Patent Publication Number: US-2023154673-A1

Title: Isolated switchmode power supplies having quasi-planar transformers

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation that claims benefit of and priority to U.S. application Ser. No. 16/809,112, filed Mar. 4, 2020. The entire disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to isolated switchmode power supplies, and in particular, isolated switchmode power supplies having quasi-planar transformers. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Quasi-planar transformers are commonly used in isolated switchmode power supplies and typically have “windings” formed of various types of wires and coils including thin copper sheets or triple insulated wire. As compared to conventional “wire-wound-on-a-bobbin” transformers, a quasi-planar transformer may have a higher power density, reduced height, greater surface area for heat dissipation, greater magnetic cross-section area (enabling fewer turns), lower leakage inductance, and/or less AC winding resistance. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     According to one aspect of the present disclosure, an isolated switch-mode power supply includes at least one input, at least one output, and a power circuit coupled between the at least one input and the at least one output for converting an input voltage or current to an output voltage or current. The power circuit includes a transformer having one or more primary windings, one or more secondary windings, an electrical insulator, and a core magnetically coupling the one or more primary windings and the one or more secondary windings. Upper portions of the primary and secondary windings are covered with the electrical insulator. 
     According to another aspect of the present disclosure, a quasi-planar transformer includes one or more primary windings, one or more secondary windings, a core magnetically coupling the one or more primary windings and the one or more secondary windings, and an electrical insulator. Upper portions of the primary and secondary windings are covered with the electrical insulator. 
     According to a further aspect of the present disclosure, a method includes applying an electrical insulator to only upper portions of one or more primary windings and one or more secondary windings of a quasi-planar transformer to form a substantially flat nonconductive surface extending above the upper portions of the primary and secondary windings. The method also includes assembling the one or more primary windings and the one or more secondary windings with one or more magnetic core segments. 
     According to yet another aspect of the present disclosure, an electrical component comprises an annular core, a winding including a wire extending around the core, and an electrical insulator. An upper portion of the winding is covered with the electrical insulator, and a lower portion of the winding is not covered with an electrical insulator. 
     Further aspects and areas of applicability will become apparent from the description provided herein. It should be understood that various aspects of this disclosure may be implemented individually or in combination with one or more other aspects. It should also be understood that the description and specific examples herein are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG.  1    is a side view of an example transformer. 
         FIG.  2    is a perspective view of a core included in the transformer of  FIG.  1   . 
         FIG.  3    is a perspective view of a core including tapings. 
         FIG.  4    is a perspective view of a transformer including a film. 
         FIG.  5    is a perspective view of the transformer of  FIG.  1   . 
         FIG.  6    is a block diagram of a switchmode power supply (SMPS) including the transformer of  FIG.  1   . 
         FIG.  7    is a perspective view of the transformer of  FIG.  1   , without the core. 
         FIG.  8    is an alternate perspective view of the transformer of  FIG.  7   , illustrating a bottom of the transformer without the core. 
         FIGS.  9 A-H  are perspective views of components of a winding assembly at various points of assembly. 
         FIG.  10 A  is an orthogonal view of the winding assembly. 
         FIG.  10 B  is a side view of the winding assembly of  FIG.  10 A  including an optional clip. 
         FIG.  11    is an orthogonal view of a mold. 
         FIG.  12    is a perspective view of inserting the winding assembly of  FIG.  10 A  into the mold of  FIG.  11   . 
         FIG.  13    is a perspective view of inserting a transformer into the mold of  FIG.  11   . 
         FIG.  14 A  is a perspective view of an alternate transformer without the core. 
         FIG.  14 B  is an alternate perspective view of the transformer of  FIG.  14 A , illustrating a bottom of the transformer without the core. 
         FIG.  15 A  is a perspective view of an example magnetic choke according to another aspect of the present disclosure. 
         FIG.  15 B  is a perspective view of another example magnetic choke. 
         FIG.  15 C  is a perspective view of still another example magnetic choke. 
