Electric drive system and control method of new energy locomotive

Abstract

This invention discloses an electric drive system and its control method for a new energy locomotive. The system includes a first DC bus, a second DC bus, a first power battery pack, a second power battery pack, a bidirectional voltage converter, and a controller. The first power battery pack is connected to a first traction motor and a first auxiliary load via the first DC bus. The second power battery pack is connected to a second traction motor and a second auxiliary load via the second DC bus. The bidirectional voltage converter is connected between the first DC bus and the second DC bus. The first DC bus is also connected to the first traction motor via a first traction inverter, and the second DC bus is also connected to the second traction motor via a second traction inverter. The controller is used to control the bidirectional voltage converter to perform power balancing, or to control the first traction inverter and the second traction inverter to perform power balancing, based on the locomotive's operating mode and the power information of the first and second power battery packs.

Description

Technical Field

[0001] This invention relates to the field of new energy locomotive technology, and in particular to an electric drive system and control method for a new energy locomotive. Background Technology

[0002] New energy locomotives typically use large-capacity power batteries as their power source. To improve system redundancy and reliability, at least two independent intermediate DC links are often used, with each DC link connected to a set of power batteries to supply power to different types of loads.

[0003] However, when a vehicle remains stationary for extended periods, some loads continuously consume electrical energy, while others consume almost none, leading to an imbalance in the charge levels between different battery packs. Related technologies typically utilize redundant switching contactors to mitigate this imbalance, but this interrupts equipment operation, impacting user experience, and frequent operation causes wear and tear on contactors and other components. Furthermore, since the vehicle's overall range or charging strategy may be based on the battery pack with the lowest charge, even if some battery packs still have a significant remaining charge, they may be forced to charge due to one pack's low charge, thus reducing the vehicle's standby time, increasing charging frequency, and impacting operational efficiency. Summary of the Invention

[0004] This invention provides an electric drive system and control method for a new energy locomotive to solve the technical problem of uneven power supply between different power battery packs caused by differences in the power consumption of different types of loads.

[0005] According to one aspect of the present invention, an electric drive system for a new energy locomotive is provided, comprising a first DC bus, a second DC bus, a first power battery pack, a second power battery pack, a bidirectional voltage converter, and a controller;

[0006] The first power battery pack is connected to the first traction motor and the first auxiliary load via the first DC bus; the second power battery pack is connected to the second traction motor and the second auxiliary load via the second DC bus; the bidirectional voltage converter is connected between the first DC bus and the second DC bus and is communicatively connected to the controller;

[0007] The first DC bus is also connected to the first traction motor via the first traction inverter, and the second DC bus is also connected to the second traction motor via the second traction inverter; the controller is also communicatively connected to the first traction inverter and the second traction inverter.

[0008] The controller is used to control the bidirectional voltage converter to perform power balancing, or to control the first traction inverter and the second traction inverter to perform power balancing, based on the locomotive's operating mode and the power information of the first power battery pack and the second power battery pack; wherein, the locomotive's operating mode includes a stationary mode and a running mode, and the power information includes the power level of the first power battery pack and the power level of the second power battery pack.

[0009] Optionally, when the locomotive is in a stationary mode, the controller is configured to: control the bidirectional voltage converter to turn on when the difference between the charge of the first power battery pack and the charge of the second power battery pack exceeds a first threshold, and / or the charge of the first power battery pack is less than a second threshold.

[0010] Optionally, the operating modes include traction operating mode and braking operating mode;

[0011] When the locomotive is in traction operation mode, the controller is configured to: reduce the power of the second traction inverter when the charge of the first power battery pack is greater than the charge of the second power battery pack; or, reduce the power of the first traction inverter when the charge of the second power battery pack is greater than the charge of the first power battery pack.

[0012] The operating modes include traction operating mode and braking operating mode;

[0013] When the locomotive is in traction operation mode, the controller is configured to: reduce the power of the second traction inverter when the charge of the first power battery pack is greater than the charge of the second power battery pack; or, reduce the power of the first traction inverter when the charge of the second power battery pack is greater than the charge of the first power battery pack.

[0014] When the locomotive is in braking operation mode, the controller is configured to: reduce the power of the first traction inverter when the charge of the first power battery pack is greater than the charge of the second power battery pack; or, reduce the power of the second traction inverter when the charge of the second power battery pack is greater than the charge of the first power battery pack.

