Electric drive system with electric machine having stationary rotor power transfer

Abstract

An electric drive system with an electric machine having stationary rotor power transfer. An electric drive system includes an electric machine having a stator assembly and a rotor assembly. The stator assembly has a plurality of multi-phase stator windings, including a first stator winding and a second stator winding. The first inverter is adapted to feed power to the first stator winding. The second inverter is adapted to feed power to the second stator winding. The electrical machine is a wound rotor machine in which a respective frequency of alternating current (AC) in the rotor assembly is synchronized with a respective frequency of AC in the stator assembly. The rotor assembly includes a multi-phase rotor winding. The electrical machine is configured such that power transfer between the first stator winding and the second stator winding is effected when the rotor assembly is stationary.

Description

[0001] introduce

[0002] The present disclosure generally relates to an electric drive system having an electric machine. More specifically, the present disclosure generally relates to an electric drive system having power transfer occurring between stator windings when the rotor is stationary. The electric machine generally includes a stator having a plurality of stator windings and a rotor rotatable within the stator. In the generator mode, the rotation of the rotor induces a voltage in the stator windings, which powers an external load. Alternatively, if current passes through the stator windings, the energized windings cause the rotor to rotate, and the machine will perform as a motor. In a synchronous electric machine, the stator magnetic field and the rotor magnetic field are locked together and rotate at the same speed. The power transfer topology of the electric machine generally uses DC excitation on the rotor, which can be achieved, for example, using permanent magnets or single-phase field windings. Maintaining synchronization between the rotor and stator fields requires the rotor to spin during power transfer. In addition, during power transfer, a mechanical clutch is required to decouple the electric machine from the axle. Summary of the invention

[0003] An electric drive system is disclosed herein, which has an electric machine with a stator assembly and a rotor assembly. The stator assembly has a plurality of multi-phase stator windings, including a first stator winding and a second stator winding. A first inverter is suitable for feeding power to the first stator winding. A second inverter is suitable for feeding power to the second stator winding. The rotor assembly includes a multi-phase rotor winding, wherein a corresponding frequency of an alternating current (AC) in the rotor assembly is synchronized with a corresponding frequency of an AC in the stator assembly. The electric machine is configured so that power transfer between the first stator winding and the second stator winding is achieved when the rotor assembly is stationary.

[0004] In one embodiment, the rotor assembly includes exactly two multi-phase rotor windings, including a first phase coil and a second phase coil. Here, the first phase coil and the second phase coil define respective currents that form a combined rotating AC current vector, wherein the respective currents of the first phase coil and the second phase coil are separated by 90 electrical degrees. In another embodiment, the multi-phase rotor winding has exactly three phases, including a first phase coil, a second phase coil, and a third phase coil. The first phase coil, the second phase coil, and the third phase coil may define respective currents that form a combined rotating AC current vector, wherein the respective currents of the first phase coil, the second phase coil, and the third phase coil are separated by 120 electrical degrees.

[0005] The electric drive system may include a controller having a processor and a tangible non-transitory memory having instructions recorded thereon. The first and second phase coils are arranged relative to a plurality of circuit legs, each circuit leg having a corresponding first switch and a corresponding second switch. The controller is adapted to modulate the phase and amplitude of the combined rotating current vector by controlling the corresponding states of the corresponding first switch and the corresponding second switch.

[0006] A vehicle battery may be selectively electrically coupled to the first stator winding, wherein during a propulsion mode of the vehicle, the battery provides power to the first stator winding. An external energy source may be selectively electrically coupled to the second stator winding, the external energy source comprising at least one of a vehicle-to-load connection, a vehicle-to-premises connection, and a vehicle-to-grid connection. During a charging mode of the vehicle, the second stator winding is adapted to consume energy from the external energy source, power transfer occurs from the second stator winding to the first stator winding, and the first stator winding is adapted to provide power to the vehicle battery.

[0007] In some embodiments, the electric drive system may include a power source that can be selectively coupled to the electric machine, the power source being suitable for transmitting a direct current (DC) signal. The power converter may be suitable for receiving a DC signal. Here, a high-frequency rotary transformer may be electrically coupled to the power converter, the high-frequency rotary transformer having a stationary portion and a rotating portion, so that an alternating current (AC) in the stationary portion induces an AC voltage in the rotating portion. The rectifier is suitable for receiving an AC voltage from the rotating portion of the high-frequency rotary transformer, the rectifier being suitable for converting the AC voltage into a DC voltage. The DC bus may be suitable for storing a DC voltage from the rectifier.

[0008] The electric drive system may include a two-phase inverter adapted to receive a DC voltage from a DC bus, wherein the DC voltage is converted into a corresponding AC current in the two-phase inverter. Here, the multi-phase rotor winding includes a first phase coil and a second phase coil, wherein the first phase coil and the second phase coil are adapted to receive a corresponding AC current from the two-phase inverter to generate a rotor field.