     
    
    
     Corresponding reference numerals indicate corresponding parts or features throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated  90  degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     A transformer according to one example embodiment of the present disclosure is illustrated in  FIG.  1    and indicated generally by reference number  100 . The transformer  100  includes a winding assembly  102  having one or more primary windings  104  and one or more secondary windings  106 . The transformer  100  also includes a core  108  which magnetically couples the primary windings  104  and the secondary windings  106 . 
     As shown in  FIG.  1   , an electrical insulator  110 , which serves as a covering, is disposed on the winding assembly  102  and partially encapsulates the winding assembly  102 . The electrical insulator  110  also includes a substantially flat upper surface  112 . In the exemplary embodiment, the electrical insulator  110  covers upper portions of the primary and secondary windings  104 ,  106  and does not cover lower portions of the primary and secondary windings  104 ,  106 . Alternatively, the lower portions of the primary and secondary windings  104 ,  106  are covered by an electrical insulator and the upper portions of the primary and secondary windings  104 ,  106  are not covered by the electrical insulator  110 . In some embodiments, the upper portions and the lower portions of the primary and secondary windings  104 ,  106  are each covered by an electrical insulator, without fully encapsulating the windings  104 ,  106  or the transformer  100 . 
     In the exemplary embodiment, the primary windings  104  and the secondary windings  106  are positioned generally vertically and each have a central opening. Alternate configurations of the winding assembly  102  are contemplated to satisfy various design requirements such as efficiency, power density, etc. For example, as shown in  FIG.  1   , the primary and secondary windings  104 ,  106  arranged as a quasi-planar transformer configuration. In some embodiments, the primary and secondary windings  104 ,  106  are interleaved. Unlike planar transformers which utilize PCB windings, the windings  104 ,  106  may include various types of windings such as copper plates (e.g., stamped copper plates, rectangular copper coils, bus bar plates, etc.) and/or self-bonded or non-self-bonded insulated wire windings (e.g., single-insulated, double-insulated, triple-insulated). The windings  104 ,  106  may also include various types of wires and coils that are twisted, bunched, litz, round, rectangular, flat litz, etc. Other windings and/or other configurations of windings may be used herein. In some embodiments, non-self-bonded insulated wire windings are included in winding assembly  102  and are taped with tape  114 . 
     The electrical insulator  110  is composed of an encapsulant material. The encapsulant material is suitable to retain the primary windings  104  and the secondary windings  106  in a fixed position, such as to maintain appropriate or desired spacing between the windings  104 ,  106 , and to integrate the components of the winding assembly  102  into a single piece. In some embodiments, the electrical insulator  110  is composed of an ultraviolet (UV) curable encapsulant material. The UV curable material is cured by irradiating the electrical insulator  110  with a UV light source. UV curable materials often have a short cure time such that exposure to a UV light can occur during in-line production of the transformer  100 . For example, the electrical insulator  110  is cured by irradiating with a UV light to retain the winding assembly  102  in a fixed position with respect to the electrical insulator  110 . In alternate embodiments, the electrical insulator  110  is composed of a heat-curable material and cured by applying heat to the electrical insulator  100 . In some embodiments, the electrical insulator  110  is allowed to cure by waiting a sufficient time for the material to cure. Alternatively, the electrical insulator  110  may any suitable material able to retain the winding assembly  102  in a fixed position such that the winding assembly  102  (and the components of the winding assembly  102  including primary and secondary windings  104 ,  106 ) cannot move relative to the electrical insulator  110 . 
