Three-phase motor phase-to-phase short circuit detection method and system

Abstract

The application discloses a three-phase motor phase-to-phase short-circuit detection method and system, relates to the motor fault diagnosis technical field, and discloses the three-phase motor phase-to-phase short-circuit detection method and system, which excites by inputting a sampling voltage with a specific amplitude to a phase winding of a three-phase motor and obtains current data of a non-excitation phase winding, realizes fault determination through ratio calculation and threshold comparison, solves the problems that traditional detection means cannot realize fast online monitoring, is low in efficiency and inaccurate in positioning, realizes fast online detection, automatic judgment and accurate positioning of the three-phase motor phase-to-phase short-circuit fault, and improves detection efficiency and safety.

Description

Technical Field

[0001] This application relates to the field of motor fault diagnosis technology, and in particular to a method and system for detecting phase-to-phase short circuits in three-phase motors. Background Technology

[0002] Three-phase motors, as core industrial power equipment, are most commonly affected by phase-to-phase short-circuit faults. If these faults are not detected and addressed promptly, they can lead to serious consequences such as abnormally increased motor operating current, localized overheating of windings, and even burnout. This not only affects the normal operation of the equipment but may also cause safety accidents. Currently, traditional detection methods used in industrial settings, such as megohmmeter measurements, multimeter testing, or dedicated short-circuit detectors, have significant limitations: they typically require offline testing of the motor before equipment installation, involve manual operation, are inefficient, and are susceptible to subjective judgment errors; more importantly, they cannot detect early short-circuit hazards that dynamically change during motor operation, making timely warnings difficult.

[0003] The above content is only used to help understand the technical solution of this application and does not represent an admission that the above content is prior art. Summary of the Invention

[0004] The main purpose of this application is to provide a method and system for detecting phase-to-phase short circuits in three-phase motors, aiming to improve the safety and efficiency of detecting phase-to-phase short circuit faults in three-phase motors.

[0005] To achieve the above objectives, this application proposes a method for detecting phase-to-phase short circuits in a three-phase motor, the method comprising:

[0006] Step S100: Input a sampling voltage to one phase winding of the three-phase motor for excitation, so as to obtain the current data of the non-excited phase winding accordingly;

[0007] Step S200: Calculate the ratio of the current data to obtain the corresponding current ratio, and compare the current ratio with a preset threshold to obtain the corresponding fault judgment data;

[0008] For the unexcited phase winding, repeat steps S100 and S200 until, based on the fault determination data, it is determined that the three-phase motor has no phase-to-phase short circuit fault, has a phase-to-phase short circuit fault, or the phase-to-phase short circuit fault of the three-phase motor is located.

[0009] In one embodiment, the three-phase motor is connected to a three-phase drive circuit and a three-phase current sampling circuit, respectively, and step S100 includes:

[0010] The bus voltage data is proportionally stepped down based on the three-phase drive circuit to obtain the sampled voltage.

[0011] The sampled voltage data is input to one phase winding of a three-phase motor to excite it, and this process continues for a preset duration.

[0012] The current data of the non-excited phase winding is obtained based on the three-phase current sampling circuit.

[0013] In one embodiment, the preset threshold includes a preset lower threshold and a preset upper threshold, and step S200 includes:

[0014] The current data is used to calculate the ratio to obtain the corresponding current ratio.

[0015] The current ratio is compared with the preset lower threshold and the preset upper threshold respectively. If the current ratio is lower than the preset lower threshold or higher than the preset upper threshold, the fault determination data indicates that the three-phase motor has a phase-to-phase short circuit fault.

[0016] In one embodiment, prior to step S100, the method further includes:

[0017] Obtain the current temperature data of the three-phase motor windings;

[0018] Query the pre-stored benchmark database to obtain the dynamic threshold corresponding to the temperature data, and update the dynamic threshold to the preset threshold.

[0019] In one embodiment, the complete execution of steps S100 and S200 is considered as one detection cycle, and the first detection cycle and the second detection cycle are executed sequentially; the location of inter-phase short-circuit faults in a three-phase motor based on the fault determination data includes:

[0020] If the fault determination data of the first detection cycle determines that the three-phase motor has no phase-to-phase short circuit fault, and the fault determination data of the second detection cycle determines that the three-phase motor has a phase-to-phase short circuit fault, then the phase-to-phase short circuit fault is located between the excitation phase winding and the non-excitation phase winding in the second detection cycle.

[0021] If the fault determination data of the first detection cycle determines that the three-phase motor has a phase-to-phase short circuit fault, and the fault determination data of the second detection cycle determines that the three-phase motor has no phase-to-phase short circuit fault, then the phase-to-phase short circuit fault is located between the excitation phase winding and the non-excitation phase winding in the first detection cycle.

[0022] In one embodiment, the location of inter-phase short-circuit faults in a three-phase motor based on the fault determination data further includes:

[0023] If the fault determination data from the first and second detection cycles both indicate that the three-phase motor has a phase-to-phase short circuit fault, then the third detection cycle is executed.

[0024] If the fault determination data of the third detection cycle determines that the three-phase motor has no phase-to-phase short circuit fault, then the phase-to-phase short circuit fault is located between the excitation phase winding of the first detection cycle and the excitation phase winding of the second detection cycle.

[0025] If the fault determination data from the third detection cycle determines that the three-phase motor has a phase-to-phase short circuit fault, then it is determined that the three-phase motor has multiple phase-to-phase short circuit faults.

