A low-side circuit of an electric vehicle lithium battery protection board

Abstract

The present invention relates to the technical field of lithium batteries, specifically to a low-side circuit of an electric vehicle lithium battery protection board that is compatible with one-line-through and CAN communication. It includes a control template, a charge and discharge control circuit, a communication circuit, and a collection circuit. Its characteristic is that the charge and discharge control circuit contains a three-terminal fuse FUSE1. One fuse terminal of the three-terminal fuse FUSE1 is connected to the source electrode of the charging MOS of the charge and discharge control circuit. The other fuse terminal of the three-terminal fuse FUSE1 is connected to the charging port P- / C- of the battery. The control terminal of the three-terminal fuse FUSE1 is used to be connected to the positive electrode B+ of the lithium battery through a first switching circuit. When a fault occurs in the lithium battery, the control module controls the first switching circuit to conduct, a voltage difference is generated between the control terminal and the fuse terminal of the three-terminal fuse, and the three-terminal fuse melts. The cost of this circuit is relatively low, it will not damage the protection board, nor will it affect personal and property safety.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, specifically to a low-side circuit of an electric vehicle lithium battery protection board that is compatible with one-line-through and CAN communication. Background Art

[0002] GB43854-2024 "Safety Technical Specification for Lithium-Ion Batteries for Electric Bicycles" will be officially implemented on November 1, 2024. The specification requires that the battery pack adopt a dual protection design and recharge only after successful mutual recognition with the charger.

[0003] Currently, in traditional BMS systems, three-terminal fuses are generally used in the positive electrode circuit. In the low-side scheme, it is necessary to add the positive power line on the protection board, which will increase the cost. At the same time, locking the positive and negative power lines on the protection board will inevitably cause contact arcing and damage the protection board, and may even affect personal and property safety. Therefore, the existing BMS systems with three-terminal fuses adopt the high-side scheme. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a low-side circuit of an electric vehicle lithium battery protection board, which has a lower cost, will not damage the protection board, and will not affect personal and property safety.

[0005] To solve the above problems, the following technical solutions are provided:

[0006] The low-side circuit of the electric vehicle lithium battery protection board of the present invention includes:

[0007] A control template;

[0008] A charge and discharge control circuit for adaptively connecting to the lithium battery. The control template is adaptively connected to the charge and discharge control circuit, and the control template is used to control the MOS of the charge and discharge control circuit to turn on or off, so as to realize the charge and discharge of the lithium battery;

[0009] A communication circuit for adaptively connecting to the control template to realize external communication;

[0010] An acquisition circuit, adaptively connected to the control template, for acquiring the state information of the lithium battery and transmitting the state information to the control template;

[0011] Its characteristics are that the charge and discharge control circuit contains a three-terminal fuse FUSE1. One fuse terminal of the three-terminal fuse FUSE1 is connected to the source electrode of the charging MOS of the charge and discharge control circuit, and the other fuse terminal of the three-terminal fuse FUSE1 is connected to the charging port P- / C- of the battery. The control terminal of the three-terminal fuse FUSE1 is connected to the positive electrode B+ of the lithium battery through a first switch circuit. When a fault occurs in the lithium battery, the control module controls the first switch circuit to conduct, a voltage difference is generated between the control terminal and the fuse terminal of the three-terminal fuse, and the three-terminal fuse melts;

[0012] The first switch circuit includes an MOS transistor Q31. The drain electrode of the MOS transistor Q31 is connected to the control terminal of the three-terminal fuse, and the source electrode of the MOS transistor Q31 is connected to the positive electrode B+ of the lithium battery; one end of the gate electrode of the MOS transistor Q31 is respectively connected to one end of a capacitor C2, one end of a resistor R59, and one end of a resistor R58. The other ends of the capacitor C2 and the resistor R59 are both connected to the positive electrode B+ of the lithium battery, and the other end of the resistor R58 is connected to the collector electrode of a triode Q32; the base electrode of the triode Q32 is respectively connected to one end of a resistor R56 and one end of a resistor R57. The other end of the resistor R56 is connected to the control module for receiving the FUSE-Control signal generated by the control module. The other end of the resistor 57 and the emitter electrode of the triode Q32 are grounded; when a fault occurs in the lithium battery, the FUSE-Control signal is at a high level, the MOS transistor Q31 conducts, a voltage difference is generated between the control terminal and the fuse terminal of the three-terminal fuse, and the three-terminal fuse melts.

