A new energy locomotive self-load test system and method

Abstract

The application discloses a new energy locomotive self-load test system and method. The new energy locomotive self-load test method is applied to the new energy locomotive self-load test system. When the new energy locomotive is a hybrid locomotive, a locomotive control system controls a diesel generator set to charge a first power battery pack or a second power battery pack, and the performance of the diesel generator set is examined by adjusting the charging power. When the new energy locomotive is a pure electric locomotive, the locomotive control system controls one power battery pack and a bidirectional DC / DC converter to perform energy transfer on the other power battery pack and the bidirectional DC / DC converter, and the high-power charging and discharging characteristics of the power battery pack are examined by adjusting the energy transfer power. The application can effectively examine the high-power performance of the diesel generator set, the power battery pack and related conversion equipment of the new energy locomotive, and has the advantages of low cost, convenient operation and flexible test.

Description

Technical Field

[0001] This invention relates to the field of rail transit technology, and in particular to a self-load test system and method for new energy locomotives. Background Technology

[0002] Traditional diesel locomotives are typically equipped with braking resistors. During factory testing, periodic maintenance, or troubleshooting, the diesel engine drives the main generator to generate electricity, which is then consumed by the braking resistors. This allows for the evaluation of the diesel engine-generator set's performance under different operating conditions; this is known as a self-load test. This test is crucial for assessing key indicators such as diesel engine power, fuel consumption rate, generator performance, and cooling system capacity.

[0003] However, with increasing environmental protection requirements and the development of energy technologies, new energy locomotives such as hybrid electric locomotives and pure battery-powered locomotives have been widely used. These new energy locomotives, especially pure battery locomotives, are typically not equipped with high-power braking resistors, or their energy regeneration systems are primarily designed to recover the train's braking energy rather than the high-power consumption of static braking resistors over extended periods. Therefore, effectively evaluating the high-power performance of the diesel generator set (for hybrid locomotives), the power battery pack (for both hybrid and pure battery locomotives), and related converter systems under static conditions has become a pressing technical challenge.

[0004] Currently, testing of new energy locomotives often relies on laboratory bench tests or actual line operation tests. The former cannot fully simulate the vehicle environment, while the latter is costly, time-consuming, and difficult to precisely control test conditions. Therefore, developing a self-load test or equivalent assessment method suitable for static conditions of new energy locomotives is of great significance. Summary of the Invention

[0005] This invention provides a self-load test system and method for new energy locomotives, which can effectively evaluate the high-power performance of diesel generator sets, power battery packs and related converter equipment of new energy locomotives under static conditions, and has the advantages of low cost, convenient operation and flexible testing.

[0006] According to one aspect of the present invention, a self-load test method for a new energy locomotive is provided, which is applied to a self-load test system for a new energy locomotive. The self-load test system for a new energy locomotive includes: a new energy locomotive; the new energy locomotive includes: a locomotive control system, at least one traction inverter, and a traction motor.

[0007] When the new energy locomotive is a hybrid electric locomotive, it also includes: a diesel generator set, a three-phase uncontrolled rectifier, and at least one power battery pack.

[0008] When the new energy locomotive is a pure electric locomotive, it also includes: at least two power battery packs and at least two bidirectional DC-DC devices;

[0009] The self-load test method for the new energy locomotive includes:

[0010] When the new energy locomotive is a hybrid electric locomotive, the locomotive control system controls the diesel generator set to charge the first or second power battery pack, and evaluates the performance of the diesel generator set by adjusting the charging power.

[0011] When the new energy locomotive is a pure electric locomotive, the locomotive control system controls one power battery pack and a bidirectional DC / DC converter to transfer energy to another power battery pack and a bidirectional DC / DC converter, and evaluates the high-power charging and discharging characteristics of the power battery pack by adjusting the energy transfer power.

[0012] Optionally, the performance evaluation of the diesel generator set by adjusting the charging power includes:

[0013] The output power of the diesel generator set is adjusted according to the preset test power curve or constant power command, and the operating parameters of the diesel generator set, the first power battery pack and the second power battery pack are monitored in real time.

[0014] Optionally, the assessment of the high-power charge and discharge characteristics of the power battery pack by adjusting the energy transfer power includes:

[0015] The first bidirectional DC / DC converter and the second bidirectional DC / DC converter control the energy transfer between the first power battery pack and the second power battery pack, and monitor the operating parameters of each relevant power battery pack in real time.

[0016] According to another aspect of the present invention, a static load test method for a new energy locomotive is also provided, which is applied to a self-load test system for a new energy locomotive. The self-load test system for a new energy locomotive includes: interconnected new energy locomotives and an external resistive load cabinet; the new energy locomotive includes: a locomotive control system, at least one traction inverter, and a traction motor.

[0017] When the new energy locomotive is a hybrid electric locomotive, it also includes: a diesel generator set, a three-phase uncontrolled rectifier, and at least one power battery pack.

[0018] When the new energy locomotive is a pure electric locomotive, it also includes: at least two power battery packs and at least two bidirectional DC-DC devices;

[0019] The static load test method for the new energy locomotive includes:

[0020] Disconnect the electrical connection between the traction motor and the at least one traction inverter;

[0021] The external resistor load cabinet is connected between at least two AC output phase terminals of the at least one traction inverter, or between at least one AC output phase terminal and the DC bus neutral point;

[0022] The at least one traction inverter is configured to chopper mode, and the DC power from the power source of the new energy locomotive is chopped by the switching devices of at least one or two bridge arms inside the inverter, and the chopped electrical energy is applied to the external resistor load cabinet.

