A three-phase permanent magnet synchronous motor fault diagnosis method and diagnosis system

Abstract

The application discloses a kind of three-phase permanent magnet synchronous motor fault diagnosis method and diagnosis system, three-phase permanent magnet synchronous motor includes star connection three-phase winding, rotor, rotor position sensor and at least two current sensors, each current sensor is located in two phase windings in three-phase winding, rotor position sensor is located on the rotor, method includes: obtaining the current value of two phase windings detected by each current sensor, and the rotor position angle detected by the rotor position sensor;By applying preset voltage to three-phase winding, and according to the current value of two phase windings and the rotor position angle, determine whether each current sensor is faulty, and whether each phase winding is faulty. Using the above method, the current sensor fault and / or winding fault are quickly and accurately determined, and the diagnosis efficiency is improved.

Description

Technical Field

[0001] This invention relates to the technical field of motor fault diagnosis, and in particular to a fault diagnosis method and system for a three-phase permanent magnet synchronous motor. Background Technology

[0002] In recent years, benefiting from the development of my country's new energy industry, the installed capacity of electric drive systems has continued to reach new highs. This has intensified competition in the field while also promoting technological progress. The reliability and safety of new energy vehicles are key concerns for many automakers and consumers, making early identification of system faults extremely important. In automotive electric drive systems, resolvers are typically used to monitor the motor position angle in real time, and Hall effect current sensors are used to detect two-phase currents. The remaining phase current value is determined by calculating the sum of the three-phase currents to be zero. Therefore, open-circuit faults in the motor windings, resolver faults, and current sensor faults can all directly lead to system abnormalities. During operation, resolvers typically provide feedback on their current operating status, which can be used to determine if a resolver fault has occurred. In addition to position and current sensors, electric drive systems usually have two or more temperature sensors to monitor the temperature of the motor and power devices. A temperature sensor malfunction does not directly cause an abnormality in the electric drive system.

[0003] Existing methods for diagnosing winding and sensor faults typically utilize algorithmic models and determine open-circuit faults based on the current trajectory in a stationary coordinate system. These methods all have limitations in practical applications. The algorithms rely on the sensors operating normally and require the collection of a large amount of data on current movement to form the algorithm, resulting in a significant workload. Furthermore, the initial data collection phase consumes substantial memory, potentially leading to insufficient chip storage and requiring trade-offs in system software variables, ultimately hindering the system's ability to accurately and quickly diagnose faults. Summary of the Invention

[0004] This invention provides a fault diagnosis method and system for a three-phase permanent magnet synchronous motor, which can quickly and accurately determine whether the current sensor and / or rotor position sensor is faulty based on the winding current value detected by two current sensors and the rotor position angle detected by the rotor position sensor, achieving rapid location and with simple logic.

[0005] In a first aspect, the present invention provides a fault diagnosis method for a three-phase permanent magnet synchronous motor. The three-phase permanent magnet synchronous motor includes a star-connected three-phase winding, a rotor, a rotor position sensor, and at least two current sensors. Each current sensor is located on two of the three-phase windings, and the rotor position sensor is located on the rotor. The method includes:

[0006] Acquire the current values ​​of two phase windings detected by each current sensor, and the rotor position angle detected by the rotor position sensor.

[0007] By applying a preset voltage to the three-phase windings and determining whether each current sensor is faulty and whether each phase winding is faulty based on the current value of two phase windings and the rotor position angle.

[0008] Optionally, before determining whether each current sensor is faulty and whether each phase winding is faulty by applying a preset voltage to the three-phase windings and based on the current values ​​of two phase windings and the rotor position angle, the method further includes:

[0009] It was confirmed that none of the current sensors were short-circuited.

[0010] Optionally, determining that no short circuit has occurred in any of the current sensors includes:

[0011] If all current values ​​are determined to be 0, then the current sensor is confirmed to be free from short circuit.

[0012] Optionally, before determining that no short circuit has occurred in any of the current sensors, the process also includes:

[0013] It was confirmed that the rotor position sensor was not malfunctioning.

[0014] Optionally, by applying a preset voltage to the three-phase windings, and based on the current values ​​of two phase windings and the rotor position angle, it can be determined whether each current sensor is faulty, and whether each phase winding is faulty, including:

[0015] By applying a first preset voltage to the three-phase windings, the current sensor and the rotor position angle of two phase windings are used to determine whether each current sensor is faulty and whether each phase winding is faulty.

[0016] When it is not determined whether each current sensor or each phase winding is faulty, a second preset voltage is applied to the three-phase windings, and the faultiness of each current sensor and each phase winding is determined based on the current value of two phase windings and the rotor position angle; the first preset voltage and the second preset voltage are different.

[0017] Optionally, the three-phase winding includes phase A, phase B, and phase C; the first preset voltage includes U. A =U1,U B =-1 / 2U1,U C = 1 / 2U1; U1 is the rated voltage of one phase winding;

[0018] By applying a first preset voltage to the three-phase windings, and based on the current values ​​of two phase windings and the rotor position angle, it is determined whether each phase winding is faulty, including:

[0019] By applying a first preset voltage to the three-phase windings, when the rotor position angle is 0 and at least one current value is 0, it is determined that at least one current sensor is faulty and each phase winding is normal.

[0020] When the rotor position angle is not 0 and all current values ​​are not 0, it is determined that at least one phase winding is faulty, and all current sensors are normal.

[0021] When the rotor position angle is not 0 and at least one current value is 0, at least one phase winding fault and at least one current sensor fault are determined.

[0022] When the rotor position angle is not the preset angle and all current values ​​are 0, it is impossible to determine whether each current sensor is faulty or whether each phase winding is faulty.

[0023] Optionally, the current sensor includes a first current sensor and a second current sensor, with the first current sensor located on the A-phase winding and the second current sensor located on the B-phase winding.

