Deceleration control method for high-speed motor-driven hydraulic system

Abstract

The invention relates to the technical field of logistics warehouse storage equipment, in particular to a speed reduction control method for a high-speed motor driven hydraulic system, which comprises the following steps: S1, the output torque of a high-speed motor is transmitted to a gear pump through a motor shaft, a planetary reducer and a planet carrier in sequence to drive the gear pump to work; s2, acquiring a three-phase current instantaneous signal and a direct current bus voltage signal, and performing preprocessing and frequency spectrum conversion to determine a current frequency spectrum; s3, in the current frequency spectrum, extracting an energy value in a preset frequency band with the meshing frequency and harmonic waves of the planetary gear as the center, and calculating to obtain a disturbance characterization value of the planetary gear; s4, determining a torque smooth adjustment coefficient according to the planet wheel disturbance characterization value; and S5, dynamically adjusting a dynamic response parameter of a torque control ring of the high-speed motor according to the torque smooth adjustment coefficient. The problems that in the prior art, a high-rotating-speed motor and a hydraulic pump are not matched in rotating speed, and mechanical disturbance is difficult to restrain are solved.

Description

Technical Field

[0001] This invention relates to the field of logistics warehouse storage equipment technology, and in particular to a deceleration control method for a high-speed motor-driven hydraulic system. Background Technology

[0002] Currently, hydraulic systems are widely used in logistics and warehousing equipment such as stacker trucks and handling vehicles to lift and lower goods. Existing hydraulic power assemblies typically consist of three independent components: a DC motor, a valve block, and a hydraulic pump. These three components are positioned by a stop and fastened with bolts. The motor's output shaft is directly inserted into the hydraulic pump's input shaft, forming a rigid direct-drive transmission. In this structure, the motor's output speed is the same as the hydraulic pump's input speed. Due to limitations imposed by mechanical structure and lubrication conditions, commonly used hydraulic pumps such as gear pumps typically have rated speeds below 5000 r / min. Therefore, the motor must be designed with a lower speed specification to match the pump. This speed limitation makes it difficult to further reduce the motor's size, resulting in a larger material usage and higher motor manufacturing costs. Simultaneously, the entire hydraulic power assembly occupies a significant amount of installation space, hindering the compact layout of the entire vehicle.

[0003] With increasing demands for energy efficiency, endurance, and space utilization in logistics equipment, reducing the cost and size of hydraulic power assemblies has become a pressing issue in the industry. Increasing the motor's operating speed is an effective way to reduce its size, but a speed mismatch exists between high-speed motors and low-speed hydraulic pumps. Direct coupling will lead to pump overspeed operation, causing cavitation, accelerated wear, and even damage. Introducing a reduction gear mechanism between the motor and pump can achieve a match between the high-speed motor drive and the low-speed pump operation, thus balancing motor miniaturization and pump reliable operation. However, existing reduction gear mechanisms are mostly independent modules with low integration and lack active control methods for electromechanical coupling vibrations, making it difficult to ensure the long-term stability of the system.

[0004] Chinese Patent Publication No. CN110345200A discloses a tubular motor reducer, including a cylindrical shell, a front cover, a rear cover, an input shaft, an output shaft, and a gear pump. The cylindrical shell is horizontally arranged, and multiple planetary reduction gear mechanisms are installed inside the cylindrical shell. The gear pump corresponds one-to-one with each planetary reduction gear mechanism and is installed beside the planetary reduction gear mechanism and is connected to the planetary reduction gear mechanism for transmission. An oil return pipe is provided at the bottom of the cylindrical shell, connecting the front end inside the cylindrical shell and the rear end inside the cylindrical shell. It can be seen that the tubular motor reducer has the following problems: the tubular motor reducer only solves the lubrication problem, but cannot monitor the wear state of the planetary gears, and cannot actively suppress the electromechanical coupling vibration caused by wear, making it difficult to ensure the long-term stability of the hydraulic system. Summary of the Invention

[0005] Therefore, the present invention provides a deceleration control method for a high-speed motor driven hydraulic system to overcome the problems of mismatch between the speed of the high-speed motor and the hydraulic pump and the difficulty in suppressing mechanical disturbances in the prior art.

[0006] To achieve the above objectives, the present invention provides a deceleration control method for a high-speed motor-driven hydraulic system, comprising: In step S1, the output torque of the high-speed motor is transmitted sequentially through the motor shaft, planetary reducer and planetary carrier to the gear pump, driving the gear pump to work; Step S2: Obtain the instantaneous three-phase current signal and DC bus voltage signal of the high-speed motor, preprocess and perform spectrum conversion on the instantaneous three-phase current signal to determine the current spectrum; Step S3: Extract the energy value within a preset frequency band centered on the planetary gear meshing frequency and its harmonics from the current spectrum, and calculate the planetary gear disturbance characterization value. Step S4: Compare the planetary gear disturbance characterization value with a preset quiet threshold. When the planetary gear disturbance characterization value is greater than the quiet threshold, determine the torque smoothing adjustment coefficient based on the planetary gear disturbance characterization value. Step S5: Dynamically adjust the dynamic response parameters of the torque control loop of the high-speed motor according to the torque smoothing adjustment coefficient, so that the adjusted dynamic response parameters are less than the original dynamic response parameters.

[0007] Further, step S2 includes: Step S21: Bandpass filter is applied to the instantaneous three-phase current signal to retain a preset frequency band related to the meshing frequency of the planetary gears; Step S22: The amplitude of the filtered three-phase instantaneous current signal is corrected according to the DC bus voltage signal to obtain the preprocessed current signal. Step S23: Perform a Fourier transform on the preprocessed current signal to convert the time-domain signal into a frequency-domain signal, thereby obtaining the current spectrum.