     One half of an exemplary core  108  is illustrated in  FIG.  2   . The core  108  may comprise any suitable material, such as a magnetic material. In the exemplary embodiment, the core  108  includes two segments or halves and each half of the core  108  is generally identical. Each half of the core  108  includes a central post  116 , a first surface  118 , a second surface  120 , and a third surface  122 . Surfaces  118 ,  120 , and  122  are inner surfaces or inner portions of the core. The central post  116  and the surfaces  118 ,  120 ,  122  of each half of the core  108  at least partially define a cavity for receiving the winding assembly  102  between the two halves of the core  108 . That is, when the primary and secondary windings  104 ,  106  are assembled with the core  108 , the primary and secondary windings  104 ,  106  are positioned around the central post  116  and adjacent or between the surfaces  118 ,  120 ,  122 . In addition, each half of the core  108  is coupled to the electrical insulator  110 . In some embodiments, side surface  124  of the electrical insulator  110  (as shown in  FIG.  1   ) is positioned to contact the first surface  118  of the core  108  and surface  126 . In this way, the electrical insulator  110  ensures proper spacing between the core  108  and the components of the winding assembly  102 . In alternate embodiments, the electrical insulator  110  is coupled to the core  108  without contacting the first surface  118 . For example, in embodiments where the electrical insulator  110  is applied after the core  108  is assembled with the primary and secondary windings  104 ,  106 , the electrical insulator  110  is coupled to an upper surface  128  and/or an upper surface  130  of the core  108 . 
     In some embodiments, it is desirable to construct the electrical insulator  110  as thin as possible for material savings purposes and to achieve a compact winding design. In one embodiment, when accounting for manufacturing considerations, the thickness of the electrical insulator  110  above the primary and secondary windings  104 ,  106  is at least 0.4 millimeters, the thickness between adjacent windings included in the primary and secondary windings  104 ,  106  is at least 0.1 millimeters, and the thickness between the windings and the core  108  is at least 0.4 millimeters. The electrical insulator may include different thicknesses in other embodiments. 
     As shown in the exemplary embodiment of  FIG.  1   , the core  108  covers a portion  132  of the side surface  124  of the electrical insulator  110  (as indicated by dotted lines). The portion  132  of the electrical insulator  110  is coupled to the first surface  118  of the core  108 . The electrical insulator  110 , and in particular the portion  132 , is of sufficient thickness to ensure a gap is maintained between the winding assembly  102  and the core  108 . Such a gap prevents damage to the winding assembly  102  and/or the core  108 , without the need for tape to secure or insulate the winding assembly  102  from the core  108 . 
       FIG.  3    illustrates an alternative core that includes tape on surfaces  10  to prevent damage to the windings and/or core during assembly of a transformer (e.g., a planar or quasi-planar transformer). Tape may be applied to these surfaces  10  by an automatic core taping machine which adds expense to the assembly process. By including the electrical insulator  110  in a transformer, tape may be eliminated from these surfaces  10 , which reduces costs associated with transformer production, including machinery costs. And, as shown in  FIG.  4   , some configurations of transformers include a film  20 , such as Mylar® film or Nomex® paper, to prevent damage to the windings and/or core of the transformers. In some embodiments, the use of the electrical insulator  110  in a transformer eliminates the need for the film  20 . 
       FIG.  5    depicts an exemplary transformer  100 . The transformer  100  also includes bus bar terminals  134  which are adjacent to a bottom surface of the core  108 . For purposes of illustration, the electrical insulator  110  is substantially transparent such that the upper portion of the winding assembly  102  is visible through the electrical insulator  110 . The electrical insulator  110  partially encapsulates the winding assembly  102 , and in this way, the components of the winding assembly  102  (e.g., the primary windings  104 , the secondary windings  106 , etc.) are secured in a fixed position. This is accomplished without entirely encapsulating the winding assembly  102  and/or the transformer  100 . For example, in some embodiments, the electrical insulator  110  encapsulates less than half of the winding assembly  102  (e.g., less than half of each of the primary and secondary windings  104 ,  106 ). In other embodiments, the electrical insulator  110  encapsulates only an upper portion of the winding assembly  102  such that electrical insulator  110  does not obstruct a central opening of the winding assembly  102  (i.e., the central post  116  of the core  108  is permitted to pass through the central opening of the winding assembly  102 ). In still other embodiments, the electrical insulator  110  encapsulates at least portion of the winding assembly  102  that extends beyond the upper surfaces  128 ,  130  of the core  108  (e.g., a portion of the winding assembly  102  that remains exposed when the core  108  is coupled to the winding assembly  102 ). 