[0024] When the rotor position angle is 0 and at least one current value is 0, at least one current sensor fault is determined, including:

[0025] When the rotor position angle is 0, the first current value detected by the first current sensor is 0, and the second current value detected by the second current sensor is not 0, the first current sensor is determined to be faulty.

[0026] When the rotor position angle is 0, the first current value detected by the first current sensor is not 0, and the second current value detected by the second current sensor is 0, it is determined that the second current sensor is faulty.

[0027] When the rotor position angle is 0, and the first current value detected by the first current sensor and the second current value detected by the second current sensor are both 0, it is determined that both the first current sensor and the second current sensor are faulty.

[0028] Optionally, the current sensor includes a first current sensor and a second current sensor, with the first current sensor located on the A-phase winding and the second current sensor located on the B-phase winding.

[0029] When the rotor position angle is not 0 and at least one current value is 0, at least one phase winding fault and at least one current sensor fault are determined, including:

[0030] When the rotor position angle is -30°, the first current value detected by the first current sensor is 0, and the second current value detected by the second current sensor is -I2, it is determined that the C-phase winding is faulty and the first current sensor is faulty; I2 is the current in the B-phase winding and the C-phase winding when one of the phase windings is faulty.

[0031] When the rotor position angle is -30°, the first current value detected by the first current sensor is I2, and the second current value detected by the second current sensor is 0, it is determined that the C-phase winding is faulty and the second current sensor is faulty.

[0032] When the rotor position angle is -30°, and the first current value detected by the first current sensor and the second current value detected by the second current sensor are both 0, it is determined that the C-phase winding is faulty, and the first current sensor and the second current sensor are also faulty.

[0033] When the rotor position angle is 30°, the first current value detected by the first current sensor is I2, and the second current value detected by the second current sensor is 0, it is determined that the B-phase winding is faulty, and the second current sensor is either normal or faulty.

[0034] When the rotor position angle is 30°, and the first current value detected by the first current sensor and the second current value detected by the second current sensor are both 0, it is determined that the B-phase winding is faulty, the first current sensor is faulty, or both the first current sensor and the second current sensor are faulty.

[0035] Optionally, the three-phase winding includes an A-phase winding, a B-phase winding, and a C-phase winding; the current sensor includes a first current sensor and a second current sensor, the first current sensor being located on the A-phase winding and the second current sensor being located on the B-phase winding; the second preset voltage includes U. A =-1 / 2U1,U B =U1,U C = -1 / 2U1; U1 is the rated voltage of one phase winding;

[0036] By applying a second preset voltage to the three-phase windings, and based on the current values ​​of two phase windings and the rotor position angle, it is determined whether each current sensor is faulty, and whether each phase winding is faulty, including:

[0037] By applying a second preset voltage to the three-phase windings, when the rotor position angle is 90°, the first current value detected by the first current sensor is 0, and the second current value detected by the second current sensor is I2, it is determined that the A-phase winding is faulty, and the first current sensor is normal or faulty; I2 is the current in the B-phase winding and the C-phase winding when one of the phase windings is faulty.

[0038] When the rotor position angle is 90°, and the first current value detected by the first current sensor and the second current value detected by the second current sensor are both 0, it is determined that the A-phase winding is faulty, the second current sensor is faulty, or both the first current sensor and the second current sensor are faulty.

[0039] When the rotor position angle is any other angle, and the first current value detected by the first current sensor and the second current value detected by the second current sensor are both 0, at least two phase winding faults are determined. The other angles are degrees excluding 0, ±30° and 90°.

[0040] In a second aspect, the present invention provides a fault diagnosis system for a three-phase permanent magnet synchronous motor, comprising a star-connected three-phase winding, a rotor, a rotor position sensor, at least two current sensors, and a controller.

[0041] Each current sensor is located on two of the three-phase windings to obtain the current value of those two phase windings.

[0042] The rotor position sensor is located on the rotor and is used to obtain the rotor position angle;

[0043] The controller is electrically connected to the rotor position sensor and each current sensor to obtain the current values ​​and rotor position angle; it applies a preset voltage to the three-phase windings and determines whether each current sensor and each phase winding is faulty based on the current values ​​of two phase windings and the rotor position angle.

[0044] The technical solution of this invention obtains the current values ​​of two phase windings detected by each current sensor and the rotor position angle detected by the rotor position sensor; by applying a preset voltage to the three-phase windings, and based on the current values ​​of two phase windings and the rotor position angle, it determines whether each current sensor and each phase winding is faulty. Using this method, based on the current values ​​of the windings detected by the two current sensors and the rotor position angle detected by the rotor position sensor, it quickly and accurately determines whether the current sensor and / or rotor position sensor is faulty, achieving rapid localization with simple logic.

[0045] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 A flowchart of a fault diagnosis method for a three-phase permanent magnet synchronous motor provided in an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of the structure of a three-phase permanent magnet synchronous motor provided in an embodiment of the present invention;

[0049] Figure 3 This is a schematic diagram showing the relationship between the axis of the winding and the rotor position of a three-phase permanent magnet synchronous motor, provided as an embodiment of the present invention.

[0050] Figure 4 A flowchart of another fault diagnosis method for a three-phase permanent magnet synchronous motor provided in an embodiment of the present invention;

[0051] Figure 5 A flowchart of another method for diagnosing faults in a three-phase permanent magnet synchronous motor provided in an embodiment of the present invention;

[0052] Figure 6 An equivalent circuit diagram for a B-phase winding fault provided in an embodiment of the present invention;

[0053] Figure 7 for Figure 6 A schematic diagram of the combined current along the axes of the corresponding three-phase windings. Detailed Implementation

[0054] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0055] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0056] In one embodiment, Figure 1 This is a flowchart of a fault diagnosis method for a three-phase permanent magnet synchronous motor provided by an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of a three-phase permanent magnet synchronous motor provided in an embodiment of the present invention. Figure 3This is a schematic diagram illustrating the relationship between the axis of the winding and the rotor position of a three-phase permanent magnet synchronous motor according to an embodiment of the present invention. This embodiment is applicable to quickly and accurately determining whether a fault has occurred in the winding and current sensor of a three-phase permanent magnet synchronous motor. This method can be executed by a three-phase permanent magnet synchronous motor fault diagnosis system. The three-phase permanent magnet synchronous motor includes a star-connected three-phase winding, a rotor (not shown in the figure), a rotor position sensor (not shown in the figure), and at least two current sensors 1. Each current sensor 1 is located on two of the three-phase windings, and the rotor position sensor is located on the rotor. Figures 1 to 3 As shown, the three-phase winding can be an A-phase winding, a B-phase winding, and a C-phase winding. The method includes:

[0057] S110: Obtain the current values ​​of two phase windings detected by each current sensor, and the rotor position angle detected by the rotor position sensor.

