A traction power hold control method, unit, device and vehicle for power switching

Abstract

This application relates to a traction power holding control method, unit, device, and vehicle during power supply switching. Before the vehicle reaches the phase-splitting zone, if a phase-splitting warning signal is received, the power battery system is controlled to supply power to the intermediate DC circuit in a manner matching the voltage of the intermediate DC circuit, and the rectifier is controlled to gradually reduce the power drawn from the grid. When the real-time traction power obtained is less than the preset power, the main circuit breaker is controlled to open and block the rectifier. After the main circuit breaker is opened, the power battery system maintains the voltage stability of the intermediate DC circuit until the grid voltage obtained after passing through the phase-splitting zone is greater than or equal to the preset voltage. In this application, by continuously supplying power to the vehicle during the phase-splitting period, the longitudinal impulse of the train caused by traction unloading is avoided, and the stability of vehicle operation is improved. At the same time, the phase-splitting accident caused by a sudden drop in speed on uphill sections is avoided, ensuring the safety and continuity of train operation.

Description

Technical Field

[0001] This application belongs to the field of traction power control technology, and in particular relates to a traction power holding control method, unit, equipment and vehicle during power supply switching. Background Technology

[0002] Electric locomotives rely on the overhead contact line for power supply. The contact line has phase separation zones at specific locations to isolate the phases of different power supply sections. When an electric locomotive passes through a phase separation zone, the main circuit breaker must be temporarily disconnected and the traction force unloaded. The locomotive will coast through the phase separation zone without power and then close the main circuit breaker again to restore power supply.

[0003] On flat sections, this coasting-through-phase method usually only causes a brief speed loss and has little impact on operation. However, when the locomotive travels on a long uphill slope and enters the phase separation zone, the traction unloading will cause the train speed to drop significantly, and may even cause longitudinal impulse, affecting the smoothness of operation and the comfort of passengers.

[0004] This problem is particularly prominent for heavy-haul trains. At the phase break points on steep uphill sections, trains need to coast through frequently. Each speed loss is difficult to recover in a short time, and the cumulative effect may cause the train's speed to fall below the critical value after passing through the phase break zone, making it unable to maintain normal climbing. In severe cases, it may even cause the train to stop in the phase break zone, i.e., a "phase break drop" accident. Such accidents not only disrupt railway transportation but may also damage critical facilities such as the overhead contact line and pantograph, posing significant safety hazards.

[0005] Therefore, how to avoid train jerk and speed drop caused by traction unloading during the phase transition of electric locomotives, especially on uphill sections, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this application is to provide a traction power holding control method, unit, device, and vehicle during power supply switching. The traction power holding control method, unit, device, and vehicle provided by this application, through the continuous power supply of the power battery system during the phase transition, avoids longitudinal impulse of the train caused by traction unloading, and improves the stability of vehicle operation. At the same time, it avoids phase loss accidents caused by sudden speed drop on uphill sections, and ensures the safety and continuity of train operation.

[0007] This application provides a traction power holding control method during power supply switching, applied to a vehicle traction system. The vehicle traction system includes a power battery system, a traction converter, a main circuit breaker, and a traction motor. The traction converter includes an intermediate DC circuit and a rectifier. The power battery system is electrically connected to the intermediate DC circuit, and the output terminal of the rectifier is electrically connected to the intermediate DC circuit. The main circuit breaker is located between the power grid and the rectifier. The method includes: If a phase break warning signal is received before the vehicle reaches the phase break zone, the power battery system is controlled to supply power to the intermediate DC circuit in a manner that matches the voltage of the intermediate DC circuit, and the rectifier is controlled to gradually reduce the power drawn from the grid so that the voltage of the intermediate DC circuit remains stable during the power supply switching process. The system acquires the vehicle's real-time traction power. When the acquired real-time traction power is less than the preset power, it controls the main circuit breaker to disconnect and block the rectifier. The preset power is set based on the maximum power supply of the power battery system. After the main circuit breaker is disconnected, the power battery system maintains the voltage stability of the intermediate DC circuit to drive the traction motor to continue working and maintain traction power output until the grid voltage obtained after passing through the phase-splitting zone is greater than or equal to the preset voltage.

[0008] Optionally, the vehicle traction system further includes a chopper boost circuit connected between the power battery system and the intermediate DC circuit. Controlling the power battery system to supply power to the intermediate DC circuit in a manner matching the voltage of the intermediate DC circuit includes: The power battery system is controlled to supply power to the intermediate DC circuit through the chopper boost circuit.

[0009] Optionally, the rectifier is a four-quadrant rectifier.

