value and melt, thereby greatly reducing the probability of explosion of the battery cell 120.

[0043] In one embodiment, Figure 3 As shown, the switch tube control unit 134 adopts an NMOS switch tube, the source of the NMOS switch tube is the first end of the switch tube control unit 134, the drain of the NMOS switch tube is the second end of the overvoltage protection unit 130, and the gate of the NMOS switch tube is the third end of the overvoltage protection unit 130.

[0044] In this embodiment, an NMOS switch tube is used, which increases the hardware cost. The NMOS switch tube receives the voltage control signal output by the battery management system 140 to generate a corresponding current control signal, and outputs it to the thyristor surge suppressor 132 .

[0045] In one embodiment, the fuse 100 is also used to melt when the battery cell 120 has an overcurrent.

[0046] In addition, if Figure 4 As shown, a charge and discharge protection system 200 is also provided, including the above-mentioned charge and discharge protection circuit 100, a battery management system 140 and a battery cell 120, and the battery management system 140 is also electrically connected to the positive terminal of the battery cell 120.

[0047] The battery management system 140 is used to generate a control signal when the battery cell 120 is over-voltage.

[0048] The charge and discharge protection circuit 100 is used to receive the voltage control signal output by the battery management system 140, and control the branch where the circuit is located to be turned on according to the voltage control signal, so that the fuse 100 is blown.

[0049] In one embodiment, Figure 4 As shown, the battery management system 140 includes an electrically connected switch control circuit 142 and a battery energy management unit 144. A switch control circuit 142 is arranged between the second end of the fuse 100 and the positive end of the battery cell 120. The switch control circuit 142 is used to control the charging and discharging of the battery cell 120.

[0050] In one embodiment, the switch control circuit 142 is a MOS switch unit.

[0051] In one embodiment, the MOS switch unit is an NMOS switch unit.

[0052] The above description is only a partial or preferred embodiment of the present invention. Neither the text nor the drawings can limit the scope of protection of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the overall concept of the present invention, or direct / indirect application in other related technical fields are included in the scope of protection of the present invention.

Claims

1. A charge and discharge protection circuit, characterized in that: include: A fuse, wherein a first end of the fuse is used to be electrically connected to a charging input end, and a second end of the fuse is used to be electrically connected to a battery management system, and the battery management system is used to perform energy management on the battery cell; An overvoltage protection unit, wherein a first end of the overvoltage protection unit is electrically connected to a first end of the fuse, a second end of the overvoltage protection unit is used to be externally connected to a preset power supply, a third end of the overvoltage protection unit is used to be electrically connected to the battery management system, and a fourth end of the overvoltage protection unit is used to be electrically connected to the battery management system and the ground terminal of the battery cell, respectively; The overvoltage protection unit is used to receive the control signal output by the battery management system to control the branch where the overvoltage protection unit is located to be turned on, so as to blow the fuse, wherein the control signal is generated by the battery management system when the battery cell is overvoltage; The overvoltage protection unit includes a thyristor surge suppressor and a switch tube control unit, the positive terminal of the thyristor surge suppressor serves as the first terminal of the overvoltage protection unit, the negative terminal of the thyristor surge suppressor serves as the fourth terminal of the overvoltage protection unit, and the control terminal of the thyristor surge suppressor is electrically connected to the first terminal of the switch tube control unit; The second end of the switch tube control unit serves as the second end of the overvoltage protection unit, and the third end of the switch tube control unit serves as the third end of the overvoltage protection unit; The switch tube control unit adopts an NPN transistor or an NMOS switch tube; When the switch tube control unit adopts the NPN type transistor, the emitter of the NPN type transistor is the first end of the switch tube control unit, the collector of the NPN type transistor is the second end of the overvoltage protection unit, and the base of the NPN type transistor is the third end of the overvoltage protection unit; When the switch tube control unit adopts the NMOS switch tube, the source of the NMOS switch tube is the first end of the switch tube control unit, the drain of the NMOS switch tube is the second end of the overvoltage protection unit, and the gate of the NMOS switch tube is the third end of the overvoltage protection unit.

2. The charge and discharge protection circuit according to claim 1, characterized in that: The fuse is also used to melt when the battery cell has an overcurrent.

3. A charge and discharge protection system, characterized in that: It comprises the charge and discharge protection circuit, battery management system and battery cell according to claim 1 or 2, wherein the battery management system is also electrically connected to the positive terminal of the battery cell; The battery management system is used to generate a voltage control signal when the battery cell is over-voltage; The charge and discharge protection circuit is used to receive the voltage control signal output by the battery management system, and control the branch where the circuit is located to be turned on according to the voltage control signal, so as to cause the fuse to blow.

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