Motor early inter-turn short circuit fault detection system based on six-vector injection

Abstract

The application discloses a motor early inter-turn short circuit fault detection system based on six-vector injection, which comprises the following steps: S1, generating a pulse excitation signal of a first voltage vector through an inverter, collecting common-mode switching oscillation current i of the motor after the signal is injected cm ; S2, extracting current effective value I corresponding to a characteristic frequency band in each single switching oscillation waveform MF ; S3, obtaining current effective average value corresponding to the first voltage vector; S4, generating pulse excitation signals of the second to sixth voltage vectors in sequence according to the above steps S1-S4, and the voltage pulse excitation signals of the six different voltage vectors constitute a complete electrical angle rotation period; and S5, performing average calculation to obtain a multi-vector average insulation state index; the application has high detection sensitivity, effectively overcomes the interference of rotor mechanical rotation on static fault detection in a detection working condition, and has stable anti-interference performance.

Description

Technical Field

[0001] This invention relates to the field of fault monitoring of permanent magnet synchronous motors, and specifically to a motor early-stage inter-turn short-circuit fault detection system based on six-vector injection. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in key fields such as new energy vehicles, rail transit, and industrial drives due to their high efficiency, high power density, and excellent control performance. Among motor fault types, stator winding insulation faults account for a large proportion, with inter-turn short circuit faults being particularly common and dangerous. These faults are usually caused by local insulation aging, overvoltage surges, or thermal stress accumulation, and are characterized by their high degree of concealment and rapid development. If not detected in the early stages, minor inter-turn insulation defects can evolve into phase-to-phase or phase-to-ground short circuits in a very short time, leading to serious equipment damage or even systemic accidents. Therefore, early detection of inter-turn short circuit faults in the stator windings of PMSMs is of great significance.

[0003] A domestic invention patent application with publication number CN115494388A discloses a method for diagnosing stator inter-turn short-circuit faults by detecting electromagnetic torque. This method uses a current transformer to obtain the stator three-phase current value, calculates the torque parameters and performs Fourier decomposition to obtain the percentage of the second harmonic and fundamental components, and compares them in real time for fault diagnosis. However, it requires high sampling accuracy for voltage and current.

[0004] A domestic invention patent application with publication number CN113064073A discloses a method for diagnosing inter-turn short-circuit faults in permanent magnet synchronous motors based on residual current. This method estimates the current residual in the two-phase rotating coordinate system of the permanent magnet synchronous motor using a Luneburger observer, and then transforms it into the stator current residual in the three-phase stationary coordinate system using a transformation matrix. The amplitude change of the stator current residual is observed to determine the inter-turn short circuit. This method requires no additional hardware and effectively detects inter-turn faults. However, the observer's performance is highly dependent on the motor parameters. Different operating conditions of the motor will change the parameters, leading to a decrease in detection sensitivity.

[0005] A domestic invention patent application with publication number CN121114757A discloses a method for diagnosing inter-turn short-circuit faults in permanent magnet synchronous motors based on high-frequency negative sequence components. This method extracts high-frequency components of voltage and current through rotating high-frequency current injection and a second-order generalized integrator, and compares the fault characteristic quantities with dynamic thresholds to achieve fault detection. However, this invention does not consider the influence of changes in the motor rotor position on the characteristic quantities, which weakens the ability to detect weak inter-turn faults. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a motor early inter-turn short circuit fault detection system based on six-vector injection, which has high detection sensitivity and solves the problem that traditional methods are difficult to detect local inter-turn short circuit faults with weak response. At the same time, it effectively overcomes the interference caused by rotor mechanical rotation on static fault detection during the detection process, and has stable anti-interference ability, thus having high engineering practicality.

