Patent Description:
Inductively-coupled power transfer is gaining acceptance in military and commercial applications. Evolving undersea systems, for example, serve a variety of military and commercial applications including data communication networks, object sensing and detection systems, and vehicle hub systems. To achieve these wide-ranges of applications, conventional inductively-coupled power transfer devices aim to employ an uncomplicated and robust power interface to facilitate practical energy transfer.

<CIT> and <CIT> disclose designs for coreless printed circuit board transformers designed for operation in power transfer applications, in which shielding is provided by a combination of ferrite plates and thin conductive sheets. <CIT> discloses a multilayered ceramic electromagnetic coupler apparatus including coils formed on ceramic substrates. The coils are laminated and have insulting layers between the ceramic substrates, a modulator section having an oscillator and a demodulator for outputting a transmitted signal. <CIT> discloses an electromagnetic coupling device using laminated ceramic substrate.

The present invention provides an inductive wireless power transfer device as recited in claim <NUM>. Optional features are recited in the dependent claims. The present invention also provides a method of increasing power transfer in an inductive wireless power transfer device as recited in claim <NUM>.

Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein. For a better understanding of the invention with the advantages and the features, refer to the description and to the drawings.

Traditional wireless energy devices were typically constructed as power transformers that required several primary-secondary interfaces such as, for example, center and outer core legs. Inductively-coupled wireless devices have been developed which reduced the number primary-secondary interfaces needed to transfer energy. Inductively-coupled wireless devices are typically required to provide high-voltage (HV) withstanding capability in the range of hundreds to thousands of volts. In addition, inductively-coupled wireless devices are typically separate from the primary winding and secondary winding coils from one another by a distance (h), while providing a magnetic coupling factor (k) that is approximately proportion to a ratio (r/h being about <NUM>) based on the radius of wound coils with respect to the of the coil separation distance (h).

As mentioned above, however, conventional inductively-coupled power transfer devices do not provide effective voltage protection measures capable of withstanding high voltage events. For example, conventional inductively-coupled power transfer devices to date do not combine a voltage withstanding capability with sufficient magnetic coupling factor (k) because they rely only on air gaps to introduce voltage isolation regions between the primary and secondary energy transfer coils. The magnetic coupling factor is inversely proportional to the coil separation distance while power transfer efficiency is approximately proportional to the magnetic coupling factor. For this reason, using only air gaps does not allow to simultaneously provide efficient transfer power and effectively protect these conventional inductively-coupled power transfer devices from high voltage events such as, for example, lightning strikes, electromagnetic pulses, etc..

Various non-limiting embodiments described herein provide an inductive wireless HV power transfer device with high efficiency that employs a multi-section HV isolator, which includes one or more individual isolator sections interposed between a primary energy coil (i.e., primary winding) and a secondary energy coil (i.e., secondary winding). High-voltage exists between the primary energy coil and ground while the secondary energy coil is at or near (tens of volts difference at the most) to ground. The multi-section HV isolator further includes a magnetic material arranged between the primary and secondary windings to form one or more intermediate cores. The implementation of the multi-section HV isolator allows inductive wireless power transfer device to achieve a substantial improvement in power transfer efficiency compared to conventional devices, while maintaining necessary HV isolation for providing HV protection capabilities.

In at least one non-limiting embodiment, the multi-section HV isolator includes two individual sections, which are coupled together to surround around a hollowed volume, i.e., cavity. An intermediate ferrite core is disposed inside the cavity such that the intermediate ferrite core is encased in a middle core portion of the multi-section HV insulator. The multi-section HV isolator is further divided into a plurality of ring-shaped insulator sections that extend radially from a middle core portion. The insulator sections are separated from one another by an air gap or void, which achieves a sufficient creepage distance to further improve HV isolation. In yet another non-limiting embodiment, the multi-section insulator is constructed as an alternating stacked arrangement of individual insulator layers and magnetic core layers. In any of the aforementioned examples, an inductive wireless power transfer device is provided which improves voltage protection, while still facilitating inductive energy coupling to effectively transfer power in an efficient manner.

