TECHNICAL FIELD

The subject matter described herein, in general, relates to an electrical machine and, in particular, relates to an electrical member of an electrical machine.

BACKGROUND

Electrical machines include generators and motors. Typically, an electrical machine includes electrical members, such as a rotating part known as rotor and a stationary part known as stator. The stator and the rotor, in combination, may generate an electric current, as in the case of generators, or produce a torque, as in the case of motors.

Typically, the stator of the electrical machine, such as an AC machine, includes a stator core and a poly-phase stator winding. Generally, the poly-phase stator winding is a 3-phase stator winding. Typically, the poly-phase stator winding is realized by use of copper wires with circular cross section inserted in a plurality of slots in the stator core. Rectangular cross section wires may also be employed for stator windings to enhance a slot fill factor of the stator to further enhance the performance of the electrical machine.

Conventionally, when rectangular wires are used in the stator, the slots are divided into a number of layers for inserting the wires, and the greater the number of the layers in a slot, greater is number of wires in the slot. However, an increase in the number of layers complicates the insertion and winding of wires. Therefore, conventional techniques employ the provision of less number of layers in each slot of the stator. Alternately, expensive and complex machinery is employed for carrying out a winding of the stator of the electrical machine when a greater number of layers are used in each slot of the stator.

SUMMARY

The subject matter described herein is directed to a method of winding an electrical member of an electrical machine. The method includes inserting at least two conductor segments from a first side of the electrical member and at least two other conductor segments from a second side of the electrical member. It can be understood that a limb of each of the at least two conductor segments is inserted in a slot in the electrical member from the first side and protrudes from the second side and a limb of each of the at least two other conductor segments is inserted in the slot in the electrical member from the second side and protrudes from the first side. Each of the limbs protruding from the second side is connected to a limb of another conductor segment protruding from the second side to form in part a first side coil group and each of the limbs protruding from the first side is connected to a limb of another conductor segment protruding from the first side to form in part a second coil group. Further, the first side coil group and the second side coil group are fastened to form a phase winding.

These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components.

Fig. 1a illustrates a cross sectional view of a conventional electrical machine.

Fig. 1b illustrates an exemplary view of an electrical member used in the conventional electrical machine.

Fig. 2a illustrates a cross sectional view of an electrical machine, in accordance with an embodiment of the present subject matter.

Fig. 2b illustrates an exemplary view of electrical member used in the electrical machine, in accordance with an embodiment of the present subject matter.

Fig. 2c illustrates a slot of the electrical member, in accordance with an embodiment of the present subject matter.

Fig. 3 illustrates a perspective view showing conductor segments of the electrical member, in accordance with an embodiment of the present subject matter.

Fig. 4 illustrates a schematic view of conductor segments of the electrical member, in accordance with an embodiment of the present subject matter.

Fig. 4a, Fig. 4b & Fig. 4c illustrate perspective views of full pitch, short pitch, and link conductor segments, used in the electrical member, in accordance with an embodiment of the present subject matter.

Fig. 4d illustrates a perspective view of a conductor segment used in odd coil-groups of the electrical member, in accordance with an embodiment of the present subject matter.

Fig. 4e and Fig. 4f illustrate a perspective view of conductor segments used in even coil groups of the electrical member, in accordance with an embodiment of the present subject matter.

Fig. 5a illustrates an assembly of the odd coil group of a first phase, in accordance with an embodiment of the present subject matter.

Fig. 5b illustrates an assembly of the even coil group of the first phase, in accordance with an embodiment of the present subject matter.

Fig. 5c illustrates an electrical winding diagram of the first phase with the odd and even coil groups, in accordance with an embodiment of the present subject matter.

Fig. 6a illustrates an electrical winding diagram of the electrical member, in accordance with an embodiment of the present subject matter.

Fig. 6b illustrates various views of windings of the stator electrical member, in accordance with an embodiment of the present subject matter.

Fig. 7 illustrates various views of the windings of the electrical member, in accordance with another embodiment of the present subject matter.

DETAILED DESCRIPTION

The subject matter described herein is directed to winding of an electrical member in an electrical machine, for example, a motor or a generator. The electrical machine may be an AC machine and may belong to the class of either synchronous or asynchronous machines. Conventionally, in an electrical machine, the electrical member, such as a stator, in combination with other electrical members, for example, a rotor, may either generate current as in a generator, or generate torque as in a motor.

