A towing system and a control method and device thereof

Abstract

The application provides a system and a control method and device thereof, and relates to the technical field of power electronic control. The system comprises a first power converter and a second power converter. The control method comprises the following steps: acquiring the output power of the first power converter and the second power converter in real time; determining the current charge-discharge power difference according to the current output power of the first power converter and the second power converter; when the current charge-discharge power difference is within a preset difference range, adjusting the current output power of the first power converter and the second power converter to the initial power; and when the current charge-discharge power difference is greater than the upper limit of the preset difference range, adjusting the current output power of the first power converter and the second power converter to 0. The application dynamically adjusts the current output power of the first power converter and the second power converter, avoids the imbalance of the charge-discharge power in the system, and improves the stability and flexibility of the system.

Description

Technical Field

[0001] The present invention relates to the field of power electronic control technology, and in particular to a towing system and its control method and device. Background Technology

[0002] In the fields of microgrids, energy storage systems, and power conversion systems (PCS), drag control is a key testing and energy management technology used to enable power exchange between electrical devices to verify system performance and improve operating efficiency.

[0003] Existing parallel-drive systems typically employ two sets of power converters, each connected to one of two sets of energy storage modules. A fixed power command is used to control one set of power converters to charge while the other discharges. This enables power exchange between the two sets of energy storage modules, or allows the energy storage modules to exchange power with the power grid via a transformer.

[0004] However, the power distribution of the power converters in the aforementioned paired-trailer system is based on preset fixed values ​​and remains unchanged during system operation. Therefore, the paired-trailer system cannot dynamically adjust its operating power according to the real-time operating status of the power converters, potentially causing the power difference between the two sets of power converters to exceed the expected range, leading to system instability or transformer overload. Furthermore, the lack of a real-time adjustment mechanism makes the paired-trailer system difficult to adapt to changes in the testing environment, such as power limitations of the energy storage module or grid fluctuations, thus affecting the stability and safety of the paired-trailer system. Summary of the Invention

[0005] This invention provides a towing system and its control method and apparatus, which avoids the imbalance of charging and discharging power in the towing system by dynamically adjusting the current output power of two sets of power converters, thereby improving the stability and flexibility of the towing system.

[0006] The first aspect of the present invention provides a control method for a towing system, the towing system comprising a first power converter and a second power converter connected in series; the control method for the towing system includes:

[0007] S1: When the first power converter and the second power converter are charging and discharging, the output power of the first power converter and the output power of the second power converter are acquired in real time.

[0008] S2: Determine the current charge / discharge power difference based on the current output power of the first power converter and the current output power of the second power converter;

[0009] S3: When the current charge / discharge power difference is within a preset difference range, adjust the current output power of the first power converter and the current output power of the second power converter to the initial power.

[0010] S4: When the current charge / discharge power difference is greater than the upper limit of the preset difference range, the current output power of the first power converter and the current output power of the second power converter are both adjusted to 0.

[0011] Optionally, before S1, the following is also included:

[0012] S0: When starting the first power converter and the second power converter for charging and discharging, the initial output power of the first power converter is adjusted to the initial power, and the initial output power of the second power converter is adjusted to the initial power.

[0013] Optionally, S0 includes:

[0014] S01: When the first power converter and the second power converter are started for charging and discharging, the current initial output power of the first power converter and the current initial output power of the second power converter are increased by a first preset power adjustment gradient until the current initial output power of the first power converter and the current initial output power of the second power converter are both the initial power.

[0015] Optionally, S3 includes:

[0016] S31: When the current charge / discharge power difference is within the preset difference range, the current output power of the first power converter and the current output power of the second power converter are adjusted by the second preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both the initial power.

[0017] Optionally, S31 includes:

[0018] S311: When the current charge / discharge power difference is within the preset difference range, the larger of the current output power of the first power converter and the current output power of the second power converter is determined as the first output power, the smaller of the two is determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter is determined as a high-power converter, and the power converter with the second output power among the first power converter and the second power converter is determined as a low-power converter;

[0019] S312: Reduce the first output power until the power difference between the current output power of the high-power converter and the second output power reaches the lower limit of the preset difference range;

[0020] S313: Adjust the first output power and the second output power respectively according to the second preset power adjustment gradient until the current output power of the high-power converter and the current output power of the low-power converter are both the initial power.

[0021] Optionally, S4 includes:

[0022] S41: When the current charge / discharge power difference is greater than the upper limit of the preset difference range, the current output power of the first power converter and the current output power of the second power converter are reduced by a third preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0023] Optionally, S41 includes:

[0024] S411: When the current charge / discharge power difference is greater than the upper limit of the preset difference range, the larger of the current output power of the first power converter and the current output power of the second power converter is determined as the first output power, the smaller of the two is determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter is determined as a high-power converter, and the power converter with the second output power among the first power converter and the second power converter is determined as a low-power converter;

[0025] S412: Reduce the first output power using the third preset power adjustment gradient;

[0026] S413: Reduce the second output power using the third preset power adjustment gradient;

[0027] S414: When the current output power of the low-power converter is greater than 0, return to execute S412 to S413 until the current output power of the low-power converter is 0;

[0028] S415: When the current output power of the low-power converter is 0 and the current output power of the high-power converter is greater than 0, return to execute S413 until the current output power of the high-power converter is 0.

[0029] Optionally, the towing system further includes a first energy storage module and a second energy storage module; the first power converter is connected to the first energy storage module; the second power converter is connected to the second energy storage module; the control method of the towing system further includes:

[0030] S5: Real-time acquisition of operating condition information of the first power converter, the second power converter, the first energy storage module, and the second energy storage module; the operating condition information includes operating voltage, operating current, and operating temperature;

[0031] S6: When it is determined, based on the operating condition information, that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, the current output power of the first power converter and the current output power of the second power converter are reduced by a fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0032] Optionally, S6 includes:

[0033] S61: When it is determined, based on the operating condition information, that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, the larger of the current output power of the first power converter and the current output power of the second power converter is determined as the first output power, the smaller of the two is determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter is determined as a high-power converter, and the power converter with the second output power among the first power converter and the second power converter is determined as a low-power converter;

[0034] S62: Reduce the first output power with the fourth preset power adjustment gradient until the current output power of the high-power converter reaches the second output power;

[0035] S63: Reduce the current output power of the first power converter and the current output power of the second power converter by the fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0036] Optionally, the towing system further includes a transformer; the AC terminals of the first power converter and the second power converter are both electrically connected to the primary side of the transformer, and the secondary side of the transformer is electrically connected to the mains power grid; one of the first power converter and the second power converter is a charging power converter, and the other is a discharging power converter; the control method of the towing system further includes:

[0037] S7: When the output power of the discharge power converter is greater than the output power of the charging power converter, control a portion of the output power of the discharge power converter to be converted by the transformer and then supplied to the mains power grid;

[0038] S8: Obtain the grid power value output by the discharge power converter to the mains power grid;

[0039] S9: When the grid power value is greater than the preset reverse current threshold, obtain the power difference between the grid power value and the preset reverse current threshold;

[0040] S10: Reduce the output power of the discharge power converter by the power difference.

[0041] A second aspect of the present invention provides a control device for a towing system, the towing system comprising a first power converter and a second power converter connected in series; the control device for the towing system includes:

[0042] The output power acquisition module is used to acquire the output power of the first power converter and the output power of the second power converter in real time when the first power converter and the second power converter are charging and discharging.

[0043] The current charge / discharge power difference determination module is used to determine the current charge / discharge power difference based on the current output power of the first power converter and the current output power of the second power converter.

