Parallel power supply current-sharing control method for asymmetric chargers of rail transit vehicle

Abstract

The invention discloses a parallel power supply current-sharing control method and device for asymmetric chargers of a rail transit vehicle, which solve the problem that the output current of the asymmetric parallel chargers is unbalanced, and in the rail transit vehicle, the charger with a storage battery adopts constant-current voltage-limiting control, and the charger without the storage battery adopts constant-voltage control. The two are connected in parallel to a DC bus. The method comprises the steps that a vehicle network control system collects output reference voltage and output current of each charger with a storage battery, selects the maximum value as a voltage reference value and a current reference value, and sends the voltage reference value and the current reference value to a charger without a storage battery; and the current sharing control module is used for setting initial reference voltage and output target current, generating a compensation voltage value through proportional integral (PI) adjustment according to the deviation between the output current and the target current, and dynamically adjusting the output voltage to realize current sharing control. According to the invention, on the premise of not changing the existing vehicle architecture and control mode, efficient and reliable current sharing is realized, and the power supply reliability of the system is improved.

Description

Technical Field

[0001] This invention relates to the technical field of electrical control for rail transit vehicles, and more particularly to a method for current sharing control of parallel power supply of asymmetrical chargers for rail transit vehicles. Background Technology

[0002] In rail transit vehicles, multiple chargers are often connected in parallel to supply power to the DC bus to achieve redundancy and increase power supply capacity. Some chargers simultaneously charge the onboard battery and supply power to the bus (chargers with battery attachments), while others only supply power to the bus (chargers without battery attachments). These two types of chargers often employ different control strategies (such as "constant current limiting voltage" and "constant voltage control") due to their different functions and are asymmetrically arranged in different vehicles. Because of the difference in bus line impedance on the vehicle side, if only the voltage of the chargers without battery attachments is regulated, it can easily lead to a severe imbalance in the output power of the two types of chargers, and may even prevent the chargers without battery attachments from outputting current. This would prevent the multiple chargers from effectively coordinating, and the advantages of redundancy design would be difficult to realize. Traditional current sharing methods (such as voltage droop control) suffer from limited current sharing accuracy and slow dynamic response in this asymmetrical scenario, which may affect system stability and the accuracy or effectiveness of current sharing. Summary of the Invention

[0003] The purpose of this invention is to provide a current sharing control method for parallel power supply of asymmetrical chargers in rail transit vehicles, addressing the deficiencies in existing technologies. This method achieves effective balanced control of the output current of asymmetrically connected chargers in rail transit vehicles. By collecting and determining key state parameters of the battery-equipped chargers through the vehicle network control system as a reference benchmark, the chargers without batteries perform local PI closed-loop regulation based on this benchmark. This overcomes the current imbalance problem caused by differences in control modes and line impedance. Without changing the existing vehicle network architecture and the core control method of the chargers, this method improves the power supply reliability, capacity utilization efficiency, and collaborative working capability of the parallel system, while also extending the working life of the batteries.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: at least one charger with a battery and at least one charger without a battery are connected in parallel on the DC bus of the rail transit vehicle. The method includes: The vehicle network control system collects the output reference voltage and output current of the battery charger. The vehicle network control system determines and sends voltage reference values ​​and current reference values ​​to the battery-free charger based on the collected output reference voltage and output current. The voltage reference value is set as the initial reference voltage of the battery-free charger, and the current reference value is set as the output target current of the battery-free charger. The charger without a battery generates a compensation voltage value through proportional-integral (PI) regulation based on the deviation between its output current and the target output current. The initial reference voltage is then adjusted based on the compensation voltage value to achieve current sharing control between the output current of the charger without a battery and the charger with a battery.

[0005] Furthermore, the step of determining and sending the voltage reference value and the current reference value includes: The maximum value among the collected output reference voltages is selected as the voltage reference value, and the maximum value among the collected output currents is selected as the current reference value.

[0006] Furthermore, the maximum value is selected from the data collected within the current collection period.

[0007] Furthermore, the vehicle network control system communicates with the charger with a battery and the charger without a battery via a multi-function vehicle bus (MVB) to perform the acquisition and transmission steps at a fixed communication cycle.