     With continued reference to  FIG.  5   , the electrical insulator  110  is sized and shaped for engagement with a “pick and place” device (not shown) such that the transformer  100  may be moved and placed on a circuit board, where the transformer  100  is electronically coupled to the circuit board. In particular, the substantially flat surface  112  of the electrical insulator  110  is suitable for receiving a suction-type “pick and place” device of an automated insertion machine (not shown). The surface  112  is flat, or at least substantially flat, to ensure the suction device can properly engage with the electrical insulator  110  (e.g., form a seal between the suction device and the surface  112 ). For example, a suction-type device of the automated insertion assembly engages, via suction, with the surface  112  of the electrical insulator  110  to pick up, move, relocate, and/or insert the transformer  100  as desired (e.g., move a transformer from one location to another location to place the transformer on a circuit board). 
     The electrical insulator  110  further includes a plurality of side surfaces  124  which are perpendicular to the surface  112 . Alternatively, the side surfaces  124  are oriented at one or more other suitable angle(s) (e.g., an angle suitable for removing the electrical insulator  110  from a mold, etc.). In some embodiments, a grip-type device such as a claw or a gripper of the automated insertion assembly frictionally engages with two or more side surfaces  124  of the electrical insulator  110  to pick up, move, and/or insert the transformer  100  as desired. For example, the automated insertion assembly picks up and/or moves the transformer  100  from a first location to a second location, such as a circuit board, by engaging with the surface  112  and/or the side surfaces  124  of the electrical insulator  110 . As such, the electrical insulator  110 , in particular the substantially flat surface  112  and the plurality of side surfaces  114 , is sized and shaped to engage with a variety of gripping devices attachable to automated assertion assemblies for automated production. 
     As described above, the transformer  100  is suitable for use in a circuit board with any suitable circuit topologies, such as a power supply. In some embodiments, the transformer  100  is used in a switchmode power supply (SMPS).  FIG.  6    illustrates a SMPS  600  according to one example embodiment of the present disclosure that includes the transformer  100 . As shown in  FIG.  6   , the SMPS  600  includes a power circuit  602  and a control circuit  604 . The power circuit  602  includes an input  606  for receiving an input voltage Vin, the transformer  100  including primary windings  104  and secondary windings  106 , and an output  608  for providing an output voltage Vout. As shown in  FIG.  6   , the control circuit  604  is coupled to the power circuit  602  for regulating the output voltage Vout. Alternatively, the control circuit  604  is coupled to the power circuit  602  for regulating the input voltage Vin. The control circuit  604  is configured to generate a control signal  610 . The components included in SMPS  600  are exemplary only and the transformer  100  is contemplated for use in other circuit topologies, including any other suitable isolated SMPS topologies. 
       FIGS.  7  and  8    depict a transformer  100  without the core  108 . As shown in  FIG.  7   , the electrical insulator  110  partially encapsulates an upper portion of the winding assembly  102  such that the primary windings  104  and the secondary windings  106  are retained in a fixed position. In the embodiment shown in  FIG.  8   , the bottom portion of the winding assembly  102  is not encapsulated by the electrical insulator  110 . By including a portion of the winding assembly  102  that is not encapsulated, such uncovered portions may facilitate improved heat transfer. The electrical insulator  110  is directly coupled to the upper portion of the winding assembly  102 , such as by applying a material to the upper portion of the primary and secondary windings  104 ,  106  and curing the material to form the electrical insulator  110 . In some embodiments, the upper portion of the winding assembly  102  is dipped into a mold filled with an electrical insulator or encapsulant material and after the material is set or cured, the winding assembly  102  and the encapsulant material are removed from the mold. Alternatively, the electrical insulator  110  may be formed or molded of a rigid or semi-rigid nonconductive material (e.g., of a plastic material) apart from the winding assembly  102  and subsequently coupled to the winding assembly  102 . The rigid or semi-rigid nonconductive cover is sized and shaped to cover over only the upper portions of the primary and secondary windings  104 ,  106 . 