With reference now to <FIG> and <FIG>, an inductive wireless power transfer device <NUM> is illustrated according to a non-limiting embodiment. The inductive wireless power transfer device <NUM> includes a primary winding assembly <NUM> and a secondary winding assembly <NUM>. The primary winding assembly <NUM> and the secondary winding assembly <NUM> are separated from one another by a multi-section isolator <NUM>, which extends along an axis (Z) to define a separation distance (h1). The distance (h1) between the primary winding assembly <NUM> and the secondary winding assembly <NUM> can range, for example, from about <NUM> inches (<NUM>) to about <NUM> inches (<NUM>).

The inductive wireless power transfer device <NUM> further includes a first magnetic core cap <NUM> on the primary winding assembly <NUM> and a second magnetic core cap <NUM> on the secondary winding assembly <NUM>. In at least one embodiment, the first magnetic core cap <NUM> and the second magnetic core cap <NUM> are shaped as discs, and are disposed directly against the primary winding and secondary winding assemblies <NUM> and <NUM>, respectively. The first and second magnetic core caps <NUM> and <NUM> facilitate magnetic coupling between the primary winding assembly <NUM> and the secondary winding assembly <NUM> as described in greater detail below.

The primary winding assembly <NUM> includes a first safety shield layer <NUM>, a first primary shield <NUM>, a primary winding <NUM>, and a primary winding insulator layer <NUM>. The first safety shield layer <NUM> is interposed between the first magnetic core cap <NUM> and the primary shield <NUM>. The primary winding <NUM> and the primary winding insulator layer <NUM> are surrounding or encased within the first primary winding assembly <NUM> using polyamide or other comparable insulating materials.

The primary winding <NUM> can be formed as a spiral-shaped trace composed of an electrically conductive material such as, for example, copper. The primary winding insulator layer <NUM> is formed directly on the first primary shield <NUM>, while the primary winding <NUM> is formed directly on the primary winding insulator layer <NUM>. The first safety shield <NUM>, the primary shield <NUM> and the primary winding <NUM> each have terminals that extend from the first primary winding assembly <NUM> to provide access to an external electrical connection.

The secondary winding assembly <NUM> includes a secondary shield <NUM>, a secondary winding <NUM>, and a secondary winding insulator <NUM>. Unlike the primary winding, no insulator layer should be interposed between the second magnetic core cap <NUM> and the secondary shielding <NUM> because the case of the secondary shield is connected to ground.

The secondary winding <NUM> and the secondary winding insulator layer <NUM> are surrounded or encased within the secondary shield <NUM>. The secondary winding <NUM> can be formed as a spiral-shaped traced composed of an electrically conductive material such as, for example, copper. The secondary winding insulator layer <NUM> is formed directly on the secondary shield <NUM>, while the secondary winding <NUM> is formed directly on the secondary winding insulator layer <NUM>. In one or more embodiments, the secondary winding assembly <NUM> can include an additional ground insulating layer <NUM>. The ground insulating layer <NUM> can be interposed between the multi-section HV insulator <NUM> and the secondary winding assembly <NUM>.

Turning to <FIG>, for example, the primary and secondary winding assemblies <NUM> and <NUM> are shown as being magnetically coupled to one another via a single pair of magnetic coils, i.e., a single primary winding <NUM> and a single secondary winding <NUM>. The combination of a given winding (e.g., <NUM>) and magnetic core cap (e.g. <NUM>) in each of the primary winding assembly <NUM> and the secondary winding assembly <NUM> generates magnetic fields. The magnetic fields are mutually shared by the primary and secondary winding assemblies <NUM> and <NUM> such that they are "magnetically coupled" to one another.

Although a single pair of magnetic coils <NUM> and <NUM> are illustrated in <FIG>, the invention is not limited thereto. <FIG>, for example, illustrates the primary and secondary winding assemblies <NUM> and <NUM> being magnetically coupled to one another via two separate pairs of primary magnetic coils 118a-118b and secondary magnetic coils 126a-126b according to a non-limiting embodiment. Each magnetic coil 118a-118b and 126a-126b included in a respective pair is arranged next to one another, e.g., side-by-side. In this manner, the magnetic coupling strength (k) between the primary and secondary winding assemblies <NUM> and <NUM> is increased, while stray magnetic fields <NUM> are reduced.