[0023] By adjusting the chopper control parameters of the traction inverter, the power applied to the external resistor load cabinet is controlled, thereby evaluating the performance of the power source and traction inverter of the new energy locomotive.

[0024] Optionally, the chopping of the DC power from the power source of the new energy locomotive using the switching devices of at least one or two of its internal bridge arms includes:

[0025] At least two arms of the traction inverter form an equivalent DC / DC chopper circuit through a specific pulse width modulation control strategy.

[0026] Optionally, at least two arms of the traction inverter form an equivalent DC / DC chopper circuit through a specific pulse width modulation control strategy, including:

[0027] The external resistive load cabinet is connected between the U-phase and V-phase output terminals of the traction inverter, and the external resistive load cabinet is chopped and powered by a specific combination of U-phase and V-phase associated switching devices through synchronous control.

[0028] Optionally, the static load test method for new energy locomotives further includes: when the test power requirement is large, using multiple traction inverters with the same configuration and their corresponding external resistor load cabinets in parallel to evaluate the performance of the power source and traction inverters of the new energy locomotives.

[0029] According to another aspect of the present invention, a self-load test system for new energy locomotives is also provided. The self-load test system for new energy locomotives includes: interconnected new energy locomotives and an external resistive load cabinet.

[0030] The new energy locomotive includes: a locomotive control system, at least one traction inverter, and a traction motor;

[0031] When the new energy locomotive is a hybrid electric locomotive, it also includes: a diesel generator set, a phase uncontrolled rectifier, and at least one power battery pack.

[0032] When the new energy locomotive is a pure electric locomotive, it also includes: at least two power battery packs and at least two bidirectional DC-DC devices;

[0033] The locomotive control system is connected to the traction inverter, and the traction inverter is connected to the traction motor;

[0034] The diesel generator set is connected to the three-phase uncontrolled rectifier and then connected to the traction inverter via a DC bus. The diesel generator set is used to supply power to the traction inverter. The power battery pack is connected to the bidirectional DC / DC converter and then connected to the traction inverter via a DC bus. The power battery pack is used to supply power to the traction inverter.

[0035] The first end of the external resistor load cabinet is connected to the U-phase output terminal of the traction inverter, and the second end of the external resistor load cabinet is connected to the V-phase output terminal of the traction inverter. The external resistor load cabinet is used for the external load test of the full power verification of the new energy locomotive.

[0036] The locomotive control system includes a plurality of locomotive control units, which are used to perform the method described in any one of the above aspects; or, the locomotive control units are used to perform the method described in any one of the above aspects.

[0037] Optionally, the traction inverter includes: at least one U-phase bridge arm and a V-phase bridge arm, wherein the U-phase bridge arm is composed of U-phase upper bridge arm switching devices and U-phase lower bridge arm switching devices connected in series, and the V-phase bridge arm is composed of V-phase upper bridge arm switching devices and V-phase lower bridge arm switching devices connected in series.

[0038] The U-phase bridge arm and the V-phase bridge arm are connected in parallel between the positive and negative terminals of the DC bus; the connection point of the upper U-phase bridge arm switch and the lower U-phase bridge arm switch forms the U-phase output terminal of the traction inverter, and the connection point of the upper V-phase bridge arm switch and the lower V-phase bridge arm switch forms the V-phase output terminal of the traction inverter; the switching devices of the U-phase bridge arm and the V-phase bridge arm, under the control of the locomotive control system, are used to realize the chopping power supply function of the external resistor load cabinet connected between the U-phase output terminal and the V-phase output terminal.

[0039] Optionally, the new energy locomotive self-load test system further includes: a connection interface;

[0040] The connection interface is connected between the external resistor load cabinet and the traction inverter, and the connection interface is used to safely connect the external resistor load cabinet to the traction inverter.

[0041] Optionally, the locomotive control unit includes: a test mode selection module, a parameter monitoring and recording module, and a safety protection module connected in sequence;

[0042] The test mode selection module is used to select and switch the test mode of the new energy locomotive, the parameter monitoring and recording module is used to monitor and record the parameters during the test of the new energy locomotive, and the safety protection module is used to provide safety protection during the test of the new energy locomotive.

[0043] The technical solution of this invention, for hybrid electric locomotives, controls the diesel generator set to charge the power battery pack to evaluate the diesel generator set. By using the locomotive's power battery pack as the charging load for the diesel generator set, the load test of the diesel generator set is achieved by controlling the charging power. For locomotives with multiple power battery unit groups, some power battery groups are controlled to charge and discharge other power battery groups to evaluate the high-power characteristics of the batteries. By controlling the energy transfer from the first power battery group to the second power battery group in the locomotive, the high-current charging and discharging performance of the battery group is evaluated. Through the energy transfer test inside the battery group under the static environment of the whole vehicle, it is closer to the actual operating conditions and avoids the limitations of bench testing. It solves the problem of the lack of effective static high-power evaluation methods for new energy locomotives. It can effectively evaluate the high-power performance of the diesel generator set, power battery pack and related converter equipment of new energy locomotives under static conditions, and has the advantages of low cost, convenient operation and flexible testing.

[0044] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a flowchart of a self-load test method for a new energy locomotive provided according to an embodiment of the present invention;

[0047] Figure 2This is a schematic diagram of a static test system connection for an external load and a traction inverter as a chopper, according to an embodiment of the present invention.

