Doubly-fed induction machine for series hybrid applications

Abstract

A hybrid powertrain for a vehicle includes a doubly-fed induction machine, a first inverter, and a second inverter. A doubly-fed induction machine includes a stator having a plurality of stator windings and a rotor. The rotor includes a plurality of rotor windings and a plurality of slip rings electrically connected to the plurality of rotor windings. The first inverter is arranged to provide a first multi-phase power to the plurality of stator windings and the second inverter is arranged to provide a second multi-phase power to the plurality of rotor windings through the plurality of slip rings. In an example embodiment, a second multi-phase power is provided to a plurality of slip rings through a plurality of brushes. In example embodiments, the number of slip rings is exactly three.

Description

[0001] Cross-reference to related applications This application claims priority to U.S. Patent Application No. 18 / 374,286, filed September 28, 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] This disclosure generally relates to induction motors, and more specifically to doubly-fed induction motors for series hybrid power applications. Background Technology

[0003] Doubly fed asynchronous motors are known. An example is found in the Siemens Aktiengesellschaft titled "DOPPELT GESPEISTE ASYNCHRONMASCHINE MIT EINEM SCHLEIFRING". The European patent application No. EP 3 771 075 A1, for a "Doubly Fed Asynchronous Motor with a Slip Ring Rotor" (UFER), is shown and described herein by reference as if fully set forth herein. Summary of the Invention

[0004] The example implementation broadly includes a hybrid powertrain for a vehicle, comprising a doubly-fed induction motor, a first inverter, and a second inverter. The doubly-fed induction motor includes a stator and a rotor, the stator having multiple stator windings. The rotor includes multiple rotor windings and multiple slip rings electrically connected to the multiple rotor windings. The first inverter is arranged to provide a first multiphase power to the multiple stator windings, and the second inverter is arranged to provide a second multiphase power to the multiple rotor windings via the multiple slip rings. In the example implementation, the second multiphase power is provided to the multiple slip rings via multiple brushes. In the example implementation, the number of slip rings is exactly three.

[0005] In some example embodiments, the doubly-fed induction motor has a first maximum rated power, and the second inverter has a second maximum rated power, which is 25% to 35% of the first maximum rated power. In some example embodiments, the hybrid powertrain also includes a generator. The generator has a third maximum rated power, and the third maximum rated power is equal to or greater than the first maximum rated power. In some example embodiments, the hybrid powertrain also includes a generator arranged to be drivenly connected to an internal combustion engine, and the generator is selectively electrically connected to a plurality of stator windings and the first inverter. In some example embodiments, the generator is arranged to provide a third multiphase power to the stator windings and the first inverter, and the first multiphase power, the second multiphase power, and the third multiphase power all have the same number of phases.

[0006] In some example embodiments, the hybrid powertrain also includes a battery electrically connected to the first and second inverters. In one example embodiment, the battery is arranged to provide a first DC power to the first and second inverters.

[0007] Other examples broadly include hybrid powertrains for vehicles, comprising an internal combustion engine, a doubly-fed induction motor, a first inverter, a second inverter, a generator, a battery, and at least one drive wheel. The doubly-fed induction motor includes a stator and a rotor, the stator having multiple stator windings. The rotor includes multiple rotor windings and multiple slip rings electrically connected to the multiple rotor windings. The first inverter is arranged to provide a first multiphase power to the multiple stator windings, and the second inverter is arranged to provide a second multiphase power to the multiple rotor windings via multiple brushes in contact with the multiple slip rings. The generator is drivably connected to the internal combustion engine and arranged to provide a third multiphase power to the stator windings and the first inverter, and the battery is arranged to provide a first DC power to the first and second inverters. At least one drive wheel is drivably connected to the rotor.

[0008] This disclosure also provides a method for operating a hybrid powertrain in a first electric mode, wherein a first inverter is arranged to provide a second DC power to a second inverter. The method includes: driving a generator using an internal combustion engine; providing a third multiphase power from the generator to a given rotor winding and the first inverter; providing the second DC power from the first inverter to the second inverter; providing the second multiphase power from the second inverter to a rotor winding to adjust the electrical slip of the doubly-fed induction motor to be greater than zero; and driving at least one drive wheel using the rotor.

