Double-end driving long shaft system multi-order torsional vibration test platform and torsional vibration identification and suppression method

Abstract

The application provides a double-end driving long shaft system multi-order torsional vibration test platform and a torsional vibration identification and suppression method, and relates to the technical field of long shaft system variable frequency driving. The platform comprises two double-winding driving motors arranged at two ends of the shaft system respectively, a load motor located at the middle part, and a switchable shaft system connecting structure, and is matched with a double-master double-slave cooperative control system composed of four driving frequency converters. The method realizes controllable excitation of multi-order torsional vibration by superimposing the load torque step and the frequency excitation source, extracts the speed fluctuation characteristics by using the difference amplification and double-channel filtering of the signal processing module, and accurately identifies the critical speeds of each order of the system. In view of the identified torsional vibration, the torque instruction of the frequency converter is corrected by using the speed differential negative feedback algorithm, and the torsional vibration energy of the elastic transmission chain is offset by actively enhancing the electrical damping of the system. The application solves the problems that the super-large unit is difficult to reproduce the complex working condition torsional vibration in a safe and controllable environment and verify the suppression strategy.

Description

Technical Field

[0001] This invention relates to the field of frequency conversion drive technology for long shaft systems, and more specifically, to a dual-end driven long shaft system multi-stage torsional vibration test platform and a torsional vibration identification and suppression method. Background Technology

[0002] In the field of long-shaft compressor drives, especially for experimental devices such as wind tunnel compressors with special shaft structures that need to operate at a wide range of speeds, variable frequency drive technology has become the mainstream choice. However, as compressors become larger, with shaft power reaching over 200MW, some ultra-large projects often adopt complex drive forms such as multiple machines with multiple windings and double-end drive, which brings significant torsional vibration safety hazards to the stable operation of the system.

[0003] Due to the long shaft length and wide operating speed range, the critical speed of the system's shaft is very likely to fall into the normal operating speed range. When using a frequency converter for drive, the harmonic current output by the frequency converter will generate torque pulsation. When the pulsation frequency coincides with the mechanical resonance point of the shaft, it will aggravate the critical speed resonance within the operating speed range, which may lead to shaft breakage or equipment damage in severe cases.

[0004] Currently, research on torsional vibration problems in such ultra-large long shaft systems faces the following main difficulties: High risks associated with actual machine testing: Directly conducting torsional vibration reproduction, excitation testing, or research on suppression methods on ultra-large generating units in actual operation carries extremely high safety risks. Once torsional vibration goes out of control, it will cause huge economic losses and safety accidents.

[0005] Lack of dedicated research platforms: The industry lacks physical testing platforms that can flexibly simulate various driving forms such as double-end drag and multi-winding, and whose shaft parameters (such as length, stiffness, and inertia) are adjustable, making it impossible to accurately reproduce torsional vibration phenomena for different working conditions.

[0006] Insufficient detection and verification methods: Existing technologies lack an integrated solution that can stably excite torsional vibration, accurately separate and detect weak torsional vibration signals, and efficiently verify the effectiveness of suppression strategies. As a result, the research and development of torsional vibration suppression technology remains largely at the theoretical level, with long debugging cycles and high risks in practical verification.

[0007] Therefore, there is an urgent need for a torsional vibration research platform that can strictly follow the principle of dynamic similarity, has diverse driving methods and load simulation functions, and can achieve quantitative verification of torsional vibration suppression effect, so as to provide key technical support for the safe and stable operation of ultra-large units. Summary of the Invention

[0008] The present invention aims to solve at least one of the aforementioned technical problems existing in the prior art.

[0009] Therefore, the first aspect of the present invention provides a dual-end driven long shaft system multi-stage torsional vibration test platform.

[0010] A second aspect of the present invention provides a method for identifying and suppressing torsional vibration.

[0011] This invention provides a dual-end driven long shaft system multi-stage torsional vibration test platform, comprising: A multi-winding drive motor, with two multi-winding drive motors respectively set at both ends of the shaft system to be tested, and a speed encoder is provided on the non-drive end of each multi-winding drive motor; A load motor is disposed between the two multi-winding drive motors, wherein the two multi-winding drive motors are respectively connected to both sides of the load motor through a shaft connection structure to form a long shaft structure with double-end drive. A frequency converter drive assembly includes multiple drive frequency converters and at least one load frequency converter. The multiple drive frequency converters are respectively connected to each set of windings of the two multi-winding drive motors, and the load frequency converter is connected to the load motor. Multiple drive inverters are configured in a master-slave cooperative control topology, wherein: The two drive frequency converters, which are respectively connected to the first set of windings of the two multi-winding drive motors, are configured as main frequency converters to independently acquire the speed feedback signal of the speed encoder on the corresponding side and generate torque command based on the speed feedback signal. Other drive inverters connected to the remaining windings of the two multi-winding drive motors are configured as slave inverters. Each slave inverter is communicatively connected to the corresponding master inverter and is used to receive synchronization commands issued by the master inverter and follow the operation. The signal processing module is communicatively connected to the speed encoder and the inverter drive assembly. It is used to process the speed feedback signal to identify torsional vibration characteristic signals and to feed back the torsional vibration suppression signal to the two main inverters.

