A method and system for estimating the temperature of a permanent magnet synchronous motor based on offline data

Abstract

This invention discloses a method and system for estimating the temperature of a permanent magnet synchronous motor (PMSM) based on offline data. The method includes: constructing a temperature-considered voltage model of the PMSM; acquiring multiple sets of offline data and obtaining the sum and difference of the products of the dq-axis voltage and current under the offline data through calculation and relationship fitting; and combining the difference between the sum and difference of the products of the dq-axis voltage and current under the offline and online data with the temperature-considered PMSM voltage model to calculate the estimated winding temperature and flux linkage temperature. The system includes: a model construction module, an offline data acquisition module, an offline data calculation module, a relationship fitting module, an online data acquisition module, and a temperature estimation module. Using this invention simplifies implementation and storage, ensures that the temperature remains constant during data acquisition, and improves the accuracy of temperature estimation. This invention, as a temperature estimation method and system for PMSMs based on offline data, can be widely applied in the field of PMSM technology.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous motors, and more particularly to a method and system for estimating the temperature of a permanent magnet synchronous motor based on offline data. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in practical applications due to their high power density and other advantages. To achieve high-performance and efficient motor control and ensure safe operation, motor temperature information is crucial. However, directly measuring the internal temperature of the motor is challenging, not only due to cost issues but also because it's difficult to obtain the overall temperature distribution from a global perspective. Temperature estimation methods can effectively avoid these problems, but traditional temperature estimation models are related to motor speed, current, and current angle, making modeling them very difficult. Furthermore, traditional temperature estimation models are generally based on online data acquisition, but the motor temperature changes during online data acquisition, making it impossible to guarantee that multiple sets of online data are at the same temperature, resulting in poor accuracy in motor temperature estimation. Summary of the Invention

[0003] To address the aforementioned technical problems, the objective of this invention is to provide a method and system for estimating the temperature of a permanent magnet synchronous motor based on offline data. This method simplifies implementation and storage, ensures that the temperature remains constant during offline data acquisition, and improves the accuracy of temperature estimation.

[0004] The first technical solution adopted in this invention is: a method for estimating the temperature of a permanent magnet synchronous motor based on offline data, comprising the following steps:

[0005] Construct a voltage model for a permanent magnet synchronous motor that takes temperature into account;

[0006] Multiple sets of offline data were collected under preset conditions to obtain multiple sets of current and voltage measurement values;

[0007] The sum and difference of the products of d-axis voltage and q-axis current are defined as the sum of the product of d-axis voltage and current and the product of q-axis voltage and current, and the difference between the product of q-axis voltage and d-axis current and the product of q-axis current and d-axis voltage.

[0008] The sum and difference of the products of the dq-axis voltage and current of each set of data are calculated based on multiple sets of current and voltage measurements to obtain offline data measurement information.

[0009] Based on offline data measurement information, the relationship between the sum and difference of the product of dq-axis voltage and current and the current angle, current amplitude and rotational speed is fitted. The current angle, current amplitude and rotational speed are then constrained to obtain the sum and difference of the product of dq-axis voltage and current under the constrained conditions of offline data.

[0010] Collect online data under limited conditions and calculate the sum and difference of the product of dq-axis voltage and current at this time to obtain the sum and difference of the product of dq-axis voltage and current under limited conditions under online data.

[0011] Based on the sum and difference of the products of dq-axis voltage and current under constraints of online and offline data, the voltage model of the permanent magnet synchronous motor considering temperature is transformed and calculated to obtain the flux linkage temperature and winding temperature.

[0012] Furthermore, in the step of constructing a temperature-considered voltage model for a permanent magnet synchronous motor, the expression for the temperature-considered voltage model is as follows:

[0013]

[0014] U d U q I d and I q L represents the dq-axis stator voltage and current. q and L d λ represents the inductance along the dq axis; λ represents the permanent magnet flux linkage; R represents the winding resistance; ω represents the electric angular velocity; D D and D Q The coefficients represent the inverter's coefficients, α and β represent the thermal coefficients of copper and magnets, respectively, and T M and T w These represent the flux linkage temperature and the winding temperature, respectively. R0 represents the winding resistance at temperature T0, and λ0 represents the permanent magnet flux linkage at temperature T0.

[0015] Through this optimization step, the constructed voltage model of the permanent magnet synchronous motor that takes temperature into account can reflect temperature changes through winding resistance and electromagnetic flux.

[0016] Furthermore, the step of acquiring multiple sets of offline data under preset conditions to obtain multiple sets of current and voltage measurement values ​​specifically includes:

[0017] Set multiple speeds, multiple current amplitudes, and multiple current angles to obtain the measurement data of dq axis voltage and current in each state;

[0018] The average value of the dq-axis voltage and current measurements under each state is calculated to obtain multiple sets of current and voltage measurements.

