DESC:THREE AIR-GAP MOTOR
CROSS REFERENCE TO RELATED APPLICTIONS
The present application claims priority from Indian Provisional Patent Application No. 202221049853 filed on 31/08/2022, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
Generally, the present disclosure generally relates to a motor for an electric vehicle. Particularly, the present disclosure relates to a three air-gap motor for an electric vehicle.
BACKGROUND
Recently, electric vehicles have emerged as an alternative to conventional vehicles using gasoline diesel, and similar fossil fuels. Electric vehicles require traction motors to convert the electrical energy into mechanical energy for driving the vehicle. There are multiple types of electric motors being used in electric vehicles. Some known types of electrical motors are radial flux motors and axial flux motors. The radial flux motors are more commonly used as they are known for a longer time, however, radial flux motors have limitations such as longer axial length, low power and torque density, and higher losses and weight.
The axial flux motors overcome these limitations, because, in the axial flux motor, the direction of the lines of magnetic flux that are cut during the operation of the motor is parallel to the rotational axis of the motor. The axial flux motors have characteristics including small axial length, higher power and torque density, lesser losses, and lesser weight compared to radial flux motors.
The axial flux motor comprises a stator having a plurality of wound core teeth or stator assemblies arranged circumferentially. The wound core tooth comprises a bobbin, a core, and conductors wound over the bobbin. However, the stator of the axial flux motor is difficult to assemble due to the requirement of a segmented design. Moreover, the power density is limited by the size and weight of the motor. Furthermore, the axial flux motors have thermal issues and suffer lower efficiency at high speeds. To overcome the limitations of the radial flux motors and the axial flux motors, hybrid flux motors have been developed as a solution combining the advantages of the radial flux motors and the axial flux motors. However, the hybrid flux motors are highly complex to design. Moreover, the hybrid flux motors are difficult to assemble due to their complex structure and components. Moreover, the hybrid flux motors also suffer the limitations of size and weight, as the compactness of the motor reduces with an increase in the power output. Moreover, the hybrid flux motors suffer reduced flux utilization and increased noise and vibrations due to the inefficiencies in the design. Such problems might even lead to motor failure in some cases.
Furthermore, the motors of electric vehicles generally use neodymium magnets such as Neodymium-iron-boron (NdFeB) magnets in the rotor assemblies. However, in the case of the hybrid flux motors, as the cost of the motor is already high compared to other motors, the use of such expensive magnets becomes even more impractical and cost-inefficient.
Therefore, there exists a need for an improved motor for an electric vehicle that overcomes one or more problems associated with the conventional electric flux motor as set forth above.
SUMMARY
An object of the present disclosure is to provide a three air-gap motor for an electric vehicle.
Another object of the present disclosure is to provide a three air-gap hybrid flux motor of an electric vehicle with increased efficiency and power density.
In accordance with an aspect of the present disclosure, there is provided a three air-gap motor for an electric vehicle. The three air-gap motor for an electric vehicle comprises a motor casing, a stator assembly, a radial-flux rotor, a pair of axial-flux rotors, and a motor shaft. The radial-flux rotor and the pair of axial-flux rotors comprises a plurality of permanent magnet blocks. The radial-flux rotor is mounted on the motor shaft in a radially inward direction of the stator assembly. The pair of axial-flux rotors are mounted on the motor shaft in mutually opposite axial directions sandwiching the stator assembly.
The present disclosure provides a three air-gap motor with improved efficiency and power density. Advantageously, the present invention provides an easy-to-assemble and disassemble three air-gap hybrid flux motor. Furthermore, the three air-gap motor has lower non-flux weight i.e., low weight of components that are not generating any flux, resulting in increased power density and efficiency. Furthermore, the three air-gap motor comprises hybrid magnetic flux, i.e., magnetic flux in both radial and axial directions. Beneficially, the three air-gap motor has the magnetic flux in three directions comprising radially inward and mutually opposite axial directions. Beneficially, the three air-gap motor utilizes the magnetic flux directed in the three directions for rotating the rotor resulting in improved torque output. Advantageously, the three air-gap motor is cost-efficient in manufacturing and provides ease of servicing and maintenance. Beneficially, the three air-gap motor efficiently utilizes the space inside the motor casing resulting in compact size despite increased power density. Beneficially, the three air-gap motor is suitable for use in high-power applications such as use in the powertrain of electric vehicles. Beneficially, the three air-gap motor is advantageous in terms of reducing flux leakage and maximizing flux utilization resulting in higher power density and efficiency. Beneficially, the three air-gap motor has reduced vibrations.
