Control strategy for charging two or more groups of auxiliary storage batteries by one vehicle-mounted charger

Abstract

The invention provides a control strategy for charging two or more groups of auxiliary storage batteries by one vehicle-mounted charger, and relates to the technical field of train charging, and a charging system comprises the vehicle-mounted charger and a charging and discharging circuit; each bullet train and each trailer are provided with the auxiliary storage batteries, the auxiliary storage battery of each train is provided with the charging and discharging circuit, and the auxiliary storage battery of each train is provided with the charging and discharging circuit; and each vehicle-mounted charger is connected with the two ends of at least two groups of auxiliary storage batteries through the corresponding charging circuit. According to the invention, one vehicle-mounted charger charges multiple groups of auxiliary storage batteries through information coordination of the vehicle-mounted charger, the BMS and the TCMS and through a timing charging control strategy for each storage battery group, and meanwhile, the vehicle-mounted charger supplies power to the vehicle auxiliary load through the auxiliary load power supply circuit.

Description

Technical Field

[0001] This invention relates to the field of train charging technology, and more specifically, to a control strategy for charging two or more sets of auxiliary batteries using an on-board charger. Background Technology

[0002] Currently, rail vehicles use one onboard charger to charge one set of auxiliary batteries. When the auxiliary batteries are used for traction, one onboard charger also charges one set of auxiliary batteries. If there are multiple sets of auxiliary batteries, multiple onboard chargers are required, which is not conducive to vehicle weight reduction and energy saving, and is also costly. Summary of the Invention

[0003] This invention provides a control strategy for charging two or more sets of auxiliary batteries with one onboard charger, which solves the problem that traditional rail vehicles use one onboard charger to charge one set of batteries. This saves one onboard charger per vehicle unit, greatly reducing vehicle weight, size, energy consumption and cost.

[0004] This invention provides a novel control strategy for on-board charging of auxiliary batteries for rail vehicles.

[0005] To address the aforementioned problems, this invention provides a control strategy for charging two or more sets of auxiliary batteries using an on-board charger. This relates to a charging system for a train formation and is applied to such a system. The charging system includes an on-board charger, a BMS (Battery Management System), a TCMS (Traffic Control System), and a charging / discharging circuit. The charging / discharging circuit includes an emergency traction circuit and auxiliary batteries. The train formation includes multiple vehicles, including motor cars or motor cars and trailer cars. Each motor car and each trailer car is equipped with the auxiliary batteries, and each vehicle's auxiliary batteries are equipped with the charging / discharging circuit. At least one vehicle has an auxiliary load power supply circuit. Each motor car... The vehicle is equipped with an emergency traction circuit for emergency towing; the auxiliary battery of the vehicle is connected to the emergency traction circuit through a corresponding charging and discharging circuit; each on-board charger is connected to at least two sets of auxiliary batteries through a corresponding charging and discharging circuit; the auxiliary load power supply circuit is connected to the corresponding auxiliary battery through the vehicle's charging and discharging circuit; the BMS is connected to the auxiliary battery pack and the charging and discharging circuit, and is used to control the on / off state of the charging and discharging circuit; the on-board charger is also connected to the BMS and the TCMS through the vehicle bus, and is used for charging process control.

[0006] Optionally, the rail vehicle is a train set, the train set including at least one of the train units; each of the train units includes the auxiliary load power supply circuit, the emergency traction circuit and a vehicle, the vehicle including the motor car, or the motor car and the trailer car.

[0007] Optionally, each of the train sets includes two train units arranged symmetrically. Each train unit is equipped with at least one on-board charger. Each on-board charger is connected to the two ends of the auxiliary battery of each vehicle in the train unit through a corresponding charging and discharging circuit. The auxiliary load power supply circuit is located in the vehicle corresponding to the on-board charger.

[0008] Optionally, under the same conditions, for train units of different train formations, the capacity and charging current of the auxiliary battery of the motor car are both greater than those of the trailer car.

[0009] Optionally, the charging and discharging circuit includes a charging and discharging contactor, the charging and discharging circuit and the auxiliary battery constitute the main circuit, the main circuit is connected in parallel to the two ends of the on-board charger, the auxiliary load power supply circuit is connected in parallel to the two ends of the on-board charger, the emergency traction circuit of the train is connected in parallel to the two ends of the main circuit with the on-board charger; the BMS controls the on / off of the charging and discharging contactor.

[0010] Optionally, the emergency traction circuit includes a traction contactor, which forms a traction circuit with the traction converter of the train, and the traction circuit is connected in parallel with the on-board charger at both ends of the main circuit; the TCMS controls the on / off state of the traction contactor.

[0011] Optionally, the control strategy provided by the present invention for charging two or more auxiliary batteries with one on-board charger relates to the charging control process, which mainly includes: When the train is activated, the corresponding vehicle's BMS control contactor closes. The on-board charger obtains and judges the auxiliary battery power sent by the BMS of each vehicle, determines the vehicle with the smallest auxiliary battery power as the vehicle to be charged, keeps the charging and discharging circuit closed, or notifies the BMS of the vehicle to be charged to close the corresponding charging and discharging circuit and start charging according to the charging process determined by the present invention. If the charging parameters of the auxiliary battery of the vehicle to be charged meet the corresponding threshold conditions, it is determined whether there is an auxiliary battery traction command from the TCMS. The auxiliary battery traction command is used to control the closure of the corresponding emergency traction circuit to execute battery traction. After the auxiliary battery traction is performed, the on-board charger will determine the vehicle to be charged again based on the auxiliary battery power sent by the BMS of each vehicle, and start charging again according to the process. If the TCM does not perform auxiliary battery traction, it determines whether there is a stop command or to continue charging until the vehicle to be charged is fully charged. The on-board charger then notifies the vehicle's BMS to disconnect the corresponding charging and discharging circuit. Based on the auxiliary battery charge levels sent by the BMSs of the remaining vehicles, it determines the next vehicle to be charged, and starts charging the next vehicle to be charged while determining traction conditions or receiving a stop command.

[0012] Optionally, the on-board charger acquires and determines the auxiliary battery power from the BMS of each vehicle, identifies the vehicle with the lowest auxiliary battery power as the vehicle to be charged, maintains the closed state of the charging and discharging circuit, or notifies the BMS of the vehicle to be charged to close the corresponding charging and discharging circuit, initiate charging, and determine traction conditions, including: The on-board charger notifies the BMS of the vehicle to be charged so that the BMS of the vehicle to be charged closes the corresponding charging and discharging circuit; or, keeps the charging and discharging circuit of the vehicle to be charged closed. After the on-board charger starts charging, it acquires the power, current and voltage of the BMS of the vehicle to be charged, and compares them with the corresponding thresholds to execute at least one of the charging modes of constant current charging, constant voltage charging and float charging. In the constant voltage charging and float charging modes respectively, the on-board charger responds to the auxiliary battery traction command sent by the TCMS to disconnect the charging and discharging circuit of the BMS of the vehicle to be charged, and notifies the TCMS to close the emergency traction circuit of each motor car in the corresponding train unit to execute auxiliary battery traction.

