Multi-wound rotor for electric machine

Abstract

The invention relates to a multi-wound rotor for an electric machine. The electric machine includes: a stator having a plurality of stator windings configured to generate a magnetic field; and a rotor configured to rotate within the stator according to a torque induced by the magnetic field. The rotor includes a plurality of electrically independent sets of rotor windings wound around each of the plurality of circumferentially spaced rotor projections. The electric machine also includes a power transfer circuit operable to independently control the electrical excitation of the rotor winding sets. The electric machine also includes a cooling system for dissipating heat from the rotor winding set.

Description

Technical Field

[0001] The present disclosure relates generally to electric machines, and more particularly to multi-wound rotors for electric machines. Background Art

[0002] Some electric machines include a rotor configured to rotate within a stator. Common implementations of those types of electric machines include a rotor having a single set of rotor windings operable to rotate in response to a magnetic field from the stator. Such implementations are widely used and are generally considered adequate. However, rotors having a single set of rotor windings may be relatively susceptible to torque fluctuations, particularly those resulting from oscillations in the current used in its excitation. This reliance on a single set of rotor windings, particularly when faced with torque fluctuations, may affect the overall performance of the electric machine. Summary of the invention

[0003] One aspect of the present disclosure relates to an electric machine having a multi-wound rotor. The multi-wound rotor may include a plurality of independently energizable rotor winding sets configured to minimize or reduce torque ripple. The present disclosure also relates to a cooling system that provides slot cooling of the multi-wound rotor and improves the thermal performance of the multi-wound rotor.

[0004] An electric machine is provided. The electric machine includes a stator including a plurality of stator windings configured to generate a magnetic field; and a rotor configured to rotate within the stator according to a torque induced by the magnetic field. The rotor includes a plurality of electrically independent rotor winding sets wound around each of a plurality of circumferentially spaced rotor protrusions. The electric machine also includes a power transmission circuit operable to independently control the electrical excitation of the rotor winding sets.

[0005] In some embodiments, the rotor winding set includes an inner set and an outer set, wherein the power transfer circuit is operable to provide an inner current operable to electrically excite the inner set, and an outer current operable to electrically excite the outer set.

[0006] In some embodiments, the inner and outer groups include a plurality of conductive coils wound with an equal number of turns.

[0007] In some embodiments, each of the winding sets includes: a plurality of conductive coils wound with more turns than the plurality of conductive coils of another of the winding sets.

[0008] In some embodiments, each of the winding sets includes a plurality of conductive coils composed of the same material.

[0009] In some embodiments, the plurality of conductive coils of one or more of the winding sets include a first material and the plurality of conductive coils of another of the winding sets include a second material different from the first material.

[0010] In some embodiments, each of the winding sets includes a plurality of conductive coils having the same cross-sectional area.

[0011] In some embodiments, the plurality of conductive coils of one or more of the winding sets have a first cross-sectional area and the plurality of conductive coils of another of the winding sets have a second cross-sectional area different from the first cross-sectional area.

[0012] In some embodiments, a conductive coil having a first cross-sectional area generates a first current density when energized with a first amount of current, and a conductive coil having a second cross-sectional area generates a second current density when energized with the first amount of current.

[0013] In some embodiments, the rotor includes a plurality of rotor slots formed between each adjacent rotor projection, and a cooling system configured to dissipate heat away from the rotor slots.

[0014] In some embodiments, the cooling system includes one or more cooling channels disposed within each of the rotor slots, and a coolant source configured to circulate a coolant through the cooling channels to dissipate heat therefrom.

[0015] In some embodiments, one or more of the cooling channels are shaped to wrap substantially around each of the winding sets.

[0016] In some embodiments, one or more of the cooling channels are shaped to contact three sides of each of the winding sets.

[0017] In some embodiments, the inner group is disposed radially inwardly relative to the outer group.

[0018] In some embodiments, the rotor slots are shaped to include an inner wall, an outer wall, an upper sidewall, and a lower sidewall such that an inner group is proximate to the inner wall and an outer group is proximate to the outer wall.

[0019] In some embodiments, one or more of the cooling channels are shaped to dissipate heat from an intermediate gap coinciding with an intermediate region between the inner group and the outer group.