[0009] The electric drive system may include a three-phase inverter adapted to receive a DC voltage from a DC bus, the DC voltage being converted into a corresponding AC current in the three-phase inverter. The multi-phase rotor winding includes first, second and third phase coils adapted to receive corresponding AC currents from the three-phase inverter to generate a rotor field.

[0010] A power source may be selectively coupled to the electric machine, the power source being adapted to transmit a DC signal. In one embodiment, a first DC to AC inverter and a second DC to AC inverter are adapted to receive the DC signal to convert into a corresponding AC current. A first slip ring device and a second slip ring device may be adapted to receive a corresponding AC current from the first DC to AC inverter and the second DC to AC inverter, the electric machine having a stationary side and a rotating side. The first slip ring device and the second slip ring device are positioned so that the corresponding AC current flows from the stationary side to the rotating side, and the multi-phase rotor winding is adapted to receive the corresponding AC current to generate a rotor field.

[0011] In another embodiment, the first DC to AC inverter and the second DC to AC inverter are adapted to receive a DC signal to convert into a corresponding AC signal. A rotary transformer having a corresponding double node is adapted to receive the corresponding AC signal from the first DC to AC inverter and the second DC to AC inverter. The rotary transformer is adapted to transmit the corresponding AC signal to the multi-phase rotor winding.

[0012] A vehicle having an electric drive system is disclosed herein, the electric drive system having an electric machine having a stator assembly and a rotor assembly. The stator assembly has a plurality of multi-phase stator windings, including a first stator winding and a second stator winding. A first inverter is adapted to feed power to the first stator winding; and a second inverter is adapted to feed power to the second stator winding. The rotor assembly includes a multi-phase rotor winding, and a corresponding frequency of an alternating current (AC) in the rotor assembly is synchronized with a corresponding frequency of an AC in the stator assembly. The electric machine is configured so that power transfer between the first stator winding and the second stator winding is achieved when the rotor assembly is stationary.

[0013] An electric drive system for a vehicle is disclosed, comprising: an electric machine having a stator assembly and a rotor assembly, the stator assembly having a plurality of multi-phase stator windings, including a first stator winding and a second stator winding; a first inverter adapted to feed power to the first stator winding; a second inverter adapted to feed power to the second stator winding; wherein the rotor assembly comprises a multi-phase rotor winding, a corresponding frequency of an alternating current (AC) in the rotor assembly is synchronized with a corresponding frequency of the AC in the stator assembly; and wherein the electric machine is configured to enable power transfer between the first stator winding and the second stator winding when the rotor assembly is stationary.

[0014] Wherein: the multi-phase rotor winding has exactly two phases, which has a first phase coil and a second phase coil; and the first phase coil and the second phase coil define corresponding currents forming a combined rotating AC current vector, and the corresponding currents of the first phase coil and the second phase coil are separated by 90 electrical degrees.

[0015] Further comprising: a controller having a processor and a tangible non-transitory memory having instructions recorded thereon; and wherein the first and second phase coils are arranged relative to a plurality of circuit branches, each circuit branch having a corresponding first switch and a corresponding second switch; the controller is adapted to modulate the phase and amplitude of the combined rotating current vector by controlling the corresponding states of the corresponding first switch and the corresponding second switch.

[0016] Wherein: the multi-phase rotor winding has exactly three phases, which has a first phase coil, a second phase coil and a third phase coil; and the first phase coil, the second phase coil and the third phase coil define corresponding currents that form a combined rotating AC current vector, and the corresponding currents of the first phase coil, the second phase coil and the third phase coil are separated by 120 electrical degrees.

[0017] further comprising: a vehicle battery selectively electrically coupled to the first stator winding, the battery providing power to the first stator winding during a propulsion mode of the vehicle; an external energy source selectively electrically coupled to the second stator winding, the external energy source comprising at least one of a vehicle-to-load connection, a vehicle-to-premises connection, and a vehicle-to-grid connection; and

[0018] Wherein during a charging mode of the vehicle, the second stator winding is adapted to consume energy from an external energy source, power transfer occurs from the second stator winding to the first stator winding, and the first stator winding is adapted to provide power to a vehicle battery.

[0019] Further includes: a power supply, which can be selectively coupled to the electric machine, the power supply is suitable for transmitting a direct current (DC) signal; a power converter, which is suitable for receiving a DC signal; a high-frequency rotary transformer, which is electrically coupled to the power converter, the high-frequency rotary transformer has a stationary part and a rotating part, so that an alternating current (AC) in the stationary part induces an AC voltage in the rotating part; a rectifier, which is suitable for receiving an AC voltage from the rotating part of the high-frequency rotary transformer, the rectifier is suitable for converting the AC voltage into a DC voltage; and a DC bus, which is suitable for storing the DC voltage from the rectifier.

[0020] Further comprising: a two-phase inverter adapted to receive a DC voltage from a DC bus, wherein the DC voltage is converted into a corresponding AC current in the two-phase inverter; and wherein the multi-phase rotor winding comprises a first phase coil and a second phase coil, wherein the first phase coil and the second phase coil are adapted to receive a corresponding AC current from the two-phase inverter to generate a rotor field.

