Charging and discharging protection circuit of lithium battery
By introducing a charge/discharge detection unit and a switching unit into the lithium battery charge/discharge protection circuit, and using a differential amplifier and comparator to detect voltage, the problem of lithium battery damage under undervoltage conditions is solved, thus achieving battery protection and lifespan extension.
Patent Information
- Application Number
- CN202423313529.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2026-02-06
- Estimated Expiration
- 2034-12-31
AI Technical Summary
Existing lithium battery charging protection circuits cannot effectively protect batteries from damage when they are undervoltage, resulting in reduced battery capacity and performance, and shortened lifespan.
A lithium battery charge and discharge protection circuit was designed, including a charge and discharge detection unit and a switching unit. The voltage is detected by a differential amplifier and a comparator, and the opening and closing of the switching unit is controlled to prevent undervoltage charging.
It effectively protects the battery from damage under low voltage conditions, maintains battery capacity and performance, and extends battery life.
Smart Images
Figure CN223884968U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model discloses battery technical field especially relates to a kind of charge-discharge protection circuit of lithium battery. BACKGROUND
[0002] Lithium battery PACK leasing becomes the choice of more and more users, and the leasing company is responsible for the update and maintenance of lithium battery PACK and recycling work, which improves the utilization rate of energy and has a positive significance for resource recycling and environmental protection. The BMS module is usually provided in the lithium battery to detect the power of the battery pack, the input and output current of the battery; the BMS module is usually provided with an overvoltage protection circuit, when the charging voltage is too high, it will accelerate the speed of the chemical reaction inside the battery, causing the internal structure of the battery to be damaged, thereby reducing the service life of the battery; the overvoltage protection circuit is used to protect the charging voltage in the circuit from being too high. However, when the charging voltage is too low, the battery will also be in an under-voltage state, and under-voltage charging will reduce the capacity and performance of the battery, and also damage the internal structure of the battery, shortening the service life of the battery; the existing battery pack charging does not effectively protect the voltage that is too low, and the battery will be damaged if the time is too long. SUMMARY
[0003] The purpose of the application is to overcome the shortcomings of the prior art, and to provide a charge-discharge protection circuit for lithium battery, which protects the battery pack from being damaged during low-voltage charging by the circuit structure of the charge-discharge detection unit and the switching unit.
[0004] Technical scheme: To achieve the above purpose, the charge-discharge protection circuit for lithium battery of the utility model includes lithium battery BMS module, battery pack unit, switching unit, charge-discharge terminal, low-power supply unit and charge-discharge detection unit; the lithium battery BMS module detects various state data of the battery pack unit, and the lithium battery BMS module is bidirectionally connected with the switching unit; the power output end of the low-power supply unit is electrically connected with the power end of the lithium battery BMS module; the positive and negative terminals of the battery pack unit are respectively electrically connected with the positive and negative terminals of the charge-discharge terminal through the switching unit, the charge-discharge detection unit detects the voltage of the positive and negative terminals of the charge-discharge terminal, and the charge-discharge detection unit controls the switching unit to control the opening and closing of the switching unit.
[0005] Further, the switching unit includes a KM1 contactor switch; one end of the KM1 contactor switch is electrically connected with the positive terminal of the battery pack unit, and the other end of the KM1 contactor switch is electrically connected with the positive terminal of the charge-discharge terminal; the negative terminal of the battery pack unit is electrically connected with the negative terminal of the charge-discharge terminal.
[0006] Further, the switch unit further comprises a KM contactor coil, an OR gate and an M1 transistor switch; a positive electrode of a low-power supply unit power supply output end is electrically connected to a source electrode of the M1 transistor switch, one end of the KM contactor coil is electrically connected to a drain electrode of the M1 transistor switch, the other end of the KM contactor coil is electrically connected to a negative electrode of the low-power supply unit power supply output end, and a gate electrode of the M1 transistor switch is electrically connected to an output end of the OR gate.
[0007] Further, the charge and discharge detection circuit comprises a DA1 differential amplifier, a Comp comparator and a bandgap reference circuit; a positive input end and a negative input end of the DA1 differential amplifier are electrically connected to a positive electrode end and a negative electrode end of the charge and discharge end respectively, and an output end of the DA1 differential amplifier is electrically connected to a positive input end of the Comp comparator; a negative input end of the Comp comparator is electrically connected to an output end of the bandgap reference circuit, and an output end of the Comp comparator is electrically connected to one input end of the OR gate.