[0010] Optionally, the preset power is set based on the current maximum available power supply of the power battery system, which is determined based on at least one of the state of charge, temperature, or state of health of the power battery system.

[0011] Optionally, before receiving the over-phase warning signal, the method further includes: Receive mode selection instructions from the user; The step of controlling the power battery system to supply power to the intermediate DC circuit in a manner matching the voltage of the intermediate DC circuit if an over-phase warning signal is received includes: If the mode selection command and the over-phase warning signal have been received, the power battery system is controlled to supply power to the intermediate DC circuit in a manner that matches the voltage of the intermediate DC circuit.

[0012] Optionally, the step of "until the grid voltage obtained after passing through the phase-splitting zone is greater than or equal to a preset voltage" further includes: The main circuit breaker is controlled to close, and the rectifier is controlled to gradually increase the power drawn from the grid, while the power supply from the power battery system to the intermediate DC circuit is gradually reduced until the power battery system stops supplying power and the grid power supply is restored.

[0013] Optionally, the method further includes: The state of charge (SOC) of the power battery system is obtained. If the obtained SOC is less than a preset value, a prompt message is issued.

[0014] This application also provides a traction control unit applied to a vehicle traction system. The vehicle traction system includes a power battery system, a traction converter, a main circuit breaker, and a traction motor. The traction converter includes an intermediate DC circuit and a rectifier. The power battery system is electrically connected to the intermediate DC circuit, and the output terminal of the rectifier is electrically connected to the intermediate DC circuit. The main circuit breaker is disposed between the power grid and the rectifier. The traction control unit includes: The power supply switching module is used to control the power battery system to supply power to the intermediate DC circuit in a manner that matches the voltage of the intermediate DC circuit if a phase break warning signal is received before the vehicle reaches the phase break zone, and to control the rectifier to gradually reduce the power drawn from the grid so that the voltage of the intermediate DC circuit remains stable during the power supply switching process. The switching control module is used to obtain the real-time traction power of the vehicle. When the obtained real-time traction power is less than the preset power, the main circuit breaker is controlled to open and block the rectifier. The preset power is set based on the maximum power supply of the power battery system. The power supply module is used to maintain the voltage stability of the intermediate DC circuit by the power battery system after the main circuit breaker is disconnected, so as to drive the traction motor to continue to work and maintain the traction power output until the grid voltage obtained after passing through the phase split zone is greater than or equal to the preset voltage.

[0015] This application also provides a vehicle traction control device, including a vehicle traction system and a traction control unit as described above; The vehicle traction system includes a power battery system, a traction converter, a main circuit breaker, and a traction motor. The traction converter includes an intermediate DC circuit and a rectifier. The power battery system is electrically connected to the intermediate DC circuit; The output terminal of the rectifier is electrically connected to the intermediate DC circuit. The main circuit breaker is located between the power grid and the rectifier; The traction control unit is electrically connected to the power battery system, the rectifier, and the main circuit breaker, respectively.

[0016] This application also provides a vehicle including the vehicle traction control device as described above.

[0017] Compared with existing technologies, this application provides a traction power holding control method, unit, device, and vehicle during power supply switching. Before the vehicle reaches the phase-splitting zone, if a phase-splitting warning signal is received, the power battery system is controlled to supply power to the intermediate DC circuit in a manner matching the voltage of the intermediate DC circuit. The rectifier is also controlled to gradually reduce the power drawn from the grid to maintain a stable voltage in the intermediate DC circuit during power supply switching. The real-time traction power of the vehicle is obtained. When the obtained real-time traction power is less than a preset power, the main circuit breaker is controlled to open and block the rectifier. The preset power is set based on the maximum power supply of the power battery system. After the main circuit breaker is disconnected, the power battery system maintains the voltage stability of the intermediate DC circuit to drive the traction motor to continue working and maintain traction power output until the grid voltage obtained after passing through the phase break zone is greater than or equal to the preset voltage. In this application, by continuously supplying power to the power battery system during the phase break period, the longitudinal impulse of the train caused by the unloading of traction force is avoided, and the stability of vehicle operation is improved. At the same time, the phase break accident caused by the sudden drop in speed on the uphill section is avoided, ensuring the safety and continuity of train operation. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of a traction power holding control method during power supply switching disclosed in an embodiment of this application; Figure 2 This is a circuit diagram of the vehicle traction system disclosed in the embodiments of this application; Figure 3 This is a structural block diagram of a traction control unit disclosed in an embodiment of this application; Figure 4 This is a structural block diagram of a vehicle traction control device disclosed in an embodiment of this application. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to the other component.