[0012] The dual-end driven long shaft multi-stage torsional vibration test platform according to the above-described technical solution of the present invention may also have the following additional technical features: In the above technical solution, the shaft connection structure includes the following three switchable connection methods: coupling extended shaft connection, direct coupling connection, or direct coupling connection of the two multi-winding drive motors; wherein, the coupling adopts a combination structure of rigid coupling and elastic diaphragm coupling.

[0013] The above technical solution also includes a rigid mounting base, which has mounting holes that are equidistant from the base holes of the two multi-winding drive motors and the load motor, for alignment installation to accommodate different shaft connection methods.

[0014] In the above technical solution, the current distribution strategy executed by the multiple drive inverters is configured as follows: Under steady-state operation, the output current of the two main frequency converters and the corresponding two slave frequency converters is equally distributed; when the winding current deviation is detected to exceed the set threshold, the main frequency converter issues a current adjustment command to correct the output current of the slave frequency converter.

[0015] In the above technical solution, the signal processing module includes: The speed waveform amplification output unit is used to proportionally amplify the difference between the per-unit speed measured by the speed encoder and the reference command, and then output it after superimposing a DC bias. The dual-channel filtering unit is used to filter and amplify the speed feedback signal through bandpass filters whose center frequency corresponds to different torsional vibration frequency points, so as to highlight the characteristics of the torsional vibration waveform.

[0016] The present invention provides a torsional vibration identification and suppression method, which is performed based on a dual-end driven long shaft multi-stage torsional vibration test platform as described in any of the above technical solutions. The method includes the following steps: The load motor is controlled by the load inverter to apply load disturbance to the long shaft system structure, thereby stimulating torsional vibration of the system. The two speed encoders are used to collect the rotational speed feedback signals at both ends of the long shaft system in real time, and the critical speed and torsional vibration order are identified by the signal processing module. The speed differential negative feedback algorithm is adopted, in which the two main frequency converters extract the high-frequency fluctuation component in the speed feedback signal and perform differential processing to generate a torsional vibration suppression signal; The torsional vibration suppression signal is synchronously applied to the torque command channel of each of the drive frequency converters, thereby suppressing torsional vibration fluctuations by correcting the electrical damping of the motor output torque enhancement system.

[0017] The torsional vibration identification and suppression method according to the above-described technical solution of the present invention may further have the following additional technical features: In the above technical solution, the torsional vibration excitation system includes at least one of the following methods: Torque step excitation: The load motor is used to achieve a sudden loading or sudden unloading of a set proportion of load fluctuation; Frequency excitation source superposition: A sinusoidal torque pulsation signal with a set frequency and amplitude is superimposed on the torque command of the load inverter or multiple drive inverters.

[0018] In the above technical solution, the features for identifying the critical speed and torsional vibration order include: If the speed fluctuations of the two speed encoders are out of phase and their amplitudes match, then it is determined to be a first-order torsional vibration. If the speed fluctuations of the two speed encoders are in the same phase and have the same amplitude, then it is determined to be a second-order torsional vibration.

[0019] In the above technical solution, the generation process of the torsional vibration suppression signal includes: The average speed is obtained by processing the speed feedback signal through a first-order low-pass filter. The high-frequency fluctuation component is obtained by subtracting the average rotational speed from the rotational speed feedback signal. The high-frequency fluctuation component is differentiated and its gain is adjusted to generate the torsional vibration suppression signal.

[0020] In the above technical solution, the rotational speed differential negative feedback algorithm is tuned by adjusting the filter time constant and the proportional coefficient. The filter time constant is selected to achieve frequency domain separation between the torsional vibration signal and the measurement noise, and the proportional coefficient is increased to enhance the damping strength for long shaft structures.

[0021] In summary, due to the adoption of the above-mentioned technical features, the beneficial effects of the present invention are: The dual-end driven long shaft system multi-stage torsional vibration test platform and torsional vibration identification and suppression method described in this invention have significant technical advantages and application value. Firstly, the platform, through a scaled-down physical simulation architecture, can accurately reproduce the complex driving forms unique to ultra-large generator units, such as dual-end driven and multi-winding driven systems. The scaling system, designed based on the principle of dynamic similarity, strictly adheres to the criteria of frequency similarity, stiffness similarity, and inertia similarity, ensuring that the test platform maintains a high degree of consistency with prototype units such as the 240MW generator unit in terms of torsional vibration response laws and modal characteristics. This makes the test data directly applicable to actual engineering projects. With three quickly switchable shaft connection methods, the platform can flexibly simulate various operating conditions, including long shaft systems, short shaft systems, and no-load direct connections, solving the problem that existing technologies struggle to simulate diverse long shaft system operating states under controlled environments.

[0022] In the area of ​​torsional vibration excitation and detection, this invention employs a dual-mode excitation mechanism combining torque step and frequency excitation sources. This mechanism can naturally reproduce sudden torsional vibration scenarios during operation and provide a precise and controllable target excitation source to meet different research needs. Through the coordinated processing of differential amplification, DC bias, and dual-channel bandpass filtering in the signal processing module, the system can effectively filter out interference and highlight the characteristics of the torsional vibration signal, achieving high-definition visualization and precise quantitative detection of the torsional vibration waveform. This high-precision signal processing method allows minute speed fluctuations to be intuitively captured, providing an accurate feedback basis for the subsequent formulation of suppression strategies.