[0009] This disclosure also provides a method for operating a hybrid powertrain in a second electric mode, the method comprising: driving a generator using an internal combustion engine; providing a third multiphase power from the generator to a given sub-winding; providing a first DC power from a battery to a first inverter and a second inverter; providing the first multiphase power from the first inverter to the given sub-winding; providing a second multiphase power from the second inverter to a rotor winding such that the electrical slip of the doubly-fed induction motor is adjusted to less than zero; and driving at least one drive wheel using the rotor.

[0010] This disclosure also provides a method for operating a hybrid powertrain in a regeneration mode, wherein the stator is arranged to provide a fourth multiphase power to a first inverter, and the first inverter is arranged to provide a second DC power to a battery. The method includes: driving a rotor using at least one drive wheel; providing the fourth multiphase power from the stator to the first inverter; providing the second DC power from the first inverter to the battery and the second inverter; and providing the second multiphase power from the second inverter to the rotor windings such that the electrical slip regulation of the doubly-fed induction motor is greater than zero.

[0011] This disclosure also provides a method for operating a hybrid powertrain in an electric drive mode, the method comprising: providing first DC power from a battery to a first inverter and a second inverter; providing first multiphase power from the first inverter to a stator winding; providing second multiphase power from the second inverter to a rotor winding to adjust the electrical slip of a doubly-fed induction motor to less than zero; and driving at least one drive wheel using the rotor. In an example embodiment, the method further comprises electrically disconnecting a generator from the stator winding and the first inverter. In an example embodiment, the method further comprises providing fifth multiphase power from the first inverter to the generator to rotate the generator and start an internal combustion engine.

[0012] This disclosure also provides a method for operating a hybrid powertrain to start an internal combustion engine, the method comprising: providing first DC power from a battery to a first inverter; and providing fifth multiphase power from the first inverter to a generator to cause the generator to rotate and start the internal combustion engine. In an example embodiment, a second inverter does not provide second multiphase power to the rotor windings. Attached Figure Description

[0013] Figure 1 The illustration shows a perspective view of a prior art doubly-fed induction motor, in which a portion of the housing has been removed for clarity.

[0014] Figure 2 A schematic diagram of a hybrid powertrain according to an example embodiment is shown.

[0015] Figure 3A This is a schematic diagram showing the entry and exit of power into and from the rotor and stator during subsynchronous power generation mode.

[0016] Figure 3B This is a schematic diagram of power entering and leaving the rotor and stator during supersynchronous power generation mode.

[0017] Figure 3C This is a schematic diagram showing the entry and exit of power into and from the rotor and stator during the secondary synchronous electric mode.

[0018] Figure 3DThis is a schematic diagram of power entering and leaving the rotor and stator during supersynchronous electric mode.

[0019] Figure 4A The diagram illustrates the operation of a hybrid powertrain in subsynchronous hybrid electric mode without battery power.

[0020] Figure 4B The diagram illustrates the operation of a hybrid powertrain in supersynchronous hybrid electric mode without battery power.

[0021] Figure 5A The diagram illustrates the operation of a hybrid powertrain in subsynchronous hybrid electric mode with battery power.

[0022] Figure 5B The diagram illustrates the operation of a hybrid powertrain in supersynchronous hybrid electric mode with battery power.

[0023] Figure 6A The illustration shows a schematic diagram of the operation of a hybrid powertrain in subsynchronous regeneration mode (e.g., during vehicle coasting).

[0024] Figure 6B The illustration shows a schematic diagram of the operation of a hybrid powertrain in supersynchronous regeneration mode (e.g., during vehicle coasting).

[0025] Figure 7A The diagram illustrates the operation of a hybrid powertrain in subsynchronous electric drive mode.

[0026] Figure 7B The diagram illustrates the operation of a hybrid powertrain in supersynchronous electric drive mode.

