Novel lithium battery protection circuit and circuit protection board

Abstract

The utility model provides a novel lithium battery protection circuit and a circuit protection board. The protection function of the circuit is realized by additionally arranging a positive end measuring circuit and a negative end measuring circuit. Wherein the positive-end measuring circuit comprises two divider resistors, and the positive-end voltage value of the charger is obtained by performing analog-to-digital conversion on the divided voltage through the processor; the negative end measuring circuit comprises four resistors and calculates the negative end voltage value of the charger based on the Kirchhoff's current law; and calculating a charger voltage value based on the charger positive-end voltage value and the charger negative-end voltage value, comparing the charger voltage value with a standard voltage value, and judging whether the charger voltage value at the moment meets the standard or not. The lithium battery protection method provided by the utility model is simple, easy to understand and easy to realize, the number of electronic components used by the corresponding lithium battery protection circuit is small, and the circuit structure is simple. According to the utility model, accurate measurement of the voltage of the charger is realized with extremely low material cost and production cost, and the cost performance is extremely high.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium batteries, and in particular to a novel lithium battery protection circuit and a circuit protection board. Background Art

[0002] In the field of lithium battery protection circuits, a common design scheme is called charging and discharging at the same port and switching control at the total negative terminal, referred to as same port control negative. This scheme is widely used because it has the advantages of maturity, reliability, and low cost. It is used in many products such as handheld power tools, cleaning tools, power banks, base station energy storage, and home energy storage.

[0003] However, as people's awareness of lithium battery protection continues to increase, more and more electronic devices require confirmation of the correct charger voltage before turning on the charging MOS. This trend has led to a new problem: in the same-port negative control solution, the negative end of the load, that is, the negative end of the charger, is not grounded before the charging MOS is closed, which makes it impossible for the processor MCU to conveniently measure the charger voltage. If voltage measurement is required, an expensive and complex isolation acquisition circuit must be added, which not only increases the complexity of the entire circuit system, but also increases production costs. Utility Model Content

[0004] In order to solve the above technical problems, the utility model provides a novel lithium battery protection circuit and circuit protection board, which realize the protection function of the circuit by adding a positive terminal measurement circuit and a negative terminal measurement circuit; wherein, the positive terminal measurement circuit obtains the voltage of the positive terminal of the load, that is, the positive terminal of the charger, by performing analog-to-digital conversion on the voltage after voltage division; the negative terminal measurement circuit obtains the voltage of the negative terminal of the load, that is, the negative terminal of the charger, based on Kirchhoff's current law; based on the positive terminal voltage value of the charger and the negative terminal voltage value of the charger, the charger voltage value is calculated and compared with the standard voltage value to determine whether the charger voltage value at this time meets the standard.

[0005] In a first aspect, the utility model provides a novel lithium battery protection circuit, comprising:

[0006] A battery pack consisting of multiple battery cells connected in series.

[0007] The battery management chip comprises a plurality of first ports connected in parallel with the battery packs connected in series, and a second port and a third port connected to the charging MOS tube and the discharging MOS tube respectively.

[0008] Processor: has a communication connection with the battery management chip.

[0009] in,

[0010] The first MOS tube and the second MOS tube are sequentially connected in series, one end of which is connected to the positive terminal of the battery pack, and the other end is connected to the positive terminal of the charger.

[0011] Characterized in that, the lithium battery protection circuit also includes: a positive terminal measurement circuit and a negative terminal measurement circuit.

[0012] in,

[0013] The positive terminal measurement circuit is connected between the processor and the positive terminal of the charger.

[0014] The negative terminal measurement circuit is connected between the processor and the negative terminal of the charger.

[0015] Furthermore, the processor at least includes: a positive terminal digital-to-analog conversion port, a negative terminal digital-to-analog conversion port, an I / O port and a positive terminal digital-to-analog conversion enable port.

[0016] Furthermore, the positive terminal measurement circuit includes: a first voltage-dividing resistor R1, a second voltage-dividing resistor R2, a resistor Rpad and a third MOS tube Q3.

[0017] Furthermore, the positive terminal measurement circuit includes:

[0018] One end of the first voltage-dividing resistor R1 is connected to the positive terminal of the charger, and the other end is connected to the source of the third MOS tube Q3.

