Lithium ion battery pack protection circuit

Abstract

The lithium ion battery pack protection circuit comprises a control unit, a charging control unit, a discharging control unit and a voltage reduction module, a positive power supply port of the control unit is electrically connected with a positive electrode of a battery pack, and a plurality of battery positive connection ports of the control unit are electrically connected with positive electrodes of a plurality of battery cells; the negative electrode of the battery pack is electrically connected with the negative power supply port of the control unit, the charging detection negative port and the input end of the discharging control unit, the discharging detection port of the control unit is electrically connected with the discharging negative port, and the output end of the discharging control unit is electrically connected with the discharging negative port and the output end of the charging control unit; the controlled end of the discharging control unit is electrically connected with a discharging control port of the control unit, the controlled end of the charging control unit is electrically connected with a charging control port of the control unit, the input end of the charging control unit is electrically connected with the negative output end of the voltage reduction module and is grounded, and the positive output end of the voltage reduction module is electrically connected with the positive electrode of the battery pack. The input end of the voltage reduction module is electrically connected with the adaptive power supply.

Description

Technical Field

[0001] The present application relates to the technical field of lithium batteries, and particularly to a protection circuit for a lithium-ion battery pack. Background Art

[0002] For outdoor devices, such as advertising machines, an emergency power supply or a backup power supply is often set up to maintain emergency use for an expected period of time in the event of a power outage in the municipal power grid. In related technologies, a battery pack is used as a backup power supply for outdoor devices. However, in the existing technology, a lithium battery backup power supply composed of multiple batteries cannot be adapted to charge the backup power supply at a set voltage in an outdoor scenario. At the same time, during the DC-DC conversion of the corresponding backup power supply, the conversion efficiency is low, and during the charging process, effective overcurrent protection and temperature protection cannot be carried out, and there are safety risks during the use of the backup power supply.

[0003] In view of the problems of low conversion efficiency of the backup power supply, inadaptability to charging at a set voltage, and easy damage to the battery pack in related technologies, there is still a lack of a better technical solution. Summary of the Utility Model

[0004] The present application provides a protection circuit for a lithium-ion battery pack and a lithium battery pack to at least solve the problems of low conversion efficiency of the backup power supply, inadaptability to charging at a set voltage, and easy damage to the battery pack in related technologies.

[0005] The present application provides a protection circuit for a lithium-ion battery pack, including a control unit, a charging control unit, a discharging control unit, and a buck module. The positive power supply port of the control unit is electrically connected to the positive electrode of the lithium-ion battery pack. A plurality of battery positive connection ports of the control unit are sequentially electrically connected to the positive electrodes of a plurality of series-connected battery cells of the lithium-ion battery pack. The negative electrode of the lithium-ion battery pack is coupled and electrically connected to the negative power supply port of the control unit, the charging detection negative port, and the input end of the discharging control unit. The discharging detection port of the control unit is coupled and electrically connected to the discharging negative port. The output end of the discharging control unit is electrically connected to the discharging negative port and the output end of the charging control unit respectively. The controlled end of the discharging control unit is coupled and electrically connected to the discharging control port of the control unit. The controlled end of the charging control unit is coupled and electrically connected to the charging control port of the control unit. The input end of the charging control unit is electrically connected to the negative output end of the buck module and grounded. The positive output end of the buck module is electrically connected to the positive electrode of the lithium-ion battery pack. The input end of the buck module is electrically connected to an adapted power supply. Wherein, the control unit is configured to detect the voltages of a plurality of battery cells, and determine whether the battery pack is charging and discharging normally by detecting the voltages of the negative electrode and the discharging negative port. The control unit is further configured to control the discharging control unit to disconnect the negative electrode and the discharging negative port when it is determined that the battery pack is over-discharged, and to control the charging control unit to disconnect the negative electrode from the ground when it is determined that the battery pack is over-charged. The buck module is configured to convert a preset voltage input from the adapted power supply into a first target voltage, and charge the lithium-ion battery pack with the first target voltage when the control unit controls the charging control unit to connect the negative output end of the buck module to the charging control unit.

[0006] In some of these embodiments, the charging control unit includes a first drive circuit and a charging switch. The first drive circuit includes a voltage conversion circuit and a voltage clamping circuit. The input end of the voltage conversion circuit is connected to the controlled end of the charging control unit. The output end of the voltage conversion circuit is electrically connected to the input end of the voltage clamping circuit. The output end of the voltage clamping circuit is connected to the controlled end of the charging switch. The input end of the charging switch is connected to the input end of the charging control unit. The output end of the charging switch is connected to the output end of the charging control unit. Among them, the voltage conversion circuit is used to convert the level of the charging control signal output by the control unit to generate a first drive signal; the voltage clamping circuit is used to clamp the level of the first drive signal to generate a first control signal; the charging switch is used to control the on-off of its input end and output end according to the level of the first control signal received by its controlled end; when the input end and the output end of the charging switch are connected, the charging control unit controls the negative electrode to be grounded, and when the input end and the output end of the charging switch are disconnected, the charging control unit controls the negative electrode to be disconnected from the ground.

[0007] In some of these embodiments, the voltage conversion circuit includes a first resistor and a first switching tube. The first switching tube includes a first control end, a first input end, and a first output end. One end of the first resistor is connected to the controlled end of the charging control unit, and the other end of the first resistor is electrically connected to the first input end. The first control end is connected in series with a second resistor to the negative electrode. The first output end is connected to the output end of the voltage conversion circuit. Among them, the first resistor is used to couple the charging control signal to the first input end; the first switching tube is used to control the on-off of the first input end and the first output end according to the potential difference between the level of the charging control signal received by the first input end and the level of the first control end, and output the first drive signal of the corresponding level along the first output end.