[0013] Optionally, the control strategy may also include: If the charging parameters of the auxiliary battery of the vehicle to be charged meet the corresponding threshold conditions, and the on-board charger does not receive the auxiliary battery traction command within a set time period, the on-board charger determines that the auxiliary battery is faulty based on the auxiliary battery status information sent by the BMS of the vehicle to be charged, or it receives a charging stop command sent by the TCMS and stops charging.

[0014] This invention provides a control strategy for charging two or more sets of auxiliary batteries using a single onboard charger. Each onboard charger is connected to at least two sets of auxiliary batteries via a corresponding charging / discharging circuit. For two or more sets of auxiliary batteries, a single onboard charger can charge multiple sets, demonstrating the flexibility and scalability of this invention. For trains using auxiliary batteries for traction, each motor car and each trailer car is equipped with an auxiliary battery. Each vehicle's auxiliary battery is equipped with a charging / discharging circuit, and each motor car is equipped with an emergency traction circuit for emergency traction. The motor car's auxiliary battery is connected to the emergency traction circuit via a corresponding discharging circuit. The vehicle's auxiliary load power supply circuit is connected to the corresponding auxiliary battery via the vehicle's charging / discharging circuit. Through TCMS control, the emergency traction circuit can be closed when traction conditions are met, such as sufficient battery power, to provide traction power from the auxiliary batteries. The onboard charger interacts with the TCMS and BMS, and can be activated for charging as needed. As long as the onboard charger is operating, it can supply power to the train's auxiliary loads and charge the auxiliary batteries simultaneously. By employing a scheme where "one on-board charger charges two or more sets of auxiliary batteries," emergency load power can be guaranteed both during and after charging, and energy is provided for emergency traction. Compared to the traditional mode of "one on-board charger charging one set of batteries," this invention achieves multifunctionality and significantly reduces the number of on-board chargers required, lowering the system's hardware cost, size, and weight, thus achieving a high cost-performance ratio. Furthermore, the control of the entire charging system relies entirely on the vehicle's inherent on-board charger, BMS, and TCMS, eliminating the need for additional dedicated control hardware. This greatly simplifies the system structure, reduces complexity and failure rate, and improves overall reliability. Attached Figure Description

[0015] Figure 1 This invention illustrates the control circuit principle of an onboard charger charging two sets of auxiliary batteries using a train unit of a 4-motor, 4-car train as an example. Figure 1 ; Figure 2 This illustration shows the control circuit principle of a single onboard charger charging two sets of auxiliary batteries, using a 2-motor, 2-trailer, 4-train configuration as an example in an embodiment of the present invention. Figure 2 ; Figure 3 This illustration shows the control circuit principle of an onboard charger charging three sets of auxiliary batteries using a train unit of a 4-motor, 2-trailer, 6-car train as an example in this embodiment of the invention. Figure 1 ; Figure 4 This invention illustrates the control circuit principle of an onboard charger charging three sets of auxiliary batteries using a train unit of a 6-motor, 6-car train as an example. Figure 1 ; Figure 5 The diagram illustrates the control flow of a vehicle-mounted charger charging two sets of auxiliary batteries in an embodiment of the present invention. Detailed Implementation

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0017] It should be noted that relational terms such as "first" and "second" in this invention are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0018] In the description of this specification, references to terms such as "embodiment," "one embodiment," and "one implementation" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or implementation is included in at least one embodiment or illustrative implementation of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or implementation. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or implementations.

[0019] Reference Figure 1 and Figure 5As shown, this embodiment of the invention proposes a control strategy for charging two or more sets of auxiliary batteries using a single onboard charger. Applied to a charging system for a train formation, the charging system includes an onboard charger, a BMS, a TCMS, and a charging / discharging circuit. The charging / discharging circuit includes an emergency traction circuit and auxiliary batteries. The train formation includes multiple vehicles, including motor cars, or motor cars and trailer cars. Each motor car and each trailer car is equipped with the auxiliary batteries, and each vehicle's auxiliary batteries are equipped with the charging / discharging circuit. At least one vehicle has an auxiliary load power supply circuit, and each motor car is equipped with... The vehicle has an emergency traction circuit for emergency traction; the auxiliary battery of the vehicle is connected to the emergency traction circuit through a corresponding charging and discharging circuit; each on-board charger is connected to at least two sets of auxiliary batteries through a corresponding charging and discharging circuit; the auxiliary load power supply circuit is connected to the corresponding auxiliary battery through the vehicle's charging and discharging circuit; the BMS is connected to the auxiliary battery pack and the charging and discharging circuit, and is used to control the on / off state of the charging and discharging circuit; the on-board charger is also connected to the BMS (Battery Management System) and the TCMS (Train Control and Management System) through the vehicle bus, and is used for charging process control.

[0020] Specifically, the auxiliary batteries proposed in this invention are three or more sets. For the train formation conforming to this invention, the following formation can be adopted: 2-motor-2-trailer 4-car formation, 4-motor-4-car formation, 4-motor-2-trailer 6-car formation, 6-motor-6-car formation; for example, 2-motor-2-trailer 4-car formation means that 4 trains form a formation, which has two motor cars and two trailer cars; 4-motor-4-car formation is a train formation consisting of 4 motor cars, and so on.

[0021] Figure 1 This is the main circuit diagram of one unit (M1, M2) of a 4-motor, 4-car train, where an onboard charger (OBC) charges two sets of auxiliary batteries (BAT). The other unit (M3, M4) is exactly the same as (M1, M2).

[0022] Figure 2 This is the main circuit diagram of one unit (T1, M1) of a 2-motor, 2-trailer, 4-car train, where an onboard charger (OBC) charges two sets of auxiliary batteries (BAT). The other unit (T2, M2) is exactly the same as (T1, M1).

[0023] Figure 3This is the main circuit diagram of one unit (T1, M1, M2) of a 4-motor, 2-trailer, 6-car train, where the on-board charger OBC charges the auxiliary batteries BAT of trailer car 1 and motor car 2. The other unit (T2, M3, M4) is exactly the same as (T1, M1, M2).

[0024] Figure 4 This is the main circuit diagram of one unit (M1, M2, M3) of a 6-motor, 6-car train, where the onboard charger (OBC) charges the auxiliary batteries (BAT) of trailer car 1 and motor car 2. The other unit (M6, M5, M4) is exactly the same as (M1, M2, M3).

[0025] Each car (whether a motor car or a trailer car) is equipped with an auxiliary battery (BAT) and an independent charging and discharging circuit, but only the motor car is equipped with an emergency traction circuit, which enables basic energy access and safety redundancy.