[0058] The current sensor is mounted on the winding and is used to detect the current value in the corresponding winding after power-on. The rotor position sensor is located on the rotor and is used to detect the corresponding rotor position angle after power-on. (Reference) Figure 3 The three-phase windings are connected in a star configuration, meaning the angle between each phase winding is 120°. Under normal circumstances, the initial position of the rotor coincides with the axis of phase A winding. Therefore, after power-on, the rotor position sensor detects the rotor position angle as follows: Figure 3 The angle θ1 in the equation is the angle between the axis of phase A winding and the axis of phase B winding.

[0059] S120. By applying a preset voltage to the three-phase windings and determining whether each current sensor is faulty and whether each phase winding is faulty based on the current value of two phase windings and the rotor position angle.

[0060] The preset voltage is Figure 2 Middle U A U B and U C This refers to the voltage values ​​applied to the A-phase winding, B-phase winding, and C-phase winding respectively. The voltage values ​​can be determined based on the rated voltage of the A-phase winding, the voltage values ​​of the B-phase winding and C-phase winding, the rated voltage of the B-phase winding and A-phase winding and C-phase winding, or the rated voltage of the C-phase winding and A-phase winding and B-phase winding. The specific determination can be made according to the actual situation, and there is no restriction here.

[0061] It should be noted that the purpose of applying a preset voltage to the three-phase windings in this embodiment is to determine, under the influence of the voltage, the correct current value and rotor position angle that the current sensor should output for the corresponding phase winding, as well as the correct current value and rotor position angle. In other words, a certain preset correspondence exists under this preset voltage: the correspondence between current values ​​and preset current values, and the relationship between rotor position angles and preset rotor position angles. Thus, the actual current values ​​of two phase windings can be compared with the preset current values; if they are different, it indicates a fault in the current sensor. Similarly, the actual rotor position angle can be compared with the preset rotor position angle; if they are different, it indicates a fault in at least one phase winding. Using this method, it is possible to quickly and accurately determine whether each current sensor and each winding is faulty, enabling accurate repair. Furthermore, if the acquired current value and rotor position angle do not fall within the aforementioned preset relationships, it is necessary to disassemble the motor for inspection to determine the location and cause of the fault.

[0062] The technical solution of this invention obtains the current values ​​of two phase windings detected by each current sensor and the rotor position angle detected by the rotor position sensor; by applying a preset voltage to the three-phase windings, and based on the current values ​​of two phase windings and the rotor position angle, it determines whether each current sensor and each phase winding is faulty. Using this method, based on the current values ​​of the windings detected by the two current sensors and the rotor position angle detected by the rotor position sensor, it quickly and accurately determines whether the current sensor and / or rotor position sensor is faulty, achieving rapid localization with simple logic.

[0063] In another specific embodiment, Figure 4 A flowchart of another three-phase permanent magnet synchronous motor fault diagnosis method provided in an embodiment of the present invention is shown below. Figure 4 As shown, the method includes:

[0064] S210. Obtain the current values ​​of two phase windings detected by each current sensor, and the rotor position angle detected by the rotor position sensor.

[0065] S220, Confirmed that the rotor position sensor is not faulty.

[0066] Specifically, after obtaining the rotor position angle detected by the rotor position sensor, it is necessary to determine whether the rotor position angle is normal, that is, to determine whether the rotor position sensor is faulty. If no fault has occurred, the detected rotor position angle can be used to determine the faults of each phase winding and current sensor. If a fault has occurred, the rotor position sensor needs to be repaired. After confirming that there is no fault, the subsequent steps can be carried out.

[0067] It should be noted that the rotor position sensor is connected to the fault detection structure during operation. The fault detection structure detects the operating status of the rotor position sensor and generates a corresponding fault detection result. Therefore, the fault detection result detected by the fault detection structure and the rotor position angle detected by the rotor position sensor can be obtained simultaneously. The fault detection result detected by the fault detection structure can be displayed as a high level or a low level. A high level indicates that the rotor position sensor is not faulty, and a low level indicates that the rotor position sensor is faulty; or, a low level indicates that the rotor position sensor is not faulty, and a high level indicates that the rotor position sensor is faulty. The specific method can be determined according to the actual situation and is not limited here. In addition, the output of the fault detection result can be not only the above-mentioned level signal output, but also a direct output of the fault result, or other signal forms that can quickly determine the fault status. This embodiment does not limit this. Therefore, based on the received fault detection result, the fault status of the rotor position sensor can be quickly determined. When a fault is determined to be caused by the rotor position sensor, a corresponding fault code can be output, or it can be directly displayed on the display structure to indicate the rotor position sensor fault. Only after confirming that the rotor position sensor is not faulty should subsequent fault diagnosis be performed to avoid misjudgment and improve accuracy.

[0068] S230. Confirm that none of the current sensors are short-circuited.

[0069] This step can be further refined as follows: when all current values ​​are determined to be 0, it is determined that the current sensor has not been short-circuited.

[0070] Specifically, after confirming that the rotor position sensor is not faulty, it is also necessary to confirm that the current sensor is not short-circuited to ensure that the current value detected by the current sensor is valid. In this embodiment, based on the current values ​​of two phase windings detected by the two current sensors, if both current values ​​are 0, it indicates that neither current sensor is short-circuited to ground or power supply. If at least one current value is not 0, it can be determined that the current sensor corresponding to the non-zero value is short-circuited. A corresponding fault code will be output or displayed directly to indicate the short circuit of the corresponding current sensor, facilitating troubleshooting.