[0008] In some of these embodiments, the voltage clamping circuit includes a first voltage regulator tube and a third resistor. The anode of the first voltage regulator tube is electrically connected to the first output end. The cathode of the first voltage regulator tube is electrically connected to the first end of the third resistor and the output end of the voltage clamping circuit respectively. The second end of the third resistor is grounded. Among them, the first voltage regulator tube is used to regulate the level of the first drive signal; the charging switch is used to control the on-off of its input end and output end according to the level of the first drive signal received by its controlled end; the third resistor is used to pull down the level of the control end of the charging switch to a preset low level when the input end and the output end of the charging switch are disconnected.

[0009] In some of these embodiments, the charging switch includes two second switching tubes connected in parallel. The second switching tube includes a second control end, a second input end, and a second output end. The second control end is docked with the controlled end of the charging switch, the second input end is docked with the input end of the charging switch, and the second output end is docked with the output end of the charging switch.

[0010] In some of these embodiments, the discharge control unit includes a second driving circuit and a discharge switch. The second driving circuit includes a fourth resistor, a fifth resistor, and a second voltage stabilizing tube. The first end of the fourth resistor is docked with the controlled end of the discharge control unit. The second end of the fourth resistor is electrically connected to the first end of the fifth resistor and the cathode of the second voltage stabilizing tube respectively. The second end of the fifth resistor and the anode of the second voltage stabilizing tube are electrically connected and docked with the controlled end of the discharge switch. The input end of the discharge switch is docked with the input end of the discharge control unit, and the output end of the discharge switch is docked with the output end of the discharge control unit. Among them, the fourth resistor is used to couple the discharge control signal output by the control unit to the voltage stabilizing circuit composed of the fifth resistor and the second voltage stabilizing tube; the voltage stabilizing circuit is used to stabilize the discharge control signal into a second control signal; the discharge switch is used to control the on-off of its input end and output end according to the level of the second control signal received by its controlled end; when the input end and the output end of the discharge switch are connected, the discharge control unit controls the negative electrode and the discharge negative port to be connected, and when the input end and the output end of the discharge switch are disconnected, the discharge control unit controls the negative electrode and the discharge negative port to be disconnected.

[0011] In some of these embodiments, the discharge switch includes two third switching tubes connected in parallel. The third switching tube includes a third control end, a third input end, and a third output end. The third control end is docked with the controlled end of the discharge switch, the third input end is docked with the input end of the discharge switch, and the third output end is docked with the output end of the discharge switch.

[0012] In some of these embodiments, the buck module includes an EG1163 buck control chip, a synchronous rectifier buck conversion circuit, an output filter circuit, a feedback circuit, and an overcurrent temperature protection circuit. The power supply port of the EG1163 buck control chip is electrically connected to the positive pole of the adapted power supply. The output control high end and the output control low end of the EG1163 buck control chip are respectively electrically connected to the first drive controlled end and the second drive controlled end of the synchronous rectifier buck conversion circuit. The power output end of the synchronous rectifier buck conversion circuit is electrically connected to the input end of the output filter circuit and the input end of the feedback circuit. The output end of the output filter circuit is connected to the positive output end of the buck module. The feedback end of the feedback circuit is electrically connected to the feedback port of the EG1163 buck chip. The overcurrent temperature protection circuit includes an EG358 operational amplifier chip. The EG358 operational amplifier chip includes a first non-inverting input terminal, a first inverting input terminal, a first operational amplifier output terminal, a second non-inverting input terminal, a second inverting input terminal, and a second operational amplifier output terminal. The first non-inverting input terminal receives a first reference voltage provided by a first voltage dividing circuit. The first inverting input terminal is electrically connected to the negative output end of the buck module through a series-connected sixth resistor. The second non-inverting input terminal receives a second reference voltage provided by a second voltage dividing circuit. The second inverting input terminal is electrically connected to an NTC temperature detection sensor installed in the synchronous rectifier buck conversion circuit. Both the first operational amplifier output terminal and the second operational amplifier output terminal are coupled and electrically connected to the voltage loop operational amplifier output port of the EG1163 buck chip. Among them, after being driven to start, the EG1163 buck control chip controls the synchronous rectifier buck conversion circuit to step down a preset voltage to a first charging voltage; the output filter circuit is used to filter the first charging voltage to generate the first target voltage; the feedback circuit is used to input a feedback voltage reflecting the change of the first charging voltage collected into the feedback port of the EG1163 buck chip, so that the EG1163 buck control chip controls the synchronous rectifier buck conversion circuit to output a stable first charging voltage; the EG358 operational amplifier chip is used to output an overcurrent control signal along the first operational amplifier output port according to the comparison result between the voltage received by the first inverting input terminal and the first reference voltage, and output a temperature protection control signal along the second operational amplifier output port according to the comparison result between the voltage received by the second inverting input terminal and the second reference voltage; when the level of the overcurrent control signal or the temperature protection control signal received at the voltage loop operational amplifier output port is the target level, the EG1163 buck control chip is enabled to turn off, and the buck module stops outputting the first target voltage.

