A protection control circuit and method for a battery cell

Abstract

The present invention discloses a protection control circuit and method for a battery cell; wherein a main control module determines whether to switch the working state of a switch control module according to a signal collected from a charge and discharge control module, so that the battery cell stops charging or discharging; and provides a reliable and safe protection control circuit for a battery cell and an effective and reliable protection control method for a battery cell.

Description

Technical Field

[0001] The present invention relates to the technical field of safe charging and discharging of power supplies, and in particular to a protection control circuit and method for a battery cell. Background Art

[0002] With the continuous development of battery technology, battery power supply has become an important means of power supply in many fields. Therefore, how to ensure that the battery can be safely charged and discharged has become a technical problem that must be solved.

[0003] In the prior art, a general lithium battery protection board protects the battery by controlling the switch of the MOS tube to prevent the battery from being overcharged, over-discharged, over-current, over-temperature, short-circuited, and other abnormalities. However, such a technical solution has certain disadvantages: since the MOS tube has a certain withstand voltage value, if the voltage is too high during the battery charging and discharging process, the MOS tube is easily broken down. After the MOS tube is broken down, it is generally in a conducting state, which will cause the battery protection function to be lost. At this time, if the terminal product connected to the battery is overcharged, over-discharged, short-circuited, and over-heated, the lithium battery will have safety risks. For example, the power protection scheme of some notebooks determines whether it is necessary to start the power protection by detecting the current between the drain and source of the MOS tube. After starting the power protection, if it is found that the MOS tube is not turned off and there is still current flowing through the source and drain, the secondary battery protection will be performed. However, since the failure of the MOS tube generally starts with the voltage between the gate and the source dropping, and the drain and the source are gradually connected, this protection scheme will only find that the MOS tube has failed when the protection occurs. If the battery does not trigger the protection action, the MOS tube cannot be found to have failed. There may be a safety risk that the user will burn the MOS tube when using a large current. At the same time, if the battery protection is not triggered, the failure of the MOS tube will not be found. Therefore, how to provide a more reliable and safe battery protection circuit has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, one object of the present invention is to provide a reliable and safe protection control circuit for a battery cell.

[0005] To this end, a second object of the present invention is to provide an effective and reliable protection control method for a battery cell.

[0006] The technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a protection control circuit for a battery cell, which includes a main control module, a switch control module, a charge and discharge control module and an input and output interface; wherein the battery cell is connected to the switch control module, the switch control module is connected to the input and output interface, the battery cell is connected to the charge and discharge control module, the charge and discharge control module is connected to the input and output interface, the output end of the charge and discharge control module is connected to the input end of the main control module to input a detection voltage, and the output end of the main control module is connected to the input end of the switch control module to switch the working state of the switch control module according to the detection voltage.

[0008] Furthermore, the charging and discharging module includes a lithium battery protection chip, a charging control switch tube and a discharging control switch tube; the switch control module is respectively connected to the power input end of the lithium battery protection chip and the positive input and output ends of the input and output interface, the charging protection control end of the lithium battery protection chip is connected to the control end of the charging control switch tube, the discharging protection control end of the lithium battery protection chip is connected to the control end of the discharging control switch tube, the negative pole of the battery cell is connected to the negative output end of the discharging control switch tube, the positive output end of the discharging control switch tube is connected to the positive output end of the charging control switch tube, the negative output end of the charging control switch tube is connected to the negative input and output end of the input and output interface, and the charging protection control end and / or the discharging protection control end are connected to the input end of the main control module to input the detection voltage.

[0009] Furthermore, the charging control switch tube and / or the discharging control switch tube is an NMOS tube, the gate of the NMOS tube is the control end of the switch tube, the source of the NMOS tube is the negative output end of the switch tube, and the drain of the NMOS tube is the positive output end of the switch tube.

[0010] Furthermore, the charge and discharge control module also includes a voltage sampling circuit, which is used to sample the voltage of the control end of the charging control switch tube and / or the control end of the discharging control switch tube as a detection voltage, and the output end of the voltage sampling circuit is connected to the input end of the main control module to input the detection voltage.

[0011] Furthermore, the switch control module includes a three-terminal fuse and a first switch tube; the first end of the three-terminal fuse is connected to the positive pole of the battery cell, the second end of the three-terminal fuse is connected to the positive input and output end of the input and output interface, the third end of the three-terminal fuse is connected to the positive output end of the first switch tube, the control end of the first switch tube is connected to the output end of the main control module, and the negative output end of the first switch tube is grounded.

