Lithium battery protection circuit for secondary protection
By designing a lithium battery protection circuit combining primary and secondary protection units, multi-level protection of lithium batteries is achieved, solving the problem that traditional lithium battery protection circuit lacks secondary protection function, and significantly improving the safety of the battery.
Patent Information
- Application Number
- CN202421219849.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-31
- Publication Date
- 2025-02-25
- Estimated Expiration
- 2034-05-31
AI Technical Summary
Traditional lithium battery protection circuits lack secondary protection functions and cannot effectively prevent safety hazards such as overcharge, overdischarge, overcurrent and short circuit.
A secondary protection lithium battery protection circuit is designed, using a combination of primary protection unit and secondary protection unit to detect the intermediate voltage of lithium battery, and the current is detected through series charge and discharge switches and alloy resistance, so as to realize the second Secondary charge overvoltage protection, secondary discharge undervoltage protection, secondary charge overcurrent protection and secondary discharge overcurrent protection.
This design significantly improves the safety of lithium batteries. Through the multi-level protection mechanism, it can effectively prevent overvoltage, undervoltage, overcurrent and other safety hazards during charging and discharging, improving the safety of battery use.
Smart Images
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Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of lithium ion batteries, in particular to a lithium battery protection circuit with secondary protection. Background Art
[0002] Lithium batteries have the advantages of relatively high energy, long service life, high rated voltage, high power tolerance, very low self-discharge rate, light weight, and strong adaptability to high and low temperatures. However, they have the disadvantages of poor safety and require protection circuits to prevent overcharging, over-discharging, over-current, short circuit, and over-temperature protection.
[0003] The secondary protection circuit of the traditional lithium battery protection circuit is protected by a fuse, and only has secondary charging overvoltage protection, but does not have secondary undervoltage protection, secondary charging overcurrent protection, and secondary discharge overcurrent protection. Utility Model Content
[0004] The utility model aims to provide a lithium battery protection circuit with secondary protection, which can realize secondary charging overvoltage protection, secondary discharging undervoltage protection, secondary charging overcurrent protection and secondary discharging overcurrent protection.
[0005] The technical solution of the utility model is:
[0006] A secondary protection lithium battery protection circuit, wherein the lithium battery is a double-cell lithium battery, the positive and negative charging terminals P+ and P- are respectively connected to the positive and negative electrodes B+ and B- of the lithium battery, the lithium battery protection circuit comprises a primary protection unit and a secondary protection unit, both of which are connected to detect the middle voltage of the double-cell lithium battery; two groups of charge and discharge switches are connected in series between the negative charging terminal P- and the negative electrode B- of the lithium battery, and the primary protection unit and the secondary protection unit are respectively connected to control one group of charge and discharge switches.
[0007] Preferably, the primary protection unit and the secondary protection unit have different overvoltage and undervoltage protection voltage values.
[0008] Preferably, the two groups of charge and discharge switches are connected to a common reference potential P1, the two groups of charge and discharge switches are respectively connected in series with alloy resistors RS1 and RS4, and the primary protection unit and the secondary protection unit are respectively connected to detect the current of the two groups of charge and discharge switches through resistors R2 and R6.
[0009] Preferably, the alloy resistors RS1 and RS4 set the charge and discharge overcurrent protection values of the two groups of charge and discharge switches by adjusting different resistance values.
[0010] Preferably, among the two groups of charge and discharge switches, the first group of charge and discharge switches includes MOS tubes Q1 and Q2 connected in series, and the primary protection unit is respectively connected to control the gates of the MOS tubes Q1 and Q2; the second group of charge and discharge switches includes MOS tubes Q5 and Q6 connected in series, and the secondary protection unit is respectively connected to control the gates of the MOS tubes Q5 and Q6.
[0011] Preferably, the first group of charge and discharge switches also includes MOS tubes Q3 and Q4 respectively connected in parallel with the MOS tubes Q1 and Q2, and the primary protection unit is respectively connected to control the gates of the MOS tubes Q3 and Q4; the second group of charge and discharge switches also includes MOS tubes Q7 and Q8 respectively connected in parallel with the MOS tubes Q5 and Q6, and the secondary protection unit is respectively connected to control the gates of the MOS tubes Q7 and Q8.
