Method and system for detecting electromagnetic state of compressor stator and rotor

Abstract

The present application relates to the technical field of compressor electromagnetic state detection, in particular to a compressor stator-rotor electromagnetic state detection method and system. The method obtains operating parameters in the continuous operation process of the compressor, determines a no-torque detection window allowing injection of detection perturbation; injects a pair of no-torque perturbation voltage vectors into the stator winding within the window, collects transient current responses before, during and after injection, equivalent back electromotive force recovery and current loop compensation; generates a stator-rotor differential magnetic guide response matrix according to the perturbation vector and the corresponding response, and determines stator-side impedance abnormalities, rotor-side flux linkage abnormalities or air gap magnetic guide skew abnormalities, and outputs abnormal attribution positions, detection reliability and retest instructions. The method is suitable for compressor factory detection, operation maintenance and electromagnetic abnormality review.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic condition detection technology for compressors, specifically to a method and system for detecting the electromagnetic condition of compressor stators and rotors. Background Technology

[0002] Electromagnetic condition detection of compressor stators and rotors is mainly used for factory testing, operation and maintenance, and anomaly diagnosis of variable frequency compressors, permanent magnet synchronous compressors, and compressors with integrated motors. It is used to determine whether there are abnormalities in the stator windings, rotor flux linkage, air gap magnetic permeability, and their coupling states. Existing methods typically collect current, voltage, speed, vibration, temperature, or pressure signals during compressor operation and determine whether the compressor is in an abnormal operating state through threshold comparison, spectrum analysis, feature extraction, or model recognition.

[0003] However, in actual operation, compressors are affected by refrigerant pressure fluctuations, load changes, speed regulation, and current closed-loop control. Early electromagnetic anomalies in the stator and rotor are easily masked by changes in operating conditions or control compensation. Especially when there are changes in local stator impedance, slight rotor flux linkage shifts, or slight air gap permeability deviations, externally acquired signals often fail to directly reflect the response differences of the electromagnetic structure itself, leading to unclear anomaly attribution and insufficient basis for retesting. Therefore, a method and system for detecting the electromagnetic state of compressor stator and rotor are needed to solve the above problems. Summary of the Invention

[0004] To solve the above problems, the present invention provides the following technical solution: a method for detecting the electromagnetic state of a compressor stator and rotor, comprising: S1. Obtain the operating parameters during the continuous operation of the compressor, and determine the torque-free detection window that allows the injection of detection disturbances based on the operating parameters. The operating parameters include three-phase current, bus voltage, drive frequency, speed estimate, current electrical angle, current loop output, and load stability index. S2. Inject a pair of torque-free perturbation voltage vectors into the stator winding of the compressor within the torque-free detection window. The pair of torque-free perturbation voltage vectors includes a positive detection vector and a reverse compensation vector. The average torque increment of the positive detection vector and the reverse compensation vector within the torque-free detection window satisfies the cancellation condition. S3. Collect the transient current response, equivalent back electromotive force recovery, and current loop compensation of the paired torque-free perturbation voltage vector before, during, and after injection. S4. Generate the stator and rotor differential magnetic permeability response matrix based on the paired torque-free perturbation voltage vectors and their corresponding transient current response, equivalent back electromotive force recovery, and current loop compensation. S5. Determine the electromagnetic state category of the compressor stator and rotor based on the stator and rotor differential magnetic permeability response matrix. The electromagnetic state category of the compressor stator and rotor includes at least one of stator-side impedance abnormality, rotor-side magnetic flux abnormality, and air gap magnetic permeability skewness abnormality. S6. Output the electromagnetic state category of the compressor stator and rotor, the location of the abnormality attribution, and the detection reliability, and generate a retest command when the retest conditions are met.

[0005] Furthermore, determining the torque-free detection window that allows for the injection of detection perturbations based on the operating parameters includes: Determine the rate of change of the current vector based on the three-phase current; The speed fluctuation is determined based on the estimated speed value; The control margin is determined based on the output of the current loop. The continuous operating interval in which the current vector change rate, speed fluctuation, and load stability index are all less than the corresponding thresholds and the control margin is greater than the preset margin threshold is determined as the candidate detection window; When the current electrical angle within the candidate detection window falls within a preset injectable phase range, the candidate detection window is determined as the torque-free detection window.

[0006] Furthermore, the forward detection vector and the reverse compensation vector act in opposite directions along the same detection axis, and the voltage amplitude, duration of action, or duty cycle of the forward detection vector and the reverse compensation vector are configured to make the voltage-time area difference between the two less than a preset area difference threshold, and to make the average torque increment within the torque-free detection window lower than a preset torque disturbance threshold.

[0007] Furthermore, the same detection axis is selected from the direct-axis detection axis, the quadrature-axis detection axis, and the oblique detection axis according to the current electrical angle; when the current loop compensation amount is greater than the preset compensation threshold, the voltage amplitude of the positive detection vector and the reverse compensation vector is reduced, or the injection interval between two adjacent torque-free perturbation voltage vectors is extended.