[0026] In one embodiment, after determining that the three-phase motor has a phase-to-phase short-circuit fault, the method further includes:

[0027] The current deviation value is calculated based on the current ratio and the preset threshold, and the collected current waveform data is subjected to harmonic analysis to obtain the total harmonic distortion rate data.

[0028] Based on the current deviation value and the total harmonic distortion rate data, the short-circuit resistance value is calculated using a preset short-circuit resistance mapping model.

[0029] The short-circuit resistance value is compared with a multi-level preset warning threshold range, and a graded warning operation is performed based on the comparison result.

[0030] In one embodiment, the multi-level preset warning threshold range includes a first-level warning threshold range, a second-level alarm threshold range, and a third-level fault threshold range. The step of comparing the short-circuit resistance value with the multi-level preset warning threshold range and performing a graded warning operation based on the comparison result includes:

[0031] When the short-circuit resistance value is within the range of the first-level warning threshold, a first warning signal is reported;

[0032] When the short-circuit resistance value is within the range of the secondary alarm threshold, a second warning signal is reported, and the maximum output power of the three-phase motor is limited to below a preset power.

[0033] When the short-circuit resistance value is within the range of the third-level fault threshold, a third warning signal is reported and the corresponding safety protection strategy is executed.

[0034] In one embodiment, prior to step S100, the method further includes:

[0035] The three-phase drive circuit is controlled to apply voltage pulses to any phase winding of the three-phase motor, and the initial slope of the corresponding current response is collected.

[0036] If the initial slope data exceeds the preset slope threshold, then step S100 is executed.

[0037] Furthermore, to achieve the above objectives, this application also proposes a three-phase motor phase-to-phase short-circuit detection system, the system comprising: a memory, a processor, and a three-phase motor phase-to-phase short-circuit detection program stored in the memory and executable on the processor, the three-phase motor phase-to-phase short-circuit detection program being configured to implement the steps of the three-phase motor phase-to-phase short-circuit detection method.

[0038] The three-phase motor phase-to-phase short circuit detection method and system proposed in this application excite one phase winding of the three-phase motor by inputting a sampling voltage of a specific amplitude and acquiring the current data of the non-excited phase winding. Fault determination is achieved by calculating the ratio and comparing it with a threshold. This solves the problems of traditional detection methods, such as inability to quickly monitor online, low efficiency, and inaccurate positioning. It realizes rapid online detection, automatic judgment, and accurate positioning of phase-to-phase short circuit faults in three-phase motors, improving detection efficiency and safety. Attached Figure Description

[0039] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0040] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 A flowchart illustrating an embodiment of the three-phase motor phase-to-phase short circuit detection method of this application;

[0042] Figure 2 For this application Figure 1 A detailed flowchart of step S100;

[0043] Figure 3 For this application Figure 1 A detailed flowchart of step S200;

[0044] Figure 4 This is a flowchart illustrating another embodiment of the three-phase motor phase-to-phase short circuit detection method of this application;

[0045] Figure 5 A flowchart illustrating yet another embodiment of the three-phase motor phase-to-phase short circuit detection method of this application;

[0046] Figure 6 A flowchart illustrating yet another embodiment of the three-phase motor phase-to-phase short circuit detection method of this application;

[0047] Figure 7This is a schematic diagram of a structure provided for an embodiment of the three-phase motor phase-to-phase short-circuit detection system of this application;

[0048] Figure 8 This is a schematic diagram of the current waveform provided in an embodiment of the three-phase motor phase-to-phase short circuit detection method of this application;

[0049] Figure 9 This is a schematic diagram of the current waveform provided for another embodiment of the three-phase motor phase-to-phase short circuit detection method of this application.

[0050] Explanation of icon numbers:

[0051] 10. Memory; 20. Processor.

[0052] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0053] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0054] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0055] The main solution of this application embodiment is: Step S100, inputting a sampling voltage to one phase winding of a three-phase motor for excitation, so as to obtain the current data of the non-excited phase winding accordingly;

[0056] Step S200: Calculate the ratio of the current data to obtain the corresponding current ratio, and compare the current ratio with a preset threshold to obtain the corresponding fault judgment data;

[0057] For the unexcited phase winding, repeat steps S100 and S200 until, based on the fault determination data, it is determined that the three-phase motor has no phase-to-phase short circuit fault, has a phase-to-phase short circuit fault, or the phase-to-phase short circuit fault of the three-phase motor is located.

[0058] In this embodiment, for ease of description, the following description will focus on a three-phase motor phase-to-phase short-circuit detection system.

[0059] In existing technologies, three-phase motors, as core industrial power equipment, experience phase-to-phase short-circuit faults, which are among the most common types of failures. If these faults are not detected and addressed promptly, they can lead to serious consequences such as abnormally increased motor operating current, localized overheating of windings, and even burnout. This not only affects the normal operation of the equipment but may also cause safety accidents. Currently, traditional detection methods used in industrial settings, such as megohmmeter measurements, multimeter testing, or dedicated short-circuit detectors, have significant limitations: they typically require offline testing of the motor before equipment installation, the testing process requires manual operation, is inefficient, and is prone to subjective judgment errors; more importantly, they cannot detect early short-circuit hazards in the motor, making timely warnings difficult.

[0060] This application provides a solution that excites one phase winding of a three-phase motor by inputting a sampling voltage and acquiring current data of the non-excited phase winding. Fault determination is achieved by calculating the ratio and comparing it with a threshold. This solves the problems of traditional detection methods, such as inability to quickly monitor online, low efficiency, and inaccurate positioning. It realizes rapid online detection, automatic judgment, and accurate positioning of phase-to-phase short circuit faults in three-phase motors, improving detection efficiency and safety.