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:
Figure 1 illustrates a perspective view of a three air-gap motor for an electric vehicle, in accordance with an embodiment of the present disclosure.
Figure 2 illustrates an exploded view of the components of the three air-gap motor for an electric vehicle, in accordance with an embodiment of the present disclosure.
Figure 3 illustrates a perspective view of the two-part stator tooth along with flux coil, 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 recognize that other embodiments for carrying out or practicing 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 three air-gap hybrid flux motor and is not intended to represent the only forms that may be developed or utilized. 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 minimized 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, or 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 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 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 that 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-wheelers, electric three-wheelers, electric four-wheelers, electric pickup trucks, electric trucks, and so forth.
As used herein, the terms “electric motor”, “motor”, “hybrid motor”, “hybrid flux motor”, “three air-gap motor” and “radial-axial flux motor” 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 three air-gap flux motor is a type of electric motor that combines the radial and axial flux configurations. The three air-gap flux motor comprises permanent magnets arranged radially around the stator and permanent magnets arranged axially along the stator. The three air-gap flux motors combine the advantages of both radial and axial configurations, such as the high torque density of radial flux motors and the high efficiency of axial flux motors. The three air-gap flux motor comprises a combination of axial flux rotors and radial flux rotors.
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 rotors (the rotating component of the motor). The stator may act as a field magnet. The stator typically consists of a disc-shaped structure with coil windings. The coil windings, also called stator windings, are responsible for generating a magnetic field when electric current passes through them. The magnetic field produced by the stator interacts with the permanent magnets on the rotor to induce rotation.
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 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 term “motor casing” refers to the outer shell of an electric motor for providing a protective enclosure for the motor's internal components, such as the windings, bearings, shaft, etc.
As used herein, the term “front-end case” refers to a part of the casing that is located at the front of the motor and generally houses the motor's power connection, such as the terminal block or connector.
As used herein, the term “rear-end case” refers to a part of the casing that is located at the back of the motor that houses the output shaft of the motor.
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. The stator of the flux motor typically consists of a disk-shaped structure with coil windings. The coil windings are typically placed in slots or grooves on the stator disk. The stator windings are responsible for generating a magnetic field when electric current passes through them. The magnetic field produced by the stator interacts with the permanent magnets on the rotor to induce rotation.
As used herein, the term “radial-flux rotor” refers to a type of rotor in an electric motor in which the magnetic flux lines are extending radially outwards from the centre of the rotor.
As used herein, the term “axial-flux rotor” refers to a type of rotor in an electric motor in which the magnetic flux lines are extending from the front to the back of the rotor.
As used herein, the term “motor shaft” refers to a cylindrical component extending from the motor central portion along the longitudinal axis for transferring the mechanical power generated within the motor to other devices or systems.
As used herein, the terms “wound core tooth”, “two-part stator tooth”, “two-part tooth”, and “tooth” are used interchangeably and refer to a component of the stator that generates and shapes the magnetic field and contributes to the motor’s performance. It is to be understood that multiple wound core teeth are arranged in a disc plane to form a segmented stator assembly. The two-part metallic core serves as a path for the magnetic flux within the stator of the motor providing a low reluctance path for the magnetic field generated by the stator windings, allowing efficient transfer of magnetic energy between the stator and rotor. It is to be understood that the design of the two-part stator tooth, including its shape and size may be optimized to provide a balance between magnetic efficiency, mechanical strength, and minimizing losses. The two-part stator tooth contributes to the overall performance, efficiency, and power density of the hybrid flux motor.
As used herein, the term “axial-flux segment” refers to a segment of the two-part stator tooth that guides the magnetic flux in mutually opposite axial directions.
As used herein, the term “radial-flux segment” refers to a segment of the two-part stator tooth that guides the magnetic flux in radial directions.
As used herein, the term “axial-flux face” refers to a face of the axial-flux segment of the two-part stator tooth that guides the magnetic flux in an axial direction.
As used herein, the term “outer face” refers to the face of the axial-flux segment of the two-part stator tooth that is faced toward a motor casing. It is to be understood that the outer face is fixed on the motor casing and provides mechanical support to the stator assembly during the operation of the hybrid flux motor.
