CN211606124U

CN211606124U - Balanced charge-discharge protection circuit of lithium battery pack

Info

Publication number: CN211606124U
Application number: CN201820544164.4U
Authority: CN
Inventors: 杜涛; 黄斌; 范钧
Original assignee: Chengdu Technological University CDTU
Current assignee: Chengdu Technological University CDTU; Chengdu Univeristy of Technology
Priority date: 2018-04-17
Filing date: 2018-04-17
Publication date: 2020-09-29
Anticipated expiration: 2028-04-17

Abstract

The utility model discloses a lithium battery pack balanced charging and discharging protection circuit, which comprises a control circuit, a main circuit and N shunting discharging branches, wherein each shunting discharging branch comprises a switch and a resistor which are connected in series in sequence; the main circuit comprises N lithium batteries, an MOS (metal oxide semiconductor) tube charging control switch and an MOS tube discharging control switch which are sequentially connected in series, the anode of the first lithium battery is anode BAT +, the cathode of the Nth lithium battery is connected with the source electrode of the MOS tube discharging control switch, the drain electrode of the MOS tube discharging control switch is connected with the drain electrode of the MOS tube charging control switch, the source electrode of the MOS tube charging control switch is cathode BAT-, and a shunt discharging branch is connected with the two ends of each lithium battery in parallel. The utility model discloses an above-mentioned circuit, the protection of charging overvoltage, discharge undervoltage, overcurrent, short circuit can be realized to each section lithium cell homoenergetic, and has realized the problem of whole group battery equalizing charge in the charging process.

Description

Balanced charge-discharge protection circuit of lithium battery pack

Technical Field

The utility model relates to a protection circuit field, concretely relates to balanced charge-discharge protection circuit of lithium cell group.

Background

The current lithium batteries are increasingly popularized, phenomena such as overcharge and overdischarge are occasionally caused in the charging and discharging process, each battery cannot be charged and discharged in a balanced manner, even combustion and explosion are caused by overheating short circuit, and in order to use safety and improve the service efficiency of the batteries, the need of an effective device for preventing overcharge and overdischarge and balancing energy is very necessary for researching series connection of grouped lithium batteries.

When the grouped lithium batteries are charged in series, the balance charging of each battery is ensured, otherwise, the performance and the service life of the whole group of batteries are influenced in the using process. Common equalizing charge technologies include constant shunt resistance equalizing charge, on-off shunt resistance equalizing charge, average battery voltage equalizing charge, switch capacitor equalizing charge, buck converter equalizing charge, inductance equalizing charge, and the like. The existing single lithium battery protection chip does not have the equalizing charge control function; the equalizing charge control function of the multiple lithium battery protection chips needs to be externally connected with a Central Processing Unit (CPU) and is realized through serial communication (such as an I2C bus) with the protection chips, so that the complexity and the design difficulty of the protection circuit are increased, the efficiency and the reliability of a system are reduced, and the power consumption of the management battery is increased.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that realize the equalizing charge of whole group battery, aim at providing an equalizing charge and discharge protection circuit of lithium cell group, each section lithium cell homoenergetic realizes the protection of charging overvoltage, discharge under-voltage, overcurrent, short circuit, and has realized the equalizing charge's of whole group battery problem in the charging process.

The utility model discloses a following technical scheme realizes:

a lithium battery pack balanced charging and discharging protection circuit comprises a control circuit, a main circuit and N shunt discharging branches, wherein each shunt discharging branch comprises a switch and a resistor which are sequentially connected in series; the main circuit comprises N lithium batteries, an MOS (metal oxide semiconductor) tube charging control switch and an MOS tube discharging control switch which are sequentially connected in series, wherein the anode of the first lithium battery is an anode BAT +, the cathode of the Nth lithium battery is connected with the source electrode of the MOS tube discharging control switch, the drain electrode of the MOS tube discharging control switch is connected with the drain electrode of the MOS tube charging control switch, the source electrode of the MOS tube charging control switch is a cathode BAT-, and two ends of each lithium battery are connected with a shunt discharging branch in parallel; the control circuit comprises N single lithium battery protection chips, an OR gate, an AND gate and N overcurrent detection protection resistors, wherein the single lithium battery protection chips are connected with the single lithium batteries in a one-to-one manner, a VDD port of each lithium battery protection chip is connected with the anode of the corresponding lithium battery, a VSS port of each lithium battery protection chip is connected with the cathode of the corresponding lithium battery, a VM port of each lithium battery protection chip is correspondingly connected with one end of one overcurrent detection protection resistor, the other end of each overcurrent detection protection resistor is connected with the cathode of the corresponding single lithium battery of the single lithium battery protection chip, CO ports of the N single lithium battery protection chips are connected with the same end of the OR gate, the other end of the OR gate is connected with the grid of the MOS tube charging control switch, DO ports of the N single lithium battery protection chips are connected with the same end of the AND gate, and the other end of the AND gate is connected with the grid, and the CO port of each single lithium battery protection chip is also simultaneously connected with the movable end of the switch on the corresponding shunt discharge branch circuit.