[0008] Further, a signal output end of the lithium battery BMS module is electrically connected to the other input end of the OR gate.
[0009] Further, a control output end of the lithium battery BMS module is electrically connected to the bandgap reference circuit to control a reference voltage output by the bandgap reference circuit; and the other control output end of the lithium battery BMS module is electrically connected to the positive input end of the Comp comparator.
[0010] Further, the KM1 contactor switch is a normally closed switch.
[0011] Beneficial effects: the charge and discharge protection circuit of the lithium battery is provided with a charge and discharge detection unit and a switch unit, in an under-voltage state, when charging the battery, the battery pack will not be damaged during low-voltage charging; the voltage of the charge and discharge end is collected through the differential amplifier, the comparator is used for comparing the voltage, when the voltage of the charge and discharge end is lower than the set minimum limit, the charging circuit is cut off, the battery will not appear in the under-voltage charging state, the capacity, performance and internal structure of the battery are maintained, and the service life of the battery is maintained. BRIEF DESCRIPTION OF DRAWINGS
[0012] Figure 1 It is a charging protection circuit block diagram of the lithium battery;
[0013] Figure 2 It is a circuit connection schematic view of the charge and discharge detection unit and the switch unit. DETAILED DESCRIPTION
[0014] The utility model will be further explained in connection with the drawings.
[0015] As Figure 1As shown, a lithium battery charging and discharging protection circuit includes a lithium battery BMS module 1, a battery pack unit 2, a switch unit 3, a charging and discharging end 4, a low-power power supply unit 6 and a charging and discharging detection unit 5; the lithium battery BMS module 1 detects various state data of the battery pack unit 2, and the lithium battery BMS module 1 is bidirectionally connected with the switch unit 3; the power output end of the low-power power supply unit 6 is electrically connected with the power end of the lithium battery BMS module 1 to supply power for the lithium battery BMS module; the positive and negative ends of the battery pack unit 2 are respectively electrically connected with the positive and negative ends of the charging and discharging end 4 through the switch unit 3, the charging and discharging detection unit 5 detects the voltage of the positive and negative ends of the charging and discharging end 4, and the charging and discharging detection unit 5 controls the switch unit 3 to control the opening and closing of the switch unit 3; when the charging voltage is too low, the switch unit 3 is opened to prevent the battery from being damaged.
[0016] As shown, Figure 1 It also includes a communication client unit 7 and a server end 8 connected with the communication client, the communication client unit 7 is bidirectionally connected with the lithium battery BMS module 1 to realize the reception and sending of lithium battery BMS data, and the communication client unit 7 and the server end 8 are bidirectionally and wirelessly connected, and the communication client unit 7 receives and sends data with the server end through wireless transmission. In addition to the basic voltage, temperature, current and other lithium battery protection functions, the lithium battery BMS module 1 measures the total discharge capacity and use time of the lithium battery, and interacts with the server end to determine whether the customer has the use permission of the lithium battery PACK, and controls the power-on and power-off functions through the controller in the battery PACK. The charging and discharging end 4 is used to electrically connect with a load motor or a charger to discharge and charge.
[0017] As shown, Figure 2 The switch unit 3 includes a KM1 contactor switch 31, one end of the KM1 contactor switch 31 is electrically connected with the positive end of the battery pack unit 2, and the other end of the KM1 contactor switch 31 is electrically connected with the positive end of the charging and discharging end 4; the negative end of the battery pack unit 2 is electrically connected with the negative end of the charging and discharging end 4.
[0018] As shown, Figure 2 The switch unit 3 further includes a KM contactor coil 32, an OR gate circuit 34 and an M1 transistor switch 33; the source of the M1 transistor switch 33 is electrically connected with the positive end of the power output end of the low-power power supply unit 6, the drain of the M1 transistor switch 33 is electrically connected with one end of the KM contactor coil 32, the other end of the KM contactor coil 32 is electrically connected with the negative end of the power output end of the low-power power supply unit 6, and the gate of the M1 transistor switch 33 is electrically connected with the output end of the OR gate circuit 34.