[0071] S240. By applying a first preset voltage to the three-phase windings, determine whether each current sensor is faulty and whether each phase winding is faulty based on the current value of two phase windings and the rotor position angle.

[0072] Specifically, after confirming that no short circuits have occurred in the current sensors, the fault judgment logic for the current sensors and windings is then implemented. At this point, a first preset voltage is applied to the three-phase windings, which can be understood as a primary pressure application. Under this first preset voltage, the current values ​​and rotor position angles can be compared with corresponding preset relationships. When it is determined that each current value and rotor position angle falls within the preset relationships, the fault condition of each current sensor and each phase winding can be determined as the fault condition corresponding to that phenomenon. For example, when the first preset voltage is applied, the preset relationships can include 11 cases, including the fault causes corresponding to the current values ​​output by two current sensors and the acquired rotor position angles. Of these 11 cases, one cannot accurately pinpoint the fault cause and requires a secondary pressure application judgment; the other 10 cases each correspond to a single fault cause. Therefore, after obtaining the current values ​​and rotor position angles of two phase windings, it is determined which of the 10 cases the two current values ​​and rotor position angles belong to, i.e., whether the values ​​are the same. When all three values ​​are the same, it indicates that the fault diagnosis result at this time is the fault cause corresponding to that case, and a secondary pressure application judgment is not required. If it is determined that each current value and rotor position angle belong to another case, then multiple fault causes can be identified under the first preset voltage. If the fault cannot be accurately located, further judgment is needed in this case to locate the fault cause.

[0073] S250. When it is not determined whether each current sensor or each phase winding is faulty, a second preset voltage is applied to the three-phase windings, and the faultiness of each current sensor and each phase winding is determined based on the current value of two phase windings and the rotor position angle.

[0074] The first preset voltage and the second preset voltage are different.

[0075] Specifically, after applying the first preset voltage, if the acquired current values ​​and rotor position angles cannot accurately determine whether each current sensor or each phase winding is faulty according to the aforementioned preset correspondence, a second preset voltage can be applied to the three-phase windings. This second preset voltage differs from the first preset voltage. After applying the second preset voltage, the current values ​​and rotor position angles are re-determined within the preset correspondence under the second preset voltage, based on the initially determined fault causes. This allows for precise fault location. For example, if it is determined that the fault cause cannot be located under the first preset voltage due to the current values ​​and rotor position angles, the second preset voltage is applied to the three-phase windings. Under the second preset voltage, the fault condition is determined based on the current values ​​output by the two current sensors and the acquired rotor position angles. If both current values ​​and rotor position angles match one of these conditions, the fault condition of the current sensors and windings is determined to be the fault in the corresponding fault cause under that condition. In addition, if the current values ​​and rotor position angles do not fall under all of the above conditions, the cause of the fault cannot be located, and disassembly and inspection are required to locate the cause of the fault.

[0076] The technical solution of this invention determines whether the rotor position sensor and each current sensor are faulty by applying a first preset voltage to the three-phase windings and determining whether each current sensor and each phase winding is faulty based on the current values ​​of two phase windings and the rotor position angle. If the faults of the current sensors and phase windings are not determined, a second preset voltage is applied to the three-phase windings, and the faults of each current sensor and each phase winding are determined based on the current values ​​of two phase windings and the rotor position angle. The first preset voltage and the second preset voltage are different. Using this method, when the rotor position sensor is determined to be fault-free and the current sensors are not short-circuited, the fault conditions of the current sensors and each phase winding are accurately and quickly located through one or two diagnostic steps. The logic is simple, easy to operate, and low in cost.

[0077] In another specific embodiment, Figure 5 The flowchart illustrates another method for diagnosing faults in a three-phase permanent magnet synchronous motor, as provided in an embodiment of the present invention. Figure 6 This invention provides an equivalent circuit diagram for a fault in phase B winding. Figure 7 for Figure 6 A schematic diagram of the combined current along the axes of the corresponding three-phase windings, wherein the three-phase windings include phase A winding, phase B winding, and phase C winding, and current sensor 1 includes a first current sensor 11 and a second current sensor 12, with the first current sensor 11 located on the phase A winding and the second current sensor 12 located on the phase B winding; Reference Figure 2 , Figures 5 to 7 As shown, the method includes:

[0078] S310: Obtain the current values ​​of two phase windings detected by each current sensor, and the rotor position angle detected by the rotor position sensor.

[0079] S320, confirming that the rotor position sensor is not faulty.

[0080] S330. Confirm that none of the current sensors are short-circuited.

[0081] S340. By applying a first preset voltage to the three-phase windings, when the rotor position angle is 0 and at least one current value is 0, it is determined that at least one current sensor is faulty and each phase winding is normal.

[0082] This step can be further broken down as follows: when the rotor position angle is 0, the first current value detected by the first current sensor is 0, and the second current value detected by the second current sensor is not 0, the first current sensor is determined to be faulty; when the rotor position angle is 0, the first current value detected by the first current sensor is not 0, and the second current value detected by the second current sensor is 0, the second current sensor is determined to be faulty; when the rotor position angle is 0, and both the first current value detected by the first current sensor and the second current value detected by the second current sensor are 0, both the first current sensor and the second current sensor are determined to be faulty.