[0023] Furthermore, the speed differential negative feedback algorithm proposed in this invention exhibits excellent suppression performance. This algorithm actively enhances the electrical damping of the transmission system by extracting and processing the differential signal of the motor speed, thereby effectively counteracting the torsional vibration energy generated by the elastic transmission chain and weakening periodic fluctuations. Experimental verification shows that this suppression strategy can stably function under different rated speeds and load conditions, achieving a torsional vibration suppression effect of 30% to over 70%, providing a mature technical path for practical engineering applications. Through the application of this platform, researchers can significantly shorten the research and development and debugging cycle of torsional vibration suppression technology while ensuring safety, effectively reducing the high safety risks and debugging costs associated with conducting research on actual machines.

[0024] Additional aspects and advantages of the invention will become apparent in the following description or may be learned by practice of the invention. Attached Figure Description

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the structural layout of a dual-end driven long shaft multi-stage torsional vibration test platform according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the rigid mounting base of the test platform according to an embodiment of the present invention; Figure 3 This is a wiring diagram of a frequency converter system topology according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a dual-channel filtering method for signal processing according to an embodiment of the present invention; Figure 5 This is a block diagram of an algorithm for introducing a torsional vibration frequency excitation source according to an embodiment of the present invention; Figure 6 This is a block diagram of a rotational speed differential negative feedback algorithm for torsional vibration suppression according to an embodiment of the present invention.

[0026] in, Figures 1 to 6 The correspondence between the reference numerals and component names in the attached drawings is as follows: 1. Speed ​​encoder; 2. Rigid mounting base platform; 3. Dual-winding drive motor; 4. Flexible diaphragm coupling; 5. Drive shaft; 6. Rigid coupling; 7. Single-winding load motor; 8. Encoder signal line; 9. Drive inverter; 10. Master-slave inverter communication cable; 11. Inverter output cable; 12. Load inverter. Detailed Implementation

[0027] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0029] The following reference Figures 1 to 6 This invention describes a dual-end driven long shaft multi-stage torsional vibration test platform and a torsional vibration identification and suppression method provided by some embodiments of the present invention.

[0030] Some embodiments of this application provide a dual-end driven long shaft multi-stage torsional vibration test platform.

[0031] Torsional vibration is a common problem in inverter-driven motors operating with loads, easily leading to equipment damage. Existing torsional vibration suppression technologies are mostly theoretical, lacking practical platform verification. To develop an effective suppression strategy, it is necessary to first controllably excite torsional vibration, accurately analyze feedback data, and verify the effectiveness of the suppression algorithm. This invention utilizes a scaled-down physical simulation test platform (simulating an experimental platform and a 120MW electrically excited synchronous motor project), combined with innovative shaft system design, excitation methods, and detection algorithms, to achieve safe, controllable, accurate reproduction, and quantitative verification of the entire torsional vibration research process.

[0032] The dual-end driven long-shaft multi-stage torsional vibration test platform described in this embodiment of the invention strictly follows the principle of dynamic similarity in its scaling design during construction. This ensures that the torsional vibration dynamic characteristics of the test platform are completely similar to those of the 120MW prototype unit (exemplary, but the technical solution disclosed herein can be flexibly applied to units of different capacities). Specifically, the two platforms maintain consistency in key indicators such as torsional vibration response laws, vibration modes, and frequency characteristics, ensuring that test data can be directly mapped to the prototype unit. In one specific embodiment, the platform utilizes multiple simulation software programs to establish a full-shaft calculation model, verifying and iteratively optimizing the platform design results. While considering both geometric and kinematic similarity, the scaling ratio is set to 1 / 18, meaning the key geometric dimensions of the test platform are 1 / 18 of the prototype unit.

[0033] This scaling design system primarily adheres to the following three core similarity principles: Firstly, there is the frequency similarity criterion, which requires ensuring that the torsional vibration natural frequencies of the test platform and the prototype unit are in a fixed ratio, and that the proportional relationship of each natural frequency is consistent, to avoid distortion of torsional vibration characteristics due to frequency mismatch. In practice, this should be ensured... and : approximate, and : Approximate, where , These are the first and second order torsional vibration natural frequencies of the test platform. The rated frequency of the test platform; , These are the first and second order torsional vibration natural frequencies of the prototype. This is the rated frequency of the prototype.

[0034] Secondly, there is the stiffness similarity criterion, which requires ensuring that the torsional stiffness ratio and scaling ratio of the two components are matched to maintain the similarity of stiffness response during torsional vibration and ensure consistent vibration transmission patterns. In practice, this means ensuring that the rotor elastic modulus and shear modulus of the test platform and the prototype are essentially the same, thus satisfying the stiffness ratio requirement. ,in, To improve the torsional stiffness of the test platform, denoted as the torsional stiffness of the prototype, and k as the stiffness ratio.

[0035] Finally, there is the inertia similarity criterion, which, based on the dynamic characteristics of rotating components, controls the ratio of the rotational inertia of the test platform and the prototype unit to conform to scaling logic, ensuring that the influence of inertial forces during torsional vibration is consistent with that of the prototype. In practice, this should be ensured... and : Approximately, and requires that the two drive motors of the test platform have the same moment of inertia, where, , The moment of inertia of the drive motor and load motor of the test platform; , The moment of inertia of the drive motor and load compressor of the prototype machine.