Typically, a stator includes a cylinder shaped stator core having two sides, one at each end of its longitudinal axis, wherein multiple slots are provided along the periphery of the stator, extending from one end to the other. The stator also includes poly-phase stator windings over the stator core. As will be understood, the stator windings intercept a magnetic flux generated by the rotor, to generate an output i.e., either the stator generates the current when the torque is supplied to the rotor or the torque is produced by the rotor when the current is supplied to the stator. Therefore, as the number of stator windings is increased, the magnetic flux intercepted is increased, that further increases the output of the electrical machine. Generally, the stator windings are realized by use of copper wires.

The copper wires may have any cross-section, for example, circular cross section or rectangular cross section.

Further, performance of the electrical machine depends upon a number of parameters, one such performance parameter being a rated capacity of the electrical machine for a given size and weight. Conventionally, performance of the electrical machine is enhanced by optimizing the use of the stator by improving a slot fill factor, which defines an occupancy state of the stator core by the stator windings. In order to optimize the slot fill factor of the stator core, a number of conductor segments inserted per slot are increased and also conductor segments of rectangular cross sections are used.

Generally, a conductor segment of rectangular cross section has a 'U' shaped portion on one side and free ends on the other side. Typically, a pair or multiple pairs of conductor segments are inserted in the slots of the stator core along an axial direction. The conductor segments are inserted from one side of the stator core in the axial direction such that the 'U' shaped portions are on one side of the stator core and the free ends are electrically joined on the other side of the stator core with the free ends of other conductor segments electrically joined to form continuous coil groups.

Each slot of the stator core is divided into layers for inserting the conductor segments into it. To increase the slot fill factor of the slot, as additional conductor segments are inserted, the number of layers in the slots is also increased. Consequently, the gap between the layers of the slot is reduced. Therefore, the formation of the ends of stator coils, to required position and establishment of the electrical connections between the appropriate coil group ends, becomes complex and tedious. The complexity of stators with such stator windings necessitates use of special tools and processes for manufacturing, and thereby leading to corresponding increase in the manufacturing costs.

A method for winding an electrical member of an electrical machine is described herein. In one example, the electrical member can be a stator of the electrical machine. Although the following description of the present subject matter and the description of the figures is provided with reference to the stator of the electrical machine, it should not be construed as limiting the scope of the subject matter.

In one embodiment, the conductor segments of rectangular cross section are inserted in each of the slots in the axial direction, in pairs alternately from both the sides of the stator core. For example, a first pair of conductor segments may be inserted from one side of the stator core and a second pair of conductor segments may be inserted from the other side of the stator core. In one implementation, the conductor segments are insulated from the stator. Portions of the conductor segments protruding outside the slots on both the sides can be electrically joined together to form a poly-phase stator winding. In said embodiment, the poly-phase stator winding is a three phase stator winding.

The method of winding the stator core as described herein realizes a compact size of the stator, low noise levels during operation, and an enhanced performance of the electrical machine. Further, as the stator winding is formed on both the sides of the stator core, complexity in manufacturing the stator is significantly reduced. Further, the present winding arrangement for the stator core provides a higher power output for the same size of the stator. The described method of stator winding and establishing electrical connections between the conductor segments can be extended to any appropriate number of conductor segments inserted into the slots of the stator core.

Fig. la and Fig. 1b illustrate a cross sectional view of a conventional electrical machine 100 and assembly of an electrical member of the conventional electrical machine 100, respectively.

Fig.1a illustrates the cross sectional view of the conventional electrical machine 100 used in automobiles. The electrical machine 100 includes a rotor 105, a stator 125 that acts as an armature, and a pair of frames, a drive end (DE) bracket 115 and a slip ring end (SRE) bracket 120. The rotor 105 includes a rotor winding and a pair of claw shaped pole cores that are disposed circumferentially about a shaft 110. The stator 125 includes a stator core and a stator winding assembly. The stator core has two sides, one at each end of the stator core along its longitudinal axis. The stator core includes a number of slots having grooves lying in an axial direction that are disposed on circumferential side of the stator core. The slots of the stator core are disposed with a number of conductor segments to form the stator windings.

In an example of the conventional electrical machine 100, described herein, the grooves of the slots of the stator core receive four conductor segments that are rectangular in cross-section. The stator winding assembly comprises one or more coil groups. A coil group is formed by inserting four conductor segments into the slots, such that each slot receives the conductor segments from one side of the stator core. The conductor segments are inserted axially from one side of the stator core such that portion of the conductor segments protruding outside the slots are twisted and appropriate coil ends are electrically joined on the other side of the stator core. Such portions of the conductor segments that protrude outside the slots may also be referred to as protruding portions of the conductor segments. The stator 125 is supported by two end frames (referred to as brackets hereinafter) namely Drive End (DE) bracket 115 & Slip Ring End (SRE) bracket 120 fixed at the rear end and front end of the electrical machine 100 respectively.