[0044] The first current output power adjustment module is used to adjust the current output power of the first power converter and the current output power of the second power converter to the initial power when the current charge-discharge power difference is within a preset difference range.

[0045] The second current output power adjustment module is used to adjust the current output power of the first power converter and the current output power of the second power converter to 0 when the current charge-discharge power difference is greater than the upper limit of the preset difference range.

[0046] Optionally, a third aspect of the present invention provides a towing system, the towing system comprising: a controller, and a first power converter and a second power converter connected in series;

[0047] The controller is connected to the first power converter and the second power converter respectively, and the controller is used to execute the control method of the towing system as described above.

[0048] Optionally, the towing system further includes a transformer;

[0049] The AC terminals of the first power converter and the second power converter are both electrically connected to the primary side of the transformer, and the secondary side of the transformer is electrically connected to the mains power grid.

[0050] One of the first power converter and the second power converter is a charging power converter, and the other is a discharging power converter.

[0051] The technical solution of this invention achieves real-time monitoring of the operating status of the coupled system by acquiring the output power of the first power converter and the second power converter in real time. It also determines the current charge / discharge power difference based on the current output power of the first and second power converters, providing a data basis for dynamically adjusting their current output power. When the current charge / discharge power difference is within a preset range, both the current output power of the first and second power converters are adjusted to their initial power values. This reduces the current charge / discharge power difference to below the lower limit of the preset range, thereby preventing power imbalance in the coupled system, ensuring the safe operation of the transformer, improving the stability and flexibility of the coupled system, and enabling it to operate according to the preset initial charge / discharge power, ensuring accurate operation and improving the system's operating efficiency. Furthermore, by adjusting the current output power of both the first and second power converters to 0 when the current charge-discharge power difference exceeds the upper limit of the preset difference range, the power transmission of the towing system can be stopped in a timely manner when there is a serious imbalance in the charge-discharge power of the towing system. This effectively prevents transformer overload, mains power grid fluctuations, and damage to the energy storage module, ensuring the safe operation of the towing system and its equipment. At the same time, it improves the maintenance efficiency of the towing system and enhances its reliability and stability.

[0052] 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

[0053] 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.

[0054] Figure 1 This is a schematic diagram of the structure of a towing system provided by the present invention;

[0055] Figure 2 This is a flowchart illustrating a control method for a towing system provided by the present invention;

[0056] Figure 3 This is a flowchart illustrating another method for controlling a towing system provided by the present invention.

[0057] Figure 4 This is a flowchart illustrating another method for controlling a towing system provided by the present invention.

[0058] Figure 5 This is a flowchart illustrating another method for controlling a towing system provided by the present invention.

[0059] Figure 6 This is a schematic diagram of the structure of a control device for a towing system provided by the present invention. Detailed Implementation

[0060] 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.

[0061] 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.

[0062] Figure 1 This is a schematic diagram of the structure of a towing system provided by the present invention, as shown below. Figure 1 As shown, the towing system includes: a first power converter 11 and a second power converter 12 connected in series.

[0063] The first power converter 11 and the second power converter 12 constitute a power conversion system. The first power converter 11 and the second power converter 12 are connected in series to form a string power conversion system, used to achieve bidirectional power conversion between DC and AC. The first power converter 11 can be connected to the first energy storage module 21, and the second power converter 12 can be connected to the second energy storage module 22 to realize power transfer between the first energy storage module 21 and the second energy storage module 22. Specifically, the first energy storage module 21 and the second energy storage module 22 can be understood as energy storage devices for storing and releasing electrical energy. For example, the first energy storage module 21 and the second energy storage module 22 may include a battery pack and a battery management system. The battery management system is used to monitor parameters such as the state of charge, voltage, current, and temperature of the battery pack in real time to ensure the charging and discharging performance and safety of the battery pack.

[0064] Specifically, the control signal transmission terminal 111 of the first power converter 11 is communicatively connected to the control signal input terminal 211 of the first energy storage module 21, so that the first power converter 11 can control the first energy storage module 21 to charge or discharge according to its output power; the control signal transmission terminal 121 of the second power converter 12 is communicatively connected to the control signal input terminal 221 of the second energy storage module 22, so that the second power converter 12 can control the second energy storage module 22 to charge or discharge according to its output power.

[0065] One of the first power converter 11 and the second power converter 12 is a charging power converter, and the other is a discharging power converter. The AC terminal 113 of the first power converter 11 is electrically connected to the AC terminal 123 of the second power converter 12, enabling the parallel drive system to transfer electrical energy between the first energy storage module 21 and the second energy storage module 22 through DC-AC conversion or AC-DC conversion between the first power converter 11 and the second power converter 12. Unless otherwise specified, the embodiments of the present invention use the first power converter 11 as a discharging power converter and the second power converter 12 as a charging power converter as examples to exemplify the technical solution of the present invention.

[0066] The first power converter 11 can control the first energy storage module 21 to discharge at its output power, so that the DC signal stored in the first energy storage module 21 can be transmitted to the DC terminal 112 of the first power converter 11 through the charging / discharging terminal 212. The DC signal is converted from DC to AC by the first power converter 11 and transmitted to the AC terminal 123 of the second power converter 12 through the AC terminal 113 of the first power converter 11. The second power converter 12 converts the received AC signal from AC to DC and transmits it to the charging / discharging terminal 222 of the second energy storage module 22 at its output power through the DC terminal 122 of the second power converter 12, thereby realizing the storage of electrical energy output by the first energy storage module 21 by the second energy storage module 22.

[0067] In addition, the towing system also includes a transformer 3. The AC terminal 113 of the first power converter 11 and the AC terminal 123 of the second power converter 12 are both electrically connected to the primary side 31 of the transformer 3, and the secondary side 32 of the transformer 3 is electrically connected to the mains power grid 4.

[0068] It is understandable that during the operation of the towing system, there may be a difference in the output power of the first power converter 11 and the second power converter 12, resulting in an imbalance in the charging and discharging power of the first energy storage module 21 and the second energy storage module 22. To ensure the operational stability of the towing system, it is necessary to transmit AC signals between the mains power grid 4 and the towing system through the transformer 3 to ensure the balance of the charging and discharging power of the first energy storage module 21 and the second energy storage module 22. For example, when the discharge power of the first power converter 11 is greater than the charging power of the second power converter 12, the excess AC signal of the first power converter 11 can be output to the primary side 31 of the transformer 3 through the AC terminal 113 of the first power converter 11, and transmitted to the mains grid 4 via the secondary side 32 of the transformer 3. The mains grid 4 absorbs the excess AC signal output by the first energy storage module 21 to maintain the power balance of the traction system. When the charging power of the second power converter 12 is greater than the discharge power of the first power converter 11, the mains grid 4 can provide power to the secondary side 32 of the transformer 3, and transmit it to the AC terminal 123 of the second power converter 12 via the primary side 31 of the transformer 3, so as to supplement the power required by the second energy storage module 22 through the AC signal provided by the mains grid 4, so as to maintain the power balance of the traction system.

[0069] It is also understandable that when the power difference between the output power of the first power converter 11 and the output power of the second power converter 12 is too large, the AC signal transmitted through the transformer 3 may exceed its rated power, potentially causing the transformer 3 to overload, overheat, and lead to instability in the coupling system. Therefore, it is necessary to dynamically adjust the output power of the first power converter 11 and the second power converter 12 to maintain the power balance of the coupling system, ensure the safe operation of the transformer, and thus improve the stability and flexibility of the coupling system.