[0027] Figure 8 The diagram illustrates the operation of a hybrid powertrain in internal combustion engine start mode when the vehicle is stationary. Detailed Implementation

[0028] Embodiments of this disclosure are described herein. It should be understood that similar reference numerals appearing in different drawing views indicate the same or functionally similar structural elements. Furthermore, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various forms and alternative forms. The drawings are not necessarily drawn to scale; some features may be exaggerated or minimized to show detail of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but rather as a representative basis for teaching those skilled in the art to adopt embodiments in various ways. As will be understood by those skilled in the art, various features illustrated and described with reference to any of the figures in this disclosure may be combined with features illustrated in one or more other figures to produce embodiments not explicitly illustrated or described. The combinations of illustrated features provide representative embodiments for typical applications. However, for a particular application or implementation, various combinations and modifications of features consistent with the teachings of this disclosure may be desired.

[0029] The terminology used herein is for descriptive purposes only and is not intended to limit the scope of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Although any methods, apparatus, or materials similar to or equivalent to those described herein may be used in practice or testing of this disclosure, the following example methods, apparatus, and materials will now be described.

[0030] Reference Figure 1 Please describe it as follows. Figure 1 A perspective view of a prior art doubly-fed induction motor 100 is shown, wherein a portion of the housing 102 is removed for clarity. The doubly-fed induction motor 100 includes: a stator 104 having stator windings 106, fixed within the housing 102; and a rotor 108 having rotor windings 110. The rotor 108 also includes a sliding ring 112 electrically connected to the rotor windings. The sliding ring can be separated from the rotor windings by a partition 114. Brushes 116 are stationary in rotation within the housing 102 and transmit electrical power to the sliding ring 112, as described in more detail below. The rotor 108 also includes a rotor shaft 118. The shaft 118 can be sealed with a partition and rotatably supported within the housing by bearings (not shown).

[0031] Reference Figures 1 to 2 Please describe it as follows. Figure 2This is a schematic diagram of a hybrid powertrain 200 according to an exemplary embodiment. The hybrid powertrain 200 includes a doubly-fed induction motor 100 and inverters 202 and 204. Inverter 202 is arranged (e.g., via multiphase conductor 206) to supply multiphase power to the stator windings, and inverter 204 is arranged (e.g., via multiphase conductor 208) to supply multiphase power to the rotor windings via a slip ring 112. Multiphase means that power is supplied with independent alternating currents at the same voltage, wherein each phase is uniformly distributed within one cycle. As an example, for three-phase power, all three conductors carry power at the same voltage and frequency, but each power phase is offset by one-third of the cycle (i.e., 120°). Therefore, when one phase is at its maximum positive current, the other two phases are at a negative current. The conductor refers to copper or aluminum wire, busbars, or other known conductors or combinations thereof.

[0032] It should be noted that inverters 202 and 204 can operate in both directions. For example, a common use of inverters is to convert 12V DC to 120V AC to power a laptop or television from a vehicle battery. In contrast, converters are typically used to convert 120V AC to 12V DC to charge a vehicle battery at home or to power recreational vehicle lights and 12V appliances from a campground power outlet. However, here, inverters 202 and 204 can be used to convert DC (e.g., from a battery) to AC (e.g., to power an induction motor), and they can also be used to convert AC (e.g., from a generator) to DC (e.g., to charge a battery). It should also be noted that although inverters 202 and 204 are shown as separate components, they can be integrated into a single unit.

[0033] Multiphase power is supplied to the slip rings 112 via brushes (e.g., brush 118 described above). In the example shown, there are exactly three slip rings 112 (one slip ring for each phase of the three-phase power). Although the example shown uses three-phase power, other types of multiphase power are possible. For example, an implementation (not shown) could have six slip rings and power could be supplied in all six phases. In this case, each inverter would be connected to the corresponding component via, for example, six conductors.

[0034] The hybrid powertrain 200 also includes a generator 210 arranged for a drive-connected (e.g., mechanically connected) connection to an internal combustion engine 212. Specifically, the generator includes a generator shaft 214 coupled to the internal combustion engine, such that as the shaft rotates via the internal combustion engine (as indicated by the rotation arrow 216), the generator produces multiphase power. The generator 210 can be similar to, for example, a conventional induction motor operating in reverse (e.g., generator mode), and is designed to have the same number of phases as the doubly-fed induction motor 100. The generator 210 can also be a permanent magnet device. The generator 210 is selectively electrically connected, for example, via multiphase conductors 218 and circuit breakers or disconnectors 220 to the stator windings 106 and the inverter 202, and is arranged to provide multiphase power to the stator windings and the inverter 202. All multiphase power from the inverters 202 and 204, as well as the generator 210, has the same number of phases.