[0061] It should be noted that the executing entity in this embodiment can be a computing service device with data processing, network communication, and program execution functions, such as a tablet computer, personal computer, or mobile phone, or an electronic device capable of performing the above functions, such as a three-phase motor phase-to-phase short-circuit detection system. The following description uses a three-phase motor phase-to-phase short-circuit detection system as an example to illustrate this embodiment and the subsequent embodiments.

[0062] In existing technologies, three-phase motors, as core industrial power equipment, are susceptible to damage from phase-to-phase short circuits if not detected promptly, leading to abnormal current, overheating of windings, and even burnout. Traditional detection methods require offline testing before equipment installation, resulting in low detection efficiency. For example, in continuous production line operation scenarios, if a hidden phase-to-phase short circuit exists during motor startup, traditional detection methods struggle to detect the potential fault in a timely manner.

[0063] To address the aforementioned issues, the inventors discovered that traditional methods for quickly capturing abnormal signals from three-phase motors during the startup preparation phase necessitate the establishment of an online detection mechanism. By analyzing the abnormal current distribution caused by phase-to-phase short circuits, they proposed using the correlation between active excitation and response current for fault diagnosis. Based on the principle that symmetrical windings should exhibit a specific proportional relationship under normal conditions, they designed a cyclic judgment logic for phase-by-phase excitation and cross-detection to quickly locate the fault point.

[0064] Based on this, the embodiments of this application provide a method for detecting phase-to-phase short circuits in a three-phase motor, referring to... Figure 1 Three-phase motor phase-to-phase short circuit detection includes:

[0065] Step S100: Input a sampling voltage to one phase winding of the three-phase motor for excitation, so as to obtain the current data of the non-excited phase winding accordingly;

[0066] Step S200: Calculate the ratio of the current data to obtain the corresponding current ratio, and compare the current ratio with a preset threshold to obtain the corresponding fault judgment data;

[0067] Step S300: Repeat steps S100 and S200 for the unexcited phase windings until it is determined, based on the fault determination data, that the three-phase motor has no phase-to-phase short circuit fault, has a phase-to-phase short circuit fault, or the phase-to-phase short circuit fault of the three-phase motor is located.

[0068] In this embodiment, the sampling voltage is a low-amplitude test voltage obtained by proportionally reducing the bus voltage. Specifically, a stepped wave signal can be generated using PWM modulation to avoid the three-phase motor being subjected to large current surges. Unexcited phase windings refer to windings for which no sampling voltage is applied during the current detection cycle. For example, if a sampling voltage is applied to phase A winding during the current detection cycle, then phase B and phase C windings are unexcited phase windings. If a sampling voltage is applied to phase B winding during the current detection cycle, then phase A and phase C windings are also unexcited phase windings. Unexcited phase windings refer to windings for which no sampling voltage has been applied during the entire three-phase motor phase-to-phase short-circuit detection process. A complete execution of steps S100 and S200 constitutes one detection cycle. If only phase A winding is sampled for one detection cycle, then the unexcited phase windings are phase B and phase C windings. If a sampling voltage is applied to phase B winding for one detection cycle, then the unexcited phase winding is phase C winding. Ratio calculation refers to using the quotient of the two-phase currents as the basis for judgment. Specifically, the current of one phase winding is divided by the current of the other phase winding to obtain the current ratio. The preset threshold is a threshold set according to the impedance symmetry of the motor windings. Specifically, it includes two thresholds and forms a range based on these two thresholds. For example, 0.9-1.1 or 0.95-1.05 is set as the normal fluctuation range. If the value exceeds this range, a fault judgment is triggered.

[0069] In this embodiment, when a sampling voltage is applied to phase A winding, phases B and C windings form a closed loop. Under normal conditions, the currents in phases B and C exhibit a fixed proportional relationship due to the symmetry of the windings, and their current ratio is theoretically 1 (referencing) excluding external interference. Figure 8The waveform below is the excitation phase waveform, and the two waveforms above are the non-excitation phase waveforms. By collecting current data from phases B and C, the ratio of their currents is calculated and compared with a preset threshold to obtain corresponding fault judgment data. This fault judgment data includes both three-phase motors with no phase-to-phase short circuit faults and three-phase motors with phase-to-phase short circuit faults. If the ratio exceeds the preset threshold range, fault detection data can be provided to determine that the three-phase motor has a phase-to-phase short circuit fault (see reference). Figure 9 The waveform below is the excitation phase waveform, and the two waveforms above are the non-excitation phase waveforms. Thus, one or more detection cycles can be performed as needed, thereby determining whether the three-phase motor has no phase-to-phase short-circuit fault, has a phase-to-phase short-circuit fault, or completes the location of the phase-to-phase short-circuit fault based on the fault determination data obtained from one or more detection cycles. Specifically, when it is only necessary to determine whether the three-phase motor has a fault, if the fault determination data obtained in the first detection cycle determines that the three-phase motor has a phase-to-phase short-circuit fault, the detection can be stopped; if the fault determination data obtained in the first detection cycle determines that the three-phase motor has no phase-to-phase short-circuit fault, the second detection cycle needs to be performed.

[0070] Understandably, for ease of maintenance, this application can also locate phase-to-phase short-circuit faults. In this case, at least two detection cycles of phase-to-phase short-circuit testing are required. For example, if the fault determination data from the first detection cycle determines that the three-phase motor has no phase-to-phase short-circuit fault, but the fault determination data from the second detection cycle determines that the three-phase motor has a phase-to-phase short-circuit fault, then the phase-to-phase short-circuit fault is located between the excitation phase winding and the non-excitation phase winding in the second detection cycle. That is, by performing one or more detection cycles of phase-to-phase short-circuit testing as needed, this application can determine whether a three-phase motor has a phase-to-phase short-circuit fault, and can accurately locate the phase winding combination where the short circuit occurred by cross-comparing the fault determination data obtained from multiple detection cycles of phase-to-phase short-circuit testing, thus facilitating subsequent maintenance.

