Method, device and equipment for calculating core loss of permanent magnet synchronous motor and storage medium

Abstract

The application relates to a permanent magnet synchronous motor core loss calculation method and device, computer equipment and a storage medium, comprising: obtaining the direct-axis current and the quadrature-axis current of the stator of the permanent magnet synchronous motor and the electric angle of the rotor; separating the fundamental wave and the high-frequency harmonic of the permanent magnet synchronous motor from the direct-axis current and the quadrature-axis current of the stator according to the electric angle of the rotor; obtaining the frequency value and the amplitude value of the fundamental wave and the frequency value and the amplitude value of the high-frequency harmonic; obtaining the loss coefficient of the permanent magnet synchronous motor and the real-time temperature, wherein the loss coefficient comprises a hysteresis loss coefficient, and the loss coefficient is dynamically updated through a state equation and an observation equation constructed based on the permanent magnet synchronous motor; obtaining a core loss formula; and calculating the core loss of the permanent magnet synchronous motor according to the core loss formula, the loss coefficient of the permanent magnet synchronous motor and the real-time temperature, the frequency value and the amplitude value of the fundamental wave, and the frequency value and the amplitude value of the high-frequency harmonic. The above method realizes accurate dynamic calculation of the core loss under the high-frequency harmonic magnetic field.

Description

Technical Field

[0001] This application relates to the field of electromagnetic loss processing technology, and in particular to a method, apparatus, computer equipment, and storage medium for calculating the core loss of a permanent magnet synchronous motor. Background Technology

[0002] Currently, in the thermal management systems of permanent magnet synchronous motors, electromagnetic loss calculations often employ simplified formulas. For example, core losses are calculated solely based on the fundamental Steinmetz equation, resulting in low computational efficiency and insufficient accuracy. Furthermore, electromagnetic loss calculations suffer from large errors due to neglecting time-varying loss coefficients and harmonic effects. High-frequency harmonic compensation has poor versatility and limited effectiveness. The calibration and correction of loss coefficients lag behind changes in motor characteristics during operation. Ultimately, this leads to low modeling accuracy and weak adaptability in the thermal management system, making it difficult to meet the requirements for efficient heat dissipation and reliable operation. Summary of the Invention

[0003] Based on this, it is necessary to provide a method, device, computer equipment, and storage medium for calculating the core loss of a permanent magnet synchronous motor, in order to address the above-mentioned technical problems. This would enable accurate dynamic calculation of core loss under high-frequency harmonic magnetic fields, and compensate for the hysteresis drift caused by material aging by dynamically updating the loss coefficient, thereby solving the loss problem caused by the harmonic superposition effect in traditional models.

[0004] A method for calculating the core loss of a permanent magnet synchronous motor (PMSM) includes: obtaining the direct-axis current and quadrature-axis current of the stator and the electrical angle of the rotor; separating the fundamental wave and high-frequency harmonics of the PMSM from the direct-axis current and quadrature-axis current of the stator based on the rotor's electrical angle; obtaining the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of the high-frequency harmonics; obtaining the loss coefficient and real-time temperature of the PMSM, wherein the loss coefficient includes the hysteresis loss coefficient, and the loss coefficient is dynamically updated through a state equation and observation equation constructed based on the PMSM; obtaining the core loss formula; and calculating the core loss of the PMSM based on the core loss formula, the loss coefficient of the PMSM, the real-time temperature, the frequency and amplitude values ​​of the fundamental wave, and the frequency and amplitude values ​​of the high-frequency harmonics.

[0005] In one embodiment, the fundamental wave and high-frequency harmonics of the permanent magnet synchronous motor are separated from the direct-axis current and quadrature-axis current of the stator based on the rotor's electrical angle. This includes: transforming and mapping the direct-axis current and quadrature-axis current of the stator to a synchronous rotating coordinate system based on the rotor's electrical angle; extracting the coordinate information of the fundamental wave of the permanent magnet synchronous motor in the synchronous rotating coordinate system based on the coordinate information of the direct-axis current and quadrature-axis current of the stator in the synchronous rotating coordinate system and passing it through a low-pass filter; and performing an inverse transformation on the coordinate information of the fundamental wave of the permanent magnet synchronous motor in the synchronous rotating coordinate system to obtain the fundamental wave of the permanent magnet synchronous motor.

[0006] In one embodiment, the fundamental wave and high-frequency harmonics of the permanent magnet synchronous motor are separated from the direct-axis current and quadrature-axis current of the stator based on the rotor's electrical angle. This includes: determining the window length of a sliding window based on the rotor's electrical angle; sampling the direct-axis current and quadrature-axis current of the stator using the sliding window and performing spectrum calculation on the sampled direct-axis current and quadrature-axis current based on the window length of the sliding window to obtain a time-frequency matrix; performing demixing processing based on the time-frequency matrix to obtain time-frequency information of one or more independent signal sources; and constructing each high-frequency harmonic of the permanent magnet synchronous motor based on the time-frequency information of each independent signal source.

[0007] In one embodiment, acquiring the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of the high-frequency harmonics includes: when the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of each high-frequency harmonic are found to meet the electromagnetic theory constraints of the motor, and / or when the error between the total energy of the fundamental wave and each high-frequency harmonic and the total energy of the original signal is less than a set value, acquiring the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of each high-frequency harmonic, wherein the original signal is constructed by the direct-axis current and quadrature-axis current of the stator; or, identifying abnormal harmonics based on the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of each high-frequency harmonic, and acquiring the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of the high-frequency harmonics other than the abnormal harmonics.

[0008] In one embodiment, a method for calculating the core loss of a permanent magnet synchronous motor further includes: obtaining an amplitude correction formula, which expresses the relationship between the corrected amplitude value and the original amplitude value, as well as the local temperature and reference temperature of the core; obtaining the local temperature and reference temperature of the core; calculating the corrected amplitude value of the fundamental wave using the amplitude correction formula, the amplitude value of the fundamental wave, the local temperature and reference temperature of the core; and calculating the corrected amplitude value of the high-frequency harmonic using the amplitude correction formula, the amplitude value of the high-frequency harmonic, the local temperature and reference temperature of the core; and calculating the core loss of the permanent magnet synchronous motor according to the core loss formula, the loss coefficient of the permanent magnet synchronous motor, the real-time temperature, the frequency and amplitude values ​​of the fundamental wave, and the frequency and amplitude values ​​of the high-frequency harmonic, including: calculating the core loss of the permanent magnet synchronous motor according to the core loss formula, the loss coefficient of the permanent magnet synchronous motor, the real-time temperature, the frequency and corrected amplitude values ​​of the fundamental wave, and the frequency and corrected amplitude values ​​of the high-frequency harmonic.

[0009] In one embodiment, a method for calculating the core loss of a permanent magnet synchronous motor further includes: constructing a state equation and an observation equation for the permanent magnet synchronous motor, both of which contain parameters of the loss coefficient of the permanent magnet synchronous motor; and dynamically updating the loss coefficient of the permanent magnet synchronous motor based on the state equation and the observation equation using a recursive least squares method.

[0010] In one embodiment, a method for calculating the core loss of a permanent magnet synchronous motor further includes: inputting the core loss of the permanent magnet synchronous motor into a three-dimensional thermal model and obtaining the first temperature field distribution data output by the three-dimensional thermal model; adjusting the values ​​of the material parameters of the core of the permanent magnet synchronous motor based on the first temperature field distribution data, wherein the values ​​of the material parameters of the core affect the loss coefficient.

[0011] In one embodiment, a method for calculating the core loss of a permanent magnet synchronous motor further includes: performing equivalent circuit modeling on the stator slots of the permanent magnet synchronous motor along the axial layered windings to obtain the impedance model of each layer of stator windings; obtaining the mechanical angle of the stator slots and calculating the offset of the electrical angle based on the mechanical angle; calculating the induced electromotive force of each layer of stator windings based on the offset; calculating the impedance of each layer of stator windings based on the impedance model of each layer of stator windings; calculating the induced electromotive force difference vector of each layer based on the induced electromotive force of each layer of stator windings; obtaining the circulating current between each layer of stator windings based on the impedance of each layer of stator windings and the induced electromotive force difference vector of each layer; calculating the circulating current loss of each layer based on the circulating current between each layer of stator windings, and calculating the additional copper loss based on the circulating current loss of each layer; obtaining the fundamental copper loss generated by the fundamental wave, and obtaining the total copper loss of the permanent magnet synchronous motor based on the fundamental copper loss and the additional copper loss.

