Structure of a hairpin-shaped flat wire winding and permanent magnet synchronous motor using the same

Abstract

The present invention relates to a structure of a hairpin-shaped flat wire winding and a permanent magnet synchronous motor using the same. The stator of the motor uses parallel teeth, and the slot width of the stator slot gradually increases from the inner side to the outer side. The width of the cross-section of the hairpin-shaped flat wire conductor in each stator slot remains unchanged, denoted as w, and the length increases as the slot width of the stator slot increases. There are n layers of flat wire conductors arranged radially in each stator slot, and m flat wire conductors are arranged circumferentially in each stator slot, where m≥1. There are a total of nm flat wire conductors in one stator slot. The ratio of the sum of the lengths of the cross-sections of the flat wire conductors in each layer to the slot width of the stator slot is the same, denoted as c, and the sizes of the flat wire conductors in the same layer are the same. The stator slot area is fully utilized, and under the same current excitation, the motor in the present invention has a higher electromagnetic torque compared to a motor using non-parallel teeth.

Description

Technical Field

[0001] The present invention relates to the technical field of motor windings, and more particularly to a structure of a hairpin flat wire motor winding and a permanent magnet synchronous motor using the same. Background Art

[0002] With the continuous development of new energy vehicles, higher and higher requirements are put forward for the torque performance and efficiency of motors. How to reduce the losses of a flat wire permanent magnet synchronous motor while improving its torque capacity has received more and more extensive attention. The losses of a permanent magnet synchronous motor mainly include copper loss, iron loss, permanent magnet eddy current loss, etc. Generally speaking, the copper loss accounts for the largest proportion.

[0003] The copper loss of a flat wire permanent magnet synchronous motor is the Joule loss generated by the winding passing through current. The DC copper loss generated under the action of direct current is related to the wire resistance and the current passed through. Under the action of alternating current, due to the proximity effect and skin effect, at high frequencies, the AC copper loss of the motor will be much greater than the DC copper loss. When the motor operates at a lower frequency, the influence of these two effects is very small, and it can be approximately considered that the AC loss at low frequencies is equal to the DC loss.

[0004] Generally, a vehicle-used flat wire permanent magnet synchronous motor usually operates at a relatively low speed of 1500 r / min or 3000 r / min. At this time, the operating frequency of the motor is low, and the AC copper loss of the motor is approximately equal to the DC copper loss. When the motor operates at a higher speed, since the hairpin flat wire winding is adopted in the flat wire permanent magnet synchronous motor, the cross-sectional area of the flat wire conductor is large, and the influence of the proximity effect and skin effect is more obvious. At this time, the AC copper loss will increase significantly compared with that at low frequencies. Therefore, if the AC copper loss of the flat wire motor under different working conditions can be reduced, the efficiency of the flat wire permanent magnet synchronous motor can be effectively improved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a structure of a hairpin flat wire winding and a permanent magnet synchronous motor using the same, so as to reduce the copper loss of the motor and improve the torque performance of the motor.

[0006] The purpose of the present invention is to propose a structure of a hairpin flat wire winding and a permanent magnet synchronous motor using the same to solve the technical problems in the above background art. The stator part of the motor uses parallel teeth, and the winding uses a hairpin flat wire winding, and the winding size changes with the change of the slot width of the stator slot, so as to increase the effective conductive area under the same current, improve the output torque and reduce the DC copper loss at the same time. At the same time, the transposition technology of Litz wire is applied to the hairpin flat wire winding to exchange the positions of the flat wire conductors in the stator slot to suppress the proximity effect and skin effect, so as to achieve the purpose of reducing the AC copper loss.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a structure of a hairpin flat wire winding. The stator of the motor adopts parallel teeth, and the width of the stator slot gradually increases from the inner side to the outer side. The width of the cross-section of the hairpin flat wire conductor in each stator slot remains unchanged, denoted as w, and the length increases as the width of the stator slot increases;