[0035] In the illustrated arrangement, the doubly-fed induction motor 100 has a maximum rated power, and the inverter 204 has a maximum rated power that is only 25% to 35% of the maximum rated power of the doubly-fed induction motor 100. The inverter 202 has a continuous rated power equal to or slightly greater than the maximum rated power of the inverter 204 to continuously supply DC power to the inverter 204. The generator 210 has a maximum rated power equal to or greater than the maximum rated power of the doubly-fed induction motor. The inverter 202 has a maximum rated power selected to meet or exceed the regenerated power from the generator 210. The inverter 202 has a lower continuous rated power, and the inverter 204 has a lower maximum rated power, due to the operating method described below. This provides the hybrid powertrain 200 with efficiency in terms of size, cost, and necessary cooling.

[0036] The hybrid powertrain 200 also includes a battery 222, which is electrically connected to inverters 202 and 204 via a DC conductor 224. The battery 222 is arranged to provide DC power to inverters 202 and 204. Unlike alternating current (AC), DC requires only two conductors, a positive conductor and a negative conductor, and the current flows in only one direction.

[0037] In an example embodiment, the hybrid powertrain 200 includes: an internal combustion engine 212; a doubly-fed induction motor 100 having a stator 104 and a rotor 108, the stator including stator windings 106 and the rotor including rotor windings 110 and a slip ring 112 electrically connected to the rotor windings; an inverter 202 arranged to provide multiphase power to the stator windings; an inverter 204 arranged to provide multiphase power to the rotor windings via the slip ring; a generator 210 drivably connected to the internal combustion engine and arranged to provide multiphase power to the stator windings and the inverter 202; a battery 222 arranged to provide DC power to the inverters 202 and 204; and a drive wheel 226 drivably connected to the rotor (e.g., via rotor shaft 118). For example, the hybrid powertrain 200 can be used in a series hybrid vehicle, wherein the doubly-fed induction motor 100 is mounted in an electric axle (not shown).

[0038] During electric or electrical generation, the acceleration in a steady state is defined by the following equation: Where J is the rotor's moment of inertia, dw / dt is the change of the rotor's angular velocity with time, and T... m It is the shaft torque, and T s This refers to the stator (electromagnetic) torque. Electrical slip is defined by the following equation: Where s is the electrical slip, ω r It is the rotor speed, and ω s It is the speed of excitation.

[0039] During power generation mode, rotor power is defined by the following equation: Among them, P r It is the rotor power, P m Shaft power, and P s This refers to stator power. The remaining terms are defined above. Subsynchronous mode is defined as having a slip greater than zero (e.g., the rotor rotates slower than the excitation), and supersynchronous mode is defined as having a slip less than zero (e.g., the rotor rotates faster than the excitation). Similarly, during motoring mode, rotor power is defined by the following equation: All terms have been defined above. A summary of the discussion above is provided in the table below: Reference Figures 3A to 3B Please describe it as follows. Figure 3AThis is a schematic diagram illustrating the entry and exit of power into and from the rotor and stator during subsynchronous power generation mode. Figure 3B This is a schematic diagram illustrating the entry and exit of power into and from the rotor and stator during supersynchronous power generation. Further details regarding the power generation mode will be discussed below. Figure 3A As can be seen, during subsynchronous power generation, shaft power (e.g., from axle 118 discussed above) is available at the rotor, and rotor electrical power (e.g., from inverter 204 discussed above) is supplied to rotor winding 110, and the sum of shaft power and rotor electrical power is recovered from stator winding 106. However, during supersynchronous power generation ( Figure 3B At the rotor, only shaft power is available. Power is supplied by the rotor windings (via inverter 204 discussed above), and the difference between shaft power and rotor electrical power is restored. Therefore, when the doubly-fed induction motor operates in supersynchronous mode, more regenerated power is generated.