[0008] Furthermore, step S2 also includes: Step S24: Obtain the winding temperature signal of the high-speed motor and the oil temperature signal of the gear pump; Step S25: Dynamically compensate the preprocessed current signal based on the winding temperature signal and the oil temperature signal.

[0009] Further, step S3 includes: Step S31: Calculate the root mean square of the amplitude of all spectral components within the preset frequency band, and use the calculation result as the perturbation characterization value of the planetary gear. Step S32: Calculate the energy value within the gear pump meshing frequency band as a pump disturbance reference feature, and extract the fundamental current component from the current spectrum; Step S33: Determine whether the planetary gear train disturbance is the main reason for the increase in the planetary gear disturbance characterization value based on the pump disturbance reference characteristics and the fundamental current component.

[0010] Furthermore, in step S33, when the planetary gear disturbance characterization value is greater than the historical average value and the change amplitude of the pump disturbance reference characteristic is less than the first preset threshold and the change amplitude of the current fundamental component is less than the second preset threshold, it is determined to be a planetary gear system disturbance.

[0011] Furthermore, in step S4, the torque smoothing adjustment coefficient is determined by a preset nonlinear mapping function based on the proportion of the planetary gear disturbance characterization value that is greater than the quiet threshold. The value range of the torque smoothing adjustment coefficient is greater than or equal to 0 and less than or equal to 1.

[0012] Furthermore, in step S5, the dynamic response parameter includes the proportional gain of the torque current loop.

[0013] Furthermore, in step S5, the dynamic response parameters include the adjustment rate of the PWM duty cycle or the torque compensation coefficient during the commutation process.

[0014] Furthermore, it also includes: Step S6: Repeat steps S2 to S5 until the planetary gear disturbance characterization value is less than or equal to the quiet threshold.

[0015] Furthermore, the high-speed motor is a brushless DC motor.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: by using the output shaft of the high-speed motor as the sun gear of the planetary reducer, the present invention constructs an integrated electromechanical transmission structure, and collects the motor current signal in real time for spectrum analysis, extracts the energy value near the meshing frequency of the planetary gears to quantify the mechanical disturbance, and then dynamically adjusts the response parameters of the motor torque control loop based on the disturbance value, the present invention effectively solves the problem of speed mismatch between the high-speed motor and the hydraulic pump, and actively suppresses the electromechanical coupling vibration caused by the wear of the planetary gear system, significantly improving the stability and reliability of the hydraulic drive system in long-term operation.

[0017] Furthermore, by directly using the motor shaft as the sun gear of the planetary reducer and integrating the planetary reducer between the motor and the valve block, the present invention achieves an integrated and compact design of the motor and the reduction mechanism, reducing axial installation dimensions and connecting parts, which is beneficial to the overall spatial layout of logistics and warehousing equipment.

[0018] Furthermore, by acquiring the three-phase current signal of the motor and performing spectrum conversion, the present invention extracts the energy value near the meshing frequency of the planetary gears as the disturbance characterization value of the planetary gears, thereby realizing the indirect monitoring of the mechanical state of the planetary gear system using the motor's own electrical signals, without the need for additional vibration sensors, thus reducing system costs.

[0019] Furthermore, by introducing winding temperature and oil temperature signals to dynamically compensate for the current signal, this invention eliminates the interference of temperature changes on the current amplitude, enabling the extracted planetary gear disturbance characterization values ​​to more accurately reflect the real mechanical disturbances caused by planetary gear wear, thereby improving the accuracy of condition monitoring.

[0020] Furthermore, this invention compares the planetary gear disturbance characterization value with a preset quiet threshold, and dynamically determines the torque smoothing adjustment coefficient based on the excess ratio when the threshold is exceeded, thereby achieving adaptive control of the adjustment intensity. This ensures that the intensity of the control action matches the severity of the mechanical disturbance, avoiding the adverse effects of over-adjustment on the dynamic performance of the system.

[0021] Furthermore, by dynamically adjusting the proportional gain of the torque current loop or the adjustment rate of the PWM duty cycle according to the torque smoothing adjustment coefficient, the present invention makes the electromagnetic torque output of the motor smooth, reduces the tracking ability of high-frequency torque fluctuations on the mechanical side, thereby actively suppressing electromechanical coupling vibration and extending the service life of transmission components.

[0022] Furthermore, by introducing pump disturbance reference features and current fundamental component as auxiliary criteria, and combining them with the historical average value of planetary gear disturbance characterization values ​​for comprehensive judgment, this invention can accurately identify whether the disturbance source comes from inside the planetary gear system, eliminate misjudgments caused by load changes or pump malfunctions, and improve the reliability of the control logic.

[0023] Furthermore, by repeatedly executing the steps of signal acquisition, feature extraction, and parameter adjustment, the present invention forms a closed-loop control until the planetary gear disturbance characterization value falls back to within the quiet threshold, thereby achieving continuous suppression of planetary gear system disturbances and ensuring that the system can maintain stable operation under various operating conditions. Attached Figure Description

[0024] Figure 1 This is a flowchart of the deceleration control method for a high-speed motor-driven hydraulic system according to the present invention; Figure 2 This is a flowchart of step S2 of the deceleration control method for a high-speed motor-driven hydraulic system according to the present invention; Figure 3 This is a flowchart of step S3 of the deceleration control method for a high-speed motor-driven hydraulic system according to the present invention; Figure 4This is a schematic diagram of the deceleration control method for a high-speed motor-driven hydraulic system according to an embodiment of the present invention; In the diagram, 1-high-speed motor; 11-motor shaft; 2-internal gear ring; 3-planetary shaft; 4-planetary gear; 5-planetary carrier; 6-gear shaft; 7-valve block. Detailed Implementation

[0025] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0026] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0027] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0028] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] Please see Figure 1 The diagram shows a flowchart of a deceleration control method for a high-speed motor-driven hydraulic system according to the present invention. The present invention provides a deceleration control method for a high-speed motor-driven hydraulic system, comprising: In step S1, the output torque of the high-speed motor is transmitted sequentially through the motor shaft, planetary reducer and planetary carrier to the gear pump, driving the gear pump to work; Specifically, the high-speed motor is a brushless DC motor.