[0015] Optionally, the electric drive system of the new energy locomotive further includes: a first voltage conversion module, a second voltage conversion module, a constant voltage and constant frequency inverter, and a variable voltage and variable frequency inverter; the first auxiliary load includes a constant voltage and constant frequency auxiliary load, and the second auxiliary load includes a variable voltage and variable frequency auxiliary load;

[0016] The first power battery pack is connected to the first DC bus through the first voltage conversion module and to the constant voltage and constant frequency auxiliary load through the constant voltage and constant frequency inverter; the second power battery pack is connected to the second DC bus through the second voltage conversion module and to the variable voltage and variable frequency auxiliary load through the variable voltage and variable frequency inverter.

[0017] Optionally, the electric drive system of the new energy locomotive further includes: a first switching unit, a second switching unit, and a third switching unit; the controller is communicatively connected to the first switching unit, the second switching unit, and the third switching unit, respectively.

[0018] One end of the first switching unit is connected to the constant voltage and constant frequency inverter, and the other end is connected to the first auxiliary load; one end of the second switching unit is connected to the variable voltage and variable frequency inverter, and the other end is connected to the second auxiliary load; one end of the third switching unit is connected to the first auxiliary load, and the other end is connected to the second auxiliary load.

[0019] The control module is also used to control the first switch unit to turn off and the second switch unit and the third switch unit to turn on when the first DC bus fails; and to control the second switch unit to turn off and the first switch unit and the third switch unit to turn on when the second DC bus fails.

[0020] According to a second aspect of the present invention, a control method for an electric drive system of a new energy locomotive is provided, applied to the electric drive system of a new energy locomotive as described in any one of the first aspects, comprising:

[0021] Obtain power information for the first and second power battery packs;

[0022] A power balancing strategy is determined based on the power information and the locomotive's operating mode. The power balancing strategy includes: when the locomotive is stationary, controlling the bidirectional voltage converter to conduct to perform power balancing based on the power information; and when the locomotive is in operation, adjusting the power of the first traction inverter and the second traction inverter to perform power balancing based on the power information.

[0023] Optionally, the power information of the first and second power battery packs is obtained, including:

[0024] The battery pack's charge, voltage, temperature, and health status are obtained.

[0025] Optionally, when the locomotive is in a stationary mode, controlling the bidirectional voltage converter to turn on for power balancing based on the power information includes:

[0026] If the difference between the charge of the first power battery pack and the charge of the second power battery pack is greater than a first threshold, and / or the charge of the first power battery pack is less than a second threshold, the bidirectional voltage converter is controlled to turn on.

[0027] Optionally, when the locomotive is in operating mode, adjusting the power of the first traction inverter and the second traction inverter according to the power information to achieve power balance includes:

[0028] If the charge of the first power battery pack is less than that of the second power battery pack, then while keeping the total output power unchanged, the power of the first traction inverter is reduced and the power of the second traction inverter is increased.

[0029] If the charge of the first power battery pack is greater than that of the second power battery pack, then while keeping the total output power unchanged, the power of the second traction inverter is reduced and the power of the first traction inverter is increased.

[0030] Optionally, the control method for the electric drive system of the new energy locomotive also includes:

[0031] Determine whether the first and second power battery packs are faulty based on their voltage, temperature, and health status:

[0032] When the first power battery pack fails, the first switching unit is turned off and the second and third switching units are turned on.

[0033] When the second power battery pack fails, the second switching unit is turned off, and the first switching unit and the third switching unit are turned on.

[0034] The electric drive system of the new energy locomotive provided in this embodiment of the invention obtains the power information of the first and second power battery packs through a controller. When the new energy locomotive is in a stationary mode, it controls the bidirectional voltage converter to conduct and balance the power of the first and second power battery packs; or when the new energy locomotive is in a running mode, it controls the power conversion power of the first and second traction inverters to balance the power of the first and second power battery packs. The technical solution provided in this embodiment of the invention achieves static and dynamic multi-mode power balancing. Compared with the traditional balancing scheme that uses a switch contactor, the static and dynamic power balancing methods provided by this invention do not cause power interruption or significant fluctuations, improving the user experience and increasing the ability of the electric drive system of the new energy locomotive to cope with power imbalances under different operating conditions. It can effectively avoid the problem of power battery pack imbalance caused by rapid power consumption of the load when the vehicle is stationary, and reduce the charging frequency.

[0035] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the electric drive system of a new energy locomotive provided in an embodiment of the present invention;

[0038] Figure 2 A schematic diagram of the electric drive system of another new energy locomotive provided in an embodiment of the present invention;

[0039] Figure 3 A flowchart illustrating a control method for an electric drive system of a new energy locomotive, provided as an embodiment of the present invention;

[0040] Figure 4 A flowchart illustrating a control method for an electric drive system of a new energy locomotive, provided as an embodiment of the present invention;

[0041] Figure 5 A flowchart illustrating a control method for an electric drive system of a new energy locomotive, provided as an embodiment of the present invention;

[0042] Figure 6 A flowchart illustrating a control method for the electric drive system of a new energy locomotive, provided as an embodiment of the present invention.