[0026] For emergency traction circuits, they are used to connect the vehicle's traction module, such as the traction converter UC, and the traction module is generally directly connected to the high-voltage power grid; for train sets, the motor car is used for power traction and needs to be equipped with an emergency traction circuit, while the trailer car does not need to be equipped with one.

[0027] The auxiliary load power supply circuit is generally used for the 110V auxiliary power supply of the vehicle. It can be used for the vehicle's air conditioning, lights, etc. It is usually installed on the head and tail cars of the train and used as the auxiliary power supply of the vehicle (the main power supply can be configured with other battery packs).

[0028] Each on-board charger (OBC) acts as a power replenishment center, charging at least two auxiliary battery banks (BATs) via a charging circuit. The auxiliary load power supply circuit and emergency towing circuit are both connected in parallel with the auxiliary battery banks (BATs) through charging and discharging circuits. This ensures that as long as the auxiliary battery banks (BATs) have power, they can supply power to the load. During emergency towing controlled by the TCM, power comes directly from the auxiliary battery banks (BATs). While an on-board charger (OBC) is not strictly necessary, when it is operational, it can simultaneously charge and provide power to the auxiliary load. When the on-board charger is not operational, the trailer's battery can supply power to the vehicle's emergency load. For example, the OBC can charge the auxiliary batteries based on information such as the battery level of the auxiliary battery banks (BATs) collected by the BMS, or stop charging when the TCMS performs emergency towing.

[0029] The charging and discharging circuit is mainly responsible for managing three main energy flow directions: When charging, electrical energy starts from the on-board charger (OBC), passes through the charging circuit, and charges the auxiliary battery (BAT). When the train has grid voltage, the OBC operates, replenishing the battery's energy through this circuit. When discharging, electrical energy starts from the auxiliary battery (BAT), passes through the discharging circuit, and supplies power to the auxiliary load power supply circuit. When discharging, electrical energy starts from the train's auxiliary battery (BAT), passes through the charging circuit, and flows into the emergency traction circuit to provide high-voltage electricity to the traction system.

[0030] Information between the BMS and the on-board charger (OBC) is transmitted via Ethernet, MVB (Multifunction Vehicle Bus), or CAN bus. The transmitted data includes the BMS's battery SOC (state of charge) and fault status, as well as the OBC's output current and voltage.

[0031] In practical application, this embodiment utilizes a scheme where "one on-board charger (OBC) charges two or more auxiliary batteries (BAT)". This ensures power supply to emergency loads during and after charging, and provides energy assurance for emergency towing. Compared to the traditional "one charger, one battery" model, this invention achieves multi-functionality and significantly reduces the number of required OBCs, lowering system hardware costs, size, and weight, resulting in high cost-effectiveness. Furthermore, the control of the entire charging system relies entirely on the vehicle's inherent OBC, BMS, and TCMS, eliminating the need for additional dedicated control hardware. This greatly simplifies the system structure, reduces complexity and failure rate, and improves overall reliability.

[0032] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, in an optional embodiment of the present invention, the rail vehicle is a train set, the train set includes at least one train unit; each train unit includes the auxiliary load power supply circuit, the emergency traction circuit and the vehicle, the vehicle including a motor car, or the motor car and the trailer car.

[0033] Specifically, for a more flexible and scalable train formation architecture, its basic building block is the "train unit." A train formation can consist of one or more such units. Each train unit is a fully functional, self-contained, independent subsystem. Its core configuration has two typical modes: the first is the minimum functional unit, which must include an auxiliary load power supply circuit, an emergency traction circuit, and a motor car as the power source; the second is the extended functional unit, which adds a non-powered trailer car to the motor car to increase carrying capacity. In this case, the auxiliary load power supply circuit can be set on the trailer car. This modular design means that both short and long train formations can be quickly constructed by stacking one or more of these standardized "train units," greatly simplifying the design, manufacturing, and maintenance processes. More importantly, each unit has built-in complete power supply (auxiliary load power supply circuit) and emergency safety (emergency traction circuit) functions, ensuring the independent operation capability of a single unit and the redundancy backup capability in case of failure. Thus, from the system level, based on the charging system, the high availability and high reliability of the entire vehicle are achieved.

[0034] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, in an optional embodiment of the present invention, each train formation includes two train units arranged symmetrically. Each train unit is equipped with at least one on-board charger (OBC). Each OBC is connected to the auxiliary battery (BAT) terminals of all vehicles in the train unit via a corresponding charging / discharging circuit. The auxiliary load power supply circuit is provided in the vehicle corresponding to the OBC. Under the same conditions, for train units of different train formations, the capacity and charging current of the auxiliary battery (BAT) of the motor car are greater than those of the trailer car.

[0035] Specifically, symmetrical arrangement is a relatively simple train formation configuration that creates a train with two train units arranged symmetrically, such as... Figure 1 It is a 4-motor, 4-car train; Figure 2 It is a 4-car train consisting of 2 powered cars and 2 trailer cars; Figure 3 It is a 6-car train consisting of 4 powered cars and 2 trailer cars; Figure 4 It is a 6-motor, 6-car train; the assembly is simple, requiring only an end-to-end connection of two train units.

[0036] For each train unit, the on-board charger (OBC) is installed at one end, for example... Figure 1 The M1 and M4 cars in the middle, Figure 2 The T1 and T2 cars in the middle, Figure 3 The T1 and T6 cars in the series Figure 4The M1 and M6 cars in the example; for example, the auxiliary battery BAT of the motor car which is in the same car as the on-board charger OBC has a capacity of 200Ah: including auxiliary capacity (100Ah) and auxiliary battery traction capacity (100Ah); another car (the motor car that does not contain the on-board charger OBC and the trailer car which is only used for auxiliary power supply) has an auxiliary battery BAT capacity of 100Ah (only auxiliary battery traction or auxiliary power supply); for auxiliary battery BAT with a smaller capacity, the constant current charging current is smaller.

[0037] In practical application, this embodiment allows one onboard charger (OBC) to charge two or more auxiliary batteries (BAT) for a train unit. This solves many of the shortcomings of the previous method of configuring one onboard charger (OBC) for each auxiliary battery (BAT), such as the large number of onboard chargers (OBC) per train, heavy train weight, high energy consumption, and high price.

[0038] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, in an optional embodiment of the present invention, the charging and discharging circuit includes a charging and discharging contactor KM1. The charging and discharging circuit and the auxiliary battery BAT constitute the main circuit. The main circuit is connected in parallel to the two ends of the on-board charger OBC. The auxiliary load power supply circuit is connected in parallel to the two ends of the on-board charger OBC. The emergency traction circuit of the train is connected in parallel to the two ends of the main circuit. The BMS controls the on and off of the charging and discharging contactor KM1.

