Method for conveniently calculating top turn copper wire loss of surface cooling stator generator

Abstract

The invention relates to a method for conveniently calculating the loss of a top turn copper wire of a surface-cooled stator generator, which realizes the rapid calculation of the loss of the top turn copper wire of the surface-cooled stator generator by inputting 11 electromagnetic design parameters of the surface-cooled stator generator through 14 simple steps, and is suitable for an air-cooled synchronous generator and a hydrogen-cooled air-cooled synchronous generator. The automatic calculation of the top turn copper wire loss of the surface-cooled stator generator can be realized only by inputting 11 parameters and 14 calculation steps, so that the method can well meet the calculation requirements of development of related new machine technical schemes, and the purpose of conveniently, quickly and accurately obtaining the top turn copper wire loss of the surface-cooled stator generator is achieved. The workload and long calculation time of simulation modeling of numerical calculation are avoided, so that the problems of high calculation complexity and loss of part of numerical values due to the fact that a program is introduced to calculate the loss of the top turn copper wire in the stator slot are solved, and the method has the advantages of less input data, simplicity and convenience in operation, quickness in calculation and drawing and simplicity and intuitiveness in process.

Description

Technical Field

[0001] The invention relates to an electromagnetic technology of a synchronous motor, and in particular to a convenient calculation method for determining the top turn copper wire loss of a surface-cooled stator generator, which can be used in the product design and development of the surface-cooled stator generator. Background Art

[0002] According to the different cooling media in the machine, surface-cooled stator generators are usually divided into two categories: air cooling and hydrogen cooling. The surface-cooled stator cooling structure makes the generator have technical advantages such as simple cooling structure and small wind resistance of the ventilation system; on the other hand, due to the indirect cooling method of stator coil surface cooling, the cooling effect is worse than coil internal cooling, and for this type of generator, the temperature bottleneck in the stator slot is at the top turn copper wire, so the accuracy of the calculation of the top turn copper wire loss in the stator slot is crucial to the success of the model development.

[0003] In order to solve the technical difficulty of calculating the top turn copper wire loss in the stator slot, the imported program was used to calculate it in the past. Since the imported program has complex interweaving of electromagnetic, loss, ventilation, and heat dissipation multi-physics field variables, and the program has no output value for the top turn copper wire loss in the stator slot, it is very inconvenient for engineering application. In order to quickly and accurately determine the top turn copper wire loss of the surface-cooled stator generator, it is necessary to develop a new convenient calculation method. Summary of the invention

[0004] Aiming at the problem that the calculation of the top turn copper wire loss in the stator slot is highly complex and some numerical outputs are missing when using imported programs, a convenient method for calculating the top turn copper wire loss of the surface-cooled stator generator is proposed. The convenient loss calculation formula is used to quickly calculate the top turn copper wire loss in the stator slot, providing a convenient algorithm for product development to quickly and accurately control the heating of the copper wire in the stator slot, so as to improve the efficiency of scheme design and optimization.

[0005] The technical solution of the present invention is:

[0006] A method for conveniently calculating the top turn copper wire loss of a surface-cooled stator generator comprises the following steps:

[0007] Step 1: Obtain and input the parameters required to complete the calculation, including the stator upper copper wire height a cu1 , stator lower layer strand height a′ cu1 , stator strand width b cu1 , the number of rows of strands in each bar-shaped conductor on the upper layer of the stator m1, the number of rows of strands in each bar-shaped conductor on the lower layer of the stator m′1, the number of columns of stator strands n1, the frequency of the alternating current in the stator winding f n , stator copper conductor conductivity σ at 75°C, stator current I n , the number of stator winding parallel branches a1, the length of the stator core l t, the magnetic permeability of copper μ;

[0008] Step 2: Calculate the basic copper consumption q0 of each copper wire in the upper layer of the slot, which is:

[0009]

[0010] Step 3: Calculate the basic copper loss q′0 of each copper wire in the lower layer of the slot, and we have:

[0011]

[0012] Step 4: Calculate the circulation loss q of each copper wire in the upper layer of the slot c ,have:

[0013] q c =Kc·q0

[0014] Where Kc is the circulation loss q c The proportion of DC loss q0 is generally Kc = 0.12 according to the motor design manual;

[0015] Step 5: Calculate the electrical angular velocity ω:

