TECHNICAL FIELD

The present disclosure relates to a radial flux electric machine.

BACKGROUND

The current disclosure relates to electrical machines, and in particular to radial flux electrical machines. Electric machine (or electrical machine) is a general term for machines that rely on electromagnetic forces for its operation. The two main parts of an electric machine can be described in mechanical or electrical terms. In mechanical terms, the rotor is the rotating part, and the stator is the stationary part of an electrical machine. In electrical terms, the armature is the power-producing component and the field is the magnetic field producing component of an electrical machine. The armature can be on the rotor or the stator, and the magnetic field can be provided by either electromagnets or permanent magnets mounted on either the rotor or the stator. Electric machines are electromechanical energy converters and include, among others, electric motors, and electric generators. An electric motor converts electricity to mechanical power while an electric generator converts mechanical power to electricity. The moving part of the electric machine can be rotating (rotating electric machines) or linear (linear electric machines). Electric machines operate on the principle that electrical current generates electromagnetic flux and vice versa. In some electric machine, a rotor comprising permanent magnets is configured for rotating in an electromagnetic field generated by a plurality of electromagnets through which electricity is passed.

Electrical machines can be categorized as axial flux electric machines and radial flux electric machines. The fundamental difference between these types of machines lie in the orientation of the magnetic field in these machines. In radial flux electric machines, the working magnetic flux crosses the air gap between the stator and the rotor in the radial plane, while in axial flux electric machines, the magnetic flux crosses the air gap parallel to the axis of rotation. A large number of solutions are known aimed at reducing the stray fields of permanent magnets and windings of an electric machine, as well as increasing the concentration of the magnetic flux density in the stator and rotor cores, and strive to ensure the same values of the magnetic flux density in all parts of the core. There are also a large number of solutions aimed at providing a high fill factor for permanent magnet electric machines. Some of these solutions use complex tooth shapes to improve electric machine performance. While some of these solutions effectively uses the volume of the tooth, they do not sufficiently reduce the leakage fluxes of the electric machine. In addition, in some cases, the complex tooth shapes makes it difficult to provide a high winding fill factor for electric machines. The radial flux electric machines of the current disclosure alleviates some or all of the above-mentioned issues. A decrease in leakage fluxes and an increase in the fill factor in embodiments of electric machines of the current disclosure may allow for increased power and efficiency of electrical machines. However, the scope of the current disclosure is defined by the claims and not by the ability to solve any problem.

SUMMARY

Several embodiments of an electric machine and methods of fabricating and using an electric machine are disclosed. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only. As such, the scope of the disclosure is not limited solely to the disclosed embodiments. Instead, it is intended to cover such alternatives, modifications and equivalents within the spirit and scope of the disclosed embodiments. Persons skilled in the art would understand how various changes, substitutions and alterations can be made to the disclosed embodiments without departing from the spirit and scope of the disclosure.

In one embodiment, an electric machine having a plurality of trapezoidal teeth is disclosed. The electric machine may include a plurality of electromagnetic coils. Each coil may include a non-uniform trapezoidal cavity therethrough and may be configured to contain therein one tooth of the plurality of teeth. Each tooth may be formed of multiple pieces that, when assembled together form a trapezoidal tooth.

In some embodiments, the trapezoidal shape of the multipiece tooth, in which the cross-sectional area increases in the radial direction towards the rotor, and the winding coils are shifted as close as possible to the air gap, may significantly reduce the leakage fields of the electric machine. Pre-forming a tooth with a constant cross-sectional perimeter in the radial direction leads to an increase in the fill factor of the electric machine and improves the performance, efficiency torque and power of the electric machine.

In one embodiment, a radial flux electric machine is disclosed. The electric machine may include a rotor configured to rotate about an axis of rotation and a stator. At least one of the rotor or the stator may include a plurality of teeth annularly arranged about the axis of rotation. The electric machine may also include a plurality of electromagnetic coils. Each coil of the plurality of electromagnetic coils may have a non-uniform trapezoidal cavity therethrough. Each cavity may be configured to contain therein one tooth of the plurality of teeth. Each tooth of the plurality of teeth may be formed of multiple pieces that, when assembled together correspond to a shape of the non-uniform trapezoidal cavity.

