Patent ID: 12213291

In the drawings, reference numbers may be reused to identify similar and/or identical elements.

DETAILED DESCRIPTION

A power control system for an electric vehicle (or other vehicular or non-vehicular application) includes a power inverter that transfers power between a battery system and a load (such as a electric machine). A high level of functional integration of components in the power inverter reduces mass, reduces volume, and/or improves performance. For example, a structural housing of the power inverter is formed using polymer composite. In some examples, the polymer composite encapsulates at least some of the components of the power control system and/or provides a mounting surface and/or cooling for components of the power inverter.

The structural housing further utilizes conductive materials such as conductive layers, conductive coatings and/or conductive foam where needed to provide EMI shielding, EMI absorption, and/or ground attachment points. In some examples, an inner surface of the housing and a facing surface of a bulk capacitor housing are used create cooling channels to perform double-sided cooling of the switch module including the power switches.

In some examples, the polymer composite that is used has low moisture absorption (e.g., moisture absorption less than 0.5% by mass). In some examples, the polymer composite has a low cure temperature (e.g., cure temperature less than 120° C.). In some examples, the polymer composite has a low molding pressure (e.g., molding pressure less than 20 MPa−) and high flowability during molding (e.g., flow length greater than 80 cm in ASTM D3123 Spiral Flow test). Use of encapsulation in polymer composite allows integration and/or elimination of components such as fasteners, housings, electrical isolators, clips, etc.

In some examples, the housing for the power inverter comprises greater than 50% polymer composite by volume. In some examples, the polymer is mixed with fillers inorganic (ceramic or mineral) fillers. In some examples, due to their higher density, the inorganic fillers may comprise up to 85% by weight of the polymer composite. The polymer may also be mixed with structural fibers such as glass fibers, carbon fibers, aramid fibers, etc.

In some examples, the housing includes one or more integrated cooling cavities for cooling the power inverter. In some examples, the housing includes a conductive coating and/or conductive layer on an exterior surface thereof to perform EMI shielding. In some examples, the housing encapsulates at least one electronic component of the power control system and has at least one other electronic component mounted on a surface thereof. In some examples, the polymer composite has a coefficient of thermal expansion between 10-30 ppm/° C. and dielectric strength>20 kV/mm.

In some examples, the power control system includes an encapsulated bulk capacitor and power inverter. In some examples, the encapsulated capacitor and power inverter include one or more cooling cavities that provide cooling to at least two surfaces of a switch module including a plurality of power switches. In some examples, an outer surface of the housing for the bulk capacitor forms at least 1 cooling cavity. In some examples, surfaces of the cooling cavity that are exposed to moisture are coated with a low moisture permeability coating (e.g., metallic or ceramic) to mitigate absorption of moisture. In some examples, the polymer composite increases capacitance of the system and thereby reduces capacitance that is needed from the dedicated bulk capacitor.

In some examples, a controller board and/or a gate driver board are encapsulated by polymer composite on a least 1 side thereof.

In other examples, a metallic sheet/bar/coating is attached to an outer surface of the inverter housing to act as an EMI shield and ground conductor. In other examples, a conductive coating is formed on an outside surface of the polymer composite housing and covers at least 80% or 90% of the exterior surface of the polymer composite housing. The conductive coating or layer is in electrical contact with ground or another reference potential to increase coverage of the EMI shield.

In some examples, the housing includes conductive foam arranged therein to absorb EMI signals. In some examples, the housing includes vascular channels within the polymer composite to reduce polymer composite mass or to provide cooling to electrical components such as the busbars.

Referring now toFIGS.1-3, various levels of integration of a power control system are shown. InFIG.1, a power control system100includes a power inverter102connected to first and second terminals of a battery system112. The battery system112includes one or more battery cells, modules and/or packs that are connected in series or parallel. The first and second terminals of the battery system112are connected to a switch module120.