[0008] Furthermore, the transient current response includes the current increment slope, peak current increment, and current recovery time after perturbation injection; the equivalent back electromotive force recovery amount is determined based on the voltage balance residual after the removal of the paired torque-free perturbation voltage vectors; and the current loop compensation amount is determined based on the compensation voltage increment output by the current regulator during perturbation injection.

[0009] Furthermore, the generation of the stator-rotor differential permeability response matrix includes: Using the detection electrical angle, detection axis direction, and perturbation vector direction as matrix indices, the forward response quantity, reverse response quantity, differential response quantity, response recovery time, response asymmetry quantity, and control compensation residual are written into the matrix cell corresponding to the matrix index to form the stator and rotor differential magnetic permeability response matrix.

[0010] Furthermore, the differential response is obtained by normalizing the positive response and the negative response, and the normalization process includes: The forward response and the reverse response are corrected according to the voltage-time area corresponding to the forward detection vector and the reverse compensation vector, respectively, and the corrected forward response and the reverse response are compensated according to the control compensation residual to obtain a normalized differential response that characterizes the difference in the stator and rotor magnetic circuit response.

[0011] Furthermore, determining the electromagnetic state category of the compressor stator and rotor based on the stator-rotor differential magnetic permeability response matrix includes: When the differential response corresponding to the same phase winding or the combination of adjacent phase windings is continuously greater than the preset stator differential threshold within multiple torque-free detection windows, and the corresponding abnormal position does not migrate with the rotor electrical angle, the electromagnetic state category of the compressor stator and rotor is determined to be stator-side impedance abnormality, and the same phase winding or the combination of adjacent phase windings is determined to be the abnormal attribution position.

[0012] Furthermore, the step of determining the electromagnetic state category of the compressor stator and rotor based on the stator-rotor differential magnetic permeability response matrix further includes: When the equivalent back electromotive force recovery amount shifts periodically with the rotor electrical angle, and the shift position is not fixed to the same phase winding or adjacent phase winding combination, the electromagnetic state category of the compressor stator and rotor is determined to be rotor-side magnetic flux abnormality. When the change in response asymmetry and the difference in response between adjacent detected electrical angles are both greater than the corresponding threshold, and the anomaly occurs repeatedly in a fixed mechanical angle range, the electromagnetic state category of the compressor stator and rotor is determined to be an air gap magnetic permeability skew anomaly. When the load stability index is greater than the preset stability threshold or the control compensation residual is greater than the preset residual threshold, the conclusion that the stator side impedance is abnormal, the rotor side flux linkage is abnormal, or the air gap permeability is abnormal is not output, and the retest command is generated.

[0013] The present invention also provides a compressor stator and rotor electromagnetic state detection system for the above-mentioned compressor stator and rotor electromagnetic state detection method, comprising: The operating parameter acquisition module is used to acquire the operating parameters of the compressor during continuous operation. The operating parameters include three-phase current, bus voltage, drive frequency, speed estimate, current electrical angle, current loop output, and load stability index. The detection window determination module is used to determine, based on the operating parameters, a torque-free detection window that allows the injection of detection perturbations; The perturbation injection module is used to inject a pair of torque-free perturbation voltage vectors into the stator winding of the compressor within the torque-free detection window. The pair of torque-free perturbation voltage vectors includes a positive detection vector and a reverse compensation vector. The average torque increment of the positive detection vector and the reverse compensation vector within the torque-free detection window satisfies the cancellation condition. The response acquisition module is used to acquire the transient current response, equivalent back electromotive force recovery, and current loop compensation before, during, and after the injection of the paired torque-free perturbation voltage vector. The matrix generation module is used to generate the stator and rotor differential magnetic permeability response matrix based on the paired torque-free perturbation voltage vectors and their corresponding transient current response, equivalent back electromotive force recovery, and current loop compensation. An anomaly attribution module is used to determine the electromagnetic state category of the compressor stator and rotor based on the stator-rotor differential magnetic permeability response matrix. The electromagnetic state category of the compressor stator and rotor includes at least one of stator-side impedance anomaly, rotor-side magnetic flux anomaly, and air gap magnetic permeability skew anomaly. The result output module is used to output the electromagnetic state category of the compressor stator and rotor, the location of the abnormality attribution, and the detection reliability, and to generate a retest command when the retest conditions are met.

