Railway vehicle lithium battery emergency power supply system

Abstract

The utility model discloses an emergency power supply system for a lithium battery of a railway vehicle. The emergency power supply system comprises an emergency battery pack, a charger and a power-on switch, the emergency battery pack comprises at least one battery pack, the battery pack is provided with a plurality of lithium battery monomers connected into a battery module, a battery pack control system, a first series connection part, a second series connection part, a third series connection part and a fourth series connection part, the charger comprises a charging module used for outputting direct-current power supply voltage, and the battery pack control system adopts a three-stage structure. The system can ensure that the emergency power supply system safely and reliably supplies power to the railway vehicle; safe and reliable charging of the lithium battery pack is ensured; the effective capacity of the lithium battery pack is improved; meanwhile, the problem that the lithium battery is not suitable for long-time floating charge is solved, the circuit structure is simple, and fault positioning, maintenance and replacement are facilitated.

Description

Technical Field

[0001] The utility model relates to a lithium battery emergency power supply system for railway vehicles. Background Art

[0002] As an important energy storage device for railway vehicles, the emergency battery provides emergency electric energy for the vehicle when there is no high-voltage power supply. Emergency power supply includes equipment control power supply, emergency lighting power supply, air-conditioning emergency ventilation power supply, emergency traction power supply, etc. At present, lead-acid batteries or nickel-chromium batteries are generally used for emergency batteries of domestic railway vehicles. However, due to their low energy density and short single-cell cycle life, lead-acid batteries or nickel-chromium batteries can no longer meet the increasing requirements for emergency power consumption, service life, and intelligence of railway vehicles. The energy density and single-cell cycle life of lithium batteries are much higher than those of lead-acid batteries or nickel-chromium batteries. Therefore, lithium batteries are gradually being used as emergency batteries on railway vehicles.

[0003] When lead-acid batteries or nickel-chromium batteries are used as emergency batteries for railway vehicles, their charging method generally adopts a method of constant current first, then constant voltage, and finally floating charge. If the same charging method is used for lithium batteries, long-term floating charge will cause continuous chemical reactions inside the battery, and the positive and negative electrode materials of the lithium battery will gradually become inactivated, reducing the capacity and service life of the lithium battery. At the same time, continuous floating charge is likely to cause safety hazards due to floating charge of the lithium battery.

[0004] In the case of low temperature, the charging capacity and discharge capacity of lithium batteries are significantly reduced compared with those at normal temperature, and corresponding measures need to be taken to improve the charge and discharge capacity of lithium batteries. Content of the Utility Model

[0005] The utility model provides a lithium battery emergency power supply system for railway vehicles and its charge and discharge control method.

[0006] The technical solution of the utility model is as follows: A lithium battery emergency power supply system for railway vehicles includes: an emergency battery pack, a charger, and a power-on switch;

[0007] The emergency battery pack includes at least 1 battery pack. The battery pack has a plurality of lithium battery monomers connected into a battery module, a battery pack control system, a first series part, a second series part, a third series part, and a fourth series part. The charger includes a charging module for outputting a DC power supply voltage;

[0008] The battery pack control system and the power-on switch are connected in series, and both ends of the formed series part are respectively connected to the positive electrode and the negative electrode of the corresponding battery module;

[0009] The first series connection part includes a total current transmitter and a charge and discharge contactor connected in series. Two ends of the first series connection part are respectively connected to a first pole of the positive and negative electrodes of a corresponding battery module and a first end of the positive and negative output terminals of the charging module;

[0010] The second series connection part includes a heating element and a heating contactor connected in series. Two ends of the second series connection part are respectively connected to a first pole of the positive and negative electrodes of a corresponding battery module and a second end of the positive and negative output terminals of the charging module;

[0011] The third series connection part includes a charging contactor and a first diode connected in series. Two ends of the third series connection part are respectively connected to a second pole of the positive and negative electrodes of a corresponding battery module and a second end of the positive and negative output terminals of the charging module. The first diode allows the current in the third series connection part to flow unidirectionally to charge the battery module;