[0036] Reference Figure 1 As shown, in terms of the specific physical architecture, the test platform includes core component configuration, signal processing module, and supporting connection structure. The core components include two multi-winding drive motors. In this disclosure, a dual-winding drive motor 3 is used as an example. Specifically, the dual-winding drive motor 3 is used to simulate two electrically excited dual-winding synchronous motors that are driven at both ends of the shaft system. The spatial position and physical parameters of the two sets of three-phase windings of each motor are consistent, and all 12 terminals are brought out. It can flexibly switch between joint operation or single-winding operation mode. Each of its non-drive ends is equipped with a speed encoder 1 for speed detection and torsional vibration identification.

[0037] A single-winding load motor 7 is installed in the middle of the shaft system to simulate the load of a compressor or fan. Its load characteristics can be simulated by the following formula:

[0038] Where Torque is the load torque. Here, b is the torque coefficient, and b is the fixed base torque. This represents the real-time rotor speed of the load motor.

[0039] Two dual-winding drive motors 3 are respectively connected to both sides of a single-winding load motor 7 via a shaft connection structure, forming a dual-end driven long shaft series structure. In one specific embodiment, the shaft connection structure includes a combination logic of a drive shaft 5, an elastic diaphragm coupling 4, and a rigid coupling 6, wherein the rigid structure facilitates alignment, and the elastic diaphragm is used to absorb eccentricity and vibration. In some embodiments, the shaft connection method supports three mode switching: Mode 1 is a coupling-extended shaft connection, for example, the drive shaft 5 is configured with a length of 1m, a shaft diameter of 55mm, and a length-to-diameter ratio L / D≥10:1, used to simulate typical long shaft working conditions; Mode 2 is a direct coupling connection, used to simulate short shaft working conditions; Mode 3 is a no-load direct connection working condition where the two dual-winding drive motors are directly connected by a coupling.

[0040] like Figure 2 As shown, to ensure installation accuracy, the platform is also equipped with a rigid mounting base platform 2, whose base holes are equidistant from the motor base holes. Figure 2 The spacing between adjacent base holes is indicated by double-headed arrows to ensure installation accuracy when switching between different connection methods.

[0041] Reference Figure 1 and Figure 3 As shown, in terms of electrical and inverter component configuration, the test platform described in this embodiment includes four high-voltage drive inverters 9 (shown as inverters 1# to 4# in the figure) and one low-voltage four-quadrant load inverter 12. Inverters 1# and 2# are connected to a dual-winding drive motor via inverter output cables 11. Figure 1 The drive motor shown is #1), and the drive inverters #3 and #4 are connected to another dual-winding drive motor. Figure 1 (See shown is drive motor #2). The four high-voltage drive frequency converters 9 employ a two-level master-slave control logic: frequency converter #1 acts as the master for drive motor #1, and frequency converter #3 acts as the master for drive motor #2. Both master converters independently acquire speed signals as feedback references, undertaking the core functions of speed regulation, torque command generation, and issuance. Frequency converters #2 and #4 act as slaves of frequency converters #1 and #3 respectively, receiving only torque synchronization, current distribution, and torsional vibration suppression commands. They do not independently acquire speed signals to ensure coordinated operation between the motor's two windings and avoid operational deviations. The master and slave frequency converters exchange data in real time via communication cable 10, with communication latency controlled within 1ms. The speed encoder 1 is connected to the drive frequency converter via encoder signal line 8 to obtain test data.

[0042] Specifically, the master and slave frequency converters achieve real-time data interaction through fiber optic communication (communication delay ≤1ms). The master frequency converter acts as the host of the entire system, and the slave frequency converter acts as the slave. Start-stop and speed setting are both achieved by the master frequency converter. Power balance and speed synchronization are achieved by inputting the torque setting difference between the two motors at the input terminal of the speed regulator of the slave system.

[0043] In some embodiments, all four drive inverters 9 employ a cascaded control method with speed and torque loops. The outer loop (speed loop) is set only by the main inverter, taking the deviation between the actual speed and the set speed as input. It generates a torque command including a torsional vibration suppression correction signal through PID control, ensuring stable motor speed and suppressing torsional vibration caused by speed fluctuations. The inner loop (torque loop) is set jointly by all inverters, taking the torque command (including the torsional vibration suppression signal) issued by the main inverter as input. It is used to adjust the amplitude and phase of the output current, ensuring that the actual output torque accurately tracks the command torque issued by the main inverter, and improving drive stability by introducing a current feedback closed loop.

[0044] To ensure uniform stress on the windings, the system adopts a current distribution strategy of "equal distribution + dynamic correction," with the specific rules as follows: Under steady-state operating conditions (no torsional vibration, stable load), the output current of the main frequency converter (1#, 3#) and the corresponding slave frequency converter (2#, 4#) is evenly distributed, that is, the output current of frequency converter 1# is the same as that of frequency converter 2#, and the output current of frequency converter 3# is the same as that of frequency converter 4#, ensuring that the load of the two sets of windings of the motor is balanced.

[0045] The output current signals of the four frequency converters are collected in real time. The current balancing algorithm built into the main frequency converter is used to calculate the deviation between the current of each winding and the reference current (the theoretical current when evenly distributed). When the deviation exceeds ±3%, the main frequency converter automatically sends a current adjustment command to the slave frequency converter to correct the output current of the slave frequency converter and bring the current deviation between windings back to the allowable range.