[0014] Compared with the prior art, the present invention has the following beneficial effects: This method and system for detecting the electromagnetic state of the compressor stator and rotor determines a torque-free detection window during continuous compressor operation and injects paired torque-free micro-perturbation voltage vectors into the stator windings within this window. This allows the stator and rotor magnetic circuits to generate a controlled transient response without significantly altering the average output torque, avoiding reliance on natural operating signals that could be masked by refrigerant pressure fluctuations, load changes, or current closed-loop compensation. By acquiring the transient current response, equivalent back electromotive force recovery, and current loop compensation before and after perturbation injection, a stator-rotor differential permeability response matrix is ​​generated. This allows stator-side impedance changes, rotor-side flux linkage shifts, and air gap permeability skew to be distinguished by different response differences. By combining control compensation residuals and load stability to determine whether to retest, the system reduces the likelihood of misjudging operating disturbances as stator-rotor electromagnetic anomalies, thereby improving the reliability of anomaly attribution locations and detection conclusions. Attached Figure Description

[0015] Figure 1 A schematic diagram of the steps of the compressor stator and rotor electromagnetic state detection method provided by the present invention; Figure 2 A schematic flowchart of the compressor stator and rotor electromagnetic state detection method provided by the present invention; Figure 3This is a schematic diagram of the electromagnetic state detection system for compressor stator and rotor provided by the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] Please see Figure 1 and Figure 2 , Figure 1 A schematic diagram of the steps of the compressor stator and rotor electromagnetic state detection method provided by the present invention; Figure 2 This is a flowchart illustrating the electromagnetic state detection method for compressor stator and rotor provided by the present invention; the present invention provides a method for electromagnetic state detection of compressor stator and rotor, comprising: S1. Obtain the operating parameters during the continuous operation of the compressor, and determine the torque-free detection window that allows the injection of detection disturbances based on the operating parameters. The operating parameters include three-phase current, bus voltage, drive frequency, speed estimate, current electrical angle, current loop output, and load stability index. Specifically, when the compressor is in continuous operation, the variable frequency drive or compressor controller reads the three-phase current, bus voltage, drive frequency, current loop output, and current electrical angle in real time. The speed estimate can be obtained by converting the drive frequency into the number of motor pole pairs, or it can be provided by a sensorless observer or a speed sensor. The load stability index is used to determine whether the current operating range is suitable for detecting disturbances, and it can be formed by one or more of the following: speed fluctuation, bus current fluctuation, discharge pressure change, and electromagnetic torque estimation fluctuation. When the compressor is in the startup, shutdown, rapid frequency increase / decrease, defrost switching, refrigerant pressure change, or controller current limiting phase, the current range is not used as a detection window to avoid the detection response being masked by changes in operating conditions.

[0019] The load stability index can be expressed as:

[0020] in, This indicates a load stability index. This indicates the fluctuation of the estimated rotational speed within the detection window. This indicates the fluctuation in bus current. This indicates the change in exhaust pressure. This represents the estimated fluctuation in electromagnetic torque. and These are preset weights. The preset weights can be determined based on stable operating samples of compressors of the same model, factory calibration data, or historical operating records. If the compressor is not equipped with a pressure sensor, these are omitted. The weights are redistributed based on the available parameters so that the load stability index can still reflect the load disturbance level in the current operating range.

[0021] Furthermore, in one embodiment provided in this application, determining the torque-free detection window that allows for the injection of detection perturbations based on the operating parameters includes: Determine the rate of change of the current vector based on the three-phase current; The speed fluctuation is determined based on the estimated speed value; The control margin is determined based on the output of the current loop. The continuous operating interval in which the current vector change rate, speed fluctuation, and load stability index are all less than the corresponding thresholds and the control margin is greater than the preset margin threshold is determined as the candidate detection window; When the current electrical angle within the candidate detection window falls within a preset injectable phase range, the candidate detection window is determined as the torque-free detection window.

[0022] Specifically, the rate of change of the current vector can be obtained by dividing the difference in the current vector between adjacent sampling times by the sampling interval; the speed fluctuation can be determined by the standard deviation or the maximum-minimum difference of the speed estimates within the candidate interval; and the control margin can be determined by the difference between the allowable output range of the bus voltage and the current output voltage of the current loop. Let the length of the candidate interval be... The current vector is Then the rate of change of the current vector can be expressed as:

[0023] in, This represents the maximum rate of change of the current vector within the candidate interval. This represents the current vector at the current moment. This indicates the sampling interval. The current vector change rate threshold can be determined based on the current vector change range during stable operation of the same model compressor. The speed fluctuation threshold can be determined based on the steady-state speed fluctuation range allowed by the controller. The load stability threshold can be determined based on the load disturbance distribution in the stable operation sample. The preset margin threshold can be determined based on the bus voltage, PWM output resolution, and the minimum implementable amplitude of the disturbance voltage. The current electrical angle is used to limit the disturbance injection location, such as avoiding the rapid commutation range of the current vector or the torque-sensitive range, so that subsequent disturbances mainly excite the stator and rotor magnetic circuit response, rather than causing significant operating disturbances.