[0039] In terms of circuit connection, the charging / discharging contactor KM1 is connected to the auxiliary battery BAT, forming the main circuit. This main circuit is directly connected in parallel across the on-board charger (OBC). Simultaneously, the vehicle's auxiliary load power supply circuit (e.g., DC 110V) is also connected in parallel across the OBC. The OBC can charge the auxiliary battery BAT and supply power to the vehicle's loads simultaneously; that is, whenever the OBC is operating, it must simultaneously charge the battery and provide power to the auxiliary load.

[0040] Furthermore, the emergency traction circuit of the EMU is designed to be connected in parallel across the two ends of the main circuit. This key layout ensures that when emergency traction is required, the power from the auxiliary battery (BAT) can directly power the traction system through this circuit. In addition, the auxiliary battery (BAT) of the EMU can also power the auxiliary load power supply circuit (when the on-board charger (OBC) is not running). As for trailers, they do not have an emergency traction circuit and do not need to be used for emergency traction; they only need to power the auxiliary load power supply circuit. thus, Figure 1 and Figure 2 The difference is, Figure 1 The auxiliary batteries for the EMU include both the 110 auxiliary batteries and the 110 auxiliary batteries used for traction. Figure 2 The trailer T1 auxiliary battery only includes the auxiliary 110 auxiliary battery, whose capacity is greater than that of the standard auxiliary battery. Figure 1 The auxiliary battery of the M1 high-speed train is small, and the constant current charging current is different. Figure 2 T1 trailer Figure 1 The auxiliary battery of the M1 high-speed train has a small constant current charging current, but other aspects are the same.

[0041] Figure 3 and Figure 4 The difference is, Figure 3 The auxiliary battery for the M1 EMU includes both the 110 auxiliary battery and the 110 auxiliary battery for traction. Figure 3 The trailer T1 auxiliary battery only includes the auxiliary 110 auxiliary battery, whose capacity is greater than that of the standard auxiliary battery. Figure 4 The auxiliary battery of the M1 high-speed train is small, and the constant current charging current is different. Figure 3 T1 trailer Figure 4 The auxiliary battery of the M1 high-speed train has a small constant current charging current, but other aspects are the same.

[0042] As an optional embodiment of the present invention, the emergency traction circuit includes a traction contactor KM3, which forms a traction circuit with the traction converter UC of the train. The traction circuit is connected in parallel with the on-board charger OBC at both ends of the main circuit. The TCMS controls the on / off state of the traction contactor KM3.

[0043] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, in an optional embodiment of the present invention, the traction contactor KM3 of the traction circuit is provided with two pairs of contacts, which are connected to the two ends of the auxiliary battery BAT.

[0044] The following describes the charging and discharging paths based on various grouping methods. Because... Figure 1 and Figure 3 , Figure 2 and Figure 4 The charging principle diagrams for the auxiliary batteries BAT are completely identical, so this section's explanation of the charging principle diagrams only applies to... Figure 1 , Figure 4 The principle will be explained using an example.

[0045] (1) For Figure 1 Charging: One onboard charger (OBC) charges two auxiliary battery packs (BAT). M1 vehicle auxiliary battery BAT charging path: (On-board charger OBC 110V positive output point) 1~3~4~5~9~10~11~6~2 (On-board charger OBC 110V negative); M2 vehicle auxiliary battery BAT charging path: (On-board charger OBC 110V positive output point) 1~3~7~16~9~10~11~17~6~2 (On-board charger OBC 110V negative). (2) For Figure 4 Charging: One onboard charger (OBC) charges three auxiliary battery packs (BAT). M1 vehicle auxiliary battery BAT charging path: (On-board charger OBC 110V positive output point) 1~3~4~5~6~15~17~16~7~2 (On-board charger OBC 110V negative); M2 vehicle auxiliary battery BAT charging path: (On-board charger OBC 110V positive output point) 1~3~4~9~21~15~17~16~22~2 (On-board charger OBC 110V negative); M3 vehicle auxiliary battery BAT charging path: (On-board charger OBC 110V positive output point) 1~3~8~19~20~15~17~16~23~2 (On-board charger OBC 110V negative).

[0046] (3) Figures 1-4 Non-charging instructions: (On-board charger OBC 110V positive output point) 1~ Diode VD1~ to vehicle DC110V load This path is the on-board charger OBC supplying power to the auxiliary load (after the on-board charger OBC starts).

[0047] Auxiliary battery BAT discharge path: (1) For Figure 1 Discharge path: When the auxiliary battery is used for traction: the auxiliary battery BAT of cars M1 and M2 supplies power to the traction converter UC, and the contactor traction contactor KM3 is closed (auxiliary battery BAT positive) 10~9~12~13~11 (auxiliary battery BAT negative); at the same time, the auxiliary battery BAT of car M1 supplies power to the auxiliary load (auxiliary battery BAT positive) 10~9~4~8~auxiliary load~11 (auxiliary battery BAT negative).

[0048] (2) For Figure 2 Discharge path: When the auxiliary battery is used for traction: M1 car's auxiliary battery BAT supplies power to the traction converter UC, and the contactor traction contactor KM3 is closed (auxiliary battery BAT positive) 10~9~12~13~11 (auxiliary battery BAT negative); T1 car's auxiliary battery BAT supplies power to the auxiliary load (auxiliary battery BAT positive) 10~9~4~8~auxiliary load~11 (auxiliary battery BAT negative).

[0049] (3) For Figure 3 Discharge path: When the auxiliary battery is used for traction: the auxiliary battery BAT of cars M1 and M2 supplies power to the traction converter UC. The discharge path of the auxiliary battery BAT to the traction converter UC is the same. The contactor traction contactor KM3 is closed (auxiliary battery BAT positive) 17~15~11~12~16 (auxiliary battery BAT negative); at the same time, the auxiliary battery BAT of car T1 supplies power to the auxiliary load (auxiliary battery BAT positive) 15~6~5~10~auxiliary load~7`16 (auxiliary battery BAT negative).

[0050] (4) For Figure 4 Discharge path: When the auxiliary battery is used for traction: the auxiliary battery BAT of cars M1, M2, and M3 supplies power to the traction converter UC. The discharge path of the auxiliary battery BAT to the traction converter UC is the same. The contactor traction contactor KM3 is closed (auxiliary battery BAT positive) 17~15~11~12~16 (auxiliary battery BAT negative); at the same time, the auxiliary battery BAT of car M1 supplies power to the auxiliary load (auxiliary battery BAT positive) 17~15~6~5~10~7 auxiliary load ~16 (auxiliary battery BAT negative).