[0070] The towing system also includes a controller 5 connected to the first power converter 11 and the second power converter 12 respectively. Specifically, the control signal output terminal 51 of the controller 5 is communicatively connected to the control signal transmission terminal 111 of the first power converter 11 and the control signal transmission terminal 121 of the second power converter 12. For example, the controller 5 may include an energy management system (EMS), which can communicate with the first power converter 11 and the second power converter 12 via the Modbus TCP protocol. It is understood that the controller 5 in the towing system can execute the control method of the towing system provided in this embodiment of the invention, possessing the corresponding functional modules and beneficial effects of the method. Technical details not described in detail in this embodiment can be found in the control method of the towing system described in the following embodiments.

[0071] Figure 2 This is a flowchart illustrating a control method for a towing system provided by the present invention. This method can be used to control the towing system described in the above embodiments, and can be executed by a control device for the towing system. This device can be implemented in software and / or hardware, and is generally integrated into a controller. Correspondingly, as... Figure 2 As shown, the control method for the towing system may include:

[0072] S1: When the first power converter and the second power converter are charging and discharging, the output power of the first power converter and the output power of the second power converter are acquired in real time.

[0073] For example, when the first power converter is a discharge power converter and the second power converter is a charging power converter, the output power of the first power converter can be specifically understood as the output power of the AC terminal of the first power converter. The first power converter is used to control the first energy storage module to discharge using the output power of the first power converter. The output power of the second power converter can be specifically understood as the output power of the DC terminal of the second power converter. The second power converter is used to control the second energy storage module to charge using the output power of the second power converter, thereby enabling the second energy storage module to store the electrical energy output by the first energy storage module.

[0074] Specifically, the controller can acquire the output current of the first power converter and the second power converter in real time through the current signal acquisition module, and acquire the output voltage of the first power converter and the second power converter in real time through the voltage signal acquisition module, so as to realize the real-time acquisition of the output power of the first power converter and the output power of the second power converter. This enables real-time monitoring of the operating status of the towing system and provides a data basis for subsequently determining the power difference between the current output power of the first power converter and the current output power of the second power converter, and dynamically adjusting the current output power of the first power converter and the current output power of the second power converter.

[0075] S2: Determine the current charge / discharge power difference based on the current output power of the first power converter and the current output power of the second power converter.

[0076] Specifically, the charge / discharge power difference can be understood as the absolute value of the difference between the current discharge power of the first power converter and the current charging power of the second power converter. For example, when the current discharge power of the first power converter is greater than the current charging power of the second power converter, the charge / discharge power difference can be understood as the difference between the current discharge power of the first power converter and the current charging power of the second power converter; when the current discharge power of the first power converter is less than the current charging power of the second power converter, the charge / discharge power difference can be understood as the difference between the current charging power of the second power converter and the current discharge power of the first power converter; when the current discharge power of the first power converter is equal to the current charging power of the second power converter, the charge / discharge power difference is 0.

[0077] Specifically, after the controller acquires the output power of the first power converter and the second power converter in real time, it can also determine the current charge / discharge power difference based on the current output power of the first and second power converters. This current charge / discharge power difference reflects the degree of imbalance in energy transfer between the first and second energy storage modules in the towing system. This difference may be caused by differences in the state of charge of the energy storage modules, limitations of the battery management system, or losses in the towing system.

[0078] It is also understandable that a large difference between the current charging and discharging power may lead to transformer overload, overheating, and instability in the tandem system. Therefore, it is necessary to obtain the output power of the first power converter and the second power converter in real time through the controller, and determine the current charging and discharging power difference. This provides a data basis for dynamically adjusting the current output power of the first and second power converters, thereby improving the stability and flexibility of the tandem system. In addition, the maximum number of verifications of the current charging and discharging power difference can be preset in the controller. For example, the maximum number of verifications can be 60 times to reduce the computational burden on the controller and reduce the energy consumption of the tandem system.

[0079] S3: When the current charge / discharge power difference is within the preset difference range, adjust the current output power of the first power converter and the current output power of the second power converter to the initial power.

[0080] The preset difference range can be understood as the acceptable range of the current charge / discharge power difference. The preset difference range includes a lower limit and an upper limit. For example, the lower limit of the preset difference range can be 150kW, and the upper limit can be 350kW. It can be understood that when the current charge / discharge power difference is less than the lower limit of the preset difference range, it indicates that the output power of the first power converter and the second power converter are close to or have reached a balance. At this time, the system operates stably, and there is no need to adjust the output power of the first and second power converters. When the current charge / discharge power difference is greater than or equal to the lower limit of the preset difference range, and the current charge / discharge power difference is less than or equal to the upper limit of the preset difference range, it indicates that the current charge / discharge power difference is small but there is still a power imbalance. Dynamic adjustment of the output power of the first and second power converters is needed to reduce the current charge / discharge power difference to below the lower limit of the preset difference range. In addition, the preset difference range may include a dead zone range. The dead zone range is close to the lower limit of the preset difference range. When the current charge and discharge power difference is within the dead zone range, it can be considered that the current charge and discharge power difference is small enough. The controller will not trigger the adjustment of the current output power of the first power converter and the current output power of the second power converter to avoid frequent or unnecessary power changes and maintain the smooth power transmission to the towing system.

[0081] Specifically, after the controller determines the current charging and discharging power of the first and second power converters, it can compare the current charging and discharging power with a preset difference range. If the difference in current charging and discharging power is within the preset difference range, the controller adjusts the current output power of both the first and second power converters to their initial power. By adjusting the current output power of both the first and second power converters to their initial power, an imbalance in the charging and discharging power of the transmission system is avoided, ensuring the safe operation of the transformer and improving the stability and flexibility of the transmission system. Simultaneously, this allows the transmission system to operate according to the preset initial charging and discharging power, thereby ensuring accurate operation of the transmission system and improving its operating efficiency.

[0082] S4: When the current charge / discharge power difference is greater than the upper limit of the preset difference range, adjust the current output power of the first power converter and the current output power of the second power converter to 0.

[0083] Specifically, when the controller determines that the current charge and discharge power difference is greater than the upper limit of the preset difference range, it indicates that the difference between the current output power of the first power converter and the current output power of the second power converter is too large, and there is a serious imbalance in the charge and discharge power of the towing system. Therefore, the controller can adjust the current output power of both the first power converter and the current output power of the second power converter to 0 to ensure the safety of the towing system.

[0084] Understandably, when the difference between the current output power of the first power converter and the second power converter is too large, the electrical energy that needs to be transmitted through the transformer may exceed its rated power, potentially causing transformer overload, overheating, or equipment damage, and possibly causing power surges to the mains power grid, thus affecting the safety of the mains power grid. Simultaneously, excessive current charging and discharging power may cause over-discharging of the first energy storage module or overcharging of the second energy storage module, triggering the battery management system's protection, and even potentially damaging the battery pack. Therefore, by adjusting the current output power of both the first and second power converters to 0 through the controller, the power transmission to the towing system can be stopped in a timely manner, effectively preventing transformer overload, mains power grid fluctuations, and damage to the energy storage modules, extending the service life of the transformer and energy storage modules, and ensuring the safe operation of the towing system and all equipment. Furthermore, after adjusting the current output power of both the first power converter and the second power converter to 0, the controller can stop the operation of the first and second power converters, providing a safe maintenance environment for operators and facilitating timely troubleshooting of abnormal operating conditions of the towing system. This improves the maintenance efficiency of the towing system and enhances its reliability and stability.