[0046] When torsional vibration occurs in the shaft system, the current distribution ratio is dynamically adjusted (with a deviation of no more than ±5%) based on the amplitude of the torsional vibration suppression signal, prioritizing the torsional vibration suppression effect; after the torsional vibration is eliminated, it automatically returns to the 1:1 equal distribution mode, taking into account both torsional vibration suppression and winding current balance.

[0047] To ensure effective torsional vibration suppression and dual-end drive stability, this embodiment adopts a synchronous application mode of "main inverter leading and slave inverter synchronously following," with the specific rules as follows: Signal generation and transmission: The torsional vibration suppression signal is generated synchronously by the two main frequency converters (1# and 3#) (based on the speed fluctuation signals collected by each of them, and calculated by combining the speed differential negative feedback algorithm provided later), ensuring that the suppression signals of the two main frequency converters have the same phase and amplitude; after generation, the main frequency converter simultaneously transmits the suppression signal to itself and the corresponding slave frequency converter (2# and 4#), realizing the synchronous response of the four frequency converters.

[0048] Synchronous application requirements: The timing, amplitude, and duration of the suppression signal application must be completely synchronized (synchronization error ≤ 1ms) to avoid imbalance of torque at both ends and fluctuation of winding current due to some frequency converters applying the signal first and others applying it later, which would aggravate shaft torsional vibration.

[0049] Differentiated adaptation adjustment: When there is a slight deviation in the speed fluctuation at both ends (such as the opposite phase of the speed at both ends during first-order torsional vibration), the main frequency converter can fine-tune the amplitude of the suppression signal of the corresponding frequency converter according to the phase difference of the speed fluctuation (fine-tuning range ±10%), further improving the torsional vibration suppression effect; during the fine-tuning process, the signal synchronization of the four frequency converters is always maintained, without destroying the coordination of the dual-end drive.

[0050] Combination Figure 3The inverter system topology diagram shown illustrates the electrical drive and control hardware architecture of this invention in detail. In one specific embodiment, a 6kV three-phase AC voltage is connected to the system input. After being stepped down and phase-shifted by the same phase-shifting transformer, it supplies power to multiple inverter power units in the subsequent stage. The system is equipped with four high-voltage drive inverters 9, corresponding to four inverter main control boards: inverter main control board #1, inverter main control board #2, inverter main control board #3, and inverter main control board #4. Each inverter main control board is communicatively connected to three power units. For example, inverter main control board #1 is connected to power units A1, B1, and C1. Each power unit's output is equipped with a current transformer (CT) to monitor the output current of each phase winding in real time and transmit the current feedback signal to the corresponding inverter main control board. In terms of the physical connection of the motors, the two sets of three-phase windings of motor #1 (i.e., drive motor #1) are connected to the power unit output terminals of inverters #1 and #2, respectively. Similarly, the two sets of three-phase windings of motor #2 (drive motor #2) are connected to the power unit output terminals of inverters #3 and #4, thus achieving multi-winding joint drive. In the hardware data link of the control logic, start / stop / reset commands and speed setpoint signals are uniformly input to the main control board of inverter #1, which serves as the system's main unit. The main control board of inverter #1 interacts with the slave main control board of inverter #2 on the same side and the master main control board of inverter #3 on the opposite side via master-slave inverter communication cable 10. The main control board of inverter #3 is then connected to the slave main control board of inverter #4 on the same side via the same master-slave inverter communication cable. This communication topology not only establishes the No. 1 frequency converter as the overall host for overall scheduling, but also ensures the real-time issuance and precise tracking of master-slave collaborative control commands from the hardware level, thus ensuring the power balance and speed synchronization of the dual-end drive system.

[0051] In one specific embodiment, the four drive inverters 9 are of the same model and are powered by the same phase-shifting transformer. Each inverter's main control board is connected to three power units (rated current 70A) via optical fiber.

[0052] This invention also includes a dedicated signal processing module to improve the accuracy of torsional vibration detection. Specifically, the signal processing module is communicatively connected to the speed encoder and the inverter drive assembly, used to process the speed feedback signal to identify torsional vibration characteristic signals, and to feed back the torsional vibration suppression signal to the two main inverters. In some embodiments, the signal processing module includes a speed waveform amplification and output unit, which multiplies the difference between the per-unit speed measured by the encoder and the reference command by 10, adds a 50% DC bias, and outputs it via a DA (digital-to-analog converter), so that a peak-to-peak value of 100mV on the oscilloscope corresponds to a 0.3% speed fluctuation, facilitating intuitive observation. Furthermore, the signal processing module also includes a dual-channel filtering unit, referencing... Figure 4As shown, the encoder speed signal ω is filtered by bandpass filters whose center frequencies correspond to the system's first-order torsional vibration frequency point f1 and second-order torsional vibration frequency point f2, respectively. Figure 4 The Bandpass (f1) and Bandpass (f2) illustrated in the diagram can be understood as follows: a bandpass is a specific frequency range passband achieved through filtering or electronic signals. The filtered signal is then tunable by 20 times before being output to the DA test points (DA1 and DA2) on the main control board. This highlights the characteristics of the torsional vibration waveform, enabling accurate detection and high-definition visualization analysis of the torsional vibration signal. This multi-stage processing effectively reduces environmental interference and provides high-quality signal support for the subsequent quantitative verification of torsional vibration identification and suppression strategies.

