DESC:WOUND CORE ASSEMBLY FOR PERMANENT MAGNET SYNCHRONOUS RELUCTANCE MOTOR
CROSS REFERENCE TO RELATED APPLICTIONS
The present application claims priority from Indian Provisional Patent Application No. 202221040546 filed on 15/07/2022, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
Generally, the present disclosure relates to a wound core assembly for a motor. Particularly, the present disclosure relates to a wound core assembly for a permanent magnet synchronous reluctance motor.
BACKGROUND
Recently, traction motors are increasingly being used due to adoption of electric vehicles. AC motors, such as permanent magnet synchronous reluctance motor are one of the good options to serve as traction motor in electric vehicles due to their high performance and efficiency. As known in the art, the electric motor has two main parts, a stator, and a rotor, concealed within a motor casing.
Conventionally, the electric motors size is proportional to the power output of the electric motor. The electric motors with higher power output would require bigger components to handle increased currents, bigger windings to generate more electric field and additional surface for heat dissipation. The electric motors used for application in electric vehicles are required to be powerful, thus, such electric motors have larger windings and other electrical components.
However, the electric vehicles have space and weight constraints. The space available in the electric vehicle is limited, thus, the motor size cannot be increased more than a certain limit. Similarly, a bigger electric motor installed in an electric vehicle would be heavier, thus, adding more weight to the electric vehicle. This further decreases the overall efficiency of the electric vehicle.
Furthermore, the conventional winding of the electric motor is done using cylindrical copper wires. The conventional windings of the electric motor have low fill factor, low efficiency and high losses. Furthermore, the conventional windings have multiple joint-points of the copper wire resulting in multiple hotspots in the wound core assembly, resulting in heating of the stator. Furthermore, the conventional windings have direct connection of copper wires in wound core assembly resulting in imbalanced 3-phases connection and improper loading of current. Such imbalance in the current results in imbalanced torque and increased vibrations in the electric motor.
Thus, there exists a need for a wound core assembly of permanent magnetic synchronous reluctance motor that overcomes the one or more problems associated with the winding of the permanent magnetic synchronous reluctance motor as set forth above.
SUMMARY
An object of the present disclosure is to provide a wound core assembly for a permanent magnet synchronous reluctance motor with improved efficiency and compact size.
In accordance with first aspect of the present disclosure, there is provided a wound core assembly for a permanent magnet synchronous reluctance motor, wherein the wound core assembly comprises a stator, a plurality of flat wire coils and a plurality of wedges. The stator comprises a plurality of teeth, wherein each tooth of the plurality of teeth comprises a tooth face and a close end. In the stator, adjacent teeth faces are configured to form slot openings. The plurality of flat wire coils are inserted through the tooth face into the slot openings. The plurality of wedges configured inside wound core to close the slot openings.
The present disclosure provides a wound core assembly of a permanent magnet synchronous reluctance motor with increased efficiency. Advantageously, the disclosed wound core assembly is compact in size. Furthermore, the disclosed wound core assembly is advantageous in terms of generating higher flux per unit of copper weight inside the electric motor. Advantageously, the disclosed wound core assembly is lighter in weight compared to a conventional wound core of similar power output. Furthermore, the disclosed wound core assembly does not comprise any overhang windings. Furthermore, the disclosed wound core assembly is advantageous in terms of eliminating hot spots inside the windings.
Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments constructed in conjunction with the appended claims that follow.
It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
FIG. 1 illustrates a perspective view of a wound core assembly of a permanent magnet synchronous reluctance motor, in accordance with an embodiment of the present disclosure.
FIG. 2 illustrates a perspective view of the stator with one flat wire coil, in accordance with an embodiment of the present disclosure.
FIG. 3 illustrates a perspective view of the plurality of flat wire coils winded on bobbins, in accordance with an embodiment of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognise that other embodiments for carrying out or practising the present disclosure are also possible.
The description set forth below in connection with the appended drawings is intended as a description of certain embodiments of a motor of an electric vehicle and is not intended to represent the only forms that may be developed or utilised. The description sets forth the various structures and/or functions in connection with the illustrated embodiments; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimised to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.