[0019] Through this optimized process, multiple sets of current and voltage measurements are obtained that sufficiently fit the relationship between the sum and difference of the product of the dq-axis voltage and current and the current angle, current amplitude, and rotational speed.

[0020] Furthermore, the step of fitting the relationship between the sum and difference of the product of the dq-axis voltage and current and the current angle, current amplitude, and rotational speed based on offline data measurement information, and limiting the current angle, current amplitude, and rotational speed to obtain the sum and difference of the product of the dq-axis voltage and current under the limited conditions of offline data, specifically includes:

[0021] For a given current amplitude and rotational speed, the least squares method is used to fit the offline data measurement information of different current angles to obtain the relationship between the sum and difference of the product of the dq axis voltage and current and the current angle.

[0022] Based on the relationship between the sum and difference of the product of the dq-axis voltage and current and the current angle, the current angle is limited to obtain the sum and difference of the product of the dq-axis voltage and current under a given current angle.

[0023] By using the least squares method to fit the sum and difference of the products of the dq-axis voltage and current at different rotational speeds under a given current angle, the relationship between the sum and difference of the products of the dq-axis voltage and current and the rotational speed under a given current angle is obtained.

[0024] Based on the relationship between the sum and difference of the product of the dq-axis voltage and current under a given current angle and the rotational speed, the rotational speed is limited to obtain the sum and difference of the product of the dq-axis voltage and current under a given current angle and a given rotational speed.

[0025] By using the least squares method to fit the sum and difference of the products of the dq-axis voltage and current for different current amplitudes under the given current angle and rotational speed, the relationship between the sum and difference of the products of the dq-axis voltage and current and the current amplitude is obtained.

[0026] Based on the relationship between the sum and difference of the product of the dq-axis voltage and current and the current amplitude under the given current angle and rotational speed, the current amplitude is limited to obtain the sum and difference of the product of the dq-axis voltage and current under the limited conditions of offline data.

[0027] By performing relationship fitting on the scattered offline data through this optimization step, the current amplitude, current angle and rotation speed can be gradually defined, and the sum and difference of the product of the dq axis voltage and current under the offline data can be obtained intuitively.

[0028] Furthermore, the step of using the least squares method to fit the sum and difference of the products of the dq-axis voltage and current at different rotational speeds under the current angle, and obtaining the relationship between the sum and difference of the products of the dq-axis voltage and current under the current angle and the rotational speed, specifically includes:

[0029] Construct a relational model using piecewise functions based on polynomials;

[0030] Substitute the sum and difference of the products of the dq-axis voltage and current at different rotational speeds under a given current angle into the relational model, and use the least squares method to find the polynomial coefficients of the piecewise function.

[0031] Based on the polynomial coefficients of the piecewise function, the relationship between the sum and difference of the product of the voltage and current on the dq axis and the rotational speed is obtained under a given current angle.

[0032] This optimization step can improve the model fitting accuracy. Using piecewise functions to fit the rotational speed model under different iron losses can reduce the impact of iron losses on the model accuracy. Similarly, using piecewise functions to fit the current amplitude model under different magnetic saturation can reduce the impact of magnetic saturation on the model accuracy.

[0033] Furthermore, the step of transforming the voltage model of the permanent magnet synchronous motor considering temperature by using the sum and difference of the products of the dq-axis voltage and current under the constraints of online and offline data to obtain the flux linkage temperature and winding temperature specifically includes:

[0034] By combining the voltage model of the permanent magnet synchronous motor considering temperature and replacing the parameters of the sum and difference of the product of the dq-axis voltage and current, the relationship equation of the sum and difference of the product of the dq-axis voltage and current considering temperature is obtained.

[0035] Substituting the sum and difference of the products of dq-axis voltage and current under the constraints of online and offline data into the relationship equation of the sum and difference of the products of dq-axis voltage and current considering temperature, the difference is calculated to obtain the relationship equation between the difference of the sum and difference of the products of dq-axis voltage and current under the constraints of online and offline data and resistance and flux linkage.

[0036] By combining the sum and difference of the products of dq-axis voltage and current under the constraints of online and offline data with the relationship equations of resistance and flux linkage, and considering the voltage model of permanent magnet synchronous motor considering temperature, the winding temperature and flux linkage temperature are obtained.

[0037] Through this optimized step, the difference between the sum and difference of the products of dq-axis voltage and current under the constraints of online and offline data is successfully converted into the difference of winding resistance and permanent magnet flux linkage using a permanent magnet synchronous motor voltage model that takes temperature into account. Finally, the winding temperature and flux linkage temperature are estimated.

