Patent ID: 12210805

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure is directed to systems and methods for modeling a wireless power transfer system including stacked plate resonators. A method includes generating, using a computing device, a plurality of different sets of design parameters for a wireless power transfer system, the wireless power transfer system including a transmit resonator and a receive resonator, each of the transmit resonator and the receive resonator including a magnetic core having a post, and a plurality of alternating dielectric layers and conductive layers stacked around the post. The method further includes selecting, using the computing device, one set of the plurality of generated sets of design parameters, generating, using the computing device, an initial population of wireless power transfer systems based on the selected set, evaluating, using the computing device, each wireless power transfer system in the initial population, and generating, using the computing device, a subsequent population of wireless power transfer systems based on the evaluating.

Referring now to the drawings,FIG.1is a simplified circuit of an exemplary wireless power transfer system100. The system100includes an external transmit resonator102and an implantable receive resonator104. In the system shown inFIG.1, a power source Vs is electrically connected with the transmit resonator102, providing power to the transmit resonator102. The receive resonator104is connected to a load106(e.g., an implantable medical device). The receive resonator104and the load106may be electrically connected with a switching or rectifying device (not shown).

In the exemplary embodiment, the transmit resonator102includes a coil Lx connected to the power source Vs by a capacitor Cx. Further, the receive resonator104includes a coil Ly connected to the load106by a capacitor Cy. Inductors Lx and Ly are coupled by a coupling coefficient k. Mxyis the mutual inductance between the two coils. The mutual inductance, Mxy, is related to the coupling coefficient k as shown in the below Equation (1).
Mxy=k√{square root over (Lx·Ly)}  (1)

In operation, the transmit resonator102transmits wireless power received from the power source Vs. The receive resonator104receives the power wirelessly transmitted by the transmit resonator102, and transmits the received power to the load106.

FIG.2illustrates one embodiment of a patient200using an external coil202(such as the transmit resonator102shown inFIG.1) to wirelessly transmit power to an implanted coil204(such as the receive resonator shown inFIG.1). The implanted coil204uses the received power to power an implanted device206. For example, the implanted device206may include a pacemaker or heart pump (e.g., a left ventricular assist device (LVAD)). In some embodiments, the implanted coil204and/or the implanted device206may include or be coupled to a battery.

In one embodiment, the external coil202is communicatively coupled to a computing device210, for example, via wired or wireless connection, such that the external coil202may receive signals from and transmit signals to the computing device210. In some embodiments, the computing device210is a power source for the external coil202. In other embodiments, the external coil202is coupled to an alternative power supply (not shown). The computing device210includes a processor212in communication with a memory214. In some embodiments, executable instructions are stored in the memory214.

The computing device210further includes a user interface (UI)216. The UI216presents information to a user (e.g., the patient200). For example, the UI216may include a display adapter (not shown) that may be coupled to a display device, such as a cathode ray tube (CRT), a liquid crystal display (LCD), an organic LED (OLED) display, and/or an “electronic ink” display. In some embodiments, the UI216includes one or more display devices. Further, in some embodiments, presentation interface may not generate visual content, but may be limited to generating audible and/or computer-generated spoken-word content. In the example embodiment, the UI216displays one or more representations designed to aid the patient200in placing the external coil202such that the coupling between the external coil202and the implanted coil204is optimal. In some embodiments, the computing device210may be a wearable device. For example, in one embodiment, the computing device210is a wrist watch, and the UI216is displayed on the wrist watch.

FIG.3Ais a schematic diagram of one embodiment of a stacked plate resonator300that may be used to implement the system100shown inFIG.1. For example, the stacked plate resonator300may be used to implement external transmit resonator102, the implantable receive resonator104, the external coil202, and/or the implanted coil204.FIG.3Bis an exploded view of the stacked plate resonator300. Similar stacked plate resonators are shown and described in “Thin Self-Resonant Structures with a High-Q for Wireless Power Transfer” by Stein et al., Mar. 4, 2018, Thayer School of Engineering, Dartmouth College, Hanover, NH.

