Fault diagnosis method and device of power tube and current sensor, and electronic equipment

Abstract

The application discloses a kind of fault diagnosis methods, specifically is related to a kind of power tube and the fault diagnosis method of current sensor, device and electronic equipment.The method comprises: obtaining the first phase current and the second phase current in signal period;Third phase current is calculated based on the first phase current and the second phase current;With the first phase current as abscissa and the second phase current as ordinate, output current trajectory is constructed, and with first target current as abscissa and second target current as ordinate, adjacent phase current trajectory is constructed, the first target current and the second target current are two of the first phase current, the second phase current and the third phase current except fault phase current;Target fault type is determined based on the output current trajectory and the adjacent phase current trajectory.The power tube and the coupling fault diagnosis of current sensor in traction inverter can be realized in the embodiment of the application.

Description

Technical Field

[0001] This invention pertains to a fault diagnosis method, specifically relating to a fault diagnosis method, apparatus, and electronic equipment for power transistors and current sensors. Background Technology

[0002] The traction inverter is the power heart of a high-speed train. As key components of the traction inverter, power transistors and current sensors play important roles in energy conversion and system control, respectively. Due to prolonged operation in harsh environments, power transistors and current sensors are highly susceptible to failure.

[0003] Power transistor failures mainly manifest as open circuits, caused by electrothermal effects, short-circuit breakdown, or loss of drive signals. These failures are latent and easily trigger secondary faults, directly affecting train operation safety. Current sensor failures mainly include jamming, zero-output, gain, offset, and noise faults, caused by package breakage, external stress, or electromagnetic interference, leading to reduced system control performance or even system failure.

[0004] Power transistor faults and current sensor faults are tightly coupled within a limited current signal. Because drive monitoring methods are prone to false alarms due to various interferences, effective power transistor fault diagnosis largely relies on sensor feedback. However, traction inverters commonly employ a two-current sensor scheme, meaning only two-phase current signals are available at the output, resulting in extremely limited fault information. Furthermore, the sensor signal bias or signal-to-weight ratio directly impacts fault diagnosis.

[0005] In practical applications, open-circuit faults in power transistors and the most severe zero-output faults in current sensors share similar and difficult-to-distinguish characteristics, and their coupling can lead to the loss of open-circuit fault features in the current sensor signal. Furthermore, the coupling between open-circuit faults in power transistors and current sensor offset faults exhibits characteristics similar to those of a single open-circuit fault in power transistors. Such phenomena are significant factors affecting the accurate diagnosis of coupled faults.

[0006] In coupled fault scenarios, fault characteristics are easily obscured or confused with fault information, making them difficult to extract (e.g., power transistor open-circuit faults and current sensor jamming or zero-output faults), or they are intertwined and coupled, making them difficult to fully identify (e.g., power transistor open-circuit faults and current sensor gain / offset / noise faults). Existing fault diagnosis methods typically focus on diagnosing and locating single faults, neglecting the joint diagnosis of coupled faults, resulting in poor accuracy of fault diagnosis results. Summary of the Invention

[0007] The technical problem to be solved by the present invention is that the methods commonly used in the prior art are usually for the diagnosis and location of a single fault, without considering the joint diagnosis when multiple types of faults are coupled, resulting in poor accuracy of the fault diagnosis results. In order to solve the above problem, the present invention provides a fault diagnosis method, device and electronic equipment for power transistors and current sensors.

[0008] The content of this invention includes: In a first aspect, embodiments of the present invention provide a fault diagnosis method for power transistors and current sensors, comprising: Obtain the first phase current and the second phase current within the signal cycle; Calculate the third phase current based on the first phase current and the second phase current; The output current trajectory is constructed with the first phase current as the abscissa and the second phase current as the ordinate, and the adjacent phase current trajectory is constructed with the first target current as the abscissa and the second target current as the ordinate. The first target current and the second target current are the two of the first phase current, the second phase current and the third phase current, excluding the fault phase current. The target fault type is determined based on the output current trajectory and the adjacent phase current trajectory.

[0009] Optionally, before determining the target fault type based on the output current trajectory and the adjacent phase current trajectory, the method further includes: Multiple sampling points are obtained by performing equidistant sampling on the output current trajectory; The sampling point that is closest to the origin of the output current trajectory is determined as the key point; Based on the key point, a first reference point and a second reference point are determined. The first reference point is a sampling point on the output current trajectory located before the key point, and the second reference point is a sampling point on the output current trajectory located after the key point.

[0010] Optionally, determining the target fault type based on the output current trajectory and the adjacent phase current trajectory includes: Target characteristic parameters are calculated based on the output current trajectory and the adjacent phase current trajectory. The target characteristic parameters include at least one of the following: comprehensive slope index, trajectory direction, center offset, amplitude gain, roundness, and key point offset. The target fault type is determined based on the target characteristic parameters; The comprehensive slope index is determined based on the slope of the output current trajectory, the trajectory direction is determined based on the directional increment of the output current trajectory, the center offset is used to quantify the impact of current sensor faults on the center position of the output current trajectory, the amplitude gain is used to evaluate the amplitude ratio of the output current trajectory in the horizontal axis direction to the vertical axis direction, the roundness is used to measure the degree of deviation of the adjacent phase current trajectory from the preset circular trajectory, and the key point offset is used to characterize the position offset of the key point.

[0011] Optionally, the target feature parameters include the comprehensive slope index, the trajectory direction, the center offset, the amplitude gain, the roundness, and the key point offset.

[0012] Optionally, determining the target fault type based on the target feature parameters includes: The target fault type is determined based on the correspondence between the values ​​of predefined target characteristic parameters and fault types.

