Charging circuit capable of being recovered after battery overdischarge and battery system

Abstract

The utility model discloses a charging circuit capable of recovering after battery overdischarge and a battery system, the charging circuit is used for charging a battery management system, the battery management system comprises a first joint, and the charging circuit comprises a charging joint and a charging control unit; the charging connector is used for cooperating with the first connector to electrically connect a cathode end and an anode end of an external power supply device for charging. The charging control unit is electrically connected with the battery management system and the charging connector, and the charging control unit is used for controlling current in the charging connector to flow unidirectionally so as to charge the battery management system. The charging connector is matched with the first connector to be electrically connected with the negative electrode end and the positive electrode end of the external power supply device for charging, and the charging control unit controls the current in the charging connector to flow unidirectionally to charge the battery management system, so that the problem that the battery is scrapped due to the fact that the discharging MOS tube is not conducted and cannot be charged is solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to lithium battery technical field especially relates to a battery overdischarge recoverable charging circuit and battery system. BACKGROUND

[0002] With the development of science and technology, the price of lithium also continues to decline, so that the lithium battery is no longer a representative of high price, but a people-friendly and affordable high-tech product. According to KWH, at present, part of the lithium battery has been lower than lead-acid battery, so in many application fields of lead-acid, lithium battery is always permeated at all times.

[0003] Safety problem is always a topic that lithium battery cannot bypass. At present, the most fundamental reason for refusing to use lithium battery in these fields is that safety problem cannot be guaranteed. In order to protect the internal cell of lithium battery from being affected by overcharge, overdischarge, high temperature and low temperature, a corresponding BMS board (BATTERY MANAGEMENT SYSTEM, i.e. storage battery management system) is generally equipped for each lithium battery to read the parameters of lithium cell and develop appropriate strategies to avoid the influence of overcharge, overdischarge, high temperature and low temperature on lithium battery.

[0004] As for the strategy of overdischarge, the following operation is generally performed: when the single voltage value reaches the lowest voltage of single cell or the overall voltage of battery is lower than the lowest overall voltage set to allow, the BMS will start the protection instruction to disconnect the discharge MOS tube. Generally, the charging MOS tube and the discharge MOS tube of the battery are connected in series, at this time, if the battery is connected to the external power supply through the positive and negative terminals for intervention charging, the BMS will detect the charging current and close the discharge MOS tube, at this time, the battery can be normally charged through the positive and negative terminals.

[0005] Under normal circumstances, the above strategy can operate normally and will not affect the use. However, when the voltage of lithium battery is low and the external does not intervene in charging in time, since the lithium battery will continuously self-discharge and the BMS needs to be continuously powered during the period, the lithium battery will be reduced. When the lithium battery is reduced to a certain extent, there may not be enough power to close the discharge MOS tube, when the battery is charged at this time, the discharge MOS tube will not be turned on, and the positive and negative terminals cannot form a closed path, so the battery will be scrapped. Utility model content

[0006] In view of the deficiencies existing in the prior art, the utility model aims at providing a battery overdischarge recoverable charging circuit and battery system, which is used for avoiding the battery from being scrapped.

[0007] According to the first aspect of the utility model, provide the charge circuit that battery overdischarge can recover, be used for charging battery management system, the battery management system includes first joint, the charge circuit includes:

[0008] Charging joint, the charging joint is used for matching the first joint electric connection negative end and positive end of external power supply device to charge;

[0009] Charging control unit, the charging control unit is electrically connected with the battery management system, the charging joint respectively, the charging control unit is used for controlling the one-way flow of electric current in the charging joint, to charge the battery management system.

[0010] The utility model discloses a charge circuit that battery overdischarge can recover, another charging joint of battery management system is replaced by the charging joint of charge circuit to cooperate with the first joint of battery management system electric connection negative end and positive end of external power supply device to charge, and the one-way flow of electric current in the charging joint is controlled by charging control unit to charge battery management system, and then the problem that battery is scrapped due to the discharge MOS pipe not conducting and being unable to charge is solved.

