Diagnostic methods for motor faults

Abstract

The present invention provides a method for diagnosing motor faults. By obtaining the deviation value of the actual value of the d-axis voltage relative to the theoretical value and the deviation value of the actual value of the q-axis voltage relative to the theoretical value, it is possible to diagnose whether the motor has a fault. It can be seen that the diagnostic process of the diagnostic method is simple and convenient, and the current state of the motor can be known in a timely manner. Moreover, the motor can be diagnosed when there is only a slight deviation in the performance of the motor, so that the motor can be repaired in time, and the performance of the motor is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of motors, and in particular to a method for diagnosing motor faults. Background Art

[0002] Generally speaking, the main function of a motor is to generate driving torque, serving as a power source for electrical devices or various machines. Commonly used motors include, for example, permanent magnet synchronous motors.

[0003] At present, the drive control of permanent magnet synchronous motors is significantly affected by rotor offset angle, flux, stator inductance, three-phase current, etc. Therefore, fault diagnosis of rotor offset angle, flux, and stator inductance is particularly important. In the current motor fault diagnosis strategy, the rotor offset angle and the rationality of the three-phase current are diagnosed separately. However, these diagnostic strategies will only generate a fault response when the diagnostic object has caused a significant impact on the performance of the motor.

[0004] However, when the parameter value of the diagnosis object has already deviated, but has not caused a significant impact on the performance of the motor, the hidden problem cannot be discovered, and the predictive diagnosis function is not available. Summary of the invention

[0005] The object of the present invention is to provide a method for diagnosing motor faults, so as to solve the problem that existing diagnostic testing strategies cannot promptly and conveniently diagnose whether a motor has a fault.

[0006] In order to solve the above technical problems, the present invention provides a method for diagnosing motor faults, comprising:

[0007] Acquiring a theoretical value of a d-axis voltage and a theoretical value of a q-axis voltage of the motor, and detecting an actual value of the d-axis voltage and an actual value of the q-axis voltage of the motor;

[0008] Comparing the actual value of the d-axis voltage of the motor with the theoretical value to obtain a deviation value of the d-axis voltage, and comparing the actual value of the q-axis voltage with the theoretical value to obtain a deviation value of the q-axis voltage; and,

[0009] Whether the motor has a fault is diagnosed based on the deviation value of the d-axis voltage and the deviation value of the q-axis voltage of the motor.

[0010] Optionally, based on the deviation value of the d-axis voltage and the deviation value of the q-axis voltage of the motor, a method for diagnosing whether the motor is faulty includes: when the deviation value of the d-axis voltage exceeds the allowable deviation range, and the deviation value of the q-axis voltage is within the allowable deviation range, it is diagnosed that the q-axis inductance of the motor is faulty.

[0011] Optionally, the method for diagnosing a fault in the q-axis inductance of the motor further includes:

[0012] When the deviation value of the d-axis voltage exceeds the allowable deviation range in the positive direction, it is diagnosed that the actual value of the q-axis inductance of the motor is smaller than the theoretical value;

[0013] When the deviation value of the d-axis voltage exceeds the allowable deviation range in the negative direction, it is diagnosed that the actual value of the q-axis inductance of the motor is larger than the theoretical value.

[0014] Optionally, the d-axis voltage of the motor conforms to the d-axis voltage equation shown below:

[0015] U d =R s *I d -ω r *L q *I q ;

[0016] Among them, U d is the d-axis voltage;

[0017] R S is the stator resistance;

[0018] I q is the q-axis current;

[0019] I d is the d-axis current;

[0020] ω r is the rotor angular velocity;

[0021] Lq is the q-axis inductance.

[0022] Optionally, when diagnosing that the q-axis inductance of the motor has a fault, the diagnostic method further includes: obtaining a deviation equation of the d-axis voltage with respect to the q-axis inductance according to the d-axis voltage equation, and calculating a deviation of an actual value of the q-axis inductance relative to a theoretical value using the deviation equation of the d-axis voltage with respect to the q-axis inductance; wherein the deviation equation of the d-axis voltage with respect to the q-axis inductance is as follows;

[0023] U d-err =-ω r *I q (L ql -L q2 )

[0024] Among them, U d-err is the deviation of the actual value of the d-axis voltage from the theoretical value;

[0025] L q1 is the actual value of the q-axis inductance;

[0026] L q2 is the theoretical value of the q-axis inductance.

[0027] Optionally, based on the deviation value of the d-axis voltage and the deviation value of the q-axis voltage of the motor, a method for diagnosing whether the motor is faulty includes: when the deviation value of the d-axis voltage is within the allowable deviation range, and the deviation value of the q-axis voltage exceeds the allowable deviation range, it is diagnosed that there is a fault in the magnetic flux of the motor.

[0028] Optionally, the method for diagnosing a magnetic flux fault of the motor further includes:

[0029] When the deviation value of the q-axis voltage exceeds the allowable deviation range in the positive direction, it is diagnosed that the actual value of the magnetic flux of the motor is larger than the theoretical value;

[0030] When the deviation value of the q-axis voltage exceeds the allowable deviation range in the negative direction, it is diagnosed that the actual value of the magnetic flux of the motor is smaller than the theoretical value.

[0031] Optionally, the q-axis voltage of the motor conforms to the q-axis voltage equation shown below:

[0032]

[0033] Among them, U q is the q-axis voltage;

[0034] R S is the stator resistance;

[0035] I q is the q-axis current;

[0036] I d is the d-axis current;

[0037] ω r is the rotor angular velocity;

[0038] is the magnetic link;

[0039] Ld is the d-axis inductance.

[0040] Optionally, when diagnosing that the magnetic flux of the motor is faulty, the diagnostic method further includes:

[0041] According to the q-axis voltage equation, a deviation equation of the q-axis voltage with respect to the flux is obtained, and the deviation of the actual value of the flux relative to the theoretical value is calculated using the deviation equation of the q-axis voltage with respect to the flux; wherein the deviation equation of the q-axis voltage with respect to the flux is as follows:

[0042]

[0043] Among them, U q-err is the deviation of the actual value of the q-axis voltage from the theoretical value;

[0044] is the actual value of magnetic linkage;

[0045] is the theoretical value of magnetic flux.