[0013] Optionally, a comprehensive slope index is determined based on the output current trajectory and the adjacent phase current trajectory, including: A first local slope and a second local slope are determined, wherein the first local slope is used to characterize the slope between the key point and the first reference point, and the second local slope is used to characterize the slope between the key point and the second reference point; The first slope index, the second slope index, and the third slope index are determined based on the first local slope and the second local slope. The comprehensive slope index is determined based on the first slope index, the second slope index, and the third slope index.

[0014] Optionally, the first slope index for:

[0015]

[0016] Second slope index for:

[0017]

[0018] The third slope index for: ; ; in, The first local slope, This is the second local slope.

[0019] Secondly, embodiments of the present invention provide a fault diagnosis device for a power transistor and a current sensor, comprising: The acquisition module is used to acquire the first phase current and the second phase current within the signal cycle. The calculation module is used to calculate the third phase current based on the first phase current and the second phase current; The module is used to construct an output current trajectory with the first phase current as the abscissa and the second phase current as the ordinate, and to construct an adjacent phase current trajectory with the first target current as the abscissa and the second target current as the ordinate, wherein the first target current and the second target current are two of the first phase current, the second phase current and the third phase current, excluding the fault phase current. The first determining module is used to determine the target fault type based on the output current trajectory and the adjacent phase current trajectory.

[0020] Thirdly, embodiments of the present invention provide an electronic device, including: a memory, a processor, and a program stored in the memory and executable on the processor; the processor is configured to read the program in the memory to implement the steps in the fault diagnosis method for power transistors and current sensors as described in the first aspect.

[0021] Fourthly, embodiments of the present invention provide a readable storage medium for storing a program, which, when executed by a processor, implements the steps in the fault diagnosis method for power transistors and current sensors as described in the first aspect.

[0022] The beneficial effects of this invention are as follows: In the embodiments of this invention, the first phase current and the second phase current within the signal period are obtained; the third phase current is calculated based on the first phase current and the second phase current; an output current trajectory is constructed with the first phase current as the abscissa and the second phase current as the ordinate, and an adjacent phase current trajectory is constructed with the first target current as the abscissa and the second target current as the ordinate, wherein the first target current and the second target current are two of the first phase current, the second phase current, and the third phase current, excluding the fault phase current; the target fault type is determined based on the output current trajectory and the adjacent phase current trajectory. By constructing the adjacent phase current trajectory, the impact of the current sensor zero-output fault on the adjacent phase current is characterized, solving the problem that the open-circuit fault of the power transistor and the current sensor fault are similar in characteristics and difficult to distinguish, thus realizing the diagnosis of coupling faults between the power transistor and the current sensor in the traction inverter. Attached Figure Description

[0023] Appendix Figure 1 This is a topology diagram of a two-level inverter; Appendix Figure 2A flowchart of a fault diagnosis method for power transistors and current sensors provided in an embodiment of the present invention; Appendix Figure 3 Example diagram of diagnostic results for open circuit faults in T1 and T2; Appendix Figure 4 Example diagram of diagnostic results when phase A current sensor experiences zero output fault; Appendix Figure 5 Example diagram showing the diagnostic results of single-tube fault and sensor A offset coupling fault; Appendix Figure 6 A schematic diagram of a fault diagnosis device for a power transistor and a current sensor provided in an embodiment of the present invention; Appendix Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0024] In this application's embodiments, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship. In this application's embodiments, the term "multiple" refers to two or more, and other quantifiers are similar. The terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such terms can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first" and "second" are generally of the same class, not limited to the number of objects. For example, the first object can be one or multiple.

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0027] First, let's analyze some of the terms used in this application: The topology of a two-level inverter consists of six power switches and their parallel-connected reverse diodes. A DC power supply serves as the system input, providing electrical energy for the inverter to convert power. Each bridge arm contains two power switches and two reverse diodes, which control the forward and reverse current flow, respectively. See [link to relevant documentation] for details. Figure 1 .

[0028] To perform fault detection and monitor the output current, current sensors were installed on phases A and B, respectively, to measure the output current of phase A. and B-phase current . Figure 1 middle, Indicates the DC bus voltage. The IGBT modules representing phases A, B, and C are respectively. According to Kirchhoff's laws, the current value of phase C can be calculated from the current signals of phases A and B of the inverter. The specific calculation is not limited here.

[0029] Based on this, embodiments of this application provide a fault diagnosis method, device, and electronic device for power transistors and current sensors, aiming to achieve accurate diagnosis of coupling faults in key components of traction inverters.

[0030] Please see Figure 2 , Figure 2 This is a flowchart illustrating the fault diagnosis method for power transistors and current sensors provided in an embodiment of the present invention. The method specifically includes the following steps: Step 101: Obtain the first phase current and the second phase current within the signal cycle.

[0031] Step 102: Calculate the third phase current based on the first phase current and the second phase current.

[0032] Step 103: Construct an output current trajectory with the first phase current as the abscissa and the second phase current as the ordinate, and construct an adjacent phase current trajectory with the first target current as the abscissa and the second target current as the ordinate. The first target current and the second target current are the two of the first phase current, the second phase current and the third phase current, excluding the fault phase current.

[0033] Step 104: Determine the target fault type based on the output current trajectory and the adjacent phase current trajectory.

[0034] For ease of description, the first phase current is denoted as phase A, the second phase current as phase B, and the third phase current as phase C. As mentioned above, phase A and phase B currents can be detected using current sensors. By acquiring data at multiple sampling points within the signal cycle, the phase A and phase B currents can be obtained. Furthermore, the phase C current can be calculated from the phase A and phase B currents; the specific process will not be elaborated here.

