Flat copper wire winding armature of external rotor motor

Abstract

The utility model particularly relates to a flat copper wire winding armature of an external rotor motor. The flat copper wire winding armature comprises an external rotor iron core, H wire slots arranged on the external rotor iron core, and three-phase windings embedded in the H wire slots, the three-phase windings are circularly arranged in the H wire slots in sequence; the three-phase winding comprises a plurality of I-pin windings, a plurality of Hair-pin crown windings and a plurality of special-shaped windings, and each phase of the three-phase winding is a branch. The three-phase leading-out wire of the armature is led out from the crown end, so that the welding end is prevented from being too high, and the internal space of the armature is effectively saved; according to the winding armature, the slot space factor, the heat dissipation capability, the peak torque and the efficiency of the armature can be improved.

Description

Technical Field

[0001] This utility model belongs to the field of motor armature, specifically relating to a flat copper wire winding armature for an external rotor motor. Background Technology

[0002] Due to their high slot fill factor and low noise, flat copper wire windings are widely used in the new energy vehicle field. However, because automotive motors operate at high speeds and have few pole pairs, the proximity and skin effect of flat copper wire at high frequencies leads to high losses. While flat copper wire is advantageous in low-frequency motors, its application in low-speed, multi-rotor motors shows promise. Currently, most rotor motor armatures are concentrated winding structures made of continuously wound round copper wire. Their slot fill factor is limited by the winding equipment, resulting in low motor torque density. Even with continuous winding of flat copper wire, the increase in slot fill factor is still limited. Conventional hairpin crown winding structures with double-layer concentrated windings still suffer from problems such as severe interference at the crown end, numerous wire types, excessively high leads due to welded wire exits, and non-concentrated leads.

[0003] To concentrate the leads of the motor windings, Chinese Patent Publication No. CN114614609A discloses a single-path flat copper wire hairpin rotor winding structure and winding method, including a rotor core, multiple slots, and hairpin flat copper wire windings. Each slot contains multiple wire layers. The hairpin flat copper wire windings include U-phase, W-phase, and V-phase flat copper wire windings. Each of the three-phase flat copper wire windings includes multiple inner single-layer flat copper wires and multiple cross-layer flat copper wires. All wire layers are arranged in ascending order along the direction away from the rotor core center, from the first wire layer to the eighth wire layer. The first layer has multiple inner single-layer flat copper wires embedded in it, the second to seventh layers have multiple cross-layer flat copper wires embedded in it, and the eighth layer has multiple inner single-layer flat copper wires embedded in it. All the flat copper wires are connected together by welding. By inserting inner and outer single-layer flat copper wires and cross-layer flat copper wires into the wire groove and connecting them together by welding, a single-circuit flat copper wire motor winding is formed. Although this patent solves the problem of the lead wires not being concentrated, the wires coming out at the welding end cause the welding end to be too high, occupying too much space at the welding end. In addition, a variety of irregular hair clips are used, which increases the process cost. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model provides a flat copper wire winding armature for an external rotor motor.

[0005] This utility model is achieved through the following technical solution.

[0006] An external rotor motor armature with flat copper wire windings includes an external rotor core, H slots formed on the external rotor core, and three-phase windings embedded in the H slots; the three-phase windings are sequentially circulated within the H slots; the three-phase windings include multiple I-pin windings, multiple hair-pin crown windings, and multiple irregularly shaped windings, with each phase of the three-phase windings being a branch.

[0007] The I-pin winding includes a vertical flat copper wire inserted into the wire slot, with the top and bottom ends of the vertical flat copper wire bent to the same side.

[0008] The Hair-pin crown winding includes Hair-pin crown winding I, Hair-pin crown winding II, Hair-pin crown winding III and Hair-pin crown winding IV;

[0009] The Hair-pin crown winding I includes two vertical flat copper wires inserted in adjacent wire slots, and a horizontal flat copper wire that is bent upwards and positioned to the left of the center point at the top of the two vertical flat copper wires. The bottom ends of the two vertical flat copper wires are bent inwards.

[0010] The Hair-pin crown winding II includes two vertical flat copper wires inserted into adjacent wire slots, a horizontal flat copper wire that is bent upwards and positioned to the left of the center point at the top of the two vertical flat copper wires, and the bottom ends of the two vertical flat copper wires are bent outwards and inwards respectively.