[0013] In some of these embodiments, the output filter circuit includes a plurality of filter capacitors connected in parallel and two voltage-regulating diodes connected in parallel. The positive electrodes of the plurality of filter capacitors are electrically connected to the input end of the output filter circuit and the anodes of the two voltage-regulating diodes. The cathodes of the two voltage-regulating diodes are connected to the output end of the output filter circuit. The feedback circuit includes a sixth resistor, a seventh resistor, and an eighth resistor connected in series. The first end of the sixth resistor is connected to the input end of the feedback circuit. The second end of the sixth resistor is electrically connected to the first end of the seventh resistor. The second end of the seventh resistor is electrically connected to both the output end of the feedback circuit and the first end of the eighth resistor. The second end of the eighth resistor is grounded. The synchronous rectifier buck conversion circuit includes a high-side MOS transistor, a synchronous rectifier MOS transistor, a third drive circuit, and an output inductor. The control terminal of the high-side MOS transistor is connected to the first drive controlled terminal through one of the third drive circuits. The input terminal of the high-side MOS transistor is electrically connected to the positive electrode of the adapted power supply. The output terminal of the high-side MOS transistor is electrically connected to both the output inductor and the input terminal of the synchronous rectifier MOS transistor. The control terminal of the synchronous rectifier MOS transistor is connected to the second drive controlled terminal through one of the third drive circuits. The output terminal of the synchronous rectifier MOS transistor is grounded. The other end of the output inductor is connected to the power output terminal of the synchronous rectifier buck conversion circuit. Among them, the third drive circuit includes a current-limiting resistor, a clamping resistor, and a clamping diode. The clamping resistor and the clamping diode are connected in series and then connected in parallel with the current-limiting resistor. The electrical connection point of the current-limiting resistor and the clamping resistor is electrically connected to the first drive controlled terminal or the second drive controlled terminal. The electrical connection point of the current-limiting resistor and the clamping diode is electrically connected to the control terminal of the high-side MOS transistor or the control terminal of the synchronous rectifier MOS transistor. The high-side MOS transistor is configured to control the on / off of the input terminal and the output terminal of the high-side MOS transistor according to the level of the first rectification control signal received at its control terminal. The synchronous rectifier MOS transistor is configured to control the on / off of the input terminal and the output terminal of the synchronous rectifier MOS transistor according to the level of the first rectification control signal received at its control terminal. The EG1163 buck control chip is configured to control the interlocking on / off of the high-side MOS transistor and the synchronous rectifier MOS transistor, so that the output inductor converts the preset voltage into the first charging voltage.

[0014] In some of these embodiments, the control unit includes a battery protection chip of the CW1244AFAS model.

[0015] Compared with the related art, in this embodiment, a protection circuit for a lithium-ion battery pack is provided. The charging control unit and the discharging control unit are controlled by a control unit to disconnect the negative electrode and the discharging negative port when the lithium-ion battery pack is over-discharged, and to disconnect the negative electrode from the ground when it is determined that the lithium-ion battery pack is over-charged, thereby protecting the charging and discharging of the lithium-ion battery pack. At the same time, a preset voltage provided by an adapter power supply is converted into a first target voltage through a buck module to charge the lithium-ion battery pack. At the same time, over-current detection protection and temperature protection control are carried out through the buck module during charging to further effectively protect the lithium-ion battery pack and extend the service life of the corresponding backup power supply, solving the problems of low conversion efficiency of the backup power supply, inadaptability to the set voltage for charging and easy damage to the battery pack in the related art.

[0016] 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 concise and understandable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present invention and used together with the specification to explain the principles of the present invention.

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a structural block diagram of a protection circuit for a lithium-ion battery pack provided by an embodiment of the present application;

[0020] Figure 2 It is a topological structure diagram of the control unit, the charging control unit and the discharging control unit in an embodiment of the present application;

[0021] Figure 3 It is a topological circuit diagram of the buck module in a preferred embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0023] The lithium-ion battery pack protection circuit of the present application will be described below in combination with the accompanying drawings in the embodiments of the present application and through specific embodiments.

[0024] Figure 1 It is a structural block diagram of a lithium-ion battery pack protection circuit provided in an embodiment of the present application. As Figure 1 shown, an embodiment of the present application provides a lithium-ion battery pack protection circuit, including a control unit 100, a charge control unit 200, a discharge control unit 300, and a buck module 400. The positive power supply port 101 of the control unit 100 is electrically connected to the positive electrode 002 of the lithium-ion battery pack 001. Multiple battery positive connection ports (refer to Figure 2 the VC1 to VC4 pins of IC1 in the figure) of the control unit 100 are sequentially electrically connected to the positive electrodes of multiple series-connected battery cells of the lithium-ion battery pack 001 (refer to Figure 2 B1 to B3 and B+ in the figure), the negative electrode 003 of the lithium-ion battery pack 001 (refer to Figure 2 B- in the figure) is coupled and electrically connected to the negative power supply port of the control unit 100 (refer to Figure 2 the VSS pin of IC1 in the figure), the charge detection negative port B-, and the input end 301 of the discharge control unit 300. The discharge detection port of the control unit 100 (refer to Figure 2 the VM pin of IC1 in the figure) is coupled and electrically connected to the discharge negative port P-. The output end 302 of the discharge control unit 300 is respectively electrically connected to the discharge negative port P- and the output end 202 of the charge control unit 200. The controlled end 303 of the discharge control unit 300 is coupled and electrically connected to the discharge control port 102 of the control unit 100. The controlled end 203 of the charge control unit 200 is coupled and electrically connected to the charge control port 103 of the control unit 100. The input end 201 of the charge control unit 200 is electrically connected to the negative output end 401 of the buck module 400 and grounded. The positive output end 402 of the buck module 400 is electrically connected to the positive electrode 002 of the lithium-ion battery pack 001 (it can also refer to P+ / B+). The input end of the buck module 400 (refer to C+, C-) is electrically connected to the adapter power supply 004. Among them,

[0025] the control unit 100 is used to detect the voltages of multiple battery cells, and to determine whether the lithium-ion battery pack 001 is charging and discharging normally by detecting the voltages of the negative electrode 003 and the discharge negative port P-. The control unit 100 is also used to control the discharge control unit 300 to disconnect the negative electrode 003 and the discharge negative port P- when it is determined that the lithium-ion battery pack 001 is over-discharged, and to control the charge control unit 200 to disconnect the negative electrode 003 from the ground when it is determined that the lithium-ion battery pack 001 is over-charged.

[0026] In some of these alternative embodiments, the control unit 100 includes, but is not limited to, a battery protection chip of model CW1244AFAS (refer to Figure 2 IC1 in

[0027] In this embodiment, when the lithium-ion battery pack 001 is operating normally, the control unit 100 controls the discharge control unit 300 to connect the negative electrode 003 and the discharge negative port P-, and controls the charging control unit 200 to connect the negative electrode 003 to the ground, so that the lithium-ion battery pack 001 can be charged and discharged normally.

[0028] The buck module 400 is used to convert the preset voltage input from the adapted power supply 004 into a first target voltage, and when the control unit 100 controls the charging control unit 200 to connect the negative output terminal 401 of the buck module 400 to the charging control unit 200, charge the lithium-ion battery pack 001 with the first target voltage.

