A method for determining the equivalent slot division ratio of a non-salient pole generator rotor

Abstract

The application discloses a method for determining an equivalent slot division ratio of a non-salient pole generator rotor, and belongs to the technical field of steam turbine generator design. The method is characterized in that shallow slots and equal-depth slots are arranged on both sides of a large tooth of each pole of the rotor, the depth of the shallow slots and the number of turns of the coils are smaller than those of the equal-depth slots, when there are multiple groups of shallow slots, the slot depth and the number of turns increase successively from the large tooth to the equal-depth slots; when there is one group of shallow slots, the equal-depth slot coils are divided into inner and outer two-layer windings based on the number of turns of the shallow slots; when there are multiple groups of shallow slots, the windings are divided layer by layer based on the difference in the number of turns of adjacent slot groups, each layer satisfies equal-turn configuration, winding coefficients of each layer are obtained, the synthetic winding coefficient of the rotor is obtained by synthesis, the equivalent slot division ratio is obtained by backstepping through an equivalent equation, and the technical problems that it is difficult to consider the structural design contradiction between large tooth saturation and magnetic potential distortion when optimizing the number of turns and the slot division number, and it is difficult to directly determine the slot division ratio and the winding coefficient after the slot depth of the rotor is changed are solved, accurate parameter input is provided for magnetic circuit calculation and determination of excitation current.

Description

Technical Field

[0001] This invention relates to the field of steam turbine (including nuclear power) generator design technology, specifically to a method for determining the rotor of a salient pole generator and its slot pitch ratio. Background Technology

[0002] In the field of steam turbine generator technology, the rotor of a salient-pole synchronous generator includes N-pole and S-pole. The rotor slots are typically multiple sets of equal-depth slots, with each set containing an equal number of coil turns. Each set of equal-depth slots includes two slots symmetrically arranged on either side of the large tooth, centered on it. The large tooth structure of the rotor serves as a crucial magnetic circuit channel for the main magnetic flux to cross the air gap, and its magnetic flux density exhibits peak characteristics in magnetic circuit calculations. This characteristic leads to an increase in the magnetomotive force gradient, thus requiring a larger excitation current input to the rotor excitation winding. Therefore, in engineering design, to reduce the excitation current load and control rotor temperature rise, a collaborative design strategy of increasing the number of rotor winding turns and optimizing the number of slot divisions is usually adopted. However, this approach leads to two technical contradictions: firstly, the magnetic cross-sectional area of ​​the large tooth is reduced. Increasing the number of winding turns often requires expanding the slot dimensions or increasing the number of slots, which encroaches on the width or area of ​​the large tooth, resulting in a smaller magnetic cross-sectional area. With a smaller cross-sectional area, the larger teeth are more prone to magnetic saturation, requiring a larger excitation current to drive the magnetic flux, creating a design contradiction. Secondly, the excitation magnetomotive force waveform is distorted. Adjusting the number of turns and slot divisions alters the spatial distribution of the rotor windings, generating additional harmonic components in the originally designed sinusoidal excitation magnetomotive force. Waveform distortion increases additional losses and vibration noise in the generator, affecting electrical performance.

[0003] In existing technology, the "Electromagnetic Calculation Formula for Steam Turbine Generators" (hereinafter referred to as "Electromagnetic Formula (DZ) 28-63") only records the calculation method for winding coefficients of rotors with all equal-depth slots. Because the excitation windings of equal-depth slot rotors are concentrically distributed, the excitation magnetomotive force curve is as follows... Figure 5 The diagram shows a set of stepped waveforms, formed by the superposition of magnetomotive forces generated by the coils in each slot. The large tooth section has no excitation winding, so its magnetomotive force remains constant. If the slot pitch ratio γ is appropriately chosen, the magnetomotive force distribution will closely approximate a sine wave. The formula for calculating the slot pitch ratio γ is: In the formula, This represents the total number of slots on the rotor. This represents the rotor slot division number.

[0004] When analyzing the winding magnetomotive force of a rotor with equal-depth slots, all coils under one pole can be considered as distributed across... The full-pitch coils within the range. Therefore, the winding factor of the equal-depth slot rotor excitation winding is equal to... Distribution coefficient of the excitation winding within the range.

[0005] To quantitatively calculate this distribution coefficient, the vector relationship of the excitation magnetomotive force of the constant-depth slot rotor is as follows: Figure 6 As shown. First, the groove angle is... , In the formula, Let be the number of rotor pole pairs. According to the geometric relationship shown in the diagram, within one pole... The combined magnetomotive force of the distributed coils is , , because: , so: , In the formula, The magnetomotive force vector generated for each slot, R is the value of each slot. The radius of the circumcircle corresponding to vector composition.

[0006] Thus, an extremely inner The resultant magnetomotive force of the condensed coils is , , The distribution coefficient is , The value is also the winding coefficient of the equal-depth slot rotor. The formula for calculating the winding coefficient of the equal-depth slot rotor is: .

[0007] However, the above calculation method is based on the premise that all slots have the same depth and the number of turns in each slot coil is equal. In actual engineering design, if there are rotors with varying slot depths or turns configurations, the above calculation of winding coefficients and analysis of slot pitch ratio γ based on the assumption of equal slot depth will no longer be applicable.

