Railway vehicle lithium battery emergency power supply system and charging and discharging control method thereof

Abstract

The invention discloses a railway vehicle lithium battery emergency power supply system and a charging and discharging control method thereof. The railway vehicle lithium battery 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 and the corresponding charging and discharging control method 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] This invention relates to an emergency power supply system for lithium batteries in railway vehicles and its charging and discharging control method. Background Technology

[0002] Emergency batteries, as crucial energy storage devices in railway vehicles, provide emergency power to the vehicles when there is no high-voltage power supply. Emergency power supply includes power for equipment control, emergency lighting, emergency ventilation for air conditioning, and emergency traction. Currently, domestic railway vehicles generally use lead-acid or nickel-chromium batteries for emergency power. However, due to their low energy density and short cycle life, lead-acid and nickel-chromium batteries are increasingly unable to meet the growing emergency power demands, lifespan requirements, and intelligent features of railway vehicles. Lithium-ion batteries have significantly higher energy density and longer cycle life than lead-acid or nickel-chromium batteries, therefore, lithium-ion batteries are gradually being used as emergency batteries in railway vehicles.

[0003] When lead-acid or nickel-cadmium batteries are used as emergency batteries in railway vehicles, they are typically charged using a constant current followed by a constant voltage charge, and finally a float charge. If lithium batteries are charged using the same method, prolonged float charging will cause continuous chemical reactions inside the battery, gradually deactivating the positive and negative electrode materials and reducing the battery's capacity and lifespan. Furthermore, continuous float charging can easily lead to safety hazards caused by float charging.

[0004] At low temperatures, the charging and discharging capacities of lithium batteries are significantly reduced compared to those at room temperature, necessitating corresponding measures to improve the effective discharge capacity of lithium batteries. Summary of the Invention

[0005] This invention provides an emergency power supply system for lithium batteries in railway vehicles and a charging and discharging control method thereof.

[0006] The technical solution of the present invention is as follows: an emergency power supply system for lithium batteries in railway vehicles, comprising: an emergency battery pack, a charger, and a power-on switch;

[0007] The emergency battery pack includes at least one battery pack, which has multiple lithium battery cells connected to form a battery module, a battery pack control system, a first series section, a second series section, a third series section and a fourth series section, and the charger includes a charging module for outputting DC power supply voltage.

[0008] The battery pack control system and the power-on switch are connected in series, and the two ends of the series connection are respectively connected to the positive and negative terminals of the corresponding battery modules.

[0009] The first series section includes a total current transmitter and a charge / discharge contactor connected in series. The two ends of the first series section are respectively connected to the first terminal of the positive and negative terminals of the corresponding battery module and the first terminal of the positive and negative output terminals of the charging module.

[0010] The second series section includes a heating element and a heating contactor connected in series. The two ends of the second series section are respectively connected to the first terminal of the positive and negative terminals of the corresponding battery module and the second terminal of the positive and negative output terminals of the charging module.

[0011] The third series section includes a charging contactor and a first diode connected in series. The two ends of the third series section are respectively connected to the second terminal of the positive and negative terminals of the corresponding battery module and the second terminal of the positive and negative output terminals of the charging module. The first diode allows the current in the third series section to flow in one direction to charge the battery module.

[0012] The fourth series section includes a discharge contactor and a second diode connected in series. The two ends of the fourth series section are respectively connected to the second terminal of the positive and negative terminals of the corresponding battery module and the second terminal of the positive and negative output terminals of the charging module. The second diode allows the current in the fourth series section to flow in one direction so that the battery module can discharge to the outside.

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

[0014] The railway vehicle lithium battery emergency power supply system also includes: a cell temperature transmitter and a cell voltage transmitter that correspond one-to-one with 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.

[0015] The battery pack control system includes a BMS slave controller, a BMS master controller, and a BMS central controller connected in parallel. The BMS slave controller and the BMS master controller are connected via a bus (e.g., a CAN bus), the BMS master controller and the BMS central controller are connected via a bus (e.g., a CAN bus), the BMS central controller and the charger are connected via a bus (e.g., an Ethernet bus), the total voltage transmitter and the total current transmitter are connected to the BMS master controller, and the individual cell temperature transmitter and the individual cell voltage transmitter are connected to the BMS slave controller.