[0007] The technical solution adopted in this invention is as follows:

[0008] An early-turn inter-turn short-circuit fault detection system for a motor based on six-vector injection, wherein the inverter is connected between a DC power supply and a permanent magnet synchronous motor, includes the following steps:

[0009] S1. By selectively turning on or off each switch in the inverter, a pulse excitation signal for the first voltage vector is generated. The common-mode switching oscillation current i of the motor after this signal injection is acquired. cm ;

[0010] S2, from the motor common-mode switch oscillation current i cm The continuous-mode oscillation current located in the characteristic frequency band is extracted, and several single-switching oscillation waveforms are obtained. The effective value of the current I corresponding to the characteristic frequency band in each single-switching oscillation waveform is extracted. MF ;

[0011] S3. Extract the effective current value I from each single switching oscillation waveform. MF By performing an average calculation, the effective average current value corresponding to the first voltage vector is obtained. ;

[0012] S4. Following steps S1-S4 above, pulse excitation signals for the second to sixth voltage vectors are generated sequentially, and the effective average current values ​​corresponding to the second to sixth voltage vectors are calculated sequentially. The voltage pulse excitation signals of the six different voltage vectors constitute a complete electrical angle rotation cycle;

[0013] S5. The effective average value of the current corresponding to the six different voltage vectors above. Averaging calculations are performed to obtain multi-vector average insulation condition indices. Based on this multi-vector average insulation state index The early inter-turn short-circuit fault status of the motor is assessed.

[0014] Preferably, the pulse excitation signals of the first to sixth voltage vectors are spatially separated by 60° electrical angles.

[0015] Preferably, the inverter includes:

[0016] The first and fourth switching transistors are connected between the positive and negative terminals of the DC power supply, and the connection point between the first and fourth switching transistors is connected to the A-phase winding of the motor.

[0017] The third and sixth switching transistors are connected between the positive and negative terminals of the DC power supply, and the connection point between the third and sixth switching transistors is connected to the B-phase winding of the motor.

[0018] The fifth and second switching transistors are connected between the positive and negative terminals of the DC power supply, and the connection point between the fifth and second switching transistors is connected to the C-phase winding of the motor.

[0019] By selectively turning on or off the above-mentioned switching transistors, voltage pulse excitation signals of the six different voltage vectors are generated in sequence.

[0020] Preferably, when the first switch, the sixth switch, and the second switch are in the on state, and the remaining switches are in the off state, a pulse excitation signal for the first voltage vector is generated.

[0021] When the first, third, and second switching transistors are in the on state and the remaining switching transistors are in the off state, a pulse excitation signal for the second voltage vector is generated.

[0022] When the fourth, third, and second switches are in the on state and the remaining switches are in the off state, a pulse excitation signal for the third voltage vector is generated.

[0023] When the fourth, third, and fifth switches are in the on state and the remaining switches are in the off state, a pulse excitation signal for the fourth voltage vector is generated.

[0024] When the fourth, sixth, and fifth switches are in the on state and the remaining switches are in the off state, a pulse excitation signal for the fifth voltage vector is generated.

[0025] When the first, sixth, and fifth switches are in the ON state and the remaining switches are in the OFF state, a pulse excitation signal for the sixth voltage vector is generated.

[0026] Preferably, a high-frequency current sensor is non-contactly installed on the motor side by passing a three-phase cable through it, for collecting the common-mode switching oscillation current i of the motor. cm .

[0027] In step S2, the effective value of the extracted current I is... MF Previously, several single-switching oscillation waveforms were pre-bandpass filtered using a high-order filter; then, the effective current value I corresponding to the characteristic frequency band in each single-switching oscillation waveform was extracted using a Fast Fourier Transform (FFT). MF.

[0028] Preferably, in step S3, the effective average value of the current corresponding to each voltage vector is... The calculation formula is as follows:

[0029] In the formula, k is the sequence number of the switching oscillation waveform, and N is the number of the switching oscillation waveforms.

[0030] Quantity, I MF (k) represents the effective value of the current extracted from the characteristic frequency band of the k-th single-switch oscillation waveform;

[0031] In step S5, the multi-vector average insulation state index The calculation formula is as follows:

[0032] In the formula, j is the voltage vector index corresponding to the pulse excitation signal.