As shown inFIGS.3A and3B, the stacked plate resonator300includes a plurality of stacked plates302arranged on a magnetic core304. For clarity, inFIGS.3A and3B, the thickness of each stacked plate302is exaggerated. For example, in some embodiments, the thickness of each stacked plate302may be in a range from 10 micrometers (μm) to 200 μm. For example, more particularly, the thickness may in a range from 20-70 μm. Further, inFIGS.3A and3B, the stacked plate resonator300is shown as including five stacked plates302. However, those of skill in the art will appreciate that the stacked plate resonator300may include any suitable number of stacked plates302.

The magnetic core304includes a base310, a perimeter wall312, and a post314. In some embodiments, the perimeter wall312is omitted. As shown inFIGS.3A and3B, each stacked plate302includes an aperture320sized to receive the post314, such that each stacked plate302generally surrounds the post314and is positioned between the post314and the perimeter wall312of the magnetic core304. A height from the base310to the top of the perimeter wall312may be the same as, or different from, a height of the post314. The magnetic core304may be formed of a ferrite material, such as nickel-based or manganese-based ferrites. Nickel-based ferrites generally have lower electrical conductivity and reduced losses, while manganese-based ferrites have a higher magnetic permeability (while still having acceptable losses), facilitating containing magnetic field lines, and reducing fringing fields entering nearby conductors (e.g., a titanium enclosure or copper in a nearby PCB) to prevent losses. In other embodiments, other types of ferrite materials may be used. For example, in some embodiments, a magnesium-based ferrite (e.g., MgCuZn, which may outperform nickel-based and manganese-based ferrites in a frequency range around 1 Megahertz (MHz)) may be used.

The stacked plates302include a plurality of alternating dielectric layers322and conductive layers324that form a stack. In the embodiment shown inFIGS.3A and3B, each dielectric layer322is an annular plate that is generally o-shaped, and extends between an inner diameter and an outer diameter. Each conductive layer324defines a notch326, such that each conductive layer is generally c-shaped and extends between an inner diameter and an outer diameter. Each conductive layer324extends circumferentially through an angle (referred to herein as an “angular span”) that is less than 360° to define the notch326. The dielectric layers322may be formed of, for example, ceramic, plastic, glass, and/or mica.

Further, each conductive layer324has an opposite orientation relative to the next conductive layer324, such that the notches326in consecutive conductive layers324are oriented at 180° relative to each other. The opposite orientations result in consecutive conductive layers324forming two capacitors. Alternatively, other angular orientations may be used.

In one embodiment, one conductive layer324is a base conductive layer330that includes two terminals332. The terminals332enable the stacked plate resonator300to be coupled to, for example, a power source (when functioning as a transmit resonator) or the load106(when functioning as a receive resonator). Further, in some embodiments, the stacked plates302that form the top and bottom of the stack are conductive layers324, not dielectric layers322. Alternatively, a dielectric layer322may be positioned on the top and/or bottom of the stack.

In operation, when power is supplied to a stacked plate resonator300operating as a transmit resonator, current flows through the capacitors formed by the conductive layers324, creating an inductive current loop. Specifically, when supplied power, a first stacked plate resonator300functions as a parallel LC resonator, and is capable of wirelessly transmitting power to a second stacked plate resonator300(which similarly functions as a parallel LC resonator), provided the resonance frequencies of the first and second stacked plate resonators300overlap.

The resonance frequency of the stacked plate resonator300may be, for example, approximately 6.78 Megahertz (MHz). Specifically, the resonance frequency of the stacked plate resonator300is inversely proportional to the square root of the product of inductance and capacitance in the stacked plate resonator300. The inductance and capacitance are determined based on the design of the stacked plate resonator300. Accordingly, by modifying the design of the stacked plate resonator300, the resonance frequency may be modified.