[0021] Further comprising: a three-phase inverter adapted to receive a DC voltage from a DC bus, the DC voltage being converted into a corresponding AC current in the three-phase inverter; and wherein the multi-phase rotor winding comprises first, second and third phase coils, the first, second and third phase coils being adapted to receive corresponding AC currents from the three-phase inverter to generate a rotor field.

[0022] Further comprising: a power source selectively coupled to the electric machine, the power source being adapted to transmit a DC signal; a first DC to AC inverter and a second DC to AC inverter being adapted to receive the DC signal for conversion into a corresponding AC current; a first slip ring device and a second slip ring device being adapted to receive the corresponding AC current from the first DC to AC inverter and the second DC to AC inverter, the electric machine having a stationary side and a rotating side; and wherein the first slip ring device and the second slip ring device are positioned such that the corresponding AC current flows from the stationary side to the rotating side, and the multi-phase rotor winding is adapted to receive the corresponding AC current to generate a rotor field.

[0023] Further comprising: a power supply selectively coupleable to the electric machine, the power supply being adapted to transmit a DC signal; a first DC to AC inverter and a second DC to AC inverter being adapted to receive the DC signal to convert into a corresponding AC signal; and a rotary transformer having corresponding dual nodes, being adapted to receive the corresponding AC signal from the first DC to AC inverter and the second DC to AC inverter, the rotary transformer being adapted to transmit the corresponding AC signal to the multi-phase rotor winding.

[0024] A vehicle is disclosed, comprising: an electric drive system having an electric machine, the electric machine having a stator assembly and a rotor assembly, the stator assembly having a plurality of multi-phase stator windings, including a first stator winding and a second stator winding; a first inverter adapted to feed power to the first stator winding; a second inverter adapted to feed power to the second stator winding; wherein the rotor assembly comprises a multi-phase rotor winding, a corresponding frequency of an alternating current (AC) in the rotor assembly is synchronized with a corresponding frequency of the AC in the stator assembly; and wherein the electric machine is configured to enable power transfer between the first stator winding and the second stator winding when the rotor assembly is stationary.

[0025] Wherein: the multi-phase rotor winding includes a first-phase coil and a second-phase coil, and the corresponding currents of the first-phase coil and the second-phase coil are 90 electrical degrees apart.

[0026] Further comprising: a controller having a processor and a tangible non-transitory memory having instructions recorded thereon; and wherein the first phase coil and the second phase coil are arranged relative to a plurality of circuit branches, each circuit branch having a corresponding first switch and a corresponding second switch; the controller is adapted to modulate the phase and amplitude of the combined rotating current vector by controlling the corresponding states of the corresponding first switch and the corresponding second switch.

[0027] Further includes: a power supply, which can be selectively coupled to the electric machine, the power supply is suitable for transmitting a direct current (DC) signal; a power converter, which is suitable for receiving a DC signal; a high-frequency rotary transformer, which is electrically coupled to the power converter, and the high-frequency rotary transformer has a stationary part and a rotating part, so that an alternating current (AC) in the stationary part induces an AC voltage in the rotating part; a rectifier, which is suitable for receiving an AC voltage from the rotating part of the high-frequency rotary transformer, and the rectifier is suitable for converting the AC voltage into a DC voltage; and a DC bus, which is suitable for storing the DC voltage from the rectifier.

[0028] Further comprising: a two-phase inverter adapted to receive a DC voltage from a DC bus, wherein the DC voltage is converted into a corresponding AC current in the two-phase inverter; and wherein the multi-phase rotor winding comprises a first phase coil and a second phase coil, wherein the first phase coil and the second phase coil are adapted to receive a corresponding AC current from the two-phase inverter to generate a rotor field.

[0029] Further comprising: a three-phase inverter adapted to receive a DC voltage from a DC bus, the DC voltage being converted into a corresponding AC current in the three-phase inverter; and wherein the multi-phase rotor winding comprises first, second and third phase coils, the first, second and third phase coils being adapted to receive corresponding AC currents from the three-phase inverter to generate a rotor field.

[0030] Further comprising: a power supply selectively coupleable to the electric machine, the power supply being adapted to transmit a DC signal; a first DC to AC inverter and a second DC to AC inverter being adapted to receive the DC signal to convert into a corresponding AC signal; and a rotary transformer having corresponding dual nodes, being adapted to receive the corresponding AC signal from the first DC to AC inverter and the second DC to AC inverter, the rotary transformer being adapted to transmit the corresponding AC signal to the multi-phase rotor winding.