[0009] Let the number of layers of flat wire conductors in the radial direction in each stator slot be n, and the number of flat wire conductors in the circumferential direction be m, m≥1. The sizes of the flat wire conductors in the same layer are the same, and the ratio of the sum of the lengths of the cross-sections of the flat wire conductors in each layer to the width of the stator slot is the same, denoted as c; the depth of the stator slot is h, the radial distance between adjacent two layers of flat wire conductors is ε1, the circumferential distance between adjacent two flat wire conductors on each layer is ε2, the width of the stator slot opening is l1, the width of the stator slot bottom is l2. Denote the first layer of flat wire conductors closest to the stator slot opening in the stator slot as Z1, and the sum of the cross-section lengths of the m flat wire conductors on the first layer is The cross-section length of each flat wire conductor on the first layer is b1, and the k-th layer of flat wire conductors counted from the stator slot opening to the stator slot bottom direction is denoted as Z k , 1≤k≤n, and the sum of the cross-section lengths of the m flat wire conductors on the k-th layer is The cross-section length of each flat wire conductor on the k-th layer is b k , and the width of the slot where the outermost layer of flat wire conductors is located is l3.

[0010] Then, the length and width of the cross-section of the k-th layer of flat wire conductors in the stator slot are described and restricted by the following variables

[0011]

[0012] where Δ is the difference in length between adjacent two layers of flat wire conductors.

[0013] Before assembling the motor winding, first process the flat wire windings with various cross-sectional area sizes externally, and then insert them into the stator slots. Set the position of each flat wire conductor in each stator slot corresponding to the position in the stator slot after crossing one pitch to achieve the purpose of wire transposition, and then weld the ends of two corresponding hairpin flat wire conductors together.

[0014] The wire transposition method adopts the transposition technology of Litz wire. Determine the number of pole pairs and the number of stator slots of the motor. Adopt the integral pitch lap winding, then the pitch is the number of stator slots divided by twice the number of pole pairs; name any slot on the stator as slot 1, and then name them as slot 2, slot 3,... in the clockwise direction in turn; then the stator slots spanned by the A-phase winding are slot 1, slot 2, slot 7, and slot 8. Each slot contains nm flat wire conductors. Name each flat wire conductor in slot 1 as A 1+ ,A 2+ ,…,Anm+ , where \(n_m = 1, 2, \cdots\), \(n_m\) is an integer multiple of 4, and each flat wire conductor in slot 2 is named A 1- , A 2- , …, A nm- , and each flat wire conductor in slot 7 is named Each flat wire conductor in slot 8 is named where the plus sign indicates that the flat wire conductor penetrates into the stator slot, and the minus sign indicates that the flat wire conductor penetrates out of the stator slot;

[0015] After the flat wire conductor penetrates into slot 1, it should penetrate out of slot 7. The flat wire conductor that penetrates out of slot 7 should penetrate into slot 2, and the flat wire conductor that penetrates into slot 2 should penetrate out of slot 8. Taking four adjacent flat wire conductors as a group, when penetrating into slot 7, the two flat wire conductors on the same side of adjacent two layers in different slots exchange positions along the diagonal, and the other two flat wire conductors on the same side do not exchange positions.

[0016] In a second aspect, the present invention provides a permanent magnet synchronous motor, and the permanent magnet synchronous motor uses the structure of the hairpin flat wire winding described above.

[0017] The permanent magnet synchronous motor includes a stator core, a rotor core, permanent magnets, and a rotating shaft. Among them, the tooth part of the stator core is a parallel tooth, and the stator core is formed by axially laminating and fastening a number of identical amorphous alloy thin sheets with uniform internal settings in the same state; the rotor core is formed by axially laminating and fastening a number of identical silicon steel thin sheets with uniform internal settings in the same state; the hairpin flat wire winding is processed externally and then inserted into the stator slots. According to the position of each flat wire conductor in the stator slot corresponding to the stator slot after spanning a pitch, the ends of the flat wire conductors are welded at the other end; the rotor core and the permanent magnets form a rotor structure, a rotating shaft mounting hole is provided in the center of the rotor structure, the rotor structure is fixed on the rotating shaft through the rotating shaft mounting hole, the stator core is sleeved on the outer periphery of the rotor structure, and there is an air gap between the stator core and the rotor structure, and the stator core is fixed by a motor base, and the length of the stator core is the same as the length of the rotor structure.