[0035] As a specific implementation, the output current trajectory can be constructed by using the A-phase current as the abscissa and the B-phase current as the ordinate. In some embodiments, the faulty phase current can be determined based on the first and second phase currents, and then the adjacent phase current trajectory can be constructed. For example, in the case of an A-phase current fault, the adjacent phase current trajectory is constructed based on the B-phase and C-phase currents; in the case of a B-phase current fault, the adjacent phase current trajectory is constructed based on the A-phase and C-phase currents. Through the adjacent phase current trajectory model, key features can be extracted to effectively distinguish between a dual-transistor open-circuit fault in the power transistor and a zero-output fault in the current sensor.

[0036] The output current trajectory under normal operating conditions is different from that under fault conditions. The adjacent phase current trajectory under normal operating conditions is also different from that under fault conditions. Furthermore, the adjacent phase current trajectories are also different under different fault types. Therefore, the fault type can be determined by obtaining the output current trajectory and the adjacent phase current trajectory.

[0037] The following analysis first examines the output current trajectory and adjacent phase current trajectory under normal operating conditions and system fault conditions to illustrate how to determine the fault type based on the output current trajectory and adjacent phase current trajectory.

[0038] Under normal operating conditions, the three-phase currents (A, B, and C) are 120° phase-shifted relative to each other, maintaining a stable amplitude and phase relationship. This results in an elliptical current trajectory in the xy coordinate system, where the output current trajectory is constructed with the A-phase and B-phase currents as the coordinate axes, i.e., the horizontal axis corresponds to the A-phase current. The vertical axis corresponds to the B-phase current. The current through phase A and B-phase current Transforming to the xy coordinate system, the characteristic equation of the output current trajectory during normal operation can be obtained as follows: ; ; in, The amplitude of phase A current. This represents the amplitude of the B-phase current. =2π / 3 is the phase difference.

[0039] When a system fault occurs, this balance is disrupted, and the output current trajectory will change significantly. Taking an open-circuit fault in phase A as an example, the current in phase A is zero throughout the entire cycle, i.e.: ; The output current trajectory has changed from an ellipse to a straight line: ; The output current trajectory changed from an ellipse to a straight line, providing a basis for fault diagnosis.

[0040] To effectively diagnose power transistor open-circuit faults and current sensor zero-output faults, this embodiment further constructs adjacent-phase current trajectories to characterize the impact of current sensor zero-output faults on adjacent-phase currents, addressing the problem of difficulty in distinguishing between power transistor open-circuit faults and current sensor faults due to their similar characteristics. During normal operation, the three-phase currents can be expressed as: ; in, It is angular frequency. This represents the amplitude of the C-phase current.

[0041] In equilibrium, the superposition of the three-phase currents forms a rotating magnetic flux, the complex form of which is: ; Where N is the number of turns in the stator winding.

[0042] The adjacent phase current is defined by the fault-free currents of the other two phases. Specifically, the adjacent phase current trajectory is obtained by phase-shifting the adjacent phase current and performing coordinate transformation on the two adjacent phase currents. When the system is operating normally or a double-tube open-circuit fault occurs, the adjacent phase current trajectory appears as a circle centered on the origin; however, when the current sensor experiences a zero-output fault, the adjacent phase current trajectory will exhibit an irregular shape.

[0043] The following analysis will take the current of phase A as the fault phase current as an example to conduct a detailed analysis of the current trajectory of adjacent phases.

[0044] For example, when a double-tube open-circuit fault occurs in phase A, The stator flux linkage after the fault is as follows: ; in ,because Therefore, we can further obtain: ; calculate ,therefore: ; Starting from the amplitude, the flux linkage amplitude after the fault is .

[0045] To maintain flux linkage balance, the flux linkage amplitude is equal before and after the fault (before the fault it is...). ): ; Transforming this to the time domain, we get: ; ; At this point, the system can be considered equivalent to a single-phase inverter.

[0046] By performing a π / 2 phase shift on the C-phase current, we can obtain: ; ; definition , Using m as the abscissa and n as the ordinate, we obtain the equation for the adjacent phase current trajectory, which satisfies: ; In an ideal situation where there is no abnormal control influence, the adjacent phase current trajectory is roughly circular, with its center at the origin, and rotates periodically around the origin.

[0047] When the A-phase current sensor experiences a zero-output fault, the system's stability is severely affected, as detailed below: Under normal operating conditions, to achieve effective control of the q-axis current, the output voltage of the PI controller is... It can be represented as: ; in, Set the desired q-axis current value. To obtain the actual q-axis current value from the feedback, and These are the proportional gain and integral gain of the controller, respectively. This is the delay of the inverter.

[0048] In some embodiments, due to the relationship between the stator voltage and the rotor flux linkage ( and The π can be ignored, therefore the simplified expression for the PI controller output voltage is: ; The equation for the q-axis voltage on the motor side is: ; in, It is the stator resistance. It is a q-axis inductor.

[0049] When the A-phase current sensor experiences a zero-output fault, the current feedback signal remains constant at 0, leading to current error. This persists. At this point, the controller output is: ; The voltage on the motor side still meets the requirements: ; Equating the controller output voltage with the motor-side voltage equation, we obtain: ; The characteristic equation obtained by rearranging is: ; Under zero-output fault conditions, the coefficients of the characteristic equation become: ; According to the Routh criterion, the stability of a system requires that all elements in the first column of the Routh table be positive. If > or A value greater than 0 will cause the Routh table to become negative, leading to system instability. When the current error... When the characteristic equation becomes a constant non-zero value due to a zero-output fault, the root distribution is affected. This is especially true when... Exceed When this happens, the output voltage of the PI controller will oscillate, and the error will gradually accumulate, eventually causing the system to lose stability and making the adjacent phase current trajectory exhibit an irregular shape.

[0050] Based on the above analysis, although the zero-output fault of the current sensor and the dual-transistor fault of the power transistor have similar characteristics in the output current trajectory, their impact mechanisms on the adjacent phase current are significantly different. Therefore, by constructing the adjacent phase current trajectory and extracting key features, the dual-transistor fault of the power transistor and the zero-output fault of the current sensor can be effectively distinguished under limited current signals, thereby realizing the diagnosis of coupling faults between the power transistor and the current sensor in the traction inverter.