[0012] Furthermore, the first switch tube is an NMOS tube, the gate of the NMOS tube is the control end of the first switch tube, the source of the NMOS tube is the negative output end of the first switch tube, and the drain of the NMOS tube is the positive output end of the first switch tube.

[0013] Furthermore, the switch control module includes a second switch tube and a third switch tube; the negative output end of the third switch tube is connected to the positive pole of the battery cell, the positive output end of the third switch tube is connected to the positive input and output end of the input-output interface, the control end of the third switch tube is connected to the positive output end of the second switch tube, the control end of the second switch tube is connected to the output end of the main control module, and the negative output end of the second switch tube is grounded.

[0014] Furthermore, the second switch tube is a second NMOS tube, and the third switch tube is a first PMOS tube; the gate of the second NMOS tube is the control end of the second switch tube, the source of the second NMOS tube is the negative output end of the second switch tube, the drain of the second NMOS tube is the positive output end of the second switch tube, the gate of the first PMOS tube is the control end of the third switch tube, the source of the first PMOS tube is the negative output end of the third switch tube, and the drain of the first PMOS tube is the positive output end of the third switch tube.

[0015] In a second aspect, the present invention provides a protection control method for a battery cell, which is applied to the protection control circuit of the battery cell, and comprises the following steps:

[0016] The charge and discharge control module outputs the detection voltage to the main control module;

[0017] The main control module compares the received detection voltage with a set voltage threshold;

[0018] The main control module switches the working state of the switch control module according to the comparison result.

[0019] Furthermore, the voltage sampling circuit samples the voltage at the control end of the charging control switch tube and / or the control end of the discharging control switch tube as the detection voltage; the main control module compares the detection voltage with the voltage threshold to switch the working state of the switch control module.

[0020] The beneficial effects of the present invention are:

[0021] The present invention provides a protection control circuit for a battery cell. The output end of a charge and discharge control module is connected to the input end of a main control module, and the output end of the main control module is connected to the input end of a switch control module. The main control module further controls whether to trigger the switch control module to work according to a signal collected from the charge and discharge control module, so that the battery cell stops charging or discharging. The present invention solves the technical problems in the prior art that the protection circuit of the battery cell is unreliable and has potential safety hazards, and provides a reliable and safe protection control circuit for the battery cell.

[0022] Another beneficial effect of the present invention is:

[0023] A protection control method for a battery cell in the present invention is applied to the protection control circuit of the battery cell. A main control module makes a judgment based on a signal received from a charge and discharge control module to control the working state of the switch control module. The technical problems of a high failure probability and poor reliability of the protection control method for a battery cell in the prior art are solved, and an effective and reliable protection control method for a battery cell is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a module block diagram of a specific embodiment of a protection control circuit of a battery cell in the present invention;

[0025] Figure 2 It is a circuit schematic diagram of a specific embodiment of a protection control circuit for a battery cell in the present invention;

[0026] Figure 3 It is a flow chart of a specific embodiment of a protection control method for a battery cell in the present invention.

[0027] Among them, CELL is a battery cell, F1 is a three-terminal fuse, D1 is the first diode, Q1 is the first NMOS tube, Q3 is the third NMOS tube, Q4 is the fourth NMOS tube, R1 is the first resistor, R2 is the second resistor, R3 is the third resistor, R4 is the third voltage-dividing resistor, R5 is the fourth voltage-dividing resistor, R6 is the first voltage-dividing resistor, R7 is the second voltage-dividing resistor, C1 is the first capacitor, U1 is a lithium battery protection chip, U2 is an MCU, P+ is the positive connection terminal, and P- is the negative connection terminal. DETAILED DESCRIPTION

[0028] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0029] like Figure 1 As shown, a protection control circuit of a battery cell in the present invention includes a main control module, a switch control module, a charge and discharge control module, an input and output interface, and a battery cell; wherein the positive electrode of the battery cell is connected to the switch control module, the switch control module is connected to the input and output interface, the negative electrode of the battery cell is connected to the charge and discharge control module, the charge and discharge control module is connected to the input and output interface, the output end of the charge and discharge control module is connected to the input end of the main control module, and the output end of the main control module is connected to the input end of the switch control module. The main control module further controls whether to switch the working state of the switch control module according to the signal collected from the charge and discharge control module, so that the battery cell stops charging or discharging, and provides a reliable and safe protection control circuit for the battery cell.