The switch module120includes 2P power switches where P is the number of phases. In this example, the electric machine is a three-phase electric machine (P=3) and the switch module120includes power switches T1, T2, T3, T4, T5, and T6. The power switches T1, T2and T3are connected to the first terminal of the battery system112and a first terminal of the capacitor C1. Second terminals of the power switches T1, T2and T3are connected to first, second and third phases of the electric machine124, respectively, and to first terminals of the power switches T4, T5and T6, respectively. Second terminals of the power switches T4, T5and T6are connected to the second terminal of the battery system112and the second terminal of the capacitor C1.

A gate driver126generates control signals for power switches T1, T2, T3, T4, T5, and T6. The gate driver126communicates with a controller130and a current sensor135. The gate driver126is configured to generate control signals to open and close the power switches T1, T2, T3, T4, T5, and T6as needed. The current sensor135senses current flowing through the AC busbars to the electric machine124. The gate driver126controls the power switches T1, T2, T3, T4, T5, and T6in response to sensed current. The controller130is configured to control the gate driver126in response commands from a vehicle bus.

The power control systems inFIGS.1to3have increasing levels of packaging integration. InFIG.1, a typical level of integration is shown. The power switch pairs T1and T2, T3and T4, and T5and T6are separately encapsulated in polymer composite136. Likewise, the capacitor C1is separately encapsulated in polymer composite and the current sensor135is separately encapsulated in polymer composite136.

InFIG.2, an increasing level of packing integration is used according to the present disclosure. In this example, the power switches T1, T2, T3, T4, T5, and T6, the gate driver126and/or the current sensor135are encapsulated together in polymer composite136. However different combinations of the components can be encapsulated together. In other examples, the power switches T1, T2, T3, T4, T5, and T6and the current sensor135are encapsulated together in polymer composite136or the power switches T1, T2, T3, T4, T5, and T6and the gate driver126are encapsulated in polymer composite.

InFIG.3, the power switches T1, T2, T3, T4, T5, and T6, the gate driver126, the current sensor135and the controller130are encapsulated together in polymer composite. As can be appreciated, encapsulating higher numbers of components reduces parts count.

Referring now toFIGS.4to6, an example of a power control system200is shown. InFIG.4, the power control system200includes a housing202made at least partially of polymer composite. In some examples, the housing202includes structural fibers embedded in polymer composite for additional strength. The housing202includes a first housing portion202A (FIG.5) and a second housing portion202B that are connected to form the housing202and to enclose the power inverter and related components. In some examples, flanges203extend from sides of the first housing portion202A and the second housing portion202B and include bores to receive fasteners.

The power control system200includes AC busbars204connecting the power switches to the electric machine124. The second housing portion202B includes slots206that are molded into an inner surface of the second housing portion202B. The AC busbars204are mounted in the slots206. The power control system200includes a current sensor208to sense current flowing through the AC busbars204.

A bulk capacitor assembly210includes a bulk capacitor211and DC busbars214and216that are separately embedded in polymer composite. The additional polymer composite located between the DC busbars214and216and the bulk capacitor211increases the capacitance of the bulk capacitor211, which may reduce the size of the bulk capacitor211.

The bulk capacitor assembly210further includes a first cooling cavity222formed on a lower, outer portion of the bulk capacitor assembly210. Cooling fins223are arranged in the cooling cavity222and are in thermal contact with a first or lower surface of a switch module225. The switch module225is arranged between a first or inner surface of the second housing portion202B and the first surface of the bulk capacitor assembly210.

The inner surface of the second housing portion202B defines a second cooling cavity224arranged adjacent to and in thermal contact with the switch module225. Cooling fins227are arranged in the cooling cavity224. Cooling fluid is supplied via a cooling cavity222through internal passages (not shown) in the housing202that are in fluid communication with the cooling cavities222and224.

A shield226is embedded in the second housing portion202B between the switch module225and an outer surface of the second housing portion202B to provide shielding to reduce electromagnetic interference (EMI). In some examples, a controller228is also embedded in the second housing portion202B between the shield226and the outer surface of the second housing portion202B.

InFIGS.4and5, shields234are formed over the first housing portion202A and the second housing portion202B. In some examples, the shields234include flanges262and bores264that align with some or all of the bores formed in the flanges203of the housing202. The shield234include openings250arranged in locations where the cooling conduit220connects to the housing202and/or where connectors254to a controller board and/or a gate driver board are arranged. The shields234are grounded to chassis or another reference potential.