[0020] In some embodiments, one or more of the cooling channels are shaped to dissipate heat from an internal gap coincident with an interior region between the interior group and an associated interior wall.

[0021] In some embodiments, one or more of the cooling channels are shaped to dissipate heat from an outer gap that coincides with an outer region between the outer group and an outer wall associated therewith.

[0022] According to an alternative embodiment, the electric machine includes a stator and a rotor configured to rotate within the stator. The rotor includes a plurality of circumferentially spaced rotor projections and a plurality of rotor slots formed between each adjacent rotor projection, wherein at least an inner rotor winding and an outer rotor winding are wound around each of the rotor projections. The inner rotor winding and the outer rotor winding are electrically isolated from each other. The electric machine also includes a power transmission circuit operable to independently control the electrical excitation of the rotor windings, and a cooling system configured to dissipate heat from the interior of the rotor projections. The cooling system includes one or more cooling channels disposed in each of the rotor slots, and a coolant source configured to circulate a coolant through the cooling channels to dissipate heat therefrom.

[0023] In some embodiments, a vehicle with an electric engine is provided. The vehicle includes a vehicle body, a plurality of drive wheels mounted to the vehicle body; and an electric motor mounted to the vehicle body. The electric motor is operable to drive one or more of the drive wheels to propel the motor vehicle. The electric motor includes: a stator having a plurality of stator windings configured to generate a magnetic field; and a rotor configured to rotate within the stator according to a torque induced by the magnetic field. The rotor includes a plurality of electrically independent rotor winding groups wound around each of a plurality of circumferentially spaced rotor protrusions. The rotor winding groups include an inner group and an outer group. The electric motor also includes a power transmission circuit operable to independently control the excitation of each of the rotor winding groups. The power transmission circuit is operable to provide an internal current operable to electrically excite the inner group, and an external current operable to electrically excite the outer group. The electric motor also includes a cooling system configured to dissipate heat from the rotor protrusions. The cooling system includes one or more cooling channels disposed in each of the rotor slots, and a coolant source configured to circulate a coolant through the cooling channels to dissipate heat therefrom. The rotor includes a plurality of rotor slots formed between each adjacent rotor projection, the rotor slots being formed to include an inner wall, an outer wall, an upper side wall, and a lower side wall such that the inner group is proximate to the inner wall and the outer group is proximate to the outer wall. The cooling passages are formed to dissipate heat from an intermediate gap coinciding with an intermediate region between the inner group and the outer group, from an inner gap coinciding with an inner region between the inner group and the associated inner wall, and from an outer gap coinciding with an outer region between the outer group and the outer wall associated therewith.

[0024] One aspect of the present disclosure relates to an electric machine, comprising: a stator, comprising a plurality of stator windings configured to generate a magnetic field; a rotor, configured to rotate within the stator according to a torque induced by the magnetic field, the rotor comprising a plurality of electrically independent rotor winding sets wound around each of a plurality of circumferentially spaced rotor protrusions; and a power transmission circuit operable to independently control the electrical excitation of the rotor winding sets.

[0025] In some embodiments, the rotor winding set includes an inner set and an outer set, wherein the power transfer circuit is operable to provide an inner current operable to electrically excite the inner set, and an outer current operable to electrically excite the outer set.

[0026] In some embodiments, the inner group includes a plurality of inner conductive coils and the outer group includes a plurality of outer conductive coils, wherein the inner conductive coils and the outer conductive coils are wound around the rotor protrusion with an equal number of turns.

[0027] In some embodiments, the inner group includes a plurality of inner conductive coils and the outer group includes a plurality of outer conductive coils, wherein the inner conductive coils and the outer conductive coils are wound around the rotor protrusion with unequal numbers of turns.

[0028] In some embodiments, the inner group includes a plurality of inner conductive coils and the outer group includes a plurality of outer conductive coils, wherein the inner conductive coils and the outer conductive coils are composed of the same material.

[0029] In some embodiments, the plurality of conductive coils of one or more of the winding sets include a first material, and the plurality of conductive coils of another of the winding sets include a second material different from the first material.

[0030] In some embodiments, each of the winding sets includes a plurality of conductive coils having the same cross-sectional area.

[0031] In some embodiments, the plurality of conductive coils of one or more of the winding sets have a first cross-sectional area, and the plurality of conductive coils of another of the winding sets have a second cross-sectional area different from the first cross-sectional area.