[0024] S2. Inject a pair of torque-free perturbation voltage vectors into the stator winding of the compressor within the torque-free detection window. The pair of torque-free perturbation voltage vectors includes a positive detection vector and a reverse compensation vector. The average torque increment of the positive detection vector and the reverse compensation vector within the torque-free detection window satisfies the cancellation condition. Specifically, within the defined torque-free detection window, the controller does not change the original operating setpoint of the compressor. Instead, it superimposes a set of short-duration perturbation voltage vectors onto the original control voltage. The forward probe vector first acts on the selected probe axis, causing transient responses in the stator windings, rotor flux linkage, and air gap permeability. The reverse compensation vector then acts in the opposite direction to counteract the average torque effect introduced by the forward probe vector. The torque-free detection window and torque-free perturbation voltage vectors in this application do not mean that the electromagnetic torque remains absolutely unchanged during the detection process. Rather, they mean that the average torque increment caused by the paired perturbation voltage vectors is limited to within a preset torque disturbance threshold, ensuring that the detected perturbations do not substantially affect the continuous operation of the compressor.

[0025] Furthermore, in one embodiment provided in this application, the forward detection vector and the reverse compensation vector act in opposite directions along the same detection axis, and the voltage amplitude, duration of action, or duty cycle of the forward detection vector and the reverse compensation vector are configured such that the voltage-time area difference between the two is less than a preset area difference threshold, and the average torque increment within the torque-free detection window is lower than a preset torque disturbance threshold.

[0026] Specifically, the voltage amplitude of the forward probe vector is denoted as... The duration of action is recorded as The voltage amplitude of the reverse compensation vector is denoted as The duration of action is recorded as The voltage-time area difference between the two can be expressed as:

[0027] in, This represents the voltage-time-area difference. When... When the area difference is less than a preset area difference threshold, the forward probe vector and the reverse compensation vector are nearly balanced in terms of voltage effect. The preset area difference threshold can be determined based on the bus voltage fluctuation range, PWM minimum resolution, sampling period, and controller output voltage accuracy, and is used to determine whether the forward probe vector and the reverse compensation vector meet the approximate cancellation condition.

[0028] The average torque increment can be determined by the integral difference between the electromagnetic torque estimate within the detection window and the original operating torque estimate, and can be expressed as:

[0029] in, This represents the average torque increment within the detection window. Indicates the length of the detection window. Indicates the start time of the detection window. This represents the estimated electromagnetic torque after the perturbation is injected. This represents the reference electromagnetic torque estimated based on the original control state without injected perturbations. The preset torque perturbation threshold is used to limit the impact range of detected perturbations on the normal output torque of the compressor. It can be determined based on the rated torque of the same model compressor, the average electromagnetic torque within the current stable operating range, the controller's allowable torque ripple limit, the compressor's allowable speed fluctuation range, or factory calibration data. For different speed ranges or different load ranges, the preset torque perturbation threshold can be set to different values, or it can be dynamically generated by the controller based on the current average electromagnetic torque and the allowable speed fluctuation range. If the average torque increment caused by the positive probe vector and the reverse compensation vector within the detection window is greater than the preset torque perturbation threshold, then the perturbation group is determined not to meet the torque-free detection requirements, and the perturbation voltage amplitude is reduced, the duration of action is shortened, or the detection window is reselected.

[0030] Furthermore, in one embodiment provided in this application, the same detection axis is selected from the direct-axis detection axis, the quadrature-axis detection axis, and the oblique detection axis according to the current electrical angle; when the current loop compensation amount is greater than the preset compensation threshold, the voltage amplitude of the positive detection vector and the reverse compensation vector is reduced, or the injection interval between two adjacent torque-free perturbation voltage vectors is extended.

[0031] Specifically, the direct-axis probe is mainly used to excite responses related to rotor flux linkage, the quadrature-axis probe is mainly used to observe the sensitivity of the torque path to disturbances, and the oblique probe is used to enhance the detection capability of air gap permeability deviation when the direct-axis and quadrature-axis responses are not significant. The current electrical angle is used to determine the actual direction of the probe axis in the three-phase stationary coordinate system. The preset compensation threshold can be determined based on the normal adjustment amplitude of the current loop during stable operation, the controller output voltage margin, and the maximum allowable compensation voltage increment during disturbance injection. If the current loop compensation exceeds this threshold, it indicates that the detected disturbance has been significantly suppressed by the controller, and the acquired response can no longer fully characterize the state of the stator and rotor magnetic circuits themselves. Therefore, the disturbance amplitude should be reduced or the interval between two adjacent disturbance injections should be increased to make subsequent response acquisitions comparable.

[0032] S3. Collect the transient current response, equivalent back electromotive force recovery, and current loop compensation of the paired torque-free perturbation voltage vector before, during, and after injection. Specifically, the reference current, voltage, and current loop output are recorded before perturbation injection; the current increment rise is recorded during the positive probe vector action; the current fallback is recorded during the reverse compensation vector action; and the current and voltage recovery processes are recorded after perturbation removal. The transient current response reflects the instantaneous response of the stator impedance and air gap permeability to voltage excitation; the equivalent back electromotive force recovery reflects the recovery state of the rotor flux linkage after perturbation removal; and the current loop compensation is used to determine the degree of controller intervention in the perturbation response. The acquisition process preferentially uses a local sampling frequency higher than the conventional control cycle to ensure that the current slope and recovery time during the perturbation duration can be captured.

