Temperature Rise Calculation Method Applicable to the Healthy and Fault Conditions of Dual Three-Phase Motors

Abstract

The present invention discloses a temperature rise calculation method applicable to healthy and faulty conditions of a dual-three-phase motor. Through the temperature rise calculations for several conditions, the method determines the relationships among the stator core loss of the motor, the eddy current loss of the permanent magnet, the current of each phase, and the temperature rise of various parts of the motor, thereby establishing a model from the motor loss to the motor temperature rise. This model is a temperature rise calculation model that is applicable to both the healthy state and the single-phase open circuit state of the dual-three-phase permanent magnet synchronous motor. Compared with the existing temperature rise calculation models, this model starts from the heat sources and temperature rises in the temperature rise calculation, establishes a low-order transfer function between the heat sources and the temperature rises of various parts, has a high calculation efficiency, does not require repeated modeling, and can be applied to the healthy condition and the single-phase open circuit fault condition of the motor. On the basis of ensuring accuracy, the temperature rise calculation method of the present invention uses a low-order transfer function matrix to replace the complex temperature field finite element process, so it has a fast calculation speed.

Description

Technical Field

[0001] The present invention belongs to the field of motors, and relates to the temperature rise calculation of a dual three-phase permanent magnet synchronous motor, specifically to a temperature rise calculation method applicable to the healthy state and single-phase open circuit fault state of a dual three-phase permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors have been widely used in the fields of production and life due to their advantages such as small volume, high power density, simple structure, and stable operation. Among them, dual three-phase permanent magnet synchronous motors have attracted much attention because of their advantages such as low voltage and high power, low torque ripple, and fault tolerance performance. When the dual three-phase motor operates healthily, the internal electromagnetic field distribution is symmetric, and the traditional temperature rise calculation method can be used for temperature rise calculation; when one phase is open circuited and the fault tolerance control strategy is used for operation, only 5-phase windings continue to operate at this time, and the internal electromagnetic field and heat source distribution of the motor are uneven, and it is necessary to re-establish the model and calculate the temperature, which leads to multiple sets of models for the motor temperature rise calculation, and the calculation is complex and time-consuming. Summary of the Invention

[0003] The purpose of the present invention is to provide a temperature rise calculation method applicable to the healthy and fault conditions of a dual three-phase motor. Through the temperature rise calculation of several conditions, the relationship between the stator core loss, permanent magnet eddy current loss of the motor, and the temperature rise of each part of the motor and the current of each phase is determined, thereby establishing a model from the motor loss to the motor temperature rise. This model is a temperature rise calculation model that is simultaneously applicable to the healthy state and single-phase open circuit state of a dual three-phase permanent magnet synchronous motor. Compared with the existing temperature rise calculation model, this model starts from the heat source and temperature rise of the temperature rise calculation, establishes a low-order transfer function between the heat source and the temperature rise of each part, has a high calculation efficiency, does not require repeated modeling, and can be applied to the healthy condition and single-phase open circuit fault condition of the motor.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A temperature rise calculation method applicable to the healthy and fault conditions of a dual three-phase motor includes the following steps:

[0006] Step 1: Establish a temperature rise finite element calculation model of a dual three-phase permanent magnet synchronous motor, and separately apply the stator core loss P core , permanent magnet eddy current loss P eddy , and the winding copper loss P of one phase coil1 to the temperature rise finite element calculation model respectively, and perform three motor temperature rise calculations;

[0007] Step 2: Extract the temperature rise curves T mag , T coils , T shell of the motor parts concerned, with P core , Peddy and P coil1 as the input signal, with T mag and T coils and T shell as the output signal, construct the transfer function G(s) representing the relationship between temperature rise and loss. The specific construction method is as follows:

[0008] (1) Set the number of poles of the transfer function G(s) to n, the number of zeros to m, and assign the initial values n = 1 and m = 0. According to the number of poles n, the number of zeros m, the loss P, and the temperature rise calculation result T0 of the temperature field finite element, use the parameter identification method to calculate a1, a2... a m+1 and b1, b2... b n+1 to complete the construction of the transfer function G(s), where:

[0009]

[0010] The relationship between the temperature rise T0 and the loss P is:

[0011] T0 = G(s)P;

[0012] In the formula, G(s) is the transfer function, a1, a2... a m+1 and b1, b2... b n+1 are coefficients related to the motor structure parameters and material characteristics, s is the Laplace operator, n is the number of poles in the transfer function (n ≥ 1), m is the number of zeros (m ≥ 0 and m ≤ n), P is the loss, and T0 is the temperature rise;