[0038] The second technical solution adopted in this invention is: a temperature estimation system for permanent magnet synchronous motors based on offline data, comprising:

[0039] The model building module is used to build a voltage model of a permanent magnet synchronous motor that takes temperature into account.

[0040] The offline data acquisition module is used to collect multiple sets of offline data under preset conditions to obtain multiple sets of current and voltage measurement values.

[0041] The offline data calculation module is used to calculate the sum and difference of the dq axis voltage and current products of each set of current and voltage measurements based on multiple sets of current and voltage measurements, and to obtain offline data measurement information.

[0042] The relationship fitting module, based on offline data measurement information, fits the relationship between the sum and difference of the product of dq-axis voltage and current and the current angle, current amplitude and rotational speed, and limits the current angle, current amplitude and rotational speed to obtain the sum and difference of the product of dq-axis voltage and current under the limited conditions of offline data.

[0043] The online data acquisition module is used to collect online data under certain conditions and calculate the sum and difference of the product of the dq axis voltage and current at this time, so as to obtain the sum and difference of the product of the dq axis voltage and current under the certain conditions of the online data.

[0044] The temperature estimation module transforms the voltage model of the permanent magnet synchronous motor considering temperature by calculating the sum and difference of the products of the dq-axis voltage and current under the constraints of online and offline data, and obtains the flux linkage temperature and winding temperature.

[0045] The beneficial effects of the method and system of this invention are as follows: This invention achieves accurate estimation of flux linkage temperature and winding temperature by constructing a voltage model of a permanent magnet synchronous motor that takes temperature into account and combining the sum and difference of the products of dq-axis voltage and current; by using a piecewise function fitting model, the influence of magnetic saturation and iron loss is avoided, thus improving the accuracy of the model; by using offline data acquisition, temperature changes are avoided, effectively improving the accuracy of temperature detection, and thus improving the accuracy of temperature estimation. Attached Figure Description

[0046] Figure 1 This is a flowchart of the steps of a permanent magnet synchronous motor temperature estimation method based on offline data according to the present invention;

[0047] Figure 2 This is a structural block diagram of a permanent magnet synchronous motor temperature estimation system based on offline data according to the present invention;

[0048] Figure 3 This is a schematic diagram illustrating a specific implementation of the temperature estimation method for permanent magnet synchronous motors based on offline data according to the present invention. Detailed Implementation

[0049] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

[0050] Reference Figure 1 and Figure 3 This invention provides a method for estimating the temperature of a permanent magnet synchronous motor based on offline data. The method includes the following steps:

[0051] S1. Construct a voltage model for a permanent magnet synchronous motor that takes temperature into account;

[0052] The expression for the voltage model of a permanent magnet synchronous motor considering temperature is as follows:

[0053]

[0054] U d U q I d and I q L represents the dq-axis stator voltage and current. q and L d λ represents the inductance along the dq axis; λ represents the permanent magnet flux linkage; R represents the winding resistance; ω represents the electric angular velocity; D D and D Q The coefficients represent the inverter's coefficients, α and β represent the thermal coefficients of copper and magnets, respectively, and T W and T M These represent the flux linkage temperature and the winding temperature, respectively. R0 represents the winding resistance at temperature T0, and λ0 represents the permanent magnet flux linkage at temperature T0.

[0055] S2. Collect multiple sets of offline data under preset conditions to obtain multiple sets of current and voltage measurement values;

[0056] Set the speed of group Q, the current amplitude of group P, and the current angle of group K, and obtain the measurement of the dq axis voltage and current for each group;

[0057] The average value of the dq-axis voltage and current measurements for each group is calculated to obtain the current and voltage measurement values ​​for group Q*P*K.

[0058] Specifically, the rotational speed is divided into Q ranges. For example, when Q = 3, each range corresponds to low speed, medium speed, and high speed. Similarly, the current amplitude can also be divided into P ranges. Therefore, in ω-I s The plane is divided into Q*P regions, and K current angles can be set in each region. Therefore, the measurement data of each small region is Q*P*K.

[0059] S3. Define the sum and difference of the products of d-axis voltage and current as including the sum of the product of d-axis voltage and current and the product of q-axis voltage and current, and the difference between the product of q-axis voltage and d-axis current and the product of q-axis current and d-axis voltage. Calculate the sum and difference of the products of d-axis voltage and current for each set of data based on multiple sets of current and voltage measurements to obtain offline data measurement information. The sum of the products of d-axis voltage and current is denoted as M, and the difference of the products of d-axis voltage and current is denoted as N. Specifically, the formulas for M and N are as follows:

[0060]

[0061] Where M represents the sum of the products of the dq-axis voltage and current, N represents the difference of the products of the dq-axis voltage and current, and U d U q I d and I q These represent the stator voltage and current along the dq axis, respectively.