[0071] In this embodiment, rapid detection during the startup preparation stage is achieved through online active excitation. Fault screening can be automatically completed during the equipment startup stage, effectively identifying phase-to-phase short circuit faults. Furthermore, the phase-by-phase cyclic detection mechanism can accurately determine the location of the short circuit between phases, effectively preventing equipment damage caused by latent short circuits, ensuring the continuous and safe operation of industrial equipment, and improving the safety and detection efficiency of phase-to-phase short circuit fault detection in three-phase motors.

[0072] In one feasible implementation, the three-phase motor is connected to both a three-phase drive circuit and a three-phase current sampling circuit, as shown in the reference. Figure 2 Step S100 includes:

[0073] Step S110: Perform proportional voltage reduction processing on the bus voltage data based on the three-phase drive circuit to obtain the sampled voltage;

[0074] Step S120: Input the sampled voltage data into one phase winding of the three-phase motor to excite it, and continue for a preset time;

[0075] Step S130: Obtain the current data of the non-excited phase winding based on the three-phase current sampling circuit.

[0076] In this embodiment, the duty cycle of the PWM modulation is controlled by the program, and the corresponding phase voltage is generated by the drive circuit (for example, if the duty cycle of the PWM modulation is 3%, the drive circuit will eventually generate a phase voltage equal to 3% of the bus voltage), thereby obtaining the sampled voltage. It is understood that, considering the influence of the motor's angular position and the motor's incomplete stationary state due to external interference, the sampled phase current may not be ideally stable and balanced, which is not conducive to making the final result judgment. Therefore, a preset time period (the duration of the applied excitation voltage) is used to lock the motor rotor to the position with the minimum magnetic reluctance between it and the stator, ensuring that the winding current reaches a stable state for accurate sampling and detection. This preset time period can be 100ms, 150ms, etc., as long as it allows the non-excited phase winding to reach a stable state; its specific value is not limited here. The three-phase current sampling circuit can be a measurement module composed of a current sensor and a signal conditioning circuit. Specifically, it can be implemented using a Hall effect sensor or a shunt resistor in conjunction with an operational amplifier to capture the current change data of the non-excited phase winding in real time.

[0077] In this embodiment, during the detection process, the bus voltage is first proportionally adjusted by the step-down module inside the drive circuit, for example, reducing the 400V bus voltage to a safe range below 5V. The adjusted sampling voltage is applied to both ends of the target phase winding, such as phase A winding, while phases B and C are in an unexcited state. Within a preset time period, such as 100ms, the current sampling circuit continuously collects the current signals of phases B and C and transmits the data to the processing unit.

[0078] In this embodiment, rapid online detection is achieved directly using the drive circuit and built-in sampling module. Furthermore, this solution reuses the voltage output function of the drive circuit to achieve periodic automatic detection capability. Thus, this application solves the deficiency of traditional detection methods in rapidly monitoring phase-to-phase short circuits online. Simultaneously, proportional voltage reduction ensures the safety of the detection process, preventing secondary damage to the winding insulation caused by high voltage. The collaborative working mode of the current sampling circuit and the drive circuit allows the detection data to be directly integrated into the motor control system, providing real-time data support for fault early warning.

[0079] In one feasible implementation, the preset threshold includes a preset lower threshold and a preset upper threshold, as referenced. Figure 3 Step S200 includes:

[0080] Step S210: Calculate the ratio of the current data to obtain the corresponding current ratio;

[0081] Step S220: Compare the current ratio with the preset lower threshold and the preset upper threshold respectively. If the current ratio is lower than the preset lower threshold or higher than the preset upper threshold, then determine that the three-phase motor has a phase-to-phase short circuit fault based on the fault determination data.

[0082] In this embodiment, the preset lower threshold refers to the minimum allowable value of the current ratio, which can be achieved using empirical data or experimental calibration values. For example, it can be set to 0.9 times the normal current ratio under standard operating conditions. Similarly, the preset upper threshold refers to the maximum allowable value of the current ratio, which can be generated through theoretical calculations or dynamic adjustment models. For example, it can be set to 1.1 times the normal current ratio. The current ratio refers to the ratio of the current data of the non-excited phase winding, which can be obtained by dividing the two values. It is used to quantify the degree to which the current deviates from the normal range.

[0083] In this embodiment, during the detection process, when a phase winding is energized, the current data of the non-energized phase winding is collected and calculated as a current ratio. This ratio is compared with a preset lower threshold and a preset upper threshold to determine whether it exceeds the allowable range. If the current ratio is lower than the preset lower threshold or higher than the preset upper threshold, a phase-to-phase short-circuit fault is determined based on the fault determination data. In this embodiment, the preset upper and lower thresholds can cover the reasonable fluctuation range under normal operating conditions and accurately identify abnormal signals exceeding the range, thereby accurately detecting phase-to-phase short-circuit faults in the three-phase motor.

[0084] In one feasible implementation, refer to Figure 4 Before step S100, the method further includes:

[0085] Step S011: Obtain the current temperature data of the three-phase motor windings;

[0086] Step S012: Query the pre-stored benchmark database, obtain the dynamic threshold corresponding to the temperature data, and update the dynamic threshold to the preset threshold.