[0013] (2) If the error between the temperature rise T0 calculated by the transfer function G(s) and the loss and the temperature field finite element calculation result T1 satisfies the specified range δ, then the construction of the transfer function G(s) is completed; if the error does not satisfy the specified range δ, then modify the number of poles n and the number of zeros m. If m is less than n, keep n unchanged and increase m by 1, and then return to (1) to construct the transfer function again; if m is not less than n, set m = 0 and increase n by 1, and then return to (1) to construct the transfer function again; until the suitable number of poles n and the number of zeros m are found so that the error between the temperature rise T1 calculated by the constructed transfer function G(s) and the temperature field finite element calculation result T0 satisfies the specified range δ;

[0014] Step 3. According to the periodicity of the motor stator core structure and the symmetry and periodicity of the winding distribution, the transfer function of the temperature rise of the region where the J-phase winding is located with respect to the copper loss P coil1 of the 1-phase winding is expressed as G(s) 1-J :

[0015] G(s) 1-J = G(s)2-(J+1) = G(s) 3-(J+2) = G(s) 4-(J+3) = G(s) 5-(J+4) = G(s) 6-(J+5)

[0016] = G(s) J-1 = G(s) (J+1)-2 = G(s) (J+2)-3 = G(s) (J+3)-4 = G(s) (J+4)-5 = G(s) (J+5)-6 ;

[0017] Step Four: When the dual-three-phase motor is operating normally, all 6-phase windings are working. For the region where the second-phase winding is located, the copper losses of the 6-phase windings will cause corresponding temperature rises, and the superposition principle is satisfied, that is:

[0018]

[0019] According to the above analysis, combined with the periodicity of the motor stator structure and the symmetry and periodicity of the winding distribution, the above formula is transformed into:

[0020]

[0021] Step Five: Divide the entire motor into 6 regions according to the 6-phase windings, then there is:

[0022]

[0023] According to the periodicity of the motor stator structure and the symmetry and periodicity of the winding distribution, the above formula is transformed into:

[0024]

[0025] Step Six: When the dual-three-phase motor is operating normally, if it is necessary to calculate the temperature rise at a certain point within the region where winding k is located, k ∈ [1, 6], then the temperature rise caused by copper loss is:

[0026]

[0027] The temperature rise caused by core loss is:

[0028] T coilK-Pcore = G(s) coilK-Pcore P core ;

[0029] The temperature rise caused by eddy current loss of the rotor permanent magnet is:

[0030] T coilK-Peddy = G(s) coilK-Peddy P eddy ;

[0031] The temperature rises caused by the above different losses satisfy the superposition principle, and the final total temperature rise is as follows:

[0032] T coilK = T coilK-Pcoils + T coilK-Pcore + T coilK-Peddy ;

[0033] Step 7: When the dual-three-phase motor runs with one phase open, its internal heat dissipation path remains unchanged, so the transfer function matrix characterizing the heat dissipation process remains unchanged, and only the heat source changes. The copper loss of the open phase is 0. At this time, if the temperature rise at a certain point in the region where winding k is located is to be calculated, the temperature rise caused by copper loss is:

[0034]

[0035] The temperature rise caused by core loss is:

[0036] T coilK-Pcore = G(s) coilK-Pcore P core .

[0037] The temperature rise caused by eddy current loss of the rotor permanent magnet is:

[0038] T coilK-Peddy = G(s) coilK-Peddy P eddy

[0039] The temperature rises caused by the above different losses satisfy the superposition principle, and the final total temperature rise of phase k is:

[0040] T coilK = T coilK-Pcoils + T coilK-Pcore + T coilK-Peddy .

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] 1. The temperature rise calculation method of the present invention is based on the accurate finite element calculation results of the temperature field, so it has the accuracy of the finite element calculation level. On the basis of ensuring the accuracy, a low-order transfer function matrix is used to replace the complex temperature field finite element process, so it has a fast calculation speed.

