Motor voltage current phase and polarity self-identification method and system

Abstract

This invention discloses a method and system for self-identifying the phase and polarity of motor voltage and current. The method includes: acquiring three-phase voltage and current signals, performing signal validity detection, and acquiring the fundamental phase angle data when the signal is valid; calculating the phase sequence by determining the adjacent phase difference, and generating instructions to exchange data between channels B and C to restore the positive sequence if the sequence is negative; calculating the original power angle based on the corrected positive sequence voltage and current phases; constructing multiple candidate power angles corresponding to different channel rotation and polarity reversal combinations; comparing each candidate power angle with a preset effective range of power angles, and selecting the optimal adjustment strategy that conforms to physical laws; and outputting the final phase sequence status, channel adjustment, and polarity correction instructions. This method can automatically complete phase identification, phase sequence, and polarity recognition, and is suitable for scenarios such as smart meters, frequency converters, and motor protection. It has the advantages of high reliability, strong robustness, and low resource consumption.

Description

Technical Field

[0001] This invention relates to the field of power system measurement and control technology, specifically a method, system, and apparatus for automatic identification and correction of voltage and current phase identification, phase sequence, and polarity for three-phase motors and general three-phase loads. Background Technology

[0002] In three-phase power systems, accurate identification of the voltage and current phases (A / B / C) and polarities (positive / reverse connection) of motors is fundamental for achieving precise energy metering, protection control, fault diagnosis, and condition monitoring. Especially in devices such as smart meters, frequency converters, motor drives, and relay protection devices, incorrect voltage and current path connections (e.g., incorrect phase sequence, reverse polarity, incorrect phase connection) can lead to serious consequences such as power calculation errors, malfunctions or failures to operate protection systems, and inaccurate control.

[0003] Currently, the mainstream methods for phase sequence and polarity identification in three-phase systems mainly rely on the following technical approaches:

[0004] Phase sequence determination based on phase difference: By acquiring the phase information of three-phase voltage or current, the relative relationship of phase differences (such as U_A-U_B, U_B-U_C) is used to determine whether the phase sequence is positive (ABC) or negative (ACB). Typical methods include calculating the algebraic sum of the three-phase phase differences or using Fourier transform to extract the fundamental phase, and then determining the sequence based on the sign or magnitude of the phase differences. For example, in positive sequence, U_A-U_B≈-120°, U_B-U_C≈-120°, while in negative sequence, the opposite is true.

[0005] Polarity and phase verification based on power angle (UI phase difference): Given the phase sequence, the power angle (UI angle difference) between voltage and current is calculated. Combined with a preset reasonable effective range of power angle (e.g., -90° to +90°), it is determined whether the voltage or current path is reversed. If the power angle exceeds the reasonable range, it is inferred that there may be reverse polarity or phase mismatch, and then correction is achieved by adjusting the path sequence or polarity.

[0006] Channel combination trial method: When the initial phase and polarity cannot be determined, the system tries multiple channel combinations (such as ABC, BCA, CAB, -ABC, etc.) and calculates the corresponding power angles, selecting the combination that keeps the power angles within a reasonable range as the final configuration. This method is commonly used in automatic wiring identification modules.

[0007] However, the aforementioned existing technologies still have several key problems:

[0008] Phase sequence determination relies on a single phase difference, which is susceptible to noise and non-steady-state signal interference. Existing phase sequence determination methods usually only use the phase difference between two phases for judgment. When there are harmonics, transient processes or sampling errors in the signal, it is easy to misjudge the phase sequence, leading to subsequent power angle correction errors.

[0009] The current method does not fully consider the multiple possibilities of channel combination and polarity change when judging the polarity of voltage and current. It simply compares whether the UI angle is within a reasonable range, without systematically considering the phase offset combination caused by channel rotation (such as ABC→BCA→CAB) and polarity reversal (±180°). This results in the inability to fully cover all possible wiring error situations and the limited recognition rate.

[0010] Lack of a unified phase and polarity joint identification mechanism: Existing technologies mostly treat "phase sequence identification" and "polarity judgment" as two independent steps, without establishing a unified identification framework. This leads to confusion in the identification logic and difficulty in accurately restoring the true physical connection in complex wiring error scenarios (such as phase sequence error + polarity reversal).