[0011] The Hair-pin crown winding III includes two vertical flat copper wires inserted into adjacent wire slots, a horizontal flat copper wire that is bent upwards and positioned to the right of the center point at the top of the two vertical flat copper wires, and the bottom ends of the two vertical flat copper wires are bent inwards and outwards respectively.

[0012] The Hair-pin crown winding IV includes two vertical flat copper wires inserted into adjacent wire slots, and a horizontal flat copper wire that is bent upwards and positioned to the right of the center point, connected to the top of the two vertical flat copper wires. The bottom ends of the two vertical flat copper wires are bent inwards.

[0013] The irregular winding includes a horizontal flat copper wire inserted into a space that spans 7 to 9 slots, and two vertical flat copper wires connected to both ends of the horizontal flat copper wire. The bottom ends of the two vertical flat copper wires are bent inward and outward, respectively.

[0014] Each phase of the three-phase winding has five sets of coils evenly spaced along the circumference of the outer rotor core.

[0015] The N-terminus of the three-phase winding is connected by two irregularly shaped windings and then by an I-pin winding.

[0016] The beneficial effects of this utility model are as follows:

[0017] 1. The use of flat copper wire concentrated windings improves the slot fill factor of the motor rotor, thereby enhancing the motor's heat dissipation capacity, peak torque, and efficiency.

[0018] 2. Using different types of Hair-pin crown windings in the same layer ensures that the crown ends of the two Hair-pin crown windings in the same layer do not interfere with each other. When pressing into the armature, it can ensure that the I-pin winding is not damaged, thus improving the insertion efficiency.

[0019] 3. A combination of Hair-pin crown winding and I-pin winding is used to concentrate the winding, so as to realize the crown end wire exit, avoid the welded end wire exit causing the end to be too high, and save the internal space of the armature. Attached Figure Description

[0020] Figure 1 This is a three-dimensional view of the flat copper wire winding armature structure of the external rotor motor of this utility model;

[0021] Figure 2 This is a schematic diagram of the layer distribution of a single wire groove in this utility model;

[0022] Figure 3 This is a schematic diagram of the structure of the I-pin winding of this utility model;

[0023] Figure 4 This is a schematic diagram of the structure of the Hair-pin crown winding I of this utility model;

[0024] Figure 5 This is a schematic diagram of the structure of the Hair-pin crown winding II of this utility model;

[0025] Figure 6 This is a schematic diagram of the structure of the Hair-pin crown winding III of this utility model;

[0026] Figure 7 This is a schematic diagram of the structure of the Hair-pin crown winding IV of this utility model;

[0027] Figure 8 This is a schematic diagram of the irregular winding structure of this utility model;

[0028] Figure 9 This is a schematic diagram showing the distribution of the U-phase winding, V-phase winding, and W-phase winding in the armature according to an embodiment of the present invention, where 9(a1) is a distribution diagram. Figure 1 , 9(a2) is a schematic diagram of the distribution. Figure 2 ;

[0029] Figure 10 This is a schematic diagram showing the winding distribution of the five coil windings of phase U in Embodiment 1 of this utility model, where 10(b1) is a winding diagram. Figure 1 10(b2) is a winding diagram. Figure 2 ;

[0030] Figure 11 A schematic diagram of the winding distribution of the five coil windings of phase U in Embodiment 2 of this utility model, wherein 11(c1) is a winding diagram. Figure 1 11(c2) is a winding diagram. Figure 2 ;

[0031] In the diagram: 1-Outer rotor core, 2-I-pin winding, 3-Hair-pin crown winding, 4-Irregular winding, 5-Crown end, 6-Welding end, 7-Wire slot, 8-Wire layer, 9-Vertical flat copper wire of I-pin winding, 10-Top of I-pin winding, 11-Bottom of I-pin winding, 12-Hair-pin crown winding I, 13-Two vertical copper wires of Hair-pin crown winding I, 14-Top of Hair-pin crown winding I, 15-Bottom of Hair-pin crown winding I, 16-Horizontal flat copper wire of Hair-pin crown winding I, 17-Hair-pin crown winding II, 18-Two vertical copper wires of Hair-pin crown winding II, 19-Top of Hair-pin crown winding II, 20-Hair-pin crown winding II Bottom of crown winding II, 21-Hair-pin crown winding II horizontal flat copper wire, 22-Hair-pin crown winding III, 23-Hair-pin crown winding III two vertical copper wires, 24-Hair-pin crown winding III top, 25-Hair-pin crown winding III bottom, 26-Hair-pin crown winding III horizontal flat copper wire, 27-Hair-pin crown winding IV, 28-Hair-pin crown winding IV two vertical copper wires, 29-Hair-pin crown winding IV top, 30-Hair-pin crown winding IV bottom, 31-Hair-pin crown winding IV horizontal flat copper wire, 32-Two vertical copper wires of irregular winding, 33-Top of irregular winding, 34-Bottom of irregular winding, 35-Horizontal flat copper wire of irregular winding. Detailed Implementation