Various embodiments of the electric machine may alternatively or additionally include one or more of the following aspects: when the multiple pieces of each tooth are assembled together, an external perimeter of each tooth corresponds to an internal perimeter of the cavity of a corresponding coil; each tooth includes a core tooth-portion and at least one wedge-shaped portion; each tooth includes a core tooth-portion and at least two wedge-shaped portions disposed on opposite sides of the core portion; in a plane perpendicular to the axis of rotation, the core tooth-portion has a substantially rectangular cross-sectional shape and the at least one wedge-shaped portion has a substantially triangular cross-sectional shape; in a plane perpendicular to a radial direction, the core tooth-portion and the at least one wedge-shaped portion has a substantially rectangular cross-sectional shape; the core tooth-portion and the at least one wedge-shaped portion of each tooth are coupled together using an adhesive material; the core tooth-portion of each tooth is integrally formed with an annular ring that extends around the axis of rotation; when the multiple pieces of each tooth are assembled together, each tooth defines external surfaces having two sets of opposing faces, the opposing faces of each set of the two sets being non-parallel to each other; the opposing faces of adjacent teeth are parallel to each other; each face of the two sets of opposing faces is inclined in a radial direction; the opposing faces of one set of opposing faces converge towards each other in a radially outward direction and the opposing faces of the other set of opposing faces diverge from each other in the radially outward direction; a cross-section of each tooth in a plane perpendicular to the axis of rotation has a trapezoidal shape, and a cross-section of each tooth in a plane perpendicular to a radial direction has a rectangular shape; a perimeter of the cross-sections perpendicular to a radial direction is substantially a constant in the radial direction; an area of the cross-sections perpendicular to the radial direction varies in the radial direction; the stator includes the plurality of teeth, and the area of the cross-section perpendicular to the radial direction increases in the radial direction towards the rotor; a cross-section of each tooth in an axial plane has an isosceles trapezoidal shape; at least one piece of the multiple pieces of each tooth is formed of a soft magnetic composite (SMC); the stator includes the plurality of teeth, and wherein a first piece of the multiple pieces of each tooth is integral with and extends radially from an annular stator ring that extends around the axis of rotation, and a second piece of the multiple pieces of each tooth is non-integrally formed with the first piece; the electric machine is one of an electric motor or an electric generator.

In another embodiment, a radial flux electric machine is disclosed. The electric machine may include a rotor configured to rotate about an axis of rotation and a stator fixedly positioned proximate the rotor. At least one of the rotor or the stator may include a plurality of teeth annularly arranged about the axis of rotation. Each tooth of the plurality of teeth may extend in a radial direction such that a plurality of cross-sectional areas of each tooth in a plurality of planes perpendicular to the radial direction may vary. And perimeters of the plurality of cross-sections may be substantially the same across the plurality of perpendicular planes.

Various embodiments of the electric machine may alternatively or additionally include one or more of the following aspects: a shape of each tooth in at least one of an axial plane or a radial plane of the electric machine is a trapezoid; the shape of each tooth in at least one of an axial plane or a radial plane of the electric machine is an isosceles trapezoid; the plurality of teeth are annularly arranged on the stator; the rotor is disposed radially outwards of the stator, a width of each tooth in a radial plane increases in the radial direction towards the rotor, and a length of each tooth in an axial plane decreases in the radial direction towards the rotor; each tooth extends in the radial direction such that a cross-sectional area of each tooth in a plane perpendicular to the radial direction increases in the radial direction toward the rotor; the rotor is disposed radially inwards of the stator, and a cross-sectional area of each tooth of the plurality of teeth in a plane perpendicular to the radial direction increases in the radial direction toward the rotor; the plurality of teeth are annularly arranged on the rotor; the electric machine further includes a plurality of electromagnetic coils, and wherein each coil of the plurality of electromagnetic coils extends around a separate tooth of the plurality of teeth; each coil includes copper wire having one of a square, rectangular, or circular cross-sectional shape; the wire is multi-strand and each coil is wound in the form of a spiral in the radial direction along a tooth; each coil includes copper foil wound around a tooth such that a flat side of the foil extends over an entire length of the tooth in the radial direction; each coil includes a rib of copper foil wound in the form of a spiral in the radial direction along a tooth; each tooth includes a soft magnetic composite (SMC) material; each tooth includes multiple pieces coupled together; the multiple pieces include a core portion integrally formed with an annular ring that extends around the axis of rotation and one or more wedge portions coupled to the core portion; the one or more wedge portions include at least two wedge portions disposed on opposite sides of the core portion; the electric machine is an electric motor or an electric generator; one of the stator or the rotor includes an outer part and an inner part and wherein the stator and rotor are separated by a double air gap; the outer part and the inner part connected together by a connecting portion made of a magnetically conductive material.

