Modular electric motor assembly

An electric motor assembly is disclosed. The electric motor assembly can include a plurality of electric motors coupled to a common gear assembly. Individual motors within the electric motor assembly can be dynamically controlled to increase motor efficiency at a given torque and RPM output.

FIELD

Aspects relate to electric motors and implementations within an axle of an electric vehicle (EV).

BACKGROUND

The move towards clean energy is prompting interest, research, and development in the area of EVs, and specifically, systems used to propel EVs. Electric drive systems that can match or exceed the performance of internal combustion (IC) engines are critical to the success and adoption of EVs. EVs require electric drive systems that are energy efficient and can be produced and repaired in a cost efficient manner. In particular, the efficiency of electric drive systems is crucial for enabling EVs to travel for long distances without the need for the EVs' batteries to be recharged. Electric drive systems can implement electric motor assemblies to supply the torque and rotational frequency needs of EVs. Conventional electric motor assemblies typically consist of a single electric motor driving a gear set.

Conventional electric motor assemblies used in EVs suffer from several shortcomings. First, conventional electric motor assemblies are expensive to produce, implement, and repair. The peak power rating of electric motors used in EVs can exceed 400 kW, depending on the weight and use of the EV. Producing or purchasing electric motors of such size can be expensive. Additionally, electronic components compatible with large motors can be more rare and expensive compared to those compatible with smaller motors, leading to higher costs for implementing the electric motor within an EV. Further, if a component of the motor fails, the entire motor may need to be replaced. Even if the entire motor does not need to be replaced, the size of the motor may require handling by multiple technicians during repair.

Second, conventional electric motor assemblies have upper RPM operational limits based on the centrifugal forces that are applied to the rotor assemblies. The centrifugal force is directly related to the diameter and mass of the rotating assembly. This effectively limits the power-to-weight ratio because power is directly related to the operating RPM (output power=output torque×RPM). The upper operational speed can be increased by employing exotic materials but this comes at a cost.

Third, conventional electric motor assemblies do not have operational redundancy. Failure of the electric motor in a conventional electric motor assembly typically results in the loss of function of the entirety or large portions of the electric drive system, making the system inoperable.

Fourth, conventional electric motor assemblies often suffer from a significant difference between peak and continuous power rating. The power the electric motor can produce continuously is significantly less than the power the electric motor can produce instantaneously, due to overheating of the stator assembly (magnets) when the motor is run at peak power for an extended time.

Fifth, conventional electric motor assemblies are not versatile—the torque and power are locked in to the design. Thus, a conventional electric motor assembly that is built for one EV cannot be easily modified to work with other EVs without significant expense or reconfiguration. Further, a conventional electric motor assembly that is built for a particular use environment cannot be easily modified for optimal use in another environment posing different torque needs without significant expense or reconfiguration.

Sixth, conventional electric motor assemblies are not dynamically configurable (i.e., they cannot be adapted in real-time to be better suited to meet a particular torque demand). The electric motor in a conventional electric motor assembly is typically chosen to meet the maximum torque and power needs of a device (e.g., an EV) implementing the electric motor assembly. However, conventional electric motors operate at varying efficiencies depending on torque and RPM, with efficiency typically declining at torques that are a small percentage of a motor's continuous output torque (i.e., the torque the electric motor is capable of producing indefinitely without causing overheating, given a particular RPM). This is especially true at high RPM. The efficiency of a conventional electric motor assembly implementing a single electric motor will therefore vary significantly depending on the torque and RPM demand placed on the electric motor. Conventional electric motor assemblies do not have a means of configuring the electric motor assembly in real-time to more efficiently provide the torque/power need. Accordingly, EV's implementing conventional electric motor assemblies will run less than peak efficiency at many operating points which results in decreased range for a given battery capacity.

Seventh, conventional drivelines typically include multiple stages of gear reduction between an electric motor and an axle. This can increase the complexity and number of components along the driveline between the electric motor and the axle.

Eighth, conventional permanent magnet electric motor assemblies and control systems often implement field weakening to achieve higher RPMs. For an electric motor assembly implemented in an EV, field weakening can be required at high vehicle speeds. However, field weakening introduces losses and increases heat generation, and can reduce the overall efficiency of a drive system.

Thus, improved electric motor assemblies are needed to overcome one or more of the aforementioned shortcomings and to provide improved and more adaptable electric motor assemblies.

DETAILED DESCRIPTION

Aspects disclosed herein provide a novel electric motor assembly. The electric motor assembly provides a novel construction over conventional electric motor assemblies, as will be described. This construction may provide several benefits.

First, it allows the electric motor assembly to potentially be less expensive to produce, implement, and repair. For example, the use of a plurality of smaller electric motors in place of a single, larger electric motor can allow for less expensive motors to be produced and/or purchased at higher volumes, reducing production and/or purchasing costs. Further, a wider variety of less expensive power electronic components are available for use with smaller electric motors, reducing costs of implementing electric motors within the electric motor assembly/electric drive system. If a motor within the assembly fails, it can be replaced at a cheaper cost. Additionally, the smaller size of the motors allows a single technician to handle and repair the motor assembly.

Second, the electric motor assembly can have higher power-to-weight ratios, due to the smaller size of the electric motors implemented within the electric motor assembly (see discussion above regarding operating RPM). The smaller diameters of the motor rotors used in the electric motor assembly can enable the electric motors to operate at higher RPM and generate more power for a given amount of magnetics (materials/mass) compared to a larger motor, while having approximately the same torque-to-weight ratio as the larger motor. Accordingly, a plurality of smaller motors can collectively provide the same power output as a single, larger motor while potentially weighing less than the larger motor.

Third, the electric motor assembly can have operational redundancy. Failure of a single electric motor of a plurality of electric motors does not necessarily result in the loss of function of the entire electric motor assembly, since the remaining electric motors of the plurality of electric motors can continue to operate. Thus, the operability of the electric drive system can be maintained through a motor failure.

Fourth, the difference between the peak and continuous power rating of the electric motor assembly can be smaller than for a conventional electric motor assembly. Given the same output power, a plurality of smaller electric motors produces less heat buildup than a single, larger electric motor. This is at least because the plurality of electric motors has a larger surface area, allowing for quicker dissipation of heat into surrounding materials (e.g., a housing, air, etc.).

Fifth, the electric motor assembly can be versatile. The use of a plurality of smaller electric motors in place of a single, larger electric motor can provide a single component that can be used in multiple EVs or types of EVs. For example, one or more of the plurality of electric motors can be removed based on the torque needs of the type of EV (e.g., an electric motorcycle can implement an electric motor assembly with fewer motors installed than an electric truck). Further, one or more of the plurality of electric motors can be removed based on the torque needs associated with a use environment (e.g., an electric car that operates primarily in a mountainous area can implement an electric motor assembly with more motors installed than an electric car that operates primarily in a flat region). The electric motor assembly can be easily reconfigured depending on the type and/or use environment of an EV since the electric motor assembly is designed to accommodate the attachment, detachment, and omission of individual electric motors.

Sixth, the electric motor assembly can be dynamically configurable (i.e., it can be adapted in real-time to be better suited to meet a particular torque demand). Conventional electric motors operate at varying efficiencies depending on torque and RPM, with efficiency typically declining at torques that are a small percentage of the motor's continuous output torque, particularly at high RPM. Accordingly, in an electric motor assembly in which a plurality of smaller motors replace a single, larger motor, the continuous and peak output torque of the electric motor assembly at a given RPM can be adjusted by selectively activating or deactivating one or more motors. Therefore, the electric motor assembly's output torque as a percentage of the continuous output torque of its activated motors can be dynamically adjusted to ensure that the output torque is achieved at a higher efficiency. Additionally, since smaller motors can produce higher RPM more efficiently, as noted above, the efficiency of the motor assembly at low loads and high RPM can be improved. Operation at low loads and high RPM is an inefficient operating domain for an electric motor assembly implementing a single, large motor.

Seventh, the electric motor assembly can provide for gear reduction as part of the mechanical integration of a plurality of electric motors. For example, an output gear (coupled to an output shaft configured to transmit a torque to an external component) of the electric motor assembly can have more teeth than adjacent gears driven by electric motors. This can cause gear reduction between the adjacent gears and the output gear, eliminating at least one stage of gear reduction on a driveline between the electric motor assembly and an axle. This can reduce the complexity and number of components along the driveline between the electric motor assembly and the axle.

Eighth, because a central electric motor can be at a lower gear ratio relative to peripheral motors, the central electric motor coupled to the output gear need not be in field weakening at high vehicle speeds when the electric motor assembly is implemented in an EV. Instead, as compared to an electric motor of a conventional EV, the electric motor coupled to the output gear can output a lower RPM to achieve the same axle RPMs as the conventional EV. This is because a stage of gear reduction can occur within the electric motor assembly before the output gear rather than along the drivetrain between the electric motor coupled to the output gear and the axle. Accordingly, losses, increased heat generation, and associated reductions in efficiency of a drive system related to field weakening can be avoided. The efficiency and range of an EV can be increased by implementing the electric motor assembly of the present disclosure, particularly at high speeds.