[0011] The existing methods cannot effectively handle the automatic processing of "invalid and abnormal" states: When the sampled data has invalid states such as noise, frequency abnormality or zero amplitude, the existing methods still attempt to perform phase sequence or power angle judgment, which leads to misjudgment or getting stuck in an infinite loop, and lacks robustness.

[0012] In summary, existing technologies for the self-identification of phase and polarity of three-phase voltage and current have problems such as low identification accuracy, poor anti-interference ability, incomplete logic, and inability to handle compound errors, making it difficult to meet the requirements of high-reliability power equipment for automatic wiring identification. Summary of the Invention

[0013] A brief overview of embodiments of the invention is provided below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0014] The purpose of this invention is to provide a universal method capable of handling voltage and current phase sequence and polarity issues in a single operation. This method can automatically identify phase, phase sequence, and polarity without prior information. It requires no additional hardware investment, relying solely on conventional three-phase voltage and current acquisition data. After the equipment is powered on, it can quickly perform automatic diagnosis and correction suggestions for wiring errors, making it suitable for scenarios such as motor control, energy metering, relay protection, and fault diagnosis. Its core lies in introducing an algorithm logic that enumerates seven candidate combinations by verifying the physical constraint of a reasonable power angle range. Whether it's a phase sequence error, reverse polarity connection, or channel rotation, its impact on the power angle is definite; by calculating and verifying which combination's power angle is within a reasonable range, the actual wiring status can be deduced.

[0015] According to one aspect of this application, a method for self-identifying the phase and polarity of motor voltage and current is provided, comprising the following steps:

[0016] Step S1: Acquire three-phase sampling data

[0017] Acquire three-phase voltage signals (U_A, U_B, U_C) and three-phase current signals (I_A, I_B, I_C) at a sampling frequency no less than 12 times the power frequency (e.g., above 600Hz), with at least one cycle of sampling points (e.g., 24 points / cycle). First, perform signal validity testing. Phase sequence and power angle analysis are only performed under the premise that the voltage / current is valid (RMS normal, frequency stable) to avoid invalid data interfering with the judgment logic. Signal validity testing includes determining whether the effective values ​​of the three-phase voltage and current signals are greater than preset thresholds and whether the system frequency is stable within the preset power frequency range. For a power frequency system with a rated frequency of 50Hz, the condition for determining frequency stability is that the frequency measurement value remains between 49.5Hz and 50.5Hz (i.e., ±0.5Hz deviation), or the frequency fluctuation rate is less than 0.1Hz / s, to ensure that the sampled data can correctly reflect the fundamental phase characteristics. Obtain the fundamental phase angle data through Discrete Fourier Transform (DFT) or Taylor Fourier Transform (TFT).

[0018] Step S2: Phase sequence determination and adjustment

[0019] Input the phase angle data of the three-phase voltage or current (A / B / C phases, unit: degrees), and perform the following operations:

[0020] 1. Normalize each phase angle to the range [0°, 360°);

[0021] 2. Calculate the phase angle difference between two adjacent phases and normalize it to 0-360 degrees:

[0022] ΔAB=(A-B+360°)mod 360°, ΔBC=(B-C+360°)mod 360°, ΔCA=(C-A+360°)mod360°; where mod 360 means taking the modulus, that is, converting the value to the range of 0 to 360.

[0023] 3. If |ΔAB-120°| < angle tolerance, |ΔBC-120°| < angle tolerance, and |ΔCA-120°| < angle tolerance, then it is determined to be in positive sequence (ABC), and the output phase sequence identifier is 0; the preset value of angle tolerance is 15°, which can be modified in the interface or configuration file according to actual needs;

[0024] 4. If |ΔCA-240°| < angle tolerance and |ΔBC-240°| < angle tolerance, it is determined to be negative sequence (ACB), the output phase sequence flag is set to 1, and it is recommended to swap the order of channels B and C to restore the positive sequence;

[0025] 5. Otherwise, return an abnormal status (-1).