[0029] In this embodiment, while the buck module 400 satisfies providing the first target voltage for the lithium-ion battery pack 001, it also detects and protects the overcharge and overcurrent of the lithium-ion battery pack 001, and performs temperature protection when charging the lithium-ion battery pack 001. For example, when the lithium-ion battery pack 001 is overcurrent or over-temperature protected, the buck module 400 is turned off.

[0030] The above-mentioned lithium-ion battery pack protection circuit controls the charging control unit 200 and the discharge control unit 300 through the control unit 100. When the lithium-ion battery pack 001 is overdischarged, the discharge control unit 300 is controlled to disconnect the negative electrode B- and the discharge negative port P-, and when it is determined that the lithium-ion battery pack 001 is overcharged, the charging control unit 200 is controlled to disconnect the negative electrode B- from the ground, thereby protecting the charging and discharging of the lithium-ion battery pack. At the same time, the buck module 400 converts the preset voltage provided by the adapted power supply 004 into a first target voltage to charge the lithium-ion battery pack 001. At the same time, overcurrent detection protection and temperature protection control are performed during charging through the buck module 400 to further effectively protect the lithium-ion battery pack 001 and extend the service life of the corresponding backup power supply, solving the problems of low conversion efficiency of the backup power supply, inadaptability to the set voltage for charging, and easy damage to the battery pack in the related art.

[0031] Figure 2 It is a topology diagram of the control unit, charging control unit, and discharge control unit of the embodiment of the present application. For controlling the charging of the lithium-ion battery pack, refer to Figures 1 to 2, in some embodiments, the charging control unit 200 includes a first driving circuit 21 and a charging switch 22. The first driving circuit 21 includes a voltage conversion circuit 211 and a voltage clamping circuit 212. The input end of the voltage conversion circuit 211 is connected to the controlled end 201 of the charging control unit 200 (refer to Figure 2 the CO pin of IC1 in

[0032] ). The output end of the voltage conversion circuit 211 is electrically connected to the input end of the voltage clamping circuit 212. The output end of the voltage clamping circuit 212 is connected to the controlled end of the charging switch 22. The input end of the charging switch 22 is connected to the input end 201 of the charging control unit 200. The output end of the charging switch 22 is connected to the output end 202 of the charging control unit 200. Among them,

[0032] the voltage conversion circuit 211 is used to convert the level of the charging control signal output by the control unit 100 to generate a first driving signal.

[0033] In this embodiment, the voltage conversion circuit 211 includes a first resistor RC1 and a first switching tube Q13. The first switching tube Q13 includes a first control end, a first input end, and a first output end. One end of the first resistor RC1 is connected to the controlled end 203 of the charging control unit 200. The other end of the first resistor RC1 is electrically connected to the first input end. The first control end is connected in series with a second resistor R4C to the negative electrode B-. The first output end is connected to the output end of the voltage conversion circuit (refer to Figure 2 in

[0034] ). Among them,

[0035] the first resistor RC1 is used to couple the charging control signal to the first input end.

[0035] the first switching tube Q13 is used to control the on / off of the first input end and the first output end according to the potential difference between the level of the charging control signal received by the first input end and the level of the first control end, and output a first driving signal with a corresponding level along the first output end.

[0036] In this embodiment, when the level of the charging control signal received by the first input end is greater than the level of the first control end, the first input end is connected to the first output end. When the level of the charging control signal received by the first input end is not greater than the level of the first control end, the first input end is disconnected from the first output end.

[0037] It should be noted that the first switching transistor Q13 in the embodiments of the present application includes, but is not limited to, a triode, a MOS transistor, and a field-effect transistor. Moreover, according to the content disclosed in the present application, those skilled in the art can easily think of modifying the first switching transistor disclosed in the present application into a voltage conversion circuit adapted to the specific selection of the switching transistor according to the specific type of the first switching transistor. Therefore, whether the switching transistor is an NPN or PNP triode, an N-channel or P-channel switching MOS transistor, or an N-type or P-type field-effect transistor, the present application can be implemented, and no limitation is made in the embodiments of the present application; in some alternative embodiments, the first switching transistor is preferably a PNP triode of the MMBT5401 model.

[0038] A voltage clamping circuit 212, configured to clamp the level of the first driving signal to generate a first control signal.

[0039] In this embodiment, the voltage clamping circuit 212 includes a first voltage regulator diode D3A and a third resistor R9C. The anode of the first voltage regulator diode D3A is electrically connected to the first output terminal, the cathode of the first voltage regulator diode D3A is electrically connected to the first end of the third resistor R9C and the output terminal of the voltage clamping circuit 212 respectively, and the second end of the third resistor R9C is grounded. Among them, the first voltage regulator diode D3A is used to regulate the level of the first driving signal; the third resistor R9C is used to pull down the level of the control terminal of the charging switch 22 to a preset low level when the input terminal and the output terminal of the charging switch 22 are disconnected; in this embodiment, when the charging switch 22 controls its input terminal and output terminal to be disconnected, through the third resistor R9C, the gate level of the corresponding second switching transistor is controlled to be effectively low, avoiding the charging switch 22 from being misdriven and turned on.

[0040] A charging switch 22, configured to control the on / off of its input terminal and output terminal according to the level of the first control signal received by its controlled terminal.

[0041] When the input terminal and the output terminal of the charging switch 22 are connected, the charging control unit 200 controls the negative electrode B- to be grounded, and when the input terminal and the output terminal of the charging switch 22 are disconnected, the charging control unit 200 controls the negative electrode B- to be disconnected from the ground.

[0042] In some alternative embodiments, the charging switch 22 includes two second switching transistors (QC1 and QC2 shown in Figure 2 ) connected in parallel. The second switching transistor includes a second control terminal, a second input terminal, and a second output terminal. The second control terminal is docked with the controlled terminal of the charging switch 22, the second input terminal is docked with the input terminal of the charging switch 22, and the second output terminal is docked with the output terminal of the charging switch 22.