[0051] like Figure 5 As shown, this embodiment of the invention provides a control strategy for charging two or more sets of auxiliary batteries using an on-board charger, based on the charging system of a train formation as described in any of the preceding claims, including: The auxiliary load power supply circuit corresponds to the charging and discharging circuit of the vehicle's BMS closure. The on-board charger (OBC) obtains and judges the power level of the auxiliary battery (BAT) sent by the BMS of each vehicle. It determines that the vehicle with the lowest auxiliary battery BAT power level is the vehicle to be charged and keeps the charging and discharging circuit closed, or notifies the BMS of the vehicle to be charged to close the corresponding charging and discharging circuit, start charging, and judge the traction conditions. If the charging parameters of the auxiliary battery BAT of the vehicle to be charged meet the corresponding threshold conditions, it waits for the auxiliary battery traction command from the TCMS. The auxiliary battery traction command is used to control the closure of the corresponding emergency traction circuit. After the TCMS performs auxiliary battery traction, the on-board charger (OBC) again determines the vehicle to be charged based on the auxiliary battery (BAT) power level sent by the BMS of each vehicle, so as to start charging the vehicle to be charged and determine the traction conditions. If the TCM does not perform auxiliary battery traction, the on-board charger (OBC) will notify the vehicle's BMS to disconnect the corresponding charging and discharging circuit until the vehicle to be charged is fully charged. When the previous vehicle to be charged is fully charged, the next vehicle to be charged will be determined based on the auxiliary battery (BAT) charge level sent by the BMS of the remaining vehicles, so as to start charging the next vehicle to be charged and determine the traction conditions.

[0052] Specifically, after the train is activated, the BMS of the auxiliary battery BAT of each vehicle will work. Generally, the auxiliary battery BAT of vehicles equipped with on-board charger (OBC) is configured with an auxiliary load power supply circuit. At this time, the BMS of vehicles equipped with on-board charger (OBC) controls the charging and discharging contactor KM1 to close (while for vehicles without an auxiliary load power supply circuit, its charging and discharging circuit is in a normally open state). After closing, the auxiliary battery BAT discharges 110V to the relevant loads of the vehicle. Subsequently, the charger and the Train Network Control System (TCMS) perform self-tests. If the self-tests are successful, all systems begin operation. The Onboard Charger (OBC) determines that there is grid voltage and begins supplying power to the auxiliary loads. Based on the State of Charge (SOC) values ​​of the auxiliary battery charge (BAT) of each vehicle transmitted from the Train Management System (BMS), the OBC determines the vehicle with the minimum auxiliary battery charge (BAT) capacity (i.e., the vehicle to be charged) and initiates the charging and traction judgment process for that vehicle. Of course, if there is a charging instruction directly designated for a specific vehicle, that vehicle will be designated as the vehicle to be charged. Otherwise, before each charging cycle, the vehicle with the minimum auxiliary battery charge (BAT) capacity is used as the judgment criterion to determine the vehicle to be charged. For example, the aforementioned 2-motor 2-trailer 4-car train, 4-motor 4-car train, 4-motor 2-trailer 6-car train, and 6-motor 6-car train can achieve time-sharing and orderly charging.

[0053] The on-board charger starts charging and performs traction condition judgment process as follows: After determining the vehicle to be charged (such as M1), the charging and discharging circuit is kept closed (the charging and discharging contactor KM1 is closed when the auxiliary load power supply circuit has been powered), or the BMS of the vehicle to be charged is notified to close the corresponding charging and discharging circuit (the charging and discharging contactor KM1 is not closed). When the on-board charger (OBC) starts charging the vehicle to be charged, it charges according to the charging parameters transmitted from the vehicle management system (BMS). For example, if the state of charge (SOC) is low, it should perform high-current charging on the vehicle's auxiliary battery (BAT). As charging progresses, or after charging starts, it obtains the charging parameters of the auxiliary battery (BAT) transmitted from the BMS. If it finds that the traction conditions are met, such as if the charging current is extremely low, it indicates that the charging is close to complete. Then it is allowed to receive or respond to the auxiliary battery traction command from the vehicle management system (TCMS). When the TCMS performs auxiliary battery traction, it controls the traction contactor KM3 in the emergency traction circuit of each motor car of the train to close. After auxiliary battery traction is performed, if the on-board charger (OBC) detects a voltage issue, it returns to the vehicle battery level determination process. The OBC then uses the SOC value of the auxiliary battery (BAT) of each vehicle transmitted from the vehicle's BMS to determine the vehicle with the lowest battery level as the vehicle to be charged. This vehicle could be M1, M2, or M3. Subsequently, the OBC initiates charging and performs the traction condition determination process. After auxiliary battery traction is performed and the charging conditions are met, charging continues. This process is the same as the one described in the previous example. If auxiliary battery traction is not performed, the vehicle to be charged will be fully charged, and then the BMS will disconnect the vehicle's charging / discharging contactor KM1. Then, the charging determination for the next vehicle continues. The onboard charger (OBC) continues to determine the SOC value of the auxiliary battery (BAT) of each vehicle (usually the remaining uncharged vehicles, such as M2 and M3 train units that have not been charged) based on the data transmitted from the BMS. The vehicle with the lowest charge level is then selected as the next vehicle to be charged. Subsequently, the onboard charger (OBC) starts charging and performs the traction condition determination process, which is the same as the process in the previous example. After the train is activated, the onboard charger (OBC) is generally in the process of continuously charging each auxiliary battery (BAT), unless the train is in hibernation, receives a charging stop command, or there is a malfunction of the auxiliary battery (BAT).

[0054] After the on-board charger (OBC) is working, since the auxiliary load power supply circuit (DC110V) is connected to the two ends of the corresponding auxiliary battery (BAT) through the vehicle's charging and discharging circuit, and each on-board charger (OBC) is connected to the two ends of the auxiliary battery (BAT) of at least one vehicle through the corresponding charging and discharging circuit, as long as the on-board charger (OBC) is working, the on-board charger (OBC) can simultaneously charge and provide power to the auxiliary load.

[0055] The software control strategy of one on-board charger (OBC) charging two or more auxiliary batteries (BAT) in a time-sharing manner ensures that the capacity of each OBC is basically the same as or only slightly increased compared to the traditional OBC that charges one auxiliary battery (BAT) per unit, resulting in high cost-effectiveness.

