Patent Application
20160104567
The field of the invention relates generally to the design and manufacture of electromagnetic components and related methods, and more particularly to the design and manufacture of electromagnetic transformer components for electronic devices and applications.
Electromagnetic components are known that utilize electric current and magnetic fields to provide a desired effect in an electrical circuit. Transformers are one well known type of electromagnetic components that include at least one pair of coils or windings, sometimes referred to as a primary winding and as secondary winding. Electrical current flow through the primary winding induces a magnetic field within a magnetic core, which in turn induces electrical current flow in the secondary winding. Depending on the relative number of turns in the primary and secondary windings, the current output in the secondary winding may be increased or decreased relative to the current flow in the primary winding. Voltage and current transformers are known that function to convert an input voltage or input current having a first magnitude to an output voltage or output current having a second magnitude different from the first magnitude. Such transformers are sometimes referred to as step-up and step-down transformers.
Recent trends to produce increasingly powerful, yet smaller electronic devices have led to numerous challenges to the electronics industry. Electronic devices such as smart phones, personal digital assistant (PDA) devices, entertainment devices, and portable computer devices, to name a few, are now widely owned and operated by a large, and growing, population of users. Such devices include an impressive, and rapidly expanding, array of features allowing such devices to interconnect with a plurality of communication networks, including but not limited to the Internet, as well as other electronic devices. Rapid information exchange using wireless communication platforms is possible using such devices, and such devices have become very convenient and popular to business and personal users alike.
For surface mount component manufacturers for circuit board applications required by such electronic devices, the challenge has been to provide increasingly miniaturized components so as to minimize the area occupied on a circuit board by the component (sometimes referred to as the component “footprint”) and also its height measured in a direction perpendicular to a plane of the circuit board (sometimes referred to as the component “profile”). By decreasing the footprint and profile, the size of the circuit board assemblies for electronic devices can be reduced and/or the component density on the circuit board(s) can be increased, which allows for reductions in size of the electronic device itself or increased capabilities of a device with comparable size. Miniaturizing electromagnetic components in a cost effective manner has introduced a number of practical challenges to electromagnetic component manufacturers in a highly competitive marketplace. Because of the high volume of components needed for electronic devices in great demand, cost reduction in fabricating components has been of great practical interest to electromagnetic component manufacturers.
In order to meet increasing demand for electronic devices, especially hand held devices, each generation of electronic devices need to be not only smaller, but offer increased functional features and capabilities. As a result, the electronic devices must be increasingly powerful devices. For some types of components, such as electromagnetic transformer components used in the power supply circuitry for the devices, meeting increased power demands while continuing to reduce the size of components that are already quite small, has proven challenging.
Non-limiting and non-exhaustive embodiments are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various drawings unless otherwise specified.
Exemplary embodiments of inventive electromagnetic transformer designs, assemblies and constructions, and also related methodologies and methods of transformer component design and manufacture, are described below that, among other things, facilitate the design and manufacture of optimal electromagnetic transformer components in applications such as power circuitry for higher current and higher power applications yet having low profiles that are difficult, if not impossible, to achieve, using conventional electromagnetic component design and fabrication techniques. Electromagnetic transformer components may also be fabricated with reduced cost compared to other known miniaturized transformer component constructions. Manufacturing methodology and steps associated with the devices described are in part apparent and in part specifically described below but are believed to be well within the purview of those in the art without further explanation.
As used, herein, the term “transformer” shall refer to an electromagnetic component provided for achieving a step increase or step decrease in current or voltage in an electrical circuit. Transformers are designed to induce a magnetic field in a magnetic core as current flows through a primary winding having a first number of turns, and from that magnetic field to induce a current in a secondary winding having a second number of turns that is a ratio of the turns of the primary winding. The current output from the secondary winding may accordingly be increased or decreased by the ratio provided in the primary and secondary windings.
For clarity, the term “transformer” as used herein is distinguishable from other types of electromagnetic components, and more specifically from inductor components, including but not limited to power and non-power inductors. While transformers and inductors both operate using electromagnetic principles, there are fundamental differences between them from a component design and fabrication perspective.
A “power inductor” shall refer to an electromagnetic component provided in power supply management applications and power management circuitry on circuit boards for powering a host of electronic devices, including but not necessarily limited to hand held electronic devices. Power inductors are designed to induce magnetic fields in magnetic cores via current flowing through one or more conductive windings, and store energy via the generation of magnetic fields in magnetic cores associated with the windings. Power inductors also return the stored energy to the associated electrical circuit as the current through the winding and may, for example, provide regulated power from rapidly switching power supplies. Unlike a power inductor, a transformer is typically not designed to store energy via the generation of magnetic fields. In a transformer, energy storage in the magnetic core effectively amounts to an undesirable, parasitic power loss in the circuitry.
As used herein, the term “non-power inductor,” amongst other things, shall refer to an electromagnetic component provided for filtering purposes in an electrical circuit, and is distinguishable from a power inductor. Such non-power inductors are sometimes referred to as noise suppression components and typically operate on signal lines, as opposed to power lines, in the circuitry. For example, one type of non-power inductor is designed to induce magnetic fields in a magnetic core via current flowing through more than one conductive winding in opposite directions to one another, with the magnetic fields cancelling one another to remove undesirable noise. Unlike a non-power inductor, a transformer is not designed to filter or suppress any aspect of a signal, but rather only to change its magnitude.
Each type of electromagnetic component described above therefore utilizes principles of magnetism and inductance via current flow through electrical conductors, but in different ways to achieve a desired result. The different ways that the principles of inductance and desired results are obtained are reflected by structural differences in the devices that allow such disparate results to occur. As such, neither power inductor components nor non-power inductor components are generally capable of serving as a transformer, nor are transformer components generally capable of serving as power or non-power inductor components. Instead of being interchangeable components, each type of electromagnetic component described above is typically custom designed for a particular application and environment, and even in the same application or environment, power inductors, non-power inductors, and transformers may be provided as discrete components that are used in combination with each component providing its own unique function in the circuitry.
As appreciated by those in the art, the basic function of a transformer is to transfer electrical energy from one circuit to another by electromagnetic induction (transformer action). The electrical energy is always transferred without a change in frequency, but instead involves changes in magnitude of voltage and current between the input (sometimes referred to as the line side) and output side (sometimes referred to as the load side) of the transformer component. A varying magnetic flux is generated in a magnetic core of the transformer in response to a varying current flowing through the primary winding of the transformer. This varying magnetic field and associated electromotive force induces a voltage in the secondary winding(s).
Today's transformers are highly efficient, but still are disadvantaged in some aspects, and improvements in transformer efficiency remain desired but are elusive to transformer component manufacturers in the present state of the art. Inefficiencies of transformer components are primarily attributable to two major types of power loss, namely the core loss and copper loss of the transformer component in operation. Improvements in either core loss and copper loss are desired.
The engineering principles of electromagnetic transformer component design are well known but difficult to apply in some aspects, and as a result the manufacture of electromagnetic transformer components is partly experimental in nature. That is, electromagnetic transformer component manufacturers tend to adopt transformer designs through an iterative process wherein a design may be developed in a theoretical manner, prototypes of the design may be made and tested to evaluate the theoretical design, changes are proposed in view of the test results, and another round of components is made and tested. Such a process may be, and has been, successfully accomplished to provide satisfactory electromagnetic transformer, components meeting desired specifications in certain aspects. To some extent, because of the number of transformer designs that are known for certain applications, the theoretical design step may be omitted and one may instead attempt to simply change an existing transformer design and proceed with testing of prototypes to assess the impact of the change.