[0043] It should be noted that the second switching tube in the embodiments of the present application includes, but is not limited to, triodes, MOS tubes, and field effect transistors. Moreover, based on the content disclosed in the present application, those skilled in the art can easily think of modifying the second switching tube disclosed in the present application into a voltage conversion circuit adapted to the selected type of switching tube according to the specific selection of the second switching tube. Therefore, 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, the present application can be implemented, and no limitation is made in the embodiments of the present application; in this embodiment, the second switching tube is preferably an NMOS tube of model TF040N03.

[0044] In this embodiment, when the second switching tube is an NMOS tube, if the level of the first driving signal corresponds to a high level (the voltage satisfies the voltage for turning on the charging switch 22, for example: +5V), the second switching tube corresponding to the charging switch 22 controls its input terminal (corresponding to the drain of the NMOS tube) to communicate with the output terminal (corresponding to the source of the NMOS tube). If the level of the first driving signal corresponds to a low level (for example: +0V or a low level not greater than 2V), the second switching tube corresponding to the charging switch 22 controls its input terminal (corresponding to the drain of the NMOS tube) to disconnect from the output terminal (corresponding to the source of the NMOS tube).

[0045] To control the discharge of the lithium-ion battery pack, refer to Figures 1 to 2 , in some of these embodiments, the discharge control unit 300 includes a second driving circuit 31 and a discharge switch 32. The second driving circuit 31 includes a fourth resistor R2C, a fifth resistor R3C, and a second zener diode D2A. The first end of the fourth resistor R2C is connected to the controlled terminal 303 of the discharge control unit 300 (refer to Figure 2 the DO pin of IC1 in

[0046] The fourth resistor R2C is used to couple the discharge control signal output by the control unit to the voltage stabilizing circuit composed of the fifth resistor R3C and the second zener diode D2A;

[0047] The voltage stabilizing circuit is used to stabilize the discharge control signal into a second control signal;

[0048] The discharge switch 32 is used to control the on / off of its input terminal and output terminal according to the level of the second control signal received by its controlled terminal.

[0049] In this embodiment, the discharge switch 32 includes two third switching tubes connected in parallel (refer to QD1 and QD2 in Figure 2 ), the third switching tube includes a third control terminal, a third input terminal and a third output terminal, the third control terminal is docked with the controlled terminal of the discharge switch 32, the third input terminal is docked with the input terminal of the discharge switch 32, and the third output terminal is docked with the output terminal of the discharge switch 32.

[0050] It should be noted that the third switching tube in the embodiments of the present application includes, but is not limited to, triodes, MOS tubes, and field effect transistors. And, according to the content disclosed in the present application, those skilled in the art can easily think of modifying the third switching tube disclosed in the present application into a voltage conversion circuit adapted to the specific selection of the switching tube. Therefore, whether the switching tube is an NPN or PNP triode, or an N-channel or P-channel switching MOS tube, or an N-type or P-type field effect transistor, the present application can be implemented, and it is not limited in the embodiments of the present application; in this embodiment, the third switching tube preferably uses an NMOS tube of the TF040N03 model.

[0051] In this embodiment, when the third switching tube is an NMOS tube, if the level of the second control signal corresponds to a high level (the voltage satisfies the voltage for turning on the discharge switch 32, for example: +5V), the third switching tube corresponding to the discharge switch 32 controls its input terminal (corresponding to the drain of the NMOS tube) to be connected to the output terminal (corresponding to the source of the NMOS tube). If the level of the second control signal corresponds to a low level (for example: +0V or a low level not greater than 2V), the third switching tube corresponding to the discharge switch 32 controls its input terminal (corresponding to the drain of the NMOS tube) to be disconnected from the output terminal (corresponding to the source of the NMOS tube).

[0052] In this embodiment, when the input terminal and the output terminal of the discharge switch 32 are connected, the discharge control unit 300 controls the negative electrode B- to be connected to the discharge negative port P-, and when the input terminal and the output terminal of the discharge switch 32 are disconnected, the discharge control unit 300 controls the negative electrode B- to be disconnected from the discharge negative port P-.

[0053] Figure 3 is the topological circuit diagram of the buck module of the preferred embodiment of the present application. To realize power supply and charging to the lithium-ion battery, refer to Figure 1 and Figure 3 , the buck module of the embodiments of the present application includes an EG1163 buck control chip U2, a synchronous rectification buck conversion circuit 41, an output filter circuit 42, a feedback circuit 43 and an overcurrent temperature protection circuit 44. The power supply port of the EG1163 buck control chip U2 (refer to the VCC pin of U2 in Figure 3 ) is connected to the adapted power supply 004 (refer to Figure 3is electrically connected to the positive electrode (C+) of C+ and C- therein. The output control high end HO and the output control low end LO of the EG1163 buck control chip U2 are respectively electrically connected to the first drive controlled end and the second drive controlled end of the synchronous rectification buck conversion circuit 41. The power output end of the synchronous rectification buck conversion circuit 41 is electrically connected to the input end of the output filter circuit 42 and the input end of the feedback circuit 43. The output end of the output filter circuit 42 is connected to the positive output end B+ of the buck module 400. The feedback end of the feedback circuit 43 is electrically connected to the feedback port FB of the EG1163 buck chip U2. The overcurrent temperature protection circuit 44 includes an EG358 operational amplifier chip U1. The EG358 operational amplifier chip U1 includes a first non-inverting input terminal +IN1, a first inverting input terminal -IN1, a first operational amplifier output terminal OUT1, a second non-inverting input terminal +IN2, a second inverting input terminal -IN2, and a second operational amplifier output terminal OUT2. The first non-inverting input terminal +IN1 is connected to a first reference voltage provided by a first voltage dividing circuit (refer to Figure 3 the voltage dividing circuit composed of resistor R1, resistor R2, and resistor R9 therein), corresponding to the voltage at the electrical connection point of resistor R9 and resistors R1 and R2. The first inverting input terminal -IN1 is electrically connected to the negative output terminal 401 of the buck module 400 (corresponding to the ground of the buck module 400, refer to Figure 3 GND1 therein) through a series-connected sixth resistor R8. The second non-inverting input terminal +IN2 is connected to a second reference voltage provided by a second voltage dividing circuit (refer to Figure 3 the voltage dividing circuit composed of resistor R17 and resistor R18 therein), corresponding to the voltage at the electrical connection point of resistor R17 and resistor R18. The second inverting input terminal -IN2 is electrically connected to an NTC temperature detection sensor installed in the synchronous rectification buck conversion circuit (refer to Figure 3 R14 therein, and the corresponding drive circuit is composed of R12, R13, and R15). Both the first operational amplifier output terminal OUT1 and the second operational amplifier output terminal OUT2 are coupled and electrically connected to the voltage loop operational amplifier output port of the EG1163 buck chip U2 (refer to Figure 3 the ERRO pin of U2 therein). Among them,