The protection of charge overvoltage, discharge undervoltage, overcurrent, short circuit can all be realized to each section lithium cell in this scheme, adopt single section lithium cell protection chip to protect the group lithium cell of arbitrary series connection number, wholly constitute the group battery protection circuit who has the balanced function of charging, utilize the break-make of lithium cell protection chip control reposition of redundant personnel branch road switch device to realize the problem that whole group battery balanced charge, this protection circuit protect function is perfect, job stabilization, the sexual valence relative altitude, the balanced charging error is little, below 50 mV. The design scheme is different from the traditional method for realizing equalizing charge at the charger end, and reduces the cost of design and application of the lithium battery pack charger, thereby improving the cost performance of the protection circuit.

Preferably, the source of the MOS transistor charge control switch is connected to the anode of the diode D1, the drain of the MOS transistor charge control switch is connected to the cathode of the diode D1, the source of the MOS transistor discharge control switch is connected to the anode of the diode D2, and the drain of the MOS transistor discharge control switch is connected to the cathode of the diode D2.

Preferably, the value of N is a positive integer of 2 or more.

A lithium battery pack balanced charge-discharge protection circuit comprises a lithium battery protection chip U1-U4, a NAND gate U5, an MOS transistor T1-T4, a photoelectric coupler U9-U12, a photoelectric coupler U15-U18 and a triode U21-U24, wherein the OD end of the lithium battery protection chip U1-U4 is sequentially connected with one end of a resistor R17, one end of a resistor R19, one end of a resistor R21 and one end of a resistor R23, the other end of the resistor R17, the other end of a resistor R19, the other end of a resistor R21 and the other end of a resistor R23 are sequentially connected with a port 1 of a photoelectric coupler U9, a port 1 of a photoelectric coupler U10, a port 1 of a photoelectric coupler U11 and a port 1 of a photoelectric coupler U12; the OC end of the lithium battery protection chip U1-U4 is sequentially connected with one end of a resistor R18, one end of a resistor R20, one end of a resistor R22 and one end of a resistor R24, and the other end of a resistor R18, the other end of a resistor R20, the other end of the resistor R22 and the other end of a resistor R24 are sequentially connected with a port 1 of a photoelectric coupler U15, a port 1 of a photoelectric coupler U16, a port 1 of a photoelectric coupler U17 and a port 1 of a photoelectric coupler U18; a resistor R9 is connected between the CS end and the GND end of the lithium battery protection chip U1 in series, the VCC end of the lithium battery protection chip U1 is also connected with one end of a resistor R3 and one end of a capacitor C3 at the same time, the other end of the resistor R3 is connected with an R + end, and the other end of the capacitor C3 is connected with the GND end of the lithium battery protection chip U1, the port 2 of a photoelectric coupler U9 and the port 2 of a photoelectric coupler U15 at the same time; a resistor R10 is connected in series between the CS end and the GND end of the lithium battery protection chip U2, the VCC end of the lithium battery protection chip U2 is also connected with one end of a resistor R4 and one end of a capacitor C4 at the same time, the other end of the resistor R4 is connected with a port 2 of a photoelectric coupler U9 and a port 2 of a photoelectric coupler U15 at the same time, and the other end of the capacitor C4 is connected with the GND end of the lithium battery protection chip U2, the port 2 of the photoelectric coupler U10 and the port 2 of the photoelectric coupler U16 at the same time; a resistor R11 is connected in series between the CS end and the GND end of the lithium battery protection chip U3, the VCC end of the lithium battery protection chip U3 is also connected with one end of a resistor R5 and one end of a capacitor C5 at the same time, the other end of the resistor R5 is connected with a port 2 of a photoelectric coupler U10 and a port 2 of a photoelectric coupler U16 at the same time, and the other end of the capacitor C5 is connected with the GND end of the lithium battery protection chip U3, the port 2 of the photoelectric coupler U11 and the port 2 of the photoelectric coupler U17 at the same time; a resistor R12 is connected in series between the CS end and the GND end of the lithium battery protection chip U4, the VCC end of the lithium battery protection chip U4 is also connected with one