Electric drive units with integrated power electronics for vehicle powertrains

Presented are electric drive unit (EDU) assemblies with integrated power electronics, methods for making/operating such EDU assemblies, and motor vehicles equipped with such EDU assemblies. An EDU assembly includes an outer housing that mounts to a vehicle body. The EDU outer housing has internal motor and transmission chambers and an external cavity. A traction motor is mounted inside the motor chamber and drives one or more vehicle wheels to thereby propel the vehicle. A gear train is mounted inside the transmission chamber and drivingly connects the traction motor to the vehicle wheels. An integrated power electronics (IPE) unit, which is operable to control the traction motor, includes an IPE outer housing with a housing chassis mounted inside the external cavity, and a main housing mounted on the housing chassis to define therebetween a power electronics (PE) chamber. Multiple integrated circuit (IC) PE modules are mounted inside the PE chamber.

The present disclosure relates generally to motor vehicle powertrains. More specifically, aspects of this disclosure relate to electric-drive vehicles and powertrains with a traction motor, transmission, and power inverter combined into an electric drive unit.

Current production motor vehicles, such as the modern-day automobile, are originally equipped with a powertrain that operates to propel the vehicle and power the vehicle's onboard electronics. In automotive applications, for example, the vehicle powertrain is generally typified by a prime mover that delivers driving torque through an automatic or manually shifted power transmission to the vehicle's final drive system (e.g., differential, axle shafts, road wheels, etc.). Automobiles have historically been powered by a reciprocating-piston type internal combustion engine (ICE) assembly due to its ready availability and relatively inexpensive cost, light weight, and efficiency. Such engines include compression-ignited (CI) diesel engines, spark-ignited (SI) gasoline engines, two, four, and six-stroke architectures, and rotary engines, as non-limiting examples. Hybrid electric and full electric (“electric-drive”) vehicles, on the other hand, utilize alternative power sources to propel the vehicle, such as an electric motor generator unit (MGU), and therefore minimize or eliminate reliance on a fossil-fuel based engine for tractive power.

A full electric vehicle (FEV)—colloquially identified as an “electric car”—is a type of electric-drive vehicle configuration that altogether removes the internal combustion engine and attendant peripheral components from the powertrain system, relying solely on electric traction motors for propulsion and for supporting accessory loads. The engine assembly, fuel supply system, and exhaust system of an ICE-based vehicle are replaced with a single or multiple traction motors, a traction battery pack, and battery cooling and charging electronics in an FEV. Hybrid vehicle powertrains, in contrast, employ multiple sources of tractive power to propel the vehicle, most commonly operating an internal combustion engine assembly in conjunction with a battery-powered or fuel-cell-powered electric motor. Since hybrid vehicles are able to derive their power from sources other than the engine, hybrid electric vehicle (HEV) engines may be turned off, in whole or in part, while the vehicle is propelled by the electric motor(s).

High-voltage (HV) electrical systems govern the transfer of electricity between each traction motor and a rechargeable traction battery pack (also referred to as “electric-vehicle battery” or “EVB”) that stores and supplies the requisite power for operating hybrid and full-electric powertrains. HV electric systems may employ a front-end DC-to-DC electric power converter that is electrically connected to the vehicle's traction battery pack(s) in order to increase the supply of voltage to a high-voltage main direct current (DC) bus and an electronic power inverter. A high-frequency bulk capacitor may be arranged across the positive and negative terminals of the main DC bus to provide electrical stability and store supplemental electric energy. Bulk capacitor size—in terms of total capacitance—may be selected based upon expected DC bus voltage range, peak current and ripple voltage when operating the inverter employing, for example, a six-step mode of operation. Operation and control of multi-phase electric motor/generator units, such as permanent magnet synchronous traction motors, may be accomplished by employing the inverter to transform DC electric power to alternating current (AC) power using pulse-width modulated control signals output from a resident vehicle controller.

