Drive motor whole machine resistance measurement method and system applied to new energy vehicle

Abstract

The application discloses a driving motor whole machine resistance measurement method and system applied to a new energy automobile, relates to the technical field of new energy automobiles, and determines a dynamic threshold range and a trend early warning condition through pretreatment and statistical analysis based on historical winding resistance data and working condition parameters; an initial angle position of a rotor is identified by scanning a current pulse to collect a back electromotive force, an electromagnetic balance current is input to lock the rotor at a first predetermined position; a closed-loop regulated compensation current is used to maintain stable locking, a four-wire Kelvin connection method is used to calculate a first winding resistance value; the rotor is controlled to step to a second position at 180 degrees of an electric angle to repeat measurement, a second resistance value is acquired, and a monitoring sequence is updated; differences between the two resistance values and a sequence trend are analyzed, and an alarm is generated when the threshold value is exceeded or the trend approaches an upper limit, so that the measurement accuracy and early warning timeliness are improved, and the motor operation safety is ensured.

Description

Technical Field

[0001] This invention relates to the field of technology, specifically to a method and system for measuring the overall resistance of drive motors in new energy vehicles. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the drive motor, as the core component of vehicle power output, directly affects the overall vehicle performance through its operational reliability and safety. Winding resistance is a key parameter reflecting the health status of the motor windings; abnormal changes may indicate faults such as winding aging, insulation damage, or poor contact. Failure to monitor this in time can lead to serious consequences such as decreased motor efficiency, localized overheating, or even fire.

[0003] Existing methods for measuring the resistance of drive motor windings have several limitations: First, static measurement modes are difficult to simulate actual operating conditions and ignore the influence of parameters such as temperature and operating time on resistance; second, the rotor is susceptible to electromagnetic interference during measurement, causing position fluctuations and resulting in magnetic field coupling errors, which affect the accuracy of resistance calculation; third, most methods use two-wire measurement, which introduces additional errors due to the resistance of the wires; fourth, the threshold judgment criteria are fixed and cannot be dynamically adjusted according to individual motor differences, resulting in poor adaptability; and fifth, there is a lack of continuous analysis of resistance change trends, making it difficult to achieve early warning of faults, and often only responding passively after a fault occurs.

[0004] Therefore, there is a need for a method to measure the overall resistance of drive motors that can accurately locate the rotor position under complex operating conditions, dynamically optimize measurement conditions, and combine trend analysis to achieve early warning, so as to meet the high reliability monitoring requirements of drive motors in new energy vehicles. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for measuring the overall resistance of drive motors used in new energy vehicles, in order to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method and system for measuring the overall resistance of a drive motor in new energy vehicles, the method comprising:

[0007] Step S1: Obtain historical measurement data of the winding resistance of the target motor and corresponding operating parameters. By preprocessing the data and calculating the characteristic values, obtain the dynamic reasonable threshold range and trend warning conditions.

[0008] Step S2: Input a scanning current pulse into the stator winding of the motor and collect the back electromotive force signal to identify the initial angular position of the rotor; calculate and input the electromagnetic balance current based on the initial angular position to generate a zero torque between the magnetic field of the rotor permanent magnet and the static magnetic field of the stator, thereby locking the rotor in the first predetermined position.

[0009] Step S3: The compensation current is dynamically adjusted through closed-loop control to suppress rotor displacement disturbance and maintain the rotor in a stable locked state at the first predetermined position; while maintaining the locked state, a DC measurement current is applied to the stator winding, and the voltage drop across the winding is collected using the four-wire Kelvin connection method to calculate the first winding resistance value.

[0010] Step S4: Control the rotor to rotate to the second predetermined position, repeat the locking control and resistance measurement process of steps S2 to S3, obtain the resistance value of the second winding; synchronously record the current resistance difference data and update it to the continuous monitoring sequence;

[0011] Step S5: Calculate the difference between the resistance values ​​of the first winding and the second winding; combine the dynamic reasonable threshold range and trend warning conditions determined in step S1 to analyze the current resistance difference and continuous monitoring sequence; if the resistance difference exceeds the dynamic reasonable threshold range, or if the continuous monitoring sequence shows a significant upward trend and approaches the upper limit of the threshold according to the trend warning conditions, then it is determined that there is a fault in the winding and a corresponding alarm is generated.

[0012] Furthermore, step S1 includes:

[0013] Step S1-1: Collect historical measurement data of the winding resistance of the target motor to obtain the initial dataset R={R1, R2, ..., R...} i , ..., R n}, where n is the number of historical measurements, and R i This represents the winding resistance value measured in the i-th measurement; the motor operating parameters at each measurement are recorded synchronously, including the ambient temperature T. i and motor running time t i ;

[0014] Step S1-2: Use the 3σ criterion to remove outliers. Outliers are measurements whose deviation from the mean of the initial dataset exceeds three times the standard deviation. The standard deviation is a measure of the dispersion of the initial dataset and is calculated using the following formula: Where μ0 is the average value of the initial dataset, ; Obtain a valid dataset Where m≤n; after grouping by operating parameters, calculate the statistical characteristic values ​​of each group of valid data, including the average value. and standard deviation ;

[0015] Step S1-3: Determine the dynamic reasonable threshold range based on statistical characteristic values. Set the lower threshold to L=μ-λ·σ and the upper threshold to U=μ+λ·σ, where λ is an adjustable coefficient and 1.5≤λ≤3. The dynamic reasonable threshold range is represented as [L, U].

[0016] Step S1-4: The resistance difference value after q consecutive measurements The moving average shows an upward trend, and the cumulative increase is... When a trend warning is triggered, q is the number of consecutive monitoring times and Δ0 is the preset minimum increase threshold.

[0017] Step S1-5: When 10 new measurement data are accumulated, repeat steps S1-1 to S1-4 to update the parameters λ, q, and Δ0 in the dynamic reasonable threshold range and trend warning conditions.

[0018] Furthermore, step S2 includes:

[0019] Step S2-1: Input scanning current pulses into the three-phase stator windings of the motor, synchronously acquire back electromotive force signals, and record the peak time t of the three-phase winding back electromotive force in the signal waveform. a ;

[0020] Step S2-2: Calculate the initial angular position θ0 of the rotor based on the peak time of the back electromotive force. The calculation formula is θ0 = 2πrp·(t a -t0), where r is the motor speed, p is the number of motor pole pairs, and t0 is the start time of the scanning current pulse (t a -t0) is the time difference from the start of the scanning current pulse to the peak value of the back electromotive force, and θ0 is the time difference between the start of the current pulse and the peak value of the back electromotive force. a The spatial phase position of the rotor relative to the stator winding at any given moment, and θ0 serves as the first reference position identified by the back electromotive force characteristics in the entire rotor locking and resistance measurement process;

[0021] Step S2-3: Calculate the electromagnetic balance current I based on the initial angular position θ0 of the rotor. b The phase of the rotor permanent magnet magnetic field is defined as θ0, where θ0 represents the spatial phase of the rotor permanent magnet magnetic field. The angle between the stator magnetic field and the rotor permanent magnet magnetic field is defined as α, based on the motor torque formula M=k u ·I·Φ·sinα, where M is the electromagnetic torque, k u Let I be the torque coefficient, Φ be the winding current, and Φ be the permanent magnet flux. When α = 0°, the electromagnetic torque M = 0, which is the zero-torque. By setting the stator magnetic field phase to θ0 and making α = 0°, the electromagnetic balance current I is obtained. b The phase matches θ0;

[0022] Step S2-4: Input electromagnetic balancing current I into the stator winding b The rotor position change Δθ is monitored in real time; when Δθ ≤ 0.5° electrical angle, it is determined that the rotor has been locked at the first predetermined position θ1.

