Propulsion system with dual wound electric motor and dual inverter

Abstract

The invention relates to a propulsion system with a dual wound electric motor and dual inverter configuration. A propulsion system for a vehicle includes an electric motor configured to generate torque to propel the vehicle. The electric motor has a stator assembly having a plurality of stator slots defining slot layers along respective slot axes. A first plurality of conductors is positioned at least partially in the plurality of stator slots and forms a first winding set. A second plurality of conductors is positioned at least partially in the plurality of stator slots and forms a second winding set. The first inverter is adapted to drive the electric motor, and the first set of windings is coupled to the first inverter. The second inverter is adapted to drive the electric motor, and the second set of windings is coupled to the second inverter. The system includes a controller adapted to control operation of the first inverter and the second inverter based in part on a motor speed of the electric motor.

Description

Technical Field

[0001] The present disclosure generally relates to a propulsion system for a vehicle having an electric motor. More specifically, the present disclosure relates to a propulsion system having a dual-wound electric motor and a dual inverter configuration. Background Art

[0002] An electric machine typically includes a stator with multiple stator windings and a rotor that can rotate within the stator. In generator mode, the rotation of the rotor induces a voltage in the stator windings that powers an external load, such as charging a battery pack. Alternatively, if current is passed through the stator windings, the energized coils rotate the rotor and the machine will act as a motor. Winding losses in the stator windings in a permanent magnet motor can become a challenging issue at various operating speeds. Summary of the invention

[0003] A propulsion system for a vehicle having an electric motor is disclosed herein. The electric motor includes a stator assembly having a plurality of stator slots defining slot layers along respective slot axes. A first plurality of conductors are at least partially positioned in the plurality of stator slots and form a first winding set. A second plurality of conductors are at least partially positioned in the plurality of stator slots and form a second winding set. The propulsion system includes a first inverter adapted to drive the electric motor, the first winding set being coupled to the first inverter. The second inverter is adapted to drive the electric motor, the second winding set being coupled to the second inverter. The system includes a controller having a processor and a tangible, non-transitory memory having instructions recorded thereon. The controller is adapted to control the operation of the first inverter and the second inverter based in part on a motor speed of the electric motor.

[0004] In one embodiment, both the first inverter and the second inverter are three-level inverters. The first inverter is adapted to carry a first current, and the second inverter is adapted to carry a second current. The operation of the first inverter and the second inverter may be controlled such that: when the motor speed is above a predetermined threshold, the first current is greater than the second current; and when the motor speed is below the predetermined threshold, the second current is greater than the first current. The second current may be approximately 5% higher than the first current.

[0005] Each of the first plurality of conductors may be radially inward along the corresponding slot axis relative to each of the second plurality of conductors such that the first plurality of conductors are closer to an air gap of the stator assembly. In a first embodiment, the first plurality of conductors extend a first conductor length along the corresponding slot axis and the second plurality of conductors extend a second conductor length along the slot axis, the first conductor length being less than the second conductor length. In a second embodiment, the first plurality of conductors and the second plurality of conductors define equal conductor lengths.

[0006] In a third embodiment, the first plurality of conductors may be staggered with the second plurality of conductors along the respective slot axis. Here, the first plurality of conductors extend a first conductor length along the respective slot axis, and the second plurality of conductors extend a second conductor length along the slot axis, wherein the first conductor length is less than the second conductor length. Here, at least one of the second plurality of conductors may incorporate a split configuration having two equal conductor segments. In one example, the split configuration extends in a radial direction parallel to the respective slot axis. In another example, the split configuration extends in a circumferential direction perpendicular to the respective slot axis.

[0007] Disclosed herein is a method of operating a propulsion system in a vehicle, the propulsion system having an electric motor configured to generate torque and a controller having a processor and a tangible non-transitory memory. The method includes incorporating a stator assembly in the electric motor, the stator assembly having a plurality of stator slots defining slot layers along respective slot axes. The method includes: forming a first winding set by positioning a first plurality of conductors in the plurality of stator slots; and forming a second winding set by positioning a second plurality of conductors in the plurality of stator slots. The method includes: coupling the first winding set to a first inverter adapted to drive the electric motor; and coupling the second winding set to a second inverter adapted to drive the electric motor. Operation of the first inverter and the second inverter is controlled via the controller based in part on a motor speed of the electric motor.