In aspects, an electric motor assembly can include at least: a housing including a plurality of cavities; a gear assembly, the gear assembly including: an output gear coupled to an output shaft, and adjacent gears coupled to the output gear; the electric motor assembly further including: a plurality of electric motors at least partially within the plurality of cavities, the plurality of electric motors including: a first electric motor coupled to the output gear, and adjacent electric motors coupled to the adjacent gears; the electric motor assembly further including: a controller to activate and deactivate one or a pair of motors of the plurality of electric motors.

In aspects, an electric drive system can include at least: an electric motor assembly, the electric motor assembly including: a gear assembly including an output gear and one or more gears coupled to the output gear, the output gear being coupled to an output shaft, and a plurality of electric motors, each of the plurality of electric motors coupled to a gear of the gear assembly; the electric drive system further including: a control system to activate and deactivate one or more motors of the plurality of electric motors; an energy storage system coupled to the electric motor assembly; and a power demand system to communicate a torque need to the control system to activate or deactivate the one or more motors.

In aspects, a method can include at least: installing an electric motor assembly in an electric drive unit, the electric motor assembly including: a housing including a plurality of cavities; a gear assembly, the gear assembly including: an output gear coupled to an output shaft, and adjacent gears coupled to the output gear; the electric motor assembly further including: a plurality of electric motors at least partially within the plurality of cavities, the plurality of electric motors including: a first electric motor coupled to the output gear, and adjacent electric motors coupled to the adjacent gears; the electric motor assembly further including: a controller to activate and deactivate one or a pair of motors of the plurality of electric motors.

In aspects, a vehicle can include at least: an electric motor assembly, the electric motor assembly including: a housing including a plurality of cavities; a gear assembly, the gear assembly including: an output gear coupled to an output shaft, and adjacent gears coupled to the output gear; the electric motor assembly further including: a plurality of electric motors at least partially within the plurality of cavities, the plurality of electric motors including: a first electric motor coupled to the output gear, and adjacent electric motors coupled to the adjacent gears; the electric motor assembly further including: a controller to activate and deactivate one or a pair of motors of the plurality of electric motors.

In aspects, an electric motor assembly can include at least: a housing including a plurality of cavities; a gear assembly including: a sun gear, planetary gears rotatably fixed relative to the housing and coupled to the sun gear, a ring gear comprising gear teeth on both an inner and outer side, the planetary gears enmeshed with the gear teeth on the inner side of the ring gear, and outer adjacent gears enmeshed with the gear teeth on the outer side of the ring gear; the electric motor assembly further including: a plurality of electric motors at least partially within the plurality of cavities, the plurality of electric motors including: a first electric motor coupled to the sun gear, and outer adjacent electric motors coupled to the outer adjacent gears; the electric motor assembly further including: a controller to activate and deactivate one or more motors of the plurality of electric motors.

In aspects, a vehicle can include at least: an electric drive system including: an electric motor assembly including: a gear assembly including a ring gear and a plurality of adjacent gears coupled to the ring gear, the ring gear being coupled to a drive plate to transmit torque to an external component, the plurality of adjacent gears including inner adjacent gears coupled to the ring gear inside a perimeter of the ring gear and one or more outer adjacent gears coupled to the ring gear outside a perimeter of the ring gear, the electric motor assembly further including a plurality of electric motors, each of the plurality of electric motors coupled to a gear of the gear assembly; the electric drive system further including: a control system to activate and deactivate one or more motors of the plurality of electric motors; an energy storage system coupled to the electric motor assembly; and a power demand system to communicate a torque need to the control system to activate or deactivate the one or more motors, wherein the control system is configured to activate and deactivate the one or more motors based on the torque need such that a number of simultaneously activated motors of the plurality of electric motors depends on the torque need.

In aspects, an electric motor assembly can include at least: a housing including a plurality of cavities; a gear assembly including: an output gear coupled to a rotatable output shaft configured to transfer a torque to an external component, and a plurality of adjacent gears coupled to the output gear and to a plurality of rotatable adjacent shafts; the electric motor assembly further including: a plurality of electric motors at least partially within the plurality of cavities, each of the plurality of electric motors coupled to an adjacent gear of the plurality of adjacent gears via a rotatable adjacent shaft of the plurality of rotatable adjacent shafts; a controller to activate and deactivate one or more motors of the plurality of electric motors; and a plurality of clutches to mechanically engage and disengage the plurality of electric motors from the plurality of adjacent gears, each of the plurality of clutches selectively securing an adjacent gear of the plurality of adjacent gears relative to a rotatable adjacent shaft of the plurality of rotatable adjacent shafts.

In aspects, a vehicle can include at least: an electric drive system including: an electric motor assembly including: a gear assembly including an output gear and one or more adjacent gears coupled to the output gear, the output gear being coupled to a rotatable output shaft and the one or more adjacent gears being coupled to one or more rotatable adjacent shafts, the electric motor assembly further including: a plurality of electric motors including: one or more adjacent electric motors, each of the one or more adjacent electric motors coupled to an adjacent gear of the one or more adjacent gears via a rotatable adjacent shaft of the one or more rotatable adjacent shafts, the electric motor assembly further including: one or more clutches to mechanically engage and disengage the one or more adjacent electric motors from the one or more adjacent gears, each of the one or more clutches selectively securing an adjacent gear of the one or more adjacent gears relative to a rotatable adjacent shaft of the one or more rotatable adjacent shafts; the electric drive system further including: a control system to activate and deactivate one or more motors of the plurality of electric motors and to operate the one or more clutches; an energy storage system coupled to the electric motor assembly; and a power demand system to communicate a torque need to the control system to activate or deactivate the one or more motors, the control system being configured to: activate and deactivate the one or more motors based on the torque need such that a number of simultaneously activated motors of the plurality of electric motors depends on the torque need, and mechanically disengage, by operating a clutch of the one or more clutches, a deactivated adjacent electric motor from an adjacent gear in conjunction with the deactivated adjacent electric motor being deactivated.

The following aspects are described in sufficient detail to enable those skilled in the art to make and use the disclosure. It is to be understood that other aspects are evident based on the present disclosure, and that system, process, or mechanical changes may be made without departing from the scope of an aspect of the present disclosure.

In the following description, numerous specific details are given to provide a thorough understanding of the disclosure. However, it will be apparent that the disclosure may be practiced without these specific details. In order to avoid obscuring aspects of the present disclosure, some configurations and process steps are not disclosed in detail.

The drawings showing aspects of the system and its components are semi-diagrammatic, and not to scale. Some of the dimensions are for the clarity of presentation and are shown exaggerated in the drawing figures. Similarly, although the views in the drawings are for case of description and generally show similar orientations, this depiction in the figures is arbitrary for the most part. Generally, the disclosure may be operated in any orientation.

FIG.1shows a vehicle100according to aspects of the disclosure. Vehicle100can be an EV (i.e., vehicle100can be propelled using at least one electric motor). WhileFIG.1shows vehicle100as an electric car, vehicle100can be any electric vehicle, such as a truck, an airplane, a boat, a 4-wheeler, a motorcycle, etc. As shown inFIG.1, vehicle100can include a drive unit102to propel vehicle100, such as first drive unit102aand second drive unit102b. In aspects, first and second drive units102a/bcan be electric axles (eAxles). In aspects in which vehicle100is a car, first drive unit102acan be disposed toward the front of vehicle100and second drive unit102bcan be disposed toward the rear of the vehicle100. In such aspects, vehicle100can also alternatively include a single drive unit102disposed toward either the front or rear of vehicle100, or additional drive units102. In other aspects, vehicle100can include any number of drive units102to propel vehicle100.

Vehicle100can further include energy storage system104to supply power to drive units102. Accordingly, energy storage system104can be coupled to drive units102. In aspects, energy storage system104can include a battery or collection of batteries. In aspects, the battery or collection of batteries can be rechargeable electric vehicle batter (ies).

FIG.2Ashows a drive unit102according to aspects of the disclosure. Drive unit102can be an electric drive unit (i.e., drive unit102can include an electric motor used to provide a torque for a device). More specifically, drive unit102can be an eAxle. As shown inFIG.2A, drive unit102can include a motor assembly202, an example of which is described in more detail with respect toFIGS.3A-3B and8A-8B. Drive unit102can further include a housing204to house the components of drive unit102. Drive unit102can further include a shaft206to output a torque produced by motor assembly202. While not shown inFIG.2A, drive unit102can include at least one inverter to control the operation of motor assembly202by manipulating electric currents provided to motor assembly202. For example, the inverter can convert a current from direct current (DC) to alternating current (AC) and adjust the frequency of the alternating current to control the output speed of motor assembly202.