[0008] Furthermore, when the communication between the vehicle network control system and the charger without a battery is abnormal, the charger without a battery maintains a preset fixed reference value, or maintains the voltage reference value and current reference value received last before the communication abnormality.

[0009] Furthermore, adjusting the initial reference voltage based on the compensation voltage value specifically involves adding the compensation voltage value to the initial reference voltage to generate a final reference command.

[0010] Furthermore, the proportional coefficient and integral coefficient are settable parameters, and their specific values ​​are determined based on system testing.

[0011] Furthermore, the proportional-integral (PI) regulation is continuously executed with a fixed adjustment period, dynamically adjusting the compensation voltage value according to the deviation and limiting its amplitude within a preset range, so that the deviation of the output current is maintained within an acceptable range.

[0012] A current sharing control device for parallel power supply of asymmetrical chargers in rail transit vehicles is disclosed. The rail transit vehicle includes a DC bus, a vehicle network control system, at least one charger with a battery and at least one charger without a battery, wherein the at least one charger with a battery and the at least one charger without a battery are connected in parallel to the DC bus. The function of the device is achieved collaboratively by the vehicle network control system and the charger without a battery, wherein: The vehicle network control system is configured to: acquire the output reference voltage and output current of the battery-equipped charger; determine a voltage reference value and a current reference value based on the acquired output reference voltage and output current; and send the voltage reference value and current reference value to the battery-free charger; wherein the voltage reference value is set as the initial reference voltage of the battery-free charger, and the current reference value is set as its output target current; The charger without a battery is configured to generate a compensation voltage value by proportional-integral (PI) adjustment based on the deviation between its output current and the target output current, and to adjust the initial reference voltage according to the compensation voltage value, so as to perform current sharing control on the output current of the charger without a battery and the charger with a battery.

[0013] At least one battery-equipped charger and at least one batteryless charger are connected in parallel to the DC bus of the rail transit vehicle. The method includes: the vehicle network control system acquiring the output reference voltage and output current of the battery-equipped charger; the vehicle network control system determining and sending voltage reference values ​​and current reference values ​​to the batteryless charger based on the acquired output reference voltage and output current, wherein the voltage reference value is set as the initial reference voltage of the batteryless charger, and the current reference value is set as the output target current of the batteryless charger; and the batteryless charger generating compensation through proportional-integral (PI) regulation based on the deviation between its output current and the output target current. The voltage value is calculated, and the initial reference voltage is adjusted based on the compensation voltage value to achieve current sharing control of the output current of the charger without a battery and the charger with a battery. This achieves effective balanced control of the output current of the chargers connected in asymmetrical parallel in rail transit vehicles. The key state parameters of the charger with a battery are collected and determined by the vehicle network control system as a reference benchmark, and the charger without a battery performs local PI closed-loop regulation based on this benchmark. This overcomes the problem of uneven current caused by differences in control modes and line impedance. Without changing the existing vehicle network architecture and the core control method of the charger, the power supply reliability, capacity utilization efficiency and collaborative working capability of the parallel system are improved, and the battery life is also extended. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a flowchart of the parallel power supply current sharing control method for asymmetric chargers in rail transit vehicles according to the present invention; Figure 2 This is a schematic diagram of a parallel power supply topology for a vehicle charger according to a specific embodiment of the present invention; Figure 3 This is a communication topology diagram between the vehicle network control system and the charger; Figure 4 This is a block diagram of the current sharing control principle inside a charger without a battery. Detailed Implementation

[0016] 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.

[0017] In the description of this invention, it should be noted that the orientations or positional relationships indicated by terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inner", and "outer" are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0018] like Figure 1 , Figure 2 As shown, Figure 1 The control flow of the present invention is shown. Figure 2This is a topology diagram of a specific embodiment of the present invention, showing the parallel connection relationship of two chargers with batteries (labeled 'charger with batteries 1' and 'charger with batteries 2') and two chargers without batteries (labeled 'charger without batteries 1' and 'charger without batteries 2'). It should be understood that the specific types and quantities shown in the figures are merely examples, and the 'at least one charger with batteries' and 'at least one charger without batteries' described in the present invention include, but are not limited to, this configuration. A method for parallel power supply and current sharing control of asymmetrical chargers for rail transit vehicles, wherein at least one charger with batteries and at least one charger without batteries are connected in parallel to the DC bus of the rail transit vehicle; The method includes: The vehicle network control system collects the output reference voltage and output current of the battery charger. The vehicle network control system determines and sends voltage reference values ​​and current reference values ​​to the battery-free charger based on the collected output reference voltage and output current. The voltage reference value is set as the initial reference voltage of the battery-free charger, and the current reference value is set as the output target current of the battery-free charger. The charger without a battery generates a compensation voltage value through proportional-integral (PI) regulation based on the deviation between its output current and the target output current. The initial reference voltage is then adjusted according to the compensation voltage value to achieve current sharing control between the output current of the charger without a battery and the charger with a battery.