[0033] Furthermore, in one embodiment provided in this application, the transient current response includes the current increment slope, current peak increment, and current recovery time after perturbation injection; the equivalent back electromotive force recovery amount is determined based on the voltage balance residual after the removal of the paired torque-free perturbation voltage vectors; and the current loop compensation amount is determined based on the compensation voltage increment output by the current regulator during perturbation injection.

[0034] Specifically, the current increment slope is determined by the short-term current increment change after the perturbation begins; the peak current increment is the maximum deviation of the current within the detection window relative to the pre-injection reference current; and the current recovery time is the time required for the current to return to the allowable deviation range after the perturbation is removed. The equivalent back electromotive force recovery can be obtained based on the voltage balance residual, which can be expressed as:

[0035] in, This represents the voltage balance residual. Indicates the equivalent voltage at the stator terminals. This represents the stator equivalent resistance. This represents the phase current or the current component after coordinate transformation. Indicates the stator equivalent inductance. This represents the rate of change of current. After the perturbation is removed, if... The occurrence of a stable offset near a specific rotor electrical angle indicates an abnormality in the rotor flux recovery process. The current loop compensation is determined by the difference between the current regulator output voltage and the original control voltage. The larger the compensation voltage increment, the higher the degree of intervention of the controller in the perturbation response. This compensation amount is needed to correct or eliminate the response results during subsequent matrix generation.

[0036] S4. Generate the stator and rotor differential magnetic permeability response matrix based on the paired torque-free perturbation voltage vectors and their corresponding transient current response, equivalent back electromotive force recovery, and current loop compensation. Specifically, each torque-free perturbation injection forms a detection sample, which includes the detection electrical angle, probe axis direction, perturbation vector direction, forward response, reverse response, recovery time, response asymmetry, and control compensation residual. The detection samples under different detection electrical angles and probe axes are organized in matrix form to obtain the stator-rotor differential permeability response matrix. This matrix is ​​not a statistical set of ordinary operating signals, but rather a set of correspondences between perturbation inputs and magnetic circuit output responses, used to reflect the differential responses of the stator windings, rotor flux linkage, and air gap permeability to controlled electromagnetic excitation.

[0037] Furthermore, in one embodiment provided in this application, the generation of the stator-rotor differential magnetic permeability response matrix includes: using the detection electrical angle, the detection axis direction, and the perturbation vector direction as matrix indices, writing the forward response quantity, the reverse response quantity, the differential response quantity, the response recovery time, the response asymmetry quantity, and the control compensation residual into the matrix cell corresponding to the matrix index to form the stator-rotor differential magnetic permeability response matrix.

[0038] Specifically, the detected electrical angle is used to identify the relative electromagnetic position between the rotor and stator when a perturbation occurs; the detected axis direction is used to distinguish between direct-axis, quadrature-axis, or oblique excitation; and the perturbation vector direction is used to distinguish between forward detection and reverse compensation. The meanings of the fields in the matrix unit are shown in Table 1 below: Table 1. Meaning of fields in matrix units

[0039] Furthermore, in one embodiment provided in this application, the differential response is obtained by normalizing the positive response and the negative response, and the normalization process includes: The forward response and the reverse response are corrected according to the voltage-time area corresponding to the forward detection vector and the reverse compensation vector, respectively, and the corrected forward response and the reverse response are compensated according to the control compensation residual to obtain a normalized differential response that characterizes the difference in the stator and rotor magnetic circuit response.

[0040] Specifically, since the forward probe vector and the reverse compensation vector may have amplitude or duration errors in the actual output, the response quantity needs to be corrected according to the voltage-time area. Let the forward response quantity be... The reverse response quantity is The forward and reverse voltage time areas are respectively and Control compensation residual is The normalized difference response can then be expressed as:

[0041] in, This represents the normalized differential response. The control compensation residual can be determined by the difference between the current loop compensation during perturbation injection and the normal fluctuation of the current loop under stable operating conditions. It is used to subtract the influence of the controller's active suppression of perturbations from the response result. The preset residual threshold can be determined based on the current loop output fluctuation range, bus voltage sampling error, and current sampling error under perturbation-free operating conditions. When the control compensation residual exceeds the preset residual threshold, it indicates that the detected sample is significantly affected by controller compensation or sampling perturbation, and it is not used to output the final anomaly category. The normalized differential response is used to characterize the true difference in the response of the stator and rotor magnetic circuits to forward and reverse excitations after eliminating the perturbation input area difference and the influence of current loop compensation.

[0042] S5. Determine the electromagnetic state category of the compressor stator and rotor based on the stator and rotor differential magnetic permeability response matrix. The electromagnetic state category of the compressor stator and rotor includes at least one of stator-side impedance abnormality, rotor-side magnetic flux abnormality, and air gap magnetic permeability skewness abnormality. Specifically, anomaly attribution does not rely solely on the magnitude of a single perturbation response. Instead, it compares the changes in matrix units across multiple torque-free detection windows, multiple detection electrical angles, and multiple detection axis directions. Stator-side impedance anomalies are typically associated with a fixed-phase winding or a combination of adjacent phase windings; rotor-side flux linkage anomalies usually migrate with the rotor electrical angle and are not fixed to a single phase winding; air gap permeability skew anomalies simultaneously manifest as asymmetric forward and reverse responses and increased differences between adjacent detection electrical angles, repeating within a fixed mechanical angle range. This attribution method allows stator, rotor, and air gap-related anomalies to be distinguished from the same type of current fluctuations.