Because of the experimental nature of the electromagnetic transformer component design, a design may be achieved that meets a desired specification but is nonetheless sub-optimal. Because the impact of a design change in one aspect of the transformer component design and manufacture to other aspects of the resultant transformer component are not well understood or easy to predict, there is typically some trial and error in arriving at a final transformer design that meets a specification in a desired attribute, but once the specification is met it may have negatively (and unknowingly) affected another performance attribute. This is perhaps even more so in the manufacture of miniaturized transformer components that may be surface mounted to circuit boards in smaller packages and design envelopes to facilitate the manufacture of increasingly smaller and/or increasingly powerful portable electronic devices.
Any transformer component will include at least one pair of electrically conductive coils or windings (i.e., at least one primary winding and at least one secondary winding) and a magnetic core. The basic, theoretical design of the transformer component may proceed with the applicable known relationships including but not limited to those discussed further below, and when connected to an energized electrical circuit), the primary and secondary coils define a number of turns of a winding in a predetermined ratio to achieve a desired step-up or step-down output effect (i.e., to achieve the desired change in magnitude of the transformer output to the transformer input in the circuitry). Transformer components may be varied considerably for different applications by varying the number of turns in the primary and secondary winding(s), the arrangement of the turns of the winding in the magnetic core, the cross sectional area of the turns in the winding, and the properties of the magnetic core materials themselves. The magnetic core may be constructed in one piece or multiple pieces.
A great focus is reflected in the patent literature regarding the development of magnetic core materials that can enhance the performance of electromagnetic transformer components in various applications, and a great variety of different shapes of the magnetic cores is also reflected in the patent literature to achieve desired transformer characteristics. In some cases, separate core pieces are combined to define a magnetic core structure. In other cases, single piece, monolithic cores structures may be provided to embed, encase or surround portions of the primary and secondary windings. The core pieces may be fabricated from granular, magnetic powder materials in a pressing operation, or may alternatively be laminated using layers of pre-formed materials that are joined or united as layers, or still further may be successively formed in layers one upon another in the fabrication of a transformer component. Single phase and multi-phase transformer components may be provided for different electrical power distribution systems.
Regarding the fabrication of the primary and secondary coils for transformer components, copper is and has been predominately the conductive material of choice by electromagnetic component manufacturers. A great deal of different configurations of primary and secondary windings now exist that can be combined with the various different magnetic materials discussed above. Coils and windings fabricated from copper have been effectively utilized to provide adequate transformer performance in combination with a variety of magnetic materials to fabricate the magnetic core including the windings in increasingly smaller packages. Great efforts have been made in recent times, with some success, to manufacture smaller electromagnetic transformer components and/or to increase the power capabilities of transformer components that are already quite small.
However, the use of copper to fabricate the primary and secondary windings of a transformer is believed to impose a ceiling to the development of higher performing transformers and/or to provide comparable performance to existing transformers in smaller package sizes. In other words, the performance potential of copper windings and known magnetic materials is believed to have reached its peak, such that copper-based windings and coils have little more to offer in terms of providing performance improvement and reduction in size of transformer components. Because the demand for further size reduction and miniaturization of transformer components having improved performance has not subsided, a new approach is needed to further improve electromagnetic transformer performance, reduce the size of electromagnetic transformer components, and also to reduce the cost of electromagnetic transformer components.
In order to achieve increased performance while continuing to reduce the size of electromagnetic transformer components that are already quite small, the present invention proposes the use of a composite conductive material for fabricating the primary and secondary coils of the electromagnetic transformer component. In contemplated examples, the composite conductive material has a conductivity that is greater than copper to facilitate still further improvement in performance of transformers. In contemplated embodiments, the composite conductive material may include known conductive metals, or conductive metal alloys, in combination with carbon nanotubes (hereinafter CNTs). Metals such as copper, silver or other metals and alloys, for example, may be enhanced with CNTs to provide superior electrical properties to those of the metal or metal alloys alone (i.e., the metal or metal alloys without CNTs). Using CNT enhanced materials having improved conductivity, copper losses and/or core losses of transformer components may each be improved beyond the capability of conventional transformer component design. That is, transformer components utilizing the CNT enhanced materials, among other things, may operate with reduced total power loss, and hence higher efficiency, than conventionally fabricated transformers.
For example, in various exemplary embodiments the composite conductive material may include 1-99%, or even 1-100%, CNTs by weight to provide varying degrees of improved conductivity. In various contemplated embodiments, the composite conductive material including CNTs may be fabricated into flexible wire conductors that may be wound into a winding for assembly with a magnetic core piece, may be fabricated into layers of material from which conductors may be stamped and shaped into a desired geometric configuration, or may be deposited on substrate materials using known techniques. Single walled CNTs or multiple walled CNTs may be utilized and bonded to or otherwise joined with a metal or metal alloy to provide a composite material having improved conductivity relative to copper and other known metals that have been used to fabricate windings in conventional transformer fabrication. Consortiums of companies and universities have been established to develop such composite conductive materials and their manufacture.
In contemplated embodiments, a ratio of conductivity (β) of the composite conductive material including CNTs relative to that of copper may be within a range of, for example, about 1.1 to about 10.0. Such composite conductive materials are sometimes referred to as ultra-conductive materials due to their greatly increased conductivity relative to pure metals. Such ultra-conductivity is possible using such materials at room temperature, and is expressly contrasted with so-called superconductor materials that require cooling below critical temperatures in order to achieve nearly zero electrical resistance.
The use of new composite ultra-conductive materials to fabricate coils and windings in electromagnetic transformer component fabrication presents both great opportunities and great challenges to electromagnetic component manufacturers. The improved conductivity of the composite conductor materials provides much potential for improving electromagnetic performance, but the implications of its use leave much to be explored. As previously mentioned, because so much of the electromagnetic transformer component knowledge base has been built around copper-based windings, the relation between an improved conductivity of primary and secondary windings and other important attributes of the electromagnetic transformer component are not immediately clear. Thus, the implementation of ultra-conductive materials in transformer components may mean much more significant trial and error experimentation in relation to existing transformer designs, with much expense and associated delay in delivering electromagnetic transformer components that meet desired specifications.
In one aspect of the present invention, a methodology is proposed that facilitates adjusting/selecting electrical parameters associated with transformers, such as the primary winding volt-second product, the magnetizing current, maximum core magnetic field density, and total power loss based on the ratio of conductivity of a selected composite ultra-conductive material to previously used conductive materials such as copper in the fabrication of electromagnetic transformer components. Previously known transformer designs can be effectively adapted for use with ultra-conductive materials with highly reliable results that may avoid the expense and delays of experiments that may otherwise be required to implement ultra-conductive materials in electromagnetic transformer component constructions. Advantageously, the ratio of conductivity can be utilized to fabricate transformers having ultra-conductive material windings with smaller core structures, or alternatively to provide transformers of approximately the same size as existing transformers but with much greater performance capability.
In another aspect, the invention proposes identifying a range (i.e. an upper limit and lower limit), of an effective diameter of a conductor used to fabricate the primary and secondary windings of a transformer, based on the ratio of conductivity of the composite material used to fabricate the coil and an effective diameter of a similarly configured transformer having a conventional metal coil of lower conductivity such as copper. More specifically, the invention proposes to identify upper and lower limits of a ratio of an effective diameter of the improved conductivity conductor relative to a reference conductor (e.g., a copper-based conductor) in a reference transformer. Based on a range defined by the ratio of conductivity of the composite material and coil conductor diameters (or range of ratio of effective diameter of an improved conductivity conductor relative to a reference effective diameter of a reference conductor fabricated from a lower conductivity material such as copper), values of any one of the following exemplary performance parameters may be selected: the primary winding volt-second product, the magnetizing current, maximum core magnetic field density, and total power loss. When one of the parameter values is selected, the remaining ones of the parameters may be adjusted to provide a transformer with desired performance improvements. The magnetic core volume, which relates to the physical size of the completed transformer component may likewise be adjusted to vary the size of the transformer component fabrication including the ultra-conductive composite material.