FIG.2Bshows an exploded view of electric drive unit102according to aspects of the disclosure. As shown inFIG.2B, motor assembly202can be attachable to and detachable from housing204(shown as a first housing204aand a second housing204binFIG.2B). Motor assembly202can be attached to housing204using attachment element208. Attachment element208can be a fixture configured to attach to both motor assembly202and housing204. Motor assembly202can include alignment elements210that can be received by alignment apertures212on attachment element208. Further, motor assembly202can include affixment apertures214to receive bolts or screws used to secure attachment element208to motor assembly202. Attachment element208can then be secured to housing204using similar means.

Drive unit102can further include a gear assembly216to receive and control a torque produced by motor assembly202. Gear assembly216can transfer a torque from motor assembly202to shaft206, altering gear ratios within gear assembly216to control the torque and rotational frequency supplied to shaft206. In aspects, gear assembly216can be a two-speed gear assembly. In other aspects, gear assembly216can be a single speed gear assembly.

WhileFIGS.2A-2Bshow motor assembly202in a drive unit102for use in an EV, motor assembly202can be used in any device requiring the production of a torque. Further, motor assembly202can be interchangeable with a conventional motor assembly (i.e., a conventional motor assembly can be attached to drive unit102in place of motor assembly202). However, unlike conventional motor assemblies, motor assembly202can include multiple motors, as discussed with respect toFIGS.3A-3B.

FIG.3Ashows a motor assembly202according to aspects of the disclosure. As shown inFIG.3A, motor assembly202can include a main housing302, a first end cap304, a layer305, and a second end cap306to house motors within motor assembly. Main housing302, first end cap304, layer305, and second end cap306can collectively form a housing307. First end cap304can include an aperture308allowing an output shaft310to pass therethrough. Output shaft310can transfer a torque to external gear assemblies, such as gear assembly216shown inFIG.2B.

FIG.3Bshows an exploded view of motor assembly202according to aspects of the disclosure. As shown inFIG.3B, motor assembly202can include a drive assembly312to generate a torque. Drive assembly312can include a support plate314to which components of drive assembly312can be attached. For example, a gear assembly316can be attached to support plate314.

Gear assembly316can include gears318.FIG.3Bshows seven gears318a-318g. Gear318aof gear assembly316can be an output gear coupled to output shaft310. Gears318b-318gcan be adjacent gears coupled to gear318a(gears318b-318gare sequentially labeled in a clockwise direction starting with gear318bat the top of gear assembly316). That gears318b-318gare adjacent can mean that gears318b-318gare in a common gear assembly with gear318a. Further, that gears318b-318gare adjacent can include cases in which gears318b-318gare both directly or indirectly coupled to gear318a. In aspects, gears318b-318gcan be directly coupled to gear318a, for example, by each of gears318b-318gbeing in contact and enmeshed with gear318a. In other aspects, at least one of gears318b-318gcan be indirectly coupled to gear318a, for example, by being coupled to gear318awithout being in contact or enmeshed with gear318a. In this sense, that gears are “coupled” to gear318acan mean that rotation of one of gears318b-318gcontributes to rotation of gear318a, either directly or via another gear. To avoid mechanical breakdown, if one of gears318b-318gis directly coupled to gear318a, it cannot be directly coupled to another of gears318b-318gthat is in turn directly coupled to gear318a(e.g., gear318bcannot be directly coupled to gear318cinFIG.3B).

In aspects, gear318acan be a central gear (i.e., arranged between at least two of gears318b-318g). In such aspects, at least two of gears318b-318gcan be peripheral gears arranged around gear318a.

WhileFIG.3Bshows six gears318b-318gcoupled to gear318a, this is exemplary and gear assembly316can include fewer or additional adjacent gears, such as 1, . . . , n adjacent gears, where n is a positive integer. Further, the number of adjacent gears can be an even number. Particularly, the adjacent gears can be pairs of gears, each gear of a pair of gears arranged on opposite sides of gear318a, for example, like gear318band gear318einFIG.3B. The reference to gears318b-318gin this disclosure should be understood to include aspects in which there are fewer or more than six adjacent gears.

Gears318can form any suitable gear ratios for providing the output torques required of motor assembly202. In aspects, gears318b-318gcan each form the same gear ratio with gear318a. For example, in aspects, gears318b-318gcan each form a gear ratio of approximately 1:1 with gear318a. In other aspects, gears318b-318gcan form varying gear ratios with gear318a. In aspects, at least one of gears318b-318gor any adjacent gears318described herein can form a gear ratio of greater than 1 with gear318a(i.e., an adjacent gear has fewer teeth than gear318aand makes more than 1 full turn for every full turn of gear318a) to provide for gear reduction between adjacent gears318and gear318a. In aspects, each of adjacent gears318directly coupled to gear318acan form a gear ratio of greater than 1 with gear318a. In aspects, all adjacent gears318can form a gear ratio of greater than 1 with gear318a.

Drive assembly312can further include motors322, such as motors322a-322g, to rotate gears318a-318g.FIG.3Bshows seven motors322a-322gcorresponding to gears318a-318g. In aspects, motors322can be permanent magnet motors. In aspects, motors322can be induction motors. In aspects, motor322acan be a permanent magnet motor while motors322b-322gcan be induction motors. In aspects, motors322can be AC electric motors. For example, in aspects, motors322can be three-phase induction AC electric motors. In other aspects, motors322can be three-phase synchronous AC electric motors. Motor322acan be coupled to gear318avia output shaft310. Motors322b-322gcan be adjacent motors coupled to gears318b-318gvia shafts320(motors322b-322gare sequentially labeled in a clockwise direction starting with motor322bcorresponding to gear318b). That motors322b-322gare adjacent can mean that motors322b-322gare coupled via shafts320to gears that are in a common gear assembly with gear318a. In aspects, motor322acan be a central motor (i.e., arranged between at least two of motors322b-322g). In such aspects, at least two of motors322b-322gcan be peripheral motors arranged around motor322a. Motors322b-322gcan turn each of gears318b-318gin a direction that contributes to the turning of gear318ain a particular direction. For example, in aspects in which gears318b-318gare each directly coupled to gear318a, motors322b-322gcan turn gears318b-318gin one direction (e.g., clockwise) while motor322acan turn gear318ain the opposite direction (e.g., counterclockwise).

WhileFIG.3Bshows six motors322b-322gcoupled to six gears318b-318gthat are in turn coupled to gear318a, this is exemplary and drive assembly312can include fewer or additional adjacent motors, such as 1, . . . , n adjacent motors, where n is a positive integer. Further, the number of adjacent motors can be an even number. Particularly, the adjacent motors can be pairs of motors, each motor of a pair of motors arranged on opposite sides of motor322a, for example, like motor322dand motor322g. The inclusion of multiple motors322b-322gcan increase operational redundancy of motor assembly202. For example, upon failure of a portion of motors322, operability of motor assembly202can be maintained. The reference to motors322b-322gin this disclosure should be understood to include aspects in which there are fewer or more than six adjacent motors. In aspects, a motor322can be coupled to each of gears318, as shown inFIG.3B. In other aspects, drive assembly312can include a larger number of gears318than motors322.

Motors322can be conventional electric motors. For example, motors322can each include a stator and a rotor contained within a housing. Additionally, in aspects, the housing of a motor can include at least one coolant channel for a non-direct or direct contact cooling fluid, e.g., a dielectric oil, to flow. Each motor322including a cooling system can increase the continuous power rating of motor assembly202. Additionally or alternatively, housing307can include a cooling system for all of motors322, as described below.

While the principles of the present disclosure are discussed with regard to motors322that can be used in an electric vehicle, the principles of the present disclosure can be apply to motors322having any specifications. For example, the principles of the present disclosure can apply to motors322having any continuous power rating, peak power rating, continuous torque rating, and peak torque rating.

In aspects, motors322can be substantially similar. For example, in aspects, motors322can have substantially the same continuous power rating, peak power rating, continuous torque rating, and peak torque rating. In other aspects, the specifications of motors322can vary among motors322. For example, in such aspects, motors322b-322gcan have substantially the same continuous power rating, peak power rating, continuous torque rating, and peak torque rating while motor322acan have a different power rating, peak power rating, continuous torque rating, and/or peak torque rating. In aspects, it may be advantageous to separately configure motor322ato have different specifications from motors322b-322g, as motor322acan operate alone at low torque needs. Additionally, in such aspects, at least two of motors322b-322gcan have different continuous power ratings, peak power ratings, continuous torque ratings, and/or peak torque ratings while motor322acan have a different or the same power rating, peak power rating, continuous torque rating, and/or peak torque rating as at least one of motors322b-322g. In aspects in which the specifications of motors can322vary among motors322, the gear ratios of each of gears318b-318gwith gear318acan be selected based on the specifications of each of motors322to optimize the torque and RPM output of motor assembly202. Further, in such aspects, one or more motors322can be activated or deactivated based on a torque need and individual specifications of motors322(i.e., to optimize the efficiency of motor assembly202at a given torque and RPM output). For example, motors322having various continuous torque ratings can provide a means of more precisely adjusting the continuous torque output of an activated combination of motors of motor assembly202at a given RPM. This can provide increased control over the percentage of the continuous output torque a required output torque comprises at a given RPM, which can enable motor assembly202to more precisely target percentages that correspond to maximum efficiencies.

