A correction method for short-distance coefficient of fractional-slot concentrated winding

Abstract

The present invention relates to the technical field of stator winding design of AC motors, and in particular to a correction method for the short-distance coefficient of a fractional slot concentrated winding, the correction method comprising the following steps: determining the mechanical angle difference between the first layer of conductors and the center line of the winding according to the structural parameters of the stator and the stator winding; determining the layering coefficient of the v-pole motor winding according to the mechanical angle difference between the first layer of conductors and the center line of the winding and the total number of coil winding layers; determining the concentration coefficient according to the structural parameters of the stator; and correcting the short-distance coefficient corresponding to the v-pole harmonic according to the concentration coefficient and the layering coefficient of the v-pole motor winding. The problem that the short-distance coefficient of the fractional slot concentrated winding is inaccurately calculated in the prior art will lead to more magnetomotive force harmonics.

Description

Technical Field

[0001] The invention relates to the technical field of AC motor stator winding design, and in particular to a method for correcting a short-distance coefficient of a fractional slot concentrated winding. Background Art

[0002] Conventional integer slot motors usually have double-layer windings that are layered up and down. During the motor design process, when calculating the winding coefficient, it is generally assumed that the center line of the winding coincides with the center line of the slot. Unlike conventional integer slot motors, for axial-radial hybrid flux permanent magnet motors that use fractional slot concentrated windings, since the windings are layered left and right instead of up and down during winding, the center line of the winding element edge is not in the center of the slot, but in the center of the multi-turn winding, which is the concentration effect. The concentration effect is ubiquitous in motor windings, but the effects caused in different situations need to be discussed separately. For integer slot windings, the upper and lower element edges of the windings span multiple stator teeth, θ y and θ′ y The difference between θ and θ is a small proportion of the total pitch and can be ignored. However, for the fractional slot concentrated winding with a pitch of 1, θ y and θ′ y The difference between them accounts for a large proportion of the total pitch, and the fractional-slot concentrated winding has a large number of pole pairs. The mechanical angle difference caused by the concentration effect multiplied by the number of rotor pole pairs will lead to a larger electrical angle difference, which cannot be ignored when designing to reduce winding harmonics.

[0003] At the same time, since the windings are arranged in layers in the stator slots, there is a θ la The angular difference is the stratification effect of the winding. The stratification effect is common in motor windings and can generally be ignored in integer slot windings. However, due to the large number of pole pairs in fractional slot concentrated windings, θ la The electrical angle corresponding to the mechanical angle is large, so special consideration is required when considering reducing winding harmonics.

[0004] To solve the above problems, a Chinese patent with publication number CN113849775A discloses a method for calculating the distribution factor of a fractional-slot concentrated winding unit motor. The invention introduces a normalized ordered pair of slot-pole matching, analogizes any unit motor winding to a basic unit motor winding arrangement, so that the unit motor winding arrangement has a regular concentrated distribution feature, and then uniformly calculates its distribution factor.

[0005] However, this method is inaccurate in calculating the short-distance coefficient of the fractional-slot concentrated winding, which will lead to more magnetomotive force harmonics. Summary of the invention

[0006] In view of the defects existing in the prior art, the purpose of the present invention is to provide a method for correcting the short-pitch coefficient of fractional-slot concentrated windings, which can solve the problem that the short-pitch coefficient of fractional-slot concentrated windings is inaccurately calculated in the prior art, resulting in more magnetomotive force harmonics.

[0007] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0008] The present invention provides a method for correcting a short-distance coefficient of a fractional-slot concentrated winding, comprising the following steps:

[0009] According to the structural parameters of the stator and the stator winding, the mechanical angle difference between the i-th layer of conductor and the center line of the winding is determined;

[0010] Determine the layering coefficient of the v-pole motor winding according to the mechanical angle difference between the i-th layer of conductor and the center line of the winding and the total number of layers of the coil winding;

[0011] Determine the concentration factor based on the structural parameters of the stator;

[0012] According to the concentration factor and the layering factor of the v-pole motor winding, the short-distance factor corresponding to the v-pole harmonic is corrected.