[0031] An electric drive system for a vehicle is disclosed, comprising: an electric machine having a stator assembly and a rotor assembly, the stator assembly having a plurality of multi-phase stator windings, including a first stator winding and a second stator winding; a first inverter, adapted to feed power to the first stator winding; a second inverter, adapted to feed power to the second stator winding; a power source, selectively coupled to the electric machine, the power source being adapted to transmit a direct current (DC) signal; a power converter, adapted to receive a DC signal; a rotating transformer, electrically coupled to the power converter, the rotating transformer having a stationary portion and a rotating portion, such that an alternating current (AC) in the stationary portion induces an AC voltage in the rotating portion; a vehicle battery, selectively electrically coupled to the first stator winding, and an external energy source, selectively electrically coupled to the second stator winding; wherein the rotor assembly comprises a multi-phase rotor winding, the corresponding frequency of the alternating current (AC) in the rotor assembly being synchronized with the corresponding frequency of the AC in the stator assembly; and wherein the electric machine is configured to enable power transfer between the first stator winding and the second stator winding when the rotor assembly is stationary.

[0032] wherein: during a charging mode of the vehicle, the second stator winding is adapted to consume energy from an external energy source, power transfer occurs from the second stator winding to the first stator winding, and the first stator winding is adapted to provide power to a vehicle battery; and the external energy source comprises at least one of a vehicle-to-load connection, a vehicle-to-house connection, and a vehicle-to-grid connection.

[0033] Further comprising: a power supply selectively coupled to the electric machine, the power supply being adapted to transmit a direct current (DC) signal, the electric machine having a stationary side and a rotating side; a plurality of inverters being adapted to receive the DC signal to convert into a corresponding alternating current (AC); a first slip ring device and a second slip ring device being adapted to receive a corresponding AC current from the plurality of inverters; and wherein the first slip ring device and the second slip ring device are positioned such that the corresponding AC current flows from the stationary side to the rotating side, and the multi-phase rotor winding is adapted to receive the corresponding AC current to generate a rotor field.

[0034] 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

[0035] Figure 1 is a schematic fragmentary block diagram of an electric drive system having an electric machine and a plurality of inverters;

[0036] Figure 2 is through Figure 1 A schematic fragmentary cross-sectional view of an electric machine;

[0037] Figure 3 is available in Figure 1 A schematic, incomplete diagram of an example two-phase rotor winding employed in an electric machine of;

[0038] Figure 4 is available in Figure 1 A schematic, incomplete diagram of an example three-phase rotor winding employed in an electric machine of;

[0039] Figure 5 According to the first embodiment Figure 1 A schematic incomplete diagram of the electric drive system;

[0040] Figure 6 According to the second embodiment Figure 1 A schematic incomplete diagram of the electric drive system;

[0041] Figure 7 According to the third embodiment Figure 1 A schematic incomplete diagram of an electric drive system; and

[0042] Figure 8 According to the fourth embodiment Figure 1 Schematic incomplete diagram of the electric drive system.

[0043] Representative embodiments of the present disclosure are shown in the accompanying drawings by way of non-limiting examples and are described below in additional detail. However, it should be understood that the novel aspects of the present disclosure are not limited to the specific forms illustrated in the above-listed drawings. Rather, the present disclosure will cover modifications, equivalents, combinations, sub-combinations, permutations, groupings, and substitutions that fall within the scope of the present disclosure as, for example, encompassed by the appended claims. DETAILED DESCRIPTION

[0044] Referring to the drawings, wherein like reference numerals refer to like parts, Figure 1 1 is a schematic, incomplete diagram of an electric drive system 10 that may be part of a vehicle 12. The vehicle 12 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 transportation vehicle, a bicycle, a robot, an agricultural implement, sports-related equipment, a boat, an airplane, a train, or other equipment. The vehicle 12 may be partially electric or fully electric. The vehicle 12 may take many different forms and include multiple and / or alternative components and facilities.

[0045] The electric drive system 10 includes an electric motor / generator, referred to herein as an electric machine 14, which is configured to generate torque, and a plurality of electric power converters 15. Figure 1, the electric machine 14 includes a stator assembly 16 positioned at least partially around a rotor assembly 18 having a rotor shaft 20. The electric machine 14 is a wound rotor machine.

[0046] Figure 2 is a schematic fragmentary cross-sectional view through the electric machine 14. Figure 2 , the stator assembly 16 is separated from the rotor assembly 18 by an air gap G. Figure 2 The stator assembly 16 has corresponding conductors 22 extending through stator slots 24 and arranged in a set of windings. The stator assembly 16 has a plurality of multi-phase stator windings, including a first stator winding 26 and a second stator winding 28. Figure 1-2 In other words, the stator assembly 16 has two windings, and each winding has three phases.

[0047] See also Figure 2 , the rotor assembly 18 includes corresponding conductors 30 extending through the rotor slots 32. The rotor assembly 18 has a winding having multiple phases (e.g., 2 phases, 3 phases, etc.), referred to herein as a multi-phase rotor winding 34. In some embodiments, the multi-phase rotor winding 34 includes exactly two phases, having a first phase coil R1 and a second phase coil R2, Figure 3 The multi-phase rotor winding 34 may include exactly three phases, which include a first phase coil R1, a second phase coil R2 and a third phase coil R3. Figure 4 as shown in .