[0011] In some embodiments, the battery management system further comprises:

[0012] Battery pack, the battery pack includes a plurality of series and / or parallel battery monomers, and a positive end of the battery pack is electrically connected with the first joint;

[0013] BMS unit, the BMS unit is electrically connected with the battery pack;

[0014] Detection unit, the detection unit is electrically connected with the negative end of the battery pack and the BMS unit respectively;

[0015] Charging MOS pipe, the charging MOS pipe is electrically connected with the detection unit and the BMS unit respectively;

[0016] Discharge MOS pipe, the discharge MOS pipe is electrically connected with the charging MOS pipe and the BMS unit respectively;

[0017] Second joint, the second joint is electrically connected with the discharge MOS pipe.

[0018] In some embodiments, the charging control unit is electrically connected between the charging MOS pipe and the discharge MOS pipe.

[0019] In some embodiments, the charging control unit is electrically connected with the negative end of the battery pack.

[0020] In some embodiments, the detection unit is a detection resistor.

[0021] In some embodiments, the charging control unit comprises:

[0022] a unidirectional conduction unit for controlling unidirectional flow of current in the charging terminal.

[0023] In some embodiments, the unidirectional conduction unit is a diode.

[0024] In some embodiments, the charging control unit further comprises:

[0025] a current control unit for controlling magnitude of current in the charging terminal.

[0026] In some embodiments, the current control unit is an air switch or a fuse.

[0027] According to a second aspect of the present application, a battery system is provided, which comprises the above-mentioned charging circuit recoverable after over-discharge of a battery.

[0028] Compared with the prior art, the charging circuit recoverable after over-discharge of a battery and the battery system of the present application replace another charging terminal of a battery management system by a charging terminal of the charging circuit, so as to cooperate with a first terminal of the battery management system to electrically connect a negative terminal and a positive terminal of an external power supply device for charging, and meanwhile, the charging control unit controls unidirectional flow of current in the charging terminal to charge the battery management system, thereby solving the problem that the battery is scrapped due to failure of charging caused by non-conduction of a discharge MOS tube. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 a first circuit diagram of the battery system of an embodiment of the present application;

[0030] Figure 2 a second circuit diagram of the battery system of an embodiment of the present application;

[0031] Figure 3 a third circuit diagram of the battery system of an embodiment of the present application.

[0032] BRIEF DESCRIPTION OF DRAWINGS Battery management system A, battery pack 1, first terminal 2, second terminal 3, discharge MOS tube 4, charging MOS tube 5, detection unit 6, BMS unit 7, charging circuit B, charging control unit 8, unidirectional conduction unit 81, current control unit 82, charging terminal 9. DETAILED DESCRIPTION

[0033] The present application will be further described in detail below with reference to the accompanying drawings.

[0034] This utility model provides a battery system, such as Figure 1 As shown, the battery system includes a battery management system A, which includes a battery pack 1, a first connector 2, a second connector 3, a discharge MOSFET 4, a charging MOSFET 5, a detection unit 6, and a BMS unit 7.

[0035] like Figure 1 As shown, battery pack 1 includes multiple battery cells connected in series and / or in parallel. Each battery cell can be a lithium battery cell. Specifically, battery pack 1 can be formed by connecting at least two battery cells in series. Alternatively, battery pack 1 can be formed by first connecting at least two battery cells in series, and then connecting at least one battery cell in parallel with one or more battery cells based on the above-mentioned at least two battery cells connected in series. The positive terminal of battery pack 1 is electrically connected to the first connector 2, so the first connector 2 is the positive terminal connector. The first connector 2 is used to electrically connect to the positive terminal of an external power supply device (such as an external power source) during charging. The second connector 3 is used as the negative terminal connector. The second connector 3 is used to electrically connect to the negative terminal of an external power supply device (such as an external power source) during charging. In addition, when battery pack 1 is discharging to the outside, the first connector 2 and the second connector 3 are respectively electrically connected to the positive and negative terminals of the electrical device.