As shown inFIG.3B, main housing302can include cavities324, such as cavities324a-324g, to receive motors322a-322g.FIG.3Bshows seven cavities324a-324gcorresponding to motors322a-322g. Cavity324acan receive motor322acoupled to gear318a. Cavities324b-324gcan be adjacent cavities that receive motors322b-322g(cavities324b-324gare sequentially labeled in a clockwise direction starting with cavity324bcorresponding to motor322b). That cavities324b-324gare adjacent can mean that cavities324b-324greceive motors that are coupled via shafts320to gears that are in a common gear assembly with gear318a. In aspects, cavity324acan be a central cavity (i.e., arranged between at least two of cavities324b-324g). In such aspects, at least two of cavities324b-324gcan be peripheral cavities arranged around cavity324a.

WhileFIG.3Bshows six cavities324b-324greceiving six motors322b-322g, this is exemplary and main housing302can include fewer or additional adjacent cavities, such as 1, . . . , n adjacent cavities, where n is a positive integer. Further, the number of adjacent cavities can be an even number. Particularly, the adjacent cavities can be pairs of cavities, each cavity of a pair of cavities arranged on opposite sides of cavity324a, for example, like cavity324band cavity324c. The reference to cavities324b-324gin this disclosure should be understood to include aspects in which there are fewer or more than six adjacent cavities. In aspects, main housing302can include a cavity324for each motor322(i.e., the same number of cavities324as motors322within motor assembly202). In other aspects, main housing302can include a larger number of cavities324than the number of motors322included in motor assembly202. In aspects, cavities324can be substantially the same size. In other aspects, cavities324can be sized differently, for example, to accommodate different sized motors322.

A motor322inserted into a cavity324can be at least partially within the cavity324. For example, only a part or none of the motor322can be visible when the motor is inserted into the cavity324. Accordingly, motors322a-322gcan be at least partially within cavities324a-324gwhen motor assembly202is assembled. In aspects, main housing302including cavities324can form a unitary structure for receiving motors322. WhileFIG.3Bshows main housing302having a circular cross section, the cross section main housing302can be ovular or polygonal, such as rectangular, hexagonal, octagonal, etc., without interfering with the function of motor assembly202.

As shown inFIG.3B, motor assembly202can further include a first printed circuit board (PCB)326. First PCB326can include controllers for driving motors322, as described in more detail below. For example, first PCB326can include at least one inverter for controlling motors322. In aspects, first PCB326can include an inverter connected to each of motors322. First PCB326can be positioned between main housing302and layer305such that it abuts motors322. Controllers on first PCB326can connect to terminals on motors322. In aspects, motor assembly202can include a second PCB328including additional components, such as circuitry for receiving and supplying power to motors322from connectors334, described below. In aspects, second PCB328can be positioned between layer305and second end cap306. In other aspects, first PCB326and second PCB328can be combined and can be positioned between main housing302and layer305.

As shown inFIG.3B, layer305can include channels330. Channels330can be cooling channels configured to circulate a cooling fluid. In aspects, the cooling fluid can be a dielectric fluid, for example, a dielectric oil. The cooling fluid can enter and exit channels330through nozzles332. The cooling fluid can contact first PCB326and/or second PCB328and motors322to cool components disposed on first PCB326and/or second PCB328and components disposed within motors322. First PCB326and/or second PCB328being positioned between layer305/channels330and motors322can secure the benefit of a single cooling feature (e.g., channels330for transporting cooling fluid) being used to cool various electronic components within motor assembly202.

Additionally, the inclusion of multiple motors322within motor assembly202can improve the efficiency of motor assembly202's cooling features. For example, as compared to a single large motor, multiple smaller motors322can provide greater access (for cooling) to components within the multiple smaller motors322that generate heat (e.g., the rotors and stators), since the components of a smaller motor can be nearer to exterior surfaces of a housing of the smaller motor. Therefore, a cooling fluid (e.g., dielectric oil) can flow nearer to heat-generating components and better absorb and transfer heat out of motor assembly202.

As shown inFIG.3B, second end cap306can include connectors334. Connectors334can communicatively couple motor assembly202to various components or systems within vehicle100, for example, energy storage system104and/or a power demand system as described below.

First end cap304can be detachable from support plate314and/or main housing302. Support plate314can be detachable from main housing302. First PCB326, layer305, second PCB328, and second end cap306can be detachable from main housing302and one another. Each of these components can be detached by removing fasteners336, as shown inFIG.3B. Accordingly, motor assembly202can be easily disassembled to gain access to drive assembly312for the configuration and/or repair of drive assembly312. For example, motors322can each be detachable from its corresponding gear318and from support plate314. Individual motors322can be easily removed and serviced or replaced. Further, individual gears318can be easily removed and serviced or replaced.

The size and weight of each of motors322can allow a single technician to handle and repair motor assembly202. For example, in aspects, one of motors322can be removed and inspected by a single technician, as it can weigh about 8-12 kg. In comparison, an electric motor with a peak power rating of about 400 kW for use in an EV can weigh 50 kg or more. A technician can open motor assembly202, remove a gear318from a motor322, detach the motor322from support plate314, and repair or replace the motor322. Alternatively, the technician can remove or add motors322to configure motor assembly202to operate in a particular environment (e.g., a flat region requiring less torque and fewer motors322within motor assembly202).

FIG.4shows a diagram of a drive system400according to aspects of the disclosure. Drive system400can include energy storage system104, motor assembly202, a control system402, and a power demand system406. Power demand system406can be integrated within a device implementing motor assembly202, such as vehicle100. Power demand system406can determine a torque need to be requested from motor assembly202. The torque need can be based on a particular speed, or RPM, a user of an EV is desiring to produce at a given resistance (i.e., a particular RPM output can result from a particular torque output applied to a given resistance). In an EV, the torque need can be based on a user operation of the EV, which can in turn be based on an environment in which the EV is operating. For example, when the EV is operating on a hill, a user may apply more force to an accelerator of the EV to maintain the constant speed of the EV while traveling up the hill. Power demand system406can determine, based on the user's action, that an increased torque must be requested from motor assembly202. In a self-driving system, power demand system406can determine the torque need based on monitoring features of the environment (e.g., forces acting on the vehicle, speed limit signs, the radius of a turn in the road, position calculated by a GPS along with data, for example, speed limit data, associated with the position, etc.). Once power demand system406has determined the torque need, power demand system406can communicate the torque need to control system402, which can request motor assembly202produce the torque need as an output torque. Power demand system406can communicate the torque need to control system402at any interval to communicate changes in the torque need. Energy storage system104can provide power to motor assembly202to meet the torque need communicated to control system402by power demand system406.

In aspects, power demand system406can include one or more computer processors and/or sensors within the device implementing motor assembly202. For example, power demand system406can include one or more microprocessors (MPUs), microcontrollers (MCUs), and/or systems-on-chip (SoCs). Additionally, power demand system can include one or more sensors, for example, an accelerator pedal position sensor, one or more accelerometers and/or force sensors, one or more image sensors, a GPS, etc. The one or more computer processors can be configured to receive outputs of the one or more sensors, calculate a torque need based on the outputs, and communicate the torque need to control system402. The one or more computer processors can be communicatively coupled to memory of the power demand system406and can be configured to perform the above operations, for example, by implementing software instructions stored on the memory. The memory of power demand system406can include dynamic random access memory (DRAM), low-power dynamic random access memory (LPDRAM), NOR flash memory, NAND flash memory, embedded MultiMediaCard (eMMC), universal flash storage (UFS), and/or non-volatile memory express (NVMe) memory.

In aspects, control system402can be bodily integrated with motor assembly202, for example, by being integrated into first PCB326and/or second PCB328. In other aspects, control system402can be distinct from but communicatively coupled to motor assembly202, or can be partially bodily integrated with motor assembly202and partially distinct from but communicatively coupled to motor assembly202. Control system402can include one or more computer processors (e.g., one or more MPUs, MCUs, and/or SoCs) configured to receive the torque need from power demand system406and instruct motor assembly202to produce the torque need as an output torque, for example, via one or more motor controllers, as described herein.