[0030] Please see Figure 4The diagram illustrates the structure of a deceleration control method for a high-speed motor-driven hydraulic system according to an embodiment of the present invention. In one specific embodiment, the high-speed motor 1 is a brushless DC motor, and its output shaft, i.e., the end of the motor shaft 11, is machined with gear teeth, serving as the sun gear of a planetary reducer. An internal gear ring 2 is installed between the motor base and the valve block 7. A planetary carrier 5 is installed inside the internal gear ring 2, and several planetary shafts 3 and planetary gears 4 are evenly distributed on the planetary carrier 5. The motor shaft 11, internal gear ring 2, planetary gears 3, planetary shafts 4, and planetary carrier 5 together constitute a planetary reducer. The planetary carrier 5 is installed inside the valve block 7, and its output end is fixedly connected to the gear shaft 6 of the gear pump via a key connection. During operation, the high-speed motor 1 outputs torque, which is transmitted to the planetary gears 4 via the motor shaft 11 (sun gear). The planetary gears 4 rotate around their own planetary shafts and revolve around the sun gear, driving the planetary carrier 5 to rotate. The planetary carrier 5 then transmits torque to the gear shaft 6 of the gear pump, thereby driving the gear pump to operate.

[0031] Among them, the high-speed motor is a brushless DC motor with a rated operating speed greater than 10,000 r / min; the planetary reducer has a preset reduction ratio, which is used to convert the high speed and low torque output of the motor shaft into low speed and high torque before outputting it to the gear pump; the gear pump is the actuator of the hydraulic power unit, with an operating speed less than or equal to 5,000 r / min.

[0032] Understandably, in this embodiment, by directly using the motor shaft as the sun gear and integrating the planetary reducer between the motor and the valve block, a compact, integrated design of the motor and reduction mechanism is achieved. This structure eliminates the need for an external, independent reducer, reducing axial installation dimensions and connecting components, which is beneficial for the overall vehicle space layout. Simultaneously, using a high-speed brushless DC motor in conjunction with the planetary reducer leverages the small size of the high-speed motor to reduce material costs, while the reducer lowers the output speed to within the allowable operating range of the gear pump, ensuring reliable pump operation.

[0033] Step S2: Obtain the instantaneous three-phase current signal and DC bus voltage signal of the high-speed motor, preprocess and perform spectrum conversion on the instantaneous three-phase current signal to determine the current spectrum; Please continue reading. Figure 2 As shown, it is a flowchart of step S2 of the deceleration control method for a high-speed motor driven hydraulic system of the present invention; Specifically, step S2 includes: Step S21: Bandpass filter is applied to the instantaneous three-phase current signal to retain a preset frequency band related to the meshing frequency of the planetary gears; Step S22: The amplitude of the filtered three-phase instantaneous current signal is corrected according to the DC bus voltage signal to obtain the preprocessed current signal. Step S23: Perform a Fourier transform on the preprocessed current signal to convert the time-domain signal into a frequency-domain signal, thereby obtaining the current spectrum.

[0034] In one specific embodiment, the instantaneous three-phase current signals and DC bus voltage signals of the high-speed motor are acquired in real time. Current sensors are used to acquire the instantaneous current values ​​of the three-phase windings of the motor, and voltage sensors are used to acquire the DC bus voltage values. The acquired instantaneous three-phase current signals are preprocessed: First, digital bandpass filtering is performed on the instantaneous three-phase current signals to retain a preset frequency band related to the planetary gear meshing frequency and filter out high-frequency noise such as power supply harmonics and switching frequencies; second, amplitude correction is performed on the filtered instantaneous three-phase current signals based on the real-time acquired DC bus voltage signals to eliminate current amplitude changes caused by battery voltage fluctuations, resulting in a preprocessed current signal; finally, a fast Fourier transform is performed on the preprocessed current signal to convert the time-domain signal into a frequency-domain signal, obtaining the current spectrum.

[0035] The passband frequency range of the bandpass filter is determined based on the current motor speed and the structural parameters of the planetary gear reducer, typically centered on the planetary gear meshing frequency and its main harmonics, and also covering a certain sideband. The DC bus voltage correction uses a normalization method, and the specific correction formula is as follows: i cr =i raw ×V ref / V bus ; Where i cr This is the corrected instantaneous current value, dimensionless, with the same unit as the original current; i raw The current is the instantaneous value after filtering, in amperes (A); V ref This is a preset reference voltage, measured in volts (V), typically taken as the rated voltage of the battery; V bus The DC bus voltage is acquired in real time, and the unit is volts (V). The fast Fourier transform uses a fixed time window length, which is set according to the required frequency resolution. Preferably, it is 0.1 seconds. The transformed current spectrum is obtained, and the amplitude of the spectrum is in amperes (A).