[0008] The method may include setting a first current greater than a second current via the controller when the motor speed is above a predetermined threshold; and setting the second current greater than the first current via the controller when the motor speed is below the predetermined threshold.

[0009] In one embodiment, the method includes positioning each of the first plurality of conductors radially inwardly along the corresponding slot axis relative to each of the second plurality of conductors such that the first plurality of conductors are closer to an air gap of the stator assembly. The first plurality of conductors and the second plurality of conductors may define different conductor lengths. The first plurality of conductors and the second plurality of conductors may define equal conductor lengths.

[0010] In another embodiment, the method includes staggering the first plurality of conductors with the second plurality of conductors along a respective slot axis. Here, the first plurality of conductors extend a first conductor length along the respective slot axis and the second plurality of conductors extend a second conductor length along the slot axis, wherein the first conductor length is less than the second conductor length. A split configuration is incorporated in at least one of the second plurality of conductors, the split configuration being defined by two equal conductor segments.

[0011] Disclosed herein is a vehicle including an electric motor having a stator assembly having a plurality of stator slots defining slot layers along respective slot axes. The electric motor is configured to generate torque for propelling the vehicle. A first plurality of conductors are at least partially positioned in the plurality of stator slots and form a first winding set. A second plurality of conductors are at least partially positioned in the plurality of stator slots and form a second winding set. A first inverter is adapted to drive the electric motor, the first winding set being coupled to the first inverter. A second inverter is adapted to drive the electric motor, the second winding set being coupled to the second inverter.

[0012] The vehicle includes a controller having a processor and a tangible non-transitory memory having instructions recorded thereon. The controller is adapted to control the operation of a first inverter and a second inverter based in part on a motor speed of an electric motor. The first inverter is adapted to carry a first current and the second inverter is adapted to carry a second current. The operation of the first inverter and the second inverter is controlled such that: when the motor speed is above a predetermined threshold, the first current is greater than the second current; and when the motor speed is above a predetermined threshold, the second current is greater than the first current.

[0013] The present invention also includes the following technical solutions:

[0014] Solution 1. A propulsion system comprising:

[0015] an electric motor having a stator assembly with a plurality of stator slots defining slot layers along respective slot axes;

[0016] a first plurality of conductors positioned at least partially in the plurality of stator slots, the first plurality of conductors forming a first winding set;

[0017] a second plurality of conductors positioned at least partially in the plurality of stator slots, the second plurality of conductors forming a second winding set;

[0018] a first inverter adapted to drive the electric motor, the first winding set being coupled to the first inverter;

[0019] a second inverter adapted to drive the electric motor, the second winding set being coupled to the second inverter; and

[0020] A controller having a processor and tangible, non-transitory memory having instructions recorded thereon, the controller being adapted to control operation of the first inverter and the second inverter based in part on a motor speed of the electric motor.

[0021] Option 2. The propulsion system according to Option 1, wherein both the first inverter and the second inverter are three-level inverters.

[0022] Solution 3. A propulsion system according to Solution 1, wherein the first inverter is adapted to carry a first current, the second inverter is adapted to carry a second current, and operations of the first inverter and the second inverter are controlled such that:

[0023] When the motor speed is higher than a predetermined threshold, the first current is greater than the second current; and

[0024] When the motor speed is lower than the predetermined threshold, the second current is greater than the first current.

[0025] Option 4. The propulsion system of Option 3, wherein the second current is approximately 5% higher than the first current.

[0026] Option 5. A propulsion system according to Option 1, wherein each of the first plurality of conductors is radially inward along the corresponding slot axis relative to each of the second plurality of conductors so that the first plurality of conductors are closer to the air gap of the stator assembly.

[0027] Option 6. A propulsion system according to Option 1, wherein the first plurality of conductors extend a first conductor length along the corresponding slot axis, and the second plurality of conductors extend a second conductor length along the slot axis, the first conductor length being less than the second conductor length.