InFIGS.4and6, the slots206are shown in further detail. The AC busbars204are arranged and mounted in the slots206. The cooling cavity224is shown to include a plurality of the cooling fins227associated with each of the electric machine phases. Alternately, the cooling fins can extend the length of the cooling cavity224.

InFIGS.5and6, the housing202includes vascular channels213. InFIG.5, the vascular channels213(shown in dotted lines). The vascular channels213can be formed by encapsulating deflagratable material in predetermined patterns (or preforms) such as channels in the polymer composite. After encapsulation, the deflagratable material is ignited. Deflagration converts solid into gas. The gas escapes from the housing leaving cavities in the polymer composite in the shape of the predetermined patterns or preforms. In some examples, the deflagratable material has a shape corresponding to the predetermined patterns. The deflagratable material is attached to a solid support during encapsulation. Other suitable sacrificial materials could alternatively be used for forming the channels, including soluble or decomposable materials.

In some examples, the vascular channels213are arranged adjacent to the slots206and/or adjacent to the AC busbars or other components to allow cooling of the AC busbars. In other examples, the vascular channels213are arranged in other locations such as the housing of the bulk capacitor assembly. Cooling the busbars allows the size of the busbars to be reduced. In other words, lower temperatures correspond to lower resistance due to removal of heat by the vascular channels213.

Additional details regarding vascular channels can be found in commonly assigned U.S. Pat. No. 10,923,827, issued on Feb. 16, 2021 and entitled “Vascular Cooled Capacitor Assembly and Method”, U.S. Pat. No. 11,147,193, issued on Oct. 12, 2021 and entitled “Vascular Cooling System for Electrical Conductors”; US Patent Publ. No. 2019/0357386, published on Nov. 21, 2019 and entitled “Vascular Polymer Composite IC Assembly”, and US Patent Publ. No. 2022/0130735, published on Apr. 28, 2022 and entitled “Package for Power Semiconductor Device and Method of Manufacturing Same”, which are hereby incorporated by reference in their entirety.

Referring now toFIGS.7to9B, additional details of a power inverter, coolant housing and capacitor system300is shown. InFIG.7, the power inverter, coolant housing and capacitor system300is encapsulated in polymer composite310. Each phase of the power inverter includes first and second DC terminals314-1and314-2and an AC terminal316extending from the polymer composite310. Gate control pins320are connected from a gate control board (not shown inFIGS.7,8and9A) to a switch module342including a plurality of power switches. Alternately, the gate control board is integrated as well as shown inFIG.9B.

A cooling conduit326supplies cooling fluid to cooling cavities formed in the polymer composite310. InFIG.8, DC busbars330and332extend around sides of a bulk capacitor340. A cooling cavity344(FIG.9) (formed in the polymer composite310) and cooling fins346are arranged on a top surface of the switch module342. A cooling cavity348(formed in the polymer composite310) and cooling fins349are arranged on a bottom surface of the switch module342. InFIG.9B, a gate control board360and the gate control pins362are also integrated in the polymer composite310.

Referring now toFIG.10, a power control system600is shown to include a housing640including a conductive coating641applied to an outer surface of a polymer composite642. In some examples, the conductive coating641increases reflectance of EMI signals. In some examples, the conductive coating641is formed by electroplating, electroless coating, cold spray and/or other coating techniques. The polymer composite642may be molded in a predetermined pattern to define a shape of the outer and inner surfaces, cavities, and/or other attachment features designed to receive or house components of the power control system.

The power control system600further includes a bulk capacitor assembly610arranged in the housing640. The bulk capacitor assembly610includes a bulk capacitor616and DC busbars612and614that are encased in polymer composite615. A switch module620is arranged between the bulk capacitor assembly610and the polymer composite642. The switch module620is connected to AC busbars618that are connected to the phases of the electric machine124, gate drive pins630connected to the gate driver board650, and DC busbars612and614. Cooling cavities can be arranged on opposite surfaces of the switch module620.