[0054] After being driven to start, the EG1163 buck control chip U2 controls the synchronous rectification buck conversion circuit 41 to step down a preset voltage to a first charging voltage.

[0055] It should be noted that the start of the EG1163 buck control chip U2 and the corresponding driving of the synchronous rectification buck conversion circuit 41 for power conversion are clear and understandable to those skilled in the art, and do not constitute an unclear limitation to this application.

[0056] The output filter circuit 42 is used to filter the first charging voltage to generate a first target voltage.

[0057] In this embodiment, the output filter circuit 42 includes a plurality of parallel-connected filter capacitors (refer to E1, E3, E5, C16, C17, C18 in Figure 3 ), and two parallel-connected voltage-regulating diodes (refer to D7, D8 in Figure 3 ). The positive electrodes of the plurality of filter capacitors are electrically connected to the input end of the output filter circuit 42 and the anodes of the two voltage-regulating diodes, and the cathodes of the two voltage-regulating diodes are connected to the output end of the output filter circuit.

[0058] The feedback circuit 43 is configured to input the feedback voltage collected and reflecting the change of the first charging voltage into the feedback port FB of the EG1163 step-down chip U2, so that the EG1163 step-down control chip U2 controls the synchronous rectification step-down conversion circuit 42 to output a stable first charging voltage.

[0059] In this embodiment, the feedback circuit 43 includes a serially-connected sixth resistor R73, seventh resistor R31, and eighth resistor R32. The first end of the sixth resistor R73 is connected to the input end of the feedback circuit 43 (refer to the opposite-name end of the output inductor L1 in Figure 3 ), the second end of the sixth resistor R73 is electrically connected to the first end of the seventh resistor R31, the second end of the seventh resistor R31 is electrically connected to the output end of the feedback circuit 43 and the first end of the eighth resistor R32, and the second end of the eighth resistor R3 is grounded.

[0060] The EG358 operational amplifier chip U1 is configured to output an overcurrent control signal along the first operational amplifier output port OUT1 according to the comparison result between the voltage received by the first inverting input terminal -IN1 and the first reference voltage, and output a temperature protection control signal along the second operational amplifier output port OUT2 according to the comparison result between the voltage received by the second inverting input terminal -IN2 and the second reference voltage.

[0061] When the level of the overcurrent control signal or the temperature protection control signal received at the voltage loop operational amplifier output port ERRO is the target level (a preset level value, for example: low level), the EG1163 step-down control chip U2 is enabled to be turned off, and the step-down module 400 stops outputting the first target voltage.

[0062] In this embodiment, the synchronous rectification step-down conversion circuit 41 includes a high-side MOS transistor Q1, a synchronous rectification MOS transistor Q2, a third drive circuit 411, and an output inductor L1. The control end of the high-side MOS transistor Q1 passes through a third drive circuit 411 (refer to Figure 3The drive circuit composed of resistor R39, resistor R20, and diode D4 in it) is connected to the first drive controlled terminal. The input terminal of high-side MOS transistor Q1 is electrically connected to the positive electrode C+ of the adapted power supply 004. The output terminal of high-side MOS transistor Q1 is electrically connected to the output inductor L1 and the input terminal of synchronous rectifier MOS transistor Q2 respectively. The control terminal of synchronous rectifier MOS transistor Q2 is connected to the second drive controlled terminal through a third drive circuit (refer to Figure 3 The drive circuit composed of resistor R40, resistor R21, and diode D5 in it) is connected to the second drive controlled terminal. The output terminal of synchronous rectifier MOS transistor Q2 is grounded, and the other end of output inductor L2 is connected to the power output terminal of synchronous rectifier buck conversion circuit 41. Among them,

[0063] The third drive circuit 411 includes a current-limiting resistor (refer to Figure 3 R20 and R21 in it), a clamping resistor (refer to Figure 3 R39 and R40 in it), and a clamping diode (refer to Figure 3 D4, D5 in it). The clamping resistor and the clamping diode are connected in series and then in parallel with the current-limiting resistor. The electrical connection point of the current-limiting resistor and the clamping resistor is electrically connected to the first drive controlled terminal or the second drive controlled terminal. The electrical connection point of the current-limiting resistor and the clamping diode is electrically connected to the control terminal of the high-side MOS transistor or the control terminal of the synchronous rectifier MOS transistor.

[0064] The high-side MOS transistor Q1 is used to control the on / off of the input terminal and the output terminal of the high-side MOS transistor Q1 according to the level of the first rectification control signal received by its control terminal.

[0065] The synchronous rectifier MOS transistor Q2 is used to control the on / off of the input terminal and the output terminal of the synchronous rectifier MOS transistor Q2 according to the level of the first rectification control signal received by its control terminal.

[0066] The EG1163 buck control chip U2 is used to control the interlocked on / off of the high-side MOS transistor Q1 and the synchronous rectifier MOS transistor Q2, so that the output inductor L1 converts the preset voltage into the first charging voltage.