The terms “comprise”, “comprises”, “comprising”, “include(s)”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, system that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or system. In other words, one or more elements in a system or apparatus preceded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings and which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
The present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.
As used herein, the terms ‘electric motor’, ‘motor’, ‘permanent magnet synchronous reluctance motor’, ‘PMSR motor’, ‘IPM-SynRM’ and ‘PMSRM’ are used interchangeably and refer to electric motors capable of being implemented in an industrial or automobile application, such as on the work machine or other vehicle. The permanent magnet synchronous reluctance motor is a type of hybrid electric motor that combines the features of Permanent Magnet Synchronous Motor (PMSM) and Reluctance Motor (RM). The PMSRM has permanent magnets in the rotor, which generates a constant magnetic field, and the PMSRM relies on the principle of magnetic reluctance to create a rotating field within the motor. It would be appreciated that combination of technologies allows the PMSRM to achieve higher efficiency and better performance than other types of electric motors. In general, the stator of the PMSRM typically contains three-phase windings, which are used to generate alternating current that powers the electric motor. Typically, the rotor is made of iron or other magnetic materials, contains the permanent magnets that generate the magnetic field. It would be appreciated that the PMSRM can be modified to comprise active cooling system, such as a liquid cooling system. It would be appreciated that such cooling system would employ a coolant liquid circulating through the well-defined coolant flow paths inside the motor to dissipate the heat generated by the electric motor during operation.
As used herein, the terms ‘electric vehicle’, ‘EV’, and ‘EVs’ are used interchangeably and refer to any vehicle having stored electrical energy, including the vehicle capable of being charged from an external electrical power source. This may include vehicles having batteries which are exclusively charged from an external power source, as well as hybrid-vehicles which may include batteries capable of being at least partially recharged via an external power source. Additionally, it is to be understood that the ‘electric vehicle’ as used herein includes electric two-wheeler, electric three-wheeler, electric four-wheeler, electric pickup trucks, electric trucks and so forth.
As used herein, the terms ‘rotor’ and ‘rotor assembly’ are used interchangeably and refer to the rotating part of the motor which is typically made of iron or other magnetic materials. It contains the permanent magnets and the reluctance winding that generate the magnetic field used to drive the rotor. The rotor converts electrical energy supplied to the stator into mechanical energy.
As used herein, the terms ‘stator’ and ‘stator assembly’ are used interchangeably and refer to the stationary part of a motor which provides a magnetic field that drives the rotating armature. The stator may act as a field magnet.
As used herein, the term “wound core” and “wound core assembly” are used interchangeably and refers to an assembly of windings that are wound around a laminated core to form stator assembly. The stator is typically made of magnetic material such as iron or steel. It would be appreciated that the winding arrangement and core design play a crucial role in the motor's operation. Notably, the stator windings are distributed along the laminated core, forming coils that are wound around the core's teeth. Optionally, the windings are typically made of copper or aluminium wire, and they carry the electric current that generates the magnetic field required for motor operation. It would be appreciated that the wound core design in a PMSRM allows for a high level of control over the magnetic field distribution within the motor. By adjusting the winding arrangement and the current flowing through the windings, it is possible to optimize the motor's performance characteristics, such as torque, speed, and efficiency.
As used herein, the terms “bus bar” and “busbars” are used interchangeably and refers to a conductive metal strip or thick wire used to connect the ends of the plurality of coils in the motor winding. The busbar serves as a common electrical connection point for multiple coils in the wound core.
As used herein, the terms “terminal”, “ends”, “coil ends” are used interchangeably and refers to the ends of the winding of the plurality of flat wire coils.
As used herein, the terms “plurality of teeth”, “teeth” and “tooth arrangement” are used interchangeably and refers to inward extending structure inside the stator configured to receive hollow portion of the plurality of winding coils.