[0048] Motor-based power transfer strategies using synchronous electric machines typically require rotor rotation in order to synchronize the rotor field with the stator field. During power transfer, a mechanical clutch is required to decouple the electric machine from the shaft of the vehicle. As described below, the electric drive system 10 enables power transfer without the need for rotor rotation in order to synchronize the rotor field with the stator field. In addition, the electric drive system 10 eliminates the need for a mechanical clutch. The electric machine 14 is able to use current in the rotor windings (arranged around the rotor shaft 20) instead of permanent magnets for rotor flux control.

[0049] Various embodiments of the electric drive system 10 are described in Figure 3-8 shown in and referenced below Figure 3-818. The electric drive system 10 is configured to generate a rotating rotor magnetic field vector and synchronize it with the stator magnetic field, allowing alternating current ("AC") power to be transferred between the two segmented stator windings without rotating the rotor assembly 18.

[0050] refer to Figure 1-2 , the stator assembly 16 has two sets of segmented multi-phase windings, each of which is fed by a separate inverter for independent current control. Figure 1 , the first stator winding 26 and the second stator winding 28 are fed by the first inverter 40 and the second inverter 42, respectively. During stationary power transfer, the first stator winding 26 and the second stator winding 28 can be electrically coupled to the vehicle battery 44 and the external energy source 46 (or the grid 46), respectively. During the propulsion mode, the vehicle battery 44 provides power to the first stator winding 26. During the charging mode, the first stator winding 26 (on the battery side) provides power to the battery 44. During the charging mode, the second stator winding 28 (on the grid side) consumes power from the grid 46; power is drawn from the grid-side stator winding ( Figure 1 The second stator winding 28 in the battery side is transferred to the stator winding ( Figure 1 The external energy source 46 may be a vehicle-to-load connection (V2L), a vehicle-to-house connection (V2H), or a vehicle-to-grid (V2G) connection. Figure 1 , the torque generated by the electric drive system 10 is subsequently transmitted to the wheels 48 of the vehicle 12 .

[0051] Figure 3 is a schematic diagram of an example arrangement of a rotor winding 34 having exactly two phases, with first and second phase coils R1, R2. The first and second phase coils R1, R2 are arranged relative to a plurality of circuit branches connected between a positive node 50 and a negative node 52. Figure 3 In the embodiment shown in FIG. 5 , the circuit branches include a first branch 54 , a second branch 56 , and a third branch 58 , each branch having a respective first switch S1 , S3 , S5 and a respective second switch S2 , S4 , S6 .

[0052] The electric drive system 10 may employ a two-phase or multi-phase inverter to generate a rotating current vector and magnetic field without rotating the rotor assembly 18. During power transfer, the multi-phase rotor winding 34 is excited with an alternating current ("AC"). The respective currents of the first phase coil R1 and the second phase coil R2 are separated by 90 electrical degrees, thereby forming a combined rotating current vector.

[0053] The first and second phase coils R1, R2 generate a combined rotating current vector having a phase and amplitude that can be modulated by controlling the states of the corresponding first switches S1, S3, S5 and the corresponding second switches S2, S4, S6. In other words, a subset of the three-phase space state vector is used to modulate the amplitude and phase of the winding voltage and generate a rotating rotor magnetic field. The frequency of the AC rotor current is synchronized with the frequency of the AC stator current. In this way, the electric machine 14 maintains synchronization between the stator field and the rotor field for power transfer without having to rotate the rotor assembly 18.

[0054] refer to Figure 1 , the vehicle 12 includes a controller C having a processor P and a tangible non-transitory memory M having recorded thereon instructions for controlling the operation of the electric drive system 10 based on torque demand. The controller C can be suitable for modulating the corresponding states (ON / OFF) of switches S1 to S6. This setting enables four different configurations (I, II, III, IV), as shown in Table I below. Each corresponding branch can be in one of two states, one of which is a first state or a zero state. "State 0" indicates that the corresponding first switch (S1, S3, S5) is in an off state and the corresponding second switch (S2, S4, S6) is in an on state. "State 1" indicates that the corresponding top switch (S1, S3, S5) is in an on state and the corresponding bottom switch (S2, S4, S6) is in an off state. The first voltage (V1) and the second voltage (V2) in Table 1 indicate the input voltages of the first and second phase coils R1 and R2, respectively, where the maximum input voltage is represented by Vdc.

[0055] Table 1

[0056] Configuration Status of branch 54 Status of branch 56 Status of branch 58 V1 V2 I 1 0 0 Vdc 0 II 1 1 0 0 Vdc III 0 1 1 -Vdc 0 IV 0 0 1 0 -Vdc

[0057] Figure 4 Another example configuration is shown in FIG. 1 , in which the rotor winding 34 has exactly three phases, which have first, second and third phase coils R1, R2, R3. The first, second and third phase coils R1, R2, R3 are connected to respective circuit branches arranged between a positive node 60 and a negative node 62. The circuit branches include a first branch 64, a second branch 66 and a third branch 68. Figure 4 , each branch has a corresponding first switch 70 and a corresponding second switch 72. The first, second and third phase coils R1, R2, R3 are selected to be spaced 120 electrical degrees apart from each other. The first, second and third phase coils R1, R2, R3 generate a combined rotating current vector having a phase and amplitude that can be modulated by controlling the states of the corresponding first and second switches 70, 72. Similar to Figure 3 In the example shown in FIG. 1 , the controller C is adapted to modulate the states (on / off) of the respective first and second switches 70 , 72 of the first branch 64 , the second branch 66 , and the third branch 68 .