[0019] One end of the second voltage-dividing resistor R2 is connected to the drain of the third MOS transistor Q3 , and the other end is grounded.

[0020] One end of the resistor Rpad is connected to the drain of the third MOS tube Q3 , and the other end is connected to the processor.

[0021] Furthermore, the positive terminal measurement circuit further includes:

[0022] The gate of the third MOS tube Q3 is connected to the positive digital-to-analog conversion enable port of the processor.

[0023] The resistor Rpad is connected to the positive digital-to-analog conversion port of the processor.

[0024] The processor controls the opening or closing of the positive terminal measurement circuit through the positive terminal digital-to-analog conversion enable port of the processor. When the charger voltage measurement is not required, the positive terminal measurement circuit can be closed to save energy consumption of the circuit system.

[0025] The positive digital-to-analog conversion port of the processor is connected to the resistor Rpad, and the voltage across the resistor Rpad is obtained through analog-to-digital conversion, thereby obtaining the positive terminal voltage of the charger.

[0026] Furthermore, the negative terminal measurement circuit includes: a resistor Rp, a resistor Rn, a resistor Rt, a resistor Rnad, a diode Dn, a node B and a DC voltage source VDD.

[0027] Furthermore, the negative terminal measurement circuit includes:

[0028] One end of the resistor Rp is connected to the node B, and the other end is connected to the DC voltage source VDD.

[0029] One end of the resistor Rn is connected to the node B, and the other end is grounded.

[0030] One end of the resistor Rt is connected to the node B, and the other end is connected to the positive terminal of the charger.

[0031] The diode Dn has an anode connected to the node B, a cathode connected to the DC voltage source VDD, and is connected in parallel with the resistor Rp.

[0032] One end of the resistor Rnad is connected to the node B, and the other end is connected to the processor.

[0033] Furthermore, the negative terminal measurement circuit includes.

[0034] The DC voltage source VDD is connected to the I / O port of the processor.

[0035] The resistor Rpad is connected to the negative terminal digital-to-analog conversion port of the processor.

[0036] The processor controls the opening or closing of the negative terminal measurement circuit through the I / O port of the processor. When the charger voltage measurement is not required, the positive terminal measurement circuit can be closed to save energy consumption of the circuit system.

[0037] The negative end digital-to-analog conversion port of the processor and the resistor Rnad obtain the voltage across the resistor Rnad through analog-to-digital conversion, thereby obtaining the voltage of the node B.

[0038] Furthermore, according to Kirchhoff's current law, the sum of the currents of the branches of node B is 0. The current value flowing from the node to the negative terminal of the charger is calculated, and multiplied by the resistance Rt in series between them, which is the voltage value of the node relative to the negative terminal of the charger.

[0039] Furthermore, based on the voltage of the node B and the voltage value of the node relative to the negative terminal of the charger, the voltage of the negative terminal of the charger is calculated.

[0040] Furthermore, based on the charger positive terminal voltage and the charger negative terminal voltage, a charger voltage is calculated.

[0041] Further, it is determined whether the charger voltage UC is consistent with the standard charger voltage value, if so, the charging MOS tube is turned on; if not, the charging MOS tube is continuously turned off.

[0042] In the second aspect, the utility model proposes a circuit protection board, comprising: the above-mentioned new type of lithium battery protection circuit, the circuit is integrated on a circuit substrate; the battery protection board comprises: the above-mentioned lithium battery protection circuit, and a circuit substrate, the lithium battery protection circuit is integrated on the circuit substrate.

[0043] In summary, the utility model proposes a novel lithium battery protection circuit and circuit protection board, which realize the protection function of the circuit by adding a positive terminal measurement circuit and a negative terminal measurement circuit; the positive terminal measurement circuit is used to obtain the voltage of the positive terminal of the load, that is, the positive terminal of the charger; the negative terminal is used to obtain the voltage of the negative terminal of the load, that is, the negative terminal of the charger; then, based on the positive terminal voltage value of the charger and the negative terminal voltage value of the charger, the charger voltage value is calculated and compared with the standard voltage value to determine whether the charger voltage value at this time meets the standard.