Various multi-speed power transmission architectures have been developed for selectively transmitting rotational power from the vehicle's prime mover to the final drive system. An available type of power transmission is the electrically-variable electric drive unit (EDU) that contains one or more electric motor/generator units, epicyclic gear train elements, clutches, power electronics and, optionally, differential and axle components. The clutches govern engagement/disengagement of the gear train elements to provide for electrically-variable modes, fixed speed ratio modes, and electric-only (“battery power”) modes of operation. The electronic power inverter assembly is utilized to control operation of the EDU's motor/generator unit(s). Generally, the power inverter, DC-to-DC power converter, and other requisite power electronic modules are assembled remote from and subsequently mounted to the EDU. Assembly of the individual power electronic modules to the EDU is labor intensive and necessitates additional mounting hardware, electrical connectors, sealing gaskets, and dedicated housing containers to secure each module to the EDU. Furthermore, the EDU's power electronic modules are cooled by pipes and related plumbing to route coolant fluid into each module's discrete housing; additional packaging space is needed to accommodate the additional pipes and plumbing.

SUMMARY

Presented herein are electric drive unit assemblies with integrated power electronics (IPE), vehicle powertrains equipped with such EDU assemblies, methods for making and methods for operating such EDU assemblies, and electric-drive vehicles equipped with modular EDU assemblies with integrated power electronics and transaxles. By way of example, a modular EDU assembly includes an electric traction motor, a gearbox, an electric circuit, and a housing. The electric traction motor may be in the nature of a single or a pair of motor/generator units. For some applications, the gear box may comprise a planetary gear train, clutches, differential, and axle shafts. The electric circuit may be composed of an AC-DC power inverter module (PIM), a DC-DC converter and auxiliary power module (APM), an onboard charge module (OBCM), a high-power distribution module (HPDM), and other power electronic componentry. All power electronic modules are sealed within a singular, internally cooled IPE outer housing; the shared IPE housing seats within an IPE cavity in and fastens to the EDU outer housing.

A front-drive EDU assembly takes on a tall, narrow footprint with an AC rod connection to a composite oil reservoir cover that is located on top of the drive unit housing. The AC rod connector internally interfaces with a three-phase terminal assembly of the motor's stator; the oil cavity and bolted interface are cooled with oil. The AC rod connector externally interfaces with the 3-phase bus bar assembly; doing so moves the connection points to a location near the perimeter of a power electronic mounting flange. External to the drive unit housing, but internal to the power electronic flange, is a dry cavity that is sealed within the integrated power electronics shared housing assembly. The IPE assembly includes a power inverter module and other componentry related to usage of the front-drive EDU in battery electric vehicle (BEV) platforms. Additionally, the IPE assembly utilizes a DC connector that interfaces with a rechargeable electric storage system (RESS).

In contrast to front-drive EDU assemblies, a rear-drive EDU assembly takes on a low, wide footprint. Rear-drive EDU assemblies may incorporate a fixed AC rod connection to the housing. The AC rod connector internally interfaces with the 3-phase terminal assembly of the stator; an oil cavity and the bolted interface are cooled with oil. The AC rod connector externally interfaces with the 3-phase bus bar assembly of the power inverter module. The power inverter module has a sealing interface to the housing, situated in a dry cavity. Furthermore, the power inverter module has a DC connector that interfaces with the on-board RESS.

Strategic integration of the power electronics to the electric drive unit helps to achieve increased packaging efficiencies and weight savings. Vehicle packaging may be further optimized through calculated positioning of the electric drive unit and transaxle, as well as the consolidated arrangement of desired power electronic content. Sealing the power electronics in a single, unitary IPE housing, which is mounted directly to the EDU housing, enables maximum packaging compactness and a wide-bolt layout that ameliorates noise, vibration and harshness (NVH). Attendant benefits for at least some of the disclosed integrated power electronics designs include improved efficiencies in power transfer and the ability to cool the stator terminals with oil. Other attendant benefits may include reduced system complexity and minimized design and part costs by eliminating the peripheral electronic hardware and fluid plumbing for designs utilizing discrete housings for each power electronics module.

Aspects of this disclosure are directed to electric drive units with integrated power electronics. An EDU assembly is presented for driving a motor vehicle with multiple road wheels attached to the vehicle's body. The EDU assembly includes a rigid outer housing that mounts to the vehicle body. Defined inside the EDU outer housing are an internal motor chamber and an internal transmission chamber; an external cavity is defined on an exterior surface of the EDU outer housing. A single or multiple traction motors are mounted inside the EDU housing's internal motor chamber and operable to drive one or more of the road wheels to thereby propel the vehicle. A gear train, which is mounted inside the EDU housing's internal transmission chamber, drivingly connects the traction motor(s) to the vehicle's road wheels. Governing operation of the traction motor(s) is an IPE unit that is fabricated with a rigid IPE outer housing. The IPE outer housing includes a housing chassis mounted inside the EDU outer housing's external cavity, and a main housing mounted on the housing chassis to define therebetween a PE chamber. Multiple integrated circuit (IC) PE modules are mounted inside the PE chamber.