end of a resistor R6 and one end of a capacitor C6 at the same time, the other end of the resistor R6 is connected with the port 2 of a photoelectric coupler U11 and the port 2 of a photoelectric coupler U17 at the same time, the other end of the capacitor C6 is connected with the GND end of the lithium battery protection chip U4, the common connecting end of the resistor R26 and the capacitor C7 at the same time, the other end of the resistor R26 is also connected with the port 12 of a NAND gate U5, and the other end of the capacitor C7 is connected with the port 4 of the photoelectric; the port 1 of the NAND gate U5 is connected with the port 11, the port 10 of the NAND gate U5 is connected with the port 13, a resistor R28 is connected in series between the ports 7 and 8 of the NAND gate U5, the ports 5, 6 and 7 of the NAND gate U5 are connected, the ports 8 and 9 of the NAND gate U5 are connected, the port 8 of the NAND gate U5 is also connected with one end of a resistor R29, the other end of the resistor R29 is simultaneously connected with the drains of MOS transistors T1 and T2, the port 3 of the NAND gate U5 is also connected with one end of a resistor R27, the other end of the resistor R27 is simultaneously connected with the gates of MOS transistors T1 and T2, the port 14 of the NAND gate U5 is also connected with one end of a resistor R25, the other end of the resistor R25 is simultaneously connected with ports 2 of a photoelectric coupler U9 and a U15, a resistor R30 and a resistor R31 are connected in series, the hanging end of the resistor R30 is connected with the port 3 of the photoelectric coupler U18, the hanging end of the resistor R31 is simultaneously connected with the sources of MOS transistors T3 and T4, and the common connecting end of the resistor R30 and the resistor R31 is simultaneously connected with the gates of the MOS transistors T3 and T4; the drains of the MOS tubes T1-T4 are all connected, and the sources of the MOS tubes T1-T2 are simultaneously connected with the port 5 of the NAND gate, the GND of the lithium battery protection chip U4, the port 2 of the photoelectric coupler U18 and the port 2 of the photoelectric coupler U12; a port 4 of the photoelectric coupler U9 is connected with a port 4 of a photoelectric coupler U15, a port 3 of the photoelectric coupler U9 is connected with a port 4 of a photoelectric coupler U10, a port 3 of the photoelectric coupler U15 is connected with a port 4 of a photoelectric coupler U16, a port 3 of a photoelectric coupler U10 is connected with a port 4 of a photoelectric coupler U11, a port 3 of the photoelectric coupler U16 is connected with a port 4 of a photoelectric coupler U17, a port 3 of the photoelectric coupler U11 is connected with a port 4 of a photoelectric coupler U12, and a port 3 of the photoelectric coupler U17 is connected with a port 4 of a photoelectric coupler U18; a resistor R1 and a resistor RA3 are sequentially connected in series between an emitting electrode and a collector electrode of the triode U21, and a resistor R2 and a resistor R7 are sequentially connected in series between the emitting electrode and a base electrode of the triode U21; a resistor RA4 is connected in series between the base of the triode U21 and the collector of the triode U22, a resistor R8 is connected in series between the base of the triode U21 and the emitter of the triode U22, and resistors R13 and R14 are sequentially connected in series between the emitter and the base of the triode U22; a resistor RA5 is connected in series between the base of the triode U22 and the collector of the triode U23, a resistor R15 is connected in series between the base of the triode U22 and the emitter of the triode U23, and resistors R16 and R35 are sequentially connected in series between the emitter and the base of the triode U23; a resistor RA6 is connected in series between the base of the triode U23 and the collector of the triode U24, a resistor R32 is connected in series between the base of the triode U23 and the emitter of the triode U24, resistors R33 and R34 are connected in series between the emitter and the base of the triode U24 in sequence, the base of the triode U24 is further connected with a port 2 of a photocoupler U12, a common connection end of R1 and RA3, a common connection end of the base of U21 and RA4, a common connection end of the base of U22 and RA5, and a common connection end of the base of U23 and RA6 are connected with a port 4, a port 3, a port 2 and a port 1 of the interface P1 in sequence.

Preferably, diodes Q1, Q3, Q4 and Q2 are connected in series between the drain and the source of the MOS transistor T1-T4 in sequence, and the anodes of the diodes Q1, Q3, Q4 and Q2 are all connected with the source of the MOS transistor.