[0019] Specifically, in a 6-car metro train, four chargers are connected in parallel to the DC bus and distributed across different cars. The charger in car Tc is a battery-equipped charger, which simultaneously charges the onboard battery and supplies power to the DC bus; the charger in car M1 is a battery-free charger, which only supplies power to the DC bus. The arrangement of these two types of chargers on the train constitutes an asymmetrical parallel structure. The implementation of this method relies on the vehicle's existing network control system and the controllers of each charger. The specific control flow is as follows: S1, Data Acquisition and Transmission The vehicle network control system uses the Multifunction Vehicle Bus (MVB) (such as...) Figure 3 The vehicle-mounted communication network (as shown) collects the output reference voltage (i.e., the voltage setting value after compensation based on the battery temperature) and real-time output current of the battery charger on the Tc vehicle at a fixed communication cycle.

[0020] The network control system selects the maximum values ​​of the output reference voltage and the output current from the collected data. In a preferred embodiment, the maximum values ​​are selected from the data collected within the current acquisition cycle, rather than instantaneous values, effectively avoiding frequent jumps in the reference values ​​caused by instantaneous data fluctuations.

[0021] The network control system selects the maximum output reference voltage and maximum output current as voltage reference values ​​and current reference values, and sends them to the battery-less charger of the M1 vehicle via MVB.

[0022] S2. Target value setting and fault tolerance handling The M1 vehicle's battery-less charger receives voltage and current reference values ​​from the network control system. The charger sets the received voltage reference value as its initial reference voltage and the received current reference value as its target output current. To ensure system reliability during brief communication interruptions, when communication between the network control system and the M1 vehicle's charger is lost, the charger will maintain either a preset fixed reference value or the last correctly received voltage and current reference values ​​before the communication interruption, until communication is restored. Upon restoration, the newly received values ​​are immediately used for updating.

[0023] S3, Closed-loop regulation and flow equalization control The M1's battery-less charger uses its own output current as feedback to calculate the deviation from the target output current. The charger has a built-in proportional-integral (PI) regulator (see...). Figure 4A compensation voltage value is generated based on the current deviation. The proportional and integral coefficients of the PI regulator are parameters that can be preset or tuned online according to system characteristics. The PI regulation is performed with a fixed adjustment period (e.g., 1 second). The amplitude of the compensation voltage value is limited to a preset allowable deviation range (e.g., ±4V) to prevent over-adjustment and ensure system stability. The charger's control logic corrects the initial reference voltage based on the compensation voltage value, generating a reference command that ultimately acts on the charger's voltage loop controller. Through this dynamic correction, the compensation voltage value is used as a feedback adjustment quantity to adjust the initial reference voltage based on the state setting of the battery-connected charger in real time. This closed-loop regulation process continues, driving the actual output current of the M1 vehicle charger to approach the target current, thereby coordinating its output power with the output power of the Tc vehicle's battery-connected charger, ultimately achieving a balanced distribution of the DC bus power supply current from all parallel chargers, i.e., current sharing control. This solution specifically addresses the unique current sharing challenges inherent in asymmetric parallel architectures. For parallel charging scenarios in rail transit vehicles where the control strategies and physical locations of battery-equipped and battery-free chargers are asymmetrical, a dedicated solution is proposed. By enabling the battery-free charger in constant-voltage control mode to dynamically follow the operating state of the battery-equipped charger, which features temperature compensation and constant-current-voltage limiting characteristics, this fundamentally overcomes the technical problems of power imbalance or even no current output caused by inconsistent control objectives and line impedance differences between the two chargers. This allows the redundantly designed chargers to truly cooperate and work effectively. Furthermore, high-performance control is achieved while maintaining the existing system architecture. It is entirely based on the vehicle's existing network control system and the charger's original hardware platform, without requiring changes to the mature vehicle network topology or the charger's internal constant-current-voltage limiting or constant-voltage core control algorithms. This is achieved simply by adding data filtering and forwarding logic to the network control system and enabling or adding a PI regulator function to the battery-free charger's control software. Therefore, it offers advantages such as ease of implementation, low modification costs, and no introduction of additional complexity, while ensuring the reliability of the control logic. Simultaneously, it improves the overall system efficiency and reliability. By achieving precise current sharing, this invention avoids overload or underload operation of individual chargers caused by uneven current distribution, thereby improving the capacity utilization efficiency and long-term operational reliability of the entire power supply system. For chargers with batteries, the output current is more balanced and stable, which is beneficial for extending the charging life and overall service life of the batteries. The data retention mechanism in case of communication anomalies further enhances the robustness of the system under non-ideal operating conditions.