[0043] Figure 7 A flowchart illustrating a control method for an electric drive system of a new energy locomotive, provided as an embodiment of the present invention. Detailed Implementation

[0044] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0045] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0046] Figure 1 This is a schematic diagram of the electric drive system of a new energy locomotive, provided as an embodiment of the present invention. See also... Figure 1 The electric drive system of this new energy locomotive includes a first DC bus L1, a second DC bus L2, a first power battery pack 12, a second power battery pack 22, a bidirectional voltage converter 3, and a controller 5. The first power battery pack 12 is connected to the first traction motor 14 and the first auxiliary load 17 via the first DC bus L1. The second power battery pack 22 is connected to the second traction motor 24 and the second auxiliary load 27 via the second DC bus L2. The bidirectional voltage converter 3 is connected between the first DC bus L1 and the second DC bus L2 and is communicatively connected to the controller 5. The first DC bus L1 is also connected to the first traction inverter 13. The second DC bus L2 is connected to the first traction motor 14 and is also connected to the second traction motor 24 via the second traction inverter 23. The controller 5 is also communicatively connected to the first traction inverter 13 and the second traction inverter 23. The controller 5 is used to control the bidirectional voltage converter 3 to perform power balancing, or to control the first traction inverter 15 and the second traction inverter 23 to perform power balancing, based on the locomotive's operating mode and the power information of the first power battery pack 12 and the second power battery pack 22. The locomotive's operating mode includes a stationary mode and a running mode, and the power information includes the power level of the first power battery pack and the power level of the second power battery pack.

[0047] Specifically, the first power battery pack 21 and the second power battery pack 22 can be energy storage units for the new energy locomotive. The first power battery pack 21 and the second power battery pack 22 can supply power to the first traction motor 14, the second traction motor 24, the first auxiliary load 17, and the second auxiliary load 27 of the new energy locomotive, or store the energy generated by different loads. The first DC bus L1 can transmit energy between the first power battery pack 21 and the first traction motor 14; the second DC bus L2 can transmit energy between the second power battery pack 22 and the second traction motor 24. When the new energy locomotive is traction-driven, the first traction motor 14 and the second traction motor 24 consume the energy stored in the first power battery pack 21 and the second power battery pack 22 to provide power to the new energy locomotive and drive it. When the new energy locomotive brakes, the energy generated by the first traction motor 14 and the second traction motor 24 is stored in the first power battery pack 21 and the second power battery pack 22. The first traction inverter 13 can convert DC power from the first power battery pack 21 into AC power, enabling the first traction motor 14 to drive the new energy locomotive; or, when the new energy locomotive brakes, it can convert the AC power generated by the first traction motor 14 into DC power for transmission and storage in the first power battery pack 21. The second traction inverter 23 can convert DC power from the second power battery pack 22 into AC power, enabling the second traction motor 24 to drive the new energy locomotive; or, when the new energy locomotive brakes, it can convert the AC power generated by the second traction motor 24 into DC power for transmission and storage in the second power battery pack 22. One end of the bidirectional voltage converter 3 can be connected to the first power battery pack 12 via the first DC bus L1, and the other end can be connected to the second DC battery pack 22 via the second DC bus L2. The controller 5 can be the electronic control unit of the new energy locomotive. The controller 5 can communicate with the bidirectional voltage converter 3, the first power battery pack 21, the second power battery pack 22, the first traction inverter 13, and the second traction inverter 23 via wired or wireless means, respectively. The controller 5 can acquire the power information of the first power battery pack 21 and the second power battery pack 22, and when the new energy locomotive is in a stationary mode, control the bidirectional voltage converter 3 to conduct in order to balance the power of the first power battery pack 21 and the second power battery pack 22; or when the new energy locomotive is in a running mode, control the power conversion power of the first traction inverter 15 and the second traction inverter 23 in order to balance the power of the first power battery pack 21 and the second power battery pack 22.