[0013] Among them, the communication circuit contains a one-line communication circuit, and the one-line communication circuit contains isolation optocouplers U7 and U6; the negative electrode of the diode terminal of the isolation optocoupler U7 and the emitter electrode of the triode terminal of the isolation optocoupler U6 are both connected to the ground C- of the external circuit. The positive electrode of the diode terminal of the isolation optocoupler U7 is connected to one end of a resistor R106. The collector electrode of the triode terminal of the isolation optocoupler U6 and the other end of the resistor R106 are both connected to one end of an external resistor. The other end of the external resistor is connected to a 5V power supply, and the end of the external resistor connected to the resistor R106 forms a YXT signal; the collector electrode of the triode terminal of the isolation optocoupler U7 is respectively connected to one end of a resistor R104 and adaptively connected to the control module. The other end of the resistor R104 is connected to a 3.3V power supply. The collector electrode of the triode terminal of the isolation optocoupler U7 sends a YXT_R signal to the control module, and the emitter electrode of the triode terminal of the isolation optocoupler U7 is grounded; the positive electrode of the diode terminal of the isolation optocoupler U6 is connected to one end of a resistor R95. The other end of the resistor R95 is connected to a 3.3V power supply. The negative electrode of the diode terminal of the isolation optocoupler U6 is adaptively connected to the control module for receiving the YXT_T signal generated by the control module.

[0014] The communication circuit includes a CAN communication circuit, and the control module realizes CAN communication through the CAN communication circuit.

[0015] The control module includes a main control unit and a secondary control unit. The main control unit is powered by an auxiliary power supply module, and the secondary control unit is powered by the acquisition circuit. Both the main control unit and the secondary control unit are used to receive the acquisition signals of the signal acquisition circuit; the main control unit is adaptively connected to the secondary control unit. When the main control unit works, the main control unit sends an interrupt signal to the secondary control unit, and the secondary control unit is in a sleep state. The main control unit receives the acquisition signals. When the lithium battery stops standing for 24H, the main control unit enters the sleep state, the auxiliary power supply circuit is disconnected, and the secondary control unit is in the wake-up state, and the secondary control unit receives the acquisition signals.

[0016] The CAN communication circuit is adaptively connected to the secondary control unit, and the secondary control unit is adaptively connected to the auxiliary power supply circuit. The CAN communication circuit sends a CAN_test signal to the secondary control unit. When the charger is not connected, the CAN_test signal is at a high level, and the PWR-1 signal sent by the secondary control unit to the auxiliary power supply circuit is at a low level, and the auxiliary power supply circuit does not work; when the charger is connected, the CAN_test signal is at a low level, and the PWR-1 signal sent by the secondary control unit to the auxiliary power supply circuit is at a high level, and the auxiliary power supply circuit works, and the main control unit is powered on and enters the working state.

[0017] The CAN communication circuit includes an isolation optocoupler U2 and a chip U3 of model CA-IS2062W; the collector of the triode end of the isolation optocoupler U2 is connected to one end of a resistor R19, the other end of the resistor R19 is connected to the power supply VCC, and the collector of the triode end of the isolation optocoupler U2 forms the CAN_test signal; a resistor R26 is connected in series between the CANH pin and the CANL pin of the chip U3, and the CANH pin and the CANL pin of the chip U3 are used to connect to the charger to realize CAN communication; the CANH pin of the chip U3 is connected to one end of a resistor R23, the other end of the resistor R23 is respectively connected to the positive pole of the diode end of the isolation optocoupler U2, and the negative pole of the diode end of the isolation optocoupler U2 is connected to the CANL pin of the chip U3.

[0018] The positive pole of the diode end of the isolation optocoupler U2 is connected to the negative pole of a diode D3, and the negative pole of the diode end of the isolation optocoupler U2 is connected to the positive pole of the diode D3.

[0019] The auxiliary power supply module includes a chip U1. The input end of the chip U1 is connected to the positive electrode B+ of the lithium battery through a second switching circuit, and the output end of the chip U1 is adaptively connected to the main control unit for supplying power to the main control unit. Both the main control unit and the sub-control unit are connected to the second switching circuit. The PWR-1 signal is used to control the second switching circuit. When the PWR-1 signal is at a high level, the second switching circuit is in a conducting state, the chip U1 is powered on to supply power to the main control unit, the main control unit generates a PWR signal at a high level to control the second switching circuit to be in a conducting state, and at the same time, the main control unit generates an interrupt signal to control the sub-control unit to be in a sleep state. When the lithium battery stops standing for a preset time, the main control unit enters a sleep state, the PWR signal and the interrupt signal disappear, the second switching circuit is in an off state, and the sub-control unit starts.