[0024] As a preferred embodiment of the above, such as Figures 1-2 As shown, the steps of determining and sending the voltage reference value and the current reference value include: The maximum value among the collected output reference voltages is selected as the voltage reference value, and the maximum value among the collected output currents is selected as the current reference value.

[0025] Specifically, in step S1, the vehicle network control system collects the output reference voltage and output current of at least one battery-equipped charger. In the subsequent determination and transmission steps, the network control system does not simply randomly select or forward a value, but executes a specific filtering logic: from the collected output reference voltages of one or more battery-equipped chargers, it selects the maximum value as the voltage reference value to be transmitted; simultaneously, from the collected output currents, it selects the maximum value as the current reference value to be transmitted. In a specific example, if there are multiple battery-equipped chargers in the system, the network control system will periodically read the output voltage setpoint (temperature-compensated reference voltage) and real-time output current of each charger and compare these values ​​respectively. Finally, it filters out the highest output voltage setpoint and the highest output current value among all battery-equipped chargers in the current cycle, and sends them as a set of collaborative reference instructions to the chargers without batteries. This establishes a clear and robust collaborative operating benchmark. The maximum value of the output reference voltage is selected as the benchmark, setting a common lower voltage limit for the entire parallel system that covers the needs of all battery-powered chargers. This ensures that the output voltage requirement of any battery-powered charger is supported by the bus voltage, thus creating the prerequisite for its current-sharing output. Furthermore, it enhances the system's stability and anti-interference capabilities, providing a smoothly changing and forward-looking operating command for chargers without batteries. This avoids frequent jumps in their reference command due to instantaneous fluctuations in front-end data, thereby improving the stability and robustness of the entire parallel system control and reducing unnecessary adjustment oscillations.

[0026] As a preferred embodiment of the above, such as Figures 1-2 As shown, the maximum value is selected from the data collected within the current collection period.

[0027] As a preferred embodiment of the above, such as Figures 1-2 As shown, the vehicle network control system communicates with the charger with a battery and the charger without a battery via the Multifunction Vehicle Bus (MVB) to perform the acquisition and transmission steps at a fixed communication cycle.

[0028] Specifically, the vehicle network control system establishes communication connections with both the battery-equipped and battery-free chargers via a multi-functional vehicle bus. This multi-functional vehicle bus is an internationally standardized control and monitoring network widely used in rail transit vehicles, possessing high reliability and strong real-time performance. Under this communication architecture, the vehicle network control system, acting as the communication manager, sequentially performs the following operations according to a pre-set and fixed communication cycle: at specific times within a cycle, it sequentially sends data requests to each battery-equipped charger or directly collects its output reference voltage and output current data from their periodic broadcast messages; subsequently, within the same cycle or the next fixed cycle, it sends the determined voltage and current reference values ​​to the designated battery-free charger via the bus. The entire acquisition, processing, and transmission process is strictly defined and driven by this fixed cycle, repeating continuously. This fully utilizes the vehicle's existing high-reliability network, achieving seamless integration and high determinism. Furthermore, the fixed-cycle communication establishes a deterministic control rhythm, ensuring system stability and achieving standardization and manageability of the control timing.