[0032] In some embodiments, the conductive coil having the first cross-sectional area generates a first current density when excited with a first amount of current, and the conductive coil having the second cross-sectional area generates a second current density when excited with the first amount of current.

[0033] In some embodiments, the rotor includes a plurality of rotor slots formed between each adjacent rotor projection; and a cooling system configured to dissipate heat away from the rotor slots.

[0034] In some embodiments, the cooling system includes: one or more cooling channels disposed in each of the rotor slots; and a coolant source configured to circulate a coolant through the cooling channels to dissipate heat therefrom.

[0035] In some embodiments, one or more of the cooling channels are shaped to wrap substantially around each of the winding sets.

[0036] In some embodiments, one or more of the cooling channels are shaped to contact three sides of each of the winding sets.

[0037] In some embodiments, the rotor winding set includes an inner set and an outer set, the inner set being disposed radially inward relative to the outer set.

[0038] In some embodiments, the rotor slots are shaped to include an inner wall, an outer wall, an upper side wall, and a lower side wall such that the inner group is proximate to the inner wall and the outer group is proximate to the outer wall.

[0039] In some embodiments, one or more of the cooling channels are shaped to dissipate heat from an intermediate gap coinciding with an intermediate region between the inner group and the outer group.

[0040] In some embodiments, one or more of the cooling channels are shaped to dissipate heat from an internal gap coincident with an interior region between the interior group and an associated interior wall.

[0041] In some embodiments, one or more of the cooling channels are shaped to dissipate heat from an external gap coincident with an external region between the outer group and an outer wall associated therewith.

[0042] Another aspect of the present disclosure relates to an electric machine, comprising: a stator; a rotor configured to rotate within the stator, the rotor comprising a plurality of circumferentially spaced rotor projections and a plurality of rotor slots formed between each adjacent rotor projection, wherein at least an inner rotor winding and an outer rotor winding are wound around each of the rotor projections, the inner rotor winding and the outer rotor winding being independently excitable; a power transmission circuit operable to independently control the electrical excitation of the rotor windings; and a cooling system configured to dissipate heat from the interior of the rotor projections, the cooling system comprising one or more cooling channels disposed in each of the rotor slots, and a coolant source configured to circulate a coolant through the cooling channels to dissipate heat therefrom.

[0043] Another aspect of the present disclosure relates to a motor vehicle, comprising: a vehicle body; a plurality of drive wheels mounted to the vehicle body; and a synchronous motor mounted to the vehicle body and operable to drive one or more of the drive wheels to propel the motor vehicle, the synchronous motor comprising: a stator comprising a plurality of stator windings configured to generate a magnetic field; a rotor configured to rotate within the stator according to a torque induced by the magnetic field, the rotor comprising a plurality of electrically independent rotor winding sets wound around each of a plurality of circumferentially spaced rotor protrusions, the rotor winding sets comprising an inner set and an outer set; a power transmission circuit operable to independently control the excitation of each of the rotor winding sets, the power transmission circuit operable to provide an internal current operable to electrically excite the inner set, and an internal current operable to electrically excite the outer set. an external current for electrically exciting the group; and a cooling system configured to dissipate heat from the rotor protrusions, the cooling system comprising one or more cooling channels disposed in each of the rotor slots, and a coolant source configured to circulate a coolant through the cooling channels to dissipate heat therefrom, wherein the rotor comprises a plurality of rotor slots formed between each adjacent rotor protrusion, the rotor slots being formed to include an inner wall, an outer wall, an upper side wall and a lower side wall such that the inner group is proximate to the inner wall and the outer group is proximate to the outer wall, wherein the cooling channels are formed to dissipate heat from an intermediate gap coinciding with an intermediate region between the inner group and the outer group, from an internal gap coinciding with an internal region between the inner group and an associated inner wall, and from an external gap coinciding with an external region between the outer group and an outer wall associated therewith.

[0044] These features and advantages and other features and advantages of the present teachings can be readily apparent from the following detailed description of the modes for implementing the present teachings when understood in conjunction with the accompanying drawings. It should be understood that even though the following drawings and embodiments may be described separately, their individual features may also be combined into additional embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The accompanying drawings, which may be incorporated in and constitute a part of this specification, illustrate implementations of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0046] Figure 1 is a perspective view of an electric machine having a stator and a rotor within the stator according to one or more implementations of the present disclosure.