[0033] Preferably, when detecting early-stage inter-turn short-circuit faults in a motor, the multi-vector average insulation condition index calculated under the detection conditions is used. The multi-vector average insulation condition index calculated under normal motor conditions A comparison was made to determine the early inter-turn short-circuit fault status of the motor; among which, the multi-vector average insulation status index was used. The larger the value, the more severe the early inter-turn short circuit fault of the motor.

[0034] Preferably, the motor rotor is rotated to different mechanical angles, and the multi-vector average insulation state index corresponding to each mechanical angle is calculated according to steps S1-S5 above. Among them, by comparing the multi-vector average insulation state index corresponding to different mechanical angles... The difference is used to evaluate and verify the impact of rotor position changes on the variability of characteristic parameters.

[0035] Preferably, under the same rotor position, taps are drawn from inside the winding, and a turn near the end is connected to cement resistors of different resistance values ​​to simulate different degrees of early inter-turn short-circuit faults in the motor; according to steps S1-S5 above, the multi-vector average insulation condition index corresponding to different degrees of early inter-turn short-circuit faults in the motor is calculated. Among them, by comparing the multi-vector average insulation status index corresponding to different degrees of early inter-turn short-circuit faults in motors. The difference is used to assess the sensitivity of verifying different inter-turn short-circuit fault levels.

[0036] This application directly utilizes an inverter to generate a specific sequence of pulse excitation signals, resulting in high detection sensitivity and solving the problem of weak response in traditional methods for detecting local inter-turn short-circuit faults. Crucially, this application controls the inverter to sequentially inject six voltage vectors at different electrical angles, forming a complete electrical angle rotation cycle (i.e., 360°). This transforms the randomness of the rotor's actual mechanical angle into a systematic scan of the excitation voltage in the electrical angle space, effectively overcoming the interference caused by rotor mechanical rotation (i.e., rotor position change) on static fault detection during the detection process. It exhibits stable anti-interference capabilities and therefore high engineering practicality.

[0037] Based on the above, this application also specifically uses a high-frequency current sensor to collect the switching oscillation current during motor operation in a non-contact manner, without the need for additional current sensors. This improves the accuracy and reliability of switching oscillation current detection and does not affect the actual operation of the motor. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of the motor early-stage inter-turn short-circuit fault detection system based on six-vector injection according to a specific embodiment of this application;

[0039] Figure 2 This is a schematic diagram of the early inter-turn short circuit fault detection process of a motor based on six-vector injection in a specific embodiment of this application;

[0040] Figure 3 This is a schematic diagram of the electrical principle structure of the experimental platform built in a specific embodiment of this application;

[0041] Figure 4 Is adopted Figure 3 The common-mode switching oscillation current i of the motor was collected when the experimental platform shown was used to conduct an inter-turn short-circuit fault experiment at the same rotor position. cm Original waveform;

[0042] Figure 5 Yes Figure 4 The common-mode switching oscillation current i of the motor was collected. cm The spectrum after FFT analysis;

[0043] Figure 6 Is adopted Figure 3 The experimental platform shown compares the effective current values ​​calculated under different inter-turn short-circuit fault conditions and normal conditions at the same rotor location; among them... Figure 6 The left-hand vertical axis represents the calculated multi-vector average insulation state index. (that is) Figure 6 The marked "RMS value of current") Figure 6The right-hand vertical axis represents the multi-vector average insulation condition index corresponding to different inter-turn short-circuit fault states compared to the normal state. The ratio (i.e.) Figure 6 The marked "Fault State / Normal State Current RMS Value");

[0044] Figure 7 Is adopted Figure 3 When the experimental platform shown conducts testing experiments at different rotor positions under normal conditions, the common-mode switching oscillation current i of the motor is collected. cm The spectrum after FFT analysis;