[0085] In this embodiment, the real-time monitoring of the operating status of the coupled system is achieved by acquiring the output power of the first and second power converters. The current charge / discharge power difference is determined based on the current output power of the first and second power converters, providing a data basis for dynamically adjusting their current output power. When the current charge / discharge power difference is within a preset range, both the current output power of the first and second power converters are adjusted to their initial power values. This reduces the current charge / discharge power difference to below the lower limit of the preset range, thereby preventing power imbalance in the coupled system, ensuring the safe operation of the transformer, improving the stability and flexibility of the coupled system, and enabling the coupled system to operate according to the preset initial charge / discharge power, ensuring accurate operation and improving the system's operating efficiency. Furthermore, by adjusting the current output power of both the first and second power converters to 0 when the current charge-discharge power difference exceeds the upper limit of the preset difference range, the power transmission of the towing system can be stopped in a timely manner when there is a serious imbalance in the charge-discharge power of the towing system. This effectively prevents transformer overload, mains power grid fluctuations, and damage to the energy storage module, ensuring the safe operation of the towing system and its equipment. At the same time, it improves the maintenance efficiency of the towing system and enhances its reliability and stability.

[0086] Optional, Figure 3 This is a flowchart illustrating another control method for a towing system provided by the present invention, as shown below. Figure 3 As shown, before S1, it also includes:

[0087] S0: When starting the first power converter and the second power converter for charging and discharging, adjust the initial output power of the first power converter to the initial power, and adjust the initial output power of the second power converter to the initial power.

[0088] Specifically, when the first and second power converters are activated for charging and discharging to achieve power transfer between the first and second energy storage modules, the controller can adjust the initial output power of both the first and second power converters to their initial power levels. The initial power can be understood as the target output power of the first and second power converters preset according to actual needs. For example, the initial power can be automatically allocated to the first and second power converters by the controller, or it can be manually set via the controller's display module, such as a display screen.

[0089] It is understandable that by setting the initial power of the first power converter and the second power converter to the same value, so that the initial charging and discharging power difference between the first power converter and the second power converter is 0, the charging and discharging power balance of the parallel-drive system is ensured. This minimizes the transmission burden on the transformer and the supplementary demand of the mains power grid, and ensures that the first energy storage module and the second energy storage module charge and discharge at the expected power. It is also understandable that, provided that the initial charging and discharging power difference between the first power converter and the second power converter is less than the lower limit of a preset difference range, the initial power of the first power converter and the second power converter can also be slightly different. This allows the parallel-drive system to adapt to the different charging and discharging power requirements of the first energy storage module and the second energy storage module, improving the flexibility and robustness of the parallel-drive system.

[0090] Optionally, S0 includes:

[0091] S01: When starting the first power converter and the second power converter for charging and discharging, the current initial output power of the first power converter and the current initial output power of the second power converter are increased by a first preset power adjustment gradient until the current initial output power of the first power converter and the current initial output power of the second power converter are both the initial power.

[0092] Specifically, when adjusting the initial output power of the first power converter and the second power converter to their initial power levels via the controller, the initial output power of both the first and second power converters can be increased by a first preset power adjustment gradient to bring them to their initial power levels. The first preset power adjustment gradient can be understood as a fixed power increment for each adjustment when the initial output power of the first and second power converters is adjusted via the controller. This first preset power adjustment gradient can be determined according to actual needs, and the present invention does not impose specific limitations on it. For example, the first preset power adjustment gradient can be 200kW.

[0093] The controller first increases the initial output power of the first and second power converters by a first preset power adjustment gradient, so that the initial output power of the first power converter is increased by one first preset power adjustment gradient, and the initial output power of the second power converter is increased by one first preset power adjustment gradient. The adjustment order of the initial output power of the first and second power converters can be determined according to actual needs, and the present invention does not specifically limit it. For example, the current initial output power of the first power converter is increased to 200kW, and the current initial output power of the second power converter is increased to 200kW. Subsequently, the controller will acquire the current initial output power of the first power converter and the second power converter. When the current initial output power of both the first and second power converters has been correctly increased by one gradient, and the current initial output power of the first and second power converters has not yet reached the initial power, the controller will continue to increase the initial output power of the first and second power converters by a first preset power adjustment gradient, so that the initial output power of the first power converter is increased by another first preset power adjustment gradient, and the initial output power of the second power converter is increased by another first preset power adjustment gradient. For example, the current initial output power of the first power converter is increased to 400kW, and the current initial output power of the second power converter is increased to 400kW, until the current initial output power of the first and second power converters is increased by another first preset power adjustment gradient. Once the initial power is reached, the adjustment of the initial output power of the first power converter and the second power converter is stopped. When at least one of the initial output power of the first power converter and the second power converter fails to increase by a first preset power adjustment gradient, it indicates that there may be a fault in the tractor system. The controller will control the initial output power of the power converter whose current initial output power has failed to increase by a first preset power adjustment gradient back to the previous gradient value. For example, when the initial output power of the first power converter fails to increase from 200kW to 400kW, the controller will control the initial output power of the first power converter to return to 200kW and stop further adjustment of the initial output power of the first power converter and the second power converter to prevent the fault from expanding further and to provide conditions for the inspection and maintenance of the tractor system.

[0094] Understandably, the controller, by alternating between increasing the initial output power of the first power converter by a first preset power adjustment gradient and then increasing the initial output power of the second power converter by another first preset power adjustment gradient, ensures that the difference between the current initial output power of the first and second power converters remains within a small range—that is, the difference does not exceed one first preset power adjustment gradient. This avoids power imbalance in the charging and discharging system, improving its stability and flexibility. Simultaneously, by adjusting the initial output power of the first and second power converters with the first preset power adjustment gradient, the controller ensures stable power transmission between the first and second energy storage modules, preventing malfunctions caused by sudden changes in charging and discharging power and extending the lifespan of the energy storage modules.

[0095] It is also understandable that when increasing the initial output power of the first power converter and the second power converter with the first preset power adjustment gradient, the initial output power of the discharge power converter can be adjusted first, followed by the initial output power of the charging converter. This ensures sufficient power supply by first controlling the energy storage module to discharge through the discharge power converter, providing a stable power input for subsequent charging by the charging power converter, which conforms to the flow logic of power transmission. This avoids the increased burden on the mains power grid and voltage fluctuations that might occur if the initial output power of the discharge power converter is insufficient when the initial output power of the charging converter is increased first, thus ensuring the stability of power transmission in the drive system.

[0096] Optionally, S3 includes:

[0097] S31: When the current charge / discharge power difference is within a preset difference range, adjust the current output power of the first power converter and the current output power of the second power converter respectively with the second preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both the initial power.

[0098] Specifically, when the current charge / discharge power difference is within a preset difference range, it indicates that the current charge / discharge power difference is small but there is still a power imbalance. The controller can adjust the current output power of the first power converter and the current output power of the second power converter respectively with a second preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both at their initial power. This reduces the current charge / discharge power difference to below the lower limit of the preset difference range, while allowing the towing system to operate according to the preset initial charge / discharge power, thereby ensuring the accurate operation of the towing system and improving its operating efficiency. The second preset power adjustment gradient can be understood as a fixed power increment adjusted in a single operation when the controller adjusts the current output power of the first power converter and the second power converter. The second preset power adjustment gradient and the first preset adjustment gradient can be the same or different, and this invention does not specifically limit this. For example, the second preset power adjustment gradient can be 200kW.

[0099] Optionally, S31 includes:

[0100] S311: When the current charge / discharge power difference is within a preset difference range, the larger of the current output power of the first power converter and the current output power of the second power converter is determined as the first output power, and the smaller of the two is determined as the second output power. The power converter with the first output power among the first power converter and the second power converter is determined as a high-power converter, and the power converter with the second output power among the first power converter and the second power converter is determined as a low-power converter.

[0101] Specifically, when the controller adjusts the current output power of the first power converter and the current output power of the second power converter to the initial power, the current output power of the first power converter and the current output power of the second power converter are first compared. The larger of the two current output powers is determined as the first output power, and the smaller of the two current output powers is determined as the second output power. The power converter with the first output power is determined as a high-power converter, and the power converter with the second output power is determined as a low-power converter, thus providing a basis for the subsequent adjustment process.

