Lithium battery protection circuit and lithium battery module

Abstract

The present application relates to a lithium battery protection circuit and a lithium battery module. The control circuit includes a first control unit, a second control unit, a charge and discharge switch unit, and an auxiliary protection switch unit. The first control unit is also connected to the peripheral main controller through a two-wire serial bus. The first control unit and the second control unit are both electrically connected to the lithium battery pack and used to detect the status parameters of the lithium battery pack. The first control unit also controls the electrical connection between the charge and discharge switch unit and the auxiliary protection switch unit. The second control unit controls the electrical connection between the auxiliary protection switch unit. The input end of the auxiliary protection switch unit is electrically connected to the positive electrode of the lithium battery pack, the output end of the auxiliary protection switch unit is electrically connected to the charging input end of the charge and discharge switch unit, and the output end of the charge and discharge switch unit is electrically connected to the positive port. Through this application, the problem of lithium battery packs in the related art that the hardware protection is out of control and the battery pack cannot be actively protected, causing battery damage, is solved.

Description

Technical Field

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

[0002] In the field of new energy batteries, it is often practiced to connect multiple batteries in parallel to form corresponding battery cells, and then connect multiple battery cells in series to form corresponding battery packs, thereby meeting the power supply needs of large capacity and large current.

[0003] In the prior art, for a battery pack composed of cells connected in series, corresponding control circuits are set up to protect all individual cells and the entire battery pack. For example, by monitoring the voltage and current of all individual cells during charging and discharging, when overcharging or over-discharging occurs, the corresponding circuit is disconnected to suspend the battery pack from continuing to overcharge or over-discharge. However, in the related art, for the protection of parallel and series battery packs, when the hardware protection function (overcharge and discharge protection) on the protection board fails or occasional thermal runaway, overcharging or over-discharging occurs during the use of lithium batteries, the protection board cannot actively protect the battery pack, which can easily cause damage to the battery pack and there is a risk of battery explosion.

[0004] There is still a lack of better technical solutions to the problem that the protection board of the lithium battery pack in the related art occasionally fails to protect the battery pack or the hardware protection fails to control, so that the protection board cannot actively protect the battery pack and causes damage to the battery. Summary of the Invention

[0005] The present application provides a lithium battery protection circuit and a lithium battery module to at least solve the problem in the related art that the protection board of the lithium battery pack occasionally fails to protect the battery pack or the hardware protection fails to control the protection, so that the protection board cannot actively protect the battery pack and causes damage to the battery.

[0006] In the first aspect, the present application provides a lithium battery protection circuit for protecting a lithium battery pack, comprising a first control unit, a second control unit, a charge and discharge switch unit, and an auxiliary protection switch unit. The first control unit is also communicatively connected to a peripheral main controller via a two-wire serial port bus. The first control unit and the second control unit are both electrically connected to the lithium battery pack and are used to detect the state parameters of the lithium battery pack. The first control unit also controls the electrical connection between the charge and discharge switch unit and the auxiliary protection switch unit. The second control unit controls the electrical connection between the auxiliary protection switch unit. The input end of the auxiliary protection switch unit is electrically connected to the positive electrode of the lithium battery pack, the output end of the auxiliary protection switch unit is electrically connected to the charging input end of the charge and discharge switch unit, and the output end of the charge and discharge switch unit is electrically connected to the positive port. Used to generate a charge and discharge protection control signal and a first protection control signal according to the detected state parameter; the second control unit is used to generate a corresponding second protection control signal according to the detected state parameter; the charge and discharge switch unit is used to control the connection and disconnection of the charging input terminal and the positive port according to the charge and discharge protection control signal, so as to control the charging and discharging of the lithium battery pack; the peripheral main controller is used to generate a first control signal according to the state parameter transmitted by the first control unit and send the first control signal to the first control unit at least when the charge and discharge switch unit cannot control the charging and discharging of the lithium battery pack; the auxiliary protection switch unit is used to control the connection and disconnection of the positive electrode of the lithium battery pack and the charging input terminal according to at least one of the first protection control signal and the first control signal sent by the first control unit and the second protection control signal sent by the second control unit, so as to provide secondary protection for the charging of the lithium battery pack.

[0007] In a second aspect, the present application provides a lithium battery module, comprising a protection board, on which a protection circuit is provided, wherein the protection circuit comprises the lithium battery protection circuit described in the first aspect.

[0008] Compared with the related art, the present embodiment provides a lithium battery protection circuit and a lithium battery module, which include a first control unit, a second control unit, a charge and discharge switch unit, and an auxiliary protection switch unit. The first control unit is also communicatively connected to the peripheral main controller via a two-wire serial port bus. The first control unit and the second control unit are both electrically connected to the lithium battery pack and are used to detect the state parameters of the lithium battery pack. The first control unit also controls the electrical connection between the charge and discharge switch unit and the auxiliary protection switch unit. The second control unit controls the electrical connection between the auxiliary protection switch unit. The input end of the auxiliary protection switch unit is electrically connected to the positive electrode of the lithium battery pack, the output end of the auxiliary protection switch unit is electrically connected to the charging input end of the charge and discharge switch unit, and the output end of the charge and discharge switch unit is electrically connected to the positive port. The first control unit generates a charge and discharge protection control signal and a first protection control signal according to the detected state parameters, and the second control unit generates a corresponding second protection control signal according to the detected state parameters. The charge-discharge switch unit controls the connection between the charging input terminal and the positive port according to the charge-discharge protection control signal to control the charging and discharging of the lithium battery pack. When the charge-discharge switch unit cannot control the charging and discharging of the lithium battery pack, the peripheral main controller generates a first control signal according to the state parameter transmitted by the first control unit and transmits the first control signal to the first control unit. The auxiliary protection switch unit controls the connection between the positive electrode of the lithium battery pack and the charging input terminal according to one of the first protection control signal and the first control signal transmitted by the first control unit and the second protection control signal transmitted by the second control unit to provide secondary protection for the charging of the lithium battery pack. This solves the problem in the related art that the protection board of the lithium battery pack occasionally fails to protect the battery pack or the hardware protection fails to protect the battery pack, thereby preventing the protection board from actively protecting the battery pack and causing damage to the battery. This prevents the forced charging and discharging of defective batteries, reduces the occurrence of safety issues in the use of lithium batteries, and extends the service life of the batteries.