[0012] In one embodiment, a method for calculating the core loss of a permanent magnet synchronous motor further includes: inputting the core loss and total copper loss of the permanent magnet synchronous motor into a three-dimensional thermal model and obtaining second temperature field distribution data output by the three-dimensional thermal model; adjusting the values ​​of the material parameters of the core of the permanent magnet synchronous motor based on the second temperature field distribution data, wherein the values ​​of the material parameters of the core affect the loss coefficient.

[0013] In one embodiment, a method for calculating the core loss of a permanent magnet synchronous motor further includes: obtaining the frequency value, reference temperature, and material resistance temperature coefficient of the stator winding of the permanent magnet synchronous motor; updating the impedance of each layer of stator winding based on the real-time temperature, the frequency value, reference temperature, and material resistance temperature coefficient of the stator winding; updating the circulating current between each layer of stator winding based on the updated impedance of each layer of stator winding and the induced electromotive force difference vector of each layer; updating the circulating current loss of each layer based on the updated circulating current between each layer of stator winding; updating the additional copper loss based on the updated circulating current loss of each layer; and obtaining the total copper loss of the permanent magnet synchronous motor based on the fundamental copper loss and the updated additional copper loss.

[0014] A core loss calculation device for a permanent magnet synchronous motor (PMSM) includes: a first acquisition module for acquiring the direct-axis current and quadrature-axis current of the stator and the electrical angle of the rotor of the PMSM; a separation module for separating the fundamental wave and high-frequency harmonics of the PMSM from the direct-axis current and quadrature-axis current of the stator based on the electrical angle of the rotor; a second acquisition module for acquiring the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of the high-frequency harmonics; a third acquisition module for acquiring the loss coefficient and real-time temperature of the PMSM, wherein the loss coefficient includes the hysteresis loss coefficient, and the loss coefficient is dynamically updated through a state equation and observation equation constructed based on the PMSM; a fourth acquisition module for acquiring the core loss formula; and a calculation module for calculating the core loss of the PMSM based on the core loss formula, the loss coefficient of the PMSM, the real-time temperature, the frequency and amplitude values ​​of the fundamental wave, and the frequency and amplitude values ​​of the high-frequency harmonics.

[0015] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of any of the methods described above.

[0016] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the methods described above.

[0017] The aforementioned method, apparatus, computer equipment, and storage medium for calculating the core loss of a permanent magnet synchronous motor (PMSM) acquire the direct-axis and quadrature-axis currents of the stator and the electrical angle of the rotor. Based on the rotor's electrical angle, the fundamental wave and high-frequency harmonics of the PMSM are separated from the direct-axis and quadrature-axis currents of the stator. The frequency and amplitude values ​​of the fundamental wave and the high-frequency harmonics are acquired. The loss coefficient and real-time temperature of the PMSM are obtained, including the hysteresis loss coefficient, which is dynamically updated using state equations and observation equations constructed based on the PMSM. The core loss formula is obtained. Based on the core loss formula, the loss coefficient of the PMSM, the real-time temperature, the frequency and amplitude values ​​of the fundamental wave, and the frequency and amplitude values ​​of the high-frequency harmonics, the core loss of the PMSM is calculated. Therefore, accurate dynamic calculation of core loss under high-frequency harmonic magnetic fields is achieved, and the drift of hysteresis characteristics caused by material aging is compensated by dynamically updating the loss coefficient, solving the loss problem caused by harmonic superposition effects in traditional models. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating a method for calculating the core loss of a permanent magnet synchronous motor in one embodiment.

[0019] Figure 2 This is a structural block diagram of a core loss calculation device for a permanent magnet synchronous motor in one embodiment;

[0020] Figure 3 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] In one embodiment, such as Figure 1 As shown, a method for calculating the core loss of a permanent magnet synchronous motor is provided, including the following steps:

[0023] S101, obtain the direct-axis current and quadrature-axis current of the stator of the permanent magnet synchronous motor and the electrical angle of the rotor.

[0024] In this embodiment, the direct-axis current id(t) and quadrature-axis current iq(t) of the stator are acquired by a high-frequency current sensor, and combined with the rotor position θ, the harmonic components are extracted in real time using a sliding window short-time Fourier transform (STFT). Specifically, the sensor is configured as follows: the bandwidth of the high-frequency current sensor is ≥200kHz, and the sampling frequency is ≥500kHz, to capture the transient waveforms of the direct-axis current id(t) and quadrature-axis current iq(t) of the stator. The high-frequency current sensor can be a Rogowski coil. The rotor position sensor can be a rotary transformer to obtain the rotor's electrical angle θ in real time. r The accuracy is ≤0.1°. In addition, a phase-locked loop (PLL) is used to align the current sampling with the rotor position, eliminating phase jitter caused by mechanical speed fluctuations.

[0025] S102 separates the fundamental wave and high-frequency harmonics of the permanent magnet synchronous motor from the direct-axis current and quadrature-axis current of the stator based on the rotor's electrical angle.

[0026] S103, acquires the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of the high-frequency harmonics.

[0027] In one example of this embodiment, the separation of the fundamental wave and high-frequency harmonics of the permanent magnet synchronous motor from the direct-axis current and quadrature-axis current of the stator based on the rotor's electrical angle includes: transforming and mapping the direct-axis current and quadrature-axis current of the stator to a synchronous rotating coordinate system based on the rotor's electrical angle; extracting the coordinate information of the fundamental wave of the permanent magnet synchronous motor in the synchronous rotating coordinate system based on the coordinate information of the direct-axis current and quadrature-axis current of the stator in the synchronous rotating coordinate system and passing it through a low-pass filter; and performing an inverse transformation on the coordinate information of the fundamental wave of the permanent magnet synchronous motor in the synchronous rotating coordinate system to obtain the fundamental wave of the permanent magnet synchronous motor.

[0028] Specifically, the fundamental component is extracted using the synchronous rotating coordinate system method:

[0029] The three-phase currents ii and iq are the direct-axis current id(t) and the quadrature-axis current it. a i b i c The Clarke-Park transformation maps the coordinates to a synchronous rotating coordinate system, and the specific transformation formula is shown below.

[0030]

[0031] Among them, i d i q These represent the expressions for the direct-axis current id(t) and quadrature-axis current iq(t) in the synchronous rotating coordinate system, respectively.

[0032] i is extracted using a low-pass filter. d i q The fundamental component i in d1 i q1 The cutoff frequency of the low-pass filter can be twice the fundamental frequency. Finally, based on the fundamental component i... d1 i q1 Reconstructing the fundamental wave i using the inverse Park transform abc1 (t), and then calculate the amplitude value B1(t) of the fundamental wave.

[0033] In one example of this embodiment, the separation of the fundamental wave and high-frequency harmonics of the permanent magnet synchronous motor from the direct-axis current and quadrature-axis current of the stator based on the rotor's electrical angle includes: determining the window length of the sliding window based on the rotor's electrical angle; sampling the direct-axis current and quadrature-axis current of the stator using the sliding window and performing spectrum calculation on the sampled direct-axis current and quadrature-axis current based on the window length of the sliding window to obtain a time-frequency spectrum matrix; performing demixing processing based on the time-frequency spectrum matrix to obtain time-frequency information of one or more independent signal sources; and constructing each high-frequency harmonic of the permanent magnet synchronous motor based on the time-frequency information of each independent signal source.

[0034] Specifically, a time-frequency domain joint analysis framework is used to extract the high-frequency harmonics of the permanent magnet synchronous motor. First, a short-time Fourier transform (STFT) is constructed using an adaptive window. The Blackman-Harris window is used as the window function to suppress spectral leakage. The window length is dynamically adjusted using the following formula:

[0035]

[0036] Where f s f is the sampling rate; max The highest frequency of interest value, such as 3 times the switching frequency value; β = 2.5 is the overlap factor; N win This is the window length.

[0037] Spectrum calculation based on the above window length:

[0038]

[0039] In the above equation, the Short-Time Fourier Transform (STFT) is represented, indicating the transformation after a window length N. win The signal x(n) is divided into frames, and each frame is weighted by a window function w(k) and then subjected to a Fourier transform.