Additional aspects of this disclosure are directed to electric-drive vehicles and vehicle powertrains equipped with EDU assemblies having integrated power electronic modules. As used herein, the terms “vehicle” and “motor vehicle” may be used interchangeably and synonymously to include any relevant vehicle platform, such as passenger vehicles (REV, FEV, BEV, PHEV, etc.), commercial vehicles, industrial vehicles, tracked vehicles, off-road and all-terrain vehicles (ATV), motorcycles, farm equipment, watercraft, aircraft, etc. In an example, a motor vehicle includes a vehicle body with multiple road wheels and other standard original equipment. For hybrid configurations, an internal combustion engine is mounted inside an engine bay of the vehicle body and operates alone or in conjunction with a single or multiple traction motors to drive one or more of the road wheels to thereby propel the vehicle.

Continuing with the discussion of the above example, the motor vehicle also includes a modular EDU assembly with a rigid outer housing that is mounted to the vehicle body. The traction motor(s) is/are mounted inside an internal motor chamber of the EDU housing. A gear train, such as an electrically-variable transmission with a differential and mating axle half shafts, is mounted inside an internal transmission chamber of the EDU housing. This gear train drivingly connects the traction motor(s) to the vehicle's road wheels. A power electronics unit operable to govern operation of the traction motor is integrated into the EDU assembly. The IPE unit includes a rigid IPE outer housing with a housing chassis mounted inside the external cavity of the EDU outer housing, and a main housing mounted on the housing chassis to define therebetween a PE chamber. Three to five (or more) IC PE modules are mounted inside the PE chamber. These PE modules may include a DC-DC power converter module, an AC-DC power inverter module, an onboard charge module and, optionally, a high-power distribution module.

Additional aspects of this disclosure are directed to methods for making and methods for operating any of the disclosed electric drive unit assemblies, vehicle powertrains, and motor vehicles. In an example, a method is presented for assembling an EDU assembly for a motor vehicle. This representative method includes, in any order and in any combination with any of the above and below options and features: providing an EDU outer housing configured to mount to the vehicle body, the EDU outer housing defining therein an internal motor chamber and an internal transmission chamber and defining on an exterior surface thereof an external cavity; mounting a traction motor inside the internal motor chamber of the EDU housing, the traction motor being configured to drive one or more of the road wheels to thereby propel the motor vehicle; mounting a gear train inside the internal transmission chamber of the EDU housing, the gear train being configured to drivingly connect the traction motor to the one or more road wheels; providing an IPE unit operable to govern operation of the traction motor, the IPE unit including an IPE outer housing composed of a housing chassis and a main housing mounted on the housing chassis to define therebetween a power electronics (PE) chamber, and a plurality of integrated circuit PE modules mounted inside the PE chamber; and mounting the housing chassis inside the external cavity of the EDU outer housing.

For any of the disclosed EDUs, powertrains, vehicles and methods, the IPE outer housing may be a tripartite construction with a main case, a housing cover mounted on the main case, and the main case mounted on the housing chassis. The housing cover may include a high-voltage direct current (HVDC) electrical connector, and the main case may include a high-voltage alternating current electrical connector. Optionally, the main case may also include HVDC electrical connectors for an air conditioning control module (ACCM), a cabin heater control module (CHCM), and a storage heater control module (SHCM). The main case may include an integrated cooling manifold, a cooling inlet port that feeds coolant into the IPE outer housing, and a cooling exit port that exhausts coolant from the IPE outer housing. Optionally, three IC PE modules may be mounted between the main case and housing cover, and a fourth IC PE module may be mounted between the main case and the housing chassis. The IPE outer housing may have an IPE interface flange that projects from the main housing, and the EDU outer housing may have an EDU interface flange that projects from the external cavity; the IPE interface flange seals to the EDU interface flange along a single plane.