[0032] The technical solution of this utility model is further described below, but the scope of protection is not limited to what is described.

[0033] As shown in the figures, an armature of an external rotor motor with flat copper wire windings includes an external rotor core 1, H slots 7 formed on the external rotor core 1, and three-phase windings embedded in the H slots 7; the three-phase windings are sequentially circulated in the H slots 7; the three-phase windings include multiple I-pin windings 2, multiple hair-pin crown windings 3, and multiple irregular windings 4, with each phase of the three-phase windings being a branch.

[0034] Technical benefits: By inserting I-pin winding 2, hairpin crown winding 3, and irregular winding 4 into the slot 7, a concentrated winding distribution is adopted. The copper wire welding ends are widened inward, and the welding ends of adjacent layers are twisted in opposite directions. Every two stripped copper wires are welded together to form a single-path flat copper wire winding armature. This overcomes the difficulties in arranging concentrated flat copper wire windings, which can easily cause branch asymmetry and circulating current. The pure copper slot fill factor is as high as 67%, and the winding arrangement is compact, which is conducive to armature heat conduction. The use of I-pin winding 2 not only effectively reduces the height of welding end 6, but also allows the three-phase leads to be led out at crown end 5, avoiding excessive height of welding end 6, and effectively saving internal armature space.

[0035] The value of H is 45.

[0036] The three-phase windings are the U-phase winding, the V-phase winding, and the W-phase winding.

[0037] like Figure 2 The diagram shows the layer distribution of a single wire slot of this utility model. The single wire slot 7 is divided into two columns of wire layers 8, namely the M1 column and the M2 column. Each column of wire layers 8 is arranged in ascending order along the direction close to the center of the outer rotor core 1, and is arranged as follows: first layer a, second layer b, third layer c, fourth layer d, fifth layer e, sixth layer f, and seventh layer g.

[0038] Technical effect: By dividing a single wire slot into two rows of wire layers 8, with each row of wire layers 8 divided into 7 layers, the slot area can be effectively reduced, thereby effectively reducing the magnetic voltage drop, and thus improving the air gap magnetic flux density of the motor, achieving the purpose of improving the peak torque and efficiency of the armature.

[0039] like Figure 3 The schematic diagram of the structure of the I-pin winding of this utility model shows that the I-pin winding 2 includes a vertical flat copper wire 9 inserted in the wire groove 7, and the top end 10 and bottom end 11 of the vertical flat copper wire 9 are both bent to the same side.

[0040] In this embodiment, a total of 4 I-pin windings 2 are used, namely the input terminal and common point N terminal of the U-phase winding, V-phase winding and W-phase winding, so that the input and output wires exit at the crown terminal 5, avoiding the welding terminal 6 from exiting, which would cause its end to be too high, effectively reducing the end height of the welding terminal 6 and saving the internal space of the welding terminal 6.

[0041] The Hair-pin crown winding 3 includes Hair-pin crown winding I 12, Hair-pin crown winding II 17, Hair-pin crown winding III 22 and Hair-pin crown winding IV 27;

[0042] like Figure 4The diagram shows the structure of the Hair-pin crown winding I of this utility model; the Hair-pin crown winding I 12 includes two vertical flat copper wires 13 inserted in adjacent wire slots 7, a horizontal flat copper wire 16 that is bent upward and set to the left of the center point and connected to the top 14 of the two vertical flat copper wires 13, and the bottom 15 of the two vertical flat copper wires 13 are bent inward.