[0044] Compared with the prior art, the present invention has at least the following beneficial effects:

[0045] The lithium battery protection method proposed by the utility model is simple, understandable and easy to implement. The number of electronic components used in the corresponding lithium battery protection circuit is small, and the circuit structure is simple. The voltage value of the charger can be calculated by simply adding a few resistor components and an analog-to-digital conversion port. The utility model can achieve accurate measurement of the charger voltage with extremely low material cost and production cost, and has extremely high cost performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of a lithium battery protection circuit shown in an embodiment of the utility model.

[0047] Figure 2 It is a schematic diagram of a positive terminal measurement circuit shown in an embodiment of the utility model.

[0048] Figure 3 It is a schematic diagram of a negative terminal measurement circuit shown in an embodiment of the utility model. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model. Example

[0050] See also Figure 1 , is a schematic diagram of a lithium battery protection circuit shown in an embodiment of the utility model, specifically comprising:

[0051] A battery pack consisting of multiple battery cells connected in series.

[0052] The battery management chip AFE comprises a plurality of first ports connected in parallel with the battery packs connected in series, and a second port and a third port connected to the charging MOS tube CMOS and the discharging MOS tube DMOS respectively.

[0053] Processor MCU: has a communication connection with the battery management chip.

[0054] in,

[0055] The charging MOS tube CMOS and the discharging MOS tube DMOS are sequentially connected in series, and one end of the tube is connected to the positive terminal of the battery pack, and the other end is connected to the positive terminal of the charger.

[0056] The lithium battery protection circuit also includes: a positive terminal measurement circuit and a negative terminal measurement circuit.

[0057] in,

[0058] The positive terminal measurement circuit is connected between the processor and the positive terminal of the charger.

[0059] The negative terminal measurement circuit is connected between the processor and the negative terminal of the charger.

[0060] In an embodiment of the utility model, optionally, the processor at least includes: a positive terminal digital-to-analog conversion port, a negative terminal digital-to-analog conversion port, an I / O port and a positive terminal digital-to-analog conversion enable port.

[0061] In the embodiment of the utility model, optionally, as shown in the attached Figure 2 As shown, the positive terminal measurement circuit includes: a first voltage-dividing resistor R1, a second voltage-dividing resistor R2, a resistor Rpad, a capacitor Cpad, a protection resistor R3 and a third MOS tube Q3.

[0062] Furthermore, the positive terminal measurement circuit includes:

[0063] One end of the first voltage-dividing resistor R1 is connected to the positive terminal of the charger, and the other end is connected to the source of the third MOS tube Q3.

[0064] One end of the second voltage-dividing resistor R2 is connected to the drain of the third MOS transistor Q3 , and the other end is grounded.

[0065] One end of the resistor Rpad is connected to the drain of the third MOS tube Q3 , and the other end is connected to the processor.

[0066] One end of the resistor Cpad is connected to the positive terminal digital-to-analog conversion port, and the other end is grounded.

[0067] Furthermore, the positive terminal measurement circuit further includes:

[0068] The gate of the third MOS tube Q3 is connected to the positive terminal digital-to-analog conversion enable port of the processor through the protection resistor R3.

[0069] The resistor Rpad is connected to the positive terminal digital-to-analog conversion port of the processor.

[0070] The processor controls the opening or closing of the positive terminal measurement circuit through the positive terminal digital-to-analog conversion enable port of the processor. When the charger voltage measurement is not required, the positive terminal measurement circuit can be closed to save energy consumption of the circuit system.

[0071] The positive digital-to-analog conversion port of the processor is connected to the resistor Rpad, and the voltage across the resistor Rpad is obtained through analog-to-digital conversion, thereby obtaining the positive terminal voltage Uchp of the charger.

[0072] In the embodiment of the utility model, optionally, as shown in the attached Figure 3 As shown, the negative terminal measurement circuit includes: a resistor Rp, a resistor Rn, a resistor Rt, a resistor Rnad, a diode Dn, a capacitor Cnad, a node B and a DC voltage source VDD.

[0073] Furthermore, the negative terminal measurement circuit includes:

[0074] One end of the resistor Rp is connected to the node B, and the other end is connected to the DC voltage source VDD.

[0075] One end of the resistor Rn is connected to the node B, and the other end is grounded.

[0076] One end of the resistor Rt is connected to the node B, and the other end is connected to the positive terminal of the charger.