[0087] In this embodiment, the temperature data is the winding temperature value collected in real time by a temperature sensor, specifically a surface-mount thermistor or an infrared temperature measurement module, used to reflect the actual thermal state of the motor. The reference database refers to a database storing the mapping relationship between temperature and corresponding threshold values, specifically implemented using non-volatile memory, used to dynamically adjust the judgment criteria according to temperature changes. The dynamic threshold refers to the range of current ratios that automatically adjust with temperature changes, specifically generated through a preset temperature-threshold curve or a polynomial fitting algorithm, used to eliminate the influence of temperature on winding resistance.

[0088] In this embodiment, before the detection process begins, a temperature sensor is placed on or inside the motor windings to collect the current temperature signal in real time. The collected temperature data is transmitted to the processor, triggering a reference database query operation. The reference database pre-stores the corresponding current ratio threshold ranges at different temperatures; for example, the threshold range can be 0.95-1.05 at 20℃, and adjusted to 0.90-1.10 at 80℃. By updating the dynamic threshold corresponding to the current temperature to the preset threshold, the subsequent current ratio comparison process can automatically compensate for the changes in winding resistance caused by temperature increases, avoiding misjudgments caused by fixed threshold settings.

[0089] In this embodiment, a dynamic threshold adjustment mechanism automatically adapts the detection standard to temperature changes, resolving the misjudgment problem caused by temperature drift. This enables accurate identification of phase-to-phase short-circuit faults at different temperatures, effectively reducing the impact of ambient temperature changes on the detection results and improving the reliability of fault determination. Simultaneously, by pre-storing a benchmark database, the processing delay caused by real-time threshold calculation is avoided, ensuring the real-time nature of the detection process.

[0090] In one feasible implementation, the complete execution of steps S100 and S200 is considered as one detection cycle, and the first detection cycle and the second detection cycle are executed sequentially. Locating the phase-to-phase short-circuit fault of the three-phase motor based on the fault determination data includes: if the fault determination data of the first detection cycle determines that the three-phase motor has no phase-to-phase short-circuit fault, and the fault determination data of the second detection cycle determines that the three-phase motor has a phase-to-phase short-circuit fault, then the phase-to-phase short-circuit fault is located between the excitation phase winding and the unexcited phase winding in the second detection cycle; if the fault determination data of the first detection cycle determines that the three-phase motor has a phase-to-phase short-circuit fault, and the fault determination data of the second detection cycle determines that the three-phase motor has no phase-to-phase short-circuit fault, then the phase-to-phase short-circuit fault is located between the excitation phase winding and the unexcited phase winding in the first detection cycle.

[0091] In this embodiment, the detection cycle refers to the complete detection process including voltage excitation, current acquisition, ratio calculation and threshold comparison. The fault judgment data refers to the logical judgment signal generated by comparing the current ratio with the preset threshold. Specifically, it can be implemented using a digital comparator or a condition judgment module in a microprocessor to determine whether a short circuit fault exists.

[0092] In this embodiment, for example, in the first detection cycle, a voltage excitation is applied to the A-phase winding. If the current ratio does not exceed the threshold range, and in the second detection cycle, a voltage excitation is applied to the B-phase winding, if the current ratio exceeds the threshold, then the fault is determined to exist between the B-phase and the unexcited C-phase. Conversely, if a fault is determined to exist in the first detection cycle but not in the second detection cycle, it indicates that the fault exists between the A-phase winding that was excited in the first detection cycle and the C-phase winding that was not excited. By observing the changes in the excited phases and the differences in the determination results between the two detection cycles, the location of the phase-to-phase short-circuit fault is achieved.

[0093] In this embodiment, by switching the excitation phases in stages and comparing the results, the location of phase-to-phase short circuit faults can be achieved. The fault point is directly associated with a specific winding combination, without relying on manual inspection or offline testing equipment. This solves the problem that traditional detection methods cannot determine the fault location, enabling maintenance personnel to quickly locate the faulty winding combination, reduce inspection time, and improve the efficiency of motor operation and maintenance.

[0094] In one feasible implementation, the location of phase-to-phase short-circuit faults in the three-phase motor based on the fault determination data further includes: if the fault determination data of the first detection cycle and the second detection cycle both determine that the three-phase motor has a phase-to-phase short-circuit fault, then a third detection cycle is executed; if the fault determination data of the third detection cycle determines that the three-phase motor has no phase-to-phase short-circuit fault, then the phase-to-phase short-circuit fault is located between the excitation phase winding of the first detection cycle and the excitation phase winding of the second detection cycle; if the fault determination data of the third detection cycle determines that the three-phase motor has a phase-to-phase short-circuit fault, then it is determined that the three-phase motor has multiple phase-to-phase short-circuit faults.

[0095] In this embodiment, the first detection cycle and the second detection cycle are independent detection processes that excite different phase windings of the three-phase motor and obtain fault determination data, respectively. If fault location cannot be achieved after the first and second detection cycles, a third detection cycle is performed for fault detection.

[0096] In this embodiment, when both the first and second detection cycles trigger fault determination, a third detection cycle is executed. The phase winding that was not excited in the previous two cycles is selected for excitation; for example, after phases A and B have been excited, phase C is selected for the third excitation. If no fault is detected in the third cycle, it indicates that the short circuit exists only between the first two excited phases; if a fault is still detected in the third cycle, it indicates that at least two independent short circuit paths exist. This logic gradually narrows down the fault range through elimination, avoiding potential misjudgments that might occur with a single detection cycle.