[0048] The electric drive system of the new energy locomotive provided in this embodiment of the invention obtains the power information of the first and second power battery packs through a controller. When the new energy locomotive is in a stationary mode, it controls the bidirectional voltage converter to conduct and balance the power of the first and second power battery packs; or when the new energy locomotive is in a running mode, it controls the power conversion power of the first and second traction inverters to balance the power of the first and second power battery packs. The technical solution provided in this embodiment of the invention achieves static and dynamic multi-mode power balancing. Compared with the traditional balancing scheme that uses a switch contactor, the static and dynamic power balancing methods provided by this invention do not cause power interruption or significant fluctuations, improving the user experience and increasing the ability of the electric drive system of the new energy locomotive to cope with power imbalances under different operating conditions. It can effectively avoid the problem of power battery pack imbalance caused by rapid power consumption of the load when the vehicle is stationary, and reduce the charging frequency.

[0049] Optionally, based on the above embodiments, see below. Figure 1 When the locomotive is in a stationary mode, the controller 5 is used to: control the bidirectional voltage converter 3 to turn on when the difference between the charge of the first power battery pack 12 and the charge of the second power battery pack 22 exceeds a first threshold, and / or the charge of the first power battery pack 12 is less than a second threshold.

[0050] Specifically, the first power battery pack 12 and the second power battery pack 22 can each be equipped with a battery management unit. The battery management unit can acquire information such as the charge, temperature, voltage, and health status of the corresponding battery pack in real time and transmit it to the controller 5. The stationary mode can be understood as the locomotive being in a parked, standby state. In the stationary mode, the first auxiliary load 17 and the second auxiliary load 27 will consume different amounts of electricity due to different needs. When the charge difference between the first power battery pack 12 and the second power battery pack 22 exceeds a first threshold, it indicates a large charge difference between the battery packs, requiring active balancing. At this time, the controller 5 controls the bidirectional voltage converter 3 to conduct, allowing electrical energy to flow from the battery pack with higher charge to the battery pack with lower charge, assisting the battery pack with lower charge in supplying power to the load, thereby achieving charge balance. This can be understood as the battery pack with higher charge simultaneously supplying power to both the first auxiliary load 17 and the second auxiliary load 27. Alternatively, if the charge of the first power battery pack 12 is less than the second threshold, it indicates that the first power battery pack 12 is in a low charge state and needs to obtain power from the second power battery pack 22 for charging, thereby avoiding over-discharge of the first power battery pack 12 and achieving power balance.

[0051] Optionally, based on the above embodiments, see below. Figure 1The operating modes include traction operating mode and braking operating mode. When the locomotive is in the operating mode, the controller 5 is used to: reduce the power of the first traction inverter 13 when the charge of the first power battery pack 12 is greater than the charge of the second power battery pack 22; or, reduce the power of the second traction inverter 23 when the charge of the second power battery pack 22 is greater than the charge of the first power battery pack 12.

[0052] When the locomotive is in braking operation mode, the controller 5 is used to: reduce the power of the first traction inverter 13 when the charge of the first power battery pack 12 is greater than the charge of the second power battery pack 22; or, reduce the power of the second traction inverter 23 when the charge of the second power battery pack 22 is greater than the charge of the first power battery pack 12.

[0053] Specifically, the traction operation mode can be understood as the new energy locomotive being in a traction driving state. In this mode, the first power battery pack 12 and the second power battery pack discharge power to the first traction motor 14 and the second traction motor 24. In traction operation mode, when the charge of one battery pack (first power battery pack 12 or second power battery pack 22) is greater than that of the other, the controller 5 can balance the charge of the two battery packs by reducing the power of the traction inverter corresponding to the lower-charged battery pack and increasing the power of the traction inverter corresponding to the higher-charged battery pack, while maintaining a constant total traction force. For example, when the charge of the first power battery pack 12 is greater than that of the second power battery pack 22, the controller 5 can reduce the power of the second traction inverter 23 and increase the power of the first traction inverter 13, thereby balancing the charge of the two battery packs while maintaining a constant total traction force.

[0054] The braking operation mode can be understood as the state of the new energy vehicle braking and moving before coming to a complete stop. In this mode, the first traction motor 14 and the second traction motor 24 charge the first power battery pack 12 and the second power battery pack. In braking operation mode, when the charge of one battery pack (first power battery pack 12 or second power battery pack 22) is greater than that of the other, the controller 5 can reduce the power of the traction inverter corresponding to the higher-charged battery pack, thereby reducing the charging power to the higher-charged battery pack and balancing the charge levels of the two battery packs. For example, when the charge of the first power battery pack 12 is greater than that of the second power battery pack 22, the controller 5 can reduce the power of the first traction inverter 13, so that the charging amount of the first power battery pack 12 during braking is less than that of the second power battery pack 22, thus balancing the charge levels of the two battery packs.