[0045] Figure 8 Is adopted Figure 3 The experimental platform shown compares the effective current values ​​calculated under different rotor positions and different inter-turn short-circuit fault conditions as well as under normal conditions; among them... Figure 8 The effective value of the current in the figure represents the calculated multi-vector average insulation condition index. , Figure 8 The angles marked in the diagram represent different rotor positions. Detailed Implementation

[0046] Please refer to the above. Figure 1 and Figure 2 As shown, this embodiment proposes an early-stage inter-turn short-circuit fault detection system for motors based on six-vector injection. The inverter is connected to the DC power supply V. DC Between the inverter and the permanent magnet synchronous motor; preferably, in this embodiment, the inverter includes: a first switch T1 and a fourth switch T4 connected between the positive and negative terminals of the DC power supply, the connection point between the first switch T1 and the fourth switch T4 being connected to the A-phase winding of the motor; a third switch T3 and a sixth switch T6 connected between the positive and negative terminals of the DC power supply, the connection point between the third switch T3 and the sixth switch T6 being connected to the B-phase winding of the motor; a fifth switch T5 and a second switch T2 connected between the positive and negative terminals of the DC power supply, the connection point between the fifth switch T5 and the second switch T2 being connected to the C-phase winding of the motor;

[0047] Preferably, a high-frequency current sensor (i.e., as...) is used. Figure 1 The "Switch Oscillation Current Acquisition Module" shown is threaded through a three-phase cable (i.e., Figure 1 The three-phase interconnection method shown is used to non-contactly install the device on the motor side to collect the motor common-mode switching oscillation current i. cm In the actual operation of permanent magnet synchronous motors, single-phase overlays are usually also configured (such as...). Figure 1The high-frequency current sensor (shown) is used to detect the current of a single-phase winding of a motor. These are common knowledge to those skilled in the art and are not considered as innovative content of this application, so they will not be elaborated on in detail.

[0048] In this embodiment, the detection process of the motor early-stage inter-turn short-circuit fault detection system as described above includes the following steps:

[0049] S1. By selectively turning on or off each switch in the inverter, a pulse excitation signal of the first voltage vector V1 is generated. The motor common-mode switching oscillation current i after this signal injection is acquired by the switching oscillation current acquisition module. cm This step corresponds to Figure 2 The figure shows "Injecting V1 vector and acquiring common-mode switching oscillation current i". cm ”;

[0050] S2, The common-mode switching oscillation current i of the motor is extracted through the feature parameter extraction module. cm The continuous-mode oscillation current located in the characteristic frequency band is extracted, and several single-switching oscillation waveforms are obtained. The effective value of the current I corresponding to the characteristic frequency band (also known as the "sensitive frequency band") in each single-switching oscillation waveform is extracted. MF This step corresponds to Figure 2 The figure shows "Extracting the effective value of the current corresponding to the sensitive frequency band I". MF ”;

[0051] Preferably, in step S2, the effective value of the extracted current I is... MF Previously, several single-cycle switching oscillation waveforms were pre-bandpass filtered using a high-order filter. Specifically, a Simulink high-order filter was used to perform bandpass filtering on the obtained single-cycle oscillation waveforms to improve detection sensitivity and reliability. Then, the effective current value I corresponding to the characteristic frequency band in each single-cycle switching oscillation waveform was extracted using a Fast Fourier Transform (FFT) method. MF It should be noted that the characteristic frequency bands involved in the entire application refer to the frequency bands located at and near the parallel resonant point frequency. This part belongs to the common knowledge of Fast Fourier Transform (FFT) extraction and processing, and this part itself is not considered as the innovative content of this application. Therefore, this application will not elaborate on it.