[0040] Reference Figures 3C to 3D Please describe it as follows. Figure 3C This is a schematic diagram showing the entry and exit of power into and out of the rotor and stator during the subsynchronous electric mode. Figure 3D This is a schematic diagram illustrating the entry and exit of power into and from the rotor and stator during supersynchronous electric mode. (As shown in...) Figure 3C As can be seen, during subsynchronous motoring, the stator power available at the stator and rotor windings 110 is supplied as output power (e.g., to the inverter 204 discussed above), and the difference between the stator power and the rotor power is available as motor power at the shaft (e.g., to the drive axle 118 discussed above). However, during supersynchronous motoring ( Figure 3D The stator power is available at stator winding 106, and the rotor power is supplied to rotor winding 110. The sum of the stator power and rotor power is available at the shaft for motoring. Therefore, when the doubly-fed induction motor operates in subsynchronous mode, less input power is required for motoring.

[0041] The method of operating the hybrid powertrain 200 will now be discussed with reference to Figures 4 through 9. Figures 4A to 4B Please describe it as follows. Figure 4A The diagram illustrates the operation of the hybrid powertrain 200 in subsynchronous hybrid electric mode without battery power. Figure 4B The diagram illustrates the operation of the hybrid powertrain 200 in supersynchronous hybrid electric mode without battery power. Figure 4AIn the illustrated configuration, the generator is driven by an internal combustion engine (as indicated by rotating arrow 216), and multiphase power from the generator is supplied to a given sub-winding (as indicated by dashed arrow 300). Multiphase power from rotor winding 106 (dashed arrow 302) is converted to DC power by inverter 204 (solid arrow 400), and this multiphase power is supplied to given sub-winding 110 as multiphase power from inverter 202 (dashed arrow 304). Drive wheel 226 is driven by rotor 108. Although only one drive wheel 226 is shown, multiple drive wheels connected to the rotor via the vehicle's electric axle or other drivetrain are also possible.

[0042] exist Figure 4B In the illustrated configuration, the generator is driven by an internal combustion engine (as indicated by rotating arrow 216), and multiphase power from the generator is supplied to the rotor windings and inverter 202 (as indicated by dashed arrows 300 and 306, respectively). DC power from inverter 202 is supplied to inverter 204 (as indicated by solid arrow 402), and multiphase power from inverter 204 is supplied to the rotor windings (as indicated by dashed arrow 308) to adjust the electrical slip of the doubly-fed induction motor to less than zero (i.e., supersynchronous). Drive wheel 226 is driven by rotor 108. The typical value of the electrical slip is about 5%, with very short periods of slip reaching up to 30% during transient events.

[0043] Electrical slip refers to the difference between the rotor's rotational speed and the rotational speed at which the magnetic field in the stator is energized. In the example above, the generator operates at a speed proportional to (or exactly at) the speed of the internal combustion engine and supplies alternating current to the stator windings proportional to that frequency. If the internal combustion engine accelerates or decelerates, the magnetic field in the stator will also accelerate or decelerate because the magnetic field is controlled by the alternating current supplied by the generator. Similarly, the magnetic field in the rotor is controlled by the alternating current supplied by inverter 204. Since the inverter is an electrical component and not mechanically driven, inverter 204 can regulate the alternating current supplied to the rotor, thereby controlling the speed of the magnetic field (equal to the slip speed) and the direction of power in the rotor windings.

[0044] When the electrical slip is greater than zero, the excitation speed is greater than the rotor speed, and the doubly-fed induction motor generates an electric torque T. m .

[0045] Reference Figure 5A and Figure 5B Please describe it as follows. Figure 5A The diagram illustrates the operation of the hybrid powertrain 200 in a subsynchronous hybrid electric mode with battery power. Figure 5BThe diagram illustrates the operation of the hybrid powertrain 200 in supersynchronous hybrid electric mode with battery power. Figure 5A In the illustrated configuration, the generator is driven by an internal combustion engine (as indicated by rotating arrow 216), and multiphase power from the generator is supplied to a given rotor winding (as indicated by dashed arrow 300). Multiphase power from the rotor winding is supplied to inverter 202 (as indicated by solid arrow 302), which provides DC power to battery 222 (as indicated by solid arrow 404). Drive wheel 226 is driven by rotor 108.