[0043] 2. The temperature rise calculation method of the present invention is different from other calculation methods. It no longer regards copper loss as a single heat source, but splits it according to the number of phases of the motor, so as to realize the refined calculation of the motor temperature rise. Therefore, the model established by this method has universality and can be used for both normal and faulty motors. As long as the heat source parameters of the current working condition are given, the motor temperature rise can be calculated quickly and accurately through this model. Description of the Drawings

[0044] Figure 1 It is the structure diagram of a dual three-phase permanent magnet synchronous motor. (a) is the schematic diagram, where: 1-1 is the permanent magnet, 1-2 is the motor rotor, 1-3 is the motor stator, and 1-4 is the winding; (b) divides the motor into 6 regions according to the 6-phase winding, and A1 - A6 and B1 - B6 are the temperature rise monitoring points in the slot and the motor housing respectively.

[0045] Figure 2 It is a process of establishing an equivalent low-order transfer function by taking the loss as the input signal and the temperature rise as the output signal.

[0046] Figure 3 It is the temperature in the 6-phase winding slots (i.e., the temperatures at points A1 - A6) and the temperature of the motor housing (i.e., the temperatures at points B1 - B6) when the motor is operating normally, calculated based on the method proposed in the present invention.

[0047] Figure 4 It is the temperature in the 6-phase winding slots (i.e., the temperatures at points A1 - A6) and the temperature of the motor housing (i.e., the temperatures at points B1 - B6) when a single-phase winding is open (the second phase is open), calculated based on the method proposed in the present invention. a) is the winding temperature rise (temperature rise at points A1 - A6) curve, and b) is the motor housing temperature rise (temperature rise at points B1 - B6) curve.

[0048] Figure 5 It is the temperature rise calculation results under healthy and faulty conditions calculated using the present invention and the finite element method of the temperature field. a) is the temperature rise at points A4 and B4 under faulty conditions calculated using the finite element method of the temperature field and the method proposed in the present invention under healthy conditions, and b) is the temperature rise at points A4 and B4 under faulty conditions calculated using the finite element method of the temperature field and the method proposed in the present invention under faulty conditions. Detailed implementation manners

[0049] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings, but it is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be covered by the protection scope of the present invention.

[0050] The present invention provides a temperature rise calculation method applicable to the healthy state and single-phase open state of a dual three-phase permanent magnet synchronous motor. The method includes the following steps:

[0051] 1) Establish a finite element calculation model for the temperature rise of the dual three-phase permanent magnet synchronous motor. Since there is a faulty operating state of single-phase open in the dual three-phase motor, which causes the copper loss distribution to be asymmetric, the total copper loss cannot be used as a single heat source. Instead, the copper losses of each phase winding should be used as heat sources respectively, and the temperature rise effects caused by the 6-phase copper losses should be considered separately. Apply the stator core loss P of the motor to the finite element calculation model of the motor temperature rise separatelycore 1. The eddy current loss \(P\) of the permanent magnet eddy and the copper loss \(P\) of the winding of one phase coil1 are used to perform the motor temperature rise calculation three times.

[0052] 2) Extract the temperature rise curves \(T\) mag , \(T\) coils , \(T\) shell of the motor parts of interest (such as the permanent magnet, winding, housing, etc.). Using various losses as input signals and the temperature rise curves of interest as output signals, construct the transfer function \(G(s)\) that characterizes the relationship between temperature rise and loss.

[0053] 3) Set the number of poles of the constructed transfer function \(G(s)\) to \(n\) and the number of zeros to \(m\), and assign the initial values \(n = 1\) and \(m = 0\). According to the number of poles \(n\), the number of zeros \(m\), the loss \(P\), and the temperature rise calculation result \(T_0\) of the temperature field finite element, use the parameter identification method to calculate \(a_1\), \(a_2\cdots a\) m+1 and \(b_1\), \(b_2\cdots b\) n+1 to complete the construction of the transfer function \(G(s)\), where

[0054]

[0055] The relationship between the temperature rise \(T_0\) and the loss \(P\) is

[0056] \(T_0 = G(s)P\);

[0057] In the formula, \(G(s)\) is the transfer function, \(a_1\), \(a_2\cdots a\) m+1 and \(b_1\), \(b_2\cdots b\) n+1 are coefficients related to the motor structure parameters and material characteristics, \(s\) is the Laplace operator, \(n\) is the number of poles in the transfer function (\(n\geq1\)), \(m\) is the number of zeros (\(m\geq0\) and \(m\leq n\)), \(P\) is the loss, and \(T_0\) is the temperature rise.