[0022] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0023] like Figure 1 As shown, this application provides a traction power holding control method during power supply switching, applicable to, for example... Figure 2 The vehicle traction system 100 shown includes a power battery system 110, a traction converter 120, a main circuit breaker 130, and a traction motor 140. The traction converter 120 includes an intermediate DC circuit 121 and a rectifier 122. The power battery system 110 is electrically connected to the intermediate DC circuit 121, and the output terminal of the rectifier 122 is electrically connected to the intermediate DC circuit 121. The main circuit breaker 130 is located between the power grid and the rectifier 122. As a preferred embodiment, such as Figure 2 As shown, the vehicle traction system 100 adopts a multi-axis independent power supply and control architecture, specifically: the power battery system 110 includes four battery cabinets 111-1 to 111-4; the traction converter 120 includes four rectifiers 121-1 to 121-4 (such as four-quadrant rectifiers), four DC-DC converters 122-1 to 122-4, two intermediate DC circuits 123-1 to 123-2, and four inverters 124-1 to 124-4; correspondingly, four traction motors 140-1 to 140-4 are configured. The vehicle traction system 100 also includes a transformer 150 and four DC contactors 160-1 to 160-4. The first end of the main circuit breaker 130 is connected to the power grid, and the second end of the main circuit breaker 130 is connected to the first end of the primary winding of the transformer 150. The first winding of transformer 150 is connected to the input terminal of the first rectifier 121-1; the output terminal of the first battery cabinet 111-1 is connected to the input terminal of the first DC-DC converter 122-1 through the first DC contactor 160-1; the output terminals of the first rectifier 121-1 and the first DC-DC converter 122-1 are connected to the first input terminal of the first intermediate DC circuit 123-1. The second winding of transformer 150 is connected to the input terminal of the second rectifier 121-2; the output terminal of the second battery cabinet 111-2 is connected to the input terminal of the second DC-DC converter 122-2 through the second DC contactor 160-2; the output terminals of the second rectifier 121-2 and the second DC-DC converter 122-2 are connected to the second input terminal of the first intermediate DC circuit 123-1. The first output terminal of the first intermediate DC circuit 123-1 is connected to the first traction motor 140-1 through the first inverter 124-1; the second output terminal of the first intermediate DC circuit 123-1 is connected to the second traction motor 140-2 through the second inverter 124-2. The third winding of transformer 150 is connected to the input terminal of the third rectifier 121-3; the output terminal of the third battery cabinet 111-3 is connected to the input terminal of the third DC-DC converter 122-3 through the third DC contactor 160-3; the output terminals of the third rectifier 121-3 and the third DC-DC converter 122-3 are connected to the first input terminal of the second intermediate DC circuit 123-2. The fourth secondary winding of transformer 150 is connected to the input terminal of the fourth rectifier 121-4; the output terminal of the fourth battery cabinet 111-4 is connected to the input terminal of the fourth DC-DC converter 122-4 through the fourth DC contactor 160-4; the output terminals of the fourth rectifier 121-4 and the fourth DC-DC converter 122-4 are connected to the second input terminal of the second intermediate DC circuit 123-2. The first output terminal of the second intermediate DC circuit 123-2 is connected to the third traction motor 140-3 through the third inverter 124-3; the second output terminal of the second intermediate DC circuit 123-2 is connected to the fourth traction motor 140-4 through the fourth inverter 124-4.

[0024] The methods include: S11. If a phase break warning signal is received before the vehicle reaches the phase break zone, the power battery system is controlled to supply power to the intermediate DC circuit in a manner that matches the voltage of the intermediate DC circuit, and the rectifier is controlled to gradually reduce the power drawn from the grid so that the voltage of the intermediate DC circuit remains stable during the power supply switching process. In this embodiment, before the locomotive reaches the phase-splitting zone, the ground beacon or onboard equipment sends a phase-splitting warning signal to the traction control unit. Upon receiving this signal, the traction control unit immediately activates the power battery system, allowing it to inject electrical energy into the intermediate DC circuit of the traction converter through an appropriate power electronic interface. Simultaneously, it instructs the rectifier (usually a four-quadrant rectifier) ​​to gradually reduce the power absorbed from the overhead contact line. During this process, the traction control unit coordinates the power output of the power battery system and the rectifier according to the power command set by the traction handle, jointly meeting the current traction requirements of the train. Through the coordinated adjustment of the two, the voltage of the intermediate DC circuit is precisely controlled near the set value, avoiding voltage drops or overshoots caused by sudden grid interruptions.