[0053] The signal processing module filters out the torsional vibration frequency signal from the rotation speed signal, outputting a clear torsional vibration waveform. This improves signal readability and analysis accuracy, facilitating waveform viewing and comparison on the oscilloscope. The calculated peak-to-peak value of 100mV on the oscilloscope corresponds to a rotation speed fluctuation of 0.3%, and the torsional vibration intensity is determined by the amplitude of this fluctuation.

[0054] Based on the dual-end drive long shaft system multi-stage torsional vibration test platform described in any of the above embodiments, other embodiments of the present invention provide a torsional vibration identification and suppression method, aiming to reproduce the multi-condition torsional vibration phenomenon of a long shaft system variable frequency drive system under safe and controllable conditions, and to quantitatively verify the suppression strategy. This method specifically includes the following steps S1 to S4.

[0055] S1. The load motor is controlled by the load inverter to apply load disturbance to the long shaft system structure in order to excite torsional vibration of the system; S2. The two speed encoders are used to collect the speed feedback signals at both ends of the long shaft structure in real time, and the critical speed and torsional vibration order are identified by the signal processing module. S3. Using a speed differential negative feedback algorithm, the two main frequency converters extract the high-frequency fluctuation components in the speed feedback signal and perform differential processing to generate a torsional vibration suppression signal. S4. The torsional vibration suppression signal is synchronously applied to the torque command channel of each of the drive frequency converters. By correcting the electrical damping of the motor output torque enhancement system, torsional vibration fluctuations are suppressed.

[0056] Specifically, in step S1, the method first provides a controllable excitation source for torsional vibration research through an excitation stage, and the torsional vibration excitation is carried out in a dual-mode manner.

[0057] One method is torque step excitation, which uses a low-voltage four-quadrant frequency converter to drive the load motor, achieving a sudden loading or unloading of a set proportion (e.g., 10%) of load fluctuation. Since the step torque contains rich frequency components, it can naturally excite various orders of torsional vibration in the system, making it suitable for testing torsional vibration frequency points under different driving conditions. Specifically, the load frequency converter is controlled to drive the load motor, achieving a sudden loading / unloading operation of 10% load. The frequency converter drives the motor at 450 rpm (corresponding to a rotor rotation frequency of 7.5 Hz). Speed ​​fluctuation signals are collected by a speed encoder, and after processing by the signal processing module, speed fluctuations around 13 Hz (opposite phase, matching amplitude) are observed and identified as first-order torsional vibration; speed fluctuations around 21 Hz (same phase, matching amplitude) are observed and identified as second-order torsional vibration.

[0058] The second is the superposition of frequency excitation sources. In some embodiments, refer to... Figure 5 As shown, a quadrature-axis current disturbance component ΔIq is superimposed on the quadrature-axis current given signal Iq* as the input to the torque regulator ATL. During operation, this can be changed to achieve a step change in load torque, or a function for the change in load torque can be set to obtain specific load characteristics, thus forming a load disturbance excitation. This example uses a sinusoidal excitation source, meaning the disturbance component satisfies the formula:

[0059] in, The disturbance amplitude coefficient, f, and Δt are all parameters that can be set through a customized menu. This allows for the superposition of torque pulsations with different frequencies and amplitudes. When the frequency matches the first-order or second-order torsional vibration frequency, it can excite the first-order and second-order torsional vibrations of the system. When the superposition frequency approaches the critical speed of the shaft system, the speed fluctuation amplitude will increase significantly, thus providing a precise target excitation for the verification of the suppression strategy.

[0060] When the load torque is selected based on the square torque load characteristic of the fan, its function is as described above:

[0061] Where Torque is the load torque. Here, b is the torque coefficient, and b is the fixed base torque. This represents the real-time rotor speed of the load motor.

[0062] In one specific embodiment, the present invention Figure 5 This is a block diagram of the algorithm for introducing the torsional vibration frequency excitation source, which details the fusion logic between the inverter's internal control loop and the torsional vibration excitation signal. The block diagram mainly consists of a flux linkage control link, a torque control link, and a coordinate transformation output stage.

[0063] In the flux linkage control loop, the symbol Ψ* represents the flux linkage setpoint signal, while Ψ represents the actual flux linkage feedback signal of the motor. These two are compared through a summation point, and the resulting deviation value is input to the flux linkage regulator (AFR) for calculation. The output of the AFR is Id*, which represents the direct-axis current setpoint value, used to control the motor's excitation state. Subsequently, Id* enters the flux linkage regulation loop AML, ultimately generating the direct-axis voltage setpoint signal Vd*.

[0064] In the torque control loop, Iq* represents the basic quadrature-axis current setpoint, typically generated by the speed loop output. To achieve controlled excitation of torsional vibration, the system adds a disturbance component to Iq* through a summation point. The superimposed total quadrature-axis current command is input to the torque regulator ATL, which then calculates the quadrature-axis voltage command signal Vq*.

[0065] In the coordinate transformation and output stage, the generated Vd* and Vq* signals are combined with the rotor position angle θ and input to the coordinate transformation module. The 2 / 3Transform shown in the block diagram represents a combination of the inverse Park and inverse Clarke transformations. Its function is to convert the DC component voltage signal in the rotating coordinate system into AC voltage command values ​​in the stationary three-phase coordinate system, i.e., the outputs are VA*, VB*, and VC*. These three-phase voltage commands ultimately act on the motor M, causing the motor output torque to contain specific frequency pulsating components, thereby exciting the expected torsional vibration phenomenon in the long shaft structure.