[0047] Figure 2 is a perspective view of a rotor having multiple rotor projections including multiple rotor winding sets according to one or more implementations of the present disclosure.

[0048] Figure 3 is a schematic diagram of a cross-sectional portion of a rotor having a plurality of rotor winding sets in electrical communication with a power transmission circuit according to one or more implementations of the present disclosure.

[0049] Figure 4-5 is an exemplary cross-sectional view of a portion of a rotor having multiple rotor winding sets interacting with cooling channels of a cooling system according to one or more implementations of the present disclosure. DETAILED DESCRIPTION

[0050] As required, detailed embodiments of the present disclosure are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the present disclosure, and the present disclosure may be embodied in various and alternative forms. The drawings are not necessarily drawn to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein are not to be construed as limiting, but merely as a representative basis for teaching those skilled in the art to adopt the present disclosure in different ways.

[0051] Figure 1 is a perspective view of an electric machine 100 having a stator 110 and a rotor 120 within the stator 110 according to one or more implementations of the present disclosure. The electric machine 100 includes a stator 110 having a plurality of stator windings or other features suitable for generating a rotating magnetic field (RMF).

[0052] The motor 100 may include a base 102 coupled to a housing 104 of the motor 100. The housing 104 may be coupled to a plurality of sets of fins 106 for dissipating heat generated by the motor 100. The motor 100 may include a controller for controlling input alternating current (AC) and monitoring parameters, among other things.

[0053] Still reference Figure 1 , stator slots 112 arranged around the inner portion of the stator 110 open to an air gap 108, which separates the stator 110 and the rotor 120. For simplicity, although the stator slots 112 in the stator 110 and the various openings in the rotor 120 directly open to the air gap 108, Figure 1 The air gap 108 is defined using two circles extending around the inner periphery of the stator 110 and the outer portion of the rotor 120. The rotor 120 in this configuration has a cylindrical profile, although this geometry may vary widely and other rotors may employ different geometries, for example, using different numbers and geometries of poles distributed around the rotor 120, or otherwise. An annular housing 109 is provided on the outer periphery of the stator 110.

[0054] The rotor 120 is configured to rotate within the stator 110 according to a torque induced by a magnetic field. The rotor 120 includes a plurality of electrically independent rotor winding sets 150 wound around each of the plurality of rotor protrusions 130, such as Figure 2 The rotor winding set 150 is configured to be electrically excited by direct current. Each winding set 150 includes an inner set 152 and an outer set 154. Although two sets are shown, it is understood that the rotor winding set 150 includes two or more sets.

[0055] Figure 1 The motor 100 also shows a shaft 115. Depending on the application, the shaft 115 can rotate with the rotor 120 under different loads to perform work. For example, the rotating shaft 115 can be used to rotate one or more wheels of a vehicle.

[0056] As used herein, "vehicle" or "motor vehicle" may be used interchangeably and is understood to mean a device configured for transporting a person, thing, object, or the like. Non-limiting examples of motor vehicles (e.g., internal combustion engine (ICE) vehicles, electric vehicles including battery and fuel cell vehicles, or the like) include land vehicles (e.g., cars, trucks, motorcycles, electric bicycles, buses, trains, or the like), air vehicles (e.g., airplanes, helicopters, drones, or the like), water vehicles (e.g., boats, ships, or the like), and amphibious vehicles (e.g., hovercrafts, or the like).

[0057] Additional aspects of the present disclosure relate to an electric motor 100 that is operably disposed, incorporated, or otherwise used in a vehicle, such as an electric vehicle. In one embodiment, the electric vehicle includes a vehicle body, a plurality of drive wheels mounted to the vehicle body, and an electric motor 100 mounted to the vehicle body and operable to drive one or more of the drive wheels to propel the electric vehicle.

[0058] The electric machine 100 can be used as a motor that converts electrical energy into mechanical energy, as discussed above with respect to propulsion of an electric vehicle. Alternatively, the electric machine 100 can be used as a generator that converts mechanical energy into electrical energy. Regardless of the mode of use, the electric machine 100 operates according to the principles of electromagnetic induction, where the movement of a conductor within a magnetic field produces a voltage (as in the case of an electric motor), and the interaction between the magnetic field and the current produces mechanical motion (as in the case of a generator).