[0016] These transmitters output analog current or analog voltage signals, which are then converted from analog to digital by the corresponding BMS to obtain the corresponding digital values.

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

[0018] If the first terminal of the battery module is the negative terminal and the second terminal is the positive terminal, then the first terminal of the charging module is the negative output terminal and the second terminal is the positive output terminal.

[0019] If the second terminal of the positive and negative terminals of the battery module is the negative terminal and the first terminal is the positive terminal, 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 section and the second series section are connected to the first terminal of the positive and negative terminals of the battery module via a fuse; and / or, the third series section, the fourth series section, and the series section containing the battery pack control system are connected to the second terminal of the positive and negative terminals of the battery module via a fuse.

[0021] In other words, the fuse can be connected to either the negative or positive terminal of the battery module. The fuse protects the battery module from burning out due to overcurrent.

[0022] Optionally, the second series connection also 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, there are multiple battery packs, and each BMS master controller is connected to the master controller of all BMS via a bus communication connection.

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

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

[0026] Optionally, the charger further includes a diode, and the second 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 to provide overcurrent protection for the charging module.

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

[0029] Furthermore, the present invention also provides a charging and discharging control method for the aforementioned emergency power supply system for lithium batteries in railway vehicles, comprising: the battery pack control system determining whether the emergency battery pack needs charging based on the total voltage detected by the total voltage transmitter and the individual cell voltage detected by each individual cell voltage transmitter; then determining whether the emergency battery pack needs heating based on the individual cell temperature detected by each individual cell temperature transmitter; if heating is required, controlling the charging and discharging contactor and the heating contactor to close, controlling the charging contactor and the discharging contactor to open, and then sending a heating request command to the charger; if heating is not required, directly entering the charging process; during the charging process, controlling the charging and discharging contactor and the charging contactor to close, controlling the heating contactor and the discharging contactor to open, and then sending a charging request command to the charger.

[0030] Optionally, it further includes: during the charging process, the charger controls the currently output charging voltage and charging current based on the charging voltage and charging current detected by the total voltage transmitter and the total current transmitter.

[0031] Optionally, it further includes: during the charging process, the battery pack control system determines whether to stop charging based on the total current detected by the total current transmitter and the individual cell voltage detected by the individual cell voltage transmitter. If it is necessary to stop charging, it sends a stop charging command to the charger and controls the charging contactor to disconnect.

[0032] Optionally, the system further includes: the battery pack control system determines whether the discharge requirements are met based on the individual cell voltage detected by the individual cell voltage transmitter, the individual cell temperature detected by the individual cell temperature transmitter, and the total voltage detected by the total voltage transmitter; then controls the charging / discharging contactor and the discharging contactor to close, and controls the heating contactor and the charging contactor to open.

[0033] Optionally, the discharge requirements include: the individual cell voltage is within a set voltage range, the maximum individual cell voltage difference is less than a set value, the individual cell temperature is less than a set value, the maximum individual cell temperature difference is less than a set value, and the total voltage is greater than a set value.

[0034] Optionally, each BMS master controller has hot standby redundancy, with only one BMS master controller communicating and interacting with the charger at any given time, while the other BMS master controllers back up the information sent to them by each BMS master controller.

[0035] Based on the above circuit structure and corresponding charging and discharging control methods, the battery pack control system can obtain the voltage and temperature information of the lithium battery cells, as well as the output voltage and current of the battery module. This allows it to determine whether the 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 preventing float charging. The battery pack control system can also determine when the current battery module temperature is too low and charging is required. In this case, it controls the charging and discharging contactor and the heating contactor to conduct, thereby forming a current loop between the first series branch and the second series branch and the charging module. The heating element heats the lithium battery cells, thus preventing the charging capacity from being too low.

[0036] The first, second, third, and fourth series sections achieve different functions through the on / off settings of each contactor, resulting in a simple circuit structure.