[0008] For example, Chinese patent document CN105391261A discloses a method for determining the rotor and structural parameters of a high-speed salient-pole electrically excited synchronous motor with a sinusoidal air-gap magnetic field distribution. This technical solution involves setting each pole to have 2n teeth, with a large tooth in the middle and n slots on each side. The half-tooth pitch angle α and the number of conductors in each slot are adjusted. The dimensions of each slot are determined based on the maximum slot depth, the number of conductors in each slot, and the wire diameter. Then, the number of conductors in each slot is configured with an unequal turn distribution, ultimately making the excitation magnetomotive force waveform approximate a sinusoidal distribution to reduce harmonic components. This method generally follows the idea of ​​waveform optimization, that is, first assuming an ideal sinusoidal air-gap magnetomotive force, then deducing the winding layout to improve the magnetomotive force waveform. However, this method does not clearly explain how to analyze the rotor winding coefficients and how to determine the slot pitch ratio. There are still theoretical gaps for subsequent magnetic circuit calculations and generator design, making it difficult to determine the final excitation current requirement of the rotor.

[0009] In summary, on the one hand, existing equal-depth slot rotors struggle to balance large tooth saturation and magnetomotive force distortion when optimizing the number of turns and slot number, resulting in a contradiction in structural design; on the other hand, when the rotor slot depth changes, the calculation method in "Electrical Index (DZ) 28-63" is no longer applicable, and CN105391261A does not provide an analytical approach for the winding coefficient and slot ratio in this case.

[0010] Therefore, it is urgent to propose a rotor structure that can improve the magnetomotive force waveform and alleviate large tooth saturation, as well as a method that can directly determine the slot pitch ratio and obtain the winding coefficient for this rotor structure, so as to provide a complete parameter acquisition scheme for subsequent magnetic circuit calculation and excitation current determination. Summary of the Invention

[0011] The purpose of this invention is to solve the above-mentioned problems in the prior art and to provide a method for determining the rotor of a salient pole generator and its equivalent slot pitch ratio. This method effectively solves the structural design contradiction of existing equal-depth slot rotors in optimizing the number of turns and slot pitch, which makes it difficult to balance the large tooth saturation and magnetomotive force distortion. It also addresses the technical problem that existing calculation methods cannot directly determine the slot pitch ratio and winding coefficient after the rotor slot depth changes.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A salient-pole generator rotor includes an N pole and an S pole. Each pole has at least one set of shallow slots and multiple sets of equal-depth slots on both sides of the large tooth. The shallow slots are located between the large tooth and the equal-depth slots. The depth of the shallow slots is less than the depth of the equal-depth slots. All equal-depth slots have the same number of coil turns, and the number of coil turns in any shallow slot is less than the number of coil turns in a single equal-depth slot. When the number of shallow slots is greater than one set, the slot depth and the number of coil turns of each shallow slot increase sequentially from the large tooth to the equal-depth slot.

[0013] When the number of shallow slots is a group, the number of coil turns in a single shallow slot is 50% to 85% of the number of coil turns in a single slot of equal depth.

[0014] When the number of shallow slots is greater than one set, the number of coil turns increases sequentially in either equal or non-equal increments. The number of coil turns in the shallow slot adjacent to the large tooth is 30% to 45% of the number of coil turns in a single equal-depth slot, and the number of coil turns in the shallow slot adjacent to the equal-depth slot is 50% to 90% of the number of coil turns in a single equal-depth slot.

[0015] The number of coil turns in a single equal-depth slot ranges from 7 to 15.

[0016] A method for determining the equivalent slot pitch ratio of a salient-pole generator rotor, when each pole's large tooth has a set of shallow slots and multiple sets of slots of equal depth on both sides, includes the following steps: S1. Along the radial direction of the rotor, using the number of coil turns in the shallow slot as the dividing criterion, divide the coils in the equal-depth slots into outer coils and inner coils, so that the number of turns of the outer coil in each equal-depth slot is equal to the number of turns of the coil in the shallow slot; and take all the coils in the shallow slots and all the outer coils as the outer windings, and take all the inner coils as the inner windings. S2. Based on the total number of rotor slots and the number of rotor pole pairs, and combined with the results of S1, calculate the number of series turns of the outer winding and the number of series turns of the inner winding, respectively. S3. Calculate the slot ratio of the outer winding based on the total number of rotor slots and the number of rotor slot divisions. The slot ratio of the inner winding is calculated based on the total number of rotor slots, the number of rotor slot divisions, and the number of rotor pole pairs. ; S4. Based on the slot pitch ratio of the outer winding. Calculate the winding factor of the outer winding based on the slot pitch ratio of the inner winding. Calculate the winding factor of the inner winding; S5. Based on the results of S2 and S4, calculate the combined winding coefficient of the rotor; S6. Establish the equivalent equation based on the composite winding coefficients, and calculate the equivalent slot pitch ratio of the rotor using the approximation iterative method. .

[0017] In step S2, the number of turns in series for the outer winding and the inner winding is calculated using the following formulas: , , In the formula, The number of turns in series for the outer winding coil. This refers to the number of turns in series of the inner winding coil. The number of coil turns within a single shallow slot. The number of coil turns within a single slot of equal depth. The number of rotor pole pairs, This represents the total number of slots on the rotor.