Referring again to <FIG>, the multi-section HV isolator <NUM> includes one or more insulator sections <NUM> and one or more intermediate magnetic cores <NUM> interposed between the primary winding assembly <NUM> and the secondary winding assembly <NUM>. The insulator sections <NUM> are composed of a dielectric material including, but not limited to, polytetrafluoroethylene (PTFE), while the magnetic core(s) <NUM> is composed of a ferrite material such as, for example, a manganese-nickel ferrite material, manganese-zinc ferrite material, or combination thereof.

The multi-section HV isolator <NUM> includes a core isolator region <NUM> extending along axis (Z) between a first core isolator portion <NUM> and an opposing second core isolator portion <NUM> to define a core isolator height (h2) (see <FIG>). The core isolator height (h2) can range, for example, from about <NUM> inches (<NUM>) to about <NUM> inches (<NUM>). The core isolator portion <NUM> also extends along a second axis (X) perpendicular to axis (Z) to define an isolator width. In at least one embodiment suitable for protected (e.g., indoors) environment, the core isolator region <NUM> can have a cylindrical shape having a diameter ranging from about <NUM> inches (<NUM>) to about <NUM> inches (<NUM>). The core isolator region <NUM> includes a cavity <NUM> configured to support the intermediate magnetic core <NUM> therein. The intermediate magnetic core <NUM> is formed as non-sectioned ferrite core, and embedded in the middle of the multi-section HV isolator <NUM>. The intermediate magnetic core <NUM> extends along axis (Z) to define a ferrite core height, and extends along the second axis to define a ferrite core width that typically is less than the ferrite core height.

The individual insulator sections <NUM> extend radially from the core isolator region <NUM>. Each individual insulator section <NUM> is separated from one another by a void <NUM>. The distance (h3) between each insulator section <NUM> (i.e., defined by a given void) ranges, for example, from about <NUM> inches (<NUM>) to about <NUM> inches (<NUM>). In at least one non-limiting embodiment, each individual insulator section <NUM> has a disc-shaped, and includes an exterior disc sidewall extending parallel with the vertical axis between a first disc surface and an opposing second disc surface to define an insulator height. The disc-shaped insulator sections <NUM> can have a diameter (i.e., extending radially from the core portion <NUM>), for example, of about <NUM> inch (<NUM>), and a thickness (i.e., along the z-axis) of about <NUM> inches (<NUM>). The middle non-sectioned ferrite core <NUM> can extend through the center of each disc-shaped insulator section <NUM>.

Turning now to <FIG> and <FIG>, an inductive wireless power transfer device <NUM> not according to the invention is illustrated. The intermediate magnetic core <NUM> is constructed as one or more individual layers instead of a single, non-sectioned middle ferrite core that extends through the individual insulator sections <NUM>. For example, the intermediate magnetic core can include a first individual core layer <NUM> and a second individual core layer <NUM> spaced apart from the first individual core layer <NUM> along axis (Z). Each of the first and second individual core layers <NUM> and <NUM> extend radially from axis (Z) to define a width. The first and second individual core layers <NUM> and <NUM> include an exterior sidewall <NUM> extending parallel with axis (Z) between a first layer surface <NUM> and an opposing second layer surface <NUM> to define a layer thickness (h4) that is typically less than the layer width. The first and second individual core layers <NUM> and <NUM> can be composed of a ferrite material such as, for example, a nickel-zinc ferrite material, manganese-zinc ferrite material, or combination thereof. The first and second individual core layers <NUM> and <NUM> can also be formed as a rigid layer, or as flexible layer such as, for example, a flexible sintered ferrite layer.