[0058] 4) If the error between the temperature rise \(T_0\) calculated by the transfer function \(G(s)\) and the loss and the temperature field finite element calculation result \(T_1\) meets the specified range \(\delta\lt3^{\circ}C\), the construction of the transfer function \(G(s)\) is completed; if the error does not meet the specified range \(\delta\), modify the number of poles \(n\) and the number of zeros \(m\). If \(m\lt n\), keep \(n\) unchanged and increase \(m\) by 1, and then return to step 3) to construct the transfer function; if \(m\geq n\), set \(m = 0\) and increase \(n\) by 1, and then return to step 3) to construct the transfer function; until suitable numbers of poles \(n\) and zeros \(m\) are found so that the error between the temperature rise \(T_1\) calculated by the constructed transfer function \(G(s)\) and the temperature field finite element calculation result \(T_0\) meets the specified range \(\delta\).

[0059] 5) Since only the copper loss \(P\) of one phase is used coil1To calculate the temperature rise of the motor, the transfer function of the copper loss of one phase to the temperature rise in the regions of the other five-phase windings can be determined using the above method.P coil1 The transfer function of the temperature rise in the region where the J-phase winding is located can be expressed as G(s) 1-J .

[0060] 6) Due to the periodicity of the motor stator core structure and the symmetry and periodicity of the winding distribution, the following relationship exists:

[0061] G(s) 1-J = G(s) 2-(J+1) = G(s) 3-(J+2) = G(s) 4-(J+3) = G(s) 5-(J+4) = G(s) 6-(J+5)

[0062] = G(s) J-1 = G(s) (J+1)-2 = G(s) (J+2)-3 = G(s) (J+3)-4 = G(s) (J+4)-5 = G(s) (J+5)-6 .

[0063] 7) When the dual three-phase motor is operating normally, all six-phase windings are operating. For the region where the second-phase winding is located, the copper losses of all six-phase windings will cause corresponding temperature rises, and the superposition principle is satisfied, that is:

[0064]

[0065] According to the above analysis, combined with the periodicity of the motor stator structure and the symmetry and periodicity of the winding distribution, the above formula can be transformed into:

[0066]

[0067] That is, the transfer functions in the transfer function matrix are all calculated using the copper loss of the first-phase winding. Therefore, only the calculation results of the copper loss of one phase are used to characterize the temperature rise caused by the copper losses of all six phases.

[0068] 8) If the entire motor is evenly divided into six regions according to the six-phase windings, then:

[0069]

[0070] According to the periodicity of the motor stator structure and the symmetry and periodicity of the winding distribution, the above formula can be transformed into:

[0071]

[0072] At this time, the transfer functions inside the transfer function matrix are all the copper losses obtained when the copper loss of a given single-phase winding is considered. By using the transfer function corresponding to the copper loss of a single-phase winding, the motor temperature rise can be calculated when the copper loss of the six-phase winding is given.

[0073] 9) When the dual three-phase motor is operating normally, if it is necessary to calculate the temperature rise at a certain point within the area where winding 5 is located, the temperature rise caused by copper loss:

[0074]

[0075] The temperature rise caused by core loss:

[0076] T coil5-Pcore = G(s) coil5-Pcore P core .

[0077] The temperature rise caused by eddy current loss of the rotor permanent magnet:

[0078] T coil5-Peddy = G(s) coil5-Peddy P eddy .

[0079] The temperature rises caused by the above different losses satisfy the superposition principle, and the final total temperature rise is:

[0080] T coil5 = T coil5-Pcoils + T coil5-Pcore + T coil5-Peddy .

[0081] 10) When the dual three-phase motor is operating with one phase open-circuited, its internal heat dissipation path remains unchanged, so the transfer function matrix characterizing the heat dissipation process remains unchanged, only the heat source changes, and the copper loss of the open-circuited phase is 0 (assuming it is the sixth phase). At this time, if it is necessary to calculate the temperature rise at a certain point within the area where winding 5 is located, the temperature rise caused by copper loss:

[0082]

[0083] The temperature rise caused by core loss:

[0084] T coil5-Pcore = G(s) coil5-Pcore P core .

[0085] The temperature rise caused by eddy current loss of the rotor permanent magnet:

[0086] T coil5-Peddy = G(s) coil5-Peddy P eddy

[0087] The temperature rises caused by the above different losses satisfy the superposition principle, and the final total temperature rise is:

[0088] T coil5 = T coil5-Pcoils + T coil5-Pcore + T coil5-Peddy 。

[0089] 12) The rotor of the motor rotates continuously, so the temperature rise of each part in the circumferential direction is the same. When calculating its temperature rise, it is only necessary to take the average value of the temperature rises in the six regions.