[0019] The KM1 contactor switch 31 and the KM contactor coil 32 are two structures of the same contactor; the KM1 contactor switch 31 is a normally closed switch, when the KM contactor coil 32 is powered, the KM1 contactor switch 31 is opened; when the KM contactor coil 32 is powered off, the KM1 contactor switch 31 is closed.
[0020] As shown in Figure 2 The charging and discharging detection unit 5 includes a DA1 differential amplifier 51, a Comp comparator 52 and a bandgap reference circuit 55; the positive input end and the negative input end of the DA1 differential amplifier 51 are electrically connected to the positive end and the negative end of the charging and discharging end 4 respectively, the output end of the DA1 differential amplifier 51 is electrically connected to the positive input end of the Comp comparator 52, and the output end of the DA1 differential amplifier 51 is grounded through an R1 resistor; the negative input end of the Comp comparator 52 is electrically connected to the output end of the bandgap reference circuit 55, and the output end of the Comp comparator 52 is electrically connected to one input end of the OR gate circuit 34. The signal output end of the lithium battery BMS module 1 is electrically connected to the other input end of the OR gate circuit 34. The DA1 differential amplifier 51, the Comp comparator 52 and the bandgap reference circuit 53 are all powered by a low-power power supply unit.
[0021] The DA1 differential amplifier collects the voltage of the positive and negative electrodes of the charging and discharging end and outputs it to the positive input end of the Comp comparator 52, and the bandgap reference circuit 53 outputs a reference voltage VREF input to the negative input end of the Comp comparator 52; the set reference voltage VREF is the lowest voltage allowed for charging the battery during charging, and if the charging voltage is lower than the lowest voltage allowed for charging, the internal structure of the battery pack will be damaged, so the charging needs to be stopped. When the collection voltage VIN collected and output by the DA1 differential amplifier is lower than the reference voltage VREF, the output end of the Comp comparator 52 outputs a low voltage; when the collection voltage VIN collected and output by the DA1 differential amplifier is higher than the reference voltage VREF, the output end of the Comp comparator 52 outputs a high voltage.
[0022] When the signal output end of the lithium battery BMS module outputs a high level and the output end of the Comp comparator 52 outputs a high level; the OR gate circuit 34 outputs a high level to the gate of the M1 transistor switch 33, the M1 transistor switch 33 is turned off, the circuit where the KM contactor coil 32 is located is powered off, and there is no power; at this time, the KM1 contactor switch 31 is closed, and the charging and discharging can be normal. When the signal output end of the lithium battery BMS module outputs a low level, or the output end of the Comp comparator 52 outputs a low level, or both output a low level; the OR gate circuit 34 outputs a low level to the gate of the M1 transistor switch 33, the M1 transistor switch 33 is turned on, the circuit where the KM contactor coil 32 is located is powered on; at this time, the KM1 contactor switch 31 is opened, and the charging and discharging cannot be normal.
[0023] The control output end of the lithium battery BMS module 1 is electrically connected with the band gap reference circuit 55, and the reference voltage output by the band gap reference circuit 55 is controlled. The other control output end of the lithium battery BMS module 1 is electrically connected with the positive input end of the Comp comparator 52. The detection end of the lithium battery BMS module 1 detects the switch state of the KM1 contactor switch 31, detects whether the switch is in the closed state or in the open state, and transmits the detected state to the lithium battery BMS module 1. The band gap reference circuit 55 is a variable and adjustable reference circuit, and the control signal output by the control output end of the lithium battery BMS module 1 controls the reference voltage VREF output by the band gap reference circuit 55. When charging, the control reference voltage VREF of the lithium battery BMS module 1 is set to the minimum voltage allowed for charging of the battery pack. When discharging, the control reference voltage VREF of the lithium battery BMS module 1 is set to the minimum voltage allowed for discharging of the battery pack.
[0024] When the switch unit is in the open state, if charging at this time, the charge and discharge detection unit 5 can detect the voltage across the charge and discharge end 4, and determine whether the charging voltage is higher than the minimum voltage allowed for charging of the battery pack. If it is higher, a high level is output, at this time the lithium battery BMS module 1 outputs a high level, the KM1 contactor switch 31 is closed, and charging is performed. If it is not higher, a low level is output, at this time the lithium battery BMS module 1 outputs a high level, the KM1 contactor switch 31 is still open, and charging is not performed.