[0018] Apply the transposition technology of Litz wire to the hairpin flat wire winding, exchange the positions of the hairpin flat wire conductors in the stator slots, suppress the proximity effect and skin effect, effectively reduce the AC copper loss of the motor when working at high frequencies, and at the same time improve the electromagnetic torque at low and high frequencies.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. In traditional flat wire permanent magnet motors, the stator teeth are non-parallel teeth. Compared with parallel teeth, the area of the stator slots is smaller, which means a smaller effective conductive area, thus affecting the torque performance of the motor. The permanent magnet synchronous motor of the present invention adopts parallel teeth. At the same time, the cross-sectional area of each flat wire conductor in the stator slot changes with the change of the slot width of the stator slot, making full use of the stator slot area. Under the same current excitation, the motor in the present invention has a higher electromagnetic torque compared with the motor using non-parallel teeth.

[0021] 2. In the present invention, the cross-sectional area of the flat wire conductor in the stator slot changes with the change of the slot width. From the slot opening to the slot bottom, the cross-sectional area of the flat wire conductor gradually increases. Compared with the traditional flat wire winding with the same size of flat wire conductors in each slot, its DC resistance is smaller, effectively reducing the DC copper loss when the flat wire permanent magnet synchronous motor operates at low frequencies.

[0022] 3. Due to the large cross-sectional area, when the hairpin flat wire winding operates at high frequencies, it will generate a high AC copper loss under the influence of the proximity effect and the skin effect. The present invention applies the transposition technology of Litz wire to the hairpin flat wire winding, exchanges the positions of the hairpin flat wire conductors in the stator slot, suppresses the proximity effect and the skin effect, effectively reducing the AC copper loss when the motor operates at high frequencies, and at the same time improving the electromagnetic torque. Description of the Drawings

[0023] Figure 1 The figure shows the cross-sectional dimension marking diagram of the hairpin flat wire winding in the parallel tooth stator slot in Embodiment 1;

[0024] Figure 2 The figure shows the distribution schematic diagram of each flat wire conductor included in the A-phase winding of a pair of poles of the parallel tooth hairpin flat wire winding permanent magnet synchronous motor in Embodiment 1;

[0025] Figure 3 The figure shows the finite element model diagram established in the finite element analysis software (Ansys) for the parallel tooth hairpin flat wire winding permanent magnet synchronous motor in Embodiment 1;

[0026] Figure 4 The figure shows the finite element model diagram established in the finite element analysis software (Ansys) for the traditional permanent magnet synchronous motor with non-parallel tooth hairpin flat wire winding;

[0027] Figure 5 The figure shows the torque comparison schematic diagram between the parallel tooth hairpin flat wire winding permanent magnet synchronous motor (Curve A) in Embodiment 1 and the traditional permanent magnet synchronous motor with non-parallel tooth hairpin flat wire winding (Curve B).

[0028] Figure 6Shown are the low-frequency winding copper losses when the parallel-tooth hairpin flat wire winding permanent magnet synchronous motor (curve A) in Embodiment 1 and the traditional hairpin flat wire winding permanent magnet synchronous motor with non-parallel teeth (curve B) operate at a speed of 1500 r / min with different currents.

[0029] Figure 7 Shown is the current density distribution of the flat wire conductor in the stator slot when the traditional non-parallel-tooth hairpin flat wire winding permanent magnet synchronous motor operates at a speed of 15000 r / min.

[0030] Figure 8 Shown is the current density distribution of the flat wire conductor in the stator slot when the parallel-tooth hairpin flat wire winding permanent magnet synchronous motor in Embodiment 1 operates at a speed of 15000 r / min.

[0031] Figure 9 Shown are the high-frequency winding copper losses when the hairpin flat wire winding permanent magnet synchronous motor (curve A) in Embodiment 1 and the traditional hairpin flat wire winding permanent magnet synchronous motor with non-parallel teeth (curve B) operate at a speed of 15000 r / min with different currents.