[0052] S3. The effective current value I extracted from each single-switch oscillation waveform is processed by the feature parameter processing module. MF By performing an average calculation, the effective average current value corresponding to the first voltage vector is obtained. This step corresponds to Figure 2 The figure shows that "averaging the effective values ​​of the current obtained from multiple oscillating currents yields..." ”;

[0053] Preferably, in step S3, the effective average current corresponding to each voltage vector is... The calculation formula is as follows:

[0054] In the formula, k is the sequence number of the switching oscillation waveform, and N is the number of the switching oscillation waveforms.

[0055] Quantity, I MF (k) represents the effective value of the current extracted from the characteristic frequency band of the k-th single-switch oscillation waveform;

[0056] S4. Following steps S1-S4 above, pulse excitation signals for the second to sixth voltage vectors V2-V6 are generated sequentially, and the effective average current values ​​corresponding to the second to sixth voltage vectors are calculated sequentially. (correspond Figure 2 The “Is the injection of the six vectors complete? No, switch to vectors V2-V6” shown means that the voltage pulse excitation signals of the six different voltage vectors constitute a complete electrical angle rotation cycle; wherein, preferably, in this embodiment, the pulse excitation signals of the first to sixth voltage vectors V1-V6 are spatially separated by 60° electrical angles.

[0057] In implementation, by selectively turning on or off the first to sixth switches as described above, six voltage pulse excitation signals with different voltage vectors are generated sequentially. Specifically, preferably, in this embodiment, when the first switch T1, the sixth switch T6, and the second switch T2 are in the on state, and the remaining switches are in the off state, a pulse excitation signal for the first voltage vector V1 is generated; when the first switch T1, the third switch T3, and the second switch T2 are in the on state, and the remaining switches are in the off state, a pulse excitation signal for the second voltage vector V2 is generated; when the fourth switch T4, the third switch T3, and the second switch T2 are in the on state, and the remaining switches are in the off state, a pulse excitation signal for the third voltage vector V3 is generated; when the fourth switch T4, the third switch T3, and the second switch T2 are in the on state, and the remaining switches are in the off state, a pulse excitation signal for the third voltage vector V3 is generated; when the sixth switch T6, the sixth switch T6, and the second switch T2 are in the on state, and the remaining switches are in the off state, a pulse excitation signal for the third voltage vector V3 is generated; when the sixth switch T4 ... When four switches T4, T3, and T5 are turned on, and the remaining switches are turned off, a pulse excitation signal for the fourth voltage vector V4 is generated. When four switches T4, T6, and T5 are turned on, and the remaining switches are turned off, a pulse excitation signal for the fifth voltage vector V5 is generated. When first switches T1, T6, and T5 are turned on, and the remaining switches are turned off, a pulse excitation signal for the sixth voltage vector V6 is generated. Of course, those skilled in the art can also generate the required six different voltage vector voltage pulse excitation signals by selectively turning on or off the switches in other sequences, and this application does not limit this to a single one.

[0058] S5. The effective average current corresponding to the six different voltage vectors above is calculated using the inter-turn insulation condition assessment module. Averaging calculations are performed to obtain multi-vector average insulation condition indices. That is, corresponding Figure 2 The average of the six vector results shown is used to obtain one angle index. Based on this multi-vector average insulation status index Assess the early inter-turn short-circuit fault status of the motor;

[0059] Preferably, in step S5, the multi-vector average insulation state index The calculation formula is as follows:

[0060] In the formula, j is the voltage vector index corresponding to the pulse excitation signal.

[0061] Preferably, when detecting early-stage inter-turn short-circuit faults in a motor, the multi-vector average insulation condition index calculated under the detection conditions is used. The multi-vector average insulation condition index calculated under normal motor conditions A comparison was made to determine the early inter-turn short-circuit fault status of the motor; among which, the multi-vector average insulation status index was used. The larger the value, the more severe the early inter-turn short circuit fault of the motor.