[0020] The second switching circuit includes an MOS transistor Q9 and a triode Q12. The source electrode of the MOS transistor Q9 is respectively connected to one end of a fuse FUSE2, one end of a resistor R36, and the negative electrode of a diode ZD1. The other end of the fuse FUSE2 is used to be connected to the positive electrode B+ of the lithium battery. The other end of the resistor R36 and the positive electrode of the diode ZD1 are connected to the gate of the MOS transistor Q9. The gate of the MOS transistor Q9 is connected to one end of a resistor R39, the other end of the resistor R39 is connected to the collector of the triode Q12, the base of the triode Q12 is respectively connected to one end of a resistor R42 and one end of a resistor R43, the other end of the resistor R43 and the emitter of the triode Q12 are both grounded, and the other end of the resistor R42 is respectively connected to the negative electrodes of a diode D5 and a diode D6. The positive electrode of the diode D5 is used to receive the PWR signal, and the positive electrode of the diode D5 is used to receive the PWR-1 signal.

[0021] Adopting the above solution has the following advantages:

[0022] 1. The three-terminal fuse circuit of the present invention is located on the negative electrode loop, so there is no need to increase the power line of the positive electrode, which greatly reduces the cost. At the same time, the power line of the ineffective locking of the positive electrode on the protection board is protected, thus completely avoiding the situation that the protection board is damaged due to the contact and sparking between the positive and negative power lines, and further not affecting the personal and property safety.

[0023] 2. The one-line communication circuit adopted by the present invention ensures that once a protection is triggered to turn off the charge and discharge MOS through two isolated optocouplers, the battery terminal and the system terminal can no longer achieve direct communication. At the same time, the one-line communication circuit can be used to realize charging after successful mutual recognition with the charger. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the structural topology diagram of the low-side circuit of the lithium battery protection board for electric vehicles of the present invention;

[0025] Figure 2 It is a schematic diagram of the auxiliary power supply circuit in the low-side circuit of the lithium battery protection board for electric vehicles of the present invention;

[0026] Figure 3 It is a schematic diagram of the control template circuit in the low-side circuit of the lithium battery protection board for electric vehicles of the present invention;

[0027] Figure 4 It is a schematic diagram of the first part of the acquisition circuit in the low-side circuit of the lithium battery protection board for electric vehicles of the present invention;

[0028] Figure 5 It is a schematic diagram of the second part of the acquisition circuit in the low-side circuit of the lithium battery protection board for electric vehicles of the present invention;

[0029] Figure 6 It is a schematic diagram of the third part of the acquisition circuit in the low-side circuit of the lithium battery protection board for electric vehicles of the present invention;

[0030] Figure 7 It is a schematic diagram of the one-line-through circuit in the low-side circuit of the lithium battery protection board for electric vehicles of the present invention;

[0031] Figure 8 It is a schematic diagram of the CAN communication circuit in the low-side circuit of the lithium battery protection board for electric vehicles of the present invention;

[0032] Figure 9 It is a schematic diagram of the first part of the charge and discharge control circuit in the low-side circuit of the lithium battery protection board for electric vehicles of the present invention;

[0033] Figure 10 It is a schematic diagram of the second part of the charge and discharge control circuit and the connection schematic diagram of the three-terminal fuse in the low-side circuit of the lithium battery protection board for electric vehicles of the present invention;

[0034] Figure 11 It is a schematic diagram of the Internet of Things communication circuit in the low-side circuit of the lithium battery protection board for electric vehicles of the present invention;

[0035] Figure 12 It is a schematic diagram of the CRG signal detection circuit in the low-side circuit of the lithium battery protection board for electric vehicles of the present invention;

[0036] Figure 13 It is a schematic diagram of the ON signal and ACC signal detection circuit in the low-side circuit of the lithium battery protection board for electric vehicles of the present invention; Detailed implementation manners

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0038] Such as Figures 1-13As shown in the figure, the low-side circuit of the lithium battery protection board of the electric vehicle of the present invention includes an auxiliary power supply circuit, a control template, a charge and discharge control circuit, a communication circuit, and a collection circuit. The auxiliary power supply circuit is connected to the control template and the positive electrode B+ of the lithium battery. The auxiliary power supply circuit converts the voltage of the lithium battery into 3.3V voltage for the control module to use. The control template is connected to the lithium battery and the charge and discharge control circuit. The control template controls the MOS of the charge and discharge control circuit to turn on or off, realizing the charge and discharge of the lithium battery. The communication circuit is adaptively connected to the control template to realize external communication. The collection circuit is connected to the control template. The collection circuit collects the state information of the lithium battery and transmits the state information to the control template.