In one aspect, the present invention utilizes a design approach referencing an existing or established electromagnetic transformer component having certain attributes. That is, reference may be made to a reference transformer that has a reference core fabricated from a selected magnetic material and reference primary or secondary coil fabricated form a conventional conductive metal material such as copper or copper alloy in one example. The conductivity of the copper material may be deemed a reference value of 1. Except as noted below, it is to be understood that the reference transformer and the improved transformer of the present invention have otherwise identical core shapes whether fabricated from the same or different magnetic materials as the core of the reference transformer. For instance, if the transformer of the present invention has a toroid shaped core then the reference transformer is assumed to have a toroid shaped core fabricated from the same magnetic material. For the sake of the present description, any parameter preceded by the word “reference” shall mean the corresponding parameter associated with the reference transformer, unless specified otherwise.
In accordance with some of the contemplated embodiments, the ratio of electrical conductivity (β) of composite conductive material to that of copper used in a reference conductor of copper is greater than 1. The ratio of electrical conductivity (β) defines an upper limit and lower limit of a diameter ratio (δ) of the coil conductor formed of a composite conductive material relative to a diameter of reference coil conductor formed of copper in the reference transformer.
In accordance with the embodiments of the invention, a ratio of conductivity (simply referred to as conductivity (β) in rest of the specification) of the composite material used in a transformer winding of the present invention, relative to that of copper used in reference winding affects the range of diameter of the winding or alternatively defines the range of a ratio of diameter of the conductor forming the transformer winding relative to the diameter of reference transformer's reference conductor forming the transformer winding in the reference transformer. Within this range of the effective diameter ratio (δ), the diameter of the conductors fabricated from ultra-conductive material can be selected to design and fabricate a new and improved transformer according to the present invention. For the matter of simplicity this ratio will be referred to as effective diameter ratio (δ) in the rest of description. Further, for a value of effective diameter ratio (δ) and conductivity (β) of the improved conductivity composite material, some of the parameters of the transformer, such as those described above, can be adjusted to achieve desired performance characteristics of the transformer and optimize the transformer in desired aspects. The word “adjusted,” in addition to its dictionary meaning, is intended to mean selection, alteration, variation or deviation from the respective reference parameters of the reference transformer.
In accordance with the embodiments of the present invention, if the conductivity of composite material used in the transformer windings of the invention is β times that of windings made of copper used in the reference transformer, then a linear dimension ratio of a transformer according to the invention (ξ) may be within the following range defined as function of (β):
Given (ξ) as set forth above, an effective diameter ratio (δ) to construct a transformer according to the invention may be within the following range defined as function of (β) and (ξ):
Within a sub-range
of the entire range
and at a specific value of number of turns of primary winding (n1) defined by a function ξ2δ−2, the primary winding volt-second product (λ1) may be adjustable in a bounded transformer design improvement region having lower limit or boundary value of about 1 and upper limit or boundary value defined by a function ξ4δ−2.
Within a sub-range
of the entire range
and at a specific value of number of turns of primary winding (n1) defined by a function ξ2δ−2, the magnetizing current (Itot) may be adjustable in a bounded transformer design improvement region having a lower limit or boundary value defined by a function
and an upper limit or boundary value defined by a function
Within a sub-range
of the entire range
and at a specific value of number of turns of primary winding (n1) defined by a function ξ2δ−2, the maximum core magnetic field density (Bmax) may be adjustable in a bounded transformer design improvement region having a lower limit or boundary value defined by a function
and an upper limit or boundary value of about 1.
Within a sub-range
of the entire range
and at a specific value of number of turns of primary winding (n1) defined by a function ξ2δ−2, the total power loss (Ptot) may be adjustable in a bounded transformer design improvement region having a lower limit or boundary value defined by a function ξ3-4γδ2γ and an upper limit or boundary defined by a function ξ3.
It must be noted that the bounded transformer design improvement regions described above, wherein the desired values can be adjusted, are envisaged in relation to respective values of the same reference parameters of the reference transformer component. At each effective diameter ratio (δ) within the range described the ratio of the number of turns in the transformer of the present invention relative to the number of turns of each winding in the reference transformer is also determined by a function ξδ−2.
It is to be understood that the material constant (γ) of the magnetic material of the core of the transformer of the present invention is equal to that of the reference core of the reference transformer, and shape of the core of the transformer of the present invention is the same as the reference core of the reference transformer. A volume ratio of the volume of the core of the transformer of the present invention relative to reference volume of the reference core of the reference transformer is defined by a function ξ3.
The “reference transformer” for purposes of the discussion herein is a transformer having a reference primary winding volt-second product, a reference magnetizing current, a reference maximum core magnetic field density, and a reference total power loss. The “reference transformer” also has a reference core volume including a Window Area (WA) to be occupied by a winding, a Mean Length Per Turn (MLT) for each winding, and a Cross-sectional Area (AC) of the core structure. Utilizing the design methodology and fabrication techniques herein, transformers of the invention including the higher conductivity composite material may be readily adapted to have the same or better transformer parameters and characteristics as the reference transformer.
Referring to
As one example, magnetically responsive sheet materials may be provided to include soft magnetic particles dispersed in a binder material, and may be provided as freestanding thin layers or films that may be assembled in solid form, as opposed to semi-solid or liquid materials that are deposited on and supported by a substrate material. Soft magnetic powder particles may be used to make the magnetic composite sheets, including Ferrite particles, Iron (Fe) particles, Sendust (Fe—Si—Al) particles, MPP (Ni—Mo—Fe) particles, HighFlux (Ni—Fe) particles, Megaflux (Fe—Si Alloy) particles, iron-based amorphous powder particles, cobalt-based amorphous powder particles, and other suitable materials known in the art. Combinations of such magnetic powder particle materials may also be utilized if desired. The magnetic powder particles may be obtained using known methods and techniques. Optionally, the magnetic powder particles may be coated with an insulating material.
After being formed, the magnetic powder particles may be mixed and combined with a binder material. The binder material may be a polymer based resin having desirable heat flow characteristics in the layered construction of a magnetic core for higher current, higher power use of the component 100. The resin may further be thermoplastic or thermoset in nature, either of which facilitates lamination of the sheet layers provided with heat and pressure. Solvents and the like may optionally be added to facilitate the composite material processing. The composite powder particle and resin material may be formed and solidified into a definite shape and form, such as substantially planar and flexible thin sheets. Further details of pre-formed magnetic sheet layers are described in the commonly owned U.S. patent application Ser. No. 12/766,382, the entire disclosure of which is hereby incorporated by reference. Insulator sheets may be used in combination with magnetic sheets as desired, or the magnetic sheets may be joined in surface contact without any intervening layers between them.
While two windings 104a and 104b are shown in the example of
In the example shown in
The component 100 shown in
The windings 124a and 124b in the example shown in
The transformer component 120 shown in
A transformer component including the toroidal core 130 shown in
A transformer component including the EE core configuration 140 shown in
A transformer component including the ER core configuration 150 shown in
A transformer component including the UU core configuration 160 shown in
A transformer component including the EPC core configuration 170 shown in
A transformer component including the PC core configuration 180 shown in
A transformer component including the DS core configuration 190 shown in
The transformer component 200 including the I core 202 may be referenced to a reference transformer of a similar configuration, but having copper-based windings, and is but one example of the type of transformer component that may benefit from the design approach described herein. The leads of the primary and secondary windings may be connected to terminal clips that may, in turn, be surface mounted to a circuit board. Alternatively, the leads of the primary and secondary windings formed on the core 202 may be through-hole mounted to a circuit board. In some embodiments, the primary and secondary windings formed on the core 202 need not connect to a circuit board at all, but rather may be terminated to external circuitry using known connections and techniques.