[0043] like Figure 5 The diagram shown is a structural schematic of the Hair-pin crown winding II of this utility model. The Hair-pin crown winding II 17 includes two vertical flat copper wires 18 inserted into adjacent wire slots 7, a horizontal flat copper wire 21 that is bent upward and set to the left of the center point and connected to the top 19 of the two vertical flat copper wires 18, and the bottom 20 of the two vertical flat copper wires 18 are bent outward and inward respectively.

[0044] Except for the 7th layer which uses I-pin winding 2 and irregular winding 4, the remaining windings in the M1 column are: the first and seventh layers use Hair-pin crown winding II 17, and the second to sixth layers in the M1 column use Hair-pin crown winding I 12.

[0045] like Figure 6 The diagram shown is a structural schematic of the Hair-pin crown winding III of this utility model. The Hair-pin crown winding III 22 includes two vertical flat copper wires 23 inserted into adjacent wire slots 7, a horizontal flat copper wire 26 that is bent upward and set to the right relative to the center point, connected to the top 24 of the two vertical flat copper wires 23, and the bottom 25 of the two vertical flat copper wires 23 are bent inward and outward respectively.

[0046] like Figure 7 The diagram shown is a structural schematic of the Hair-pin crown winding IV of this utility model. The Hair-pin crown winding IV 27 includes two vertical flat copper wires 28 inserted into adjacent wire slots 7, and a horizontal flat copper wire 31 that is bent upward and set to the right relative to the center point, connected to the top 29 of the two vertical flat copper wires 28. The bottom 30 of the two vertical flat copper wires 28 are both bent inward.

[0047] Except for the 7th layer which uses I-pin winding 2 and irregular winding 4, the remaining windings in the M2 column are: the first and seventh layers use Hair-pin crown winding Ⅲ22, and the second to sixth layers in the M2 column use Hair-pin crown winding Ⅳ27.

[0048] like Figure 8The diagram shown is a schematic diagram of the irregular winding of this utility model. The irregular winding 4 includes a horizontal flat copper wire 35 inserted into a slot that can span 7 to 9 slots, and two vertical flat copper wires 32 connected to both ends of the horizontal flat copper wire 35. The bottom ends 34 of the two vertical flat copper wires 32 are bent inward and outward respectively.

[0049] like Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 The different winding structures shown have different bends at the bottom to facilitate welding, and different bends at the top to make the armature windings form left and right spikes and staggered layers at the crown end 5 of the same layer.

[0050] Its technical advantages are as follows: The Hair-pin structure solves the problem of compact space and easy interference at the crown end of the concentrated winding structure with two rows of flat copper wires in the same slot. It not only reduces the height of the crown end winding and saves copper, but also ensures that the solder joints of the two rows of copper wires in the same slot are evenly distributed, greatly improving the automation of production processes. The mixed use of I-pin winding structure can effectively change the winding current flow direction, so that the three-phase leads are at the crown end, reducing the height of the lead wire at the solder end.

[0051] Figure 9 This is a schematic diagram showing the distribution of the U-phase winding, V-phase winding, and W-phase winding in the armature according to an embodiment of the present invention, where 9(a1) is a distribution diagram. Figure 1 , 9(a2) is a schematic diagram of the distribution. Figure 2 Each phase of the three-phase winding has five sets of coils evenly spaced along the circumference of the outer rotor core 1. Specifically, the U-phase winding, V-phase winding, and W-phase winding each have five sets of coils spaced along the circumference of the outer rotor. One of the 45 slots 7 on the outer rotor core 1 is designated as sequence 1, and the 45 slots 7 are sequentially numbered along the circumference of the outer rotor core 1, with sequence number 45 adjacent to sequence number 1. The span between adjacent sets of coils in the U-phase winding is nine slots 7. The span between each of the five sets of coils in the V-phase winding relative to the adjacent coils in the U-phase winding is four slots. The span between each of the five sets of coils in the W-phase winding relative to the adjacent coils in the U-phase winding is nine slots.

[0052] Technical effect: The above arrangement can effectively weaken the back EMF harmonics of the winding, reduce the torque fluctuation of the motor, and at the same time enable each slot winding to be directly connected after the welding end is twisted and evenly distributed, avoiding the generation of circulating current.

[0053] The first group of coils in the U-phase winding is connected to the second group of coils, the second group of coils is connected to the third group of coils, the third group of coils is connected to the fourth group of coils, and the fourth group of coils is connected to the fifth group of coils through the irregular winding 4.