[0039] As Figure 2 shown, in some possible embodiments, the auxiliary power supply module contains a chip U1 of model H6203L. The chip U1 contains a peripheral circuit for driving its operation. The auxiliary power supply circuit supplies power to the entire protection board circuit. The battery voltage B+ and B- are converted into 5V through a DC-DC buck-type constant voltage and constant current controller H6203L. The 5V voltage supplies power to the CAN communication circuit and the Internet of Things communication circuit. At the same time, the 5V voltage is converted into 3.3V voltage through an LDO to supply power to the single-chip microcomputer. The specific structure of the auxiliary power supply module is as Figure 2 shown, which belongs to the prior art and will not be elaborated here.

[0040] As Figure 3 shown, in some possible embodiments, the control module contains a main control unit and a sub-control unit. The main control unit is a chip U4 of GD32E303C8TB and a peripheral circuit for driving the chip U4. The sub-control unit is a chip IC1B of HR7P153P4SA and a peripheral circuit for driving the chip IC1B. The specific structure is as Figure 4 shown, which belongs to the prior art and will not be elaborated here.

[0041] As Figure 3 、 Figure 9 and Figure 10 shown, in some possible embodiments, the charge and discharge control circuit contains a charge and discharge MOS and a three-terminal fuse FUSE1. The specific structure of the charge and discharge MOS is as Figure 3As shown, it belongs to the prior art and will not be elaborated here. One fuse terminal of the three-terminal fuse FUSE1 is connected to the source electrode of the charging MOS of the charge and discharge control circuit, and the other fuse terminal of the three-terminal fuse FUSE1 is connected to the charging port P- / C- of the battery. The control terminal of the three-terminal fuse FUSE1 is connected to the positive electrode B+ of the lithium battery through the first switch circuit. When a fault occurs in the lithium battery, the chip U4 controls the first switch circuit to conduct, a voltage difference is generated between the control terminal and the fuse terminal of the three-terminal fuse, and the three-terminal fuse blows. The first switch circuit includes an MOS transistor Q31. The drain electrode of the MOS transistor Q31 is connected to the control terminal of the three-terminal fuse, and the source electrode of the MOS transistor Q31 is connected to the positive electrode B+ of the lithium battery. One end of the gate electrode of the MOS transistor Q31 is respectively connected to one end of the capacitor C2, one end of the resistor R59, and one end of the resistor R58. The other ends of the capacitor C2 and the resistor R59 are both connected to the positive electrode B+ of the lithium battery. The other end of the resistor R58 is connected to the collector electrode of the triode Q32. One end of the base electrode of the triode Q32 is respectively connected to one end of the resistor R56 and one end of the resistor R57. The other end of the resistor R56 is connected to the 25th pin of the chip U4 to receive the FUSE-Control signal generated by the chip U4. The other end of the resistor 57 and the emitter electrode of the triode Q32 are grounded. When a fault occurs in the lithium battery, the FUSE-Control signal is at a high level, the MOS transistor Q31 conducts, a voltage difference is generated between the control terminal and the fuse terminal of the three-terminal fuse, and the three-terminal fuse blows. Specifically, the three-terminal fuse circuit is connected between the S pole of the BMS charging MOS and the charging port of the battery. When the BMS is normal, the FUSE-Control outputs a low level, the C pole and the E pole of the NPN triode Q32 are disconnected, the S pole and the G pole voltages of the PMOS Q31 are the same as B+, the D pole and the S pole of the PMOS Q31 are disconnected, there is no voltage difference between the control terminal and the fuse terminal of the three-terminal fuse, and the three-terminal fuse will not blow, and the BMS works normally. When the BMS is abnormal, the FUSE-Control outputs a high level, the C pole and the E pole of the NPN triode Q32 conduct, the S pole-G pole voltage of the PMOS Q31 is greater than the conduction voltage of the PMOS Q31, the D pole and the S pole of the PMOS Q31 conduct, the control terminal of the three-terminal fuse is B+, and there is a voltage difference with the fuse terminal, and the three-terminal fuse blows to achieve the purpose of protection.