[0023] Furthermore, step S3 includes:

[0024] Step S3-1: Continuously monitor the current position θ of the rotor, and calculate the position deviation Δθ from the first predetermined position θ1 as Δθ = θ - θ1;

[0025] Step S3-2: Using the position deviation Δθ as the input, calculate the compensation current ΔI with a proportional controller, with the formula ΔI = k v ×Δθ, where k v is the proportionality coefficient and 0.5 A / ° electrical angle ≤ k v ≤ 2 A / ° electrical angle; superimpose the compensation current ΔI onto the electromagnetic balance current I b , to obtain the total control current I total = I b + ΔI, and input it into the stator winding;

[0026] Step S3-3: The total control current I total acts on the stator winding to generate an adjustment torque, driving the rotor to shift towards the first predetermined position θ1; repeat steps S3-1 to S3-2, by continuously collecting new rotor position deviations and dynamically adjusting the total control current to form a closed-loop feedback control; until the position deviations Δθ of 5 consecutive samples all satisfy |Δθ| ≤ ±0.2° electrical angle, determine that the rotor maintains a stable locked state;

[0027] Step S3-4: In the stable locked state, cut off the control current circuit, and apply a DC measurement current I d to the stator winding through an independent current circuit; using the four-wire Kelvin connection method, connect two current lines in series in the measurement current circuit, and directly connect two voltage lines to both ends of the winding to collect the winding voltage drop U d ;

[0028] Step S3-5: Calculate the first winding resistance value , where U d is the average value of the voltage sampled 3 times.

[0029] Furthermore, step S4 includes:

[0030] Step S4-1: Stop inputting the electromagnetic balance current and the compensation current, input a stepping drive current to the stator winding, and control the rotor to step-rotate from the first predetermined position θ1 to the second predetermined position θ2, where the electrical angle difference between θ2 and θ1 is 180° electrical angle;

[0031] Step S4-2: At the second predetermined position θ2, repeat steps S2 and S3, and calculate to obtain the second winding resistance value R γ ;

[0032] Step S4-3: Calculate the resistance difference value ΔR g = |R γ - R βRecord the measurement time t g and the corresponding operating conditions parameters, including the ambient temperature T g and the cumulative operating duration of the motor ;

[0033] Step S4-4: Store ΔR g and the associated parameters into the continuous monitoring sequence S = {S1, S2, …, S g , …, S w}, where , and w is the cumulative number of monitoring times

[0034] Furthermore, step S5 includes:

[0035] Step S5-1: Calculate the absolute difference ΔR current = 丨R γ - R β 丨;

[0036] Step S5-2: Invoke the dynamic reasonable threshold range [L, U] determined in step S1, and judge whether ΔR current exceeds this range: If ΔR current < L or ΔR current > U, then mark it as threshold exceeding the standard;

[0037] Step S5-3: Extract the resistance difference values corresponding to the last q measurements arranged in chronological order in the continuous monitoring sequence S to form a continuous data subset with a length of q , and use the fixed window moving average method to calculate the moving average value. The formula is . If the current window moving average value is greater than the previous window moving average value and this feature appears in two or more consecutive windows, and at the same time the cumulative increase , and the latest difference value ΔR q > 80%×U, then mark it as trend warning;

[0038] Step S5-4: If the threshold exceeding the standard condition of step S5-2 or the trend warning condition of step S5-3 is satisfied, determine that there is a fault in the winding, and generate two-level alarms: output "Winding resistance abnormal fault alarm" when the threshold exceeds the standard, and output "Winding resistance difference rising warning" when there is a trend warning

[0039] The system includes: a threshold and warning condition construction module, a rotor initial locking module, a winding resistance measurement module, a multi-position measurement and sequence update module, and a fault analysis and alarm module;

[0040] The threshold and early warning condition construction module is used to obtain historical measurement data of the winding resistance of the target motor and corresponding operating parameters. By preprocessing the data and calculating the characteristic value, the dynamic reasonable threshold range and trend early warning conditions are obtained.

[0041] The historical data acquisition unit is used to collect historical measurement data of the winding resistance of the target motor, forming an initial dataset R={R1, R2, ..., R...} i , ..., R n}, where n is the number of historical measurements, and R i This represents the winding resistance value measured in the i-th measurement; the motor operating parameters at each measurement are recorded synchronously, including the ambient temperature T. i and motor running time t i ;

[0042] The data preprocessing unit is used to preprocess the initial dataset by removing outliers using the 3σ criterion. Outliers are measurements whose deviation from the mean of the initial dataset exceeds three times the standard deviation, where the standard deviation is a measure of the dispersion of the initial dataset and is calculated using the following formula: Where μ0 is the average value of the initial dataset, ; Obtain a valid dataset Where m≤n; after grouping by operating parameters, calculate the statistical characteristic values ​​of each group of valid data, including the average value. and standard deviation ;

[0043] The threshold calculation unit is used to determine the dynamic reasonable threshold range based on statistical characteristic values. The lower threshold is set as L=μ-λ·σ, and the upper threshold is set as U=μ+λ·σ, where λ is an adjustable coefficient and 1.5≤λ≤3. The dynamic reasonable threshold range is represented as [L, U].

[0044] The warning condition setting unit is used to set the warning condition when the resistance difference value of q consecutive measurements is... The moving average shows an upward trend, and the cumulative increase is... When a trend warning is triggered, q is the number of consecutive monitoring times and Δ0 is the preset minimum increase threshold.

[0045] The parameter update unit is used to repeat the historical data acquisition unit to the early warning condition setting unit when 10 new measurement data are accumulated, and update the parameters λ, q, and Δ0 in the dynamic reasonable threshold range and trend early warning conditions.

[0046] The rotor initial locking module is used to input scanning current pulses to the stator windings of the motor, collect back electromotive force signals to identify the initial angular position of the rotor; calculate and input electromagnetic balance current based on the initial angular position, so as to generate a zero torque between the magnetic field of the rotor permanent magnet and the static magnetic field of the stator, thereby locking the rotor in the first predetermined position.