[0062] S4. Based on offline data measurement information, fit the relationship between the sum and difference of the product of dq axis voltage and current and the current angle, current amplitude and rotation speed, and limit the current angle, current amplitude and rotation speed to obtain the sum and difference of the product of dq axis voltage and current under the limit conditions of offline data.

[0063] S4.1 For a given current amplitude and rotational speed, the offline data measurement information of different current angles is fitted by the least squares method to obtain the relationship between the sum and difference of the product of the dq axis voltage and current and the current angle.

[0064] Specifically, a model relating the sum and difference of the products of the dq-axis voltage and current to the current angle is constructed using a first-order or second-order polynomial. Using third-order, fourth-order, or higher-order polynomials can improve the model fitting accuracy. The expression of the relational model constructed using first-order and second-order polynomials in a specific embodiment of this invention is shown below:

[0065]

[0066] Where a2, a1, a0, b1, and b0 represent the parameters of the model relating the sum and difference of the product of the dq-axis voltage and current to the current angle.

[0067] For the sum and difference of the product of the voltage and current along the dq axis of the k-th group (k=1…K), the following condition can be satisfied:

[0068]

[0069] Therefore, the coefficients of each polynomial can be obtained using the least squares method, and the expressions for the coefficients of each polynomial are as follows:

[0070]

[0071] in

[0072] S4.2. Based on the relationship between the sum and difference of the product of the dq-axis voltage and current and the current angle, the current angle is constrained to obtain the sum and difference of the product of the dq-axis voltage and current under a given current angle. The current angle is then denoted as γ. t Let M be the sum and difference of the product of the voltage and current along the dq axis at the current angle. pq and N pq ;

[0073] Specifically, the parameters a2, a1, a0, b1, and b0 of the model relating the sum and difference of the products of the identified dq-axis voltages and currents to the current angle are used to calculate the Q*P group M according to formula (6). pq and N pq .

[0074]

[0075] S4.3. Using the least squares method to fit the sum and difference of the products of the dq-axis voltage and current at different rotational speeds under the current angle, the relationship between the sum and difference of the products of the dq-axis voltage and current under the current angle and the rotational speed is obtained.

[0076] Specifically, a first-order polynomial is used to construct a model relating the sum and difference of the product of the dq-axis voltage and current to the rotational speed under a given current angle. Using second-, third-, fourth-, or higher-order polynomials can improve the model fitting accuracy. Considering that the influence of iron loss increases with the rotor speed and affects the accuracy of the model relating the sum and difference of the dq-axis voltage and current to the rotational speed under a given current angle, piecewise functions are used to fit the rotational speed model under different iron losses. If a two-piece piecewise function is used, the fitting is performed under the assumption that the iron loss in case 1 or case 2 remains constant. Using more piecewise functions will result in higher fitting accuracy. The expression of the relational model constructed using a first-order polynomial and a two-piece piecewise function in a specific example of this invention is shown below:

[0077]

[0078] Where e ij and f ij (i,j=0,1) represents the parameters of the model relating the sum and difference of the product of the voltage and current on the dq axis to the rotational speed under a given current angle.

[0079] Taking case 1 as an example, for the qth group (q=1…Q) with a determined current angle, the sum and difference of the product of the voltage and current on the dq axis can satisfy the following conditions:

[0080]

[0081] Therefore, the coefficients of each polynomial can be obtained using the least squares method, and the expressions for the coefficients of each polynomial are as follows:

[0082]

[0083] in

[0084] The method for identifying the coefficients of each polynomial in case 2 is consistent with that in case 1.

[0085] S4.4. Based on the relationship between the sum and difference of the products of the dq-axis voltage and current under a given current angle and the rotational speed, the rotational speed is constrained to obtain the sum and difference of the products of the dq-axis voltage and current under a given current angle and a given rotational speed. The determined current angle is denoted as γ. t The rotational speed is determined and denoted as ω. t The sum and difference of the products of the current angle and the dq-axis voltage and current at a given rotational speed are denoted as M. p and N p .

[0086] Specifically, taking case 1 as an example, the parameters e of the model relating the sum and difference of the product of the dq-axis voltage and current under the identified current angle to the rotational speed are used. 10 e 00 f 10 and f 00 Calculate P group M according to formula (10) p and N p .

[0087]

[0088] The method for calculating the sum and difference of the product of the current angle and the dq-axis voltage and current under the given rotational speed in case 2 is consistent with that in case 1.

[0089] S4.5. Using the least squares method, fit the sum and difference of the products of the dq-axis voltage and current for different current amplitudes under the conditions of a determined current angle and a determined rotational speed, and obtain the relationship between the sum and difference of the products of the dq-axis voltage and current and the current amplitude under the conditions of a determined current angle and a determined rotational speed.