Fig. 1b illustrates an exemplary view of the stator 125 present within the electrical machine 100 of Fig. 1. The stator 125 includes four conductor segments inserted into the slots from one side of the stator core. Subsequent to the formation of the coil groups as explained above, the straight members protruding outside the slots on the other side of the stator core are twisted, welded or brazed to form a three phase winding 106. Thus, the electrical connections are established in the stator 125 by twisting and welding the conductor segments in one side of the stator core arranged in multiple rows.

The method of implementing the stator windings of an electrical machine 200 in accordance with the present subject matter is explained in detail with respect to Fig. 2 through Fig. 7. While aspects of method of winding can be implemented in any number of different electrical machines, the embodiments are described in the context of an electrical machine 200, such as an alternator, used in an automobile.

Fig. 2a illustrates an exemplary cross-sectional view of an electrical machine 200, in accordance with an embodiment of the present subject matter. In an implementation, the electrical machine 200 can be a machine having poly-phase armature windings, for example, an AC machine. Further, the electrical machine 200 includes a rotor 205, and a stator 225 that acts as an armature; and a pair of frames, DE frame 215 & SRE frame 220.

The rotor 205 includes a winding and a pair of claw shaped pole cores that are disposed circumferentially about a shaft 210. The following description is provided with respect to winding of the stator 225, also referred to as electrical member 225. However, it will be understood that winding of the other electrical members, such as the rotor 205, can be achieved in a similar manner. As will be understood from the foregoing description, the electrical machine 200 can include various electrical members, such as stator 225 and rotor 205.

The stator 225 includes a stator core 275 and a stator winding assembly 276 having a winding construction pattern in accordance with an embodiment of the present subject matter. The stator core 275 has two sides, one at each end of the stator core 275 along its longitudinal axis. The stator core 275 includes a number of slots having grooves lying in an axial direction that are disposed on circumferential side of the stator core 275. The grooves receive a plurality of conductor segments. The conductor segments may be, for example, either circular or rectangular in cross-section.

To increase the output power and efficiency of the electrical machine 200, one common approach used is to increase a slot fill factor of the stator 225. The slot fill factor can be understood as a factor which determines the proportion of the volume of the slot of the stator core 275 filled by the stator windings. In one example, the slot fill factor can be increased is by inserting conductor segments having rectangular cross section, into the slots. The rectangular conductor segments maximize the space utilization of the slots in the stator core 275.

Fig.2b represents the perspective view of the stator 225 with the conductor segments inserted into the stator core 275, in accordance with the present subject matter. The stator 225 includes the stator core 275 and the stator winding assembly 276. The stator core 275 has two sides, side 'A' and side 'B1 at each end of its longitudinal axis of the stator core 275. Side A and side B may also be referred to as a first side and a second side of the stator core 275, respectively. The stator core 275 further includes a number of slots that are disposed on the circumferential side and extending through the lateral wall such that the slots extend longitudinally in an axial direction of the stator core 275 from the first side to the second side. The slots receive a plurality of hairpin shaped conductor segments of rectangular cross section, in antipodal directions from both the sides of the stator core 275 axially. In one embodiment, the conductor segments can be round cross-sectional conductor segments. In yet another embodiment, the conductor segments can be square or trapezoidal in cross-section or with any other shape that suits the slot profile.

In an embodiment, each slot accommodates at least four conductor segments such that at least two conductor segments of the four conductor segments can be inserted from each side of the stator core 275. Although, the forthcoming description describes insertion of four conductor segments into each slot, but it will be understood that the same principles may extended to cover insertion of a more than four conductor segments into every slot.

Furthermore, although the description of the present subject matter is provided with respect to an electrical machine 200 used in automobiles, it may be noted that this arrangement may be implemented in all other types of electrical machines. In an example, the electrical machines include generators and motors of synchronous and asynchronous type used in any applications.

Fig. 2c illustrates a view of the slots of the stator 225, in accordance with the present subject matter. The conductor segments may be inserted in four layers viz., layer 1, layer 2, layer 3, and layer 4. A pair of conductor segments constitutes two consecutive layers.