[0054] The first group of coils in the V-phase winding is connected to the second group of coils, the second group of coils is connected to the third group of coils, the third group of coils is connected to the fourth group of coils, and the fourth group of coils is connected to the fifth group of coils through the irregular winding 4.

[0055] The first group of coils in the W-phase winding is connected to the second group of coils, the second group of coils is connected to the third group of coils, the third group of coils is connected to the fourth group of coils, and the fourth group of coils is connected to the fifth group of coils through a special-shaped winding 4.

[0056] The N-terminals of the U-phase winding, V-phase winding, and W-phase winding are connected by two irregular windings 4 and then by an I-pin winding 2. That is, the N-terminal of the fifth coil of the U-phase winding is connected to the N-terminal of the fifth coil of the V-phase winding by irregular windings 4, and the N-terminal of the fifth coil of the V-phase winding is connected to the N-terminal of the fifth coil of the W-phase winding by irregular windings 4. Then, the N-terminals of the three-phase windings that have been connected are connected by an I-pin winding 2. This arrangement is to allow the N-terminals of the three phases to exit from the crown end 5.

[0057] like Figure 10 This is a schematic diagram of the winding of the 5 groups of coils in the U phase of Embodiment 1 of this utility model, where 10(b1) is a winding diagram. Figure 1 10(b2) is a winding diagram. Figure 2 Suppose there are 45 slots (7), 50 poles, and 1 branch. Each slot (7) is divided into two rows of 8 layers, and each row of 8 layers is divided into 7 layers. Define xyz as the z-th column of the y-th layer in the x-th slot, where 1 ≤ x ≤ 45, x is a positive integer, y is a, b, c, d, e, f, g, where a represents the 1st layer in the slot, b represents the 2nd layer, c represents the 3rd layer, d represents the 4th layer, e represents the 5th layer, f represents the 6th layer, g represents the 7th layer, and z is M1 and M2, where M1 represents the 1st column in the slot and M2 represents the 2nd column in the slot. IN I is the initial current inflow point of the U-phase branch. OUT This is the final outlet point for the current in the U-phase branch; in the diagram, the "solid line" represents the crown end of the flat copper wire, and the "dashed line" represents the welded end; the "arrow direction" indicates the direction of current flow. The U-phase winding configuration in this embodiment 1 is as follows:

[0058] 2gM2→1fM2→2eM2→1dM2→2cM2→1bM2→2aM2→3aM1→2bM1→3cM1→2dM1→3eM1→2fM1→3gM1→4gM1→3fM1→4eM1→3dM1→4cM1→3bM1→4aM1→3aM2→2bM2→3cM2→2dM2→3eM2→2fM2→3gM2→4gM2→3fM2→4 eM2→3dM2→4cM2→3bM2→4aM2→5aM1→4bM1→5cM1→4dM1→5eM1→4fM1→5gM1→11gM2, completing the first group of coils for phase U as described above. The remaining four groups of coils are then wound in the same manner as the first group of coils, spanning nine slots along the increasing direction of slot 7. The initial current of the phase U branch flows in from 2gM2 and finally flows out from 42gM1. The I of this winding method... IN For 2gM2, I OUT It is 42gM1.

[0059] Figure 11 A schematic diagram of the winding of the 5 groups of coils in phase U of embodiment 2 of this utility model, wherein 11(c1) is a winding diagram. Figure 1 11(c2) is a winding diagram. Figure 2 The U-phase winding configuration for this implementation is as follows:

[0060] 3gM1→2gM2→1fM2→2eM2→1dM2→2cM2→1bM2→2aM2→3aM1→2bM1→3cM1→2dM1→3eM1→2fM1→3fM1→4eM1→3dM1→4cM1→3bM1→4aM1→3aM2→2bM2→3cM2→2dM2→3eM2→2fM2→3fM2→4eM2→3dM2→4cM2→ The first group of coils for phase U is completed as follows: 3bM2→4aM2→5aM1→4bM1→5cM1→4dM1→5eM1→4fM1→5gM1→4gM2→3gM2→4gM1→12gM1. The remaining four groups of coils are then wound sequentially across nine slots along the increasing slot width, following the same winding method as the first group. The initial current of the phase U branch flows into 3gM1 and finally flows out from 42gM1. The I of this winding method... IN For 3gM1, I OUT It is 42gM1.