[0013] In some optional solutions, the step of determining the mechanical angle difference between the i-th layer of conductor and the center line of the winding according to the structural parameters of the stator and the stator winding includes:

[0014] According to the thickness of one side of a single coil, determine the arc at the average radius of the stator slot;

[0015] The mechanical angle difference between the i-th layer of conductor and the center line of the winding is determined according to the arc at the average radius of the stator slot and the total number of layers of coil winding.

[0016] In some optional solutions, determining the mechanical angle difference between the i-th layer of conductor and the center line of the winding according to the arc at the average radius of the stator slot and the total number of layers of coil winding includes:

[0017] According to the formula Determine the mechanical angle difference θ between the i-th layer of wire and the center line of the winding i , where l a is the total number of coil winding layers, θ la is the arc angle at the mean radius of the stator slot.

[0018] In some optional solutions, the step of determining the layering coefficient of the v-pole motor winding according to the mechanical angle difference between the i-th layer of wire and the winding center line and the total number of coil winding layers includes:

[0019] According to the formula Determine the layering factor k of the v-pole motor windinglav ;

[0020] Among them, θ i is the mechanical angle difference between the i-th layer conductor and the winding center line, l a is the total number of coil winding layers, and v is the number of magnetic pole pairs.

[0021] In some optional solutions, the concentration factor is determined according to the structural parameters of the stator, including:

[0022] Determine the slot width coefficient based on the arc occupied by the motor slot width at the average radius and the number of motor slots;

[0023] Determine the concentration factor based on the slot width factor.

[0024] In some optional solutions, the slot width coefficient is determined according to the arc occupied by the motor slot width at the average radius and the number of motor slots, including:

[0025] According to the formula Determine the slot width factor w s ;

[0026] Where z is the number of motor slots, θ s It is the arc occupied by the motor slot width at the average radius.

[0027] In some optional solutions, the concentration factor is determined according to the slot width coefficient, including:

[0028] According to the formula Determine the concentration factor k cs , where w s is the slot width coefficient.

[0029] In some optional solutions, the correction of the short-distance coefficient corresponding to the pole-to-pole harmonic according to the concentration factor and the layering factor of the v-pole-to-pole motor winding includes:

[0030] According to the formula Corrected short-distance coefficient k corresponding to the opposite harmonic yv ;

[0031] Among them, k lav is the layering coefficient of the v-pole motor winding, v is the number of magnetic poles, k cs is the concentration coefficient, θ yis the mechanical arc difference between the two slot midlines. Compared with the prior art, the advantages of the present invention are: fully considering the influence of the winding stratification effect and concentration effect on the short-distance coefficient, and correcting the short-distance coefficient by calculating the stratification coefficient and concentration coefficient of the v-pole motor winding. The number of pole pairs of the main wave of the magnetomotive force can be determined according to the corrected short-distance coefficient, and the motor stator parameters can be designed to weaken the magnetomotive force harmonics of the specified order, thereby improving the torque quality and improving the overall operating efficiency of the motor. It is not only applicable to fractional slot concentrated winding motors, but also a universal design method applicable to all motors with non-negligible stratification effect and concentration effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 It is a flow chart of a method for correcting the short-pitch coefficient of a fractional-slot concentrated winding in an embodiment of the present invention.

[0034] Figure 2 Schematic diagram of the left and right layered concentrated winding with fractional slots in an embodiment of the present invention;

[0035] Figure 3 Schematic diagram of the distribution of conductor vectors in different layers in an embodiment of the present invention;

[0036] Figure 4 A schematic diagram of the distribution of conductor vectors in different layers in an embodiment of the present invention;

[0037] Figure 5 It is a schematic diagram of the comparison before and after the short-distance coefficient is corrected in an embodiment of the present invention; DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0039] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0040] The stratification effect is the phenomenon that the inner and outer windings have an angle difference when the windings are arranged in layers in the stator slots; the concentration effect is the phenomenon that the center line of the concentrated winding element deviates from the center of the slot, resulting in the short pitch angle being unequal to the slot pitch angle. In conventional integer slot motors, the influence of the two effects is small, but they cannot be ignored in fractional slot concentrated winding motors. In order to obtain an accurate short pitch coefficient, it is necessary to calculate the stratification coefficient and concentration coefficient of the v-pole motor winding and correct it.