In another embodiment, a radial flux electric machine is disclosed. The electric machine may include a rotor configured to rotate about an axis of rotation, a plurality of electromagnetic coils, and a stator. The stator may include an annular stator ring extending about the axis of rotation and a plurality of multi-part teeth circumferentially arranged on the stator ring. Each multi-part tooth of the plurality of multi-part teeth may include a core tooth-portion integrally formed with the stator ring and at least one additional tooth-portion separate from the stator ring. Each coil of the plurality of electromagnetic coils may be mounted on a different multi-part tooth of the plurality of multi-part teeth such that each coil surrounds a corresponding core tooth-portion of the multi-part tooth with a gap between the coil and the core tooth-portion. The at least one additional tooth-portion may be disposed in the gap.

Various embodiments of the electric machine may alternatively or additionally include one or more of the following aspects: the core tooth-portion each multi-part teeth is formed of a soft magnetic composite (SMC); the annular stator ring is formed of a soft magnetic composite (SMC); the annular stator ring includes two mirror-symmetric halves coupled together along a plane of symmetry perpendicular to the axis of rotation; the two mirror-symmetric halves are attached together along the plane of symmetry using an adhesive material; the annular stator ring includes multiple axially stacked annular rings, at wherein at least two of the stacked annular rings are made of a soft magnetic composite (SMC); the core tooth-portion of each multi-part tooth extends outward in a radial direction from the annular stator ring; a cross-sectional of each of the core tooth-portion and the at least one additional tooth-portion along a plane perpendicular to the radial direction has a substantially rectangular shape; a cross-section of the core tooth-portion along a plane perpendicular to the axis of rotation has a substantially rectangular shape; a cross-section of the at least one additional tooth-portion along the plane perpendicular to the axis of rotation has a substantially triangular shape; a cross-sectional of each tooth of the plurality of multi-part teeth along the plane perpendicular to the axis of rotation has a substantially trapezoidal shape; the at least one additional tooth-portion includes a pair of additional tooth-portions arranged symmetrically on opposite sides of the core tooth-portion; the core tooth-portion and the at least one additional tooth-portion of each tooth of the plurality of multi-part teeth are coupled together using an adhesive material; a difference between coefficients of thermal expansion of materials of the core tooth-portion, the at least one additional tooth-portion, and the adhesive material is less than about 20%; the at least one additional tooth-portion of each multi-part tooth is wedged between an internal surface of a coil of the plurality of electromagnetic coils and an external surface of the core tooth-portion; a coil of the plurality of electromagnetic coils surrounds the core tooth-portion of each tooth such that at least two gaps are formed between an inner surface of the coil and opposite sides of the core tooth-portion, and wherein the at least one additional tooth-portion includes at least two additional tooth-portions disposed in a different gap of the at least two gaps; a cross-section of each multi-part tooth of the plurality of multi-part teeth in a plane perpendicular to a radial direction has a rectangular shape; a perimeter of the cross-section is substantially a constant in the radial direction; an area of the cross-section varies in the radial direction; the electric machine is an electric motor or an electric generator.