[0016] ω=2·π·f n

[0017] Step 6: Calculate the penetration depth of AC in the stator copper conductor δ ac ,have:

[0018]

[0019] Step 7: Calculate the ratio coefficient k of the upper eddy current loss in the slot to the basic copper loss ed ,have:

[0020]

[0021] Step 8: Calculate the ratio coefficient k' of the eddy current loss in the lower layer of the slot to the basic copper loss ed ,have:

[0022]

[0023] Step 9: Calculate the total eddy current loss Q of each copper wire rod in the upper layer of the slot e ,have:

[0024] Q e =q0·m1·n1·k ed

[0025] Step 10: Calculate the ratio coefficient Q′ of the eddy current loss in the lower layer of the slot to the basic copper loss e ,have:

[0026] Q′ e =q′0·m′1·n1·k′ ed

[0027] Step 11, calculate the parameter a, we have:

[0028]

[0029] Step 12: Calculate parameter b:

[0030]

[0031] The loss of the nth strand from the bottom of the slot to the slot opening in the stator slot is q = a·n 2 +b, where a and b are the coefficients of the quadratic function;

[0032] Step 13: Calculate the eddy current loss q of the top turn copper strand in the slot e ,have:

[0033]

[0034] Step 14: Calculate the top turn copper strand loss q in the slot cuT ,have:

[0035] q cuT =q0+q c +q e

[0036] Use EXCEL language to calculate the basic copper loss q0 recorded in step 2 and the circulation loss q of each copper wire in the upper layer of the slot recorded in step 4. c Calculation formula, the ratio coefficient k of the upper eddy current loss in the slot recorded in step 7 to the basic copper loss ed Calculation formula, calculation formula for parameter a in step 11, calculation formula for parameter b in step 12, eddy current loss q of the top turn copper strand in the slot recorded in step 13 e The calculation formula and the top turn copper strand loss q recorded in step 14 cuT Calculation formula, prepare table cooling stator generator top turn copper wire loss automatic calculation EXCEL file, the stator upper copper wire height a cu1 , stator lower layer strand height a′ cu1 , stator strand width b cu1 , the number of rows of strands in each bar-shaped conductor on the upper layer of the stator m1, the number of rows of strands in each bar-shaped conductor on the lower layer of the stator m′1, the number of columns of stator strands n1, the frequency of the alternating current in the stator winding f n , stator copper conductor conductivity σ at 75°C, stator current I n , the number of stator winding parallel branches a1, the length of the stator core l tAfter the magnetic permeability μ of copper is input into the automatic calculation EXCEL file of the top turn copper wire loss of the surface-cooled stator generator, the top turn copper wire loss q of the surface-cooled stator generator is automatically calculated. cuT .

[0037] Furthermore, the implementation principle is as follows:

[0038] The stator slot of the surface-cooled generator of the analysis model has one upper layer and one lower layer wire bar in the slot, and each wire bar has two rows of solid copper strands; in the upper layer wire bar near the slot, taking the left row of copper wires as an example, from the bottom of the slot to the number of slots, the strands are numbered 1, 2...m1; in the lower layer wire bar near the bottom of the slot, taking the left row of copper wires as an example, from the bottom of the slot to the number of slots, the strands are numbered 1, 2...m′1; due to the transposition structure between the solid strands in the wire bar, the top turn solid copper strands in the left row of the wire bar are connected at the top center of the wire bar, and the strands are numbered m1 for the upper layer wire bar and m′1 for the lower layer wire bar;

[0039] Losses in the stator strands, including DC losses, circulating losses, and eddy current losses;

[0040] For the lower layer of wire bars near the bottom of the stator slot, the loss q′ of the nth strand is counted from the bottom of the slot to the slot mouth. n for:

[0041] q′ n =a·n 2 +b——(I)

[0042] For the upper layer of wire bars near the slot opening in the stator slot, the loss q of the nth strand is calculated from the slot bottom to the slot opening. n for:

[0043] q n =a·n 2 +b+Δ——(II)

[0044] Where a and b are the coefficients of the quadratic function; Δ is the difference between the loss of the first strand of the upper wire bar closest to the bottom of the slot and the loss of the first strand of the lower wire bar closest to the bottom of the slot;