[0090] Example 1:

[0091] Figure 1 It is a finite element model of a 22-pole 24-slot double-layer winding dual three-phase permanent magnet synchronous motor. The rated speed of the motor is 1800 r / min, the rated frequency is 330 Hz, and the control method of id = 0 is used for control. For the Figure 1 motor in, a finite element model of the temperature field is established, and only one-phase current is applied, and the copper loss P coil1 caused by this phase current is used as the heat source to perform finite element calculation of the temperature field, and the temperature rise T As-Pcoils at points A1 - A6 is extracted. Using the copper loss P coil1 caused by this phase current as the input signal and the temperature rise T As-Pcoils at points A1 - A6 as the output signal, using the Figure 2 shown process, the construction of the transfer function matrix can be completed, and the calculation of the temperature rise at A1 - A6 caused by the single-phase copper loss can be completed.

[0092] Based on the periodicity of the stator structure of the dual three-phase motor and the symmetry and periodicity of the winding, the transfer function of the single-phase copper loss P coil1 to the temperature rise T As-Pcoils at points A1 - A6 can be used to construct the transfer function matrix of all 6-phase copper losses P coil1 , P coil2 , P coil3 , P coil4 , P coil5 , P coil6 to the temperature rise T As-Pcoils at points A1 - A6:

[0093]

[0094] Using this transfer function matrix, the temperature rise caused by the copper loss at points A1 - A6 can be quickly calculated.

[0095] Using the same method, calculate the transfer function of the stator core loss P core and the rotor permanent magnet eddy current loss P eddy to points A1 - A6. It should be noted that due to the stator core loss P core and the rotor permanent magnet eddy current loss P eddyThey are evenly distributed, and points A1 - A6 are also evenly and periodically distributed. Therefore, they can be represented by a single transfer function, that is:

[0096]

[0097] Therefore, for the temperature rise of points A1 - A6, it is jointly caused by the copper loss Pcoils, the stator core loss P core and the eddy current loss P eddy of the rotor permanent magnet, and the resulting temperature rise satisfies the superposition principle. The temperature rise calculation model is:

[0098]

[0099] When the dual three - phase permanent magnet synchronous motor is in a healthy working state, the 6 - phase copper losses are equal, and the heat sources inside the motor show a uniform, symmetric and periodic distribution. At this time, the temperature rises of points A1 - A6 are equal, as Figure 3 shown; when the motor operates with a single - phase open - circuit (the second - phase open - circuit), the copper loss P coil2 of the second phase = 0. The heat source distribution inside the motor is uneven, resulting in the smallest temperature rise at point A2. Points A1 and A3 adjacent to A2 are greatly affected, points A6 and A4 which are the next - nearest are less affected, and point A5 which is the farthest away is the least affected, and the temperature rise hardly changes.

[0100] It should be noted that A1 - A6 are just points selected for convenience in explaining the method of the present invention. For any point on the motor stator, the method of the present invention is applicable. For example, for points B1 - B6 on the motor housing, the method of the present invention can still quickly and accurately obtain the temperature rise results, as Figure 3 、 Figure 4 shown. As Figure 3 shown, the motor operating condition is that it stops for cooling at the 900th second after working for 300 seconds. At this time, the copper loss of the second phase inside the motor is 0, and the heat source distribution is unbalanced, so the temperatures of each point are different. As Figure 5 shown, compared with the finite - element calculation results of the temperature field, this method can obtain the accuracy at the finite - element level, and at the same time can greatly improve the speed of temperature rise calculation, and can realize the real - time calculation of the motor temperature rise. The comparison of the accuracy and calculation duration between this method and the finite - element method is shown in Table 1.

[0101] Table 1 Comparison of motor temperature rise calculation results under different working conditions using different methods

[0102]

[0103]