[0040] x(t+k) represents the k-th sample at time t; w(k) represents the window function, such as the Hanning window, to reduce spectral leakage.

[0041] This represents the Fourier basis functions, where the corresponding frequency value f is the normalized frequency value. s The sampling rate.

[0042] The resolution design includes:

[0043] Frequency resolution: Δf = f s / N win ≤10Hz, therefore N win ≥f s / 10.

[0044] Time resolution: determined by window shift hop, Δt = hop / f s ≤0.1ms=0.0001s, therefore hop≤fs·0.0001.

[0045] f s Let's take 44.1kHz as an example for explanation:

[0046] N win =4410 (satisfying Δf = 10Hz); hop = 4 (satisfying Δt ≈ 0.0907ms ≤ 0.1ms).

[0047] Specifically, the construction of the spectrum matrix X(t,f):

[0048] Dimension: Rows (frequency) × Columns (time).

[0049] Frequency range: 0≤f <N win / 2, total N win / 2 frequency points (10Hz resolution).

[0050] Time range: Within the total signal duration, each hop sample corresponds to one column (resolution 0.0907ms).

[0051] Calculation process: For each frame of signal (starting at t, containing N) winThe sample is subjected to a window function and then a Discrete Fourier Transform (DFT) to obtain the complex spectrum X(t,f), where f is the frequency index (0≤f). <N win Take the first N. win / 2 positive frequency components.

[0052] The symbols in the above formula are explained as follows:

[0053] In x(t+k): x represents the input time-domain signal (a discrete-time sequence, such as the sampled value of audio, vibration, etc.); t represents the sample index at the start of the frame; k represents the sample index within the frame (0≤k). <N win Therefore, x(t+k) is the kth sample in the t-th frame (used for frame segmentation processing of short-time Fourier transform).

[0054] f represents frequency: Discrete Frequency Index (the frequency bin number in the DFT, ranging from 0 to f). <N win ).

[0055] The corresponding actual frequency is Frequency resolution is For example, if f s =44.1kHz, N win =4410, then f=1 corresponds to 10Hz, f=2 corresponds to 20Hz, and so on. The positive frequency range is 0≤f <N win / 2, covering the signal spectrum within the Nyquist frequency range.

[0056] Specifically, an improved SVD-ICA hybrid algorithm is used to separate high-frequency harmonics:

[0057] First, construct the time-frequency matrix: reorganize the time-frequency spectrum matrix x(t+k) output by STFT into a two-dimensional matrix X∈C by frequency slices. M×N Where M is the number of time points and N is the number of frequency points.

[0058] Singular Value Decomposition (SVD) dimensionality reduction: X = UεV H ;

[0059] Wherein, matrix U represents the left singular matrix, the principal component of the row space; physical meaning: the row space (left subspace) of the data, reflecting the direction of the principal components of the data in the row dimension, such as the time-domain / spatial-domain characteristics of the signal.

[0060] Matrix V represents the right singular matrix, the principal component of the column space; physical meaning: the column space (right subspace) of the data, reflecting the direction of the principal components of the data in the column dimension, such as the frequency domain / modal characteristics of the signal.

[0061] The matrix ε represents the singular value matrix; its physical meaning is to quantify the contribution of each singular vector to the original data. Large singular values ​​correspond to the principal components, while small singular values ​​correspond to noise / minor components. During dimensionality reduction, the first k singular values ​​can be truncated and retained.

[0062] The superscript H indicates the conjugate transpose, also known as the Hermitian transpose.

[0063] Furthermore, retaining the first K principal components (K is determined by energy percentage > 99%), we reconstruct the dimensionality-reduced matrix:

[0064]

[0065] Then, independent component analysis (ICA) was used for unmixing:

[0066] Assume the observed signal is a linear mixture of harmonic source signals:

[0067] The following harmonics are separated by estimating the mixing matrix A and the independent source signal S using the FastICA algorithm:

[0068] Carrier harmonics: PWM sideband harmonics concentrated near the switching frequency;

[0069] Space harmonics: Low-order harmonics caused by the cogging effect of motor teeth;

[0070] Random noise: Gaussian white noise and measurement noise.

[0071] Finally, reconstruct the harmonics and extract the parameters:

[0072] Perform a Hilbert transform on each independent source signal S to extract the instantaneous amplitude value B. n (t) and frequency value f n (t):

[0073]

[0074] For the instantaneous amplitude value B n The meaning of formula (t): For signal s i (t) is subjected to the Hilbert transform, denoted as H(s) i (t) is combined with the original signal to form the analytic signal z(t) = s. i (t)+jH(s i (t)).

[0075] The modulus of the analytic signal, i.e., the amplitude value of the complex number, is the instantaneous amplitude value Bn(t), representing the envelope of the signal at time t. Physical meaning: This formula expands the real signal into a complex signal through the Hilbert transform, thereby directly extracting the time-varying amplitude characteristics of the signal, and is suitable for non-stationary signal analysis.

[0076] For the instantaneous amplitude f n The meaning of the formula z(t): Analytical signal z(t) = s i (t)+jH(s i The phase of z(t) is θ(t) = arg(z(t)). The instantaneous frequency value is defined as the derivative of the phase with respect to time divided by 2π. Physical meaning: The instantaneous frequency value reflects the frequency change characteristics of the signal at time t.

[0077] H(s i (t) represents the signal s i (t) is the result of performing the Hilbert Transform.

[0078] Therefore, frequency domain decomposition of permanent magnet synchronous motors was realized, accurately separating the fundamental wave and high-frequency harmonic components from the dynamic electromagnetic field, solving the problem of spectrum leakage and aliasing in traditional Fourier transform under unsteady conditions, and providing accurate harmonic amplitude and frequency values ​​as input for multi-frequency domain loss modeling.

[0079] In one example, the window length of the sliding window is automatically adjusted according to the rate of change of motor speed dω / dt.

[0080] Specifically, acceleration mode: shorten the window (N) win =1024 points), improving time resolution to 0.5ms. Steady-state condition: Extend window (N win =4096 points), increasing the frequency resolution to 5Hz.

[0081] In one example, the low-pass filter is constructed using a combination of multiple filters.

[0082] Specifically, an aliased low-pass filter is constructed by combining a cascaded integrator comb (CIC) filter with a finite impulse response (FIR) filter. The CIC filter consists of 5 cascaded stages, reducing the sampling rate to fs. s / 8, suppressing high-frequency noise. FIR compensated filter: least squares design, passband ripple <0.1dB, stopband attenuation >80dB.

[0083] In one embodiment, the acquisition of the fundamental frequency and amplitude values, as well as the frequency and amplitude values ​​of the high-frequency harmonics, includes: acquiring the fundamental frequency and amplitude values, as well as the frequency and amplitude values ​​of each high-frequency harmonic, when the fundamental frequency and amplitude values ​​and each high-frequency harmonic are found to meet the electromagnetic theory constraints of the motor; and / or, when the error between the total energy of the fundamental and each high-frequency harmonic and the total energy of the original signal is less than a set value, wherein the original signal is constructed by the direct-axis current and quadrature-axis current of the stator; or, identifying abnormal harmonics based on the fundamental frequency and amplitude values ​​and the frequency and amplitude values ​​of each high-frequency harmonic, and acquiring the fundamental frequency and amplitude values, as well as the frequency and amplitude values ​​of the high-frequency harmonics other than the abnormal harmonics.

[0084] Specifically, the dynamic amplitude-frequency correlation check verifies whether the amplitude and frequency values ​​of each harmonic conform to the electromagnetic theory constraints of the motor. Energy conservation verification ensures that the total energy of the separated harmonics has an error of less than 1% compared to the original signal. Abnormal harmonic removal uses Mahalanobis distance to detect outlier harmonic components and eliminates spurious harmonics caused by sensor noise or transient interference.

[0085] S104: Obtain the loss coefficient and real-time temperature of the permanent magnet synchronous motor. The loss coefficient includes the hysteresis loss coefficient. The loss coefficient is dynamically updated through the state equation and observation equation constructed based on the permanent magnet synchronous motor.