[0041] Figure 1 FIG. 1 is a flow chart of a method for correcting the short-distance coefficient of a fractional-slot concentrated winding in an embodiment of the present invention. Figure 1 As shown, the present invention provides a method for correcting the short-distance coefficient of a fractional-slot concentrated winding, comprising:

[0042] S1: Determine the mechanical angle difference between the i-th layer of conductor and the center line of the winding according to the structural parameters of the stator and the stator winding.

[0043] like Figure 3 As shown, the coil is wound with wire l a The vector distribution corresponding to the conductors of different layers is drawn. The vectors corresponding to each layer of conductors are numbered 1 to 1 from near to far in the direction away from the stator teeth. a , angle θ i It is the mechanical angle difference between the i-th layer conductor and the center line of the winding.

[0044] In some optional embodiments, step S1 specifically includes:

[0045] S11: Determine the curvature of the stator slot at the average radius according to the single-side thickness of a single coil.

[0046] like Figure 2 As shown, in this example, the thickness of a single coil is converted to the arc θ at the average radius of the stator slot. la .

[0047] S12: Determine the mechanical angle difference between the i-th layer of conductor and the center line of the winding according to the arc at the average radius of the stator slot and the total number of layers of coil winding.

[0048] In this embodiment, according to the formula Determine the mechanical angle difference θ between the i-th layer of wire and the center line of the winding i , where l a is the total number of coil winding layers, θ la is the arc angle at the mean radius of the stator slot.

[0049] S2: Determine the layering coefficient of the v-pole motor winding according to the mechanical angle difference between the i-th layer of wire and the center line of the winding and the total number of layers of the coil winding.

[0050] In some optional embodiments, according to the formula Determine the layering factor k of the v-pole motor winding lav ,v is the layering factor k of the pole-to-pole motor winding lav Used to represent the influence of layering effect on conductor vector superposition.

[0051] Among them, θ i is the mechanical angle difference between the i-th layer conductor and the winding center line, l a is the total number of coil winding layers, and v is the number of magnetic pole pairs.

[0052] S3: Determine the concentration factor based on the structural parameters of the stator.

[0053] In some optional embodiments, step S3 specifically includes:

[0054] S31: Determine the slot width coefficient according to the arc occupied by the motor slot width at the average radius and the number of motor slots.

[0055] In this example, according to the formula Determine the slot width factor w s . Slot width factor w s Indicates the ratio of the motor slot width at the average radius to the entire circumference.

[0056] Where z is the number of motor slots, θ s It is the arc occupied by the motor slot width at the average radius.

[0057] S32: Determine the concentration factor k based on the slot width coefficient cs Used to indicate the influence of concentration effect on winding pitch.

[0058] In this example, according to the formula Determine the concentration factor k cs , where w s is the slot width coefficient.

[0059] S4: According to the concentration factor and the layering factor of the v-pole motor winding, correct the short-distance coefficient corresponding to the pole-to-pole harmonic.

[0060] The method is aimed at the fractional slot left and right layered concentrated winding, and takes into account the layering effect and the concentration effect of the fractional slot concentrated winding. In some optional embodiments, step S4 specifically includes:

[0061] According to the formula Corrected short-distance coefficient k corresponding to the opposite harmonic yv ;

[0062] Among them, k lav is the layering coefficient of the v-pole motor winding, v is the number of magnetic poles, k csis the concentration coefficient, θ y It is the difference of mechanical curvature between the center lines of the two slots.