As will be appreciated by those of skill in the art, it is generally desirable to increase/improve/optimize the amount of wireless power transmitted from a transmit resonator to a receive resonator. Accordingly, the systems and methods described herein use a computing device to model and simulate operation of a wireless power transfer system including stacked plate resonators to facilitate improving wireless power transfer in such a system. To model and simulate operation of the wireless power transfer system, the computing device may leverage artificial intelligence (AI). AI may include, for example, search and optimization approaches, logic, probabilistic methods (fuzzy logic), statistical learning, genetic algorithms, heuristic searching, and neural networks.

FIG.4is a block diagram of a computing device400that may be used to implement the systems and methods described herein. The computing device400includes at least one memory device410and a processor415that is coupled to the memory device410for executing instructions. In some embodiments, executable instructions are stored in the memory device410. In this embodiment, the computing device400performs one or more operations described herein by programming the processor415. For example, the processor415may be programmed by encoding an operation as one or more executable instructions and by providing the executable instructions in the memory device410.

The processor415may include one or more processing units (e.g., in a multi-core configuration). Further, the processor415may be implemented using one or more heterogeneous processor systems in which a main processor is present with secondary processors on a single chip. In another illustrative example, the processor415may be a symmetric multi-processor system containing multiple processors of the same type. Further, the processor415may be implemented using any suitable programmable circuit including one or more systems and microcontrollers, microprocessors, reduced instruction set circuits (RISC), application specific integrated circuits (ASIC), programmable logic circuits, field programmable gate arrays (FPGA), graphics processing units (GPU), and any other circuit capable of executing the functions described herein.

In this embodiment, the memory device410is one or more devices that enable information such as executable instructions and/or other data to be stored and retrieved. The memory device410may include one or more computer readable media, such as, without limitation, dynamic random access memory (DRAM), static random access memory (SRAM), a solid state disk, and/or a hard disk. The memory device410may be configured to store, without limitation, application source code, application object code, source code portions of interest, object code portions of interest, configuration data, execution events and/or any other type of data.

In this embodiment, the computing device400includes a presentation interface420that is coupled to the processor415. The presentation interface420presents information to a user425. For example, the presentation interface420may include a display adapter (not shown) that may be coupled to a display device, such as a cathode ray tube, a liquid crystal display (LCD), an organic LED (OLED) display, and/or an “electronic ink” display. In some embodiments, the presentation interface420includes one or more display devices. Input signals and/or filtered signals processed using the embodiments described herein may be displayed on the presentation interface420.

In this embodiment, the computing device400includes a user input interface435. The user input interface435is coupled to the processor415and receives input from the user425. The user input interface435may include, for example, a keyboard, a pointing device, a mouse, a stylus, a touch sensitive panel (e.g., a touch pad or a touch screen), a gyroscope, an accelerometer, a position detector, and/or an audio user input interface. A single component, such as a touch screen, may function as both a display device of the presentation interface420and the user input interface435.

The computing device400, in this embodiment, includes a communication interface440coupled to the processor415. The communication interface440communicates with one or more remote devices. To communicate with remote devices, the communication interface440may include, for example, a wired network adapter, a wireless network adapter, and/or a mobile telecommunications adapter.

FIG.5is a flow chart of one embodiment of a method500for modeling a wireless power transfer system including stacked plate resonators. The method500makes use of a genetic algorithm, or a search heuristic, with various evolutions. An evolutionary optimization algorithm, such as the genetic algorithm described herein, is a technique to find an optimum solution to a complicated problem that is difficult and time consuming to analyze directly. For circuit designs, such as a stacked plate resonator circuit design, it may be used to optimize a problem for several parameters at once even when the circuit is relatively complicated with interrelations between different components.

One advantage of an optimization algorithm is that it may be used to solve a complicated system without having to establish closed form equations to define the optimization. Therefore, there does not need to be a complete or comprehensive understanding of the interactions within the modeled system in order to achieve optimization.

As described above, a wireless power transfer system may include a first stacked plate resonator that functions as a transmit resonator, and a second stacked plate resonator that functions as a receive resonator. The method500described herein facilitates generating an optimization equation for such a wireless power transfer system. For this embodiment, the circuit structure is fixed, and design parameters are varied to facilitate optimization.