Compared with the prior art, the utility model, following advantage and beneficial effect have: the lithium battery protection circuit has the advantages that the lithium battery protection chip is adopted to protect groups of lithium batteries with any serial number, the battery pack protection circuit with the equalizing charge function is integrally formed, the lithium battery protection chip is used for controlling the on-off of a shunt discharge branch switch device to realize the equalizing charge of the whole group of batteries, the protection function of the protection circuit is perfect, the work is stable, the cost performance is high, the equalizing charge error is small, and the voltage drop of the battery pack protection circuit is below 50 mV. The design scheme is different from the traditional method for realizing equalizing charge at the charger end, and reduces the cost of design and application of the lithium battery pack charger, thereby improving the cost performance of the protection circuit.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

fig. 1 is a circuit diagram of the present invention;

FIG. 2 is a circuit diagram of a charging process of the circuit of FIG. 1;

FIG. 3 is a circuit diagram of a shunt equalization process of the circuit of FIG. 1;

FIG. 4 is a circuit diagram of a discharge process of the circuit of FIG. 1;

fig. 5 is a circuit diagram of a part of a specific 12V lithium battery pack protection circuit with equalizing charge capability based on the principle of fig. 1;

fig. 6 is another partial circuit diagram of a specific 12V lithium battery pack protection circuit with equalizing charge capability based on the principle of fig. 1, and fig. 5 and 6 form a complete circuit diagram.

Reference numbers and corresponding part names in the drawings:

1. a lithium battery; 2. a resistance; 3. a switch; 4. an overcurrent detection protection resistor; 5. the omitted lithium battery protection chip and circuit connection part; 6. a single lithium battery protection chip; 7. an OR gate; 8. an AND gate; 9. a charge control switching device; 10. a discharge control switching device; 11. a control circuit; 12. a main circuit; 13. and shunting the discharging branch.

Detailed Description

To make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the following examples and drawings, and the exemplary embodiments and descriptions thereof of the present invention are only used for explaining the present invention, and are not intended as limitations of the present invention.

Example 1:

as shown in fig. 1-6, the present invention includes a lithium battery pack equalizing charge-discharge protection circuit, which includes a control circuit 11, a main circuit 12 and N shunt discharge branches 13, wherein each shunt discharge branch 13 includes a switch 3 and a resistor 2 connected in series in sequence; the main circuit 12 comprises N lithium batteries 1, an MOS (metal oxide semiconductor) tube charging control switch 9 and an MOS tube discharging control switch 10 which are sequentially connected in series, wherein the anode of the first lithium battery is an anode BAT +, the cathode of the Nth lithium battery is connected with the source electrode of the MOS tube discharging control switch 10, the drain electrode of the MOS tube discharging control switch 10 is connected with the drain electrode of the MOS tube charging control switch 9, the source electrode of the MOS tube charging control switch 9 is a cathode BAT-, and two ends of each lithium battery 1 are connected with a shunt discharging branch in parallel; the control circuit 11 comprises N single lithium battery protection chips 6, an OR gate 7, an AND gate 8 and N over-current detection protection resistors 4, the single lithium battery protection chips 6 are connected with the single lithium batteries 1 one by one, a VDD port of each lithium battery protection chip 6 is connected with the anode of the corresponding lithium battery 1, a VSS port of each lithium battery protection chip 6 is connected with the cathode of the corresponding lithium battery 1, a VM port of each lithium battery protection chip 6 is correspondingly connected with one end of one over-current detection protection resistor 4, the other end of the over-current detection protection resistor 4 is connected with the cathode of the single lithium battery 1 corresponding to the single lithium battery protection chip 6, CO ports of the N single lithium battery protection chips 6 are all connected with the same end of the OR gate 7, the other end of the OR gate 7 is connected with a grid electrode of an MOS tube charging control switch 9, DO ports of the N single lithium battery protection chips 6 are all connected with the same end of the AND gate 8, the other end of the AND gate 8 is connected with the grid of the MOS tube discharge control switch 10, and the CO port of each single lithium battery protection chip 6 is also simultaneously connected with the movable end of the switch on the corresponding shunt discharge branch 13. In fig. 1, CO in each single lithium battery is a charging control pin, DO is a discharging control pin, VM is a discharging overcurrent and short circuit detection pin VM, VDD is a battery positive terminal VDD, VSS is a battery negative terminal, 5 is an omitted lithium battery protection chip and circuit connection part, or gate 7 is a charging overvoltage protection signal, which is isolated by an optical coupler and forms a parallel connection to drive a charging control MOS transistor gate in the main circuit, and gate 8 is a discharging undervoltage overcurrent and short circuit protection signal, which is isolated by an optical coupler and forms a series connection to drive a discharging control MOS gate in the main circuit, resistor 2 is a charging overvoltage shunt discharging branch resistor, and switch 3 is a shunt discharging branch control switch device.