[0046] Optionally, based on the deviation value of the d-axis voltage and the deviation value of the q-axis voltage of the motor, a method for diagnosing whether the motor is faulty includes: when the deviation value of the d-axis voltage and the deviation value of the q-axis voltage both exceed the allowable deviation range, it is diagnosed that there is a fault in the offset angle of the motor.

[0047] Optionally, the method for diagnosing that the offset angle of the motor is faulty further includes:

[0048] When the deviation value of the d-axis voltage exceeds the allowable deviation range in the positive direction and the deviation value of the q-axis voltage exceeds the allowable deviation range in the negative direction, it is diagnosed that the actual value of the offset angle of the motor is larger than the theoretical value;

[0049] When the deviation value of the d-axis voltage exceeds the allowable deviation range in the negative direction and the deviation value of the q-axis voltage exceeds the allowable deviation range in the positive direction, it is diagnosed that the actual value of the offset angle of the motor is smaller than the theoretical value.

[0050] Optionally, when diagnosing that the magnetic flux of the motor is faulty, the diagnostic method further comprises: calculating a deviation of an actual value of the offset angle relative to a theoretical value according to a deviation equation of a d-axis voltage with respect to the offset angle and a deviation equation of a q-axis voltage with respect to the offset angle;

[0051] The deviation equation of the d-axis voltage with respect to the offset angle is as follows:

[0052]

[0053] And, the deviation equation of the q-axis voltage with respect to the offset angle is as follows:

[0054]

[0055] Among them, U d-err is the deviation of the actual value of the d-axis voltage from the theoretical value;

[0056] U q-err is the deviation of the actual value of the q-axis voltage from the theoretical value;

[0057] I S is the stator current;

[0058] ω r is the rotor angular velocity;

[0059] Ld is the d-axis inductance;

[0060] Lq is the q-axis inductance;

[0061] β is the theoretical value of the deviation angle;

[0062] Δθ is the deviation of the actual value of the offset angle relative to the theoretical value, and both sinβ and cosβ are located in the second quadrant.

[0063] Optionally, the method for diagnosing whether the motor is faulty also includes:

[0064] Obtaining a theoretical value and an actual value of the torque of the motor, and comparing the theoretical value and the actual value of the torque of the motor to obtain a torque deviation value; and,

[0065] When the deviation value of the d-axis voltage and the deviation value of the torque exceed the allowable deviation range in opposite directions, and the deviation value of the q-axis voltage does not exceed the allowable deviation range, it is diagnosed that the q-axis inductance of the motor is faulty;

[0066] When the deviation value of the q-axis voltage and the deviation value of the torque both exceed the allowable deviation range in the same direction, and the deviation value of the d-axis voltage does not exceed the allowable deviation range, it is diagnosed that the magnetic flux of the motor is faulty;

[0067] When the deviation value of the q-axis voltage and the deviation value of the d-axis voltage exceed the allowable deviation range in opposite directions, and the deviation value of the torque exceeds the allowable deviation range in the negative direction, it is diagnosed that the offset angle of the motor is faulty.

[0068] Optionally, when it is diagnosed that the q-axis inductance of the motor is faulty, the method further includes:

[0069] When the torque deviation value exceeds the allowable deviation range in the negative direction, it is diagnosed that the actual value of the q-axis inductance of the motor is smaller than the theoretical value;

[0070] When the deviation value of the torque exceeds the allowable deviation range in the positive direction, it is diagnosed that the actual value of the q-axis inductance of the motor is larger than the theoretical value.

[0071] Optionally, when it is diagnosed that the magnetic flux of the motor is faulty, the method further includes:

[0072] When the torque deviation value exceeds the allowable deviation range in the negative direction, it is diagnosed that the actual value of the q-axis inductance of the motor is smaller than the theoretical value;

[0073] When the deviation value of the torque exceeds the allowable deviation range in the positive direction, it is diagnosed that the actual value of the q-axis inductance of the motor is larger than the theoretical value.

[0074] Optionally, the torque of the motor complies with the torque equation shown below:

[0075]

[0076] Among them, T r is the torque;

[0077] P is the number of motor pole pairs

[0078] I q is the q-axis current;

[0079] I d is the d-axis current, and the d-axis current I d and q-axis current I q is the opposite vector;

[0080] is the magnetic link;

[0081] L d is the d-axis inductance;

[0082] L q is the q-axis inductance.

[0083] Optionally, when diagnosing that the q-axis inductance of the motor has a fault, the diagnostic method further includes: obtaining a deviation equation of the torque with respect to the q-axis inductance according to the torque equation, and calculating a deviation of the actual value of the q-axis inductance relative to the theoretical value using the deviation equation of the torque with respect to the q-axis inductance; wherein the deviation equation of the torque with respect to the q-axis inductance is as follows:

[0084]

[0085] Among them, T err It is the deviation of the actual value of torque from the theoretical value;

[0086] Lq1 is the actual value of the q-axis inductance;

[0087] Lq2 is the theoretical value of the q-axis inductance.

[0088] Optionally, when diagnosing that there is a fault in the flux of the motor, the diagnostic method further includes: obtaining a deviation equation of the torque with respect to the flux according to the torque equation, and calculating a deviation of the actual value of the flux relative to the theoretical value using the deviation equation of the torque with respect to the flux; wherein the deviation equation of the torque with respect to the flux is as follows:

[0089]

[0090] Among them, T err It is the deviation of the actual value of torque from the theoretical value;

[0091] is the actual value of magnetic linkage;

[0092] is the theoretical value of magnetic flux.