[0097] In this embodiment, by introducing a third detection cycle and constructing a multi-level verification mechanism, it is possible to clearly distinguish between a single short circuit point and multiple faults within three detections, reducing the need for manual intervention, solving the problem of inaccurate fault location when multiple detection results conflict, improving the diagnostic accuracy in complex short circuit scenarios, and automatically identifying multiple faults through logical judgment to avoid the risk of continued equipment operation due to missed detections.

[0098] In one feasible implementation, refer to Figure 5 After determining that the three-phase motor has a phase-to-phase short-circuit fault, the method further includes:

[0099] Step S410: Calculate the current deviation value based on the current ratio and the preset threshold, and perform harmonic analysis processing on the collected current waveform data to obtain the total harmonic distortion rate data.

[0100] Step S420: Calculate the short-circuit resistance value based on the current deviation value and the total harmonic distortion rate data using a preset short-circuit resistance mapping model;

[0101] Step S430: Compare the short-circuit resistance value with the multi-level preset warning threshold range, and perform a graded warning operation based on the comparison result.

[0102] In this embodiment, the current deviation value is the difference between the actual current ratio and a preset threshold. It can be calculated using absolute value or percentage difference to quantify the degree of deviation from the short-circuit fault. The total harmonic distortion rate (THC) data refers to the ratio of harmonic components to the fundamental component in the current waveform. This can be achieved through spectral analysis of the current waveform using a fast Fourier transform algorithm, reflecting the severity of current distortion. The short-circuit resistance mapping model establishes the correspondence between current deviation, harmonic distortion rate, and short-circuit resistance value. This can be achieved using polynomial fitting based on experimental data or a machine learning regression model, converting electrical characteristics into physical parameters. The multi-level preset warning threshold range refers to dividing resistance value intervals into different severity levels. For example, it can be set to three levels: Level 1 warning, Level 2 alarm, and Level 3 fault, with each level corresponding to a different response strategy.

[0103] In this embodiment, upon detecting a phase-to-phase short-circuit fault, the current deviation value is first calculated by comparing the current ratio with a threshold value. This value reflects the degree of abnormality in the short-circuit current. Simultaneously, harmonic analysis is performed on the current waveform, and the total harmonic distortion rate (THD) is extracted as a quantitative indicator of current distortion. These two parameters are input into a short-circuit resistance mapping model, and the actual short-circuit resistance value is calculated using a preset mathematical relationship. This resistance value is then compared with a multi-level preset warning threshold range, and a tiered warning operation is executed based on the comparison results. For example, when the warning threshold is divided into three levels, a Level 1 warning indicates an early short-circuit sign but has not yet affected operation; only a warning signal needs to be reported. A Level 2 warning indicates that the short circuit has caused performance degradation, requiring limiting the motor output power to avoid overload. A Level 3 fault indicates that the short circuit has caused a serious safety hazard, requiring immediate triggering of a protection mechanism to cut off the power supply.

[0104] In this embodiment, by combining current deviation and harmonic distortion rate to calculate the short-circuit resistance value, the fault state can be accurately assessed. Furthermore, the response strategy is dynamically adjusted based on the different threshold ranges of the resistance value, solving the problems of misoperation or delayed response caused by the single-parameter processing of traditional detection methods. Thus, this application achieves accurate quantitative assessment of phase-to-phase short-circuit faults and dynamically triggers a graded early warning mechanism based on the short-circuit resistance value. This allows maintenance personnel to take targeted measures according to the severity of the fault, avoiding over-protection or under-protection caused by a single threshold judgment, effectively improving motor operation safety and fault handling efficiency.

[0105] In one feasible implementation, the multi-level preset warning threshold range includes a first-level warning threshold range, a second-level alarm threshold range, and a third-level fault threshold range. The step of comparing the short-circuit resistance value with the multi-level preset warning threshold range and performing graded warning operations based on the comparison results includes: reporting a first warning signal when the short-circuit resistance value is within the first-level warning threshold range; reporting a second warning signal and limiting the maximum output power of the three-phase motor to below a preset power when the short-circuit resistance value is within the second-level alarm threshold range; and reporting a third warning signal and executing corresponding safety protection strategies when the short-circuit resistance value is within the third-level fault threshold range.

[0106] In this embodiment, the multi-level preset warning threshold range refers to multiple warning level intervals divided according to the short-circuit resistance value. Specifically, different threshold ranges can be set using experimental data or historical fault records to distinguish the severity of short-circuit faults. The first-level warning threshold range refers to the interval where the short-circuit resistance value is in a slightly abnormal state. Specifically, it can be a threshold range higher than the normal resistance value but not reaching a dangerous level, used to trigger an initial warning. The second-level alarm threshold range refers to the interval where the short-circuit resistance value is in a moderately abnormal state. Specifically, it can be a value range where the resistance value further decreases, used to trigger power limiting operation. The third-level fault threshold range refers to the interval where the short-circuit resistance value is in a severely abnormal state. Specifically, it can be a value close to zero or significantly deviating from the safe range, used to trigger emergency protection actions. The first warning signal is a primary alarm used to indicate potential risks, specifically implemented using indicator lights or low-priority alarm information. The second warning signal is a medium-level alarm requiring immediate intervention, specifically implemented using audible and visual alarms combined with control system linkage. The third warning signal is an emergency shutdown command, specifically implemented by cutting off the power supply or activating the backup protection device. The preset power refers to the upper limit of safe operation set according to the rated power of the motor. Specifically, it can be a value range of 50% to 80% of the rated power to avoid overload damage. The safety protection strategy refers to the emergency measures to prevent the fault from escalating, which can be achieved by means of power failure protection, mechanical braking, or switching to a backup motor.