[0058] The number of turns of the multi-phase rotor winding 34 can be selected so that the winding impedance is sufficiently high enough to maintain a relatively low DC or AC current during the propulsion mode of the vehicle 12. The number of turns of the multi-phase rotor winding can also be appropriately selected so that the back-electromotive force of the multi-phase rotor winding 34 is below a predefined voltage limit at a desired frequency during power transfer or propulsion. The electric drive system 10 can be controlled so that the torque fluctuation during stationary power transfer is below a predefined threshold to improve the life of other components such as the gear unit 36. For example, the predefined threshold can be set to between about 1 and 2 Nm (Newton meters).

[0059] Reference now Figure 5 , shows an electric drive system 110 according to a first embodiment. The electric drive system 110 includes an electric machine 114 having a stator assembly 116, and a rotor assembly 118 having a rotor shaft 120. The electric drive system 110 has a rotating side 122 and a stationary side 124 separated by an air gap G.

[0060] refer to Figure 5 , a power source 126 (e.g., a high voltage battery) can be selectively coupled to the electric drive system 110 and is suitable for transmitting a direct current (DC) signal to a power converter, such as a DC to AC inverter 130. The DC to AC inverter 130 converts the DC signal into an AC signal for transmission to a stationary portion 132 of a rotary transformer T. The rotary transformer T is suitable for coupling electrical signals between two parts that rotate relative to each other and can be a high-frequency rotary transformer. In one embodiment, the high-frequency rotary transformer has an operating frequency of more than about 10 kilohertz. The AC excitation in the stationary portion 132 induces a voltage in the rotating portion 134 of the rotary transformer T, which is connected to a rectifier 136. The rectifier 136 converts the AC voltage and establishes a DC voltage in the DC bus 138.

[0061] refer to Figure 5 The DC voltage from the DC bus 138 is converted into AC current by the first and second inverters 140, 142 and supplied to the first and second phase coils 144, 146, resulting in the generation of a rotor field. The rotor field interacts with the stator field in the first and second stator windings 148, 150. Figure 5The first and second stator windings 148, 150 are fed by first and second inverters 152, 154, which are powered by an energy source 156. The interaction of the rotor field with the stator field results in the generation of torque, which is subsequently transmitted to the wheels 48 of the vehicle 12. Figure 5 The example shown in combines a single wireless power transfer across the air gap G.

[0062] Reference now Figure 6 , shows an electric drive system 210 according to a second embodiment. The electric drive system 210 includes an electric machine 214 having a stator assembly 216, and a rotor assembly 218 having a rotor shaft 220. The electric drive system 210 has a rotating side 222 and a stationary side 224 separated by an air gap G.

[0063] refer to Figure 6 , a power source 226 (e.g., a high voltage battery) is selectively coupled to the electric drive system 210 and is adapted to transmit a DC signal to a first inverter 230 and a second inverter 232, which convert the DC signal into an AC signal, respectively. The AC signal flows from the stationary side 224 to the rotating side 222 through mechanical contact power transfer in the form of slip ring devices 234, 236, which supply the AC signal to the first and second phase coils 244, 246. Slip ring devices 234, 236 are used to transmit power or electrical signals between stationary components and rotating components, and slip ring devices 234, 236 may also be referred to as rotating electrical joints (joints), electrical swivels (swivels), and collector rings (collector rings). Slip ring devices 234, 236 may include one or more rotating rings and stationary brushes. The configuration of slip ring devices 234, 236 may vary based on the application.

[0064] AC excitation in the first and second phase coils 244, 246 results in the generation of a rotor field that interacts with the stator field in the first and second stator windings 248, 250. Figure 6 The first and second stator windings 248, 250 are fed by first and second inverters 252, 254, which are powered by an energy source 256. The interaction of the rotor field with the stator field results in the generation of torque, which is subsequently transmitted to the wheels 48 of the vehicle 12.

[0065] Reference now Figure 7 , shows an electric drive system 310 according to a third embodiment. The electric drive system 310 includes an electric machine 314 having a stator assembly 316, and a rotor assembly 318 having a rotor shaft 320. The electric drive system 310 has a rotating side 322 and a stationary side 324 separated by an air gap G.

[0066] refer to Figure 7 , a power source 326 (e.g., a high voltage battery) can be selectively coupled to the electric drive system 310 and is suitable for transmitting a DC signal to a first DC to AC inverter 330 and a second DC to AC inverter 332, the first DC to AC inverter 330 and the second DC to AC inverter 332 converting the DC signal into an AC signal for transmission to the stationary double node 334 of the rotary transformer T, respectively. The rotary transformer T can use low-frequency AC excitation. The AC excitation in the stationary double node 334 induces an AC voltage in the rotating double node 336 of the rotary transformer T, which is supplied to the first and second phase coils 344, 346, thereby resulting in the generation of a rotor field. Therefore, the electric drive system 310 combines dual wireless power transmission across the air gap G.