As used herein, the term “slot opening”, “slot openings” and “plurality of slot openings” refers to the empty space between the adjacent teeth configured to receive the winding portion of the flat wire coil, once the coil is being inserted onto the tooth. It is to be understood that each slot opening would receive one side of each of the two adjacent coils which are being inserted onto two adjacent teeth.
As used herein, the terms “flat wire coil”, “winding coil”, “coil” and “plurality of coils” are used interchangeably and refers to an electromagnetic coil winded using a flat wire. It is to be understood that the flat wire refers to a metal wire with rectangular cross section. It would be appreciated that the wire with rectangular cross section area would be wounded more efficiently as no space would be left in between the surfaces of the wires wounded in a coil. In other words, the conductor used is a flat wire rather than a traditional round wire. Instead of a circular cross-section, the flat wire has a rectangular or square shape, with a significantly greater width compared to its thickness. It would be appreciated that the flat wire coil would improve the space efficiency of the winding as the rectangular or square shape allows for tighter packing of the winding turns, maximizing the use of available space within the coil or winding area.
As used herein, the terms “plurality of wedges”, “wedges” and “magnetic wedges” are used interchangeably and refers to stator slot wedges or components that are inserted into the teeth of the stator winding in an electric motor. Advantageously, the plurality of wedges improves the performance and efficiency of the motor by reducing magnetic losses and improving the magnetic flux distribution within the stator core.
As used herein, the term “bobbin” refers to a rectangular shaped hollow device on which a coil is wound. In other words, the wire is wound around the bobbin to form the coil.
As used herein, the terms “magnetic composite material”, “composite material” and “magnetic material” are used interchangeably and refers to a composite material with magnetic properties. It would be appreciated that the magnetic composite material may comprise at least one of: a magnetic metal, a binder resin, a filler and so forth.
As used herein, the terms “end lamination”, “end-lamination” and “lamination” are used interchangeably and refers to a layer of insulating material placed at the end of the stator windings to electrically and mechanically insulate the winding from other components of the motor.
Figure 1, in accordance with an embodiment describes a perspective view of a wound core assembly 100 for a permanent magnet synchronous reluctance motor. The wound core assembly 100 comprises a stator 102, a plurality of flat wire coils 116 and a plurality of wedges 114. The stator 102 comprises a plurality of teeth 104. Each tooth 104 of the plurality of teeth comprises a tooth face 106 and a close end 108. The adjacent teeth faces are configured to form slot openings 110. The plurality of flat wire coils 116 inserted through the tooth face 106 into the slot openings 110. The plurality of wedges 114 configured inside wound core to close the slot openings 110.
The wound core assembly 100, as disclosed in the present disclosure is advantageous in terms of reducing size of the motor as the wound core assembly 100 is compact in size. Furthermore, the disclosed wound core assembly 100 is advantageous in terms of generating higher flux per unit of copper weight inside the electric motor. Advantageously, the disclosed wound core assembly 100 is lighter in weight compared to a conventional wound core of similar power output. Furthermore, the disclosed wound core assembly 100 does not comprise any overhang windings. Furthermore, the disclosed wound core assembly 100 is advantageous in terms of eliminating hot spots inside the windings.
In an embodiment, the stator 102 is a non-segmented stator, wherein the plurality of teeth 104 are formed in the stator 102 during the manufacturing of the stator 102. It would be appreciated that the stator 102 may be manufactured by stamping and stacking of multiple layers of metal sheet. Alternatively, the stator 102 may be manufactured with any other method suitable for such purpose. It would be appreciated that the plurality of teeth 104 projecting inward from the stator would form the slot opening 110. In other words, the slot openings 110 are the vertical gap between the adjacent teeth of the plurality of teeth 104. As used above, the close end 108 refers to an originating end of the plurality of teeth 104 from the stator 102. In other words, the close end 108 refers to a location on the stator 102 from which the teeth 104 originates. Similarly, the tooth face 106 refers to the open end of each of the tooth of the plurality of teeth 104 projecting inward.
In an embodiment, when the plurality of flat wire coils 116 are inserted through the tooth face 106 into the slot openings 110, hollow core of each of the coil 106 is received over the tooth 104 through tooth face 106 and wounded portion of the coil is received into the slot opening 110.