The above summary is not intended to represent every embodiment or every aspect of the present disclosure. Rather, the foregoing summary merely provides an exemplification of some of the novel concepts and features set forth herein. The above features and advantages, and other features and attendant advantages of this disclosure, will be readily apparent from the following detailed description of illustrated examples and representative modes for carrying out the present disclosure when taken in connection with the accompanying drawings and the appended claims. Moreover, this disclosure expressly includes any and all combinations and subcombinations of the elements and features presented above and below.

The present disclosure is amenable to various modifications and alternative forms, and some representative embodiments are shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the novel aspects of this disclosure are not limited to the particular forms illustrated in the above-enumerated drawings. Rather, the disclosure is to cover all modifications, equivalents, combinations, subcombinations, permutations, groupings, and alternatives falling within the scope of this disclosure as encompassed by the appended claims.

DETAILED DESCRIPTION

This disclosure is susceptible of embodiment in many different forms. Representative embodiments of the disclosure are shown in the drawings and will herein be described in detail with the understanding that these embodiments are provided as an exemplification of the disclosed principles, not limitations of the broad aspects of the disclosure. To that extent, elements and limitations that are described, for example, in the Abstract, Introduction, Summary, and Detailed Description sections, but not explicitly set forth in the claims, should not be incorporated into the claims, singly or collectively, by implication, inference or otherwise.

For purposes of the present detailed description, unless specifically disclaimed: the singular includes the plural and vice versa; the words “and” and “or” shall be both conjunctive and disjunctive; the words “any” and “all” shall both mean “any and all”; and the words “including,” “containing,” “comprising,” “having,” and the like, shall each mean “including without limitation.” Moreover, words of approximation, such as “about,” “almost,” “substantially,” “generally,” “approximately,” and the like, may each be used herein in the sense of “at, near, or nearly at,” or “within 0-5% of,” or “within acceptable manufacturing tolerances,” or any logical combination thereof, for example. Lastly, directional adjectives and adverbs, such as fore, aft, inboard, outboard, starboard, port, vertical, horizontal, upward, downward, front, back, left, right, etc., may be with respect to a motor vehicle, such as a forward driving direction of a motor vehicle when the vehicle is operatively oriented on a horizontal driving surface.

Referring now to the drawings, wherein like reference numbers refer to like features throughout the several views, there is shown inFIG. 1a schematic illustration of a representative automobile, which is designated generally at10and portrayed herein for purposes of discussion as a four-wheel drive (4WD) passenger vehicle with a hybrid-electric powertrain. In particular, the illustrated powertrain is generally composed of an internal combustion engine (ICE) assembly12and an electric drive unit (EDU) assembly14that operate, individually and in concert, to transmit tractive power to drive one or more road wheels16R,16F of the vehicle's final drive system. The illustrated automobile10—also referred to herein as “motor vehicle” or “vehicle” for short—is merely an exemplary application with which novel aspects and features of this disclosure can be practiced. In the same vein, implementation of the present concepts into a 4WD hybrid powertrain architecture should also be appreciated as an exemplary application of the novel concepts disclosed herein. As such, it will be understood that aspects and features of the present disclosure can be applied to other powertrain configurations and utilized for any logically relevant type of motor vehicle. Lastly, only select components have been shown and will be described in additional detail herein. Nevertheless, the vehicles, powertrains, and drive units discussed below can include numerous additional and alternative features, and other available peripheral components, e.g., for carrying out the various methods and functions of this disclosure.

The 4WD powertrain of automobile10is shown split into two discrete branches: a rear (first) powertrain PTR and a front (second) powertrain PTF. Rear powertrain PTR is represented herein by a restartable internal combustion engine12that is drivingly connected to a backend final drive system20by a multi-speed automatic power transmission18. The engine12transfers power, preferably by way of torque via an engine crankshaft13(“engine output member”), to an input side of the transmission18. The transmission18, in turn, is adapted to receive, selectively manipulate, and distribute tractive power from the engine12to the vehicle's final drive system20and thereby propel the vehicle10. The rear final drive system20ofFIG. 1is generally composed of a drive shaft22that drivingly connects the power transmission18to a rear limited-slip differential24; a pair of rear axle shafts26drivingly connect the differential24to a set of rear road wheels16R.