[0036] Understandably, the purpose of bandpass filtering is to extract the frequency band related to the mechanical vibration of the planetary gear train from the original current signal and eliminate irrelevant electrical noise interference; the purpose of DC bus voltage correction is to eliminate the influence of power supply voltage fluctuations on the current amplitude, so that the current signal can more realistically reflect the changes in load torque and avoid misjudgment due to voltage changes; fast Fourier transform converts the time-domain current signal to the frequency domain, which facilitates the subsequent extraction of energy characteristics of specific frequency components in the frequency domain.

[0037] It is understandable that the motor current signal contains not only the fundamental component proportional to the load torque, but also modulation components caused by mechanical vibration. When wear or uneven loading occurs on the planetary gears inside the planetary reducer, periodic torque fluctuations are generated. These fluctuations modulate the motor's current waveform, manifesting as sidebands near the planetary gear meshing frequency and its harmonics in the current spectrum. By filtering and voltage correction of the current signal, interference can be removed while retaining this modulation information. Then, through Fourier transform, the modulation information is clearly presented in the frequency domain, laying the foundation for subsequent extraction of planetary gear disturbance characteristics. This process essentially utilizes the motor itself as a sensor, analyzing its electrical signals to sense the mechanical vibration state, achieving sensorless monitoring.

[0038] Specifically, step S2 further includes: Step S24: Obtain the winding temperature signal of the high-speed motor and the oil temperature signal of the gear pump; Step S25: Dynamically compensate the preprocessed current signal based on the winding temperature signal and the oil temperature signal.

[0039] In one specific embodiment, while acquiring the electrical signals of the motor, the winding temperature signal of the high-speed motor and the oil temperature signal of the gear pump are acquired in real time. Temperature sensors, such as thermistors or thermocouples, are installed at the ends of the motor stator windings and inside the gear pump housing, respectively, to measure the winding temperature and oil temperature. Based on the acquired winding temperature and oil temperature signals, the preprocessed current signal is dynamically compensated to eliminate the influence of temperature changes on the current signal amplitude, resulting in a compensated current signal used for subsequent spectrum analysis. The temperature compensation uses a linear correction model, and its calculation formula is as follows: ; Where i cp The instantaneous current value after temperature compensation, in amperes (A); i cr The instantaneous current value is the voltage-corrected value, in amperes (A); α is the winding temperature compensation coefficient, in degrees Celsius (°C). -1 The value range is 0.001℃. -1 ~0.005℃ -1 Preferably, α is 0.002℃. -1 It is calibrated based on the temperature coefficient of resistance of the motor winding material; T m The winding temperature is collected in real time, in degrees Celsius (°C); T m0 β is the preset winding reference temperature, in degrees Celsius (°C), typically taken as the winding temperature under rated motor conditions, such as 80°C; β is the oil temperature compensation coefficient, in degrees Celsius (°C). -1 The value range is 0.0005℃. -1~0.002℃ -1 Preferably, β is 0.001℃. -1 It is calibrated based on the influence of hydraulic oil viscosity-temperature characteristics on load torque; T r The oil temperature is collected in real time and is expressed in degrees Celsius (°C). T r0 The preset oil temperature reference temperature is expressed in degrees Celsius (°C). It is usually taken as the normal operating oil temperature of the hydraulic system, and preferably 50°C.

[0040] Understandably, the winding temperature compensation coefficient α is used to correct the effect of motor winding resistance changes with temperature on the current amplitude. As motor winding resistance increases with temperature, the current will change under the same load. The oil temperature compensation coefficient β is used to correct the effect of hydraulic oil viscosity changes with temperature on the gear pump load torque. As oil temperature increases, viscosity decreases, the pump's rotational resistance decreases, and the motor load current decreases accordingly. By introducing these two temperature compensation terms, the interference of temperature changes on the current signal can be eliminated, allowing the compensated current signal to more accurately reflect the mechanical disturbances caused by planetary gear wear.

[0041] It is understandable that the resistance of motor windings has a positive temperature coefficient; as temperature increases, resistance increases, and current decreases at the same voltage. This change is independent of the load, and without compensation, it may be misinterpreted as a decrease in load or the disappearance of disturbance. Simultaneously, the viscosity of hydraulic oil changes significantly with temperature; as oil temperature rises, viscosity decreases, altering the mechanical losses and leakage characteristics of the gear pump, leading to changes in the motor's load torque. This change is also unrelated to planetary gear wear. By introducing dynamic compensation based on winding temperature and oil temperature, the influence of these temperature-related non-disturbance factors on the current signal can be eliminated. This ensures that the final current signal used for feature extraction only reflects torque fluctuations caused by mechanical wear, thereby improving the accuracy and reliability of subsequent diagnostics. The temperature compensation coefficient is obtained through experimental calibration to ensure that the compensation model matches the actual system characteristics.

[0042] Step S3: Extract the energy value within a preset frequency band centered on the planetary gear meshing frequency and its harmonics from the current spectrum, and calculate the planetary gear disturbance characterization value. Please continue reading. Figure 3 As shown, it is a flowchart of step S3 of the deceleration control method for a high-speed motor driven hydraulic system of the present invention; Specifically, step S3 includes: Step S31: Calculate the root mean square of the amplitude of all spectral components within the preset frequency band, and use the calculation result as the perturbation characterization value of the planetary gear. Step S32: Calculate the energy value within the gear pump meshing frequency band as a pump disturbance reference feature, and extract the fundamental current component from the current spectrum; In a specific embodiment, based on the current spectrum obtained in step S2, the energy value within a preset frequency band centered on the planetary gear meshing frequency and its harmonics is extracted, and the planetary gear disturbance characterization value is calculated. First, the planetary gear meshing frequency is determined, which is calculated based on the current motor speed and the structural parameters of the planetary reducer. The meshing frequency is equal to the motor shaft rotation frequency multiplied by the number of teeth on the sun gear of the planetary reducer. The preset frequency band covers a certain width of sidebands above and below the planetary gear meshing frequency and its second and third harmonics. The bandwidth is preset according to the structural characteristics of the planetary gear system and the actual working conditions, and is usually taken as 5% to 10% of the meshing frequency. Then, the root mean square amplitude of all spectral components within the preset frequency band is calculated, and the calculation result is used as the planetary gear disturbance characterization value. At the same time, the energy value within the gear pump meshing frequency band is calculated as the pump disturbance reference characteristic. The gear pump meshing frequency is calculated based on the current motor speed, reduction ratio, and the number of teeth on the gear pump; and the amplitude at the point in the current spectrum where the frequency equals the product of the number of motor pole pairs and the motor shaft rotation frequency is extracted as the fundamental current component.