[0093] In the motor fault diagnosis method provided by the present invention, it is possible to directly infer whether the motor has a fault based on the deviation of the actual value of the d-axis voltage relative to the theoretical value and the deviation of the actual value of the q-axis voltage relative to the theoretical value. The diagnosis method provided by the present invention is simple and convenient, and can monitor the current status of the motor in a timely manner. Further, when the performance of the motor has only a slight deviation, it can predictively diagnose the hidden dangers of the motor and adjust the performance of the motor in a timely manner.

[0094] Furthermore, the diagnostic object with fault in the motor can be further inferred based on the deviation direction of the d-axis voltage and the deviation direction of the q-axis voltage. In other words, for multiple diagnostic objects, the deviation direction of the d-axis voltage and the deviation direction of the q-axis voltage can be used to exclude the diagnostic objects without fault one by one, and infer the diagnostic objects with fault. In this way, targeted adjustments can be made for the diagnostic objects with fault, thereby improving the efficiency of repairing motor faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Figure 1 is a flow chart of a method for diagnosing motor faults in one embodiment of the present invention;

[0096] Figure 2 The figure is a flowchart of a diagnosis process of a diagnosis object in a method for diagnosing a motor fault in an embodiment of the present invention. DETAILED DESCRIPTION

[0097] The motor fault diagnosis method proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0098] Figure 1 The figure is a flow chart of a motor fault diagnosis method in an embodiment of the present invention, and the motor fault diagnosis method in this embodiment is described in detail in conjunction with the accompanying drawings. And, the motor in this embodiment is, for example, a permanent magnet synchronous motor.

[0099] In step S100 , a theoretical value of a d-axis voltage and a theoretical value of a q-axis voltage of a motor are acquired, and an actual value of a d-axis voltage and an actual value of a q-axis voltage of the motor are detected.

[0100] In step S200, the theoretical value and the actual value of the d-axis voltage of the motor are compared to obtain the deviation value U of the d-axis voltage. d-err ; and, comparing the theoretical value and the actual value of the q-axis voltage to obtain the deviation value U of the q-axis voltage q-err .

[0101] After extensive research and experiments, the inventor of the present application found that by comparing the theoretical value with the actual value, the deviation value U of the actual value of the motor d-axis voltage relative to the theoretical value can be obtained. d-er The deviation value U of the actual value of the q-axis voltage relative to the theoretical value q-err In this way, it is possible to further diagnose whether the motor has a fault, refer to step 300 for details.

[0102] In step S300, according to the deviation value U of the d-axis voltage of the motor d-er and the deviation value U of the q-axis voltage q-err , diagnose whether the motor is faulty.

[0103] Specifically, for example, the allowable deviation range [-Udx, Udx] can be preset for the d-axis voltage, the allowable deviation range [-Uqx, Uqx] can be preset for the q-axis voltage, and the deviation value U of the d-axis voltage can be determined. d-err Whether it exceeds the allowable deviation range [-Udx, Udx], and the deviation value U of the q-axis voltage q-err Whether it exceeds the allowable deviation range [-Uqx, Uqx]. If both items are within their corresponding allowable deviation range, it can be diagnosed that the motor has no fault; if one of them exceeds its corresponding allowable deviation range, it can be diagnosed that the motor may have a fault.

[0104] Figure 2 FIG. 1 is a flow chart of a diagnostic process of a diagnostic object in a method for diagnosing a motor fault in an embodiment of the present invention. Figure 2 As shown, in a specific embodiment, according to the deviation value U of the d-axis voltage of the motor d-err and the deviation value U of the q-axis voltage q-err , the method for diagnosing whether the motor has a fault and diagnosing the specific fault object includes:

[0105] When the d-axis voltage deviation value U d-err Out of the allowable deviation range [-Udx, Udx] (i.e., │U d-err │>Udx), and the deviation value of the q-axis voltage U q-err Within the allowable deviation range [-Uqx, Uqx] (i.e., |U q-err │≤Uqx), it is diagnosed that the q-axis inductance of the motor is faulty.

[0106] When the d-axis voltage deviation value U d-err Within the allowable deviation range [-Udx, Udx] (i.e., |U d-err │≤Udx), and the deviation value of the q-axis voltage U q-errOut of the allowable deviation range [-Uqx, Uqx] (i.e., │U q-err │>Uqx), it is diagnosed that the magnetic flux of the motor is faulty.

[0107] When the d-axis voltage deviation value U d-err and the deviation value U of the q-axis voltage q-err All exceed the allowable deviation range (i.e., │U d-err │>Udx; │U q-err │>Uqx), it is diagnosed that the offset angle of the motor is faulty.

[0108] That is, in this embodiment, by confirming whether there is a deviation in the d-axis voltage and whether there is a deviation in the q-axis voltage, it is possible to infer that there is a fault diagnosis object in the motor, so that timely adjustments can be made based on the fault diagnosis object of the motor to ensure the normal operation of the motor. In addition, the diagnosis process of the motor fault as described above is not only simple in diagnosis, but also takes a short time, so that the current state of the motor can be detected in time.

[0109] In a further scheme, after the diagnostic object with fault is preliminarily inferred according to the diagnostic method as described above, it can also include: confirming that the actual value of the d-axis voltage is a positive deviation or a negative deviation relative to the theoretical value, and confirming that the actual value of the q-axis voltage is a positive deviation or a negative deviation relative to the theoretical value, so that on the basis of diagnosing the fault diagnostic object of the motor, it can be further inferred that the actual value of the fault diagnostic object is larger or smaller than the theoretical value. Based on this, the fault diagnostic object of the motor can be adjusted in a targeted manner.

[0110] Specifically, when the q-axis inductance of the motor is diagnosed to be faulty, the method further includes: further confirming the deviation value U of the d-axis voltage d-err It is outside the permissible deviation range in the positive direction or outside the permissible deviation range in the negative direction.

[0111] Among them, when the deviation value of the d-axis voltage U d-err When the positive direction exceeds the allowable deviation range [-Udx, Udx], that is, the actual value of the d-axis voltage is larger than the theoretical value (U d-err >Udx), it is diagnosed that the actual value of the q-axis inductance of the motor is smaller than the theoretical value.