[0009] The details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0012] Figure 1 A structural block diagram of a lithium battery protection circuit provided in an embodiment of the present application;

[0013] Figure 2 A topological diagram of a lithium battery protection circuit according to an embodiment of the present application;

[0014] Figure 3 A topological diagram of the first control unit of a preferred embodiment of the present application;

[0015] Figure 4 A topological diagram of the second control unit of a preferred embodiment of the present application;

[0016] Figure 5 A topological diagram of the auxiliary protection switch unit of a preferred embodiment of the present application;

[0017] Figure 6 This is a topological diagram of the charge and discharge switch unit of the preferred embodiment of the present application. DETAILED DESCRIPTION

[0018] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0019] The lithium battery protection circuit of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application and through specific embodiments.

[0020] refer to Figures 1 to 6The embodiment of the present application provides a lithium battery protection circuit for protecting a lithium battery pack, including a first control unit 100, a second control unit 200, a charge and discharge switch unit 300, and an auxiliary protection switch unit 400. The first control unit 100 is also communicatively connected to the peripheral main controller 500 via a two-wire serial bus (for example, SMBus). The first control unit 100 and the second control unit 200 are both electrically connected to the lithium battery pack 600 and are used to detect status parameters of the lithium battery pack 600. The first control unit 100 also controls the electrical connection between the charge and discharge switch unit 300 and the auxiliary protection switch unit 400. The second control unit 200 controls the electrical connection between the auxiliary protection switch unit 400. The input end of the auxiliary protection switch unit 400 is electrically connected to the positive electrode B+ of the lithium battery pack 600, the output end of the auxiliary protection switch unit 400 is electrically connected to the charging input end 301 of the charge and discharge switch unit 300, and the output end 302 of the charge and discharge switch unit 300 is electrically connected to the positive port P+1.

[0021] The first control unit 100 is configured to generate a charge-discharge protection control signal and a first protection control signal according to the detected state parameter.

[0022] In this embodiment, when detecting the status parameters of the lithium battery pack 600, the first control unit 100 detects the following parameters: voltage, current, temperature, voltage difference between battery cells, number of charge and discharge cycles, battery charge SOC and remaining capacity; after detecting the corresponding status parameters, the first control unit 100 will generate a corresponding charge and discharge protection control signal (a control signal for controlling the stop of charging and discharging) and a first protection control signal (a signal for controlling the lithium battery pack 600 to stop working and using); in this embodiment, when the first control unit 100 detects that each status parameter exceeds a preset safety parameter value range, it will generate a corresponding first protection control signal, thereby suspending the use of the battery pack.

[0023] In this embodiment, the first control unit 100 is in communication connection with the peripheral main controller 500. After detecting and obtaining the corresponding status parameters, the first control unit 100 reports the corresponding status parameters to the peripheral main controller 500 in real time, so that the peripheral main controller 500 can judge the status of the battery.

[0024] The second control unit is configured to generate a corresponding second protection control signal according to the detected state parameter.

[0025] In this embodiment, when detecting the status parameters of the lithium battery pack 600, the second control unit 200 detects the following parameters: the voltage of each battery cell, whether the voltage of each battery cell exceeds the overcharge protection voltage, whether the duration of overcharging exceeds the overcharge protection delay time, and whether each battery cell is disconnected; after detecting the corresponding status parameters, the second control unit 200 will generate a second protection control signal to control the auxiliary protection switch unit 400 to perform secondary protection, that is, directly suspend the use of the battery.

[0026] The charge and discharge switch unit 300 is used to control the connection and disconnection between the charging input terminal 301 and the positive port P+1 according to the charge and discharge protection control signal, so as to control the charge and discharge of the lithium battery pack 600.

[0027] In this embodiment, the charge and discharge switch unit 300 is controlled by the first control unit 100. That is, the first control unit 100 controls the charging or discharging of the lithium battery pack 600 by controlling the charge and discharge switch unit 300. Specifically, the first control unit 100 controls the lithium battery pack 600 to suspend overcharging or overdischarging through the charge and discharge switch unit 300.

[0028] The peripheral main controller 500 is at least used to generate a first control signal according to the state parameter transmitted by the first control unit 100 and send the first control signal to the first control unit 100 when the charge and discharge switch unit 300 cannot control the charge and discharge of the lithium battery pack 600.

[0029] In this embodiment, the first control unit 100 is communicatively connected with the peripheral main controller 500. After receiving the corresponding status parameters uploaded by the first control unit 100, the peripheral main controller 500 will determine whether the corresponding protection function on the protection board is invalid based on each status parameter. For example: based on the voltage and current, it is determined that the lithium battery pack 600 is overcharging, and the overcharging time exceeds the preset overcharging protection time, it means that the active protection of the lithium battery pack 600 is invalid, and the first control unit 100 does not trigger the generation of the first protection control signal. At this time, the peripheral main controller 500 will generate a first control signal and transmit the first control signal to the first control unit 100. The first control unit 100 controls the auxiliary protection switch unit 400 based on the first control signal to disconnect the positive electrode B+ of the lithium battery pack 600 from the charging input terminal 301, that is, to suspend the use of the lithium battery pack 600.

[0030] The auxiliary protection switch unit 400 is at least used to control the connection and disconnection between the positive electrode B+ of the lithium battery pack 600 and the charging input terminal 301 according to the first protection control signal and one of the first control signals sent by the first control unit 100 and the second protection control signal sent by the second control unit 200, so as to provide secondary protection for the charging of the lithium battery pack 600.

