Multi-protection BMS for explosion-proof forklift

Abstract

The invention discloses a multi-protection BMS (Battery Management System) for an explosion-proof forklift, belongs to the technical field of battery management, and solves the technical problems that a lithium battery BMS of an existing explosion-proof forklift is single in protection mechanism, and redundant protection cannot be formed. The BMS comprises an MCU, a first lithium battery management chip, a second lithium battery management chip, a voltameter chip and an operational amplifier chip; the first lithium battery management chip and the second lithium battery management chip are used for respectively acquiring a first battery cell voltage and a second battery cell voltage of the battery pack, and the average value is taken as an actual battery cell voltage; the first current and the second current of the battery pack are obtained through the voltameter chip and the operational amplifier chip respectively, and the SOC is obtained through current coulomb integral calculation after comparison and calibration. If one lithium battery management chip or one path of current collection fails, the other path of current collection continues to operate, and it is ensured that the explosion-proof forklift can continue to work normally when working in a dangerous environment.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management, and more particularly to a multi-protection BMS for explosion-proof forklifts. Background Art

[0002] As an innovative industrial vehicle, explosion-proof lithium battery forklifts have been widely used in many industries in recent years. They work in dangerous environments such as flammable and explosive environments, so the design of explosion-proof lithium battery forklifts is crucial. Among lithium battery packs, the lithium battery BMS is the most important, and BMS is related to the operation of the entire forklift and various data collection.

[0003] However, the current protection mechanisms of explosion-proof forklift lithium battery BMS are relatively simple and cannot form redundant protection. Summary of the invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art, and an object of the present invention is to provide a multi-protection BMS for explosion-proof forklifts that can perform redundant protection.

[0005] The technical solution of the present invention is: a multi-protection BMS for explosion-proof forklifts, including an MCU, a first lithium battery management chip, a second lithium battery management chip, a power meter chip, and an operational amplifier chip;

[0006] The MCU obtains the first cell voltage of the battery pack through the first lithium battery management chip, and obtains the second cell voltage of the battery pack through the second lithium battery management chip, and compares the first cell voltage with the second cell voltage; if the first lithium battery management chip and the second lithium battery management chip are both normal, the average value of the first cell voltage and the second cell voltage is taken as the actual cell voltage of the battery pack; if only one of the first lithium battery management chip and the second lithium battery management chip is normal, the normal voltage of the first lithium battery management chip and the second lithium battery management chip is taken as the actual cell voltage of the battery pack, and an abnormal alarm message of the battery management chip is issued;

[0007] The MCU obtains the first current of the battery pack through the fuel meter chip, and the MCU obtains the second current of the battery pack through the operational amplifier chip; if the fuel meter chip and the operational amplifier chip are both normal, the first current and the second current are compared and calibrated, and the SOC is calculated using the current coulomb integral; if only one of the fuel meter chip and the operational amplifier chip is normal, the SOC is calculated using the current coulomb integral according to the normal current of the fuel meter chip and the operational amplifier chip, and a current chip abnormality alarm message is issued.

[0008] As a further improvement, the first lithium battery management chip and the second lithium battery management chip are of the same model, the fuel gauge chip is of CS5840, and the operational amplifier chip is of TP5532-SR.

[0009] Furthermore, after measuring the cell voltage of the battery pack with a multimeter, the cell voltage measured by the multimeter is calibrated with the cell voltage collected by the first lithium battery management chip and the second lithium battery management chip through a host computer.

[0010] Furthermore, it also includes a temperature acquisition module, which includes 16 temperature sensors. The MCU uses two CD4051 logic 8-channel analog switches to connect each of the temperature sensors respectively to collect the temperature of each battery cell.

[0011] Furthermore, the MCU generates a temperature curve for each battery cell, and informs the vehicle controller through the communication module what current is most suitable for charging or discharging according to the temperature curve of each battery cell.

[0012] Furthermore, it also includes a release, which is connected in series in the main circuit, and the MCU controls the operation of the release through a release driving circuit.

[0013] Furthermore, it also includes a charging relay, a discharging relay, and a pre-charging relay. The charging relay is connected in series in the charging circuit of the main circuit, the discharging relay is connected in series in the discharging circuit of the main circuit, the pre-charging relay is connected in series with a resistor and then connected in parallel with the discharging relay. The MCU controls the operation of the charging relay, the discharging relay, and the pre-charging relay through a relay driving circuit, and the MCU is connected to the output ends of the charging relay and the discharging relay through a voltage / current detection module.