[0042] As Figure 3 and Figure 7As shown, in some possible embodiments, the communication circuit includes a single-line communication circuit, and the single-line communication circuit includes isolation optocouplers U7 and U6. The negative electrode of the diode terminal of isolation optocoupler U7 and the emitter of the triode terminal of isolation optocoupler U6 are both connected to the ground C- of the external circuit. The positive electrode of the diode terminal of isolation optocoupler U7 is connected to one end of resistor R106. The collector of the triode terminal of isolation optocoupler U6 and the other end of resistor R106 are both connected to one end of an external resistor, and the other end of the external resistor is connected to a 5V power supply. The end of the external resistor connected to resistor R106 forms the YXT signal. The collector of the triode terminal of isolation optocoupler U7 is respectively connected to one end of resistor R104 and pin 12 of chip U4. The other end of resistor R104 is connected to a 3.3V power supply. The collector of the triode terminal of isolation optocoupler U7 sends the YXT_R signal to chip U4, and the emitter of the triode terminal of isolation optocoupler U7 is grounded. The positive electrode of the diode terminal of isolation optocoupler U6 is connected to one end of resistor R95. The other end of resistor R95 is connected to a 3.3V power supply. The negative electrode of the diode terminal of isolation optocoupler U6 is connected to pin 13 of chip U4, which is used to receive the YXT_T signal generated by chip U4. The single-line communication circuit is for the BMS external single-line communication protocol. Through two isolated optocouplers, it is ensured that once a protection is triggered to turn off the charging and discharging MOS, the battery terminal and the system terminal can no longer directly communicate. The working principle of the single-line communication circuit in this embodiment is as follows: The external signal consists of a 5V and a 2.2K pull-up resistor. When the BMS is not connected to the single-line charger, there is no voltage at the diode terminal of optocoupler U7, the triode terminal is open, and the voltage received at the YXT-R terminal of the single-chip microcomputer is 3.3V high level, and the single-chip microcomputer determines that the single-line charger is not connected. When the single-line charger is connected, there is voltage at the diode terminal of optocoupler U7, the triode terminal is short-circuited, and the voltage received at the YXT-R terminal of the single-chip microcomputer is 0V low level, and the single-chip microcomputer determines that the single-line charger is connected. The YXT-T pin of the single-chip microcomputer outputs a communication protocol of high and low levels. When the YXT-T pin of the single-chip microcomputer outputs a high level, there is no voltage at the diode terminal of optocoupler U6, the triode terminal is open, and the external YXT signal is high level. When the YXT-T pin of the single-chip microcomputer outputs a low level, there is voltage at the diode terminal of optocoupler U6, the triode terminal is short-circuited, and the external YXT signal is low level. The single-chip microcomputer outputs a communication protocol and can communicate with the single-line charger through single-line communication. Among them, when selecting R106, two points need to be ensured. One is that the external 5V passes through the external resistor, R106, and the optocoupler to connect to the ground C- of the external circuit. The resistance value cannot be selected too large to prevent the loop current from being small and the optocoupler U7 from not working. The other is that the resistance value cannot be selected too small. It is necessary to ensure that after the 5V is divided by the external resistor and R106, when YXT outputs a high level at the main single-chip microcomputer output, that is, when the triode terminal of U6 is disconnected, the voltage of YXT is high level. In this embodiment, R106 is 4.7K, and the models of optocouplers U6 and U7 are LTV-217-C-G.

[0043] As Figure 2 、 Figure 3, Figure 4 , Figure 5 and Figure 6 As shown in Figure 4 , Figure 5 and Figure 6 , the main control unit is powered by the auxiliary power supply module, and the secondary control unit is powered by the acquisition circuit. Both the main control unit and the secondary control unit are used to receive the acquisition signals from the signal acquisition circuit. The main control unit is adaptively connected to the secondary control unit. When the main control unit is working, the main control unit sends an interrupt signal to the secondary control unit, and the secondary control unit is in the sleep state. The main control unit receives the acquisition signals. When the lithium battery stops standing still for 24H, the main control unit enters the sleep state, the auxiliary power supply circuit is disconnected, the secondary control unit is in the wake-up state, and the secondary control unit receives the acquisition signals. The auxiliary power supply module contains the chip U1. The input end of the chip U1 is connected to the positive electrode of the lithium battery through the second switch circuit, and the output end of the chip U1 is adaptively connected to the main control unit for powering the main control unit. Both the main control unit and the secondary control unit are connected to the second switch circuit. The PWR-1 signal is used to control the second switch circuit. When the PWR-1 signal is at a high level, the second switch circuit is in the conducting state, the chip U1 is powered to supply power to the main control unit, the main control unit generates a PWR signal at a high level to control the second switch circuit to be in the conducting state, and at the same time the main control unit generates an interrupt signal to control the secondary control unit to be in the sleep state. When the lithium battery stops standing still for the preset time, in this embodiment, the preset time is 24 hours, the main control unit enters the sleep state, the PWR signal and the interrupt signal disappear, the second switch circuit is in the disconnected state, and the secondary control unit starts.