Based on the torque need, control system402can selectively activate or deactivate one or more motors322within motor assembly202. For example, control system402can activate one or motors322if the torque need increases, and deactivate one or more motors322if the torque need decreases. As shown inFIG.4, motor assembly can include any number of motors up to motor322n. In aspects, control system402can selectively activate, deactivate, and control motors322individually. In aspects, control system402can selectively activate, deactivate, and control motors322in pairs. For example, based on power demand system406determining that motor assembly202is required to output a decreased torque, control system402can deactivate pairs of motors that are arranged on opposite sides of motor322a, such as motors322band322eshown inFIG.3B. Activating or deactivating motors in opposing pairs can maintain mechanical balance within motor assembly202during operation.

In aspects, activated pairs of motors322can be rotated among motors322based on motor usage (e.g., total input or output power). For example, in aspects, control system402can be configured to track usage of each of motors322such that a pairs of motors322can deactivated and another pair of motors322can be activated based on motor usage. This method can be utilized even if motors322are not activated or deactivated in pairs. In this way, control system402can maintain approximate equivalency of usage among motors322. Accordingly, the lifetime of motors322can be extended and the frequency of servicing motor assembly202to address failure of over-utilized motors can be reduced.

In aspects, control system402can activate or deactivate one or more motors322to reach a maximally efficient number of motors322for outputting the torque need. For example, the maximally efficient number of motors322can be a number of motors that causes the torque need to comprise a percentage of the continuous output torque (of the number of active motors322collectively) that corresponds to a maximum possible operating efficiency for motor assembly202. The determination of operating efficiency for specific torque and RPM outputs of an electric motor is discussed below in more detail with respect toFIG.6.

In aspects, the maximally efficient number of motors322can be calculated by control system402based on at least one of a continuous power rating, peak power rating, continuous torque rating, peak torque rating, or service factor of each of motors322(e.g., by comparing the torque need to a cumulative continuous or peak torque rating of various numbers of motors322and selecting the number that most efficiently produces the torque need). For example, in aspects, the maximally efficient number of motors322can be a number of motors322that causes the torque need to be between about 60 percent and about 100 percent of the cumulative continuous torque rating of the number of motors322.

Additionally or alternatively, the maximally efficient number of motors322can be calculated by control system402based on data on at least one of continuous output torque or peak output torque of motors322at a given RPM at which motor assembly202is operating (e.g., by comparing the torque need to a cumulative continuous or peak output torque of various numbers of motors322and selecting the number that most efficiently produces the torque need, accounting for the variation in continuous output torque caused by changes in RPM output). For example, in aspects, the maximally efficient number of motors322can be a number of motors322that causes the torque need to be between about 60 percent and about 100 percent of the cumulative continuous output torque of the number of motors322at the current RPM output.

Additionally or alternatively, the maximally efficient number of motors322can be calculated by control system402based on a temperature of individual motors322within motor assembly202(e.g., the maximally efficient number of motors can be increased if the temperature of a motor322rises above a threshold level).

In aspects, the maximally efficient number of motors322can be the minimum number of motors322required to continuously output the torque need. As noted above, in aspects, this number can depend on RPM output.

In aspects, calculating the maximally efficient number of motors322can include calculating a maximally efficient number of pairs of motors322, such that activating the maximally efficient number of motors322does not cause mechanical imbalance by activating an unpaired motor322.

With reference toFIG.3B, control system402can drive each of motors322a-322gin a direction that contributes to the turning of gear318ain a particular direction. For example, in aspects in which gears318b-318gare each directly coupled to gear318a, control system402can drive each of motors322b-322gin an opposite direction to motor322a. For example, control system402can drive motors322b-322gclockwise while driving motor322acounterclockwise, or vice-versa.

Control system402can communicate with motors322via controllers404, such as controllers404a-404n. In aspects, controllers404can be 3-phase motor controllers. In aspects, controllers404can each include an inverter. In aspects, controllers can be variable-frequency drive (VFD) controllers. Accordingly, controllers404can control motors322via field-oriented control (FOC). In other aspects, controllers404can control motors322via direct torque control (DTC) or V/Hz control. In aspects, controllers404can be bodily integrated with motors322. In other aspects, controllers404can be distinct from but communicatively coupled to motors322, for example, by being integrated within first PCB326and/or second PCB328. As shown inFIG.4, control system402can include a controller404per motor322. Controllers404can activate, deactivate, and control individual motors of motors322based on the torque need.

FIG.5shows a diagram of a drive system500according to aspects of the disclosure. Drive system500can be substantially the same as drive system400. However, drive system500can include a single controller404per pair of motors within motors322. Like drive system400, drive system500can include a single controller404acontrolling motor322a. However, drive system500can include a single controller404bcontrolling both of motors322band322c. Drive system500can likewise include a single controller404ccontrolling both of motors322cand322f. Drive system500can include any number of controllers404up to controller404n, and, as noted above, motor assembly202can include any number of pairs of motors, with the final pair of motors being represented by322dand322n. Each of the pairs of motors can be controlled by a controller404. In aspects, the pairs of motors controlled by controllers404can be two motors arranged on opposite sides of motor322a, like motors322band322eshown inFIG.3B. In other aspects, the pairs of motors controlled by controllers404can be two motors arranged in any other configuration, such as side by side, like motors322band322cshown inFIG.3B.

The configuration ofFIG.5can be advantageous when motors322b-322nare controlled in pairs. For example, the configuration ofFIG.5can reduce the number of components required while maintaining the functionality of activating or deactivating motors322b-322nin pairs based on the torque need.

FIG.6shows a graph of motor efficiency as a function of output torque and RPM for an electric motor. Motor efficiency is defined as the percentage of electrical input power that is converted to mechanical output power.

The electric motor ofFIG.6has a continuous power rating of about 150 kW. While the scale and shape ofFIG.6depends on the specifications of the electric motor (e.g., continuous power rating, peak power rating, etc.),FIG.6illustrates the relationship between torque (Nm), speed (RPM), and efficiency for electric motors. In particular,FIG.6shows that efficiency decreases at lower loads (i.e., at output torques that represent a smaller percentage of the electric motor's continuous output torque for a given RPM). For example,FIG.6shows that at 8,000 RPM, the electric motor operates at an efficiency of about 90% when providing 50 Nm of torque. However, the electric motor operates at an efficiency of about 82% when providing 12 Nm of torque at the same RPM. Using an inverter with an efficiency of 92% at low loads to operate the electric motor therefore yields an overall efficiency of about 75% at 12 Nm of torque and 8,000 RPM. In aspects, this torque and RPM represents the approximate requirements of propelling an EV at 60 MPH on a flat road (e.g., a highway).

However, as noted above, motor assembly202can provide a means for dynamically adjusting the peak and continuous output torque at a given RPM. Specifically, the plurality of electric motors of motor assembly202can each be activated or deactivated based on a torque needed to achieve a particular RPM. For example, ifFIG.6represents motor assembly202with all motors322operating, deactivating one or more motors322to reduce the continuous output torque of motor assembly202at a given RPM can cause the torque need to comprise a higher percentage of the continuous output torque of motor assembly202(i.e., of the continuous output torque of active motors322collectively). This can effectively compress the graph ofFIG.6along the y-axis for motor assembly202. Accordingly, the efficiency of motor assembly202can be improved when providing the torque need. As a result, the range of an EV implementing motor assembly202can be increased.

For example, providing 12 Nm of output torque at 8,000 RPM, motor assembly202can operate at an efficiency of about 92% when operating with a single motor (e.g., motor322a). Using an inverter with an efficiency of 98% at medium loads to operate motor322ayields an overall efficiency of about 90%. Motor322aby itself can provide a continuous output torque of about 24 Nm at 8,000 RPM, and therefore 12 Nm comprises about 50% of the continuous output torque of motor assembly202operating in such a configuration at 8,000 RPM. This is a higher percentage of the continuous output torque of motor assembly202than when additional motors322are activated, resulting in increased efficiency. This increased efficiency is not only compared to motor assembly202with more motors322activated; it also represents an increased efficiency as compared to a single, large electric motor having similar specifications as motor assembly202with all motors322activated, such single, large electric motors being conventionally provided in electric motor assemblies.

In the first case above, an electric motor operating at about 75% overall efficiency would require a battery to provide 13.3 kW of power (not including the 12V parasitic loss and battery loss). Therefore, an 80 kWh battery could provide about 6 hours of operation. At 60 MPH, this corresponds to about 360 miles of range. Motor assembly202operating with only motor322aactivated, yielding an overall efficiency of 90%, would require a battery to provide 11.1 kW of power (not including the 12V parasitic loss and battery loss). Therefore, an 80 kWh battery could provide about 7.2 hours of operation. At 60 MPH, this corresponds to about 435 miles of range, a 20% improvement. Alternatively, a 20% smaller battery would be needed to travel the same range.