[0014] Furthermore, it also includes an insulation detection module, and the MCU collects the shell voltage and the voltage of the battery pack through the insulation detection module, and compares them to determine the insulation performance of the battery pack.

[0015] Furthermore, it also includes an onboard isolated power supply, which supplies power to the MCU and the onboard isolated power supply through a power control circuit.

[0016] Further, the power control circuit includes a switch, an optical coupler, a first transistor, a MOS transistor, a third transistor, a fourth transistor, a fifth transistor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a sixth diode, a seventh diode, an eighth diode, a ninth diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a first capacitor, a second capacitor, and a third capacitor;

[0017] One end of the light-emitting electrode of the optocoupler is connected to the DC_OUT_IO output port of the MCU through the sixth diode, and the other end is grounded. One end of the receiving electrode of the optocoupler is respectively connected to the base of the third transistor and one end of the ninth diode through the seventh resistor, the other end of the receiving electrode of the optocoupler is grounded, the other end of the ninth diode and the emitter of the third transistor are connected to the reference voltage, the collector of the third transistor is respectively connected to the base of the first transistor, the base of the fourth transistor, and one end of the eighth resistor through the third resistor, the collector of the first transistor is connected to the reference voltage through the first resistor, the emitter of the first transistor is respectively connected to the emitter of the fourth transistor, one end of the second resistor, and one end of the fourth resistor, the other end of the second resistor is respectively connected to the gate of the MOS tube and one end of the second diode, the source of the MOS tube is respectively connected to the positive pole of the power supply, the first interface, one end of the first capacitor, one end of the first diode, and one end of the fifth resistor, the other end of the first capacitor is grounded, the other end of the eighth resistor, the collector of the fourth transistor, the other end of the fourth resistor, the second second resistor are ... The other end of the transistor, the drain of the MOS tube, one end of the third diode, one end of the fourth diode, and one end of the second capacitor are grounded, the other end of the second capacitor is connected to the other end of the first diode and the other end of the fifth resistor, the other end of the third diode, the other end of the fourth diode, one end of the fifth diode, one end of the sixth diode, one end of the seventh diode, and one end of the eighth diode are commonly connected to the onboard isolated power supply, the other end of the sixth diode and the other end of the eighth diode power the MCU through the third interface, the other end of the fifth diode and the other end of the seventh diode are connected to one end of the twelfth resistor and the positive pole of the power supply through the switch, the other end of the twelfth resistor is respectively connected to one end of the third capacitor, one end of the thirteenth resistor, and the base of the fifth transistor through the ninth diode, the collector of the fifth transistor is respectively connected to the positive pole of the working voltage through the tenth resistor and to the SW_IO input port of the MCU through the eleventh resistor, the other end of the third capacitor, the other end of the thirteenth resistor, and the emitter of the fifth transistor are grounded.

[0018] Beneficial Effects

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) The accuracy of battery cell voltage acquisition is improved, and dual redundant protection of battery voltage is provided. For example, if a battery cell voltage acquisition failure occurs in an explosion-proof forklift operating in a hazardous environment, the explosion-proof forklift can be safely driven out of the hazardous environment.

[0021] (2) The accuracy of current detection is improved, and the error of residual capacity (SOC) is reduced. The conventional SOC error is about 5%, and the method of the present invention reduces the SOC error to less than 2%. At the same time, multiple protections against overcurrent are added to form redundant protection. For example, when an explosion-proof forklift has an overcurrent fault while operating in a dangerous environment, it can also ensure that the explosion-proof forklift can safely leave the dangerous environment.

[0022] (3) By detecting the temperature of each battery cell, it can communicate with the controller and inform the controller or charger through the temperature curve what current is suitable for charging and discharging. Conventional BMS can only cut off the relay through the temperature protection threshold.

[0023] The current solution can always control the temperature of the battery cell within the working range, and minimize the temperature protection caused by the battery cell temperature to cut off the relay. If the battery cell temperature rises frequently, it will affect the service life of the battery cell. The solution of the present invention can greatly increase the service life of the battery cell and is more flexible than conventional BMS in temperature control.