[0067] The rotor field interacts with the stator field in the first and second stator windings 348, 350. Figure 7 The first and second stator windings 344, 346 are fed by first and second inverters 352, 354, which are powered by an energy source 356. The interaction of the rotor field with the stator field results in the generation of torque, which is subsequently transmitted to the wheels 48 of the vehicle 12.

[0068] Reference now Figure 8 , shows an electric drive system 410 according to a fourth embodiment. In addition to the presence of a three-phase rotor winding set 444, Figure 8 The fourth embodiment is similar to Figure 5 The first embodiment of the present invention. Figure 4 An example configuration of a three-phase rotor winding set is shown in FIG. Figure 8 , the electric drive system 410 includes a wound-field electric machine having a stator assembly 416, and a rotor assembly 418 having a rotor shaft 420. The electric drive system 410 has a rotating assembly 422 and a stationary side 424 separated by an air gap G.

[0069] refer to Figure 8, a power source 426 (e.g., a high voltage battery) may be selectively coupled to the electric drive system 410 and is adapted to transmit a DC signal to a DC to AC inverter 430, which converts the DC signal into an AC signal for transmission to a stationary portion 432 of a rotary transformer T. The rotary transformer T is adapted to couple electrical signals between two portions that rotate relative to each other and may be a high frequency rotary transformer. The AC excitation in the stationary portion 432 induces a voltage in a rotating portion 434 of the rotary transformer T, which is connected to a rectifier 436. The rectifier 436 converts the AC voltage and establishes a DC voltage in a DC bus 438.

[0070] refer to Figure 8 The DC voltage from the DC bus 438 is converted into AC current by the three-phase inverter 440 and supplied to the three-phase rotor winding set 444, thereby generating a rotor field. The three-phase rotor winding set 444 includes first, second and third phase coils R1, R2, R3 ( Figure 4 ). The rotor field interacts with the stator field in the first and second stator windings 448, 450. The first and second stator windings 448, 450 are fed by first and second inverters 452, 454, which are powered by an energy source 456. The interaction of the rotor field with the stator field results in the generation of torque.

[0071] In summary, various embodiments of an electric drive system 10 having an electric machine 14 are disclosed. The electric drive system 10 enables bidirectional AC power transfer to and from a vehicle 12 when the rotor assembly 18 is stationary. The electric drive system 10 can be configured to employ a high fundamental frequency for stationary power transfer in order to increase the back EMF and reduce the current required to achieve high efficiency and high power operation. In some embodiments, before starting power transfer, the rotor assembly 18 can be moved to the middle of the gear tooth gap to minimize the impact on the gear unit 36 ​​in the vehicle 12. For example, the rotor assembly 18 can be positioned within about 15 degrees of the gear tooth gap.

[0072] Figure 1The controller C includes a computer-readable medium (also referred to as a processor-readable medium), including 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. Non-volatile media can include, for example, optical or magnetic disks and other persistent memories. Volatile media can include, for example, dynamic random access memory (DRAM), which can constitute a main memory. Such instructions can be transmitted via one or more transmission media, including coaxial cables, copper wires, and optical fibers, including wires that include a system bus coupled to a processor of a computer. Some forms of computer-readable media include, for example, floppy disks, flexible disks, hard disks, tapes, other magnetic media, CD-ROMs, DVDs, other optical media, physical media, RAMs, PROMs, EPROMs, FLASH-EEPROMs, other memory chips or cassettes, or other media from which a computer can read.

[0073] 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, file collections in file storage systems, application databases in proprietary formats, relational database management systems (RDBMS), etc. Each such data store may be included in a computing device that uses a computer operating system such as one of those mentioned above and may be accessed via a network in a variety of ways. The file system may be accessible from a computer operating system and may include files stored in various formats. In addition to the language used to create, store, edit and execute stored procedures, RDBMS may also use structured query language (SQL), such as the PL / SQL language mentioned above.

[0074] The numerical values ​​of parameters (e.g., amounts or conditions) in this specification, including the appended claims, are to be understood as being modified by the term "about" in each respective instance, whether or not "about" actually appears before the numerical value. "About" indicates that the numerical value allows some slight imprecision (with a certain proximity to the precision of the value; approximately or reasonably close to the value; almost). If the imprecision provided by "about" is not otherwise understood in the art with this ordinary meaning, then "about" as used herein at least indicates the variation that may be caused by the ordinary methods of measuring and using such parameters. In addition, the disclosure of the range includes the disclosure of each value within the entire range and the further divided range. Each value within the range and the endpoints of the range are thereby disclosed as separate embodiments.