[0037] The three-level BMS control divides functions into a minimum number of replaceable units, which facilitates fault location and reduces maintenance costs. In other words, only the faulty BMS needs to be replaced. Attached Figure Description

[0038] Figure 1 This is a circuit diagram of an emergency power supply system for lithium batteries in railway vehicles according to an embodiment of the present invention.

[0039] Figure 2 This is a communication relationship diagram of the emergency power supply system for lithium batteries in railway vehicles according to an embodiment of the present invention. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0041] Figure 1 This is a circuit diagram of an emergency power supply system for lithium batteries in railway vehicles according to an embodiment of the present invention. Figure 2 This is a communication relationship diagram of the emergency power supply system for lithium batteries in railway vehicles according to an embodiment of the present invention.

[0042] In embodiments 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 operation, the railway vehicle lithium battery emergency power supply system is connected to a high-voltage power supply device and a load.

[0043] The high-voltage power supply unit provides high-voltage DC power, and outputs DC600V (DC500V to DV660V) DC power voltage.

[0044] Loads include, for example, controllers for high-voltage power supply devices and controllers for chargers.

[0045] The emergency battery pack consists of two battery packs (Battery Pack 1 and Battery Pack 2), which are redundant. The emergency battery pack can also contain three or more battery packs, or in extreme cases, it can contain only one battery pack. The internal structure and external connections of each battery pack can be found in [reference needed]. Figure 1 The illustrated embodiment. In one practical example, the rated capacity of the emergency battery pack is 120 Ah.

[0046] A single battery pack contains multiple lithium battery cells, BMS slave controller, BMS master controller, BMS central controller, heating film, multiple contactors, multiple transmitters, multiple fuses, and multiple diodes.

[0047] Figure 1 The multiple battery symbols shown represent multiple lithium battery cells. The voltage range of a single lithium battery cell is DC 2.5V to DC 3.5V. Multiple lithium battery cells are connected in series and parallel to form a battery module, so that the battery pack has an output rated voltage of DC 110V (voltage range DC 83V to DC 115V).

[0048] The BMS slave controller, BMS master controller, and BMS master controller constitute a three-level power management system (battery pack control system). The BMS slave controller, BMS master controller, and BMS master controller are three independent battery management systems. In battery pack 1, they are labeled BMS1 slave controller, BMS1 master controller, and BMS1 master controller. In battery pack 2, they are labeled BMS2 slave controller, BMS2 master controller, and BMS2 master controller.

[0049] The BMS slave controller is connected to individual cell voltage transmitters (not shown), each corresponding to a single lithium-ion battery cell in the battery pack, for detecting the voltage of the corresponding lithium-ion battery cell. The BMS slave controller also includes individual cell temperature transmitters (not shown), each corresponding to a single lithium-ion battery cell in the battery pack, for detecting the temperature of the corresponding lithium-ion battery cell. (Reference) Figure 2 The BMS slave controller communicates with the BMS master controller in the battery pack via the CAN bus, and sends the voltage and temperature values ​​of each lithium battery cell to the BMS master controller.

[0050] The BMS master controller connects to the total voltage and total current transmitters to detect the total voltage and total current of the battery pack and calculate the State of Charge (SOC) percentage of the remaining capacity of the battery pack relative to the total capacity. The total voltage transmitter for battery pack 1 is labeled V1, and the total current transmitter is labeled A1. The total voltage transmitter for battery pack 2 is labeled V2, and the total current transmitter is labeled A2. The BMS master controller sends the highest and lowest individual lithium battery voltages, highest and lowest individual lithium battery temperatures, battery pack charge / discharge current, battery pack charge / discharge voltage, and battery pack SOC to the BMS master controller within the respective battery pack.

[0051] refer to Figure 2 Each BMS master controller communicates with the central BMS controller via a CAN bus. Each BMS central controller communicates with the charger via an Ethernet bus.