Conductive foam646is arranged on an inner surface of the polymer composite642to absorb EMI. In some examples, the conductive foam646is thicker than the conductive coating641. The conductive foam646extends between an outer surface of the gate driver board650and the polymer composite642and/or between the gate driver board650and the bulk capacitor assembly610to act as an absorbing material. In some examples, the conductive foam646has an “E”-shaped cross-section. In some examples, the conductive foam646and the conductive coating641are connected to ground. While the conductive foam646primarily acts as an absorbing layer and the conductive coating641primarily acts as a reflecting layer, both provide reflection and absorption functionality.

A cavity652is formed inside of the outer housing640to receive the components. A controller board654is arranged in the cavity652adjacent to a shield660. The shield660is arranged between the controller654and/or the AC busbars618and between the controller654and the bulk capacitor assembly610. In some examples, the shield660is “L”-shaped. In some examples, a spacer662supports the shield660in position above the AC busbars618and below the controller654.

The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

In the figures, the direction of an arrow, as indicated by the arrowhead, generally demonstrates the flow of information (such as data or instructions) that is of interest to the illustration. For example, when element A and element B exchange a variety of information but information transmitted from element A to element B is relevant to the illustration, the arrow may point from element A to element B. This unidirectional arrow does not imply that no other information is transmitted from element B to element A. Further, for information sent from element A to element B, element B may send requests for, or receipt acknowledgements of, the information to element A.

In this application, including the definitions below, the term “module” or the term “controller” may be replaced with the term “circuit.” The term “module” may refer to, be part of, or include: an Application Specific Integrated Circuit (ASIC); a digital, analog, or mixed analog/digital discrete circuit; a digital, analog, or mixed analog/digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip.

The module may include one or more interface circuits. In some examples, the interface circuits may include wired or wireless interfaces that are connected to a local area network (LAN), the Internet, a wide area network (WAN), or combinations thereof. The functionality of any given module of the present disclosure may be distributed among multiple modules that are connected via interface circuits. For example, multiple modules may allow load balancing. In a further example, a server (also known as remote, or cloud) module may accomplish some functionality on behalf of a client module.

The term code, as used above, may include software, firmware, and/or microcode, and may refer to programs, routines, functions, classes, data structures, and/or objects. The term shared processor circuit encompasses a single processor circuit that executes some or all code from multiple modules. The term group processor circuit encompasses a processor circuit that, in combination with additional processor circuits, executes some or all code from one or more modules. References to multiple processor circuits encompass multiple processor circuits on discrete dies, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or a combination of the above. The term shared memory circuit encompasses a single memory circuit that stores some or all code from multiple modules. The term group memory circuit encompasses a memory circuit that, in combination with additional memories, stores some or all code from one or more modules.

The term memory circuit is a subset of the term computer-readable medium. The term computer-readable medium, as used herein, does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave); the term computer-readable medium may therefore be considered tangible and non-transitory. Non-limiting examples of a non-transitory, tangible computer-readable medium are nonvolatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc).

The apparatuses and methods described in this application may be partially or fully implemented by a special purpose computer created by configuring a general purpose computer to execute one or more particular functions embodied in computer programs. The functional blocks, flowchart components, and other elements described above serve as software specifications, which can be translated into the computer programs by the routine work of a skilled technician or programmer.

The computer programs include processor-executable instructions that are stored on at least one non-transitory, tangible computer-readable medium. The computer programs may also include or rely on stored data. The computer programs may encompass a basic input/output system (BIOS) that interacts with hardware of the special purpose computer, device drivers that interact with particular devices of the special purpose computer, one or more operating systems, user applications, background services, background applications, etc.

The computer programs may include: (i) descriptive text to be parsed, such as HTML (hypertext markup language), XML (extensible markup language), or JSON (JavaScript Object Notation) (ii) assembly code, (iii) object code generated from source code by a compiler, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. As examples only, source code may be written using syntax from languages including C, C++, C#, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, Javascript®, HTML5 (Hypertext Markup Language 5th revision), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, Visual Basic®, Lua, MATLAB, SIMULINK, and Python®.