[0043] The meshing frequency of the planetary gears is denoted as f. mesh The unit is Hertz (Hz), and its calculation formula is as follows: f mesh =f motor ×Z sun ; f motor Z is the motor shaft rotation frequency, in Hz, calculated from the motor speed; sun The number of teeth on the sun gear is dimensionless and determined based on the planetary reducer design parameters. The preset bandwidth is denoted as Δf, in Hz, and its value ranges from 0.05f. mesh ~0.1f mesh Preferably, Δf is 0.08f mesh It is calibrated based on the sidefrequency distribution law of the planetary gear system. The perturbation characterization value of the planetary gear is denoted as P. planet The unit is ampere (A), and its calculation uses the root mean square formula, specifically: ; Among them, A k The amplitude of the k-th spectral component within the preset frequency band is given by amperes (A); N is the total number of spectral components within the frequency band, dimensionless. The pump disturbance reference characteristic is denoted as P. pump The unit is ampere (A), and its calculation method is the same as that for phosphorus (P). planet Similarly, the root mean square amplitude is calculated within a preset frequency band corresponding to the gear pump meshing frequency and its harmonics. The fundamental current component is denoted as I. fund The unit is ampere (A), which is the amplitude at the fundamental frequency in the current spectrum.

[0044] Understandably, the planetary gear meshing frequency and its sidebands are key frequency ranges reflecting the operating state of the planetary gear train. When planetary gears experience wear or uneven load distribution, periodic torque fluctuations occur, which modulate the motor current, manifesting as sideband components near the meshing frequency and its harmonics in the current spectrum. Therefore, calculating the energy value within this frequency band can quantify the strength of this modulation effect; the higher the energy value, the more severe the mechanical disturbance in the planetary gear train. Using the root mean square (RMS) value can comprehensively reflect the overall energy level of all spectral components within the frequency band, providing greater stability and reliability than a single frequency amplitude. Simultaneously, introducing pump disturbance reference characteristics and the fundamental current component helps determine the source of the disturbance: if the planetary gear disturbance characterization value increases while the pump characteristics remain essentially unchanged and the fundamental component is stable, the influence of load changes and pump malfunctions can be ruled out, pinpointing the cause to the planetary gear train.

[0045] Understandably, wear on the planetary gears inside a planetary reducer causes periodic changes in the meshing stiffness of the gear teeth, leading to fluctuations in output torque. These fluctuations act on the motor through the mechanical transmission chain, requiring the motor's electromagnetic torque to dynamically balance the load fluctuations, thus generating corresponding modulation signals in the current. Due to the structural characteristics of the planetary gear train, its vibration characteristic frequency is closely related to the meshing frequency and its harmonics, and the modulation caused by wear produces abundant sideband components. By calculating the root mean square energy within a preset frequency band, the overall intensity of these sideband components can be captured, forming a planetary gear disturbance characterization value. The pump disturbance reference characteristic is used to monitor the meshing state of the gear pump itself. If the pump experiences wear or cavitation, it will also produce similar characteristic frequencies, but these frequencies differ from those of the planetary gears, thus allowing for differentiation. The fundamental current component directly reflects the average load torque of the motor. If the fundamental component is stable, it indicates that the overall load remains unchanged, further confirming that the disturbance originates from the transmission chain rather than external load changes. Through the comprehensive application of these characteristics, indirect but effective monitoring of the planetary gear train's state is achieved, providing reliable input for subsequent active control.

[0046] Step S33: Determine whether the planetary gear train disturbance is the main reason for the increase in the planetary gear disturbance characterization value based on the pump disturbance reference characteristics and the fundamental current component.

[0047] Specifically, in step S33, when the planetary gear disturbance characterization value is greater than the historical average value and the change amplitude of the pump disturbance reference characteristic is less than the first preset threshold and the change amplitude of the current fundamental component is less than the second preset threshold, it is determined to be a planetary gear system disturbance.

[0048] In a specific embodiment, based on the planetary gear disturbance characterization value, pump disturbance reference characteristic, and current fundamental component calculated in step S32, it is determined whether the planetary gear system disturbance is the main cause of the increase in the planetary gear disturbance characterization value. First, the historical average value of the planetary gear disturbance characterization value within a preset historical time period is calculated. The length of the historical time period is preset according to the dynamic characteristics of the system, for example, taking the calculated values ​​of the previous 10 sampling periods as a moving average. The planetary gear disturbance characterization value at the current moment is compared with the historical average value to determine whether it is greater than the historical average value. At the same time, the change amplitude of the current pump disturbance reference characteristic relative to its historical average value and the change amplitude of the current current fundamental component relative to its historical average value are calculated. When the planetary gear disturbance characterization value is greater than the historical average value, and the change amplitude of the pump disturbance reference characteristic is less than a first preset threshold, and the change amplitude of the current fundamental component is less than a second preset threshold, it is determined to be a planetary gear system disturbance.

