Patent Description:
Inductors are important components in power electronics circuits. A variety of systems are used to create efficient thermal management in order to meet inductance requirements. The inductor generally includes a core and a wire winding wrapped or coiled around the core. The inductor is generally positioned within a metal housing. The wire winding needs to be spaced apart from the metal housing, the space between the winding and the metal housing is typically filled with potting material. The core material, potting material, and wire insulations for the windings generally have temperature limits. These temperature limits and other thermal requirements require efficient heat transfer from the heat-generating components (the core and wire winding), and/or a coolant used (which can sometimes be at high temperature, e.g. <NUM>-<NUM>), to a heat sink (e.g. a cold plate). Generally, heat is transferred to the heat sink using the potting material which generates large gradient between the heat generating components and heat sink due to lower thermal conductivity of the potting material.

<CIT> discloses a method and apparatus of cooling magnetic circuit elements.

The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved systems and methods for thermal management in inductors. This disclosure provides a solution for this need.

An inductor assembly having a thermal management includes an inductor, a housing in thermal communication with the inductor, the housing defining a wall, and a conductor within a groove in the wall configured to transfer heat through the wall as defined in claim <NUM>.

The conductor has a greater heat transfer rate than the wall and is positioned within a groove and/or an aperture formed in the wall. The conductor is configured to transfer heat through the wall more efficiently than if the conductor were not present.

The conductor can be a heat pipe. The wall of the housing includes an outer wall and an inner wall. At least one of the outer wall or the inner wall can define an inner surface. The inductor can include a toroidal core and a winding coiled around the toroidal core. The housing can include at least one of a tin or nickel plating.

In certain embodiments, the inner surface includes the groove defined therein. The groove can be helical relative to a central axis of the housing. The conductor can be soldered within the groove to the inner surface of the housing. The conductor can be one of a plurality of conductors. Each of the plurality of conductors can be positioned in end-to-end abutment within the groove.

In certain embodiments, at least one of the outer wall or the inner wall may further include an aperture, wherein the aperture is an axially extending aperture. The conductor can be positioned within the axially extending aperture. A longitudinal axis of the conductor can be aligned with a longitudinal axis of the axially extending aperture. The axially extending aperture can be aligned with a central axis of the housing. The axially extending aperture can be one of a plurality of axially extending apertures defined about a circumference of the outer wall. The conductor can be one of a plurality of conductors. Each of the plurality of conductors can be positioned within a respective one of the axially extending apertures. The axially extending apertures can be equally spaced apart around the circumference of the outer wall.

In accordance with another aspect, a method of manufacturing an inductor assembly having a thermal management system includes forming a housing by additive manufacturing. The housing defines a wall having at least one groove defined therein. The method includes positioning a conductor in at least one of the groove and the aperture. The conductor has a greater heat transfer rate than the wall. The method includes positioning an inductor into thermal communication with the housing.

Forming the housing can include forming the wall having an outer wall and an inner wall. At least one of the outer wall or the inner wall can define an inner surface.

In certain embodiments, forming the housing includes forming the groove within the inner surface. Forming the groove can include forming the groove with a helical shape relative to a central axis of the housing. In certain embodiments, forming the housing includes forming the aperture in at least one of the outer wall or the inner wall, wherein the aperture is an axially extending aperture. Forming the axially extending aperture can include forming a plurality of axially extending apertures about a circumference of the outer wall. The axially extending apertures can be equally spaced apart around the circumference of the outer wall. The method can include coiling a winding around the inductor.

Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an embodiment of a system in accordance with the disclosure is shown in <FIG> and is designated generally by reference character <NUM>. Other embodiments of systems in accordance with the disclosure, or aspects thereof, are shown in <FIG> and described below. The systems and methods described herein provide for a thermal management system for an inductor assembly with improved thermal distribution across the inductor housing.

As shown in <FIG>, a thermal management system <NUM> includes a toroidal inductor <NUM>, a toroidal housing <NUM> around the toroidal inductor <NUM>. The toroidal housing <NUM> is defined by an outer wall <NUM> and an inner wall <NUM>. The housing <NUM> includes a top wall or lid <NUM>. The toroidal inductor <NUM> includes a toroidal core <NUM> and winding <NUM> coiled around the toroidal core <NUM>. The toroidal housing and/or inductor core can have a rectangular toroid shape, circular toroid shape, or the like. It is also contemplated that the inner and outer housing walls and/or inner and outer surfaces of the inductor can be annular, or generally concentric with one another and have a variety of other shapes, e.g. squares, ovals or the like. The winding <NUM> and core <NUM> generally generate a large amount of heat. Winding <NUM> can be made from a single wire <NUM> coiled about core <NUM>, or a plurality of wire windings. Those skilled in the art will readily appreciate that the wire <NUM> could be a solid wire or a strand of wire in the form of a Litz wire. A potting material <NUM> surrounds toroidal inductor <NUM> and is positioned between the toroidal inductor <NUM> and the toroidal housing <NUM>. Potting material <NUM> is within an interior <NUM> of toroidal housing <NUM> between the toroidal inductor <NUM> and inner and outer walls <NUM> and <NUM>, respectively, of the toroidal housing <NUM>. For clarity purposes, potting material <NUM> is depicted as partially removed from the left side of housing <NUM> in <FIG> and entirely removed from the right side of housing <NUM>, as oriented in <FIG>. In actuality, potting material <NUM> would generally fill the entire interior <NUM> of housing <NUM>. The heat is transferred through potting material <NUM> (i) to the housing <NUM> and then to a cold plate <NUM>, or (ii) directly to the cold plate <NUM>. Due to the heat transfer properties of the potting material <NUM> (in particular, thermal conductivity), there is generally a large temperature gradient between the heat generating source (the inductor <NUM>) and cold plate <NUM>.