[0107] In this embodiment, when the detected short-circuit resistance value is within the first-level warning threshold range, the system automatically reports a first warning signal, prompting the operator to check the motor status. If the short-circuit resistance is within the second-level alarm threshold range, the system reports a second warning signal and simultaneously limits the motor output power to below a preset power through the control circuit, reducing the risk of winding overheating. When the short-circuit resistance is within the third-level fault threshold range, the system immediately reports a third warning signal and triggers a safety protection strategy to force a shutdown, preventing equipment damage. This process ensures the timeliness and accuracy of warning and protection operations by taking corresponding measures at different fault stages.

[0108] In this embodiment, by matching the short-circuit resistance value with multiple threshold levels, differentiated responses can be implemented according to the severity of the short-circuit fault. Early warnings are given in the minor abnormal stage, providing maintenance personnel with a time window for handling; output power is limited in the moderate abnormal stage to slow down the rate of fault deterioration; and the risk source is immediately cut off in the severe fault stage to prevent equipment damage and ensure equipment safety.

[0109] In one feasible implementation, refer to Figure 6 Before step S100, the method further includes:

[0110] Step S021: Control the three-phase drive circuit to apply voltage pulses to any phase winding of the three-phase motor, and collect the initial slope of the corresponding current response;

[0111] Step S022: If the initial slope data exceeds the preset slope threshold, then step S100 is executed.

[0112] In this embodiment, the voltage pulse refers to a short-time voltage signal output by the three-phase drive circuit. Specifically, it can be generated using pulse width modulation (PWM) technology, such as a square wave signal with a pulse width of 50 to 200 microseconds, used to excite a transient current response in the winding. The initial slope refers to the rate of increase of the current over time. Specifically, it can be achieved by acquiring the current waveform through a current sampling circuit and then extracting the slope value during the current rise phase using differential calculation or fitting algorithms. The preset slope threshold is a critical value pre-set based on the current response characteristics of the motor under normal conditions. For example, a dynamic threshold database can be established based on the motor model, winding parameters, and temperature conditions to determine whether abnormal conduction occurs. This feature, by predicting the winding conduction state, avoids direct excitation when a short circuit already exists in the winding, thus preventing detection failure.

[0113] In this embodiment, before the motor starts, the controller sends a pulse control signal to the three-phase drive circuit, causing it to output a voltage pulse of a specific amplitude to the target phase winding. The current sampling circuit collects the current data of the winding in real time and calculates the initial slope of the current rising phase through the microprocessor. If the initial slope exceeds a preset threshold, it indicates an abnormal decrease in winding impedance, which may pose a risk of phase-to-phase short circuit. At this time, the subsequent phase-to-phase short circuit detection process is triggered. For example, if the preset slope threshold is 10A / ms and the measured initial slope reaches 15A / ms, it is determined to be an abnormal state, and the excitation and detection process in step S100 is initiated.

[0114] In some specific implementations, the amplitude of the voltage pulse can be set to 5% to 20% of the rated voltage. For example, a pulse voltage of 19V to 76V can be used in a 380V system to avoid impacting the normal windings. The initial slope can be calculated using the difference method between adjacent sampling points. For example, after acquiring current data at a sampling frequency of 1kHz, the average rate of change of the first 10 sampling points can be taken as the initial slope. The preset slope threshold can be dynamically adjusted according to the motor operating temperature. For example, in high-temperature environments, the preset slope threshold can be appropriately reduced to compensate for the effect of temperature on winding resistance.

[0115] In this embodiment, by performing pre-testing and slope analysis, abnormal states can be quickly identified in the early stages of detection, avoiding invalid detection operations. This also reduces system power consumption and hardware wear risks, enabling pre-screening of motor winding conditions and effectively distinguishing between normal windings and potential short-circuit faults. This ensures that subsequent detection processes are only initiated when necessary. This not only shortens the overall detection time but also improves the safety of the detection system, preventing equipment damage or malfunctions caused by directly stimulating short-circuited windings.

[0116] In this embodiment, the three-phase motor phase-to-phase short circuit detection method excites one phase winding of the three-phase motor by inputting a sampling voltage and obtaining the current data of the non-excited phase winding. The fault is determined by calculating the ratio and comparing it with a threshold. This solves the problems of traditional detection methods, such as inability to quickly monitor online, low efficiency, and inaccurate positioning. It realizes rapid online detection, automatic judgment, and accurate positioning of phase-to-phase short circuit faults in three-phase motors, improving detection efficiency and safety.

[0117] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the three-phase motor phase-to-phase short circuit detection method of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0118] This application also provides a three-phase motor phase-to-phase short-circuit detection system; please refer to [reference needed]. Figure 7 The three-phase motor phase-to-phase short circuit detection system includes: a memory 10, a processor 20, and a three-phase motor phase-to-phase short circuit detection program stored in the memory 10 and executable on the processor 20. The three-phase motor phase-to-phase short circuit detection program is configured to implement the steps of the three-phase motor phase-to-phase short circuit detection method.