[0112] Or, when the d-axis voltage deviation value U d-err The negative direction exceeds the allowable deviation range [-Udx, Udx], that is, the actual value of the d-axis voltage is smaller than the theoretical value (U d-err <-Udx), it is diagnosed that the actual value of the q-axis inductance of the motor is larger than the theoretical value.

[0113] And, when the motor flux fault is diagnosed, the method further includes: further confirming the deviation value U of the q-axis voltage q-err It is outside the permissible deviation range in the positive direction or outside the permissible deviation range in the negative direction.

[0114] Among them, when the deviation value of the q-axis voltage is U q-err The positive direction exceeds the allowable deviation range [-Uqx, Uqx], that is, the actual value of the q-axis voltage is larger than the theoretical value (U q-err >Uqx), it is diagnosed that the actual value of the magnetic flux of the motor is larger than the theoretical value.

[0115] Or, when the deviation value of the q-axis voltage is U q-err The negative direction exceeds the allowable deviation range [-Uqx, Uqx], that is, the actual value of the q-axis voltage is smaller than the theoretical value (U q-err <-Uqx), it is diagnosed that the actual value of the magnetic flux of the motor is smaller than the theoretical value.

[0116] And, when the motor offset angle is diagnosed to be faulty, the method further includes: further confirming the deviation value U of the d-axis voltage d-err The positive direction exceeds the allowable deviation range or the negative direction exceeds the allowable deviation range; and confirm the deviation value U of the q-axis voltage q-err It is outside the permissible deviation range in the positive direction or outside the permissible deviation range in the negative direction.

[0117] When the deviation of the d-axis voltage exceeds the allowable deviation range (i.e., U d-err >Udx), the deviation of the q-axis voltage exceeds the allowable deviation range in the negative direction (i.e., U q-err <-Uqx), it is diagnosed that the actual value of the offset angle of the motor is larger than the theoretical value.

[0118] Or, when the deviation of the d-axis voltage exceeds the allowable deviation range (i.e., U d-err <-Udx), the deviation of the q-axis voltage exceeds the allowable deviation range in the positive direction (i.e., U q-err >Uqx), it is diagnosed that the actual value of the offset angle of the motor is smaller than the theoretical value.

[0119] Therefore, when it is known that there is a fault in the motor, the specific deviation direction of the fault diagnosis object can be further known, which is conducive to further adjustment of the fault diagnosis object.

[0120] In this embodiment, based on the diagnosis process described above, a comparison table as shown in Table 1 is summarized.

[0121]

[0122]

[0123] Table 1

[0124] In Table 1, “━” means that the difference between the actual value and the theoretical value is within the allowable deviation range;

[0125] “↓” means: the actual value is smaller than the theoretical value and the difference exceeds the allowable deviation range;

[0126] “↑” means: the actual value is larger than the theoretical value and the difference exceeds the allowable deviation range.

[0127] Specific reference is shown in Table 1:

[0128] In Project 1: -Udx≤U d-err ≤Udx,U q-err <-Uqx, then the motor flux is diagnosed There is a fault and the fault in the flux linkage is a negative deviation.

[0129] In Project 2: -Udx≤U d-err ≤Udx,U q-err >Uqx, the motor flux is diagnosed There is a fault and the fault in the flux linkage is a positive deviation.

[0130] Project 3: U d-err >Udx,-Uqx≤U q-err ≤Uqx, it is diagnosed that the q-axis inductance Lq of the motor is faulty, and the fault of the q-axis inductance Lq is a negative deviation.

[0131] Project 4: U d-err <-Udx,-Uqx≤U q-err ≤Uqx, it is diagnosed that the q-axis inductance Lq of the motor is faulty, and the fault of the q-axis inductance Lq is a positive deviation.

[0132] Project 5: U d-err >Udx,U q-err <-Uqx, it is diagnosed that the deflection angle β of the motor is faulty, and the fault of the deflection angle β is a positive deviation.

[0133] Project 6: U d-err <-Udx,U q-err >Uqx, it is diagnosed that the deflection angle β of the motor is faulty, and the fault of the deflection angle β is a negative deviation.

[0134] It should be noted that normally, the motor will not have two or more faults at the same time. That is, the motor will not normally have a flux fault and a q-axis inductance fault at the same time, or in other words, the probability of a flux fault and a q-axis inductance fault occurring at the same time is extremely low or even zero. Therefore, when the d-axis voltage and the q-axis voltage deviate at the same time, the possibility of the motor having a flux fault and a q-axis inductance fault at the same time can be ignored, and it can be diagnosed as a fault in the motor's offset angle.

[0135] In addition, the motor fault diagnosis method described above can be deduced and demonstrated from the d-axis voltage equation and the q-axis voltage equation, that is, the d-axis voltage equation and the q-axis voltage equation can be used to further verify the theoretical basis of the motor fault diagnosis method described above.

[0136] Specifically, the d-axis voltage of the motor conforms to the d-axis voltage equation shown below, for example, the d-axis voltage equation (1) is:

[0137] U d =R s *I d -ω r +L q *I q (1)

[0138] Among them, U d is the d-axis voltage;

[0139] R S is the stator resistance;

[0140] I q is the q-axis current;

[0141] I d is the d-axis current;

[0142] ω r is the rotor angular velocity;

[0143] Lq is the q-axis inductance.

[0144] Based on the d-axis voltage equation, the deviation equation (2) between the actual value and the theoretical value of the d-axis voltage can be further obtained as follows:

[0145] U d-err =R s *(I d1 -I d2 )-ω r *(L q1 *I q1 -L q2 *I q2 ) (2)

[0146] Among them, U d-erris the deviation of the actual value of the d-axis voltage relative to the theoretical value;

[0147] I q1 is the actual value of the q-axis current;

[0148] I q2 is the theoretical value of q-axis current;

[0149] I d1 is the actual value of the d-axis current;

[0150] I d2 is the theoretical value of d-axis current;

[0151] L q1 is the actual value of the q-axis inductance;

[0152] L q2 is the theoretical value of the q-axis inductance.