[0032] Legend: 1. Stator core; 2. Hairpin flat wire winding; 3. Air gap; 4. Permanent magnet; 5. Rotor core; 6. Shaft. Detailed implementation manners

[0033] The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific implementation manners, and this does not limit the protection scope of this application.

[0034] The present invention provides a structure of a hairpin flat wire winding. The stator teeth of the motor adopt parallel teeth, the slot width of the stator slot gradually increases from the inside to the outside, the width w of the cross-section of the flat wire conductor in each stator slot remains unchanged, and the length b1 increases as the slot width increases. Before assembling the motor winding, the hairpin flat wire windings with various cross-sectional area dimensions are processed externally first, and then inserted into the stator slots. The position of each flat wire conductor in each stator slot corresponding to the stator slot after crossing a pitch is set to achieve the purpose of wire transposition, and then the ends of two corresponding hairpin flat wire conductors are welded together.

[0035] The cross-sectional dimensions of each hairpin flat wire conductor in the motor stator slot can be determined by the following method. Let the number of layers of flat wire conductors in the radial direction in each stator slot be n, the number of flat wire conductors in the circumferential direction be m (m≥1, both m and n are integers greater than 1), the slot depth be h, and the radial distance between adjacent layers of flat wire conductors be ε1. Then the width w of the cross-section of the flat wire conductor satisfies:

[0036] nw+(n - 1)ε1 < h

[0037] That is:

[0038]

[0039] Set the width of the stator slot opening as l1, the width of the stator slot bottom as l2, and denote the first layer of flat wire conductors closest to the stator slot opening in the stator slot as Z1. The sum of the cross-sectional lengths of m flat wire conductors on the first layer is The cross-sectional length of each flat wire conductor on the first layer is b1. Denote the kth (1 ≤ k ≤ n) layer of flat wire conductors counted from the stator slot opening to the stator slot bottom as Z k , and the sum of the cross-sectional lengths of m flat wire conductors on the kth layer is The cross-sectional length of each flat wire conductor on the kth layer is b k . b k and satisfy the following relationship:

[0040]

[0041] Let the circumferential distance between two adjacent flat wire conductors on each layer be ε2, then satisfies:

[0042]

[0043] Let the sum of the lengths of the cross-sections of the flat wire conductors on each layer be proportional to the slot width, and denote this proportion as c. Then c satisfies:

[0044]

[0045] Let the width of the slot where the outermost layer of flat wire conductors is located be l3 and the depth be h1. Then h1 satisfies:

[0046] h1 = h - (n - 1)(w + ε1)

[0047] Then l3 satisfies:

[0048]

[0049] Then the change in the stator slot width from the outermost layer of flat wire conductors to the innermost layer of flat wire conductors

[0050]

[0051] Denote the difference in length between two adjacent layers of flat wire conductors as Δ. Then the value of Δ can be expressed in terms of c as:

[0052]

[0053] Therefore, the sum of the cross-sectional lengths of the flat wire conductors on the kth layer is:

[0054]

[0055] In summary, the length and width of the cross-section of the flat wire conductor in the k-th layer in the stator slot can be described and limited by the following variables:

[0056]

[0057] Furthermore, a permanent magnet synchronous motor is designed. The permanent magnet synchronous motor includes a stator core 1, a rotor core 5, a permanent magnet 4, a rotating shaft 6, and also includes the hairpin flat wire winding structure as described above. Among them, the tooth part of the stator core 1 is designed as parallel teeth, which are formed by laminating and fastening a number of identical amorphous alloy sheets uniformly arranged inside in the same state along the axial direction; the rotor core is formed by laminating and fastening a number of identical silicon steel sheets uniformly arranged inside in the same state along the axial direction; the hairpin flat wire winding is processed externally and then inserted into the stator slot, and then the ends of the winding are welded together at the other end; the rotor core and the permanent magnet form a rotor structure, a rotating shaft mounting hole is arranged at the center of the rotor structure, the rotor structure is fixed on the rotating shaft through the rotating shaft mounting hole, the stator core is sleeved on the outer periphery of the rotor structure and there is an air gap between the stator core and the rotor structure, and the stator core is fixed by the motor base, and the length of the stator core is the same as the length of the rotor structure.