Claims

1. A temperature rise calculation method applicable to healthy and faulty conditions of a dual three-phase motor, characterized in that The method includes the following steps: Step 1. Establish a temperature rise finite element calculation model for a dual three-phase permanent magnet synchronous motor, and separately apply the stator core loss P core of the motor, the eddy current loss P eddy of the permanent magnet, and the winding copper loss P coil1 of one phase to the temperature rise finite element calculation model respectively, and perform three motor temperature rise calculations; Step 2: Extract the temperature rise curve T of the motor part of interest mag , T coils , T shell , taking P core , P eddy , P coil1 as the input signal, and taking T mag , T coils , T shell as the output signal, construct the transfer function G(s) that characterizes the relationship between temperature rise and loss; Step 3. According to the periodicity of the motor stator core structure and the symmetry and periodicity of the winding distribution, the copper loss P of the winding of Phase 1 coil1 The transfer function of the temperature rise of the region where the winding of Phase J is located is expressed as G(s) 1-J : G(s) 1-J = G(s) 2-(J+1) = G(s) 3-(J+2) = G(s) 4-(J+3) = G(s) 5-(J+4) = G(s) 6-(J+5) = G(s) J-1 = G(s) (J+1)-2 = G(s) (J+2)-3 = G(s) (J+3)-4 = G(s) (J+4)-5 = G(s) (J+5)-6 ; Step 4: When the dual three-phase motor is operating normally, all 6-phase windings are working. For the region where the second-phase winding is located, the copper losses of the 6-phase windings will cause corresponding temperature rises, and the superposition principle is satisfied, that is: Based on the above analysis, considering the periodicity of the motor stator structure and the symmetry and periodicity of the winding distribution, the above formula is transformed into: Step 5: Divide the entire motor into 6 regions according to the 6-phase windings, then there is: Based on the periodicity of the motor stator structure and the symmetry and periodicity of the winding distribution, the above formula is transformed into: Step 6: When the dual three-phase motor is operating normally, if it is necessary to calculate the temperature rise at a certain point within the region where winding k is located, k ∈ [1, 6], then the temperature rise caused by copper loss is: The temperature rise caused by core loss is: T coilK-Pcore = G(s) coilK-Pcore P core ; The temperature rise caused by rotor permanent magnet eddy current loss is: T coilK-Peddy = G(s) coilK-Peddy P eddy ; The temperature rises caused by the above different losses satisfy the superposition principle, and the final total temperature rise is: T coilK = T coilK-Pcoils + T coilK-Pcore + T coilK-Peddy ; Step 7: When the dual three-phase motor operates with one phase open, its internal heat dissipation path remains unchanged, so the transfer function matrix characterizing the heat dissipation process remains unchanged, only the heat source changes. The copper loss of the open phase is 0. At this time, if it is necessary to calculate the temperature rise at a certain point within the region where winding k is located, then the temperature rise caused by copper loss is: The temperature rise caused by core loss is: T coilK-Pcore = G(s) coilK-Pcore P core The temperature rise caused by rotor permanent magnet eddy current loss is: T coilK-Peddy = G(s) coilK-Peddy P eddy The temperature rises caused by the above different losses satisfy the superposition principle, and the final total temperature rise of phase k is: T coilK = T coilK-Pcoils + T coilK-Pcore + T coilK-Peddy 。 2. The temperature rise calculation method applicable to the healthy and faulty conditions of a dual-three-phase motor according to claim 1, wherein In the above Step 2, the specific construction method of the transfer function G(s) is as follows: (1) Set the number of poles of the transfer function G(s) to n, the number of zeros to m, assign the initial values n = 1 and m = 0, and use the parameter identification method to calculate a1, a2... a m+1 and b1, b2... b n+1 based on the number of poles n, the number of zeros m, the loss P, and the temperature rise calculation result T0 of the temperature field finite element, thereby completing the construction of the transfer function G(s), where: The relationship between the temperature rise T0 and the loss P is: T0 = G(s)P; where G(s) is the transfer function, a1, a2... a m+1 and b1, b2... b n+1 are coefficients related to the motor structure parameters and material properties, s is the Laplace operator, n is the number of poles in the transfer function, n≥1, m is the number of zeros, m≥0 and m≤n, P is the loss, and T0 is the temperature rise; (2) If the error between the temperature rise T0 calculated through the transfer function G(s) and the loss and the temperature field finite element calculation result T1 satisfies the specified range δ, then the construction of the transfer function G(s) is completed; if the error does not satisfy the specified range δ, then modify the number of poles n and the number of zeros m. If m is less than n, then keep n unchanged and increase m by 1, and then return to (1) to construct the transfer function again; if m is not less than n, then set m = 0 and increase n by 1, and then return to (1) to construct the transfer function again; until suitable numbers of poles n and zeros m are found so that the error between the temperature rise T1 calculated by the constructed transfer function G(s) and the temperature field finite element calculation result T0 satisfies the specified range δ.

3. The method for calculating temperature rise applicable to healthy and faulty conditions of a dual-three-phase motor according to claim 2, characterized in that The δ < 3°C.

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