[0036] like Figure 1 As shown, the first end of the discharge MOSFET 4 is electrically connected to the second connector 3, the second end of the charging MOSFET 5 is electrically connected to the second end of the discharge MOSFET 4, the first end of the charging MOSFET 5 is connected to the second end of the detection unit 6, and the first end of the detection unit 6 is electrically connected to the negative terminal of the battery pack 1. The BMS unit 7 is electrically connected to the battery pack 1, that is, the BMS unit 7 is electrically connected to the positive and negative terminals of the individual battery cells in the battery pack 1 respectively. The BMS unit 7 is used to detect the voltage of each individual battery cell. The BMS unit 7 is also electrically connected to the first and second ends of the detection unit 6. The BMS unit 7 is used to perform charging or discharging detection on the battery pack 1 through the detection unit 6. The BMS unit 7 is also electrically connected to the control terminals of the discharge MOSFET 4 and the charging MOSFET 5. The BMS unit 7 controls the charging and discharging of the battery pack 1 by controlling the on / off state of the discharge MOSFET 4 and the charging MOSFET 5. Among them, the detection unit 6 is a detection resistor, and the BMS unit 7 is a BMS chip. The BMS chip model can be H6203L, BQ2560x, MAX1770x, etc.

[0037] The inventor discovered that, Figure 1The first joint 2 is directly connected with the battery pack 1 in the shown battery management system A, and the second joint 3 is controlled by the discharge MOS tube 4 and the charge MOS tube 5 between the second joint 3 and the battery pack 1. As long as any one of the discharge MOS tube 4 and the charge MOS tube 5 cannot be closed, a loop cannot be formed, thereby affecting the battery charging. Therefore, when the voltage of the battery pack 1 is low and the external does not intervene in the charging in time, the lithium battery will continuously self-discharge, and the BMS unit 7 is continuously powered during the period, which will cause the lithium battery power to decrease. When the lithium battery power decreases to a certain extent, there may be insufficient power to close the discharge MOS tube 4 by the BMS unit 7. When the battery pack 1 is charged at this time, the discharge MOS tube 4 will not be turned on, and a closed path cannot be formed between the first joint 2 and the second joint 3, so the battery cannot be charged, that is, the battery will be scrapped.

[0038] In order to solve the above problems, the battery system shown in the embodiment of the present application is based on the battery management system A, and a charge circuit B (hereinafter referred to as the charge circuit B) that can recover after over-discharge of the battery is added to the battery management system A. The charge circuit B is used to charge the battery management system A. The charge circuit B includes a charge control unit 8 and a charge joint 9. Figure 2

[0039] When the battery pack 1 is charged, the charge joint 9 replaces the second joint 3 to electrically connect the negative terminal of the external power supply device. The charge joint 9 is used to electrically connect the negative terminal and the positive terminal of the external power supply device in cooperation with the first joint 2 to form a closed loop for charging.

[0040] The charge control unit 8 is electrically connected with the battery management system A and the charge joint 9. The charge control unit 8 is used to control the unidirectional flow of current in the charge joint 9 to charge the battery management system A.

[0041] In an optional embodiment, as shown in the embodiment of the present application, the charge control unit 8 is electrically connected between the charge MOS tube 5 and the discharge MOS tube 4, that is, the first end of the charge control unit 8 is electrically connected with the charge joint 9, and the second end of the charge control unit 8 is electrically connected with the second end of the charge MOS tube 5, that is, electrically connected with the second end of the discharge MOS tube 4. This can bypass the discharge MOS tube 4 and directly charge the battery pack 1, thereby solving the problem that the battery cannot be charged due to insufficient power and the discharge MOS tube 4 cannot be closed. Figure 2