It is understood that the magnetic core and winding configurations in the examples of
In all of the embodiments described above, the windings are fabricated from an ultra-conductive composite material. The composite conductive material utilized may contain 1-99% by weight, or even 100% by weight, of carbon nanotubes (CNTs) along with metal or metal alloys, such as copper, copper alloys, aluminum, or aluminum alloys. The ultra-conductive conductor including the CNTs may include a metal or metal alloy core, and carbon nanotube (CNT) cladding, that is shaped into any of the winding configurations described above and/or assembled with any of the core structures described above. In contemplated embodiments, the conductivity of the composite material may be about 1.1 to about 10 times that of copper. The ultra-conductive material used to fabricate the windings can be made using any suitable process.
Referring to
If a winding wire has a cross-sectional shape other than round, as shown in the example of
A=πr
2
where the diameter D of the circular cross section is equal to twice the radius R. In this example where A is 12 square units, the radius r can be computed and is seen to be 1.95. The diameter of a round cross section having the area of 12 is therefore twice the radius (e.g., 1.95×2) or 3.9. The conductor shown in
Of course, the exemplary conductors and cross sections illustrated in
For example, if each strand has a cross sectional area of 2 square units and seven strands are utilized as shown, the conductor 270 has a cross sectional area of 14. Using the relationship above, the radius r of a circle having an area of 14 square units can be computed. In this example, the radius r is 2.11 and the diameter is therefore twice the radius (e.g., 2.11×2) or 4.22. The conductor shown in
Continuing the example above, if each conductor 270 has a cross sectional area of 14 square units (2 square units per strand times seven strands), the cross sectional area of the entire conductor 280 is seven times the cross sectional area of the conductor strands (e.g., 7 times 14 or 98 square units). The effective diameter of the conductor for the purposes of the invention is then the diameter of a solid round wire with equivalent cross-sectional area of the conductor 280. Using the relationship above, the radius r of a circle having an area of 98 square units can be computed. In this example, the radius is 5.59 and the diameter is therefore twice the radius (e.g., 5.59×2) or 11.18. The conductor 280 shown in
It must be understood that the above examples are non-limiting and other core types can also be used in exemplary embodiments of transformers without departing from the spirit of the invention.
Regardless of which particular type of transformer is desired, including but not limited to the exemplary transformer types described above, electrical efficiency of the transformer is an important consideration to transformer designers and manufacturers. Optimizing efficiency, which correlates to reducing or minimizing power loss of the transformer in use, is of increasing concern to the transformer industry because as transformers are increasingly used in higher power, higher current circuitry, inefficiency in the transformer construction has a more pronounced effect on the circuit. Also, as many portable electronic devices include onboard battery power supplies, power losses attributable to transformers can contribute to a reduced battery life between re-charge events.
As appreciated by those in the art, the core losses in a transformer are in the form of eddy current and hysteresis losses which occur due to the core or in other words are dependent on the material used for making the core. Core loss at a fixed frequency is given by the following equation:
P
fe
=K
fe
B
max
γ
A
c
l
m
where Kfe is a constant of proportionality which depends on the operating frequency, Bmax is the magnetic core's peak flux density, Ac is the cross-sectional area of core, and lm is the mean magnetic path length in the core. The product Ac*lm corresponds to the volume of the core.
The copper losses in a transformer are mainly in the form of the heat produced in the windings of the transformer due to the flow of current through the conductors in each of the windings. The power dissipation through copper loss in a winding of a transformer is given by the following equation.
P=I
2
R
Considering that a transformer necessarily includes more than one winding, the relationship above is duplicated for each winding present. In view of this, the equation above can be seen as follows wherein J represents windings numbered 1 through n.
P
cu,j
=I
j
2
R
j (for Jth winding)
Reference is made to an exemplary text book “Fundamentals of Power Electronics” by Prof. R. W. Erickson and Prof. Dragan Maksimovie from University of Colorado, Boulder to the known and applicable transformer design equations.
In the equation for power dissipation through copper losses in the Jth winding set forth above, the values of resistance R of winding J may be substituted as per the formulae
where ρ is winding wire effective resistivity, Awj is Wire Cross-sectional Area of the Jth winding, and lj is length of the Jth winding. The length of wire of the Jth winding is given by lj=nj (MLT) where nj is number of turns of the Jth winding and MLT is mean length per turn. J=1 refers to the primary winding and J=2, 3, 4 . . . n refers to multiple secondary windings of a number n. A transformer necessarily has at least one secondary winding, J=2, but as noted above may have more than one secondary winding. A single value of MLT is applied to all windings without major loss in numerical precision in the transformer design equations.
Further, the wire cross-sectional area transformer of the Jth winding is given by the following relationship:
where WA is window area of the core, Ku is fill factor of the core considering all of the windings together and αj is the allocation factor of the Jth winding within the window area of the core. As previously mentioned, nj is the number of turns of the Jth winding.
Based on the above equations and substitutions, the copper loss of the Jth winding can be re-written as the following relationship:
The total copper loss of the transformer can likewise be written in the following form:
where value of αj is substituted based from the following equations resulting from the minimization of copper losses.
Further, a flux density in a transformer is related to the applied primary winding voltage according to Faraday's Law. Denote the volt-seconds applied to the primary winding during the positive portion of v1 (t) as λ1.
λ1=∫t1t2v1(t)dt
The above equation causes the flux to change from its negative peak to its positive peak. From Faraday's law, the peak value of the AC component of the flux density is:
Based on the above equation, to attain a given flux density of a transformer, the number of turns in the primary windings may be determined according to the following relationship:
Further, a total magnetizing current of a transformer is given by the following equation for a transformer with up to k windings
The total power loss due to copper in a transformer can be re-written as follows:
where
is the sum of the R.M.S winding currents, refer to winding 1.
Eliminating n1 using result of the previous equation, the following relationship is seen:
and where
which is the value of the optimum Bmax that minimizes total power losses, both copper and core losses.
Substituting the optimum Bmax into the expression for Pcu and Pfe to obtain total power dissipation or loss Ptot in a transformer.
It is apparent from the above equations that while designing any transformer, the parameters such as total power dissipation (or total power loss) Ptot, peak magnetizing current Itot, primary winding volt second product λ1 and the number of turns of the primary winding n1 are the important functional parameters that have major effect on the final design.
As mentioned above, the implications of constructing a transformer using primary and secondary windings fabricated from improved conductivity materials such as those described above are not immediately clear. That is, exactly how the windings fabricated from improved conductivity affects the total power dissipation (or total power loss) Ptot, peak magnetizing current Itot, primary winding volt second product λ1, and the number of turns of the primary winding n1 is, to put it mildly, hardly straightforward. If conventional transformer design and fabrication techniques were applied, much custom design effort and iteration of experimental fabrication and testing would follow as the implications and consequences of utilizing the improved conductivity matters are in some aspects practically unpredictable. The transformer design and fabrication techniques of the invention, however, eliminate such difficulties and facilitate a conversion of existing transformer designs and manufactures to new and improved transformer components with predictable results.
Accordingly, in contemplated embodiments of the invention, the transformer design and fabrication of the invention is based upon an existing transformer design and manufacture, referred to herein as a reference transformer. The reference transformer has a core shape that can be the basis for a new and improved, optimized transformer design and manufacture according to the invention.
For a constant shape magnetic core (i.e., a core having the same shape as the core in the reference transformer), points or values within a transformer design improvement region or regions, as further described below, may be defined and bounded by boundary equations that may be derived from the following equation set where the meaning of n1, Itot, λ1, Bmax, and Ptot has been changed to mean the ratio of the improved transformer parameter to that of the reference transformer parameter.
where (ξ) is within a range defined as function of (β), namely a range of
and wherein
are the upper and lower limits of δ that improvements to Bmax, Itot, λ1, and Ptot can be effected for transformer components according to the present invention.