[0045] The losses of the strands 1, 2···m′1 in the lower layer of the stator slot near the bottom are accumulated, and the total loss of the lower layer is obtained as follows:

[0046]

[0047] The losses of the strands 1, 2, ···m1 in the upper layer of the stator slot near the slot opening are accumulated, and the total loss of the upper layer is obtained as follows:

[0048]

[0049] Combining equations (I) to (IV) and the distribution characteristics of the leakage flux of the upper and lower layers of the stator slot, the coefficients a and b of the quadratic function are solved as the expressions of the coefficients a and b in step 11 and step 12; based on this, the calculation formula for the eddy current loss of the top turn copper wire in the stator slot is obtained as q in step 13 e The total loss of the top-turn strand is then accumulated with the DC loss and circulating current loss.

[0050] The beneficial effects of the present invention are:

[0051] The present invention realizes the quick calculation of the top turn copper wire loss of the surface-cooled stator generator through 14 simple steps by inputting 11 electromagnetic design parameters of the surface-cooled stator generator, and is suitable for air-cooled synchronous generators and hydrogen-cooled air-cooled synchronous generators. Since only 11 parameters and 14 calculation steps are needed to realize the automatic calculation of the top turn copper wire loss of the surface-cooled stator generator, the present invention can well adapt to the calculation requirements of the development of relevant new machine technical solutions, and achieve the purpose of conveniently, quickly and accurately obtaining the top turn copper wire loss of the surface-cooled stator generator. The workload and long calculation time of simulation modeling of numerical calculation are avoided, so the present invention overcomes the shortcomings of technical problems and obtains technical advantages such as less input data, simple operation, quick calculation and drawing, and concise and intuitive process. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 Schematic diagram of stator slots of surface-cooled stator generator and calculation model and calculation principle in the present invention;

[0053] Figure 2 A schematic diagram of inputting data in an embodiment of the present invention;

[0054] Figure 3 A schematic diagram of outputting calculation results in an embodiment of the present invention;

[0055] Figure 4 The present invention is a flow chart of a convenient method for calculating the top turn copper wire loss of a table-cooled stator generator. DETAILED DESCRIPTION

[0056] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0057] The loss of the nth strand from the bottom of the slot to the slot opening in the stator slot of the present invention is q=a·n 2 +b[See attached Figure 1(b)], and combined with the leakage magnetic field distribution law in the motor stator slot, a set of simple and feasible loss calculation formulas close to reality is obtained. This solves the problem that the loss, temperature rise and flow field are packaged together in the previous program, making it difficult to clearly quantify and output the loss.

[0058] like Figure 4 As shown, the method disclosed in this embodiment for conveniently calculating the top turn copper wire loss of a cold stator generator specifically includes the following steps:

[0059] Step 1. Enter the parameters required to complete the calculation:

[0060] The 11 input parameters required for the construction include: stator upper copper wire height (per strand) a cu1 (Unit: mm), stator lower layer strand height (each strand) a′ cu1 (Unit: mm), stator strand width (each strand) b cu1 (Unit: mm), the number of rows of strands in each bar-shaped conductor on the upper layer of the stator m1, the number of rows of strands in each bar-shaped conductor on the lower layer of the stator m′1, the number of stator strands n1, the frequency of the alternating current in the stator winding f n (unit: Hz), stator copper conductor conductivity σ at 75°C (unit: S / μm), stator current I n (Unit: A), number of stator winding parallel branches a1, stator core length l t (Unit: mm), magnetic permeability of copper μ (Unit: H / m).

[0061] Step 2: Calculate the basic copper consumption q0 of each copper wire in the upper layer of the slot, which is:

[0062]

[0063] In the formula, the unit of the basic copper loss q0 of each copper wire in the upper layer is W.

[0064] Step 3: Calculate the basic copper loss q′0 of each copper wire in the lower layer of the slot, and we have:

[0065]

[0066] Wherein, the unit of the basic copper loss q′0 of each copper wire in the lower layer is W.

[0067] Step 4: Calculate the circulation loss q of each copper wire in the upper layer of the slot c ,have:

[0068] q c =Kc·q0

[0069] Where Kc is the circulation loss q cThe proportion of DC loss q0 is generally Kc = 0.12 according to the motor design manual;

[0070] In the formula, the calculated circulation loss of each copper wire in the upper layer is q c The unit is W.