[0051] To better describe the output current trajectory, in some embodiments, key points are determined from the output current trajectory, and the slope and direction increment of the output current trajectory are further described based on the key points. Optionally, in some embodiments, before step 104, the method further includes: Multiple sampling points are obtained by performing equidistant sampling on the output current trajectory; The sampling point that is closest to the origin of the output current trajectory is determined as the key point; Based on the key point, a first reference point and a second reference point are determined. The first reference point is a sampling point on the output current trajectory located before the key point, and the second reference point is a sampling point on the output current trajectory located after the key point.

[0052] In some embodiments, a preliminary judgment can be made based on the geometric position of the key point: when the output current trajectory passes through the origin, or the key point falls within the neighborhood of the origin, the shape of the output current trajectory is significantly distorted, indicating that there may be an open circuit fault; if the key point is significantly offset relative to the origin, it is necessary to further distinguish current sensor faults.

[0053] To further refine the fault type determination, optionally in some embodiments, step 104 includes: Target characteristic parameters are calculated based on the output current trajectory and the adjacent phase current trajectory. The target characteristic parameters include at least one of the following: comprehensive slope index, trajectory direction, center offset, amplitude gain, roundness, and key point offset. The target fault type is determined based on the target characteristic parameters; The comprehensive slope index is determined based on the slope of the output current trajectory, the trajectory direction is determined based on the directional increment of the output current trajectory, the center offset is used to quantify the impact of current sensor faults on the center position of the output current trajectory, the amplitude gain is used to evaluate the amplitude ratio of the output current trajectory in the horizontal axis direction to the vertical axis direction, the roundness is used to measure the degree of deviation of the adjacent phase current trajectory from the preset circular trajectory, and the key point offset is used to characterize the position offset of the key point.

[0054] It should be understood that, in some embodiments, the target feature parameters include at least one of the following: comprehensive slope index, trajectory direction, center offset, amplitude gain, roundness, and key point offset. In practice, the more types of target feature parameters there are, the more accurate the fault location and fault type determination can be achieved.

[0055] As a specific embodiment, the target feature parameters include the comprehensive slope index, the trajectory direction, the center offset, the amplitude gain, the roundness, and the key point offset. In this embodiment, multiple target feature parameters are extracted to analyze the output current trajectory and adjacent phase current trajectory, thereby enabling a more precise judgment of the fault type.

[0056] The following example uses a specific implementation to illustrate the various target feature parameters.

[0057] As a specific implementation, in order to extract the geometric features of the neighborhood of the key point, the output current is sampled at equal intervals within one fundamental frequency cycle to obtain data of P sampling points (e.g., P=100), and the distance from each sampling point to the origin is calculated. The sampling point closest to the origin is selected as the key point B, and 15 points before and after it are defined as the first reference point A and the second reference point C, respectively.

[0058] The comprehensive slope index is used to detect abnormal slope changes in the output current trajectory to distinguish between normal operating conditions and power transistor open circuits or current sensor faults. Optionally, in some embodiments, the comprehensive slope index is determined based on the output current trajectory and the adjacent phase current trajectory, including: A first local slope and a second local slope are determined, wherein the first local slope is used to characterize the slope between the key point and the first reference point, and the second local slope is used to characterize the slope between the key point and the second reference point; The first slope index, the second slope index, and the third slope index are determined based on the first local slope and the second local slope. The comprehensive slope index is determined based on the first slope index, the second slope index, and the third slope index.

[0059] The coordinates of key point B are denoted as The coordinates of the first reference point A are denoted as... The coordinates of the second reference point C are denoted as... Based on the first reference point A, the key point B, and the second reference point C, two local slopes are defined, denoted as the first local slope. Second local slope :

[0060] ; Here, ε>0 is a minimal quantity used to avoid instability caused by an excessively small denominator. Its specific value can be adjusted and set according to the actual situation, and is not limited here.

[0061] As described above, a fault will cause a typical distortion in the local slope, manifesting as an approximately horizontal, vertical, or -45° trend. To quantify this characteristic, the two local slope segments are independently determined and segmented indicator values ​​are generated (1 if the condition is met, 0 otherwise), which can be represented as follows: ; At the cyclical level, segmented indicators of the same type are combined using a logical "OR" to obtain the first slope indicator. Second slope index and the third slope index :

[0062]

[0063] ; Based on the first slope index Second slope index and the third slope index Further determine the comprehensive slope index : ; when At that time, the trajectory did not show significant distortion, which was mostly related to sensor gain faults or offset faults; when When the trajectory exhibits distortion in a single direction, it typically corresponds to an open circuit fault in a single tube or two tubes in the same phase; when If the value is 0, it indicates that there may be an open circuit fault in the out-of-phase dual tubes.

[0064] In the process of diagnosing power transistor faults, through comprehensive analysis , and Determining the overall slope index can provide a preliminary assessment of the fault type and its potential location. While the overall slope index can characterize the type of trajectory distortion, it is insufficient to directly pinpoint the specific faulty component.

[0065] In some embodiments, the target feature parameters include the trajectory direction, which (Δx, Δy) is determined based on the direction increment of the output current trajectory and is used to identify the direction of abnormal trajectories. For example, let the direction increment of the neighborhood of key point B be: ; ; In some embodiments, the direction increment is determined by the segmentation of the triggering anomaly criterion. For example, when | k AB When |≤0.2 triggers a level-based exception, take Δ. x =Δ x (AB) When | k BC When |≤0.2 is triggered, then Δ is taken. x =Δ x (BC) Similarly, the vertical and -45° categories take the longitudinal or lateral increments of the corresponding segments, respectively.