[0090] Specifically, a model relating the sum and difference of the products of the dq-axis voltage and current to the current amplitude is constructed using a first-order or second-order polynomial, given a fixed current angle and rotational speed. Using third-, fourth-, or higher-order polynomials improves the model's fitting accuracy. Considering that the saturation level increases with the stator current, and that magnetic saturation affects the accuracy of the model relating the sum and difference of the products of the dq-axis voltage and current to the current amplitude, piecewise functions are used to fit the current amplitude models under different magnetic saturation levels. If a two-piece function is used, fitting is performed under the assumption that the magnetic saturation level in case 3 or case 4 remains constant. Using more piecewise functions results in higher fitting accuracy. The expression for the relational model constructed using a second-order polynomial and a two-piece function in a specific example of this invention is shown below:

[0091]

[0092] Where c ij (i,j=0,1) and d ij (i = 0, 1, 2, j = 0, 1) represents the parameters of the model relating the sum and difference of the product of the voltage and current on the dq axis to the current amplitude under the conditions of a given current angle and a given rotational speed.

[0093] Taking case 3 as an example, for the p-th group (p=1…P), the sum and difference of the product of the current angle and the dq-axis voltage and current under the condition of a determined current amplitude and a determined rotational speed can satisfy the following conditions:

[0094]

[0095] Therefore, the coefficients of each polynomial can be obtained using the least squares method, and the expressions for the coefficients of each polynomial are as follows:

[0096]

[0097] in

[0098] The method for identifying the coefficients of each polynomial in case 4 is consistent with that in case 3.

[0099] S4.6. Based on the relationship between the sum and difference of the products of the dq-axis voltage and current and the current amplitude under the given current angle and rotational speed, the current amplitude is limited to obtain the sum and difference of the products of the dq-axis voltage and current under the limited conditions in offline data. The limited conditions are the given current angle, rotational speed, and current amplitude. The current angle is denoted as γ. t The rotational speed is determined and denoted as ω. t The current amplitude is determined and denoted as I. tThe sum and difference of the products of the dq-axis voltage and current, which determine the current angle, current amplitude, and rotational speed under offline data, are denoted as M0 and N0, respectively.

[0100] Specifically, taking case 3 as an example, the model of the relationship between the sum and difference of the product of the dq-axis voltage and current and the current amplitude under the identified conditions of a fixed current angle and a fixed rotational speed is used. 10 c 00 d 20 d 10 and d 00 Calculate M0 and N0 according to formula (14).

[0101]

[0102] The method for calculating the sum and difference of the products of the dq-axis voltage and current to determine the current angle, current amplitude, and rotational speed in Case 4 is consistent with that in Case 3.

[0103] S5. Collect online data under the given conditions and calculate the sum and difference of the product of the dq-axis voltage and current at this time to obtain the sum and difference of the product of the dq-axis voltage and current under the given conditions in the online data.

[0104] Specifically, the current angle is determined and denoted as γ. t The rotational speed is determined and denoted as ω. t The current amplitude is determined and denoted as I. t The sum and difference of the products of the dq-axis voltage and current, which determine the current angle, current amplitude, and rotational speed under online data, are denoted as M. t and N t M t and N t It can be obtained through formula (15):

[0105]

[0106] Where M t and N t I represents the sum and difference of the products of the dq-axis voltage and current, used to determine the current angle, current amplitude, and rotational speed from online data. t Indicates the determination of current amplitude, γ t U represents the current angle. td U tq I td and I tq This represents the dq-axis voltage and current used to determine the current angle, current amplitude, and rotational speed under online data.

[0107] S6. Based on the sum and difference of the products of dq-axis voltage and current under the constraints of online and offline data, the voltage model of the permanent magnet synchronous motor considering temperature is transformed and calculated to obtain the flux linkage temperature and winding temperature.

[0108] S6.1 Specifically, by substituting the dq-axis stator voltage and current in the temperature-considered permanent magnet synchronous motor voltage model into the equation for the sum and difference of the dq-axis voltage and current products, parameter substitution is performed to obtain the equation for the sum and difference of the dq-axis voltage and current products considering temperature. The expression for the equation for the sum and difference of the dq-axis voltage and current products considering temperature is as follows:

[0109]

[0110] U d U q I d and I q L represents the dq-axis stator voltage and current. q and L d λ represents the inductance along the dq axis; λ represents the permanent magnet flux linkage; R represents the winding resistance; ω represents the electric angular velocity; D D and D Q The coefficients represent the inverter's coefficients, α and β represent the thermal coefficients of copper and magnets, respectively, and T M and T W Let T represent the flux linkage temperature and winding temperature, respectively; R0 represent the winding resistance at temperature T0; λ0 represent the permanent magnet flux linkage at temperature T0; M represent the sum of the products of the dq-axis voltage and current; N represent the difference between the products of the dq-axis voltage and current; and L represent the flux linkage temperature and winding temperature, respectively. Δ L represents q and L d The difference.