For example, conductor segments inserted in layer 1 and layer 2 constitute a first pair, the conductor segments inserted in layer 3 and layer 4 constitute a second pair, and so on. In one example, the stator 225 of the electrical machine 200 can have a 96 slot-16 pole design. The description, henceforth, is provided as an example with reference to the stator 225 having the 96 slot-16 pole design. For the purposes of explanation, the slots are numbered from 1 to 96 in counterclockwise direction, for illustrating the winding method. In said embodiment, each of the slots is divided in four layers for accommodating four conductor segments constituting two pairs. However, it may be noted that any number of pairs of conductor segments can be used with the arrangement as described herein.

Fig. 3 shows an arrangement of conductor segments in the slots of the stator core 275 from the first side and the second side, according to an embodiment of the present subject matter. A pair of conductor segments are inserted from the second side (or side B as shown Fig. 3) of the stator core 275 and the straight members of the conductor segments protrude outside from the first side (or side 'A' as shown in Fig. 3) of the stator core 275.

Similarly a second pair of conductor segments are inserted from the side 'A' of stator core 275 and the straight members of the conductor segments protrude outside from the side 'B' of the stator core 275. The straight member protruding outside from both the sides of the stator core 275 are twisted and welded to the protruding member of another conductor segments. In one embodiment, such joining can be done by brazing or soldering. In one example, the pairs of conductor segments inserted from the first side of the stator core 275 constitute odd coil groups and the pairs of conductor segments inserted from the second side constitute even coil groups. One odd coil group connected with one even coil group forms one phase winding.

Fig. 4a, Fig. 4b, Fig. 4c, Fig. 4d, Fig. 4e, and Fig. 4f shows a perspective view of different types of the conductor segments used in forming the stator windings, according to an embodiment of the present matter. In an example, the conductor segments have rectangular cross section. The conductor segments are formed into different predetermined profiles of conductor segments such as full pitch conductor segments, short pitch conductor segments, link conductor segments, lead start terminal conductor segments, and lead end terminal conductor segments.

Fig. 4a, Fig. 4b and Fig. 4c illustrate the full pitch, short pitch and the link conductors, respectively. In an example, these conductor segments are hairpin shaped used in the even and odd coil groups. The two arms of such hairpin shaped conductors may be referred to as limbs. As shown in the figure, two limbs are connected from one end to form a U shaped side, while the other ends of the limbs are free. The limbs of the full pitch conductors, the short pitch conductors, and the link conductors are separated by a gap of 5 slots, 4 slots and 5 slots, respectively in the stator core 275. The limbs of the full pitch and the short pitch conductors are inserted into two different slots so as to cover different layers of the slots, whereas the limbs of the link conductor segments is inserted into two different slots so as to cover same layers of the slots.

A lead start terminal conductor segment and a lead end terminal conductor segment are formed as shown in Fig. 4d. These conductor segments are used in the odd coil groups and include a single limb. Therefore, the limb of each of these conductor segments is inserted into the slot to cover a single layer of the slot. Fig. 4e and Fig. 4f show the lead start terminal conductor segment and the lead end terminal conductor segment respectively for the even coil groups. The limbs of these conductor segments are separated by a gap of 5 slots. The limbs of the lead start conductor segment are inserted into different slots to cover different layers of the slots, whereas the limbs of the lead end conductor segment is inserted into two different slots so as to cover same layers of the slots. Accordingly, it is understood that the insertion of any conductor segment indicates insertion of the corresponding limbs of the conductor segments into the slots.

Considering the example with 96 slots and 16 pole design of the stator 225, the full pitch conductor segments are inserted from one slot to another with five slots in between them. The full pitch conductor segments are inserted from the first side of the stator core 275 to form the odd coil group or from the second side of the stator core 275 to form the even coil group. The short pitch conductors are inserted from one slot to the other with four slots in between them. The short pitch conductors are inserted from both the sides of the stator core 275. The insertion of the short pitch conductors from both the sides, brings the take off terminal for the three phase stator winding, for example, the Red, Yellow, and Blue (R, Y, B) phases, to the first side of the stator core 275. The Red, Yellow, and Blue (R, Y, B) phases may be hereinafter referred to as first phase, second phase and the third phase respectively.