The source of the MOS transistor charging control switch 9 is connected to the anode of the diode D1, the drain of the MOS transistor charging control switch 9 is connected to the cathode of the diode D1, the source of the MOS transistor discharging control switch 10 is connected to the anode of the diode D2, and the drain of the MOS transistor discharging control switch 10 is connected to the cathode of the diode D2.

The value of N is a positive integer greater than or equal to 2.

When the lithium battery pack is charged, the positive electrode and the negative electrode of the external power supply are respectively connected with the positive electrode BAT + and the negative electrode BAT-of the battery pack, the charging current flows through the positive electrode BAT + of the battery pack, 1-N of single lithium batteries in the battery pack, the discharge control switch, the charging control switch and the negative electrode BAT-of the battery pack, and the current flows to the direction shown in figure 2.

Charging overvoltage protection control signals of a single lithium battery protection chip on the control circuit are output in parallel after being isolated by an optical coupler, and grid voltage is provided for the conduction of a charging switch device 9 in a main circuit; if one or more lithium batteries are in an overvoltage protection state in the charging process, the overvoltage protection signal controls the shunt discharging branch circuits connected in parallel at the two ends of the anode and the cathode of a single lithium battery to discharge 13, and meanwhile, the corresponding single lithium batteries connected in series in the charging loop are isolated from the charging loop.

When the lithium battery pack is charged in series, the influence of the capacity difference of the single battery is ignored, and the battery with smaller internal resistance is fully charged firstly. At this time, the corresponding overvoltage protection signal controls the switch device of the shunt discharge branch to be closed, and a shunt resistor 2 is connected in parallel at two ends of the primary battery. According to the PNGV (the partial for a New Generation of batteries) equivalent circuit model of the battery, the shunt branch resistance is equivalent to the load of the single lithium battery which is fully charged first, and the battery discharges through the shunt branch resistance, so that the terminal voltage of the battery is maintained in a very small range near the fully charged state. Assuming that the 1 st lithium battery is charged first and enters an overvoltage protection state, the current flow in the main circuit and the shunt discharge branch is as shown in fig. 3. When all the single batteries are charged and enter an overvoltage protection state, the voltages of all the single batteries are equal in an error range, the charging protection control signals of all the protection chips become low, and the charging protection control signals cannot provide grid bias voltage for the charging control switching device in the main circuit to turn off the charging control switching device, so that the main circuit is disconnected, namely, the equalizing charging is realized, and the charging process is completed.

When the battery pack discharges, an external load is respectively connected with two ends of the anode and the cathode of the battery pack BAT + and BAT-, and discharging current flows through the anode of the battery pack BAT-, the charging control switch device, the discharging control switch device, the single lithium battery N-1 in the battery pack and the anode of the battery pack BAT +, and the current flows to the direction shown in figure 4. In the system, control signals of discharging under-voltage protection, overcurrent and short-circuit protection of a single lithium battery protection chip of a control circuit part are output in series after being isolated by an optical coupler, and grid voltage is provided for conduction of a discharging switch device in a main circuit; once the battery pack meets special conditions such as undervoltage or overcurrent and short circuit of a single lithium battery in the discharging process, the discharging protection control signal of the corresponding single lithium battery becomes low, and the discharging protection control signal cannot provide grid bias voltage for a discharging control switch device in a main circuit to turn off the discharging control switch device, so that the main circuit is disconnected, and the discharging use process is ended.

The common lithium battery adopts constant-current and constant-voltage charging control. During constant voltage charging, the charging current is reduced by an approximate exponential law. The switch device of the main charge-discharge loop in the system can be selected according to the maximum working current and the working voltage which are met by the requirements of an external circuit. The single lithium battery protection chip of the control circuit can be selected according to the voltage grade, the protection delay time and the like of the single lithium battery to be protected. The discharging branch resistances connected in parallel at two ends of the single battery can be calculated according to the charging voltage of the lithium battery charger and the parameters and discharging current of the lithium battery. The balance current should be reasonably selected, and if the balance current is too small, the balance effect is not obvious; if the current is too large, the energy loss of the system is large, the balancing efficiency is low, the requirement on the thermal management of the lithium battery pack is high, and the general current can be designed to be between 50 and 100 mA. The shunt discharge branch resistance can be realized by adopting a power resistor or a resistor network. The shunt discharge branch resistor is generally realized by adopting a resistor network, so that the influence of resistor deviation can be effectively eliminated, and the effect of reducing heat power consumption can be achieved.