[0058] The stator teeth of the permanent magnet synchronous motor in the present invention are parallel teeth, the winding uses a hairpin flat wire winding, the cross-sectional area of each flat wire conductor in the stator slot changes with the change of the slot width of the stator slot, making full use of the slot area. Under the same current excitation, the motor in the present invention has a higher electromagnetic torque compared with the motor using non-parallel teeth. At the same time, due to the increase in the cross-sectional area of the flat wire conductor, its DC resistance is smaller than that of the flat wire motor with non-parallel teeth, effectively reducing the low-frequency copper loss, and introducing the transposition technology of Litz wire into the present invention to exchange the positions of the hairpin flat wire conductors in the stator slot, suppressing the AC effect and reducing the copper loss at high frequencies.

[0059] Embodiment 1

[0060] This embodiment provides a structure of a hairpin flat wire winding. The tooth part of the stator of the motor is designed as non-parallel teeth, the slot width of its stator slot gradually increases from the inside to the outside, the width of the cross-section of the flat wire conductor in each stator slot remains unchanged, and the length increases with the increase of the slot width. The length direction is defined as the circumferential direction of the stator slot, and the width direction is defined as the radial direction of the stator slot.

[0061] In this embodiment, the radial distance between adjacent two layers of flat wire conductors is ε1 = 0.1 mm, the slot depth h = 18 mm, then the width w of each flat wire conductor cross-section should satisfy:

[0062]

[0063] Take the width w of the flat wire conductor as 2.15 mm.

[0064] In this embodiment, the number of flat wire conductors per slot in the circumferential direction is m = 2, the number of layers of flat wire conductors in the radial direction is n = 8, the circumferential distance between two adjacent flat wire conductors on each layer is ε2 = 0.1 mm, and the ratio c of the sum of the lengths of the cross-sections of the flat wire conductors on each layer to the slot width of the stator slot is 0.875. Then:

[0065]

[0066] In this embodiment, the width of the stator slot opening is l1 = 4.8 mm, the width of the stator slot bottom is l2 = 7.2 mm, and the slot depth h1 where the outermost layer of flat wire conductors is located is:

[0067] h1 = h - (n - 1)(w + ε1) = 15.75 mm

[0068] Then the width l3 of the slot where the outermost layer of flat wire conductors is located is:

[0069]

[0070] Then the change l in the stator slot width from the outermost layer of flat wire conductors to the innermost layer of flat wire conductors Δ is:

[0071] l Δ = l3 - l1 = 2.1 mm

[0072] The difference Δ between the sums of the lengths of the cross-sections of two adjacent layers of flat wire conductors is:

[0073]

[0074] Therefore, the sum of the lengths of the cross-sections of the kth layer of flat wire conductors satisfies:

[0075]

[0076] The winding distributions of the A-phase, B-phase, and C-phase of the permanent magnet synchronous motor are exactly the same, only the slot positions spanned by each phase are different, and at the same time, the winding distributions under each pole are also exactly the same. Therefore, taking the A-phase winding under any pair of poles as an example, the specific positions and corresponding relationships of each flat wire conductor in the stator slot in this embodiment are described as follows:

[0077] In this embodiment, the number of pole pairs of the motor is 4, the number of stator slots is 48, and the integral pitch overlapping winding is adopted. Then the pitch is the number of stator slots divided by twice the number of pole pairs, that is, the pitch is 6. As Figure 2 shown, any slot on the stator is named slot 1, and then named slot 2, slot 3,..., slot 48 in sequence in the clockwise direction. Then the stator slots spanned by the A-phase winding are slot 1, slot 2, slot 7, and slot 8. Each slot contains 16 flat wire conductors. Each flat wire conductor in slot 1 is named A 1+ , A 2+,…,A nm+ (nm = 1, 2, …, 16, indicating there are n layers in total, with m flat wire conductors in each layer, and a total of nm flat wire conductors), name each flat wire conductor in slot 2 as A 1- , A 2- ,…,A nm- , name each flat wire conductor in slot 7 as Name each flat wire conductor in slot 8 as Where the plus sign indicates that the flat wire conductor penetrates into the stator slot, and the minus sign indicates that the flat wire conductor exits the stator slot.