[0083] Specifically, when making a judgment on each current sensor and each phase winding, a first preset voltage is applied to each phase winding, wherein the first preset voltage includes U A =U1,U B =-1 / 2U1,U C=1 / 2U1; U1 is the rated voltage of one phase winding; for simplicity, the following explanation will take U1 as the rated voltage of phase A winding as an example. That is, a voltage of the rated voltage U1 is applied to phase A winding, a voltage of half the rated voltage U1 and in the opposite direction is applied to phase B winding, and a voltage of half the rated voltage U1 and in the same direction is applied to phase C winding. At this time, refer to Table 1. Table 1 is a preset relationship table between the current value detected by the current sensor, the rotor position angle and the corresponding fault cause provided in the embodiment of the present invention. In this table, current sensor A is the first current sensor, current sensor B is the second current sensor, the value corresponding to the column of current sensor A is the first current value of phase A winding detected by the first current sensor, and the value corresponding to the column of current sensor A is the second current value of phase B winding detected by the second current sensor. As can be seen, when the rotor position angle is 0 degrees, corresponding to the preset correspondence table in Table 1, all phase windings are in normal condition. However, for the first and second current sensors, judgment needs to be made based on the current values. When the rotor position angle is 0 degrees, the first current sensor detects a first current value of I1 and a second current value of -I1 / 2, where I1 is the current generated in phase A winding after applying the first preset voltage when all three phase windings are normal. This indicates that both the first and second current sensors are normal. When the rotor position angle is 0 degrees, the first current sensor detects a first current value of 0 and a second current value of -I1 / 2, it indicates that the first current sensor is faulty, the second current sensor is normal, and all phase windings are normal. When the rotor position angle is 0 degrees, the first current sensor detects a first current value of I1 and a second current value of 0, it indicates that the second current sensor is faulty, the first current sensor is normal, and all phase windings are normal. When the rotor position angle is 0 degrees, the first current sensor detects a first current value of 0 and a second current value of 0, it indicates that both the first and second current sensors are faulty, and all phase windings are normal. To be clear, for ease of understanding, a first current value of I1, a second current value of -I1 / 2, and a rotor position angle of 0 indicate that the current sensors and all phase windings are functioning normally. Based on this normal condition, if the first current value is 0 and not I1, it indicates a fault in the first current sensor; if the second current value is 0 and not -I1 / 2, it indicates a fault in the second current sensor; and if both the first and second current values ​​are 0, it indicates a fault in both the first and second current sensors. When the rotor position angle is not 0, it indicates a fault in at least one phase winding, but determining which specific phase winding is faulty requires further diagnosis.

[0084] It should be noted that the method for obtaining Table 1 can be achieved through simulation or experimental verification by arranging and combining single-phase open circuit, multi-phase open circuit, single fault of current sensor, and multiple faults. This allows us to obtain the current values ​​fed back by each current sensor and the rotor position angle values ​​fed back by the rotor position sensor under different fault combinations. Analyzing and merging the feedback results, we obtain Table 1, which shows that there are 11 different combinations of values ​​for a single fault judgment.

[0085] Table 1 shows the fault diagnosis table after applying the first preset voltage to each phase winding.

[0086]

[0087] S350. When the rotor position angle is not 0 and all current values ​​are not 0, at least one phase winding is determined to be faulty, and all current sensors are normal.

[0088] Referring back to Table 1, when the acquired rotor position angle is not 0, and both the first and second current values ​​are not 0 (i.e., the rotor position angle is not 0, the first current value is I2, and the second current value is -I2), where I2 is the current in phase B and phase C windings when one phase winding is faulty, corresponding to the preset relationship table in Table 1, it can be determined that at least one phase winding is faulty, but the first and second current sensors are normal. In other words, based on Table 1, when the rotor position angle is -30°, the first current value is I2, and the second current value is -I2, it can be determined that the phase C winding is open-circuited, and the first and second current sensors are normal.

[0089] S360. When the rotor position angle is not 0 and at least one current value is 0, determine that at least one phase winding is faulty and at least one current sensor is faulty.

[0090] This step can be further broken down as follows: When the rotor position angle is -30°, the first current value detected by the first current sensor is 0, and the second current value detected by the second current sensor is -I2, a fault is determined in the C-phase winding, and the first current sensor is faulty; when the rotor position angle is -30°, the first current value detected by the first current sensor is I2, and the second current value detected by the second current sensor is 0, a fault is determined in the C-phase winding, and the second current sensor is faulty; when the rotor position angle is -30°, and both the first current value detected by the first current sensor and the second current value detected by the second current sensor are 0, a fault is determined in the C-phase winding, and both the first and second current sensors are faulty; when the rotor position angle is 30°, the first current value detected by the first current sensor is I2, and the second current value detected by the second current sensor is 0, a fault is determined in the B-phase winding, and the second current sensor is either normal or faulty; when the rotor position angle is 30°, and both the first current value detected by the first current sensor and the second current value detected by the second current sensor are 0, a fault is determined in the B-phase winding, and the first current sensor is faulty, or both the first and second current sensors are faulty.

[0091] Specifically, referring to Table 1, when the obtained rotor position angle is not 0 and at least one current value is 0 (i.e., the first current value is 0, the second current value is 0, or both the first and second current values ​​are 0), at least one phase winding fault and at least one current sensor fault can be determined. Specifically, when the rotor position angle is -30°, the first current value is 0, and the second current value is -I2, according to the preset relationship table in Table 1, it can be determined that the C-phase winding has an open circuit fault, the first current sensor is faulty, and the second current sensor is normal. When the rotor position angle is -30°, the first current value is I2, and the second current value is 0, according to the preset relationship table in Table 1, it can be determined that the C-phase winding has an open circuit fault, the second current sensor is faulty, and the first current sensor is normal. When the rotor position angle is -30°, and both the first and second current values ​​are 0, according to the preset relationship table in Table 1, it can be determined that the C-phase winding has an open circuit fault, and both the first and second current sensors are faulty. For simplicity, in the above scenario, when the rotor position angle is -30°, the first current value is I2, and the second current value is -I2, an open circuit fault in the C-phase winding can be determined, while the first and second current sensors are normal. Based on this, if the rotor position angles are the same, when the first current value is 0, the first current sensor is determined to be faulty; when the second current value is 0, the second current sensor is determined to be faulty; and when both the first and second current values ​​are 0, both the first and second current sensors are determined to be faulty.