[0066] Device positioning can be achieved based on direction symbols and anomaly categories: whenk y When =1, Δ y >0 and Δ y <0 corresponds to the upper and lower bridge arms T1 and T2 respectively; when k x When =1, Δ x <0 and Δ x >0 corresponds to T3 and T4 respectively; when k xy When =1, Δ x >0 and Δ x <0 corresponds to T5 and T6 respectively.

[0067] Thus, the geometric distortion category and direction increment realize the mapping from trajectory to specific device. Combined with the position criterion of key point B, it is possible to achieve unified diagnosis and accurate location of power tube open circuit faults and current sensor faults under the condition of relying only on two-phase current signals.

[0068] In some embodiments, the target feature parameters include a center bias. This is used to quantify the impact of a current sensor fault on the center position of the output current trajectory. When a current sensor bias fault occurs, the center point of the output current trajectory ( This will cause a shift, disrupting the symmetry of the current trajectory.

[0069] In some embodiments, for ease of description, the center offset is defined based on the range of coordinate values ​​of the center point. The possible values ​​are as follows: like >Δ and If the value is greater than Δ, then the center is offset. ; like <-Δ and If the value is greater than Δ, then the center is offset. .

[0070] Wherein, Δ is a pre-set bias threshold, the value of which can be determined through statistical analysis and / or experimental verification, and is not limited here.

[0071] Current trajectory data was collected under normal operating conditions and different fault conditions, based on the trajectory center point ( The value of the center offset is determined by selecting a critical value that can effectively distinguish between normal and fault states. If the trajectory center offset is within the threshold range, it is considered that the trajectory center offset has not yet reached the fault judgment standard, and the center offset is defined. We do not believe that there is a bias fault.

[0072] In some embodiments, the target characteristic parameter includes amplitude gain, which is used to evaluate the amplitude ratio of the output current trajectory in the x-axis and y-axis directions to determine the gain fault of the current sensor. When a current sensor experiences a gain fault, the amplitude of the current signal will change abnormally, affecting the shape and amplitude distribution of the output current trajectory. Through amplitude gain characteristic analysis, the specific phase of the current sensor experiencing a gain fault can be accurately identified. The amplitude gain is defined according to the range of amplitude values ​​as follows: like If the amplitude gain is greater than 1 + δ, then the amplitude gain G = 1; like If <1-δ, then the amplitude gain G = -1.

[0073] in, for x Amplitude in the axial direction, for y The amplitude in the axial direction, δ, is a pre-set amplitude gain threshold. Its value can be determined through statistical analysis and / or experimental verification, and is not limited here.

[0074] When the amplitude ratio is between [1-δ, 1+δ], the current sensor is considered to be in normal condition. Variations in the amplitude ratio within this range are usually normal fluctuations in the system or minor environmental interference, and are insufficient to determine a gain fault. Only when the amplitude ratio exceeds a preset threshold is a gain fault considered to exist, thus avoiding misjudging normal amplitude fluctuations as fault points.

[0075] In some embodiments, the target characteristic parameter includes roundness, where roundness D measures the degree of deviation between the adjacent phase current trajectory and a preset circular trajectory. The preset circular trajectory is the ideal adjacent phase current trajectory under normal operating conditions. Roundness analysis can effectively determine the degree of trajectory deviation, thereby distinguishing between a sensor zero-output fault and a power transistor in-phase open-circuit fault. Roundness is defined as follows: ; in, The maximum radius of the adjacent phase current trajectory. It is the minimum radius of the adjacent phase current trajectory.

[0076] As a specific implementation, to distinguish between an open-circuit fault in the power transistor and a zero-output fault in the current sensor, a roundness value D = 0.5 is set as the roundness threshold. If D < 0.5, the current trajectories of adjacent phases are relatively regular, close to circular; If D > 0.5, the current trajectory deviates significantly from a circle and exhibits an irregular shape.

[0077] Extensive experiments were conducted to verify this by varying the rotational speed and torque conditions. The results show that a zero-output fault in the current sensor typically leads to a significant increase in the roundness value of the adjacent phase current trajectory, generally exceeding 0.6; while an open-circuit fault in the power transistor keeps the adjacent phase current trajectory relatively regular and circular, with a roundness value typically less than 0.4. Therefore, setting the roundness threshold to 0.5 is a reasonable choice.

[0078] In some embodiments, the target feature parameters include keypoint biases. The position offset of key point B is used to detect the coupling between power transistor fault and current sensor bias fault. By analyzing the bias characteristics of key point B, it is possible to accurately determine whether there is coupling between power transistor open circuit fault and current sensor bias fault.

[0079] When an open circuit in the power transistor and a current sensor bias coupling fault occur, the position of key point B will shift. The key point bias is defined based on the range of coordinate values ​​of the key point as follows: like >Δ and If the value is greater than Δ, then the keypoint offset is... ; like <-Δ and If the value is greater than Δ, then the keypoint offset is... ; In some embodiments, the offset threshold Δ corresponding to the keypoint offset is the same as the offset threshold corresponding to the center offset. If the coordinates of keypoint B are within the threshold range, then the keypoint offset is defined. They concluded that there was no bias fault.

[0080] Optionally, in some embodiments, determining the target fault type based on the target feature parameters includes: The target fault type is determined based on the correspondence between the values ​​of predefined target characteristic parameters and fault types.

[0081] It should be understood that the correspondence between the values ​​of the target characteristic parameters and the fault types is predefined and is not specifically limited here. For example, the correspondence between the predefined values ​​of the target characteristic parameters and the fault types can be found in Table 1 below.

[0082] In some embodiments, fault types can be pre-classified based on a comprehensive slope index, and then, based on the pre-classification results, the current fault type can be determined further based on the predefined correspondence between each target feature parameter and the fault type.