In order to obtain improvements, relative to the reference transformer, in one or more of the basic functional transformer parameters and optimum values of basic functional transformer parameters, the design and fabrication approach of the present invention proposes use of primary and secondary windings made of an improved, higher conductivity composite material instead of conventional windings made of copper. The composite material has direct impact on the effective diameter of the primary and secondary windings and their number of turns, which in turn affect almost all other basic functional parameters of the transformer.
In accordance with the present invention, the improved, higher conductivity composite material may contain 1-99% by weight carbon nanotube along with metal or metal alloys, such as copper, copper alloys, aluminum, or aluminum alloys. Sometimes the composite material made of copper and carbon nanotube is also referred to as “Ultra Conductive Copper”. The primary and second windings, fabricated from such high conductivity composite material, may include a metal or metal alloy core, and carbon nanotube cladding. In accordance with contemplated embodiments of the present invention, the conductivity of the composite material may be, for example, 1.1-10 times that of copper, which is due to ballistic transport properties of the carbon nanotubes. The primary and secondary windings can be made using any suitable process and provided for use to construct improved transformers of the present invention.
In accordance with exemplary embodiments of transformers according to the present invention, an effective diameter of the winding(s) is mainly dependent on the conductivity of the composite material and other parameters and can offer significant improvements in the winding wire diameter, which in turns, advantageously provides an overall size reduction of the completed transformer component.
In one aspect, the present invention utilizes a design approach referencing an existing or established electromagnetic transformer component having certain attributes. That is, reference may be made to a reference transformer that has a reference core fabricated from a selected magnetic material and a reference coil fabricated form a conventional conductive metal material such as copper or copper alloy in one example. The conductivity of the copper material utilized to fabricate conventional transformer windings may be deemed a reference value of 1. Except as noted below, it is to be understood that the reference transformer and the improved transformer of the present invention have otherwise identical core shapes whether fabricated from the same or different magnetic materials as the core of the reference transformer. For instance, if the transformer of the present invention has a toroid shaped core then the reference transformer is assumed to have a toroid shaped core fabricated from the same magnetic material. For the sake of the present description, any parameter preceded by the word “reference” shall mean the corresponding parameter associated with the reference transformer, unless specified otherwise.
In accordance with the embodiments of the present invention, a ratio of conductivity (simply referred to as conductivity (β) in rest of the specification) of the composite material used in a transformer winding (e.g., the windings 104a and 104b shown in the
In accordance with exemplary embodiments of the present invention, if the conductivity of composite material used in the transformer windings of the present invention is β times that of windings made of copper used in then reference transformer, then the effective diameter ratio (β) may be within a range of
and the linear dimension ratio (ξ) can be within a range
Within a sub-range
of the entire range
and at a specific value of number of turns of primary winding (n1) defined by ξ2δ−2, the primary winding volt-second product (λ1) is adjustable in a bounded region having lower limit about 1 and upper limit defined by a function ξ4δ−2. The magnetizing current (Itot) is adjustable in a bounded region having lower limit defined by a function
and upper limit defined by a function
The maximum core magnetic field density (Bmax) is adjustable in a bounded region having lower limit defined by a function
and upper limit about 1. The total power loss (Ptot) is adjustable in a bounded region having lower limit defined by a function ξ3-4γδ2γ and upper limit defined by a function ξ3. It must be noted that the regions of improvement, wherein the desired values can be adjusted, are envisaged in relation to respective values of the same reference parameters. At each effective diameter ratio (δ) within the range the ratio of the number of turns relative to the number of turns of each transformer winding in the reference transformer is determined by the function ξδ−2.
It is to be understood that the material constant (γ) of the magnetic material of the transformer core of the invention is equal to that of the reference core of the reference transformer, and shape of the transformer core of the present invention is the same as a reference core of the reference transformer and a volume ratio of the volume of the transformer core of the present invention relative to a reference volume of the reference core of the reference transformer is defined by a function ξ3.
The limits and functions referred to above are derived from relationships such as those described above and are illustrated in graphical form in
of the entire range
More specifically,
of the entire range
and at a specific value of number of turns of primary winding (n1) defined by ξ2δ−2. In this sub-range, the primary winding volt-second product (λ1) is adjustable in a bounded improvement region 402 having lower limit defined by a function
and an upper limit defined by a function ξ4δ−2. The magnetizing current (Itot) is adjustable in an improvement region 404 having lower limit about 1 and upper limit defined by a function
The maximum core magnetic field density (Bmax) is adjustable in a bounded improvement region 406 having lower limit defined by a function
and upper limit about 1. The total power loss (Ptot) is adjustable in a bounded improvement region 408 having lower limit defined by a function
and an upper limit defined by a function ξ3. At each effective diameter ratio (δ) within the range the ratio of the number of turns relative to the number of turns of each transformer winding in the reference transformer is determined by the function ξδ−2.
The improvement regions 401, 402, 403, 404, 405, 406, 407 and 408 shown in
However, if the diameter ratio (δ) is selected to be outside the limits of the bounded regions 401, 402, 403, 404, 405, 406, 407 and 408 shown (i.e., outside the broken boundary line values corresponding to the functions and values described and shown for each region), the resultant transformer component including the improved higher conductivity composite material will be less desirable than the corresponding value of the reference transformer in at least one aspect. As one example, a transformer component may be constructed using the improved higher conductivity material to fabricate its windings that actually performs with higher power losses than the reference transformer using certain diameter ratios (δ) that are outside the regions 407 and 408. That a higher conductivity composite material may be utilized to provide a transformer with higher power losses than the reference transformer utilizing a conventional conductive material having a lower conductivity (but otherwise similar design) is perhaps a counterintuitive result that is preferably avoided. Thus, the bounded regions shown provide a range of values, within and including the boundaries shown in which the corresponding values of a transformer component of the present invention constructed with values (β) and (δ) is the same or better in terms than the corresponding values of the reference transformer.
In accordance with certain contemplated embodiments of the invention, it is possible to confine a reduction in size of the transformers that would occur as a result of use of the composite material winding, to the height of the transformer. In accordance with the embodiments described above, it is assumed that when the core volume (V) is improved (i.e., reduced) such improvement happens proportionally for all the sides or dimensions of the core structure (i.e., all the dimensions of the magnetic core structure shrink proportionally relative to the reference core while the core structure shape and contour remains the same).
In accordance aspects of the present invention, and as shown in
and the core height ratio (χ) can be within a range
Within a sub-range of the effective diameter ratio from χ to
of the entire range
and at a specific value of number of turns of primary winding (n1) defined by χδ−2, the primary winding volt-second product (λ1) is adjustable in a bounded region 601 having lower limit about 1 and upper limit defined by a function χδ−2. The magnetizing current (Itot) is adjustable in a bounded region 603 having lower limit defined by a function
and an upper limit defined by a function
The maximum core magnetic field density (Bmax) is adjustable in a bounded region 605 having lower limit defined by a function χ−1δ2 and upper limit about 1. The total power loss (Ptot) is adjustable in a bounded region 607 having lower limit defined by a function
and upper limit defined by a function
it must be noted that the regions 601, 603, 605, 607 of improvement, wherein the desired values can be adjusted, are envisaged in relation to respective values of the same reference parameters in the reference component. At each effective diameter ratio (δ) within the range the ratio of the number of turns relative to the number of turns of each winding in the reference transformer is χδ−2.
Similarly, and as shown in
of the entire range
and at a specific value of number of turns of primary winding (n1) defined by χδ−2, the primary winding volt-second product (λ1) is adjustable in a bounded region 602 having lower limit defined by a function
and upper limit defined by a function χδ−2. The magnetizing current (Itot) is adjustable in a bounded region 604 having lower limit about 1 and upper limit defined by a function
The maximum core magnetic field density (Bmax) is adjustable in a bounded region 606 having lower limit defined by a function
and upper limit about 1. The total power loss (Ptot) is adjustable in a bounded region 608 having lower limit defined by a function
and upper limit defined by a function
At each effective diameter ratio (δ) within the range the ratio of the number of turns relative to the number of turns of each winding in the reference transformer is χδ−2.