[0062] Preferably, in this embodiment, please refer to [reference needed]. Figure 2 As shown, the motor rotor is rotated to different mechanical angles (corresponding to...) Figure 2 The message "Is the preset angle completed? No, the rotor rotates to the next angle" indicates that, following steps S1-S5 above, the multi-vector average insulation state index corresponding to different mechanical angles is calculated. Among them, by comparing the multi-vector average insulation state index corresponding to different mechanical angles... The difference is used to evaluate and verify the impact of rotor position changes on the fluctuation of characteristic parameters (i.e., the resistance to interference of rotor angle).

[0063] Preferably, in this embodiment, under the same rotor position, a tap is drawn from inside the winding, and a cement resistor R with a different resistance value is selected near the end. f Simulate early-stage inter-turn short-circuit faults of motors of varying degrees; calculate the multi-vector average insulation status index corresponding to different degrees of early-stage inter-turn short-circuit faults of motors according to steps S1-S5 above. Among them, by comparing the multi-vector average insulation status index corresponding to different degrees of early inter-turn short-circuit faults in motors. The difference is used to assess the sensitivity of verification for different inter-turn short-circuit fault levels;

[0064] The above comparative analysis is used to evaluate and verify the impact of rotor position changes on the fluctuation of characteristic parameters and the sensitivity to different inter-turn short-circuit fault degrees, i.e., the corresponding Figure 2 The description states, "Evaluate rotor position fluctuations and inter-turn insulation condition."

[0065] To enable those skilled in the art to better understand the technical solutions of this invention, based on the above embodiments, the following specific embodiments will be proposed in conjunction with the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort should fall within the scope of protection of this invention.

[0066] In the following specific embodiments, the experimental system is as follows: Figure 3 As shown, the system consists of a DC power supply, an inverter driven by a DSP controller (whose structure and operation are the same as described above in this embodiment), a high-frequency current sensor, and the motor under test. The motor under test is a 380 V, 3 kW star-connected permanent magnet synchronous motor (PMSM), and its basic parameter configuration is shown in Table 1 below.

[0067] Table 1

[0068] Rated power 3kW Rated speed 1500 r / min Rated voltage 380 V Rated current 5.5 A Rated frequency 50 Hz Extreme number 4 Number of turns per phase 216

[0069] A Pico 5444D high-speed digital oscilloscope (sampling rate 125 MHz) was used. A high-frequency current sensor was installed at the output cable of the motor under test by means of three-phase and phase wire loops, and the experimental data was recorded by the sampling digital oscilloscope.

[0070] First, conduct an inter-turn short-circuit fault detection experiment at the same rotor location. The experimental procedure is as follows:

[0071] With the rotor in the same position, a tap is taken from inside the winding, and a turn is selected near the motor end (represented by: u = 1 / 216 = 0.47%, where u is the proportion of the faulty turn to the total number of turns) and connected to a cement resistor R of different resistance values. f (R) f (Ω = 10Ω, 5Ω, 1Ω, 0.1Ω) to simulate early-stage inter-turn short-circuit faults of varying degrees. It is particularly important to note that... Figure 5 , Figure 7 and Figure 8 The 0Ω marked in the figure indicates that there is no external cement resistor R. f , used to represent the normal state.

[0072] An inverter generates a specific sequence of six pulses, namely, six different voltage vectors V1-V6 pulse excitation signals as described above in this embodiment. High-frequency current sensors are then arranged in a three-phase loop configuration at the three-phase cable end of the motor to collect the common-mode switching oscillation current i of the motor. cm The obtained original waveform is as follows Figure 4 As shown;

[0073] Intercepting the common-mode switching oscillation current i of the motor cm Perform Fast Fourier Transform (FFT) analysis on the characteristic frequency bands and plot the spectrum of the characteristic frequency bands (parallel resonant point frequency is 300kHz) (see [link to relevant documentation]). Figure 5 (as shown)

[0074] pass Figure 5 This indicates that as the severity of the fault increases, the frequency near the parallel resonant point increases, and the resonant point shifts to the right.