[0012] The fourth series connection part includes a discharge contactor and a second diode connected in series. Two ends of the fourth series connection part are respectively connected to a second pole of the positive and negative electrodes of a corresponding battery module and a second end of the positive and negative output terminals of the charging module. The second diode allows the current in the fourth series connection part to flow unidirectionally to discharge the battery module to the outside;

[0013] The railway vehicle lithium battery emergency power supply system further includes: a total voltage transmitter connected between the positive and negative electrodes of the battery module;

[0014] The railway vehicle lithium battery emergency power supply system further includes: a single cell temperature transmitter and a single cell voltage transmitter corresponding one by one to the lithium battery cells in the corresponding battery module. The single cell temperature transmitter is used to measure the temperature of the corresponding lithium battery cell, and the single cell voltage transmitter is used to measure the voltage of the corresponding lithium battery cell;

[0015] The battery pack control system includes a BMS slave controller, a BMS master controller and a BMS total controller connected in parallel; the BMS slave controller is communicatively connected with the BMS master controller through a bus (such as a CAN bus), the BMS master controller is communicatively connected with the BMS total controller through a bus (such as a CAN bus), the BMS total controller is connected with the charger through a bus (such as an Ethernet bus), the total voltage transmitter and the total current transmitter are connected with the BMS master controller, and the single cell temperature transmitter and the single cell voltage transmitter are connected with the BMS slave controller.

[0016] These transmitters output analog current signals or analog voltage signals, and corresponding digital quantities are obtained through analog-to-digital conversion by the corresponding BMS.

[0017] The lithium battery cells in the battery module are connected in series and parallel to provide greater current driving ability and expected output voltage.

[0018] If the first pole of the positive and negative electrodes of the battery module is, for example, the negative electrode and the second pole is the positive electrode, then the first terminal of the positive and negative output terminals of the charging module is the negative output terminal and the second terminal is the positive output terminal.

[0019] If the second pole of the positive and negative electrodes of the battery module is, for example, the negative electrode and the first pole is the positive electrode, then the second terminal of the positive and negative output terminals of the charging module is the negative output terminal and the first terminal is the positive output terminal.

[0020] Optionally, the first series part and the second series part are connected to the first pole of the positive and negative electrodes of the battery module through a fuse; and / or, the third series part, the fourth series part and the series part where the battery pack control system is located are connected to the second pole of the positive and negative electrodes of the battery module through a fuse.

[0021] That is, the fuse can be connected to the negative electrode of the battery module or to the positive electrode of the battery module. The fuse protects the battery module from being burned out due to overcurrent.

[0022] Optionally, the second series part further includes a fuse connected in series with the heating element. This is to prevent overcurrent in the circuit when the heating element heats the battery module.

[0023] Optionally, the number of battery packs is multiple, and each BMS master controller is communicatively connected to all BMS master controllers through a bus.

[0024] Optionally, the charger further includes a current transmitter, and the second terminal of the positive and negative output terminals of the charging module is connected to each battery pack through the current transmitter of the charger. The current transmitter is used to detect the charging current of the charger.

[0025] Optionally, the charger further includes a voltage transmitter, and both ends of the voltage transmitter of the charger are respectively connected to the positive and negative output terminals of the charging module. The voltage transmitter is used to detect the output voltage of the charger.

[0026] Optionally, the charger further includes a diode, and the second terminal of the positive and negative output terminals of the charging module supplies power to the load through the diode of the charger.

[0027] Optionally, the charger further includes a fuse, and the charging module is connected in series with the fuse of the charger. The fuse in the charger is used for overcurrent protection of the charging module.

[0028] Optionally, a circuit breaker connected in series with the battery pack control system is further included. The circuit breaker controls whether the battery pack control system gets power from the battery module.

[0029] Based on the above circuit structure, the battery pack control system can obtain the voltage information, temperature information of the lithium battery cells, and the output voltage and output current of the battery module, so as to determine whether the current battery module is fully charged. If the battery module is fully charged, the battery pack control system can control the charging contactor to disconnect, thus avoiding floating charge; when the battery pack control system determines that the temperature of the current battery module is too low and charging is required, it can control the charge and discharge contactor and the heating contactor to conduct, so that the first series branch and the second series branch form a current loop with the charging module, and the lithium battery cells are heated through the heating element, thus avoiding too low charging power.