Example 2:

Diodes Q1, Q3, Q4 and Q2 are connected in series between the drain and the source of the MOS transistor T1-T4 in sequence, and the anodes of the diodes Q1, Q3, Q4 and Q2 are all connected with the source of the MOS transistor.

Fig. 5 and fig. 6 are combined to form a complete 12V lithium battery pack protection circuit with charge equalization capability, this embodiment is a specific implementation circuit scheme designed based on the design idea of embodiment 1, and the same network numbers in fig. 5 and fig. 6 represent the same signals, which represent that they are connected. The model of the lithium battery protection chip U1-U4 is FS361A, the model of the NAND gate U5 is HEF4011, the model of the photoelectric coupler is PC317, the model of the triode is AZ431, the model of the diode is IRFB3607, the resistance values of R3-R6 are 510 ohms, the resistance values of R9-R12 are 102 ohms, the resistance values of R17-R24 are 103 ohms, the resistance values of R26 and R27 are 105 ohms, the resistance values of R30 and R31 are 105 ohms, the resistance value of R25 is 510 ohms, the resistance values of C3-C7 are 0.1U, the resistance values of RA3-RA5 are 510 ohms, the resistance values of R1, R3, R15 and R32 are all European 473, and the resistance values of R2, R13, R16 and R33 are 102 ohms.

The result of all the outputs 'or' of the OC in the scheme is used for controlling the charging control of the MOS transistor, and is respectively U15_1, U16_1, U17_1 and U18_1, see U15_1, U16_1, U17_1 and U18_1, so long as the voltages are higher than the corresponding voltages of B2, B3 and B4, and B-voltage can conduct the optical coupler, and further, the R25_1 and R30_2 are conducted. Referring to fig. 5, R30_2 is connected to R31_2 through a resistor R30, and referring to fig. 6, R31_2 controls the charging MOS transistor. R25_1 is connected with 14 pins VDD of the NAND gate HEF4011 and is always in a high level state.

The result of all OD outputs 'and' in this scheme is used for controlling the discharge control of the MOS transistor, and the OD outputs are respectively U9_1, U10_1, U11_1 and U12_1, see U9_1, U10_1, U11_1 and U12_1 in fig. 5, so long as the voltage is higher than the corresponding voltages B2, B3, B4 and B-to turn on the optocoupler, thereby turning on R25_1 and U12_ 3. Referring to FIG. 5, U12_3 is connected to B-through resistor R26 and is low. U12_3 connects the 12 th leg of HEF4011, the 13 th leg of HEF4011 connects U5_13, and U5_13 refers to FIG. 6, which connects with U5 th leg 10. Referring to the data handbook of HEF4011, leg 10 of U5 is the nand gate output of leg 8 of U5 and leg 9 of U5. Referring to the U5 connection of FIG. 6, its pins 8 and 9 are connected with B- (low) through R28, so that

pins

10 and 13 of U5, U5_13, are always high. Since the pin U12_3 of the HEF4011 is low, the pin U5_1 of the HEF4011 is low, and the pin R27_1 of the nand gate loop of

pins

1, 2, and 3 of the HEF4011 is high. Referring to fig. 6, the output pin of R27_1 controls the discharge MOS transistor.

Each lithium battery can realize the protection of charging overvoltage, discharging undervoltage, overcurrent and short circuit, and the problem of equalizing charge of the whole battery set is realized in the charging process. In the design, a single lithium battery protection chip is adopted to protect the grouped lithium batteries with any serial number, so that the battery pack protection circuit with the equalizing charge function is integrally formed, the protection function of the protection circuit is perfect, the work is stable, the cost performance is high, and the equalizing charge error is small and is below 50 mV.