In an embodiment, the plurality of teeth 104 comprises at least one notch at each surface of the tooth inside the slot openings 110 near the tooth face 106. The plurality of wedges 114 are vertically inserted into the notches of the adjacent teeth facing each other. It would be appreciated that once the plurality of wedges 114 are inserted into the notches inside the wound core, the slot openings 110 are closed. Such closing of the slot openings 110 would advantageously prevent the plurality of flat wire coils 116 to come out from the slot openings 110 during the operation of the motor.
In an embodiment, the plurality of wedges 114 for closing the slot openings 110 are made of a magnetic composite material. Specifically, the magnetic composite material may contain 2-12% Glass, 13-23% Resin and 70-80% Iron, by weight. Advantageously, the plurality of wedges 114 may improve the performance and efficiency of the motor by reducing magnetic losses and improving the magnetic flux distribution within the wound core assembly 100. Furthermore, the plurality of wedges 114 may increase the fill factor of the slot opening 110. By occupying some of the available space within the plurality of teeth 104, the plurality of wedges 114 reduce the size of the slot openings 110 and increase the amount of copper filling, leading to better utilization of the magnetic field and improved motor performance. Furthermore, the plurality of wedges 114 may minimize the leakage of magnetic flux from the plurality of teeth 104. The plurality of wedges 114 guide the magnetic flux lines and prevent them from escaping through the slot openings 110. Such containment of magnetic flux within the wound core improves the efficiency of the motor by reducing energy losses. The plurality of wedges 114 may reduce undesirable harmonics and noise in the motor by shaping and controlling the magnetic flux distribution. The plurality of wedges 114 contribute to minimizing magnetic vibrations and audible noise generated during motor operation. Furthermore, the plurality of wedges 114 may act as insulation between rotor and stator 102.
In an embodiment, each flat wire coil 116 of the plurality of flat wire coils comprises a bobbin 112. Specifically, each of the flat wire coil 116 is formed by winding flat wires around the bobbin 112. It would be appreciated that the winding the flat wire coil 116 around the bobbin 112 would provide insulation between the tooth 104 and the flat wire coil 116. Advantageously, the bobbin 112 would provide mechanical support to the flat wire coil 116. In an embodiment, the bobbin 112 is rectangular in shape. Advantageously, the rectangular shape ensures snug fit of the bobbin 112 on the tooth 104.
In another embodiment, the flat wire coil 116 is wounded around any other suitable insulating material such as paper, plastic lamination and so forth.
In an embodiment, the rectangular cross-section of the flat wire used for the winding of the plurality of flat wire coils 116 has a height to width ratio of 2:3. In an example, the flat wire coil 116 has a height of 2 mm and width of 3 mm. Advantageously, the flat wire coil 116 improves the compactness of the wound core assembly 100 resulting into compact motor. Advantageously, the flat wire coil 116 allows tighter packing of the winding turns, maximizing the use of available space within the coil or winding area. Furthermore, the flat wire coils 116 have improved heat dissipation capabilities compared to round wire coils due to their larger surface area. Advantageously, the wider cross-section of flat wire used in the flat wire coils 116 enables it to carry higher electrical currents without excessive resistive losses, resulting into increase of current carrying capacity. Advantageously, the wider surface area of the flat wire reduces the skin effect, allowing for more efficient current distribution throughout the wire.
In an embodiment, the tooth face 106 comprises a groove 118 to reduce cogging torque. Advantageously, each tooth face 106 comprises one groove 118 to reduce the cogging torque in the motor. Notably, the cogging torque is a fluctuating or pulsating torque that occurs when the magnetic poles align with the teeth of the stator, causing resistance to rotation and impacting the motor's smoothness of operation. Advantageously, the grooves 118 disrupt the alignment of the magnetic poles and reduce the interaction between the magnetic poles and the teeth, thereby minimizing cogging torque.