[0047] The scanning pulse input unit is used to input scanning current pulses to the three-phase stator windings of the motor, synchronously acquire back electromotive force signals, and record the peak time t of the three-phase winding back electromotive force in the signal waveform. a ;

[0048] The initial angle calculation unit is used to calculate the rotor's initial angular position θ0 based on the peak time of the back electromotive force. The calculation formula is θ0 = 2πrp·(t a -t0), where r is the motor speed, p is the number of motor pole pairs, and t0 is the start time of the scanning current pulse (t a -t0) is the time difference from the start of the scanning current pulse to the peak value of the back electromotive force, and θ0 is the time difference between the start of the current pulse and the peak value of the back electromotive force. a The spatial phase position of the rotor relative to the stator winding at any given moment, and θ0 serves as the first reference position identified by the back electromotive force characteristics in the entire rotor locking and resistance measurement process;

[0049] The balance current generation unit is used to calculate the electromagnetic balance current I based on the rotor's initial angular position θ0. b The phase of the rotor permanent magnet magnetic field is defined as θ0, where θ0 represents the spatial phase of the rotor permanent magnet magnetic field. The angle between the stator magnetic field and the rotor permanent magnet magnetic field is defined as α, based on the motor torque formula M=k u ·I·Φ·sinα, where M is the electromagnetic torque, k u Let I be the torque coefficient, Φ be the winding current, and Φ be the permanent magnet flux. When α = 0°, the electromagnetic torque M = 0, which is the zero-torque. By setting the stator magnetic field phase to θ0 and making α = 0°, the electromagnetic balance current I is obtained. b The phase matches θ0;

[0050] The locking determination unit is used to input an electromagnetic balance current I into the stator winding. b The rotor position change Δθ is monitored in real time; when Δθ ≤ 0.5° electrical angle, it is determined that the rotor has been locked at the first predetermined position θ1.

[0051] The winding resistance measurement module is used to dynamically adjust the compensation current through closed-loop control to suppress rotor displacement disturbance and maintain the rotor in a stable locked state at the first predetermined position. In the locked state, a DC measurement current is applied to the stator winding, and the voltage drop across the winding is collected using a four-wire Kelvin connection method to calculate the first winding resistance value.

[0052] The position deviation monitoring unit is used to monitor the current position θ of the rotor in real time and calculate the deviation Δθ = θ - θ1 between θ1 and the first predetermined position.

[0053] The compensation current adjustment unit is used to calculate the compensation current ΔI using the position deviation Δθ as input and a proportional controller, with the formula ΔI=kv ×Δθ, where k v is a proportionality coefficient and 0.5 A / ° electrical angle ≤ k v ≤ 2 A / ° electrical angle; The compensation current ΔI is superimposed on the electromagnetic balance current I b , to obtain the total control current I total = I b + ΔI, and input it into the stator winding;

[0054] The stable locking determination unit is used for the total control current I total to act on the stator winding to generate an adjustment torque, driving the rotor to deviate towards the first predetermined position θ1; Repeat the execution of the position deviation monitoring unit to the compensation current adjustment unit, and form a closed-loop feedback control by collecting the new rotor position deviation in real time and dynamically adjusting the total control current; Until the position deviations Δθ of 5 consecutive samples all satisfy |Δθ| ≤ ±0.2° electrical angle, it is determined that the rotor maintains a stable locking state;

[0055] The measured current application unit is used to cut off the control current loop in the stable locking state and apply a DC measured current I to the stator winding through an independent current loop d ; Using the four-wire Kelvin connection method, two current lines are connected in series in the measured current loop, and two voltage lines are directly connected to both ends of the winding to collect the winding voltage drop U d ;

[0056] The voltage acquisition unit and the resistance calculation unit are used to calculate the first winding resistance value , where U d is the average value of the voltages sampled 3 times;

[0057] The multi-position measurement and sequence update module is used to control the rotor to step-rotate to the second predetermined position, repeat the locking control and resistance measurement processes of the rotor initial locking module to the winding resistance measurement module, and obtain the second winding resistance value; Synchronously record the current resistance difference data and update it to the continuous monitoring sequence;

[0058] The step drive unit is used to stop inputting the electromagnetic balance current and the compensation current, input a step drive current to the stator winding, and control the rotor to step-rotate from the first predetermined position θ1 to the second predetermined position θ2, where the electrical angle difference between θ2 and θ1 is 180° electrical angle;

[0059] The secondary locking measurement unit is used to repeat steps S2 and step S3 at the second predetermined position θ2 to calculate and obtain the second winding resistance value R γ ;

[0060] The difference calculation unit is used to calculate the resistance difference value ΔR of this measurement g = |R γ - R βRecord the measurement time t g and the corresponding operating parameters, including the ambient temperature T g , the cumulative operating duration of the motor ;

[0061] A sequence storage unit for storing ΔR g and associated parameters into a continuous monitoring sequence S = {S1, S2, …, S g , …, S w}, where , w is the cumulative number of monitoring times;

[0062] A fault analysis and alarm module for calculating the difference between the first winding resistance value and the second winding resistance value; analyzing the current resistance difference and the continuous monitoring sequence in combination with the dynamic reasonable threshold range and trend warning conditions determined by the threshold and warning condition construction module; if the resistance difference exceeds the dynamic reasonable threshold range, or if it is determined according to the trend warning conditions that the continuous monitoring sequence shows a significant upward trend and approaches the upper threshold limit, it is determined that there is a fault in the winding and a corresponding alarm is generated;

[0063] A difference value calculation unit for calculating the absolute difference ΔR between the first winding resistance value and the second winding resistance value current = |R γ -R β |;

[0064] A threshold comparison unit for calling the dynamic reasonable threshold range [L, U] determined by the threshold and warning condition construction module to judge whether ΔR current exceeds this range: if ΔR current < L or ΔR current > U, it is marked as threshold exceeding the standard;

[0065] A trend analysis unit for extracting the resistance difference values corresponding to the last q measurements arranged in chronological order in the continuous monitoring sequence S to form a continuous data subset with a length of q , and using the fixed window moving average method to calculate the moving average value, the formula is , if the current window moving average value is greater than the previous window moving average value and this feature appears in two or more consecutive windows, and at the same time the cumulative increase , and the latest difference value ΔR q > 80%×U, it is marked as trend warning;

[0066] A hierarchical alarm unit for determining that there is a fault in the winding if the threshold exceeding the standard condition of the threshold comparison unit or the trend warning condition of the trend analysis unit is satisfied, and generating two-level alarms: outputting "Winding resistance abnormal fault alarm" when the threshold exceeds the standard, and outputting "Winding resistance difference rising warning" when there is a trend warning.

[0067] Compared with the prior art, the beneficial effects of the present invention are:

[0068] 1. The initial angular position of the rotor is identified by the back electromotive force signal. Combined with electromagnetic balance current and closed-loop compensation control, the rotor is stably locked within ±0.2° electrical angle, eliminating magnetic field coupling error caused by rotor position fluctuation. A four-wire Kelvin connection method is adopted to avoid interference from wire resistance. The voltage is sampled three times and the average value is taken, which greatly reduces the measurement error.

[0069] 2. By combining resistance difference analysis from multiple locations with trend judgment from continuous monitoring sequences, early identification of winding faults can be achieved through early warning of moving average and cumulative increase, avoiding the lag of "post-fault response" in traditional methods;

[0070] 3. By using a graded alarm mechanism, potential risks such as winding aging and insulation damage can be detected in advance, reducing problems such as motor overheating and efficiency decline, extending the service life of the drive motor, and ensuring the safe operation of the power system of new energy vehicles. Attached Figure Description

[0071] Figure 1 This is a schematic diagram of the overall resistance measurement system for drive motors in new energy vehicles, as described in this invention.

[0072] Figure 2 This is a schematic diagram of the winding resistance measurement module of the overall resistance measurement system for drive motors of new energy vehicles, as described in this invention.

[0073] Figure 3 This is a flowchart illustrating the method for measuring the overall resistance of the drive motor of a new energy vehicle, according to the present invention. Detailed Implementation

[0074] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0075] Example: Figure 1 , Figure 2 and Figure 3 As shown, the present invention provides a technical solution, a method and system for measuring the overall resistance of the drive motor of a new energy vehicle.