[0031] In this embodiment, the auxiliary protection switch unit 400 mainly provides secondary protection for the overcharging of the lithium battery pack 600, and achieves protection by disconnecting the lithium battery pack 600 from the input end of the charge and discharge switch unit 300, so that the lithium battery pack 600 stops working.

[0032] The above-mentioned lithium battery protection circuit adopts a configuration in which the first control unit 100 is configured to generate a charge and discharge protection control signal and a first protection control signal according to the detected state parameter, the second control unit 200 is configured to generate a corresponding second protection control signal according to the detected state parameter, the charge and discharge switch unit 300 is configured to control the on and off of the charging input terminal 301 and the positive port P+1 according to the charge and discharge protection control signal to control the charge and discharge of the lithium battery pack 600, and the peripheral main controller 500 is configured to generate a first control signal according to the state parameter transmitted by the first control unit 100 when the charge and discharge switch unit 300 cannot control the charge and discharge of the lithium battery pack 600, and send the first control signal to the external main controller 500. To the first control unit 100 and set the auxiliary protection switch unit 400 to control the on and off of the positive electrode B+ of the lithium battery pack 600 and the charging input terminal 301 according to the first protection control signal and one of the first control signals sent by the first control unit 100 and according to the second protection control signal sent by the second control unit 200, so as to provide secondary protection for the charging of the lithium battery pack 600, solve the problem of occasional protection failure or hardware protection failure of the protection board of the lithium battery pack 600 in the related art, so that the protection board cannot actively protect the battery pack and cause battery damage, and achieve the beneficial effect of avoiding forced charging and discharging of defective batteries, reducing the occurrence of safety problems in the use of lithium batteries, and extending the service life of batteries.

[0033] In order to realize the state parameter detection, charge and discharge control and secondary protection control of the lithium battery pack 600, refer to Figures 1 to 6 In some embodiments, the first control unit 100 includes a first lithium battery manager U1, a capacitor voltage sampling circuit 101 and a first detection circuit 102, wherein,

[0034] The first lithium battery manager U1 is in communication with the peripheral main controller 500, and the first lithium battery manager U1 has multiple first positive power ports (refer to Figure 2 and Figure 3 The VC1 to VC6 pins of U1 are connected in sequence to the positive electrodes of the multiple series-connected cells of the lithium battery pack 600 (reference Figure 2 B1, B2, B3, B4, B5, B+) are electrically connected, and the negative electrode of the lithium battery pack 600 (reference Figure 2 B-) are connected to the negative power supply port of the first lithium battery manager U1 (reference Figure 2 and Figure 3 The VSS pin of U1 in the figure) is electrically connected to the negative port P-1, and the charging control port of the first lithium battery manager U1 (reference Figure 2 and Figure 3 CHG pin of U1 in the middle) and discharge control port (reference Figure 2 and Figure 3 The DSG pins of U1 in the figure are connected in series with the first coupling resistor (reference Figure 2 and Figure 3 R25 and R23 in the charging and discharging switch unit 300 are electrically connected to the charging controlled port 303 and the discharging controlled port 304, respectively, and the auxiliary protection control port of the first lithium battery manager U1 (reference Figure 2 and Figure 3 The FUSE pin of U1 in the middle is electrically connected to the controlled terminal 401 of the auxiliary protection switch unit 400 through a second coupling resistor R22 in series;

[0035] The capacitor voltage divider sampling circuit 101 includes a plurality of sampling points (in this embodiment, the capacitor voltage divider sampling circuit 100 is composed of capacitors C1 to C6 connected in series, and the electrical connection point of two adjacent capacitors corresponds to a sampling point). Each sampling point is connected in series with a third coupling resistor (reference Figure 2 and Figure 3 The resistors R1, R2, R3, R4, R5, and R6 in the battery are connected to the positive terminal of a battery cell (reference Figure 2 B+, B5, B4, B3, B2, B1) are electrically connected, and each sampling point is also electrically connected to a first positive power supply port (reference Figure 2 and Figure 3 VC1 to VC6 pins of U1 in the middle);

[0036] The first detection circuit 102 includes a π-type RC filter circuit (refer to Figure 2 The filter circuit consists of resistor R13, resistor R17, capacitor C17, capacitor C18, capacitor C15, and capacitor C19) and a sensing resistor RS1. The sensing resistor RS1 is connected in series between the negative electrode B- and the negative port P-1 of the lithium battery pack 600. One end of the π-type RC filter circuit is connected to the two analog input detection ports (reference Figure 2 The other end of the π-type RC filter circuit is electrically connected to the first end of the sensing resistor RS1 (reference Figure 2 The electrical connection point between the middle resistor R13 and the sensing resistor RS1) and the second end (reference Figure 2 The middle resistor R17 is electrically connected to the electrical connection point of the sensing resistor RS1, wherein,

[0037] The first lithium battery manager U1 is used to detect the voltage of multiple battery cells connected in series through the capacitive voltage divider sampling circuit 101 and multiple third coupling resistors, and detect the charging and discharging current of the lithium battery pack 600 through the first detection circuit 102 to obtain status parameters. The first lithium battery manager U1 is also used to generate a charge and discharge protection control signal and a first protection control signal based on the status parameters.

[0038] In this embodiment, the first lithium battery manager includes a multi-cell lithium-ion battery pack manager of the BQ40Z80 model; in this embodiment, the two analog input detection ports of the first lithium battery manager U1 electrically connected to the first detection circuit 102 are connected to the internal coulomb counter periphery of the first lithium battery manager U1, which is used to integrate a small voltage between SRP and SRN. The charging current detected by the first detection circuit 102 flows from SRP to SRN.