[0028] Option 7. A propulsion system according to Option 1, wherein the first plurality of conductors and the second plurality of conductors define equal conductor lengths.

[0029] Option 8. The propulsion system of Option 1, wherein:

[0030] The first plurality of conductors are staggered with the second plurality of conductors along the respective slot axes;

[0031] the first plurality of conductors extending a first conductor length along the respective slot axis and the second plurality of conductors extending a second conductor length along the slot axis, the first conductor length being less than the second conductor length; and

[0032] At least one of the second plurality of conductors incorporates a split configuration having two equal conductor segments.

[0033] Option 9. A propulsion system according to Option 8, wherein the split structure extends in a radial direction parallel to the corresponding slot axis.

[0034] Option 10. A propulsion system according to Option 8, wherein the split structure extends in a circumferential direction perpendicular to the corresponding slot axis.

[0035] Embodiment 11. A method of operating a propulsion system in a vehicle, the propulsion system having an electric motor configured to generate torque and a controller having a processor and a tangible non-transitory memory, the method comprising:

[0036] incorporating in the electric motor a stator assembly having a plurality of stator slots defining slot layers along respective slot axes;

[0037] forming a first winding set by positioning a first plurality of conductors in the plurality of stator slots;

[0038] forming a second winding set by positioning a second plurality of conductors in the plurality of stator slots;

[0039] coupling the first winding set to a first inverter adapted to drive the electric motor;

[0040] coupling the second winding set to a second inverter adapted to drive the electric motor; and

[0041] Operation of the first inverter and the second inverter are controlled via the controller based in part on a motor speed of the electric motor.

[0042] Solution 12. The method according to solution 11 further includes:

[0043] When the motor speed is higher than a predetermined threshold, setting the first current to be greater than the second current via the controller; and

[0044] When the motor speed is below the predetermined threshold, the second current is set via the controller to be greater than the first current.

[0045] Solution 13. The method according to Solution 12 further includes:

[0046] Each of the first plurality of conductors is positioned radially inwardly along the corresponding slot axis relative to each of the second plurality of conductors such that the first plurality of conductors is closer to an air gap of the stator assembly, the first and second pluralities of conductors defining different conductor lengths.

[0047] Solution 14. The method according to Solution 12 further includes:

[0048] Each of the first plurality of conductors is positioned radially inwardly along the corresponding slot axis relative to each of the second plurality of conductors such that the first plurality of conductors is closer to an air gap of the stator assembly, the first and second plurality of conductors defining equal conductor lengths.

[0049] Solution 15. The method according to Solution 12 further includes:

[0050] staggering the first plurality of conductors with the second plurality of conductors along the respective slot axes, the first plurality of conductors extending a first conductor length along the respective slot axes and the second plurality of conductors extending a second conductor length along the slot axes, the first conductor length being less than the second conductor length; and

[0051] A split configuration is incorporated in at least one of the second plurality of conductors, the split configuration being defined by two equal conductor segments.

[0052] Solution 16. A vehicle, comprising:

[0053] an electric motor having a stator assembly with a plurality of stator slots defining slot layers along respective slot axes, the electric motor being configured to generate torque for propulsion;

[0054] a first plurality of conductors at least partially positioned in the plurality of stator slots and forming a first winding set;

[0055] a second plurality of conductors at least partially positioned in the plurality of stator slots and forming a second winding set;

[0056] a first inverter adapted to drive the electric motor, the first winding set being coupled to the first inverter;

[0057] a second inverter adapted to drive the electric motor, the second winding set being coupled to the second inverter; and

[0058] a controller having a processor and tangible, non-transitory memory having instructions recorded thereon, the controller adapted to control operation of the first inverter and the second inverter based in part on a motor speed of the electric motor;

[0059] The first inverter is adapted to carry a first current, and the second inverter is adapted to carry a second current, and operations of the first inverter and the second inverter are controlled such that:

[0060] When the motor speed is higher than a predetermined threshold, the first current is greater than the second current; and

[0061] When the motor speed is above a predetermined threshold, the second current is greater than the first current.