[0030] The first series part, the second series part, the third series part, and the fourth series part achieve different functions through the on-off settings of each contactor, and the circuit structure is simple.

[0031] The 3-level BMS control divides the functions to obtain the minimized replaceable unit, which is beneficial for fault location and also reduces the maintenance cost. That is, only the faulty BMS needs to be replaced. Brief Description of the Drawings

[0032] Figure 1 is the circuit diagram of the railway vehicle lithium battery emergency power supply system according to the embodiment of the present invention.

[0033] Figure 2 is the communication relationship diagram of the railway vehicle lithium battery emergency power supply system according to the embodiment of the present invention. Detailed Embodiment

[0034] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0035] Figure 1 is the circuit diagram of the railway vehicle lithium battery emergency power supply system according to the embodiment of the present invention. Figure 2 is the communication relationship diagram of the railway vehicle lithium battery emergency power supply system according to the embodiment of the present invention.

[0036] In the embodiment of the present invention, the railway vehicle lithium battery emergency power supply system includes an emergency battery pack, a charger, and a power-on switch. In the application state, the railway vehicle lithium battery emergency power supply system is connected to a high-voltage power supply device and a load.

[0037] The high-voltage power supply device provides a high-voltage DC power supply voltage, and the high-voltage power supply device outputs a DC600V (DC500V to DV660V) DC power supply voltage.

[0038] The load includes, for example: the controller of the high-voltage power supply device, the controller of the charger.

[0039] The emergency battery pack includes two battery packs (Battery Pack 1 and Battery Pack 2), and the two battery packs are redundant with each other. Three or more battery packs can also be set in the emergency battery pack, or in extreme cases, one battery pack can also be set in the emergency battery pack. The internal structure and external connection relationship of each battery pack can all refer to Figure 1 the illustrated embodiment. In an actual example, the rated capacity of the emergency battery pack is 120Ah.

[0040] A single battery pack has multiple lithium battery cells, a BMS slave controller, a BMS master controller, a BMS total controller, a heating film, multiple contactors, multiple transmitters, multiple fuses, and multiple diodes.

[0041] Figure 1 The multiple battery symbols shown in represent multiple lithium battery cells. The voltage range of the lithium battery cells is from DC2.5V to DC3.5V. The multiple lithium battery cells are connected in series and parallel to form a battery module, so that the output rated voltage of the battery pack is a DC power supply voltage of DC110V (voltage range DC83V to DC115V).

[0042] The BMS slave controller, the BMS master controller, and the BMS total controller constitute a three-level power management system (battery pack control system). The BMS slave controller, the BMS master controller, and the BMS total controller are three independent battery management systems. In Battery Pack 1, the three are marked as BMS1 slave controller, BMS1 master controller, and BMS1 total controller. In Battery Pack 2, the three are marked as BMS2 slave controller, BMS2 master controller, and BMS2 total controller.

[0043] The BMS slave controller is connected to the cell voltage transmitters (not shown) provided corresponding to the lithium battery cells in the battery pack where it is located, and is used to detect the voltages of the corresponding lithium battery cells; the BMS slave controller also includes cell temperature transmitters (not shown) provided corresponding to the lithium battery cells in the battery pack where it is located, and is used to detect the temperatures of the corresponding lithium battery cells. Referring to Figure 2 , the BMS slave controller is communicatively connected to the BMS master controller in the battery pack where it is located through the CAN bus, and sends the voltage values and temperature values of each lithium battery cell to the BMS master controller.

[0044] The BMS master controller is connected to the total voltage transmitter and the total current transmitter, and is used to detect the total voltage and total current of the battery pack where it is located, and calculate the percentage SOC of the remaining power to the total power of the battery pack where it is located. The total voltage transmitter of Battery Pack 1 is marked as V1, and the total current transmitter is marked as A1. The total voltage transmitter of Battery Pack 2 is marked as V2, and the total current transmitter is marked as A2. The BMS master controller sends the highest voltage of the lithium battery cells, the lowest voltage of the lithium battery cells, the highest temperature of the lithium battery cells, the lowest temperature of the lithium battery cells, the charge and discharge current of the battery pack, the charge and discharge voltage of the battery pack, and the SOC of the battery pack to the BMS total controller in the battery pack where it is located.