[0076] Taking a certain type of permanent magnet synchronous drive motor with a rated speed of 12000 r / min and a stator resistance design value of (0.020Ω±5%) as the object, the complete measurement process was carried out by simulating the abnormal resistance caused by local aging of the winding.

[0077] The methods include:

[0078] Step S1: Obtain historical measurement data of the winding resistance of the target motor and corresponding operating parameters. By preprocessing the data and calculating the characteristic values, obtain the dynamic reasonable threshold range and trend warning conditions.

[0079] Step S2: Input a scanning current pulse into the stator winding of the motor and collect the back electromotive force signal to identify the initial angular position of the rotor; calculate and input the electromagnetic balance current based on the initial angular position to generate a zero torque between the magnetic field of the rotor permanent magnet and the static magnetic field of the stator, thereby locking the rotor in the first predetermined position.

[0080] Step S3: The compensation current is dynamically adjusted through closed-loop control to suppress rotor displacement disturbance and maintain the rotor in a stable locked state at the first predetermined position; while maintaining the locked state, a DC measurement current is applied to the stator winding, and the voltage drop across the winding is collected using the four-wire Kelvin connection method to calculate the first winding resistance value.

[0081] Step S4: Control the rotor to rotate to the second predetermined position, repeat the locking control and resistance measurement process of steps S2 to S3, obtain the resistance value of the second winding; synchronously record the current resistance difference data and update it to the continuous monitoring sequence;

[0082] Step S5: Calculate the difference between the resistance values ​​of the first winding and the second winding; combine the dynamic reasonable threshold range and trend warning conditions determined in step S1 to analyze the current resistance difference and continuous monitoring sequence; if the resistance difference exceeds the dynamic reasonable threshold range, or if the continuous monitoring sequence shows a significant upward trend and approaches the upper limit of the threshold according to the trend warning conditions, then it is determined that there is a fault in the winding and a corresponding alarm is generated.

[0083] Furthermore, step S1 includes:

[0084] Step S1-1: Collect 30 historical winding resistance measurement data of the target motor to form an initial dataset R={R1=0.018Ω, R2=0.019Ω, …, R n =0.022Ω}, and synchronously record the ambient temperature T for each measurement. i (25℃~30℃) and motor running time t i (800h~1000h);

[0085] Step S1-2: Preprocess the initial dataset according to the 3σ criterion and calculate the initial average. Standard deviation Two outliers, 0.015Ω and 0.028Ω, with a deviation exceeding 3 × 0.0018Ω = 0.0054Ω, were removed, resulting in the valid dataset. After grouping according to the 25℃ operating condition, calculate the average value of the group. Standard deviation ;

[0086] Step S1-3: Determine the dynamic reasonable threshold range based on statistical characteristic values. Take λ=2.0, calculate the lower threshold L=μ-λ·σ=0.0203-2×0.0012=0.0179Ω, the upper threshold U=μ+λ·σ=0.0203+2×0.0012=0.0227Ω, and the dynamic reasonable threshold range is [L, U]=[0.0179Ω, 0.0227Ω];

[0087] Step S1-4: Set trend warning conditions: Continuous monitoring count q=5, preset minimum increase threshold Δ0=0.002Ω. When the moving average of the resistance difference values ​​for 5 consecutive measurements shows an upward trend, and the cumulative increase... Timely triggering of warnings;

[0088] Step S1-5: Since the cumulative new measurement data has reached 10 times, repeat steps S1-1 to S1-4 to update the parameters: After the update, μ=0.0208Ω, σ=0.0013Ω, λ is adjusted to 2.1, and the threshold range is updated to [0.0182Ω, 0.0234Ω].

[0089] Furthermore, step S2 includes:

[0090] Step S2-1: Input an 8A / 15ms scanning current pulse into the three-phase stator windings of the motor, synchronously acquire the back electromotive force signal, and record the peak time t of the back electromotive force of phase A winding in the signal waveform. a =0.026s;

[0091] Step S2-2: Calculate the initial angular position of the rotor based on the peak time of the back EMF. The motor speed is r = 95 r / min ≈ 1.583 r / s, the number of pole pairs is p = 3, and the starting time of the scanning current pulse is t0 = 0.010 s. Substitute these values ​​into the formula θ0 = 2πrp·(t a -t0)=2π×1.583×3×0.016≈0.475rad, the process of converting radians to electrical degrees: 1rad=(180 / π)°, electrical degree=mechanical degree×number of pole pairs, the result calculated here is mechanical degree, so electrical degree=0.475rad×(180 / π)×3≈0.475×57.3×3≈27.2° electrical degree;

[0092] Step S2-3: Based on the initial angular position of the rotor θ0 = 27.2°, define the angle between the stator magnetic field and the rotor permanent magnet magnetic field as α, and based on the motor torque formula M = k u When α = 0°, the electromagnetic torque M = 0, which is the zero-torque. The stator magnetic field phase is set to θ0, so that the electromagnetic balance current I... b The phase is matched with θ0=27.2°, the current amplitude is 12A, and the torque balance principle of step S2 is strictly followed.

[0093] Step S2-4: Input electromagnetic balancing current I into the stator winding b The rotor position change Δθ = 0.45° electrical angle is monitored in real time. Since Δθ ≤ 0.5° electrical angle, it is determined that the rotor has been locked in the first predetermined position θ1 = 27.2°.

[0094] Furthermore, step S3 includes:

[0095] Step S3-1: Monitor the current rotor position θ in real time and calculate the deviation Δθ = θ - θ1 = θ - 27.2° from the first predetermined position θ1;

[0096] Step S3-2: Using the position deviation Δθ as input, calculate the compensation current using a proportional controller, with the proportional coefficient k v =1.2A / ° electrical angle, the formula is ΔI=k v ×Δθ=1.2×Δθ, total control current I total =I b +ΔI=12A+ΔI;

[0097] Step S3-3: The total control current generates adjustment torque to drive the rotor to deflect. Repeat steps S3-1 to S3-2 to form closed-loop feedback control. The position deviations of the five consecutive samples are 0.19°, 0.15°, 0.20°, 0.17° and 0.18°, respectively. All of them satisfy |Δθ|≤±0.2° electrical angle, and it is determined that the rotor maintains a stable locked state.

[0098] Step S3-4: In the stable locked state, disconnect the control current loop and apply a DC measuring current I to the stator winding through an independent current loop. d =40A, using a four-wire Kelvin connection method: two current lines are connected in series in the current measurement loop, and two voltage lines are directly connected to the two ends of the winding to collect the winding voltage drop U. d ;

[0099] Step S3-5: Calculate the resistance value of the first winding, using the average value of three voltage samples. , ;

[0100] Furthermore, step S4 includes:

[0101] Step S4-1: The stepper drive current adopts an S-shaped acceleration and deceleration curve, with a maximum stepper current of 20 A and an acceleration of 1000° / s 2 , ensuring that the rotor rotates smoothly from θ1 = 27.2° to θ2 = 27.2° + 180° = 207.2° electrical angle. The rotation process takes 1.2 s without overshoot.