[0075] Please see further. Figure 6 As shown, it displays the detection results under different inter-turn short-circuit fault conditions and normal conditions, through... Figure 6 As can be seen, with the severity of the fault, the multi-vector average insulation condition index... The larger the value, the more closely it corresponds to the multi-vector average insulation state index under normal conditions. The greater the difference.

[0076] Second, conduct inter-turn short-circuit fault detection experiments at different rotor positions. The experimental procedure is as follows:

[0077] First, following the procedure described in Part One, “Inter-turn short-circuit fault detection experiment at the same rotor position,” different rotor positions were tested sequentially under normal conditions (i.e., without an external cement resistor R). f The testing experiment involved changing the rotor's mechanical angle to 0°, 30°, 60°, and 90°. Figure 7 As shown, it can be observed that the amplitude at a specific frequency band in the spectrum (parallel resonant point frequency is 300kHz) changes periodically with the change of rotor position; this confirms that the change of rotor position will cause fluctuations in characteristic parameters, thereby affecting the accurate detection of early inter-turn short circuit faults.

[0078] Then, based on the different rotor positions set above, further different rotor positions were set with an angle variation range of 15°. Then, tests were performed under different inter-turn short-circuit fault conditions and normal conditions. The results can be found in [link to relevant documentation]. Figure 8 As shown; via Figure 8It can be seen that, using the six-vector pulse injection method proposed in this embodiment (i.e., based on six-vector injection), the fluctuation of the characteristic parameters of the same insulation state under different rotor positions can be basically controlled within 1.2%, wherein, simultaneously with external R f The detection sensitivity reaches approximately 1% under a fault condition of 10Ω, which demonstrates that this application has good position robustness and fault detection capability.

[0079] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0080] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A motor early-turn inter-turn short-circuit fault detection system based on six-vector injection, characterized in that, The inverter is connected between the DC power supply and the permanent magnet synchronous motor, including the following steps: S1. By selectively turning on or off each switch in the inverter, a pulse excitation signal for the first voltage vector is generated. The common-mode switching oscillation current i of the motor after this signal injection is acquired. cm ; S2, from the motor common-mode switch oscillation current i cm The continuous-mode oscillation current located in the characteristic frequency band is extracted, and several single-switching oscillation waveforms are obtained. The effective value of the current I corresponding to the characteristic frequency band in each single-switching oscillation waveform is extracted. MF ; S3. Extract the effective current value I from each single switching oscillation waveform. MF By performing an average calculation, the effective average current value corresponding to the first voltage vector is obtained. ; S4. Following steps S1-S4 above, pulse excitation signals for the second to sixth voltage vectors are generated sequentially, and the effective average current values ​​corresponding to the second to sixth voltage vectors are calculated sequentially. The voltage pulse excitation signals of the six different voltage vectors constitute a complete electrical angle rotation cycle; S5. The effective average value of the current corresponding to the six different voltage vectors above. Averaging calculations are performed to obtain multi-vector average insulation condition indices. Based on this multi-vector average insulation state index The early inter-turn short-circuit fault status of the motor is assessed.

2. The early-stage inter-turn short-circuit fault detection system for motors based on six-vector injection according to claim 1, characterized in that, The pulse excitation signals of the first to sixth voltage vectors are spatially separated by 60° electrical angles.

3. The early-stage inter-turn short-circuit fault detection system for motors based on six-vector injection according to claim 1 or 2, characterized in that, The inverter includes: The first and fourth switching transistors are connected between the positive and negative terminals of the DC power supply, and the connection point between the first and fourth switching transistors is connected to the A-phase winding of the motor. The third and sixth switching transistors are connected between the positive and negative terminals of the DC power supply, and the connection point between the third and sixth switching transistors is connected to the B-phase winding of the motor. The fifth and second switching transistors are connected between the positive and negative terminals of the DC power supply, and the connection point between the fifth and second switching transistors is connected to the C-phase winding of the motor. By selectively turning on or off the above-mentioned switching transistors, voltage pulse excitation signals of the six different voltage vectors are generated in sequence.