[0066] After torsional vibration is induced, step S2 involves using a speed encoder to collect speed fluctuation signals in real time, and combining this with a signal processing module to identify the critical speed and torsional vibration order. In some embodiments, the identification logic is based on the phase and amplitude characteristics of the encoder signals at both ends. If the speed fluctuations of the encoders at both ends have opposite phases and matching amplitudes, the system is determined to have first-order torsional vibration, corresponding to a frequency of approximately 13Hz. If the speed fluctuations of the encoders at both ends have the same phase and matching amplitudes, the system is determined to have second-order torsional vibration, corresponding to a frequency of approximately 21Hz. In a specific embodiment, the accuracy of the identified critical speed can be further verified by superimposing torque pulsation signals of specific frequencies (such as 11Hz, 13Hz, 17Hz, 21Hz, etc.) and observing the changes in the speed fluctuation amplitude.

[0067] To address the identified torsional vibration phenomenon, this embodiment employs the suppression algorithm based on speed differential negative feedback in step S3. By extracting the differential signal of the motor speed and performing negative feedback compensation, the electrical damping of the transmission system is actively enhanced to counteract the torsional vibration energy of the elastic transmission chain, thereby reducing the periodic fluctuations in speed and torque. (Refer to...) Figure 6 As shown, the inhibition process specifically includes: The actual motor speed n is acquired in real time and used as the input signal of the differential negative feedback loop. The speed deviation signal is obtained by summing and comparing it with the speed setpoint signal n*, and then input to the speed regulator ASR to output the torque setpoint signal Tm*.

[0068] In some embodiments, the actual rotational speed n is processed by a first-order low-pass filter to obtain a slowly varying approximate DC component, thereby filtering out high-frequency fluctuations and torsional vibration components.

[0069] The high-frequency fluctuation component (i.e. torsional vibration component or noise) in the rotational speed is extracted by subtracting the average rotational speed after low-pass filtering from the actual rotational speed n.

[0070] The difference is differentiated by first order to obtain an approximate rate of change of acceleration or torsional vibration, which serves as a negative feedback signal to suppress high-frequency noise and generate a smooth signal. In one specific embodiment, Figure 6 The transfer function of the differential element described in the dashed box can be expressed as:

[0071] in, Represents the transfer function. This represents the proportionality coefficient. represents the filtering time constant, and s represents the input signal.

[0072] Through the proportionality coefficient Adjust the amplitude of the differential signal to match the damping requirements of the transmission system, and then adjust the negative feedback signal. It is superimposed on the torque command channel of the control system to correct the original torque command.

[0073] The corrected torque command is converted into the actual output torque of the motor through the current loop ATL and the frequency converter HVVF. The resonant component of torsional vibration is offset by phase compensation, the electrical damping of the system is improved, and torsional vibration fluctuation is finally suppressed.

[0074] In some embodiments, the algorithm parameter scaling factor and filter time constant The tuning needs to balance suppression effect, system stability, and noise immunity. The tuning steps include: first, fixing... (If selected as 0.2 or 0.01), Gradually increase the value from 0 until the torsional vibration amplitude is reduced to its minimum and the system exhibits no overshoot oscillation. For the strong resonance characteristics of long-shaft structures, it is typically necessary to increase the value. (e.g., 15-30) to enhance damping to counteract strong resonance.

[0075] In one specific embodiment, the effectiveness of the suppression method was verified through experiments.

[0076] (1) Verification of first-order torsional vibration suppression: Step 1: Start the test platform and run the motors at 20% of their rated speed using 4 drive frequency converters; Step 2: Add a torque fluctuation with an amplitude of 2% and a frequency of 13Hz to the torque command of inverter #1, and detect the speed fluctuation through the speed encoders of the two drive motors, recording the peak-to-peak value as 0.23%; Step 3: Implement the speed differential negative feedback suppression algorithm and set the filter time constant. =0.01, adjust the scaling factor =20; Step 4: The rotational speed fluctuation was checked again. The peak-to-peak value dropped to 0.12%, and the torsional vibration suppression effect was about 47%.

[0077] (2) Verification of second-order torsional vibration suppression: Step 1: Add a torque fluctuation with an amplitude of 0.5% and a frequency of 21Hz to the torque output of the load motor, and detect the peak-to-peak speed fluctuation as 0.3%; Step 2: Keep =0.01, adjust =30, implement the suppression algorithm; Step 3: The peak-to-peak value of the speed fluctuation was reduced to 0.1%, and the torsional vibration suppression effect was about 66%.

[0078] (3) Verification of the suppression effect at different rotation speeds: The above steps were repeated at 30%, 50%, 80%, and 100% of the rated speed, respectively. The measured torsional vibration suppression effect was higher than 30%, with a maximum of 70%. At 100% of the rated speed, the suppression algorithm remained effective when a sudden load and sudden unload of 10% to 40% were applied to the load motor.

[0079] (4) Verification of single-winding drive condition: Drive motor #1 with a single winding and drive motor #2 with an open circuit. Repeat the first-order and second-order torsional vibration suppression tests. =30, the measured speed fluctuation was effectively suppressed, verifying the applicability of the suppression algorithm under single winding drive conditions.

[0080] In this specification, the illustrative expressions of the terms used do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0081] Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention shall be included within the scope of protection of this invention.