[0048] Figure 3 This is a schematic diagram of a static testing method for a diesel generator set according to an embodiment of the present invention;

[0049] Figure 4 This is a schematic diagram of the high-power characteristic assessment and inter-pack energy transfer of a power battery pack according to an embodiment of the present invention. Detailed Implementation

[0050] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0051] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0052] Figure 1 This is a flowchart of a self-load test method for a new energy locomotive according to an embodiment of the present invention, with reference to... Figure 1 The present invention provides a self-load test method for new energy locomotives, which is applied to a self-load test system for new energy locomotives. Figure 2 This is a schematic diagram of a static test system connection for an external load and a traction inverter as a chopper according to an embodiment of the present invention. (Refer to...) Figure 2 The new energy locomotive self-load test system includes: a new energy locomotive 1; the new energy locomotive 1 includes: a locomotive control system, at least one traction inverter 3, and a traction motor;

[0053] When the new energy locomotive is a hybrid electric locomotive, it also includes: a diesel generator set, a three-phase uncontrolled rectifier, and at least one power battery pack.

[0054] When the new energy locomotive is a pure electric locomotive, it also includes: at least two power units and at least two bidirectional DC-DC devices;

[0055] The self-load test methods for new energy locomotives include:

[0056] S110. When the new energy locomotive is a hybrid electric locomotive, the locomotive control system controls the diesel generator set to charge the first or second power battery pack, and evaluates the performance of the diesel generator set by adjusting the charging power.

[0057] Specifically, the static high-power test method for diesel generator sets in hybrid electric locomotives is as follows:

[0058] a. Place the new energy locomotive in a static safety state and ensure that the relevant safety interlocks are effective;

[0059] b. Start the locomotive control system and enter the static test mode of the diesel generator set;

[0060] c. Control the diesel generator set to start and generate electricity, and charge the power battery pack with the electrical energy generated by the diesel generator set through the locomotive on-board energy management system (diesel generator set, three-phase uncontrolled rectifier, at least two power battery packs, at least two bidirectional DC / DC converters) and the converter system (traction inverter).

[0061] d. Adjust the output power of the diesel generator set according to the preset test power curve or constant power command, and monitor the diesel generator set speed, output voltage, output current, fuel consumption rate, cooling system temperature, and power battery pack charging voltage, charging current, temperature, SOC (State of Charge) and other parameters in real time.

[0062] e. During the assessment process, the power battery pack serves as the load of the diesel generator set. By adjusting the charging power of the power battery pack, the performance of the diesel generator set at different power points can be assessed.

[0063] Furthermore, different charging strategies (such as constant current charging, constant voltage charging, and constant power charging) can be set through the locomotive control system to simulate different load characteristics, thereby more comprehensively evaluating the dynamic response and stable operation capability of the diesel generator set.

[0064] Figure 3 This is a schematic flowchart of a static testing method for a diesel generator set according to an embodiment of the present invention, combined with... Figure 3 The following is a further detailed explanation of the static testing method for diesel generator sets in hybrid electric locomotives:

[0065] (a) Preparation of new energy locomotives: Park the hybrid electric locomotive in the designated test area, apply the parking brake, and confirm that the wheel chocks are engaged.

[0066] (b) System Settings: Enter the "Stabilized Performance Mode of Diesel Generator Set" through the human-machine interface. The operator can preset the target power for the performance test (e.g., 50%, 75%, 100%, 110% of the rated power, etc.) and the duration of each power point. It is recommended that the initial SOC of the power battery pack be at a low level (e.g., 20%-50%) to ensure sufficient charging space.

[0067] (c) Test execution:

[0068] The locomotive control system starts the diesel generator set.

[0069] The electrical energy output from the diesel generator set is rectified by a three-phase uncontrolled rectifier and then charged to the power battery pack via a bidirectional DC / DC converter.

[0070] The locomotive control system adjusts the output power of the diesel generator set according to the preset power command, and at the same time controls the charging current of the power battery so that the actual output power of the diesel generator set reaches the target value.

[0071] During this process, the diesel engine's speed, fuel consumption, coolant temperature, oil pressure and temperature, generator output voltage, current, and power are recorded in real time; at the same time, the power battery's charging voltage, current, maximum / minimum temperature of individual cells, and SOC are also recorded.

[0072] (d) Data analysis: After the test, the performance indicators of the diesel generator set at each power point are evaluated based on the recorded data to determine whether they meet the design requirements.

[0073] In summary, the core of the static testing method for diesel generator sets in hybrid electric locomotives lies in using the locomotive's power battery pack as the charging load for the diesel generator set, and controlling the charging power to achieve load testing of the diesel generator set.

[0074] S120. When the new energy locomotive is a pure electric locomotive, the locomotive control system controls one power battery pack and a bidirectional DC / DC converter to transfer energy to another power battery pack and a bidirectional DC / DC converter. The high-power charging and discharging characteristics of the power battery pack are tested by adjusting the energy transfer power.

[0075] Specifically, the evaluation method for the high-power characteristics of the power battery packs in pure battery-powered locomotives or hybrid locomotives is as follows:

[0076] a. Place the new energy locomotive in a static safety state and ensure that the relevant safety interlocks are effective;

[0077] b. Start the locomotive control system and enter the static test mode of the power battery pack;

[0078] c. Divide the power battery pack into at least one discharge unit and one charging unit;

[0079] d. Control the energy transfer from the discharge unit to the charging unit through an energy management system and a bidirectional DC / DC converter or a back-to-back converter;

[0080] e. Adjust the power of energy transfer according to the preset discharge / charge power curve or constant power command, and monitor the discharge voltage, discharge current, temperature, and SOC changes of the discharge unit, as well as the charging voltage, charging current, temperature, and SOC changes of the charging unit in real time.

[0081] f. Through this internal energy circulation process, the performance of the power battery pack under high-current discharge and charging conditions can be evaluated.