[0102] S312: Reduce the first output power until the power difference between the current output power and the second output power of the high-power converter reaches the lower limit of the preset difference range.

[0103] Specifically, after determining the first output power and the second output power, the controller will reduce the first output power until the power difference between the current output power of the high-power converter and the second output power reaches the lower limit of the preset difference range. This will make the power difference between the current output power of the high-power converter and the current output power of the low-power converter smaller, thereby avoiding the imbalance of charging and discharging power in the tractor system. This will reduce the transmission burden on the transformer and the need for supplementary power from the mains grid, ensuring the stable power transmission of the tractor system.

[0104] S313: Adjust the first output power and the second output power respectively with the second preset power adjustment gradient until the current output power of the high-power converter and the current output power of the low-power converter are both the initial power.

[0105] Specifically, after the power difference between the current output power and the second output power of the high-power converter reaches the lower limit of the preset difference range, the controller can adjust the first output power and the second output power respectively with a second preset power adjustment gradient, so that the first output power adjusts by one second preset power adjustment gradient and the second output power adjusts by one second preset power adjustment gradient. The adjustment order of the first output power and the second output power can be determined according to actual needs. This invention does not limit this. For example, when the first output power is greater than the initial power and the second output power is less than the initial power, the first output power is reduced by 200kW and the second output power is increased by 200kW. Subsequently, the controller will acquire the current output power of the high-power converter and the low-power converter. When neither the current output power of the high-power converter nor the current output power of the low-power converter reaches its initial power, the controller will continue to adjust the first and second output powers respectively by a second preset power adjustment gradient. This will cause the first output power to adjust by another second preset power adjustment gradient, and the second output power to adjust by another second preset power adjustment gradient. For example, the first output power may decrease by 200kW again, and the second output power may increase by 200kW again, until the current output power of both the high-power converter and the low-power converter reaches their initial power, at which point the adjustment of the first and second output powers will cease. It can be understood that when the current output power of the high-power converter does not reach its initial power, and one of the current output powers of the low-power converter reaches its initial power while the other does not, the controller will only adjust the current output power of the converter that has not reached its initial power by the second preset power adjustment gradient.

[0106] Furthermore, once both the high-power converter and the low-power converter have reached their initial output power, the controller will continue to monitor the first and second output powers. This allows for timely dynamic adjustments to the current output powers of both converters when the current charge / discharge power difference exceeds or equals the lower limit of a preset range. This enables the timely detection and prevention of charge / discharge power imbalances in the traction system, reducing the transmission burden on the transformer and the need for grid power supplementation, thus improving the stability and flexibility of the traction system.

[0107] Understandably, by employing an alternating adjustment method of controlling the first output power to adjust to a second preset power adjustment gradient, and then controlling the second output power to adjust to a second preset power adjustment gradient, the controller ensures that during the adjustment of the first and second output power, the difference between the current output power of the first power converter and the second power converter always remains at the lower limit of the preset difference range. This avoids imbalance in the charging and discharging power of the towing system and improves the stability and flexibility of the towing system.

[0108] Optionally, S4 includes:

[0109] S41: When the current charge / discharge power difference is greater than the upper limit of the preset difference range, the current output power of the first power converter and the current output power of the second power converter are reduced by the third preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0110] Specifically, when the current charge / discharge power difference exceeds the upper limit of the preset difference range, it indicates that the difference between the current output power of the first power converter and the current output power of the second power converter is too large, resulting in a severe imbalance in the charge / discharge power of the tractor system. The controller can reduce the current output power of the first and second power converters with a third preset power adjustment gradient until both current output power of the first and second power converters is zero. This allows for timely cessation of power transmission in the tractor system, effectively preventing transformer overload, grid fluctuations, and damage to the energy storage module, extending the service life of the transformer and energy storage module, and ensuring the safe operation of the tractor system and all equipment. The third preset power adjustment gradient can be understood as a fixed power increment for a single adjustment when the controller adjusts the current output power of the first and second power converters. The third preset power adjustment gradient and the first preset adjustment gradient can be the same or different; this invention does not specifically limit this. For example, the third preset power adjustment gradient can be 200kW.

[0111] Optionally, S41 includes:

[0112] S411: When the current charge / discharge power difference is greater than the upper limit of the preset difference range, the larger of the current output power of the first power converter and the current output power of the second power converter is determined as the first output power, the smaller of the two is determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter is determined as a high-power converter, and the power converter with the second output power among the first power converter and the second power converter is determined as a low-power converter.

[0113] Specifically, when the controller adjusts the current output power of the first power converter and the current output power of the second power converter to 0, the current output power of the first power converter and the current output power of the second power converter are first compared. The larger of the two current output powers is determined as the first output power, and the smaller of the two current output powers is determined as the second output power. The power converter with the first output power is determined as a high-power converter, and the power converter with the second output power is determined as a low-power converter, thus providing a basis for the subsequent adjustment process.

[0114] S412: Reduce the first output power using the third preset power adjustment gradient.

[0115] Specifically, after determining the first output power and the second output power, the controller will reduce the first output power by a third preset power adjustment gradient.

[0116] S413: Reduce the second output power using the third preset power adjustment gradient.

[0117] Specifically, after reducing the first output power with a second preset power adjustment gradient, the second output power is reduced with a third preset power adjustment. This achieves the goal of prioritizing the adjustment of the output power of the high-power converter to reduce by one third preset power adjustment gradient, and then adjusting the output power of the low-power converter to reduce by one third preset power adjustment gradient. This allows the current charge-discharge power difference to be reduced by prioritizing the adjustment of the output power of the high-power converter, thus avoiding the continued increase in the current charge-discharge power difference caused by prioritizing the adjustment of the output power of the low-power converter. This alleviates the transmission burden on the transformer and the supplementary demand of the mains power grid. For example, after the first output power is reduced by 200kW, the second output power is adjusted to be reduced by 200kW.

[0118] S414: If the current output power of the low-power converter is greater than 0, return to execute S412 to S413 until the current output power of the low-power converter is 0.

[0119] Specifically, the controller will obtain the current output power of the low-power converter and the current output power of the high-power converter. When the current output power of the low-power converter is greater than 0, it indicates that the current output power of both the low-power converter and the high-power converter has not decreased to 0. The controller will continue to reduce the first output power by the third preset power adjustment gradient, and after reducing the first output power by the second preset power adjustment gradient, it will continue to reduce the second output power by the third preset power adjustment gradient. This will achieve the goal of prioritizing the adjustment of the output power of the high-power converter by one third preset power adjustment gradient, and then adjusting the output power of the low-power converter by one third preset power adjustment gradient again. For example, after the first output power is reduced by 200kW again, the second output power is adjusted to be reduced by 200kW again until the current output power of the low-power converter is 0, at which point the adjustment of the first output power will stop.

[0120] S415: When the current output power of the low-power converter is 0 and the current output power of the high-power converter is greater than 0, return to execute S413 until the current output power of the high-power converter is 0.

[0121] Specifically, when the current output power of the low-power converter is 0 and the current output power of the high-power converter is greater than 0, it indicates that the current output power of the low-power converter has decreased to 0, while the current output power of the high-power converter has not yet decreased to 0. In this case, only the current output power of the high-power converter needs adjustment. The controller will reduce the second output power by a third preset power adjustment gradient until the current output power of the high-power converter is 0. Furthermore, after adjusting the current output power of both the first and second power converters to 0, the controller can stop both converters, providing a safe maintenance environment for operators and facilitating timely troubleshooting of abnormal operating conditions in the towing system. This improves the maintenance efficiency, reliability, and stability of the towing system.