[0046] exist Figure 5B In the illustrated configuration, the generator is driven by an internal combustion engine (as indicated by rotating arrow 216), and multiphase power from the generator is supplied to the given sub-winding (as indicated by dashed arrow 300). DC power from the battery is supplied to inverter 204 (as indicated by solid arrow 406). Multiphase power from inverter 204 is supplied to the rotor winding (as indicated by dashed arrow 308) to reduce the electrical slip regulation of the doubly-fed induction motor to less than zero. Drive wheel 226 is driven by rotor 108.

[0047] Reference Figure 6A and Figure 6B Please describe it as follows. Figure 6A The illustration shows a schematic diagram of the operation of the hybrid powertrain 200 in a subsynchronous regeneration mode (e.g., during vehicle coasting). Figure 6B The illustration shows a schematic diagram of the operation of the hybrid powertrain 200 in supersynchronous regeneration mode (e.g., during vehicle coasting). Figure 6A In the illustrated configuration, rotor 108 is driven by drive wheel 226 (as indicated by rotating arrow 228). Stator winding 106 is arranged to supply multiphase power to inverter 202 (as indicated by dashed arrow 310), and inverter 202 is arranged to supply DC power to battery 222 (as indicated by solid arrow 408). Battery 222 supplies DC power to inverter 204 (as indicated by solid arrow 406), and multiphase power is supplied from inverter 204 to rotor winding (as indicated by arrow 308) to make the electrical slip regulation of the doubly-fed induction motor greater than zero.

[0048] exist Figure 6BIn the illustrated configuration, rotor 108 is driven by drive wheel 226 (as indicated by rotating arrow 228). Stator winding 106 is arranged to provide multiphase power to inverter 202 (as indicated by dashed arrow 310), and inverter 202 is arranged to provide DC power to battery 222 (as indicated by solid arrow 408). Multiphase power is supplied from rotor winding to inverter 204 (as indicated by dashed arrow 302), and DC power is supplied from inverter 204 to battery 222 (as indicated by solid arrow 404).

[0049] During the regeneration mode, the electrical slip s and the flow through the air gap P 间隙 The power is less than zero, and the generator power P g The power is zero because the internal combustion engine is not running and the generator is not rotating. Therefore, without considering the losses in the doubly-fed induction motor (e.g., copper losses), the power in inverter 204 is equal to the rotor excitation power P. r And the power in inverter 202 is equal to the rotor excitation power P. r and through the air gap P 间隙 The power output is controlled by the generator. When the engine is not running, the disconnect connector 220 is opened during regeneration mode to prevent multiphase power from being used to operate the generator 210.

[0050] Reference Figures 7A to 7B Please describe it as follows. Figure 7A The diagram illustrates the operation of the hybrid powertrain 200 in subsynchronous electric drive mode. Figure 7B The illustration shows a schematic diagram of the hybrid powertrain 200 operating in super-synchronous electric drive mode. The electric drive mode is similar to that described above and... Figure 5A and Figure 5B The diagram illustrates operation in hybrid electric mode with battery power available. However, in this mode, only the battery supplies power to propel the vehicle. In this mode, the generator can be electrically disconnected from the stator windings and inverter 202 by opening circuit breaker 220. Figure 7A In the illustrated configuration, DC power is supplied from the battery to inverter 202 (as indicated by solid arrow 410). Multiphase power is supplied from inverter 202 to the given sub-winding (as indicated by dashed arrow 304), and multiphase power is supplied from the rotor winding to inverter 204 (as indicated by dashed arrow 302). DC power is supplied from inverter 204 to the battery (as indicated by solid arrow 406). Drive wheel 226 is driven by rotor 108.

[0051] exist Figure 7BIn the illustrated configuration, DC power is supplied from the battery to inverters 202 and 204 (as indicated by solid arrows 410 and 406, respectively). Multiphase power is supplied from inverter 202 to the given sub-winding (as indicated by dashed arrow 304), and multiphase power is supplied from inverter 204 to the rotor winding (as indicated by dashed arrow 308) to reduce the electrical slip regulation of the doubly-fed induction motor to less than zero. Drive wheel 226 is driven by rotor 108.