[0102] Step S4-2: The second position measurement data is complete: Repeat the locking process of steps S2 - S3. The three voltage values measured at θ2 are 1.00 V, 1.01 V, and 0.99 V, and the average value U d = 1.00 V. Calculate the resistance of the second winding ;

[0103] Step S4-3: Calculate ΔR g = |0.025 - 0.023| = 0.002 Ω. The measurement time is accurate to the second t g = 2025-08-21-16:30:22, and the ambient temperature T g = 28.5 °C, and the cumulative operation duration = 980.5 h;

[0104] Step S4-4: Store ΔR g and associated parameters into the continuous monitoring sequence , .

[0105] Further, step S5 includes:

[0106] Step S5-1: Calculate the absolute difference ΔR between the resistance value of the first winding and the resistance value of the second winding current = 0.002 Ω;

[0107] Step S5-2: Call the updated threshold range [0.0182 Ω, 0.0234 Ω]. Since 0.0020 Ω < 0.0182 Ω, it meets the over-standard condition of "ΔR current < L", and is marked as threshold over-standard;

[0108] Step S5-3: Extract the recent 5 difference values {0.0012 Ω, 0.0014 Ω, 0.0016 Ω, 0.0018 Ω, 0.0020 Ω}, and calculate the moving average , the average value of the previous window is 0.0013 Ω, showing an upward trend, and the cumulative increase =(0.0014-0.0012)+(0.0016-0.0014)+(0.0018-0.0016)+(0.0020-0.0018)=0.0008Ω<Δ0=0.002Ω, but the latest difference value 0.0020Ω>80%×U=0.8×0.0234=0.0187Ω, which satisfies some trend characteristics;

[0109] Step S5-4: Because the threshold exceeds the limit, output a first-level alarm "winding resistance abnormality fault alarm".

[0110] The system includes: a threshold and early warning condition construction module, a rotor initial locking module, a winding resistance measurement module, a multi-position measurement and sequence update module, and a fault analysis and alarm module;

[0111] The threshold and early warning condition construction module is used to obtain historical measurement data of the winding resistance of the target motor and corresponding operating parameters. By preprocessing the data and calculating the characteristic value, the dynamic reasonable threshold range and trend early warning conditions are obtained.

[0112] The historical data acquisition unit is used to collect historical measurement data of the winding resistance of the target motor, forming an initial dataset R={R1, R2, ..., R...} i , ..., R n}, where n is the number of historical measurements, and R i This represents the winding resistance value measured in the i-th measurement; the motor operating parameters at each measurement are recorded synchronously, including the ambient temperature T. i and motor running time t i ;

[0113] The data preprocessing unit is used to preprocess the initial dataset by removing outliers using the 3σ criterion. Outliers are measurements whose deviation from the mean of the initial dataset exceeds three times the standard deviation, where the standard deviation is a measure of the dispersion of the initial dataset, and is calculated using the following formula: Where μ0 is the average value of the initial dataset, ; Obtain a valid dataset Where m≤n; after grouping by operating parameters, calculate the statistical characteristic values ​​of each group of valid data, including the average value. and standard deviation ;

[0114] The threshold calculation unit is used to determine the dynamic reasonable threshold range based on statistical characteristic values. The lower threshold is set as L=μ-λ·σ, and the upper threshold is set as U=μ+λ·σ, where λ is an adjustable coefficient and 1.5≤λ≤3. The dynamic reasonable threshold range is represented as [L, U].

[0115] The warning condition setting unit is used to set the warning condition when the resistance difference value of q consecutive measurements is... The moving average shows an upward trend, and the cumulative increase is... When a trend warning is triggered, q is the number of consecutive monitoring times and Δ0 is the preset minimum increase threshold.

[0116] The parameter update unit is used to repeat the historical data acquisition unit to the early warning condition setting unit when 10 new measurement data are accumulated, and update the parameters λ, q, and Δ0 in the dynamic reasonable threshold range and trend early warning conditions.

[0117] The rotor initial locking module is used to input scanning current pulses to the stator windings of the motor, collect back electromotive force signals to identify the initial angular position of the rotor; calculate and input electromagnetic balance current based on the initial angular position, so as to generate a zero torque between the magnetic field of the rotor permanent magnet and the static magnetic field of the stator, thereby locking the rotor in the first predetermined position.

[0118] The scanning pulse input unit is used to input scanning current pulses to the three-phase stator windings of the motor, synchronously acquire back electromotive force signals, and record the peak time t of the three-phase winding back electromotive force in the signal waveform. a ;

[0119] The initial angle calculation unit is used to calculate the rotor's initial angular position θ0 based on the peak time of the back electromotive force. The calculation formula is θ0 = 2πrp·(t a -t0), where r is the motor speed, p is the number of motor pole pairs, and t0 is the start time of the scanning current pulse (t a -t0) is the time difference from the start of the scanning current pulse to the peak value of the back electromotive force, and θ0 is the time difference between the start of the current pulse and the peak value of the back electromotive force. a The spatial phase position of the rotor relative to the stator winding at any given moment, and θ0 serves as the first reference position identified by the back electromotive force characteristics in the entire rotor locking and resistance measurement process;

[0120] The balance current generation unit is used to calculate the electromagnetic balance current I based on the rotor's initial angular position θ0. b The phase of the rotor permanent magnet magnetic field is defined as θ0, where θ0 represents the spatial phase of the rotor permanent magnet magnetic field. The angle between the stator magnetic field and the rotor permanent magnet magnetic field is defined as α, based on the motor torque formula M=k u ·I·Φ·sinα, where M is the electromagnetic torque, k u Let I be the torque coefficient, Φ be the winding current, and Φ be the permanent magnet flux. When α = 0°, the electromagnetic torque M = 0, which is the zero-torque. By setting the stator magnetic field phase to θ0 and making α = 0°, the electromagnetic balance current I is obtained. b The phase matches θ0;

[0121] The locking determination unit is used to input an electromagnetic balance current I into the stator winding. bThe rotor position change Δθ is monitored in real time; when Δθ ≤ 0.5° electrical angle, it is determined that the rotor has been locked at the first predetermined position θ1.

[0122] The winding resistance measurement module is used to dynamically adjust the compensation current through closed-loop control to suppress rotor displacement disturbance and maintain the rotor in a stable locked state at the first predetermined position. In the locked state, a DC measurement current is applied to the stator winding, and the voltage drop across the winding is collected using a four-wire Kelvin connection method to calculate the first winding resistance value.

[0123] The position deviation monitoring unit is used to monitor the current position θ of the rotor in real time and calculate the deviation Δθ=θ-θ1 from the first predetermined position θ1;

[0124] The compensation current adjustment unit is used to calculate the compensation current ΔI using the position deviation Δθ as input and a proportional controller, with the formula ΔI=k v ×Δθ, where k v The proportionality coefficient is 0.5A / ° electrical angle ≤ k v ≤2A / ° electrical angle; superimpose the compensation current ΔI onto the electromagnetic balance current I. b The total control current I is obtained. total =I b +ΔI, and input the stator winding;

[0125] Stability locking determination unit, used for total control current I total The adjustment torque is generated by acting on the stator winding, driving the rotor to offset towards the first predetermined position θ1; the position deviation monitoring unit to the compensation current adjustment unit is repeatedly executed, and the new rotor position deviation is collected in real time and the total control current is dynamically adjusted to form a closed-loop feedback control; until the position deviation Δθ of 5 consecutive samples all meet |Δθ|≤±0.2° electrical angle, it is determined that the rotor maintains a stable locked state.