[0078] Therefore, after the flat wire conductor penetrates into slot 1, it should exit from slot 7. Taking four adjacent flat wire conductors as a group, when penetrating into slot 7, for two adjacent flat wire conductors on the same side of two adjacent layers in different slots, they exchange positions along the diagonal, while the other two adjacent flat wire conductors on the same side do not exchange positions. Then, A in slot 1 1+ The corresponding position in slot 7 is like A 1- shown, A 2+ The corresponding position in slot 7 is A 2- shown. Similarly, A nm+ The corresponding position is A nm- shown; The flat wire conductor exiting from slot 7 should penetrate into slot 2. A in slot 7 1- The corresponding position in slot 2 is like shown, A 2- The corresponding position in slot 2 is shown. Similarly, A nm- The corresponding position is A * nm+ shown; The flat wire conductor penetrating into slot 2 should exit from slot 8. The corresponding position in slot 8 is like shown, The corresponding position in slot 8 is shown. Similarly, A * nm+

[0079] The corresponding position is A * nm- shown.

[0080] Further, a permanent magnet synchronous motor is designed, which includes a stator core, a rotor core, permanent magnets, a rotating shaft, and also includes the structure of the hairpin flat wire winding as described above. Among them, the tooth part of the stator core is designed as parallel teeth, which are formed by laminating and fastening a number of identical amorphous alloy sheets with uniform internal settings in the same state along the axial direction; the hairpin flat wire winding is processed externally and then inserted into the stator slots, and the ends of the corresponding flat wire conductors are welded together at the other end according to the corresponding positions of each flat wire conductor described above; the rotor core is formed by laminating and fastening a number of identical silicon steel sheets with uniform internal settings in the same state along the axial direction; the rotor structure is fixed on the rotating shaft through the rotating shaft mounting hole, the stator core is sleeved on the outer periphery of the rotor structure and there is an air gap between the two, and the stator core is fixed by the motor base, and the length of the stator core is the same as that of the rotor structure.

[0081] The parameters of the permanent magnet synchronous motor in this embodiment are shown in Table 1.

[0082]

[0083] According to the permanent magnet motor structure parameters in Table 1, a finite element model of the parallel-tooth hairpin flat wire winding permanent magnet synchronous motor in Embodiment 1 is established in the finite element analysis software (Ansys), as Figure 3 shown, including a stator core 1, a hairpin flat wire winding 2, a rotor core 5, permanent magnets 4, and a rotating shaft 6.

[0084] Among them, the stator core 1 is an annular structure composed of a plurality of parallel tooth parts, and a plurality of slit grooves composed of tooth parts and yoke parts are provided. This slit groove is the stator slot for winding the hairpin flat wire winding 2. A three-phase symmetric distributed winding is wound inside the stator core 1, which can generate a rotating magnetic field. This magnetic field interacts with the magnetic field generated by the permanent magnets 4 on the rotor to generate electromagnetic torque.

[0085] The finite element model of the traditional non-parallel-tooth hairpin flat wire winding permanent magnet synchronous motor, as Figure 4 shown.

[0086] Figure 5 Shown is a schematic diagram of the torque comparison between the hairpin flat wire winding permanent magnet synchronous motor (Curve A) in Embodiment 1 and the traditional hairpin flat wire winding permanent magnet synchronous motor with non-parallel teeth (Curve B); it can be seen from the figure that the hairpin flat wire winding permanent magnet synchronous motor in this embodiment has a higher electromagnetic torque than the hairpin flat wire winding permanent magnet synchronous motor with non-parallel teeth.