[0030] like Figure 3 As shown, a protection control method of a battery cell in the present invention is applied in the protection control circuit of the battery cell, comprising the following steps:

[0031] The charge and discharge control module outputs the detection voltage to the main control module;

[0032] The main control module compares the received detection voltage with a set voltage threshold;

[0033] The main control module switches the working state of the switch control module according to the comparison result.

[0034] The detection voltage is obtained by sampling the voltage of the control end of the charge control switch tube and / or the control end of the discharge control switch tube through the voltage sampling circuit, and the main control module compares the detection voltage with the set voltage threshold to switch the working state of the switch control module. The main control module makes a judgment based on the signal received from the charge and discharge control module to control the opening and closing of the switch control module; the technical problem of the high failure probability and poor reliability of the protection control method of the battery cell in the prior art is solved, and an effective and reliable protection control method for the battery cell is provided.

[0035] Embodiment 1:

[0036] A protection control circuit for a battery cell in the present invention comprises a charge and discharge control module comprising a lithium battery protection chip, a charge control switch tube, a discharge control switch tube and a voltage sampling circuit, wherein the voltage sampling circuit comprises a first voltage sampling circuit for sampling the voltage of the control end of the charge control switch tube and / or a second voltage sampling circuit for sampling the voltage of the control end of the discharge control switch tube, wherein the first voltage sampling circuit comprises a first voltage dividing resistor and a second voltage dividing resistor, wherein the second sampling circuit comprises a third voltage dividing resistor and a fourth voltage dividing resistor, wherein the switch control module comprises a three-terminal fuse and a first switch tube, wherein the main control module is an MCU, wherein the discharge control switch tube, the charge control switch tube and the first switch tube are all NMOS tubes, wherein the gate of the NMOS tube is the control end, the source of the NMOS tube is the negative output end, and the drain of the NMOS tube is the positive output end.

[0037] Specifically, Figure 2As shown, a protection control circuit of a battery cell in the present invention includes: a battery cell CELL, a three-terminal fuse F1, a first diode D1, a first NMOS tube Q1 (first switch tube), a first resistor R1, a second resistor R2, a first capacitor C1, a lithium battery protection chip U1, a main control module U2, a third resistor R3, a first voltage-dividing resistor R6, a second voltage-dividing resistor R7, a third voltage-dividing resistor R4, a fourth voltage-dividing resistor R5, a third NMOS tube Q3 (discharge control switch tube), a fourth NMOS tube Q4 (charge control switch tube), a positive connection terminal P+ (positive input and output terminal of the input and output interface) and Negative connection terminal P- (negative input and output terminal of the input and output interface); wherein, the first end of the three-terminal fuse F1 is connected to the positive electrode of the battery cell CELL, the second end of the three-terminal fuse F1 is respectively connected to the positive connection terminal P+, one end of the first resistor R1, and the power input terminal of the main control module U2, the third end of the three-terminal fuse F1 is connected to the drain of the first NMOS tube Q1 and the cathode of the first diode D1, the other end of the first resistor R1 is respectively connected to the power input terminal VDD of the lithium battery protection chip U1 and one end of the first capacitor C1, the source of the first NMOS tube Q1 is respectively connected to the anode of the first diode D1, the cathode of the battery cell CELL, and the cathode of the first diode D1. The negative electrode of CELL, one end of the second resistor R2, the other end of the first capacitor C1, the VSS port of the lithium battery protection chip U1, and the source of the third NMOS tube Q3 are connected to a common ground, the gate of the first NMOS tube Q1 is respectively connected to the other end of the second resistor R2 and the output end IO1 of the main control module U2, the discharge control output end DO of the lithium battery protection chip U1 is respectively connected to the gate of the third NMOS tube Q3 and one end of the third voltage-dividing resistor R4, the other end of the third voltage-dividing resistor R4 is respectively connected to one end of the fourth voltage-dividing resistor R5 and the first input end IO2 of the main control module, and the fourth voltage-dividing resistor R 5 is grounded, the charging control output terminal CO of the lithium battery protection chip U1 is respectively connected to the gate of the fourth NMOS tube Q4 and one end of the first voltage-dividing resistor R6, the other end of the first voltage-dividing resistor R6 is respectively connected to one end of the second voltage-dividing resistor R7 and the second input terminal IO3 of the main control module, the other end of the second voltage-dividing resistor R7 is grounded, the drain of the third NMOS tube Q3 is connected to the drain of the fourth NMOS tube Q4, the source of the fourth NMOS tube Q4 is respectively connected to one end of the third resistor R3 and the negative connection terminal P-, and the other end of the third resistor R3 is connected to the VM pin of the lithium battery protection chip U1.