[0055] Optionally, Figure 2 This is a schematic diagram of the electric drive system of another new energy locomotive provided in an embodiment of the present invention. Based on the above embodiments, see... Figure 2The electric drive system of this new energy locomotive also includes: a first voltage conversion module 11, a second voltage conversion module 21, a constant voltage and constant frequency inverter 15, and a variable voltage and variable frequency inverter 25; the first auxiliary load 17 is a constant voltage and constant frequency auxiliary load, and the second auxiliary load 27 is a variable voltage and variable frequency auxiliary load; the first power battery pack 12 is connected to the first DC bus L1 through the first voltage conversion module 11, and is connected to the constant voltage and constant frequency auxiliary load 17 through the constant voltage and constant frequency inverter 15; the second power battery pack 22 is connected to the second DC bus L2 through the second voltage conversion module 21, and is connected to the variable voltage and variable frequency auxiliary load 27 through the variable voltage and variable frequency inverter 25.

[0056] Specifically, the first voltage conversion module 11 converts the low-voltage electricity from the first power battery pack 12 into high-voltage electricity that can be used to power the first traction motor 14 and the constant voltage and frequency auxiliary load 17; the second voltage conversion module 21 converts the low-voltage electricity from the second power battery pack 22 into high-voltage electricity that can be used to power the second traction motor 24 and the variable voltage and frequency auxiliary load 27. The first voltage conversion module 11 and the second voltage conversion module 21 can also be connected to an external charging pile. When the new energy vehicle is charged through an external charging pile, the charging power of the first power battery pack 12 and the second power battery pack 22 can be controlled by the controller 5. The constant voltage and frequency auxiliary load 17 can be the new energy vehicle's air conditioner, air conditioner compressor, vehicle socket, auxiliary heating equipment, etc.; the variable voltage and frequency auxiliary load 27 can be equipment such as a traction fan, cooling tower fan, and converter cooling fan. The constant voltage / constant frequency inverter 15 converts the DC power from the DC bus L1 into constant voltage / constant frequency AC power to supply the constant voltage / constant frequency auxiliary load 17. The variable voltage / variable frequency inverter 25 converts the DC power from the DC bus L2 into variable voltage / variable frequency AC power to supply the variable voltage / variable frequency auxiliary load 27. Both the constant voltage / constant frequency inverter 15 and the variable voltage / variable frequency inverter 25 can communicate with the controller 5. The controller 5 adjusts the output power of the constant voltage / constant frequency inverter 15 and the variable voltage / variable frequency inverter 25, thereby controlling the power supply to the constant voltage / constant frequency auxiliary load 17 and the variable voltage / variable frequency auxiliary load 27.

[0057] Optionally, based on the above embodiments, see below. Figure 2The electric drive system of this new energy locomotive also includes: a first switch unit 6, a second switch unit 8, and a third switch unit 7; the controller 5 is communicatively connected to the first switch unit 6, the second switch unit 8, and the third switch unit 7 respectively; one end of the first switch unit 6 is connected to the constant voltage and constant frequency inverter 15, and the other end is connected to the first auxiliary load 17; one end of the second switch unit 8 is connected to the variable voltage and variable frequency inverter 25, and the other end is connected to the second auxiliary load 27; one end of the third switch unit 17 is connected to the first auxiliary load 17, and the other end is connected to the second auxiliary load 27; the control module 5 is also used to control the first switch unit 6 to turn off and the second switch unit 8 and the third switch unit 7 to turn on when the first DC bus L1 fails; and to control the second switch unit 8 to turn off and the first switch unit 6 and the third switch unit 7 to turn on when the second DC bus L2 fails.

[0058] Specifically, the first switching unit 6, the second switching unit 8, and the third switching unit 7 can be contactor switching units, and are respectively communicatively connected to the controller 5. The controller 5 can determine whether the first power battery pack 12 and the second power battery pack 22 have malfunctioned based on the acquired power level, voltage, temperature, and health status. When the first power battery pack 12 malfunctions, the controller 5 can control the first switching unit 6 to turn off and the second switching unit 8 and the third switching unit 7 to turn on, thereby supplying power to the constant voltage and constant frequency auxiliary load 17 through the second power battery pack 22; or, when the second power battery pack 22 malfunctions, the controller 5 can control the second switching unit 8 to turn off and the first switching unit 6 and the third switching unit 7 to turn on, thereby supplying power to the variable voltage and variable frequency auxiliary load 27 through the first power battery pack 12. In the vehicle's stationary mode, the electric drive system of the new energy locomotive balances the power of the first power battery pack 12 and the second power battery pack 22 through the bidirectional voltage converter 3, which can avoid the wear of the contactors caused by frequent switching through the first switching unit 6, the second switching unit 8, and the third switching unit 7 for power balancing.