In another embodiment, a radial flux electric machine is disclosed. The electric machine may include a rotor configured to rotate about an axis of rotation, a plurality of electromagnetic coils, and a stator. The stator may have an annular stator ring and a plurality of core tooth-portions extending in a radial direction. The annular stator ring and the plurality of core tooth-portions may be integrally formed of a Soft Magnetic Composite (SMC). The SMC may include one or more isotropic ferromagnetic materials, a magnetic saturation induction of greater than or equal to about 1.6 Tesla, and an electrical resistivity greater than 10 micro-ohm/m.

Various embodiments of the electric machine may alternatively or additionally include one or more of the following aspects: the stator includes a plurality of multi-part teeth symmetrically arranged on the annular stator ring, wherein each tooth of the plurality of multi-part teeth includes one of the plurality of core tooth-portions and at least one additional tooth-portion non-integrally formed with the one of the plurality of core tooth portions; a pair of additional tooth-portions are arranged on opposite sides of an associated core tooth-portion; a cross-section of the core tooth-portion of each tooth along a plane perpendicular to the axis of rotation has a substantially rectangular shape, and a cross-section of each additional tooth portion of the at least one additional tooth-portions along the plane perpendicular to the axis of rotation has a substantially triangular shape; a cross-section of each of the core tooth-portions and the at least one additional tooth-portions along a plane perpendicular to the radial direction has a substantially rectangular shape; a cross-section of each tooth of the plurality of multi-part teeth in a plane perpendicular to the axis of rotation has a trapezoidal shape; a cross-section of each tooth of the plurality of multi-part teeth in a plane perpendicular to the radial direction has a substantially rectangular shape, and a perimeter of the cross-section is substantially a constant in the radial direction, and an area of the cross-section varies in the radial direction; the rotor is disposed radially outwards of the stator to form an air gap between the rotor and the stator, and the area of the cross-section increases in the radial direction toward the air gap; each tooth of the plurality of multi-part teeth defines external surfaces having two sets of opposing faces, the opposing faces of each set of the two sets being non-parallel to each other, and adjacent side faces of adjacent teeth being parallel to each other; each face of the two sets of opposing faces is inclined in a radial direction; the opposing faces of one set of opposing faces converge towards each other in a radially outward direction and the opposing faces of the other set of opposing faces diverge from each other in the radially outward direction; the at least one additional tooth-portions is formed of the SMC; at least one additional tooth-portion is formed of an isotropic material other than SMC; the annular stator ring includes two mirror-symmetric bodies coupled together along a plane of symmetry perpendicular to the axis of rotation; the two mirror-symmetric bodies are attached together along the plane of symmetry using an adhesive material, wherein a difference between coefficients of thermal expansion of the SMC and the adhesive material is less than about 20%; the magnetic saturation induction of the SMC is greater than or equal to about 2.4 Tesla; the magnetic saturation induction of the SMC is greater than or equal to about 2.5 Tesla; the resistivity of the SMC is greater than about 100 micro-ohm/m; the electric machine is an electric motor; the electric machine is an electric generator.

In another embodiment, a radial flux electric machine is disclosed. The electric machine may include an inner stator and an outer rotor configured to rotate about the stator. The outer rotor may include a rotor base and a plurality of annularly arranged permanent magnets axially extending from the rotor base parallel to an axis of rotation of the rotor. A cylindrical core may extend from the rotor base encircling the plurality of permanent magnets. The core may be formed of a Soft Magnetic Composite (SMC). A sleeve may encircle the rotor. The sleeve may support the cylindrical core and the cylindrical core may support the plurality of permanent magnets. The cylindrical core may be positioned radially between the sleeve and the plurality of permanent magnets.