[0062] Embodiment 17. The vehicle according to embodiment 16, wherein:

[0063] each of the first plurality of conductors is radially inward along the respective slot axis relative to each of the second plurality of conductors such that the first plurality of conductors are closer to an air gap of the stator assembly; and

[0064] The first plurality of conductors and the second plurality of conductors define equal conductor lengths.

[0065] Embodiment 18. The vehicle according to embodiment 16, wherein:

[0066] each of the first plurality of conductors is radially inward along the respective slot axis relative to each of the second plurality of conductors such that the first plurality of conductors are closer to an air gap of the stator assembly; and

[0067] The first plurality of conductors extend a first conductor length along the respective slot axis and the second plurality of conductors extend a second conductor length along the slot axis, the first conductor length being less than the second conductor length.

[0068] Embodiment 19. The vehicle according to embodiment 16, wherein:

[0069] The first plurality of conductors are staggered with the second plurality of conductors along the respective slot axes;

[0070] the first plurality of conductors extending a first conductor length along the respective slot axis and the second plurality of conductors extending a second conductor length along the slot axis, the first conductor length being less than the second conductor length; and

[0071] At least one of the second plurality of conductors incorporates a split configuration having two equal conductor segments.

[0072] Option 20. The vehicle according to Option 16, wherein the split structure extends in a radial direction parallel to the corresponding slot axis.

[0073] The above features and advantages and other features and advantages of the present disclosure are readily apparent from the following detailed description of the best modes for carrying out the disclosure when taken in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 is a schematic partial perspective view of an electric motor / generator (referred to herein as an electric motor) having a stator assembly;

[0075] Figure 2 Is used to combine Figure 1 A schematic partial diagram of a propulsion system of a vehicle including an electric motor;

[0076] Figure 3 According to the first embodiment Figure 1 A schematic partial cross-sectional view of a stator assembly of FIG.

[0077] Figure 4 According to the second embodiment Figure 1 A schematic partial cross-sectional view of a stator assembly of FIG.

[0078] Figure 5A According to the third embodiment Figure 1 A schematic partial cross-sectional view of a stator assembly of FIG.

[0079] Figure 5B It's a picture. Figure 5A Schematic diagrams of alternative split configurations of components; and

[0080] Figure 6 yes Figure 1 Schematic diagram of an exemplary inverter architecture that may be employed by a system.

[0081] Representative embodiments of the present disclosure are shown in the accompanying drawings by way of non-limiting examples and are described in more detail below. However, it should be understood that the novel aspects of the present disclosure are not limited to the specific forms shown in the drawings listed above. On the contrary, the present disclosure will cover modifications, equivalents, combinations, sub-combinations, permutations, groupings, and alternatives that fall within the scope of the present disclosure as, for example, covered by the appended claims. DETAILED DESCRIPTION

[0082] Referring to the drawings, wherein like reference numerals refer to like parts, Figure 1 is a schematic partial perspective view of an electric motor / generator or electric traction machine, referred to herein as electric motor 10, having a stator assembly 12. Electric motor 10 is configured to produce motor torque by, for example, converting electrical energy into rotational motion.

[0083] refer to Figure 2 , the electric motor 10 may be part of a propulsion system 11 in a vehicle V. The vehicle V may be a mobile platform such as, but not limited to, a passenger car, a sport utility vehicle, a light truck, a heavy vehicle, an ATV, a minivan, a bus, a transport vehicle, a bicycle, a robot, a farm implement, sports-related equipment, a boat, an airplane, a train, or other device. The vehicle V may take many different forms and include multiple and / or alternative components and facilities.

[0084] Figure 3 3 is a schematic partial cross-sectional view through the axis 3-3 of the electric motor 10 according to the first embodiment. Figure 3 , the electric motor 10 includes a rotor assembly 14 that is rotatable relative to and within the stator assembly 12. For clarity, Figure 1 The rotor assembly 14 is omitted. The rotor assembly 14 may be annular in shape and include one or more permanent magnets 16. Figure 2 , the rotor assembly 14 may include, but is not limited to, interior permanent magnets, surface permanent magnets, induction, synchronous, reluctance, or a separately excited / wound field rotor.