[0153] And, the q-axis voltage of the motor, for example, conforms to the q-axis voltage equation shown below, and the q-axis voltage equation (3) is, for example:

[0154]

[0155] Among them, U q is the q-axis voltage;

[0156] R S is the stator resistance;

[0157] I q is the q-axis current;

[0158] I d is the d-axis current;

[0159] ω r is the rotor angular velocity;

[0160] is the magnetic link;

[0161] L d is the d-axis inductance.

[0162] Based on the q-axis voltage equation, the deviation equation (4) between the actual value and theoretical value of the q-axis voltage can be further obtained as follows:

[0163]

[0164] Combining the above-mentioned d-axis voltage equation (1) and q-axis voltage equation (3), it can be seen that when the deviation of the actual value of the d-axis voltage relative to the theoretical value is within the allowable deviation range (i.e., |U d-err │≤Udx), from which it can be inferred that the d-axis current I d , q-axis current Iq and q-axis inductance L q There is no abnormality. Based on this, the deviation equation of the q-axis voltage can be simplified as follows:

[0165]

[0166] It should be noted that the inventor of the present application has found through extensive research and experiments that even if there is a deviation in the d-axis inductance Ld, it will not have a significant impact on the q-axis voltage. For example, taking a specific experimental data as an example, when there is a 10% deviation in the d-axis inductance Ld, the impact on the q-axis voltage is only 0.251. However, when there is a 10% deviation in the q-axis inductance Lq, the impact on the d-axis voltage can reach 1.509; when the flux linkage When there is a 10% deviation, the influence on the q-axis voltage can reach 2.218; and when there is a 10% deviation in the rotor offset angle β, it has a greater influence on both the d-axis voltage and the q-axis voltage.

[0167] It can be seen that compared with other diagnostic objects of the motor (such as q-axis inductance, flux linkage and rotor offset angle), the change of d-axis inductance Ld has a very small impact on the q-axis voltage. Therefore, the change of d-axis inductance Ld can be ignored.

[0168] Based on this, the deviation equation (5) of the q-axis voltage can be further simplified to (6), that is:

[0169]

[0170] It can be seen that, combining the d-axis voltage equation (1) and the q-axis voltage equation (3), it can be inferred that: when the deviation value of the d-axis voltage is within the allowable deviation range, the deviation equation of the q-axis voltage can be simplified to: The deviation equation (6).

[0171] At this time, it is verified that, as mentioned above, when the deviation value of the d-axis voltage is within the allowable deviation range (i.e., |U d-err │≤Udx), and the deviation of the q-axis voltage exceeds the allowable deviation range (i.e., │U q-err │>Uqx), the magnetic flux of the motor can be inferred There is a fault. And, according to the q-axis voltage on the flux linkage The deviation equation (6) can further verify that when the deviation value of the q-axis voltage exceeds the allowable deviation range, the flux linkage of the motor On the contrary, when the deviation value of the q-axis voltage exceeds the allowable deviation range in the negative direction, it can be inferred that the magnetic flux of the motor A bit small.

[0172] Further, after diagnosing the flux linkage of the motor After a fault occurs, the flux can be further calculated using the q-axis voltage deviation equation (6) with respect to flux: The deviation of the actual value from the theoretical value. This will be more conducive to the subsequent targeted parameter adjustment of the magnetic flux.

[0173] Continuing to combine the above-mentioned d-axis voltage equation (1) and q-axis voltage equation (3), it can be known that when the deviation of the actual value of the q-axis voltage relative to the theoretical value is within the allowable deviation range (i.e., |U q-err │≤Uqx), from which it can be inferred that the d-axis current I d , q-axis current I q And magnetic links There is no abnormality. Based on this, the deviation equation (2) of the d-axis voltage can be further simplified to:

[0174] U d-err =-ω r *I q (L q1 -L q2 ) (7)

[0175] It can be seen that, combining the d-axis voltage equation (1) and the q-axis voltage equation (3), it can be inferred that: when the deviation value of the q-axis voltage is within the allowable deviation range, the deviation equation of the d-axis voltage can be simplified to the deviation equation of the d-axis voltage with respect to the q-axis inductance Lq (7).

[0176] At this time, it is verified that, as mentioned above, when the deviation value of the q-axis voltage is within the allowable deviation range (i.e., |U q-err │≤Uqx), and the deviation of the d-axis voltage exceeds the allowable deviation range (i.e., │U d-err │>Udx), it can be inferred that the q-axis inductance Lq of the motor is faulty. Moreover, according to the deviation equation (7) of the d-axis voltage with respect to the q-axis inductance Lq, it can be further verified that when the deviation value of the d-axis voltage exceeds the allowable deviation range in the positive direction, the q-axis inductance Lq of the motor is too small; conversely, when the deviation value of the d-axis voltage exceeds the allowable deviation range in the negative direction, it can be inferred that the q-axis inductance Lq of the motor is too small.

[0177] Furthermore, after diagnosing that the q-axis inductance Lq of the motor has a fault, the deviation of the actual value of the q-axis inductance Lq relative to the theoretical value can be further calculated using the deviation equation (7) of the d-axis voltage with respect to the q-axis inductance Lq.

[0178] In addition, the d-axis current Id and the q-axis current Iq have the following relationship with the stator current Is:

[0179]

[0180]

[0181] Based on this, when there is a deviation in the rotor offset angle, for example, the offset angle is Δθ, the d-axis current equation and the q-axis current equation after the offset are as follows:

[0182]

[0183]

[0184] Therefore, by combining the d-axis current equation and the q-axis current equation shown above, the deviation equation (2) of the d-axis voltage can be further converted into:

[0185]

[0186] And, the deviation equation (4) of the q-axis voltage is further converted into:

[0187]

[0188] It should be noted that in the motor, the value of the stator resistance Rs is usually very small (for example, the value of the stator resistance Rs of some motors is only 0.00628 ohms), and under normal operating conditions of the motor, the deviation equation of the q-axis voltage is also mainly determined by the unit term ωr*Lq. Based on this, the unit term of Rs can be ignored.