[0111] S6.2, due to the inverter coefficient D D and D Q It only depends on the current angle, therefore (D D I d +D Q I q V dt and (D) Q I d -D D I q V dt The factors related to the current angle and current amplitude are eliminated during the difference calculation. Substituting the sum and difference of the products of the dq-axis voltage and current under the constraints of online and offline data into the equation relating the sum and difference of the products of the dq-axis voltage and current considering temperature, we obtain the equation relating the difference of the sum and difference of the products of the dq-axis voltage and current under the constraints of online and offline data to resistance and flux linkage. The expression of this equation is as follows:

[0112]

[0113] Where M t and Nt M0 and N0 represent the sum and difference of the products of dq-axis voltages and currents under constraints in online data, while M0 and N0 represent the sum and difference of the products of dq-axis voltages and currents under constraints in offline data. γ t I represents a defined current angle. t This indicates the determination of the current amplitude, ω. t The given values ​​represent the determined rotational speed, R represents the winding resistance value under online data, λ represents the permanent magnet flux linkage value under online data, R0 represents the winding resistance value under offline data, λ0 represents the permanent magnet flux linkage value under offline data, ΔR represents the difference between the winding resistance under online data and offline data, and Δλ represents the difference between the permanent magnet flux linkage under online data and offline data.

[0114] S6.3. Combining the relationship equations between the sum and difference of the products of dq-axis voltage and current under the constraints of online and offline data, and the voltage model of the permanent magnet synchronous motor considering temperature, the winding temperature and flux linkage temperature are obtained. The derived expressions for winding temperature and flux linkage temperature are as follows:

[0115]

[0116] Where T M and T W ΔT represents the flux linkage temperature and winding temperature, respectively. M and ΔT W The values ​​represent the difference in flux linkage temperature and winding temperature between the online and offline states. T0 represents the flux linkage temperature and winding temperature in the offline state. ΔR represents the difference in winding resistance between the online and offline data. Δλ represents the difference in permanent magnet flux linkage between the online and offline data. R0 represents the winding resistance value in the offline data. λ0 represents the permanent magnet flux linkage value in the offline data. α and β represent the thermal coefficients of copper and magnet, respectively.

[0117] like Figure 2 As shown, a permanent magnet synchronous motor temperature estimation system based on offline data includes:

[0118] The model building module is used to build a voltage model of a permanent magnet synchronous motor that takes temperature into account.

[0119] The offline data acquisition module is used to collect multiple sets of offline data under preset conditions to obtain multiple sets of current and voltage measurement values.

[0120] The offline data calculation module is used to calculate the sum and difference of the dq axis voltage and current products of each set of current and voltage measurements based on multiple sets of current and voltage measurements, and to obtain offline data measurement information.

[0121] The relationship fitting module, based on offline data measurement information, fits the relationship between the sum and difference of the product of dq-axis voltage and current and the current angle, current amplitude and rotational speed, and limits the current angle, current amplitude and rotational speed to obtain the sum and difference of the product of dq-axis voltage and current under the limited conditions of offline data.

[0122] The online data acquisition module is used to collect online data under certain conditions and calculate the sum and difference of the product of the dq axis voltage and current at this time, so as to obtain the sum and difference of the product of the dq axis voltage and current under the certain conditions of the online data.

[0123] The temperature estimation module transforms the voltage model of the permanent magnet synchronous motor considering temperature by calculating the sum and difference of the products of the dq-axis voltage and current under the constraints of online and offline data, and obtains the flux linkage temperature and winding temperature.