As shown in <FIG>, system <NUM> includes conductors <NUM>, e.g. heat pipes <NUM>. The heat pipes <NUM> (in combination with the heat transfer fluid therein) have greater heat transfer rate than the inner and outer walls <NUM> and <NUM>. The heat pipes <NUM> are configured to conduct heat through inner and outer walls <NUM> and <NUM> from one side, e.g. first side 102a, of the housing <NUM> to the other, e.g. second side 102b, more efficiently than if the conductor were not present. Each heat pipe <NUM> is positioned in abutment with the toroidal housing <NUM> to conduct heat from first side 102a of the toroidal housing <NUM>, e.g. a side proximate to inductor <NUM>, to second side 102b of the toroidal housing <NUM>, e.g. the side proximate to the cold plate <NUM>. Heat pipes <NUM> are enclosed metal tubes with fluid contained therein. The fluid is not depicted in <FIG>, but is shown schematically in <FIG> within a heat pipe <NUM>, for example. The fluid is generally a two-phase heat transfer fluid where the heated vapor flows from the hotter region to the cooler side through the channel defined within heat pipe <NUM> and condensed liquid-return via wicking action. This process enhances conduction top to bottom in housing <NUM>. Heat pipes can also be oscillating heat pipes that use two-phase fluid flow to transfer heat between toroidal inductor <NUM> and cold plate <NUM>.

With continued reference to <FIG>, heat pipes <NUM> are used on the sides of the housing <NUM> (e.g. inner and outer walls <NUM> and <NUM>) to reduce gradient from a top side, e.g. a first side 102a, to a bottom side, e.g. a second side 102b. The outer wall <NUM> and the inner wall <NUM> each define respective inner surfaces 104a and 106a, respectively, that face the interior of the housing <NUM> and the toroidal inductor <NUM>. The inner surfaces 104a and 106a of both outer and inner walls <NUM> and <NUM> each include a groove <NUM> defined therein. Each groove <NUM> is helical relative to a central axis A of the toroidal housing <NUM>. Each heat pipe <NUM> is soldered within a respective groove <NUM> to a respective one of the inner surfaces 104a and 106a. The toroidal housing <NUM> includes at least one of a tin or nickel plating locally or globally as desired to assist with soldering the heat pipes <NUM> or other conductor, e.g. a copper spreader, into grooves <NUM>.

In some embodiments, as shown in <FIG>, instead of having grooves <NUM> at least partially open to the interior <NUM> of housing <NUM>, heat pipes <NUM> are enclosed within helical apertures <NUM>'. Helical apertures <NUM>' are bounded by outer wall <NUM>, such that the helical apertures <NUM>' are isolated from the potting material <NUM> that fills the interior <NUM> of housing <NUM>. Similar helical apertures <NUM>' can be included in inner wall <NUM>.

With continued reference to <FIG>, groove <NUM> is generally longer than the length of a given one of the heat pipes <NUM>. As such, a plurality of heat pipes <NUM> are used within a given groove <NUM>. The heat pipes <NUM> are positioned within the groove <NUM> in end-to-end abutment with one another. The second side 102b of the toroidal housing <NUM> is proximate to and abuts a cold plate <NUM>. Bottom surface <NUM> of toroidal housing <NUM> abuts a top surface <NUM> of cold plate <NUM>. The toroidal housing <NUM> is mounted to cold plate <NUM> by way of mounting flanges <NUM> of housing <NUM>. The mounting flanges <NUM> include apertures <NUM> and are fixed to cold plate <NUM> by way of fasteners such as screws, bolts and the like. Additionally, inner surfaces 104a and 106a can each include multiple separate helical grooves defined therein.

As shown in <FIG>, a thermal management system <NUM> is the same as thermal management system <NUM> as described above, except that instead of having helical grooves <NUM> defined in the outer and/or inner walls, a toroidal housing <NUM> is defined by an outer wall <NUM> and an inner wall <NUM>, where the outer wall <NUM> defines axially extending apertures <NUM>. The housing <NUM> includes a top wall or lid <NUM>. The outer wall <NUM> and the inner wall <NUM> each define respective inner surfaces 204a and <NUM>, respectively, that face the interior of the housing <NUM>. The axially extending apertures <NUM> are defined within a flange portion <NUM> of outer wall <NUM>. Conductors, e.g. heat pipes <NUM>, are positioned within the axially extending apertures <NUM> and are in abutment with the toroidal housing <NUM> to conduct heat from a first side 202a of the toroidal housing to a second side 202b of the toroidal housing <NUM>. The portion of outer wall <NUM> with apertures <NUM> and the heat pipes <NUM> therein, are shown partly in cross-section. The conductors, e.g. heat pipes <NUM>, operate in the same manner as heat pipes <NUM>, described above.