[0018] In step S3, the slot pitch ratio of the outer winding is... Slot pitch ratio of inner winding Calculate using the following formulas respectively: , , In the formula, This represents the rotor slot division number.

[0019] In step S4, the winding coefficients of the outer and inner windings are calculated according to the following formulas: , , In the formula, The winding factor of the outer winding. This represents the winding coefficient of the inner winding.

[0020] In step S5, the formula for calculating the composite winding coefficient of the rotor is as follows: , In the formula, is the composite winding coefficient of the rotor.

[0021] In step S6, the equivalent equation is: .

[0022] A method for determining the equivalent slot pitch ratio of a salient-pole generator rotor, when multiple sets of shallow slots and multiple sets of equal-depth slots are provided on both sides of the large tooth of each pole, includes the following steps: S1. Based on the slot depth from smallest to largest, the number of coil turns in the slot with the smallest depth is used as the dividing benchmark. Subsequently, the difference in the number of coil turns in the current slot and the previous slot is used as the dividing benchmark to divide the rotor winding radially from the outside to the inside. In each layer of winding, the number of coil turns in each slot is the same; S2. Based on the total number of rotor slots, the number of rotor pole pairs, and the number of coil turns in each slot, calculate the number of coil turns in series for each layer of windings. S3. Calculate the slot pitch ratio of the first layer winding based on the total number of rotor slots and the number of rotor slot pitches. Then, calculate the slot pitch ratio of the second to third layers based on the total number of rotor slots, the number of rotor slot pitches, and the number of rotor pole pairs. Slot pitch ratio of the layer winding; S4. Calculate the winding coefficient of each layer of winding based on the slot pitch ratio of each layer of winding. S5. Based on the results of steps S2 and S4, calculate the combined winding coefficient of the rotor. S6. Establish the equivalent equation based on the composite winding coefficients, and calculate the equivalent slot pitch ratio of the rotor using the approximation iterative method. .

[0023] In step S2, the number of turns in series for each layer of winding is calculated using the following formula: , , , ……, , In the formula, The number of coil turns in each slot, arranged in ascending order of slot depth, is given by: The number of coil turns in the shallower slot adjacent to the slot of equal depth. The number of coil turns within a single slot of equal depth; This refers to the number of coil turns connected in series in each layer of windings along the rotor radially from the outside to the inside. The number of rotor pole pairs, This represents the total number of slots on the rotor.

[0024] In step S3, the slot pitch ratio of each winding layer is calculated according to the following formula: , , , ... , In the formula, They are respectively the first to the second floor. Slot pitch ratio of the layer winding, This represents the rotor slot division number.

[0025] In step S4, the winding factor of each layer of winding is calculated according to the following formula: , , , ……, , In the formula, They are respectively the first to the second floor. The winding factor of the layered winding.

[0026] In step S5, the composite winding coefficient of the rotor is calculated according to the following formula: .

[0027] In step S6, the equivalent equation is: .

[0028] The advantages of using this invention are as follows: 1. The salient-pole generator rotor provided by this invention, by setting at least one set of shallow slots between the large teeth and the equal-depth slots, and making the depth and number of coil turns of the shallow slots smaller than those of the equal-depth slots, and when there are multiple sets of shallow slots, the slot depth and the number of coil turns increase sequentially from the large teeth to the equal-depth slots, thereby reducing the encroachment on the magnetic cross section of the large teeth, alleviating the risk of magnetic saturation of the large teeth, reducing the magnetomotive force gradient in the large teeth region of the rotor, and making the magnetomotive force stepped waveform close to a sine wave, effectively suppressing harmonic components, effectively solving the structural design contradiction of existing equal-depth slot rotors in which it is difficult to balance large teeth saturation and magnetomotive force distortion when optimizing the number of turns and slot divisions, reducing the excitation current load while meeting the excitation ampere-turns required for operation, and effectively controlling the rotor temperature rise.

[0029] 2. The salient pole generator rotor provided by the present invention, when the number of shallow slots is a set, by setting the number of coil turns in a single shallow slot to 50%~85% of the number of coil turns in a single equal-depth slot, reduces the magnetomotive force peak near the large tooth without excessively weakening the magnetomotive force contribution on the large tooth side, thus taking into account both waveform optimization and large tooth saturation.

[0030] 3. The salient pole generator rotor provided by this invention, when the number of shallow slots is greater than one set, increases the number of coil turns of the shallow slots in an equal or non-equal manner, and sets the number of turns of the shallow slot closest to the large tooth to 30%~45% of the number of turns of the equal-depth slot, and sets the number of turns of the shallow slot closest to the equal-depth slot to 50%~90% of the number of turns of the equal-depth slot, so that the magnetomotive force on the large tooth side gradually rises through the shallow slot region and then smoothly transitions to the high-level magnetomotive force in the equal-depth slot region, forming a gentle stepped waveform, avoiding harmonic components caused by sudden changes in magnetomotive force, and taking into account the dual requirements of large tooth saturation suppression and magnetomotive force waveform optimization.