[0083] The following is an example of a specific implementation. First, by acquiring the two-phase current signal within one signal cycle ( The output current trajectory and adjacent phase current trajectory are constructed by calculating the distance between each sampling point and the origin, key point B, first reference point A, and second reference point C. In practical applications, when a power transistor fault occurs, point B is usually close to the origin.

[0084] Next, extract the first slope index. Second slope index and the third slope index As a global feature parameter, a comprehensive slope index is calculated, and the comprehensive slope index is used to initially detect potential fault types.

[0085] In the first case, when the comprehensive slope index meets the first preset condition, namely: ; At this point, the output current trajectory remains an elliptical trajectory, does not cross the origin, and has no abnormal slope, which may indicate a sensor gain or bias fault. Therefore, it is necessary to consider the center bias. Further judgment is then made based on the amplitude gain G. In the specific implementation, the correspondence between the center bias value, the amplitude gain value, and the fault type is predefined as follows: If the center is offset The corresponding fault type is A-phase current sensor bias fault; If the center is offset The corresponding fault type is B-phase current sensor bias fault; If amplitude gain The corresponding fault type is A-phase current sensor gain fault; If amplitude gain The corresponding fault type is B-phase current sensor gain fault.

[0086] In the second case, when the comprehensive slope index meets the second preset condition, namely: ; At this point, the output current trajectory exhibits an abnormal change in direction and slope, requiring further determination of the fault time. Is it less than half the signal period? / 2.

[0087] if / 2, there may be an open circuit fault in a single power transistor or a coupling fault with the sensor offset. The trajectory direction (Δx, Δy) is calculated using the coordinate information of key point B and the second reference point C, combined with the key point offset. This allows for further analysis to determine whether the fault is of a coupled type, and to accurately locate the fault location based on the criteria in Table 1.

[0088] if / 2, the roundness D needs to be extracted from the adjacent phase current trace to distinguish between in-phase power transistor faults and zero-output current sensor faults. Specifically, the predefined roundness values ​​and key point biases correspond to the fault types as follows: If roundness D < 0.5 and The trajectory shape is roughly circular, and the corresponding fault type is a power transistor in-phase open circuit fault. If roundness D > 0.5 and The trajectory is irregular, and the corresponding fault type is zero output fault of the current sensor. like The corresponding fault type is current sensor jamming fault.

[0089] Combination Table 1 and the specific fault phase and faulty device can be further determined.

[0090] In the third case, when the comprehensive slope index meets the third preset condition, namely: ; At this point, the output current trajectory exhibits two abnormal directions and slope changes, indicating that the system may have a power transistor dual-transistor out-of-phase open circuit fault or a coupling fault with the current sensor bias.

[0091] For a dual-tube out-of-phase fault, the trajectory can be considered as the superposition of two single-tube faults. The vector direction and abnormal slope characteristics are calculated using the coordinates of A, B, and C, and then combined with... This allows for further identification of the faulty power transistor. Regarding the coupling fault with the current sensor bias, since the trajectory shows both bias and directional abnormalities, further analysis of the key point bias and... By combining the criteria in Table 1, we can accurately distinguish the types and specific locations of compound faults, thereby achieving a comprehensive diagnosis of power transistor open circuit and sensor bias coupling faults.

[0092] Table 1. Correspondence between predefined target characteristic parameters and fault types

[0093] The following example of a specific experimental result illustrates the beneficial effects of the method provided in this embodiment of the invention. Experimental results for three different types of faults will be presented to verify the effectiveness and robustness of the proposed fault diagnosis method.

[0094] Diagnosis of open circuit fault in phase A power transistor as follows: Figure 3 As shown, Figure 3 The diagnostic results for open-circuit faults T1 and T2 are given, among which, Figure 3(a) represents the current, (b) represents the roundness, and (c) represents the diagnostic result. At 0.2 seconds, an open-circuit fault occurred in phase A power transistor. Before the fault, the system current exhibited a normal sinusoidal waveform; after the fault, the phase A current rapidly dropped to zero, indicating that the current was completely disconnected. Through calculation of the target characteristic parameters, the trajectory roundness characteristic value was below 0.5, accurately determining the fault type and location. Fault flags F1 and F2 were both set to 1, successfully detecting the open-circuit fault in phase A power transistor and locating it to T1 and T2.

[0095] A-phase current sensor zero-output fault diagnosis, such as... Figure 4 As shown, Figure 4 The diagnostic results for a zero-output fault in phase A current sensor are given, among which, Figure 4 In the diagram, (a) represents the current, (b) represents the roundness, and (c) represents the fault diagnosis result. At 0.2 seconds, the A-phase current sensor experienced a zero-output fault. After the fault occurred, the A-phase current waveform fixed at 0 and no longer exhibited a sinusoidal waveform. Simultaneously, the B-phase current waveform showed an amplitude shift, consistent with the characteristics of a zero-output fault in the current sensor. The characteristic value rapidly exceeded the 0.5 threshold, reflecting the occurrence of the fault. The fault flag F9 was set to 1, and the system correctly identified the zero-output fault of the A-phase current sensor, verifying the effectiveness of the method provided in this embodiment of the invention in detecting such faults.

[0096] T1 open circuit and A-phase current sensor bias coupling fault diagnosis as follows: Figure 5 As shown, Figure 5 The diagnostic results for single-tube faults and sensor A offset coupling faults are presented, whereby... Figure 5 In the diagram, (a) represents the current, (b) represents the slope index and key point bias, and (c) represents the fault diagnosis result. At 0.2 seconds, the T1 power transistor experienced an open-circuit fault, and at 0.22 seconds, the A-phase current sensor experienced a bias fault. After the faults occurred, the A-phase current waveform exhibited abnormalities: due to the T1 open circuit, the current rapidly decreased to zero; due to the sensor bias, the current waveform shifted and did not completely return to zero. Simultaneously, the B-phase waveform showed a slight amplitude shift. Through the calculation of the target characteristic parameters, the changes in each target characteristic parameter were consistent with the predefined correspondence. The F1 and F7 flags were set to 1, and the system successfully detected and located the coupling between the T1 power transistor open-circuit fault and the A-phase current sensor bias fault. This verifies the reliability and effectiveness of the embodiments of the present invention in handling coupled faults.