[0044] Specifically, the second switch circuit includes the MOS transistor Q9 and the triode Q12. The source electrode of the MOS transistor Q9 is respectively connected to one end of the fuse FUSE2, one end of the resistor R36 and the negative electrode of the diode ZD1. The other end of the fuse FUSE2 is used to be connected to the positive electrode B+ of the lithium battery. The other end of the resistor R36 and the positive electrode of the diode ZD1 are connected to the gate of the MOS transistor Q9. The gate of the MOS transistor Q9 is connected to one end of the resistor R39, and the other end of the resistor R39 is connected to the collector of the triode Q12. The base of the triode Q12 is respectively connected to one end of the resistor R42 and one end of the resistor R43. The other end of the resistor R43 and the emitter of the triode Q12 are both grounded. The other end of the resistor R42 is respectively connected to the negative electrodes of the diode D5 and the diode D6. The positive electrode of the diode D5 is used to receive the PWR signal, and the positive electrode of the diode D5 is used to receive the PWR-1 signal.

[0045] As Figure 3 and Figure 8As shown, in some possible embodiments, the communication circuit includes a CAN communication circuit, and the control module implements CAN communication through the CAN communication circuit. The CAN communication circuit is adaptively connected to the secondary control unit, and the secondary control unit is adaptively connected to the auxiliary power supply circuit. The CAN communication circuit sends a CAN_test signal to the secondary control unit. When the charger is not connected, the CAN_test signal is at a high level, and the PWR-1 signal sent by the secondary control unit to the auxiliary power supply circuit is at a low level, and the auxiliary power supply circuit does not work. When the charger is connected, the CAN_test signal is at a low level, and the PWR-1 signal sent by the secondary control unit to the auxiliary power supply circuit is at a high level, and the auxiliary power supply circuit works, and the main control unit is powered on and enters the working state. The CAN communication circuit includes an isolation optocoupler U2 and a chip U3 of model CA-IS2062W. The collector of the triode end of the isolation optocoupler U2 is connected to one end of the resistor R19, and the other end of the resistor R19 is connected to the power supply VCC. The collector of the triode end of the isolation optocoupler U2 forms the CAN_test signal. A resistor R26 is connected in series between the CANH pin and the CANL pin of the chip U3. The CANH pin and the CANL pin of the chip U3 are used to connect to the charger to implement CAN communication. The CANH pin of the chip U3 is connected to one end of the resistor R23, and the other end of the resistor R23 is respectively connected to the positive pole of the diode end of the isolation optocoupler U2, and the negative pole of the diode end of the isolation optocoupler U2 is connected to the CANL pin of the chip U3. The positive pole of the diode end of the isolation optocoupler U2 is connected to the negative pole of the diode D3, and the negative pole of the diode end of the isolation optocoupler U2 is connected to the positive pole of the diode D3.

[0046] Specifically, the chip U3 of CA-IS2062W is an isolated CAN communication chip with an internal isolated power supply. The two ends are electrically isolated from each other and cannot interfere with each other, improving the stability of the electrical part and the circuit safety. The CAN communication circuit has a CAN wake-up function, and the specific operation is as follows: When the battery stops standing for 24H, the BMS enters the low-power mode, the auxiliary power supply circuit is disconnected, and the main single-chip microcomputer GD32F303CCT6 supplies power to the auxiliary power supply circuit and does not work. The secondary single-chip microcomputer supplies power to the 3.3V output of DVC1117, and the secondary single-chip microcomputer works. At this time, the charger is not connected to the battery pack, there is no voltage on CANH and CANL, the optocoupler U2 does not work, and the voltage detected by a detection pin CAN-test of the secondary single-chip microcomputer is at a high level. When the charger is connected, there is voltage on CANH and CANL, the optocoupler U2 works, the voltage detected by CAN-test is at a low level, and the PWR-1 pin of the secondary single-chip microcomputer outputs a high level, and the auxiliary power supply circuit works, and the main single-chip microcomputer works.

[0047] In this embodiment, the acquisition circuit includes functions of AFE temperature acquisition, voltage acquisition, and current acquisition. The chip U5 used, with the model of DVC1117 of Jiche, is used to acquire the voltage, temperature, and charge and discharge current of the battery pack. Then, the acquired information is sent to the chip U4 through IIC communication. The specific circuit structure is as Figures 4-6 shown, which belongs to the prior art and will not be elaborated here.

[0048] The communication circuit includes an Internet of Things communication circuit, a CRG signal detection circuit, an ON signal and an ACC signal detection circuit. The specific circuit structure is as Figure 11 , Figure 12 and Figure 13 shown, which belongs to the prior art and will not be elaborated here.