While the example of all but motor322aof motor assembly202being deactivated is provided, it should be understood that similar increases in efficiency can be achieved by activating whatever number of motors322corresponds to a maximally efficient configuration for a given torque and RPM output. That is, control system402can activate the number of motors322that, at the RPM output, causes the output torque to comprise a percentage of the continuous output torque of the active number of motors322that corresponds to a maximum possible operating efficiency for motor assembly202.

FIG.7shows a diagram of a method700according to aspects of the disclosure. In aspects, the electric drive unit of method700can be first or second drive unit102aor102b. The method700can include step702.

Step702can include installing an electric motor assembly in an electric drive unit, the electric motor assembly including: a housing including a plurality of cavities; a gear assembly, the gear assembly including: an output gear coupled to an output shaft, and adjacent gears coupled to the output gear; the electric motor assembly further including: a plurality of electric motors at least partially within the plurality of cavities, the plurality of electric motors including: a first electric motor coupled to the output gear, and adjacent electric motors coupled to the adjacent gears; the electric motor assembly further including: a controller to activate and deactivate one or a pair of motors of the plurality of electric motors. In aspects, the housing can be main housing302. In aspects, the plurality of cavities can be cavities324a-324g. In aspects, the gear assembly can be gear assembly316. In aspects, the adjacent gears can be gears318b-318g. In aspects, the output gear can be gear318a. The adjacent gears can be either directly or indirectly coupled to gear318a, as described with respect toFIG.3B. In aspects, the plurality of electric motors can be motors322. In aspects, the adjacent electric motors can be motors322b-322g. In aspects, the first electric motor can be motor322a. In aspects, the controller can be any one of controllers404.

In aspects, the electric drive unit of step702can be installed on a vehicle. In aspects, the vehicle can be an electric vehicle. In aspects, the vehicle can be vehicle100.

In aspects, the plurality of cavities of method700can include peripheral cavities arranged around a central cavity. In aspects, the peripheral cavities can be cavities324b-324gand the central cavity can be cavity324a. In aspects, the adjacent electric motors of method700can be an even number of electric motors. In aspects, the electric motor assembly of method700can further include a cooling feature configured to simultaneously cool at least one motor of the plurality of electric motors and a printed circuit board (PCB) connected to the at least one motor. In aspects, the cooling feature can be one or more of cooling channels330and the PCB can be first PCB326and/or second PCB328. In aspects, method700can further include selecting a number of electric motors to be included in the plurality of cavities based on a use environment.

In aspects, the electric motor assembly installed in the electric drive unit of method700can be motor assembly202described with respect toFIG.3A-3Cor motor assembly202described with respect toFIGS.8A-8B.

FIG.8Ashows an electric motor assembly202according to aspects of the disclosure. As shown inFIG.8A, in aspects, motor assembly202can include additional gears in gear assembly316to increase the amount of torque motor assembly202can provide. For example, as shown inFIGS.8A, motor assembly202can include a gear assembly316configured to provide more space for additional adjacent motors322to be coupled to an output gear. In aspects, additional gears of gear assembly316shown inFIG.8Acan include gears318h-318jand ring gear802. In aspects according toFIGS.8A-8B, the “output gear” can be ring gear802rather than gear318a. That is, ring gear802can be coupled to a rotatable output shaft (e.g., via a drive plate) to transmit a torque to an external component (e.g., an axle). Gear318acan be coupled to a shaft808that can spin without engaging an external component and/or that can be anchored in a bearing.

In aspects, ring gear802can include gear teeth on both an inner side804aand outer side804b.

In aspects according toFIG.8A, gear318acan be a sun gear. In aspects, gears318h-318jcan be planetary gears. In aspects, gears318h-318jcan be rotatably fixed relative to main housing302. That is, gears318h-318jcan rotate around the center axis of their associated shafts320, but do not translate relative to main housing302(or housing307) such that they move around shaft808. In aspects, shafts320supporting gears318h-318jcan be fixed to a plate805that is secured to support plate314(e.g., via screws or bolts). In aspects, gears318h-318jcan be coupled to their associated shafts320via needle bearings which allow them to rotate on their associated shafts320. In aspects, associated shafts320supporting gears318h-318jcan be rotatably coupled relative to plate805, support plate314, and/or main housing302such that the shafts320rotate while gears318h-318jare secured relative to their associated shafts320.

In aspects, gears318h-318jdo not have any associated motors322. Instead, they free spin to transmit a torque from gear318a, which is coupled to motor322a, to ring gear802.

In aspects, gears318h-318jcan be coupled, via their associated shafts320, to additional motors322positioned at least partially within additional cavities324of main housing302.

In aspects, gears318aand318h-318jcan be inner adjacent gears. Gears318aand318h-318jcan be “inner” adjacent gears in that they can be interior to inner side804aof ring gear802. Inner side804acan face toward gear318aand shaft808. Ring gear802can be coupled to gears318h-318j. For example, in aspects, gears318h-318jcan contact and be enmeshed with inner side804a. In aspects, gears318h-318jcan be directly coupled to gear318aand/or ring gear802. WhileFIG.8Ashows three gears318h-318j, in aspects, gear assembly316can include any number of gears318h-318j(e.g., planetary gears), for example, two, four, five, or six.

In aspects, gears318b-318gcan be outer adjacent gears coupled to ring gear802. Gears318b-318gcan be “outer” adjacent gears in that they can be exterior to outer side804bof ring gear802. Outer side804bcan face away from gear318aand shaft808. In aspects, gears318b-318gcan contact and be enmeshed with outer side804b. Collectively, gears318a-318jcan be referred to as adjacent gears, since they are in a common gear assembly316with ring gear802(the output gear).

With respect to the aspects according toFIG.8A-8B, motor(s)322coupled to gears318a(and318h-318j, if any), can be referred to as “inner” adjacent motors322, and motors322coupled to gears318b-318gcan be referred to as “outer” adjacent motors322. In aspects, inner adjacent motors322can include shafts320that lie along axes positioned inside the perimeter of ring gear802. In aspects, outer adjacent motors322can include shafts320that lic along axes positioned outside the perimeter of ring gear802. Collectively, motors322coupled to gears318a-318jcan be referred to as adjacent motors, as noted herein, since they are coupled to gears that are in a common gear assembly316with ring gear802. In aspects, motor322acan still be a central motor and gear322acan still be a central gear.

In aspects, the outer adjacent motors322can be an even number of motors322. For example, motor assembly202can include two, four, six, eight, 10, 12, or 14, etc., outer adjacent motors322.

Because of ring gear802's increased diameter relative to gear318aofFIG.3B, a greater number of outer adjacent motors322can be included in motor assembly202, since there is space for additional motors322and outer adjacent gears that are enmeshed with ring gear802. Accordingly, in aspects, motor assembly202includes more than six outer adjacent motors322.

Additionally, the configuration shown inFIG.8Aallows for multiple gear ratios between inner adjacent gears318a,318h-318jand ring gear802and between outer adjacent gears318b-318gand ring gear802. For example, in aspects, an inner adjacent gear (e.g., gear318a) can form a first gear ratio with ring gear802, while an outer adjacent gear can form a second gear ratio with ring gear802. This can provide multiple layers of configurability for motor assembly202. Any gear ratio can be selected to ensure that motors322will be driven at various speeds to maximize performance and efficiency, achieve gear reduction, avoid field weakening, etc. In aspects, all outer adjacent gears318b-318gcan form the same gear ratio with ring gear802.

In aspects, the first gear ratio can be lower than the second gear ratio. For example, gear318a(e.g., a sun gear) can form a gear ratio of 4:1 with ring gear802(gear318aturns four times for each single turn of ring gear802), while one or more outer adjacent gears318b-318gcan form a gear ratio of 8:1 with ring gear802(the outer adjacent gear turns eight times for each single turn of ring gear802). These are example gear ratios and any values for the first and second gear ratios can be selected. In this example, motor322acoupled to gear318awill run at half the speed of outer adjacent motors322coupled to the one or more outer adjacent gears318b-318g. The first gear ratio being lower than the second gear ratio can avoid or reduce field weakening of motor322a, since motor322awill run at a reduced speed compared to outer adjacent motors322. Avoiding or reducing field weakening in motor322acan benefit efficiency since, in aspects, motor322amay be activated for greater periods of time than other motors322of motor assembly202.

In aspects, motor assembly202can include additional ring gears coupled to additional gears, and shafts positioned outside the additional ring gears, coupled to additional motors. For example, in aspects, motor assembly202can include an additional ring gear coupled to gears318b-318gon the additional ring gear's inner side and additional gears coupled to the outer side of the additional ring gear. In this way, the continuous and peak output torque of motor assembly202can be increased.

Motors322of the motor assembly202shown inFIG.8Acan be selectively controlled as described with respect toFIGS.3A-3BandFIGS.4-5.