[0061] The beneficial effects of this invention are as follows: The use of flat copper wire concentrated windings improves the slot fill factor of the motor rotor, enhancing the motor's heat dissipation capacity, peak torque, and efficiency; the use of different structural types of hair-pin crown windings in the same layer ensures that the crown ends of the two hair-pin crown windings in the same layer do not interfere with each other, guaranteeing that the I-pin winding is not damaged when pressed into the armature, thus improving insertion efficiency; the combination of hair-pin crown windings and I-pin windings in a concentrated winding allows for crown end wire exit, avoiding excessively high ends due to welded end wire exit, and saving internal armature space.

[0062] The above embodiments are merely descriptions of preferred embodiments of the present utility model and should not be construed as limiting the present utility model. All modifications and alterations to the technical solutions of the present utility model should fall within the protection scope defined by the claims of the present utility model.

Claims

1. A flat copper wire winding armature of an outer rotor motor, characterized in that: It comprises an outer rotor core (1), H wire slots (7) opened on the outer rotor core (1), and a three-phase winding embedded in the H wire slots (7); the three-phase winding circulates in the H wire slots (7) in sequence; the three-phase winding comprises a plurality of I-pin windings (2), a plurality of Hair-pin crown windings (3), and a plurality of special-shaped windings (4), and each phase of the three-phase winding is a branch.

2. A flat copper wire winding armature for an outer rotor motor as claimed in claim 1, characterized in that: The I-pin winding (2) comprises a vertical flat copper wire (9) inserted into a wire slot (7), and the top end (10) and the bottom end (11) of the vertical flat copper wire (9) are both bent toward the same side.

3. The flat copper wire winding armature of an outer rotor motor as claimed in claim 1, characterized in that: The hair-pin crown winding (3) comprises a hair-pin crown winding I (12), a hair-pin crown winding II (17), a hair-pin crown winding III (22) and a hair-pin crown winding IV (27); The Hair-pin crown winding I (12) comprises two vertical flat copper wires (13) inserted into adjacent wire slots (7), a horizontal flat copper wire (16) connected to the top ends (14) of the two vertical flat copper wires (13) and bent upward and arranged to the left of the center point, and the bottom ends (15) of the two vertical flat copper wires (13) are bent inwards; The Hair-pin crown winding II (17) comprises two vertical flat copper wires (18) inserted into adjacent wire slots (7), a horizontal flat copper wire (21) connected to the top ends (19) of the two vertical flat copper wires (18) and bent upward and arranged to the left of the center point, and the bottom ends (20) of the two vertical flat copper wires (18) are bent outward and inward respectively; The Hair-pin crown winding III (22) comprises two vertical flat copper wires (23) inserted into adjacent wire slots (7), a horizontal flat copper wire (26) connected to the top ends (24) of the two vertical flat copper wires (23) and bent upward and arranged to the right of the center point, and the bottom ends (25) of the two vertical flat copper wires (23) are bent inwards and outwards respectively; The Hair-pin crown winding IV (27) comprises two vertical flat copper wires (28) inserted into adjacent wire slots (7), a horizontal flat copper wire (31) connected to the top ends (29) of the two vertical flat copper wires (28) and bent upward and arranged to the right of the center point, and the bottom ends (30) of the two vertical flat copper wires (28) are bent inwards.

4. The flat copper wire winding armature of an outer rotor motor as claimed in claim 1, characterized in that: The special-shaped winding (4) comprises a horizontal flat copper wire (35) inserted in a region capable of spanning 7 to 9 wire slots, and two vertical flat copper wires (32) connected to both ends of the horizontal flat copper wire (35), wherein the bottom ends (34) of the two vertical flat copper wires (32) are bent inwardly and outwardly respectively.

5. The flat copper wire winding armature of an outer rotor motor as claimed in claim 1, characterized in that: Each phase of the three-phase winding is provided with five groups of coils evenly spaced along the circumferential direction of the outer rotor core (1).

6. The flat copper wire winding armature of an outer rotor motor as claimed in claim 1, characterized in that: The N ends of the three-phase winding are connected through two special-shaped windings (4) and then connected through an I-pin winding (2).

Images