[0082] Furthermore, by preset different depths of discharge and charge / discharge rates, the performance and degradation characteristics of the power battery pack under different operating conditions can be evaluated.

[0083] Figure 4 This is a schematic diagram illustrating the high-power characteristic assessment and inter-pack energy transfer of a power battery pack according to an embodiment of the present invention. (Refer to...) Figure 4 The following section provides a more detailed explanation of the static high-power characteristic testing method for power battery packs in new energy locomotives:

[0084] (a) Preparation of pure battery-powered locomotive: Same as the above embodiment. Assume that the locomotive is equipped with two independent power battery packs, A and B.

[0085] (b) System Settings: Enter the "Power Battery Pack Static Assessment Mode". Set battery pack A as the discharge unit and battery pack B as the charging unit. Preset the discharge rate (e.g., 1C, 2C) or constant discharge power, and the discharge cutoff conditions (e.g., lower SOC limit or lower voltage limit).

[0086] (c) Test execution:

[0087] The locomotive control system initiates the energy transfer process. Battery pack A is connected to a bidirectional DC / DC converter (boost or buck, depending on the charging voltage requirements of battery pack B) at its output. If the locomotive itself has a bidirectional DC / DC converter for battery balancing or auxiliary system power supply, this device can be used. Alternatively, a central DC bus can be used, with battery pack A discharging to the bus via a DC / DC converter, and battery pack B drawing power from the bus via the DC / DC converter for charging.

[0088] The preferred embodiment is as follows: Battery pack A outputs energy to the intermediate DC bus via its associated bidirectional DC / DC converter, and battery pack B absorbs energy from the intermediate DC bus via its associated bidirectional DC / DC converter.

[0089] The locomotive control system adjusts the power of energy transfer so that battery pack A discharges according to preset conditions.

[0090] Real-time recording of the discharge voltage, current, power, SOC change, and temperature of battery pack A; and the charging voltage, current, power, SOC change, and temperature of battery pack B.

[0091] (d) Data Analysis: Analyze the battery's voltage drop / recovery characteristics, temperature rise, and charge / discharge efficiency during high-rate discharge / charge processes. Reverse testing can be performed by switching roles A and B.

[0092] In summary, the core of the static high-power characteristic assessment method for power battery packs in new energy locomotives lies in controlling the energy transfer from the first power battery pack to the second power battery pack within the locomotive, thereby achieving the assessment of the high-current charging and discharging performance of the power battery pack.

[0093] The technical solution of this invention, for hybrid electric locomotives, controls the diesel generator set to charge the power battery pack to evaluate the diesel generator set. By using the locomotive's power battery pack as the charging load for the diesel generator set, the load test of the diesel generator set is achieved by controlling the charging power. For locomotives with multiple power battery unit groups, some power battery groups are controlled to charge and discharge other power battery groups to evaluate the high-power characteristics of the batteries. By controlling the energy transfer from the first power battery group to the second power battery group in the locomotive, the high-current charging and discharging performance of the battery group is evaluated. Through the energy transfer test inside the battery group under the static environment of the whole vehicle, it is closer to the actual operating conditions and avoids the limitations of bench testing. It solves the problem of the lack of effective static high-power evaluation methods for new energy locomotives. It can effectively evaluate the high-power performance of the diesel generator set, power battery pack and related converter equipment of new energy locomotives under static conditions, and has the advantages of low cost, convenient operation and flexible testing.

[0094] Optionally, evaluating the performance of the diesel generator set by adjusting the charging power includes:

[0095] The output power of the diesel generator set is adjusted according to the preset test power curve or constant power command, and the operating parameters of the diesel generator set, the first power battery pack and the second power battery pack are monitored in real time.

[0096] Specifically, the output power of the diesel generator set is adjusted according to the preset test power curve or constant power command, and the speed, output voltage, output current, fuel consumption rate, cooling system temperature, and power battery pack charging voltage, charging current, temperature, and SOC (State of Charge) parameters of the diesel generator set are monitored in real time.

[0097] Optionally, the high-power charge and discharge characteristics of the power battery pack can be evaluated by adjusting the energy transfer power, including:

[0098] The first bidirectional DC / DC converter and the second bidirectional DC / DC converter control the energy transfer between the first power battery pack and the second power battery pack, and monitor the operating parameters of each relevant power battery pack in real time.

[0099] Specifically, the power of energy transfer is adjusted according to the preset discharge / charge power curve or constant power command, and the discharge voltage, discharge current, temperature, and SOC changes of the discharge unit, as well as the charging voltage, charging current, temperature, and SOC changes of the charging unit, are monitored in real time.

[0100] Embodiments of the present invention also provide a static load test method for a new energy locomotive, applied to a self-load test system for a new energy locomotive. The self-load test system for a new energy locomotive includes: interconnected new energy locomotives and an external resistive load cabinet; the new energy locomotive includes: a locomotive control system, at least one traction inverter, and a traction motor.

[0101] When the new energy locomotive is a hybrid electric locomotive, it also includes: a diesel generator set, a three-phase uncontrolled rectifier, and at least one power battery pack.

[0102] When the new energy locomotive is a pure electric locomotive, it also includes: at least two power battery packs and at least two bidirectional DC-DC devices;

[0103] Static load test methods for new energy locomotives include:

[0104] Disconnect the electrical connection between the traction motor and at least one traction inverter;

[0105] Connect the external resistive load cabinet between at least two AC output phase terminals of at least one traction inverter, or between at least one AC output phase terminal and the DC bus neutral point;

[0106] At least one traction inverter is configured to chopper mode, using the switching devices of at least one or two bridge arms inside it to chop the DC power from the power source of the new energy locomotive, and apply the chopped electrical energy to the external resistive load cabinet.