[0049] The historical average value of the planetary gear disturbance characterization value is denoted as P1, and the unit is amperes (A). It is calculated by taking the arithmetic mean of the planetary gear disturbance characterization values ​​from N consecutive samplings, where N is between 10 and 20, preferably 15. The variation amplitude of the pump disturbance reference characteristic is denoted as Δ. Ppump It is dimensionless, and its calculation formula is: ; Among them, P pump The current pump disturbance reference characteristic is given, in amperes (A). P1 is its historical average value, also in amperes (A). The first preset threshold is denoted as ε1, dimensionless, ranging from 0.03 to 0.08, preferably 0.05, calibrated based on the fluctuation level under normal pump operation. The amplitude of the change in the fundamental current component is denoted as ΔI. fund It is dimensionless, and its calculation formula is: ; Among them, I fund I1 is the fundamental component of the current current, in amperes (A), and I1 is its historical average value, in amperes (A). The second preset threshold is denoted as ε2, which is dimensionless and ranges from 0.02 to 0.05. Preferably, ε2 is 0.03, and it is calibrated according to the normal fluctuation range of the load.

[0050] Understandably, the first preset threshold ε1 is used to determine whether the pump disturbance reference characteristics have changed significantly. When the change is less than this threshold, the pump's meshing state is considered basically stable, ruling out the possibility that wear or malfunction of the gear pump itself could cause an increase in disturbance characteristics. The second preset threshold ε2 is used to determine whether the fundamental current component is stable. When the change is less than this threshold, the average load of the motor is considered not to have changed significantly, ruling out the possibility that changes in external load could cause an increase in disturbance characteristics. By using these two thresholds, the increase in the planetary gear disturbance characterization value can be attributed to disturbances within the planetary gear train.

[0051] It is understandable that an increase in the planetary gear disturbance characterization value may be caused by three reasons: first, wear or uneven load distribution in the planetary gear train itself, which is the main operating condition that this invention needs to identify; second, a gear pump malfunction, causing load fluctuations to be transmitted to the motor; and third, a change in the overall system load, leading to an overall increase in the motor current. To accurately distinguish between these three situations, pump disturbance reference characteristics and the fundamental current component are introduced as auxiliary criteria. The pump disturbance reference characteristic is specifically designed for the meshing frequency and harmonic band of the gear pump, and can sensitively reflect the pump's own operating state. If this characteristic remains unchanged, it indicates that the pump is working normally. The fundamental current component reflects the average output torque of the motor, i.e., the average load of the system. If this component is stable, it indicates that the overall load has not changed. When the planetary gear disturbance characterization value increases while both of these auxiliary quantities remain stable, it can be determined that the disturbance source is located inside the planetary gear train.

[0052] Step S4: Compare the planetary gear disturbance characterization value with a preset quiet threshold. When the planetary gear disturbance characterization value is greater than the quiet threshold, determine the torque smoothing adjustment coefficient based on the planetary gear disturbance characterization value. Specifically, in step S4, the torque smoothing adjustment coefficient is determined by a preset nonlinear mapping function based on the proportion of the planetary gear disturbance characterization value that is greater than the quiet threshold. The value range of the torque smoothing adjustment coefficient is greater than or equal to 0 and less than or equal to 1.

[0053] In a specific embodiment, the planetary gear disturbance characterization value calculated in step S3 is compared with a preset quiet threshold. The preset quiet threshold is determined statistically based on the planetary gear disturbance characterization values ​​of the hydraulic power unit under normal operating conditions. Typically, it is the maximum value of the planetary gear disturbance characterization value of a newly assembled system or a system that has just undergone maintenance, operating under no-load or typical load conditions, multiplied by a certain reliability coefficient. When the planetary gear disturbance characterization value is less than or equal to the quiet threshold, the planetary gear system is considered to be operating smoothly and requires no adjustment; the torque smoothing adjustment coefficient is set to 0. When the planetary gear disturbance characterization value is greater than the quiet threshold, the proportion exceeding the quiet threshold is calculated, and the torque smoothing adjustment coefficient is determined based on this proportion using a preset nonlinear mapping function. The value of this coefficient is greater than or equal to 0 and less than or equal to 1.

[0054] The preset quiet threshold is denoted as T. h The unit is ampere (A). Its calibration method is as follows: After the hydraulic power unit is assembled or maintained, collect the planetary gear disturbance characterization values ​​during continuous operation under no-load and typical load conditions. Take the maximum value under all conditions and multiply it by a reliability coefficient of 1.1 to 1.3, preferably 1.2, as the quiet threshold. The proportion of planetary gear disturbance characterization values ​​exceeding the quiet threshold is denoted as r, which is dimensionless. Its calculation formula is as follows: ; Among them, P planet The current planetary gear disturbance characterization value is expressed in amperes (A); the torque smoothing adjustment coefficient is denoted as K. s Dimensionless, its value ranges from greater than or equal to 0 to less than or equal to 1, and its value is determined by a nonlinear mapping function based on the excess ratio r. In this implementation, an exponential function is used. Where b is the exponential coefficient, dimensionless, ranging from 1.0 to 3.0, preferably b is 2.0, and is calibrated according to the smoothness requirements of the system's adjustment characteristics. When r is small, K s As r increases slowly; when r is large, K s Approaching 1.