[0025] When the switch unit is in the open state, if discharging at this time, the charge and discharge detection unit 5 can detect the voltage across the charge and discharge end 4, at this time the voltage of the charge and discharge end 4 is 0, the voltage collected and output by the DA1 differential amplifier 51 is 0, and therefore the charge and discharge detection unit 5 outputs a low voltage. At this time, the other control output end of the lithium battery BMS module 1 outputs a high voltage to the positive input end of the Comp comparator 52, and makes the high voltage higher than the minimum voltage allowed for discharging of the battery pack. Finally, the charge and discharge detection unit 5 outputs a high level, and at the same time the signal output end of the lithium battery BMS module 1 outputs a high level, the KM1 contactor switch 31 is closed, and discharging is performed. After discharging is completed, the other control output end of the lithium battery BMS module 1 stops outputting a high voltage to the positive input end of the Comp comparator 52. The charge and discharge detection unit 5 then detects the voltage across the charge and discharge end 4 again to determine whether the switch unit is open.
[0026] Embodiment one
[0027] When the user rents the battery, unexpected situations will inevitably occur; when the user does not return the battery after renting it, the user may take the battery home to charge or charge it elsewhere, rather than in the battery cabinet of the battery rental, at which time the charging voltage is not fixed, and a too low charging voltage will damage the battery and its internal structure.
[0028] Therefore, when the battery is charged again, the output end of the Comp comparator 52 and the output end of the lithium battery BMS module 1 both output high voltage; or the output end of the OR gate circuit 34 also outputs high level, the KM contactor coil 32 is powered off, the KM1 contactor switch 31 is closed; the lithium battery BMS module 1 sets the reference voltage VREF output by the bandgap reference circuit 55 as the lowest voltage allowed for charging the battery pack, and the charge and discharge detection circuit 5 detects the voltage between the positive and negative electrodes of the charge and discharge end 4 and compares it with the reference voltage VREF; when it is detected that the voltage between the positive and negative electrodes of the charge and discharge end 4 is higher than the reference voltage VREF, the output end of the Comp comparator 52 still outputs high level; when it is detected that the voltage between the positive and negative electrodes of the charge and discharge end 4 is lower than the reference voltage VREF, the output end of the Comp comparator 52 outputs low level, and the output end of the OR gate circuit 34 outputs low level to the gate of the M1 transistor switch 33 to make it conductive, the KM contactor coil 32 is powered on, and the KM1 contactor switch 31 is opened, so that the charging is stopped. The lithium battery BMS module 1 can cut off the switch through information transmission with the server end 8 connected by the communication client, but when the battery is in an area with poor signal or no signal, the switch cannot be cut off at this time, so the charge and discharge detection unit is set to automatically cut off the switch.
[0029] When the battery can be normally charged, the battery pack unit 2 is fully charged, the lithium battery BMS module 1 can transmit information to the server end 8 connected by the communication client through the communication client unit 7; the server end 8 connected by the communication client sends an instruction to open the switch, the signal output end of the lithium battery BMS module 1 outputs low level, and the output end of the OR gate circuit 34 outputs low level, so that the gate of the M1 transistor switch 33 is conductive, the KM contactor coil 32 is powered on, and the KM1 contactor switch 31 is opened, so that the charging is stopped.
[0030] Example two
[0031] Therefore, when discharging the battery again, the output end of the Comp comparator 52 and the output end of the lithium battery BMS module 1 both output high voltage; or the output end of the OR gate circuit 34 also outputs high level, the KM contactor coil 32 is powered off, the KM1 contactor switch 31 is closed; the lithium battery BMS module 1 sets the reference voltage VREF output by the band gap reference circuit 55 as the minimum voltage allowed by the battery pack to discharge, and the charge-discharge detection circuit 5 detects the voltage between the positive and negative electrodes of the charge-discharge end 4 and compares it with the reference voltage VREF; when it is detected that the voltage between the positive and negative electrodes of the charge-discharge end 4 is higher than the reference voltage VREF, the output end of the Comp comparator 52 still maintains high level output; when it is detected that the voltage between the positive and negative electrodes of the charge-discharge end 4 is lower than the reference voltage VREF, the output end of the Comp comparator 52 outputs low level, and the output end of the OR gate circuit 34 outputs low level to the gate of the M1 transistor switch 33 to make it conductive, the KM contactor coil 32 is powered on, so that the KM1 contactor switch 31 is opened, and the discharging is stopped; a part of the battery pack unit 2 is reserved to maintain its own function.