[0126] The measuring current application unit is used to cut off the control current loop and apply a DC measuring current I to the stator winding through an independent current loop in a stable locked state. d A four-wire Kelvin connection method is used, with two current lines connected in series in the current measurement loop and two voltage lines directly connected to the two ends of the winding to collect the winding voltage drop U. d ;

[0127] The voltage acquisition unit and resistance calculation unit are used to calculate the resistance value of the first winding. U d This is the average voltage value from three samples.

[0128] A multi-position measurement and sequence update module, which is used to control the rotor to step-rotate to the second predetermined position, repeatedly execute the locking control and resistance measurement processes from the rotor initial locking module to the winding resistance measurement module, and obtain the second winding resistance value; synchronously record the current resistance difference data and update it to the continuous monitoring sequence;

[0129] A stepping drive unit, which is used to stop inputting the electromagnetic balance current and compensation current, input the stepping drive current to the stator winding, and control the rotor to step-rotate from the first predetermined position θ1 to the second predetermined position θ2, where the electrical angle difference between θ2 and θ1 is 180° electrical angle;

[0130] A secondary locking measurement unit, which is used to repeat Step S2 and Step S3 at the second predetermined position θ2 to calculate and obtain the second winding resistance value R γ ;

[0131] A difference calculation unit, which is used to calculate the resistance difference value ΔR of this measurement g =丨R γ -R β 丨, record the measurement time t g and the corresponding operating condition parameters, including the ambient temperature T g and the cumulative operating duration of the motor ;

[0132] A sequence storage unit, which is used to store ΔR g and the associated parameters into the continuous monitoring sequence S={S1, S2,..., S g ,..., S w}, where , w is the cumulative number of monitoring times;

[0133] A fault analysis and warning module, which is used to calculate the difference between the first winding resistance value and the second winding resistance value; combine the dynamic reasonable threshold range and trend warning conditions determined by the threshold and warning condition construction module to analyze the current resistance difference and the continuous monitoring sequence; if the resistance difference exceeds the dynamic reasonable threshold range, or it is judged according to the trend warning conditions that the continuous monitoring sequence shows a significant upward trend and approaches the upper threshold limit, it is determined that there is a fault in the winding and a corresponding warning is generated;

[0134] A difference value calculation unit, which is used to calculate the absolute difference ΔR between the first winding resistance value and the second winding resistance value current =丨R γ -R β 丨;

[0135] A threshold comparison unit, which is used to call the dynamic reasonable threshold range [L, U] determined by the threshold and warning condition construction module to judge whether ΔR current exceeds this range: if ΔR current <L or ΔRcurrent If the value is >U, it is marked as exceeding the threshold.

[0136] The trend analysis unit is used to extract the resistance difference values ​​corresponding to the last q measurements in the continuous monitoring sequence S, arranged in chronological order, forming a continuous data subset of length q. The moving average is calculated using the fixed-window moving average method, and the formula is as follows: If the current window's sliding average is greater than the previous window's sliding average, and two or more consecutive windows exhibit this characteristic, and the cumulative increase is... And the latest difference value ΔR q If the value is greater than 80% × U, it will be marked as a trend warning;

[0137] The graded alarm unit is used to determine that there is a fault in the winding if the threshold exceeding the threshold condition of the threshold comparison unit or the trend warning condition of the trend analysis unit is met, and to generate two levels of alarms: when the threshold exceeds the limit, it outputs "winding resistance abnormality fault alarm", and when the trend warning is triggered, it outputs "winding resistance difference increase warning".

Claims

1. A method for measuring the overall resistance of a drive motor used in new energy vehicles, characterized in that: Includes the following steps: Step S1: Obtain historical measurement data of the winding resistance of the target motor and corresponding operating parameters. By preprocessing the data and calculating the characteristic values, obtain the dynamic reasonable threshold range and trend warning conditions. Step S2: Input a scanning current pulse into the stator winding of the motor and collect the back electromotive force signal to identify the initial angular position of the rotor; calculate and input the electromagnetic balance current based on the initial angular position to generate a zero torque between the magnetic field of the rotor permanent magnet and the static magnetic field of the stator, thereby locking the rotor in the first predetermined position. Step S3: The compensation current is dynamically adjusted through closed-loop control to suppress rotor displacement disturbance and maintain the rotor in a stable locked state at the first predetermined position; while maintaining the locked state, a DC measurement current is applied to the stator winding, and the voltage drop across the winding is collected using the four-wire Kelvin connection method to calculate the first winding resistance value. Step S4: Control the rotor to rotate to the second predetermined position, repeat the locking control and resistance measurement process of steps S2 to S3, obtain the resistance value of the second winding; synchronously record the current resistance difference data and update it to the continuous monitoring sequence; Step S5: Calculate the difference between the resistance values ​​of the first winding and the second winding; combine the dynamic reasonable threshold range and trend warning conditions determined in step S1 to analyze the current resistance difference and continuous monitoring sequence; if the resistance difference exceeds the dynamic reasonable threshold range, or if the continuous monitoring sequence shows a significant upward trend and approaches the upper limit of the threshold according to the trend warning conditions, then it is determined that there is a fault in the winding and a corresponding alarm is generated.

2. The method for measuring the overall resistance of a drive motor in a new energy vehicle according to claim 1, characterized in that: Step S1 includes: Step S1-1: Collect historical measurement data of the winding resistance of the target motor to obtain the initial dataset R={R1, R2, ..., R...} i , ...R n }, where n is the number of historical measurements, and R i The winding resistance value is measured for the i-th time; motor operating parameters, including ambient temperature T, are recorded synchronously for each measurement. i and motor running time t i ; Step S1-2: Use the 3σ criterion to remove outliers. Outliers are measurements whose deviation from the mean of the initial dataset exceeds three times the standard deviation. The standard deviation is a measure of the dispersion of the initial dataset and is calculated using the following formula: Where μ0 is the average value of the initial dataset, ; Obtain a valid dataset Where m≤n; after grouping by operating parameters, calculate the statistical characteristic values ​​of each group of valid data, including the average value. and standard deviation ; Step S1-3: Determine the dynamic reasonable threshold range based on statistical characteristic values. Set the lower threshold to L=μ-λ·σ and the upper threshold to U=μ+λ·σ, where λ is an adjustable coefficient and 1.5≤λ≤3. The dynamic reasonable threshold range is represented as [L, U]. Step S1-4: The resistance difference value after q consecutive measurements The moving average shows an upward trend, and the cumulative increase is... When a trend warning is triggered, q is the number of consecutive monitoring times and Δ0 is the preset minimum increase threshold. Step S1-5: When 10 new measurement data are accumulated, repeat steps S1-1 to S1-4 to update the parameters λ, q, and Δ0 in the dynamic reasonable threshold range and trend warning conditions.