In an embodiment, the wound core assembly 100 comprises a pair of busbars configured to connect end terminals of the plurality flat wire coils 116. Specifically, in an embodiment, the pair of busbars is a uniformly routed busbar. Advantageously, the pair of busbars connecting the terminals of the plurality flat wire coils 116 would eliminate the overhang winding in the stator assembly, reducing the size of the stator assembly. Optionally, the busbars are uniformly routed at vertical ends 120a, 120b of the stator 102 connecting the end terminals of the plurality flat wire coils 116.
In an embodiment, the stator 102 comprises end-lamination fixed at vertical ends 120a, 120b of the stator 102 covering the plurality of teeth 104. Advantageously, the end-lamination prevents flaring of the plurality of teeth 104. In an embodiment, the end-lamination comprises a plurality of inward extensions configured to extend into the slot openings 110 between the adjacent flat wire coils 116. Advantageously, the plurality of inward extensions mechanically supports the plurality of flat wire coils 116.
Figure 2, in accordance with an embodiment, describes a perspective view of the stator 102 with a flat wire coil 116 inserted into the tooth 104. As shown in the figure, the flat wire coil 116 is inserted into the tooth 104 from the tooth face 106 towards the close end 108. Optionally, the flat wire coil 116 snugly fits on the tooth 104.
Figure 3, in accordance of an embodiment, describes a perspective view of the plurality of flat wire coils 116 wound around bobbins 112. The plurality of flat wire coils 116 wound around bobbins 112 are inserted into the plurality of teeth 104.
In the description of the present invention, it is also to be noted that, unless otherwise explicitly specified or limited, the terms “disposed,” “mounted,” and “connected” are to be construed broadly, and may for example be fixedly connected, detachably connected, or integrally connected, either mechanically or electrically. They may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Modifications to embodiments and combination of different embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a non- exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural where appropriate.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the present disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

,CLAIMS:WE CLAIM:
1. A wound core assembly (100) for a permanent magnet synchronous reluctance motor, wherein the wound core assembly (100) comprises:
- a stator (102), comprising a plurality of teeth (104), wherein each tooth (104) of the plurality of teeth comprises a tooth face (106) and a close end (108), and wherein adjacent teeth faces are configured to form slot openings (110);
- a plurality of flat wire coils (116) inserted through the tooth face (106) into the slot openings (110); and
- a plurality of wedges (114) configured inside wound core to close the slot openings (110).
2. The wound core assembly (100) as claimed in claim 1, wherein each flat wire coil (116) of the plurality of flat wire coils comprises a bobbin (112).
3. The wound core assembly (100) as claimed in claim 1 and 2, wherein each flat wire coil (116) is formed by winding flat wires around the bobbin (112).
4. The wound core assembly (100) as claimed in claim 1 to 3, wherein the bobbin (112) is rectangular in shape.
5. The wound core assembly (100) as claimed in claim 1 to 4, wherein the plurality of wedges (114) for closing the slot openings (110) are made of a magnetic composite material.
6. The wound core assembly (100) as claimed in claim 5, wherein the magnetic composite material contains 2-12% Glass, 13-23% Resin and 70-80% Iron, by weight.
7. The wound core assembly (100) as claimed in claim 1 to 6, wherein rectangular cross-section of the flat wire has a height to width ratio of 2:3.
8. The wound core assembly (100) as claimed in claim 1 to 7, wherein the tooth face (106) comprises a groove (118) to reduce cogging torque.
9. The wound core assembly (100) as claimed in claim 1 to 8, wherein the wound core assembly (100) comprises a pair of busbars configured to connect end terminals of the plurality flat wire coils (116).
10. The wound core assembly (100) as claimed in claim 9, wherein the pair of busbars is a uniformly routed busbar.
11. The wound core assembly (100) as claimed in claim 1 to 10, wherein the stator (102) comprises end-lamination fixed at vertical ends (120a, 120b) of the stator (102) covering the plurality of teeth (104).
12. The wound core assembly (100) as claimed in claim 11, wherein the end-lamination comprises a plurality of inward extensions configured to extend into the slot openings (110) between the adjacent flat wire coils (116).