[0107] By adjusting the chopper control parameters of the traction inverter, the power applied to the external resistive load cabinet is controlled, thereby evaluating the performance of the power source and traction inverter of the new energy locomotive.

[0108] Specifically, in combination Figure 2 The specific external load test method for static full-power verification of new energy locomotives (or their main power sources) is as follows:

[0109] a. Place the new energy locomotive 1 in a static safety state and ensure that the parking brake is effective;

[0110] b. Disconnect the electrical connection between the traction motor and the traction inverter 3;

[0111] c. Connect the external resistor load cabinet 2 to the output terminal of the traction inverter 3. For example, connect the external resistor load cabinet 2 between the U-phase output terminal and the V-phase output terminal of the traction inverter 3, or between the U-phase output terminal and the DC bus neutral point N output terminal (if available).

[0112] d. Start the locomotive control system and enter the external load test mode;

[0113] e. Reconfigure the operating mode of the traction inverter 3 so that at least two bridge arms (e.g., the U-phase bridge arm composed of the U-phase upper bridge arm switch device 31 and the U-phase lower bridge arm switch device 32 and the V-phase bridge arm composed of the V-phase upper bridge arm switch device 41 and the V-phase lower bridge arm switch device 42) work together to achieve the chopping function of the DC bus voltage and apply the chopped energy to the external resistive load cabinet 2.

[0114] f. The locomotive's power source, for example, DC power converted from diesel generator set 21 by three-phase uncontrolled rectifier 22, or first power battery pack 11 via first bidirectional DC / DC converter 12, or second power battery pack 13 via second bidirectional DC / DC converter 14, or a combination thereof, supplies power to traction inverter 3 via DC link.

[0115] g. Based on the preset test power, the locomotive control system adjusts the modulation strategy (such as PWM duty cycle) of the traction inverter 3 (as a chopper) to control the power applied to the external resistive load cabinet 2.

[0116] h. Real-time monitoring of key parameters such as DC link voltage and current, voltage and current on external resistor load cabinet 2, as well as the traction inverter 3, locomotive power source, and temperature of external resistor load cabinet 2;

[0117] i. As needed, multiple traction inverters with similar configurations and their corresponding external resistive load cabinets can be used in parallel to meet higher test power requirements.

[0118] Furthermore, the U-phase bridge arm and V-phase bridge arm of the traction inverter 3 can form an equivalent DC / DC chopper circuit through a specific PWM (Pulse Width Modulation) control strategy. For example, by synchronously controlling the on and off of the U-phase upper bridge arm switch 31 and the V-phase lower bridge arm switch 42 (or the U-phase lower bridge arm switch 32 and the V-phase upper bridge arm switch 41), chopper loading of the external resistive load cabinet 2 connected between the U-phase and V-phase outputs can be achieved.

[0119] The following is combined Figure 2 The external load test method for static full-power verification of new energy locomotives (or their main power sources) is further explained in detail:

[0120] (a) Locomotive and Load Preparation: Park the new energy locomotive 1 in the designated test area and apply the parking brake to ensure safety. Prepare the external resistor load cabinet 2. Disconnect the traction motor cable from the U, V, and W phase output terminals of the traction inverter 3. Connect one end of the external resistor load cabinet 2 to the U phase output terminal of the traction inverter 3 and the other end to the V phase output terminal.

[0121] (b) System Setup and Inverter Reconfiguration: Enter external load test mode. The locomotive control system reconfigures the control logic of the traction inverter 3. An equivalent chopper circuit is constructed using the U-phase bridge arm (including U-phase upper bridge arm switch 31 and U-phase lower bridge arm switch 32) and the V-phase bridge arm (including V-phase upper bridge arm switch 41 and V-phase lower bridge arm switch 42). For example, the on and off of the U-phase upper bridge arm switch 31 and V-phase lower bridge arm switch 42 (or the on and off of the U-phase lower bridge arm switch 32 and V-phase upper bridge arm switch 41) are synchronously controlled by a PWM control strategy. When the U-phase upper bridge arm switch 31 and V-phase lower bridge arm switch 42 are on, the current path is: DC bus positive terminal -> U-phase upper bridge arm switch 31 -> U-phase output terminal -> external resistor load cabinet 2 -> V-phase output terminal -> V-phase lower bridge arm switch 42 -> DC bus negative terminal. Unused W-phase bridge arm switches remain off. Alternatively, external resistor load cabinet 2 can be connected between the U-phase output terminal and the DC bus neutral point N (if the DC side midpoint of the traction inverter 3 is available). In this case, only the U-phase bridge arms (U-phase upper bridge arm switch 31 and U-phase lower bridge arm switch 32) need to be used to configure a chopper. For example, by controlling the U-phase upper bridge arm switch 31 to turn on via PWM, the current flows back to the neutral point N through the external resistor load cabinet 2 or freewheels through the freewheeling diode of the U-phase lower bridge arm switch 32.

[0122] (c) Test execution:

[0123] The power source of the new energy locomotive 1, such as the diesel generator set 21, supplies power to the DC bus through the three-phase uncontrolled rectifier 22, or the first power battery pack 11 supplies power to the DC bus through the first bidirectional DC / DC converter 12 and / or the second power battery pack 13 supplies power to the DC bus through the second bidirectional DC / DC converter 14.

[0124] The locomotive control system calculates and outputs a PWM signal to control the selected switching devices in the traction inverter 3 based on the input test power.

[0125] Real-time monitoring of DC bus voltage and current, voltage, current and temperature on external resistor load cabinet 2, and temperature of traction inverter 3 and power source, etc.