[0059] The electric drive system of the new energy locomotive can also be equipped with a fourth switching unit 4. The fourth switching unit 4 can be communicatively connected to the controller 5. The fourth switching unit 4 is located between the first DC bus L1 and the bidirectional voltage converter 3, or between the second DC bus L2 and the bidirectional voltage converter 3. For example, as... Figure 2 As shown, the fourth switch unit 4 is located between the first DC bus L1 and the bidirectional voltage converter 3. The fourth switch unit 4 can be turned on when the new energy locomotive is in stationary mode and turned off when the new energy locomotive is in running mode, so as to assist the bidirectional voltage converter 3 in maintaining the power balance between the first power battery pack 12 and the second power battery pack 22.

[0060] Figure 3This is a flowchart illustrating a control method for an electric drive system of a new energy locomotive, provided as an embodiment of the present invention. This method can be applied to the electric drive system of a new energy locomotive provided in any embodiment of the present invention. See also... Figure 3 The method includes:

[0061] S110: Obtain power information for the first and second power battery packs.

[0062] Specifically, the first power battery pack and the second power battery pack may each be equipped with a battery management unit. The battery management unit can obtain the power information of the first power battery pack and the second power battery pack in real time and transmit the obtained power information to the controller.

[0063] S120. Determine the power balance strategy based on power information and locomotive operating mode.

[0064] The power balancing strategy includes: when the locomotive is stationary, controlling the bidirectional voltage converter to conduct power balancing based on power information; and when the locomotive is running, adjusting the power of the first traction inverter and the second traction inverter based on power information to achieve power balancing.

[0065] Specifically, in stationary mode, the controller can control the bidirectional voltage converter to conduct, allowing electrical energy to flow from the battery pack with higher charge to the battery pack with lower charge, thus achieving power balance. When the new energy vehicle is in operating mode, the controller can adjust the power conversion power of the first and second traction inverters, so that the lower-charge battery pack releases less power during discharge, or charges the higher-charge battery pack with less power during charging, thereby achieving power balance.

[0066] Optionally, Figure 4 A flowchart illustrating a control method for an electric drive system of a new energy locomotive, provided as an embodiment of the present invention. Based on the above embodiment, see... Figure 4 The method includes:

[0067] S210: Obtain the charge, voltage, temperature, and health status of the first and second power battery packs.

[0068] Specifically, the power information can include data such as the charge, temperature, voltage, and health status of the first and second power battery packs. The battery management unit can acquire this data in real time and transmit it to the controller.

[0069] S220: Determine the power balance strategy based on power information and locomotive operating mode.

[0070] Optionally, Figure 5A flowchart illustrating a control method for an electric drive system of a new energy locomotive, provided as an embodiment of the present invention. Based on the above embodiment, see... Figure 5 The method includes:

[0071] S310: Obtain the charge, voltage, temperature, and health status of the first and second power battery packs.

[0072] S320. When the locomotive is in a stationary mode, if the difference between the charge of the first power battery pack and the charge of the second power battery pack is greater than a first threshold, and / or the charge of the first power battery pack is less than a second threshold, the bidirectional voltage converter is controlled to turn on.

[0073] Specifically, in static mode, when the charge difference between the first and second power battery packs exceeds a first threshold, it indicates a significant difference in charge between the battery packs, requiring active balancing. At this time, the controller activates the bidirectional voltage converter, allowing energy to flow from the battery pack with higher charge to the battery pack with lower charge, thus assisting the lower-charged battery pack in supplying power to the load, achieving charge balance. This can be understood as the higher-charged battery pack simultaneously supplying power to both the first and second auxiliary loads, thereby achieving charge balance. Alternatively, if the charge of the first power battery pack is below a second threshold, it indicates that the first power battery pack is in a low-charge state and needs to draw power from the second power battery pack for charging. This prevents the first power battery pack from over-discharging and extends its battery life, thus achieving charge balance.

[0074] Optionally, Figure 6 A flowchart illustrating a control method for an electric drive system of a new energy locomotive, provided as an embodiment of the present invention. Based on the above embodiment, see... Figure 6 The method includes:

[0075] S410: Obtain the charge, voltage, temperature, and health status of the first and second power battery packs.

[0076] S420: Determine whether the locomotive is in traction or braking operation mode.

[0077] Specifically, the controller can determine whether the locomotive is in traction or braking mode based on changes in its operating speed. When the locomotive speed remains within a certain speed range, it can be considered to be in traction mode; when the locomotive speed decreases significantly and falls below a certain speed threshold, it can be considered to be in braking mode.