[0025] This step utilizes the rapid response characteristics of the power battery to dynamically compensate for the power gap generated during the rectifier shutdown process, thereby achieving a smooth transition from grid power supply to battery power supply. This eliminates voltage fluctuations at the moment of traction unloading, ensures the stable operation of the inverter, and avoids longitudinal impulses caused by power interruption when the train passes through phase breaks, significantly improving operational stability.

[0026] S12. Obtain the real-time traction power of the vehicle. When the obtained real-time traction power is less than the preset power, control the main circuit breaker to disconnect and block the rectifier. The preset power is set based on the maximum power supply of the power battery system. In this embodiment, after the power battery intervenes to supply power, the traction control unit continuously monitors the real-time traction power of each axle or the entire vehicle. This real-time traction power is the actual response value to the power command set by the traction handle. The preset power is a threshold set based on the maximum power that the power battery system can continuously provide under the current state. This maximum power can be obtained by looking up a table using the battery mode characteristic curve. When the real-time traction power is detected to drop below this threshold, it indicates that the traction force required according to the traction handle command can now be fully borne independently by the power battery, without relying on the power grid. At this time, the traction control unit issues a command to disconnect the main circuit breaker, physically isolating the locomotive from the power grid, and simultaneously blocks the rectifier's pulses, causing it to stop working.

[0027] This step, through precise switching based on power criteria, ensures that the battery system will not fail due to overload at the moment of disconnection from the grid. It also prevents damage that may result from the rectifier continuing to operate in the absence of a grid. This achieves safe and reliable grid disconnection operation, protecting both the traction converter and the power battery, and laying a stable voltage foundation for the subsequent pure battery power supply phase.

[0028] S13. After the main circuit breaker is disconnected, the power battery system maintains the voltage stability of the intermediate DC circuit to drive the traction motor to continue working and maintain traction power output until the grid voltage obtained after passing through the phase separation zone is greater than or equal to the preset voltage.

[0029] In this embodiment, after the main circuit breaker is disconnected, the intermediate DC circuit of the traction converter is entirely supported by the power battery system. The traction control unit sends a set force to the traction motor according to the battery mode characteristic curve and the power command set by the traction handle. The battery mode characteristic curve is pre-calibrated based on parameters such as the state of charge, temperature, and health status of the power battery system, and is used to determine the maximum power and optimal power curve that the battery can safely and stably output under the current state. The battery system continuously supplies power according to this curve and the handle command, so that the locomotive maintains a stable and controllable power output when coasting in the phase-splitting zone, thereby maintaining the climbing speed. When the locomotive passes through the phase-splitting zone, the traction control unit detects that the contact network voltage has recovered and reached the normal range (greater than or equal to the preset voltage), and prepares to reconnect to the grid. During this period, the power battery always serves as the sole power source, strictly following the characteristic curve to supply power, which ensures the continuity of traction force and avoids battery over-discharge or overload.

[0030] This step utilizes the energy self-sufficiency characteristics of the energy storage system, combined with precise battery management, to independently drive the train in areas without electricity. This overcomes the shortcomings of traditional phase transitions, which must rely entirely on inertial coasting. It completely solves the risk of phase drop accidents caused by sudden speed drops when heavy-load trains cross phases on steep uphill slopes, significantly improving operational efficiency and safety. At the same time, because the traction force is always present and output is stable, the train's impulsive behavior is effectively suppressed, further optimizing the driver's and passengers' operating experience and comfort.

[0031] In one implementation embodiment, the traction control unit and the central control unit work together. The central control unit is responsible for energy management and control command issuance at the vehicle level, including calculating and issuing a set force based on the battery mode characteristic curve and the traction handle position. The traction control unit is responsible for executing specific power distribution and inverter control. In the over-phase power holding mode, the central control unit sends the traction force command calculated based on the battery characteristic curve and the handle position to the traction control unit. The traction control unit then controls the power output of the power battery system and the rectifier accordingly to achieve precise control of the traction force.

[0032] Compared with existing technologies, this application provides a traction power holding control method, unit, device, and vehicle during power supply switching. Before the vehicle reaches the phase-splitting zone, if a phase-splitting warning signal is received, the power battery system is controlled to supply power to the intermediate DC circuit in a manner matching the voltage of the intermediate DC circuit. The rectifier is also controlled to gradually reduce the power drawn from the grid to maintain a stable voltage in the intermediate DC circuit during power supply switching. The real-time traction power of the vehicle is obtained. When the obtained real-time traction power is less than a preset power, the main circuit breaker is controlled to open and block the rectifier. The preset power is set based on the maximum power supply of the power battery system. After the main circuit breaker is disconnected, the power battery system maintains the voltage stability of the intermediate DC circuit to drive the traction motor to continue working and maintain traction power output until the grid voltage obtained after passing through the phase break zone is greater than or equal to the preset voltage. In this application, by continuously supplying power to the power battery system during the phase break period, the longitudinal impulse of the train caused by the unloading of traction force is avoided, and the stability of vehicle operation is improved. At the same time, the phase break accident caused by the sudden drop in speed on the uphill section is avoided, ensuring the safety and continuity of train operation.