[0085] refer to Figure 1 and Figure 3 , the stator assembly 12 includes a plurality of stator slots 18 (hereinafter "plurality" is omitted) extending through the stator core 20. The number of slots and poles in the stator assembly 12 may vary based on the application at hand. Figure 1 , the stator slots 18 may be evenly spaced radially from one another.

[0086] refer to Figure 3 , the stator slots 18 are defined in slot layers or arranged in slot layers along corresponding slot axes SA, such as first slot layers, second slot layers, third slot layers, fourth slot layers, fifth slot layers, and sixth slot layers S1, S2, S3, S4, S5, and S6. It should be appreciated that the stator slots 18 may include different numbers of layers, including but not limited to four layers or eight layers. The stator slots 18 may be partially open slots, fully open slots, or closed slots. Reference Figure 3 The first slot layer S1 is closest to the air gap 26 of the stator assembly 12 and is farthest from the outer diameter 28 of the stator core 20. The sixth slot layer S6 is closest to the outer diameter 28 of the stator assembly 12 and is farthest from the air gap 26 of the stator assembly 12.

[0087] refer to Figure 1, the stator assembly 12 includes a plurality of conductors 30 that are segmented and include respective first legs 32, respective second legs 34, and respective curved portions 36 sandwiched therebetween. The plurality of conductors 30 are configured to allow current to flow from the respective first legs 32 to the respective second legs 34. As described below, the plurality of conductors 30 may incorporate various sizes. The plurality of conductors 30 may include small stranded conductors, as well as strip or hairpin shaped conductors. It is to be understood that the form and cross-sectional shape of the conductors may vary based on the application at hand.

[0088] refer to Figure 2 The plurality of conductors 30 have their respective first legs 32 inserted into one of the plurality of corresponding slot layers S1-S6 (see Figure 2 ), and insert its corresponding second leg portion 34 into another layer of the plurality of corresponding slot layers S1-S6 (see Figure 2 ). Slot liners (not shown) may be inserted into the stator slots 18 to electrically isolate the plurality of conductors 30 from each other and from the stator core to prevent phase-to-phase short circuits or phase-to-ground short circuits.

[0089] refer to Figure 1 The plurality of conductors 30 extend through the stator slots 18 between the crown end 38 and the weld end 40. Figure 1 , the plurality of conductors 30 can be inserted into the stator slots 18 at the crown end 38. Once the plurality of conductors 30 pass through the stator slots 18, their respective distal end portions 42 can be welded at the welding end 40 ( Figure 1 ) and connected to a multi-phase AC winding. It is to be understood that the number of conductor layers may vary based on the application at hand.

[0090] As described below, the propulsion system 11 has a dual-wound electric motor configuration and a dual inverter configuration to optimize the current density across the stator slots 18. The plurality of conductors 30 form two winding sets within the stator slots 18, thereby defining the same number of phases. In one embodiment, the number of phases is exactly three, such as a "U" phase, a "V" phase, and a "W" phase. In another embodiment, the number of phases is five. However, the electric motor 10 is not limited to a three-phase or five-phase motor, and the number of phases may be different than described herein.

[0091] The propulsion system 11 provides reduced motor copper losses at different operating speed regions, resulting in better thermal management and performance under high demand drive cycles. Figure 2, the electric motor 10 may be configured to use an alternating current (“AC”) voltage from a plurality of inverters, including a first inverter 50 and a second inverter 52, to generate rotational motion that is subsequently transmitted to wheels 54 of the vehicle V. To power the electric motor 10, direct current (“DC”) power is provided from one or more energy sources (not shown) to the first inverter 50 and the second inverter 52, which convert the DC power into AC power.

[0092] refer to Figure 2 , the propulsion system 11 includes a controller C having a processor P and a tangible non-transitory memory M having instructions recorded thereon. The controller C is adapted to control the operation of the first inverter 50 and the second inverter 52 based in part on the motor speed of the electric motor 10. The controller C may employ high frequency pulse width modulators 56, 58 to modulate and control the first inverter 50 and the second inverter 52 accordingly. In the illustrated embodiment, the first inverter 50 and the second inverter 52 each include six switches (e.g., semiconductor devices) arranged in three corresponding pairs.