[0052] The information sent from the BMS master controller to the charger includes: the highest voltage, lowest voltage, highest temperature, and lowest temperature of the lithium battery cells in the battery pack where the BMS master controller is located; the total current and voltage of the battery pack; the state of charge (SOC) of the battery pack; the maximum allowable charging current and voltage of the emergency battery pack; the charging request command; the heating request command; the status of the charging contactor; the status of the discharging contactor; the status of the heating contactor; and the status of the charge / discharge contactor.

[0053] refer to Figure 1 Battery pack 1 has a charging contactor marked KMC1+, a discharging contactor marked KMF1+, a heating contactor marked KMJR1, and a charge / discharge contactor marked KMCF1-. Battery pack 1 also includes a circuit breaker QF1, fuses FU11 and FU12, and diodes D11 and D12. Battery pack 2 has a charging contactor marked KMC2+, a discharging contactor marked KMF2+, a heating contactor marked KMJR2, and a charge / discharge contactor marked KMCF2-. Battery pack 2 also includes a circuit breaker QF2, fuses FU21 and FU22, and diodes D21 and D22. Diodes D11 and D21 are the first diodes mentioned earlier. Diodes D12 and D22 are the second diodes mentioned earlier. The circuit connections of the two battery packs are the same; the following detailed explanation uses battery pack 1 as an example.

[0054] The BMS1 slave controller, BMS1 master controller, and BMS1 main controller are connected in parallel (the positive power terminals of the three are short-circuited, and the negative power terminals of the three are short-circuited). The three constitute the first parallel section. The first end of the first parallel section is connected to the negative terminal of the battery module, and the second end of the first parallel section is connected to the positive terminal of the battery module in sequence through a pair of electrodes of the power-on switch, circuit breaker QF1, and fuse FU11.

[0055] One measuring terminal of the total voltage transmitter V1 is connected to the negative terminal of the battery module, and the other measuring terminal is connected to the positive terminal of the battery module through the fuse FU11.

[0056] The two measuring terminals of the total current transmitter A1 and the charge / discharge contactor KMCF1 are connected in series to form the first series section. One end of the first series section is connected to the negative terminal 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.

[0057] The heating film is a membrane that wraps around a lithium battery cell to heat it. The heating film can also be replaced with other types of heating elements, such as resistance wire.

[0058] The heating film, fuse FU12, and heating contactor KMJR1 are connected in series to form a second series section. One end of the second series section is connected to the negative terminal 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.

[0059] The charging contactor KMC1+ and diode D11 are connected in series to form the third series section. The discharging contactor KMF1+ and diode D12 are connected in series to form the fourth series section. The third and fourth series sections are connected in parallel to form the second parallel section. The first terminal of the second parallel section is connected to the positive terminal of the battery module through fuse FU11, and the second terminal is connected to the positive power supply terminal of the load through the current transmitter A3 inside the charger. Diode D11 allows current to flow unidirectionally to the positive terminal of the battery module to charge the battery module. Diode D12 allows current to flow unidirectionally out of the positive terminal of the battery module to discharge the battery module.

[0060] The high-voltage power supply unit is connected to the charger to provide a DC 600V power supply voltage to the charger. The charger internally converts the DC 600V DC voltage to a DC 115V DC power supply voltage, which is then output by the charging module inside the charger.

[0061] Inside the charger, the positive and negative output terminals of the charging module are connected in series with fuse FU3, forming the fifth series connection. Voltage transmitter V3 is connected in parallel with the fifth series connection. The end of fuse FU3 not connected to the charging module is connected to the end of current transmitter A3 not connected to the second parallel connection. The end of current transmitter A3 not connected to the second parallel connection is connected to the positive power supply terminal of the load through diode D3, which allows current to flow unidirectionally from current transmitter A3 to the positive power supply terminal of the load.

[0062] Continue to refer to Figure 2 Both BMS1 master controller and BMS2 master controller simultaneously send their respective information to both the BMS1 main controller and the BMS2 main controller. The information received by the BMS1 main controller and the BMS2 main controller from the BMS1 master controller and the BMS2 main controller remains identical. The BMS1 main controller and the BMS2 main controller have hot standby redundancy. One of the BMS1 main controller and BMS2 main controllers acts as the master controller, exchanging information with the charger via an Ethernet bus. When the master controller fails, the other BMS main controller is promoted to master controller and continues to perform the master controller's tasks.

