A method and device for diagnosing motor shaft breakage in a frame-controlled traction EMU

Abstract

The present invention relates to a method and device for diagnosing motor shaft breakage in a frame-controlled traction mode EMU train, comprising the following steps: collecting the inverter output current of the traction inverter of the monitored EMU motor, the speed signals of each motor, and the EMU torque preset value; determining the operating state of the traction inverter; if the traction inverter is in traction or electric braking, comparing the difference in output current of two inverters sharing a common intermediate circuit; when the difference is greater than a certain range, detecting whether the motor under the inverter with the larger output current has a shaft breakage; if the traction inverter is in coasting, directly proceeding to the next step; comparing the difference between the stator current frequency and the rotor rotation frequency of each motor under the same inverter, i.e., the slip; when the slip of a motor is close to 0, determining that the motor has a shaft breakage. The motor shaft breakage detection device of the present invention can improve the scientificity and timeliness of routine maintenance of EMUs and ensure the stable operation of EMU equipment.

Description

Technical Field

[0001] The present invention relates to the field of fault diagnosis of traction motors of EMUs, and in particular to a method and device for diagnosing broken shafts of motors of EMUs in a frame-controlled traction mode. Background Art

[0002] The control technology of the traction motor of an EMU is one of the core technologies of the entire vehicle system. The quality of its control performance plays a decisive role in whether the EMU can operate safely and stably.

[0003] There are three control methods for high-speed EMU traction systems: axle control, frame control, and vehicle control. Axle control involves a single inverter loading one motor. Frame control involves a single inverter loading two motors, both mounted on the same bogie. Vehicle control involves a single inverter loading four motors, distributed across the same EMU, with two motors per bogie. The motor is mounted on the bogie and ultimately drives the wheels to produce rolling motion through transmission mechanisms such as couplings and gearboxes. When the transmission mechanism between the motor and wheelset fails, such as a disconnected coupling or gearbox failure, the connection between the motor and wheelset is severed, resulting in a broken axle. This failure requires prompt diagnosis and appropriate protective action to prevent further escalation.

[0004] In the current operation of EMUs, traction motor shaft breakage is an occasional inertial mass problem, which generally occurs during the operation of the EMU. Common causes of motor shaft breakage failure include: (1) excessive load on the motor, especially the large impact load during the electric braking and traction dynamic process; (2) large concentricity deviation between the motor and the reduction gearbox; (3) excessive stress concentration on the motor shaft during operation, causing cracks in the motor shaft and then spreading, etc. If a shaft breakage failure occurs during the operation of the EMU and is not detected in time, the EMU will continue to operate in this case. On the one hand, other motors that have not experienced shaft breakage will be in a long-term overload state, causing the motor temperature to rise too high, thus affecting their operational safety and service life. On the other hand, if the shaft breakage problem is caused by mechanical reasons, it may further affect the operational safety of the EMU and may even cause a train safety accident in severe cases. Therefore, once a motor shaft breakage failure occurs, the system needs to identify it in time and quickly perform traction removal. Summary of the Invention

[0005] In order to solve the problem of operational safety of EMUs caused by motor shaft breakage failure, the present invention provides a method and device for diagnosing motor shaft breakage of EMUs in a frame-controlled traction mode.

[0006] The present invention is achieved through the following technical solutions: A method for diagnosing motor shaft breakage in a frame-controlled traction EMU comprises the following steps:

[0007] Step 1: Collect the inverter output current of the traction converter of the monitored EMU motor, the speed signal of each motor, and the EMU torque preset value;

[0008] Step 2: Determine the operating status of the traction inverter;

[0009] Step 3: If the traction converter is in traction or electric braking mode, compare the output current difference between the two inverters sharing the same intermediate circuit. If the difference is greater than a certain range, check whether the motor under the inverter with the larger output current has a broken shaft, and then proceed to step 5.

[0010] Step 4: If the traction converter is in coasting mode, go directly to step 5.

[0011] Step 5: Compare the difference between the stator current frequency and the rotor rotation frequency of each motor under the same inverter, that is, the slip. When the slip of a motor is close to 0, it is determined that the motor has a broken shaft.

[0012] The present invention further provides a motor shaft breakage detection device for a motor shaft breakage diagnosis method of a train with a frame-controlled traction mode, comprising a data acquisition module and a shaft breakage state diagnosis module.

[0013] The output end of the data acquisition module is connected to the broken shaft state diagnosis module.

[0014] As a further improvement of the technical solution of the motor broken shaft detection device described in the present invention, the data acquisition module is used to collect the three-phase current value, current frequency, and speed signal of each motor of the traction inverter of the monitored EMU motor; the broken shaft status diagnosis module is used to determine the broken shaft status of each motor based on the operating status of each motor and the pre-acquired broken shaft status comparison value.

[0015] The present invention's motor shaft breakage diagnosis method and device for EMUs operating in a frame-controlled traction mode monitors the three-phase current, current frequency, and speed signals of each motor in the traction converter used to monitor the EMU motors. The motor shaft breakage status is determined based on the operating status of each motor and a pre-acquired shaft breakage status comparison value, thereby improving the reliability of EMU motor shaft breakage monitoring. The present invention's motor shaft breakage detection device can improve the scientificity and timeliness of routine maintenance on EMUs, ensuring the stable operation of EMU equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 It is a structural schematic diagram of the motor broken shaft detection device.