[0093] refer to Figure 3 , the electric motor 10 has a double-wound configuration, wherein the first plurality of conductors 60 and the second plurality of conductors 62 are at least partially positioned in the stator slots 18. The term "at least partially positioned" is used because some portions of the conductors extend outside the stator slots 18 (see Figure 1 ).exist Figure 3 In the first embodiment shown in FIG. 1 , each conductor of the first plurality of conductors 60 is radially inward along the corresponding slot axis SA relative to each of the second plurality of conductors 62, so that the first plurality of conductors 60 are closer to the air gap 26 and farther from the outer diameter 28 of the stator assembly 12. In the embodiment shown, the first plurality of conductors 60 are in slot layers S1, S2, S3, and the second plurality of conductors 62 are in slot layers S4, S5, S6. The total number of conductors 30 in the stator assembly 12 is evenly divided between the first plurality of conductors 60 and the second plurality of conductors 62.

[0094] refer to Figure 3 , the first plurality of conductors 60 form a first inverter 50 (see Figure 2 ) so that the first inverter 50 generates an AC voltage across the first winding set 64. The second plurality of conductors forms a second winding set 66 coupled to the second inverter 52 so that the second inverter 52 generates an AC voltage across the second winding set 66.

[0095] refer to Figure 3, each conductor in the first plurality of conductors 60 extends radially along the slot axis SA by a first conductor length L1. Each conductor in the second plurality of conductors 62 extends radially along the slot axis SA by a second conductor length L2. The first conductor length L1 is less than the second conductor length L2, resulting in a different cross-section. Similarly, for the same radial length, each conductor in the first plurality of conductors 60 may be circumferentially narrower than each conductor in the second plurality of conductors 62, resulting in a different cross-section. Figure 3 , both the current and the current density are different between the first plurality of conductors 60 and the second plurality of conductors 62. The relatively smaller conductors (of the first plurality of conductors 60) placed near the air gap 26 are fed by the lower current first inverter 50, while the relatively larger conductors (of the second plurality of conductors 62) placed near the outer diameter 28 are fed from the higher current second inverter 52. This configuration keeps the current density similar across the stator slots 18, thereby minimizing AC losses in the electric motor 10. Additionally, due to the low current density, lower DC losses in the case of higher current operation are possible. In one example, approximately 40% to 60% of the slot area near the air gap 26 may be filled with small stranded conductors, and the remainder may include larger strip or hairpin conductors.

[0096] An alternative embodiment of the electric motor 10 is Figure 4 and Figure 5A and described below. Figure 4 , each of the first plurality of conductors 160 is radially inward along the corresponding slot axis SA relative to each of the second plurality of conductors 162, such that the first plurality of conductors 160 are closer to the air gap 126 of the stator assembly 112 and farther from the outer diameter 128 of the stator core 122. The first plurality of conductors 160 form a first inverter 50 (see Figure 2 ) and the second plurality of conductors 162 form a second winding set 166 coupled to the second inverter 52.

[0097] refer to Figure 4 The first and second plurality of conductors extend along respective slot axes SA by a first conductor length L1 and a second conductor length L2. Figure 4 The second embodiment shown in Figure 3 is similar to the first embodiment shown in Figure 4 , the first conductor length L1 and the second conductor length L2 are equal. The current and current density across the first and second winding sets 164, 166 are the same. Here, there are higher alternating current (AC) losses in the conductors closer to the air gap 126, and lower direct current (DC) losses in the conductors farther from the air gap 126.

[0098] Figure 5A A third embodiment is shown in FIG. Figure 5A , the first plurality of conductors 260 form a first inverter 50 (see Figure 2 ), and the second plurality of conductors 262 form a second winding set 266 coupled to the second inverter 52. The first plurality of conductors 260 and the second plurality of conductors 262 extend along the respective slot axes SA by a first conductor length L1 and a second conductor length L2, respectively. In this embodiment, the first conductor length L1 is less than the second conductor length L2. Here, both the current and the current density are different between the first plurality of conductors and the second plurality of conductors.