[0063] The present invention will be further described below in conjunction with specific embodiments and accompanying drawings:

[0064] like Figure 4 and Figure 5 As shown, taking a 12-slot motor as an example, the slot width coefficient is 0.5, the number of conductor layers is 8, and the winding layering is as follows Figure 4 As shown. The comparison of short-distance coefficients of different pole pairs before and after correction is calculated. Figure 5 Before correction, the short-distance coefficient reaches its maximum value when the number of pole pairs is 6, and the short-distance coefficients of 5-pole and 7-pole harmonics are both 0.966. After correction, the short-distance coefficient reaches its maximum value when the number of pole pairs is 8, and the short-distance coefficients of 5-pole and 7-pole harmonics are both reduced to 0.813 and 0.937 respectively. From the perspective of short-distance coefficient, 12-slot motors are more suitable for using 7-pole harmonics as the main wave.

[0065] In summary, a fractional slot concentrated winding harmonic reduction design method proposed in the present invention is adopted, and the winding coefficient is corrected by utilizing the stratification effect and the concentration effect, so as to reduce the winding magnetomotive force harmonics, including: using the stratification coefficient to represent the influence of the stratification effect on the superposition of the inner and outer conductor vectors, and using the concentration coefficient to represent the influence of the concentration effect on the change of the winding pitch. By designing the stratification coefficient and the concentration coefficient, the correction of the short-distance coefficient of the fractional slot concentrated winding is realized, and the short-distance coefficient of the fractional slot concentrated winding can be accurately calculated. At the same time, the number of main wave pole pairs can be determined according to the corrected short-distance coefficient, and the stator parameters can be designed to weaken the stator magnetomotive force harmonics of the specified number of pole pairs, thereby improving the torque quality and improving the overall operating efficiency of the motor. It is not only applicable to fractional slot concentrated winding motors, but also a general design method, which is applicable to all motors whose stratification effect and concentration effect cannot be ignored.

[0066] This method can accurately calculate the short-distance coefficient of the fractional slot concentrated winding. At the same time, the main wave pole pairs can be determined according to the corrected short-distance coefficient, and the stator parameters can be designed to weaken the stator magnetomotive force harmonics of the specified pole pairs, thereby improving the torque quality and the overall operating efficiency of the motor. It includes: using the layering coefficient to represent the influence of the layering effect on the superposition of the inner and outer conductor vectors, and using the concentration coefficient to represent the influence of the concentration effect on the change of the winding pitch. By designing the layering coefficient and the concentration coefficient, the correction of the short-distance coefficient of the fractional slot concentrated winding is realized.

[0067] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0068] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for correcting the short-distance coefficient of fractional-slot concentrated windings, characterized in that: The following steps are involved: According to the structural parameters of the stator and stator winding, determine the The mechanical angle difference between the layer conductor and the winding center line, including: According to the thickness of one side of a single coil, determine the arc at the average radius of the stator slot; Determine the arc of the stator slot at the average radius and the total number of coil winding layers. The mechanical angle difference between the layer conductor and the winding center line includes: According to the formula , determine the Mechanical angle difference between the layer conductor and the winding center line ,in, is the total number of coil winding layers, is the arc at the mean radius of the stator slot; According to The mechanical angle difference between the layer conductor and the center line of the winding and the total number of layers of the coil winding determine v The layering factor of the pole motor winding includes: According to the formula ,Sure v Layering factor of the pole motor winding ;in, For the The mechanical angle difference between the layer conductor and the winding center line, is the total number of coil winding layers, v is the number of magnetic pole pairs; According to the structural parameters of the stator, the concentration factor is determined, including: according to the arc occupied by the motor slot width at the average radius and the number of motor slots, the slot width coefficient is determined according to the formula , determine the slot width coefficient ,in, is the number of motor slots, is the arc occupied by the motor slot width at the average radius; According to the slot width coefficient, the concentration factor is determined, including: according to the formula , determine the concentration factor ,in, is the slot width coefficient; According to the concentration coefficient and v The layering coefficient of the pole motor windings and the correction of the short-distance coefficient corresponding to the pole harmonics include: according to the formula , correct the short-distance coefficient corresponding to the opposite pole harmonic ;in, for v The stratification factor of the pole motor winding, v is the number of magnetic pole pairs, is the concentration coefficient, It is the difference in mechanical curvature between the center lines of the two slots.

Images