Claims

1. A dual-end driven long shaft system multi-stage torsional vibration test platform, characterized in that, include: A multi-winding drive motor, with two multi-winding drive motors respectively set at both ends of the shaft system to be tested, and a speed encoder is provided on the non-drive end of each multi-winding drive motor; A load motor is disposed between the two multi-winding drive motors, wherein the two multi-winding drive motors are respectively connected to both sides of the load motor through a shaft connection structure to form a long shaft structure with double-end drive. A frequency converter drive assembly includes multiple drive frequency converters and at least one load frequency converter. The multiple drive frequency converters are respectively connected to each set of windings of the two multi-winding drive motors, and the load frequency converter is connected to the load motor. Multiple drive inverters are configured in a master-slave cooperative control topology, wherein: The two drive frequency converters, which are respectively connected to the first set of windings of the two multi-winding drive motors, are configured as main frequency converters to independently acquire the speed feedback signal of the speed encoder on the corresponding side and generate torque command based on the speed feedback signal. Other drive inverters connected to the remaining windings of the two multi-winding drive motors are configured as slave inverters. Each slave inverter is communicatively connected to the corresponding master inverter and is used to receive synchronization commands issued by the master inverter and follow the operation. The signal processing module is communicatively connected to the speed encoder and the inverter drive assembly. It is used to process the speed feedback signal to identify torsional vibration characteristic signals and to feed back the torsional vibration suppression signal to the two main inverters.

2. The dual-end driven long shaft multi-stage torsional vibration test platform according to claim 1, characterized in that, The shaft connection structure includes the following three switchable connection methods: coupling extended shaft connection, direct coupling connection, or direct coupling connection of the two multi-winding drive motors; wherein, the coupling adopts a combination structure of rigid coupling and elastic diaphragm coupling.

3. The dual-end driven long shaft multi-stage torsional vibration test platform according to claim 1, characterized in that, It also includes a rigid mounting base, which has mounting holes that are equidistant from the base holes of the two multi-winding drive motors and the load motor, for alignment installation to accommodate different shaft connection methods.

4. The dual-end driven long shaft multi-stage torsional vibration test platform according to claim 1, characterized in that, The current distribution strategy executed by the multiple drive inverters is configured as follows: Under steady-state operation, the output current of the two main frequency converters and the corresponding two slave frequency converters is equally distributed; when the winding current deviation is detected to exceed the set threshold, the main frequency converter issues a current adjustment command to correct the output current of the slave frequency converter.

5. The dual-end driven long shaft multi-stage torsional vibration test platform according to claim 1, characterized in that, The signal processing module includes: The speed waveform amplification output unit is used to proportionally amplify the difference between the per-unit speed measured by the speed encoder and the reference command, and then output it after superimposing a DC bias. The dual-channel filtering unit is used to filter and amplify the speed feedback signal through bandpass filters whose center frequency corresponds to different torsional vibration frequency points, so as to highlight the characteristics of the torsional vibration waveform.

6. A method for identifying and suppressing torsional vibration, characterized in that, Based on the dual-end driven long shaft system multi-stage torsional vibration test platform as described in any one of claims 1 to 5, the method includes the following steps: The load motor is controlled by the load inverter to apply load disturbance to the long shaft system structure, thereby stimulating torsional vibration of the system. The two speed encoders are used to collect the rotational speed feedback signals at both ends of the long shaft system in real time, and the critical speed and torsional vibration order are identified by the signal processing module. The speed differential negative feedback algorithm is adopted, in which the two main frequency converters extract the high-frequency fluctuation component in the speed feedback signal and perform differential processing to generate a torsional vibration suppression signal; The torsional vibration suppression signal is synchronously applied to the torque command channel of each of the drive frequency converters, thereby suppressing torsional vibration fluctuations by correcting the electrical damping of the motor output torque enhancement system.

7. The torsional vibration identification and suppression method according to claim 6, characterized in that, The excitation system torsional vibration includes at least one of the following methods: Torque step excitation: The load motor is used to achieve a sudden loading or sudden unloading of a set proportion of load fluctuation; Frequency excitation source superposition: A sinusoidal torque pulsation signal with a set frequency and amplitude is superimposed on the torque command of the load inverter or multiple drive inverters.

8. The torsional vibration identification and suppression method according to claim 6, characterized in that, The features for identifying critical speed and torsional vibration order include: If the speed fluctuations of the two speed encoders are out of phase and their amplitudes match, then it is determined to be a first-order torsional vibration. If the speed fluctuations of the two speed encoders are in the same phase and have the same amplitude, then it is determined to be a second-order torsional vibration.

9. The torsional vibration identification and suppression method according to claim 6, characterized in that, The generation process of the torsional vibration suppression signal includes: The average speed is obtained by processing the speed feedback signal through a first-order low-pass filter. The high-frequency fluctuation component is obtained by subtracting the average rotational speed from the rotational speed feedback signal. The high-frequency fluctuation component is differentiated and its gain is adjusted to generate the torsional vibration suppression signal.

10. The torsional vibration identification and suppression method according to claim 9, characterized in that, The rotational speed differential negative feedback algorithm is tuned by adjusting the filter time constant and the proportional coefficient. The filter time constant is selected to achieve frequency domain separation between the torsional vibration signal and the measurement noise, and the proportional coefficient is increased to enhance the damping strength for long shaft structures.

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