[0033] As one implementation, in this embodiment of the application, the vehicle traction system further includes a chopper boost circuit (not shown in the figures), which is connected between the power battery system and the intermediate DC circuit. The chopper boost circuit controls the power battery system to supply power to the intermediate DC circuit in a manner that matches the voltage of the intermediate DC circuit, including: controlling the power battery system to supply power to the intermediate DC circuit through the chopper boost circuit.

[0034] In this embodiment, since the rated voltage of the power battery system is usually much lower than the operating voltage of the intermediate DC circuit of the traction converter (for example, the rated voltage of the power battery is DC 600V-1000V, while the voltage of the intermediate DC circuit may be as high as DC 1800V-3000V), it cannot directly supply power to the intermediate DC circuit. Therefore, a chopper boost circuit is set between the power battery system and the intermediate DC circuit. This circuit uses high-frequency power switching devices (such as IGBTs) and energy storage inductors to form a boost topology. When power from the power battery is needed, the traction control unit sends a pulse width modulation (PWM) control signal to the chopper boost circuit. By controlling the duty cycle of the power switch, the low-voltage DC power from the power battery is boosted to a stable DC power that matches the voltage of the intermediate DC circuit, thereby achieving electrical matching and energy transfer between the two. This circuit also has bidirectional energy flow capability. After the grid power supply is restored, the energy from the intermediate DC circuit can be recharged back to the power battery system through the chopper circuit.

[0035] This implementation method solves the technical problem of voltage level mismatch between the power battery and the traction converter by using high-frequency chopper boost technology, ensuring that the power battery can reliably supply power to the intermediate DC circuit. On the one hand, it achieves electrical isolation and matching between the power battery and the high-voltage traction system, ensuring equipment safety; on the other hand, through precise PWM control, it can quickly respond to voltage fluctuations in the intermediate DC circuit, maintain voltage stability, and provide reliable support for power maintenance during train phase transitions.

[0036] In one embodiment of this application, the rectifier is a four-quadrant rectifier.

[0037] In this embodiment, the four-quadrant rectifier is an AC-DC converter capable of bidirectional energy flow. Its core advantage lies in enabling the traction converter to operate normally in four quadrants (i.e., combinations of positive and negative voltage and current). Under traction conditions, the four-quadrant rectifier rectifies the single-phase AC power from the contact network into stable DC power to supply the intermediate DC circuit. Under regenerative braking conditions, it inverts the DC power from the intermediate DC circuit back into single-phase AC power to the contact network, achieving energy regeneration. In the phase-splitting control method of this application, the four-quadrant rectifier gradually reduces the power drawn from the grid after receiving a warning signal. This process is achieved by controlling the firing angle or PWM modulation wave of the power switching devices inside the rectifier, so that the input current amplitude decreases smoothly rather than being interrupted instantaneously.

[0038] This implementation utilizes the controllable power regulation capability of a four-quadrant rectifier to achieve a smooth power transition during grid power withdrawal, avoiding the shortcomings of traditional diode rectifier circuits that cannot control energy flow or smoothly regulate power. It creates stable transition conditions for the power battery system to intervene in power supply, effectively suppresses voltage fluctuations in the intermediate DC circuit, and retains the ability to regenerate braking energy feedback, thereby improving the overall energy efficiency of the system.

[0039] As one implementation method, in this embodiment of the application, the preset power is set based on the current maximum available power supply of the power battery system, and the current maximum available power supply is determined based on at least one of the state of charge, temperature or health status of the power battery system.

[0040] In this embodiment, the actual power supply capacity of the power battery system is not a constant value, but changes dynamically with changes in its internal state. Therefore, the traction control unit monitors key parameters in real time, such as the battery's state of charge (SOC, i.e., remaining percentage of charge), temperature, and state of health (SOH, i.e., the ratio of the battery's current capacity to its factory-rated capacity). Based on these parameters, it calculates the maximum usable power that the battery can safely and stably output at the current moment. For example, when the SOC is low, the battery's internal resistance increases, and the usable power will decrease accordingly; when the temperature is too low or too high, the traction control unit will also actively limit the maximum output power to protect the battery's lifespan; as the battery's service life increases and the SOH decreases, its maximum power supply capacity will gradually decline. The traction control unit sets this dynamically calculated maximum usable power supply as a preset power threshold.