As used herein, the term “interlocking face” refers to a face of the axial-flux segment of the two-part stator tooth that comprises a locking mechanism for securing the radial-flux segment into the axial-flux segment to form the two-part stator tooth.
As used herein, the term “radial-flux face” refers to a face of the radial-flux segment of the two-part stator tooth that guides the magnetic flux in a radial direction.
As used herein, the term “locking protrusion face” refers to a face of the radial-flux segment of the two-part stator tooth that comprises a locking mechanism for securing the radial-flux segment into the axial-flux segment to form the two-part stator tooth.
As used herein, the term “side face” refers to a face of the radial-flux segment that complements the axial-flux face of the axial-flux segment of the two-part stator tooth.
As used herein, the term “locking protrusion” refers to a protruding mechanical element present on the radial-flux segment for locking into the corresponding recess present on the axial-flux segment for preventing the relative motion between the radial-flux segment and the axial-flux segment.
As used herein, the term “locking groove” refers to a recessed cavity present on the axial-flux segment for receiving the corresponding protruding element present on the radial-flux segment for preventing the relative motion between the radial-flux segment and the axial-flux segment.
As used herein, the terms “flux coil”, and “magnetic flux coil” are used interchangeably and refer to a coil of wire that is used to generate a magnetic field.
As used herein, the term “surface extensions” refers to an extended surface that functions similarly to the main surface from which it is extended. It is to be understood that the surface extensions in the two-part stator tooth guide the magnetic flux lines and reduce the magnetic flux leakage.
As used herein, the term “central yoke” refers to a central mechanical element that provides support to the flux coil and provides a path for the magnetic flux. It is to be understood that the flux coil is mounted on the central yoke in the slot formed around the central yoke.
As used herein, the term “tooth locking protrusion” refers to a protruding mechanical element present on one side of the central yoke for locking adjacent two-part stator teeth together forming stator assembly.
As used herein, the term “tooth locking groove” refers to a recessed cavity present on another side of the central yoke for locking adjacent two-part stator teeth together forming stator assembly. It is to be understood that the tooth locking groove receives the tooth locking protrusion.
As used herein, the term “rotor disc” refers to a disc-shaped component of the rotor for mounting the permanent magnets. The rotor disc is connected to the motor shaft and delivers the torque to the motor shaft for the rotation of the motor shaft.
As used herein, the term “permanent magnet blocks” refers to blocks arranged in the rotors of electric motors, in a specific pattern to create a permanent magnetic flux.
Figure 1 illustrates an exploded view of a three air-gap motor 100 for an electric vehicle. The three air-gap motor 100 for an electric vehicle comprises a motor casing 102, a stator assembly 104, a radial-flux rotor 106 and a pair of axial-flux rotors 108, and a motor shaft 110. The radial-flux rotor 106 and the pair of axial-flux rotors 108 comprises of a plurality of permanent magnet blocks 106a, 108a. The radial-flux rotor 106 is mounted on the motor shaft 110 in a radially inward direction of the stator assembly 104. The pair of axial-flux rotors 108 are mounted on the motor shaft 110 in mutually opposite axial directions sandwiching the stator assembly 104.
The three air-gap motor 100 as disclosed, provides improved efficiency and power density. Advantageously, the present invention provides an easy-to-assemble and disassemble three air-gap hybrid flux motor 100. Furthermore, the three air-gap motor 100 has lower non-flux weight i.e., low weight of components that are not generating any flux, resulting in increased power density and efficiency. Furthermore, the three air-gap motor 100 comprises hybrid magnetic flux, i.e., magnetic flux in both radial and axial directions. Beneficially, the three air-gap motor 100 has the magnetic flux in three directions comprising radially inward and mutually opposite axial directions. Beneficially, the three air-gap motor 100 utilizes the magnetic flux directed in the three directions for rotating the rotor resulting in improved torque output. Advantageously, the three air-gap motor 100 is cost-efficient in manufacturing and provides ease of servicing and maintenance. Beneficially, the three air-gap motor 100 efficiently utilizes the space inside the motor casing resulting in compact size despite increased power density. Beneficially, the three air-gap motor 100 is suitable for use in high-power applications such as use in the powertrain of electric vehicles. Beneficially, the three air-gap motor 100 is advantageous in terms of reducing flux leakage and maximizing flux utilization resulting in higher power density and efficiency. Beneficially, the three air-gap motor 100 has reduced vibrations and operates smoothly. Beneficially, the three air-gap motor 100 comprises reduced flux leakage and efficient utilization of the generated magnetic flux.
