Patent Description:
The present disclosure relates to a wireless power transfer device configured to generate a magnetic field and control a direction of the magnetic field.

A primary coil may be driven with AC current to generate an oscillating magnetic field, and the magnetic field can generate a current in a secondary coil in proximity to the primary coil via electromagnetic induction. Electromagnetic induction can be used to wirelessly transfer energy and is utilized in various industries and devices such as electric vehicles, medical devices, and electronic devices. The magnitude of the current generated in the secondary coil, and thus the effectiveness of the primary coil in transferring energy to the secondary coil, depends on how aligned the magnetic field is with the secondary coil. However, in conventional devices, the primary coil cannot control the direction of the magnetic field, and improving alignment between the magnetic field with the secondary coil requires physically moving and/or orientating the primary coil or the secondary coil, which may be inconvenient and cumbersome. <CIT> discloses various embodiments of a wirelessly powered local computing environment. <CIT> relates to an apparatus for transmitting wireless power using a magnetic field lens which condenses a magnetic field, and a method thereof. <CIT> describes a receiving antenna for receiving low frequency signals is constituted by arranging two loop antenna elements and one air-core loop antenna element close to each other, wherein the two loop antenna elements are arranged in combination such that a magnetic flux which passes an axis of each one loop antenna element is prevented from passing an axis of another loop antenna element, and one air-core loop antenna element is arranged in combination with the two loop antenna elements such that an axis of the air-core loop antenna crosses respective axes of the one and other loop antenna elements orthogonally. <CIT> describes a mobile wireless receiver for use with a first electromagnetic resonator coupled to a power supply and a second electromagnetic resonator coupled to at least one of a power supply and the first electromagnetic resonator
<CIT> describes an augmented reality system including an electronic contact lens and a plurality of conductive coils to be worn, for instance, around a neck, around an arm, or on a chest of a user.

The accompanying drawings, together with the specification, illustrate example embodiments of the present invention. These drawings, together with the description, serve to better explain aspects and principles of the present invention.

Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section.

It will be understood that when an element or layer is referred to as being "on", "connected to", "coupled to", or "adjacent to" another element or layer, it can be directly on, connected to, coupled to, or adjacent to the other element or layer, or one or more intervening element(s) or layer(s) may be present. In contrast, when an element or layer is referred to as being "directly on," "directly connected to", "directly coupled to", or "immediately adjacent to" another element or layer, there are no intervening elements or layers present.

As used herein, the term "substantially" and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent deviations in measured or calculated values that would be recognized by those of ordinary skill in the art. Also, the terms "about," "approximately," and similar terms, when used herein in connection with a numerical value or a numerical range, are inclusive of the stated value and mean within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (e.g., the limitations of the measurement system).

Example embodiments of the present disclosure will now be described with reference to the accompanying drawings. In the drawings, the same or similar reference numerals refer to the same or similar elements throughout. As used herein, the use of the term "may," when describing embodiments of the present disclosure, refers to "one or more embodiments of the present disclosure.

<FIG> schematically illustrates a wireless power transfer system according to some embodiments. The wireless power transfer system may include a wireless power transfer device <NUM> and an electronic device <NUM>.

The wireless power transfer device <NUM> may include a first transmitting coil <NUM>, a second transmitting coil <NUM> on (e.g., positioned on) the first transmitting coil <NUM>, a driver <NUM> configured to drive the first transmitting coil <NUM> with a first AC current and the second transmitting coil <NUM> with a second AC current, power modulation electronics <NUM> configured to modulate the first and second AC currents provided by the driver <NUM>, a controller <NUM> (e.g., a microcontroller) configured to control the operations of the driver <NUM> and the power modulation electronics <NUM>, and a receiver <NUM> for receiving information (e.g., information transmitted by the electronic device <NUM>).

The electronic device <NUM> may include a receiver coil <NUM>, a detector <NUM> configured to detect information about power received in the receiver coil <NUM>, and a transmitter <NUM> configured to transmit information (e.g., transmit information to the wireless power transfer device <NUM>). In some embodiments, the transmitter <NUM> may be a radio or an RF transmitter.