[0087] Figure 6Shown are the winding copper losses of the parallel-tooth hairpin flat wire winding permanent magnet synchronous motor (curve A) in Embodiment 1 and the traditional hairpin flat wire winding permanent magnet synchronous motor with non-parallel teeth (curve B) when operating at a speed of 1500 r / min with different current values. It can be seen that the copper loss of the motor in Embodiment 1 is less than that of the traditional hairpin flat wire winding permanent magnet synchronous motor with non-parallel teeth. When the total input current is 216 A, curve A shows a copper loss of 506.87 W, while curve B shows a copper loss of 622.58 W. It can be seen that the hairpin flat wire winding structure in Embodiment 1 effectively reduces the copper loss of the motor at low frequencies.

[0088] Figure 7 Shown is the current density distribution diagram of the traditional hairpin flat wire winding permanent magnet synchronous motor with non-parallel teeth when the total input current is 216 A at a speed of 15000 r / min. At this time, the operating frequency of the motor is 1000 Hz. Due to the relatively large cross-sectional size of the non-parallel tooth hairpin flat wire winding, the current distribution inside the flat wire conductor is affected by the skin effect and proximity effect, and the current distribution inside the flat wire conductor is very uneven.

[0089] Figure 8 Shown is the current density distribution diagram of the parallel-tooth hairpin flat wire winding permanent magnet synchronous motor in Embodiment 1 when the total input current is 216 A. It can be seen that after adopting the transposed winding, the skin effect and proximity effect are effectively suppressed, and the current distribution inside the flat wire conductor tends to be uniform.

[0090] Figure 9 Shown are the winding copper losses of the parallel-tooth hairpin flat wire winding permanent magnet synchronous motor (curve A) in Embodiment 1 and the traditional hairpin flat wire winding permanent magnet synchronous motor with non-parallel teeth (curve B) when operating at a speed of 15000 r / min with different current values. It can be seen that the copper loss of the motor in Embodiment 1 is much less than that of the traditional hairpin flat wire winding permanent magnet synchronous motor with non-parallel teeth. The transposed hairpin flat wire structure adopted in Embodiment 1 effectively reduces the copper loss of the motor at high frequencies, and the effect is remarkable.

[0091] Although the present invention has been described in connection with its specific embodiments, it should be understood that the invention can be further modified. This application intends to cover any variations, uses, or changes to the present invention in general, including those different from the content disclosed herein such as those in the known or customary practices within the technical field to which the present invention pertains, and those such as can be applied to the basic features proposed above.

[0092] Since the present invention may be embodied in several forms without departing from the spirit of its essential characteristics, it should be understood that, unless otherwise specified, the embodiments described above are not intended to limit the present invention, but rather should be construed broadly within the spirit and scope of the present invention as defined in the appended claims. The embodiments described should be considered illustrative in all respects and not restrictive.

[0093] The above-described embodiments merely represent several embodiments of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent for the present invention. It should be noted that, for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all fall within the protection scope of the present invention.

[0094] Matters not described in the present invention are applicable to the prior art.

Claims

1. The structure of a hairpin flat wire winding, characterized in that, The stator of the motor adopts parallel teeth. The slot width of the stator slot gradually increases from the inner side to the outer side. The width of the cross-section of the hairpin flat wire conductor in each stator slot remains unchanged, denoted as w, and the length increases as the slot width of the stator slot increases; Let the number of layers of flat wire conductors along the radial direction in each stator slot be n, the number of flat wire conductors along the circumferential direction be m, m ≥ 1, the sizes of the flat wire conductors in the same layer are the same, and the ratio of the sum of the lengths of the cross-sections of the flat wire conductors in each layer to the slot width of the stator slot is the same, denoted as c; the slot depth of the stator slot is h, the radial distance between adjacent layers of flat wire conductors is ε1, the circumferential distance between adjacent two flat wire conductors on each layer is ε2, the stator slot opening width is l1, the stator slot bottom width is l2, and the first layer of flat wire conductors closest to the stator slot opening in the stator slot is denoted as Z1, and the sum of the lengths of the cross-sections of the m flat wire conductors on the first layer is The length of the cross-section of each flat wire conductor on the first layer is b1, and the k-th layer of flat wire conductors counted from the stator slot opening to the stator slot bottom direction is denoted as Z k , 1 ≤ k ≤ n, and the sum of the lengths of the cross-sections of the m flat wire conductors on the k-th layer is The length of the cross-section of each flat wire conductor on the k-th layer is b k , and the width of the slot where the outermost layer of flat wire conductors is located is l3. Then, the length and width of the cross-section of the k-th layer of flat wire conductor in the stator slot are described and restricted by the following variables where, Δ is the length difference between two adjacent layers of flat wire conductors.