[0024] (4) Ensure the insulation of the battery pack shell through insulation testing. Since explosion-proof forklifts work in flammable and explosive dangerous environments, this function is the most basic protection function of explosion-proof forklifts.

[0025] (5) The power supply of the battery pack is controlled to minimize the power consumption of the battery pack. In standby mode, the BMS can automatically enter the low power consumption mode to reduce the power consumption of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a structural diagram of the present invention;

[0027] Figure 2 is a power control circuit diagram of the present invention;

[0028] Figure 3 This is a circuit diagram of the onboard isolated power supply in the present invention.

[0029] Among them: 1-MCU, 2-first lithium battery management chip, 3-second lithium battery management chip, 4-electricity meter chip, 5-op amp chip, 6-battery pack, 7-temperature acquisition module, 8-communication module, 9-tripper, 10-main circuit, 11-tripper drive circuit, 12-charging circuit, 13-discharging circuit, 14-relay drive circuit, 15-voltage / current detection module, 16-insulation detection module, 17-onboard isolated power supply, 18-alarm device, 19-display screen, 20-shunt. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the specific embodiments in the accompanying drawings.

[0031] See also Figure 1 to Figure 3 A multi-protection BMS for an explosion-proof forklift includes an MCU1, a first lithium battery management chip 2, a second lithium battery management chip 3, a power meter chip 4, and an operational amplifier chip 5.

[0032] The MCU1 obtains the first cell voltage of the battery pack 6 through the first lithium battery management chip 2 , and obtains the second cell voltage of the battery pack 6 through the second lithium battery management chip 3 , and compares the first cell voltage with the second cell voltage.

[0033] If both the first lithium battery management chip 2 and the second lithium battery management chip 3 are normal, the average value of the first cell voltage and the second cell voltage is taken as the actual cell voltage of the battery pack 6. The cell voltages collected by the two battery management chips are compared and averaged by software, and the error is verified to be within 5mV, with high detection accuracy.

[0034] If only one of the first lithium battery management chip 2 and the second lithium battery management chip 3 is normal, the normal voltage of the first lithium battery management chip 2 and the second lithium battery management chip 3 is taken as the actual cell voltage of the battery pack 6, and an abnormal battery management chip alarm message is issued.

[0035] If one of the lithium battery management chips is damaged, the BMS can continue to operate to prevent the forklift from shutting down in a dangerous environment.

[0036] The first lithium battery management chip 2 and the second lithium battery management chip 3 are of the same model. After installation, the cell voltage of the battery pack 6 is measured with a multimeter, and then the cell voltage measured by the multimeter is calibrated with the cell voltage collected by the first lithium battery management chip 2 and the second lithium battery management chip 3 through the host computer.

[0037] MCU1 obtains the first current of the battery pack 6 through the fuel gauge chip 4, and obtains the second current of the battery pack 6 through the operational amplifier chip 5. If the fuel gauge chip 4 and the operational amplifier chip 5 are both normal, the first current and the second current are compared and calibrated, and the SOC is calculated using the current coulomb integral. This makes the SCO more accurate, and the SOC changes more smoothly during the charging and discharging process, without SOC jumps, and can also more accurately collect faults such as overcurrent.

[0038] The electric meter chip 4 and the operational amplifier chip 5 collect current through the shunt 20 .

[0039] The remaining capacity (SOC) of the battery is obtained in two ways. The first is to form redundant protection, and the second is to have higher current accuracy after software processing. At the same time, the error of the remaining capacity (SOC) can be controlled within 2%.

[0040] If only one of the fuel gauge chip 4 and the operational amplifier chip 5 is normal, the SOC is calculated using the current coulomb integral according to the normal current of the fuel gauge chip 4 and the operational amplifier chip 5, and a current chip abnormality alarm message is issued.

[0041] If one current collection channel fails, the other channel will continue to operate, ensuring that the explosion-proof forklift can continue to work normally when working in a hazardous environment.

[0042] In this embodiment, the model of the fuel gauge chip 4 is CS5840, and the model of the operational amplifier chip 5 is TP5532-SR.

[0043] The BMS also includes a temperature acquisition module 7, which includes 16 temperature sensors. The MCU1 uses two CD4051 logic 8-channel analog switches to connect each temperature sensor to collect the temperature of each battery cell. Due to the use of two CD4051 logic 8-channel analog switches, the MCU1 can collect the temperature of the corresponding road through the binary logic combination of three pins, which can greatly save the pin resources of the MCU1.