[0124] The content of the above method embodiments is applicable to this system embodiment. The specific functions implemented in this system embodiment are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0125] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A method for temperature estimation of a permanent magnet synchronous motor based on offline data, characterized in that, Includes the following steps: Construct a voltage model for a permanent magnet synchronous motor that takes temperature into account; Multiple sets of offline data were collected under preset conditions to obtain multiple sets of current and voltage measurement values; The sum and difference of the product of d-axis voltage and current are defined as including the sum of the product of d-axis voltage and current and the product of q-axis voltage and current, and the difference between the product of q-axis voltage and d-axis current and the product of q-axis current and d-axis voltage. The sum and difference of the products of the dq-axis voltage and current of each set of data are calculated based on multiple sets of current and voltage measurements to obtain offline data measurement information. Based on offline data measurement information, the relationship between the sum and difference of the product of dq-axis voltage and current and the current angle, current amplitude and rotational speed is fitted. The current angle, current amplitude and rotational speed are then constrained to obtain the sum and difference of the product of dq-axis voltage and current under the constrained conditions of offline data. Collect online data under limited conditions and calculate the sum and difference of the product of dq-axis voltage and current at this time to obtain the sum and difference of the product of dq-axis voltage and current under limited conditions in online data. Based on the sum and difference of the product of dq-axis voltage and current under the constraints of online and offline data, the voltage model of the permanent magnet synchronous motor considering temperature is transformed and calculated to obtain the flux linkage temperature and winding temperature. The step of transforming the voltage model of the permanent magnet synchronous motor considering temperature by using the sum and difference of the product of the dq-axis voltage and current under the constraints of online and offline data to obtain the flux linkage temperature and winding temperature specifically includes: By combining the voltage model of the permanent magnet synchronous motor considering temperature and replacing the parameters of the sum and difference of the product of the dq-axis voltage and current, the relationship equation of the sum and difference of the product of the dq-axis voltage and current considering temperature is obtained. Substituting the sum and difference of the products of dq-axis voltage and current under the constraints of online and offline data into the relationship equation of the sum and difference of the products of dq-axis voltage and current considering temperature, the difference is calculated to obtain the relationship equation between the difference of the sum and difference of the products of dq-axis voltage and current under the constraints of online and offline data and resistance and flux linkage. By combining the sum and difference of the products of dq-axis voltage and current under the constraints of online and offline data with the relationship equations of resistance and flux linkage, and considering the voltage model of permanent magnet synchronous motor considering temperature, the winding temperature and flux linkage temperature are obtained.

2. The method of claim 1, wherein, The voltage model of the permanent magnet synchronous motor considering temperature is expressed by the following formula: in , , and This represents the dq-axis stator voltage and current. and Indicates the inductance along the dq axis; Indicates permanent magnet flux linkage. Indicates the winding resistance. Represents electric angular velocity. and This represents the inverter's coefficients. and These represent the thermal coefficients of copper and magnet, respectively. and These are represented as flux linkage temperature and winding temperature, respectively. Indicates temperature The winding resistance value at that time, Indicates temperature The permanent magnet flux linkage value at that time.

3. The method for estimating the temperature of a permanent magnet synchronous motor based on offline data according to claim 1, characterized in that, The step of acquiring multiple sets of offline data under preset conditions to obtain multiple sets of current and voltage measurement values ​​specifically includes: Set multiple speeds, multiple current amplitudes, and multiple current angles to obtain the measurement data of dq-axis voltage and current in each state; The average value of the dq-axis voltage and current measurements under each state is calculated to obtain multiple sets of current and voltage measurements.

4. The method for estimating the temperature of a permanent magnet synchronous motor based on offline data according to claim 1, characterized in that, The step of fitting the relationship between the sum and difference of the product of dq-axis voltage and current and the current angle, current amplitude, and rotational speed based on offline data measurement information, and limiting the current angle, current amplitude, and rotational speed to obtain the sum and difference of the product of dq-axis voltage and current under the limited conditions of offline data, specifically includes: For a given current amplitude and rotational speed, the least squares method is used to fit the offline data measurement information of different current angles to obtain the relationship between the sum and difference of the product of the dq axis voltage and current and the current angle. Based on the relationship between the sum and difference of the product of the dq-axis voltage and current and the current angle, the current angle is limited to obtain the sum and difference of the product of the dq-axis voltage and current under a given current angle. By using the least squares method to fit the sum and difference of the products of the dq-axis voltage and current at different rotational speeds under a given current angle, the relationship between the sum and difference of the products of the dq-axis voltage and current and the rotational speed under a given current angle is obtained. Based on the relationship between the sum and difference of the product of the dq-axis voltage and current under a given current angle and the rotational speed, the rotational speed is limited to obtain the sum and difference of the product of the dq-axis voltage and current under a given current angle and a given rotational speed. By using the least squares method to fit the sum and difference of the products of the dq-axis voltage and current for different current amplitudes under a given current angle, the relationship between the sum and difference of the products of the dq-axis voltage and current and the current amplitude is obtained under a given current angle and a given rotational speed. Based on the relationship between the sum and difference of the product of the dq-axis voltage and current and the current amplitude under the given current angle and rotational speed, the current amplitude is limited to obtain the sum and difference of the product of the dq-axis voltage and current under the limited conditions of offline data.

5. The method for estimating the temperature of a permanent magnet synchronous motor based on offline data according to claim 1, characterized in that, The sum and difference of the products of d-axis voltage and current include the sum of the product of d-axis voltage and current and the product of q-axis point voltage and current, the product of q-axis voltage and d-axis current, and the difference between the product of q-axis current and d-axis voltage. The formulas are as follows: in This represents the sum of the products of the voltage and current along the d and q axes. This represents the difference between the products of the voltage and current along the d-q axis. , , and These represent the stator voltage and current along the d and q axes, respectively. Indicates the current amplitude. Indicates the current angle.