[0122] Understandably, by adopting an alternating adjustment method of controlling the first output power to adjust to a third preset power adjustment gradient and then controlling the second output power to adjust to a third preset power adjustment gradient, the controller ensures that the difference between the current output power of the first power converter and the second power converter will not further increase during the adjustment of the first output power and the second output power. At the same time, it avoids the failure of the first energy storage module and the second energy storage module due to sudden changes in charging and discharging power, thus extending the service life of the energy storage module.

[0123] Optional, Figure 4 This is a flowchart illustrating another control method for a towing system provided by the present invention, as shown below. Figure 4 As shown, the control method for the towing system also includes:

[0124] S5: Real-time acquisition of operating status information of the first power converter, the second power converter, the first energy storage module, and the second energy storage module.

[0125] The operating information includes operating voltage, operating current, and operating temperature.

[0126] Specifically, the controller can also acquire real-time operating condition information of the first power converter, the second power converter, the first energy storage module, and the second energy storage module. This operating condition information includes operating voltage, operating current, and operating temperature. The operating voltage can be understood as the AC or DC terminal voltage of the first and second power converters, and the battery pack voltage of the first and second energy storage modules. The operating current can be understood as the input or output current of the first and second power converters, and the charging and discharging current of the first and second energy storage modules. The operating temperature can be understood as the temperature of the heat sinks in the first and second power converters, and the battery pack temperature of the first and second energy storage modules. For example, the operating condition information of the first and second power converters can be monitored through a built-in monitoring module, and the operating condition information of the first and second energy storage modules can be monitored through a battery management system and transmitted to the controller. This allows the controller to analyze the operating condition information of the first power converter, the second power converter, the first energy storage module, and the second energy storage module and to detect any abnormalities.

[0127] S6: When it is determined, based on the operating condition information, that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, the current output power of the first power converter and the current output power of the second power converter are reduced by the fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0128] Specifically, when the controller determines, based on operating condition information, that at least one of the first power converter, second power converter, first energy storage module, and second energy storage module is malfunctioning—for example, when the operating voltage, operating current, or operating temperature of at least one of these components exceeds a safe range—the controller can issue an alarm and reduce the current output power of both the first and second power converters using a fourth preset power adjustment gradient until both are zero. This allows for timely cessation of power transmission in the towing system in case of a fault, preventing further escalation of the fault. After adjusting both the current output power of the first and second power converters to zero, the controller can stop their operation, providing a safe maintenance environment for operators and facilitating timely troubleshooting of abnormal operating conditions in the towing system. This improves the maintenance efficiency, reliability, and stability of the towing system. The fourth preset power adjustment gradient can be understood as a fixed power increment for a single adjustment when the current output power of the first and second power converters is adjusted by the controller. The fourth preset power adjustment gradient and the first preset adjustment gradient can be the same or different, and this invention does not specifically limit them. For example, the fourth preset power adjustment gradient can be 200kW.

[0129] Optionally, S6 includes:

[0130] S61: When it is determined, based on the operating condition information, that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, the larger of the current output power of the first power converter and the current output power of the second power converter is determined as the first output power, the smaller of the two is determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter is determined as the high-power converter, and the power converter with the second output power among the first power converter and the second power converter is determined as the low-power converter.

[0131] Specifically, when the controller adjusts the current output power of the first power converter and the current output power of the second power converter to 0, the current output power of the first power converter and the current output power of the second power converter are first compared. The larger of the two current output powers is determined as the first output power, and the smaller of the two current output powers is determined as the second output power. The power converter with the first output power is determined as a high-power converter, and the power converter with the second output power is determined as a low-power converter, thus providing a basis for the subsequent adjustment process.

[0132] S62: Reduce the first output power with the fourth preset power adjustment gradient until the current output power of the high-power converter reaches the second output power.

[0133] Specifically, after determining the first and second output powers, the controller will reduce the first output power by a fourth preset power adjustment gradient, reducing it by one fourth preset power adjustment gradient (e.g., a reduction of 200kW). Then, the controller will obtain the current output power of the high-power converter. If the current output power of the high-power converter has not reached the second output power, the controller will continue to reduce the first output power by the fourth preset power adjustment gradient, reducing it again by one fourth preset power adjustment gradient (e.g., another reduction of 200kW), until the current output power of the high-power converter reaches the second output power. It can be understood that when the difference between the current output power and the second output power is less than the fourth preset power adjustment gradient, the controller will reduce the first output power by the difference between them. By reducing the first output power to the second output power, the difference between the current output power of the first and second power converters is reduced to zero, thereby preventing further escalation of the towing system's faults and improving the safety and stability of the towing system. Meanwhile, by reducing the first output power with the fourth preset power adjustment gradient, the energy storage module corresponding to the high-power power converter is prevented from malfunctioning due to sudden changes in charging and discharging power.

[0134] S63: Reduce the current output power of the first power converter and the current output power of the second power converter by the fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0135] Specifically, after the current output power of the high-power converter reaches the second output power, the controller will reduce the current output power of the first power converter and the second power converter by a fourth preset power adjustment gradient, so that the current output power of the first power converter is reduced by a fourth preset power adjustment gradient, and the current output power of the second power converter is reduced by a fourth preset power adjustment gradient. The adjustment order of the current output power of the first power converter and the second power converter can be determined according to actual needs. This invention does not limit this. For example, the current output power of the first power converter is reduced by 200kW, and the current output power of the second power converter is reduced by 200kW. Subsequently, the controller will obtain the current output power of the first power converter and the current output power of the second power converter. When both the current output power of the first power converter and the current output power of the second power converter are greater than 0, the controller will continue to reduce the current output power of the first power converter and the current output power of the second power converter by a fourth preset power adjustment gradient, so that the current output power of the first power converter is reduced by another fourth preset power adjustment gradient, and the current output power of the second power converter is reduced by another fourth preset power adjustment gradient. For example, the current output power of the first power converter is reduced by 200kW and the current output power of the second power converter is reduced by 200kW, until the current output power of the first power converter and the current output power of the second power converter are both 0, and the adjustment of the current output power of the first power converter and the current output power of the second power converter is stopped.

[0136] Understandably, by employing an alternating adjustment method of reducing the current output power of the first power converter by a fourth preset power adjustment gradient and then reducing the current output power of the second power converter by a fourth preset power adjustment gradient, the controller ensures that the difference between the current output power of the first power converter and the current output power of the second power converter remains at 0 during the adjustment process. This avoids imbalance in the charging and discharging power of the towing system and improves the stability and flexibility of the towing system.

[0137] Optional, Figure 5 This is a flowchart illustrating another control method for a towing system provided by the present invention, as shown below. Figure 5 As shown, the control method for the towing system also includes:

[0138] S7: When the output power of the discharge power converter is greater than the output power of the charging power converter, control part of the output power of the discharge power converter to be converted by the transformer and then supplied to the mains power grid.

[0139] Specifically, when the output power of the discharge power converter is greater than the output power of the charging power converter, the controller will control part of the output power of the discharge power converter to be converted by the transformer and then supplied to the mains power grid, so as to absorb the excess electrical energy output by the discharge power converter through the mains power grid and maintain the power balance of the towing system.

[0140] S8: Obtain the grid power value output by the discharge power converter to the mains power grid.