[0044] MCU1 analyzes the temperature of each circuit through software, creates a temperature curve for each battery cell, and informs the vehicle controller of the most suitable current for charging or discharging based on the temperature curve of each battery cell through communication module 8. That is, the size of the charging or load current is controlled according to the temperature characteristics of the battery cell.

[0045] The BMS also includes a trip unit 9, a charging relay K1, a discharge relay K2, and a pre-charge relay K3. The trip unit 9 is connected in series in the main circuit 10, and the MCU1 controls the operation of the trip unit 9 through the trip unit drive circuit 11. The charging relay K1 is connected in series in the charging circuit 12 of the main circuit 10, the discharge relay K2 is connected in series in the discharge circuit 13 of the main circuit 10, and the pre-charge relay K3 is connected in series with a resistor and connected in parallel with the discharge relay K2. The MCU1 controls the operation of the charging relay K1, the discharge relay K2, and the pre-charge relay K3 through the relay drive circuit 14, and the MCU1 connects the output ends of the charging relay K1 and the discharge relay K2 through the voltage / current detection module 15. The voltage / current detection module 15 adopts the voltage / current detection circuit or voltage / current detection chip of the prior art.

[0046] When the instantaneous current is too large, and the frequent closing and disconnection of the relay may cause the relay to be sucked and damaged, in the case of overcharging or over-discharging, the voltage / current detection module 15 detects whether there is still voltage output at the output end of the relay, or detects whether there is current at the output end of the relay, and disconnects the release by driving the release drive circuit to disconnect the release, so that the main circuit is disconnected. If the explosion-proof forklift is operating in a dangerous environment at this time, the explosion-proof forklift BMS will inform the explosion-proof forklift driver to leave the dangerous area as soon as possible for maintenance through the display of the LCD screen 19 and the alarm device 18. When reaching the safe area, the release is disconnected through the release drive circuit to disconnect the release, so that the main circuit is disconnected. The alarm device 18 can be an alarm light or a buzzer.

[0047] When the BMS detects a primary overcurrent and finds that the relay is still not disconnected, the BMS will drive the tripper to disconnect the main circuit through the tripper drive circuit. For example, if the explosion-proof forklift is in a dangerous working environment, the BMS will inform the driver of the explosion-proof forklift through the LCD display and alarm to leave the dangerous area as soon as possible for maintenance. When reaching the safe area, the tripper will be disconnected through the tripper drive circuit to disconnect the main circuit. When the overcurrent value reaches the secondary overcurrent, if the BMS fails to protect in time, the overcurrent device of the tripper will disconnect the tripper in time to disconnect the main circuit.

[0048] The BMS also includes an insulation detection module 16, which is mainly composed of a high-precision operational amplifier circuit. MCU1 collects the shell voltage of the battery pack 6 and the voltage of the battery pack 6 through the insulation detection module 16, and compares them to determine the insulation performance of the battery pack 6. Since explosion-proof forklifts operate in dangerous environments such as flammable and explosive environments, insulation detection is an important function of explosion-proof forklifts. The present invention solves the previous single protection mechanism of BMS, uses redundant protection, can protect the battery pack in an interlocking manner, and can also allow explosion-proof forklifts to operate more safely in dangerous environments.

[0049] The BMS also includes an onboard isolated power supply 17, which supplies power to the MCU1 and the onboard isolated power supply 17 through a power control circuit. Figure 2 As shown, the power control circuit includes a switch SB, an optical coupler P1, a first transistor Q1, a MOS transistor Q2, a third transistor Q3, a fourth transistor Q4, a fifth transistor Q5, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8, a ninth diode D9, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a first capacitor C1, a second capacitor C2, and a third capacitor C3.