[0059] Figure 2 is a perspective view of a rotor 120 having a plurality of rotor projections 130 including a plurality of rotor winding sets 150 according to one or more implementations of the present disclosure.

[0060] like Figure 2 As shown, the rotor 120 includes eight rotor protrusions 130, wherein a winding set 150 is wound around each of the eight rotor protrusions 130. Figure 2 1 , eight rotor protrusions 130 are shown, but it is understood that the rotor 120 may have more or less than eight rotor protrusions 130. For example, the rotor 120 may have 2, 4, 6, 8, 10, 12 or more rotor protrusions 130.

[0061] Each winding set 150 includes an inner set 152 and an outer set 154 which are independently excited by a power transfer circuit 160, such as Figure 3 The inner group 152 is radially disposed between the outer group 154 ​​and the rotational center axis of the rotor 120. The inner group 152 includes a plurality of conductive coils wound around one of the eight rotor protrusions 130 with N turns. Each inner group 152 with respect to the corresponding rotor protrusion 130 may have N turns, or may have a number of turns greater than or less than the N number.

[0062] The multiple conductive coils of the inner group 152 can have the same cross-sectional area and produce current density when excited by current (i.e., direct current). The multiple conductive coils of the inner group 152 can have different cross-sectional areas and produce different current densities when excited with the same amount of current.

[0063] The outer group 154 ​​also includes a plurality of conductive coils wound around each of the eight rotor projections 130 with M turns. Each outer group 154 ​​with respect to the corresponding rotor projection 130 may have M turns, or may have more or less than the M number of turns.

[0064] The multiple conductive coils of the outer group 154 ​​can have the same cross-sectional area and produce current density when excited by current (i.e., direct current). The multiple conductive coils of the outer group 154 ​​can have different cross-sectional areas and produce different current densities when excited with the same amount of current.

[0065] For both the inner group 152 and the outer group 154, the conductive coils are conductive. The conductive coils can be made of the same material or different materials. The material can be copper, aluminum, copper clad aluminum (CCA), silver-plated copper, silver-plated copper, copper-coated steel or other conductive materials. The conductive coils can also have the same or different wire gauge sizes.

[0066] Figure 3 is a schematic diagram of a cross-sectional portion of a rotor 120 having a plurality of rotor winding sets 150 in electrical communication with a power delivery circuit 160 according to one or more implementations of the present disclosure. Figure 3 As shown, the portion of the rotor 120 includes a rotor slot 140 defined by two adjacent rotor protrusions 130 (eg, an upper rotor protrusion 130A and a lower rotor protrusion 130B).

[0067] The rotor slot 140 includes an inner wall 142, an outer wall 144, an upper side wall 146, and a lower side wall 148. The inner wall 142 is radially located at a distance from the center of the rotor 120. The outer wall 144 is radially located at a distance from the center of the rotor 120 greater than the distance between the inner wall 142 and the center of the rotor 120.

[0068] The upper sidewall 146 and the lower sidewall 148 are connected to the inner wall 142 and the outer wall 144 in a manner that forms an enclosure within the rotor slot 140. The upper sidewall 146 is part of one of the protrusions, namely the upper rotor protrusion 130A. The lower sidewall 148 is part of the other protrusion, namely the lower rotor protrusion 130B.

[0069] Each of the rotor projections 130 is wound with a rotor winding set 150 having an inner set 152 and an outer set 154. For each rotor projection 130, the inner set 152 is disposed between the inner wall 142 and the outer set 154. Likewise, for each rotor projection 130, the outer set 154 is disposed between the inner set 152 and the outer wall 144. The inner sets 152 are electrically connected to each other. The outer sets 154 are electrically connected to each other.

[0070] The power transmission circuit 160 is operable to independently control the electrical excitation of the rotor winding set 150 by providing current (e.g., an internal current 162 and an external current 164) to the rotor winding set 150. The internal current 162 and the external current 164 are in the form of direct current. The power transmission circuit 160 is electrically connected to form an electrical circuit with the internal set 152 and is configured to provide the internal current 162 to the internal set 152. During operation of the motor 100, the internal set 152 is electrically excited by the internal current 162.