[0039] The auxiliary protection switch unit 400 is used to control the positive electrode B+ of the lithium battery pack 600 to be disconnected from the charging input terminal 301 according to the received first control signal or first protection control signal when the state parameter indicates that the lithium battery pack 600 is in an unsafe charging and discharging state.

[0040] In this embodiment, the lithium battery pack 600 is in an unsafe charging and discharging state when the first control unit 100 detects that each state parameter exceeds a preset safety parameter value range and / or the active protection of the first control unit 100 fails (at least corresponding to the inability to control the charging and discharging switch 300 to perform charging and discharging protection).

[0041] The charge and discharge switch unit 300 is used to control the charge input terminal 301 to be disconnected from the positive port P+1 according to the received charge and discharge protection control signal when the state parameter indicates that the lithium battery pack 600 is in an overcharge and overdischarge state.

[0042] In this embodiment, during normal use, the charging switch and the discharging switch inside the charge-discharge switch unit 300 are both in the on state, and at this time, the lithium battery pack 600 can be charged and discharged normally; when the lithium battery pack 600 is overcharged or over-discharged, the charging switch or the discharging switch inside the charge-discharge switch unit 300 is disconnected accordingly, thereby disconnecting the charging input terminal 301 from the positive port P+1; it can be understood that when the lithium battery pack 600 is charging, the discharging switch is connected, and when the lithium battery pack 600 is discharging, the charging switch is connected, that is, when the charge-discharge switch unit 300 is charging or discharging, the switch with the opposite function is in a working state, that is, it will not affect the control of a certain function.

[0043] In order to realize temperature detection and temperature protection control of the lithium battery pack 600, in some embodiments, reference is made to Figure 1 、 Figure 2 、 Figure 3 、 Figure 5 and Figure 6 The first control unit 100 further includes a temperature sensor RT1, one end of the temperature sensor RT1 is connected to the temperature protection detection port of the first lithium battery manager U1 (reference Figure 2 The other end of the temperature sensor RT1 is electrically connected to the negative power supply port VSS of the first lithium battery manager U1 and the first control unit 100, wherein:

[0044] The temperature sensor RT1 is used to detect the temperature of the lithium battery pack 600 during charging and discharging, and generate a corresponding first voltage signal;

[0045] The first lithium battery manager U1 is configured to control the charge and discharge switch unit 300 to disconnect the charging input terminal 301 from the positive port P+1 when detecting that the first voltage signal is greater than a preset temperature protection reference voltage.

[0046] To control the charge and discharge of the lithium battery pack 600, refer to Figure 1 、 Figure 2 、 Figure 3 and Figure 6 In some embodiments, the charge-discharge switch unit 300 includes a charge switch QC1, a discharge switch QD1, a filter unit 31, and a pre-discharge unit 32. The input end of the charge switch QC1 is connected to the charge input end 301, the controlled end of the charge switch QC1 is connected to the charge control port 303, the output end of the charge switch QC1 is electrically connected to the output end of the discharge switch QD1, the controlled end of the discharge switch QD1 is connected to the discharge controlled port 304, the input end of the discharge switch QD1 is connected to the output end of the charge-discharge switch unit 300, and the electrical connection point between the output end of the charge switch QC1 and the output end of the discharge switch QD1 is also connected to the secondary power input port of the first lithium battery manager U1 (reference) through the filter unit 31. Figure 2 and Figure 3 The input end of the discharge switch QD1 is also electrically connected to the pre-discharge unit 32, wherein,

[0047] In this embodiment, the filtering unit 31 includes a resistor R29 and a resistor R32 connected in series. One end of the resistor R29, which is remote from the electrical connection point with the resistor R32, is electrically connected to the electrical connection point between the output end of the charging switch QC1 and the output end of the discharging switch QD1. One end of the resistor R32, which is remote from the electrical connection point with the resistor R29, is electrically connected to capacitors C24 and C25 connected in parallel and to the secondary power input port of the first lithium battery manager U1. The other ends of the parallel capacitors C24 and C25 are connected to ground. In this embodiment, the drain voltage output by the first lithium battery manager U1 is filtered by the low-pass filtering circuit composed of the resistor R32, the resistor R29, the capacitors C24 and C25, so that the output ends of the charging switch QC1 and the discharging switch QD1 are connected to a stable voltage, thereby ensuring smooth switching of the charging switch QC1 and the discharging switch QD1.

[0048] The first control unit 100 is configured to generate a first charging protection control signal when the detected state parameter indicates that the lithium battery pack 600 is overcharged, and to generate a first discharging protection control signal when the detected state parameter indicates that the lithium battery pack 600 is over-discharged;

[0049] The charging switch QC1 is at least configured to control the charging input terminal 301 to be disconnected from the output terminal of the charging switch QC1 according to the first charging protection control signal.

[0050] In this embodiment, when the lithium battery pack 600 is overcharged, the first control unit 100 generates a first charging protection control signal to control the charging switch QC1 to be disconnected, that is, to stop charging. At this time, the level of the first charging protection control signal is a preset high level.

[0051] In this embodiment, the charging switch QC1 is a switching tube, which includes a control end, an input end, and an output end. The control end corresponding to the charging switch QC1 is connected to the controlled end of the charging switch QC1, the input end corresponding to the charging switch QC1 is connected to the input end of the charging switch QC1, and the output end corresponding to the charging switch QC1 is connected to the output end of the charging switch QC1. The charging switch QC1 controls the on / off of the input end and the output end of the corresponding switching tube according to the enable signal received by the control end of the corresponding switching tube. In this embodiment, when the input end and the output end of the switching tube corresponding to the charging switch QC1 (corresponding to QC1) are disconnected, the charging switch QC1 is disconnected, and the charge-discharge switch unit 300 controls the lithium battery pack 600 to stop charging.

[0052] The discharge switch QD1 is at least used for controlling the output end of the discharge switch QD1 to be disconnected from the positive port P+1 according to the first discharge protection control signal.