The ICE assembly12operates to propel the vehicle10independently of the EDU assembly14, e.g., in an “engine-only” operating mode, or in cooperation with the EDU assembly14, e.g., in a “motor-boost” operating mode. In the example depicted inFIG. 1, the ICE assembly12may be any available or hereafter developed engine, such as a compression-ignited diesel engine or a spark-ignited gasoline or flex-fuel engine, which is readily adapted to provide its available power output typically at a number of revolutions per minute (RPM). Although not explicitly portrayed inFIG. 1, it should be appreciated that the vehicle's driveline system may take on any available configuration, including front wheel drive (FWD) layouts, rear wheel drive (RWD) layouts, all-wheel drive (AWD) layouts, six-by-four (6×4) layouts, etc.

Power transmission18may use differential gearing19to achieve selectively variable torque and speed ratios between the transmission's input shaft15(“transmission input member”) and output shaft17(“transmission output member”), e.g., while sending all or a fraction of its power through the variable elements. One form of differential gearing is the epicyclic planetary gear arrangement. Planetary gearing offers the advantage of compactness and different torque and speed ratios among all members of the planetary gearing subset. Traditionally, hydraulically actuated torque establishing devices, such as clutches and brakes (the term “clutch” used to reference both clutches and brakes), are selectively engageable to activate the aforementioned gear elements for establishing desired forward and reverse speed ratios between the transmission's input and output shafts. While envisioned as an 8-speed automatic transmission, the power transmission18may optionally take on other suitable configurations, including Continuously Variable Transmission (CVT) architectures, automated-manual transmissions, etc.

Front powertrain PTF ofFIG. 1is represented herein by an electric drive unit assembly14with an integrated power electronics (IPE) unit30that drives a set of front road wheels16F through a respective pair of front axle shafts32. EDU assembly14may be generally typified by a solitary electric traction motor36having a single-speed reduction gearbox38, e.g., with two gear reductions, and a transverse-split, bevel-type differential40. Modulation of the EDU assembly14is controlled by an in-vehicle electronic control unit (ECU)34for delivering motive power to the ground-engaging road wheels16F. Compact arrangement of the contents of the EDU assembly14permits the use of a drive unit in substitution for a conventional motor assembly with torque-delivering differential and axle system. In accord with the powertrain architecture ofFIG. 1, the front powertrain PTF delivers motive power to front road wheels16F while the rear powertrain PTR delivers motive power to rear wheels16R. However, alternative powertrain arrangements may employ the EDU assembly14to drive the rear wheels16R, employ the EDU assembly14to drive the front and/or rear wheels16F,16R while altogether eliminating the ICE assembly12, or employ the ICE assembly12and EDU assembly14to cooperatively drive the front wheels16F, rear wheels16R, or both.

With continuing reference toFIG. 1, the electric traction motor36may take on any motor configuration of suitable size and power to propel vehicle10, including a permanent magnet synchronous motor/generator unit. Electric power is provided to the traction motor36through electrical conductors or cables that pass through a protective casing in suitable sealing and insulating feedthroughs (not illustrated). Conversely, electric power may be provided from the traction motor36to an onboard traction battery pack42, e.g., through regenerative braking. While shown as a hybrid-electric architecture with one traction motor for independently driving two vehicle wheels16F, the vehicle10may employ other powertrain configurations with multiple traction motors, any of which may be adapted for a full-electric vehicle (FEV), battery electric vehicle (BEV), plug-in hybrid electric vehicle (PHEV), fuel-cell hybrid electric vehicle (FCEV), etc.

As indicated above, ECU34is constructed and programmed to govern, among other things, operation of the engine12, drive unit14, transmission18, and traction battery pack42. Control module, module, controller, control unit, electronic control unit, processor, and any permutations thereof, may be used interchangeably and synonymously to mean any one or various combinations of one or more of logic circuits, combinational logic circuit(s), Application Specific Integrated Circuit(s) (ASIC), electronic circuit(s), central processing unit(s) (e.g., microprocessor(s)), input/output circuit(s) and devices, appropriate signal conditioning and buffer circuitry, and other components to provide the described functionality, etc. Associated memory and storage (e.g., read only, programmable read only, random access, hard drive, tangible, etc.)), whether resident, remote or a combination of both, store processor-executable software and/or firmware programs or routines.