[0071] Step 5: Calculate the electrical angular velocity ω:

[0072] ω=2·π·f n

[0073] Wherein, the unit of the calculated electrical angular velocity ω is Hz.

[0074] Step 6: Calculate the penetration depth of AC in the stator copper conductor δ ac ,have:

[0075]

[0076] In the formula, the calculated penetration depth δ ac The unit is mm.

[0077] Step 7: Calculate the ratio coefficient k of the upper eddy current loss in the slot to the basic copper loss ed ,have:

[0078]

[0079] Step 8: Calculate the ratio coefficient k' of the eddy current loss in the lower layer of the slot to the basic copper loss ed ,have:

[0080]

[0081] Step 9: Calculate the total eddy current loss Q of each copper wire rod in the upper layer of the slot e ,have:

[0082] Q e =q0·m1·n1·k ed

[0083] In the formula, the total eddy current loss Q of each copper wire rod in the upper layer is calculated as e The unit is W.

[0084] Step 10: Calculate the ratio coefficient Q′ of the eddy current loss in the lower layer of the slot to the basic copper loss, which is:

[0085] Q′ e =q′0·m′1·n1·k′ ed

[0086] In the formula, the ratio coefficient of the calculated lower layer eddy current loss to the basic copper loss is Q′ e The unit is W.

[0087] Step 11, calculate the parameter a, we have:

[0088]

[0089] Wherein, the unit of the calculated parameter a is W.

[0090] Step 12: Calculate parameter b:

[0091]

[0092] Wherein, the unit of the calculated parameter b is W.

[0093] Step 13: Calculate the eddy current loss q of the top turn copper strand in the slot e ,have:

[0094]

[0095] In the formula, the eddy current loss q of the top turn copper strand in the slot is calculated e The unit is W.

[0096] Step 14: Calculate the top turn copper strand loss q in the slot cuT ,have:

[0097] q cuT =q0+q c +q e

[0098] In the formula, the calculated top turn copper strand loss in the slot is q cuT The unit is W.

[0099] The principle analysis is as follows:

[0100] like Figure 1 As shown in (a), the stator slot of the surface-cooled generator of the analysis model has one upper and one lower wire bar in the slot, and each wire bar has two rows of solid copper strands. In the upper wire bar near the slot, taking the left row of copper wires as an example, the strands are numbered 1, 2...m1 from the bottom of the slot to the number of slots; in the lower wire bar near the bottom of the slot, taking the left row of copper wires as an example, the strands are numbered 1, 2...m′1 from the bottom of the slot to the number of slots. Due to the transposition structure between the solid strands in the wire bar, the top turn solid copper strands in the left row of the wire bar (the strands are numbered m1 for the upper wire bar and m′1 for the lower wire bar) are connected at the center of the top of the wire bar.

[0101] The losses in the stator strands include DC loss, circulating current loss and eddy current loss. There are relatively clear empirical formulas for the calculation of DC loss and circulating current loss; while for the calculation of eddy current loss, generally only the total eddy current loss of the upper and lower layers of the wire rods in the slot is used. It is urgent to innovate an effective algorithm to determine the eddy current loss in the top turn strands, and then add it with the DC loss and circulating current loss to get the total loss of the top turn strands.

[0102] like Figure 1 As shown in (b), for the lower layer of wire rods near the bottom of the stator slot, the loss q′ of the nth strand is counted from the bottom of the slot to the slot mouth. n for:

[0103] q′ n =a·n 2 +b——(I)

[0104] For the upper layer of wire bars near the slot opening in the stator slot, the loss q of the nth strand is calculated from the slot bottom to the slot opening. n for:

[0105] q n =a·n 2 +b+Δ——(II)

[0106] Where a and b are the coefficients of the quadratic function; Δ is the difference between the loss of the first strand of the upper wire bar closest to the bottom of the slot and the loss of the first strand of the lower wire bar closest to the bottom of the slot.