In aspects of motor assembly202shown inFIGS.3A-3C and8A, deactivated motors322can be free-spun due to the engagement of their associated gears318with one another (either directly or indirectly). For example, if motor322bis deactivated while motor322aremains activated, motor322b's shaft320can remain statically coupled to gear318b, which can be rotated by its coupling to gear318a. This can rotate motor322b's shaft320. Because motors322can include permanent magnets in their rotors, this can produce substantial back electric and magnetic fields (back EMF)—which can cause motor assembly202to require field weakening to produce high RPMs—and can cause mechanical degradation of internal motor components caused by continual spinning. Additionally the required torque to turn deactivated motors322can cause losses.

FIG.8Bshows an electric motor assembly202according to aspects of the disclosure. As shown inFIG.8B, in aspects, motor assembly202can include clutches806to mechanically engage and disengage motors322from adjacent gears318b-318g(and318h-318jif motor assembly202includes motors322associated with gears318h-318j). In aspects, each of clutches806can selectively secure an adjacent gear318relative to a shaft320. When the clutch806is engaged, the adjacent gear318is secured relative to shaft320. When the clutch806is disengaged, the adjacent gear318can rotate freely relative to shaft320. This can allow an adjacent gear318to spin on shaft320, which can be useful when an associated motor322is deactivated according to the methods disclosed herein. By mechanically disengaging deactivated motors322from gear assembly316, back EMF produced by rotation of shaft320of the deactivated motor322due to its coupling to other driven gears of gear assembly316can be avoided. Accordingly, individual motors322can be selectively mechanically disengaged from gear assembly316to reduce back EMF and increase the efficiency of a drive system implementing motor assembly202.

Clutches806can include a variety of types of clutches, including but not limited to hydraulic/pneumatic clutches, electromagnetic clutches, and sprag clutches. In aspects, hydraulic/pneumatic clutches can include hydraulically or pneumatically operated clutch packs, as described with respect toFIGS.9A-9B. In aspects, clutches806can each include a hydraulically or pneumatically operated clutch pack. In aspects, clutches806can be electromagnetic clutches. In aspects, clutches806can be sprag clutches.

While shown on aspects of motor assembly202including gears318h-318jand ring gear802, clutches806can be implemented with gears318b-318gshown inFIGS.3B-3C. Further, whileFIG.8Bshows clutches806implemented with all gears318b-318g, in aspects, clutches806can be implemented with only a subset of gears318b-318g. Additionally, in aspects, a clutch806can be implemented with gear318ato allow gear318ato selectively free spin on shaft808, for example, if motor322ais not activated.

In aspects, rather than implementing clutches806with gears318b-318g, motors322b-322gcoupled to gears318b-318gcan be induction motors. This can eliminate problems otherwise caused by back EMF produced by spinning permanent magnets within motors322b-322g.

FIGS.9A-9Bshow an example clutch806for use with a gear318according to aspects of the disclosure. Clutch806shown inFIGS.9A-9Bcan include a hydraulically or pneumatically operated clutch pack. Clutch806shown inFIGS.9A-9Bis exemplary and is not intended to limit clutches806described herein to any particular type of clutch. As shown inFIG.9A, a clutch806can include a hub902secured relative to shaft320via key904, which is situated in a keyway formed by shaft320and hub902. Clutch806can also include a drive disk906coupled to hub902. Drive disk906can be secured relative to hub902(e.g., via gear teeth) and can rotate with shaft320and hub902. Clutch806can also include a friction disk908coupled to gear318. Friction disk908can be secured relative to gear318via protrusions910, which fit into slots912of gear318or another component statically coupled to gear318. Clutch806can be actuated such that drive disk906and friction disk908are selectively pressed against one another, causing static friction between drive disk906and friction disk908to secure gear318relative to shaft320via friction disk908, drive disk906, and hub902.

As shown inFIG.9B, clutch806can include a plurality of drive disks906and a plurality of friction disks908. Drive disks906and friction disks908can form a clutch pack. The clutch pack can be operated via an inlet914which can receive a gas or liquid. In aspects, the gas can be pressurized air and/or other gases, and the liquid can be pressurized water or oil.

Inlet914can be positioned on a support916, which can be a hollow cylinder or block through which shaft320runs. Support916can be statically coupled to main housing302, in some cases via support plate314, such that support916does not rotate relative to main housing302. A control valve918can control the release of a pressurized gas or liquid into inlet914. A pressurized gas or liquid released into inlet914can force drive disks906and friction disks908to contract along the axis of shaft320, causing them to lock together to transmit a torque between shaft320and gear318.

FIG.10shows a drive system1000according to aspects of the disclosure. Drive system1000can include energy storage system104, control system402, and power demand system as described with respect toFIGS.4-5. Drive system1000can include motor assembly202as described with respect toFIGS.3A-3CorFIGS.8A-9B. In aspects according toFIG.10, control system402can additionally include controllers1010to control respective clutches806. In aspects, controllers1010can include electrically operated control valves. In aspects, controllers1010can include control valves918of each clutch806, which can be electrically operated. The control valves918can receive signals from one or more computer processors of control system402instructing the control valves918to open or close, or otherwise regulate the pressure of a fluid passing through control valves918.

In aspects, control system402can be configured to: activate and deactivate one or more motors322based on a torque need received from power demand system406such that a number of simultaneously activated motors322depends on the torque need; and mechanically engage or disengage, by operating a clutch806, an activated or deactivated adjacent motor322to or from an adjacent gear318in response to the activated or deactivated adjacent motor322having been activated or deactivated, respectively. In aspects, alternatively or additionally, control system402can be configured to: mechanically engage and disengage one or more adjacent electric motors322to and from one or more adjacent gears318based on a torque need received from power demand system406such that a number of simultaneously mechanically engaged motors322depends on the torque need; and activate or deactivate a mechanically engaged or disengaged adjacent motor322in response to the mechanically engaged or disengaged adjacent motor322having been mechanically engaged or disengaged, respectively. In aspects, alternatively or additionally, control system402can be configured to send signals to an adjacent motor322and its associated clutch806simultaneously to both activate or deactivate the adjacent motor322and mechanically engage or disengage the adjacent motor322from an adjacent gear318, respectively.

In aspects, control system402can be configured to mechanically disengage an adjacent motor322from an adjacent gear318based on a torque need, deactivate the adjacent motor322, reactivate the adjacent motor322based on a change in the torque need, and then mechanically reengage the adjacent motor322to the adjacent gear318. In aspects, control system402can be configured to deactivate an adjacent motor322based on a torque need, mechanically disengage the adjacent motor322from an adjacent gear318, reactivate the adjacent motor322based on a change in the torque need, and then mechanically reengage the adjacent motor322to the adjacent gear318.

Accordingly, control system402may be configured to mechanically engage or disengage an adjacent electric motor322to or from an adjacent gear318in conjunction with the adjacent electric motor322being activated or deactivated, respectively, using a variety of methods. Using any of the above methods, adjacent motors322can be both electrically and mechanically disengaged when they are not required to meet a torque need, and/or when their operation decreases the efficiency of motor assembly202in producing an output torque at a given RPM. Mechanical disengagement reduces or avoids inefficiencies caused by back EMF produced by spinning deactivated motors322. Additionally, mechanical degradation of internal motor components can be reduced or avoided.

In aspects, control system402can be configured to seamlessly reintegrate a previously deactivated and mechanically disengaged adjacent motor322with gear assembly316. For example, control system402can be configured to activate the adjacent motor322and control, via a controller404, the rotational velocity of its shaft320to match the rotational velocity of the adjacent gear318coupled to its shaft320and rotating within gear assembly316(but disengaged by the previous operation of an associated clutch806). Then, once the rotational velocity of shaft320matches the rotational velocity of the adjacent gear318, within certain tolerances (e.g., ±10%, 5%, 2%, or 1%), control system402can be configured to engage the associated clutch806to secure the adjacent gear318relative to shaft320.

Control system402can be configured as described herein using any known method of computer programming. For example, control system402can include one or more computer processors (e.g., one or more MPUs, MCUs, and/or SoCs) and memory having software instructions stored thereon. The one or more computer processors can be communicatively coupled to the memory and can be configured to perform operations specified in the software instructions, for example: receiving a torque need from power demand system406, calculating a required and/or maximally efficient number of motors322to meet the torque need as described herein, selecting motors322to activate/deactivate and mechanically engage/disengage, and sending instructions via controllers404/1010to the selected motors322and their associated clutches806to perform activation/deactivation and mechanical engagement/disengagement. The memory of control system402can include dynamic random access memory (DRAM), low-power dynamic random access memory (LPDRAM), NOR flash memory, NAND flash memory, embedded MultiMediaCard (eMMC), universal flash storage (UFS), and/or non-volatile memory express (NVMe) memory.

FIG.11shows a drive system1100according to aspects of the disclosure.FIG.11shows single controllers404and1010being used for multiple motors322and clutches806, analogous toFIG.5. As shown inFIG.11, in aspects, a single controller404can be used to control two adjacent motors322, and a single controller1010can be used to control two clutches806. This can be advantageous for activating/deactivating and mechanically engaging/disengaging adjacent motors322and associated clutches806in pairs to maintain mechanical balance within gear assembly316, as discussed herein.