[0067] It can be understood that the buck module 400 in the embodiments of the present application can be a synchronous rectifier buck controller composed of EG1163 combined with EG358 in the prior art or a high-efficiency synchronous rectifier non-isolated DC-DC based on EG1163 and EG358, for example: the constant voltage and constant current synchronous rectifier module disclosed by EG (Yijing Micro).

[0068] It should be noted that in this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, and also include other elements not expressly listed, or elements inherent to such a process, method, article or apparatus. Without further limitation, an element defined by the statement "comprising a..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising the said element.

[0069] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A lithium-ion battery pack protection circuit, characterized in that: It includes a control unit, a charging control unit, a discharging control unit and a step-down module, wherein the positive power supply port of the control unit is electrically connected to the positive pole of a lithium-ion battery pack, the multiple battery positive connection ports of the control unit are electrically connected to the positive poles of multiple battery cells connected in series in the lithium-ion battery pack in sequence, the negative pole of the lithium-ion battery pack is coupled and electrically connected to the negative power supply port of the control unit, the charging detection negative port and the input end of the discharging control unit, the discharging detection port of the control unit is coupled and electrically connected to the discharging negative port, the output end of the discharging control unit is electrically connected to the discharging negative port and the output end of the charging control unit respectively, the controlled end of the discharging control unit is coupled and electrically connected to the discharging control port of the control unit, the controlled end of the charging control unit is coupled and electrically connected to the charging control port of the control unit, the input end of the charging control unit is electrically connected to the negative output end of the step-down module and to the ground, the positive output end of the step-down module is electrically connected to the positive pole of the lithium-ion battery pack, and the input end of the step-down module is electrically connected to an adaptor power supply, wherein: The control unit is used to detect the voltage of multiple battery cells, and to determine whether the battery pack is charged and discharged normally by detecting the voltage of the negative electrode and the negative discharge port. The control unit is also used to control the discharge control unit to disconnect the negative electrode and the negative discharge port when it is determined that the battery pack is over-discharged, and to control the charge control unit to disconnect the negative electrode from the ground when it is determined that the battery pack is over-charged; The step-down module is used to convert the preset voltage of the adaptive power supply input into a first target voltage, and when the control unit controls the charging control unit to connect the negative output end of the step-down module with the charging control unit, the lithium-ion battery pack is charged at the first target voltage.

2. The lithium-ion battery pack protection circuit according to claim 1, characterized in that: The charging control unit includes a first driving circuit and a charging switch, wherein the first driving circuit includes a voltage conversion circuit and a voltage clamping circuit, wherein the input end of the voltage conversion circuit is connected to the controlled end of the charging control unit, the output end of the voltage conversion circuit is electrically connected to the input end of the voltage clamping circuit, the output end of the voltage clamping circuit is connected to the controlled end of the charging switch, the input end of the charging switch is connected to the input end of the charging control unit, and the output end of the charging switch is connected to the output end of the charging control unit, wherein: The voltage conversion circuit is used to convert the level of the charging control signal output by the control unit to generate a first driving signal; The voltage clamping circuit is used to clamp the level of the first driving signal to generate a first control signal; The charging switch is used to control the on and off of its input end and output end according to the level of the first control signal received by its controlled end; When the input end and the output end of the charging switch are connected, the charging control unit controls the negative electrode to be connected to the ground, and when the input end and the output end of the charging switch are disconnected, the charging control unit controls the negative electrode to be disconnected from the ground.

3. The lithium-ion battery pack protection circuit according to claim 2, characterized in that: The voltage conversion circuit includes a first resistor and a first switch tube, the first switch tube includes a first control end, a first input end and a first output end, one end of the first resistor is connected to the controlled end of the charging control unit, the other end of the first resistor is electrically connected to the first input end, the first control end is connected in series with a second resistor and is electrically connected to the negative electrode, and the first output end is connected to the output end of the voltage conversion circuit, wherein: The first resistor is used to couple the charging control signal to the first input terminal; The first switch tube is used to control the on-off of the first input terminal and the first output terminal according to the potential difference between the level of the charging control signal received by the first input terminal and the level of the first control terminal, and output the first driving signal of the corresponding level along the first output terminal.

4. The lithium-ion battery pack protection circuit according to claim 3, characterized in that: The voltage clamping circuit includes a first voltage regulator tube and a third resistor, wherein the anode of the first voltage regulator tube is electrically connected to the first output end, the cathode of the first voltage regulator tube is electrically connected to the first end of the third resistor and the output end of the voltage clamping circuit respectively, and the second end of the third resistor is connected to the ground, wherein: The first voltage regulator is used to stabilize the level of the first driving signal to generate the first control signal; The charging switch is used to control the on / off of its input end and output end according to the level of the first control signal received by its controlled end; The third resistor is used to pull down the level of the control end of the charging switch to a preset low level when the input end and the output end of the charging switch are disconnected.

5. The lithium-ion battery pack protection circuit according to claim 2, characterized in that: The charging switch includes two second switching tubes connected in parallel, and the second switching tube includes a second control end, a second input end and a second output end. The second control end is connected to the controlled end of the charging switch, the second input end is connected to the input end of the charging switch, and the second output end is connected to the output end of the charging switch.

6. The lithium-ion battery pack protection circuit according to claim 1, characterized in that: The discharge control unit includes a second drive circuit and a discharge switch, the second drive circuit includes a fourth resistor, a fifth resistor and a second voltage regulator tube, the first end of the fourth resistor is connected to the controlled end of the discharge control unit, the second end of the fourth resistor is electrically connected to the first end of the fifth resistor and the cathode of the second voltage regulator tube respectively, the second end of the fifth resistor is electrically connected to the anode of the second voltage regulator tube and connected to the controlled end of the discharge switch, the input end of the discharge switch is connected to the input end of the discharge control unit, and the output end of the discharge switch is connected to the output end of the discharge control unit, wherein, The fourth resistor is used to couple the discharge control signal output by the control unit to the voltage stabilizing circuit composed of the fifth resistor and the second voltage stabilizing tube; The voltage stabilizing circuit is used to stabilize the discharge control signal into a second control signal; The discharge switch is used to control the on and off of its input end and output end according to the level of the second control signal received by its controlled end; When the input end of the discharge switch is connected to the output end, the discharge control unit controls the cathode and the discharge negative port to be connected, and when the input end of the discharge switch is disconnected from the output end, the discharge control unit controls the cathode and the discharge negative port to be disconnected.