Further, the link conductors are inserted from one slot to the other with five slots in between them. The lead start terminal conductor segments for the odd and even coil groups are inserted in the slots to begin the coil group of a particular phase and the lead end terminal conductor segments for both coil groups are inserted in the slot to terminate the coil group of the particular phases. The full pitch conductors, the short pitch conductors, and the link conductors are inserted from both the sides of the stator core 275. The lead start terminal conductor segment and the lead end terminal conductor segments for the odd coil groups 1,3, 5 are inserted from the first side of the stator core 275. Similarly, the lead start terminal conductor segment and the lead end terminal conductor segments for the even coil groups are inserted from the second side of the stator core 275.

In an embodiment, the lead end terminal conductor segment and the lead start terminal conductor segment for the even coil groups are hairpin shaped and different from lead start terminal conductor segment and lead end terminal conductor segment for the odd coil groups. In addition, in one example, two limbs of such hairpin shaped conductor are of unequal length. The significance of such unequal length has been illustrated in the description of Fig. 5b and Fig. 5c.

Fig. 5a shows an electrical winding diagram of a first side coil group of the first phase, according to an embodiment of the present subject matter. In one exemplary implementation, the first side coil group forms a part of the odd coil group. A group of conductor segments are inserted into the slots from the first side of the stator core 275, and twisted and welded on the second side of the stator core 275 to form the first side coil group. Further, a group of conductor segments are inserted into the slots from the second side of the stator core 275, and twisted and welded in the first side of the stator core 275 to form the second side coil group. The second side coil group forms a part of the even coil group and has been elaborated in Fig. 5b.

In the example described herein, the first and second side coil groups as formed are not identical. However, it will be understood that in other embodiments of the present subject matter the coil groups can be identical. The first side coil group includes conductors such as full pitch conductors 5A, short pitch conductors 5B, link conductors 5C, lead start terminal conductor segment 5D, and lead end terminal conductor segment 5E. The full pitch conductor 5A, the short pitch conductor 5B, and the link conductors 5C are inserted from one slot to the other. The lead start terminal conductor segment 5D is inserted into the slot to begin the coil group of a particular phase. The lead end terminal conductor segment 5E is inserted into the slot to terminate the coil group of the same phase.

In said embodiment, a three phase (R, Y, and B) winding connection is established in the stator 225 by forming two or more coil groups for each phase. In one embodiment, the lead start terminal conductor segment 5D for the first phase is inserted in the lrt layer of the lrt slot from the first side of the stator core 275. The full pitch conductor 5A is inserted in 1st layer of the 85th slot to 2nd layer of the 91st slot from the first side of the stator core 275. Similarly, another full pitch conductor is inserted in 1st layer of the 73rd slot to 2nd layer of the 79th slot from the first side of the stator core 275. The full pitch conductors 5A are inserted in this pattern into the slots of the stator core 275 and are configured to produce maximum voltage during operation.

Furthermore, when seven full pitch conductors have been inserted into the slots from the first side of the stator core 275 after the lead start terminal conductor segment 5D, a short pitch conductor 5B is subsequently inserted in 1st layer of 2nd slot to 2nd layer of the 7th slot from the first side of the stator core 275. As the short pitch conductor 5B covers four slots in between the two limbs, the provision of the short pitch conductor 5B maintains a difference of one slot between the slot of insertion of the lead start terminal SD and slot of insertion of the short pitch conductor 5B, thereby preventing connection of the lead start terminal conductor segment 5D and the short pitch conductor 5B in the same slot. Further, the winding is continued and the full pitch conductors 5A are inserted in 2nd layer of 92nd slot to 1st layer of 86th slot from the side A, and this pattern is continued till the insertion of seven full pitch conductors into the slots of the stator core 275 in succession from the first side.

Subsequently, the link conductor 5C is inserted into the 2nd layer of the 8th slot to 2nd layer of the 14th slot from the first side of the stator core 275. The insertion of link conductor 5C facilitates connection of the seventh full pitch conductor 5A of the last set of full pitch conductors with a first full pitch conductor 5A of a forthcoming set of seven full pitch conductors. In addition, the link conductor 5C connects the protruding portions of the conductor segments within the same layer of two different slots. Accordingly, the first full pitch conductor 5 A of the forthcoming set of seven full pitch conductors is inserted into the slots from 1st layer of 20th slot to 2nd layer of 26th slot from the first side of the stator core 275. This pattern is continued for inserting another set of seven full pitch conductors into the slots.

Furthermore, a short pitch conductor 5B is inserted from 1st layer of the 8th slot to 2nd layer of 13th slot from the first side of the stator core 275.