[0086] In one example of this embodiment, before step S104, the method further includes: constructing the state equation and observation equation of the permanent magnet synchronous motor, both of which contain parameters of the loss coefficient of the permanent magnet synchronous motor; and dynamically updating the loss coefficient of the permanent magnet synchronous motor based on the state equation and observation equation using the recursive least squares method.

[0087] In this embodiment, the loss coefficients include hysteresis loss coefficient, eddy current loss coefficient, and abnormal loss coefficient. The loss coefficients are obtained by dynamically updating the state equations and observation equations based on the permanent magnet synchronous motor using a recursive least squares method. Real-time temperature is obtained through real-time feedback from an embedded fiber optic sensor.

[0088] S105, obtain the core loss formula.

[0089] In this embodiment, the core loss formula is:

[0090]

[0091] Where, k h k is the hysteresis loss coefficient. e K is the eddy current loss coefficient. aThe abnormal loss coefficient is denoted by , and all loss coefficients are initialized experimentally. T represents the real-time temperature, which is fed back in real time through an embedded fiber optic sensor to correct for the temperature dependence of material parameters.

[0092] Online loss coefficient identification: Define the system's state equation and observation equation, and dynamically update the loss coefficient using the recursive least squares (RLS) method.

[0093] State equation: θ(k+1)=θ(k)+Δθ(k);

[0094] Observation equation: y(k)=h(k)θ(k)+e(k);

[0095] Where θ(k) is the loss coefficient vector to be identified; y(k) is the output of the system (such as motor loss, temperature, etc.); h(k) is the regression vector; and e(k) is the observation noise.

[0096] The loss coefficients are updated using the recursive least squares method:

[0097]

[0098] K(k+1)=P(k)h T (k+1)[h(k+1)P(k)h T (k+1)+λ] -1

[0099]

[0100] in, Here, λ represents the estimated loss coefficient, K(k) is the gain matrix, P(k) is the covariance matrix, and λ is the forgetting factor. The loss coefficient here can be any one of the following: hysteresis loss coefficient, eddy current loss coefficient, or abnormal loss coefficient.

[0101] S106. Calculate the core loss of the permanent magnet synchronous motor based on the core loss formula, the loss coefficient of the permanent magnet synchronous motor, and the real-time temperature, the frequency and amplitude of the fundamental wave, and the frequency and amplitude of the high-frequency harmonics.

[0102] In this embodiment, the loss coefficient of the permanent magnet synchronous motor, as well as the real-time temperature, the frequency and amplitude of the fundamental wave, and the frequency and amplitude of the high-frequency harmonics, are used to calculate the core loss of the permanent magnet synchronous motor. The result is the core loss output by the core loss formula.

[0103] The aforementioned method for calculating the core loss of a permanent magnet synchronous motor (PMSM) involves obtaining the direct-axis and quadrature-axis currents of the stator and the electrical angle of the rotor. Based on the rotor's electrical angle, the fundamental wave and high-frequency harmonics of the PMSM are separated from the direct-axis and quadrature-axis currents of the stator. The frequency and amplitude values ​​of the fundamental wave and the high-frequency harmonics are obtained. The loss coefficient and real-time temperature of the PMSM are acquired, including the hysteresis loss coefficient, which is dynamically updated using state equations and observation equations constructed based on the PMSM. The core loss formula is then obtained. Based on the core loss formula, the loss coefficient of the PMSM, the real-time temperature, the frequency and amplitude values ​​of the fundamental wave, and the frequency and amplitude values ​​of the high-frequency harmonics, the core loss of the PMSM is calculated. Therefore, this method achieves accurate dynamic calculation of core loss under high-frequency harmonic magnetic fields and compensates for hysteresis drift caused by material aging by dynamically updating the loss coefficient, thus solving the loss problem caused by harmonic superposition effects in traditional models.

[0104] In one embodiment, after step S106, the method further includes: obtaining an amplitude correction formula, which expresses the relationship between the corrected amplitude value and the original amplitude value, as well as the local temperature of the core and the reference temperature of the core; obtaining the local temperature and the reference temperature of the core; calculating the corrected amplitude value of the fundamental wave using the amplitude correction formula, the amplitude value of the fundamental wave, the local temperature of the core, and the reference temperature; and calculating the corrected amplitude value of the high-frequency harmonic using the amplitude correction formula, the amplitude value of the high-frequency harmonic, the local temperature of the core, and the reference temperature; and calculating the core loss of the permanent magnet synchronous motor according to the core loss formula, the loss coefficient of the permanent magnet synchronous motor, the real-time temperature, the frequency and amplitude values ​​of the fundamental wave, and the frequency and amplitude values ​​of the high-frequency harmonic, including: calculating the core loss of the permanent magnet synchronous motor according to the core loss formula, the loss coefficient of the permanent magnet synchronous motor, the real-time temperature, the frequency and corrected amplitude values ​​of the fundamental wave, and the frequency and corrected amplitude values ​​of the high-frequency harmonic.

[0105] In this embodiment, a harmonic-thermal coupling feedback mechanism is set up to correct the harmonic amplitude value through temperature-driven adjustment. Specifically, the harmonic amplitude value B is established. n The correlation model between (t) and the local temperature T(x,y,z) of the iron core:

[0106]

[0107] Where γ is the temperature-permeability coupling coefficient, which is calibrated through offline experiments.

[0108] This represents the amplitude value of the corrected harmonic;

[0109] B n Indicates the original harmonic amplitude;

[0110] T represents the temperature at the current location;

[0111] T ref This indicates the reference temperature, i.e., the base temperature.

[0112] γ: Temperature-permeability coupling coefficient (unit: 1 / ℃ or 1 / K), which needs to be calibrated through offline experiments.

[0113] Physical meaning: Temperature changes alter the magnetic permeability of a material, thus affecting the magnetic field distribution and harmonic amplitude. This model corrects for the effect of temperature on B through a linear relationship. n The effect is assumed to be constant within the temperature range.

[0114] Correction mechanism:

[0115] When T>T ref When γ > 0, the amplitude value increases after correction;

[0116] When T <T ref When the amplitude value is corrected, it decreases.

[0117] Correction factor [1+γ·(TT)] ref )] is a dimensionless quantity that reflects the proportional change caused by temperature.

[0118] Then, the core loss of the permanent magnet synchronous motor is recalculated using the corrected amplitude values ​​to synchronously correct the core loss of the permanent magnet synchronous motor.

[0119] In one embodiment, after step S106, the method further includes: inputting the core loss of the permanent magnet synchronous motor into a three-dimensional thermal model and obtaining the first temperature field distribution data output by the three-dimensional thermal model; adjusting the value of the material parameter of the core of the permanent magnet synchronous motor based on the first temperature field distribution data, wherein the value of the material parameter of the core affects the loss coefficient.

[0120] Specifically, a real-time feedback mechanism for bidirectional coupling of core loss and temperature is established: the calculated core loss Pcore is input into the three-dimensional thermal model, and the first temperature field distribution data output by the three-dimensional thermal model is received simultaneously. Based on the first temperature field distribution data, the values ​​of the core material parameters are dynamically adjusted to form a closed-loop correction. For example, the resistivity of silicon steel sheets is a material parameter of the motor core. Adjusting the resistivity of silicon steel sheets can reduce eddy current losses. The resistivity of silicon steel sheets changes with temperature. Dynamically adjusting the resistivity of silicon steel sheets based on the first temperature field distribution data directly relates to the temperature dependence of the core material.

[0121] In one embodiment, after step S101, the method further includes: performing equivalent circuit modeling on the stator slots of the permanent magnet synchronous motor along the axial layered windings to obtain the impedance model of each layer of stator windings; obtaining the mechanical angle of the stator slots and calculating the offset of the electrical angle based on the mechanical angle; calculating the induced electromotive force of each layer of stator windings based on the offset; calculating the impedance of each layer of stator windings based on the impedance model of each layer of stator windings; calculating the induced electromotive force difference vector of each layer based on the induced electromotive force of each layer of stator windings; obtaining the circulating current between each layer of stator windings based on the impedance of each layer of stator windings and the induced electromotive force difference vector of each layer; calculating the circulating current loss of each layer based on the circulating current between each layer of stator windings and calculating the additional copper loss based on the circulating current loss of each layer; obtaining the fundamental copper loss generated by the fundamental wave; and obtaining the total copper loss of the permanent magnet synchronous motor based on the fundamental copper loss and the additional copper loss.