[0119] The three-phase motor phase-to-phase short-circuit detection system provided in this application, employing the three-phase motor phase-to-phase short-circuit detection method described in the above embodiments, can improve the safety and efficiency of three-phase motor phase-to-phase short-circuit fault detection. Compared with the prior art, the beneficial effects of the three-phase motor phase-to-phase short-circuit detection system provided in this application are the same as those of the three-phase motor phase-to-phase short-circuit detection method provided in the above embodiments, and other technical features of the three-phase motor phase-to-phase short-circuit detection system are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0120] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A method of detecting a phase-to-phase short circuit in a three-phase electric machine, characterized in that, The three-phase motor phase-to-phase short circuit detection method comprises: Step S100, inputting a sampling voltage to a phase winding of a three-phase motor for excitation to obtain current data of a non-excited phase winding; Step S200, performing ratio calculation on the current data to obtain a corresponding current ratio, and comparing the current ratio with a preset threshold to obtain corresponding fault determination data; For the non-excited phase winding, the above steps S100 and S200 are repeatedly executed until the three-phase motor is determined to have no phase-to-phase short circuit fault, to have a phase-to-phase short circuit fault, or to complete positioning of the phase-to-phase short circuit fault based on the fault determination data; The complete execution of the above steps S100 and S200 is taken as a detection cycle, and a first detection cycle and a second detection cycle are sequentially executed; the positioning of the phase-to-phase short circuit fault of the three-phase motor based on the fault determination data comprises: If the fault determination data based on the first detection cycle determines that the three-phase motor has no phase-to-phase short circuit fault, and the fault determination data based on the second detection cycle determines that the three-phase motor has a phase-to-phase short circuit fault, it is determined that the phase-to-phase short circuit fault exists between the excited phase winding and the non-excited phase winding of the second detection cycle; If the fault determination data based on the first detection cycle determines that the three-phase motor has a phase-to-phase short circuit fault, and the fault determination data based on the second detection cycle determines that the three-phase motor has no phase-to-phase short circuit fault, it is determined that the phase-to-phase short circuit fault exists between the excited phase winding and the non-excited phase winding of the first detection cycle.

2. The method of claim 1, wherein, The three-phase motor is connected with a three-phase drive circuit and a three-phase current sampling circuit respectively, and the step S100 comprises: Performing proportional step-down processing on bus voltage data based on the three-phase drive circuit to obtain the sampling voltage; Inputting the sampling voltage data to a phase winding of the three-phase motor for excitation, and continuing for a preset time length; Obtaining current data of a non-excited phase winding based on the three-phase current sampling circuit.

3. The method for detecting phase-to-phase short circuits in a three-phase motor as described in claim 2, characterized in that, The preset threshold comprises a preset lower limit threshold and a preset upper limit threshold, and the step S200 comprises: Performing ratio calculation on the current data to obtain a corresponding current ratio; Comparing the current ratio with the preset lower limit threshold and the preset upper limit threshold respectively, and if the current ratio is lower than the preset lower limit threshold or the current ratio is higher than the preset upper limit threshold, it is determined that the three-phase motor has a phase-to-phase short circuit fault based on the fault determination data.

4. The method for detecting phase-to-phase short circuits in a three-phase motor as described in claim 3, characterized in that, Before the step S100, the method further comprises: Obtaining current temperature data of the three-phase motor winding; Querying a pre-stored reference database to obtain a dynamic threshold corresponding to the temperature data, and updating the dynamic threshold as the preset threshold.

5. The method of claim 1, wherein, The positioning of the phase-to-phase short circuit fault of the three-phase motor based on the fault determination data further comprises: If the fault determination data based on the first detection cycle and the second detection cycle both determines that the three-phase motor has a phase-to-phase short circuit fault, a third detection cycle is executed; If the fault determination data based on the third detection cycle determines that the three-phase motor has no phase-to-phase short circuit fault, it is determined that the phase-to-phase short circuit fault exists between the excited phase winding of the first detection cycle and the excited phase winding of the second detection cycle; If the fault determination data based on the third detection cycle determines that the three-phase motor has an inter-phase short circuit fault, it is determined that the three-phase motor has multiple inter-phase short circuit faults.

6. The method of claim 1, wherein, After determining that the three-phase motor has an inter-phase short circuit fault, the method further comprises: calculating a current deviation value based on the current ratio and a preset threshold value, and performing harmonic analysis processing on the collected current waveform data to obtain total harmonic distortion rate data; According to the current deviation value and the total harmonic distortion rate data, the short circuit resistance numerical data is calculated through a preset short circuit resistance mapping model; The short circuit resistance numerical data is compared with a multi-level preset warning threshold range, and a hierarchical warning operation is performed according to the comparison result.

7. The method for detecting phase-to-phase short circuits in a three-phase motor as described in claim 6, characterized in that, The multi-level preset warning threshold range includes a first warning threshold range, a second warning threshold range and a third fault threshold range, and the step of comparing the short circuit resistance numerical data with the multi-level preset warning threshold range and performing a hierarchical warning operation according to the comparison result comprises: When the short circuit resistance numerical data is in the first warning threshold range, a first warning signal is reported; When the short circuit resistance numerical data is in the second warning threshold range, a second warning signal is reported, and the maximum output power of the three-phase motor is limited below a preset power; When the short circuit resistance numerical data is in the third fault threshold range, a third warning signal is reported, and a corresponding safety protection strategy is executed.

8. The method for detecting phase-to-phase short circuits in a three-phase motor as described in claim 2, characterized in that, Before step S100, the method further comprises: controlling the three-phase drive circuit to apply a voltage pulse to any phase winding of the three-phase motor, and collecting the initial slope of the corresponding current response; If the initial slope data exceeds a preset slope threshold, the step S100 is executed.

9. A three-phase motor interphase short circuit detection system characterized by, The system comprises a memory, a processor and a three-phase motor inter-phase short circuit detection program stored on the memory and executable on the processor, the three-phase motor inter-phase short circuit detection program being configured to implement the steps of the three-phase motor inter-phase short circuit detection method according to any one of claims 1 to 8.

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