[0042] In an optional embodiment, as shown in the embodiment of the present application, the charge control unit 8 is electrically connected between the charge MOS tube 5 and the discharge MOS tube 4, that is, the first end of the charge control unit 8 is electrically connected with the charge joint 9, and the second end of the charge control unit 8 is electrically connected with the second end of the charge MOS tube 5, that is, electrically connected with the second end of the discharge MOS tube 4. This can bypass the discharge MOS tube 4 and directly charge the battery pack 1, thereby solving the problem that the battery cannot be charged due to insufficient power and the discharge MOS tube 4 cannot be closed. Figure 2 ​​As shown, the charging control unit 8 includes a unidirectional conduction unit 81 for controlling the unidirectional flow of current in the charging terminal 9. Specifically, the unidirectional conduction unit 81 is a diode, the second end of which is electrically connected to the second end of the charging MOS tube 5, i.e. to the second end of the discharging MOS tube 4. The loop formed by the charging terminal 9 (i.e. charging through the charging terminal 9) can only charge but not discharge, and a unidirectional loop is required. Therefore, the unidirectional charging can be achieved through the diode (i.e. the unidirectional conduction unit 81).

[0043] In an alternative embodiment, as shown in Figure 2 As shown, the charging control unit 8 further includes a current control unit 82 for controlling the size of the current in the charging terminal 9. Specifically, the current control unit 82 is an air switch, which is electrically connected between the unidirectional conduction unit 81 and the charging terminal 9. In addition, the current control unit 82 can also be a fuse, which is electrically connected between the unidirectional conduction unit 81 and the charging terminal 9. Since the battery pack 1 is in a feeding state, it is generally recommended to use a small current for recharging, and a large current will cause additional damage to the battery pack 1. Therefore, the current control unit 82 is needed to control the size of the current in the charging terminal 9, and the size of the current is determined by the size of the battery pack 1, which is generally less than 30A. That is, the current control unit 82 only allows a current of 30A or less to pass through.

[0044] As shown in Figure 2 When the charging time reaches a certain time, the voltage of the battery pack 1 will rise, and the battery pack 1 can normally supply power to the BMS unit 7. Then the BMS unit 7 will also resume its function, and the discharging MOS tube 4 will be closed. At this time, the charging can be carried out between the first terminal 2 and the second terminal 3, and the normal charging mode is restored.

[0045] It should be noted that since the BMS unit 7 is an integrated circuit, the functions of the unidirectional conduction unit 81 (i.e. the diode) and the current control unit 82 (i.e. the air switch or the fuse) can be integrated into the integrated circuit. Only one terminal (i.e. the charging terminal 9) needs to be led out from the new BMS unit 7, and the charging can be carried out through the connection between the terminal and the external connection.

[0046] In an alternative embodiment, as shown in Figure 3 The charging control unit 8 is electrically connected to the negative terminal of the battery pack 1, i.e. Figure 3 The connection mode of the charging control unit 8 is shown in Figure 2The connection mode of the charging control unit 8 shown is different, specifically, the charging control unit 8 also includes a unidirectional conduction unit 81 and a current control unit 82, the first end of the unidirectional conduction unit 81 is directly electrically connected with the negative terminal of the battery pack 1, the first end of the current control unit 82 is electrically connected with the second end of the unidirectional conduction unit 81, and the second end of the current control unit 82 is electrically connected with the charging connector 9; at this time, the charging control unit 8 is directly drawn from the negative terminal of the battery pack 1, and is completely not controlled by the discharge MOS tube 4 and the charging MOS tube 5, so that the charging connector 9 and the first connector 2 can charge the battery pack 1 regardless of the state of the battery pack 1.