[0031] 4. The salient-pole generator rotor provided by this invention features a coil turn count of 7-15 turns within a single equal-depth slot. This ensures that the generator's excitation ampere-turn requirements are met while balancing slot dimensions and mechanical strength, preventing excessive turns from encroaching on the large tooth cross-sectional area and exacerbating saturation. If the number of turns is less than 7, the magnetomotive force contribution of a single slot is insufficient, requiring an increase in the number of slots or the excitation current to meet the ampere-turn requirements, which in turn encroaches on the large tooth cross-sectional area or increases copper losses. If the number of turns is greater than 15, the slot dimensions are too large, encroaching on the large tooth magnetic cross-section and exacerbating the risk of magnetic saturation. At the same time, increased copper losses lead to a rise in rotor temperature.

[0032] 5. The method for determining the equivalent slot ratio of a salient pole generator rotor provided by this invention, when there is only one set of shallow slots, is based on the difference in the number of coil turns between a single shallow slot and a single equal-depth slot, and considers the influence of the difference in the number of coil turns caused by the shallow slot distribution structure of the rotor on the magnetomotive force distribution. The rotor winding is divided into an outer layer winding and an inner layer winding along the radial direction, so that both the outer layer winding and the inner layer winding meet the equal-turn configuration of each slot. Thus, the winding coefficients of the outer layer winding and the inner layer winding can be calculated separately by combining the winding coefficient calculation method applicable to equal-depth slot rotors in "Electrical Index (DZ) 28-63".

[0033] Similarly, when there are multiple shallow slots, the number of coil turns in the slot with the smallest depth is used as the dividing criterion, and then the difference between the number of coil turns in the current slot and the previous slot is used as the dividing criterion to divide the rotor winding radially from the outside to the inside. Each layer of winding has the same number of coil turns in each slot, which allows the winding coefficient of each layer of winding to be calculated separately using the winding coefficient calculation method applicable to rotors with equal slot depth in "Electrical Index (DZ) 28-63".

[0034] Then, based on the winding coefficient of each layer of winding and the number of turns in series, the composite winding coefficient of the entire rotor is calculated. The composite winding coefficient truly reflects the actual electromagnetic characteristics of the rotor.

[0035] Finally, by back-calculating the synthetic winding coefficients and the equivalent equation, the determined rotor equivalent slot ratio is obtained. Based on the determined equivalent slot ratio, the corresponding equivalent slot number can be further calculated as the input parameter for subsequent magnetic circuit calculation. Then, in conjunction with "Electrical Index (DZ) 28-63", the magnetic circuit analysis is completed, and the required excitation current of the rotor is accurately determined.

[0036] Unlike the waveform optimization approach used in CN105391261A, which first assumes an ideal sinusoidal air-gap magnetomotive force and then reverse-engineers the winding layout, the method of this invention directly starts from the actual winding structure and performs layering, without relying on a preset ideal waveform, thus better aligning with the actual engineering design of the generator rotor. Therefore, the layering method in this invention is reasonable and improves the computational applicability of the rotor in the case of shallow slots.

[0037] Compared to the calculation method in "Electrical Index (DZ) 28-63" which is only applicable to structures with uniformly deep slots, this method effectively solves the technical problem that existing calculation methods cannot directly determine the slot ratio and winding coefficients after the rotor slot depth changes by using layered windings and the combined calculation of the winding coefficients of each layer. This method has a clear theoretical basis for motors, a simple analytical calculation process, and is convenient for the implementation of generator rotor engineering design. Moreover, through calculation and experimental verification and comparison, it can accurately calculate generator rotor parameters, providing reliable theoretical support and calculation feasibility for magnetic circuit analysis of rotor structures with shallow slots, and expanding the application scope of analytical theory of motors. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the rotor having multiple sets of shallow grooves in this invention; Figure 2 This is a schematic diagram of the rotor having a set of shallow slots in this invention; Figure 3 This is a schematic diagram of the outer winding structure when the rotor has a set of shallow slots in this invention; Figure 4 This is a schematic diagram of the inner winding structure when the rotor has a set of shallow slots in this invention; Figure 5 This is a schematic diagram of rotor excitation magnetomotive force distribution in the prior art; Figure 6 This is a schematic diagram of the rotor excitation magnetomotive force vector in the prior art.

[0039] The numbers in the diagram are: 1. Large tooth, 2. Shallow groove, 3. Groove of equal depth, 4. Coil. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0041] Example 1 This embodiment provides a salient-pole generator rotor, which includes N poles and S poles, such as... Figure 1 and Figure 2 As shown, each pole of large tooth 1 has at least one set of shallow grooves 2 and multiple sets of grooves of equal depth on both sides.

[0042] Shallow slot 2 is located between large tooth 1 and equal-depth slot 3. The depth of shallow slot 2 is less than the depth of equal-depth slot 3. The number of coil 4 turns in all equal-depth slots 3 is equal, and the number of coil 4 turns in any shallow slot 2 is less than the number of coil 4 turns in a single equal-depth slot 3. This reduces the magnetomotive force gradient in the large tooth region and makes the magnetomotive force step waveform approach a sine wave, suppressing harmonic components.

[0043] like Figure 1As shown, when the number of shallow slots 2 is greater than one set, the slot depth of each shallow slot 2 and the number of coil turns 4 increase sequentially from the direction of the large tooth 1 to the equal-depth slot 3.

[0044] like Figure 2 As shown, when the number of shallow slots 2 is a group, the number of coil turns in a single shallow slot 2 is 50% to 85% of the number of coil turns in a single equal-depth slot 3. If the calculated number of turns is a decimal, it is rounded to the nearest integer.