[0052] During operation in any of the above-described electric drive modes, the internal combustion engine can be started by closing the circuit breaker 220 and supplying multiphase power from the inverter 202 to the generator (as indicated by the dashed arrow 312), causing the generator to rotate and start the internal combustion engine.

[0053] Reference Figure 8 Please describe it as follows. Figure 8 The diagram illustrates the operation of the hybrid powertrain 200 in internal combustion engine start mode when the vehicle is stationary. Figure 8 In the mode shown, DC power is supplied from battery 222 to inverter 202 (as indicated by solid arrow 410), and multiphase power is supplied from inverter 202 to generator 210 (as indicated by dashed arrow 312) to rotate the generator (as indicated by arrow 216) and start internal combustion engine 212. In this mode, inverter 204 does not supply multiphase power to the rotor windings.

[0054] While exemplary embodiments have been described above, it is not intended that these embodiments describe all possible forms covered by the claims. The language used in this specification is descriptive rather than restrictive, and it should be understood that various modifications may be made without departing from the spirit and scope of this disclosure. As previously described, features of various embodiments may be combined to form other embodiments that may not be explicitly described or illustrated in this disclosure. Although various embodiments may have been described as providing an advantage or superiority over other embodiments or prior art implementations in one or more desired characteristics, it will be recognized by those skilled in the art that one or more features or characteristics may be compromised to achieve desired overall system properties, depending on the specific application and implementation. These properties may include, but are not limited to, cost, strength, durability, life cycle cost, merchantability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, etc. Therefore, any embodiment described as less desirable in one or more characteristics than other embodiments or prior art implementations does not exceed the scope of this disclosure and may be desirable for a particular application.

[0055] List of reference numerals 100 doubly fed induction motor 102 housing 104 stator 106 stator winding 108 rotor 110 rotor winding 112 Sliding Ring 114 partition 116 brush 118 rotor shaft 200 Hybrid Powertrain 202 Inverter (First) 204 Inverter (Second) 206 Multiphase Conductor 208 Multiphase Conductors 210 generator 212 internal combustion engine 214 generator shaft 216 Rotating Arrow 218 Multiphase Conductor 220 circuit breaker (connector disconnected) 222 battery 224 DC conductor 226 drive wheels 300-phase power arrows (from generator to stator winding) 302 Multiphase power arrow (rotor winding to inverter 204) 304 Multiphase power arrow (inverter 202 to stator winding) 306 Multiphase power arrow (generator to inverter 202) 308 Multiphase power arrow (inverter 204 to rotor winding) 310 Multiphase Power Arrow (Stator Winding to Inverter 202) 312 Multiphase Power Arrow (Inverter 202 to Generator) 400 DC power arrow (inverter 204 to inverter 202) 402 DC power arrow (inverter 202 to inverter 204) 404 DC power arrow (inverter 204 to battery) 406 DC power arrow (battery to inverter 204) 408 DC power arrow (inverter 202 to battery) 410 DC power arrow (battery to inverter 202)

Claims

1. A hybrid powertrain for a vehicle, the hybrid powertrain comprising: Doubly fed induction motor, the doubly fed induction motor comprising: Stator, the stator comprising a plurality of stator windings; and Rotor, the rotor comprising: Multiple rotor windings; and Multiple sliding rings, the multiple sliding rings being electrically connected to the multiple rotor windings; A first inverter, the first inverter being arranged to provide a first multiphase power to the plurality of stator windings; and The second inverter provides second multiphase power to the plurality of rotor windings through the plurality of sliding rings.

2. The hybrid powertrain according to claim 1, wherein, The second multiphase power is supplied to the multiple sliding rings through multiple brushes.

3. The hybrid powertrain according to claim 1, wherein, The number of the plurality of sliding rings is exactly three.

4. The hybrid powertrain according to claim 1, wherein: The doubly-fed induction motor includes a first maximum rated power; and The second inverter includes a second maximum rated power, which is 25% to 35% of the first maximum rated power.