The above-mentioned embodiments, further detailed description of the objects, technical solutions and advantages of the present invention, it should be understood that the above description is only the embodiments of the present invention, and is not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. The lithium battery pack balanced charge-discharge protection circuit is characterized by comprising a control circuit (11), a main circuit (12) and N shunt discharge branches (13), wherein each shunt discharge branch (13) comprises a switch (3) and a resistor (2) which are sequentially connected in series; the main circuit (12) comprises N lithium batteries (1), an MOS (metal oxide semiconductor) tube charging control switch (9) and an MOS tube discharging control switch (10) which are sequentially connected in series, wherein the anode of the first lithium battery is an anode BAT +, the cathode of the Nth lithium battery is connected with the source electrode of the MOS tube discharging control switch (10), the drain electrode of the MOS tube discharging control switch (10) is connected with the drain electrode of the MOS tube charging control switch (9), the source electrode of the MOS tube charging control switch (9) is a cathode BAT-, and two ends of each lithium battery (1) are connected with a shunt discharging branch in parallel; the control circuit (11) comprises N single lithium battery protection chips (6), an OR gate (7), an AND gate (8) and N overcurrent detection protection resistors (4), wherein the single lithium battery protection chips (6) are connected with the single lithium batteries (1) one by one, a VDD port of each lithium battery protection chip (6) is connected with the anode of the corresponding lithium battery (1), a VSS port of each lithium battery protection chip (6) is connected with the cathode of the corresponding lithium battery (1), a VM port of each lithium battery protection chip (6) is correspondingly connected with one end of one overcurrent detection protection resistor (4), the other end of the overcurrent detection protection resistor (4) is connected with the cathode of the single lithium battery (1) corresponding to the single lithium battery protection chip (6), CO ports of the N single lithium battery protection chips (6) are connected with the same end of the OR gate (7), or the other end of the MOS gate (7) is connected with the grid of the MOS charging control switch (9), the DO ports of the N single lithium battery protection chips (6) are connected with the same end of the AND gate (8), the other end of the AND gate (8) is connected with the grid electrode of the MOS tube discharge control switch (10), and the CO port of each single lithium battery protection chip (6) is also connected with the movable end of the switch on the corresponding shunt discharge branch (13) at the same time.

2. The lithium battery pack balanced charging and discharging protection circuit of claim 1, wherein a source of the MOS transistor charging control switch (9) is connected to an anode of the diode D1, a drain of the MOS transistor charging control switch (9) is connected to a cathode of the diode D1, a source of the MOS transistor discharging control switch (10) is connected to an anode of the diode D2, and a drain of the MOS transistor discharging control switch (10) is connected to a cathode of the diode D2.

3. The lithium battery pack balanced charge and discharge protection circuit according to claim 1 or 2, wherein a value of N is a positive integer greater than or equal to 2.