[0038] The process of a protection control circuit of a battery cell in the present invention is as follows:

[0039] 1. Discharge protection process:

[0040] Reference Figure 2During the discharge process of the battery cell CELL, the discharge control output terminal DO of the lithium battery protection chip U1 works, the third NMOS tube Q3 is turned on, and the fourth NMOS tube Q4 is turned off. Under normal circumstances, the voltage of the power input terminal VDD of the lithium battery protection chip U1 is the voltage value when the battery cell CELL is discharged. The discharge control output terminal DO of the lithium battery protection chip U1 outputs the same voltage value as the power input terminal VDD of the lithium battery protection chip U1, and the battery cell CELL continues to discharge; however, when the battery cell CELL is over-discharged, the power input terminal VDD of the lithium battery protection chip U1 decreases, causing the discharge control output terminal DO of the lithium battery protection chip U1 to output less than the battery cell CE LL standard voltage value, the voltage signal output by the discharge control output terminal DO of the lithium battery protection chip U1 is divided by the third voltage-dividing resistor R4 and the fourth voltage-dividing resistor R5 (the third voltage-dividing resistor R4 and the fourth voltage-dividing resistor R5 are resistors with the same resistance value) and transmitted to the MCU. At this time, the voltage signal received by the MCU is less than half of the standard voltage of the battery cell CELL. After receiving the signal less than half of the standard voltage of the battery cell CELL, the MCU outputs a low level to the gate of the first NMOS tube Q1. At this time, the first NMOS tube Q1 is turned off and the three-terminal fuse F1 is blown, which safely and reliably prevents the battery cell CELL from being over-discharged and thus causing the possibility of damage to the battery cell CELL.

[0041] 2. Charging protection process:

[0042] Reference Figure 2 During the charging process of the battery cell CELL, the charging control output terminal CO of the lithium battery protection chip U1 works, the third NMOS tube Q3 is turned off, and the fourth NMOS tube Q4 is turned on. Under normal circumstances, the voltage of the power input terminal VDD of the lithium battery protection chip U1 is the charging voltage (that is, the standard voltage of the battery cell CELL), and the charging control output terminal CO of the lithium battery protection chip U1 outputs the same voltage value as the power input terminal VDD of the lithium battery protection chip U1, and the battery cell CELL continues to charge; however, when the battery cell CELL is overcharged, the power input terminal VDD of the lithium battery protection chip U1 inputs a higher voltage than the standard, causing the charging control output terminal CO of the lithium battery protection chip U1 to output The voltage signal output by the charging control output terminal CO of the lithium battery protection chip U1 is greater than the standard voltage value of the battery cell. After being divided by the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7 (the first voltage-dividing resistor R6 and the second voltage-dividing resistor R7 are resistors of the same resistance value), the voltage signal received by the MCU is greater than half of the standard voltage of the battery cell. After receiving the signal greater than half of the standard voltage of the battery cell, the MCU outputs a low level to the gate of the first NMOS tube Q1. At this time, the first NMOS tube Q1 is turned off and the three-terminal fuse F1 is blown, thereby safely and reliably preventing the battery cell from being overcharged and causing damage to the battery cell.

[0043] Embodiment 2:

[0044] The present invention discloses a protection control circuit for a battery cell, wherein the switch control module includes a second switch tube and a third switch tube, wherein the second switch tube is a second NMOS tube, and the third switch tube is a first PMOS tube; specifically, the source of the first PMOS tube is connected to the positive electrode of the battery cell, the drain of the first PMOS tube is respectively connected to the positive connection terminal P+, one end of the first resistor R1, and the power input terminal of the main control module U2, the gate of the first PMOS tube is respectively connected to the drain of the second NMOS tube and the cathode of the first diode D1, the gate of the second NMOS tube is respectively connected to the other end of the second resistor R2, the output terminal of the main control module U2 IO1 is connected, the source of the second NMOS tube is respectively connected to the anode of the first diode D1, the cathode of the battery cell CELL, one end of the second resistor R2, the other end of the first capacitor C1, the VSS port of the lithium battery protection chip U1, and the source of the third NMOS tube Q3, and then they are connected to a common ground. Its circuit structure and charging and discharging protection process are basically the same as those in the above-mentioned embodiment 1, except that the protection mechanism of turning off the first NMOS tube Q1 and blowing the three-terminal fuse F1 is converted into a method of turning off the second NMOS tube and turning off the first PMOS tube to protect the battery cell CELL during the charging and discharging process, which will not be described in detail here.