5. The hybrid powertrain according to claim 4 further includes a generator, wherein: The generator includes a third maximum rated power; and The third maximum rated power is equal to or greater than the first maximum rated power.

6. The hybrid powertrain of claim 1 further includes a generator, the generator being arranged to be drivably connected to the internal combustion engine, wherein, The generator is selectively electrically connected to the plurality of stator windings and the first inverter.

7. The hybrid powertrain according to claim 6, wherein: The generator is arranged to provide a third multiphase power to the stator windings and the first inverter; and The first multiphase power, the second multiphase power, and the third multiphase power all have the same number of phases.

8. The hybrid powertrain according to claim 1 further includes a battery electrically connected to the first inverter and the second inverter.

9. The hybrid powertrain according to claim 8, wherein, The battery is arranged to provide a first DC power to the first inverter and the second inverter.

10. A hybrid powertrain for a vehicle, the hybrid powertrain comprising: Internal combustion engine; Doubly fed induction motor, the doubly fed induction motor comprising: Stator, the stator comprising a plurality of stator windings; and Rotor, the rotor comprising: Multiple rotor windings; and Multiple sliding rings, the multiple sliding rings being electrically connected to the multiple rotor windings; A first inverter, the first inverter being arranged to provide a first multiphase power to the plurality of stator windings; The second inverter provides second multiphase power to the plurality of rotor windings through a plurality of brushes in contact with the plurality of sliding rings; A generator, which is drivenly connected to the internal combustion engine and arranged to provide a third multiphase power to the stator windings and the first inverter; A battery, the battery being arranged to provide a first DC power to the first inverter and the second inverter; and At least one drive wheel is drivably connected to the rotor.

11. A method for operating the hybrid powertrain according to claim 10 in a first electric mode, wherein, The first inverter is arranged to provide a second DC power to the second inverter, the method comprising: The generator is driven by the internal combustion engine. The third multiphase power from the generator is provided to the stator winding and the first inverter; The second DC power from the first inverter is supplied to the second inverter; The second multiphase power from the second inverter is supplied to the rotor windings to make the electrical slip regulation of the doubly-fed induction motor greater than zero; and The rotor drives the at least one drive wheel.

12. A method for operating a hybrid powertrain according to claim 10 in a second electric mode, the method comprising: The generator is driven by the internal combustion engine. The third multiphase power from the generator is supplied to the stator winding; The first DC power from the battery is provided to the first inverter and the second inverter; The first multiphase power from the first inverter is provided to the stator winding; The second multiphase power from the second inverter is supplied to the rotor winding so that the electrical slip of the doubly fed induction motor is less than zero; as well as The rotor drives the at least one drive wheel.

13. A method for operating a hybrid powertrain according to claim 10 in a regeneration mode, wherein: The stator is arranged to provide a fourth multiphase power to the first inverter; and The first inverter is arranged to provide a second DC power to the battery, the method comprising: The rotor is driven by the at least one drive wheel; The fourth multiphase power from the stator is provided to the first inverter; The second DC power from the first inverter is supplied to the battery and the second inverter; and The second multiphase power from the second inverter is supplied to the rotor winding so that the electrical slip of the doubly fed induction motor is greater than zero.

14. A method for operating a hybrid powertrain according to claim 10 in an electric drive mode, the method comprising: The first DC power from the battery is provided to the first inverter and the second inverter; The first multiphase power from the first inverter is provided to the stator winding; The second multiphase power from the second inverter is supplied to the rotor winding so that the electrical slip of the doubly fed induction motor is less than zero; as well as The rotor drives the at least one drive wheel.

15. The method of claim 14, further comprising electrically disconnecting the generator from the stator winding and the first inverter.

16. The method of claim 14, further comprising providing a fifth multiphase power from the first inverter to the generator to cause the generator to rotate and start the internal combustion engine.

17. A method of operating a hybrid powertrain according to claim 10 to start the internal combustion engine, the method comprising: The first DC power from the battery is supplied to the first inverter; as well as The fifth multiphase power from the first inverter is supplied to the generator to cause the generator to rotate and start the internal combustion engine.

18. The method according to claim 17, wherein, The second inverter does not provide the second multiphase power to the rotor winding.

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