[0029] As a preferred embodiment of the above, such as Figures 1-2 As shown, when the communication between the vehicle network control system and the charger without a battery is abnormal, the charger without a battery maintains a preset fixed reference value, or maintains the voltage reference value and current reference value received last before the communication abnormality.

[0030] Specifically, during the periodic communication between the vehicle network control system and the batteryless charger via the MVB bus, the batteryless charger continuously monitors the communication status. Once a communication anomaly is detected with the vehicle network control system (e.g., failure to receive valid data frames within a preset number of communication cycles, or incorrect verification of received data frames), fault-tolerant logic is immediately triggered. Under this logic, the batteryless charger stops updating its internal voltage and current reference values. Instead, it automatically switches to hold mode, continuously using and maintaining the last successfully received and verified valid voltage and current reference values ​​before the communication anomaly occurred as the benchmark for its local PI regulation. When the communication link is restored and the vehicle network control system resumes sending valid reference data, the batteryless charger immediately exits hold mode, overwrites the original hold value with the newly received value, and resumes normal follow-up regulation. This achieves seamless degradation and maintenance of control functions, ensures uninterrupted system operation, prevents control command jumps and system oscillations caused by data loss, and provides simple, reliable, and fault-tolerant logic that does not require complex state negotiation.

[0031] As a preferred embodiment of the above, such as Figures 1-2As shown, adjusting the initial reference voltage based on the compensation voltage value specifically involves adding the compensation voltage value to the initial reference voltage to generate a final reference command.

[0032] Specifically, in the control unit without a battery charger, the adjustment of the initial reference voltage based on the compensation voltage value is implemented as follows: The compensation voltage value (ΔV) calculated by the PI regulator is used as an independent correction quantity. In a designated stage of the control algorithm, it is algebraically added to the initial reference voltage (Vref_init) received and set via the network. The output of this addition operation is the final reference instruction (Vref_final) generated and ultimately sent to the voltage loop controller inside the charger. This process is executed cyclically in each control cycle, achieving dynamic adjustment. This establishes a clear and efficient composite control structure combining feedforward reference and feedback fine-tuning, achieving a balance between fast response and precise steady-state control, maximizing the maintenance and utilization of the existing control architecture, and achieving smooth integration.

[0033] As a preferred embodiment of the above, such as Figures 1-2 As shown, the proportional coefficient and integral coefficient are settable parameters, and their specific values ​​are determined based on system testing.

[0034] Specifically, in chargers without batteries, the core control parameters of the proportional-integral (PI) regulator used to generate compensation voltage values ​​based on current deviations—namely, the proportional coefficient (Kp) and integral coefficient (Ki)—are designed to be settable and configurable. These parameters are stored numerically in the charger controller's non-volatile memory or configuration file, and can be accessed and modified through specialized debugging tools, vehicle maintenance interfaces, or authorized network commands without altering the controller's main program code. This endows the control algorithm with the core capability to handle system variability and uncertainty, achieves optimized control performance and lifecycle maintainability, and provides a convenient bridge connecting advanced control theory and engineering practice.

[0035] As a preferred embodiment of the above, such as Figures 1-2 As shown, the proportional-integral (PI) regulation is continuously executed with a fixed adjustment period, dynamically adjusting the compensation voltage value according to the deviation and limiting its amplitude within a preset range so that the deviation of the output current is maintained within an acceptable range.

[0036] Specifically, in a charger without a battery, the proportional-integral (PI) regulation function is triggered periodically with a pre-set and fixed regulation cycle. This cycle is independent of the network communication cycle and can be set to, for example, 1 second. At the arrival of each regulation cycle, the controller reads the current current deviation, performs a complete PI calculation, and outputs a new compensation voltage value. Simultaneously, to ensure smooth and controlled regulation, an amplitude limit is applied to the compensation voltage value output by the PI regulator. A preset deviation range (e.g., ±4V) is set in the control software. Regardless of the original result obtained from the PI calculation, its output value undergoes a limiting process before being used for regulation: if the calculated result exceeds the upper limit of the range, the output value is clamped at the upper limit; if it is below the lower limit, it is clamped at the lower limit; if it is within the range, it passes directly. This value after limiting is the final compensation voltage value used for regulation. Thus, a deterministic local control rhythm is established through a fixed regulation cycle, eliminating the potential for timing randomness, and a safety boundary is constructed through the compensation voltage amplitude limit, fundamentally preventing overshoot and instability.