[0122] In this embodiment, a three-dimensional skewed slot effect compensation model for a permanent magnet synchronous motor is configured. This model quantifies the axial non-uniform current distribution and high-frequency circulating current loss caused by the three-dimensional skewed slot structure, resolving the copper loss calculation deviation caused by neglecting interlayer coupling effects in traditional two-dimensional models. Specifically, the model includes the following steps:

[0123] Step 1: Modeling Axial Segmented Windings

[0124] Geometric discretization: Divide the stator slots into K layers along the axial direction, such as K=5. Treat each layer of stator winding as an independent conductor and establish the interlayer mutual inductance matrix M. k,k+1 Capacitive coupling coefficient C k,k+1 .

[0125] The impedance model for each conductor layer is as follows:

[0126] Z k (f,T)=R dc (T)·F skin (f)+j2πf·L leak ;

[0127] The impedance model describes the equivalent impedance of the k-th layer stator winding, including DC resistance and leakage reactance.

[0128] R dc (T): DC resistance changes with temperature T, and resistance increases as temperature increases.

[0129] F skin (f): Skin effect factor, used to correct the increase in conductor resistance at high frequencies.

[0130] L leak Leakage inductance characterizes the leakage magnetic effect when the magnetic flux is not fully coupled to other layers.

[0131] j2πfL leakLeakage reactance is proportional to the frequency f and reflects the inductive reactance characteristics at high frequencies.

[0132] Among them, skin effect factor

[0133] δ: Skin depth parameter, related to conductor diameter d, frequency f, material permeability μ, and conductivity σ. As the frequency f increases, δ decreases, the skin effect becomes more pronounced, the effective cross-sectional area of ​​the conductor decreases, and the resistance increases.

[0134] Step 2: Slot Harmonic Coupling Analysis:

[0135] (1) Slant polar angle mapping: based on the skew groove mechanical angle θ skew Calculate the offset of the electrical angle:

[0136]

[0137] This offset causes a phase difference in the induced electromotive force of each layer of stator windings, generating a circulating current I. cir,k .

[0138] (2) Calculation of harmonic electromotive force: Induced electromotive force of the k-th layer winding at spatial harmonic order m:

[0139]

[0140] Among them Ψ m Let f be the amplitude of the m-th harmonic flux linkage.

[0141] The above formulas together construct a three-dimensional groove effect compensation model:

[0142] Axial segmentation modeling: The stator is divided into K layers along the axial direction, and the impedance and harmonic characteristics of each layer are analyzed independently.

[0143] Skin effect correction: via F skin (f) Correcting resistance changes at high frequencies.

[0144] Sloping slot phase difference analysis: using Δθ k Quantifying the interlayer phase difference helps explain the formation of circulation.

[0145] Harmonic coupling calculation: via E m,k The interaction between spatial harmonics and axial stratification is analyzed to accurately calculate high-frequency circulating losses.

[0146] Step 3: Calculation of interlayer circulation loss

[0147] (1) Impedance matrix solution: Construct the impedance matrix equation for all-axial interlayer coupling:

[0148] [Z] K×K ·[i cir ] = [Ediff ];

[0149] Specifically, by constructing a K×K impedance matrix [Z], the circulating current [Icir] between each layer is solved.

[0150] [Z]: A matrix containing the self-impedance of each layer and the interlayer coupling impedance (such as mutual inductance and capacitance).

[0151] E diff : Vector of electromotive force difference between each layer;

[0152] [E diff ]: The electromotive force difference vector of each layer, caused by the phase difference due to the slot effect.

[0153] (2) Copper loss synthesis: The total additional copper loss is the sum of the circulating losses of each layer.

[0154]

[0155] Meaning: Calculate the additional copper loss generated by the circulating current in each layer. The total additional copper loss is the sum of the losses in each layer.

[0156] Variable description:

[0157] Icir,k: The circulation in the k-th layer, in complex form.

[0158] Z k : The impedance of the k-th layer, which includes resistance and inductive reactance.

[0159] Re(·): Take the real part, representing the active power loss.

[0160] Physical meaning: When a circulating current passes through an impedance, it generates Joule losses. The formula, combined with the real part of the complex power, accurately calculates the actual losses.

[0161] (3) Combining fundamental copper loss Total copper loss is:

[0162] P cu =P cu0 +λ·P cu，add ;

[0163] Where λ is the process coefficient (0.2~0.5), which is determined experimentally.

[0164] Meaning of fundamental copper loss: Calculates the traditional copper loss generated by the fundamental current (main operating frequency f0).

[0165] I rms : The effective value of the fundamental current.

[0166] R ac (f0,T): AC resistance, including skin effect and temperature effect (T).

[0167] Meaning of total copper loss: Total copper loss is a weighted average of fundamental copper loss and additional circulating copper loss.

[0168] λ: Process coefficient (0.2~0.5), used to correct deviations between the theoretical model and actual manufacturing, such as conductor contact resistance and material inhomogeneity. λ is calibrated experimentally to make the model more closely match actual working conditions.

[0169] In one embodiment, after obtaining the total copper loss of the permanent magnet synchronous motor based on the fundamental copper loss and the additional copper loss, the method further includes: inputting the core loss and total copper loss of the permanent magnet synchronous motor into a three-dimensional thermal model and obtaining the second temperature field distribution data output by the three-dimensional thermal model; adjusting the values ​​of the material parameters of the core of the permanent magnet synchronous motor based on the second temperature field distribution data, wherein the values ​​of the material parameters of the core affect the loss coefficient.

[0170] Specifically, total copper loss and core loss are the two main types of losses in a motor. They occur in different physical regions, but are closely related through temperature field and system-level energy balance.

[0171] The total loss of the motor is the sum of the core loss and the copper loss. This total loss is converted into a second temperature field distribution data through a three-dimensional thermal model, which in turn affects the material parameters of both components.

[0172] Core parameters: The resistivity and hysteresis loss coefficient of silicon steel sheets vary with temperature;

[0173] Winding parameters: Conductor resistivity increases with increasing temperature.

[0174] This bidirectional coupling of total loss and temperature leads to: increased core loss or copper loss → increased total loss → increased temperature → changes in material parameters → further affecting core loss and copper loss, forming a closed-loop feedback.

[0175] The effect of temperature on core loss: Increased temperature leads to increased resistivity of silicon steel sheets in the core, which suppresses eddy current loss (Pe∝1 / ρ), but hysteresis loss may change due to variations in material properties.

[0176] For example, the temperature sensor corrects the hysteresis loss coefficient k in real time. h and eddy current loss coefficient k e This makes the iron loss model more accurate.

[0177] The effect of temperature on copper loss: Increased temperature directly increases the resistance of the stator winding, resulting in an increase in both fundamental copper loss and additional copper loss.

[0178] Harmonic and frequency coupling: High-frequency harmonics caused by skewed slot effects or inverter power supply increase both core losses and copper losses.

[0179] In one embodiment, after the step of obtaining the total copper loss of the permanent magnet synchronous motor based on the fundamental copper loss and the additional copper loss, the method further includes: obtaining the frequency value, reference temperature, and material resistance temperature coefficient of the stator winding of the permanent magnet synchronous motor; updating the impedance of each layer of stator winding based on the real-time temperature, the frequency value, reference temperature, and material resistance temperature coefficient of the stator winding; updating the circulating current between each layer of stator winding based on the updated impedance of each layer of stator winding and the induced electromotive force difference vector of each layer; updating the circulating current loss of each layer based on the updated circulating current between each layer of stator winding; updating the additional copper loss based on the updated circulating current loss of each layer; and obtaining the total copper loss of the permanent magnet synchronous motor based on the fundamental copper loss and the updated additional copper loss.

[0180] In this embodiment, a temperature-resistivity feedback mechanism is configured, and the resistivity of each layer of stator winding is based on the real-time temperature T. k renew:

[0181] R ac，k (f, T) = R dc (T0)·[1+α(T k -T0)]·F skin (f)

[0182] Among them, real-time temperature T k Provided by an axially distributed array of temperature sensors. Based on real-time temperature T k The AC resistance of each layer of stator winding is dynamically updated at frequency f.