[0126] Gradually increase the test power to the target value.

[0127] (d) Parallel connection of multiple inverters: If a single traction inverter 3 and a single external resistor load cabinet 2 are insufficient to simulate full power, other traction inverters on the locomotive can be configured in the same way and connected in parallel to their respective (or shared segmentable) external resistor load cabinets.

[0128] (e) Data analysis: Evaluate the power source's power supply capacity, DC bus stability, efficiency, temperature rise, and reliability of traction inverter 3 when operating as a chopper.

[0129] In summary, the core of the static external load test method for new energy locomotives lies in: disconnecting the traction motor; connecting the external resistive load cabinet to the output terminal of the traction inverter (e.g., between phases U and V, or between phase U and the neutral line); configuring at least one or two arms of the traction inverter as a chopper circuit through specific control logic to regulate the power from the locomotive's DC bus to the external resistive load. By controlling the chopper, the energy from the locomotive's power source is applied to the external resistive load cabinet to assess the performance of the power source and converter system. The method also includes implementations using multiple traction inverters in parallel to increase the test power.

[0130] The above embodiments mainly illustrate the chopping method using the coordinated operation of the U and V bridge arms. The following describes the single-bridge-arm chopping method: An external resistive load cabinet is connected between the U-phase output terminal and the negative terminal of the DC bus; chopping can be achieved simply by controlling the U-phase bridge arm. Similarly, an external resistive load cabinet is connected between the V-phase output terminal and the negative terminal of the DC bus; chopping can be achieved simply by controlling the V-phase bridge arm.

[0131] Compared with existing technologies, the embodiments of this invention have the following beneficial effects: They solve the problem of the lack of traditional self-load testing methods for new energy locomotives. Compared with solutions requiring expensive dedicated mobile load boxes, this invention fully utilizes existing locomotive components, resulting in a significant cost advantage, especially by innovatively utilizing traction inverters to achieve chopper loading, further reducing costs. The testing is highly flexible, allowing for the separate or comprehensive evaluation of key components. Compared with bench testing detached from the vehicle environment, the on-vehicle testing of this invention more realistically reflects the performance of components under actual coupling and heat dissipation conditions. Compared with inconvenient and inefficient bench testing, this invention is easy to operate, lower in cost, and has a shorter testing cycle. Compared with solutions unsuitable for some new energy locomotives, this invention provides high-power performance evaluation of key power components of new energy locomotives under static conditions, which is beneficial for performance assessment and fault diagnosis. Compared with existing technologies with poor scalability, this invention can adapt to different power requirements by adding or removing external resistor load cabinets or paralleling traction inverters, offering good scalability.

[0132] Optionally, chopping the DC power from the power source of the new energy locomotive using switching devices in at least one or two of its internal bridge arms includes:

[0133] At least two arms of the traction inverter form an equivalent DC / DC chopper circuit through a specific pulse width modulation control strategy.

[0134] Specifically, the U-phase and V-phase bridge arms of the traction inverter can form an equivalent DC / DC chopper circuit through a specific PWM (Pulse Width Modulation) control strategy. Under specific control, the traction inverter realizes the chopping function, and by controlling the chopper, the energy of the locomotive power source is applied to the external resistive load cabinet to evaluate the performance of the power source and converter system.

[0135] Continue to refer to Figure 2 Optionally, at least two arms of the traction inverter form an equivalent DC / DC chopper circuit through a specific pulse width modulation control strategy, including:

[0136] The external resistive load cabinet is connected between the U-phase and V-phase output terminals of the traction inverter, and the external resistive load cabinet is chopped and powered by a specific combination of U-phase and V-phase associated switching devices through synchronous control.

[0137] Specifically, in combination Figure 2The U-phase and V-phase bridge arms of the traction inverter 3 can form an equivalent DC / DC chopper circuit through a specific PWM (Pulse Width Modulation) control strategy. For example, by synchronously controlling the on and off of the U-phase upper bridge arm switch 31 and the V-phase lower bridge arm switch 42 (or the U-phase lower bridge arm switch 32 and the V-phase upper bridge arm switch 41), chopper loading of the external resistive load cabinet 2 connected between the U-phase and V-phase outputs can be achieved.

[0138] Optionally, the static load test method for new energy locomotives also includes: when the test power requirement is large, using multiple traction inverters with the same configuration and their corresponding external resistor load cabinets in parallel to evaluate the performance of the power source and traction inverter of the new energy locomotive.

[0139] Specifically, depending on the needs, when the test power requirement is large, multiple traction inverters configured according to steps a) to c) above and their corresponding external resistor load cabinets can be used in parallel to meet the higher test power requirements.

[0140] The core objective of this invention is to economically and conveniently conduct high-power performance testing on key power components (diesel generator sets, power battery packs, bidirectional DC / DC converters, etc.) of new energy locomotives under static conditions. Theoretically, other possible technical paths exist to achieve similar objectives, but they each have limitations or differ in their focus from this invention.

[0141] Alternative Option 1: Use a dedicated mobile high-power load cell / load vehicle.

[0142] Solution Description: Design and manufacture a portable high-power resistive load box or a dedicated load test vehicle, which is connected to the DC bus or AC output terminal of the new energy locomotive (if applicable) via cable to load the locomotive's power system.

[0143] Comparison with and disadvantages of this invention: This solution is similar to the "external resistor load cabinet" concept in Solution 3 of this invention. However, one of the innovations of Solution 3 is that it utilizes the existing traction inverter of the locomotive for chopping control, thereby simplifying the functional requirements of the external load box (the external load box can be a passive resistor, without the need to integrate complex control and chopping functions). If the mobile load box itself integrates complex control and power conversion functions, its cost will increase significantly, and its versatility may be limited.