[0045] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A protection control circuit for a battery cell, characterized in that: It includes a main control module, a switch control module, a charge and discharge control module and an input and output interface; the battery cell is connected to the switch control module, the switch control module is connected to the input and output interface, the battery cell is connected to the charge and discharge control module, the charge and discharge control module is connected to the input and output interface, the output end of the charge and discharge control module is connected to the input end of the main control module to input a detection voltage, and the output end of the main control module is connected to the input end of the switch control module to switch the working state of the switch control module according to the detection voltage; The charge and discharge control module includes a lithium battery protection chip, a charge control switch tube and a discharge control switch tube; the switch control module is respectively connected to the power input end of the lithium battery protection chip and the positive input and output end of the input-output interface, the charge protection control end of the lithium battery protection chip is connected to the control end of the charge control switch tube, the discharge protection control end of the lithium battery protection chip is connected to the control end of the discharge control switch tube, the negative electrode of the battery cell is connected to the negative output end of the discharge control switch tube, the positive output end of the discharge control switch tube is connected to the positive output end of the charge control switch tube, the negative output end of the charge control switch tube is connected to the negative input and output end of the input-output interface, and the charge protection control end and / or the discharge protection control end are connected to the input end of the main control module to input the detection voltage; The charge and discharge control module also includes a voltage sampling circuit, which is used to sample the voltage of the control end of the charge control switch tube and / or the control end of the discharge control switch tube as the detection voltage, and the output end of the voltage sampling circuit is connected to the input end of the main control module to input the detection voltage.

2. The protection control circuit of the battery cell according to claim 1, characterized in that: The charging control switch tube and / or the discharging control switch tube is an NMOS tube, the gate of the NMOS tube is the control end of the switch tube, the source of the NMOS tube is the negative output end of the switch tube, and the drain of the NMOS tube is the positive output end of the switch tube.

3. The protection control circuit of the battery cell according to any one of claims 1 to 2, characterized in that: The switch control module includes a three-terminal fuse and a first switch tube; the first end of the three-terminal fuse is connected to the positive electrode of the battery cell, the second end of the three-terminal fuse is connected to the positive input and output end of the input and output interface, the third end of the three-terminal fuse is connected to the positive output end of the first switch tube, the control end of the first switch tube is connected to the output end of the main control module, and the negative output end of the first switch tube is grounded.

4. The protection control circuit of the battery cell according to claim 3, characterized in that: The first switch tube is an NMOS tube, the gate of the NMOS tube is the control end of the first switch tube, the source of the NMOS tube is the negative output end of the first switch tube, and the drain of the NMOS tube is the positive output end of the first switch tube.

5. The protection control circuit of the battery cell according to any one of claims 1 to 2, characterized in that: The switch control module includes a second switch tube and a third switch tube; the negative output end of the third switch tube is connected to the positive electrode of the battery cell, the positive output end of the third switch tube is connected to the positive input and output end of the input-output interface, the control end of the third switch tube is connected to the positive output end of the second switch tube, the control end of the second switch tube is connected to the output end of the main control module, and the negative output end of the second switch tube is grounded.

6. The protection control circuit of the battery cell according to claim 5, characterized in that: The second switch tube is a second NMOS tube, and the third switch tube is a first PMOS tube; the gate of the second NMOS tube is the control end of the second switch tube, the source of the second NMOS tube is the negative output end of the second switch tube, the drain of the second NMOS tube is the positive output end of the second switch tube, the gate of the first PMOS tube is the control end of the third switch tube, the source of the first PMOS tube is the negative output end of the third switch tube, and the drain of the first PMOS tube is the positive output end of the third switch tube.

7. A protection control method for a battery cell, characterized in that: The protection control circuit applied to the battery cell according to any one of claims 1 to 6 comprises the following steps: The charge and discharge control module outputs the detection voltage to the main control module; The main control module compares the received detection voltage with a set voltage threshold; The main control module switches the working state of the switch control module according to the comparison result.

8. The protection control method of the battery cell according to claim 7, characterized in that: The voltage sampling circuit samples the voltage of the control end of the charging control switch tube and / or the control end of the discharging control switch tube as the detection voltage; The main control module compares the detection voltage with the voltage threshold to switch the working state of the switch control module.

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