The method includes generating502, using the computing device400, a plurality different sets of design parameters for the wireless power transfer system. Referring back toFIGS.3A and3B, the stacked plate resonators300in the wireless power transfer system are defined by a plurality of design parameters. Design parameters used in the embodiments described herein may include, for example: a thickness of the dielectric layers322in at least one of the transmit resonator and the receive resonator, a dielectric constant of the dielectric layers322in at least one of the transmit resonator and the receive resonator, an inner diameter of the dielectric layers322in at least one of the transmit resonator and the receive resonator, an outer diameter of the dielectric layers322in at least one of the transmit resonator and the receive resonator, a number of dielectric layers322in at least one of the transmit resonator and the receive resonator, a thickness of the conductive layers324in at least one of the transmit resonator and the receive resonator, an angular span of the conductive layers324in at least one of the transmit resonator and the receive resonator, a number of conductive layers324in at least one of the transmit resonator and the receive resonator, an inner diameter of the conductive layers324in at least one of the transmit resonator and the receive resonator, and an outer diameter of the conductive layers324in at least one of the transmit resonator and the receive resonator. Those of skill in the art will appreciate that additional and/or alternative design parameters may be used.

For example, design parameters may relate to non-linear electronic components that may be included in the wireless power transfer systems. For example, the design parameters may relate to field effect transistors (FETs) used for active rectification. FETs do have regular ohmic conduction losses (i.e., proportional to current squared), but also have significant switching losses and diode conduction losses (linearly proportional to current). Accordingly, the design parameters may include selecting FETs from a library of possible FETs (and include these in the “mating” described below). Further, the design parameters may include different switching strategies (e.g., zero current switching). In another example, the design parameters may include selecting diodes (e.g., for passive rectification) from a library of diodes. In yet another example, the design parameters may relate to the generation of the input voltage (e.g., the characteristics of the duty cycle used to generate a pulse-width modulated voltage).

Each generated502set of design parameters includes randomly chosen values for one or more design parameters (e.g., one or more of the design parameters listed above). The sets may be generated502automatically by the computing device400. The values may be randomly chosen, by the computing device400, within a predetermined range. For example, values for the thickness of the dielectric layers322and the thickness of the conductive layers324may be randomly chosen within a range of 0-200 μm. In some embodiments, the predetermined range may be specified by a user (e.g., via a user input to computing device400).

The method500further includes selecting504one set of the generated502sets. The one set may be selected504automatically by the computing device400based on a calculated efficiency for the set. That is, for each generated502set, the computing device400may simulate operation of a wireless power system that includes the design parameters for that set, and calculate a wireless power transfer efficiency for that set based on the simulated operation. Then, the computing device selects504the set having the highest calculated efficiency.

The method500further includes generating506an initial population of wireless power transfer systems based on the selected504set. The wireless power transfer systems are not actual, physical systems, but digital representations (e.g., stored in the memory device410) of the wireless power transfer systems that are used for modeling and simulation purposes, as described herein. In one embodiment, the initial population of wireless power transfer systems is generated506by randomly varying, using the computing device, values for one or more of the design parameters in the selected504set. Again, the values may be varied within a predetermined range. The initial population of wireless power transfer system may be relatively large (e.g., including at least 10,000 different wireless power transfer systems).

The method500further includes evaluating508, using the computing device400, each wireless power transfer system in the initial population. On one embodiment, the evaluating508includes calculating a score for each wireless power transfer system. For example, operation of each wireless power transfer system may be simulated, and a total score may be calculated, from the simulation, based on at least one of efficiency of wireless power transfer, voltage gain, input current, power lost at the receive resonator, voltage at the receive resonator, etc. That is, the total score may be calculated by summing a plurality of sub-scores, each sub-score associated with one of the different components (e.g., efficiency of wireless power transfer, voltage gain, etc.). Further, these different components may be weighted differently when calculating the score, such that different sub-scores have different weightings. For example, efficiency of wireless power transfer may be weighted greater than voltage at the receive resonator. Those of skill in the art will appreciate that any suitable scoring methodology may be used to assess the wireless power transfer systems in the initial population.