[0047] As shown in Figure 3 The connection method skips the control of the BMS unit 7 and directly charges the battery pack 1, which may have some risks, when the battery pack 1 can normally supply power to the BMS unit 7 so that the BMS unit 7 starts to work normally, the charging between the charging connector 9 and the first connector 2 must be disconnected, and charging is performed by the first connector 2 and the second connector 3. Because the charging connector 9 directly charges the battery pack 1, bypassing the management of the BMS unit 7, if it is not removed in time, long-time charging may cause overcharging of the battery pack 1, thereby causing additional damage to the battery pack 1, so the charging personnel needs to pull out the charging connector 9 within a certain time and use the first connector 2 and the second connector 3 for charging; or install a control switch in the charging control unit 8, the control switch is electrically connected with the BMS unit 7, the control switch is in a normally closed state, that is, when the BMS unit 7 does not control the control switch, the control switch is in a closed state, and the charging control unit 8 is normally turned on, when the battery pack 1 can normally supply power to the BMS unit 7 so that the BMS unit 7 starts to work normally, the BMS unit 7 controls the control switch to be opened, so that the charging control unit 8 is disconnected and cannot continue to charge, thereby protecting the battery pack 1, for example, the control switch can be a relay or other control switch with a normally closed state.

[0048] It should be noted that since the connection method is not affected by the BMS unit 7, any BMS unit can be used, as long as the unidirectional conduction unit 81 (i.e. diode) and the current control unit 82 (i.e. air switch or fuse) and the charging connector 9 are added when the battery pack 1 is produced.

[0049] The battery system of the embodiment replaces another charging terminal (i.e. the second terminal 3) of the battery management system A with the charging terminal 9 of the charging circuit B, so as to cooperate with the first terminal 2 of the battery management system A to electrically connect the negative terminal and the positive terminal of the external power supply device for charging, and the current unidirectional flow in the charging terminal 9 is controlled by the charging control unit 8 to charge the battery management system A, thereby solving the problem that the battery is scrapped due to the failure of charging caused by the non-conduction of the discharging MOS tube.

[0050] The above merely describes some embodiments of the present application. For those skilled in the art, without departing from the inventive concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application.

Claims

1. A charging circuit capable of recovering from battery over-discharge, characterized in that, For charging a battery management system, the battery management system including a first connector, the charging circuit including: A charging connector, which is used to connect the negative and positive terminals of an external power supply device to the first connector for charging. A charging control unit is electrically connected to the battery management system and the charging connector. The charging control unit is used to control the unidirectional flow of current in the charging connector to charge the battery management system.

2. The battery over-discharge recoverable charging circuit according to claim 1, characterized in that, The battery management system also includes: A battery pack comprising multiple battery cells connected in series and / or in parallel, wherein the positive terminal of the battery pack is electrically connected to the first connector; BMS unit, wherein the BMS unit is electrically connected to the battery pack; The detection unit is electrically connected to the negative terminal of the battery pack and the BMS unit, respectively. A charging MOSFET is electrically connected to the detection unit and the BMS unit, respectively. A discharge MOS transistor, which is electrically connected to the charging MOS transistor and the BMS unit respectively; The second connector is electrically connected to the discharge MOS transistor.

3. The battery over-discharge recoverable charging circuit according to claim 2, characterized in that, The charging control unit is electrically connected between the charging MOSFET and the discharging MOSFET.

4. The battery over-discharge recoverable charging circuit according to claim 2, characterized in that, The charging control unit is electrically connected to the negative terminal of the battery pack.

5. The battery over-discharge recoverable charging circuit according to claim 2, characterized in that, The detection unit is a detection resistor.

6. The battery over-discharge recoverable charging circuit according to any one of claims 1-5, characterized in that, The charging control unit includes: A unidirectional conduction unit is used to control the unidirectional flow of current in the charging connector.

7. The battery over-discharge recoverable charging circuit according to claim 6, characterized in that, The unidirectional conduction unit is a diode.

8. The battery over-discharge recoverable charging circuit according to claim 6, characterized in that, The charging control unit also includes: A current control unit is used to control the magnitude of the current in the charging connector.

9. The battery over-discharge recoverable charging circuit according to claim 8, characterized in that, The current control unit is an air switch or a fuse.

10. A battery system, characterized in that, Includes the battery over-discharge recoverable charging circuit as described in any one of claims 1-9.

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