[0043] Furthermore, in one embodiment provided by this application, when the differential response corresponding to the same phase winding or the combination of adjacent phase windings is continuously greater than a preset stator differential threshold within multiple torque-free detection windows, and the corresponding abnormal position does not migrate with the rotor electrical angle, the electromagnetic state category of the compressor stator and rotor is determined to be stator-side impedance abnormality, and the same phase winding or the combination of adjacent phase windings is determined to be the abnormal attribution position.

[0044] Specifically, stator-side impedance anomalies may be caused by localized inter-turn degradation, abnormal contact resistance, or localized winding temperature rise. These anomalies are related to the stator's spatial position; therefore, under different rotor electrical angles, the abnormal response will still be more closely tied to the same phase winding or adjacent phase winding combinations. The preset stator differential threshold can be determined based on the distribution range of the normalized differential response in normal samples of the same compressor model, factory calibration data, or confirmed normal samples after maintenance. If the differential response exceeds the preset stator differential threshold multiple times consecutively, but the anomaly does not migrate synchronously with the rotor position, the anomaly can be attributed to the stator side. The anomaly attribution location can be output as phase A, phase B, phase C, or a combination of adjacent phases AB, BC, CA, for subsequent maintenance or production line retesting.

[0045] Furthermore, in one embodiment provided in this application, when the equivalent back electromotive force recovery quantity periodically shifts with the rotor electrical angle, and the shift position is not fixedly bound to the same phase winding or adjacent phase winding combination, the electromagnetic state category of the compressor stator and rotor is determined to be rotor-side flux linkage abnormality; when the response asymmetry quantity and the differential response change quantity between adjacent detected electrical angles are both greater than the corresponding threshold, and the abnormality repeatedly occurs in a fixed mechanical angle range, the electromagnetic state category of the compressor stator and rotor is determined to be air gap permeability skew abnormality; when the load stability index is greater than the preset stability threshold or the control compensation residual is greater than the preset residual threshold, the conclusion of stator-side impedance abnormality, rotor-side flux linkage abnormality, or air gap permeability skew abnormality is not output, and the retest command is generated.

[0046] Specifically, rotor-side flux linkage anomalies typically manifest as a periodic change in the equivalent back electromotive force recovery as the rotor position shifts. For example, local demagnetization or decreased magnet consistency can cause the recovery to repeatedly deviate within the corresponding rotor angle range. For rotor-side flux linkage anomalies, the attribution location can be represented by the corresponding rotor electrical angle range, or the mechanical angle range converted from the rotor electrical angle. Air gap permeability skew anomalies are usually related to mechanical eccentricity, uneven assembly clearances, or shaft runout, manifesting as enhanced asymmetric response in both forward and reverse directions, and significant changes in the differential response between adjacent detected electrical angles. For air gap permeability skew anomalies, the attribution location can be represented by the recurring mechanical angle range with asymmetric response, or a fixed angle range within the compressor's rotational cycle. The preset stability threshold can be determined by the compressor's speed fluctuations, bus current fluctuations, discharge pressure changes, or estimated electromagnetic torque fluctuations in a stable operating sample. If the load stability is insufficient or the control compensation residual is large, it means that the current detection sample cannot fully represent the inherent response of the stator and rotor magnetic circuit. At this time, no abnormal category is output. Instead, the detection sample is marked as invalid and waits for the next torque-free detection window that meets the conditions to re-execute the perturbation injection and response acquisition.

[0047] S6. Output the electromagnetic state category of the compressor stator and rotor, the location of the abnormality attribution, and the detection reliability, and generate a retest command when the retest conditions are met.

[0048] Specifically, the output includes the electromagnetic state category, the location of the anomaly attribution, the matrix fields supporting the conclusion, the detection confidence level, and whether retesting is required. The detection confidence level can be determined by the number of effective detection windows, the repeatability of the differential response, the degree of cancellation of forward and reverse perturbations, load stability, and control compensation residuals. Let the effective detection window number factor be... The repeatability factor of the difference response is The positive and negative offsetting factor is The load stability factor is The control compensation residual factor is The reliability of the detection can be expressed as:

[0049] in, Indicates the reliability of the detection. These are preset weights. The effective detection window quantity factor reflects the number of available samples; the differential response repeatability factor reflects the consistency of abnormal responses across multiple windows; the positive and negative cancellation factor reflects the effectiveness of pairwise perturbations in canceling the average torque; the load stability factor reflects whether the operating conditions are stable during the detection period; and the control compensation residual factor reflects the degree to which the detection response is suppressed by the controller. These preset weights can be set based on calibration data of the same model compressor or historical detection records. If the value falls below the confidence threshold, or if the retest condition is triggered, a retest instruction is output instead of being considered a final anomaly conclusion; if If the confidence threshold is reached, the corresponding anomaly category and attribution location will be output for factory testing, online maintenance, or controller alarm verification.