Subsequently, the method500includes generating510, using the computing device400, a subsequent population of wireless power transfer systems based on the evaluation508of the wireless power transfer systems from the initial population. For example, the subsequent population may be generated510by randomly varying design parameter values for all wireless power transfer systems in the initial population that are assigned a score above a predetermined threshold (e.g., indicating that the wireless power transfer systems perform relatively well). Alternatively, the subsequent population may be generated510by randomly varying design parameter values for a predetermined number of wireless power transfer systems based on their score (e.g., the wireless power transfer system having the best score, the ten wireless power transfer systems having the best scores, the fifty wireless power transfer systems having the best scores, etc.). In yet another embodiment, the subsequent population may be generated510by randomly “mating” wireless power transfer systems to generate “child” wireless power transfer systems (e.g., by randomly swapping design parameter values between different wireless power transfer systems both having favorable scores). In another embodiment, the subsequent population may be generated510using wireless power transfer systems from the initial population that are relatively diverse from one another, to avoid the algorithm converging to a local optimum.

In yet another embodiment, the subsequent population may be generated510by mating and/or varying parameters of wireless power transfer systems based on their sub-scores. For example, one wireless power transfer system may have a relatively low voltage gain sub-score, but a relatively high power transfer efficiency sub-score. This system may have only a moderate total score (due to the low voltage gain sub-score). However, given the relatively high power transfer efficiency sub-score, it may still be beneficial to use this wireless power transfer system to generate510the subsequent population.

Once the subsequent population is generated510, a candidate wireless power transfer system may be selected512, using the computing device400, from the subsequent population (e.g., based on efficiency of wireless power transfer, voltage gain, input current, power lost at the receive resonator, voltage at the receive resonator, etc.). Due to the operation of the method500, there is a high probability that candidate wireless power transfer system will have desirable operating characteristics. Accordingly, a physical wireless power transfer system may be manufactured514based on the candidate wireless power transfer system. Manufacturing514the physical wireless power transfer system may include fabricating a new wireless power transfer system, or modifying a previously existing wireless power transfer system.

Alternatively, once the subsequent population is generated510, the wireless power transfer systems in the subsequent population may be evaluated (similar to the evaluation508) to generate a further subsequent population (similar to the generation510). Those of skill in the art will appreciate that these steps may be iterated any number of times before selecting512a candidate wireless power transfer system for manufacturing514. In general, the more iterations performed of evaluating and generating subsequent populations, the more desirable the characteristics of the candidate wireless power transfer system (because the algorithm generally generates better and better populations with more and more iterations). In some embodiments, the candidate wireless power transfer system includes a transit resonator and a receive resonator with partially overlapping, but distinct resonance frequency ranges.

In various embodiments, the optimization algorithm makes use of any of the techniques described above in any combination.

The embodiments described herein are directed to systems and methods for modeling a wireless power transfer system including stacked plate resonators. A method includes generating, using a computing device, a plurality of different sets of design parameters for a wireless power transfer system, the wireless power transfer system including a transmit resonator and a receive resonator, each of the transmit resonator and the receive resonator including a magnetic core having a post, and a plurality of alternating dielectric layers and conductive layers stacked around the post. The method further includes selecting, using the computing device, one set of the plurality of generated sets of design parameters, generating, using the computing device, an initial population of wireless power transfer systems based on the selected set, evaluating, using the computing device, each wireless power transfer system in the initial population, and generating, using the computing device, a subsequent population of wireless power transfer systems based on the evaluating.

Although the embodiments and examples disclosed herein have been described with reference to particular embodiments, it is to be understood that these embodiments and examples are merely illustrative of the principles and applications of the present disclosure. It is therefore to be understood that numerous modifications can be made to the illustrative embodiments and examples and that other arrangements can be devised without departing from the spirit and scope of the present disclosure as defined by the claims. Thus, it is intended that the present application cover the modifications and variations of these embodiments and their equivalents.

This written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure 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.