[0099] In the embodiment shown in FIG5 , the first plurality of conductors 260 are staggered with the second plurality of conductors 262 along respective slot axes SA. In other words, the first plurality of conductors 260 occupy odd slot layers (the first slot layer S1, the third slot layer S3, and the fifth slot layer S5), while the second plurality of conductors 262 occupy even slot layers (the second slot layer S2, the fourth slot layer S3, and the sixth slot layer S5). This configuration minimizes AC losses in the electric motor 10, thereby allowing lower DC losses in the case of higher current operation.

[0100] refer to Figure 5A , some of the second plurality of conductors 260 may be in the form of a split configuration 270 having two equal conductor segments 272, 274. The split configuration 270 is positioned closer to the air gap 226 and further away from the outer diameter 228 of the stator core 222 than a non-split configuration. The split configuration 270 of the second plurality of conductors may extend in different directions. Figure 5A In one embodiment shown in FIG. 1 , the split structure 270 extends in a radial direction 276 parallel to the slot axis SA. Alternatively, as Figure 5B As shown in FIG. , the split configuration 270 (having two conductor segments 272 , 274 ) may extend in a circumferential direction 278 that is perpendicular to the slot axis SA.

[0101] Although Figure 3-5A A partial cross-sectional view of the stator assembly 12, 112, 212 is shown in FIG. 1 , but it is understood that the first plurality of conductors 60, 160, 260 and the second plurality of conductors 62, 162, 262 extend around the entirety (360 degrees) of the stator core 22, 122, 222, respectively.

[0102] In one embodiment, both the first inverter 50 and the second inverter 52 are three-level inverters. The three-level inverter is adapted to generate three voltage levels at the output: a DC bus positive voltage, a zero voltage, and a DC bus negative voltage. In another embodiment, the first inverter 50 is a two-level inverter and the second inverter 52 is a three-level inverter. The two-level inverter connects the output to either the positive bus or the negative bus. Figure 6, shows an exemplary inverter phase bridge arm or structure of the inverter 300. The inverter 300 is a three-level neutral point clamped (NPC) inverter using clamping diodes (eg, diode D1 and diode D2). Figure 6 The three-level inverter is suitable for generating three voltage levels at the output node using different combinations of four transistors T1, T2, T3 and T4. The three voltage levels include a DC bus positive voltage, a zero voltage and a DC bus negative voltage at the first, second and third nodes N1, N2 and N3, respectively.

[0103] In summary, the controller C is adapted to modulate or control the operation of the first inverter 50 and the second inverter 52 so that when the motor speed is above a predetermined threshold, the first current (i.e., the first plurality of conductors 60, 160, 260 carries relatively more current) is greater than the second current, and when the motor speed is below the predetermined threshold, the second current is greater than the first current (i.e., the second plurality of conductors 62, 162, 262 carries relatively more current). In one example, the second current is approximately 5% higher than the first current. The propulsion system 11 provides reduced motor copper losses at different operating speed regions, resulting in better thermal management and performance under high demand drive cycles.

[0104] Figure 2 The controller C includes a computer-readable medium (also referred to as a processor-readable medium), which includes a non-temporary (e.g., tangible) medium that participates in providing data (e.g., instructions) that can be read by a computer (e.g., by a processor of a computer). Such media can take a variety of forms, including but not limited to non-volatile media and volatile media. For example, non-volatile media may include optical or magnetic disks and other persistent memories. For example, volatile media may include dynamic random access memory (DRAM), which may constitute a main memory. Such instructions may be transmitted via one or more transmission media, including coaxial cables, copper wires, and optical fibers, including wires such as: the wires include a system bus coupled to a processor of a computer. For example, some forms of computer-readable media include floppy disks, floppy disks, hard disks, tapes, other magnetic media, CD-ROMs, DVDs, other optical media, physical media, RAMs, PROMs, EPROMs, FLASH-EEPROMs, other storage chips or cassettes, or other media that can be read by a computer.