[0055] Understandably, the excess ratio *r* reflects the relative magnitude of the planetary gear train disturbance compared to the system's acceptable baseline level; a larger *r* indicates a more severe disturbance. The purpose of the nonlinear mapping function is to assign appropriate adjustment strength based on the severity of the disturbance: a smaller adjustment coefficient is applied when the disturbance is minor to avoid over-adjustment affecting the system's dynamic response performance; a larger adjustment coefficient is applied when the disturbance is severe to ensure effective vibration suppression. The use of a nonlinear mapping instead of a linear mapping aims to achieve smooth intervention in the early stages of the disturbance and rapid response when the disturbance intensifies, making the adjustment process more aligned with actual engineering needs. The torque smoothing adjustment coefficient is limited to a range of 0 to 1, where 0 indicates no smoothing adjustment and 1 indicates the strongest smoothing adjustment.

[0056] Understandably, the quiet threshold acts as a safety boundary, defining the system's permissible normal operating range. When the characteristic value exceeds this boundary, it signifies a change in the mechanical state, requiring active intervention. The deviation quantifies the degree of deviation, providing a basis for determining the intensity of regulation. A nonlinear mapping function establishes a correspondence between the degree of mechanical state deviation and the intensity of electronic control regulation, ensuring that the strength of the control action matches the severity of the problem. Furthermore, this mapping function can be customized according to different application scenarios and system characteristics; for example, a steeper mapping curve can be used in vibration-sensitive applications, while a smoother curve can be used in applications with high dynamic response requirements.

[0057] Step S5: Dynamically adjust the dynamic response parameters of the torque control loop of the high-speed motor according to the torque smoothing adjustment coefficient, so that the adjusted dynamic response parameters are less than the original dynamic response parameters.

[0058] Specifically, in step S5, the dynamic response parameter includes the proportional gain of the torque current loop.

[0059] Specifically, in step S5, the dynamic response parameters include the adjustment rate of the PWM duty cycle or the torque compensation coefficient during the commutation process.

[0060] In a specific embodiment, for a high-speed brushless DC motor employing vector control, i.e., field-oriented control, its torque control loop has a defined proportional gain parameter for the torque-current loop. Based on the torque smoothing adjustment coefficient determined in step S4, this proportional gain is dynamically adjusted so that the adjusted proportional gain is less than the original proportional gain. Specifically, the adjustment method is as follows: the torque smoothing adjustment coefficient is denoted as Ks, and the original torque-current loop proportional gain is denoted as K... po The adjusted proportional gain is denoted as K. pad Satisfying the relationship ; Among them, K sK is the torque smoothing adjustment coefficient determined in step S4. It is dimensionless and its value ranges from greater than or equal to 0 to less than or equal to 1. po The original torque-current loop proportional gain preset in the motor controller, the specific value of which is calibrated based on the motor parameters and control system design. For example, for a high-speed brushless DC motor with a rated power of 5kW, K po The value range is typically 50V / A to 200V / A; K pad The adjusted torque current loop proportional gain, in units of K. po The same, is volts per ampere (V / A). When Ks=0, K pad =K po No adjustment is made; when K s When K > 0, pad <K po And the larger Ks is, the more K pad The smaller.

[0061] Understandably, the proportional gain of the torque current loop determines the response speed of the current loop to current errors. The larger the gain, the faster the current tracking command is executed, and the higher the system stiffness, but the more sensitive it is to load fluctuations. The smaller the gain, the slower the current response, and the greater the system flexibility. It can filter out high-frequency disturbances to a certain extent, achieving the goal of dynamically reducing the response speed of the current loop according to the severity of the disturbance, making the electromagnetic torque output of the motor smoother and reducing the tracking of high-frequency torque fluctuations on the mechanical side.

[0062] In another specific embodiment, for a high-speed brushless DC motor using square wave control (i.e., six-step commutation control), its torque control loop does not have an explicit proportional gain parameter, but it does have the PWM duty cycle adjustment rate and the torque compensation coefficient during the commutation process. These parameters together determine the dynamic response characteristics of the torque output. Based on the torque smoothing adjustment coefficient determined in step S4, the PWM duty cycle adjustment rate is dynamically adjusted so that the adjusted rate is less than the original rate. Specifically, the adjustment method is as follows: the original PWM duty cycle adjustment rate is denoted as R... p0 The adjusted PWM duty cycle regulation rate is denoted as R. pa Satisfying the relationship Among them, K s R is the torque smoothing adjustment coefficient determined in step S4, dimensionless, and its value ranges from greater than or equal to 0 to less than or equal to 1; p0 The preset original PWM duty cycle adjustment rate in the motor controller represents the maximum change in the PWM duty cycle per unit time, expressed as percentages per second (% / s). Its value ranges from 5% / ms to 20% / ms, preferably R. p0 Take 10% / ms, which is calibrated based on the motor inductance and inertia parameters; R paThe adjusted PWM duty cycle regulation rate, in units of R. p0 Same. When K s When =0, R pa =R p0 No adjustment is made; when K s When R > 0, pa Less than R p0 And K s The larger R is pa The smaller.

[0063] Simultaneously, the torque compensation coefficient during the commutation process is dynamically adjusted so that the adjusted torque compensation coefficient is less than the original torque compensation coefficient. The original commutation torque compensation coefficient is denoted as C. c0 The adjusted commutation torque compensation coefficient is denoted as C. ca Satisfying the relationship Among them, C c0 The original commutation torque compensation coefficient is preset in the motor controller. It is dimensionless and used to adjust the output voltage during commutation to compensate for torque pulsation. Its value ranges from 0.8 to 1.2, preferably C. c0 The value is set to 1.0, which is calibrated based on the motor's back EMF waveform and commutation characteristics; C ca This is the adjusted commutation torque compensation coefficient, dimensionless. When Ks > 0, C ca Less than C c0 And K s The larger C is ca The smaller.