Software, firmware, programs, instructions, routines, code, algorithms, and similar terms may be used interchangeably and synonymously to mean any processor-executable instruction sets, including calibrations and look-up tables. The ECU34may be designed with a set of control routines executed to provide desired functions. Control routines are executed, such as by a central processing unit, and are operable to monitor inputs from sensing devices and other networked control modules, and execute control and diagnostic routines to govern operation of devices and actuators. Such inputs may include vehicle speed and acceleration data, speed limit data, traffic light status and location data, road gradient data, stop sign location data, traffic flow data, geospatial data, road and lane-level data, vehicle dynamics data, sensor data, etc. Routines may be executed in real-time, continuously, systematically, sporadically and/or at regular intervals, for example, each 100 microseconds, 3.125, 6.25, 12.5, 25 and 100 milliseconds, etc., during vehicle use. Alternatively, routines may be executed in response to occurrence of an event during operation of the vehicle10.

Referring now toFIGS. 2 and 3, there is shown a representative EDU assembly114for propelling an electric-drive motor vehicle, such as hybrid electric vehicle10ofFIG. 1. The EDU assembly114includes a multi-section, protective outer housing144(“EDU outer housing”) onto which is mounted an IPE unit130. Integral fastener tabs150receive mounting lugs (not shown) that allow the EDU's outer housing144to be suspended within an engine bay of the vehicle body, e.g., adjacent ICE assembly12ofFIG. 1. The EDU outer housing144ofFIGS. 2 and 3may be cast or machined from a rigid metallic or polymeric material with a cover plate148that secures, e.g., via bolts152, to a main casing146. Securely fastening the cover plate148to the main casing146creates an internal motor chamber141that is separated by a radial support wall145from an internal transmission chamber143, which are best seen inFIG. 1. A traction motor, such as electric traction motor36ofFIG. 1, is mounted inside the EDU housing's motor chamber141, whereas a gear train, such as gearbox38and differential40, is mounted inside the transmission chamber141. It should be appreciated that the specific shape and size of the illustrated outer housing144may be specific to the intended application of the EDU assembly114and is, thus, non-limiting in nature.

For at least some embodiments, the motor chamber141may be fluidly sealed as a wet chamber, i.e., for receiving transmission oil, and the transmission chamber141may be fluidly sealed as a dry chamber, i.e., storing air. Nevertheless, the traction motor(s) stowed inside the motor chamber141is/are drivingly connected, e.g., by an appropriate motor output shaft, to the gear elements of the gear train stowed inside the transmission chamber141. Electric drive unit assembly114may be configured as a single-speed or a multi-speed power transmission device (e.g., a two-speed drive module may be coupled to the housing144as a bolt-on modification to provide multi-speed functionality). A pair of drive unit output shafts, namely port and starboard-side output shafts154and156, respectively, are adapted to spline to corresponding axle shafts, such as front axle shafts32ofFIG. 1, for driving engagement with at least two of the vehicle's road wheels.

In accord with the illustrated example, the EDU's outer housing144includes a bowl-shaped external cavity151that securely seats therein the IPE unit130. This IPE unit130exchanges data with, and receives command signals from, the ECU34to govern operation of the traction motor or motors contained within the EDU housing144. An upper “crown” section of the main casing146is formed with a basin158that is delineated by four interconnected sidewalls adjoining a base to define the external cavity151. A series of structural reinforcing ribs160is spaced around the outer perimeter of this basin158, helping to buttress the IPE unit130while concomitantly reducing gross weight of the combined assembly. The basin158and ribs160ofFIG. 2are integrally formed with the main casing146as a unitary, single-piece structure. The interior of the basin158may be shaped complementary to an IPE outer housing162to ensure a flush fit of the IPE unit130within the external cavity151.