[0092] When the rotor position angle is 30°, the first current sensor detects a first current value of I2, and the second current sensor detects a second current value of 0. According to the preset relationship table in Table 1, a faulty open circuit in phase B winding can be determined, and the second current sensor can be either normal or faulty. The reason the second current sensor is diagnosed as normal or faulty is that when phase B winding is faulty, the corresponding first current value is I2, and the second current value is 0. Therefore, when the second current value is 0, it cannot be determined whether the second current sensor is normal or faulty; it could be 0 generated during normal operation or during a fault.

[0093] When the rotor position angle is 30° and both the first and second current values ​​are 0, according to the preset relationship table in Table 1, it can be determined that the B-phase winding is open-circuited, the first current sensor is faulty, or both the first and second current sensors are faulty. Similarly, when the B-phase winding is open-circuited, the rotor position angle is 30°. In this case, the corresponding first current value should be I2, and the second current value should be 0. If the first current value is determined to be 0, then the first current sensor is faulty. If both the first and second current values ​​are determined to be 0, then the first current sensor is faulty, and the second current sensor is either normal or faulty, for the same reasons, which will not be explained here.

[0094] Furthermore, taking the open-circuit fault of phase B winding with normal sensors as an example, this section provides a theoretical explanation of the 10th case in Table 1, determining the feedback values ​​of the first current sensor, the second current sensor, and the rotor position sensor corresponding to the open-circuit fault of phase B winding. (Reference) Figure 6 and Figure 7 When a fault occurs in phase B winding, the current in phase B winding is 0, i.e., Ib = 0. Phase A and phase C windings are connected in series. The current in phase A winding is I2, and the current in phase C winding is -I2, i.e., Ia = I2, Ic = -I2. The currents in phase A winding and phase C winding are the same in magnitude but opposite in direction. After vector synthesis, refer to... Figure 7 The resulting composite current vector has an angle of 30° with the A-axis. This current will generate a composite magnetomotive force N in the same direction and a corresponding magnetic field, pulling the rotor permanent magnet to its current position, i.e., the rotor position angle of the motor is 30°. In summary, under the condition of an open circuit fault in phase B winding and normal sensor operation, the feedback values ​​of the first current value, the second current value, and the rotor position angle are (I2, 0, 30°). It is understood that the other cases in Table 1 can also be determined using the above analysis method, and will not be elaborated upon here.

[0095] S370. When the rotor position angle is not the preset angle and all current values ​​are 0, it is impossible to determine whether each current sensor is faulty or whether each phase winding is faulty.

[0096] Specifically, referring to Table 1, when the rotor position angle is not the preset angle and all current values ​​are 0, the preset angle is 0 ± 30°, corresponding to the 9th preset relationship in Table 1. The resulting fault may be an open circuit fault in phase A winding or multiple phase windings, and the sensor fault is unknown. In other words, at this time, the fault conditions of each phase winding and each current sensor cannot be accurately located, and secondary judgment and location are required.

[0097] S380. By applying a second preset voltage to the three-phase windings, when the rotor position angle is 90°, the first current value detected by the first current sensor is 0, and the second current value detected by the second current sensor is I2, it is determined that the A-phase winding is faulty, and the first current sensor is normal or faulty.

[0098] Specifically, during the secondary judgment, a second preset voltage needs to be applied to the three-phase windings, wherein the second preset voltage includes U A =-1 / 2U1,U B =U1,U C =-1 / 2U1; U1 is the rated voltage of one phase winding. For ease of understanding, the following explanation will use U1 as the rated voltage of phase A winding as an example. Referring to Table 2, which is a preset relationship table between the current value detected by the current sensor, the rotor position angle, and the corresponding fault cause after applying a second preset voltage to the three-phase winding based on the 9th case in Table 1, current sensor A is the first current sensor, current sensor B is the second current sensor, the value corresponding to the column of current sensor A is the first current value of phase A winding detected by the first current sensor, and the value corresponding to the column of current sensor A is the second current value of phase B winding detected by the second current sensor. It can be seen that under the condition of the second preset voltage, when the obtained first current value is 0, the second current value is I2, and the rotor position angle is 90°, according to the preset correspondence table in Table 2, the fault cause can be determined to be a fault in phase A winding, and the first current sensor is normal or faulty. The reasons for the first current sensor being normal and faulty are the same as the reasons described in S360, which can be referred to in S360, and will not be repeated here.

[0099] Table 2 shows the secondary fault judgment table after applying the second preset voltage to each phase winding.

[0100] 9.1 0 <![CDATA[I2]]> 90° Winding A is broken; sensor is normal or faulty (A). 9.2 0 0 90° Winding A is broken; sensor B or AB is faulty. 9.3 0 0 <![CDATA[θ1]]> Multiphase winding open circuit

[0101] It should be noted that the method for obtaining Table 2 can be based on Table 1. This can be achieved through simulation or experimental verification by arranging and combining single-phase open circuit, multi-phase open circuit, single fault of current sensor, and multiple faults. This yields the current values ​​fed back by each current sensor and the rotor position angle values ​​fed back by the rotor position sensor under different fault combinations. Analyzing and merging the feedback results reveals that there are three different combinations of values ​​for secondary fault judgment, as shown in Table 2.

[0102] S390. When the rotor position angle is 90°, and the first current value detected by the first current sensor and the second current value detected by the second current sensor are both 0, it is determined that the A-phase winding is faulty, the second current sensor is faulty, or both the first current sensor and the second current sensor are faulty.

[0103] Specifically, referring to Table 2, when the rotor position angle is 90°, and both the first current value detected by the first current sensor and the second current value detected by the second current sensor are 0, according to the preset correspondence table in Table 2, the fault cause can be determined to be an open circuit fault in phase A winding, a fault in the second current sensor, or a fault in both the first and second current sensors. The reasons for the first current sensor being normal or faulty are theoretically the same as those described in S360, and can be referred to in S360, so they will not be repeated here. It can be understood that S380 and S390 can be understood together. When the rotor position angle is 90°, it indicates an open circuit fault in phase A winding. Based on this, the first current value can be determined to be 0, and the second current value to be I2. Therefore, when the obtained current value is the same as above, it can be determined that the first current sensor is normal or faulty, and the second current sensor is normal. When the obtained second current value is also 0, the second current sensor is faulty.