Still referring to <FIG>, the multi-section HV isolator <NUM> includes a first intermediate insulator layer <NUM>, a second intermediate insulator layer <NUM>, and a third intermediate insulator layer. The first intermediate insulator layer <NUM> is interposed between the first and second individual core layers <NUM> and <NUM>. The first intermediate insulator layer <NUM> may be disposed directly against a surface of the first individual core layer <NUM> and a surface of the second individual core layer <NUM>.

The second intermediate insulator layer <NUM> is interposed between the first individual core layer <NUM> and the primary winding assembly <NUM>, while the third intermediate insulator layer <NUM> is interposed between the second individual core layer <NUM> and the secondary winding assembly <NUM>. The first, second, and third intermediate insulator layers <NUM>, <NUM> and <NUM> can be composed of a dielectric material including, but not limited to, polytetrafluoroethylene (PTFE).

Instead of extending through the centers of the individual insulator sections, the first and second individual core layers <NUM> and <NUM> can have a surface area that matches or substantially matches the surface area of the primary and secondary winding assemblies <NUM> and <NUM>. In this manner, the primary winding assembly <NUM> can be disposed directly on a surface of the first individual core layer <NUM>, and the secondary winding assembly <NUM> can be disposed directly on a surface of the second individual core layer <NUM>.

Still referring to <FIG>, the primary winding assembly <NUM> includes a first insulator cap layer <NUM>, a primary shield <NUM> layer <NUM>, a primary winding <NUM>, a primary winding insulator layers 120a and 120b, and a primary shield layer <NUM>. The first insulator cap layer <NUM> is interposed between the first magnetic core cap <NUM> and the primary shield <NUM> layer <NUM>. The primary winding <NUM> and the primary winding insulator layers 120a and 120b are surrounded by the primary HV insulator layer <NUM> and the HV insulator <NUM> layer <NUM>. The primary winding <NUM> can be formed as a spiral-shaped traced composed of an electrically conductive material such as, for example, copper. The primary winding insulator layers 120a and 120b are formed directly on the primary shielding layers <NUM> and <NUM>, respectively, while the primary winding <NUM> is formed directly on the primary winding insulator layer <NUM>. The primary winding <NUM> and primary shielding layers <NUM> and <NUM> each have terminals to provide access to an external electrical connection. Layers <NUM> and <NUM> can comprise of polyamide or a comparable dielectric material, while layers <NUM> and <NUM> comprise a metal material to provide metal shields.

The secondary winding assembly <NUM> includes a second insulator cap layer <NUM>, a first ground shield layer <NUM>, a first secondary shield layer <NUM>, a secondary winding <NUM>, a secondary winding insulator layers 128a and 128b, a second secondary shield layer <NUM>, a ground insulator layer <NUM>, and a second ground shield layer <NUM>. The second insulator cap layer <NUM> is interposed between the second magnetic core cap <NUM> and the first secondary ground shield layer <NUM>. The secondary winding <NUM> and the secondary winding insulator layers 128a and 128b are surrounded by the first secondary shield layer <NUM> and the secondary shield layer <NUM>. The secondary winding <NUM> can be formed as a spiral-shaped traced composed of an electrically conductive material such as, for example, copper. The secondary winding insulator layers 128a and 128b are formed directly on the first secondary shield layer <NUM> and the secondary shield layer <NUM>, respectively, while the secondary winding <NUM> is formed directly on the secondary winding insulator layer 128b. The secondary winding assembly <NUM> can include an additional secondary HV insulating layer <NUM>, and a second ground insulating layer <NUM>. The first ground shield layer <NUM> can be interposed between the multi-section HV insulator <NUM> (e.g., the third intermediate insulator layer <NUM>) and the first secondary shield layer <NUM>. The second secondary ground shield layer <NUM> can be interposed between the second insulator cap layer <NUM> and the ground insulator layer <NUM>. The insulating layers <NUM> and <NUM> can comprise polyamide or comparable dielectric material, while layers <NUM>, <NUM>, <NUM> and <NUM> comprise a metal material to provide metal shields.

Turning now to <FIG>, an inductive wireless power transfer device <NUM> including printed wiring board (PWB)-based windings not according to the invention is illustrated. In this example, the inductive wireless power transfer device <NUM> can use one or more built-in toroidal field equalizers to reduce electric field intensity and ionization.