[0063] The following describes the charging and discharging control method.

[0064] (1) Discharge

[0065] ① The operator closes the circuit breakers QF1 and QF2 for each battery, and sets the power switch to the "Power On" position. At this time, the power of the battery module supplies power to the BMS1 slave controller, BMS1 master controller, BMS1 main controller, BMS2 slave controller, BMS2 master controller, and BMS2 main controller through the circuit breakers QF1 and QF2 and the power switch.

[0066] ②BMS1 slave controller and BMS2 slave controller acquire the voltage and temperature of lithium battery cells through individual cell voltage transmitters (not shown) and individual cell temperature transmitters (not shown), respectively, and transmit the acquired information to the corresponding BMS master controller via CAN bus.

[0067] ③ The BMS master controller receives the information transmitted by the BMS slave controller and detects the total voltage and total current of the battery pack. It determines whether the individual cell voltage range, maximum individual cell voltage difference, individual cell temperature range, maximum individual cell temperature difference, and battery pack voltage meet the requirements, and sends the relevant status and judgment results to the BMS master controller.

[0068] The criteria used by the BMS main controller to determine whether the discharge requirements are met are as follows:

[0069] a. Individual cell voltage > 2.5V ∩ Individual cell voltage < 3.5V;

[0070] b. Maximum monomer voltage difference < 0.5V;

[0071] c. Monomer temperature < 60℃;

[0072] d. Maximum single-unit temperature difference < 20℃;

[0073] e. Battery pack voltage > 83V;

[0074] If all five conditions above are met, the BMS controller determines that the corresponding battery pack can discharge externally. The values ​​above are for illustrative purposes only and can be replaced with other preset values.

[0075] ④ When the BMS master controller receives the message that the information judgment results all meet the requirements, the two BMS master controllers respectively control the closing of discharge contactor KMF1+, charge / discharge contactor KMCF1-, discharge contactor KMF2+, and charge / discharge contactor KMCF2-.

[0076] ⑤ The positive terminal of the lithium battery pack supplies power to the load via fuse FU11 (FU21), discharge contactor KMF1+ (KMF2+), diode D12 (D22), current transmitter A3, and diode D3, and then flows back to the negative terminal of the battery module via charge / discharge contactor KMCF1- (KMCF2-) and total current transmitter A1 (A2).

[0077] ⑥ When the BMS main controller determines that the criteria for meeting the discharge requirements are not met, the BMS main controller controls the discharge contactor KMF1+, charge / discharge contactor KMCF1-, discharge contactor KMF2+, and charge / discharge contactor KMCF2- to disconnect, and the emergency battery pack stops discharging.

[0078] (2) Charging

[0079] ① The emergency battery pack is in a discharging state, supplying power to the vehicle load (including the charger controller (not shown) and the high-voltage power supply unit controller (not shown)).

[0080] ② The high-voltage power supply device provides DC600V power to the charger. If the emergency battery pack does not send a charging request, the charger outputs a constant DC115V voltage. At this time, the charger voltage is higher than the emergency battery pack voltage. Due to the blocking of diodes D12 and D22, the vehicle load is powered by the charger.

[0081] ③ When the BMS master controller detects that the total battery pack voltage is <110V and the individual cell voltage is <3.3V, it sends a charging request command to the BMS master controller via the CAN bus. After receiving the charging request command, the BMS master controller checks the temperature of the individual lithium battery cells. If the highest individual cell temperature is <0℃, the BMS master controller sends a heating request command to the charger via the Ethernet bus to execute step ④; if the lowest individual cell temperature is >0℃, the BMS master controller sends a charging request command to the charger via the Ethernet bus to execute step ⑤. The above temperature and voltage values ​​can also be replaced with other set values.