[0012] Preferably, capacitors C11 and C12 connected in series are connected in parallel at both ends of the first group of charge and discharge switches; and capacitors C9 and C10 connected in series are connected in parallel at both ends of the second group of charge and discharge switches.
[0013] Preferably, the primary protection unit and the secondary protection unit adopt R5460 lithium battery protection IC.
[0014] Preferably, a fuse F is connected in series between the positive charging terminal P+ and the positive electrode B+ of the lithium battery.
[0015] The advantages of the utility model are:
[0016] 1. The utility model adopts a primary protection unit and a secondary protection unit with different protection voltage values. When the charging voltage reaches a low overvoltage value, the first overvoltage protection is triggered. If the protection fails, charging continues. When the voltage value reaches a high overvoltage value, the second overvoltage protection is triggered. Similarly, secondary discharge undervoltage protection can be obtained during discharge. Since the two protection units independently control the charge and discharge switches, they have high safety.
[0017] 2. The utility model adopts two alloy resistors to detect the charging and discharging currents of two groups of charging and discharging switches respectively. By adjusting the resistance values of the two alloy resistors respectively, the two protection units can detect different voltages, thereby having different overcurrent protection values, and realizing secondary charging and discharging overcurrent protection. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The utility model is further described below in conjunction with the accompanying drawings and embodiments:
[0019] Figure 1 This is a schematic diagram of the secondary protection lithium battery protection circuit of the utility model. DETAILED DESCRIPTION
[0020] like Figure 1As shown, the secondary protection lithium battery protection circuit of the present invention, the lithium battery is a double-cell lithium battery, the positive and negative charging terminals P+, P- are respectively connected to the positive and negative electrodes B+, B- of the lithium battery, and a fuse F is connected in series between the positive charging terminal P+ and the positive electrode B+ of the lithium battery.
[0021] Figure 1 In the figure, the lithium battery protection circuit includes a primary protection unit and a secondary protection unit, both of which are connected to the middle node B1 of the double-cell lithium battery; two groups of charge and discharge switches are connected in series between the negative charging terminal P- and the negative electrode B- of the lithium battery, and the primary protection unit and the secondary protection unit are respectively connected to control one group of charge and discharge switches.
[0022] In the two groups of charge and discharge switches, the first group of charge and discharge switches includes MOS tubes Q1 and Q2 connected in series, and the primary protection unit is connected to control the gates of MOS tubes Q1 and Q2 respectively; the second group of charge and discharge switches includes MOS tubes Q5 and Q6 connected in series, and the secondary protection unit is connected to control the gates of MOS tubes Q5 and Q6 respectively. The first group of charge and discharge switches also includes MOS tubes Q3 and Q4 connected in parallel with MOS tubes Q1 and Q2 respectively, and the primary protection unit is connected to control the gates of MOS tubes Q3 and Q4 respectively; the second group of charge and discharge switches also includes MOS tubes Q7 and Q8 connected in parallel with MOS tubes Q5 and Q6 respectively, and the secondary protection unit is connected to control the gates of MOS tubes Q7 and Q8 respectively. The first group of charge and discharge switches are connected in parallel with capacitors C11 and C12 in series; the second group of charge and discharge switches are connected in parallel with capacitors C9 and C10 in series.
[0023] The primary protection unit and the secondary protection unit respectively use R5460 lithium battery protection ICs U1 and U2. The U1 and U2 have different overvoltage and undervoltage protection voltage values. The overvoltage value of U1 is less than the overvoltage value of U2. When the charging voltage reaches the overvoltage value of U1, the first overvoltage protection is triggered. If the protection fails, charging continues. When the voltage value reaches the overvoltage value of U2, the second overvoltage protection is triggered. Similarly, secondary discharge undervoltage protection can be obtained during discharge. Since the two protection units independently control two groups of charging and discharging switches, they have high safety.
