Patent Description:
A liquid cold plate is a platform for mounting power electronic components. The cold plate provides localized cooling to the components by transferring heat from the components mounted on one or both surfaces to the liquid flowing within. One of the components that may be placed on a cold plate is a toroidal transformer. A toroidal transformer is a power transformer with a toroidal core around which primary and secondary coils are wound. Power is transferred from the primary coil to the secondary coil. In general, voltage applied to the primary coil generates a magnetic field, which is coupled to the secondary coil. This, in turn, generates voltage in secondary coil. Cold plate thermal management is described in <CIT> and <CIT>. <CIT> describes a toroidal transformer that is placed in a cavity formed in a heat sink with an encapsulant being provided between the walls and the base of the cavity and the toroidal transformer.

In one aspect, a system is provided as defined by claim <NUM>.

In embodiments, the cold plate also includes an inlet to channel coolant into the flow channel.

In embodiments, the cold plate also includes an outlet to channel the coolant out of the flow channel.

In embodiments, the cold plate is machined from aluminum or copper.

In another aspect, a method of fabricating a system having a cold plate and a toroidal transformer is provided as defined by claim <NUM>.

In embodiments, the method also includes forming an inlet to channel coolant into the flow channel.

In embodiments, the method also includes forming an outlet to channel the coolant out of the flow channel.

As previously noted, a cold plate can support and cool electronic components. Embodiments of the systems and methods detailed herein relate to thermal management of a toroidal transformer on a cold plate. Specifically, a cavity is machined as an integral part of the cold plate to accommodate the toroidal transformer. Fins that are formed within the cavity facilitate radial heat transfer both within and outside the core of the toroidal transformer. The surface of the cold plate transfers the heat from the toroidal transformer to the liquid flowing within the body of the cold plate.

<FIG> is an exploded view showing a cold plate <NUM> used for thermal management of a toroidal transformer <NUM> according to one or more embodiments. The exploded view shows encapsulant <NUM>, referred to also as potting material, and a toroidal transformer <NUM> above the cold plate <NUM>. The encapsulant <NUM> is thermally conductive but electrically insulating. Thus, the encapsulant <NUM> encapsulates the toroidal transformer <NUM> within a cavity <NUM> and separates the toroidal transformer <NUM> from the cavity <NUM> electrically while conducting heat from the toroidal transformer <NUM> to the cavity <NUM>. The cold plate <NUM> includes the cavity <NUM> machined within a surface <NUM> of a first side <NUM> for seating the toroidal transformer <NUM>. The toroidal transformer <NUM> includes a core <NUM> that is typically made of ferrite material, for example. The two sets of windings <NUM> around the core <NUM> may be copper. The core <NUM> and the windings <NUM> dissipate heat. This heat is removed according to one or more embodiments in order to maintain the temperature of the toroidal transformer <NUM> below a predefined limit.

The cavity <NUM> of the cold plate <NUM> that seats the toroidal transformer <NUM> is further detailed with reference to <FIG>. The cold plate <NUM> has a second surface <NUM>, opposite the surface <NUM>, on a second side <NUM>. As previously noted, components could be attached to both the surface <NUM> and second surface <NUM> of the cold plate <NUM>. According to exemplary embodiments, the thickness of the first side <NUM> is greater than the thickness of the second side <NUM> to accommodate the cavity <NUM>, and components are only disposed on the surface <NUM>. Thus, the exemplary cold plate <NUM> may be referred to as a one-sided.

An inlet <NUM> facilitates an inflow of coolant <NUM> through a flow channel <NUM> (<FIG>) within the cold plate <NUM>. The flow channel <NUM> may be formed as a pipe with fins for additional heat transfer. The flow channel <NUM> within the cold plate <NUM> may be formed in a pattern to allow the coolant <NUM> to absorb heat from different areas of the surface <NUM> as it moves from the inlet <NUM> to the outlet <NUM>. That is, heat from the components on the surface <NUM>, or both surfaces <NUM>, <NUM>, is conducted into the coolant <NUM>, which carries the heat out via the outlet <NUM>. Exemplary coolants <NUM> include ethylene glycol with water (EGW), propylene glycol with water (PGW), and polyalphaolefin (PAO).