[0183] Variable description:

[0184] R dc (T0): DC resistance at reference temperature T0. Reference temperature T0 is a pre-set reference temperature, typically the temperature under standard test conditions; the DC resistance R of the conductor is obtained experimentally or through calibration at reference temperature T0. dc (T0) serves as a reference value for how resistance changes with temperature.

[0185] α: Temperature coefficient of resistance of material, such as α≈0.004 / ℃ for copper.

[0186] F skin (f): Skin effect factor, which corrects the increase in resistance at high frequencies.

[0187] Function: To achieve temperature-frequency bidirectional coupling of resistivity, thereby improving the accuracy of loss calculation.

[0188] In the impedance model, the frequency dependencies of DC resistance Rdc(T) and AC resistance Rac,k(f,T) are different, while the frequency dependency of permeability μ(f) needs to be treated separately. The following is an analysis of the relationship between the three:

[0189] 1. Relationship between resistance and frequency

[0190] (1) DC resistance Rdc(T): It is related to temperature T and is the resistance of the conductor at zero frequency.

[0191] Formula: Rdc(T)=Rdc(T0)·[1+α(T-T0)];

[0192] Features: Ignores skin and proximity effects; determined solely by material resistivity and geometry. Independent of frequency f; corrected only by temperature coefficient α.

[0193] (2 Resistance Rac,k(f,T): Resistance considering both temperature T and frequency f, including skin effect and temperature effect.

[0194] formula:

[0195] Features: F skin (f) Explicit frequency dependence The temperature term is independent of frequency and is determined solely by T. k Dynamically updated.

[0196] 2. Relationship between permeability μ and frequency f

[0197] (1) The permeability μ(f) is a function of frequency, especially significant in ferromagnetic materials (such as silicon steel sheets):

[0198] (2) Low frequency band: μ is approximately constant (magnetic domains can fully respond to changes in magnetic field);

[0199] (3) High frequency band: The magnetic domain relaxation effect leads to a decrease in μ (typically manifested as μ∝1 / f).

[0200] (4) Its role in the skin effect formula: If μ varies with frequency (as in iron core materials), μ(f) needs to be explicitly introduced to calculate δ and F. skin (f).

[0201] 3. The coupling relationship among the three

[0202]

[0203] Key interaction mechanisms:

[0204] Coupling in the skin effect: Skin depth δ depends on both f and μ(f). If μ decreases with f (at high frequencies), it will partially offset the decrease in δ and suppress the skin effect.

[0205] Impact on loss calculation:

[0206] Copper loss: through F in Rac,k(f,T)skin (f) Introducing frequency dependence;

[0207] Core losses: directly dependent on frequency via ke and ka, and affected by temperature T.

[0208] Processing methods in the model

[0209] (1) Conductor (stator winding)

[0210] Assuming μ is constant: the permeability of copper / aluminum conductors is μ≈μ0 (vacuum permeability), which is independent of frequency.

[0211] Simplified formula: Rac,k(f,T)=Rdc(T)·Fskin(f) (since μ is constant)

[0212] (2) Iron core (silicon steel sheet)

[0213] μ(f): In the core loss formula, the amplitude value Bn and the loss coefficient kh,ke implicitly contain the influence of μ(f); in the skin effect calculation, μ(f) needs to be used directly to calculate δ.

[0214] In summary, Rdc(T) depends only on temperature and is used for low-frequency or DC references; Rac,k(f,T) depends on both temperature and frequency, and the skin effect is introduced through Fskin(f); μ(f) is a frequency-dependent parameter independent of resistance and is significant in ferromagnetic materials: for conductor windings: μ is constant, and Rac,k is associated with frequency only through Fskin(f); for core materials: μ(f) needs to be explicitly introduced to calculate skin depth and iron loss.

[0215] Therefore, this embodiment employs a three-dimensional impedance matrix method to accurately quantify the interlayer circulation effect caused by the skewed groove. Axial gradient temperature compensation dynamically corrects the resistance parameters of each layer to address axial temperature differences caused by uneven cooling.

[0216] In summary, the embodiments of this application provide a method for calculating the core loss of a permanent magnet synchronous motor:

[0217] 1. Precise heat source modeling algorithm: Breaking through the limitations of traditional simplified formulas, a temperature-adaptive stator copper loss model is constructed, dynamically correcting the influence of temperature on stator winding resistance, introducing harmonic correction coefficients to optimize the core loss formula, combining the improved Steinmetz equation with non-sinusoidal magnetic field analysis, and achieving precise superposition calculation of permanent magnet multi-harmonic eddy current losses through the fusion of finite element and analytical methods, solving the core problem of neglecting time-varying parameters and harmonic interference in existing loss models.

[0218] 2. High-frequency harmonic active compensation algorithm: Abandoning the hardware dependence of passive filtering, a real-time harmonic detection and proportional-integral-derivative (PID) dynamic compensation control strategy based on fast Fourier transform (FFT) is proposed. It can realize online identification of amplitude and frequency and adaptive voltage regulation for broadband harmonics, significantly improving the versatility and dynamic response capability of harmonic suppression.

[0219] 3. Parameter dynamic identification mechanism: The parameter correction algorithm, which combines offline calibration with online recursive least squares method, tracks parameter drift caused by factors such as temperature and aging during motor operation in real time by constructing state equations and observation equations. This solves the lag problem of traditional static calibration and ensures long-term high-precision matching of the electromagnetic-thermal-fluid coupling model.

[0220] This application provides a method for calculating the core loss of a permanent magnet synchronous motor, which can:

[0221] 1. Significantly improved accuracy in electromagnetic loss calculation and more accurate heat source modeling: Compared with traditional simplified formulas (ignoring the effects of temperature / harmonics), the electromagnetic loss calculation error is reduced by more than 30%, providing accurate heat source distribution data for the thermal management system, avoiding insufficient heat dissipation (causing overheating faults) or redundancy (increasing energy consumption) caused by misjudgment of loss, and directly improving the reliability and energy efficiency of motor operation.

[0222] 2. High-frequency harmonic active compensation to reduce losses and temperature rise: It replaces the traditional passive hardware filtering solution, saving hardware costs and space, while reducing the additional losses caused by harmonics by more than 25%, effectively suppressing torque pulsation and local temperature rise, improving motor operating efficiency (reducing energy waste) and operating stability, and is especially suitable for harmonic sensitive scenarios such as high-speed field weakening.

[0223] 3. Dynamic parameter identification and real-time correction enhance model robustness: This addresses the problem of traditional static calibration parameters lagging behind time-varying characteristics such as motor temperature and aging. It synchronizes the parameter update frequency of the coupled model with changes in motor operating conditions, improving the response speed of the thermal management control strategy by 40%. For example, when permanent magnets demagnetize due to high temperatures or winding resistance changes with temperature rise, the system can correct the loss calculation model in real time, avoiding misjudgments in the cooling system caused by parameter inaccuracies (such as blindly increasing heat dissipation power or insufficient heat dissipation). This significantly enhances adaptability under complex operating conditions and long-term operational reliability, extending motor lifespan.

[0224] 4. System-level optimization improves cost, energy efficiency and control precision: Reduces hardware costs and system complexity, while achieving on-demand adjustment of the cooling system (such as fan speed and coolant flow) through precise loss calculation and dynamic control, which is expected to reduce the energy consumption of the heat dissipation system by 15%-20%, and has both energy saving and noise reduction effects.

[0225] In summary, this application, through a technical closed loop of "precise modeling - active compensation - dynamic correction," achieves multiple advantages in accuracy (loss calculation error ↓30%), real-time performance (parameter response speed ↑40%), energy efficiency (harmonic loss ↓25%), and heat dissipation energy consumption ↓20%), and reliability (avoiding overheating / redundant design), providing a breakthrough solution for efficient thermal management of high power density permanent magnet synchronous motors.

[0226] It should be understood that although the steps in the flowchart are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some of the steps in the accompanying drawings may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the sub-steps or stages of other steps.