[0189] Therefore, the deviation equation of the d-axis voltage and the deviation equation of the q-axis voltage can be further simplified to the deviation equation (8) of the d-axis voltage with respect to the offset angle and the deviation equation (9) of the q-axis voltage with respect to the offset angle, namely:

[0190]

[0191]

[0192] It should be recognized that based on the range limitation of the rotor offset angle in the motor, the motor generally operates in the electric working condition, so sinβ and cosβ can be considered to be in the second quadrant. Correspondingly, when there is a deviation in the offset angle, sin(β+△θ) and cos(β+△θ) are also located in the second quadrant.

[0193] Based on this, combined with the deviation equation (8) of the d-axis voltage with respect to the offset angle and the deviation equation (9) of the q-axis voltage with respect to the offset angle, it can be inferred that: when the deviation value of the d-axis voltage exceeds the allowable deviation range (i.e., U d-err>Udx), and the deviation of the q-axis voltage exceeds the allowable deviation range in the negative direction (i.e., U q-err <-Uqx), it is diagnosed that the actual value of the motor's deviation angle is larger than the theoretical value (ie, △θ>0). Also, when the deviation value of the d-axis voltage exceeds the allowable deviation range in the negative direction (ie, U d-err <-Udx), and the deviation of the q-axis voltage exceeds the allowable deviation range in the positive direction, that is, U q-err >Uqx), it is diagnosed that the actual value of the offset angle of the motor is smaller than the theoretical value (ie, Δθ<0).

[0194] Furthermore, after diagnosing that the rotor offset angle of the motor has a fault, the deviation equation (8) of the d-axis voltage with respect to the offset angle or the deviation equation (9) of the q-axis voltage with respect to the offset angle can be used to further calculate the specific deviation of the actual value of the offset angle relative to the theoretical value (i.e., calculate △θ).

[0195] In an optional solution, the motor torque deviation can be combined to further diagnose the diagnostic object in the motor. d-err The deviation between the voltage on the q axis and q-err , so that the fault diagnosis object in the motor can be preliminarily inferred. At this time, the torque deviation T err , further verifying the preliminary inference mentioned above. Alternatively, it can also be understood that when diagnosing the diagnostic object in the motor, the deviation of the d-axis voltage U is used. d-err , q-axis voltage deviation U q-err And the torque deviation T err , to infer that there is a fault in the motor.

[0196] Therefore, the motor fault diagnosis method further includes: obtaining the theoretical value and the actual value of the motor torque, and comparing the theoretical value and the actual value of the motor torque to obtain the torque deviation value T err .

[0197] Among them, when the d-axis voltage deviation value U d-err and torque deviation T err The deviation exceeds the permissible deviation range in opposite directions (i.e., U d-err >Udx,T err <-Tx; or, U d-err <-Udx,T err >Tx); and the deviation value of q-axis voltage U q-err If the allowable deviation range is not exceeded, it is diagnosed that the q-axis inductance Lq of the motor is faulty.

[0198] Furthermore, when the q-axis inductance Lq of the motor is diagnosed to be faulty, the torque deviation value T err The deviation direction of the q-axis inductance Lq is further inferred. Specifically, if the torque deviation value T err Negative deviation exceeds the allowable deviation range [-Tx, Tx] (i.e., T err <-Tx), it is diagnosed that the actual value of the q-axis inductance Lq of the motor is smaller than the theoretical value; and if the torque deviation value T err The positive direction exceeds the allowable deviation range [-Tx, Tx] (i.e., T err >Tx), it is diagnosed that the actual value of the q-axis inductance Lq of the motor is larger than the theoretical value.

[0199] And, when the deviation value of q-axis voltage U q-err and torque deviation T err All exceed the allowable deviation range in the same direction (i.e., U q-err >Uqx,T err >Tx; or, U q-err <-Udx,T err <-Tx), and the deviation value of the d-axis voltage does not exceed the allowable deviation range, it is diagnosed as the flux linkage of the motor There is a malfunction.

[0200] Furthermore, after diagnosing the motor flux In the event of a fault, the torque deviation value T can also be used err Further inference of magnetic linkage Specifically, if the torque deviation value T err Negative deviation exceeds the allowable deviation range [-Tx, Tx] (i.e., T err <-Tx), it is diagnosed as the flux linkage of the motor The actual value of is smaller than the theoretical value; and if the torque deviation value T err The positive direction exceeds the allowable deviation range [-Tx, Tx] (i.e., T err >Tx), it is diagnosed that the actual value of the magnetic flux of the motor is larger than the theoretical value.

[0201] In addition, when the q-axis voltage deviation value U q-err and the deviation value U of the d-axis voltage d-err The torque deviation value T err If the negative direction exceeds the allowable deviation range, it is diagnosed that the offset angle β of the motor is faulty.

[0202] Combining the deviation direction of the d-axis voltage, the deviation direction of the q-axis voltage, and the deviation direction of the torque as described above, it is inferred that the fault diagnosis object in the motor exists, which can be specifically summarized as shown in Table 2.

[0203]

[0204] Table 2

[0205] Furthermore, the torque of the motor, for example, conforms to the torque equation shown below:

[0206]

[0207] Where, T is the torque;

[0208] P is the number of motor pole pairs;

[0209] I q is the q-axis current;

[0210] I d is the d-axis current;

[0211] is the magnetic link;

[0212] L d is the d-axis inductance;

[0213] L q is the q-axis inductance.

[0214] Furthermore, after initially inferring that the motor has a faulty diagnostic object, the torque deviation equation can be further derived based on the torque equation (10).

[0215] Specifically, when the deviation of the actual value of the d-axis voltage relative to the theoretical value is within the allowable deviation range (i.e., |U d-err │≤Udx), from which it can be inferred that the d-axis current I d , q-axis current I q and q-axis inductance L q There is no abnormality. Therefore, the deviation equation of torque with respect to magnetic flux can be obtained as:

[0216]

[0217] It can be seen that according to the torque deviation equation (11) shown above, it can be further verified that when the d-axis voltage deviation value U d-err If the motor flux is within the allowable deviation range, the motor flux is faulty. After a fault occurs, the flux can be further calculated using the torque deviation equation (11) The deviation of the actual value from the theoretical value.