[0045] Reference Figure 2 Any one of the BMS master controls is communicatively connected to all BMS master controllers via a CAN bus. Any one of the BMS master controllers is communicatively connected to the charger via an Ethernet bus.

[0046] The information sent by the BMS master controller to the charger includes: the highest voltage of the lithium battery cells in the battery pack where the BMS master controller is located, the lowest voltage of the lithium battery cells, the highest temperature of the lithium battery cells, the lowest temperature of the lithium battery cells, the total current of the battery pack, the total voltage of the battery pack, the SOC of the battery pack, the maximum allowable charging current of the emergency battery pack, the maximum allowable charging voltage of the emergency battery pack, the charging request instruction, the heating request instruction, the charging contactor status, the discharging contactor status, the heating contactor status, and the charge-discharge contactor status.

[0047] Reference Figure 1 The charging contactor of battery pack 1 is marked as KMC1+, the discharging contactor is marked as KMF1+, the heating contactor is marked as KMJR1, and the charge-discharge contactor is marked as KMCF1-. A circuit breaker QF1, fuses FU11, FU12, diodes D11, and D12 are also provided in battery pack 1. The charging contactor of battery pack 2 is marked as KMC2+, the discharging contactor is marked as KMF2+, the heating contactor is marked as KMJR2, and the charge-discharge contactor is marked as KMCF2-. A circuit breaker QF2, fuses FU21, FU22, diodes D21, and D22 are also provided in battery pack 2. Diodes D11 and D21 are the first diodes in the previous text. Diodes D12 and D22 are the second diodes in the previous text. The circuit connection relationships of the two battery packs are the same. The following takes battery pack 1 as an example for detailed description.

[0048] The first diodes in the previous text are diodes D11 and D21, and the second diodes are diodes D12 and D22.

[0049] The BMS1 slave control, BMS1 master control, and BMS1 master controller are connected in parallel (the positive power supply terminals of the three are short-circuited, and the negative power supply terminals of the three are short-circuited), and the three form a first parallel part. The first end of the first parallel part is connected to the negative electrode of the battery module, and the second end of the first parallel part is sequentially connected to the positive electrode of the battery module through a pair of electrodes of the power-on switch, circuit breaker QF1, and fuse FU11.

[0050] One measurement terminal of the total voltage transmitter V1 is connected to the negative electrode of the battery module, and the other measurement terminal is connected to the positive electrode of the battery module through fuse FU11.

[0051] The two measurement terminals of the total current transmitter A1 and the charge-discharge contactor KMCF1- are connected in series to form a first series part. One end of the first series part is connected to the negative electrode of the battery module, and the other end is connected to the negative power supply terminal of the load and the negative output terminal of the charging module.

[0052] The heating film is in the form of a film, wrapping the lithium battery monomer for heating the lithium battery monomer. The heating film can also be replaced by other forms of heating elements, such as resistance wires.

[0053] The heating film, fuse FU12, and heating contactor KMJR1 are connected in series to form a second series part. One end of the second series part is connected to the negative electrode of the battery module, and the other end is connected to the positive power supply terminal of the load through the current transmitter A3 inside the charger.

[0054] The charging contactor KMC1+ and diode D11 are connected in series to form a third series part. The discharging contactor KMF1+ and diode D12 are connected in series to form a fourth series part. The third series part and the fourth series part are connected in parallel to form a second parallel part. The first end of the second parallel part is connected to the positive electrode of the battery module through the fuse FU11, and the second end is connected to the positive power supply terminal of the load through the current transmitter A3 inside the charger. The diode D11 allows current to flow unidirectionally towards the positive electrode of the battery module to charge the battery module. The diode D12 allows current to flow unidirectionally out of the positive electrode of the battery module to enable the battery module to discharge externally.

[0055] The high-voltage power supply device is connected to the charger to provide a DC600V DC power supply voltage for the charger. Inside the charger, the DC600V DC voltage is converted into a DC115V DC power supply voltage, and the DC115V DC power supply voltage is output by the charging module inside the charger.