[0227] This application also provides a device for calculating the core loss of a permanent magnet synchronous motor. For example... Figure 2 As shown, a core loss calculation device for a permanent magnet synchronous motor includes a first acquisition module 201, a separation module 202, a second acquisition module 203, a third acquisition module 204, a fourth acquisition module 205, and a calculation module 206. The first acquisition module 201 is used to acquire the direct-axis current and quadrature-axis current of the stator of the permanent magnet synchronous motor and the electrical angle of the rotor; the separation module 202 is used to separate the fundamental wave and high-frequency harmonics of the permanent magnet synchronous motor from the direct-axis current and quadrature-axis current of the stator based on the electrical angle of the rotor; the second acquisition module 203 is used to acquire the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of the high-frequency harmonics; the third acquisition module 204 is used to acquire the loss coefficient and real-time temperature of the permanent magnet synchronous motor, the loss coefficient including the hysteresis loss coefficient, and the loss coefficient is dynamically updated through the state equation and observation equation constructed based on the permanent magnet synchronous motor; the fourth acquisition module 205 is used to acquire the core loss formula; the calculation module 206 is used to calculate the core loss of the permanent magnet synchronous motor based on the core loss formula, the loss coefficient of the permanent magnet synchronous motor, the real-time temperature, the frequency and amplitude values ​​of the fundamental wave, and the frequency and amplitude values ​​of the high-frequency harmonics.

[0228] In one embodiment, the fundamental wave and high-frequency harmonics of the permanent magnet synchronous motor are separated from the direct-axis current and quadrature-axis current of the stator based on the rotor's electrical angle. This includes: transforming and mapping the direct-axis current and quadrature-axis current of the stator to a synchronous rotating coordinate system based on the rotor's electrical angle; extracting the coordinate information of the fundamental wave of the permanent magnet synchronous motor in the synchronous rotating coordinate system based on the coordinate information of the direct-axis current and quadrature-axis current of the stator in the synchronous rotating coordinate system and passing it through a low-pass filter; and performing an inverse transformation on the coordinate information of the fundamental wave of the permanent magnet synchronous motor in the synchronous rotating coordinate system to obtain the fundamental wave of the permanent magnet synchronous motor.

[0229] In one embodiment, the fundamental wave and high-frequency harmonics of the permanent magnet synchronous motor are separated from the direct-axis current and quadrature-axis current of the stator based on the rotor's electrical angle. This includes: determining the window length of a sliding window based on the rotor's electrical angle; sampling the direct-axis current and quadrature-axis current of the stator using the sliding window and performing spectrum calculation on the sampled direct-axis current and quadrature-axis current based on the window length of the sliding window to obtain a time-frequency matrix; performing demixing processing based on the time-frequency matrix to obtain time-frequency information of one or more independent signal sources; and constructing each high-frequency harmonic of the permanent magnet synchronous motor based on the time-frequency information of each independent signal source.

[0230] In one embodiment, acquiring the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of the high-frequency harmonics includes: when the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of each high-frequency harmonic are found to meet the electromagnetic theory constraints of the motor, and / or when the error between the total energy of the fundamental wave and each high-frequency harmonic and the total energy of the original signal is less than a set value, acquiring the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of each high-frequency harmonic, wherein the original signal is constructed by the direct-axis current and quadrature-axis current of the stator; or, identifying abnormal harmonics based on the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of each high-frequency harmonic, and acquiring the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of the high-frequency harmonics other than the abnormal harmonics.

[0231] In one embodiment, a core loss calculation device for a permanent magnet synchronous motor further includes a first update module, used to obtain an amplitude correction formula, the amplitude correction formula representing the relationship between the corrected amplitude value and the original amplitude value, as well as the local temperature and reference temperature of the core; obtain the local temperature and reference temperature of the core; calculate the corrected amplitude value of the fundamental wave using the amplitude correction formula and the amplitude value of the fundamental wave, the local temperature and reference temperature of the core, and calculate the corrected amplitude value of the high-frequency harmonic using the amplitude correction formula and the amplitude value of the high-frequency harmonic, the local temperature and reference temperature of the core; calculate the core loss of the permanent magnet synchronous motor according to the core loss formula, the loss coefficient of the permanent magnet synchronous motor, the real-time temperature, the frequency and amplitude values ​​of the fundamental wave, and the frequency and amplitude values ​​of the high-frequency harmonic, including: calculating the core loss of the permanent magnet synchronous motor according to the core loss formula, the loss coefficient of the permanent magnet synchronous motor, the real-time temperature, the frequency and corrected amplitude values ​​of the fundamental wave, and the frequency and corrected amplitude values ​​of the high-frequency harmonic.

[0232] In one embodiment, a core loss calculation device for a permanent magnet synchronous motor further includes a construction module for constructing the state equation and observation equation of the permanent magnet synchronous motor, both of which contain parameters of the loss coefficient of the permanent magnet synchronous motor; and dynamically updating the loss coefficient of the permanent magnet synchronous motor based on the state equation and observation equation using the recursive least squares method.

[0233] In one embodiment, a core loss calculation device for a permanent magnet synchronous motor further includes a first adjustment module, used to input the core loss of the permanent magnet synchronous motor into a three-dimensional thermal model and obtain the first temperature field distribution data output by the three-dimensional thermal model; and adjust the value of the material parameter of the core of the permanent magnet synchronous motor based on the first temperature field distribution data, wherein the value of the material parameter of the core affects the loss coefficient.

[0234] In one embodiment, a core loss calculation device for a permanent magnet synchronous motor further includes a fifth acquisition module, used to perform equivalent circuit modeling on the axial layered windings of the stator slots of the permanent magnet synchronous motor to obtain the impedance model of each layer of stator windings; acquire the mechanical angle of the stator slots and calculate the offset of the electrical angle based on the mechanical angle; calculate the induced electromotive force of each layer of stator windings based on the offset; calculate the impedance of each layer of stator windings based on the impedance model of each layer of stator windings; calculate the induced electromotive force difference vector of each layer based on the induced electromotive force of each layer of stator windings; acquire the circulating current between each layer of stator windings based on the impedance of each layer of stator windings and the induced electromotive force difference vector of each layer; calculate the circulating current loss of each layer based on the circulating current between each layer of stator windings; calculate the additional copper loss based on the circulating current loss of each layer; acquire the fundamental copper loss generated by the fundamental wave; and obtain the total copper loss of the permanent magnet synchronous motor based on the fundamental copper loss and the additional copper loss.

[0235] In one embodiment, a core loss calculation device for a permanent magnet synchronous motor further includes a second adjustment module for inputting the core loss and total copper loss of the permanent magnet synchronous motor into a three-dimensional thermal model and obtaining the second temperature field distribution data output by the three-dimensional thermal model.

[0236] The material parameters of the permanent magnet synchronous motor core are adjusted based on the second temperature field distribution data, and the material parameters of the core affect the loss coefficient.

[0237] In one embodiment, a core loss calculation device for a permanent magnet synchronous motor further includes a second update module, used to obtain the frequency value, reference temperature, and material resistance temperature coefficient of the stator winding of the permanent magnet synchronous motor; update the impedance of each layer of stator winding based on the real-time temperature, the frequency value, reference temperature, and material resistance temperature coefficient of the stator winding; update the circulating current between each layer of stator winding based on the updated impedance of each layer of stator winding and the induced electromotive force difference vector of each layer; update the circulating current loss of each layer based on the updated circulating current between each layer of stator winding; update the additional copper loss based on the updated circulating current loss of each layer; and obtain the total copper loss of the permanent magnet synchronous motor based on the fundamental copper loss and the updated additional copper loss.

[0238] Specific limitations regarding the core loss calculation device for a permanent magnet synchronous motor can be found in the above-described limitations regarding the core loss calculation method for a permanent magnet synchronous motor, and will not be repeated here. Each module in the aforementioned core loss calculation device for a permanent magnet synchronous motor can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0239] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 3As shown, the computer device includes a processor, memory, network interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The network interface is used to communicate with external terminals via a network connection. When executed by the processor, the computer program implements a method for calculating the core loss of a permanent magnet synchronous motor. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0240] Those skilled in the art will understand that Figure 3 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device on which the present application is intended to be applied. A specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0241] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of a method for calculating the core loss of a permanent magnet synchronous motor according to any of the above embodiments.

[0242] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of a method for calculating the core loss of a permanent magnet synchronous motor according to any of the above embodiments.