[0141] Specifically, when a portion of the output power from the discharge power converter is converted by a transformer and supplied to the mains power grid, the controller can obtain the grid power value output by the discharge power converter to the mains power grid, that is, the power transmitted from the secondary side of the transformer to the mains power grid. When the power value output by the discharge power converter to the mains power grid is too high, it may exceed the absorption capacity of the mains power grid or exceed the maximum allowable reverse current power of the mains power grid. Therefore, it is necessary to monitor the grid power value in real time through the controller to determine whether the output power of the discharge power converter needs to be adjusted.

[0142] S9: When the grid power value is greater than the preset reverse current threshold, obtain the power difference between the grid power value and the preset reverse current threshold.

[0143] Specifically, after acquiring the grid power value in real time, the controller compares it with a preset reverse current threshold. This preset reverse current threshold can be understood as the maximum allowable output power to the grid, determined based on the grid connection protocol or the design of the parallel-drive system. When the grid power value exceeds the preset reverse current threshold, it indicates that the power output of the discharge power converter to the grid is too high, potentially causing grid voltage instability or exceeding the grid's maximum allowable output power. Therefore, the controller will obtain the power difference between the grid power value and the preset reverse current threshold to lay the foundation for subsequently reducing the output power of the discharge power converter.

[0144] S10: Reduce the output power of the discharge power converter by using the power difference.

[0145] Specifically, after determining the power difference between the grid power value and the preset reverse current threshold, the controller will reduce the output power of the discharge power converter by the power difference, so as to accurately reduce the grid power value output by the discharge power converter to the grid to the preset reverse current threshold. This avoids outputting excessive power to the grid, complies with the grid connection protocol of the grid, ensures the grid connection reliability and power transmission stability of the tractor system, and improves the stability and safety of the tractor system.

[0146] Furthermore, after reducing the output power of the discharge power converter by the power difference, the controller will continue to monitor the grid power value output by the discharge power converter to the mains power grid. This allows for timely dynamic adjustment of the discharge power converter's output power when the grid power value exceeds a preset reverse current threshold. This enables the timely detection and prevention of excessive power output from the tractor system to the mains power grid, improving the stability and flexibility of the tractor system.

[0147] Optional, Figure 6 This is a schematic diagram of a control device for a towing system provided by the present invention. This device can implement the control method for the towing system provided in the embodiments of the present invention. The device can be implemented by software and / or hardware, and is generally integrated into the controller of the towing system. Figure 6 As shown, the device includes: an output power acquisition module 10, a current charge / discharge power difference determination module 20, a first current output power adjustment module 30, and a second current output power adjustment module 40. The specific structure of the device is as follows:

[0148] The output power acquisition module 10 is used to acquire the output power of the first power converter and the second power converter in real time when the first power converter and the second power converter are charging and discharging.

[0149] The current charge / discharge power difference determination module 20 is used to determine the current charge / discharge power difference based on the current output power of the first power converter and the current output power of the second power converter.

[0150] The first current output power adjustment module 30 is used to adjust the current output power of the first power converter and the current output power of the second power converter to the initial power when the current charge and discharge power difference is within a preset difference range.

[0151] The second current output power adjustment module 40 is used to adjust the current output power of the first power converter and the current output power of the second power converter to 0 when the current charge-discharge power difference is greater than the upper limit of the preset difference range.

[0152] In an optional embodiment of the present invention, the output power acquisition module 10 may also be used to: adjust the initial output power of the first power converter to the initial power when the first power converter and the second power converter are started to charge and discharge, and adjust the initial output power of the second power converter to the initial power.

[0153] In an optional embodiment of the present invention, the output power acquisition module 10 may also be used to: when the first power converter and the second power converter are started to charge and discharge, increase the current initial output power of the first power converter and the current initial output power of the second power converter by a first preset power adjustment gradient until the current initial output power of the first power converter and the current initial output power of the second power converter are both the initial power.

[0154] In an optional embodiment of the present invention, the first current output power adjustment module 30 may also be used to: when the current charge-discharge power difference is within a preset difference range, adjust the current output power of the first power converter and the current output power of the second power converter respectively with a second power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both the initial power.

[0155] In an optional embodiment of the present invention, the first current output power adjustment module 30 may further be used to: when the current charge / discharge power difference is within a preset difference range, determine the larger of the current output power of the first power converter and the current output power of the second power converter as the first output power, and the smaller of the two as the second output power; determine the power converter with the first output power among the first power converter and the second power converter as a high-power converter, and determine the power converter with the second output power among the first power converter and the second power converter as a low-power converter; reduce the first output power until the power difference between the current output power of the high-power converter and the second output power reaches the lower limit of the preset difference range; and adjust the first output power and the second output power respectively with a second preset power adjustment gradient until the current output power of the high-power converter and the current output power of the low-power converter are both the initial power.

[0156] In an optional embodiment of the present invention, the second current output power adjustment module 40 may also be used to: when the current charge-discharge power difference is greater than the upper limit of a preset difference range, reduce the current output power of the first power converter and the current output power of the second power converter by a third preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

[0157] In an optional embodiment of the present invention, the second current output power adjustment module 40 may further be used to: when the current charge-discharge power difference is greater than the upper limit of a preset difference range, determine the larger of the current output power of the first power converter and the current output power of the second power converter as the first output power, and the smaller of the two as the second output power; determine the power converter with the first output power among the first power converter and the second power converter as a high-power converter, and determine the power converter with the second output power among the first power converter and the second power converter as a low-power converter; reduce the first output power with a third preset power adjustment gradient; reduce the second output power with a third preset power adjustment gradient; when the current output power of the low-power converter is greater than 0, return to the steps of reducing the first output power with the third preset power adjustment gradient to reducing the second output power with the third preset power adjustment gradient, until the current output power of the low-power converter is 0; when the current output power of the low-power converter is 0 and the current output power of the high-power converter is greater than 0, return to the steps of reducing the second output power with the third preset power adjustment gradient, until the current output power of the high-power converter is 0.

[0158] In an optional embodiment of the present invention, the second current output power adjustment module 40 may further be used to: acquire in real time the operating condition information of the first power converter, the second power converter, the first energy storage module, and the second energy storage module; the operating condition information includes operating voltage, operating current, and operating temperature; when it is determined, based on the operating condition information, that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, the current output power of the first power converter and the current output power of the second power converter are reduced by a fourth preset power adjustment gradient until both the current output power of the first power converter and the current output power of the second power converter are 0.

[0159] In an optional embodiment of the present invention, the second current output power adjustment module 40 may further be used to: when it is determined, based on the operating condition information, that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, determine the larger of the current output power of the first power converter and the current output power of the second power converter as the first output power, and the smaller of the two as the second output power; determine the power converter with the first output power among the first power converter and the second power converter as a high-power converter, and determine the power converter with the second output power among the first power converter and the second power converter as a low-power converter; reduce the first output power with a fourth preset power adjustment gradient until the current output power of the high-power converter reaches the second output power; reduce the current output power of the first power converter and the current output power of the second power converter with a fourth preset power adjustment gradient until both the current output power of the first power converter and the current output power of the second power converter are 0.

[0160] In an optional embodiment of the present invention, the second current output power adjustment module 40 may also be used to: when the output power of the discharge power converter is greater than the output power of the charging power converter, control a portion of the output power of the discharge power converter to be converted by a transformer and then supplied to the mains power grid; obtain the grid power value output by the discharge power converter to the mains power grid; when the grid power value is greater than a preset reverse current threshold, obtain the power difference between the grid power value and the preset reverse current threshold; and reduce the output power of the discharge power converter by the power difference.

[0161] The control device for the towing system described above can execute the control method for the towing system provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the method. Technical details not described in detail in this embodiment can be found in the control method for the towing system provided in any embodiment of the present invention.