[0053] In this embodiment, the discharge switch QD1 is a switch tube, which includes a control end, an input end, and an output end. The control end corresponding to the discharge switch QD1 is connected to the controlled end of the discharge switch QD1, the input end corresponding to the discharge switch QD1 is connected to the input end of the discharge switch QD1, and the output end corresponding to the discharge switch QD1 is connected to the output end of the discharge switch QD1; the discharge switch QD1 controls the on and off of the input end and the output end of the corresponding switch tube according to the enable signal received by the control end of the corresponding switch tube; in this embodiment, when the input end and the output end of the switch tube corresponding to the discharge switch QD1 (corresponding to QD1) are disconnected, the discharge switch QD1 is disconnected, and the charge and discharge switch unit 300 controls the lithium battery pack 600 to stop discharging.

[0054] In this embodiment, when the lithium battery pack 600 is overcharged, the first control unit 100 generates a first discharge protection control signal to control the discharge switch QD1 to be disconnected, that is, to stop discharging. At this time, the level of the first discharge protection control signal is a preset high level.

[0055] The pre-discharge unit 32 is used to control the connection between the controlled terminal of the discharge switch QD1 and the positive port P+1, so as to control the discharge rate of the lithium battery pack 600.

[0056] In some optional embodiments, the pre-discharge unit 32 includes a pre-discharge switch Q2, the input end of the pre-discharge switch Q2 is electrically connected to the positive port, the controlled end of the pre-discharge switch Q2 is electrically connected to the first resistor R35 and the second resistor R36 respectively, the other end of the first resistor R35 is electrically connected to the positive port P+, the other end of the second resistor R36 is electrically connected to the cathode of the first clamping diode D10, the anode of the first clamping diode D10 is connected to the ground, and the output end of the pre-discharge switch Q2 is connected to the controlled end of the discharge switch QD1.

[0057] In this embodiment, the first clamping diode D10 includes but is not limited to a diode of model IN4148WS; the first resistor R35 is further connected in parallel with a zener diode of model MM3Z16, and the zener diode is used to clamp the controlled voltage at the controlled end of the pre-discharge switch Q2, so that the pre-discharge switch Q2 can stably switch.

[0058] In this embodiment, the pre-discharge unit 32 drives the discharge switch QD1 to perform pre-discharge, thereby adjusting the pre-discharge rate. In this embodiment, the pre-discharge switch Q2 is a switch tube, which includes a control end, an input end, and an output end. The control end corresponding to the pre-discharge switch Q2 is connected to the controlled end of the pre-discharge switch Q2, the input end corresponding to the pre-discharge switch Q2 is connected to the input end of the pre-discharge switch Q2, and the output end corresponding to the pre-discharge switch Q2 is connected to the output end of the pre-discharge switch Q2. The pre-discharge switch Q2 controls the on-off of the input end and the output end of the corresponding switch tube according to the enable signal received by the control end of the corresponding switch tube. In this embodiment, when the input end and the output end of the switch tube corresponding to the pre-discharge switch Q2 are connected, the pre-discharge switch Q2 is connected, and the controlled end of the discharge switch QD1 is connected to the positive port P+1, so that the discharge switch QD1 performs pre-discharge.

[0059] It should be noted that the switching tubes in the embodiments of the present application include but are not limited to triodes, MOS tubes, and field-effect transistors. Furthermore, based on the content disclosed in the present application, those skilled in the art can easily think of modifying the switching tubes disclosed in the present application into charging switches QC1, discharging switches QD1, and pre-discharging switches Q2 that are compatible with the specific selection of the switching tubes. Therefore, whether the switching tubes are NPN-type or PNP-type triodes, N-channel or P-channel switching MOS tubes, or N-type or P-type field-effect transistors, the present application can be implemented and is not limited in the embodiments of the present application. In some optional implementations, the switching tubes corresponding to the charging switch QC1 and the discharging switch QD1 are preferably PAS60N018C MOS tubes, and the pre-discharging switch Q2 is preferably 2N7002 MOS tubes.

[0060] To implement state parameter detection and secondary protection control of the lithium battery pack 600, refer to Figure 1 、 Figure 2 、 Figure 4 and Figure 5 In some embodiments, the second control unit 200 includes a second lithium battery manager U2 and a first RC filter circuit 21, and a plurality of second power positive ports (reference Figure 2 and Figure 4 VC1 to VC6 of U2 are all electrically connected to the positive electrode of a battery cell through an RC filter circuit 21 (refer to Figure 2 B+, B5, B4, B3, B2, B1 in FIG), the negative power input port VSS of the second lithium battery manager U2 is connected to the ground, and the charging control port CO of the second lithium battery manager U2 is electrically connected to the controlled end of the auxiliary protection switch unit 400 through a fourth coupling resistor R19 in series, wherein,

[0061] In this embodiment, the first RC filter circuit 21 includes a third resistor (refer to Figure 2 and Figure 4 R8 to R11, resistor R21 and resistor R20) and the first capacitor (reference Figure 2 and Figure 4 The L-type RC filter circuit is composed of C13, C12, C10, C7, C22, and C20.

[0062] The second lithium battery manager U2 is used to determine whether the lithium battery pack is charged normally by detecting the voltages of multiple battery cells, obtain corresponding state parameters, and generate corresponding second protection control signals according to the state parameters.

[0063] In some optional embodiments, the second lithium battery manager U2 includes but is not limited to a CM1270-A model battery secondary protection chip.

[0064] The auxiliary protection switch unit 400 is at least used to control the positive electrode B+ of the lithium battery pack 600 to be disconnected from the charging input terminal 301 according to the received second protection control signal when the state parameter indicates that the lithium battery pack 600 is overcharged.