[0104] S400. When the rotor position angle is any other angle, and the first current value detected by the first current sensor and the second current value detected by the second current sensor are both 0, at least two phase winding faults are determined.

[0105] The remaining angles are degrees excluding 0, ±30° and 90°.

[0106] Specifically, referring to Table 2, when the rotor position angle is other angles, and the first current value detected by the first current sensor and the second current value detected by the second current sensor are both 0, where other angles are degrees excluding 0, ±30° and 90°, corresponding to the preset correspondence table in Table 2, it can only be determined that the fault is an open circuit fault in multiple windings. However, it cannot be specifically determined whether it is an open circuit fault in phase A and phase B windings, or an open circuit fault in phase A and phase C windings, or an open circuit fault in phase B and phase C windings. Further diagnostic methods are needed.

[0107] The technical solution of this invention, by setting a preset relationship table for primary and secondary diagnosis, and specifically analyzing the acquired first current value, second current value and rotor position angle, can finally determine the corresponding fault cause, achieving accurate fault location. The logic is simple and easy to implement.

[0108] Based on the same inventive concept, continue to refer to Figure 2 This invention provides a fault diagnosis system for a three-phase permanent magnet synchronous motor. The system includes a star-connected three-phase winding, a rotor (not shown in the figure), a rotor position sensor (not shown in the figure), at least two current sensors 1, and a controller (not shown in the figure). Each current sensor 1 is located on two of the three-phase windings and is used to acquire the current value of the two-phase winding. The rotor position sensor is located on the rotor and is used to acquire the rotor position angle. The controller is electrically connected to the rotor position sensor and each current sensor 1 and is used to acquire the current value and the rotor position angle. A preset voltage is applied to the three-phase winding, and based on the current value of the two-phase winding and the rotor position angle, it is determined whether each current sensor is faulty and whether each phase winding is faulty.

[0109] Each current sensor 1 is located on two phases of the three-phase winding, with reference to... Figure 2 The three-phase winding includes phase A, phase B, and phase C windings. Current sensor 1 includes a first current sensor 11 and a second current sensor 12. The first current sensor 11 is located on the phase A winding, and the second current sensor 12 is located on the phase B winding. The first current sensor 11 is used to acquire a first current value of the phase A winding; the second current sensor 12 is used to acquire a second current value of the phase B winding. The preset voltage is... Figure 2 Middle U A U B and U C This refers to the voltage values ​​applied to the A-phase, B-phase, and C-phase windings respectively. These voltage values ​​can be determined by using the rated voltage of the A-phase winding to determine the voltages of the B-phase and C-phase windings, or vice versa. The specific method can be determined based on the actual situation and is not limited here. Additionally, refer to... Figure 2 The motor also includes an inverter for converting the DC preset voltage applied by the controller into AC voltage, so as to apply pressure to the three-phase windings using AC voltage.

[0110] It should be noted that the purpose of applying a preset voltage to the three-phase windings by the controller in this embodiment is to determine the correct current value and rotor position angle that should be output by the current sensor for the corresponding phase winding under the voltage. In other words, the controller has a pre-stored preset correspondence relationship under this preset voltage, which is the correspondence between current values ​​and preset current values, and between rotor position angles and preset rotor position angles. Thus, the controller can compare the actual current values ​​of two phase windings with the preset current values; if they are different, it indicates a fault in the current sensor. Similarly, the controller can compare the actual rotor position angle with the preset rotor position angle; if they are different, it indicates a fault in at least one phase winding. Using this method, it is possible to quickly and accurately determine whether each current sensor and each winding is faulty, so as to perform accurate repairs. Furthermore, if the controller determines that the acquired current value and rotor position angle do not belong to the above preset relationship, it is necessary to disassemble the motor for inspection to determine the location and cause of the fault. When the current values ​​are the first current value of phase A winding and the second current value of phase B winding, the controller determines the cause of the fault by comprehensively considering the current of phase A winding, the current of phase B winding, and the rotor position angle, combined with a preset correspondence, so as to accurately locate the cause of the fault.

[0111] The three-phase permanent magnet synchronous motor fault diagnosis system provided in this embodiment of the invention can execute the three-phase permanent magnet synchronous motor fault diagnosis method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the method.

[0112] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0113] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A fault diagnosis method for a three-phase permanent magnet synchronous motor, characterized in that, The three-phase permanent magnet synchronous motor includes a star-connected three-phase winding, a rotor, a rotor position sensor, and at least two current sensors. Each current sensor is located on two of the three-phase windings, and the rotor position sensor is located on the rotor. The method includes: The current values ​​of two phase windings detected by each of the current sensors and the rotor position angle detected by the rotor position sensor are obtained. By applying a preset voltage to the three-phase windings and determining whether each current sensor is faulty and whether each phase winding is faulty based on the current value of two phase windings and the rotor position angle; Specifically, by applying a preset voltage to the three-phase windings, and determining whether each current sensor is faulty, and whether each phase winding is faulty, based on the current values ​​of two phase windings and the rotor position angle, including: By applying a first preset voltage to the three-phase windings, and based on the current values ​​of two of the phase windings and the rotor position angle, it is determined whether each current sensor is faulty and whether each phase winding is faulty. When it is not determined whether each current sensor or each phase winding is faulty, a second preset voltage is applied to the three-phase windings, and the faultiness of each current sensor and each phase winding is determined based on the current value of two phase windings and the rotor position angle; the first preset voltage and the second preset voltage are different. The three-phase windings include phase A, phase B, and phase C windings; the first preset voltage includes UA=U1, UB=-1 / 2U1, and UC=1 / 2U1; U1 is the rated voltage of one phase winding; by applying the first preset voltage to the three-phase windings, determining whether each phase winding is faulty based on the current values ​​of two phase windings and the rotor position angle includes: By applying a first preset voltage to the three-phase windings, when the rotor position angle is 0 and at least one of the current values ​​is 0, it is determined that at least one of the current sensors is faulty, and the windings of each phase are normal. When the rotor position angle is not 0 and all current values ​​are not 0, it is determined that at least one phase of the winding is faulty, and all current sensors are normal. When the rotor position angle is not 0 and at least one of the current values ​​is 0, it is determined that at least one phase of the winding is faulty and at least one of the current sensors is faulty. When the rotor position angle is not a preset angle and all current values ​​are 0, it is impossible to determine whether each current sensor is faulty or whether each phase winding is faulty.