4. A lithium battery pack balanced charge-discharge protection circuit is characterized by comprising a lithium battery protection chip U1-U4, a NAND gate U5, an MOS transistor T1-T4, a photoelectric coupler U9-U12, a photoelectric coupler U15-U18 and a triode U21-U24, wherein the OD end of the lithium battery protection chip U1-U4 is sequentially connected with one end of a resistor R17, one end of a resistor R19, one end of a resistor R21 and one end of a resistor R23, the other end of the resistor R17, the other end of a resistor R19, the other end of a resistor R21 and the other end of a resistor R23 are sequentially connected with a port 1 of a U9, a port 1 of a photoelectric coupler U10, a port 1 of a photoelectric coupler U11 and a port 1 of a photoelectric coupler U12; the OC end of the lithium battery protection chip U1-U4 is sequentially connected with one end of a resistor R18, one end of a resistor R20, one end of a resistor R22 and one end of a resistor R24, and the other end of a resistor R18, the other end of a resistor R20, the other end of the resistor R22 and the other end of a resistor R24 are sequentially connected with a port 1 of a photoelectric coupler U15, a port 1 of a photoelectric coupler U16, a port 1 of a photoelectric coupler U17 and a port 1 of a photoelectric coupler U18; a resistor R9 is connected between the CS end and the GND end of the lithium battery protection chip U1 in series, the VCC end of the lithium battery protection chip U1 is also connected with one end of a resistor R3 and one end of a capacitor C3 at the same time, the other end of the resistor R3 is connected with an R + end, and the other end of the capacitor C3 is connected with the GND end of the lithium battery protection chip U1, the port 2 of a photoelectric coupler U9 and the port 2 of a photoelectric coupler U15 at the same time; a resistor R10 is connected in series between the CS end and the GND end of the lithium battery protection chip U2, the VCC end of the lithium battery protection chip U2 is also connected with one end of a resistor R4 and one end of a capacitor C4 at the same time, the other end of the resistor R4 is connected with a port 2 of a photoelectric coupler U9 and a port 2 of a photoelectric coupler U15 at the same time, and the other end of the capacitor C4 is connected with the GND end of the lithium battery protection chip U2, the port 2 of the photoelectric coupler U10 and the port 2 of the photoelectric coupler U16 at the same time; a resistor R11 is connected in series between the CS end and the GND end of the lithium battery protection chip U3, the VCC end of the lithium battery protection chip U3 is also connected with one end of a resistor R5 and one end of a capacitor C5 at the same time, the other end of the resistor R5 is connected with a port 2 of a photoelectric coupler U10 and a port 2 of a photoelectric coupler U16 at the same time, and the other end of the capacitor C5 is connected with the GND end of the lithium battery protection chip U3, the port 2 of the photoelectric coupler U11 and the port 2 of the photoelectric coupler U17 at the same time; a resistor R12 is connected in series between the CS end and the GND end of the lithium battery protection chip U4, the VCC end of the lithium battery protection chip U4 is also connected with one end of a resistor R6 and one end of a capacitor C6 at the same time, the other end of the resistor R6 is connected with the port 2 of a photoelectric coupler U11 and the port 2 of a photoelectric coupler U17 at the same time, the other end of the capacitor C6 is connected with the GND end of the lithium battery protection chip U4, the common connecting end of the resistor R26 and the capacitor C7 at the same time, the other end of the resistor R26 is also connected with the port 12 of a NAND gate U5, and the other end of the capacitor C7 is connected with the port 4 of the photoelectric; the port 1 of the NAND gate U5 is connected with the port 11, the port 10 of the NAND gate U5 is connected with the port 13, a resistor R28 is connected in series between the ports 7 and 8 of the NAND gate U5, the ports 5, 6 and 7 of the NAND gate U5 are connected, the ports 8 and 9 of the NAND gate U5 are connected, the port 8 of the NAND gate U5 is also connected with one end of a resistor R29, the other end of the resistor R29 is simultaneously connected with the drains of MOS transistors T1 and T2, the port 3 of the NAND gate U5 is also connected with one end of a resistor R27, the other end of the resistor R27 is simultaneously connected with the gates of MOS transistors T1 and T2, the port 14 of the NAND gate U5 is also connected with one end of a resistor R25, the other end of the resistor R25 is simultaneously connected with ports 2 of a photoelectric coupler U9 and a U15, a resistor R30 and a resistor R31 are connected in series, the hanging end of the resistor R30 is connected with the port 3 of the photoelectric coupler U18, the hanging end of the resistor R31 is simultaneously connected with the sources of MOS transistors T3 and T4, and the common connecting end of the resistor R30 and the resistor R31 is simultaneously connected with the gates of the MOS transistors T3 and T4; the drains of the MOS tubes T1-T4 are all connected, and the sources of the MOS tubes T1-T2 are simultaneously connected with the port 5 of the NAND gate, the GND of the lithium battery protection chip U4, the port 2 of the photoelectric coupler U18 and the port 2 of the photoelectric coupler U12; a port 4 of the photoelectric coupler U9 is connected with a port 4 of a photoelectric coupler U15, a port 3 of the photoelectric coupler U9 is connected with a port 4 of a photoelectric coupler U10, a port 3 of the photoelectric coupler U15 is connected with a port 4 of a photoelectric coupler U16, a port 3 of a photoelectric coupler U10 is connected with a port 4 of a photoelectric coupler U11, a port 3 of a photoelectric coupler U16 is connected with a port 4 of a photoelectric coupler U17, a port 3 of the photoelectric coupler U11 is connected with a port 4 of a photoelectric coupler U12, and a port 3 of the photoelectric coupler U17 is connected with a port 4 of a photoelectric coupler U18; a resistor R1 and a resistor RA3 are sequentially connected in series between an emitting electrode and a collector electrode of the triode U21, and a resistor R2 and a resistor R7 are sequentially connected in series between the emitting electrode and a base electrode of the triode U21; a resistor RA4 is connected in series between the base of the triode U21 and the collector of the triode U22, a resistor R8 is connected in series between the base of the triode U21 and the emitter of the triode U22, and resistors R13 and R14 are sequentially connected in series between the emitter and the base of the triode U22; a resistor RA5 is connected in series between the base of the triode U22 and the collector of the triode U23, a resistor R15 is connected in series between the base of the triode U22 and the emitter of the triode U23, and resistors R16 and R35 are sequentially connected in series between the emitter and the base of the triode U23; a resistor RA6 is connected in series between the base of the triode U23 and the collector of the triode U24, a resistor R32 is connected in series between the base of the triode U23 and the emitter of the triode U24, resistors R33 and R34 are connected in series between the emitter and the base of the triode U24 in sequence, the base of the triode U24 is further connected with a port 2 of a photocoupler U12, a common connection end of R1 and RA3, a common connection end of the base of U21 and RA4, a common connection end of the base of U22 and RA5, and a common connection end of the base of U23 and RA6 are connected with a port 4, a port 3, a port 2 and a port 1 of the interface P1 in sequence.

5. The lithium battery pack balanced charge and discharge protection circuit as claimed in claim 4, wherein diodes Q1, Q3, Q4 and Q2 are connected in series between the drain and source of the MOS transistor T1-T4 in sequence, and the anodes of the diodes Q1, Q3, Q4 and Q2 are all connected to the source of the MOS transistor.