2. The structure of the flat wire winding of the hairpin according to claim 1, wherein Before assembling the motor winding, the flat wire windings with various cross-sectional area dimensions are first processed externally and then inserted into the stator slots. The position of each flat wire conductor in the stator slot after crossing a pitch is set to achieve the purpose of wire transposition, and then the ends of two corresponding hairpin flat wire conductors are welded together.

3. The structure of the hairpin flat wire winding according to claim 2, wherein, The wire transposition method adopts the transposition technology of Litz wire. Determine the number of pole pairs and the number of stator slots of the motor. If a full-pitch lap winding is adopted, the pitch is the number of stator slots divided by twice the number of pole pairs. Name any slot on the stator as slot 1, and then name them as slot 2, slot 3,... in the clockwise direction. Then, the stator slots spanned by the phase-A winding are slot 1, slot 2, slot 7, and slot 8. Each slot contains nm flat wire conductors. Name each flat wire conductor in slot 1 as A 1+ , A 2+ , …, A nm+ , nm = 1, 2, …, nm is an integer multiple of 4. Name each flat wire conductor in slot 2 as A 1- , A 2- , …, A nm- , name each flat wire conductor in slot 7 as Name each flat wire conductor in slot 8 as where the positive sign indicates that the flat wire conductor penetrates into the stator slot, and the negative sign indicates that the flat wire conductor penetrates out of the stator slot; The flat wire conductor should pass through slot 7 after entering slot 1, the flat wire conductor passing through slot 7 should enter slot 2, and the flat wire conductor entering slot 2 should pass through slot 8. Taking four adjacent flat wire conductors as a group, when entering slot 7, the two flat wire conductors on the same side of two adjacent layers in different slots exchange positions along the diagonal line, and the other two flat wire conductors on the same side do not exchange positions.

4. A permanent magnet synchronous motor, characterized in that, The permanent magnet synchronous motor uses the structure of the hairpin flat wire winding according to any one of claims 1-3.

5. The permanent magnet synchronous motor according to claim 4, wherein The permanent magnet synchronous motor includes a stator core, a rotor core, permanent magnets, and a rotating shaft. Among them, the tooth part of the stator core is parallel teeth, and the stator core is formed by axially laminating and fastening a number of identical amorphous alloy sheets with uniform internal settings in the same state; the rotor core is formed by axially laminating and fastening a number of identical silicon steel sheets with uniform internal settings in the same state; the hairpin flat wire winding is processed externally and then inserted into the stator slots. According to the set position of each flat wire conductor in the stator slot after crossing a pitch, the ends of the flat wire conductors are welded together at the other end; the rotor core and the permanent magnets form a rotor structure, a rotating shaft mounting hole is provided in the center of the rotor structure, the rotor structure is fixed on the rotating shaft through the rotating shaft mounting hole, the stator core is sleeved on the outer periphery of the rotor structure, and there is an air gap between the stator core and the rotor structure, and the stator core is fixed by the motor base, and the length of the stator core is the same as the length of the rotor structure.

6. The permanent magnet synchronous motor according to claim 4, characterized in that, Applying the transposition technology of Litz wire to the hairpin flat wire winding, exchanging the positions of the hairpin flat wire conductors in the stator slots, suppressing the proximity effect and the skin effect, effectively reducing the AC copper loss of the motor when operating at high frequencies, and at the same time increasing the electromagnetic torque under low-frequency and high-frequency operations.

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