The improvement regions 601, 602, 603, 604, 605, 606, 607 and 608 shown in
However, if the diameter ratio (δ) is selected to be outside the limits of the bounded regions 601, 602, 603, 604, 605, 606, 607 and 608 shown (i.e., outside the broken boundary line values corresponding to the functions and values described and shown for each region), the resultant transformer component including the improved higher conductivity composite material will be less desirable than the corresponding value of the reference transformer in at least one aspect. That a higher conductivity composite material may be utilized to provide a transformer that is less desirable than the reference transformer utilizing a conventional conductive material having a lower conductivity (but otherwise similar design) in certain aspects is perhaps a counterintuitive result that is preferably avoided. Thus, the bounded regions shown provide a range of values, within and including the boundaries shown in which the corresponding values of a transformer component of the present invention constructed with values (β) and (δ) is the same or better in terms than the corresponding values of the reference transformer.
The transformer design and fabrication approach of the present invention improves the overall performance of the transformer in relation to a reference transformer, where by using windings made of composite material having carbon nanotube, basic functional parameters of the transformers such as λ1, Itot, Bmax, and Ptot can be improved. Using either of the bounded improvement region graphs shown in
The technical advantages of the transformer design and fabrication in terms of overall size reduction is apparent in
In accordance with exemplary embodiments of the present invention, transformer components employing the concepts described above may be designed and manufactured. As described above, the improvement in the electromagnetic component of the present invention is realized in terms of ratios relative to the corresponding parameter that describes the reference transformer. As explained above, the transformer parameters include Bmax which represents the ratio of the peak magnetic flux density of the transformer relative to that of the reference transformer, Ptot which represents the ratio of total power loss of the transformer relative to that of the reference transformer, Itot which represents the ratio of total magnetizing current of the transformer relative to that of the reference transformer, λ1 which represents the ratio of the volt-second product of the transformer relative to that of the reference transformer, nj which represents the ratio of the number of turns of the respective windings of the transformer relative to those of the reference transformer, and δ represents the ratio of the wire diameter of each winding of the transformer relative to the corresponding wire diameter of the corresponding winding of the reference transformer.
While designing an electromagnetic transformer component in accordance with the present invention, a desired core size improvement is first determined in terms of either a linear reduction ratio ξ where
or a core height reduction ratio χ where
The linear reduction ratio ξ applies to scenarios described above wherein all dimensions of a core are reduced proportionally relative to the reference transformer, whereas the height reduction ratio applies to scenarios described above wherein only the height dimension is decreased. In other words, the height reduction ratio scenario involves a transformer component having a reduced profile as discussed above but having the same footprint as the reference transformer, whereas the linear reduction scenario involves both a reduced footprint and profile relative to the reference transformer.
The upper and lower limits of effective diameter ratio 6 is then determined and a performance parameter value of one of the performance parameters (as described above) is chosen or selected to be achieved in the improved transformer of the invention. The value of the performance parameter is selected such that there exists at least one effective diameter ratio within the specified upper and lower limits for the selected value of the performance parameter.
Once one of the transformer parameters is selected to match the reference transformer, the remaining performance parameters are determined which fall within the respective performance improvement regions and correspond to the selected value of effective diameter ratio (δ) and the one parameter.
For instance, in one example a transformer designer first chooses one of the parameters and a value (δ) for which the new design is to be improved. Suppose one chooses Ptot=0.85 so that the improved transformer of the present invention will operate with 85% of the power losses of the reference transformer design on which it is based. This value (Ptot=0.85) may be plotted as a horizontal line represented by reference numeral “415” in
In accordance with an alternative embodiment, a transformer design may first choose or select a value of effective diameter ratio δ. This is shown by a vertical straight line “417” in
At step 2301, a reference transformer (or reference transformers) is selected. The reference transformer is a transformer having a reference core made of magnetic material and reference windings made of copper.
At step 2303, a composite conductive material having a conductivity greater than a conductivity of the reference conductor material is provided. The composite material may be any material described above or another material of a greater conductivity than the conductor material utilized in the reference component(s). Varying degrees of conductivity may be provided by different formulations of composite materials. The composite materials may be provided in flexible wire form, sheet form, or in a form that may be deposited on a substrate material. In some embodiments, the step of providing the composite material at step 2303 may include the step of manufacturing the composite conductive material. In other embodiments, the step of providing the composite material may include acquiring the material from another party, whether a manufacturer or a distributor, and making the composite material available for electromagnetic component fabrication.
At step 2305 a ratio is determined of electrical conductivity (p) of the composite conductor provided at step 2303 to the electrical conductivity of the reference conductor material of the reference component. While illustrated as a separate step, step 2303 and step 2305 may in practice be one and the same in certain embodiments. That is, one may select the composite material provided at step 2303 to achieve a desired conductivity ratio for purposes of step 2305. Alternatively, a composite conductive material could be provided and analyzed to determine its conductivity, which can then be used to determine the conductivity ratio.
As shown at step 2307, a new core size is determined with permissible range of values of linear dimension ratio (ξ) or core height ratio (χ) based on determined ratio of electrical conductivity (β). Based on the design requirement, the transformer designer may determine the new core size for the improved transformer of the invention utilizing the improved conductivity material.
As shown at step 2309, an upper limit and lower limit (or range) of an effective diameter ratio of the composite conductive material may be determined. The upper and lower limits are determined from the perspective of identifying a range of values between the limits in which a component parameter may be improved relative to the reference transformer. The determination of the range of an effective diameter ratio (δ) is made in view of the determined ratio of electrical conductivity (β).
As shown at step 2311 one of the component parameter values (primary winding volt-second product, magnetizing current, maximum core magnetic field density, and total power loss), is selected within one of the improvement regions such as those shown in
The bounded improvement regions may be developed for each respective component parameter or component performance parameters such as those described in the embodiments above, or using other parameters as desired. The improvement regions may be defined for each parameter of interest to include functions of the ratio of electrical conductivity (β) discussed above, which also relates to the effective diameter ratio (δ) as described above. The regions of values may be defined by a function of the ratio of electrical conductivity (β) and the effective diameter ratio (δ) as described above. It is understood that graphs such as those shown in
At step 2313, the at least one effective diameter ratio is selected. The selected effective diameter value is made with an objective, as described above, of maintaining or improving a parameter of the reference transformer component(s). In some embodiments step 2313 may be consolidated with steps 2303 and 2305. For example, only one composite conductor with a given effective diameter may be provided at step 2303, such that the effective diameter at step 2313 may be effectively dictated by the composite material provided.
As shown at step 2315, a number of turns of the windings fabricated from the improved conductivity material (e.g., the ultra-conductive material discussed above) is determined relative to the copper windings in the reference transformer component.
Once the selections at steps 2311 and 2313 are completed, the remaining parameters of the improved transformer component design are now determined at step 2317.
At step 2319, a core structure is fabricated for the improved transformer of the present invention. In embodiments wherein the core volume is changed from the reference component, the core volume may be proportionally changed (decreased) in all dimensions relative to the reference component while otherwise retaining the same shape as the reference transformer. In certain embodiments, however, only the winding area (WA) in the core may be adjusted relative to the reference conductor while the footprint and the component height remain the same as discussed above. As discussed above, the core structure may be formed in one piece or multiple pieces having the same or different shape.
At step 2321, composite material windings (as described above) are provided for each winding that has the selected at least one effective diameter ratio relative to the corresponding reference transformer windings.