In an embodiment, the motor casing 102 comprises a front-end case 102a and a rear-end case 102b. It is to be understood that the motor casing 102 along with the front-end case 102a and a rear-end case 102b provides enclosure to components of the motor 100. Beneficially, the motor casing 102 along with the front-end case 102a and a rear-end case 102b provides mechanical support to the components of the motor 100.
In an embodiment, the stator assembly 104 comprises a plurality of two-part stator teeth 104a, wherein each of the two-part stator tooth comprises an axial-flux segment 104b and a radial-flux segment 104c. Beneficially, the axial-flux segment 104b and the radial-flux segment 104c in the two-part stator teeth 104a, provide for the passage of the magnetic flux lines along axial as well as radial direction respectively. Such magnetic flux enables the motor 100 to produce maximum torque output.
In an embodiment, the plurality of two-part stator teeth 104a are locked adjacent to each other to form the stator assembly 104. Beneficially, the stator assembly 104 formed by the plurality of two-part stator teeth 104a is easy to assemble and disassemble. Beneficially, the stator assembly 104 provides enhanced serviceability of the motor 100.
In an embodiment, the plurality of two-part stator teeth 104a comprise surface extensions, wherein the surface extensions reduce an air gap between the adjacent two-part stator tooth 104a to prevent magnetic flux leakage. Beneficially, the reduced air gap between the adjacent two-part stator tooth 104a increases the utilization of magnetic flux resulting in increased efficiency of the motor 100.
In an embodiment, the stator assembly 104 comprises a plurality of flux coils 104e wherein each flux coil of the plurality of flux coils 104e is accommodated in a slot formed by two adjacent two-part stator teeth 104a in the stator assembly 104. Beneficially, the slot mechanically supports the flux coils 104e. More beneficially, the slot prevents the vibration of the flux coils 104e during the operation of the motor 100. It is to be understood that the flux coils 104e generate magnetic flux when an electric current flows through the flux coils 104e.
In an embodiment, the radial-flux segments 104c of the plurality of two-part stator teeth 104a guide the magnetic flux generated by the plurality of flux coils 104e in the radially inward direction. Beneficially, the magnetic flux guided in the radially inward direction rotates the radial-flux rotor 106.
In an embodiment, the radial-flux rotor 106 comprises at least one ring of the permanent magnet blocks 106a, wherein the at least one ring of the permanent magnet blocks 106a interacts with radially inward magnetic flux to rotate the radial-flux rotor 106. Beneficially, the at least one ring of the permanent magnet blocks 106a, is aligned non-linearly with respect to each other, to reduce cogging torque in the radial-flux rotor 106.
In an embodiment, the axial-flux segments 104b of the plurality of two-part stator teeth 104a guide the magnetic flux generated by the plurality of flux coils 104e in the axial directions. Beneficially, the magnetic flux guided in the axial directions routes the pair of the axial-flux rotors 108.
In an embodiment, each of the axial-flux rotor 108 comprises a disc of permanent magnet blocks 108a mounted on a rotor disc, wherein the discs of permanent magnet blocks 108a face towards the stator assembly 104, and wherein the discs of the permanent magnet blocks 108a interact with axial magnetic flux to rotate each of the axial-flux rotor 108. Beneficially, the rotor discs are connected with the motor shaft 110 to deliver torque output.
In an embodiment, the permanent magnet blocks 108a mounted on the rotor discs are skewed in direction of rotation of each of the axial-flux rotor 108 to reduce a cogging torque. It is to be understood that the skewing of the permanent magnet blocks 108a mounted on the rotor discs in direction of rotation of each of the axial-flux rotors 108 causes misalignment between the rotor magnetic field and stator magnetic flux. Beneficially, the misalignment between the rotor magnetic field and stator magnetic flux reduces the cogging torque inside the motor 100.
In an embodiment, the permanent magnet blocks 106a, 108a are made of ferrite material. Beneficially, the disclosed three air-gap air motor 100 has increased power density that enables the usage of ferrite material in the permanent magnet blocks 106a, 108a of the motor 100. It is to be understood that the power loss occurred due to the use of ferrite material permanent magnet blocks 106a, 108a is compensated by the increased power density resulting from the use of the radial-flux rotor 106 and a pair of axial-flux rotors 108.