Integrated power electronics unit130includes a multi-section, protective outer housing162(“IPE outer housing”) that mounts on top of the EDU's outer housing144. The IPE outer housing162may be cast or machined from a rigid metallic or polymeric material with a bottom-most housing chassis164that provides subjacent support for a main housing, which is represented inFIG. 2by an intermediate main case166and a top-most housing cover168. As shown, the housing chassis164nests inside the basin158and sits generally flush against the outboard facing surfaces of the external cavity151of the EDU outer housing144. The housing cover168is mechanically attached, e.g., via self-aligning screws170, on an upper end of the main case166. Sandwiched between the housing cover168and chassis164, the main case166is rigidly secured, e.g., via bolts172, on the housing chassis164. The main case166is fabricated with two mounting interfaces: an integral bottom flange161with two sets of bolt holes, one for securing to the housing chassis164and one for securing to the EDU outer housing144; and an integral top flange163with a set of fastener holes for mounting the housing cover168. Both flanges161and163extend in a continuous fashion around the perimeter of the main case166. While shown as a tripartite construction, the IPE's outer housing162may comprise greater or fewer than three sections. Since the IPE unit130is mounted into the EDU basin158, for example, the housing chassis164may be eliminated. In some applications, including rear-wheel drive powertrain architectures, the housing chassis164is added to close out the assembly.

FIG. 4presents an exploded illustration of the representative IPE unit130ofFIGS. 2 and 3with the housing chassis164removed for simplicity and ease of reference. Housing cover168is fabricated as a single-piece, rigid structure with an integral flange167that extends continuously around the outer perimeter of the cover168and includes fastener holes for fastening to the top flange163of the main case166via screws170. Assembled into the housing cover168is a high-voltage direct current (HVDC) electrical connector174for electrically connecting the IPE module130to a vehicle battery, such as onboard traction battery pack42ofFIG. 1, via a corresponding cable harness. Spaced from the HVDC electrical connector174is a connector junction176that provides an access port for electrically connecting the IPE module130, via a corresponding cable harness, to a powertrain control module (PCM), which may be embodied as a discrete controller or incorporated into ECU34ofFIG. 1. The EDU and IPE outer housings144and162may be fabricated from distinct materials or the same material, including A360 stainless steel and/or ADC2 or ADC3 aluminum alloys.

With continuing reference toFIG. 4, the IPE housing's main case166is fabricated as a single-piece, rigid structure that functions as the primary platform for supporting and electrically interconnecting the IPE unit's numerous power electronic (PE) modules. In the illustrated example, multiple electrical junctions are assembled into the main case166, including: a high-voltage alternating current (HVAC) electrical connector178; an air conditioning control module (ACCM) HVDC electrical connector180; a cabin heater control module (CHCM) HVDC electrical connector182; and a storage heater control module (SHCM) HVDC electrical connector184. It is envisioned that the main case166may be equipped with greater or fewer electrical connectors than those enumerated above. For instance, a dedicated cable harness (not shown) may be coupled to a coolant pump HVAC electrical connector185to deliver alternating current energy to a fluid pump (not visible in the views provided). A cooling cover186, which is seated on a top surface of the main case166, provides subjacent support for a busbar assembly module188, a DSC cooling jacket190, and a high-voltage distribution panel192. While shown with a generally square-polyhedral shape, the main case166may take on alternative shapes and sizes without departing from the intended scope of this disclosure.

In addition to the features mentioned above, the integrated power electronics unit130is furnished with an internal cooling system for regulating the operating temperatures of the various PE modules contained within the IPE outer housing162. The main case166is fabricated with an integral cooling manifold194that is fluidly connected to a cooling inlet port195and a cooling exit port197. Coolant is fed from a suitable coolant sump into the IPE outer housing162through the cooling inlet port195, and coolant is exhausted from the IPE outer housing162through the cooling exit port197. Coolant fluid, which may be in the nature of ethylene glycol or deionized water or a mixture of the two, is delivered to and circulated through the IPE unit130inside the main case166to cool the various IPE components. By utilizing a single internal cooling system to cool the PE modules, the IPE unit130design helps to eliminate superfluous coolant hoses, conduits, seals, etc., that would otherwise be necessitated by systems that employ a discrete housing for each PE module.

Multiple integrated circuit (IC) based PE modules are mounted inside an internal PE chamber within the IPE's outer housing162. In accord with the representative architecture illustrated inFIG. 4, an onboard charge module (OBCM)171is mounted to an underside of the main case166, between the housing chassis164and cover168. This OBCM171is adapted to connect to an electric vehicle charging station (EVCS) or other appropriate electric vehicle supply equipment (EVSE) for recharging the vehicle's onboard traction battery pack, e.g., using a wall-mounted charge cable or a household outlet. An auxiliary power module (APM) with an HV-12V DC/DC power converter module173is mounted to a topside of the main case166underneath the housing cover168. The APM173is operable as a DC-to-DC converter that modulates power from the RESS or battery pack to a standard vehicle voltage, such as a nominal voltage for 12V starting, lighting, and ignition (SLI) battery and 12V vehicle accessory loads.