[0056] In practical application, this embodiment constructs a dynamic time-sharing on-board charger (OBC) system based on battery power priority. Through full interaction and cooperation between the BMS, TCMS, and the OBC, it achieves intensive energy management of multiple auxiliary battery banks (BATs) by a single OBC. This method uses the SOC of the auxiliary battery banks (BATs) as the decision-making basis, automatically setting the vehicle with the lowest power level as the charging target. During charging, it simultaneously monitors the traction readiness status, enabling the system to quickly respond to emergency traction commands from the TCMS while completing basic charging tasks, ensuring power supply to emergency loads and providing energy assurance for emergency traction. The "one charger for multiple vehicles" intelligent scheduling strategy allows a single OBC to be used in a time-sharing manner. The multiple auxiliary batteries (BAT) serving the entire train unit significantly reduce the number of on-board chargers (OBCs), lower equipment costs and vehicle weight. Furthermore, dynamic power allocation eliminates the need for substantial increases in OBC capacity. While ensuring reliable energy supply and emergency traction response capabilities, it achieves a comprehensive improvement in economy and operational efficiency. It fully leverages the vehicle's existing hardware infrastructure; its control logic relies entirely on the vehicle's standard OBCs, Battery Management System (BMS), and Total Control System (TCMS), eliminating the need for dedicated control hardware or complex peripherals. The entire control process can be completed simply by upgrading embedded software and optimizing information exchange between existing devices, reducing costs and improving overall operational reliability and maintenance convenience.

[0057] Regarding the acquisition of charging parameters, in Figure 1 and Figure 2 as well as Figure 3 and Figure 4 In the image below, the internal components of the on-board charger (OBC) enclosure (dashed box) are described as follows: SV-On-Board Charger OBC 110V Output Voltage Sensor; SC1-On-board charger OBC 110V output current sensor; SC3 - First Auxiliary Battery (BAT) Charging Current Sensor (in the same vehicle as the On-Board Charger (OBC); SC2 - First group of auxiliary battery BAT charging current + auxiliary load power supply current sensor; SC4 - Second Auxiliary Battery BAT Charging Current Sensor; SC5 - The first set of auxiliary battery BAT charging current sensors; SC6 - First group of auxiliary battery BAT charging current sensor + second group of auxiliary battery BAT charging current sensor + auxiliary load power supply current sensor; These current and voltage sensors transmit the corresponding current and voltage.

[0058] VD1, VD2, VD3, VD4, and VD5 are all reverse protection diodes, which prevent excessive reverse current.

[0059] By using the current and voltage sensors mentioned above and transmitting parameters such as battery charge, voltage, and current from the corresponding vehicle BMS to the on-board charger, the charging process can be monitored to determine the status of each state and set the charging voltage and current.

[0060] like Figure 5 As shown, as an optional embodiment of the present invention, the control flowchart of a vehicle-mounted charger charging two sets of batteries in a time-sharing manner includes: the vehicle-mounted charger (OBC) obtains the power level of the auxiliary battery (BAT) sent by the BMS of each vehicle and determines the vehicle with the lowest auxiliary battery (BAT) power level as the vehicle to be charged, keeping the charging and discharging circuit closed, or notifying the BMS of the vehicle to be charged to close the corresponding charging and discharging circuit, starting charging and determining traction conditions, including: The on-board charger (OBC) notifies the vehicle's battery management system (BMS) to close the corresponding charging / discharging circuit; or, keeps the corresponding charging / discharging circuit closed. Specifically, the on-board charger (OBC) collects auxiliary battery (BAT) power data reported by each vehicle's battery management system (BMS) and dynamically selects the vehicle to be charged using a "lowest power priority" strategy. Then, it performs differentiated operations based on the vehicle's circuit status: if the target vehicle's charging / discharging circuit is open (e.g., a non-load-supplying vehicle), the OBC actively notifies its BMS to close the circuit and establish a charging path; if the target vehicle itself is a load-supplying vehicle (e.g., a vehicle equipped with an OBC), its existing closed charging / discharging circuit remains open. This flexible approach ensures the reliability of the charging circuit while also accommodating the functional characteristics of different vehicle roles.

[0061] After the on-board charger (OBC) starts charging, it acquires the battery level, current, and voltage of the vehicle's battery management system (BMS) and compares them with the corresponding thresholds to execute at least one of the following charging modes: constant current charging, constant voltage charging, and float charging. Specifically, after establishing a physical connection, the on-board charger (OBC) monitors the voltage, current, and other multi-dimensional parameters of the auxiliary battery (BAT) in real time through the battery management system (BMS), compares them with preset algorithm thresholds, and dynamically implements a three-stage charging strategy: when the battery energy is low, constant current charging is used to achieve rapid energy replenishment; when the voltage reaches the set threshold, it switches to constant voltage charging mode, achieving safe saturation through natural current decay; finally, it enters the float charging stage for refined energy maintenance. This multi-mode adaptive mechanism not only ensures charging efficiency but also effectively extends battery life through algorithm control.

[0062] In the constant voltage charging and float charging modes respectively, the on-board charger (OBC) responds to the auxiliary battery traction command sent by the TCMS to disconnect the charging and discharging circuit of the BMS of the vehicle to be charged, and notifies the TCMS to close the emergency traction circuit of each motor car in the corresponding train unit to execute auxiliary battery traction.

[0063] Specifically, when traction is required, the traction command from the TCMS is only allowed to be responded to during the constant voltage charging and float charging stages. This design is based on energy state judgment: when the battery completes constant current charging and enters the constant voltage / float charging stage, it has sufficient energy reserves to support emergency traction. When the traction command is received, the system immediately performs an orderly switch: the BMS of the vehicle to be charged disconnects the charging and discharging circuit to release the charging state, and the TCMS simultaneously closes the emergency traction circuit of the entire line of trains, realizing a safe conversion from power supply mode to traction mode.

[0064] Let's combine them again below. Figure 5 Please provide an explanation.

[0065] First, it should be emphasized that during the execution of the following control process, regardless of which auxiliary battery BAT is being charged, when the TCMS issues a battery traction command, the traction contactor KM3 in the emergency traction circuit of all trains will be closed (TCMS control), and the charging and discharging contactor KM1 in all battery circuits will be closed (each train's BMS control).

[0066] Taking a charging vehicle such as the M1 as an example, the on-board charger (OBC) determines the vehicle with the minimum auxiliary battery capacity (BAT) based on the SOC value of the auxiliary battery (BAT) of each vehicle transmitted from the BMS, and then enters the charging and traction judgment process for that vehicle.