[0071] The power transmission circuit 160 is electrically connected to form a circuit with the external group 154, and is configured to provide an external current 164 to the external group 154. During operation of the motor 100, the external group 154 ​​is electrically excited by the external current 164. The internal group 152 and the external group 154 ​​can be electrically excited separately or simultaneously because the internal group 152 and the external group are connected to the power transmission circuit 160 on separate circuits.

[0072] The power transmission circuit 160 includes brushes and slip rings (not shown) for the inner group 152 and for the outer group 154. The brushes and slip rings allow the rotor 120 to rotate within the stator 110 while supplying current to the inner group 152 and the outer group 154. The power transmission circuit 160 also includes a power supply for supplying electrical energy to the power transmission circuit 160. The power transmission circuit 160 may also include a field control circuit for regulating the current supplied to the rotor winding group 150 and an armature control circuit for adjusting the voltage or current supplied to the rotor winding group 150. An example of an armature control circuit is a pulse width modulation (PWM) controller.

[0073] During operation of the motor 100, the stator 110 is excited with an alternating current and generates a magnetic field. The inner group 152 is excited with an inner current 162 supplied by the power transmission circuit 160 and generates a magnetic field. Likewise, the outer group 154 ​​is excited with an outer current 164 supplied by the power transmission circuit 160 and generates a magnetic field. The magnetic fields of the inner group 152 and the outer group 154 ​​interact with the magnetic field of the stator 110, causing the rotor 120 to rotate within the stator 110 according to the torque induced by the magnetic field of the stator 110 and create an output torque of the motor 100.

[0074] The output torque includes torque fluctuations because the alternating current is not a steady current flow, but contains variations or harmonics in the current. In order to reduce or minimize the torque fluctuations, the internal current 162 and the external current 164 are offset in time or position (i.e., electrical angle) while being supplied to the internal group 152 and the external group 154, respectively. The offset of the internal current 162 and the external current 164 has the effect of canceling some of the harmonics in the harmonics. Because the components of the torque fluctuations are caused by the harmonics, the torque fluctuations are reduced or minimized. Reducing or minimizing the torque fluctuations improves the performance of the motor 100.

[0075] In addition to improved performance, winding set 150 provides redundancy in the event that inner set 152 or outer set 154 degrades or ceases to operate. Since inner set 152 and outer set 154 are separately energized on different circuits, motor 100 will continue to operate if inner set 152 or outer set 154 ceases to function.

[0076] Figure 4-5 is an exemplary cross-sectional view of a portion of a rotor 120 having a plurality of rotor winding sets 150 interacting with cooling channels 170 of a cooling system according to one or more implementations of the present disclosure.

[0077] The cooling system is configured to remove thermal energy (i.e., heat) from the rotor slot 140. The cooling system includes one or more cooling channels 170 disposed in each of the rotor slots 140, and a cooling source (not shown) configured to pump or circulate a fluid through the cooling channel 170. The cooling source may use a pump or another device to circulate the fluid in the cooling channel 170. The cooling source may include one or more delivery channels (not shown) that axially traverse the rotor 120 and are in fluid communication with the cooling channel 170. The cooling channel 170 may be physically connected to the one or more cooling channels 170. Both the delivery channel and the cooling channel 170 include a hollow interior for holding or conveying a fluid. Non-limiting examples of fluids include coolants, air, water, oil, and / or the like.

[0078] like Figure 4 and Figure 5 As shown, cooling channels 170 are disposed adjacent to winding sets 150 (eg, inner set 152 and outer set 154) to form a physical interface between cooling channels 170 and winding sets 150. This interface allows heat to be transferred from winding sets 150 to the fluid within cooling channels 170.

[0079] The cooling channel 170 is made of a highly thermally conductive material for transferring heat away from the winding set 150. Non-limiting examples of highly conductive materials are diamond, silver, copper, gold, aluminum nitride, silicon carbide, aluminum, tungsten, graphite, and zinc. The thermally conductive material may have a thermal conductivity of about 116 watts per meter per degree Kelvin (W / m K) or greater.