[0065] In this embodiment, during normal charging, if the voltage of any battery cell exceeds the overcharge protection voltage and this state persists for longer than the overcharge protection delay time, the output of the charge control port CO of the second lithium battery manager U2 is flipped. Secondary protection is implemented via the auxiliary protection switch unit 400 at the charge control port CO. When the voltages of all batteries experiencing overcharge protection fall below the overcharge release voltage and this state persists for longer than the overcharge recovery delay time, the battery returns to normal operation. In this embodiment, during normal operation, if any one or more of the pins VC1, VC2, VC3, VC4, VC5, and VC6 of the second lithium battery manager U2 are disconnected from the battery cells, the second lithium battery manager U2 detects and determines a disconnection and forces the charge control port CO to output a protection state, thereby simultaneously entering the overcharge protection state. This state is referred to as the disconnection protection state. Once the disconnected connections are properly reconnected, the second lithium battery manager U2 exits the disconnection protection state.

[0066] To achieve secondary protection control of lithium battery pack, refer to Figure 1 、 Figure 2 and Figure 5In some embodiments, the auxiliary protection switch unit 400 includes a three-terminal fuse F1, an auxiliary protection switch Q1, and a second RC filter circuit. The three-terminal fuse F1 includes a first fuse port, a second fuse port, and a thermal fuse port. The second RC filter circuit includes a fourth resistor R18, a second capacitor C21, and a second clamping diode D4 connected in parallel. The first fuse port is electrically connected to the positive electrode B+ of the lithium battery pack 600, the second fuse port is connected to the charging input terminal 301, and the thermal fuse port is electrically connected to the input terminal (corresponding to the drain D) of the auxiliary protection switch Q1. The output terminal (corresponding to the source S) of the auxiliary protection switch Q1 is electrically connected to the first terminal of the fourth resistor R18, the first terminal of the second capacitor C21, and the anode of the second clamping diode D4, and is grounded. The controlled terminal (corresponding to the gate G) of the auxiliary protection switch Q1 is electrically connected to the second terminal of the fourth resistor R18, the second terminal of the second capacitor C21, the cathode of the second clamping diode D4, and the controlled terminal of the auxiliary protection switch unit 400, respectively.

[0067] The second RC filter circuit is used to filter the target control signal, wherein the target control signal includes one of the following: the first protection control signal, the first control signal, and the second protection control signal.

[0068] In this embodiment, the second clamping diode D4 includes but is not limited to a MM3Z16 voltage regulator diode.

[0069] The auxiliary protection switch Q1 is used to control the on / off of the input terminal and the output terminal of the auxiliary protection switch Q1 according to the level of the target control signal received by the controlled terminal.

[0070] In this embodiment, the auxiliary protection switch Q1 includes a switching tube, which includes a control end, an input end, and an output end. The control end corresponding to the auxiliary protection switch Q1 is connected to the controlled end of the auxiliary protection switch Q1, the input end corresponding to the auxiliary protection switch Q1 is connected to the input end of the auxiliary protection switch Q1, and the output end corresponding to the auxiliary protection switch Q1 is connected to the output end of the auxiliary protection switch Q1. The switching tube corresponding to the auxiliary protection switch Q1 controls whether the input end and the output end of the corresponding switching tube are connected or disconnected according to the level of the target control signal received at its control end.

[0071] The three-terminal fuse F1 is used to disconnect the first fuse port from the second fuse port when the input terminal of the auxiliary protection switch Q1 is connected to the delivery terminal, so as to disconnect the positive electrode B+ of the lithium battery pack 600 from the charging input terminal 301.

[0072] In this embodiment, the three-terminal fuse F1 includes but is not limited to a three-terminal fuse of model WPF15A6J.

[0073] It should be noted that the switching tubes in the embodiments of the present application include, but are not limited to, triodes, MOS tubes, and field-effect transistors. Furthermore, based on the disclosure of the present application, those skilled in the art will readily conceive of modifying the switching tube disclosed in the present application into an auxiliary protection switch Q1 adapted to the specific selection of the switching tube. Therefore, the present application can be implemented regardless of whether the switching tube is an NPN-type or PNP-type triode, an N-channel or P-channel switching MOS tube, or an N-type or P-type field-effect transistor, and this is not limited in the embodiments of the present application. In some optional implementations, the switching tube is preferably an AO344-type MOS tube.

[0074] In some optional embodiments, the charging switch QC1, the discharging switch QD1, the pre-discharging switch Q2 and the auxiliary protection switch Q1 are all switching tubes, and the switching tube includes a first control end, a first input end and a first output end; the first control end corresponding to the charging switch QC1 is connected to the controlled end of the charging switch QC1, the first input end corresponding to the charging switch QC1 is connected to the input end of the charging switch QC1, and the first output end corresponding to the charging switch QC1 is connected to the output end of the charging switch QC1; the first control end corresponding to the discharging switch QD1 is connected to the controlled end of the discharging switch QD1, and the first input end corresponding to the discharging switch QD1 is connected to the output end of the discharging switch QD1. The first output terminal of the discharge switch QD1 is connected to the output terminal of the discharge switch QD1; the first control terminal of the pre-discharge switch Q2 is connected to the controlled terminal of the pre-discharge switch Q2, the first input terminal of the pre-discharge switch Q2 is connected to the input terminal of the pre-discharge switch Q2, and the first output terminal of the pre-discharge switch Q2 is connected to the output terminal of the pre-discharge switch Q2; the first control terminal of the auxiliary protection switch Q1 is connected to the controlled terminal of the auxiliary protection switch Q1, the first input terminal of the auxiliary protection switch Q1 is connected to the input terminal of the auxiliary protection switch Q1, and the first output terminal of the auxiliary protection switch Q1 is connected to the output terminal of the auxiliary protection switch Q1, wherein,

[0075] The switch tube is used to control the on / off of the first input terminal and the first output terminal according to the enable signal received by the first control terminal;

[0076] When the first input terminal and the first output terminal of the switching tube corresponding to the charging switch QC1 are disconnected, the charging switch QC1 is disconnected; when the first input terminal and the first output terminal of the switching tube corresponding to the discharging switch QD1 are disconnected, the discharging switch QD1 is disconnected; when the first input terminal and the first output terminal of the switching tube corresponding to the pre-discharging switch Q2 are connected, the pre-discharging switch Q2 is connected; when the first input terminal and the first output terminal of the switching tube corresponding to the auxiliary protection switch Q1 are connected, the auxiliary protection switch Q1 is connected.