[0067] If the SOC data sent by each vehicle's BSM is used to determine the vehicle to be charged, and vehicle M1 has the lowest battery level; If vehicle M1 needs to supply power to the auxiliary load power supply circuit, the charging and discharging contactor KM1 remains closed, and the on-board charger (OBC) begins charging the vehicle to be charged. The OBC determines the SOC of the battery of the vehicle to be charged. If the SOC of the vehicle to be charged is less than the first preset capacity, such as 50%, the vehicle to be charged is charged according to the first preset charging current, such as 0.5C. If the SOC of the vehicle to be charged is not less than the first preset capacity, the vehicle is charged directly according to the preset voltage. For lithium titanate batteries, the preset voltage can be 2.68 × n (number of series batteries), and the constant voltage charging mode is entered. As constant current charging continues, the auxiliary battery BAT voltage gradually increases. The on-board charger (OBC) judges whether the BAT voltage sent by the BMS has reached the preset voltage. If not, it continues to charge according to the first set charging current until the auxiliary battery BAT voltage reaches the preset voltage. Then, it charges according to the preset voltage and enters the constant voltage charging mode. When charging according to the preset voltage, it indicates that the auxiliary battery BAT has a certain amount of power, and at this time it is allowed to receive or respond to the auxiliary battery traction command of TCMS. When TCMS performs auxiliary battery traction, it controls the traction contactor KM3 of each motor car in the train unit to close. After auxiliary battery traction is performed, if the on-board charger (OBC) detects a voltage issue, the OBC determines the vehicle with the lowest auxiliary battery BAT charge based on the SOC value of each vehicle's auxiliary battery BAT transmitted from the BMS. The OBC then initiates the charging and traction decision process for that vehicle, which is the same as the process described in the previous example. Conversely, if there is no auxiliary battery traction command from the TCMS when the vehicle to be charged is charging at the preset voltage, the charging current will continue to decrease as charging continues. At this time, the on-board charger (OBC) will determine whether the charging current transmitted from the BMS is less than the second set charging current, such as 0.02C. If the second set charging current is less than the first set charging current, and it is less, then charging will proceed according to the second set charging voltage, such as 2.5V×n, entering float charging; if it is greater, then charging will continue according to the preset voltage until the charging current is less than the second set charging current, entering float charging. Similarly, this indicates that the auxiliary battery BAT power has been further increased, and at this time it is allowed to receive or respond to the auxiliary battery traction command from TCMS; When TCMS performs auxiliary battery traction, it controls the traction contactor KM3 of each motor car in the train unit to close. After performing auxiliary battery traction, if the on-board charger (OBC) detects a grid voltage issue, the OBC determines the vehicle with the minimum auxiliary battery BAT charge based on the SOC value of each vehicle's auxiliary battery BAT transmitted from the BMS, and then initiates the charging and traction judgment process for that vehicle. Conversely, if there is no auxiliary battery traction command from TCMS when the vehicle to be charged is charged according to the preset voltage, the charging continues according to the second preset charging voltage until the charging current is less than the second preset charging current. At this time, it is considered that the vehicle to be charged is close to being fully charged, and BMS disconnects the charging and discharging contactor KM1 of the vehicle, and the "vehicle to be charged" is completed. Then the charging of the next vehicle proceeds. Similar to the previous process, the on-board charger (OBC) obtains the SOC (State of Charge) of the BMS (Battery Management System) of the remaining vehicles to make a judgment. If the battery level of vehicle M2 is low, the charging process continues according to the previous vehicles to be charged until vehicle M2 is fully charged. The same principle applies to other vehicles such as vehicle M3, thus enabling the charging of two or more auxiliary batteries (BAT).

[0068] It should be noted that in actual operation, motor cars are generally charged first, followed by trailer cars, to ensure sufficient power for emergency traction and auxiliary load power supply circuits.

[0069] The following uses lithium titanate batteries as an example to illustrate the charging modes.

[0070] The battery uses lithium titanate, and its main parameters are as follows: Nominal voltage 2.3 (V), charging cut-off voltage 2.7 (V), discharging cut-off voltage 1.5 (V).

[0071] (1) Constant current charging; control the closing of the charging and discharging contactor KM1; In this state, the voltage of the auxiliary battery BAT is low, and the charging current remains at a relatively large value. The maximum charging current of the battery is determined by the battery capacity, which is 0.5C (C battery capacity) in this invention. When the voltage of a single cell reaches 2.68V, it switches to the constant voltage charging stage.

[0072] (3) Constant voltage charging; The battery voltage remains constant at 2.68V, while the charging current gradually decreases. (4) Floating charge; When the charging current drops below 0.02C, the auxiliary battery BAT is considered to be fully charged and switches to float charging, charging at a lower constant voltage of 2.5V. The output voltage of the on-board charger OBC is controlled to fluctuate around this 2.5Xn (n is the number of individual cells in series) voltage point.

[0073] When the float charge reaches the set duration or the charging current is extremely low, the vehicle's auxiliary battery (BAT) is considered fully charged.

[0074] For the auxiliary battery traction command of TCMS, TCMS obtains the SOC sent by the BMS of all trains. When the SOC of all trains in the train unit is greater than the second preset power (generally greater than the aforementioned first preset power), it allows the auxiliary battery traction command to be sent to the on-board charger (OBC), or allows and responds to the user input of the auxiliary battery traction command. The above embeds the traction response mechanism into the charging process and allows for immediate response to TCMS traction commands under appropriate conditions. For a single train unit, the coordinated operation of the BMS disconnecting the charging and discharging circuit and the TCMS closing the emergency traction circuit enables a safe switch from power supply mode to traction mode. By time-sharing multiplexing of a single onboard charger (OBC) to orderly charge multiple auxiliary batteries (BAT), the system significantly improves equipment utilization efficiency while ensuring traction emergency response capabilities, forming a charging management solution that combines dynamic adaptability and operational economy.

[0075] like Figure 5 As shown, as an optional embodiment of the present invention, the control strategy for one on-board charger to charge two or more auxiliary batteries further includes: If the charging parameters of the auxiliary battery BAT of the vehicle to be charged meet the corresponding threshold conditions, and the on-board charger (OBC) does not receive the auxiliary battery traction command within a set time period, the OBC will determine that the auxiliary battery BAT is faulty based on the auxiliary battery BAT status information sent by the vehicle's BMS, or it will stop charging upon receiving a charging stop command sent by the TCMS.

[0076] Specifically, a safety interruption mechanism has been added to the original charging control process, enabling intelligent management of the charging process through dual judgment conditions: when the auxiliary battery (BAT) of the vehicle to be charged completes the core charging stage (charging parameters reach the threshold conditions) and no traction command is received within the set time, the on-board charger (OBC) will initiate a safety diagnostic process—analyzing the auxiliary battery (BAT) status information uploaded by the BMS to determine the fault. If a battery abnormality is detected, charging will be terminated immediately. At the same time, a TCMS system-level intervention channel is introduced. When the central control system issues a charging stop command, the OBC will unconditionally execute the stop operation. This mechanism forms a protection strategy, which not only avoids the possibility of the auxiliary battery (BAT) continuing to charge under fault conditions, but also ensures rapid response capability under special operating conditions through system-level commands, further improving the operational reliability of the charging system.

[0077] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, an embodiment of the present invention provides a train formation including, as described above, an auxiliary load power supply circuit, an emergency traction circuit, an auxiliary battery (BAT), a battery management system (BMS), and a motor car, or a motor car and a trailer car. The BMS is connected to the emergency traction circuit and is also used to connect to the emergency traction circuit and the charging / discharging circuit described above, so as to realize the control strategy of charging two or more sets of auxiliary batteries by one on-board charger as described in any of the above claims.