Also mounted onto the main case166underneath the housing cover168are an IPE control board175with a low-voltage input/output (LVIO) peripheral card connector177and a gate board179. The IPE control board175may carry an AC-DC power inverter module (PIM), a DC-DC step-up module and, optionally, a high-power distribution module (HPDM). The PIM is an element of the PE control subsystem that regulates transmission of electrical energy to and from the traction motor(s). The step-up module may be used to ensure the motor control voltage for the traction motor meets the input DC bus voltage. The HPDM may be embodied as an electrical junction box that distributes high-voltage power from the RESS to a predesignated assortment of high-voltage components. Recognizably, the PE modules may be comprised of fewer or greater or different modules than that which are shown inFIG. 4.

To help simplify and expedite the assembly process for the EDU assembly114, the entire IPE unit130, including all of the requisite PE modules packaged within the IPE outer housing162, is operatively mounted in unison onto the EDU's outer housing144. As shown inFIG. 5, the IPE outer housing162is mechanically attached along on a single plane—bolted down over a series of coplanar interfaces—to the EDU outer housing144. The main case166of the IPE's outer housing162is fabricated with a planar IPE interface flange161that projects generally orthogonally from a lower end of the main case166. An uppermost end of the EDU's outer housing144is fabricated with a planar EDU interface flange147that projects generally orthogonally from the exterior surface of the housing144, extending continuously around an upper extent of the external cavity151. The IPE's interface flange161bolts on and seals to the EDU's interface flange147along a single plane (e.g., a plane orthogonal to a vertical axis A1extending through the center of the EDU's main casing146).

While shown extending in a continuous manner around the outer perimeters of the basin158and main case166, the EDU and IPE interface flanges147and161may consist of discontinuous flanges or discrete tabs. A first gusset149extends continuously around the perimeter of the external cavity151, and sandwiches between the interface flanges147,161. A second gusset153extends continuously around the perimeter of the main case166and housing chassis164, and sandwiches between the IPE's interface flange161and complementary interface (not visible in the views provided) of the housing chassis164.FIGS. 7 and 8illustrate alternative EDU assembly configurations214and314, respectively, with a corresponding IPE unit230and330with an IPE outer housing262and362that is mechanically attached along on a single plane to the EDU outer housing244and344. By way of comparison to the top-mount configuration ofFIGS. 2 and 3, the EDU assembly214ofFIG. 7is a side-mount configuration with a singular mounting plane that is parallel to the vertical axis extending through the center of the EDU's main casing246. Contrastingly, the EDU assembly314ofFIG. 8is a slant-mount configuration with a singular mounting plane that is oblique to the vertical axis extending through the center of the EDU's main casing346.

To accommodate for stack tolerances between the IPE unit's mounting plane and the traction motor/motors stored inside the EDU's protective outer housing, the IPE unit employs a compliant AC connection interface for electrically coupling to the AC busbar. With reference toFIG. 5, for example, the EDU assembly114is provided with an alternating current (AC) busbar191that is mounted inside the EDU outer housing144. Likewise, IPE unit130is assembled with a flexible electrical busbar193that is mounted inside the PE chamber and attached to the AC busbar191, e.g., via busbar bolt199. The housing chassis164or main case166is fashioned with a busbar port155through which is received the AC busbar191. An elongated channel157receives therethrough the busbar bolt199. The IPE unit130further includes an AC busbar cap159mounted to the main case166closes off a top end of this elongated channel157.

The EDU assembly114with fully-integrated IPE unit130may further provide the ability to decouple the structural modes of the system's power electronics, e.g., to mitigate noise, vibration and harshness (NVH), by adjusting the height of the single sealing/mounting plane relative to the center of gravity (CG) of the IPE unit130. In general, the CG height may be set equal to (collinear with) the mounting plane. CG height “tuneability” allows a designer to decouple the PE structural modes by adjusting the height of the mounting plane. As shown, the CG of the IPE unit130is derived through system modeling, and the mounting plane is set substantially equal to the position of the CG in a vertical stack.