[0064] It is understandable that the adjustment rate R of the PWM duty cycle p0 The rate of change of applied voltage determines the torque response to commands. A higher rate results in faster torque response, but also greater sensitivity to load fluctuations. A lower rate results in smoother torque changes, but weakens the response to high-frequency disturbances. The commutation torque compensation coefficient is used to offset torque drops during the commutation process of the square wave motor. A larger compensation coefficient provides stronger voltage compensation during commutation, but may introduce additional fluctuations. The torque smoothing adjustment coefficient dynamically reduces the torque response speed according to the severity of the disturbance, thus smoothing the motor's electromagnetic torque output.

[0065] Understandably, the purpose of this step is to find adjustable parameters equivalent to the proportional gain function of the torque current loop for motors of different control types, and to establish a unified adjustment mechanism. For BLDC motors controlled by square waves, although there is no explicit current loop gain, the adjustment rate of the PWM duty cycle determines the speed of voltage change, directly affecting the dynamic response of the electromagnetic torque; the commutation torque compensation coefficient affects the smoothness of the commutation process. By reducing these two parameters, the electromagnetic torque output of the motor can also be made smoother, reducing the tracking ability of high-frequency torque fluctuations on the mechanical side. This adjustment method is physically the same as reducing the proportional gain in vector control; both reduce the response bandwidth of the control system, making it exhibit "low-pass filtering" characteristics for high-frequency disturbances, thereby suppressing electromechanical coupling vibration.

[0066] Specifically, it also includes: Step S6: Repeat steps S2 to S5 until the planetary gear disturbance characterization value is less than or equal to the quiet threshold.

[0067] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A deceleration control method for a high-speed motor-driven hydraulic system, characterized in that, include: In step S1, the output torque of the high-speed motor is transmitted sequentially through the motor shaft, planetary reducer and planetary carrier to the gear pump, driving the gear pump to work; Step S2: Obtain the instantaneous three-phase current signal and DC bus voltage signal of the high-speed motor, preprocess and perform spectrum conversion on the instantaneous three-phase current signal to determine the current spectrum; Step S3: Extract the energy value within a preset frequency band centered on the planetary gear meshing frequency and its harmonics from the current spectrum, and calculate the planetary gear disturbance characterization value. Step S4: Compare the planetary gear disturbance characterization value with a preset quiet threshold. When the planetary gear disturbance characterization value is greater than the quiet threshold, determine the torque smoothing adjustment coefficient based on the planetary gear disturbance characterization value. Step S5: Dynamically adjust the dynamic response parameters of the torque control loop of the high-speed motor according to the torque smoothing adjustment coefficient, so that the adjusted dynamic response parameters are less than the original dynamic response parameters.

2. The deceleration control method for a high-speed motor-driven hydraulic system according to claim 1, characterized in that, Step S2 includes: Step S21: Bandpass filter is applied to the instantaneous three-phase current signal to retain a preset frequency band related to the meshing frequency of the planetary gears; Step S22: The amplitude of the filtered three-phase instantaneous current signal is corrected according to the DC bus voltage signal to obtain the preprocessed current signal. Step S23: Perform a Fourier transform on the preprocessed current signal to convert the time-domain signal into a frequency-domain signal, thereby obtaining the current spectrum.

3. The deceleration control method for a high-speed motor-driven hydraulic system according to claim 2, characterized in that, Step S2 further includes: Step S24: Obtain the winding temperature signal of the high-speed motor and the oil temperature signal of the gear pump; Step S25: Dynamically compensate the preprocessed current signal based on the winding temperature signal and the oil temperature signal.

4. The deceleration control method for a high-speed motor-driven hydraulic system according to claim 1, characterized in that, Step S3 includes: Step S31: Calculate the root mean square of the amplitude of all spectral components within the preset frequency band, and use the calculation result as the perturbation characterization value of the planetary gear. Step S32: Calculate the energy value within the gear pump meshing frequency band as a pump disturbance reference feature, and extract the fundamental current component from the current spectrum; Step S33: Determine whether the planetary gear train disturbance is the main reason for the increase in the planetary gear disturbance characterization value based on the pump disturbance reference characteristics and the fundamental current component.

5. The deceleration control method for a high-speed motor-driven hydraulic system according to claim 4, characterized in that, In step S33, when the planetary gear disturbance characterization value is greater than the historical average value and the change amplitude of the pump disturbance reference characteristic is less than the first preset threshold and the change amplitude of the current fundamental component is less than the second preset threshold, it is determined to be a planetary gear system disturbance.

6. The deceleration control method for a high-speed motor-driven hydraulic system according to claim 1, characterized in that, In step S4, the torque smoothing adjustment coefficient is determined by a preset nonlinear mapping function based on the proportion of the planetary gear disturbance characterization value that is greater than the quiet threshold. The value range of the torque smoothing adjustment coefficient is greater than or equal to 0 and less than or equal to 1.

7. The deceleration control method for a high-speed motor-driven hydraulic system according to claim 1, characterized in that, In step S5, the dynamic response parameter includes the proportional gain of the torque current loop.

8. The deceleration control method for a high-speed motor-driven hydraulic system according to claim 1, characterized in that, In step S5, the dynamic response parameters include the adjustment rate of the PWM duty cycle or the torque compensation coefficient during the commutation process.

9. The deceleration control method for a high-speed motor-driven hydraulic system according to claim 1, characterized in that, Also includes: Step S6: Repeat steps S2 to S5 until the planetary gear disturbance characterization value is less than or equal to the quiet threshold.

10. The deceleration control method for a high-speed motor-driven hydraulic system according to any one of claims 1 to 9, characterized in that, The high-speed motor is a brushless DC motor.

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