[0056] Inside the charger, the positive and negative output terminals of the charging module are connected in series with the fuse FU3 to form a fifth series part. The voltage transmitter V3 is connected in parallel with the fifth series part. The end of the fuse FU3 not connected to the charging module is connected to the end of the current transmitter A3 not connected to the second parallel part. The end of the current transmitter A3 not connected to the second parallel part is connected to the positive power supply terminal of the load through the diode D3, and the diode D3 allows current to flow unidirectionally from the current transmitter A3 to the positive power supply terminal of the load.

[0057] Continue to refer to Figure 2 , both the BMS1 master control and the BMS2 master control simultaneously send the information they want to send to the BMS1 overall control and the BMS2 overall control. The information received by the BMS1 overall control and the BMS2 overall control from the BMS1 master control and the BMS2 master control remains the same. The BMS1 overall control and the BMS2 overall control are in hot standby redundancy. One of the BMS1 overall control and the BMS2 overall control serves as the main overall control, and the main overall control conducts information interaction with the charger through the Ethernet bus. When the main overall control fails, the other BMS overall control is upgraded to the main overall control to continue performing the tasks of the main overall control.

[0058] The following introduces the charge and discharge control method.

[0059] (1) Discharge

[0060] ① The staff closes the circuit breakers QF1 and QF2 of each battery, and the staff operates the power-on switch to the [Power On] position. At this time, the electrical energy of the battery module supplies power to the BMS1 slave controller, BMS1 master controller, BMS1 total controller, BMS2 slave controller, BMS2 master controller, and BMS2 total controller through the circuit breakers QF1, QF2, and the power-on switch.

[0061] ② The BMS1 slave controller and the BMS2 slave controller respectively collect the voltage and temperature of the lithium battery monomers through the monomer voltage transmitters (not shown) and monomer temperature transmitters (not shown), and transmit the collected information to the corresponding BMS master controller through the CAN bus.

[0062] ③ The BMS master controller receives the information transmitted by the BMS slave controller, detects the total voltage and total current of the battery pack, judges whether the monomer voltage range, the maximum monomer voltage difference, the monomer temperature range, the maximum single-body temperature difference, and the battery pack voltage meet the requirements, and sends the relevant status and judgment results to the BMS total controller.

[0063] The criteria for the BMS master controller to judge that the discharge requirements are met are as follows:

[0064] a Monomer voltage > 2.5V ∩ Monomer voltage < 3.5V;

[0065] b Maximum monomer voltage difference < 0.5V;

[0066] c Monomer temperature < 60°C;

[0067] d Maximum single-body temperature difference < 20°C;

[0068] e Battery pack voltage > 83V;

[0069] If all of the above 5 conditions are met, the BMS master controller judges that the corresponding battery pack can discharge externally. The above values are only for illustration and can be replaced by other preset values.

[0070] ④ The BMS total controller receives the message that the judgment results of the information transmitted by the BMS master controller all meet the requirements, and the two BMS total controllers respectively control the discharge contactors KMF1+, charge and discharge contactors KMCF1-, discharge contactors KMF2+, and charge and discharge contactors KMCF2- to close.

[0071] ⑤ The positive pole of the lithium battery battery pack supplies power to the load through the fuse FU11 (FU21), discharge contactor KMF1+ (KMF2+), diode D12 (D22), current transmitter A3, and diode D3, and returns to the negative pole of the battery module through the charge and discharge contactor KMCF1- (KMCF2-) and the total current transmitter A1 (A2).

[0072] ⑥When the criterion for the BMS master control to determine that the discharge requirement is not met, the BMS master control controls the disconnection of the discharge contactors KMF1+, the charge and discharge contactors KMCF1-, the discharge contactors KMF2+, and the charge and discharge contactors KMCF2-, and the emergency battery pack stops discharging.

[0073] (2) Charging

[0074] ①The emergency battery pack is in a discharging state and supplies power to the vehicle loads (including the controller of the charger (not shown) and the controller of the high-voltage power supply device (not shown)).