[0144] Compared to the "self-testing" schemes of Scheme 1 (diesel generator charging power battery pack) and Scheme 2 (energy transfer between power battery packs), which fully utilize the internal energy cycle of the locomotive, additional large external equipment is still required.

[0145] Alternative Option 2: Utilize the power grid as a load or energy source (V2G / G2V test).

[0146] Solution Description: If the new energy locomotive is equipped with a bidirectional converter and the test site has a corresponding grid connection interface, the locomotive can be controlled to feed the power energy of its power battery back to the grid (as a load test battery discharge), or draw power from the grid for high-power charging (test battery charging); for hybrid vehicles, diesel generator set power generation can also be considered for grid connection.

[0147] Compared to the present invention, the disadvantages are as follows: It requires the locomotive to possess complex grid-connection functions and control strategies, and places high demands on the grid connection conditions of the test site (such as capacity, power quality, protection configuration, grid connection permits, etc.), resulting in poor versatility. The control objectives, safety requirements, and procedures for grid-connection testing differ from the static component performance evaluation of the present invention, and it may not be able to flexibly simulate specific load curves or evaluate the extreme performance of components in independent operating modes. The initial investment and technical complexity are far higher than the solution proposed in this invention.

[0148] Alternative Option 3: Energy feedback from the machine shop.

[0149] Solution Description: Two locomotives are used, one as the test vehicle (outputting energy) and the other as the companion vehicle (absorbing energy, for example, consuming it through its regenerative braking system or charging it into its battery).

[0150] Compared with this invention, the disadvantages are as follows: It requires the simultaneous scheduling of two locomotives, making operation complex and costly. The control and coordination of the quantity feedback is difficult, and accurately controlling the load state of specific components of the test vehicle is challenging. The accompanying test vehicle also needs to possess corresponding energy absorption and dissipation capabilities.

[0151] In summary, although other theoretical possibilities exist, the three solutions proposed in this invention, especially the utilization of internal locomotive energy circulation (Solution 1 and Solution 2) and the ingenious modification of existing component functions (Solution 3), have significant advantages in terms of economy, convenience, and adaptability to existing new energy locomotive structures.

[0152] Energy internal balance and conversion utilization in embodiments of the present invention:

[0153] For hybrid locomotives, the key lies in precisely controlling the charging process of the diesel generator set to the power battery pack, so that the power battery pack is equivalent to an adjustable high-power load, thereby enabling the diesel generator set to be loaded.

[0154] For pure battery locomotives (or hybrid locomotive battery systems), the key is to achieve controllable high-power energy transfer between different power battery units (packs) in the vehicle, simulating high-rate charging and discharging conditions by "one group discharging and the other group charging".

[0155] Functional reuse and reconfiguration of traction inverters:

[0156] This is the core of the static load test method for new energy locomotives. Without adding an extra high-power onboard chopper, a specific control strategy is used to reconfigure and control some of the bridge arms of the traction inverter originally used to drive the traction motor (e.g., the upper and lower bridge arms of the U and V phases), making it equivalent to a DC / AC (and then to a resistive load) or directly equivalent to a DC / DC chopper, thus performing chopping power regulation on an external purely resistive load.

[0157] Key technologies include: the connection method of the external resistor load cabinet (e.g., Figure 2 The design of the PWM control algorithm for the corresponding bridge arm switching devices (such as IGBTs) is shown in the U and V phase connections to ensure that the inverter can operate stably and safely in chopper mode and accurately control the power output to the resistor.

[0158] System integration and control strategies:

[0159] Develop a unified test control system or mode that can execute the different test schemes mentioned above based on the selection.

[0160] The control system must have precise power regulation capabilities, comprehensive parameter monitoring (voltage, current, temperature, SOC, diesel engine parameters, etc.) and reliable safety protection functions (overcurrent, overvoltage, overtemperature, etc.).

[0161] For static load testing methods of new energy locomotives, the locomotive control system needs to manage the disconnection of the traction motor, the detection of external load connection, and the switching of inverter operating modes.

[0162] Continue to refer to Figure 2 The embodiments of the present invention also provide a new energy locomotive self-load test system, which includes: a new energy locomotive 1 and an external resistor load cabinet 2 connected to each other;

[0163] New energy locomotives include: locomotive control system, at least one traction inverter 3, and traction motor;

[0164] When the new energy locomotive is a hybrid electric locomotive, it also includes: a diesel generator set, a three-phase uncontrolled rectifier, and at least one power battery pack.

[0165] When the new energy locomotive is a pure electric locomotive, it also includes: at least two power battery packs and at least two bidirectional DC-DC devices;

[0166] The locomotive control system is connected to the traction inverter 3, and the traction inverter 3 is connected to the traction motor;

[0167] After the diesel generator set 21 is connected to the three-phase uncontrolled rectifier 22, it is connected to the traction inverter 3 through the DC bus. The diesel generator set 21 is used to supply power to the traction inverter 3. After the power battery pack is connected to the bidirectional DC / DC converter, it is connected to the traction inverter 3 through the DC bus. The power battery pack is used to supply power to the traction inverter 3.

[0168] The first end of the external resistor load cabinet 2 is connected to the U-phase output terminal of the traction inverter 3, and the second end of the external resistor load cabinet 2 is connected to the V-phase output terminal of the traction inverter 3. The external resistor load cabinet 2 is used for the external load test for full power verification of new energy locomotives.

[0169] The locomotive control system includes multiple locomotive control units, which are used to execute the self-load test method for new energy locomotives provided in any embodiment of the present invention; or, the locomotive control units are used to execute the static load test method for new energy locomotives provided in any embodiment of the present invention.