[0107] The losses of the strands 1, 2···m′1 in the lower layer of the stator slot near the bottom are accumulated, and the total loss of the lower layer is obtained as follows:

[0108]

[0109] The losses of the strands 1, 2, ···m1 in the upper layer of the stator slot near the slot opening are accumulated, and the total loss of the upper layer is obtained as follows:

[0110]

[0111] Combining equations (I) to (IV) and the distribution characteristics of the leakage flux of the upper and lower layers of the stator slot, the coefficients a and b of the quadratic function (i.e., parabola) are solved as the expressions of the coefficients a and b in step 11 and step 12. Based on this, the calculation formula for the eddy current loss of the top turn copper wire in the stator slot is obtained as q in step 13 e The total loss of the top turn strand is then added to the DC loss and the circulating current loss to obtain the total loss of the top turn strand. The total loss of the top turn strand is closely related to the heating and temperature rise of the top turn strand, that is, the loss of the top turn copper strand in the slot in step 14 obtained by the present invention is q cuT It is a very critical physical quantity in the design and development of stator surface-cooled generators.

[0112] The method provided by the present invention can be completed by manual calculation (using a scientific calculator to obtain the calculation result according to the formula in the method disclosed by the present invention). In order to more intuitively reflect the calculation ideas proposed by the present invention, this embodiment selects EXCEL in OFFICE office software as the input and output interface, and the calculation of the present invention can be realized by the function function of EXCEL.

[0113] like Figure 2 As shown, in this embodiment, a convenient calculation table named QCUTS (Quantity of copper (CU) loss at Top turen of Stator winding's calculation program) is compiled in the windows operating system using the EXCEL language. This program is an ordinary EXCEL document of the table tool under the windows operating system.

[0114] Taking the QFQ-500-2 all-hydrogen cooled generator as an example, the stator top turn copper wire loss is calculated. The specific operation process is as follows:

[0115] Step 1: Open EXCEL, such as Figure 2 As shown, under the "1. Input data" cell, enter 11 parameters in sequence, including the stator upper copper wire height (each strand) a cu1 =2mm, stator lower layer strand height (each strand) a′ cu1 =2mm, stator strand width (each strand) b cu1 =12.7mm, the number of rows of strands in each bar-shaped conductor in the upper layer of the stator m1 = 52, the number of rows of strands in each bar-shaped conductor in the lower layer of the stator m′1 = 40, the number of stator strands n1 = 2, the frequency of the alternating current in the stator winding f n =50Hz, 75℃ stator copper conductor conductivity σ=47.7S / μm, stator current I n =15500A, number of stator winding parallel branches a1 = 2, stator core length I t =6100mm, magnetic permeability of copper μ = 1.25664 / 10 6 H / m.

[0116] Step 2: If Figure 3 As shown, because the calculation formula is compiled in EXCEL according to the formula content of the present invention based on the application of EXCEL simple functions, "2. Calculate the basic copper loss q0 of each copper wire in the upper layer of the slot" to "14. Calculate the loss q0 of the top turn copper strand in the slot" are automatically generated. cuT ” calculation results.