The configurations of drive systems1000and1100shown inFIGS.10-11are not intended to limit the specific number of adjacent motors322that a single controller404controls, or the number of clutches806that a single controller1010controls. For example, a single controller404can control any number 1, . . . , n of adjacent motors322intended to be operated together (i.e., driven at the same speed and deactivated/activated simultaneously) and a single controller1010can control any number 1, . . . , n of clutches806intended to be operated together (i.e., engaged/disengaged simultaneously), where n is a positive integer. Additionally, in aspects, a hybrid of the drive systems1000and1100ofFIGS.10-11is contemplated, in which a single controller404is used to control two adjacent motors322, but two separate controllers1010are used to control clutches806associated with the same two adjacent motors322.

In aspects, motor assembly202described with respect toFIGS.3A-3CorFIGS.8B-11can implement a novel resolver configuration. A resolver is a device that measures the angular position and angular speed of a motor322's shaft320. The data produced by the resolver is used in the control of the motor322, since a motor controller can implement data on current operating conditions to accurately adjust torque and/or RPM. Typically, each motor322requires a separate resolver.

The novel resolver configuration can include a single resolver used for multiple motors322. In aspects of motor assembly202not including clutches806, this can be accomplished, for example, by using a single resolver for multiple adjacent motors322b-322gthat are in sync (i.e., their associated shafts320rotate at the same speed and are simultaneously at the same angular displacement with respect to an initial angular position). However, in the aspects of motor assembly202including clutches806, mechanically disengaged motors322can fall out of sync with other mechanically engaged motors322.

However, in aspects, motor assembly202including clutches806can still include a single resolver per multiple motors322. For example, motor assembly202can include a single resolver for a pair of adjacent motors322. In aspects, motor assembly202can include a single resolver for any number of adjacent motors322.

In aspects, the use of a single resolver per multiple motors322can be achieved by control system402performing a resolverless calculation that considers feedback produced by permanent magnets within motors322. When a deactivated adjacent motor322is mechanically disengaged from an adjacent gear318as described herein, its shaft320will continue to rotate at a substantially reduced rate and/or for a short time due to angular momentum of the shaft320/adjacent gear318and friction between the shaft320and the adjacent gear318. As the shaft320rotates, the permanent magnets of the adjacent motor322's rotor will produce back EMF. In aspects, control system402can receive this back EMF and calculate, based on data and/or the waveform related to the back EMF, how much the shaft320has rotated since going out of sync with another adjacent motor322that is coupled to a resolver. Control system402can use the results of this calculation, in association with data from the resolver coupled to the other adjacent motor322, to obtain shaft angular position and angular speed data necessary to control both adjacent motors322. In aspects, control system402can do this for any number of adjacent motors322, using a single resolver coupled to one of the adjacent motors322.

FIG.12shows an exemplary computer system1200by which aspects, or portions thereof, can be implemented as computer-readable code, according to some aspects. For example, aspects of the processes discussed herein can be implemented by computer system1200using hardware, software, firmware, tangible computer readable media having instructions stored thereon, or a combination thereof and can be implemented by one or more computer systems or other processing systems.

If programmable logic is used, such logic can execute on a commercially available processing platform or a special purpose device. One of ordinary skill in the art can appreciate that aspects of the disclosed subject matter can be practiced with various computer system configurations, including multi-core multiprocessor systems, minicomputers, and mainframe computers, computer linked or clustered with distributed functions, as well as pervasive or miniature computers that can be embedded into virtually any device.

For instance, at least one processor device and a memory can be used to implement the above-described aspects. A processor device can be a single processor, a plurality of processors, or combinations thereof. Processor devices can have one or more processor “cores.”

Various aspects described herein can be implemented in terms of this example computer system1200. After reading this description, it will become apparent to a person skilled in the relevant art how to implement one or more of the aspects using other computer systems and/or computer architectures. Although operations can be described as a sequential process, some of the operations can in fact be performed in parallel, concurrently, and/or in a distributed environment, and with program code stored locally or remotely for access by single or multi-processor machines. In addition, in some aspects the order of operations can be rearranged without departing from the spirit of the disclosed subject matter.

Processor device1204can be a special purpose or a general-purpose processor device. As will be appreciated by persons skilled in the relevant art, processor device1204can also be a single processor in a multi-core/multiprocessor system, such system operating alone, or in a cluster of computing devices operating in a cluster or server farm. Processor device1204is connected to a communication infrastructure1206, for example, a bus, message queue, network, or multi-core message-passing scheme.

Computer system1200also comprises a main memory1208, for example, random access memory (RAM), and can also comprise a secondary memory1210. Secondary memory1210can comprise, for example, a hard disk drive1212, or removable storage drive1214. Removable storage drive1214can comprise a floppy disk drive, a magnetic tape drive, an optical disk drive, a flash memory, a Universal Serial Bus (USB) drive, or the like. The removable storage drive1214reads from and/or writes to a removable storage unit1218in a well-known manner. Removable storage unit1218can comprise a floppy disk, magnetic tape, optical disk, etc. which is read by and written to by removable storage drive1214. As will be appreciated by persons skilled in the relevant art, removable storage unit1218comprises a computer usable storage medium having stored therein computer software and/or data.

Computer system1200(optionally) comprises a display interface1202(which can comprise input and output devices such as keyboards, touchscreens, buttons etc.) that forwards graphics, text, and other data from communication infrastructure1206(or from a frame buffer not shown) for display on a display unit1203.

In additional and/or alternative implementations, secondary memory1210can comprise other similar means for allowing computer programs or other instructions to be loaded into computer system1200. Such means can comprise, for example, a removable storage unit1222and an interface1220. Examples of such means can comprise a program cartridge and cartridge interface (such as that found in video game devices), a removable memory chip (such as an EPROM, or PROM) and associated socket, and other removable storage units1222and interfaces1220which allow software and data to be transferred from the removable storage unit1222to computer system1200.

Computer system1200can also comprise a communications interface1224. Communications interface1224allows software and data to be transferred between computer system1200and external devices. Communications interface1224can comprise a modem, a network interface (such as an Ethernet card), a communication port, a PCMCIA slot and card, or the like. Software and data transferred via communications interface1224can be in the form of signals, which can be electronic, electromagnetic, optical, or other signals capable of being received by communications interface1224. These signals can be provided to communications interface1224via a communications path1226. Communications path1226carries signals and can be implemented using wire or cable, fiber optics, a phone line, a cellular phone link, an RF link or other communication channels.

In this document, the terms “computer program medium” and “computer usable medium” are used to generally refer to media such as removable storage unit1218, removable storage unit1222, and a hard disk installed in hard disk drive1212. Computer program medium and computer usable medium can also refer to memories, such as main memory1208and secondary memory1210, which can be memory semiconductors (for example, DRAMs, etc.).

Computer programs (also called computer control logic) are stored in main memory1208and/or secondary memory1210. Computer programs can also be received via communications interface1224. Such computer programs, when executed, enable computer system1200to implement the aspects as discussed herein. In particular, the computer programs, when executed, enable processor device1204to implement the processes of the aspects discussed here. Accordingly, such computer programs represent controllers of the computer system1200. Where the aspects are implemented using software, the software can be stored in a computer program product and loaded into computer system1200using removable storage drive1214, interface1220, and hard disk drive1212, or communications interface1224.

Aspects described herein also can be directed to computer program products comprising software stored on any computer useable medium. Such software, when executed in one or more data processing device, causes a data processing device(s) to operate as described herein. Aspects described herein can employ any computer useable or readable medium. Examples of computer useable mediums comprise, but are not limited to, primary storage devices (for example, any type of random access memory), secondary storage devices (for example, hard drives, floppy disks, CD ROMS, ZIP disks, tapes, magnetic storage devices, and optical storage devices, MEMS, nanotechnological storage device, etc.).

The term “about” or “substantially” or “approximately” as used herein means the value of a given quantity that can vary based on a particular technology. Based on the particular technology, the term “about” or “substantially” or “approximately” can indicate a value of a given quantity that varies within, for example, 0.1-10% of the value (e.g., ±0.1%, ±1%, ±2%, ±5%, or ±10% of the value).

The breadth and scope of the present disclosure should not be limited by any of the above-described exemplary aspects, but should be defined only in accordance with the following claims and their equivalents.

The claims in the instant application are different than those of the parent application or other related applications. The Applicant therefore rescinds any disclaimer of claim scope made in the parent application or any predecessor application in relation to the instant application. The Examiner is therefore advised that any such previous disclaimer and the cited references that it was made to avoid, may need to be revisited. Further, the Examiner is also reminded that any disclaimer made in the instant application should not be read into or against the parent application.