Various embodiments of the electric machine may alternatively or additionally include one or more of the following aspects: at least one of the sleeve or the rotor base is made of non-magnetic material; the non-magnetic material is a composite material including at least one of carbon fiber, glass fiber, or aramid fiber; the non-magnetic material includes at least one of stainless steel or aluminum; the sleeve is made of a magnetic material; the magnetic material includes a soft magnetic material including laminated electrical steel sheets; the magnetic material is a solid body made of steel; the sleeve includes stiffening ribs disposed on recesses formed on an external surface of the cylindrical core; the cylindrical core extends from a first end coupled to the rotor base to a second end, wherein the sleeve includes a balancing ring located at the second end of the cylindrical core, and wherein the balancing ring is configured to provide dynamic balancing of the rotor; the sleeve extends over the balancing ring; the balancing ring is formed of a non-magnetic material; the plurality of permanent magnets are arranged on the rotor base in a substantially circular pattern around the axis of rotation; the plurality of permanent magnets are arranged on the rotor base such that the magnetic axis of each permanent magnet of the plurality of permanent magnets intersect at the axis of rotation; the rotor base is formed of aluminum or steel; the rotor base includes air vents configured to direct airflow along the axis of rotation when the rotor base rotates; the rotor base is integral with the sleeve and the balancing ring; the plurality of permanent magnets are attached to the cylindrical core using an adhesive, and wherein a difference between coefficients of thermal expansion of materials of the plurality of permanent magnets, the cylindrical core, and the adhesive is less than about 20%; the sleeve is integral with the rotor base to form a single piece; the cylindrical core and the sleeve both have a non-uniform radial thickness about the axis of rotation, and wherein thicker regions of the sleeve are located adjacent to a center of each permanent magnet; and the electric machine is one of electric motor or an electric generator.

In some embodiments, a method of assembling a coil on an irregular-shaped multi-part tooth of an electric machine is disclosed. The method may include inserting at least one wedge-portion of the multi-part tooth into an opening of the coil such that a broader end of the at least one wedge-portion extends out of the opening in the coil. The method may also include mounting the coil with the inserted at least one wedge-portion on a core tooth-portion of the multi-part tooth such that the broader end of the at least one wedge-portion remains extended out of the opening in the coil, exerting a force on the broader end of the at least one wedge-portion to tighten the coil on the multi-part tooth.

Various embodiments of the disclosed method may alternatively or additionally include one or more of the following aspects: exerting a force on the broader end of the at least one wedge-portion includes pushing the broader end of the at least one wedge-portion into the opening in the coil; the opening in the coil extends from a first end to a second end, wherein inserting the at least one wedge-portion includes inserting the at least one wedge-portion into the opening such that the broader end extends out of the second end of the opening, and exerting the force includes pushing the broader end towards the first end of the opening; the opening in the coil extends from a first end to a second end, wherein a width of the opening at the first end differs from the width of the opening at the second end, and wherein a length of the opening at the first end differs from a height of the opening at the second end; a shape of the opening at the first end and the second end is rectangular; a perimeter of the opening at the first end is substantially the same as the perimeter of the opening at the second end; an area of the opening at the first end varies from the area of the opening at the second end; an area of the opening increases from the first end to the second end; inserting the at least one wedge-portion into the opening of the coil includes inserting at least two wedge-portions into the opening; mounting the coil includes mounting the coil on the core tooth-portion such that the core tooth-portion is disposed between the at least two wedge-portions; using an adhesive material to attach the at least two wedge-portions and the core tooth-portion of the multi-part tooth together; the multi-part tooth is a part of a stator of the electric machine; the core tooth-portion of the multi-part tooth is one of a plurality of core tooth-portions symmetrically arranged on an annular stator ring that extends around a central axis, and wherein the core tooth-portion extends outward in a radial direction from the annular stator ring; the plurality of core tooth-portions are integrally formed with the annular stator ring; in a plane perpendicular to the central axis, the core tooth-portion has a substantially rectangular cross-sectional shape and the at least one wedge-portion has a substantially triangular cross-sectional shape; in a plane perpendicular to the radial direction, the core tooth-portion and the at least one wedge-portion have a substantially rectangular cross-sectional shape; the coil includes a winding of a copper wire around the opening, the wire having one of a square, rectangular, or circular cross-sectional shape; the coil includes a winding of a copper stranded wire in a spiral around the opening; the electric machine is an electric motor; and the electric machine is an electric generator.

In some embodiments, a method of fabricating a coil for mounting on a tooth of a stator or a rotor of an electric machine is disclosed. The method may include winding a wire about a mandrel to form a coil having a first shape corresponding to the shape of the mandrel, removing the coil having the first shape from the mandrel, and applying a mechanical force on the coil to change the shape of the coil from the first shape to a second shape. The second shape may correspond to the shape of the tooth. The method may also include mounting the coil of the second shape on the tooth.