[0049] The charge and discharge control circuit is that the MCU, through the AFE acquisition chip, outputs high and low levels of DSG and CHG to control the on and off of the charge and discharge MOS, thereby controlling the charge and discharge function of the battery.

[0050] This solution is the low-side solution circuit of the lithium battery protection board, adopting a dual protection design. It will charge only after successfully recognizing the charger, conforms to the GB43854-2024 standard, and ensures the personal and property safety of end customers. It has low cost, simple assembly, reduces the locking of power lines on the BMS, effectively prevents the power lines from contacting and sparking during the assembly of the battery and damaging the protection board, and ensures the personal and property safety of employees.

Claims

1. A low-side circuit of a lithium battery protection board for an electric vehicle, comprising: Control templates; A charge and discharge control circuit is adapted to be connected with a lithium battery. The control template is adapted to be connected with the charge and discharge control circuit. The control template is used to control the MOS of the charge and discharge control circuit to turn on or off, thereby realizing the charge and discharge of the lithium battery. Communication circuit, used to adapt and connect with the control template to achieve external communication; A collection circuit, adapted to be connected to the control template, for collecting status information of the lithium battery and transmitting the status information to the control template; It is characterized in that the charge and discharge control circuit contains a three-terminal fuse FUSE1, one fuse end of the three-terminal fuse FUSE1 is connected to the source of the charging MOS of the charge and discharge control circuit, the other fuse end of the three-terminal fuse FUSE1 is connected to the charging port P- / C- of the battery, and the control end of the three-terminal fuse FUSE1 is connected to the positive electrode B+ of the lithium battery through the first switch circuit. When the lithium battery fails, the control module controls the first switch circuit to be turned on, and a pressure difference is generated between the control end and the fuse end of the three-terminal fuse FUSE1, and the three-terminal fuse FUSE1 is blown; the first switch circuit includes a MOS tube Q31, the drain of the MOS tube Q31 is connected to the control end of the three-terminal fuse FUSE1, and the source of the MOS tube Q31 is used to be connected to the positive electrode B+ of the lithium battery; the The gate of the MOS tube Q31 is respectively connected to one end of the capacitor C2, one end of the resistor R59 and one end of the resistor R58, the other ends of the capacitor C2 and the resistor R59 are used to be connected to the positive electrode B+ of the lithium battery, and the other end of the resistor R58 is connected to the collector of the transistor Q32; the base of the transistor Q32 is respectively connected to one end of the resistor R56 and one end of the resistor R57, the other end of the resistor R56 is connected to the control module for receiving the FUSE-Control signal generated by the control module, and the other end of the resistor 57 and the emitter of the transistor Q32 are grounded; when the lithium battery fails, the FUSE-Control signal is high, the MOS tube Q31 is turned on, a voltage difference is generated between the control end and the fuse end of the three-terminal fuse FUSE1, and the three-terminal fuse FUSE1 is blown; The communication circuit contains a one-line circuit, which contains an isolation optocoupler U7 and an isolation optocoupler U6; the cathode of the diode end of the isolation optocoupler U7 and the emitter of the transistor end of the isolation optocoupler U6 are both connected to the ground C- of the external circuit, the anode of the diode end of the isolation optocoupler U7 is connected to one end of the resistor R106, the collector of the transistor end of the isolation optocoupler U6 and the other end of the resistor R106 are both connected to one end of the external resistor, the other end of the external resistor is connected to a 5V power supply, and one end of the external resistor connected to the resistor R106 forms a YXT signal; the isolation optocoupler U7 The collector of the transistor end is respectively adapted to be connected with one end of the resistor R104 and the control module, the other end of the resistor R104 is connected to a 3.3V power supply, the collector of the transistor end of the isolation optocoupler U7 sends a YXT_R signal to the control module, and the emitter of the transistor end of the isolation optocoupler U7 is grounded; the positive electrode of the diode end of the isolation optocoupler U6 is connected to one end of the resistor R95, the other end of the resistor R95 is connected to a 3.3V power supply, and the negative electrode of the diode end of the isolation optocoupler U6 is adapted to be connected with the control module, for receiving the YXT_T signal generated by the control module.

2. The low-side circuit of the electric vehicle lithium battery protection board as claimed in claim 1, characterized in that: The communication circuit includes a CAN communication circuit, and the control module implements CAN communication through the CAN communication circuit.