[0026] Step S3: Polarity and Phase Adjustment Strategy Identification

[0027] Based on the voltage and current phases (AngU_A, AngI_A) that have been corrected to positive sequence, and combined with the set effective range of the power angle [LoLimit, HiLimit], the following operations are performed:

[0028] 1. Calculate the original power angle: ΔAA = (AngU_A – AngI_A + 360°) mod 360, where the normalized angle is within (0-360°). Where AngU_A is the phase angle of voltage phase A (U_A); AngI_A is the phase angle of current phase A (I_A).

[0029] 2. Since the channel phase can rotate ±120° while maintaining the positive sequence (ABC->BCA->CAB), and the channel polarity can change ±180° when reversed, the channel angle can vary from 0°, ±120°, and ±180° from its original value. The actual power angle can be obtained by further deflecting the reference phase (U_A-I_A) by 0°, ±60°, ±120°, and ±180°, i.e., U_A-I_A=(0, ±120, ±180)-(0, ±120, ±180)=(0, ±60, ±120, ±180). Seven possible candidate power angle values ​​(deflected by different angles from the original power angle) are constructed and normalized, corresponding to different adjustment combinations:

[0030] o0: Initial state (ABC-ABC);

[0031] o1: Voltage path rotation BCA, current reversed → +60° (equivalent to -120°+180°) (BCA-(-ABC));

[0032] o2: Voltage channel rotates CAB, current reverses → -60° (equivalent to +120°-180°) (CAB-(-ABC));

[0033] o3: Voltage channel rotates CAB, current remains unchanged → +120° (CAB-ABC);

[0034] o4: Voltage path rotates BCA, current remains unchanged → -120° (BCA-ABC);

[0035] o5: Voltage reversed, current unchanged → +180° ((-ABC)-ABC);

[0036] o6: Voltage reversed, current unchanged → -180° (((-ABC)-ABC, equivalent to +180° of o5).

[0037] 3. Iterate through o0-o6, and for each candidate power angle theta_i, determine whether it falls within the valid range of power angles [LoLimit, HiLimit].

[0038] 4. If there is a unique candidate value that meets the conditions, return the number (0-6), and the channel rotation and polarity combination corresponding to the oi is the actual wiring state; if multiple conditions are met, select the scheme that is closest to the original power angle (the oi with the smallest angle with the original power angle ΔAA); if none of them are met, return -1 to indicate an error.

[0039] Step S4: Polarity Reversal Status Feedback

[0040] If a negative sequence is detected in step S2, channels B and C need to be swapped; if 1, 2, 5 or 6 are returned in step S3, it indicates that the polarity of the current or voltage is reversed and polarity correction is required.

[0041] Step S5: Output adjustment instructions

[0042] Based on the results of steps S2 and S3, specific wiring adjustment instructions are generated; the final output includes:

[0043] Phase sequence status (positive / negative / abnormal);

[0044] Phase sequence adjustment command (whether to switch B / C channels);

[0045] Voltage / current channel adjustment mode (alternating or reverse connection);

[0046] The phase adjustment method after final alignment.

[0047] Among them, the synchronous rotation of voltage and current or the overall polarity reversal does not affect the positive and negative sequence, nor does it affect the power angle. Therefore, the power angle offset angle can be adjusted in multiple ways with the same effect. For example, +60 = -120 - (-180) = 180 - 120. If, after the final adjustment, the customer designates a certain phase as phase A based on the site conditions, the synchronous rotation of voltage and current can be performed without affecting the final effect.

[0048] As a feasible solution, in step S3, when all candidate power angles do not meet the effective range, an identification failure signal is output, and the previous successful configuration is maintained.

[0049] In step S3, the effective range of the power angle [LoLimit, HiLimit] can be set according to the power factor characteristics of the load or dynamically adjusted according to the actual load conditions, for example:

[0050] Inductive load: The effective range of the power angle can be set to [30°, 90°];

[0051] Capacitive load: The effective range of the power angle can be set to [-90°, -30°];

[0052] Resistive load: The effective range of the power angle can be set to [-10°, 10°].