[0045] Furthermore, when the number of shallow slots 2 is greater than one set, the number of coil turns 4 increases sequentially in either an equal or non-equal increment manner. The number of coil turns 4 in the shallow slot 2 adjacent to the large tooth is 30%–45% of the number of coil turns 4 in a single equal-depth slot 3, and the number of coil turns 4 in the shallow slot 2 adjacent to the equal-depth slot 3 is 50%–90% of the number of coil turns 4 in a single equal-depth slot 3. If the calculated number of turns is a decimal, it is rounded to the nearest integer. The specific increment method for the number of turns in each shallow slot can be configured using analytical calculation or simulation verification. Whether the increment is equal or non-equal, the goal is to approximate a sine wave in the excitation magnetomotive force waveform.

[0046] Furthermore, the number of coil turns in a single equal-depth slot 3 ranges from 7 to 15.

[0047] In summary, this embodiment reduces the occupancy of the magnetic cross-section of the large tooth 1 by setting shallow slots 2 on both sides of the large tooth 1, and making the depth and number of coil turns of the shallow slots 2 smaller than those of the equal-depth slots 3, thereby mitigating the risk of magnetic saturation of the large tooth. At the same time, the number of turns of each shallow slot 2 increases sequentially from the large tooth 1 to the equal-depth slot 3: 50% to 85% of the number of turns of the equal-depth slot in a single group of shallow slots; and 30% to 45% of the number of coil turns of the coil 4 in a single equal-depth slot 3 in multiple groups of shallow slots. This allows the magnetomotive force on the large tooth side to smoothly transition to the high-level magnetomotive force in the equal-depth slot region after being gradually raised through the shallow slot region, forming a gentle stepped waveform. This avoids harmonic components caused by sudden changes in magnetomotive force, thus meeting the dual requirements of large tooth saturation suppression and magnetomotive force waveform optimization.

[0048] Example 2 This embodiment, based on the rotor structure in Embodiment 1, provides a method for determining the equivalent slot pitch ratio of a salient pole generator rotor.

[0049] Specifically, when each large tooth 1 has a set of shallow grooves 2 and multiple sets of grooves of equal depth on both sides, combined with Figures 2 to 4 Understood, this determination method includes the following steps: S1. Along the radial direction of the rotor, using the number of turns of the coil 4 in the shallow slot 2 as the dividing criterion, divide the coil 4 in the equal-depth slot 3 into outer layer coils and inner layer coils, so that the number of turns of the outer layer coil in each equal-depth slot 3 is equal to the number of turns of the coil in the shallow slot 2; and take all the coils 4 in the shallow slot 2 and all the outer layer coils 4 as outer layer windings, and take all the inner layer coils 4 as inner layer windings.

[0050] Specifically, such as Figures 2 to 4 As shown, the outer winding is represented by all the dark blue dots, denoted as outer winding A; the inner winding is represented by all the purple dots, denoted as inner winding B. This step describes the rotor winding division method under a shallow slot structure.

[0051] S2. Based on the total number of rotor slots and the number of rotor pole pairs, and combined with the results of S1, calculate the number of series turns of the outer winding and the number of series turns of the inner winding, respectively. S3. Calculate the slot ratio of the outer winding based on the total number of rotor slots and the number of rotor slot divisions. The slot ratio of the inner winding is calculated based on the total number of rotor slots, the number of rotor slot divisions, and the number of rotor pole pairs. .

[0052] S4. Based on the slot pitch ratio of the outer winding. Calculate the winding factor of the outer winding based on the slot pitch ratio of the inner winding. Calculate the winding factor of the inner winding.

[0053] S5. Based on the results of S2 and S4, calculate the composite winding coefficient of the rotor. This composite winding coefficient is the actual winding coefficient that cannot be directly calculated from "Electrical Index (DZ) 28-63" under the rotor structure of Example 1.

[0054] S6. Establish the equivalent equation based on the composite winding coefficients, and calculate the equivalent slot pitch ratio of the rotor using the approximation iterative method. .

[0055] Equivalent slot pitch ratio The analytical calculation of the generator magnetic circuit is indispensable, and its accuracy directly affects the accuracy of the generator excitation calculation.

[0056] Subsequently, the rotor equivalent slot pitch ratio was determined based on the rotor. This allows us to calculate the equivalent number of slots required for the rotor. The calculation formula is: .

[0057] Calculated equivalent slot pitch ratio Equivalent slot pitch This can then be used as the input parameter for subsequent magnetic circuit calculations of the rotor structure.

[0058] In summary, this embodiment considers the impact of coil turn differences caused by the shallow slot distribution structure on the magnetomotive force distribution. Based on the difference in coil turn count between a single shallow slot and a single equal-depth slot, the rotor winding is divided into an outer layer winding and an inner layer winding along the radial direction, ensuring that both the outer and inner layer windings satisfy the equal-turn configuration for each slot. This transforms the problem of calculating the rotor winding coefficients containing a set of shallow slots into a problem applicable to solving the winding coefficients of medium-depth slot rotors in existing technologies. Based on this, the final determined rotor equivalent slot ratio is obtained by back-calculating the synthesized winding coefficients obtained in step S5 using the equivalent equation. .