[0050] One end of the light-emitting electrode of the optocoupler P1 is connected to the DC_OUT_IO output port of MCU1 through the sixth diode D6, and the other end is grounded to AGND. One end of the receiving electrode of the optocoupler P1 is respectively connected to the base of the third transistor Q3 and one end of the ninth diode D9 through the seventh resistor R7, and the other end of the receiving electrode of the optocoupler P1 is grounded to MOS_GND. The other end of the ninth diode D9 and the emitter of the third transistor Q3 are connected to the reference voltage MOS_VCC, the collector of the third transistor Q3 is respectively connected to the base of the first transistor Q1, the base of the fourth transistor Q4, and one end of the eighth resistor R8 through the third resistor R3, the collector of the first transistor Q1 is connected to the reference voltage MOS_VCC through the first resistor R1, the emitter of the first transistor Q1 is respectively connected to the emitter of the fourth transistor Q4, one end of the second resistor R2, and one end of the fourth resistor R4, and the other end of the second resistor R2 is respectively connected to MO The gate of the MOS tube Q2, one end of the second diode D2, and the source of the MOS tube Q2 are respectively connected to the positive electrode of the power supply B+, the first interface J1, one end of the first capacitor C1, one end of the first diode D1, and one end of the fifth resistor R5. The other end of the first capacitor C1 is grounded GND. The other end of the eighth resistor R8, the collector of the fourth transistor Q4, the other end of the fourth resistor R4, the other end of the second diode D2, the drain of the MOS tube Q2, one end of the third diode D3, one end of the fourth diode D4, and one end of the second capacitor C2 are grounded MOS_ GND, the other end of the second capacitor C2 is connected to the other end of the first diode D1 and the other end of the fifth resistor R5, the other end of the third diode D3, the other end of the fourth diode D4, one end of the fifth diode D5, one end of the sixth diode D6, one end of the seventh diode D7, and one end of the eighth diode D8 are connected to the onboard isolated power supply 17, the other end of the sixth diode D6 and the other end of the eighth diode D8 supply power to MCU1 through the third interface J3, the other end of the fifth diode D5 and the other end of the seventh diode D7 are connected to one end of the twelfth resistor R12 and connected to the positive electrode B+ of the power supply through the switch SB, the other end of the twelfth resistor R12 is respectively connected to one end of the third capacitor C3, one end of the thirteenth resistor R13, and the base of the fifth transistor Q5 through the ninth diode D9, the collector of the fifth transistor Q5 is respectively connected to the positive electrode of the working voltage +3.3V through the tenth resistor R10 and the SW_IO input port of the MCU1 through the eleventh resistor R11, the other end of the third capacitor C3, the other end of the thirteenth resistor R13, and the emitter of the fifth transistor Q5 are grounded GND.

[0051] The onboard isolated power supply 17 can adopt an existing mature isolated power supply, such as Figure 3 shown.

[0052] This BMS uses a built-in isolated power supply, with a key switch, to power the onboard power module through the power control circuit to activate the microcontroller. After the microcontroller is powered, the control circuit is locked through the IO port. This reduces the external DC-DC power supply and saves production processes. At the same time, when the BMS enters the low power mode, the power consumption can be reduced to less than 30uA.

[0053] The principle of low power workpiece is as follows:

[0054] When B+ is closed by the touch switch SB, the onboard power supply module and MCU1 are powered through diodes D5 and D7. When MCU1 is powered, DC_OUT_IO is set to a high level. At this time, the optocoupler P1 is turned on. When P1 is turned on, the third transistor Q3 is turned on, and the isolated 12V voltage is transmitted to the base of the first transistor Q1. At this time, Q1 is turned on. When Q1 is turned on, the isolated 12V voltage is transmitted to the MOS tube Q2. At this time, the B+ voltage supplies power to the onboard isolated power supply through Q2 and D3 and D4. At this time, the B+ voltage is locked by Q2 to supply power to the onboard isolated power supply.

[0055] If the BMS detects that the standby condition is met, it will control DC_OUT_IO to a low level. At this time, the P1 optocoupler is disconnected, Q3 cannot be turned on, Q4 is connected to the ground through R8, Q4 is turned on, and Q2 is quickly turned off. At this time, the onboard isolated power module cannot obtain power and enters low power consumption mode.

[0056] After the switch SB is closed, Q5 is turned on, and MCU1 can detect the power-on status through the SW_IO input port.