     In some embodiments, the electrical insulator  110  partially encapsulates the winding assembly  102  such that no additional tape is necessary to insulate or protect the winding assembly  102  and/or the core  108 . That is, no tape is applied to the core  108 . Instead, the electrical insulator  110  maintains a desired separation and/or insulation between the winding assembly  102  and the core  108  and between the components of the winding assembly. In particular, the electrical insulator  110  extends beyond the winding assembly  102  by a certain distance, such that when the core  108  is coupled to the electrical insulator  110 , the electrical insulator  110  prevents the core  108  from directly contacting the winding assembly  102 . Because the electrical insulator  110  retains the winding assembly  102  in a fixed position, a compact winding design can be achieved without the windings being scratched or damaged during assembly. 
     According to another aspect of the present disclosure, a method of manufacturing a transformer  100  is disclosed.  FIGS.  9 A- 9 H  depict an exemplary method of assembling the primary and secondary windings  104 ,  106  for a quasi-planar transformer. Initially, a first winding coil  902  is inserted into an aligner jig  904  ( FIG.  9 A ). After the first winding coil  902  is inserted into the aligner jig  904 , a first bus bar plate winding  906  is inserted into the aligner jig  904  on top of the first winding coil  902  ( FIG.  9 B ). Then, a second winding coil  908  and a third winding coil  910  are combined ( FIG.  9 C ) and the central openings of the winding coils  908 ,  910  are aligned ( FIG.  9 D ). The combined winding coils  908 ,  910  are then inserted into the aligner jig  904  on top of the first bus bar plate winding  906  ( FIGS.  9 E- 9 F ). A second bus bar plate winding  912  is then inserted into the aligner jig  904  on top of the combined winding coils  908 ,  910  ( FIG.  9 G ). A fourth winding coil  914  is inserted into the aligner jig  904  on top of the second bus bar plate winding  912  ( FIG.  9 H ). The process (as shown in  FIGS.  9 A- 9 H ) may be repeated until all coils are completely assembled, forming winding assembly  102  (shown in  FIG.  10 A ). The bus bar plate windings  906 ,  912  include terminals, such as bus bar terminals  134 . Additionally, the aligner jig  904  may include features to control the spacing of the coils and bus bar windings. 
     As shown in  FIG.  10 A , the upper portions of the winding coils (e.g.,  902 ,  908 ,  910 ,  914 ) and the bus bar plates (e.g.,  906 ,  912 ) are of different shapes and/or heights such that the winding assembly  102  does not include a flat upper surface that is suitable for engaging with a grip-type or suction-type pick and place machine. To provide such a surface, the method includes applying an electrical insulator  110  to only upper portions of the primary windings  104  and the secondary windings  106  of the quasi-planar transformer to form a substantially flat nonconductive surface (e.g., surface  112 ) extending above the upper portions of the primary and secondary windings. In some embodiments, applying the electrical insulator  110  includes dispensing a material for the electrical insulator  110  into a mold  1100  and inserting or dipping the winding assembly  102  into the mold  1100  such that the winding assembly is partially inserted into the material. 
     In some embodiments, the electrical insulator  110  is applied to the winding assembly  102  while the winding assembly is within the aligner jig  904 . While in the aligner jig  904 , the spacing of the windings of the winding assembly  102  is controlled. However, with respect to non-self-bonded coil windings for example, once the windings are removed from the aligner jig  904 , the windings often cannot keep their spacing, form, and/or flatness. By applying the electrical insulator  110  while the windings are within the aligner jig  904 , a compact winding design can be achieved which ensures the windings are secured in a fixed position with proper spacing. After the electrical insulator  110  has cured or set, the winding assembly  102  is removed from the aligner jig  904 . In some embodiments, a clip  1000  (shown in  FIG.  10 B ) may be used to hold the completely assembled winding assembly  102  in place prior to the molding process, as described in more detail below. Alternatively, an adhesive, such as an instant glue, may be used to hold the assembled winding assembly  102  in place. 