The inductive wireless power transfer device <NUM> includes a first magnetic core cap <NUM> associated with a primary winding assembly <NUM> and a second magnetic core cap <NUM> associated with a secondary winding assembly <NUM> so as to magnetically couple together the primary winding assembly <NUM> and the secondary winding assembly <NUM>. An intermediate magnetic core layer <NUM> is interposed between the first magnetic core cap <NUM> and the secondary core cap <NUM>. Individual insulating layer <NUM>, <NUM> and <NUM> are interposed between the first magnetic core cap <NUM>, the intermediate magnetic core layer <NUM>, and the secondary core cap <NUM>.

The inductive wireless power transfer device <NUM> further includes a PWB-based primary winding <NUM>, a PWB-based secondary winding <NUM>, and one or more toroidal field equalizers <NUM>. A PWB-based winding refers to a winding that is formed as an electrically conductive trace on a PWB. The PWB can include a corona-resistant material with random orientation of fibers (e.g. Kevlar), while the trace is formed thereon.

The primary winding <NUM> is surrounded by a pair of first and second primary shielding layers 130a and 130b. The first and second shielding layers are connected together by a first via 168a. Similarly, the secondary winding <NUM> is surrounded by a pair of first and second ground shielding layers 130c and 130d. The first and second ground shielding layers are also connected together by a second via 168b.

The toroidal field equalizer <NUM> is surrounded by an electrical insulating filling <NUM>, and is configured to suppress high-voltage partial discharge (sometimes referred to as corona). The toroidal field equalizer <NUM> includes a compressible insulating core <NUM> surrounded by a spiral beryllium or metal spring <NUM>. The metal spring <NUM> is connected to one of the primary shielding layers, e.g., 130b.

As described herein, an inductive wireless power transfer device is provided which employs a multi-section HV isolator including one or more individual isolator sections interposed between a primary energy coil (i.e., primary winding) and a secondary energy coil (i.e., secondary winding). The multi-section HV isolator further includes a magnetic material arranged between the primary and secondary windings to form one or more intermediate cores. The implementation of the multi-section HV isolator allows inductive wireless power transfer device to achieve a substantial improvement in power transfer efficiency compared to conventional devices, while maintaining necessary HV isolation for providing HV protection capabilities.

Claim 1:
An inductive wireless power transfer device (<NUM>) comprising:
a primary winding assembly (<NUM>) and a secondary winding assembly (<NUM>) separated from the primary winding assembly by a distance (h1);
a first magnetic core cap (<NUM>) on the primary winding assembly (<NUM>) and a second magnetic core cap (<NUM>) on the secondary winding assembly (<NUM>) so as to magnetically couple together the primary winding assembly (<NUM>) and the secondary winding assembly (<NUM>); and
a multi-section high voltage isolator (<NUM>) interposed between the primary winding assembly (<NUM>) and the secondary winding assembly (<NUM>), the multi-section high voltage isolator (<NUM>) including at least one individual insulator section (<NUM>) comprising a dielectric material, and wherein
the multi-section high voltage isolator (<NUM>) including at least one intermediate magnetic core (<NUM>) comprising a ferrite material interposed between the primary winding assembly (<NUM>) and the secondary winding assembly (<NUM>),
wherein the at least one individual insulator section (<NUM>) of the multi-section high voltage isolator (<NUM>) includes a core isolator portion (<NUM>) extending along a first axis (Z), between a first core isolator portion (<NUM>) and an opposing second core isolator portion (<NUM>) to define a core isolator height (h2), and an outer isolator surface extending along a second axis (X), perpendicular to the first axis (Z), to define a multi-section high voltage isolator width,
wherein the at least one intermediate magnetic core (<NUM>) includes a middle non-sectioned ferrite core (<NUM>) embedded in the core isolator portion (<NUM>),
wherein the middle non-sectioned ferrite core (<NUM>) extends along the first axis (Z), to define a ferrite core height, and extends along the second axis (X), to define a ferrite core width that is less than the ferrite core height.