3. The low-side circuit of the electric vehicle lithium battery protection board as claimed in claim 2, characterized in that: The control module contains a main control unit and a sub-control unit. The main control unit is powered by an auxiliary power supply module, and the sub-control unit is powered by the acquisition circuit. Both the main control unit and the sub-control unit are used to receive acquisition signals from the signal acquisition circuit. The main control unit is adaptively connected to the sub-control unit. When the main control unit is working, the main control unit sends an interrupt signal to the sub-control unit, and the sub-control unit is in a sleep state. The main control unit receives the acquisition signal. When the lithium battery stops standing for 24 hours, the main control unit enters a sleep state, the auxiliary power supply circuit is disconnected, the sub-control unit is in an awake state, and the sub-control unit receives the acquisition signal.

4. The low-side circuit of the electric vehicle lithium battery protection board as claimed in claim 3, characterized in that: The CAN communication circuit is adaptably connected to the sub-control unit, and the sub-control unit is adaptably connected to the auxiliary power supply circuit. The CAN communication circuit sends a CAN_test signal to the sub-control unit. When the charger is not connected, the CAN_test signal is high, the PWR-1 signal sent by the sub-control unit to the auxiliary power supply circuit is low, and the auxiliary power supply circuit does not work; when the charger is connected, the CAN_test signal is low, the PWR-1 signal sent by the sub-control unit to the auxiliary power supply circuit is high, the auxiliary power supply circuit works, and the main control unit is powered on and enters a working state.

5. The low-side circuit of the electric vehicle lithium battery protection board as claimed in claim 4, characterized in that: The CAN communication circuit includes an isolation optocoupler U2 and a chip U3 of model CA-IS2062W; the transistor collector of the isolation optocoupler U2 is connected to one end of a resistor R19, the other end of the resistor R19 is connected to a power supply VCC, and the transistor collector of the isolation optocoupler U2 forms the CAN_test signal; a resistor R26 is connected in series between the CANH pin and the CANL pin of the chip U3, and the CANH pin and the CANL pin of the chip U3 are used to be connected to a charger to realize CAN communication; the CANH pin of the chip U3 is connected to one end of a resistor R23, the other end of the resistor R23 is respectively connected to the positive electrode of the diode end of the isolation optocoupler U2, and the negative electrode of the diode end of the isolation optocoupler U2 is connected to the CANL pin of the chip U3.

6. The low-side circuit of the electric vehicle lithium battery protection board as claimed in claim 5, characterized in that: The anode of the diode of the isolation optocoupler U2 is connected to the cathode of the diode D3 , and the cathode of the diode of the isolation optocoupler U2 is connected to the anode of the diode D3 .

7. The low-side circuit of the electric vehicle lithium battery protection board as claimed in claim 4, characterized in that: The auxiliary power supply module contains a chip U1, the input end of the chip U1 is connected to the positive electrode B+ of the lithium battery through the second switch circuit, and the output end of the chip U1 is adapted to be connected to the main control unit for powering the main control unit; the main control unit and the sub-control unit are both connected to the second switch circuit, and the PWR-1 signal is used to control the second switch circuit. When the PWR-1 signal is at a high level, the second switch circuit is in an on state, and the chip U1 is powered to power the main control unit. The main control unit generates a high-level PWR signal to control the second switch circuit to be in an on state, and at the same time, the main control unit generates an interrupt signal to control the sub-control unit to be in a sleep state. When the lithium battery stops standing for a preset time, the main control unit enters a sleep state, the PWR signal and the interrupt signal disappear, the second switch circuit is in a disconnected state, and the sub-control unit starts.

8. The low-side circuit of the electric vehicle lithium battery protection board as claimed in claim 7, characterized in that: The second switch circuit includes a MOS tube Q9 and a transistor Q12; the source of the MOS tube Q9 is respectively connected to one end of the fuse FUSE2, one end of the resistor R36 and the cathode of the diode ZD1, the other end of the fuse FUSE2 is used to be connected to the positive electrode B+ of the lithium battery, the other end of the resistor R36 and the anode of the diode ZD1 are connected to the gate of the MOS tube Q9; the gate of the MOS tube Q9 is connected to one end of the resistor R39, the other end of the resistor R39 is connected to the collector of the transistor Q12, the base of the transistor Q12 is respectively connected to one end of the resistor R42 and one end of the resistor R43, the other end of the resistor R43 and the emitter of the transistor Q12 are both grounded, the other end of the resistor R42 is respectively connected to the cathode of the diode D5 and the cathode of the diode D6, the anode of the diode D5 is used to receive the PWR signal, and the anode of the diode D5 is used to receive the PWR-1 signal.

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