In one embodiment, the provision of the short pitch conductor 5B maintains a gap of one slot between the slot of insertion of the link conductor 5C and the slot of insertion of the short pitch conductor SB, thereby preventing connection of the link conductor 5C and the short pitch conductor 5B in a same slot. Then, another set of seven full pitch conductors are inserted in succession. After the seven full pitch conductors have been inserted into the slots, a lead end terminal conductor segment 5E is inserted into 1st layer of 7th slot from the side A. The lead end terminal conductor segment 5E is taken out from the first side of the stator core 275.

The protruding portions of the conductor segments at the second side are first twisted to cover 3 slots in appropriate directions for each layer of the slot, to facilitate connection with the protruding portions of other conductor segments. Then, the protruding portion of the conductor segments outside the 1st layer of the 1st slot is welded with 2nd layer of the 91st slot on the second side of the stator core 275. Similarly, the portion of the conductor segment protruding outside the l5t layer of the 85th slot is welded with 2nd layer of the 79th slot on the second side of the stator core 275. In this manner, the conductor segments protruding outside the stator core 275 on the second side are twisted and welded to form the first side coil group 1 of the first phase. In the above referenced example, the first side coil group starts from 1st layer of the 1st slot from the first side of the stator core 275 and ends with 1st layer of the 7th slot on the first side of the stator core 275.

Fig. 5b illustrates an electrical winding diagram of second side coil group of R phase, according to an embodiment of the present subject matter. A group of conductor segments are inserted into the slots from the second side of the stator core 275, and twisted and welded on the first side of the stator core 275, to form the second side coil group. The second side coil group includes full pitch conductors 5A', short pitch conductors 5B', link conductors 5C, lead start terminal conductor segments 5D', and lead end terminal conductor segments 5E' as shown. The full pitch conductors 5A', short pitch conductors 5B' and the link conductors 5C are inserted from one slot to the other. The lead start terminal conductor segments 5D' are inserted from 3rd layer of one slot to 4th layer of the other slot and begin the coil group of a phase. The lead end terminal conductor segments 5E' are inserted from 4th layer of one slot to 4th layer of the other slot that terminates the coil group of the same phase.

The lead start terminal conductor segment 5D' of the first' phase for the second side coil group is inserted in the 3rd layer of the 1st slot to the 4th layer of 91st slot from the second side of the stator core 275, as shown in the Fig. 5b. The full pitch conductor 5A' is inserted in 3rd layer of the 85th slot to 4th layer of the 79th slot from the second side of the stator core 275. When seven full pitch conductors have been inserted into the slots from the second side of the stator core 275 after the lead start terminal conductor segment 5D', a short pitch conductor 5B' is further inserted in 3rd layer of 13th slot to 4th layer of the 8th slot from the second side. As mentioned before, the provision of the short pitch conductor 5B' maintains a difference of one slot between the slot of insertion of the lead start terminal 5D' and the slot of insertion of the short pitch conductor 5B', thereby preventing connection of the lead start terminal conductor segment 5D' and the short pitch conductor 5B' in a same slot.

Subsequently, the full pitch conductors are inserted in 3rd layer of 2nd slot to 4th layer of 92nd slot from the second side of the stator core 275, and this pattern is continued till the insertion of the seven full pitch conductors in succession. Then the link conductor 5C is inserted in the 3rd layer of the 14th slot to the 3rd layer of 20th slot from the second side of the stator core 275. The insertion of link conductor 5C facilitates connection of the seventh full pitch conductor 5B' of the last set of full pitch conductors with a first full pitch conductor 5B' of a forthcoming set of seven full pitch conductors. In addition, the link conductor 5C connects the protruding portions of the conductor segments of two different slots in a same layer.

Further, the full pitch conductors are inserted in the 3rd layer of 32nd slot to the 4th layer of 26th slot from the second side. This pattern is continued till the insertion of seven full pitch conductors into the slots. Then a short pitch conductor 5B' is inserted from the 3rd layer of the 19th slot to the 4th layer of H^slot from the second side. The provision of the short pitch conductor 5B' maintains a gap of one slot between the slot of insertion of the link conductor 5C and the slot of insertion of the short pitch conductor 5B\ thereby preventing connection of the link conductor 5C and the short pitch conductor 5B' in a same slot. Then, another set of seven full pitch conductors are inserted in succession from the second side.