[0041] This implementation feeds back the real-time status of the battery to the control logic, matching the switching criteria with the actual power supply capacity. This avoids overload, undervoltage, or protective shutdown caused by changes in battery status, ensuring that the power battery always supplies power within its safe and reliable operating range during phase transitions. This not only guarantees the continuity of traction power but also extends the service life of the battery system, improving the reliability and adaptability of the entire system.

[0042] As one implementation method, in this embodiment of the application, before receiving the over-phase warning signal, the method further includes: S21. Receive the mode selection command input by the user; In this embodiment, the microcomputer display screen in the locomotive driver's cab provides a human-machine interface. The driver and passengers can select whether to engage the "over-phase power holding mode" via the touch screen or function buttons. When the driver confirms the selection of the mode, the microcomputer display screen generates a corresponding mode selection command and sends it to the traction control unit via the train communication network (such as MVB bus or CAN bus). After receiving the command, the traction control unit sets the corresponding mode flag bit in its internal register, indicating that the locomotive has now enabled the over-phase power holding function.

[0043] This implementation grants drivers and passengers the option to choose the phase-crossing control mode through a human-machine interface, allowing them to flexibly decide whether to activate the power-holding function based on actual operating conditions (such as track gradient, load conditions, and remaining battery power). On the one hand, in scenarios where power-holding is not required (such as phase-crossing on straight roads), the function can be turned off to avoid unnecessary battery power consumption. On the other hand, the function can be activated in critical scenarios such as heavy-load uphill climbing, fully leveraging the technical advantages of this invention and improving the applicability and flexibility of the system.

[0044] If an over-phase warning signal is received, the power battery system is controlled to supply power to the intermediate DC circuit in a manner that matches the voltage of the intermediate DC circuit, including: if a mode selection command has been received and an over-phase warning signal has been received, the power battery system is controlled to supply power to the intermediate DC circuit in a manner that matches the voltage of the intermediate DC circuit.

[0045] In this embodiment, the control logic inside the traction control unit can adopt an AND gate judgment mechanism: the control process of the power battery system intervening in power supply will only be triggered when both the "mode selection command has been received (i.e., the mode has been engaged)" and the "over-phase warning signal has been received" are met simultaneously. If only the over-phase warning signal is received but the mode selection command is not set (i.e., the driver has not selected to engage the function), the traction control unit will still execute according to the traditional over-phase logic, that is, the rectifier will be blocked, the main circuit breaker will be disconnected, the train will enter the coasting state, and the power battery system will not intervene in power supply.

[0046] This implementation method uses the driver's and passengers' operational intentions as the enabling conditions for the control process, achieving an organic combination of human selection and automatic control. This ensures the consistency between the control logic and the driver's operational intentions, avoiding operational accidents or driver maladaptation that may be caused by the automatic intervention of the traction control unit. At the same time, this dual-condition triggering control mechanism also adds redundant judgment to the system, preventing the power battery system from being mistakenly engaged due to a single signal mis-triggering, further improving the reliability and safety of the system.

[0047] As one implementation method, in this embodiment of the application, after the grid voltage obtained after passing through the phase-splitting zone is greater than or equal to the preset voltage, the method further includes: S31. Control the main circuit breaker to close and control the rectifier to gradually increase the power drawn from the grid, while gradually reducing the power supply from the power battery system to the intermediate DC circuit until the power battery system stops supplying power and the grid power supply is restored.

[0048] In this embodiment, after the locomotive has completely passed the phase-splitting zone, the contact network voltage gradually returns to the normal range. The traction control unit continuously monitors the network voltage. When the network voltage is detected to be greater than or equal to the preset recovery threshold (e.g., 90% of the rated voltage), the grid restoration process is automatically initiated. First, the traction control unit issues a command to close the main circuit breaker, enabling the traction converter to re-establish electrical connection with the contact network. Subsequently, the traction control unit, on the one hand, commands the rectifier (four-quadrant rectifier) ​​to gradually increase the power drawn from the grid according to the set slope, and on the other hand, simultaneously commands the power battery system to gradually reduce the discharge power to the intermediate DC circuit through the chopper boost circuit. During this process, the power changes of the two form a dynamic complementarity: the power increased by the rectifier and the power reduced by the power battery always remain basically equal, thereby ensuring that the total input power of the intermediate DC circuit is stable and without fluctuations. The traction motor continues to operate stably according to the power command set by the traction handle. When the discharge power of the power battery system gradually decreases to zero, the battery stops supplying power, and the train fully returns to the normal operating state powered by the grid.