[0057] The above are only preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A multi-protection BMS for an explosion-proof forklift, comprising an MCU (1), characterized in that: It also includes a first lithium battery management chip (2), a second lithium battery management chip (3), a power meter chip (4), and an operational amplifier chip (5); The MCU (1) obtains the first cell voltage of the battery pack (6) through the first lithium battery management chip (2), and the MCU (1) obtains the second cell voltage of the battery pack (6) through the second lithium battery management chip (3), and compares the first cell voltage with the second cell voltage; if both the first lithium battery management chip (2) and the second lithium battery management chip (3) are normal, the average value of the first cell voltage and the second cell voltage is taken as the actual cell voltage of the battery pack (6); if only one of the first lithium battery management chip (2) and the second lithium battery management chip (3) is normal, the normal voltage of the first lithium battery management chip (2) and the second lithium battery management chip (3) is taken as the actual cell voltage of the battery pack (6), and an abnormal alarm message of the battery management chip is issued; The MCU (1) obtains a first current of the battery pack (6) through the fuel gauge chip (4), and the MCU (1) obtains a second current of the battery pack (6) through the operational amplifier chip (5); if the fuel gauge chip (4) and the operational amplifier chip (5) are both normal, the first current and the second current are compared and calibrated, and the SOC is calculated using the current coulomb integral; If only one of the electricity meter chip (4) and the operational amplifier chip (5) is normal, the SOC is calculated using the current coulomb integral according to the normal current of the electricity meter chip (4) and the operational amplifier chip (5), and a current chip abnormality alarm message is issued.

2. A multi-protection BMS for explosion-proof forklifts according to claim 1, characterized in that: The first lithium battery management chip (2) and the second lithium battery management chip (3) are of the same model, the fuel gauge chip (4) is of CS5840 model, and the operational amplifier chip (5) is of TP5532-SR model.

3. A multi-protection BMS for explosion-proof forklifts according to claim 2, characterized in that: The cell voltage of the battery pack (6) is first measured using a multimeter, and then the cell voltage measured by the multimeter is calibrated with the cell voltage collected by the first lithium battery management chip (2) and the second lithium battery management chip (3) through a host computer.

4. A multi-protection BMS for explosion-proof forklifts according to claim 1, characterized in that: It also comprises a temperature acquisition module (7), the temperature acquisition module (7) comprising 16 temperature sensors, and the MCU (1) uses two CD4051 logic 8-channel analog switches to connect the temperature sensors respectively, so as to acquire the temperature of each battery cell.

5. A multi-protection BMS for explosion-proof forklifts according to claim 4, characterized in that: The MCU (1) generates a temperature curve for each battery cell and informs the vehicle controller through the communication module (8) of the most suitable current for charging or discharging based on the temperature curve of each battery cell.

6. A multi-protection BMS for explosion-proof forklifts according to claim 1, characterized in that: It also includes a release (9), which is connected in series in a main circuit (10), and the MCU (1) controls the operation of the release (9) through a release drive circuit (11).

7. A multi-protection BMS for explosion-proof forklifts according to claim 6, characterized in that: The invention also comprises a charging relay (K1), a discharging relay (K2) and a pre-charging relay (K3); the charging relay (K1) is connected in series to a charging circuit (12) of the main circuit (10); the discharging relay (K2) is connected in series to a discharging circuit (13) of the main circuit (10); the pre-charging relay (K3) is connected in series to a resistor and then connected in parallel to the discharging relay (K2); the MCU (1) controls the operation of the charging relay (K1), the discharging relay (K2) and the pre-charging relay (K3) through a relay driving circuit (14); and the MCU (1) is connected to the output ends of the charging relay (K1) and the discharging relay (K2) through a voltage / current detection module (15).

8. The multi-protection BMS for explosion-proof forklift according to claim 1, characterized in that: It also comprises an insulation detection module (16), through which the MCU (1) collects the shell voltage of the battery pack (6) and the voltage of the battery pack (6), and compares them, thereby determining the insulation performance of the battery pack (6).

9. A multi-protection BMS for explosion-proof forklifts according to claim 1, characterized in that: It also includes an onboard isolated power supply (17), which supplies power to the MCU (1) and the onboard isolated power supply (17) through a power control circuit.