<FIG> shows aspects of the cavity <NUM> used to perform thermal management of the toroidal transformer <NUM> on a cold plate <NUM> according to one or more embodiments. As previously noted, the cavity <NUM> is machined as an integral part of the cold plate <NUM>. The cold plate <NUM> and, thus, the cavity <NUM> may be aluminum or copper, for example. The cavity <NUM> is defined by a circular outside wall <NUM> with outer fins <NUM> that protrude into the cavity <NUM> and are positioned to be concentrically outside the toroidal transformer <NUM> although they do not contact the toroidal transformer <NUM>. A center post <NUM> supports a set of inner fins <NUM> that protrude into the cavity <NUM> and are positioned to be concentrically inside the toroidal transformer although they do not contact the toroidal transformer <NUM>. The floor or base <NUM> of the cavity <NUM> ultimately conducts the heat dissipated by the toroidal transformer <NUM>, the heat source, to the coolant <NUM>, the heat sink. This is further discussed with reference to <FIG> and <FIG>.

<FIG> shows a toroidal transformer <NUM> in the cavity <NUM> used for thermal management according to one or more embodiments. The view in <FIG> is prior to the addition of a layer of encapsulant <NUM> that covers the cavity <NUM>, as shown in <FIG>. That is, the view in <FIG> can be regarded as a cross-sectional view with the top layer of encapsulant <NUM> removed from the cavity <NUM>. Exemplary encapsulants <NUM> include Stycast <NUM>, Sylgard <NUM>, and Scotchcast <NUM>. As previously noted, the outer fins <NUM> protruding from the outside wall <NUM> do not contact the toroidal transformer <NUM>. Instead, encapsulant <NUM> fills a gap between the outside wall <NUM> and each of the outer fins <NUM> and the toroidal transformer <NUM>. As also previously noted, the inner fins <NUM> protruding from the center post <NUM> do not contact the toroidal transformer <NUM>. Instead, encapsulant <NUM> fills a gap between the center post <NUM> and each of the inner fins <NUM> and the toroidal transformer <NUM>.

<FIG> shows the toroidal transformer <NUM> in the cavity <NUM> of the cold plate <NUM> for thermal management according to one or more embodiments. As <FIG> indicates, the toroidal transformer <NUM> is not visible because of a layer of encapsulant <NUM> that covers the cavity <NUM>. As further discussed with reference to <FIG>, the encapsulant <NUM> is not only above the toroidal transformer <NUM>, as shown in <FIG>, and surrounding the toroidal transformer <NUM>, as shown in <FIG>, but the encapsulant <NUM> is also beneath the toroidal transformer <NUM>.

It should be understood that other components, additional to the toroidal transformer <NUM>, may be mounted on the surface <NUM> of the cold plate <NUM>. Another one or more cavities <NUM> to seat another one or more toroidal transformers <NUM> may also be integrated into the surface <NUM>. The other components, including any other toroidal transformers <NUM>, are placed on the surface <NUM> in consideration of the heat that they dissipate and the cooling capacity of the cold plate <NUM>. The overall cooling capacity of the cold plate <NUM> is based on several factors including the size and thickness of the surface <NUM> and the temperature of the coolant <NUM>. The cross-section indicated through A-A in shown in <FIG>.

<FIG> is a cross-sectional view through the cavity <NUM> used for thermal management of the toroidal transformer <NUM> according to one or more embodiments. The cross-section through A-A indicated in <FIG> is shown. The cross-sectional view indicates that the thickness T of the first side <NUM> of the cold plate <NUM> that includes the cavity <NUM> is greater than the thickness t of the second side <NUM> of the cold plate <NUM>. Sections of the flow channel <NUM> are visible within the cold plate <NUM>. As previously noted, the cavity <NUM> is machined to be an integral part of the cold plate <NUM>. Thus, the outside wall <NUM>, center post <NUM>, inner fins <NUM>, and outer fins <NUM> are all machined from the material of the cold plate <NUM>. As a result, thermal interface resistances are eliminated between different aspects of the cavity <NUM>. The absence of thermal interface resistance maximizes heat dissipation from the source (i.e., the toroidal transformer <NUM>). As previously noted, the base <NUM> of the cavity <NUM> ultimately conducts the heat from the cavity <NUM> to the heat sink, the coolant <NUM>. The inner fins <NUM> and outer fins <NUM> define conduction paths for the heat from the toroidal transformer <NUM> (via the encapsulant <NUM>) to reach the base <NUM>, as further discussed with reference to <FIG>. The thickness Bt of this base <NUM> is minimized, with consideration to structural integrity, to maximize heat transfer from the base <NUM> to the coolant <NUM> flowing through the flow channel <NUM>.