4. The early-stage inter-turn short-circuit fault detection system for motors based on six-vector injection according to claim 3, characterized in that, When the first switch, the sixth switch, and the second switch are in the on state, and the remaining switches are in the off state, the pulse excitation signal of the first voltage vector is generated. When the first, third, and second switching transistors are in the on state and the remaining switching transistors are in the off state, a pulse excitation signal for the second voltage vector is generated. When the fourth, third, and second switches are in the on state and the remaining switches are in the off state, a pulse excitation signal for the third voltage vector is generated. When the fourth, third, and fifth switches are in the on state and the remaining switches are in the off state, a pulse excitation signal for the fourth voltage vector is generated. When the fourth, sixth, and fifth switches are in the on state and the remaining switches are in the off state, a pulse excitation signal for the fifth voltage vector is generated. When the first, sixth, and fifth switches are in the ON state and the remaining switches are in the OFF state, a pulse excitation signal for the sixth voltage vector is generated.

5. The early-stage inter-turn short-circuit fault detection system for motors based on six-vector injection according to claim 1 or 2, characterized in that, A high-frequency current sensor is non-contactly installed on the motor side by passing a three-phase cable through it, for collecting the common-mode switching oscillation current i of the motor. cm .

6. The early-stage inter-turn short-circuit fault detection system for motors based on six-vector injection according to claim 1 or 2, characterized in that, In step S2, the effective value of the extracted current I is... MF Previously, several single-switching oscillation waveforms were pre-bandpass filtered using a high-order filter; then, the effective current value I corresponding to the characteristic frequency band in each single-switching oscillation waveform was extracted using a Fast Fourier Transform (FFT). MF .

7. The early-stage inter-turn short-circuit fault detection system for motors based on six-vector injection according to claim 1 or 2, characterized in that, In step S3, the effective average current corresponding to each voltage vector is... The calculation formula is as follows: In the formula, k is the sequence number of the switching oscillation waveform, and N is the number of the switching oscillation waveforms. Quantity, I MF (k) represents the effective value of the current extracted from the characteristic frequency band of the k-th single-switch oscillation waveform; In step S5, the multi-vector average insulation state index The calculation formula is as follows: In the formula, j is the voltage vector index corresponding to the pulse excitation signal.

8. The motor early-turn inter-turn short-circuit fault detection system based on six-vector injection according to claim 1 or 2, characterized in that, When detecting early-stage inter-turn short-circuit faults in motors, the multi-vector average insulation condition index calculated under the detection conditions will be used. The multi-vector average insulation condition index calculated under normal motor conditions A comparison was made to determine the early inter-turn short-circuit fault status of the motor; among which, the multi-vector average insulation status index was used. The larger the value, the more severe the early inter-turn short circuit fault of the motor.

9. The motor early-turn inter-turn short-circuit fault detection system based on six-vector injection according to claim 1 or 2, characterized in that, Rotate the motor rotor to different mechanical angles, and calculate the multi-vector average insulation state index corresponding to each mechanical angle according to steps S1-S5 above. Among them, by comparing the multi-vector average insulation state index corresponding to different mechanical angles... The difference is used to evaluate and verify the impact of rotor position changes on the variability of characteristic parameters.

10. The motor early-turn inter-turn short-circuit fault detection system based on six-vector injection according to claim 1 or 2, characterized in that, Under the same rotor position, taps are drawn from inside the winding, and a turn near the end is connected to cement resistors of different resistance values ​​to simulate different degrees of early inter-turn short-circuit faults in the motor. Following steps S1-S5 above, the multi-vector average insulation condition index corresponding to different degrees of early inter-turn short-circuit faults in the motor is calculated. Among them, by comparing the multi-vector average insulation status index corresponding to different degrees of early inter-turn short-circuit faults in motors. The difference is used to assess the sensitivity of verifying different inter-turn short-circuit fault levels.

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