Furthermore, when seven full pitch conductors have been inserted into the slots after the short pitch conductor 5B', the lead end terminal conductor segment 5E' is inserted in the 4th layer of the 7th slot to the 4th layer of the 13th slot from the second side. The limbs of the conductor segments protruding outside the slots on the first side are twisted to cover 3 slots in appropriate direction. The portion of the conductor protruding outside the 4th layer of the 91st slot is welded with 3rd layer of the 85th slot on the side 'A' of the stator core 275. Similarly, the portion of the conductor segments protruding outside the 4th layer of the 79th slot is welded with 3rd layer of the 73rd slot on the first side of the stator core 275. In this manner the conductor segments protruding outside the stator core 275 on the first side are twisted and welded to form the second side coil group of the first phase.

In the above example, the second side coil group starts from the 3rd layer of the 1st slot from the second side of the stator core 275 and ends with 4th layer of the 7th slot on the second side of the stator core 275. A portion of the lead end terminal conductor segment 5E' is taken out in the 4th layer of the 7th slot from the first side of the stator core 275. Similarly a portion of the lead start terminal conductor segment 5D' is taken out in the 3rd layer of the 1st slot from the first side of the stator core 275 for further connections, which has been explained in detail with reference to the description of Fig. 5c. In one embodiment, for such further connections, the limbs of the lead end terminal conductor segments 5E' and the lead start terminal conductor segments 5D' are of unequal length.

As is clear from the above description, the short pitch conductor segments and the link conductor segments facilitate in interconnection between the full pitch conductor segments of a particular coil group. As a result, the full pitch conductor segments form the coil group, which traverses around the hollow portion of the stator 225 two or more times and fills the various slots of the stator 225 to form a good quality winding.

. 5c shows the electrical winding diagram of the first phase with the first and second side coil groups, according to an embodiment of the present subject matter. The lead end terminal conductor segment 5E, which is inserted in the 1st layer of 7th slot of the first side coil group is joined on the first side of stator core 275 with the lead start terminal conductor segment 5D' which is inserted in the 3rd layer of the 1st slot of the second side coil group. The joining can be done by TIG welding, soldering, brazing, or any other joining technique. The first phase winding starts with the 1st layer of the 1st slot and ends with the 4th layer of the 7th slot as R-R' as shown.

The above methodology for inserting conductor segments, as explained, brings the lead end terminal conductor segments and lead start terminal conductor segments on the first side of the stator core 275. In the similar manner, the conductor segments are inserted in their respective slots for the second phase and end conductors are taken on the first side of the stator core 275 for forming third and fourth coil groups. The second phase winding starts with the 1st layer of the 11th slot and ends with the 4th layer of the 17th slot as Y-YSimilarly, the conductor segments are inserted in their respective slots for the third phase and the end conductors are taken on the first side of the stator core 275 for forming coil groups 5 and 6. The third phase winding starts with thelst layer of the 21st slot and ends with the 4th layer of the 27th slot as B-Bth.

In said implementation, the lead end terminal conductor segments and the lead start terminal conductor segments of the three phases, i.e., the first, second, and third phases, are connected appropriately to form the three phase stator winding. The above arrangement for inserting different types of conductor segments brings the lead end terminal conductor segments of every coil group and every phase to the first side of the stator core 275. In one example, a phase angle of 120 degrees is maintained between any two phases amongst the three phases.

In an implementation, the coil groups within the same phase have a pre-determined electrical angular difference to reduce an electromagnetic noise. In one implementation, the conductor segments are made of copper. However, it may be noted that the conductor segments can be made of any other metal as well, for example, aluminium or copper clad aluminium. It is also possible to use complex conductor segments having both rectangular cross section and round cross section or any other conductor portion which suits the stator slot profile.

Fig. 6a shows the electrical winding connection of the conductor segments in the stator 225 according to the present subject matter. The connection is established in such a way that the twisting and welding of the conductor segments occur at the both sides of the stator core 275 axially for every phase. This kind of electrical connection established on both sides is convenient and does not interfere with one another, enabling easy manufacturability. In one implementation, the end connections are made for star configuration as shown. However the end connections can be connected in any other configuration to meet the output performance or application related requirements of the electrical machine 200.

Fig. 6b shows an exemplary view of the stator core 275 arranged in four layers with the three phase winding, according to an embodiment of the present subject matter. As will be understood by a person skilled in the art, Fig. 6b may be explained for various views of the stator core 275. As mentioned before, the lead end terminal conductor segments of each phase lies to the first side of the stator core 275. Accordingly, a downward side of the front view of the stator core 275 represents the first side, whereas an upward side of the stator core 275 represents the second side. Likewise, the top view depicts the second side, whereas the bottom side depicts the first side.