[0097] In the fault diagnosis method for power transistors and current sensors provided in this embodiment, the composite fault diagnosis of power transistors and current sensors can be completed by relying only on two-phase current signals, determining the specific type of fault and the specific component of the fault, and achieving accurate fault location. This overcomes the shortcomings of traditional methods, which are difficult to achieve a clear mapping between faults and states due to the lack of corresponding state characteristics under limited current conditions, and are unable to effectively distinguish coupled faults with similar or mixed characteristics.

[0098] Please see Figure 6 This invention also provides a fault diagnosis device 600 for power transistors and current sensors, comprising: The acquisition module 601 is used to acquire the first phase current and the second phase current during the signal cycle. Calculation module 602 is used to calculate the third phase current based on the first phase current and the second phase current; The construction module 603 is used to construct an output current trajectory with the first phase current as the abscissa and the second phase current as the ordinate, and to construct an adjacent phase current trajectory with the first target current as the abscissa and the second target current as the ordinate, wherein the first target current and the second target current are two of the first phase current, the second phase current and the third phase current, excluding the fault phase current. The first determining module 604 is used to determine the target fault type based on the output current trajectory and the adjacent phase current trajectory.

[0099] Optionally, the fault diagnosis device 600 for the power transistor and current sensor further includes: The sampling module is used to perform equidistant sampling on the output current trajectory to obtain multiple sampling points; The second determining module is used to determine the sampling point with the smallest distance from the origin of the output current trajectory as the key point; The third determining module is used to determine a first reference point and a second reference point based on the key point. The first reference point is a sampling point on the output current trajectory located before the key point, and the second reference point is a sampling point on the output current trajectory located after the key point.

[0100] Optionally, the first determining module 604 includes: The calculation unit is used to calculate target characteristic parameters based on the output current trajectory and the adjacent phase current trajectory. The target characteristic parameters include at least one of the following: comprehensive slope index, trajectory direction, center offset, amplitude gain, roundness, and key point offset. The determining unit is used to determine the target fault type based on the target feature parameters; The comprehensive slope index is determined based on the slope of the output current trajectory, the trajectory direction is determined based on the directional increment of the output current trajectory, the center offset is used to quantify the impact of current sensor faults on the center position of the output current trajectory, the amplitude gain is used to evaluate the amplitude ratio of the output current trajectory in the horizontal axis direction to the vertical axis direction, the roundness is used to measure the degree of deviation of the adjacent phase current trajectory from the preset circular trajectory, and the key point offset is used to characterize the position offset of the key point.

[0101] Optionally, the target feature parameters include the comprehensive slope index, the trajectory direction, the center offset, the amplitude gain, the roundness, and the key point offset.

[0102] Optionally, the determining unit is specifically used for: The target fault type is determined based on the correspondence between the values ​​of predefined target characteristic parameters and fault types.

[0103] Optionally, a comprehensive slope index is determined based on the output current trajectory and the adjacent phase current trajectory, including: A first local slope and a second local slope are determined, wherein the first local slope is used to characterize the slope between the key point and the first reference point, and the second local slope is used to characterize the slope between the key point and the second reference point; The first slope index, the second slope index, and the third slope index are determined based on the first local slope and the second local slope. The comprehensive slope index is determined based on the first slope index, the second slope index, and the third slope index.

[0104] Optionally, the first slope index for:

[0105]

[0106] Second slope index for:

[0107]

[0108] The third slope index for: ; ; in, The first local slope, This is the second local slope.

[0109] The fault diagnosis device 600 for power transistors and current sensors provided in this application embodiment can execute the above method embodiment, and its implementation principle and technical effect are similar, so it will not be described again here.

[0110] It should be noted that the division of units in the embodiments of this application is illustrative and only represents one logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units described above can be implemented in hardware or as software functional units.

[0111] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a processor-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0112] like Figure 7 As shown, this application provides an electronic device 700, including: a memory 702, a processor 701, and a program stored in the memory 702 and executable on the processor 701; the processor 701 is used to read the program in the memory 702 to implement the steps in the fault diagnosis method for power transistors and current sensors as described above.

[0113] This application also provides a readable storage medium storing a program. When the program is executed by a processor, it implements the various processes of the above-described fault diagnosis method embodiment for power transistors and current sensors, and achieves the same technical effect. To avoid repetition, it will not be described again here. The readable storage medium can be any available medium or data storage device that the processor can access, including but not limited to magnetic storage (such as floppy disks, hard disks, magnetic tapes, magneto-optical disks (MOs), etc.), optical storage (such as compact disks (CDs), digital video discs (DVDs), Blu-ray discs (BDs), high-definition versatile discs (HVDs), etc.), and semiconductor storage (such as read-only memory (ROMs), erasable programmable read-only memory (EPROMs), electrically erasable programmable read-only memory (EEPROMs), non-volatile memory (NAND flash), solid-state drives (SSDs)).