At step 2323, primary and secondary windings are fabricated from the composite material provided at step 2303, having the conductivity determined at step 2305, and having the effective diameter ratio determined at step 2313. The windings are formed with a number of turns required at step 2315 to achieve the desired improvement. Any of the techniques and winding configurations described above may be utilized to construct the winding at step 2323.
At step 2325, the core and windings are assembled to complete the electromagnetic component exhibiting the parameter values selected at steps 2313 and 2315, and 2317. In some embodiments, the steps of 2311, 2313, 2315, 2317, 2319, 2321, and 2323 may occur at the same time. As one such example, in a laminated component construction including magnetic sheets, the magnetic sheets may be pressed around the windings to fabricate the magnetic core structure. As another example, in a laminated component construction including layers successively formed on a preexisting layer, the windings may simultaneously be formed with the magnetic core structure.
At step 2327, the completed transformer component may be connected to circuitry and operated at predefined values of performance parameters associated with core and windings.
While an exemplary method 2300 has been described, the method and process steps may be performed using less than all of the steps shown, with additional steps included and/or the method and process steps may be performed in a different order. Various adaptations are possible within the scope of the pending claims.
At step 2401, a reference transformer (or reference transformers are selected. The reference transformer is a transformer having reference core made of magnetic material and reference windings made of copper.
At step 2403, am improved conductivity composite conductive material having a conductivity greater than a conductivity of the reference conductor material is provided. The improved conductivity material may be any material described above or another material of a greater conductivity than the conductor material utilized in the reference component(s). Varying degrees of higher conductivity may be provided by different formulations of composite materials. The composite materials may be provided in flexible wire form, sheet form, or in a form that may be deposited on a substrate material. In some embodiments, the step of providing the composite material at step 2403 may include the step of manufacturing the composite conductive material. In other embodiments, the step of providing the composite material may include acquiring the material from another party, whether a manufacturer or a distributor, and making the composite material available for electromagnetic component fabrication.
At step 2405 a ratio is determined of electrical conductivity (β) of the composite conductor provided at step 2403 to the electrical conductivity of the reference conductor material of for a reference component. While illustrated as a separate step, step 2403 and step 2405 may in practice be one and the same in certain embodiments. That is, one may select the composite material provided at step 2403 to achieve a desired conductivity ratio for purposes of step 2405. Alternatively, a composite conductive material could be provided and analyzed to determine its conductivity, which can then be used to determine the conductivity ratio.
As shown at step 2407, a new core size is determined with permissible range of values of linear dimension ratio (ξ) or core height ratio (χ) based on determined ratio of electrical conductivity (β). Based on the design requirement, the transformer designer determines the new core size.
As shown at step 2409, an upper limit and lower limit (or range) of an effective diameter ratio of the composite conductive material may be determined. The upper and lower limits are determined from the perspective of identifying a range of values between the limits in which a transformer component parameter may be improved relative to the reference transformer. The determination of the range of an effective diameter ratio (δ) is made in view of the determined ratio of electrical conductivity (β).
At step 2411, the at least one effective diameter ratio is selected based on the improvement(s) desired by the transformer designer. The selected effective diameter ratio is made within the upper and lower limits of the effective diameter ratio.
As shown at step 2413, a number of turns of the ultra-conductive windings in the transformer of the invention are determined relative to the copper windings in the reference transformer component. The number of turns are determined for the selected value of effective diameter ratio.
As shown at step 2415 one of the component parameter values (e.g., primary winding volt-second product, magnetizing current, maximum core magnetic field density, and total power loss), is selected within improvement regions such as those shown in
The design improvement regions may be developed for each respective component parameter or component performance parameters such as those described in the embodiments above, or other parameters as desired. The design improvement regions may be defined for each parameter of interest to include functions of the ratio of electrical conductivity (β) discussed above, which also relates to the effective diameter ratio (δ) as described above. The regions of values may be defined by a function of the ratio of electrical conductivity (β) and the effective diameter ratio (δ) as described above. It is understood that graphs such as those in
Once the selections at steps 2411 and 2415 are made, the remaining parameters of the component design are now determined at step 2417 which lie within their respective regions of performance improvement.
At step 2419, a core structure is fabricated. In embodiments wherein the core volume is changed from the reference component, the core volume may be proportionally changed (decreased) in all dimensions relative to the reference component while otherwise retaining the same shape as the reference transformer. In certain embodiments, however, only the winding area (WA) in the core may be adjusted relative to the reference conductor while the footprint and the component height remain the same as discussed above. As discussed above, the core structure may be formed in one piece or multiple pieces having the same or different shape.
At step 2421, composite material windings (as described above) are provided for each winding that has the selected at least one effective diameter ratio relative to the corresponding reference transformer windings.
At step 2423, primary and secondary windings are fabricated from the composite material provided at step 2403, having the conductivity determined at step 2405, and having the effective diameter ratio determined at step 2411. The windings are formed with a number of turns required at step 2413 to achieves the desired improvement. Any of the techniques and winding configurations described above may be utilized to construct the winding at step 2323.
At step 2425, the core and winding are assembled to complete the electromagnetic component exhibiting the parameter values selected at steps 2411 and 2415, and 2417. In some embodiments, the steps of 2411, 2413, 2415, 2417, 2419, 2421, and 2423 may occur at the same time. As one such example, in a laminated component construction including magnetic sheets, the magnetic sheets may be pressed around the windings to fabricate the magnetic core structure. As another example, in a laminated component construction including layers successively formed on a preexisting layer, the windings may simultaneously be formed with the magnetic core structure. The component completed may be configured as a transformer.
At step 2427, the completed component (i.e. the transformer) is operated at predefined values of performance parameters associated with core and windings.
While an exemplary method 2400 has been described, the method and process steps may be performed using less than all of the steps shown, with additional steps included and/or the method and process steps may be performed in a different order. Various adaptations are possible within the scope of the pending claims.
Electromagnetic components such as transformers formed according to the present invention may therefore be readily obtained in view of the teachings of the present disclosure, without necessarily undertaking the laborious task of theoretical component design, and without necessarily incurring expensive and time consuming experimentation of new component constructions. Improved transformers having better performance may be provided at relatively low cost while continuing to reduce the physical package size of transformers and/or improving component performance in different aspects or a combination of aspects. In view of the inventive design approach described above, a vast number of copper-based transformer components can be readily translated to new and improved transformer devices using ultra-conductive composite materials. Transformer designs can rather easily be optimized with respect to one or more of a plurality of parameters. The benefits of such components according to the invention are perhaps most significant for miniaturized power transformer components used in circuit boards of increasingly smaller and powerful electronic devices, but the benefits accrue to other types of transformers as well.
The benefits and advantages of the inventive concepts are now believed to have been amply illustrated in relation to the exemplary embodiments disclosed.
An embodiment of an electromagnetic transformer component has been disclosed including: a magnetic core; and at least two conductors fabricated from a composite conductive material including carbon nanotubes, the at least two conductors respectively shaped to define a primary winding and at least one secondary completing a respectively different number of turns to provide a step up or step down current or voltage output when the at least two conductors are assembled with the magnetic core and connected to electrical circuitry; wherein the at least two conductors respectively have a cross sectional area that is determined relative to at least two reference conductors in a reference transformer component.
Optionally, a ratio of an electrical conductivity (β) of the at least two conductors to an electrical conductivity of the at least two reference conductors in the reference electromagnetic component is greater than 1; and the ratio of electrical conductivity (β) may define an upper limit and a lower limit of an effective diameter that corresponds to the cross sectional area of the at least two conductors. The transformer component may be configured to operate with performance parameters selected from the group of a primary winding volt-second product, magnetizing current, maximum core magnetic field density, total power loss, and a number of turns for the windings when connected to electrical circuitry; and at least one of the performance parameters may be within bounded improvement regions defined by at least one function of a ratio of the electrical conductivity (β), an effective diameter ratio (δ) of the at least two conductors relative to the at least two reference conductors, a linear dimension ratio (ξ) of the magnetic core relative to a reference core, and a material constant (γ) of the magnetic material of the core. A performance value of at least one other performance parameter may be selected to be within a respective bounded improvement region defined by the electrical conductivity (β), the effective diameter ratio (δ), the linear dimension ratio (ξ), and the material constant (γ) of the magnetic material of the core.