     An exemplary mold is illustrated in  FIG.  11   . In the exemplary embodiment, mold  1100  is a substantially rectangular container having a substantially flat inner surface  1102  and side walls  1104 . The inner surface  1102  corresponds to the substantially flat surface  112  of electrical insulator  110 , shown in  FIG.  1   . Side walls  1104  extend perpendicularly (or at another suitable angle) from the inner surface  1102  and define an opening  1106  of the mold  1100 . Various different sizes and/or configurations of mold  1100  are contemplated dependent on core geometry and size. The material for the electrical insulator  110 , such as an encapsulant material, is dispensed into the mold  1100  and the material is received in between the inner surface  1102  and side walls  1104 . A specified amount of the material is dispensed into the mold  1100  such that the material partially encapsulates only upper portions of the primary and secondary windings  104 ,  106  of the winding assembly  102  when the windings  104 ,  106  are inserted. The amount of material is pre-determined according to core size and geometry as well as identified surfaces to be covered by the electrical insulator  110 . The method may also include leveling the mold  1100  and/or leveling the material within the mold  1100 . 
     After the encapsulant material is dispensed into the mold  1100 , the winding assembly  102  is inserted or dipped  1200  into the mold  1100  through the opening  1106 , as shown in  FIG.  12   . The opening  1106  is sized and shaped to receive the inserted winding assembly  102  such that the winding assembly  102  does not contact the inner surface  1102  and/or the side walls  1104  of the mold  1100 . To ensure the windings  104 ,  106  do not contact the mold  1100 , the mold  1100  optionally includes embedded spacers (not shown) that are positioned based on core geometry. Only the upper portions of the primary and secondary windings  104 ,  106  are inserted into the material, rather than submerging and/or inserting the entire winding assembly  102  into the material. In this way, the winding assembly  102  of the quasi-planar transformer is only partially encapsulated, rather than full encapsulation of the quasi-planar transformer. 
     In alternate embodiments, the material for the electrical insulator  110  is applied to the winding assembly  102  using an applicator. That is, rather than dispensing material into a mold, the material is applied (e.g., directly applied) with an applicator to only the upper portions of the primary and secondary windings  104 ,  106  of the quasi-planar transformer. For example, for transformer assemblies having complex winding configurations, applying the material for the electrical insulator  110  with an applicator may ensure proper application of the material for the electrical insulator  110  to the winding assembly  102 . 
     Alternatively, an electrical insulator  110  may be applied to the quasi-planar transformer by placing a rigid or semi-rigid nonconductive cover over the upper portions of the primary and secondary windings  104 ,  106 . This nonconductive cover, or molded header, may be formed separately from the quasi-planar transformer and subsequently coupled to the upper portions of the primary and secondary windings  104 ,  106 . In some embodiments, the rigid or semi-rigid nonconductive cover may be formed of a plastic material. 
     After the electrical insulator  110  is applied to upper portions of the primary and secondary windings  104 ,  106  of the winding assembly  102 , either using a mold  1100  or an applicator, the method further includes allowing the electrical insulator  110  to cure. In some embodiments, curing the electrical insulator  110  includes irradiating the electrical insulator  110  with an ultra-violet (UV) light, for example when the electrical insulator  110  is of a UV-curable encapsulant material. Such UV-curable encapsulants have a short curing time when exposed to UV light and may be cured in-line/during production. Alternatively, the electrical insulator  110  may be heat-cured or cured using another suitable curing technique (e.g., waiting a specified duration of time), based in part on the material that is used as an encapsulant and/or the specifications for the selected material. By curing the electrical insulator  110 , the components of the winding assembly  102  are retained in a fixed position with respect to the electrical insulator  110 . In this way, the cured electrical insulator  110  locks or holds the components of the winding assembly  102  (e.g., the primary and secondary windings  104 ,  106 ) in a fixed position such that the winding assembly  102  and the electrical insulator  110  (which partially encapsulates only the upper portion of the primary and secondary windings  104 ,  106 ) form a single piece. In embodiments using mold  1100 , after the electrical insulator  110  is cured (e.g., by exposing the electrical insulator  110  to a UV light), the winding assembly  102  and partially encapsulating electrical insulator  110  are removed from the mold  1100 . 
     The method also includes assembling the primary and secondary windings  104 ,  106  with one or more magnetic core segments (such as the core segment shown in  FIG.  2   ) which form core  108 . In some embodiments, the assembling of the primary and secondary windings  104 ,  106  with the core  108  occurs after the electrical insulator  110  is applied. In these embodiments, the core segments forming core  108  are coupled to the electrical insulator  110  which partially encapsulates the upper portions of the primary and secondary windings  104 ,  106 . In some embodiments, the core  108  is only coupled to a portion (including portion  132 ) of electrical insulator  110 . 