[0075] ②The high-voltage power supply device provides a DC600V power supply for the charger. If the emergency battery pack does not send a charging request, the charger outputs a constant voltage of DC115V. At this time, the charger voltage is higher than the emergency battery pack voltage. Due to the blocking of the diodes D12 and D22, the vehicle loads are powered by the charger at this time.

[0076] ③When the BMS master control detects that the total voltage of the battery pack < 110V ∪ the monomer voltage < 3.3V, it sends a charging request command to the BMS master control through the CAN bus. After receiving the charging instruction request, the BMS master control judges the lithium battery monomer temperature. If the highest monomer temperature < 0°C, the BMS master control sends a heating request command to the charger through the Ethernet bus to execute step ④; if the lowest monomer temperature > 0°C, the BMS master control sends a charging request command to the charger through the Ethernet bus to execute step ⑤. The above temperature values and voltage values can also be replaced with other set values.

[0077] ④The BMS master control controls the heating contactors KMJR1 and KMJR2 to close. After receiving the heating request command, the charger adjusts its output voltage to 115V and keeps it constant, restricting the discharge current not to exceed 24A to prevent the heating film from overheating.

[0078] During heating, the current flows from the positive output terminal of the charging module of the charger through the current transmitter A3, the heating contactors KMJR1 (KMJR2), the fuses FU12 (FU22) to the positive electrode of the heating film, and then from the negative electrode of the heating film through the total current transmitters A1 (A2), the charge and discharge contactors KMCF1- (KMCF2-) back to the negative output terminal of the charging module of the charger.

[0079] During heating, the charger output voltage is higher than the battery module voltage. Due to the blocking of the diodes D12 and D22, the vehicle loads are powered by the charger at this time.

[0080] After heating, when the lowest monomer temperature > 0°C, the BMS master control controls the heating contactors KMJR1 and KMJR2 to disconnect, controls the charging contactors KMC1+ and KMC2+ to close, and sends a charging request command to the charger through the Ethernet bus to execute step ⑤.

[0081] ⑤The BMS master controller controls the charging contactors KMC1+ and KMC2+ to close. After receiving the charging command, the charger adjusts the charging voltage to output a constant current of 24 A until the output voltage reaches DC115 V and maintains the voltage constant.

[0082] During charging, the current flows from the positive output terminal of the charging module of the charger through the current transmitter A3, diodes D11 (D21), charging contactor KMC1+ (KMC2+), fuse FU11 (FU21) to the positive pole of the battery module, and from the negative pole of the battery module through the total current transmitter A1 (A2), charge and discharge contactor KMCF1- (KMCF2-) back to the negative output terminal of the charging module of the charger.

[0083] During charging, the output voltage of the charger is higher than the voltage of the battery module. Due to the blocking of diodes D12 and D22, the vehicle load is powered by the charger at this time.

[0084] ⑥When the output voltage of the charger reaches 115 V, the output voltage remains constant. At this time, the charging current will gradually decrease. When the BMS master controller detects that the charging current < 6 A ∪ the single cell voltage > 3.5 V (this is based on the judgment that the battery pack is fully charged), the two BMS master controllers independently send the charging stop command to the BMS master controller through the CAN bus. After receiving the charging stop command request sent by any one of the BMS master controllers, the BMS master controller transmits the charging stop command to the charger through the Ethernet bus and controls the charging contactors KMC1+ and KMC2+ to open. This is to prevent floating charge. The above values can also be replaced with other set values.

[0085] ⑦After receiving the stop charging command, the charger outputs a constant voltage of DC115 V.

[0086] After stopping charging, the output voltage of the charger is higher than the voltage of the battery module. Due to the blocking of diodes D12 and D22, the vehicle load is powered by the charger.

[0087] Each embodiment in the present utility model is described in a progressive manner. The same or similar parts between each embodiment can be referred to each other, and the key points of each embodiment are the differences from other embodiments.

[0088] The protection scope of the present utility model is not limited to the above embodiments. Obviously, those skilled in the art can make various changes and deformations to the present utility model without departing from the scope and spirit of the present utility model. If these changes and deformations fall within the scope of the claims of the present utility model and its equivalent technologies, the intention of the present utility model also includes these changes and deformations.