Figure 2, in accordance with an embodiment, describes an exploded view of the three air-gap motor 100 for an electric vehicle. The three air-gap motor 100 for an electric vehicle comprises a motor casing 102, a stator assembly 104, a radial-flux rotor 106 and a pair of axial-flux rotors 108, and a motor shaft 110. The radial-flux rotor 106 and the pair of axial-flux rotors 108 comprises of a plurality of permanent magnet blocks 106a, 108a. The radial-flux rotor 106 is mounted on the motor shaft 110 in a radially inward direction of the stator assembly 104. The pair of axial-flux rotors 108 are mounted on the motor shaft 110 in mutually opposite axial directions sandwiching the stator assembly 104.
In an embodiment, the three air-gap motor 100 for an electric vehicle comprises a motor casing 102, a stator assembly 104, a radial-flux rotor 106 and a pair of axial-flux rotors 108 and a motor shaft 110. The radial-flux rotor 106 and the pair of axial-flux rotors 108 comprises of a plurality of permanent magnet blocks 106a, 108a. The radial-flux rotor 106 is mounted on the motor shaft 110 in a radially inward direction of the stator assembly 104. The pair of axial-flux rotors 108 are mounted on the motor shaft 110 in mutually opposite axial directions sandwiching the stator assembly 104. Furthermore, the motor casing 102 comprises a front-end case 102a and a rear-end case 102b. Furthermore, the stator assembly 104 comprises a plurality of two-part stator teeth 104a, wherein each of the two-part stator tooth comprises an axial-flux segment 104b and a radial-flux segment 104c. Furthermore, the plurality of two-part stator teeth 104a are locked adjacent to each other to form the stator assembly 104. Furthermore, the plurality of two-part stator teeth 104a comprise surface extensions, wherein the surface extensions reduce an air gap between the adjacent two-part stator tooth 104a to prevent magnetic flux leakage. Furthermore, the stator assembly 104 comprises a plurality of flux coils 104e wherein each flux coil of the plurality of flux coils 104e is accommodated in a slot formed by two adjacent two-part stator teeth 104a in the stator assembly 104. Furthermore, the radial-flux segments 104c of the plurality of two-part stator teeth 104a guide the magnetic flux generated by the plurality of flux coils 104e in the radially inward direction. Furthermore, the radial-flux rotor 106 comprises at least one ring of the permanent magnet blocks 106a, wherein the at least one ring of the permanent magnet blocks 106a interacts with radially inward magnetic flux to rotate the radial-flux rotor 106. Furthermore, the axial-flux segments 104b of the plurality of two-part stator teeth 104a guide the magnetic flux generated by the plurality of flux coils 104e in the axial directions. Furthermore, each of the axial-flux rotor 108 comprises a disc of permanent magnet blocks 108a mounted on a rotor disc, wherein the discs of permanent magnet blocks 108a face towards the stator assembly 104, and wherein the discs of the permanent magnet blocks 108a interact with axial magnetic flux to rotate each of the axial-flux rotor 108. Furthermore, the permanent magnet blocks 108a mounted on the rotor discs are skewed in direction of rotation of each of the axial-flux rotor 108 to reduce a cogging torque.