     In some embodiments, the method also includes an automated production device, such as a suction or gripper device of a pick and place machine, engaging the electrical insulator  110  to move the transformer  100  from one location to another location. In particular, a pick and place machine engages with the upper surface  112  and/or one or more side surfaces  124  of the transformer  100 . For example, during production, it may be desirable to move the transformer from one location to another using an automated production device to automate production and place the transformer  100  on a circuit board. Such a device engages with the electrical insulator  110  to move, adjust, and/or relocate the transformer  100 , before or after the core is coupled to the encapsulant. 
     According to another example embodiment of the present disclosure, an alternate method is disclosed in which the primary and secondary windings  104 ,  106  are assembled with the core  108  prior to or before the electrical insulator  110  is applied, rather than after.  FIG.  13    depicts an alternate method of applying the electrical insulator  110  to a transformer  1300 , after the core  108  has been assembled, using a mold  1100 . Transformer  1300  is similar to transformer  100  except that the core  108  is assembled prior to applying the electrical insulator  110  instead of after. In particular, the electrical insulator  110  is applied to the transformer  1300  by dispensing the material for the electrical insulator  110  into the mold  1100  and inserting or dipping  1200  the transformer into the mold through the opening  1106 . The opening  1106  is sized and shaped to receive the partially inserted transformer  1300  such that the winding assembly  102  of the transformer does not contact the inner surface  1102  and/or the side walls  1104  of the mold  1100 . When inserted into the mold  1100 , only the upper portion of the primary and secondary windings  104 ,  106  of the winding assembly  102  are inserted into the electrical insulator  110 . In this way, the transformer  1300  and the winding assembly  102  are not fully encapsulated by the electrical insulator  110 . Additionally, the transformer  1300  is inserted such that the electrical insulator  110  is applied to at least a portion of the upper surfaces  128 ,  130  of the core  108 . In this manner, the electrical insulator  110  covers at least a portion of the upper surfaces  128 ,  130  of the core  108  and at least a portion of the winding assembly  102  extending beyond the core  108 . The electrical insulator  110  is allowed to cure (e.g., waiting, applying heat, irradiating with UV light, etc.) and the transformer  1300  with the electrical insulator  110  is removed from the mold  1100 . The cured electrical insulator  110  retains the components of the transformer  1300  in a fixed position such that the winding assembly  102 , the core  108 , and the cured electrical insulator  110  form a single piece. 
       FIGS.  14 A and  14 B  depict the winding assembly  102  with a lower electrical insulator  136  which covers lower portions of the primary and secondary windings  104 ,  106 . The lower electrical insulator  136  does not cover the bus bar terminals  134 . In some embodiments, the transformer  100  includes the lower electrical insulator  136  in addition to the electrical insulator  110  to ensure stability and compactness of the winding assembly  102 . Even in embodiments including both the electrical insulator  110  and the lower electrical insulator  136 , the electrical insulators  110 ,  136  secure the components of the winding assembly  102  (e.g., the primary windings  104 , the secondary windings  106 , etc.) in a fixed position without entirely encapsulating the winding assembly  102  and/or the transformer  100 . For example, the electrical insulator  136  encapsulates only a lower portion of the winding assembly  102  such that electrical insulator  136  does not obstruct a central opening of the winding assembly  102  (i.e., the central post  116  of the core  108  is permitted to pass through the central opening of the winding assembly  102 ). In some embodiments, the electrical insulator  110  and the lower electrical insulator  136  are spaced apart by at least the dimension of the central opening of the winding assembly  102 . 