Claims

1. A railway vehicle lithium battery emergency power supply system, characterized in that: include: Emergency battery pack, charger, power-on switch; The emergency battery pack includes at least one battery pack, the battery pack having a plurality of lithium battery cells connected into a battery module, a battery pack control system, a first series connection section, a second series connection section, a third series connection section and a fourth series connection section, and the charger includes a charging module for outputting a DC power supply voltage; The battery pack control system and the power-on switch are connected in series, and the two ends of the series connection formed by them are respectively connected to the positive electrode and the negative electrode of the corresponding battery module; The first series connection part includes a total current transmitter and a charge-discharge contactor connected in series, and two ends of the first series connection part are respectively connected to the first electrode of the positive and negative electrodes of the corresponding battery module and the first end of the positive and negative output ends of the charging module; The second series connection part includes a heating element and a heating contactor connected in series, and two ends of the second series connection part are respectively connected to the first electrode of the positive and negative electrodes of the corresponding battery module and the second end of the positive and negative output ends of the charging module; The third series connection part includes a charging contactor and a first diode connected in series, the two ends of the third series connection part are respectively connected to the second electrode of the positive and negative electrodes of the corresponding battery module and the second end of the positive and negative output ends of the charging module, and the first diode allows the current in the third series connection part to flow unidirectionally to charge the battery module; The fourth series connection part includes a discharge contactor and a second diode connected in series, the two ends of the fourth series connection part are respectively connected to the second pole of the positive and negative poles of the corresponding battery module and the second end of the positive and negative output ends of the charging module, and the second diode allows the current in the fourth series connection part to flow unidirectionally so that the battery module discharges externally; The railway vehicle lithium battery emergency power supply system further includes: a total voltage transmitter connected between the positive electrode and the negative electrode of the battery module; The railway vehicle lithium battery emergency power supply system also includes: a cell temperature transmitter and a cell voltage transmitter corresponding to the lithium battery cells in the corresponding battery module, the cell temperature transmitter is used to measure the temperature of the corresponding lithium battery cell, and the cell voltage transmitter is used to measure the voltage of the corresponding lithium battery cell; The battery pack control system includes a BMS slave control, a BMS master control and a BMS master control connected in parallel; the BMS slave control is connected to the BMS master control via bus communication, the BMS master control is connected to the BMS master control via bus communication, the BMS master control is connected to the charger via bus communication, the total voltage transmitter and the total current transmitter are connected to the BMS master control, and the single cell temperature transmitter and the single cell voltage transmitter are connected to the BMS slave control.

2. The railway vehicle lithium battery emergency power supply system according to claim 1, characterized in that: The first series part and the second series part are connected to the first pole among the positive and negative poles of the battery module through a fuse; and / or, the third series part, the fourth series part and the series part where the battery pack control system is located are connected to the second pole among the positive and negative poles of the battery module through a fuse.

3. The railway vehicle lithium battery emergency power supply system according to claim 1, characterized in that: The second series connection further includes a fuse connected in series with the heating element.

4. The railway vehicle lithium battery emergency power supply system according to claim 1, characterized in that: There are multiple battery packs, and each BMS master control is connected to all BMS master controls via bus communication.

5. The railway vehicle lithium battery emergency power supply system according to claim 1, characterized in that: The charger also includes a current transmitter, and the second end of the positive and negative output ends of the charging module is connected to each battery pack through the current transmitter of the charger.

6. The railway vehicle lithium battery emergency power supply system according to claim 1, characterized in that: The charger also includes a voltage transmitter, and two ends of the voltage transmitter of the charger are respectively connected to the positive and negative output ends of the charging module.

7. The railway vehicle lithium battery emergency power supply system according to claim 1, characterized in that: The charger further includes a diode, and the second end of the positive and negative output ends of the charging module supplies power to the load through the diode of the charger.

8. The railway vehicle lithium battery emergency power supply system according to claim 1, characterized in that: The charger also includes a fuse, and the charging module is connected in series with the fuse of the charger.

9. The railway vehicle lithium battery emergency power supply system according to claim 1, characterized in that: Also included is a circuit breaker connected in series with the battery pack control system.

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