[0037] A current sharing control device for parallel power supply of asymmetrical chargers in rail transit vehicles is disclosed. The rail transit vehicle includes a DC bus, a vehicle network control system, at least one charger with a battery and at least one charger without a battery, wherein the at least one charger with a battery and the at least one charger without a battery are connected in parallel to the DC bus. The function of the device is achieved collaboratively by the vehicle network control system and the charger without a battery, wherein: The vehicle network control system is configured to: acquire the output reference voltage and output current of the battery-equipped charger; determine a voltage reference value and a current reference value based on the acquired output reference voltage and output current; and send the voltage reference value and current reference value to the battery-free charger; wherein the voltage reference value is set as the initial reference voltage of the battery-free charger, and the current reference value is set as its output target current; The charger without a battery is configured to: generate a compensation voltage value by proportional-integral (PI) regulation based on the deviation between its output current and the target output current, and adjust the initial reference voltage according to the compensation voltage value, so as to perform current sharing control on the output current of the charger without a battery and the charger with a battery.

[0038] Specifically, the vehicle network control system is configured to perform the following functions: acquiring the output reference voltage and output current of at least one battery-equipped charger connected in parallel to the DC bus via a vehicle communication network (such as a Multifunction Vehicle Bus, MVB) at fixed communication cycles; executing specific determination logic based on the acquired data to generate voltage and current reference values; and subsequently sending the determined voltage and current reference values ​​to the battery-free charger. The voltage reference value is set as the initial reference voltage of the battery-free charger, and the current reference value is set as its target output current. The battery-less charger is configured to perform the following functions: monitor its own output current in real time and compare it with the received target output current to obtain the current deviation; calculate a compensation voltage value based on the current deviation using the proportional-integral (PI) regulation function enabled in its control unit (the proportional and integral coefficients of the PI regulation are settable parameters, the regulation is performed at a fixed period, and the amplitude of the calculated compensation voltage value is limited to a preset deviation range); and adjust the initial reference voltage based on the compensation voltage value (specifically, by adding the compensation voltage value to the initial reference voltage to generate a final reference command), thereby dynamically adjusting its output voltage to make its output current approach the target current, ultimately achieving current sharing control between the charger and the battery-equipped charger. Through the above-mentioned coordinated configuration, the battery-less charger can adaptively follow the working state of the battery-equipped charger, overcoming the parallel current imbalance problem caused by different control modes and line impedance differences. This device innovatively utilizes the existing hardware resources of the vehicle's network control system and charger. Through software configuration and functional upgrades, it achieves complex current sharing control without altering the original vehicle network topology, communication architecture, or charger core control hardware. This results in high-performance control with minimal cost and modification, demonstrating high engineering feasibility and economy. Secondly, the device organically integrates networked collaborative decision-making with localized closed-loop regulation. The vehicle network control system provides a stable reference benchmark for global optimization (such as feedforward), while the battery-free charger performs precise fine-tuning based on local feedback. This distributed functional division enables the system to possess both rapid response capability and high steady-state accuracy. Furthermore, the structure of each component performing its specific function reduces system complexity and overall failure risk. Finally, the fault-tolerant mechanisms (such as maintaining the last valid value in case of communication failure) and stability assurance measures (such as fixed adjustment cycles and compensation voltage limiting) included in the device design ensure that the control function can still be executed reliably and stably in the harsh and dynamic operating environment of rail transit. This enhances the robustness and availability of the entire parallel power supply system, allowing the redundantly designed charger to truly leverage the advantages of collaborative power supply.

[0039] Experimental verification: To verify the control effect of this invention, a real-vehicle test was conducted on a 6-car metro train. The test system configuration and... Figure 2 Consistent with the aforementioned embodiments, after configuring the vehicle network control system and chargers to execute the method described in this invention, the operating data of four chargers (two with batteries and two without batteries) under typical loads were recorded.