     In some embodiments, the lower electrical insulator  136  is composed of an ultraviolet (UV) curable encapsulant material. The UV curable material is cured by irradiating the electrical insulator  136  with a UV light source. In alternate embodiments, the electrical insulator  136  is composed of a heat-curable material and cured by applying heat to the electrical insulator  100 . In some embodiments, the electrical insulator  136  is allowed to cure by waiting a sufficient time for the material to cure. Alternatively, the electrical insulator  136  may any suitable material able to retain the winding assembly  102  in a fixed position such that the winding assembly  102  (and the components of the winding assembly  102  including primary and secondary windings  104 ,  106 ) cannot move relative to the electrical insulator  136 . 
     The lower electrical insulator  136  is directly coupled to the lower portion of the winding assembly  102 , such as by applying a material to the lower portion of the primary and secondary windings  104 ,  106  and curing the material to form the lower electrical insulator  136 . In some embodiments, the lower portion of the winding assembly  102  is inserted into a mold filled with an electrical insulator or encapsulant material and after the material is set or cured, the winding assembly  102  and the encapsulant material are removed from the mold. The mold for the lower electrical insulator  136  includes embedded aligners to ensure proper spacing of the primary and secondary windings  104 ,  106 . To accommodate the bus bar terminals  134 , the mold for the lower electrical insulator  136  includes slots which allow the bus bar terminals  134  of the winding assembly  102  to pass through, such that the bus bar terminals  134  are not covered by the lower electrical insulator  136 . 
     As described above, the electrical insulator  110  is suitable for engagement with an automated production device. The electrical insulator  110  may be applied to other electrical components, apart from a transformer, to enable an automated production device to pick up, move, relocate, and/or insert the electrical components as desired.  FIGS.  15 A and  15 B  depict an example inductor toroid  138  that includes the electrical insulator  110 . The inductor toroid  138  includes a circular ring or donut shaped magnetic core  140  and a winding  142  that includes at least one wire wound around the core  140 . The electrical insulator  110  coupled to and covers only an upper portion of the winding  142  (e.g., encapsulating less than half of the winding  142 ) and does not cover a lower portion of the winding  142 . By including a portion of the winding  142  that is not encapsulated, such uncovered portions may facilitate improved heat transfer. The inductor toroid  138  may be used in a wide range of electronic circuits including power supplies, such as SMPS  600 . The inductor toroid  138  includes any suitable inductor toroid such as a resonant choke, a common mode choke, a differential choke, a current send, a gate drive transformer or the like. 
       FIG.  15 C  depicts an example air cored coil  144 , or spring coil, that includes the electrical insulator  110 . Similar to the inductor toroid  138 , the air cored coil  144  includes a winding  146  that is wrapped around a core, however, the core of the air cored coil  144  is comprised of air or another suitable non-magnetic material. The electrical insulator  110  is coupled to and covers only an upper portion of the winding  146  (e.g., encapsulating less than half of the winding  146 ) and does not cover a lower portion of the winding  146 . By including a portion of the winding  146  that is not encapsulated, such uncovered portions may facilitate improved heat transfer. The air cored coil  144  is any suitable air cored coil or spring coil such as an antenna coil, an inductor coil, etc. The electrical insulator  110  allows the inductor toroid  138  and the air cored coil  144  to be moved by an automated insertion machine and placed, for example, on a circuit board, where the inductor toroid  138  and the air cored coil  144  may be electronically coupled to the circuit board. 
     Example embodiments described herein may facilitate use of a partially encapsulated quasi-planar transformer for applications that use automated production. For example, the transformer may allow for an automated production device (e.g., a gripper or suction device of a pick and place machine, etc.) to engage with a substantially flat upper surface and/or side portions of the electrical insulator covering during production to move and/or adjust the transformer as desired. 
     In some embodiments, the assemblies may reduce quality problems encountered during or after assembly (e.g., problems associated with loose windings, core separation, damage to the core or windings such as scratches), because the electrical insulator covering ensures the windings of the transformer are retained in a fixed position relative to the covering. In this manner, hipot problems may be reduced. The electrical insulator covering of the transformer also eliminates the need for tape to be applied to the core to insulate, secure, and/or protect the core and windings, thus eliminating the need for expensive core taping machines for transformer production. Additionally, the electrical insulator eliminates the need for a protective film between the windings and the core. In this way, the assemblies may allow for increased throughput yield and decreased production cost. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.