[0243] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0244] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0245] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for calculating the core loss of a permanent magnet synchronous motor, characterized in that, The method includes: Obtain the direct-axis current and quadrature-axis current of the stator and the electrical angle of the rotor of the permanent magnet synchronous motor; Based on the rotor's electrical angle, the fundamental wave and high-frequency harmonics of the permanent magnet synchronous motor are separated from the direct-axis current and quadrature-axis current of the stator. Obtain the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of the high-frequency harmonics; The loss coefficient and real-time temperature of the permanent magnet synchronous motor are obtained. The loss coefficient includes the hysteresis loss coefficient and is dynamically updated by the state equation and observation equation constructed based on the permanent magnet synchronous motor. Obtain the formula for core loss; The core loss of the permanent magnet synchronous motor is calculated based on the core loss formula, the loss coefficient of the permanent magnet synchronous motor, the real-time temperature, the frequency and amplitude of the fundamental wave, and the frequency and amplitude of the high-frequency harmonics.

2. The method according to claim 1, characterized in that, The separation of the fundamental wave and high-frequency harmonics of the permanent magnet synchronous motor from the direct-axis current and quadrature-axis current of the stator based on the electrical angle of the rotor includes: The direct-axis current and quadrature-axis current of the stator are transformed and mapped to the synchronous rotating coordinate system based on the electrical angle of the rotor. Based on the coordinate information of the direct-axis current and quadrature-axis current of the stator in the synchronous rotating coordinate system, and through a low-pass filter, the coordinate information of the fundamental wave of the permanent magnet synchronous motor in the synchronous rotating coordinate system is extracted. The coordinate information of the fundamental wave of the permanent magnet synchronous motor in the synchronous rotating coordinate system is inversely transformed to obtain the fundamental wave of the permanent magnet synchronous motor.

3. The method according to claim 2, characterized in that, The separation of the fundamental wave and high-frequency harmonics of the permanent magnet synchronous motor from the direct-axis current and quadrature-axis current of the stator based on the electrical angle of the rotor includes: The window length of the sliding window is determined based on the electrical angle of the rotor; The direct-axis current and quadrature-axis current of the stator are sampled using the sliding window, and the frequency spectrum of the sampled direct-axis current and quadrature-axis current is calculated according to the window length of the sliding window to obtain the time-frequency spectrum matrix; The time-frequency information of one or more independent signal sources is obtained by demixing the time-frequency matrix. The high-frequency harmonics of the permanent magnet synchronous motor are constructed based on the time-frequency information of each independent signal source.

4. The method according to claim 3, characterized in that, The acquisition of the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of the high-frequency harmonics includes: When the frequency and amplitude values ​​of the fundamental wave and each high-frequency harmonic are found to meet the electromagnetic theory constraints of the motor, and / or when the error between the total energy of the fundamental wave and each high-frequency harmonic and the total energy of the original signal is less than a set value, the frequency and amplitude values ​​of the fundamental wave and each high-frequency harmonic are acquired, wherein the original signal is constructed by the direct-axis current and quadrature-axis current of the stator; or, Abnormal harmonics are identified based on the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of each high-frequency harmonic, and the frequency and amplitude values ​​of the fundamental wave and the high-frequency harmonics other than the abnormal harmonics are obtained.

5. The method according to claim 1, characterized in that, The method further includes: Obtain the amplitude value correction formula, which expresses the relationship between the corrected amplitude value, the original amplitude value, the local temperature of the iron core, and the reference temperature of the iron core; Obtain the local temperature and reference temperature of the iron core; The corrected amplitude value of the fundamental wave is calculated using the amplitude correction formula, the amplitude value of the fundamental wave, the local temperature of the iron core, and the reference temperature. Similarly, the corrected amplitude value of the high-frequency harmonic is calculated using the amplitude correction formula, the amplitude value of the high-frequency harmonic, the local temperature of the iron core, and the reference temperature. The step of calculating the core loss of the permanent magnet synchronous motor based on the core loss formula, the loss coefficient of the permanent magnet synchronous motor, the real-time temperature, the frequency and amplitude of the fundamental wave, and the frequency and amplitude of the high-frequency harmonics includes: calculating the core loss of the permanent magnet synchronous motor based on the core loss formula, the loss coefficient of the permanent magnet synchronous motor, the real-time temperature, the frequency and amplitude of the fundamental wave, and the frequency and amplitude of the high-frequency harmonics.

6. The method according to claim 1, characterized in that, The method further includes: The state equation and observation equation of the permanent magnet synchronous motor are constructed, and both the state equation and the observation equation include the parameters of the loss coefficient of the permanent magnet synchronous motor. The loss coefficient of the permanent magnet synchronous motor is dynamically updated based on the state equation and the observation equation using the recursive least squares method.

7. The method according to claim 1, characterized in that, The method further includes: The core loss of the permanent magnet synchronous motor is input into the three-dimensional thermal model, and the first temperature field distribution data output by the three-dimensional thermal model is obtained. The material parameters of the core of the permanent magnet synchronous motor are adjusted based on the first temperature field distribution data, and the material parameters of the core affect the loss coefficient.

8. The method according to claim 1, characterized in that, The method further includes: Equivalent circuit modeling is performed on the stator slot layered windings along the axial direction of the permanent magnet synchronous motor to obtain the impedance model of each layer of stator windings; Obtain the mechanical angle of the stator slot, and calculate the offset of the electrical angle based on the mechanical angle; Calculate the induced electromotive force of each layer of stator windings based on the offset; The impedance of each layer of stator windings is calculated based on the impedance model of each layer of stator windings; Calculate the induced electromotive force difference vector of each layer based on the induced electromotive force of each layer of stator winding; The circulating current between the stator windings of each layer is obtained based on the impedance of each layer of stator windings and the induced electromotive force difference vector of each layer. Calculate the circulating current loss of each layer based on the circulating current between each layer of stator windings, and calculate the additional copper loss based on the circulating current loss of each layer. Obtain the fundamental copper loss generated by the fundamental wave, and obtain the total copper loss of the permanent magnet synchronous motor based on the fundamental copper loss and the additional copper loss.

9. The method according to claim 8, characterized in that, The method further includes: The core loss and total copper loss of the permanent magnet synchronous motor are input into the three-dimensional thermal model, and the second temperature field distribution data output by the three-dimensional thermal model are obtained. The material parameters of the core of the permanent magnet synchronous motor are adjusted based on the second temperature field distribution data, and the material parameters of the core affect the loss coefficient.

10. The method according to claim 8, characterized in that, The method further includes: Obtain the frequency value, reference temperature, and material resistivity temperature coefficient of the stator winding of the permanent magnet synchronous motor; The impedance of each layer of stator winding is updated based on the real-time temperature, the frequency value of the stator winding, the reference temperature, and the material resistance temperature coefficient of the stator winding. The circulating current between the stator windings of each layer is updated based on the updated impedance of each layer of stator windings and the induced electromotive force difference vector of each layer. Update the circulating current loss of each layer based on the updated circulating current between each layer of stator windings, and update the additional copper loss based on the updated circulating current loss of each layer. The total copper loss of the permanent magnet synchronous motor is obtained based on the fundamental copper loss and the updated additional copper loss.

11. A device for calculating the core loss of a permanent magnet synchronous motor, characterized in that, The device includes: The first acquisition module is used to acquire the direct-axis current and quadrature-axis current of the stator of the permanent magnet synchronous motor and the electrical angle of the rotor. A separation module is used to separate the fundamental wave and high-frequency harmonics of the permanent magnet synchronous motor from the direct-axis current and quadrature-axis current of the stator based on the electrical angle of the rotor. The second acquisition module is used to acquire the frequency and amplitude values ​​of the fundamental wave and the frequency and amplitude values ​​of the high-frequency harmonics; The third acquisition module is used to acquire the loss coefficient and real-time temperature of the permanent magnet synchronous motor. The loss coefficient includes the hysteresis loss coefficient, which is dynamically updated through the state equation and observation equation constructed based on the permanent magnet synchronous motor. The fourth acquisition module is used to obtain the core loss formula; The calculation module is used to calculate the core loss of the permanent magnet synchronous motor based on the core loss formula, the loss coefficient of the permanent magnet synchronous motor, the real-time temperature, the frequency and amplitude of the fundamental wave, and the frequency and amplitude of the high-frequency harmonics.

12. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 10.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 10.

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