[0082] ④ The BMS master control controls the closing of heating contactors KMJR1 and KMJR2. After receiving the heating request command, the charger adjusts its output voltage to 115V and keeps it constant, limiting the discharge current to no more than 24A to prevent the heating film temperature from being too high.

[0083] During heating, the current flows from the positive output terminal of the charger module through the current transmitter A3, heating contactor KMJR1 (KMJR2), and fuse FU12 (FU22) to the positive electrode of the heating film, and then from the negative electrode of the heating film through the total current transmitter A1 (A2) and charge / discharge contactor KMCF1- (KMCF2-) back to the negative output terminal of the charger module.

[0084] When heating, the charger output voltage is higher than the battery module voltage. Due to the blocking effect of diodes D12 and D22, the vehicle load is powered by the charger.

[0085] After heating, when the lowest unit temperature is >0℃, the BMS main control controls the heating contactors KMJR1 and KMJR2 to open, and controls the charging contactors KMC1+ and KMC2+ to close, sending a charging request command to the charger via the Ethernet bus to execute step ⑤.

[0086] ⑤ The BMS master control controls the closing of charging contactors KMC1+ and KMC2+. After receiving the charging command, the charger adjusts the charging voltage to output a constant current of 24A until the output voltage reaches DC115V and maintains a constant voltage.

[0087] During charging, the current flows from the positive output terminal of the charger's charging module through the current transmitter A3, diode D11 (D21), charging contactor KMC1+ (KMC2+), and fuse FU11 (FU21) to the positive terminal of the battery module, and from the negative terminal of the battery module through the total current transmitter A1 (A2) and charge / discharge contactor KMCF1- (KMCF2-) back to the negative output terminal of the charger's charging module.

[0088] During charging, the charger output voltage is higher than the battery module voltage. Due to the blocking effect of diodes D12 and D22, the vehicle load is powered by the charger.

[0089] ⑥ When the charger output voltage reaches 115V, the output voltage remains constant. At this time, the charging current will gradually decrease. When the BMS master controller detects that the charging current is <6A and the cell voltage is >3.5V (based on this, the battery pack is judged to be fully charged), the two BMS master controllers independently send charging stop commands to the BMS central controller via the CAN bus. After receiving the charging stop command request from either BMS master controller, the BMS central controller transmits the charging stop command to the charger via the Ethernet bus and controls the charging contactors KMC1+ and KMC2+ to disconnect. This is to prevent float charging. The above values ​​can also be replaced with other settings.

[0090] ⑦ After receiving the stop charging command, the charger outputs a constant DC 115V voltage.

[0091] After charging stops, the charger output voltage is higher than the battery module voltage. Due to the blocking effect of diodes D12 and D22, the vehicle load is powered by the charger.

[0092] The various embodiments in this invention are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0093] The scope of protection of this invention is not limited to the embodiments described above. Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its scope and spirit. If these modifications and variations fall within the scope of the claims of this invention and their equivalents, then the intent of this invention also includes these modifications and variations.

Claims

1. A lithium battery emergency power supply system for railway vehicles, characterized in that, include: Emergency battery pack, charger, power switch; The emergency battery pack includes at least one battery pack, which has multiple lithium battery cells connected to form a battery module, a battery pack control system, a first series section, a second series section, a third series section and a fourth series section, and the charger includes a charging module for outputting 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 are respectively connected to the positive and negative terminals of the corresponding battery modules. The first series section includes a total current transmitter and a charge / discharge contactor connected in series. The two ends of the first series section are respectively connected to the first terminal of the positive and negative terminals of the corresponding battery module and the first terminal of the positive and negative output terminals of the charging module. The second series section includes a heating element and a heating contactor connected in series. The two ends of the second series section are respectively connected to the first terminal of the positive and negative terminals of the corresponding battery module and the second terminal of the positive and negative output terminals of the charging module. The third series section includes a charging contactor and a first diode connected in series. The two ends of the third series section are respectively connected to the second terminal of the positive and negative terminals of the corresponding battery module and the second terminal of the positive and negative output terminals of the charging module. The first diode allows the current in the third series section to flow in one direction to charge the battery module. The fourth series section includes a discharge contactor and a second diode connected in series. The two ends of the fourth series section are respectively connected to the second terminal of the positive and negative terminals of the corresponding battery module and the second terminal of the positive and negative output terminals of the charging module. The second diode allows the current in the fourth series section to flow in one direction so that the battery module can discharge to the outside. The railway vehicle lithium battery emergency power supply system also includes: a total voltage transmitter connected between the positive and negative terminals of the battery module; The railway vehicle lithium battery emergency power supply system also includes: a cell temperature transmitter and a cell voltage transmitter that correspond one-to-one with 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 controller, a BMS master controller, and a BMS central controller connected in parallel. The BMS slave controller is connected to the BMS master controller via a bus communication connection, the BMS master controller is connected to the BMS central controller via a bus communication connection, the BMS central controller is connected to the charger via a bus communication connection, the total voltage transmitter and the total current transmitter are connected to the BMS master controller, and the individual cell temperature transmitter and the individual cell voltage transmitter are connected to the BMS slave controller.