[0050] Please see Figure 3 , Figure 3 This is a schematic diagram of the compressor stator and rotor electromagnetic state detection system provided by the present invention. The present invention also provides a compressor stator and rotor electromagnetic state detection system for implementing the above-mentioned compressor stator and rotor electromagnetic state detection method, comprising: The operating parameter acquisition module is used to acquire the operating parameters of the compressor during continuous operation. The operating parameters include three-phase current, bus voltage, drive frequency, speed estimate, current electrical angle, current loop output, and load stability index. The detection window determination module is used to determine, based on the operating parameters, a torque-free detection window that allows the injection of detection perturbations; The perturbation injection module is used to inject a pair of torque-free perturbation voltage vectors into the stator winding of the compressor within the torque-free detection window. The pair of torque-free perturbation voltage vectors includes a positive detection vector and a reverse compensation vector. The average torque increment of the positive detection vector and the reverse compensation vector within the torque-free detection window satisfies the cancellation condition. The response acquisition module is used to acquire the transient current response, equivalent back electromotive force recovery, and current loop compensation before, during, and after the injection of the paired torque-free perturbation voltage vector. The matrix generation module is used to generate the stator and rotor differential magnetic permeability response matrix based on the paired torque-free perturbation voltage vectors and their corresponding transient current response, equivalent back electromotive force recovery, and current loop compensation. An anomaly attribution module is used to determine the electromagnetic state category of the compressor stator and rotor based on the stator-rotor differential magnetic permeability response matrix. The electromagnetic state category of the compressor stator and rotor includes at least one of stator-side impedance anomaly, rotor-side magnetic flux anomaly, and air gap magnetic permeability skew anomaly. The result output module is used to output the electromagnetic state category of the compressor stator and rotor, the location of the abnormality attribution, and the detection reliability, and to generate a retest command when the retest conditions are met.

[0051] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for detecting the electromagnetic state of a compressor stator and rotor, characterized in that, include: S1. Obtain the operating parameters during the continuous operation of the compressor, and determine the torque-free detection window that allows the injection of detection disturbances based on the operating parameters. The operating parameters include three-phase current, bus voltage, drive frequency, speed estimate, current electrical angle, current loop output, and load stability index. S2. Inject a pair of torque-free perturbation voltage vectors into the stator winding of the compressor within the torque-free detection window. The pair of torque-free perturbation voltage vectors includes a positive detection vector and a reverse compensation vector. The average torque increment of the positive detection vector and the reverse compensation vector within the torque-free detection window satisfies the cancellation condition. S3. Collect the transient current response, equivalent back electromotive force recovery, and current loop compensation of the paired torque-free perturbation voltage vector before, during, and after injection. S4. Generate the stator and rotor differential magnetic permeability response matrix based on the paired torque-free perturbation voltage vectors and their corresponding transient current response, equivalent back electromotive force recovery, and current loop compensation. S5. Determine the electromagnetic state category of the compressor stator and rotor based on the stator and rotor differential magnetic permeability response matrix. The electromagnetic state category of the compressor stator and rotor includes at least one of stator-side impedance abnormality, rotor-side magnetic flux abnormality, and air gap magnetic permeability skewness abnormality. S6. Output the electromagnetic state category of the compressor stator and rotor, the location of the abnormality attribution, and the detection reliability, and generate a retest command when the retest conditions are met.

2. The compressor stator and rotor electromagnetic state detection method according to claim 1, characterized in that, The step of determining the torque-free detection window that allows for the injection of detection perturbations based on the operating parameters includes: Determine the rate of change of the current vector based on the three-phase current; The speed fluctuation is determined based on the estimated speed value; The control margin is determined based on the output of the current loop. The continuous operating interval in which the current vector change rate, speed fluctuation, and load stability index are all less than the corresponding thresholds and the control margin is greater than the preset margin threshold is determined as the candidate detection window; When the current electrical angle within the candidate detection window falls within a preset injectable phase range, the candidate detection window is determined as the torque-free detection window.

3. The method for detecting the electromagnetic state of the compressor stator and rotor according to claim 1, characterized in that, The forward detection vector and the reverse compensation vector act in opposite directions along the same detection axis, and the voltage amplitude, duration of action, or duty cycle of the forward detection vector and the reverse compensation vector are configured such that the voltage-time area difference between the two is less than a preset area difference threshold, and the average torque increment within the torque-free detection window is lower than a preset torque disturbance threshold.