[0170] Specifically, Figure 2 An example is shown where a new energy vehicle includes: a first power battery pack 11, a second power battery pack 13, a first bidirectional DC / DC converter 12, and a second bidirectional DC / DC converter 14.

[0171] The locomotive control unit is used to receive test commands, select and execute the corresponding test modes, control the working status of relevant components, and collect and process test data.

[0172] The energy management system inside the new energy locomotive 1 includes: a diesel generator set 21 and a three-phase uncontrolled rectifier 22 for it, and / or at least two power battery packs (e.g., a first power battery pack 11 and a second power battery pack 13) and at least two bidirectional DC / DC converters associated with them (e.g., a first bidirectional DC / DC converter 12 and a second bidirectional DC / DC converter 14).

[0173] External resistor load cabinet 2 is a resistor load device independent of the locomotive. External resistor load cabinet 2 is either part of the system or a necessary component used in conjunction with the system.

[0174] The converter system is located inside the new energy locomotive 1, and mainly refers to the traction inverter 3. Under specific control, the traction inverter in this converter system can achieve chopping function.

[0175] The aforementioned new energy locomotive self-load test system can execute the new energy locomotive self-load test method or the new energy locomotive static load test method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects for executing the new energy locomotive self-load test method or the new energy locomotive static load test method.

[0176] Continue to refer to Figure 2 Optionally, the traction inverter 3 includes: at least one U-phase bridge arm and a V-phase bridge arm, wherein the U-phase bridge arm is composed of U-phase upper bridge arm switching device and U-phase lower bridge arm switching device connected in series, and the V-phase bridge arm is composed of V-phase upper bridge arm switching device and V-phase lower bridge arm switching device connected in series.

[0177] The U-phase bridge arm and the V-phase bridge arm are connected in parallel between the positive and negative terminals of the DC bus. The connection point of the U-phase upper bridge arm switch device 31 and the U-phase lower bridge arm switch device 32 forms the U-phase output terminal of the traction inverter 3, and the connection point of the V-phase upper bridge arm switch device 41 and the V-phase lower bridge arm switch device 42 forms the V-phase output terminal of the traction inverter 3. The switching devices of the U-phase bridge arm and the V-phase bridge arm are controlled by the locomotive control system to realize the chopping power supply function of the external resistive load cabinet connected between the U-phase output terminal and the V-phase output terminal.

[0178] Specifically, Figure 2 The diagram illustrates that the power source (diesel generator set 21) in the new energy locomotive 1 supplies power to the traction inverter 3 via a three-phase uncontrolled rectifier 22, or via a first power battery pack 11 and a second power battery pack 13 via a first bidirectional DC / DC converter 12 and a second bidirectional DC / DC converter 14 through a DC bus. The U and V phase output terminals (W phase is unused) of the traction inverter 3 are connected to an external resistor load cabinet 2. The switching devices of the U phase and V phase bridge arms (U phase upper bridge arm switch 31, U phase lower bridge arm switch 32, V phase upper bridge arm switch 41 and V phase lower bridge arm switch 42) are used to realize the chopping function.

[0179] Optionally, the self-load test system for new energy locomotives also includes: a connection interface;

[0180] The connection interface is located between the external resistive load cabinet and the traction inverter. The connection interface is used to safely connect the external resistive load cabinet to the traction inverter.

[0181] Specifically, the aforementioned new energy locomotive self-load test system further includes a connection interface for connecting an external resistor load cabinet.

[0182] Optionally, the locomotive control unit includes: a test mode selection module, a parameter monitoring and recording module, and a safety protection module connected in sequence;

[0183] The test mode selection module is used to select and switch test modes for new energy locomotives, the parameter monitoring and recording module is used to monitor and record parameters during the test of new energy locomotives, and the safety protection module is used to provide safety protection during the test of new energy locomotives.

[0184] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A self-load test method for new energy locomotives, characterized in that, An application is provided in a self-load test system for new energy locomotives. The self-load test system for new energy locomotives includes: a new energy locomotive; the new energy locomotive includes: a locomotive control system, at least one traction inverter, and a traction motor. When the new energy locomotive is a hybrid electric locomotive, it also includes: a diesel generator set, a three-phase uncontrolled rectifier, and at least two power battery packs; When the new energy locomotive is a pure electric locomotive, it also includes: at least two power battery packs and at least two bidirectional DC / DC converters; The self-load test method for the new energy locomotive includes: When the new energy locomotive is a hybrid electric locomotive, the locomotive control system controls the diesel generator set to charge the first or second power battery pack, and evaluates the performance of the diesel generator set by adjusting the charging power. When the new energy locomotive is a pure electric locomotive, the locomotive control system controls one power battery pack and a bidirectional DC / DC converter to transfer energy to another power battery pack and a bidirectional DC / DC converter, and evaluates the high-power charging and discharging characteristics of the power battery pack by adjusting the energy transfer power.

2. The method according to claim 1, characterized in that, The performance evaluation of the diesel generator set by adjusting the charging power includes: The output power of the diesel generator set is adjusted according to the preset test power curve or constant power command, and the operating parameters of the diesel generator set, the first power battery pack and the second power battery pack are monitored in real time.

3. The method according to claim 1, characterized in that, The evaluation of the high-power charge and discharge characteristics of the power battery pack by adjusting the energy transfer power includes: The first bidirectional DC / DC converter and the second bidirectional DC / DC converter control the energy transfer between the first power battery pack and the second power battery pack, and monitor the operating parameters of each relevant power battery pack in real time.

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