[0018] Figure 2 A flow chart of the diagnostic method is shown in FIG.

[0019] Figure 3 Another flowchart of the diagnostic method is shown in FIG. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0021] A method for diagnosing a broken shaft of a motor of a train in a frame-controlled traction mode comprises the following steps:

[0022] Step 1: Collect the inverter output current of the traction converter of the monitored EMU motor, the speed signal of each motor, and the EMU torque preset value;

[0023] Step 2: Determine the operating status of the traction inverter;

[0024] Step 3: If the traction converter is in traction or electric braking mode, compare the output current difference between the two inverters sharing the same intermediate circuit. If the difference is greater than a certain range, check whether the motor under the inverter with the larger output current has a broken shaft, and then proceed to step 5.

[0025] Step 4: If the traction converter is in coasting mode, go directly to step 5.

[0026] Step 5: Compare the difference between the stator current frequency and the rotor rotation frequency of each motor under the same inverter, that is, the slip. When the slip of a motor is close to 0, it is determined that the motor has a broken shaft.

[0027] When a shaft breakage occurs in motor 1 (M1), the current of the broken motor 1 decreases. However, the current of motor 2 (M2), which is not broken and is connected to the same inverter 1, increases to a value greater than the sum of the currents of motors 1 and 2. This means that the inverter output current increases compared to the original current. Furthermore, the sum of the currents of motors 1 and 2 exceeds the sum of the currents of motors 3 (M3) and 4 (M4) of inverter 2, which share the same intermediate circuit. Specifically, by comparing the input currents of the two inverters in the same converter, if the difference in output current between inverter 1 and inverter 2 is significant, it is necessary to detect whether the motor in that inverter has a broken shaft. Motor 1 on that shaft will be unable to generate power. According to the asynchronous motor torque formula, when the motor output torque is zero, the slip also returns to zero. The motor speed and stator frequency are essentially the same, but the rotor speeds of motors 1 and 2 differ, and the rotor speeds of motor 1 differ from those of motors 2, 3, and 4.

[0028] At the same time, under traction, braking, and coasting conditions, when a motor has a broken shaft, the stator current frequency of the broken shaft motor is the same as the rotor rotation frequency, and the slip is close to 0. The change in the rotor speed of the broken shaft motor affects the calculation of the given speed in the speed outer loop control of the inverter control. The inverter current frequency changes, and the slip of the motor without broken shaft increases, that is, the difference between the frequency of the inverter's given stator current and the rotor rotation frequency increases. Compared with the inverter with a common intermediate circuit, the given current frequency of the inverter where the faulty motor is located begins to differ. Therefore, in the present invention, the speed difference between the two motors under the same inverter and the current frequency difference between the two inverters with a common intermediate circuit are both identified as characteristic values ​​for broken shaft diagnosis.

[0029] like Figure 2 As shown, the present invention provides a motor shaft breakage detection device for a motor shaft breakage diagnosis method of a train with a frame-controlled traction mode, comprising a data acquisition module and a shaft breakage state diagnosis module.

[0030] The output end of the data acquisition module is connected to the broken shaft state diagnosis module.

[0031] Specifically, the data acquisition module is used to collect the three-phase current value, current frequency, and speed signal of each motor of the traction inverter of the monitored EMU motor; the broken axle status diagnosis module is used to determine the broken axle status of each motor based on the operating status of each motor and the pre-acquired broken axle status comparison value.

[0032] The present invention's motor shaft breakage diagnosis method and device for EMUs operating in a frame-controlled traction mode monitors the three-phase current, current frequency, and speed signals of each motor in the traction converter used to monitor the EMU motors. The motor shaft breakage status is determined based on the operating status of each motor and a pre-acquired shaft breakage status comparison value, thereby improving the reliability of EMU motor shaft breakage monitoring. The present invention's motor shaft breakage detection device can improve the scientificity and timeliness of routine maintenance on EMUs, ensuring the stable operation of EMU equipment.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for diagnosing motor shaft breakage in a frame-controlled traction EMU, characterized in that: The following steps are involved: Step 1: Collect the inverter output current of the traction converter of the monitored EMU motor, the speed signal of each motor, and the EMU torque preset value; Step 2: Determine the operating status of the traction inverter; Step 3: If the traction converter is in traction or electric braking mode, compare the output current difference between the two inverters sharing the same intermediate circuit. If the difference is greater than a certain range, check whether the motor under the inverter with the larger output current has a broken shaft, and then proceed to step 5. Step 4: If the traction converter is in coasting mode, go directly to step 5. Step 5: Compare the difference between the stator current frequency and the rotor rotation frequency of each motor under the same inverter, that is, the slip. When the slip of a motor is close to 0, it is determined that the motor has a broken shaft.

2. The motor shaft breakage detection device of the motor shaft breakage diagnosis method of the EMU with frame-controlled traction mode as claimed in claim 1 is characterized in that: Including data acquisition module, broken shaft status diagnosis module, The output end of the data acquisition module is connected to the broken shaft state diagnosis module.

3. The motor shaft breakage detection device according to claim 2, characterized in that: The data acquisition module is used to collect the three-phase current value, current frequency and motor speed signal of the traction converter of the monitored EMU motor; The broken shaft state diagnosis module is used to determine the broken shaft state of each motor according to the operating state of each motor and the pre-acquired broken shaft state comparison value.

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