[0024] The two groups of charge and discharge switches are connected to a reference potential P1, and the two groups of charge and discharge switches are respectively connected in series with alloy resistors RS1 and RS4, and U1 and U2 are respectively connected to detect the current of the two groups of charge and discharge switches through resistors R2 and R6. U1 triggers the primary overcurrent protection by detecting the voltage across RS1 and MOS tubes Q1 Q2 Q3 Q4, and U2 triggers the secondary overcurrent protection by detecting the voltage across RS4 and the charge and discharge MOS tubes Q5 Q6Q7 Q8. The alloy resistors RS1 and RS4 set the charge and discharge overcurrent protection values of the two groups of charge and discharge switches by adjusting different resistance values, thereby realizing different secondary charge and discharge overcurrent protections.
[0025] The above embodiments are only for illustrating the technical concept and features of the utility model, and their purpose is to enable people familiar with the technology to understand the content of the utility model and implement it accordingly, and they cannot be used to limit the protection scope of the utility model. Any modifications made according to the spirit of the main technical solution of the utility model should be included in the protection scope of the utility model.
Claims
1. A secondary protection lithium battery protection circuit, wherein the lithium battery is a double-cell lithium battery, and the positive and negative charging terminals P+ and P- are connected to the positive and negative electrodes B+ and B- of the lithium battery respectively, characterized in that: The lithium battery protection circuit includes a primary protection unit and a secondary protection unit, both of which are connected to detect the middle voltage of the dual-cell lithium battery; two groups of charge and discharge switches are connected in series between the negative charging terminal P- and the negative electrode B- of the lithium battery, and the primary protection unit and the secondary protection unit are respectively connected to control one group of charge and discharge switches.
2. The secondary protection lithium battery protection circuit according to claim 1, characterized in that: The primary protection unit and the secondary protection unit have different overvoltage and undervoltage protection voltage values.
3. The secondary protection lithium battery protection circuit according to claim 2, characterized in that: The two groups of charge and discharge switches are connected to a common reference potential P1, and the two groups of charge and discharge switches are respectively connected in series with alloy resistors RS1 and RS4. The primary protection unit and the secondary protection unit are respectively connected to detect the current of the two groups of charge and discharge switches through resistors R2 and R6.
4. The secondary protection lithium battery protection circuit according to claim 3, characterized in that: The alloy resistors RS1 and RS4 are used to set the charge and discharge overcurrent protection values of the two groups of charge and discharge switches by adjusting different resistance values.
5. The secondary protection lithium battery protection circuit according to claim 4, characterized in that: Among the two groups of charge and discharge switches, the first group of charge and discharge switches includes MOS tubes Q1 and Q2 connected in series, and the primary protection unit is respectively connected to control the gates of the MOS tubes Q1 and Q2; the second group of charge and discharge switches includes MOS tubes Q5 and Q6 connected in series, and the secondary protection unit is respectively connected to control the gates of the MOS tubes Q5 and Q6.
6. The secondary protection lithium battery protection circuit according to claim 5, characterized in that: The first group of charge and discharge switches also includes MOS tubes Q3 and Q4 connected in parallel with the MOS tubes Q1 and Q2 respectively, and the primary protection unit is connected to control the gates of the MOS tubes Q3 and Q4 respectively; the second group of charge and discharge switches also includes MOS tubes Q7 and Q8 connected in parallel with the MOS tubes Q5 and Q6 respectively, and the secondary protection unit is connected to control the gates of the MOS tubes Q7 and Q8 respectively.
7. The secondary protection lithium battery protection circuit according to claim 6, characterized in that: The two ends of the first group of charge and discharge switches are connected in parallel with capacitors C11 and C12 connected in series; the two ends of the second group of charge and discharge switches are connected in parallel with capacitors C9 and C10 connected in series.
8. The secondary protection lithium battery protection circuit according to claim 3, characterized in that: The primary protection unit and the secondary protection unit adopt R5460 lithium battery protection IC.
9. The secondary protection lithium battery protection circuit according to claim 3, characterized in that: A fuse F is connected in series between the positive charging terminal P+ and the positive electrode B+ of the lithium battery.