Various embodiments of the disclosed method may alternatively or additionally include one or more of the following aspects: the wire is formed of a plurality of strands of an electrical conductor; the wire is formed by twisting together an electrical conductor or made in the form of a Litz wire; the wire has a circular cross-sectional shape; the wire has one of a square or a rectangular cross-sectional shape; the first shape is a cylindrical shape or any shape with a substantially constant perimeter; the second shape is a trapezoidal shape; winding the wire about the mandrel includes winding the wire about the mandrel in a spiral pattern to form coil having an internal cavity extending from a first end to a second end; applying a mechanical force on the coil includes selectively increasing a size of the cavity at one of the first end or the second end; applying a mechanical force on the coil includes changing a shape of the internal cavity; changing the shape of the internal cavity includes changing a cross-sectional shape of the internal cavity along a plane perpendicular to a central axis of the internal cavity from a circular shape to a rectangular shape; a width and a length of the rectangular shape both vary from the first end to the second end; a perimeter of the rectangular shape is substantially a constant from the first end to the second end and an area of the rectangular shape varies from the first end to the second end; the area of the rectangular shape increases from the first end to the second end; changing the shape of the internal cavity includes changing a 3-dimensional shape of the inner cavity from a cylindrical shape to a trapezoidal shape; applying a mechanical force on the coil includes inserting a second mandrel into the internal cavity of the coil to change a shape of the first end of the internal cavity compared to a shape of the second end of the internal cavity; applying a mechanical force on the coil includes applying a first mechanical force to increase a dimension of the internal cavity at one of the first end or the second end and a second mechanical force to decrease a dimension of the internal cavity at the other of the first end or the second end; the first mechanical force acts towards a central axis of the internal cavity and the second mechanical force acts away from the central axis; applying a mechanical force on the coil includes stretching the wire of the coil that defines at least one of the first end or the second end of the internal cavity; the wire is made of copper.

In one embodiment, an electric machine is disclosed. The electric machine may include a rotor configured to rotate about an axis of rotation, a stator having a plurality of teeth annularly arranged on a stator core about the axis of rotation, a plurality of electromagnetic coils, and a base plate. Each coil of the plurality of electromagnetic coils may be mounted on a separate tooth of the plurality of teeth, and the base plate may be located adjacent to the plurality of electromagnetic coils and the stator core. The base plate may be in thermal contact with the plurality of electromagnetic coils and the stator core such that as the plurality of electromagnetic coils and the stator core heat during operation, the base plate is configured to serve as a common heat sink for the plurality of electromagnetic coils and the stator core.

Various embodiments of the disclosed electric machine may alternatively or additionally include one or more of the following aspects: each coil of the plurality of electromagnetic coils is in contact with the base plate directly or through a thermally-conductive material disposed therebetween; the stator core is in contact with the base plate directly or through a thermally-conductive material disposed therebetween; further include a motor housing thermally connected to the base plate to enable heat generated by the plurality of electromagnetic coils and stator core to be dissipated through the base plate and the motor housing; the base plate includes a first side and a second side opposite the first side, wherein the plurality of electromagnetic coils and the stator core are in thermal contact with the first side of the base plate and the motor housing is in thermal contact with the second side of the base plate; the second side of the base plate includes cooling fins that extend therefrom; the cooling fins include a plurality of pins; the base plate includes a cylindrical hub portion extending around the axis of rotation; the stator core includes an annular stator ring that extends around the cylindrical hub portion of the base plate; an inner annular surface of the annular stator ring is in contact with an outer annular surface of the cylindrical hub portion of the base plate directly or through a thermally-conductive material disposed therebetween; the stator core includes an annular stator ring that extends around the axis of rotation and each tooth of the plurality of teeth includes a core tooth-portion integral with the annular stator ring; each tooth of the plurality of teeth further includes one or more additional tooth-portions non-integrally formed with the core tooth-portion; a pair of additional tooth-portions includes tooth-portions arranged on opposite sides of the core tooth-portion; when all the tooth parts are assembled together, each tooth defines external surfaces having two sets of opposing faces, the opposing faces of each set of the two sets being non-parallel to each other, and wherein each face of the two sets of opposing faces is inclined in a radial direction; opposing faces of adjacent teeth are substantially parallel to each other; a cross-section of each tooth in a plane perpendicular to the radial direction has a rectangular shape, and wherein a perimeter of the cross-section is substantially a constant in the radial direction and an area of the cross-section varies in the radial direction; the base plate is formed of aluminum; the base plate includes air vents configured to direct air to the plurality of electromagnetic coils when the rotor rotates; the electric machine is an electric motor; the electric machine is an electric generator.