<FIG> is a cross-sectional view through the toroidal transformer <NUM> in the cavity <NUM> used for thermal management of the toroidal transformer <NUM> according to one or more embodiments. As indicated, the encapsulant <NUM> completely surrounds the toroidal transformer <NUM>. That is, the encapsulant <NUM> is below the toroidal transformer <NUM> between the toroidal transformer <NUM> and the base <NUM> of the cavity <NUM>. The encapsulant <NUM> is concentrically within the toroidal transformer <NUM> between the toroidal transformer <NUM> and the center post <NUM> and inner fins <NUM>. The encapsulant <NUM> is concentrically outside the toroidal transformer <NUM> between the toroidal transformer <NUM> and the outside wall <NUM> and outer fins <NUM> (not visible in <FIG>). The encapsulant <NUM> conducts heat away from the toroidal transformer <NUM> and into the inner fins <NUM> and outer fins <NUM>, as further discussed with reference to <FIG>.

<FIG> shows heat flow from the toroidal transformer <NUM> according to one or more embodiments. The view in <FIG> is similar to the view in <FIG> with heat flow indicated by arrows. As one set of arrows shows, heat flows radially outward from the core <NUM> and the windings <NUM> of the toroidal transformer <NUM> to encapsulant <NUM>. The encapsulant <NUM> conducts the heat to outer fins <NUM> and the outside wall <NUM>. As another set of arrows shows, heat also flows radially inward from the core <NUM> and the windings <NUM> of the toroidal transformer <NUM> to encapsulant <NUM>. The encapsulant <NUM> conducts the heat to inner fins <NUM> and the center post <NUM>.

<FIG> shows heat flow within the cavity <NUM> that performs thermal management of the toroidal transformer <NUM> according to one or more embodiments. The view in <FIG> is similar to the view in <FIG> with heat flow indicated by arrows. As the arrows indicate, heat flow is down the outside wall <NUM>, center post, <NUM>, inner fins <NUM>, and outer fins <NUM> to the base <NUM> of the cavity <NUM>. As previously noted, the heat in the base <NUM> is conducted to the coolant <NUM> that flows below the base <NUM> through the flow channel <NUM>. This coolant <NUM> is the ultimate heat sink of the system mounted on the cold plate <NUM>. The design of the cavity <NUM> provides multiple heat transfer paths to dissipate heat from the toroidal transformer <NUM>, as indicated in <FIG>. This feature, coupled with the absence of thermal interface resistance in the cavity <NUM>, facilitates the removal of a relatively larger amount of heat from the toroidal transformer <NUM> as compared with a cold plate <NUM> that does not include the cavity <NUM>.

Claim 1:
A system comprising a cold plate and a toroidal transformer,
the cold plate comprising:
a first side (<NUM>) with a first surface (<NUM>);
a second side (<NUM>), opposite the first side, with a second surface (<NUM>) opposite the first surface;
a cavity (<NUM>) integrally machined into the first surface of the first side, wherein the cavity is configured to seat a toroidal transformer and is defined by a circular outside wall (<NUM>) and a base (<NUM>), as well as an integrally machined center post (<NUM>) in a center of the cavity, and the outside wall, the base, and the center post are configured such that the toroidal transformer does not directly contact the outside wall, the base, and the center post when seated in the cavity,
wherein the cavity further includes outer fins (<NUM>) protruding from the outside wall radially toward a center of the cavity and which are configured to be concentrically outside the toroidal transformer without contacting the toroidal transformer,
wherein the cavity further includes inner fins (<NUM>) protruding radially from the center post into the cavity toward the outside wall, and which are configured to be concentrically inside the toroidal transformer without contacting the toroidal transformer;
wherein the system further comprises an encapsulant (<NUM>) surrounding the toroidal transformer in the cavity such that the toroidal transformer does not directly contact the base of the cavity; the encapsulant filling any gaps between the toroidal transformer and the base, the center post, the outside wall, the inner fins and the outer fins;
and wherein the cold plate further comprises a cooling channel formed between the base and the second surface.