[0040] The experimental results clearly show that after applying the control method of this invention, the output current values ​​of the four chargers quickly approached and remained highly consistent. During the load stabilization phase, the maximum relative deviation between the output currents of each charger was stably controlled within ±5% (based on the recorded detailed experimental data), achieving excellent current sharing performance. These experimental results directly prove that the method of this invention can effectively overcome the problem of uneven current caused by differences in control mode and line impedance, verifying its engineering practicality and significant progress.

[0041] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for current sharing control of parallel power supply of asymmetrical chargers for rail transit vehicles, characterized in that, The rail transit vehicle has at least one charger with a battery and at least one charger without a battery connected in parallel on its DC bus. The method includes: The vehicle network control system collects the output reference voltage and output current of the battery charger. The vehicle network control system determines and sends voltage reference values ​​and current reference values ​​to the battery-free charger based on the collected output reference voltage and output current. The voltage reference value is set as the initial reference voltage of the battery-free charger, and the current reference value is set as the output target current of the battery-free charger. The charger without a battery generates a compensation voltage value through proportional-integral (PI) regulation based on the deviation between its output current and the target output current. The initial reference voltage is then adjusted based on the compensation voltage value to achieve current sharing control between the output current of the charger without a battery and the charger with a battery.

2. The method for parallel power supply current sharing control of asymmetrical chargers for rail transit vehicles according to claim 1, characterized in that, The steps of determining and sending voltage reference values ​​and current reference values ​​include: The maximum value among the collected output reference voltages is selected as the voltage reference value, and the maximum value among the collected output currents is selected as the current reference value.

3. The method for parallel power supply current sharing control of asymmetrical chargers for rail transit vehicles according to claim 2, characterized in that, The maximum value is selected from the data collected within the current collection period.

4. The parallel power supply current sharing control method for asymmetrical chargers in rail transit vehicles according to claim 3, characterized in that, The vehicle network control system communicates with the charger with a battery and the charger without a battery via a multi-function vehicle bus (MVB) to perform the acquisition and transmission steps at a fixed communication cycle.

5. The method for parallel power supply current sharing control of asymmetrical chargers for rail transit vehicles according to claim 1, characterized in that, When the communication between the vehicle network control system and the charger without a battery is abnormal, the charger without a battery maintains a preset fixed reference value, or maintains the voltage reference value and current reference value last received before the communication abnormality.

6. The method for parallel power supply current sharing control of asymmetrical chargers for rail transit vehicles according to any one of claims 1 to 3, characterized in that, The adjustment of the initial reference voltage based on the compensation voltage value specifically involves adding the compensation voltage value to the initial reference voltage to generate a final reference command.

7. The method for parallel power supply current sharing control of asymmetrical chargers for rail transit vehicles according to any one of claims 1 to 3, characterized in that, The proportional coefficient and integral coefficient are settable parameters, and their specific values ​​are determined based on system testing.

8. The method for parallel power supply current sharing control of asymmetrical chargers for rail transit vehicles according to any one of claims 1 to 3, characterized in that, The proportional-integral (PI) regulation is continuously executed with a fixed adjustment period, dynamically adjusting the compensation voltage value according to the deviation and limiting its amplitude within a preset range so that the deviation of the output current is maintained within an acceptable range.

9. A current sharing control device for parallel power supply of asymmetrical chargers for rail transit vehicles, characterized in that, The rail transit vehicle includes a DC bus, a vehicle network control system, at least one charger with a battery and at least one charger without a battery, wherein the at least one charger with a battery and the at least one charger without a battery are connected in parallel to the DC bus; the function of the device is achieved collaboratively by the vehicle network control system and the charger without a battery, wherein: The vehicle network control system is configured to: acquire the output reference voltage and output current of the battery-equipped charger; determine a voltage reference value and a current reference value based on the acquired output reference voltage and output current; and send the voltage reference value and current reference value to the battery-free charger; wherein the voltage reference value is set as the initial reference voltage of the battery-free charger, and the current reference value is set as its output target current; The charger without a battery is configured to generate a compensation voltage value by proportional-integral (PI) adjustment based on the deviation between its output current and the target output current, and to adjust the initial reference voltage according to the compensation voltage value, so as to perform current sharing control on the output current of the charger without a battery and the charger with a battery.

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