[0053] Furthermore, after outputting the adjustment command in step S5, a closed-loop verification step is also included: the data is virtually corrected according to the output adjustment command, and the corrected phase sequence and power angle are re-verified. The identification result officially takes effect only after the verification is passed.

[0054] According to a second aspect of this application, a motor voltage and current phase identification and polarity self-identification system is provided, which includes a processor and a memory, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described motor voltage and current phase identification and polarity self-identification method.

[0055] According to a third aspect of this application, a computer-readable storage medium is provided, on which a computer program is stored, wherein when the computer program is executed by a processor, the steps of the above-described method for self-identifying the phase and polarity of motor voltage and current are implemented.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] 1. Fully automatic identification: No manual adjustment by the user is required. Relying only on the existing three-phase acquisition data, it can output a complete wiring correction solution including phase identification, phase sequence, and polarity identification in one go;

[0058] 2. High robustness: Through physical constraints on the power angle (the power angle must fall within a reasonable range), the effects of noise interference and phase drift are effectively filtered out, resulting in an extremely low false positive rate;

[0059] 3. Standardization: Applicable not only to motors, but also to transformers and generator sets. A standardized phase sequencer upgrade can replace complex zero-sequence differential calibration devices.

[0060] 4. Low cost: No additional hardware investment is required. Simply integrating this solution into the software algorithm can significantly improve the intelligence level of products such as smart meters and frequency converters.

[0061] 5. Immediacy: Identification can be completed instantly upon power-up of the device, without the need for long-term data accumulation, making it suitable for rapid calibration during the transient process of motor startup. Attached Figure Description

[0062] The present invention can be better understood by referring to the description given below in conjunction with the accompanying drawings, in which the same or similar reference numerals are used throughout the drawings to denote the same or similar parts. These drawings, together with the following detailed description, are incorporated in and form part of this specification, and are used to further illustrate preferred embodiments of the invention and explain the principles and advantages of the invention. In the drawings:

[0063] Figure 1 This is a system flowchart of the present invention;

[0064] Figure 2 This is a schematic diagram of the phase sequence determination logic;

[0065] Figure 3 This is a diagram showing the relationship between the power angle adjustment mode and the corresponding phase offset. Detailed Implementation

[0066] Embodiments of the present invention will now be described with reference to the accompanying drawings. Elements and features described in one drawing or embodiment of the invention may be combined with elements and features shown in one or more other drawings or embodiments. It should be noted that, for clarity, representations and descriptions of components and processes unrelated to the present invention and known to those skilled in the art have been omitted from the drawings and description.

[0067] This invention provides a method and system for self-identifying the phase and polarity of motor voltage and current. Without prior wiring information, it can automatically complete the following tasks: determine the phase sequence (positive or negative); automatically adjust the phase sequence to the standard positive sequence (ABC); identify the polarity state (positive or negative) of the voltage and current channels; determine the optimal phase adjustment strategy based on a reasonable power angle range; and achieve unified benchmark alignment of the voltage and current channels, providing accurate input for subsequent calculations of power, energy, and protection.

[0068] See Figure 1The motor voltage and current phase and polarity self-identification process of the present invention includes: acquiring three-phase voltage and current data (three-phase voltage signal and three-phase current signal), performing signal validity detection, and extracting the fundamental phase angle when the signal is valid; calculating the adjacent phase differences ΔAB, ΔBC and ΔCA of the three-phase voltage or current, and determining the phase sequence. If it is a negative sequence, an instruction to exchange data in channels B and C is generated to restore the positive sequence; based on the voltage and current phases that have been corrected to a positive sequence, identifying and adjusting the power angle and polarity, and outputting the final identification result and correction information.

[0069] See Figure 2 The phase sequence determination logic is as follows: Calculate the adjacent phase differences ΔAB, ΔBC, and ΔCA of the three-phase voltage or current; determine whether they are close to 120 degrees or 240 degrees to determine the phase sequence. If close to 120 degrees, it is determined to be positive sequence; if close to 240 degrees, it is determined to be negative sequence. The default angle tolerance threshold is 15. If it is determined to be negative sequence, generate an instruction to exchange data between channels B and C to restore positive sequence. The above determination process can also be directly determined within the angle tolerance fluctuation range defined for positive sequence (0, -120, 120) and negative sequence (0, 120, -120).