2. The fault diagnosis method according to claim 1, characterized in that, Before determining whether each current sensor is faulty and whether each phase winding is faulty by applying a preset voltage to the three-phase windings and based on the current values ​​of two phase windings and the rotor position angle, the process further includes: It was confirmed that none of the current sensors were short-circuited.

3. The fault diagnosis method according to claim 2, characterized in that, Determining that none of the aforementioned current sensors are short-circuited includes: If all the current values ​​are determined to be 0, then it is determined that the current sensor has not been short-circuited.

4. The fault diagnosis method according to claim 2, characterized in that, Before determining that any of the aforementioned current sensors have not experienced a short circuit, the procedure further includes: It was determined that the rotor position sensor was not malfunctioning.

5. The fault diagnosis method according to claim 1, characterized in that, The current sensor includes a first current sensor and a second current sensor, the first current sensor being located on the A-phase winding and the second current sensor being located on the B-phase winding; When the rotor position angle is 0 and at least one of the current values ​​is 0, determining that at least one of the current sensors is faulty includes: When the rotor position angle is 0, the first current value detected by the first current sensor is 0, and the second current value detected by the second current sensor is not 0, the first current sensor is determined to be faulty. When the rotor position angle is 0, the first current value detected by the first current sensor is not 0, and the second current value detected by the second current sensor is 0, it is determined that the second current sensor is faulty. When the rotor position angle is 0, and both the first current value detected by the first current sensor and the second current value detected by the second current sensor are 0, it is determined that both the first current sensor and the second current sensor are faulty.

6. The fault diagnosis method according to claim 1, characterized in that, The current sensor includes a first current sensor and a second current sensor, the first current sensor being located on the A-phase winding and the second current sensor being located on the B-phase winding; When the rotor position angle is not 0 and at least one of the current values ​​is 0, a fault is determined in at least one phase of the winding and at least one of the current sensors, including: When the rotor position angle is -30°, the first current value detected by the first current sensor is 0, and the second current value detected by the second current sensor is -I2, it is determined that the C-phase winding is faulty, and the first current sensor is faulty; I2 is the current in the B-phase winding and the C-phase winding when one of the phase windings is faulty. When the rotor position angle is -30°, the first current value detected by the first current sensor is I2, and the second current value detected by the second current sensor is 0, it is determined that the C-phase winding is faulty and the second current sensor is faulty. When the rotor position angle is -30°, and both the first current value detected by the first current sensor and the second current value detected by the second current sensor are 0, it is determined that the C-phase winding is faulty, and both the first current sensor and the second current sensor are faulty. When the rotor position angle is 30°, the first current value detected by the first current sensor is I2, and the second current value detected by the second current sensor is 0, it is determined that the B-phase winding is faulty, and the second current sensor is normal or faulty. When the rotor position angle is 30°, and the first current value detected by the first current sensor and the second current value detected by the second current sensor are both 0, it is determined that the B-phase winding is faulty, the first current sensor is faulty, or both the first current sensor and the second current sensor are faulty.

7. The fault diagnosis method according to claim 1, characterized in that, The three-phase winding includes an A-phase winding, a B-phase winding, and a C-phase winding; the current sensor includes a first current sensor and a second current sensor, the first current sensor being located on the A-phase winding and the second current sensor being located on the B-phase winding; the second preset voltage includes UA=-1 / 2U1, UB=U1, and UC=-1 / 2U1. U1 is the rated voltage of one phase of the winding; By applying a second preset voltage to the three-phase windings, and based on the current values ​​of two phase windings and the rotor position angle, it is determined whether each current sensor is faulty, and whether each phase winding is faulty, including: By applying the second preset voltage to the three-phase windings, when the rotor position angle is 90°, the first current value detected by the first current sensor is 0, and the second current value detected by the second current sensor is I2, it is determined that the A-phase winding is faulty, and the first current sensor is normal or faulty; I2 is the current in the B-phase winding and the C-phase winding when one of the phase windings is faulty; When the rotor position angle is 90°, and the first current value detected by the first current sensor and the second current value detected by the second current sensor are both 0, it is determined that the A-phase winding is faulty, the second current sensor is faulty, or both the first current sensor and the second current sensor are faulty. When the rotor position angle is any other angle, and the first current value detected by the first current sensor and the second current value detected by the second current sensor are both 0, at least two phases of the winding are determined to be faulty. The other angles are degrees excluding 0, ±30° and 90°.

8. A fault diagnosis system for a three-phase permanent magnet synchronous motor, characterized in that, The method for performing the fault diagnosis method of a three-phase permanent magnet synchronous motor according to any one of claims 1-7 includes a star-connected three-phase winding, a rotor, a rotor position sensor, at least two current sensors, and a controller. Each of the current sensors is located on two of the three-phase windings and is used to acquire the current value of the two phase windings. The rotor position sensor is located on the rotor and is used to obtain the rotor position angle; The controller is electrically connected to the rotor position sensor and each of the current sensors to acquire the current values ​​and the rotor position angle; it applies a preset voltage to the three-phase windings and determines whether each current sensor and each phase winding is faulty based on the current values ​​of two phase windings and the rotor position angle.

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