[0105] The lookup tables, databases, data repositories, or other data stores described herein may include various mechanisms for storing, accessing, and retrieving various data, including hierarchical databases, a set of files in a file storage system, an application database in a proprietary format, a relational database management system (RDBMS), and the like. Each such data store may be included in a computing device that employs a computer operating system such as one of those mentioned above, and may be accessed via a network in one or more of a variety of ways. The file system may be accessed from the computer operating system, and may include files stored in various formats. In addition to languages ​​for creating, storing, editing, and executing stored programs, such as the PL / SQL language mentioned above, an RDBMS may also employ structured query language (SQL).

[0106] The numerical values ​​of parameters (e.g., quantities or conditions) in this specification, including the attached claims, should be understood as being modified by the term "approximately" in each corresponding instance, regardless of whether "approximately" actually appears before the numerical value. "Approximately" means that the numerical value allows some slight imprecision (approximate the accuracy of the numerical value by some method; approximately or reasonably close to the numerical value; almost). If the imprecision provided by "approximately" is not understood in this ordinary sense in the art, "approximately" as used herein at least represents the changes that may arise from the ordinary methods of measuring and using these parameters. In addition, the disclosure of the range includes the disclosure of each value and the range further divided within the entire range. Each value within the range and the endpoints of the range are disclosed as separate embodiments herein.

[0107] The detailed description and the figures or drawings are support and description of the present disclosure, but the scope of the present disclosure is limited only by the claims. Although some best modes and other embodiments for implementing the claimed disclosure have been described in detail, there are various alternative designs and embodiments for practicing the disclosure defined in the appended claims. In addition, the embodiments shown in the drawings, or the features of the various embodiments mentioned in this specification are not necessarily to be understood as embodiments independent of each other. On the contrary, it is possible that each feature described in an example of an embodiment may be combined with one or more other desired features from other embodiments, resulting in other embodiments that are not described in words or with reference to the drawings. Therefore, such other embodiments fall within the framework of the scope of the appended claims.

Claims

1. A propulsion system comprising: an electric motor having a stator assembly with a plurality of stator slots defining slot layers along respective slot axes; a first plurality of conductors positioned at least partially in the plurality of stator slots, the first plurality of conductors forming a first winding set; a second plurality of conductors positioned at least partially in the plurality of stator slots, the second plurality of conductors forming a second winding set; a first inverter adapted to drive the electric motor, the first winding set being coupled to the first inverter; a second inverter adapted to drive the electric motor, the second winding set being coupled to the second inverter; as well as A controller having a processor and tangible, non-transitory memory having instructions recorded thereon, the controller being adapted to control operation of the first inverter and the second inverter based in part on a motor speed of the electric motor.

2. The propulsion system according to claim 1, wherein: Both the first inverter and the second inverter are three-level inverters.

3. The propulsion system according to claim 1, wherein: The first inverter is adapted to carry a first current, the second inverter is adapted to carry a second current, and operations of the first inverter and the second inverter are controlled such that: When the motor speed is higher than a predetermined threshold, the first current is greater than the second current; as well as When the motor speed is lower than the predetermined threshold, the second current is greater than the first current.

4. The propulsion system according to claim 3, wherein: The second current is approximately 5% higher than the first current.

5. The propulsion system according to claim 1, wherein: Each of the first plurality of conductors is radially inward along the corresponding slot axis relative to each of the second plurality of conductors such that the first plurality of conductors are closer to an air gap of the stator assembly.

6. The propulsion system of claim 1, wherein: The first plurality of conductors extend a first conductor length along the respective slot axis and the second plurality of conductors extend a second conductor length along the slot axis, the first conductor length being less than the second conductor length.

7. The propulsion system of claim 1, wherein: The first plurality of conductors and the second plurality of conductors define equal conductor lengths.

8. The propulsion system of claim 1, wherein: The first plurality of conductors are staggered with the second plurality of conductors along the respective slot axes; the first plurality of conductors extending a first conductor length along the respective slot axis, and the second plurality of conductors extending a second conductor length along the slot axis, the first conductor length being less than the second conductor length; as well as At least one of the second plurality of conductors incorporates a split configuration having two equal conductor segments.

9. The propulsion system of claim 8, wherein: The split structures extend in a radial direction parallel to the corresponding slot axis.

10. The propulsion system of claim 8, wherein: The split structures extend in a circumferential direction perpendicular to the respective slot axes.

Images