[0070] See Figure 3 The identification and adjustment of power angle and polarity specifically includes: calculating the original power angle ΔAA based on the voltage and current phases that have been corrected to positive sequence; constructing multiple candidate power angles corresponding to different channel rotation and polarity reversal combinations; for each candidate power angle, cyclically determining whether it falls within the effective range of the power angle; if so, setting the angle identification result and correction information, and ending the loop.

[0071] Example 1: Negative sequence and reverse polarity connection

[0072] Input voltage phase: A=0°, B=120°, C=240°;

[0073] Input current phase: A=30°, B=150°, C=270°;

[0074] Effective range of working angle: LoLimit=15°, HiLimit=45°;

[0075] Execute step S2:

[0076] Calculate the voltage phase difference: ΔAB=240°, ΔBC=240°, ΔCA=240° → This does not satisfy the positive sequence condition;

[0077] Check negative sequence conditions: ΔCA=240°, ΔBC=240° → Negative sequence conditions are met → Output phase sequence identifier is 1, and it is recommended to swap channels B / C to restore positive sequence.

[0078] After swapping channels B and C, the new phases are: A=0°, B=240°, C=120°. Calculating ΔAB=120°, ΔBC=120°, ΔCA=120° → the positive sequence holds true.

[0079] Execute step S3:

[0080] Using the corrected voltage phase A U_A=0° and current phase A I_A=30°, the original power angle ΔAA=330° is calculated;

[0081] Construct candidate power angles and determine: Candidate power angle 1 (330°+60°=30°) falls within the preset effective range of power angles [15°, 45°], while the rest are not within the range;

[0082] The returned identification result is number 1, indicating that the voltage channel needs to be adjusted to BCA and the current reversed.

[0083] Final output adjustment command: voltage is CBA, current is ACB reversed (first swap B / C channels, then adjust the voltage channel to BCA, and reverse the polarity of the current).

[0084] Example 2: Reverse polarity connection

[0085] This embodiment demonstrates a method for identifying voltage polarity reversal errors:

[0086] Input voltage phase: A=180°, B=300°, C=60°;

[0087] Input current phase: A=210°, B=90°, C=330°

[0088] Effective range of power angle: [150°, 210°];

[0089] Execute step S2:

[0090] Voltage side: ΔAB=240°, ΔBC=240°, ΔCA=240° → determined as negative sequence → execute B / C channel swap → obtain positive sequence.

[0091] Current side: ΔAB=120°, ΔBC=120°, ΔCA=120° → judged as positive sequence → normal.

[0092] Execute step S3: Using the corrected voltage phase A U_A=180° and current phase A I_A=210°, calculate the original power angle ΔAA=330°;

[0093] Construct candidate angles and determine: Candidate value 5 (330°+180°=150°) falls within the preset range [150°, 210°];

[0094] The returned identification result is number 5, indicating that the voltage needs to be reversed.

[0095] The final output adjustment command is to switch the voltage B / C channels and reverse the voltage polarity while keeping the current constant.

[0096] Example 3: The principle of generating the candidate work angle set

[0097] This embodiment details the theoretical origin of the candidate power angle set in the core algorithm: since the channel phase can rotate ±120° while maintaining the positive sequence (ABC->BCA->CAB).

[0098] The channel polarity can be reversed by ±180°, so U_A or I_A can be varied by 0°, ±120°, or ±180° from the original phase reference. Therefore, the actual power angle can be obtained by further deflecting the reference phase (U_A-I_A) by 0°, ±60°, ±120°, or ±180°, i.e., U_A-I_A=(0, ±120, ±180)-(0, ±120, ±180)=(0, ±60, ±120, ±180). By determining the truly reasonable angle using the threshold, the method for adjusting the power angle phase of voltage and current is obtained.