[0117] The above-mentioned embodiment only expresses one implementation mode of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A method for conveniently calculating the top turn copper wire loss of a surface-cooled stator generator, characterized in that: The following steps are involved: Step 1: Obtain and input the parameters required to complete the calculation, including the stator upper copper wire height a cu1 , stator lower layer strand height a′ cu1 , stator strand width b cu1 , the number of rows of strands in each bar-shaped conductor on the upper layer of the stator m1, the number of rows of strands in each bar-shaped conductor on the lower layer of the stator m′1, the number of columns of stator strands n1, the frequency of the alternating current in the stator winding f n , stator copper conductor conductivity σ at 75°C, stator current I n , the number of stator winding parallel branches a1, the length of the stator core l t , the magnetic permeability of copper μ; Step 2: Calculate the basic copper consumption q0 of each copper wire in the upper layer of the slot, which is: Step 3: Calculate the basic copper loss q′0 of each copper wire in the lower layer of the slot, and we have: Step 4: Calculate the circulation loss q of each copper wire in the upper layer of the slot c ,have: q c =Kc·q0 Where Kc is the circulation loss q c The proportion of DC loss q0 is generally Kc = 0.12 according to the motor design manual; Step 5: Calculate the electrical angular velocity ω: ω=2·π·f n Step 6: Calculate the penetration depth of AC in the stator copper conductor δ ac ,have: Step 7: Calculate the ratio coefficient k of the upper eddy current loss in the slot to the basic copper loss ed ,have: Step 8: Calculate the ratio coefficient k' of the eddy current loss in the lower layer of the slot to the basic copper loss ed ,have: Step 9: Calculate the total eddy current loss Q of each copper wire rod in the upper layer of the slot e ,have: Q e nq0·m1·n1·k ed Step 10: Calculate the ratio coefficient Q′ of the eddy current loss in the lower layer of the slot to the basic copper loss e ,have: Q′ e =q′0·m′1·n1·k′ ed Step 11: Calculate parameter a: Step 12: Calculate parameter b: The loss of the nth strand from the bottom of the slot to the slot opening in the stator slot is q = a·n 2 +b, where a and b are the coefficients of the quadratic function; Step 13: Calculate the eddy current loss q of the top turn copper strand in the slot e ,have: Step 14: Calculate the top turn copper strand loss q in the slot cuT ,have: what cuT =q0+q c +q e Use EXCEL language to calculate the basic copper loss q0 recorded in step 2 and the circulation loss q of each copper wire in the upper layer of the slot recorded in step 4. c Calculation formula, the ratio coefficient k of the upper eddy current loss in the slot recorded in step 7 to the basic copper loss ed Calculation formula, calculation formula for parameter a in step 11, calculation formula for parameter b in step 12, eddy current loss q of the top turn copper strand in the slot recorded in step 13 e The calculation formula and the top turn copper strand loss q recorded in step 14 cuT Calculation formula, prepare table cooling stator generator top turn copper wire loss automatic calculation EXCEL file, the stator upper copper wire height a cu1 , stator lower layer strand height a′ cu1 , stator strand width b cu1 , the number of rows of strands in each bar-shaped conductor on the upper layer of the stator m1, the number of rows of strands in each bar-shaped conductor on the lower layer of the stator m′1, the number of columns of stator strands n1, the frequency of the alternating current in the stator winding f n , stator copper conductor conductivity σ at 75°C, stator current I n , the number of stator winding parallel branches a1, the length of the stator core l t After the magnetic permeability μ of copper is input into the automatic calculation EXCEL file of the top turn copper wire loss of the surface-cooled stator generator, the top turn copper wire loss q of the surface-cooled stator generator is automatically calculated. cuT .

2. The method for conveniently calculating the top turn copper wire loss of a cold stator generator according to claim 1 is characterized in that: The implementation principle is as follows: The stator slot of the surface-cooled generator of the analysis model has one upper layer and one lower layer wire bar in the slot, and each wire bar has two rows of solid copper strands; in the upper layer wire bar near the slot, taking the left row of copper wires as an example, from the bottom of the slot to the number of slots, the strands are numbered 1, 2...m1; in the lower layer wire bar near the bottom of the slot, taking the left row of copper wires as an example, from the bottom of the slot to the number of slots, the strands are numbered 1, 2...m′1; due to the transposition structure between the solid strands in the wire bar, the top turn solid copper strands in the left row of the wire bar are connected at the top center of the wire bar, and the strands are numbered m1 for the upper layer wire bar and m′1 for the lower layer wire bar; Losses in the stator strands, including DC losses, circulating losses, and eddy current losses; For the lower layer of wire bars near the bottom of the stator slot, the loss q′ of the nth strand is counted from the bottom of the slot to the slot mouth. n for: q′ n =a·n 2 +b——(I) For the upper layer of wire bars near the slot opening in the stator slot, the loss q of the nth strand is calculated from the slot bottom to the slot opening. n for: q n =a·n 2 +b+Δ——(II) Where a and b are the coefficients of the quadratic function; Δ is the difference between the loss of the first strand of the upper wire bar closest to the bottom of the slot and the loss of the first strand of the lower wire bar closest to the bottom of the slot; The losses of the strands 1, 2···m′1 in the lower layer of the stator slot near the bottom are accumulated, and the total loss of the lower layer is obtained as follows: The losses of the strands 1, 2, ···m1 in the upper layer of the stator slot near the slot opening are accumulated, and the total loss of the upper layer is obtained as follows: Combining equations (I) to (IV) and the distribution characteristics of the leakage flux of the upper and lower layers of the stator slot, the coefficients a and b of the quadratic function are solved as the expressions of the coefficients a and b in step 11 and step 12; based on this, the calculation formula for the eddy current loss of the top turn copper wire in the stator slot is obtained as q in step 13 e The total loss of the top-turn strand is then accumulated with the DC loss and circulating current loss.

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