[0162] Since the control device for the towing system described above is capable of executing the control method for the towing system in the embodiments of the present invention, those skilled in the art can understand the specific implementation and various variations of the control device for the towing system in this embodiment based on the control method for the towing system described in the embodiments of the present invention. Therefore, how the control device for the towing system implements the control method for the towing system in the embodiments of the present invention will not be described in detail here. Any device used by those skilled in the art to implement the control method for the towing system in the embodiments of the present invention falls within the scope of protection of this application.

[0163] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. 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 disclosed in this invention can be achieved, and this is not limited herein.

[0164] 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. A control method for a towing system, characterized in that, The towing system includes a first power converter and a second power converter connected in series; the control method of the towing system includes: S1: When the first power converter and the second power converter are charging and discharging, the output power of the first power converter and the output power of the second power converter are acquired in real time. S2: Determine the current charge / discharge power difference based on the current output power of the first power converter and the current output power of the second power converter; S3: When the current charge / discharge power difference is within a preset difference range, the current output power of the first power converter and the current output power of the second power converter are both adjusted to a preset initial power. S4: When the current charge / discharge power difference is greater than the upper limit of the preset difference range, the current output power of the first power converter and the current output power of the second power converter are both adjusted to 0. Wherein, S3 includes: S31: When the current charge / discharge power difference is within the preset difference range, the current output power of the first power converter and the current output power of the second power converter are adjusted by the second preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both the initial power. S31 includes: S311: When the current charge / discharge power difference is within the preset difference range, the larger of the current output power of the first power converter and the current output power of the second power converter is determined as the first output power, the smaller of the two is determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter is determined as a high-power converter, and the power converter with the second output power among the first power converter and the second power converter is determined as a low-power converter; S312: Reduce the first output power until the power difference between the current output power of the high-power converter and the second output power reaches the lower limit of the preset difference range; S313: Adjust the first output power and the second output power respectively according to the second preset power adjustment gradient until the current output power of the high-power converter and the current output power of the low-power converter are both the initial power.

2. The control method for the towing system according to claim 1, characterized in that, Before S1, it also includes: S0: When starting the first power converter and the second power converter for charging and discharging, the initial output power of the first power converter is adjusted to the initial power, and the initial output power of the second power converter is adjusted to the initial power.

3. The control method for the towing system according to claim 2, characterized in that, The S0 includes: S01: When the first power converter and the second power converter are started for charging and discharging, the current initial output power of the first power converter and the current initial output power of the second power converter are increased by a first preset power adjustment gradient until the current initial output power of the first power converter and the current initial output power of the second power converter are both the initial power.

4. The control method for the towing system according to claim 1, characterized in that, S4 includes: S41: When the current charge / discharge power difference is greater than the upper limit of the preset difference range, the current output power of the first power converter and the current output power of the second power converter are reduced by a third preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

5. The control method for the towing system according to claim 4, characterized in that, S41 includes: S411: When the current charge / discharge power difference is greater than the upper limit of the preset difference range, the larger of the current output power of the first power converter and the current output power of the second power converter is determined as the first output power, the smaller of the two is determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter is determined as a high-power converter, and the power converter with the second output power among the first power converter and the second power converter is determined as a low-power converter; S412: Reduce the first output power using the third preset power adjustment gradient; S413: Reduce the second output power using the third preset power adjustment gradient; S414: When the current output power of the low-power converter is greater than 0, return to execute S412 to S413 until the current output power of the low-power converter is 0; S415: When the current output power of the low-power converter is 0 and the current output power of the high-power converter is greater than 0, return to execute S413 until the current output power of the high-power converter is 0.

6. The control method for the towing system according to claim 1, characterized in that, The towing system further includes a first energy storage module and a second energy storage module; the first power converter is connected to the first energy storage module; the second power converter is connected to the second energy storage module; the control method of the towing system further includes: S5: Real-time acquisition of operating condition information of the first power converter, the second power converter, the first energy storage module, and the second energy storage module; the operating condition information includes operating voltage, operating current, and operating temperature; S6: When it is determined, based on the operating condition information, that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, the current output power of the first power converter and the current output power of the second power converter are reduced by a fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

7. The control method for the towing system according to claim 6, characterized in that, S6 includes: S61: When it is determined, based on the operating condition information, that at least one of the first power converter, the second power converter, the first energy storage module, and the second energy storage module is abnormal, the larger of the current output power of the first power converter and the current output power of the second power converter is determined as the first output power, the smaller of the two is determined as the second output power, and the power converter with the first output power among the first power converter and the second power converter is determined as a high-power converter, and the power converter with the second output power among the first power converter and the second power converter is determined as a low-power converter; S62: Reduce the first output power with the fourth preset power adjustment gradient until the current output power of the high-power converter reaches the second output power; S63: Reduce the current output power of the first power converter and the current output power of the second power converter by the fourth preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both 0.

8. The control method for the towing system according to claim 1, characterized in that, The towing system further includes a transformer; the AC terminals of the first power converter and the second power converter are both electrically connected to the primary side of the transformer, and the secondary side of the transformer is electrically connected to the mains power grid; one of the first power converter and the second power converter is a charging power converter, and the other is a discharging power converter; the control method of the towing system further includes: S7: When the output power of the discharge power converter is greater than the output power of the charging power converter, control a portion of the output power of the discharge power converter to be converted by the transformer and then supplied to the mains power grid; S8: Obtain the grid power value output by the discharge power converter to the mains power grid; S9: When the grid power value is greater than the preset reverse current threshold, obtain the power difference between the grid power value and the preset reverse current threshold; S10: Reduce the output power of the discharge power converter by the power difference.

9. A control device for a towing system, characterized in that, The towing system includes a first power converter and a second power converter connected in series; the control device for the towing system includes: The output power acquisition module is used to acquire the output power of the first power converter and the output power of the second power converter in real time when the first power converter and the second power converter are charging and discharging. The current charge / discharge power difference determination module is used to determine the current charge / discharge power difference based on the current output power of the first power converter and the current output power of the second power converter. The first current output power adjustment module is used to adjust the current output power of the first power converter and the current output power of the second power converter to a preset initial power when the current charge-discharge power difference is within a preset difference range. The second current output power adjustment module is used to adjust the current output power of the first power converter and the current output power of the second power converter to 0 when the current charge-discharge power difference is greater than the upper limit of the preset difference range. The step of adjusting the current output power of the first power converter and the current output power of the second power converter to a preset initial power includes: adjusting the current output power of the first power converter and the current output power of the second power converter respectively with a second preset power adjustment gradient until the current output power of the first power converter and the current output power of the second power converter are both the initial power. Adjusting the current output power of the first power converter and the second power converter respectively with a second preset power adjustment gradient until both the current output power of the first power converter and the current output power of the second power converter are the initial power includes: determining the larger of the current output power of the first power converter and the current output power of the second power converter as the first output power, determining the smaller of the two as the second output power, and determining the power converter with the first output power as a high-power converter and the power converter with the second output power as a low-power converter; reducing the first output power until the power difference between the current output power of the high-power converter and the second output power reaches the lower limit of the preset difference range; and adjusting the first output power and the second output power respectively with the second preset power adjustment gradient until both the current output power of the high-power converter and the current output power of the low-power converter are the initial power.

10. A towing system, characterized in that, include: The controller, and the first and second power converters connected in series; The controller is connected to the first power converter and the second power converter respectively, and the controller is used to execute the control method of the towing system as described in any one of claims 1-8.

11. The towing system according to claim 10, characterized in that, The towing system also includes a transformer; The AC terminals of the first power converter and the second power converter are both electrically connected to the primary side of the transformer, and the secondary side of the transformer is electrically connected to the mains power grid. One of the first power converter and the second power converter is a charging power converter, and the other is a discharging power converter.

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