[0080] The cooling passages 170 may be wound around the winding set 150 in such a manner that the surface area of ​​the winding set 150 within the rotor slot 140 is substantially or completely covered by the cooling passages 170. For example, the cooling passages 170 may cover the surface area of ​​the inner set 152 disposed adjacent to the inner wall 142, the surface area disposed adjacent to the outer set 154, and the surface area disposed toward the interior of the rotor slot 140. Similarly, the cooling passages 170 may cover the surface area of ​​the outer set 154 disposed adjacent to the inner set 152, the surface area disposed adjacent to the outer wall 144, and the surface area disposed toward the interior of the rotor slot 140.

[0081] The cooling passages 170 may be shaped to dissipate heat from intermediate gaps coinciding with intermediate regions between the inner and outer groups 154. The cooling passages 170 may be shaped to dissipate heat from inner gaps coinciding with inner regions between the inner group 152 and the associated inner wall 142. The cooling passages 170 may be shaped to dissipate heat from outer gaps coinciding with outer regions between the outer group 154 ​​and the outer wall 144 associated therewith.

[0082] The cooling passage 170 may be coated with an insulating material to prevent electrical contact with the rotor winding set 150 and avoid reducing the performance of the motor 100. Non-limiting examples of insulating materials include epoxy resins.

[0083] Figure 4 The cooling channels 170 are shown without encapsulation. The cooling channels 170 may be supported by reinforcements to provide a rigid backing to portions of the cooling channels 170 that are not adjacent to the winding set 150. Non-limiting examples of reinforcements include steel, aluminum, cast iron, composites, plastics and polymers, thermosets, and / or the like.

[0084] Figure 5 The cooling passages 170 are shown with an encapsulation. The rotor slots 140 are encapsulated or filled with an encapsulation material 180 to provide rigid support to the cooling passages 170 that are not adjacent to the winding set 150. Non-limiting examples of encapsulation materials include epoxy resins, polyester resins, polyurethane resins, silicone rubbers, potting compounds, thermoplastic materials (e.g., polypropylene or polycarbonate), composite encapsulation materials combining resins with reinforcing fibers or fillers, and / or the like.

[0085] During operation of the motor, the winding set 150 increases in temperature. Heat is transferred from the winding set 150 to the fluid circulating within the cooling channel 170. The temperature of the fluid increases due to the additional thermal energy received by the fluid from the winding set 150. The fluid is transported away from the winding set 150 and then dissipates excess thermal energy before being recirculated through the cooling system. Once recirculated through the cooling system, the fluid returns via the cooling channel 170 to transfer thermal energy away from the winding set 150.

[0086] Unless specifically stated from the context, as used herein, the term "approximately" is understood to be within the normal tolerance range in the art, such as within 2 standard deviations of the mean. "Approximately" may be understood to be within 10%, 5%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. "Approximately" may alternatively be understood to imply the exact value stated. Unless otherwise clear from the context, numerical values ​​provided herein are modified by the term "approximately".

[0087] The terms "comprise", "include" and "have" are inclusive, and therefore specify the presence of the stated features, steps, operations, elements or parts, but do not exclude the presence or addition of one or more other features, steps, operations, elements or parts. The order of steps, processes and operations can be changed when possible, and additional or alternative steps can be adopted. As used in this specification, the term "or" includes any one and all combinations of the associated listed items. The term "any" is understood to include any possible combination of the cited items, including "any one" in the cited items. "One", "one", "the", "at least one" and "one or more" are used interchangeably to indicate that at least one of the items exists. Unless the context clearly indicates otherwise, multiple such items may exist. Unless otherwise clearly or clearly indicated in consideration of the context (including the attached claims), all values ​​of parameters (e.g., amount or condition) are to be understood as being modified by the term "approximately" in all cases, regardless of whether "approximately" actually appears before the value. The component "configured to" perform the specified function is able to perform the specified function without change, rather than just having the potential to perform the specified function after further modification. In other words, when expressly configured to perform the specified functions, the described hardware is specifically selected, created, implemented, utilized, programmed and / or designed for the purpose of performing the specified functions.