[0114] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0115] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0116] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A fault diagnosis method for a power transistor and a current sensor, characterized in that, include: Obtain the first phase current and the second phase current within the signal cycle; Calculate the third phase current based on the first phase current and the second phase current; The output current trajectory is constructed with the first phase current as the abscissa and the second phase current as the ordinate, and the adjacent phase current trajectory is constructed with the first target current as the abscissa and the second target current as the ordinate. The first target current and the second target current are the two of the first phase current, the second phase current and the third phase current, excluding the fault phase current. The target fault type is determined based on the output current trajectory and the adjacent phase current trajectory; Before determining the target fault type based on the output current trajectory and the adjacent phase current trajectory, the method further includes: Multiple sampling points are obtained by performing equidistant sampling on the output current trajectory; The sampling point that is closest to the origin of the output current trajectory is determined as the key point; Based on the key point, a first reference point and a second reference point are determined. The first reference point is a sampling point on the output current trajectory located before the key point, and the second reference point is a sampling point on the output current trajectory located after the key point. The step of determining the target fault type based on the output current trajectory and the adjacent phase current trajectory includes: Target characteristic parameters are calculated based on the output current trajectory and the adjacent phase current trajectory. The target characteristic parameters include comprehensive slope index, trajectory direction, center offset, amplitude gain, roundness and key point offset. The target fault type is determined based on the target characteristic parameters; The comprehensive slope index is determined based on the slope of the output current trajectory, the trajectory direction is determined based on the directional increment of the output current trajectory, the center offset is used to quantify the impact of current sensor faults on the center position of the output current trajectory, the amplitude gain is used to evaluate the amplitude ratio of the output current trajectory in the horizontal axis direction to the vertical axis direction, the roundness is used to measure the degree of deviation of the adjacent phase current trajectory from the preset circular trajectory, and the key point offset is used to characterize the position offset of the key point. The step of determining the target fault type based on the target feature parameters includes: The fault types are pre-classified according to the comprehensive slope index. Then, based on the pre-classification results, the current target fault type is determined according to the predefined target feature parameters and the correspondence between fault time and fault type. The fault types include current sensor gain fault, bias fault, zero output fault, single power tube open circuit fault, dual tube out-of-phase open circuit fault, and dual tube in-phase open circuit fault. The determination of the comprehensive slope index based on the slope of the output current trajectory includes: A first local slope and a second local slope are determined, wherein the first local slope is used to characterize the slope between the key point and the first reference point, and the second local slope is used to characterize the slope between the key point and the second reference point; The first slope index, the second slope index, and the third slope index are determined based on the first local slope and the second local slope. The comprehensive slope index is determined based on the first slope index, the second slope index, and the third slope index; Among them, the first slope index for: ； Second slope index for: ； ； ； The third slope index for: ； ； ； The comprehensive slope index for: ； in, The first local slope, This is the second local slope. , , , , and All are segmented indicators, with values ​​of 0 or 1.

2. A fault diagnosis device for a power transistor and a current sensor, characterized in that, include: The acquisition module is used to acquire the first phase current and the second phase current within the signal cycle. The calculation module is used to calculate the third phase current based on the first phase current and the second phase current; The construction module is used to construct the output current trajectory with the first phase current as the abscissa and the second phase current as the ordinate, and to construct the adjacent phase current trajectory with the first target current as the abscissa and the second target current as the ordinate, wherein the first target current and the second target current are two of the first phase current, the second phase current and the third phase current, excluding the fault phase current. The first determining module is used to determine the target fault type based on the output current trajectory and the adjacent phase current trajectory; The fault diagnosis device for the power transistor and current sensor further includes: The sampling module is used to perform equidistant sampling on the output current trajectory to obtain multiple sampling points; The second determining module is used to determine the sampling point with the smallest distance from the origin of the output current trajectory as the key point; The third determining module is used to determine a first reference point and a second reference point based on the key point. The first reference point is a sampling point on the output current trajectory located before the key point, and the second reference point is a sampling point on the output current trajectory located after the key point. The first determining module includes: The calculation unit is used to calculate target characteristic parameters based on the output current trajectory and the adjacent phase current trajectory. The target characteristic parameters include comprehensive slope index, trajectory direction, center offset, amplitude gain, roundness and key point offset. The determining unit is used to determine the target fault type based on the target feature parameters; The comprehensive slope index is determined based on the slope of the output current trajectory, the trajectory direction is determined based on the directional increment of the output current trajectory, the center offset is used to quantify the impact of current sensor faults on the center position of the output current trajectory, the amplitude gain is used to evaluate the amplitude ratio of the output current trajectory in the horizontal axis direction to the vertical axis direction, the roundness is used to measure the degree of deviation of the adjacent phase current trajectory from the preset circular trajectory, and the key point offset is used to characterize the position offset of the key point. Specifically, the determining unit is used for: The fault types are pre-classified according to the comprehensive slope index. Then, based on the pre-classification results, the current target fault type is determined according to the predefined target feature parameters and the correspondence between fault time and fault type. The fault types include current sensor gain fault, bias fault, zero output fault, single power tube open circuit fault, dual tube out-of-phase open circuit fault, and dual tube in-phase open circuit fault. The determination of the comprehensive slope index based on the slope of the output current trajectory includes: A first local slope and a second local slope are determined, wherein the first local slope is used to characterize the slope between the key point and the first reference point, and the second local slope is used to characterize the slope between the key point and the second reference point; The first slope index, the second slope index, and the third slope index are determined based on the first local slope and the second local slope. The comprehensive slope index is determined based on the first slope index, the second slope index, and the third slope index; Among them, the first slope index for: ； Second slope index for: ； ； ； The third slope index for: ； ； ； The comprehensive slope index for: ； in, The first local slope, This is the second local slope. , , , , and All are segmented indicators, with values ​​of 0 or 1.

3. An electronic device, comprising: A memory, a processor, and a program stored in the memory and executable on the processor; characterized in that the processor is configured to read the program from the memory to implement the steps in the fault diagnosis method for power transistors and current sensors as described in claim 1.

4. A readable storage medium for storing a program, characterized in that, When the program is executed by the processor, it implements the steps in the fault diagnosis method for power transistors and current sensors as described in claim 1.

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