In yet another embodiment, an electric machine is disclosed. The electric machine may include a rotor configured to rotate about an axis of rotation, a stator having a stator core and a plurality of teeth annularly arranged on the stator core about the axis of rotation, a plurality of electromagnetic coils, and a base plate. Each coil of the plurality of electromagnetic coils may be mounted on a separate tooth of the plurality of teeth. The base plate may be located adjacent to the plurality of electromagnetic coils and the stator core. The base plate may have a first side and an opposing second side. The first side may be in thermal contact with the plurality of electromagnetic coils and the stator core. A liquid-coolant channel may be defined on the second side of the base plate such that as the coils and the stator core heats during operation, the base plate is configured to transfer the heat to a liquid coolant in the liquid-coolant channel to dissipate heat from the plurality of electromagnetic coils and the stator core.

Various embodiments of the disclosed electric machine may alternatively or additionally include one or more of the following aspects: each coil of the plurality of electromagnetic coils is in contact with the base plate directly or through a thermally-conductive material disposed therebetween; the stator core is in contact with the base plate directly or through a thermally-conductive material disposed therebetween; further include a motor housing thermally connected to the base plate to enable heat generated by the plurality of electromagnetic coils and stator core to be dissipated through the base plate and the motor housing; the base plate includes a first side and a second side opposite the first side, wherein the plurality of electromagnetic coils and the stator core are in thermal contact with the first side of the base plate and the motor housing is in thermal contact with the second side of the base plate; a wall of the liquid-coolant channel is a portion of the second side of the base plate directly opposite a portion of the first side of the base plate that is in thermal contact with the plurality of electromagnetic coils; the liquid-coolant channel extends around the axis of rotation and an annular region on the second side of the base plate serves as a wall of the liquid-coolant channel; the annular region on the second side of the base plate includes a plurality of fins that extend into the liquid-coolant channel; the plurality of fins is arranged about the axis of rotation; further include a coolant inlet configured to direct the coolant into the liquid-coolant channel and a coolant outlet configured to direct the coolant out of the liquid-coolant channel; the base plate includes a cylindrical hub portion extending around the axis of rotation and the stator core includes an annular stator ring that extends around the cylindrical hub portion of the base plate, and the liquid-coolant channel passes through the cylindrical hub portion along the axis of rotation; an inner annular surface of the annular stator ring is in contact with an outer annular surface of the cylindrical hub portion of the base plate directly or through a thermally-conductive material disposed therebetween; each tooth of the plurality of teeth includes a core tooth-portion integrally formed with the annular stator ring and at least one additional tooth-portion non-integrally formed with the core tooth-portion; the annular stator ring and the core tooth-portion are formed of a Soft Magnetic Composite (SMC); when the core tooth-portion and at least one additional tooth-portion are assembled together, each tooth defines external surfaces having two sets of opposing faces, the opposing faces of each set of the two sets being non-parallel to each other, and wherein each face of the two sets of opposing faces is inclined in a radial direction; opposing faces of adjacent teeth are parallel to each other; a cross-section of each tooth in a plane perpendicular to the radial direction has a trapezoidal shape, and wherein a perimeter of the cross-section is substantially a constant in the radial direction and an area of the cross-section varies in the radial direction; the base plate is formed of aluminum; the electric machine is an electric motor; the electric machine is an electric generator.