[0077] The diode Dn has an anode connected to the node B, a cathode connected to the DC voltage source VDD, and is connected in parallel with the resistor Rp.

[0078] One end of the resistor Rnad is connected to the node B, and the other end is connected to the processor.

[0079] Furthermore, the negative terminal measurement circuit includes:

[0080] The DC voltage source VDD is connected to the I / O port of the processor.

[0081] The resistor Rpad is connected to the negative terminal digital-to-analog conversion port of the processor.

[0082] One end of the capacitor Cnad is connected to the negative terminal digital-to-analog conversion port, and the other end is grounded.

[0083] The processor controls the opening or closing of the negative terminal measurement circuit through the I / O port of the processor. When the charger voltage measurement is not required, the positive terminal measurement circuit can be closed to save energy consumption of the circuit system.

[0084] The negative end digital-to-analog conversion port of the processor is connected to the resistor Rnad, and the voltage across the resistor Rnad is obtained through analog-to-digital conversion, thereby obtaining the voltage UB of the node B.

[0085] Analog-to-Digital Conversion (ADC) is a technique used to convert analog signals, such as voltage, into digital signals that can be processed and analyzed in digital systems.

[0086] In the embodiment of the utility model, optionally, the analog-to-digital conversion can be: successive approximation (Successive Approximation), single-bit ΔΣ (Delta-Sigma) modulation, Flash, and integral type, etc.

[0087] Furthermore, according to Kirchhoff's current law, the sum of the currents of the branches of node B is 0. The current value flowing from the node to the negative terminal of the charger is calculated, and multiplied by the resistance Rt in series between them, which is the voltage value of the node relative to the negative terminal of the charger.

[0088] Kirchhoff's laws are divided into Kirchhoff's Current Law (KCL) and Kirchhoff's Voltage Law (KUL).

[0089] Kirchhoff's current law states that at any node in a circuit, the sum of the currents flowing into the node is equal to the sum of the currents flowing out of the node. In other words, the current at the node is conserved and no current accumulates at the node.

[0090] Kirchhoff's voltage law states that in any closed loop of a circuit, the sum of the voltage drop and voltage rise across each component is zero, which reflects the conservation of energy in the circuit.

[0091] Furthermore, based on the voltage UB at the node B and the voltage value of the node relative to the negative terminal of the charger, the negative terminal voltage Uchn of the charger is calculated.

[0092] Furthermore, based on the charger positive terminal voltage Uchp and the charger negative terminal voltage Uchn, a charger voltage Uchg is calculated.

[0093] Further, it is determined whether the charger voltage Uchg is consistent with the standard charger voltage value. If so, the charging MOS tube is turned on; if not, the charging MOS tube is continuously turned off.

[0094] In the embodiment of the utility model, optionally, when the charger is connected and the charging MOS tube is not turned on, there are:

[0095] (VDD-UB) / Rp=(UB-Uchn) / Rt+UB / Rn+UB / Rnad.

[0096] Then we get:

[0097] Uchn=UB+Rt / Rn*UB+Rt / Rnad*UB-Rt / Rp*(VDD-UB).

[0098] Among them, the right side of the formula are all known quantities, and the negative terminal voltage Uchn of the charger can be easily calculated.

[0099] Furthermore, Uchg=Uchp-Uchn, and the charger voltage Uchg can be simply calculated.

[0100] In the embodiment of the utility model, the optional resistor device used uses a resistor with an error less than 1%, which is beneficial to the accuracy of the calculation of the charger voltage Uchg. Example

[0101] The utility model proposes a circuit protection board, comprising: the novel lithium battery protection circuit mentioned above, wherein the circuit is integrated on a circuit substrate; the battery protection board comprises: the lithium battery protection circuit mentioned above, and a circuit substrate, wherein the lithium battery protection circuit is integrated on the circuit substrate.

[0102] In the embodiment of the utility model, optionally, the material used for the circuit substrate is glass fiber reinforced epoxy resin, but not limited thereto.