Optionally, the ratio of electrical conductivity (β) may be within the range of about 1.1 to about 10. The composite material including carbon nanotubes may be an ultra-conductive copper composite material. The linear dimension ratio (ξ) of the conductor relative to the reference conductor may be within a range defined between and including a lower boundary value defined by a function β(−1/8) and an upper boundary value of about 1. The effective diameter ratio (δ) of the conductor relative to the reference conductor may be within a range defined between and including an upper boundary value defined by a function ξ2 and a lower boundary value of about β(−1/4).
The effective diameter ratio (δ) of the conductor relative to the reference conductor may optionally be within a range defined between and including a lower boundary value defined by a function
and an upper boundary value defined by a function ξ2. A value of the number of turns the primary winding and at least one secondary winding, relative to the reference transformer, may be defined by a function ξ2δ−2. A value of the primary winding volt-second product is within a bounded improvement region defined between and including a lower boundary value of 1 and an upper boundary value defined by a function ξ4δ−2. A value of magnetizing current may be within a bounded improvement region defined between and including a lower boundary value defined by a function
and an upper boundary value defined by a function
A value of maximum core magnetic field density may be within a bounded improvement region defined between and including a lower boundary value defined by a function
and an upper limit of 1. A value of total power loss may be within a bounded improvement region defined between and including a lower boundary value defined by a function δ3-4γδ2γ and an upper boundary value defined by a function ξ3.
An effective diameter ratio (δ) of the conductor relative to the reference conductor may be within a range defined between and including a function
and a function
A value of the number of turns for the primary and secondary winding, relative to the reference conductor, may be defined by a function ξ2δ−2. A value of the primary winding volt-second product may be within a bounded improvement region defined between and including a lower boundary value defined by a function
and an upper boundary value defined by a function ξ4δ−2. A value of magnetizing current may be within a bounded improvement region defined between and including a lower boundary value of 1 and an upper boundary value defined by a function
A value of maximum core magnetic field density may be within a bounded improvement region defined between and including a lower boundary value defined by a function
and an upper boundary value of 1. A value of total power loss may be within a bounded improvement region defined between and including a lower boundary value defined by a function
and an upper boundary value defined by a function ξ3.
The magnetic core optionally has a shape that is the same as that of a reference core of the reference transformer and a volume ratio of the volume of the core relative to reference volume of the reference core of the reference transformer is defined by a function ξ3. The transformer component may be configured to operate with performance parameters selected from the group of a primary winding volt-second product, magnetizing current, maximum core magnetic field density, total power loss, and a number of turns for the of windings when connected to electrical circuitry; and at least one of the performance parameters may be within bounded improvement regions defined by and including at least one function of the ratio of the electrical conductivity (β), an effective diameter ratio (δ) of the conductor relative to the reference conductor material, a core height reduction ratio (χ) of the magnetic core relative to a reference core, and a material constant (γ) of the magnetic material of the core. The material constant (γ) of the magnetic material of the core may be equal to that of the reference core of the reference transformer. The core height ratio (χ) may be within a range defined between and including a function β(−1/3) and 1. The effective diameter ratio (δ) may be within a range defined between and including a function (χ/β)(1/4) and χ. The effective diameter ratio (δ) may within a range defined by and including a function χ and
A number of turns value for the primary and secondary windings may be defined by a function χδ−2. A value of the primary winding volt-second product may be within a bounded improvement region defined between and including a lower boundary value of 1 and an upper boundary value defined by a function χδ−2. A value of magnetizing current may be within a bounded improvement region defined between and including a lower boundary value defined by a function
and an upper boundary value defined by a function
A value of maximum core magnetic field density may be within a bounded improvement region defined between and including a function χ−1δ2 and 1. A value of total power loss may be within a bounded improvement region defined between and including a function
and a function
The effective diameter ratio (δ) may be within a range defined by and including a function
and a function
A value of the number of turns for the primary and secondary windings, relative to the reference transformer, may be defined by a function χδ−2. A value of the primary winding volt-second product may be within a bounded improvement region defined between and including a function
and a function χδ−2. A value of magnetizing current may be within a bounded improvement region defined between and including 1 and a function
A value of maximum core magnetic field density may be within a bounded improvement region defined between and including a function
and 1. A value of total power loss may be within a bounded improvement region defined between and including a function
and a function
An embodiment of a method of manufacturing an electromagnetic transformer component has been disclosed including: selecting a reference transformer having reference core made of a reference magnetic material and reference windings made of a reference conductor material; providing a composite conductive material having a conductivity greater than a conductivity of the reference conductor material; determining a ratio of electrical conductivity (β) of the composite conductor to the electrical conductivity of the reference conductor material; determining a new core size with permissible range of values of linear dimension ratio (ξ) or core height ratio (χ) based on the determined ratio of electrical conductivity (β); and based on the determined ratio of electrical conductivity (β), determining an upper limit and lower limit of an effective diameter ratio (δ) of the composite conductive material relative to the reference conductor material.
Optionally, the transformer component may be configured to operate based on performance parameters selected from the group of a primary winding volt-second product, magnetizing current, maximum core magnetic field density, total power loss, and a number of turns for the windings when connected to electrical circuitry; and the method may further include selecting a value of one of the performance parameters within a respective bounded region of improvement values defined by a function of at least one of the ratio of electrical conductivity (β) and the effective diameter ratio (δ).
The method may also include: selecting an effective diameter ratio within the determined upper and lower limit of the effective diameter ratio (δ); determining values of the remaining performance parameters; fabricating a magnetic core; fabricating at least two windings from the provided composite conductive material having an effective diameter, the effective diameter being determined based on the effective diameter ratio (δ); and assembling the at least two windings with the fabricated magnetic core and the fabricated windings having the selected number of turns. Selecting one of the performance parameters from one of the respective bounded region of improvement values may include selecting from each bounded region of values that is defined by at least one boundary value that is a function of at least one of the ratio of electrical conductivity (β) and the effective diameter ratio (δ).
The method may include fabricating an transformer component having a selected effective diameter and the selected conductivity value to achieve at least one of the selected performance parameters. The transformer component may be configured to operate based on performance parameters selected from the group of a primary winding volt-second product, magnetizing current, maximum core magnetic field density, total power loss, and a number of turns for the windings when connected to electrical circuitry; and the method may further comprise selecting an effective diameter ratio within the determined upper and lower limit of the effective diameter ratio (δ).
The method may also include determining a number of turns value based on the selected effective diameter ratio (δ). The method may also include: selecting a value of one of the performance parameters within a respective bounded region of improvement values defined by a function of at least one of the ratio of electrical conductivity (β) and the effective diameter ratio (δ); determining values of the remaining performance parameters; fabricating a magnetic core; fabricating at least two windings from the provided composite conductive material having an effective diameter, the effective diameter being determined based on the effective diameter ratio (δ); and assembling the at least two windings with the fabricated magnetic core and the fabricated windings having the selected number of turns. Selecting at least one of the performance parameters from one of the respective bounded regions of improvement values may include selecting from each bounded region of improvement values is defined by at least one limit that is a function of at least one of the ratio of electrical conductivity (β) and the effective diameter ratio (δ).
The method may include fabricating an electromagnetic transformer component having the selected effective diameter and the selected conductivity value to achieve at least one of the selected performance parameters.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