[0078] S430. When the locomotive is in traction operation mode, if the charge of the first power battery pack is less than that of the second power battery pack, then while keeping the total output power unchanged, the power of the first traction inverter is reduced and the power of the second traction inverter is increased.

[0079] Specifically, the traction operation mode can be understood as the new energy locomotive being in a traction driving state. In the traction operation mode, when the charge of the first power battery pack is less than that of the second power battery pack, the controller can reduce the power of the first traction inverter and increase the power of the second traction inverter, thereby balancing the charge of the two battery packs while maintaining the total traction force unchanged.

[0080] S440. If the charge of the first power battery pack is greater than that of the second power battery pack, then while keeping the total output power unchanged, reduce the power of the second traction inverter and increase the power of the first traction inverter.

[0081] Specifically, in traction operation mode, when the charge of the first power battery pack is greater than that of the second power battery pack, the controller can reduce the power of the second traction inverter and increase the power of the first traction inverter, thereby balancing the charge of the two battery packs while keeping the total traction force constant.

[0082] S450: When the locomotive is in braking operation mode, if the charge of the first power battery pack is greater than that of the second power battery pack, the power of the first traction inverter shall be reduced.

[0083] Specifically, the braking operation mode can be understood as the state of the new energy vehicle braking before coming to a stop. At this time, the first traction motor and the second traction motor charge the first power battery pack and the second power battery pack. In the braking operation mode, when the charge of the first power battery pack is greater than that of the second power battery pack, the controller can reduce the power of the first traction inverter, so that the charge of the first power battery pack during braking is less than that of the second power battery pack, thereby balancing the charge of the two battery packs.

[0084] S460. If the charge of the second power battery pack is greater than that of the first power battery pack, then reduce the power of the second traction inverter.

[0085] Specifically, in braking operation mode, when the charge of the second power battery pack is greater than that of the first power battery pack, the controller can reduce the power of the second traction inverter, so that the charge of the second power battery pack during braking is less than that of the first power battery pack, thereby balancing the charge of the two battery packs.

[0086] Optionally, Figure 7A flowchart illustrating a control method for an electric drive system of a new energy locomotive, provided as an embodiment of the present invention. Based on the above embodiment, see... Figure 7 The method includes:

[0087] S510: Obtain the charge, voltage, temperature, and health status of the first and second power battery packs.

[0088] S520: Determine whether the first and second power battery packs are faulty based on their voltage, temperature, and health status.

[0089] Specifically, the controller can determine whether the power battery pack is faulty based on its voltage, temperature, and health status. If the voltage of the power battery pack exceeds a preset voltage value, or the temperature exceeds a preset temperature value, or the health status is below a preset health threshold, the power battery pack can be considered faulty; otherwise, the power battery pack is considered to be in normal condition.

[0090] S530 controls the first switching unit to turn off and the second and third switching units to turn on when the first power battery pack fails.

[0091] Specifically, when the first power battery pack fails, the controller can control the first switching unit to turn off and the second and third switching units to turn on, thereby supplying power to the constant voltage and constant frequency auxiliary load through the second power battery pack.

[0092] S540: When the second power battery pack fails, control the second switching unit to turn off and the first and third switching units to turn on.

[0093] Specifically, when the second power battery pack fails, the controller can control the second switching unit to turn off and the first and third switching units to turn on, thereby supplying power to the transformer-frequency auxiliary load through the first power battery pack.