The wireless power transfer device <NUM> is configured to generate an oscillating magnetic field by driving the first and second transmitting coils <NUM> and <NUM> with the first and second AC currents, respectively, and to rotate the direction of the magnetic field by controlling (e.g., setting or adjusting) a first magnitude of the first AC current, a second magnitude of the second AC current, and a phase difference between the first and second AC currents namely, the wireless power transfer device <NUM> is configured to rotate the direction of the magnetic field by differentially driving the first and second transmitting coils <NUM> and <NUM>. When the wireless power transfer device <NUM> generates the magnetic field and the electronic device <NUM> is in the proximity to the wireless power transfer device <NUM>, a current may be generated in the receiver coil <NUM> by electromagnetic induction (e.g., wireless resonant induction). The detector <NUM> may be configured to detect information (e.g., power, amplitude, etc.) about the current generated in the receiver coil <NUM>, and the transmitter <NUM> may transmit (e.g., wirelessly transmit) the detected information to outside of the electronic device <NUM>, for example, to the receiver <NUM> of the wireless power transfer device <NUM>. The controller <NUM> may control the driver <NUM> and the power modulation electronics <NUM> based on the information received by the receiver <NUM> to control the direction of the magnetic field at the receiver coil <NUM>.

The first and second transmitting coils <NUM> and <NUM> will now be described in more detail with reference to <FIG>. <FIG> shows a perspective view of the first and second transmitting coils <NUM> and <NUM> according to some embodiments, <FIG> shows a plan view of the first and second transmitting coils <NUM> and <NUM> of <FIG>, and <FIG> shows a side view of the first and second transmitting coils <NUM> and <NUM> of <FIG>.

The first transmitting coil <NUM> may include a first rod <NUM> and a first wire <NUM> wound around the first rod <NUM>, and the second transmitting coil <NUM> may include a second rod <NUM> and a second wire <NUM> wound around the second rod <NUM>.

The first transmitting coil <NUM> may be aligned along a first axis 100A, and the second transmitting coil <NUM> may be aligned along a second axis 200A different from the first axis 100A. In some embodiments, the second axis 200A is perpendicular (or substantially perpendicular) to the first axis 100A. That is, an angle between the second axis 200A and the first axis 100A may be approximately (about) <NUM>°. When the first and second axes 100A and 200A are perpendicular, coupling between the first and second transmitting coils <NUM> and <NUM> may be reduced or substantially prevented. Coupling between the first and second transmitting coils <NUM> and <NUM> may be at a maximum when the first and second axes 100A and 200A are parallel, and coupling between the first and second transmitting coils <NUM> and <NUM> may decrease as an angle between the first and second axes 100A and 200A increases towards <NUM>°, at which point coupling is at a minimum. However, the angle between the first axis 100A and the second axis 200A may be any suitable angle, for example, within the range of about <NUM>° to about <NUM>°. In <FIG>, the first axis 100A is shown as being aligned along an X-axis, and the second axis 200A is shown as being aligned along a Y-axis.

The second transmitting coil <NUM> may be on (e.g., above) the first transmitting coil <NUM> and may overlap the first transmitting coil <NUM> in a plan view (shown in <FIG>) at an area of overlap <NUM>. In some embodiments, the area of overlap <NUM> corresponds to a center region of the first transmitting coil <NUM> and a center region of the second transmitting coil <NUM>. The second transmitting coil <NUM> may be spaced apart (e.g., separated) from the first transmitting coil <NUM> in a thickness direction (e.g., a Z-axis direction) at the area of overlap <NUM>.