[0049] This implementation achieves a smooth transition from battery power to grid power through coordinated power regulation of the rectifier and the power battery system. This avoids voltage fluctuations and traction impacts in the intermediate DC circuit caused by sudden power changes during grid connection, further improving the stability of train operation. At the same time, the power battery system gradually reduces its output in a controlled manner during the disconnection process, preventing sudden voltage spikes or system overvoltages that may be caused by sudden load disconnection, thus protecting the safety of the battery and converter equipment.

[0050] As one implementation method, in this embodiment of the application, the method further includes: S41. Obtain the state of charge of the power battery system. If the obtained state of charge is less than the preset value, issue a prompt message.

[0051] In this embodiment, the traction control unit continuously monitors the state of charge (SOC, i.e., remaining percentage of charge) of the power battery system during train operation. When the SOC is detected to be lower than a preset threshold (e.g., 20%), it indicates that the remaining battery charge is insufficient to support a complete phase-break power holding process or multiple consecutive phase-break requirements. At this time, the traction control unit issues visual and / or auditory prompts to the driver and passengers through the microcomputer display screen, such as a warning window popping up on the display screen, a status indicator flashing, or a buzzer sounding, indicating "Insufficient power battery charge, phase-break power holding function may be limited" or "Please charge in time". The prompt information may include the current SOC value, the expected number of phase breaks that can be supported, and suggested operating instructions, etc.

[0052] This implementation method feeds back battery status information to the human-machine interface in real time, enabling drivers and passengers to understand the availability of the power battery system and take appropriate measures. On the one hand, it avoids the failure of the power holding function during subsequent phase transitions due to battery depletion, thereby preventing phase transition accidents. On the other hand, it provides drivers and passengers with decision-making basis, allowing them to rationally plan operating strategies based on the remaining battery power (such as reducing traction power, charging in advance, etc.), improving the safety and availability of the system. At the same time, this prompting function also helps to detect battery system abnormalities in a timely manner (such as excessively rapid SOC drop), providing early warning information for equipment maintenance.

[0053] like Figure 3 As shown in the illustration, this application also provides a traction control unit 200, applied to a vehicle traction system. The vehicle traction system includes a power battery system, a traction converter, a main circuit breaker, and a traction motor. The traction converter includes an intermediate DC circuit and a rectifier. The power battery system is electrically connected to the intermediate DC circuit, and the output terminal of the rectifier is electrically connected to the intermediate DC circuit. The main circuit breaker is located between the power grid and the rectifier. The traction control unit 200 includes: The power supply switching module 210 is used to control the power battery system to supply power to the intermediate DC circuit in a manner that matches the voltage of the intermediate DC circuit if a phase break warning signal is received before the vehicle travels to the phase break zone, and to control the rectifier to gradually reduce the power drawn from the grid so that the voltage of the intermediate DC circuit remains stable during the power supply switching process. The switching control module 220 is used to obtain the real-time traction power of the vehicle. When the obtained real-time traction power is less than the preset power, the main circuit breaker is controlled to open and block the rectifier. The preset power is set based on the maximum power supply of the power battery system. The power supply module 230 is used to maintain the voltage stability of the intermediate DC circuit by the power battery system after the main circuit breaker is disconnected, so as to drive the traction motor to continue to work and maintain the traction power output until the grid voltage obtained after passing through the phase separation zone is greater than or equal to the preset voltage.

[0054] like Figure 2 and Figure 4As shown, this application also provides a vehicle traction control device, including a vehicle traction system 100 and a traction control unit 200 as described above; the vehicle traction system 100 includes a power battery system 110, a traction converter 120, a main circuit breaker 130, and a traction motor 140; the traction converter 1200 includes an intermediate DC circuit 121 and a rectifier 122; the power battery system 110 is electrically connected to the intermediate DC circuit 121; the output terminal of the rectifier 122 is electrically connected to the intermediate DC circuit 121; the main circuit breaker 130 is disposed between the power grid and the rectifier 122; the traction control unit 200 is electrically connected to the power battery system 110, the rectifier 122, and the main circuit breaker 130 respectively.

[0055] In this embodiment, the traction control unit is used to control the power supply of the power battery system, the start and stop of the rectifier and power regulation, and the on and off of the main circuit breaker.

[0056] This application also provides a vehicle including the vehicle traction control device as described above.

[0057] The above description is merely an embodiment of the present invention. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of the present invention, but these improvements all fall within the protection scope of the present invention.