3. The method for measuring the overall resistance of a drive motor in a new energy vehicle according to claim 1, characterized in that: Step S2 includes: Step S2-1: Input scanning current pulses into the three-phase stator windings of the motor, synchronously acquire back electromotive force signals, and record the peak time t of the three-phase winding back electromotive force in the signal waveform. a ; Step S2-2: Calculate the initial angular position θ0 of the rotor based on the peak time of the back electromotive force. The calculation formula is θ0 = 2πrp·(t a -t0), where r is the motor speed, p is the number of motor pole pairs, and t0 is the start time of the scanning current pulse (t a -t0) is the time difference from the start of the scanning current pulse to the peak value of the back electromotive force, and θ0 is the time difference between the start of the current pulse and the peak value of the back electromotive force. a The spatial phase position of the rotor relative to the stator winding at any given moment, and θ0 serves as the first reference position identified by the back electromotive force characteristics in the entire rotor locking and resistance measurement process; Step S2-3: Calculate the electromagnetic balance current I based on the initial angular position θ0 of the rotor. b The phase of the rotor permanent magnet magnetic field is defined as θ0, where θ0 represents the spatial phase of the rotor permanent magnet magnetic field. The angle between the stator magnetic field and the rotor permanent magnet magnetic field is defined as α, based on the motor torque formula M=k u ·I·Φ·sinα, where M is the electromagnetic torque, k u Let I be the torque coefficient, Φ be the winding current, and Φ be the permanent magnet flux. When α = 0°, the electromagnetic torque M = 0, which is the zero-torque. By setting the stator magnetic field phase to θ0 and making α = 0°, the electromagnetic balance current I is obtained. b The phase matches θ0; Step S2-4: Input electromagnetic balancing current I into the stator winding b The rotor position change Δθ is monitored in real time; when Δθ ≤ 0.5° electrical angle, it is determined that the rotor has been locked at the first predetermined position θ1.

4. The method for measuring the overall resistance of a drive motor in a new energy vehicle according to claim 1, characterized in that: Step S3 includes: Step S3-1: Monitor the current rotor position θ in real time and calculate the position deviation Δθ = θ - θ1 from the first predetermined position θ1; Step S3-2: Using the position deviation Δθ as input, calculate the compensation current ΔI using a proportional controller, with the formula ΔI=k v ×Δθ, where k v The proportionality coefficient is 0.5A / ° electrical angle ≤ k v ≤2A / ° electrical angle; superimpose the compensation current ΔI onto the electromagnetic balance current I. b The total control current I is obtained. total =I b +ΔI, and input the stator winding; Step S3-3: Total control current I total The adjustment torque is generated by acting on the stator winding, driving the rotor to offset towards the first predetermined position θ1; Steps S3-1 to S3-2 are repeated, and the new rotor position deviation is collected in real time and the total control current is dynamically adjusted to form a closed-loop feedback control; until the position deviation Δθ of 5 consecutive samples satisfies |Δθ|≤±0.2° electrical angle, it is determined that the rotor maintains a stable locked state. Step S3-4: In the stable locked state, disconnect the control current loop and apply a DC measuring current I to the stator winding through an independent current loop. d A four-wire Kelvin connection method is used, with two current lines connected in series in the current measurement loop and two voltage lines directly connected to the two ends of the winding to collect the winding voltage drop U. d ; Step S3-5: Calculate the resistance value of the first winding. U d This is the average voltage value from three samplings.

5. The method for measuring the overall resistance of a drive motor in a new energy vehicle according to claim 1, characterized in that: Step S4 includes: Step S4-1: Stop inputting electromagnetic balance current and compensation current, input stepping drive current to stator winding, and control rotor to rotate step by step from first predetermined position θ1 to second predetermined position θ2, wherein the electrical angle difference between θ2 and θ1 is 180° electrical angle. Step S4-2: At the second predetermined position θ2, repeat steps S2 and S3 to calculate the resistance value R of the second winding. γ ; Step S4-3: Calculate the resistance difference value ΔR of this measurement g = |R γ - R β |, record the measurement time t g and the corresponding operating conditions parameters, including the ambient temperature T g , the cumulative running time of the motor ; Step S4-4: Set ΔR g And the associated parameters are stored in the continuous monitoring sequence S={S1, S2, ..., S... g S w },in w represents the cumulative number of monitoring sessions.

6. The method for measuring the overall resistance of a drive motor in a new energy vehicle according to claim 1, characterized in that: Step S5 includes: Step S5-1: Calculate the absolute difference ΔR between the first winding resistance value and the second winding resistance value current = |R γ - R β |; Step S5-2: Call the dynamic reasonable threshold range [L, U] determined in step S1, and determine ΔR. current Does it exceed this range: If ΔR current <L or ΔR current If the value is >U, it is marked as exceeding the threshold. Step S5-3: Extract the resistance difference values ​​corresponding to the last q measurements in the continuous monitoring sequence S, arranged in chronological order, to form a continuous data subset of length q. The moving average is calculated using the fixed-window moving average method, and the formula is as follows: If the current window's sliding average is greater than the previous window's sliding average, and two or more consecutive windows exhibit this characteristic, and the cumulative increase is... And the latest difference value ΔR q If the value is greater than 80% × U, it is marked as a trend warning. Step S5-4: If the threshold exceeding condition of step S5-2 or the trend warning condition of step S5-3 is met, it is determined that there is a fault in the winding and a two-level alarm is generated: when the threshold exceeds the standard, output "winding resistance abnormal fault alarm"; when the trend warning is triggered, output "winding resistance difference rising warning".

7. A system for measuring the overall resistance of a drive motor in a new energy vehicle, used to perform the method for measuring the overall resistance of a drive motor in a new energy vehicle as described in any one of claims 1-6, characterized in that: The system includes: The module includes a threshold and early warning condition construction module, a rotor initial locking module, a winding resistance measurement module, a multi-position measurement and sequence update module, and a fault analysis and alarm module. The threshold and early warning condition construction module is used to obtain historical measurement data of the winding resistance of the target motor and corresponding operating parameters. By preprocessing the data and calculating the characteristic value, the dynamic reasonable threshold range and trend early warning conditions are obtained. The rotor initial locking module is used to input scanning current pulses into the motor stator windings and collect back electromotive force signals to identify the initial angular position of the rotor. Based on the initial angular position, the electromagnetic balance current is calculated and input to generate a zero-torque between the rotor permanent magnet magnetic field and the stator static magnetic field, thereby locking the rotor in the first predetermined position. The winding resistance measurement module is used to dynamically adjust the compensation current through closed-loop control to suppress rotor displacement disturbances and maintain the rotor in a stable locked state at the first predetermined position. While maintaining the locked state, a DC measuring current is applied to the stator winding, and the voltage drop across the winding is collected using a four-wire Kelvin connection method to calculate the resistance value of the first winding. The multi-position measurement and sequence update module is used to control the rotor to rotate to the second predetermined position, repeatedly execute the locking control and resistance measurement process from the rotor initial locking module to the winding resistance measurement module, obtain the second winding resistance value, and synchronously record the current resistance difference data and update it to the continuous monitoring sequence. The fault analysis and alarm module is used to calculate the difference between the resistance values ​​of the first winding and the second winding. By combining the dynamic reasonable threshold range and trend warning conditions determined by the threshold and warning condition construction module, the current resistance difference and continuous monitoring sequence are analyzed. If the resistance difference exceeds the dynamic reasonable threshold range, or if the continuous monitoring sequence shows a significant upward trend and approaches the upper limit of the threshold based on the trend warning condition, then the winding is determined to be faulty and a corresponding alarm is generated.