[0077] An embodiment of the present application further provides a lithium battery module, including a protection board, on which a protection circuit is provided, wherein the protection circuit is the lithium battery protection circuit in the above embodiment.

[0078] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive and also include other elements not explicitly listed, or also include elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0079] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but is intended to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A lithium battery protection circuit for protecting a lithium battery pack, characterized in that: The invention comprises a first control unit, a second control unit, a charge-discharge switch unit and an auxiliary protection switch unit. The first control unit is also connected to the external main controller via a two-wire serial bus. The first control unit and the second control unit are both electrically connected to the lithium battery pack and used to detect the state parameters of the lithium battery pack. The first control unit also controls the electrical connection between the charge-discharge switch unit and the auxiliary protection switch unit. The second control unit controls the electrical connection between the auxiliary protection switch unit. The input end of the auxiliary protection switch unit is electrically connected to the positive electrode of the lithium battery pack. The output end of the auxiliary protection switch unit is electrically connected to the charging input end of the charge-discharge switch unit. The output end of the charge-discharge switch unit is electrically connected to the positive port. The first control unit is configured to generate a charge-discharge protection control signal and a first protection control signal according to the detected state parameter; The second control unit is configured to generate a corresponding second protection control signal according to the detected state parameter; The charge and discharge switch unit is used to control the connection and disconnection between the charging input terminal and the positive port according to the charge and discharge protection control signal, so as to control the charge and discharge of the lithium battery pack; The peripheral main controller is configured to generate a first control signal according to the state parameter transmitted by the first control unit and send the first control signal to the first control unit at least when the charge and discharge switch unit cannot control the charge and discharge of the lithium battery pack; The auxiliary protection switch unit is at least used to control the on / off of the positive electrode of the lithium battery pack and the charging input terminal according to one of the first protection control signal and the first control signal sent by the first control unit and according to the second protection control signal sent by the second control unit, so as to perform secondary protection on the charging of the lithium battery pack, wherein the first control unit includes a first lithium battery manager, a capacitor voltage division sampling circuit and a first detection circuit; the first lithium battery manager is communicatively connected to the peripheral main controller, and the multiple first positive power supply ports of the first lithium battery manager are electrically connected to the positive electrodes of the multiple series-connected battery cells of the lithium battery pack in sequence, and the negative electrode of the lithium battery pack is electrically connected to the negative power supply port and the negative port of the first lithium battery manager respectively, and the charging control port and the discharge control port of the first lithium battery manager are both connected in series. The first coupling resistor is electrically connected to the charge controlled port and the discharge controlled port of the charge and discharge switch unit, respectively. The auxiliary protection control port of the first lithium battery manager is electrically connected to the controlled end of the auxiliary protection switch unit via a second coupling resistor in series. The capacitor voltage divider sampling circuit includes multiple sampling points, each of which is electrically connected to the positive electrode of a battery cell via a third coupling resistor in series. Each sampling point is also electrically connected to a corresponding first positive power supply port. The first detection circuit includes a π-type RC filter circuit and a sensing resistor, the sensing resistor is connected in series between the negative electrode of the lithium battery pack and the negative port. One end of the π-type RC filter circuit is electrically connected to the two analog input detection ports of the first lithium battery manager, respectively, and the other end of the π-type RC filter circuit is electrically connected to the first end and the second end of the sensing resistor, respectively. The first lithium battery manager is configured to detect the voltages of the plurality of battery cells connected in series through the capacitive voltage divider sampling circuit and the plurality of third coupling resistors, and to detect the charge and discharge currents of the lithium battery pack through the first detection circuit to obtain the state parameter. The first lithium battery manager is further configured to generate the charge and discharge protection control signal and the first protection control signal based on the state parameter; The auxiliary protection switch unit is configured to control the positive electrode of the lithium battery pack to be disconnected from the charging input terminal according to the received first control signal or the first protection control signal when the state parameter indicates that the lithium battery pack is in an unsafe charging and discharging state; The charge and discharge switch unit is used to control the charging input terminal to be disconnected from the positive port according to the received charge and discharge protection control signal when the state parameter indicates that the lithium battery pack is in an overcharge and overdischarge state.

2. The lithium battery protection circuit according to claim 1, characterized in that: The first control unit further includes a temperature sensor, one end of which is electrically connected to the temperature protection detection port of the first lithium battery manager, and the other end of which is electrically connected to the port of the first lithium battery manager connected to the negative power port of the first control unit, wherein: The temperature sensor is used to detect the temperature of the lithium battery pack during charging and discharging, and generate a corresponding first voltage signal; The first lithium battery manager is configured to control the charge and discharge switch unit to disconnect the charging input terminal from the positive port when detecting that the first voltage signal is greater than a preset temperature protection reference voltage.

3. The lithium battery protection circuit according to claim 2, characterized in that: The charge and discharge switch unit includes a charge switch, a discharge switch, a filter unit, and a pre-discharge unit. The input end of the charge switch is connected to the charge input end, the controlled end of the charge switch is connected to the charge control port, the output end of the charge switch is electrically connected to the output end of the discharge switch, the controlled end of the discharge switch is connected to the discharge controlled port, the input end of the discharge switch is connected to the output end of the charge and discharge switch unit, the electrical connection point between the output end of the charge switch and the output end of the discharge switch is also electrically connected to the secondary power input port of the first lithium battery manager through the filter unit, and the input end of the discharge switch is also electrically connected to the pre-discharge unit, wherein: The first control unit is configured to generate a first charging protection control signal when the detected state parameter indicates that the lithium battery pack is overcharged, and to generate a first discharging protection control signal when the detected state parameter indicates that the lithium battery pack is over-discharged; The charging switch is at least configured to control the disconnection between the charging input terminal and the output terminal of the charging switch according to the first charging protection control signal; The discharge switch is at least used to control the output end of the discharge switch to be disconnected from the positive port according to the first discharge protection control signal; The pre-discharge unit is used to control the on-off of the controlled end of the discharge switch and the positive port to control the discharge rate of the lithium battery pack.