[0059] Furthermore, in step S2, the number of turns in series for the outer winding A and the inner winding B is calculated using the following formulas: , , In the formula, The number of turns in series for the outer winding coil. This refers to the number of turns in series of the inner winding coil. The number of coil turns within a single shallow slot 2. The number of coil turns within a single equal-depth slot 3. The number of rotor pole pairs, Total number of rotor slots This includes all shallow trenches and all trenches of equal depth.

[0060] Furthermore, in step S3, the slot pitch ratio of the outer winding... Slot pitch ratio of inner winding Calculate using the following formulas respectively: , , In the formula, The rotor slot division number is given by the rotor slot layout. The value is known.

[0061] Furthermore, in step S4, the winding coefficients of the outer winding and the inner winding are calculated according to the following formulas: , , In the formula, The winding factor of the outer winding. The winding coefficient of the inner winding is given. Since both the outer and inner windings satisfy the condition of uniform configuration with equal number of turns, they are equivalent to the excitation windings of a conventional equal-depth slot rotor in terms of electromagnetic characteristics. Therefore, in step S4, the winding coefficients of the outer and inner windings can be calculated separately by combining the existing formula for calculating the winding coefficient of an equal-depth slot rotor.

[0062] Furthermore, in step S5, the formula for calculating the composite winding coefficient of the rotor is as follows: , In the formula, is the composite winding coefficient of the rotor.

[0063] Furthermore, in step S6, the equivalent equation is: .

[0064] It should be noted that the approximation iterative method first assumes an equivalent slot pitch ratio. The initial values ​​are substituted into the above equivalent equation to repeatedly approximate the rotor composite winding coefficients. Until the equivalent slot pitch ratio The convergence threshold is met, thus yielding a definite rotor equivalent slot pitch ratio. This process is a well-known mathematical method and will not be elaborated upon here.

[0065] Example 3 Based on the rotor structure of Embodiment 1 and the layering method of Embodiment 2, this embodiment targets a rotor with multiple shallow slots 2, performs winding layering, and determines its equivalent slot pitch ratio.

[0066] like Figure 1 As shown, when multiple sets of shallow grooves 2 and multiple sets of equal-depth grooves 3 are provided on both sides of the large tooth 1 of each pole, the following steps are included: S1. Based on the slot depth from smallest to largest, the number of coil turns in the slot with the smallest depth is used as the dividing benchmark. Subsequently, the difference in the number of coil turns in the current slot and the previous slot is used as the dividing benchmark to divide the rotor winding radially from the outside to the inside. In each layer of winding, the number of coil turns in each slot is the same. (Combined) Figure 1 To understand, different layers of windings are distinguished by different colored dots, and dots of the same color indicate the same layer of windings.

[0067] Specifically, Figure 1 The diagram illustrates the single-sided grooves 2 and 3 of the same depth on the same side of the large tooth 1. Only one 3 of the same depth is shown as an example; the groove structures of the remaining 3 of the same depth are identical. The groove depth and the number of turns of the coil 4 of each shallow groove 2 increase sequentially from the large tooth 1 to the 3 of the same depth.

[0068] The number of coil turns in the slot with the smallest slot depth is used as the dividing criterion: that is, the number of coil turns in a single slot of the first shallow slot 2 is used as the dividing criterion, and the coil 4 of the criterion is taken from all shallow slots 2 and slots of equal depth 3 as the first layer winding, that is, all the dark blue dots on the outermost layer. Subsequently, the difference in the number of coil turns in the current slot and the previous slot is used as the dividing criterion: that is, the difference in the number of coil turns in a single slot of the second group and the first group of shallow slots 2 is used as the dividing criterion. From the remaining coils of the second group and each subsequent group of shallow slots 2 and equal-depth slots 3, coils 4 based on this criterion are taken as the second layer winding, i.e., all the purple dotted portions; and so on, using the difference in the number of coil turns in the current slot and the previous slot as the dividing criterion. Group and No. Using the difference in the number of coil turns within a single slot of group 2 as a reference, starting from the first... From the remaining coils of shallow slot 2 and equal-depth slot 3, take the reference coil 4 as the first... Layer winding, i.e., all the orange dotted parts.

[0069] Finally, the remaining coils 4 in each equal depth groove 3 are used as the first... The innermost layer of windings, represented by the black dots, completes the layering of the rotor windings from the outside in. Each layer of windings has an equal number of turns in each slot, forming an equal-turn configuration.

[0070] S2. Based on the total number of rotor slots, the number of rotor pole pairs, and the number of coil turns in each slot, calculate the number of coil turns in series for each layer of windings. S3. Calculate the slot pitch ratio of the first layer winding based on the total number of rotor slots and the number of rotor slot pitches. Then, calculate the slot pitch ratio of the second to third layers based on the total number of rotor slots, the number of rotor slot pitches, and the number of rotor pole pairs. Slot pitch ratio of the layer winding; S4. Calculate the winding coefficient of each layer of winding based on the slot pitch ratio of each layer of winding. S5. Based on the results of steps S2 and S4, calculate the composite winding coefficient of the rotor; this composite winding coefficient is the actual winding coefficient that cannot be directly calculated from "Electrical Index (DZ) 28-63" under the rotor structure of Example 1.

[0071] S6. Establish the equivalent equation based on the composite winding coefficients, and calculate the equivalent slot pitch ratio of the rotor using the approximation iterative method. .