8. The whole-machine resistance measurement system for drive motors of new energy vehicles according to claim 7, characterized in that: The threshold and early warning condition construction module includes: The historical data acquisition unit is used to collect historical measurement data of the winding resistance of the target motor, and obtain an initial dataset R = {R1, R2, ..., R...} i , ...R n }, where n is the number of historical measurements, and R i The winding resistance value is measured for the i-th time; motor operating parameters, including ambient temperature T, are recorded synchronously for each measurement. i and motor running time t i ; The data preprocessing unit is used to remove outliers using the 3σ criterion. Outliers are measurements whose deviation from the mean of the initial dataset exceeds three times the standard deviation, where the standard deviation is a measure of the dispersion of the initial dataset and is calculated using the following formula: Where μ0 is the average value of the initial dataset, ; Obtain a valid dataset Where m≤n; after grouping by operating parameters, calculate the statistical characteristic values ​​of each group of valid data, including the average value. and standard deviation ; The threshold calculation unit is used to determine the dynamic reasonable threshold range based on statistical characteristic values. The lower threshold is set to L=μ-λ·σ, and the upper threshold is set to U=μ+λ·σ, where λ is an adjustable coefficient and 1.5≤λ≤3. The dynamic reasonable threshold range is represented as [L, U]. The warning condition setting unit is used to set the warning condition when the resistance difference value of q consecutive measurements is... The moving average shows an upward trend, and the cumulative increase is... When a trend warning is triggered, q is the number of consecutive monitoring times and Δ0 is the preset minimum increase threshold. The parameter update unit is used to repeat the historical data acquisition unit to the early warning condition setting unit when 10 new measurement data are accumulated, and update the parameters λ, q, and Δ0 in the dynamic reasonable threshold range and trend early warning conditions.

9. The whole-machine resistance measurement system for drive motors of new energy vehicles according to claim 7, characterized in that: The rotor initial locking module includes: The scanning pulse input unit is used to input scanning current pulses to the three-phase stator windings of the motor, synchronously acquire back electromotive force signals, and record the peak time t of the three-phase winding back electromotive force in the signal waveform. a ; The initial angle calculation unit is used to calculate the rotor's initial angular position θ0 based on the peak time of the back electromotive force. The calculation formula is θ0 = 2πrp·(t a -t0), where r is the motor speed, p is the number of motor pole pairs, and t0 is the start time of the scanning current pulse (t a -t0) is the time difference from the start of the scanning current pulse to the peak value of the back electromotive force, and θ0 is the time difference between the start of the current pulse and the peak value of the back electromotive force. a The spatial phase position of the rotor relative to the stator winding at any given moment, and θ0 serves as the first reference position identified by the back electromotive force characteristics in the entire rotor locking and resistance measurement process; The balance current generation unit is used to calculate the electromagnetic balance current I based on the rotor's initial angular position θ0. b The phase of the rotor permanent magnet magnetic field is defined as θ0, where θ0 represents the spatial phase of the rotor permanent magnet magnetic field. The angle between the stator magnetic field and the rotor permanent magnet magnetic field is defined as α, based on the motor torque formula M=k u ·I·Φ·sinα, where M is the electromagnetic torque, k u Let I be the torque coefficient, Φ be the winding current, and Φ be the permanent magnet flux. When α = 0°, the electromagnetic torque M = 0, which is the zero-torque. By setting the stator magnetic field phase to θ0 and making α = 0°, the electromagnetic balance current I is obtained. b The phase matches θ0; The locking determination unit is used to input an electromagnetic balance current I into the stator winding. b The rotor position change Δθ is monitored in real time; when Δθ ≤ 0.5° electrical angle, it is determined that the rotor has been locked at the first predetermined position θ1. The winding resistance measurement module includes: The position deviation monitoring unit is used to monitor the current position θ of the rotor in real time and calculate the deviation Δθ=θ-θ1 from the first predetermined position θ1; The compensation current adjustment unit is used to calculate the compensation current ΔI using the position deviation Δθ as input and a proportional controller, with the formula ΔI=k v ×Δθ, where k v The proportionality coefficient is 0.5A / ° electrical angle ≤ k v ≤2A / ° electrical angle; superimpose the compensation current ΔI onto the electromagnetic balance current I. b The total control current I is obtained. total =I b +ΔI, and input the stator winding; Stability locking determination unit, used for total control current I total The adjustment torque is generated by acting on the stator winding, driving the rotor to offset towards the first predetermined position θ1; the position deviation monitoring unit to the compensation current adjustment unit is repeatedly executed, and the new rotor position deviation is collected in real time and the total control current is dynamically adjusted to form a closed-loop feedback control; until the position deviation Δθ of 5 consecutive samples all meet |Δθ|≤±0.2° electrical angle, it is determined that the rotor maintains a stable locked state. The measuring current application unit is used to cut off the control current loop and apply a DC measuring current I to the stator winding through an independent current loop in a stable locked state. d A four-wire Kelvin connection method is used, with two current lines connected in series in the current measurement loop and two voltage lines directly connected to the two ends of the winding to collect the winding voltage drop U. d ; The voltage acquisition unit and resistance calculation unit are used to calculate the resistance value of the first winding. U d This is the average voltage value from three samplings.

10. The overall resistance measurement system for drive motors of new energy vehicles according to claim 7, characterized in that: The multi-location measurement and sequence update module includes: The stepper drive unit is used to stop the input electromagnetic balance current and compensation current, input stepper drive current to the stator winding, and control the rotor to rotate step by step from the first predetermined position θ1 to the second predetermined position θ2, wherein the electrical angle difference between θ2 and θ1 is 180° electrical angle. The secondary locking measurement unit is used to repeat steps S2 and S3 at the second predetermined position θ2 to calculate the second winding resistance value R. γ ; A difference calculation unit for calculating the resistance difference value ΔR of the current measurement g = |R γ - R β |, recording the measurement time t g and the corresponding operating condition parameters, including the ambient temperature T g , the cumulative operating duration of the motor ; Sequence storage unit, used to store ΔR g And the associated parameters are stored in the continuous monitoring sequence S={S1, S2, ..., S... g S w },in Where w is the cumulative number of monitoring times; The fault analysis and alarm module includes: A difference value calculation unit for calculating an absolute difference ΔR between a first winding resistance value and a second winding resistance value current = |R γ - R β |; The threshold comparison unit is used to call the dynamic reasonable threshold range [L, U] determined by the threshold and early warning condition construction module to determine ΔR. current Does it exceed this range: If ΔR current <L or ΔR current If the value is >U, it is marked as exceeding the threshold. The trend analysis unit is used to extract the resistance difference values ​​corresponding to the last q measurements in the continuous monitoring sequence S, arranged in chronological order, forming a continuous data subset of length q. The moving average is calculated using the fixed-window moving average method, and the formula is as follows: If the current window's sliding average is greater than the previous window's sliding average, and two or more consecutive windows exhibit this characteristic, and the cumulative increase is... And the latest difference value ΔR q If the value is greater than 80% × U, it is marked as a trend warning. The graded alarm unit is used to determine that there is a fault in the winding if the threshold exceeding the threshold condition of the threshold comparison unit or the trend warning condition of the trend analysis unit is met, and to generate two levels of alarms: when the threshold exceeds the limit, it outputs "winding resistance abnormality fault alarm", and when the trend warning is triggered, it outputs "winding resistance difference increase warning".

Images