[0103] In summary, the utility model proposes a novel lithium battery protection circuit and circuit protection board, which realize the protection function of the circuit by adding a positive terminal measurement circuit and a negative terminal measurement circuit; the positive terminal measurement circuit includes two voltage-dividing resistors and a MOS tube, and the processor obtains the positive terminal voltage of the charger by performing analog-to-digital conversion on the voltage after voltage division; the negative terminal measurement circuit includes four resistors and a node, and the node voltage is firstly converted into an analog-to-digital conversion to obtain the node voltage; then, based on Kirchhoff's law and the node voltage, the negative terminal voltage of the charger is obtained; after obtaining the positive terminal voltage of the charger and the negative terminal voltage of the charger, the charger voltage is calculated and compared with the standard charger voltage.

[0104] The lithium battery protection method proposed by the utility model is simple to understand and easy to implement. The corresponding lithium battery protection circuit uses a small number of electronic components and has a simple circuit structure. The utility model can achieve accurate measurement of charger voltage with extremely low material cost and production cost, and has extremely high cost performance.

[0105] The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the utility model in detail. It should be understood that the above description is only a specific embodiment of the utility model and is not intended to limit the protection scope of the utility model. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A new type of lithium battery protection circuit, comprising at least: A battery pack consisting of multiple battery cells connected in series; A battery management chip: comprising a plurality of first ports connected in parallel with the battery packs connected in series, and a second port and a third port connected to a charging MOS tube and a discharging MOS tube respectively; Processor: has a communication connection with the battery management chip; in, The first MOS tube and the second MOS tube are connected in series in sequence, one end of which is connected to the positive terminal of the battery pack, and the other end is connected to the positive terminal of the charger; Characterized in that the lithium battery protection circuit further comprises: a positive terminal measurement circuit and a negative terminal measurement circuit; in, The positive terminal measurement circuit is connected between the processor and the positive terminal of the charger; The negative terminal measurement circuit is connected between the processor and the negative terminal of the charger.

2. A novel lithium battery protection circuit according to claim 1, characterized in that: The processor at least includes: a positive terminal digital-to-analog conversion port, a negative terminal digital-to-analog conversion port, an I / O port and a positive terminal digital-to-analog conversion enable port.

3. A novel lithium battery protection circuit according to claim 2, characterized in that: The positive terminal measurement circuit includes: a first voltage-dividing resistor R1, a second voltage-dividing resistor R2, a resistor Rpad and a third MOS tube Q3.

4. A novel lithium battery protection circuit according to claim 3, characterized in that: The positive terminal measurement circuit comprises: One end of the first voltage-dividing resistor R1 is connected to the positive terminal of the charger, and the other end is connected to the source of the third MOS tube Q3; One end of the second voltage-dividing resistor R2 is connected to the drain of the third MOS tube Q3, and the other end is grounded; One end of the resistor Rpad is connected to the drain of the third MOS tube Q3 , and the other end is connected to the processor.

5. A novel lithium battery protection circuit according to claim 4, characterized in that: The positive terminal measurement circuit comprises: The gate of the third MOS tube Q3 is connected to the positive terminal digital-to-analog conversion enable port of the processor; The resistor Rpad is connected to the positive digital-to-analog conversion port of the processor.

6. A novel lithium battery protection circuit according to claim 5, characterized in that: The negative terminal measurement circuit includes: a resistor Rp, a resistor Rn, a resistor Rt, a resistor Rnad, a diode Dn, a node B and a DC voltage source VDD.

7. A novel lithium battery protection circuit according to claim 6, characterized in that: The negative terminal measurement circuit comprises: One end of the resistor Rp is connected to the node B, and the other end is connected to the DC voltage source VDD; One end of the resistor Rn is connected to the node B, and the other end is grounded; One end of the resistor Rt is connected to the node B, and the other end is connected to the positive terminal of the charger; The anode of the diode Dn is connected to the node B, the cathode is connected to the DC voltage source VDD, and the diode Dn is connected in parallel with the resistor Rp; One end of the resistor Rnad is connected to the node B, and the other end is connected to the processor.

8. A novel lithium battery protection circuit according to claim 7, characterized in that: The negative terminal measurement circuit comprises: A DC voltage source VDD is connected to the processed I / O port; The resistor Rpad is connected to the negative digital-to-analog conversion port of the processor.

9. A circuit protection board, characterized in that: include: A novel lithium battery protection circuit as described in any one of claims 1 to 8, and a circuit substrate, wherein the novel lithium battery protection circuit is integrated on the circuit substrate.

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