Fig.7 illustrates an exemplary view of the winding of three pairs of conductor segments inserted into the slots of stator core 275 alternately from the first side and the second side of the stator 225, according to an embodiment of the present subject matter. In this case, the conductor segments of two pairs, that is a first pair and a third pair, are welded on one side of the stator 225 whereas conductor segments of the remaining one pair, that is, a second pair, are welded on the other side of the stator 225. Similarly, it is also possible to weld and twist multiple pairs of conductor segment in the stator 225.

present method of winding the stator core 275 as described herein provides a reduction in the size of the stator 225, reduction in noise levels during operation and an enhancement in performance of the electrical machine 200 implementing the stator 225. Further, as the stator winding is formed on both the sides of the stator core 275, complexity in manufacturing the stator 225 is significantly reduced. Further, the winding arrangement as described for the stator core 275 provides a higher power output for the same size of the stator 225.

Without limiting the scope of the present subject matter, the aforementioned winding arrangement for the stator 225 may also be extended to cover winding arrangement in a rotor and other similar members of electrical machines. Further, although the subject matter has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. As such, the spirit and scope of the disclosed subject matter should not be limited to the description of the embodiment contained therein.

I/We claim:

1. A method of winding an electrical member (205,225) of an electrical machine (200), the method comprising:

inserting at least two conductor segments from a first side of the electrical member (205, 225) and at least two other conductor segments from a second side of the electrical member (205, 225), wherein a limb of each of the at least two conductor segments is inserted in a slot in the electrical member (205, 225) from the first side and protrudes from the second side and a limb of each of the at least two other conductor segments is inserted in the slot in the electrical member (205, 225) from the second side and protrudes from the first side;

connecting each of the limbs protruding from the second side to a limb of another conductor segment protruding from the second side to form in part a first side coil group, and connecting each of the limbs protruding from the first side to a limb of another conductor segment protruding from the first side to form in part a second coil group; and
joining the first side coil group and the second side coil group to form a phase winding.

2. The method as claimed in claim 1, wherein the conductor segments comprise at least one of full pitch conductor segments, short pitch conductor segments, link conductor segments, a lead end terminal conductor segments, and a lead start terminal conductor segments.

3. The method as claimed in claim 2, wherein inserting the conductor segments further comprises inserting the link conductor segments and the lead end terminal conductor segments to cover identical layers in the slots.

4. The method as claimed in claim 2, wherein inserting the conductor segments further comprises inserting the full pitch conductor segments, the short pitch conductor segments, and the lead end terminal conductor segments to cover separate layers in the slots.

5. The method as claimed in claim 1, wherein the connecting further comprise connecting the limbs by at least one of welding, brazing and soldering.

6. The method as claimed in claim 1, wherein the joining further comprises joining the first coil group and the second coil group by at least one of welding, brazing and soldering.

7. An electrical machine (200) comprising an electrical member (205, 225), wherein the electrical member (205,225) comprises:

a plurality of slots disposed in a lateral wall of the electrical member (205, 225), wherein the plurality of slots extend longitudinally in an axial direction of the electrical member (205, 225) from a first side to a second side of the electrical member (205,225); and

a plurality of conductor segments inserted into one of the plurality of slots to form a winding, wherein a limb of each of at least two conductor segments from among the plurality of conductor segments is inserted into a slot from the first side of the electrical member (205, 225) and a limb of each of at least two other conductor segments from among the plurality of conductor segments is inserted into the slot from the second side of the electrical member (205,225).

8. The electrical machine (200) as claimed in claim 7, wherein the electrical member (205, 225) is a stator of the electrical machine (200).

9. The electrical machine (200) as claimed in claim 7, wherein each of the plurality of slots accommodates at least four conductor segments.

10. The electrical machine (200) as claimed in claim 7, wherein the conductor segments exhibit one of a polygonal cross section and a circular cross section.

11. The electrical machine (200) as claimed in claim 7, wherein the conductor segments comprise at least one of full pitch conductor segments, short pitch conductor segments, link conductor segments, a lead end terminal conductor segment and a lead start terminal conductor segment.

12. The electrical machine (200) as claimed in claim 11, wherein the lead start terminal conductor segments and the lead end terminal conductor segment are segments hairpin-shaped and each of the lead start terminal conductor segments and the lead end terminal conductor segments comprises a plurality of limbs of unequal length.

13. The electrical machine (200) as claimed in claim 7 is an alternating current (AC) machine.

14. The electrical machine (200) as claimed in claim 7, wherein the electrical member (225) is stator (225).