[0075] The detailed description and the accompanying drawings or figures are support and description of the present disclosure, but the scope of the present disclosure is limited only by the claims. Although some of the best modes and other embodiments for carrying out the claimed disclosure have been described in detail, there are various alternative designs and embodiments for implementing 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. Rather, it is possible that each of the features described in one of the examples of the embodiments can be combined with one or more of the other desired features from other embodiments, resulting in other embodiments that are not described in language or by reference to the drawings. Therefore, such other embodiments fall within the framework of the scope of the appended claims.

Claims

1. An electric drive system for a vehicle, comprising: An electric machine having a stator assembly and a rotor assembly, the stator assembly having a plurality of multi-phase stator windings including a first stator winding and a second stator winding; a first inverter adapted to feed power to the first stator winding; a second inverter adapted to feed power to the second stator winding; wherein the rotor assembly includes a multi-phase rotor winding, a respective frequency of an alternating current (AC) in the rotor assembly being synchronized with a respective frequency of the AC in the stator assembly; and The electric machine is configured such that power transfer between the first stator winding and the second stator winding is achieved when the rotor assembly is stationary.

2. The electric drive system according to claim 1, wherein: The multi-phase rotor winding has exactly two phases, which has a first phase coil and a second phase coil; and The first phase coil and the second phase coil define respective currents that form a combined rotating AC current vector, the respective currents of the first phase coil and the second phase coil being 90 electrical degrees apart.

3. The electric drive system according to claim 2, further comprising: a controller having a processor and tangible, non-transitory memory having instructions recorded thereon; and The first and second phase coils are arranged relative to a plurality of circuit branches, each circuit branch having a corresponding first switch and a corresponding second switch; the controller is adapted to modulate the phase and amplitude of the combined rotating current vector by controlling the corresponding states of the corresponding first switch and the corresponding second switch.

4. The electric drive system according to claim 1, wherein: The multi-phase rotor winding has exactly three phases, which has a first phase coil, a second phase coil, and a third phase coil; and The first phase coil, the second phase coil, and the third phase coil define respective currents that form a combined rotating AC current vector, and the respective currents of the first phase coil, the second phase coil, and the third phase coil are separated by 120 electrical degrees.

5. The electric drive system according to claim 1, further comprising: a vehicle battery selectively electrically coupled to the first stator winding, the battery providing power to the first stator winding during a propulsion mode of the vehicle; an external energy source selectively electrically coupled to the second stator winding, the external energy source comprising at least one of a vehicle-to-load connection, a vehicle-to-premises connection, and a vehicle-to-grid connection; and Wherein during a charging mode of the vehicle, the second stator winding is adapted to consume energy from an external energy source, power transfer occurs from the second stator winding to the first stator winding, and the first stator winding is adapted to provide power to a vehicle battery.

6. The electric drive system according to claim 1, further comprising: a power source selectively couplable to the electric machine, the power source being adapted to transmit a direct current (DC) signal; a power converter adapted to receive a DC signal; a high frequency rotary transformer electrically coupled to the power converter, the high frequency rotary transformer having a stationary portion and a rotating portion such that an alternating current (AC) in the stationary portion induces an AC voltage in the rotating portion; a rectifier adapted to receive an AC voltage from a rotating portion of the high frequency rotary transformer, the rectifier adapted to convert the AC voltage into a DC voltage; and A DC bus is adapted to store a DC voltage from the rectifier.

7. The electric drive system according to claim 6, further comprising: a two-phase inverter adapted to receive a DC voltage from a DC bus, the DC voltage being converted into a corresponding AC current in the two-phase inverter; and The multi-phase rotor winding includes a first phase coil and a second phase coil, and the first phase coil and the second phase coil are adapted to receive corresponding AC currents from a two-phase inverter to generate a rotor field.

8. The electric drive system according to claim 6, further comprising: a three-phase inverter adapted to receive a DC voltage from a DC bus, the DC voltage being converted into a corresponding AC current in the three-phase inverter; and The multi-phase rotor winding includes first, second and third phase coils, and the first, second and third phase coils are adapted to receive corresponding AC currents from a three-phase inverter to generate a rotor field.

9. The electric drive system according to claim 1, further comprising: a power source selectively couplable to the electric machine, the power source being adapted to transmit a DC signal; a first DC to AC inverter and a second DC to AC inverter adapted to receive a DC signal to convert into a corresponding AC current; a first slip ring device and a second slip ring device adapted to receive respective AC currents from a first DC to AC inverter and a second DC to AC inverter, the electric machine having a stationary side and a rotating side; and Wherein the first slip ring device and the second slip ring device are positioned such that a corresponding AC current flows from a stationary side to a rotating side, and the multi-phase rotor winding is adapted to receive the corresponding AC current to generate a rotor field.

10. The electric drive system according to claim 1, further comprising: a power source selectively couplable to the electric machine, the power source being adapted to transmit a DC signal; a first DC to AC inverter and a second DC to AC inverter adapted to receive a DC signal to convert into a corresponding AC signal; as well as A rotary transformer having respective dual nodes is adapted to receive respective AC signals from the first DC to AC inverter and the second DC to AC inverter, the rotary transformer being adapted to transmit the respective AC signals to the multi-phase rotor winding.

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