As shown in <FIG>, a thermal management system <NUM> includes a toroidal inductor <NUM> and toroidal housing <NUM> around the toroidal inductor <NUM>. Top wall <NUM> is shown partially broken away in <FIG> to show toroidal inductor <NUM>. The toroidal inductor <NUM> includes a toroidal core <NUM> and winding <NUM> coiled around the toroidal core <NUM>. The winding <NUM> and core <NUM> are the same as winding <NUM> and core <NUM> described above. A potting material <NUM> surrounds toroidal inductor <NUM> and is positioned between the toroidal inductor <NUM> and the inner and outer walls <NUM> and <NUM>, respectively, of toroidal housing <NUM>. Potting material <NUM> is the same as potting material <NUM>. For clarity purposes, potting material <NUM> is not shown in <FIG>.

With continued reference to <FIG>, a longitudinal axis Y of each conductor <NUM> is aligned with a longitudinal axis of its respective axially extending aperture <NUM> (the longitudinal axis of the aperture <NUM> is also shown by longitudinal axis Y. Each axially extending aperture <NUM> is aligned with (e.g. substantially parallel to) a central axis A of the toroidal housing <NUM>. The axially extending apertures <NUM> are defined about a circumference of the outer wall <NUM>. The axially extending apertures <NUM> are equally spaced apart around the outer circumference of the outer wall <NUM>. For example, as shown in <FIG>, they can be positioned at <NUM>, <NUM>, <NUM> and <NUM> o'clock positions. The toroidal housing <NUM> is mounted to cold plate <NUM> by way of mounting flanges <NUM> of housing <NUM>. Bottom surface <NUM> of toroidal housing <NUM> abuts a top surface <NUM> of cold plate <NUM>. The mounting flanges <NUM> include apertures <NUM> and are fixed to cold plate <NUM> by way of fasteners such as screws, bolts and the like. Mounting flanges <NUM> can be interspersed between apertures <NUM> around the circumference of the outer wall <NUM>. It is also contemplated that inner wall <NUM> can also include longitudinally extending apertures <NUM> defined therein.

It is contemplated that grooves <NUM> of housing <NUM> and the apertures <NUM> of housing <NUM> can be combined into a single thermal management system. In other words, one could readily include helical grooves like grooves <NUM> on an inner surface 206a of inner wall <NUM> and/or on an inner surface 204a of an outer wall <NUM>. Heat pipes like heat pipes <NUM> could be included within the grooves.

A method of manufacturing a thermal management system, e.g. system <NUM> or <NUM>, includes forming a toroidal housing, e.g. a toroidal housing <NUM> or <NUM>, by three-dimensional printing, which allows for the complex groove and/or aperture geometries described above. Forming the toroidal housing includes forming an outer wall, e.g. an outer wall <NUM> or <NUM>, and an inner wall, e.g. inner wall <NUM> or <NUM>, wherein at least one of the outer wall or the inner wall defines an inner surface, e.g. inner surfaces 102a and/or 104a, and 202a and/or 204a.

In some embodiments, forming the toroidal housing includes forming a groove, e.g. groove <NUM>, within the inner surface. Forming the groove includes forming the groove with a helical shape relative to a central axis, e.g. central axis A, of the toroidal housing. In some embodiments, forming the toroidal housing includes forming an axially extending aperture, e.g. aperture <NUM>, in at least one of the outer wall or the inner wall. Forming the axially extending aperture includes forming a plurality of axially extending apertures about a circumference of the outer wall, wherein the axially extending apertures are equally spaced apart around the circumference of the outer wall. The method includes positioning a conductor, e.g. heat pipes <NUM> or <NUM>, in the at least one of the groove or the aperture to conduct heat from a first side, e.g. first side 102a or 202a, of the toroidal housing to a second side, e.g. 102b or 202b, of the toroidal housing. The method includes coiling a winding, e.g. winding <NUM> or <NUM>, around the inductor. The method includes positioning an inductor, e.g. an inductor <NUM>, within the toroidal housing and securing it within the housing with potting material, e.g. potting material <NUM> or <NUM>.

Claim 1:
An inductor assembly having a thermal management system, comprising:
an inductor (<NUM>), the thermal management system comprising a housing (<NUM>, <NUM>) around and in thermal communication with the inductor, the housing defining a wall; and characterized by
a conductor (<NUM>, <NUM>) having a greater heat transfer rate than the wall and being positioned within a groove (<NUM>) formed in the wall, wherein the wall of the housing includes an outer wall (<NUM>, <NUM>) and an inner wall (<NUM>, <NUM>) forming an interior (<NUM>) of the housing containing the inductor (<NUM>),
wherein at least one of the outer wall or the inner wall defines an inner surface (104a, 106a; 204a, 206a), wherein the inner surface includes the groove defined therein.