[0094] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0095] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An electric drive system for a new energy locomotive, characterized in that, It includes a first DC bus, a second DC bus, a first power battery pack, a second power battery pack, a bidirectional voltage converter, and a controller; The first power battery pack is connected to the first traction motor and the first auxiliary load via the first DC bus; the second power battery pack is connected to the second traction motor and the second auxiliary load via the second DC bus; the bidirectional voltage converter is connected between the first DC bus and the second DC bus and is communicatively connected to the controller; The first DC bus is also connected to the first traction motor via the first traction inverter, and the second DC bus is also connected to the second traction motor via the second traction inverter; the controller is also communicatively connected to the first traction inverter and the second traction inverter. The controller is used to control the bidirectional voltage converter to perform power balancing, or to control the first traction inverter and the second traction inverter to perform power balancing, based on the locomotive's operating mode and the power information of the first power battery pack and the second power battery pack; wherein, the locomotive's operating mode includes a stationary mode and a running mode, and the power information includes the power level of the first power battery pack and the power level of the second power battery pack; The system comprises a first voltage conversion module, a second voltage conversion module, a constant voltage and constant frequency inverter, and a variable voltage and variable frequency inverter; the first auxiliary load includes a constant voltage and constant frequency auxiliary load, and the second auxiliary load includes a variable voltage and variable frequency auxiliary load. The first power battery pack is connected to the first DC bus through the first voltage conversion module, and is connected to the constant voltage and constant frequency auxiliary load through the constant voltage and constant frequency inverter; the second power battery pack is connected to the second DC bus through the second voltage conversion module, and is connected to the variable voltage and variable frequency auxiliary load through the variable voltage and variable frequency inverter. The system comprises a first switching unit, a second switching unit, and a third switching unit; the controller is communicatively connected to the first switching unit, the second switching unit, and the third switching unit, respectively. One end of the first switching unit is connected to the constant voltage and constant frequency inverter, and the other end is connected to the first auxiliary load; one end of the second switching unit is connected to the variable voltage and variable frequency inverter, and the other end is connected to the second auxiliary load; one end of the third switching unit is connected to the first auxiliary load, and the other end is connected to the second auxiliary load. The controller is also configured to, when the first DC bus fails, control the first switching unit to turn off and the second and third switching units to turn on; and when the second DC bus fails, control the second switching unit to turn off and the first and third switching units to turn on.

2. The electric drive system of the new energy locomotive according to claim 1, characterized in that, When the locomotive is in a stationary mode, the controller is configured to: control the bidirectional voltage converter to turn on when the difference between the charge of the first power battery pack and the charge of the second power battery pack exceeds a first threshold, and / or the charge of the first power battery pack is less than a second threshold.

3. The electric drive system of the new energy locomotive according to claim 1, characterized in that, The operating modes include traction operating mode and braking operating mode; When the locomotive is in traction operation mode, the controller is configured to: reduce the power of the second traction inverter when the charge of the first power battery pack is greater than the charge of the second power battery pack; or, reduce the power of the first traction inverter when the charge of the second power battery pack is greater than the charge of the first power battery pack. When the locomotive is in braking operation mode, the controller is configured to: reduce the power of the first traction inverter when the charge of the first power battery pack is greater than the charge of the second power battery pack; or, reduce the power of the second traction inverter when the charge of the second power battery pack is greater than the charge of the first power battery pack.

4. A control method for the electric drive system of a new energy locomotive, applied to the electric drive system of the new energy locomotive as described in any one of claims 1-3, characterized in that, include: Obtain power information for the first and second power battery packs; A power balancing strategy is determined based on the power information and the locomotive's operating mode. The power balancing strategy includes: when the locomotive is stationary, controlling the bidirectional voltage converter to turn on to perform power balancing based on the power information; When the locomotive is in operation, the power of the first traction inverter and the second traction inverter is adjusted according to the power information to balance the power.

5. The control method for the electric drive system of the new energy locomotive according to claim 4, characterized in that, Obtain power information for the first and second power battery packs, including: The battery pack's charge, voltage, temperature, and health status are obtained.

6. The control method for the electric drive system of the new energy locomotive according to claim 5, characterized in that, When the locomotive is in a stationary mode, the bidirectional voltage converter is controlled to turn on for power balancing based on the power information, including: If the difference between the charge of the first power battery pack and the charge of the second power battery pack is greater than a first threshold, and / or the charge of the first power battery pack is less than a second threshold, the bidirectional voltage converter is controlled to turn on.

7. The control method for the electric drive system of the new energy locomotive according to claim 5, characterized in that, The operating modes include traction operating mode and braking operating mode. Based on the power information, the power of the first traction inverter and the second traction inverter is adjusted to achieve power balance, including: When the locomotive is in traction operation mode, if the charge of the first power battery pack is less than that of the second power battery pack, then while keeping the total output power unchanged, the power of the first traction inverter is reduced and the power of the second traction inverter is increased. If the charge of the first power battery pack is greater than that of the second power battery pack, then while keeping the total output power unchanged, the power of the second traction inverter is reduced and the power of the first traction inverter is increased. When the locomotive is in braking operation mode, if the charge of the first power battery pack is greater than the charge of the second power battery pack, the power of the first traction inverter is reduced. If the charge of the second power battery pack is greater than that of the first power battery pack, then the power of the second traction inverter is reduced.

8. The control method for the electric drive system of the new energy locomotive according to claim 5, characterized in that, Also includes: Determine whether the first and second power battery packs are faulty based on their voltage, temperature, and health status: When the first power battery pack fails, the first switching unit is turned off and the second and third switching units are turned on. When the second power battery pack fails, the second switching unit is turned off, and the first switching unit and the third switching unit are turned on.

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