10. A multi-protection BMS for explosion-proof forklifts according to claim 9, characterized in that: The power control circuit comprises a switch (SB), an optical coupler (P1), a first transistor (Q1), a MOS transistor (Q2), a third transistor (Q3), a fourth transistor (Q4), a fifth transistor (Q5), a first diode (D1), a second diode (D2), a third diode (D3), a fourth diode (D4), a fifth diode (D5), a sixth diode (D6), a seventh diode (D7), an eighth diode (D8), a ninth diode (D9), a first resistor (R1), a second resistor (R2), a third resistor (R3), a fourth resistor (R4), a fifth resistor (R5), a sixth resistor (R6), a seventh resistor (R7), an eighth resistor (R8), a ninth resistor (R9), a tenth resistor (R10), an eleventh resistor (R11), a twelfth resistor (R12), a thirteenth resistor (R13), a first capacitor (C1), a second capacitor (C2), and a third capacitor (C3); One end of the light-emitting electrode of the optical coupler (P1) is connected to the DC_OUT_IO output port of the MCU (1) through a sixth diode (D6), and the other end is grounded; one end of the receiving electrode of the optical coupler (P1) is respectively connected to the base of the third transistor (Q3) and one end of the ninth diode (D9) through a seventh resistor (R7); the other end of the receiving electrode of the optical coupler (P1) is grounded; the other end of the ninth diode (D9) and the emitter of the third transistor (Q3) are connected to a reference voltage; the collector of the third transistor (Q3) is respectively connected to the base of the first transistor (Q1), the base of the fourth transistor (Q4), and one end of the eighth resistor (R8) through a third resistor (R3); the collector of the first transistor (Q1) is connected to the base of the fourth transistor (Q4) and one end of the eighth resistor (R8) through a seventh resistor (R7); the collector of the first transistor (Q1) is connected to the base of the fourth transistor (Q4) and one end of the eighth resistor (R8) through a seventh resistor (R7); the other end of the receiving electrode of the optical coupler (P1) is grounded; the other end of the ninth diode (D9) and the emitter of the third transistor (Q3) are connected to a reference voltage; the collector of the third transistor (Q3) is respectively connected to the base of the first transistor (Q1), the base of the fourth transistor (Q4), and one end of the eighth resistor (R8) through a third resistor (R3); the collector of the first transistor (Q1) is connected to the base of the fourth transistor (Q4) and one end of the eighth resistor (R8) through a seventh resistor (R7); the other end of the receiving electrode of the optical coupler (P1) is grounded; the other end of the ninth diode (D9) and the emitter of the third transistor (Q3) are connected to a reference voltage; the collector of the third transistor (Q3) is respectively connected to the base of the first transistor (Q1), the base of the fourth transistor The first resistor (R1) is connected to a reference voltage, the emitter of the first triode (Q1) is respectively connected to the emitter of the fourth triode (Q4), one end of the second resistor (R2), and one end of the fourth resistor (R4), the other end of the second resistor (R2) is respectively connected to the gate of the MOS tube (Q2) and one end of the second diode (D2), the source of the MOS tube (Q2) is respectively connected to the positive electrode of the power supply, the first interface (J1), one end of the first capacitor (C1), one end of the first diode (D1), and one end of the fifth resistor (R5), the other end of the first capacitor (C1) is grounded, the other end of the eighth resistor (R8), the collector of the fourth triode (Q4), the other end of the fourth resistor (R4), and the second diode (D2) The other end of the first diode (D1), the drain of the MOS tube (Q2), one end of the third diode (D3), one end of the fourth diode (D4), and one end of the second capacitor (C2) are grounded; the other end of the second capacitor (C2) is connected to the other end of the first diode (D1) and the other end of the fifth resistor (R5); the other end of the third diode (D3), the other end of the fourth diode (D4), one end of the fifth diode (D5), one end of the sixth diode (D6), one end of the seventh diode (D7), and one end of the eighth diode (D8) are connected to the onboard isolated power supply (17); the other end of the sixth diode (D6) and the other end of the eighth diode (D8) are supplied to the MCU (1) through the third interface (J3). The power supply is provided, the other end of the fifth diode (D5) and the other end of the seventh diode (D7) are connected to one end of the twelfth resistor (R12) and connected to the positive electrode of the power supply through the switch (SB), the other end of the twelfth resistor (R12) is respectively connected to one end of the third capacitor (C3), one end of the thirteenth resistor (R13), and the base of the fifth triode (Q5) through the ninth diode (D9), the collector of the fifth triode (Q5) is respectively connected to the positive electrode of the working voltage through the tenth resistor (R10) and connected to the SW_IO input port of the MCU (1) through the eleventh resistor (R11), and the other end of the third capacitor (C3), the other end of the thirteenth resistor (R13), and the emitter of the fifth triode (Q5) are grounded.

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