7. The lithium-ion battery pack protection circuit according to claim 6, characterized in that: The discharge switch includes two third switch tubes connected in parallel, and the third switch tube includes a third control end, a third input end and a third output end. The third control end is connected to the controlled end of the discharge switch, the third input end is connected to the input end of the discharge switch, and the third output end is connected to the output end of the discharge switch.

8. The lithium-ion battery pack protection circuit according to claim 1, characterized in that: The buck module includes an EG1163 buck control chip, a synchronous rectification buck conversion circuit, an output filter circuit, a feedback circuit and an overcurrent temperature protection circuit. The power port of the EG1163 buck control chip is electrically connected to the positive electrode of the adaptive power supply. The output control high end and the output control low end of the EG1163 buck control chip are electrically connected to the first drive controlled end and the second drive controlled end of the synchronous rectification buck conversion circuit, respectively. The power output end of the synchronous rectification buck conversion circuit is electrically connected to the input end of the output filter circuit and the input end of the feedback circuit. The output end of the output filter circuit is connected to the positive output end of the buck module. The feedback end of the feedback circuit is electrically connected to the feedback port of the EG1163 buck chip. The overcurrent temperature protection circuit includes an EG358 operational amplifier chip. The EG358 operational amplifier chip includes a first same-direction input end, a first reverse input end, a first operational amplifier output end, a second same-direction input end, a second reverse input end and a second operational amplifier output end. The first same-direction input end is connected to a first reference voltage provided by a first voltage divider circuit. The first reverse input terminal is electrically connected to the negative output terminal of the buck module through a sixth resistor in series, the second non-inverting input terminal is connected to a second reference voltage provided by a second voltage divider circuit, the second reverse input terminal is electrically connected to an NTC temperature detection sensor installed in the synchronous rectification buck conversion circuit, and the first op amp output terminal and the second op amp output terminal are both coupled and electrically connected to the voltage loop op amp output port of the EG1163 buck chip, wherein, The EG1163 buck control chip, after being driven and started, controls the synchronous rectification buck conversion circuit to buck the preset voltage to the first charging voltage; The output filter circuit is used to filter the first charging voltage to generate the first target voltage; The feedback circuit is used to input the collected feedback voltage reflecting the change of the first charging voltage into the feedback port of the EG1163 buck chip, so that the EG1163 buck control chip controls the synchronous rectification buck conversion circuit to output the stable first charging voltage; The EG358 operational amplifier chip is used to output an overcurrent control signal along the first operational amplifier output port according to a comparison result between the voltage received by the first reverse input terminal and the first reference voltage, and to output a temperature protection control signal along the second operational amplifier output port according to a comparison result between the voltage received by the second reverse input terminal and the second reference voltage; When the level of the overcurrent control signal or the temperature protection control signal received by the output port of the voltage loop op amp is the target level, the EG1163 buck control chip is enabled and turned off, and the buck module stops outputting the first target voltage.

9. The lithium-ion battery pack protection circuit according to claim 8, characterized in that: The output filter circuit includes a plurality of filter capacitors connected in parallel and two voltage-stabilizing diodes connected in parallel, the positive electrodes of the plurality of filter capacitors are electrically connected to the input end of the output filter circuit and the anodes of the two voltage-stabilizing diodes, and the cathodes of the two voltage-stabilizing diodes are connected to the output end of the output filter circuit; The feedback circuit comprises a sixth resistor, a seventh resistor and an eighth resistor connected in series, a first end of the sixth resistor is connected to an input end of the feedback circuit, a second end of the sixth resistor is electrically connected to a first end of the seventh resistor, a second end of the seventh resistor is electrically connected to an output end of the feedback circuit and a first end of the eighth resistor, and a second end of the eighth resistor is connected to ground; The synchronous rectification step-down conversion circuit includes a high-end MOS tube, a synchronous rectification MOS tube, a third driving circuit and an output inductor. The control end of the high-end MOS tube is connected to the first driving controlled end through the third driving circuit. The input end of the high-end MOS tube is electrically connected to the positive electrode of the adaptive power supply. The output end of the high-end MOS tube is electrically connected to the output inductor and the input end of the synchronous rectification MOS tube respectively. The control end of the synchronous rectification MOS tube is connected to the second driving controlled end through the third driving circuit. The output end of the synchronous rectification MOS tube is connected to the ground. The other end of the output inductor is connected to the power output end of the synchronous rectification step-down conversion circuit. The third driving circuit includes a current limiting resistor, a clamping resistor and a clamping diode, wherein the clamping resistor is connected in series with the clamping diode and then connected in parallel with the current limiting resistor, an electrical connection point between the current limiting resistor and the clamping resistor is electrically connected to the first driving controlled end or the second driving controlled end, and an electrical connection point between the current limiting resistor and the clamping diode is electrically connected to the control end of the high-end MOS tube or the control end of the synchronous rectification MOS tube; The high-end MOS tube is used to control the on-off of the input end and the output end of the high-end MOS tube according to the level of the first rectification control signal received by the control end thereof; The synchronous rectifier MOS tube is used to control the on-off of the input end and the output end of the synchronous rectifier MOS tube according to the level of the first rectification control signal received by the control end thereof; The EG1163 step-down control chip is used to control the interlocking on and off of the high-end MOS tube and the synchronous rectification MOS tube, so that the output inductor converts the preset voltage into the first charging voltage.

10. The lithium-ion battery pack protection circuit according to any one of claims 1 to 9, characterized in that: The control unit includes a battery protection chip of model CW1244AFAS.

Images