[0032] Similarly, another method can be used. When the battery can be normally charged, the battery pack unit 2 is reduced to the set minimum amount of electricity, the lithium battery BMS module 1 can transmit information to the server end 8 connected to the communication client through the communication client unit 7; the server end 8 connected to the communication client sends an instruction to open the switch, the signal output end of the lithium battery BMS module 1 outputs low level, and the output end of the OR gate circuit 34 outputs low level, so that the gate of the M1 transistor switch 33 is conductive, the KM contactor coil 32 is powered on, so that the KM1 contactor switch 31 is opened, and the discharging is stopped. However, when the battery is in a weak signal or even no signal position, the switch cannot be opened through communication with the server end 8 connected to the communication client.
[0033] The above is only a description of the preferred embodiments of the present application, and those skilled in the art can make some modifications and optimizations based on the above disclosure without departing from the above basic principles. These improvements and optimizations should be considered as the protection scope of the present application.
Claims
1. A charge-discharge protection circuit for a lithium battery, characterized by: The application relates to a lithium battery BMS module (1), a battery unit (2), a switch unit (3), a charging and discharging end (4), a low-power power supply unit (6) and a charging and discharging detection unit (5); the lithium battery BMS module (1) detects various state data of the battery unit (2), and the lithium battery BMS module (1) is in bidirectional transmission connection with the switch unit (3); a power output end of the low-power power supply unit (6) is electrically connected with a power supply end of the lithium battery BMS module (1); positive and negative electrode ends of the battery unit (2) are respectively electrically connected with positive and negative electrode ends of the charging and discharging end (4) through the switch unit (3), a charging and discharging detection unit (5) detects the voltage of the positive and negative electrode ends of the charging and discharging end (4), and the charging and discharging detection unit (5) controls the switch unit (3) to control the opening and closing of the switch unit (3).
2. The charging and discharging protection circuit of a lithium battery according to claim 1, characterized in that: The switch unit (3) comprises a KM1 contactor switch (31); one end of the KM1 contactor switch (31) is electrically connected with a positive electrode end of the battery unit (2), and the other end of the KM1 contactor switch (31) is electrically connected with a positive electrode end of the charging and discharging end (4); a negative electrode end of the battery unit (2) is electrically connected with a negative electrode end of the charging and discharging end (4).
3. The charging and discharging protection circuit of a lithium battery according to claim 2, characterized in that: The switch unit (3) further comprises a KM contactor coil (32), an OR gate circuit (34) and an M1 transistor switch (33); a source of the M1 transistor switch (33) is electrically connected with a positive electrode of a power output end of the low-power power supply unit (6), a drain of the M1 transistor switch (33) is electrically connected with one end of the KM contactor coil (32), the other end of the KM contactor coil (32) is electrically connected with a negative electrode of the power output end of the low-power power supply unit (6), and a gate of the M1 transistor switch (33) is electrically connected with an output end of the OR gate circuit (34).
4. The charging and discharging protection circuit of a lithium battery according to claim 3, characterized in that: The charging and discharging detection unit (5) comprises a DA1 differential amplifier (51), a Comp comparator (52) and a band gap reference circuit (55); a positive input end and a negative input end of the DA1 differential amplifier (51) are respectively electrically connected with a positive electrode end and a negative electrode end of the charging and discharging end (4), and an output end of the DA1 differential amplifier (51) is electrically connected with a positive input end of the Comp comparator (52); a negative input end of the Comp comparator (52) is electrically connected with an output end of the band gap reference circuit (55), and an output end of the Comp comparator (52) is electrically connected with one input end of the OR gate circuit (34).
5. The charging and discharging protection circuit of a lithium battery according to claim 4, characterized in that: A signal output end of the lithium battery BMS module (1) is electrically connected with the other input end of the OR gate circuit (34).
6. The charging and discharging protection circuit of a lithium battery according to claim 4, characterized in that: A control output end of the lithium battery BMS module (1) is electrically connected with the band gap reference circuit (55) to control the reference voltage output by the band gap reference circuit (55); and another control output end of the lithium battery BMS module (1) is electrically connected with the positive input end of the Comp comparator (52).
7. The charging and discharging protection circuit of lithium battery according to claim 4, characterized in that: The KM1 contactor switch (31) is a normally closed switch.