6. The method for estimating the temperature of a permanent magnet synchronous motor based on offline data according to claim 4, characterized in that, The step of using the least squares method to fit the sum and difference of the products of the dq-axis voltage and current at different rotational speeds under the current angle, and obtaining the relationship between the sum and difference of the products of the dq-axis voltage and current under the current angle and the rotational speed, specifically includes: Construct a relational model using piecewise functions based on polynomials; Substitute the sum and difference of the products of the dq-axis voltage and current at different rotational speeds under a given current angle into the relational model, and use the least squares method to find the polynomial coefficients of the piecewise function. Based on the polynomial coefficients of the piecewise function, the relationship between the sum and difference of the product of the voltage and current on the dq axis and the rotational speed is obtained under a given current angle.

7. The method for estimating the temperature of a permanent magnet synchronous motor based on offline data according to claim 1, characterized in that, The equation relating the sum and difference of the products of the dq-axis voltage and current under the specified conditions in online and offline data to the resistance and flux linkage is expressed as follows: in and This represents the sum and difference of the products of the dq-axis voltages and currents under specific conditions in online data. and This represents the sum and difference of the products of the dq-axis voltages and currents under the given offline data conditions. This represents a specific current angle. This indicates the determination of the current amplitude. Indicates a specific rotational speed. This indicates the winding resistance value under online data. This represents the permanent magnet flux linkage value under online data. This represents the winding resistance value under offline data. This represents the permanent magnet flux linkage value in offline data. This represents the difference in winding resistance between online and offline data. This represents the difference in permanent magnet flux linkage between online and offline data.

8. The method for estimating the temperature of a permanent magnet synchronous motor based on offline data according to claim 1, characterized in that, The winding temperature and flux linkage temperature are expressed by the following formulas: in and These represent the flux linkage temperature and the winding temperature, respectively. and This represents the difference in flux linkage temperature and winding temperature between the online and offline states. This indicates the flux linkage temperature and winding temperature in offline mode. This represents the difference in winding resistance between online and offline data. This represents the difference in permanent magnet flux linkage between online and offline data. Indicates temperature The winding resistance value at that time, Indicates temperature The permanent magnet flux linkage value at that time, and These represent the thermal coefficients of copper and magnets, respectively.

9. A temperature estimation system for a permanent magnet synchronous motor based on offline data, characterized in that, include: The model building module is used to build a voltage model of a permanent magnet synchronous motor that takes temperature into account. The offline data acquisition module is used to collect multiple sets of offline data under preset conditions to obtain multiple sets of current and voltage measurement values. The offline data calculation module is used to calculate the sum and difference of the dq axis voltage and current products of each set of current and voltage measurements based on multiple sets of current and voltage measurements, and to obtain offline data measurement information. The relationship fitting module, based on offline data measurement information, fits the relationship between the sum and difference of the product of dq-axis voltage and current and the current angle, current amplitude and rotational speed, and limits the current angle, current amplitude and rotational speed to obtain the sum and difference of the product of dq-axis voltage and current under the limited conditions of offline data. The online data acquisition module is used to collect online data under certain conditions and calculate the sum and difference of the product of the dq axis voltage and current at this time, so as to obtain the sum and difference of the product of the dq axis voltage and current under the certain conditions of the online data. The temperature estimation module transforms the voltage model of the permanent magnet synchronous motor considering temperature by calculating the sum and difference of the product of the dq axis voltage and current under the constraints of online and offline data, and obtains the flux linkage temperature and winding temperature. The sum and difference of the product of the dq-axis voltage and current under the constraints of online and offline data are used to transform the voltage model of the permanent magnet synchronous motor considering temperature, thereby obtaining the flux linkage temperature and winding temperature, specifically including: By combining the voltage model of the permanent magnet synchronous motor considering temperature and replacing the parameters of the sum and difference of the product of the dq-axis voltage and current, the relationship equation of the sum and difference of the product of the dq-axis voltage and current considering temperature is obtained. Substituting the sum and difference of the products of dq-axis voltage and current under the constraints of online and offline data into the relationship equation of the sum and difference of the products of dq-axis voltage and current considering temperature, the difference is calculated to obtain the relationship equation between the difference of the sum and difference of the products of dq-axis voltage and current under the constraints of online and offline data and resistance and flux linkage. By combining the sum and difference of the products of dq-axis voltage and current under the constraints of online and offline data with the relationship equations of resistance and flux linkage, and considering the voltage model of permanent magnet synchronous motor considering temperature, the winding temperature and flux linkage temperature are obtained.

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