Figure 3, in accordance with an embodiment, describes a perspective view of the two-part stator tooth 104a along with the flux coil 104e. In an embodiment, the two-part stator tooth 104a comprises an axial-field segment 104b and a radial-field segment 104c. The axial-field segment 104b comprises a pair of mutually opposite axial-field faces, an interlocking face, and an outer face. The radial-field segment 104c comprises a radial-field face, a locking protrusion face, and a pair of mutually opposite side faces. The locking protrusion face of the radial-field segment 104c and the interlocking face of the axial-field segment 104b are locked together to form the two-part stator tooth 104a. Furthermore, the interlocking face of the axial-field segment 104b comprises at least one locking groove. Furthermore, the locking protrusion face of the radial-field segment 104c comprises at least one locking protrusion. Furthermore, the at least one locking protrusion of the radial-field segment 104c is received and locked into the at least one locking groove of the axial-field segment 104b to form the two-part stator tooth 104a. Furthermore, the axial-field faces of the axial-field segment 104b comprise surface extensions extended along radial length of the axial-field faces. Furthermore, the surface extensions of the axial-field faces of the axial-field segment 104b reduce an air gap between adjacent two-part stator tooth 104a to prevent flux leakage. Furthermore, the side faces of the radial-field segment 104c comprise surface extensions extended along radial length of the side faces. Furthermore, the surface extensions of the side faces of the radial-field segment 104c complement the surface extensions of the axial-field faces of the axial-field segment 104b to reduce an air gap between the adjacent two-part stator tooth 104a. Furthermore, the axial-field segment 104b of the stator tooth 104a comprises a central yoke extending in mutually opposite direction along the radial length of the axial-field segment 104b of the stator tooth 104a. Furthermore, one side of the central yoke comprises at least one tooth locking groove 106a along radial length of the central yoke 106 and another side of the central yoke 106 comprises at least one tooth locking protrusion 106b along the radial length of the central yoke. Furthermore, the two-part stator tooth 104a is locked with the adjacent two-part stator tooth 104a by inserting the at least one tooth locking protrusion of the two-part stator tooth 104a into the at least one tooth locking groove of the adjacent two-part stator tooth 104a. Furthermore, the adjacent two-part stator tooth 104a locked together forms a slot around the central yoke to accommodate a flux coil 104e.
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 combinations 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 three air-gap motor (100) for an electric vehicle, comprising:
- a motor casing (102);
- a stator assembly (104);
- a radial-flux rotor (106) and a pair of axial-flux rotors (108) comprising a plurality of permanent magnet blocks (106a,108a); and
- a motor shaft (110),
wherein the radial-flux rotor (106) is mounted on the motor shaft (110) in a radially inward direction of the stator assembly (104) and the pair of axial-flux rotors (108) are mounted on the motor shaft (110) in mutually opposite axial directions sandwiching the stator assembly (104).
2. The three air-gap motor (100) as claimed in claim 1, wherein the motor casing (102) comprises a front-end case (102a) and a rear-end case (102b).
3. The three air-gap motor (100) as claimed in claim 1, wherein the stator assembly (104) comprises a plurality of two-part stator teeth (104a), wherein each of the two-part stator tooth (104a) comprises an axial-flux segment (104b) and a radial-flux segment (104c).
4. The three air-gap motor (100) as claimed in claim 1, wherein the plurality of two-part stator teeth (104a) are locked adjacent to each other to form the stator assembly (104).
5. The three air-gap motor (100) as claimed in claim 1, wherein the plurality of two-part stator teeth (104a) comprise surface extensions, wherein the surface extensions reduce an air gap between the adjacent two-part stator tooth (104a) to prevent magnetic flux leakage.
6. The three air-gap motor (100) as claimed in claim 1 and 4, wherein the stator assembly (104) comprises a plurality of flux coils (104e), wherein each flux coil of the plurality of flux coils (104e) is accommodated in a slot formed by two adjacent two-part stator teeth (104a) in the stator assembly (104).
7. The three air-gap motor (100) as claimed in claim 1, wherein the radial-flux segments (104c) of the plurality of two-part stator teeth (104a) guide the magnetic flux generated by the plurality of flux coils (104e) in the radially inward direction.
8. The three air-gap motor (100) as claimed in any of the claims 1 and 7, wherein the radial-flux rotor (106) comprises at least one ring of the permanent magnet blocks (106a), wherein the at least one ring of the permanent magnet blocks (106a) interacts with radially inward magnetic flux to rotate the radial-flux rotor (106).
9. The three air-gap motor (100) as claimed in claim 1, wherein the axial-flux segments (104b) of the plurality of two-part stator teeth (104a) guide the magnetic flux generated by the plurality of flux coils (104e) in the axial directions.
10. The three air-gap motor (100) as claimed in any of the claims 1 and 9, wherein each of the axial-flux rotor (108) comprises a disc of permanent magnet blocks (108a) mounted on a rotor disc, wherein the discs of permanent magnet blocks (108a) face towards the stator assembly (104), and wherein the discs of the permanent magnet blocks (108a) interact with axial magnetic flux to rotate each of the axial-flux rotor (108).
11. The three air-gap motor (100) as claimed in claim 10, wherein the permanent magnet blocks (108a) mounted on the rotor discs are skewed in direction of rotation of each of the axial-flux rotor (108) to reduce a cogging torque.
12. The three air-gap motor (100) as claimed in any of the claims 1 to 11, wherein the permanent magnet blocks (106a,108a) are made of ferrite material.