[0218] And, when the deviation of the actual value of the q-axis voltage relative to the theoretical value is within the allowable deviation range (i.e., |U q-err │≤Uqx), from which it can be diagnosed that the d-axis current I d , q-axis current I q And magnetic links There is no abnormality. Based on this, the deviation equation of torque with respect to q-axis inductance can be obtained as:

[0219]

[0220] Therefore, according to the torque deviation equation (12) about the q-axis inductance shown above, it can be further verified that: when the q-axis voltage deviation value U q-err If the value is within the allowable deviation range, the q-axis inductance Lq of the motor is faulty. After diagnosing that the q-axis inductance Lq of the motor is faulty, the deviation of the actual value of the q-axis inductance Lq relative to the theoretical value can be further calculated using the torque deviation equation (12) with respect to the q-axis inductance Lq.

[0221] In addition, when there is a deviation in the rotor offset angle, according to the d-axis current equation, the q-axis current equation and the torque equation (10), the torque equation with respect to the offset angle can be further obtained as follows:

[0222]

[0223] It should be noted that the offset angle of the motor is usually obtained by making the above torque formula have a maximum value and directly taking the derivative of the above formula equal to 0. At this time, the angle β at the maximum torque value can be calculated, and the angle β obtained is the offset angle β of the motor.

[0224] Therefore, when the offset angle deviation occurs, the corresponding torque is definitely not the maximum torque value. That is, no matter whether the offset angle increases or decreases, the corresponding torque value is smaller.

[0225] In summary, in the motor fault diagnosis method provided in this embodiment, by using the deviation value of the d-axis voltage and the deviation value of the q-axis voltage, it is possible to directly diagnose whether the motor has a fault.

[0226] Furthermore, the deviation direction of the d-axis voltage and the deviation direction of the q-axis voltage can be combined to infer the faulty diagnostic object in the motor. In other words, it can be inferred whether the diagnostic object in the motor (the diagnostic object includes magnetic flux, q-axis inductance, and offset angle) is faulty based on the deviation direction of the d-axis voltage and the deviation direction of the q-axis voltage.

[0227] Furthermore, after preliminarily diagnosing that a faulty diagnostic object exists in the motor, the deviation direction of the parameter value of the faulty diagnostic object can be further inferred, so as to facilitate targeted adjustment of the faulty diagnostic object.

[0228] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A method for diagnosing motor faults, characterized in that: include: Acquiring a theoretical value of a d-axis voltage and a theoretical value of a q-axis voltage of the motor, and detecting an actual value of the d-axis voltage and an actual value of the q-axis voltage of the motor; Comparing an actual value of a d-axis voltage of the motor with a theoretical value to obtain a deviation value of the d-axis voltage, and comparing an actual value of a q-axis voltage with a theoretical value to obtain a deviation value of the q-axis voltage; as well as, Based on the deviation value of the d-axis voltage and the deviation value of the q-axis voltage of the motor, diagnose whether the motor is faulty, including: when the deviation value of the d-axis voltage exceeds the allowable deviation range, and the deviation value of the q-axis voltage is within the allowable deviation range, it is diagnosed that the q-axis inductance of the motor is faulty; when the deviation value of the d-axis voltage is within the allowable deviation range, and the deviation value of the q-axis voltage exceeds the allowable deviation range, it is diagnosed that the magnetic flux of the motor is faulty; when the deviation value of the d-axis voltage and the deviation value of the q-axis voltage both exceed the allowable deviation range, it is diagnosed that the offset angle of the motor is faulty.

2. The motor fault diagnosis method according to claim 1, characterized in that: The method for diagnosing that the q-axis inductance of the motor is faulty also includes: When the deviation value of the d-axis voltage exceeds the allowable deviation range in the positive direction, it is diagnosed that the actual value of the q-axis inductance of the motor is smaller than the theoretical value; When the deviation value of the d-axis voltage exceeds the allowable deviation range in the negative direction, it is diagnosed that the actual value of the q-axis inductance of the motor is larger than the theoretical value.

3. The motor fault diagnosis method according to claim 1, characterized in that: The d-axis voltage of the motor conforms to the d-axis voltage equation shown below: U d =R s *I d -ω r *L q *I q ; Among them, U d is the d-axis voltage; R S is the stator resistance; I q is the q-axis current; I d is the d-axis current; ω r is the rotor angular velocity; Lq is the q-axis inductance.

4. The motor fault diagnosis method according to claim 3, characterized in that: When diagnosing that the q-axis inductance of the motor is faulty, the diagnostic method further includes: According to the d-axis voltage equation, a deviation equation of the d-axis voltage with respect to the q-axis inductance is obtained, and the deviation of the actual value of the q-axis inductance relative to the theoretical value is calculated using the deviation equation of the d-axis voltage with respect to the q-axis inductance; wherein the deviation equation of the d-axis voltage with respect to the q-axis inductance is as follows; And d-err =-ω r *I q (L q1 -L q2 ) Among them, U d-err is the deviation of the actual value of the d-axis voltage from the theoretical value; L q1 is the actual value of the q-axis inductance; L q2 is the theoretical value of the q-axis inductance.

5. The motor fault diagnosis method according to claim 1, characterized in that: The method for diagnosing a magnetic flux fault of the motor further includes: When the deviation value of the q-axis voltage exceeds the allowable deviation range in the positive direction, it is diagnosed that the actual value of the magnetic flux of the motor is larger than the theoretical value; When the deviation value of the q-axis voltage exceeds the allowable deviation range in the negative direction, it is diagnosed that the actual value of the magnetic flux of the motor is smaller than the theoretical value.