[0078] Specifically, the train can be in the form of the commonly used formations of urban rail vehicles as described above: 2 powered and 2 trailer cars, 4 powered and 4 trailer cars, 4 powered and 2 trailer cars, 6 powered and 6 trailer cars; the specific implementation of other parts can be referred to the aforementioned embodiments, and will not be described here again.

[0079] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided by this invention can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0080] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

[0081] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A control strategy for charging two or more sets of auxiliary batteries using a single on-board charger, characterized in that, A charging system for train formations includes an onboard charger, a battery management system (BMS), a total charge control system (TCMS), and charging / discharging circuits. The charging / discharging circuits include an emergency traction circuit and auxiliary batteries. The train formation includes multiple cars, including power cars or power cars and trailer cars. Each power car and each trailer car is equipped with an auxiliary battery, and each car's auxiliary battery is equipped with a charging / discharging circuit. At least one car has an auxiliary load power supply circuit, and each power car is equipped with an emergency traction circuit for emergency traction. The auxiliary batteries of the power cars are connected to the emergency traction circuits via corresponding charging / discharging circuits. Each onboard charger is connected to at least two sets of auxiliary batteries via corresponding charging / discharging circuits. The auxiliary load power supply circuit is connected to the corresponding auxiliary batteries via the car's charging / discharging circuits. The BMS is connected to the auxiliary battery sets and the charging / discharging circuits and is used to control the on / off state of the charging / discharging circuits. The TCMS is connected to the onboard charger via a vehicle bus. The onboard charger is also connected to the BMS via the vehicle bus and is used to initiate charging.

2. The control strategy for charging two or more sets of auxiliary batteries with one on-board charger according to claim 1, characterized in that, The train set includes at least one train unit; each train unit includes the auxiliary load power supply circuit, the emergency traction circuit, and the vehicle, the vehicle including the motor car, or the motor car and the trailer car.

3. The control strategy for charging two or more sets of auxiliary batteries with one on-board charger according to claim 2, characterized in that, Each of the train sets includes two train units arranged symmetrically. Each train unit is equipped with at least one on-board charger. Each on-board charger is connected to the two ends of the auxiliary battery of each vehicle in the train unit through a corresponding charging and discharging circuit. The auxiliary load power supply circuit is located in the vehicle corresponding to the on-board charger.

4. The control strategy for charging two or more sets of auxiliary batteries with one on-board charger according to claim 3, characterized in that, Under the same conditions, for train units of different train formations, the capacity and charging current of the auxiliary battery of the motor car are both greater than those of the trailer car.

5. The control strategy for charging two or more sets of auxiliary batteries by one on-board charger according to any one of claims 1-4, characterized in that, The charging and discharging circuit includes a charging and discharging contactor. The charging and discharging circuit and the auxiliary battery constitute the main circuit. The main circuit is connected in parallel to both ends of the on-board charger. The auxiliary load power supply circuit is connected in parallel to both ends of the on-board charger. The emergency traction circuit of the train is connected in parallel to both ends of the main circuit. The BMS is connected to the charging and discharging contactor and is used to control its on and off states.

6. The control strategy for charging two or more sets of auxiliary batteries by one on-board charger according to claim 5, characterized in that, The emergency traction circuit includes a traction contactor, which forms a traction circuit with the traction converter of the train. The traction circuit is connected in parallel with the on-board charger at both ends of the main circuit. The TCMS is connected to the traction contactor and is used to control the on / off state of the traction contactor.

7. The control strategy for charging two or more sets of auxiliary batteries with one on-board charger according to claim 5, characterized in that, The traction circuit has at least two traction contactors, and the two ends of the traction converter are respectively connected to the two ends of the auxiliary battery through at least one traction contactor; the TCMS is used to synchronously control the on and off of the traction contactors.

8. The control strategy for charging two or more sets of auxiliary batteries by one on-board charger according to any one of claims 1-4, characterized in that, include: The auxiliary load power supply circuit corresponds to the charging and discharging circuit of the vehicle's BMS closure. The on-board charger obtains and judges the auxiliary battery power sent by the BMS of each vehicle, determines the vehicle with the smallest auxiliary battery power as the vehicle to be charged, keeps the charging and discharging circuit closed, or notifies the BMS of the vehicle to be charged to close the corresponding charging and discharging circuit, start charging and judge the traction conditions. If the charging parameters of the auxiliary battery of the vehicle to be charged meet the corresponding threshold conditions, it waits for the auxiliary battery traction command from the TCMS. The auxiliary battery traction command is used to control the closure of the corresponding emergency traction circuit. After the TCMS performs auxiliary battery traction, the on-board charger once again determines the vehicle to be charged based on the auxiliary battery power sent by the BMS of each vehicle, so as to start charging the vehicle to be charged and determine the traction conditions. If the TCM does not perform auxiliary battery traction, the on-board charger will notify the vehicle's BMS to disconnect the corresponding charging and discharging circuit until the vehicle to be charged is fully charged. When the previous vehicle to be charged is fully charged, the next vehicle to be charged will be determined based on the auxiliary battery charge level sent by the BMS of the remaining vehicles, so as to start charging the next vehicle to be charged and determine the traction conditions.

9. The control strategy for charging two or more sets of auxiliary batteries by one on-board charger according to claim 8, characterized in that, The on-board charger acquires and determines the auxiliary battery power from the BMS of each vehicle, identifying the vehicle with the lowest auxiliary battery power as the vehicle to be charged. It maintains the charging / discharging circuit in a closed state, or notifies the BMS of the vehicle to be charged to close the corresponding charging / discharging circuit, initiate charging, and determine traction conditions, including: The on-board charger notifies the BMS of the vehicle to be charged so that the BMS of the vehicle to be charged closes the corresponding charging and discharging circuit; or, keeps the charging and discharging circuit of the vehicle to be charged closed. After the on-board charger starts charging, it acquires the power, current and voltage of the BMS of the vehicle to be charged, and compares them with the corresponding thresholds to execute at least one of the charging modes of constant current charging, constant voltage charging and float charging. In the constant voltage charging and float charging modes respectively, the on-board charger responds to the auxiliary battery traction command sent by the TCMS to disconnect the charging and discharging circuit of the BMS of the vehicle to be charged, and notifies the TCMS to close the emergency traction circuit of each motor car in the corresponding train unit to execute auxiliary battery traction.

10. The control strategy for charging two or more sets of auxiliary batteries by one on-board charger according to claim 8, characterized in that, Also includes: If the charging parameters of the auxiliary battery of the vehicle to be charged meet the corresponding threshold conditions, and the on-board charger does not receive the auxiliary battery traction command within a set time period, the on-board charger determines that the auxiliary battery is faulty based on the auxiliary battery status information sent by the BMS of the vehicle to be charged, or it receives a charging stop command sent by the TCMS and stops charging.

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