[0099] +0=0-0ABC-(ABC) / / Voltage and current remain unchanged;

[0100] +60=-120-(-180)BCA-(-ABC) / / The +60 degree adjustment is required. The overall voltage shifts by -120 degrees, and the overall current shifts by 180 degrees. BCA-(-ABC) indicates that the voltage path is adjusted to BCA and the three-phase current polarity is reversed.

[0101] -60 = +120 - 180CAB - (-ABC);

[0102] +120 = +120 - 0CAB - (ABC);

[0103] -120 = -120 - 0BCA - (ABC);

[0104] +180 = +180 - 0(-ABC) - (ABC);

[0105] -180 = -180 - 0(-ABC) - (ABC);

[0106] By constructing seven candidate power angles and screening them based on physical laws (the power angle should be within a reasonable range), the optimal adjustment strategy is finally determined.

[0107] Example 4

[0108] This embodiment provides a motor voltage and current phase identification and polarity self-identification system, which includes a processor and a memory. The memory stores a computer program, and when the processor executes the computer program, it implements the steps of the above-mentioned motor voltage and current phase identification and polarity self-identification method.

[0109] Example 5

[0110] This embodiment provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the above-described method for self-identifying the phase and polarity of motor voltage and current.

[0111] While existing technologies have made some progress in phase sequence identification and power angle determination, they still have some key drawbacks:

[0112] 1. Phase sequence determination lacks a multi-dimensional verification mechanism and is easily affected by signal distortion. Existing methods rely solely on the phase difference between two phases to determine phase sequence. When harmonics, transient interference, or sampling delays exist in the signal, the phase difference calculation error is large, easily leading to misjudgment. For example, when the phase difference between U_A and U_B is +130° instead of the ideal -120°, the system may incorrectly determine it as a negative sequence, thus incorrectly swapping channels BC and triggering a chain of errors. This invention improves the robustness and accuracy of phase sequence determination by introducing a three-phase phase consistency check (e.g., the sum of phase differences approaches -360°).

[0113] 2. Power Angle Judgment Lacks Systematic Modeling of Channel and Polarity Reversal Combination Space. Existing methods only consider the UI angle difference under a single channel configuration, failing to model "channel rotation" (e.g., ABC→BCA→CAB) and "polarity reversal" (±180°) as joint variables. In practice, wiring errors in voltage or current channels may simultaneously involve phase sequence misalignment and polarity reversal, and existing methods cannot simultaneously identify and correct such compound errors. For example, if the voltage channel is BCA and the current polarity is reversed, the power angle may fall within a reasonable range, but the physical connection is completely incorrect. This invention constructs a "phase deflection combination space" (e.g., ±60°, ±120°, ±180°), systematically enumerating all possible phase adjustment combinations, thus achieving comprehensive identification of complex wiring errors.

[0114] 3. Lack of proactive detection and avoidance mechanisms for "invalid anomalies". Existing methods still force the judgment when the input signal is invalid (such as too low amplitude, abnormal frequency, phase jump), resulting in unreliable output results. This invention adds a signal validity detection module before judgment, and only performs phase sequence and power angle analysis under the premise that the voltage / current is valid (RMS is normal and the frequency is stable), effectively avoiding invalid data from interfering with the judgment logic.

[0115] 4. The fragmented identification process makes end-to-end automatic recovery difficult. Existing technologies process "phase sequence judgment" and "power angle correction" separately, lacking a unified identification and adjustment strategy. For example, phase sequence is adjusted first, followed by polarity adjustment, but the impact of the adjustment on the power angle is not considered, leading to repeated iterations. This invention proposes a joint identification algorithm framework that models phase sequence judgment and power angle correction in a unified manner, outputting the optimal phase and polarity configuration scheme in one go, significantly improving identification efficiency and accuracy.

[0116] 5. Inability to support real-time adaptive recognition in dynamic scenarios. Under dynamic operating conditions such as motor startup, sudden load changes, or power grid disturbances, voltage and current phases may change rapidly, making it difficult for existing static judgment methods to respond in real time. This invention introduces a sliding window and dynamic threshold mechanism, combined with angle tolerance and phase stability criteria, to achieve adaptive recognition of dynamic signals.