6. The motor fault diagnosis method according to claim 1, characterized in that: The q-axis voltage of the motor conforms to the q-axis voltage equation shown below: Among them, U q is the q-axis voltage; R S is the stator resistance; I q is the q-axis current; I d is the d-axis current; ω r is the rotor angular velocity; is the magnetic link; Ld is the d-axis inductance.

7. The motor fault diagnosis method according to claim 6, characterized in that: When it is diagnosed that the magnetic flux of the motor is faulty, the diagnostic method further comprises: According to the q-axis voltage equation, a deviation equation of the q-axis voltage with respect to the flux is obtained, and the deviation of the actual value of the flux relative to the theoretical value is calculated using the deviation equation of the q-axis voltage with respect to the flux; wherein the deviation equation of the q-axis voltage with respect to the flux is as follows: Among them, U q-err is the deviation of the actual value of the q-axis voltage from the theoretical value; is the actual value of magnetic linkage; is the theoretical value of magnetic flux.

8. The motor fault diagnosis method according to claim 1, characterized in that: The method for diagnosing that the offset angle of the motor is faulty also includes: When the deviation value of the d-axis voltage exceeds the allowable deviation range in the positive direction and the deviation value of the q-axis voltage exceeds the allowable deviation range in the negative direction, it is diagnosed that the actual value of the offset angle of the motor is larger than the theoretical value; When the deviation value of the d-axis voltage exceeds the allowable deviation range in the negative direction and the deviation value of the q-axis voltage exceeds the allowable deviation range in the positive direction, it is diagnosed that the actual value of the offset angle of the motor is smaller than the theoretical value.

9. The motor fault diagnosis method according to claim 1, characterized in that: When diagnosing that the magnetic flux of the motor is faulty, the diagnostic method further comprises: calculating a deviation of an actual value of the offset angle relative to a theoretical value according to a deviation equation of a d-axis voltage with respect to the offset angle and a deviation equation of a q-axis voltage with respect to the offset angle; The deviation equation of the d-axis voltage with respect to the offset angle is as follows: And, the deviation equation of the q-axis voltage with respect to the offset angle is as follows: Among them, U d-err is the deviation of the actual value of the d-axis voltage from the theoretical value; U q-err is the deviation of the actual value of the q-axis voltage from the theoretical value; I S is the stator current; ω r is the rotor angular velocity; Ld is the d-axis inductance; Lq is the q-axis inductance; β is the theoretical value of the deviation angle; Δθ is the deviation of the actual value of the offset angle relative to the theoretical value, and both sinβ and cosβ are located in the second quadrant.

10. The motor fault diagnosis method according to claim 1, characterized in that: Methods for diagnosing whether the motor is faulty also include: Obtaining a theoretical value and an actual value of the torque of the motor, and comparing the theoretical value and the actual value of the torque of the motor to obtain a torque deviation value; and, When the deviation value of the d-axis voltage and the deviation value of the torque exceed the allowable deviation range in opposite directions, and the deviation value of the q-axis voltage does not exceed the allowable deviation range, it is diagnosed that the q-axis inductance of the motor is faulty; When the deviation value of the q-axis voltage and the deviation value of the torque both exceed the allowable deviation range in the same direction, and the deviation value of the d-axis voltage does not exceed the allowable deviation range, it is diagnosed that the magnetic flux of the motor is faulty; When the deviation value of the q-axis voltage and the deviation value of the d-axis voltage exceed the allowable deviation range in opposite directions, and the deviation value of the torque exceeds the allowable deviation range in the negative direction, it is diagnosed that the offset angle of the motor is faulty.

11. The motor fault diagnosis method according to claim 10, characterized in that: When it is diagnosed that the q-axis inductance of the motor is faulty, the method further includes: When the torque deviation value exceeds the allowable deviation range in the negative direction, it is diagnosed that the actual value of the q-axis inductance of the motor is smaller than the theoretical value; When the deviation value of the torque exceeds the allowable deviation range in the positive direction, it is diagnosed that the actual value of the q-axis inductance of the motor is larger than the theoretical value.

12. The motor fault diagnosis method according to claim 10, characterized in that: When it is diagnosed that the magnetic flux of the motor is faulty, the method further includes: When the torque deviation value exceeds the allowable deviation range in the negative direction, it is diagnosed that the actual value of the q-axis inductance of the motor is smaller than the theoretical value; When the deviation value of the torque exceeds the allowable deviation range in the positive direction, it is diagnosed that the actual value of the q-axis inductance of the motor is larger than the theoretical value.

13. The motor fault diagnosis method according to claim 10, characterized in that: The torque of the motor complies with the torque equation shown below: Among them, T r is the torque; P is the number of motor pole pairs I q is the q-axis current; I d is the d-axis current, and the d-axis current I d and q-axis current I q is the opposite vector; is the magnetic link; L d is the d-axis inductance; L q is the q-axis inductance.

14. The motor fault diagnosis method according to claim 13, characterized in that: When diagnosing that the q-axis inductance of the motor is faulty, the diagnostic method further includes: According to the torque equation, a deviation equation of the torque with respect to the q-axis inductance is obtained, and the deviation of the actual value of the q-axis inductance relative to the theoretical value is calculated using the deviation equation of the torque with respect to the q-axis inductance; wherein the deviation equation of the torque with respect to the q-axis inductance is as follows: Among them, T err It is the deviation of the actual value of torque from the theoretical value; Lq1 is the actual value of the q-axis inductance; Lq2 is the theoretical value of the q-axis inductance.

15. The motor fault diagnosis method according to claim 13, characterized in that: When it is diagnosed that the magnetic flux of the motor is faulty, the diagnostic method further comprises: According to the torque equation, a deviation equation of the torque with respect to the flux is obtained, and the deviation of the actual value of the flux relative to the theoretical value is calculated using the deviation equation of the torque with respect to the flux; wherein the deviation equation of the torque with respect to the flux is as follows: Among them, T err It is the deviation of the actual value of torque from the theoretical value; is the actual value of magnetic linkage; is the theoretical value of magnetic flux.

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