Claims

1. A traction power holding control method during power supply switching, characterized in that, An application is made to a vehicle traction system, the vehicle traction system including a power battery system, a traction converter, a main circuit breaker, and a traction motor. The traction converter includes an intermediate DC circuit and a rectifier, wherein the power battery system is electrically connected to the intermediate DC circuit, the output terminal of the rectifier is electrically connected to the intermediate DC circuit, and the main circuit breaker is disposed between the power grid and the rectifier. The method includes: If a phase break warning signal is received before the vehicle reaches the phase break zone, the power battery system is controlled to supply power to the intermediate DC circuit in a manner that matches the voltage of the intermediate DC circuit, and the rectifier is controlled to gradually reduce the power drawn from the grid so that the voltage of the intermediate DC circuit remains stable during the power supply switching process. The system acquires the vehicle's real-time traction power. When the acquired real-time traction power is less than the preset power, it controls the main circuit breaker to disconnect and block the rectifier. The preset power is set based on the maximum power supply of the power battery system. After the main circuit breaker is disconnected, the power battery system maintains the voltage stability of the intermediate DC circuit to drive the traction motor to continue working and maintain traction power output until the grid voltage obtained after passing through the phase-splitting zone is greater than or equal to the preset voltage.

2. The method according to claim 1, characterized in that, The vehicle traction system further includes a chopper boost circuit connected between the power battery system and the intermediate DC circuit. Controlling the power battery system to supply power to the intermediate DC circuit in a manner matching the voltage of the intermediate DC circuit includes: The power battery system is controlled to supply power to the intermediate DC circuit through the chopper boost circuit.

3. The method according to claim 1, characterized in that, The rectifier is a four-quadrant rectifier.

4. The method according to claim 1, characterized in that, The preset power is set based on the current maximum available power supply of the power battery system, which is determined based on at least one of the state of charge, temperature, or health status of the power battery system.

5. The method according to any one of claims 1 to 4, characterized in that, Before receiving the over-phase warning signal, the method further includes: Receive mode selection instructions from the user; The step of controlling the power battery system to supply power to the intermediate DC circuit in a manner matching the voltage of the intermediate DC circuit if an over-phase warning signal is received includes: If the mode selection command and the over-phase warning signal have been received, the power battery system is controlled to supply power to the intermediate DC circuit in a manner that matches the voltage of the intermediate DC circuit.

6. The method according to any one of claims 1 to 4, characterized in that, The process of obtaining a grid voltage greater than or equal to a preset voltage after passing through the phase-splitting zone further includes: The main circuit breaker is controlled to close, and the rectifier is controlled to gradually increase the power drawn from the grid, while the power supply from the power battery system to the intermediate DC circuit is gradually reduced until the power battery system stops supplying power and the grid power supply is restored.

7. The method according to any one of claims 1 to 4, characterized in that, The method further includes: The state of charge (SOC) of the power battery system is obtained. If the obtained SOC is less than a preset value, a prompt message is issued.

8. A traction control unit, characterized in that, This system is applied to a vehicle traction system, which includes a power battery system, a traction converter, a main circuit breaker, and a traction motor. The traction converter includes an intermediate DC circuit and a rectifier. The power battery system is electrically connected to the intermediate DC circuit, and the output terminal of the rectifier is electrically connected to the intermediate DC circuit. The main circuit breaker is located between the power grid and the rectifier. The traction control unit includes: The power supply switching module is used to control the power battery system to supply power to the intermediate DC circuit in a manner that matches the voltage of the intermediate DC circuit if a phase break warning signal is received before the vehicle reaches the phase break zone, and to control the rectifier to gradually reduce the power drawn from the grid so that the voltage of the intermediate DC circuit remains stable during the power supply switching process. The switching control module is used to obtain the real-time traction power of the vehicle. When the obtained real-time traction power is less than the preset power, the main circuit breaker is controlled to open and block the rectifier. The preset power is set based on the maximum power supply of the power battery system. The power supply module is used to maintain the voltage stability of the intermediate DC circuit by the power battery system after the main circuit breaker is disconnected, so as to drive the traction motor to continue to work and maintain the traction power output until the grid voltage obtained after passing through the phase split zone is greater than or equal to the preset voltage.

9. A vehicle traction control device, characterized in that, Includes a vehicle traction system and a traction control unit as described in claim 8; The vehicle traction system includes a power battery system, a traction converter, a main circuit breaker, and a traction motor. The traction converter includes an intermediate DC circuit and a rectifier. The power battery system is electrically connected to the intermediate DC circuit; The output terminal of the rectifier is electrically connected to the intermediate DC circuit. The main circuit breaker is located between the power grid and the rectifier; The traction control unit is electrically connected to the power battery system, the rectifier, and the main circuit breaker, respectively.

10. A vehicle, characterized in that, Includes the vehicle traction control device as described in claim 9.

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