[0072] Equivalent slot pitch ratio The analytical calculation of the generator magnetic circuit is indispensable, and its accuracy directly affects the accuracy of the generator excitation calculation.

[0073] Subsequently, the rotor equivalent slot pitch ratio was determined based on the rotor. This allows us to calculate the equivalent number of slots required for the rotor. The calculation formula is: .

[0074] Calculated equivalent slot pitch ratio Equivalent slot pitch This can then be used as the input parameter for subsequent magnetic circuit calculations of the rotor structure.

[0075] In summary, this embodiment considers the influence of coil turn number differences caused by multiple shallow slot distribution structures on the magnetomotive force distribution. Based on the structure where the number of turns in multiple shallow slots 2 increases sequentially from the large tooth 1 to the equal-depth slots 3, with the equal-depth slots 3 having the largest number of turns, the rotor winding is divided into radial directions. The winding is layered, ensuring that each layer has an equal number of turns in each slot. This transforms the calculation problem of rotor winding coefficients with multiple shallow slots into a problem applicable to medium-deep slot rotor winding coefficients in existing technologies. Based on this, the determined rotor equivalent slot ratio is finally obtained by back-calculating the composite winding coefficients obtained in step S5 and the equivalent equation. .

[0076] Furthermore, in step S2, the number of turns in series for each layer of winding is calculated using the following formula: , , , ……, , In the formula, The number of coil turns in each slot, arranged in ascending order of slot depth, is given by: The number of coil turns in the shallower slot adjacent to the slot of equal depth. The number of coil turns within a single slot of equal depth; This refers to the number of coil turns connected in series in each layer of windings along the rotor radially from the outside to the inside. The number of rotor pole pairs, This represents the total number of slots on the rotor.

[0077] Furthermore, in step S3, the slot pitch ratio of each winding layer is calculated according to the following formula: , , , ... , In the formula, They are respectively the first to the second floor. Slot pitch ratio of the layer winding, The rotor slot division number is given by the rotor slot layout. The value is known.

[0078] Furthermore, in step S4, the winding coefficient of each layer of winding is calculated according to the following formula: , , , ……, , In the formula, They are respectively the first to the second floor. The winding factor of the layered winding.

[0079] Since each layer of windings satisfies the condition of uniform configuration with equal number of turns, it is equivalent to the excitation winding of a conventional equal-depth slot rotor in terms of electromagnetic characteristics. Therefore, in step S4, the winding coefficient of each layer of windings can be calculated separately by combining the existing equal-depth slot rotor winding coefficient calculation formula.

[0080] Furthermore, in step S5, the composite winding coefficient of the rotor is calculated according to the following formula: .

[0081] Furthermore, in step S6, the equivalent equation is: .

[0082] It should be noted that the approximation iterative method first assumes an equivalent slot pitch ratio. The initial values ​​are substituted into the above equivalent equation to repeatedly approximate the rotor composite winding coefficients. Until the equivalent slot pitch ratio The convergence threshold is met, thus yielding a definite rotor equivalent slot pitch ratio. This process is a well-known mathematical method and will not be elaborated upon here.

[0083] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All features or steps in the disclosed methods or processes may be combined in any way, except for mutually exclusive features and / or steps.

Claims

1. A salient-pole generator rotor, comprising an N pole and a S pole, characterized in that: Each pole has at least one set of shallow grooves (2) and multiple sets of equal-depth grooves (3) on both sides of the large tooth (1). The shallow grooves (2) are located between the large tooth (1) and the equal-depth grooves (3). The depth of the shallow grooves (2) is less than the depth of the equal-depth grooves (3). The number of coil turns in all equal-depth grooves (3) is equal, and the number of coil turns in any shallow groove (2) is less than the number of coil turns in a single equal-depth groove (3). When the number of shallow grooves (2) is greater than one set, the groove depth and the number of coil turns of each shallow groove (2) increase sequentially from the large tooth (1) to the equal-depth groove (3).

2. The salient-pole generator rotor according to claim 1, characterized in that: When the number of shallow slots (2) is a set, the number of coil turns in a single shallow slot (2) is 50% to 85% of the number of coil turns in a single equal-depth slot (3).

3. The salient-pole generator rotor according to claim 1, characterized in that: When the number of shallow slots (2) is greater than one set, the number of coil turns increases sequentially in either equal or non-equal increments. The number of coil turns in the shallow slot (2) adjacent to the large tooth is 30% to 45% of the number of coil turns in a single equal-depth slot (3), and the number of coil turns in the shallow slot (2) adjacent to the equal-depth slot (3) is 50% to 90% of the number of coil turns in a single equal-depth slot (3).

4. A salient-pole generator rotor according to claim 1, characterized in that: The number of coil turns in a single equal-depth groove (3) ranges from 7 to 15.