[0088] Although various embodiments are described, the description is intended to be exemplary, not restrictive, and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations within the scope of the embodiments are possible. Unless specifically limited, any feature of any embodiment can be used in combination with any other feature or element in any other embodiment, or replace any other feature or element in any other embodiment. Therefore, the embodiments are not limited except according to the attached claims and their equivalents. Moreover, various modifications and changes can be made within the scope of the attached claims. Although several modes for implementing many aspects of this teaching are described in detail, technicians familiar with the fields involved in these teachings will recognize various alternative aspects within the scope of the attached claims for practicing this teaching. It is intended that all the contents contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and exemplary for the entire scope of alternative embodiments, wherein ordinary skill will recognize that the alternative embodiments are implied by the included content, are structurally and / or functionally equivalent to the included content, or otherwise become apparent based on the included content, and are not limited to those embodiments that are clearly depicted and / or described.

Claims

1. A motor, comprising: a stator including a plurality of stator windings configured to generate a magnetic field; a rotor configured to rotate within the stator in accordance with a torque induced by the magnetic field, the rotor comprising a plurality of electrically independent rotor winding sets wound around each of a plurality of circumferentially spaced rotor lobes; as well as A power transfer circuit is operable to independently control the electrical excitation of the rotor winding sets.

2. The electric machine according to claim 1, wherein: The rotor winding set includes an inner set and an outer set, wherein the power transfer circuit is operable to provide an inner current operable to electrically excite the inner set, and an outer current operable to electrically excite the outer set.

3. The electric machine according to claim 2, wherein: The inner group includes a plurality of inner conductive coils and the outer group includes a plurality of outer conductive coils, wherein the inner conductive coils and the outer conductive coils are wound around the rotor protrusion with an equal number of turns.

4. The electric machine according to claim 1, wherein: The plurality of conductive coils of one or more of the winding sets have a first cross-sectional area, and the plurality of conductive coils of another of the winding sets have a second cross-sectional area that is different from the first cross-sectional area.

5. The electric machine according to claim 4, wherein: The conductive coil having the first cross-sectional area generates a first current density when excited with a first amount of current, and the conductive coil having the second cross-sectional area generates a second current density when excited with the first amount of current.

6. The electric machine according to claim 1, further comprising: The rotor includes a plurality of rotor slots formed between each adjacent rotor projection; as well as A cooling system is configured to dissipate heat away from the rotor slots.

7. The electric machine according to claim 6, wherein: The cooling system comprises: one or more cooling passages disposed in each of the rotor slots; and A coolant source is configured to circulate a coolant through the cooling passage to dissipate heat therefrom.

8. The electric machine according to claim 7, wherein: The rotor winding group includes an inner group and an outer group, and the inner group is arranged radially inward relative to the outer group.

9. The electric machine according to claim 8, wherein: The rotor slots are shaped to include an inner wall, an outer wall, an upper side wall, and a lower side wall such that the inner group is proximate to the inner wall and the outer group is proximate to the outer wall.

10. A motor vehicle comprising: Car body; a plurality of drive wheels mounted to the vehicle body; as well as a synchronous motor mounted to the vehicle body and operable to drive one or more of the drive wheels to propel the motor vehicle, the synchronous motor comprising: a stator including a plurality of stator windings configured to generate a magnetic field; a rotor configured to rotate within the stator in accordance with a torque induced by the magnetic field, the rotor comprising a plurality of electrically independent rotor winding sets wound around each of a plurality of circumferentially spaced rotor projections, the rotor winding sets comprising an inner set and an outer set; a power transfer circuit operable to independently control the excitation of each of the rotor winding sets, the power transfer circuit operable to provide an inner current operable to electrically excite the inner set, and an outer current operable to electrically excite the outer set; and a cooling system configured to dissipate heat from the rotor protrusion, the cooling system comprising one or more cooling passages disposed in each of the rotor slots, and a coolant source configured to circulate a coolant through the cooling passages to dissipate heat therefrom, wherein the rotor includes a plurality of rotor slots formed between each adjacent rotor protrusion, the rotor slots being formed to include an inner wall, an outer wall, an upper side wall, and a lower side wall such that the inner group is proximate to the inner wall and the outer group is proximate to the outer wall, wherein the cooling passage is shaped to dissipate heat from an intermediate gap coinciding with an intermediate region between the inner group and the outer group, from an inner gap coinciding with an inner region between the inner group and an associated inner wall, and from an outer gap coinciding with an outer region between the outer group and an outer wall associated therewith.

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