[0117] This invention utilizes the steady-state (or near-steady-state) three-phase voltage and current phase relationship under normal load for identification. First, it determines and corrects the phase sequence to the positive sequence. Then, it clearly models and processes the combined effect of "channel switching" (such as ABC→BCA→CAB) and "polarity reversal" (±180°), and unifies it into processing different offsets of the power angle (0°, ±60°, ±120°, ±180°). The model is complete and highly abstract.

[0118] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, element, step, or component, but does not exclude the presence or addition of one or more other features, elements, steps, or components.

[0119] Although the invention has been disclosed above through the description of specific embodiments, it should be understood that all the embodiments and examples described above are exemplary and not restrictive. Those skilled in the art can design various modifications, improvements, or equivalents to the invention within the spirit and scope of the appended claims. These modifications, improvements, or equivalents should also be considered to be included within the protection scope of the invention.

Claims

1. A method for self-identifying the phase and polarity of motor voltage and current, characterized in that, Includes the following steps: S1: Acquire three-phase voltage and three-phase current signals, perform signal validity detection, and obtain the fundamental phase angle data when the signal is valid; S2: Based on the phase angle data of the three-phase voltage or current obtained in step S1, calculate the phase difference between adjacent phases to determine the phase sequence. If the sequence is negative, generate an instruction to exchange data between channels B and C to restore the positive sequence. Specifically, determining the phase sequence includes: calculating and normalizing the phase difference between two adjacent phases, and then determining whether it is close to 120 degrees or 240 degrees to determine the phase sequence. The basis for determining the phase sequence is: If |ΔAB-120°| < angle tolerance, |ΔBC-120°| < angle tolerance, and |ΔCA-120°| < angle tolerance, then it is determined to be in positive order; If |ΔCA-240°| < angle tolerance and |ΔBC-240°| < angle tolerance, then it is determined to be a negative order; The angle tolerance is preset to 15°. S3: Based on the voltage and current phases corrected to positive sequence, calculate the original power angle; offset the original power angle by 0°, +60°, -60°, +120°, -120°, +180°, and -180° to construct seven candidate power angles corresponding to different channel rotation and polarity reversal combinations; compare each candidate power angle with the preset effective range of power angles to select the optimal adjustment strategy that conforms to physical laws; S4: Outputs the final phase sequence status, channel adjustment, and polarity correction commands.

2. The method for self-identifying motor voltage and current phase and polarity according to claim 1, characterized in that, The signal validity detection in step S1 includes: determining whether the effective values ​​of the three-phase voltage signal and the three-phase current signal are greater than a preset threshold, and determining whether the system frequency is stable within a preset power frequency range.

3. The method for self-identifying the phase and polarity of motor voltage and current according to claim 1, characterized in that, In step S3, multiple candidate power angles corresponding to different combinations of channel rotation and polarity reversal are constructed. Specifically, the angle is deflected based on the original power angle to generate seven candidate power angle values, which correspond to different combinations of no voltage and current channel adjustment, channel rotation, and polarity reversal, as expressed below: Original work angle; Voltage path BCA, current reverse connection → power angle offset +60°; Voltage channel CAB, current reverse connection → power angle offset -60°; Voltage path CAB, current unchanged → power angle shift +120°; Voltage path BCA, current unchanged → power angle shift -120°; Voltage reversed, current unchanged → power angle shift ±180°.

4. The method for self-identifying the phase and polarity of motor voltage and current according to claim 1, characterized in that, In step S3, the effective range of the power angle is set according to the power factor characteristics of the load or dynamically adjusted according to the actual load conditions.

5. The method for self-identifying motor voltage and current phase and polarity according to claim 1, characterized in that, After step S4, a closed-loop verification step is also included: the data is virtually corrected according to the output adjustment instructions, and the corrected phase sequence and power angle are re-verified. The identification result is officially effective only after the verification is passed.

6. A motor voltage and current phase identification and polarity self-identification system, characterized in that, It includes a processor and a memory, the memory storing a computer program, and the processor executing the computer program to implement the steps of the motor voltage and current phase and polarity self-identification method according to any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the motor voltage and current phase and polarity self-identification method according to any one of claims 1 to 5.

Images