5. A method for determining the equivalent slot ratio of a salient-pole generator rotor according to any one of claims 1-4, characterized in that: When each pole's large tooth (1) has a set of shallow grooves (2) and multiple sets of grooves of equal depth (3) on both sides, the following steps are included: S1. Along the radial direction of the rotor, using the number of coil turns in the shallow slot (2) as the dividing criterion, divide the coil in the equal-depth slot (3) into outer coil and inner coil, so that the number of turns of the outer coil in each equal-depth slot (3) is equal to the number of turns of the coil in the shallow slot (2); and take all the coils in the shallow slot (2) and all the outer coils as outer windings, and take all the inner coils as inner windings. S2. Based on the total number of rotor slots and the number of rotor pole pairs, and combined with the results of S1, calculate the number of series turns of the outer winding and the number of series turns of the inner winding, respectively. S3. Calculate the slot ratio of the outer winding based on the total number of rotor slots and the number of rotor slot divisions. The slot ratio of the inner winding is calculated based on the total number of rotor slots, the number of rotor slot divisions, and the number of rotor pole pairs. ; S4. Based on the slot pitch ratio of the outer winding. Calculate the winding factor of the outer winding based on the slot pitch ratio of the inner winding. Calculate the winding factor of the inner winding; S5. Based on the results of S2 and S4, calculate the combined winding coefficient of the rotor; S6. Establish the equivalent equation based on the composite winding coefficients, and calculate the equivalent slot pitch ratio of the rotor using the approximation iterative method. .

6. The method for determining the equivalent slot ratio of a salient-pole generator rotor according to claim 5, characterized in that: In step S2, the number of turns in series for the outer winding and the inner winding is calculated using the following formulas: ， ， In the formula, The number of turns in series for the outer winding coil. The number of turns in series in the inner winding coil; The number of coil turns within a single shallow slot. The number of coil turns within a single slot of equal depth. The number of rotor pole pairs, This represents the total number of slots on the rotor.

7. The method for determining the equivalent slot ratio of a salient-pole generator rotor according to claim 6, characterized in that: In step S3, the slot pitch ratio of the outer winding is... Slot pitch ratio of inner winding Calculate using the following formulas respectively: ， ， In the formula, This represents the rotor slot division number.

8. The method for determining the equivalent slot ratio of a salient-pole generator rotor according to claim 7, characterized in that: In step S4, the winding coefficients of the outer and inner windings are calculated according to the following formulas: ， ， In the formula, The winding factor of the outer winding. This represents the winding coefficient of the inner winding.

9. The method for determining the equivalent slot ratio of a salient-pole generator rotor according to claim 8, characterized in that: In step S5, the formula for calculating the composite winding coefficient of the rotor is as follows: ， In the formula, is the composite winding coefficient of the rotor.

10. The method for determining the equivalent slot ratio of a salient-pole generator rotor according to claim 9, characterized in that: In step S6, the equivalent equation is: 。 11. A method for determining the equivalent slot ratio of a salient-pole generator rotor according to any one of claims 1-4, characterized in that: When multiple shallow grooves (2) and multiple grooves of equal depth (3) are provided on both sides of the large tooth (1) of each pole, the following steps are included: S1. Based on the slot depth from smallest to largest, the number of coil turns in the slot with the smallest depth is used as the dividing benchmark. Subsequently, the difference in the number of coil turns in the current slot and the previous slot is used as the dividing benchmark to divide the rotor winding radially from the outside to the inside. In each layer of winding, the number of coil turns in each slot is the same; S2. Based on the total number of rotor slots, the number of rotor pole pairs, and the number of coil turns in each slot, calculate the number of coil turns in series for each layer of windings. S3. Calculate the slot pitch ratio of the first layer winding based on the total number of rotor slots and the number of rotor slot pitches. Then, calculate the slot pitch ratio of the second to third layers based on the total number of rotor slots, the number of rotor slot pitches, and the number of rotor pole pairs. Slot pitch ratio of the layer winding; S4. Calculate the winding coefficient of each layer of winding based on the slot pitch ratio of each layer of winding. S5. Based on the results of steps S2 and S4, calculate the combined winding coefficient of the rotor. S6. Establish the equivalent equation based on the composite winding coefficients, and calculate the equivalent slot pitch ratio of the rotor using the approximation iterative method. .

12. The method for determining the equivalent slot ratio of a salient-pole generator rotor according to claim 11, characterized in that: In step S2, the number of turns in series for each layer of winding is calculated using the following formula: ， ， ， ……， ， In the formula, The number of coil turns in each slot, arranged in ascending order of slot depth, is given by: The number of coil turns in the shallower slot adjacent to the slot of equal depth. The number of coil turns within a single slot of equal depth; This refers to the number of coil turns connected in series in each layer of windings along the rotor radially from the outside to the inside. The number of rotor pole pairs, This represents the total number of slots on the rotor.

13. The method for determining the equivalent slot ratio of a salient-pole generator rotor according to claim 12, characterized in that: In step S3, the slot pitch ratio of each winding layer is calculated according to the following formula: ， ， ， …… ， In the formula, They are respectively the first to the second floor. Slot pitch ratio of the layer winding, This represents the rotor slot division number.

14. The method for determining the equivalent slot ratio of a salient-pole generator rotor according to claim 13, characterized in that: In step S4, the winding factor of each layer of winding is calculated according to the following formula: ， ， ， ……， ， In the formula, They are respectively the first to the second floor. The winding factor of the layered winding.

15. The method for determining the equivalent slot ratio of a salient-pole generator rotor according to claim 14, characterized in that: In step S5, the composite winding coefficient of the rotor is calculated according to the following formula: 。 16. The method for determining the equivalent slot ratio of a salient-pole generator rotor according to claim 15, characterized in that: In step S6, the equivalent equation is: 。

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