4. The compressor stator and rotor electromagnetic state detection method according to claim 3, characterized in that, The same detection axis is selected from the direct-axis detection axis, the quadrature-axis detection axis, and the oblique detection axis according to the current electrical angle; when the current loop compensation amount is greater than the preset compensation threshold, the voltage amplitude of the positive detection vector and the reverse compensation vector is reduced, or the injection interval between two adjacent torque-free perturbation voltage vectors is extended.

5. The method for detecting the electromagnetic state of the compressor stator and rotor according to claim 1, characterized in that, The transient current response includes the current increment slope, peak current increment, and current recovery time after perturbation injection; the equivalent back electromotive force recovery is determined based on the voltage balance residual after the removal of the paired torque-free perturbation voltage vectors; and the current loop compensation is determined based on the compensation voltage increment output by the current regulator during perturbation injection.

6. The method for detecting the electromagnetic state of the compressor stator and rotor according to claim 1, characterized in that, The generation of the stator and rotor differential magnetic permeability response matrix includes: Using the detection electrical angle, detection axis direction, and perturbation vector direction as matrix indices, the forward response quantity, reverse response quantity, differential response quantity, response recovery time, response asymmetry quantity, and control compensation residual are written into the matrix cell corresponding to the matrix index to form the stator and rotor differential magnetic permeability response matrix.

7. The method for detecting the electromagnetic state of the compressor stator and rotor according to claim 6, characterized in that, The differential response is obtained by normalizing the forward response and the reverse response. The normalization process includes: The forward response and the reverse response are corrected according to the voltage-time area corresponding to the forward detection vector and the reverse compensation vector, respectively, and the corrected forward response and the reverse response are compensated according to the control compensation residual to obtain a normalized differential response that characterizes the difference in the stator and rotor magnetic circuit response.

8. The method for detecting the electromagnetic state of the compressor stator and rotor according to claim 6, characterized in that, The determination of the compressor stator and rotor electromagnetic state categories based on the stator and rotor differential magnetic permeability response matrix includes: When the differential response corresponding to the same phase winding or the combination of adjacent phase windings is continuously greater than the preset stator differential threshold within multiple torque-free detection windows, and the corresponding abnormal position does not migrate with the rotor electrical angle, the electromagnetic state category of the compressor stator and rotor is determined to be stator-side impedance abnormality, and the same phase winding or the combination of adjacent phase windings is determined to be the abnormal attribution position.

9. The method for detecting the electromagnetic state of the compressor stator and rotor according to claim 6, characterized in that, The method of determining the electromagnetic state category of the compressor stator and rotor based on the stator-rotor differential magnetic permeability response matrix further includes: When the equivalent back electromotive force recovery amount shifts periodically with the rotor electrical angle, and the shift position is not fixed to the same phase winding or adjacent phase winding combination, the electromagnetic state category of the compressor stator and rotor is determined to be rotor-side magnetic flux abnormality. When the change in response asymmetry and the difference in response between adjacent detected electrical angles are both greater than the corresponding threshold, and the anomaly occurs repeatedly in a fixed mechanical angle range, the electromagnetic state category of the compressor stator and rotor is determined to be an air gap magnetic permeability skew anomaly. When the load stability index is greater than the preset stability threshold or the control compensation residual is greater than the preset residual threshold, the conclusion that the stator side impedance is abnormal, the rotor side flux linkage is abnormal, or the air gap permeability is abnormal is not output, and the retest command is generated.

10. A compressor stator and rotor electromagnetic condition detection system, used to implement the compressor stator and rotor electromagnetic condition detection method according to any one of claims 1 to 9, characterized in that, include: The operating parameter acquisition module is used to acquire the operating parameters of the compressor during continuous operation. The operating parameters include three-phase current, bus voltage, drive frequency, speed estimate, current electrical angle, current loop output, and load stability index. The detection window determination module is used to determine, based on the operating parameters, a torque-free detection window that allows the injection of detection perturbations; The perturbation injection module is used to inject a pair of torque-free perturbation voltage vectors into the stator winding of the compressor within the torque-free detection window. The pair of torque-free perturbation voltage vectors includes a positive detection vector and a reverse compensation vector. The average torque increment of the positive detection vector and the reverse compensation vector within the torque-free detection window satisfies the cancellation condition. The response acquisition module is used to acquire the transient current response, equivalent back electromotive force recovery, and current loop compensation before, during, and after the injection of the paired torque-free perturbation voltage vector. The matrix generation module is used to generate the stator and rotor differential magnetic permeability response matrix based on the paired torque-free perturbation voltage vectors and their corresponding transient current response, equivalent back electromotive force recovery, and current loop compensation. An anomaly attribution module is used to determine the electromagnetic state category of the compressor stator and rotor based on the stator-rotor differential magnetic permeability response matrix. The electromagnetic state category of the compressor stator and rotor includes at least one of stator-side impedance anomaly, rotor-side magnetic flux anomaly, and air gap magnetic permeability skew anomaly. The result output module is used to output the electromagnetic state category of the compressor stator and rotor, the location of the abnormality attribution, and the detection reliability, and to generate a retest command when the retest conditions are met.

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