2. The emergency power supply system for railway vehicle lithium batteries according to claim 1, characterized in that, The first series connection and the second series connection are connected to the first terminal of the positive and negative terminals of the battery module via a fuse; and / or, the third series connection, the fourth series connection and the series connection of the battery pack control system are connected to the second terminal of the positive and negative terminals of the battery module via a fuse.

3. The emergency power supply system for railway vehicle lithium batteries according to claim 1, characterized in that, The second series section also includes a fuse connected in series with the heating element.

4. The emergency power supply system for railway vehicle lithium batteries according to claim 1, characterized in that, There are multiple battery packs, and each BMS master controller is connected to the master controller of all BMS via a bus communication.

5. The charging and discharging control method for the emergency power supply system of lithium batteries for railway vehicles as described in any one of claims 1 to 4, characterized in that, include: The battery pack control system determines whether the emergency battery pack needs charging based on the total voltage detected by the total voltage transmitter and the individual cell voltage detected by each cell voltage transmitter. Then, it determines whether the emergency battery pack needs to be heated based on the individual cell temperature detected by each cell temperature transmitter. If heating is required, it controls the charging / discharging contactor and the heating contactor to close, and controls the charging contactor and the discharging contactor to open. Then, it sends a heating request command to the charger. If heating is not required, it directly enters the charging process. During the charging process, it controls the charging / discharging contactor and the charging contactor to close, controls the heating contactor and the discharging contactor to open, and then sends a charging request command to the charger.

6. The charging and discharging control method according to claim 5, characterized in that, Also includes: During the charging process, the charger controls the current output charging voltage and charging current based on the charging voltage and charging current detected by the total voltage transmitter and the total current transmitter.

7. The charging and discharging control method according to claim 5, characterized in that, Also includes: During the charging process, the battery pack control system determines whether to stop charging based on the total current detected by the total current transmitter and the individual cell voltage detected by the individual cell voltage transmitter. If it is necessary to stop charging, it sends a stop charging command to the charger and controls the charging contactor to disconnect.

8. The charging and discharging control method according to claim 5, characterized in that, Also includes: The battery pack control system determines whether the discharge requirements are met based on the individual cell voltage detected by the individual cell voltage transmitter, the individual cell temperature detected by the individual cell temperature transmitter, and the total voltage detected by the total voltage transmitter. Then, it controls the charging and discharging contactor and the discharging contactor to close, and controls the heating contactor and the charging contactor to open.

9. The charging and discharging control method according to claim 8, characterized in that, The discharge requirements include: the individual cell voltage is within the set voltage range, the maximum individual cell voltage difference is less than the set value, the individual cell temperature is less than the set value, the maximum individual cell temperature difference is less than the set value, and the total voltage is greater than the set value.

10. The charging and discharging control method according to claim 8, characterized in that, The emergency power supply system for lithium batteries in railway vehicles is the same as that described in claim 4. Each BMS master controller has hot standby redundancy, and only one BMS master controller communicates and interacts with the charger at any given time. The other BMS master controllers back up the information sent to them by each BMS master controller.

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