4. The lithium battery protection circuit according to claim 3, characterized in that: The first lithium battery manager includes a multi-cell lithium-ion battery pack manager of the BQ40Z80 model, and / or, The pre-discharge unit includes a pre-discharge switch, an input end of the pre-discharge switch is electrically connected to the positive port, a controlled end of the pre-discharge switch is electrically connected to a first resistor and a second resistor, the other end of the first resistor is electrically connected to the positive port, the other end of the second resistor is electrically connected to the cathode of a first clamping diode, the anode of the first clamping diode is grounded, and the output end of the pre-discharge switch is connected to the controlled end of the discharge switch.

5. The lithium battery protection circuit according to claim 4, characterized in that: The second control unit includes a second lithium battery manager and a first RC filter circuit. The multiple second power positive ports of the second lithium battery manager are electrically connected to the positive electrode of one of the battery cells through one RC filter circuit. The negative power input port of the second lithium battery manager is connected to the ground. The charging control port of the second lithium battery manager is electrically connected to the controlled end of the auxiliary protection switch unit through a fourth coupling resistor in series. The second lithium battery manager is used to determine whether the lithium battery pack is charged normally by detecting the voltage of the plurality of battery cells, obtain the corresponding state parameter, and generate the corresponding second protection control signal according to the state parameter; The auxiliary protection switch unit is at least used to control the positive electrode of the lithium battery pack to be disconnected from the charging input terminal according to the received second protection control signal when the state parameter indicates that the lithium battery pack is overcharged.

6. The lithium battery protection circuit according to claim 5, characterized in that: The second lithium battery manager includes a CM1270-A model battery secondary protection chip, and / or the first RC filter circuit includes an L-type RC filter circuit composed of a third resistor and a first capacitor.

7. The lithium battery protection circuit according to claim 5, characterized in that: The auxiliary protection switch unit includes a three-terminal fuse, an auxiliary protection switch, and a second RC filter circuit. The three-terminal fuse includes a first fuse port, a second fuse port, and a heating fuse port. The second RC filter circuit includes a fourth resistor, a second capacitor, and a second clamping diode connected in parallel. The first fuse port is electrically connected to the positive electrode of the lithium battery pack, the second fuse port is connected to the charging input terminal, and the heating fuse port is electrically connected to the input terminal of the auxiliary protection switch. The output terminal of the auxiliary protection switch is electrically connected to the first terminal of the fourth resistor, the first terminal of the second capacitor, and the anode of the second clamping diode and is grounded. The controlled terminal of the auxiliary protection switch is electrically connected to the second terminal of the fourth resistor, the second terminal of the second capacitor, the cathode of the second clamping diode, and the controlled terminal of the auxiliary protection switch unit, respectively. The second RC filter circuit is configured to filter a target control signal, wherein the target control signal includes one of the following: the first protection control signal, the first control signal, and the second protection control signal; The auxiliary protection switch is configured to control the on / off of the input and output ends of the auxiliary protection switch according to the level of the target control signal received by the controlled end thereof; The three-terminal fuse is used to disconnect the first fuse port from the second fuse port when the input end of the auxiliary protection switch is connected to the delivery end, so as to disconnect the positive electrode of the lithium battery pack from the charging input end.

8. The lithium battery protection circuit according to claim 7, characterized in that: The charging switch, the discharging switch, the pre-discharging switch and the auxiliary protection switch all include a switching tube, and the switching tube includes a first control end, a first input end and a first output end; the first control end corresponding to the charging switch is connected to the controlled end of the charging switch, the first input end corresponding to the charging switch is connected to the input end of the charging switch, and the first output end corresponding to the charging switch is connected to the output end of the charging switch; the first control end corresponding to the discharging switch is connected to the controlled end of the discharging switch, the first input end corresponding to the discharging switch is connected to the input end of the discharging switch, and the first output end corresponding to the discharging switch is connected to the output end of the discharging switch; the first control end corresponding to the pre-discharging switch is connected to the controlled end of the pre-discharging switch, the first input end corresponding to the pre-discharging switch is connected to the input end of the pre-discharging switch, and the first output end corresponding to the pre-discharging switch is connected to the output end of the pre-discharging switch; The first control end corresponding to the auxiliary protection switch is connected to the controlled end of the auxiliary protection switch, the first input end corresponding to the auxiliary protection switch is connected to the input end of the auxiliary protection switch, and the first output end corresponding to the auxiliary protection switch is connected to the output end of the auxiliary protection switch, wherein: The switch tube is used to control the on / off of the first input terminal and the first output terminal according to the enable signal received by the first control terminal; When the first input end and the first output end of the switching tube corresponding to the charging switch are disconnected, the charging switch is disconnected; when the first input end and the first output end of the switching tube corresponding to the discharging switch are disconnected, the discharging switch is disconnected; when the first input end and the first output end of the switching tube corresponding to the pre-discharging switch are connected, the pre-discharging switch is connected; when the first input end and the first output end of the switching tube corresponding to the auxiliary protection switch are connected, the auxiliary protection switch is connected.

9. A lithium battery module, characterized in that: It comprises a protection board, on which a protection circuit is provided, wherein the protection circuit comprises the lithium battery protection circuit according to any one of claims 1 to 8.

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