An intermediate space 300a between the first and second transmitting coils <NUM> and <NUM> in the area of overlap <NUM> may include (e.g., be filled or at least partially filled with) a nonmagnetic material having a low permeability, for example, air, plastic, foam, one or more non-ferrimagnetic materials, one or more low permeability metals (e.g., aluminum and/or copper), etc. In some embodiments, when the intermediate space 300a is filled with air, a frame or housing may be utilized to hold the first and second transmitting coils <NUM> and <NUM> and/or to maintain the relative positions of the first and second transmitting coils <NUM> and <NUM> with respect to each other. In some embodiments, the material in the intermediate space 300a has a relative permeability of equal to or less than about <NUM>, for example, in the range of about <NUM> to about <NUM>. In some embodiments, the material in the intermediate space 300a may be diamagnetic (e.g., a material having a relative permeability in the range of about <NUM> to about <NUM>). Therefore, in some embodiments, the second transmitting coil <NUM> does not contact the first transmitting coil <NUM>, and the first and second transmitting coils <NUM> and <NUM> are magnetically independent (e.g., magnetically decoupled and/or magnetically isolated from each other) and/or electrically independent (e.g., electrically decoupled and/or electrically isolated) from each other. Because the first and second transmitting coils <NUM> and <NUM> are not in contact, coupling between the first and second transmitting coils <NUM> and <NUM> may be reduced or substantially prevented. That is, the first transmitting coil <NUM> may generate a first magnetic field without being significantly influenced by the presence of the second transmitting coil <NUM>, and the second transmitting coil <NUM> may generate a second magnetic field without being significantly influenced by the presence of the first transmitting coil <NUM>. A magnetic field generated by the wireless power transfer device <NUM> may be a superposition of the first and second magnetic fields generated by the first and second transmitting coils <NUM> and <NUM>, respectively.

The first rod <NUM> may include a magnetic material having a high permeability, such as a ferrimagnetic material (e.g., soft ferrite material), such as nickel- or manganese-based ferrites (e.g., MnZn, NiZn, and/or the like). The magnetic material may increase the intensity of a magnetic field generated by the first transmitting coil <NUM> compared to an otherwise comparable coil without the magnetic rod. In some embodiments, the material of the first rod <NUM> may have a relative permeability equal to or greater than about <NUM>, for example, in the range of about <NUM> to about <NUM>,<NUM>. The second rod <NUM> may include any material that the first rod <NUM> may include, and the second rod <NUM> may include a material that is the same as, or different from, a material included in the first rod <NUM>. In some embodiments, a ratio of the permeability of a material in the first rod <NUM> to the permeability of the material in the intermediate space 300a may be equal to or greater than approximately (about) <NUM>. When the permeability of the materials of the first and second rods <NUM> and <NUM> are significantly larger than the permeability of the material in the intermediate space 300a, coupling between the first and second transmitting coils <NUM> and <NUM> may be reduced or substantially prevented. For example, a magnetic field flowing through the first rod <NUM> may be blocked (by the material in the intermediate space 300a) from permeating through the intermediate space 300a and into the magnetic material of the second rod <NUM>. Thus, the presence of the second transmitting coil <NUM> may not substantially affect the first magnetic field generated by the first transmitting coil <NUM>, and vice versa.

The first rod <NUM> may include a first main rod 120a and first thick portion (e.g., a tab or a flange) 120b at an end (e.g., both ends) of the first main rod 120a, and the second rod <NUM> may include a second main rod 220a and a second thick portion (e.g., a tab or a flange) 220b at an end (e.g., both ends) of the second main rod 220a. The first main rod 120a may have any suitable shape. The second main rod 220a may have any shape that the first main rod 120a may have, and the shape of the second main rod 220a may be the same as, or different from, the shape of the first main rod 120a. In some embodiments, the first main rod 120a has a cylindrical shape. In other embodiments, the first main rod 120a has a rectangular shape having a length along the X-axis, a width along the Y-axis, and a thickness along the Z-axis. The width of the first main rod 120a may be less than the length of the first main rod 120a, and the thickness of the first main rod 120a may be less than the width of the first main rod 120a, but the present disclosure is not limited thereto.

A thickness of the intermediate space 300a may be relatively small compared to the dimensions of the first and second transmitting coils <NUM> and <NUM>. For example, the thickness of the intermediate space 300a may be less than the length, the width, and/or the thickness of the first main rod 120a. Because the first and second magnetic fields generated by the first and second transmitting coils <NUM> and <NUM> will each generally decrease in magnitude as respective distances from the first and second transmitting coils <NUM> and <NUM> increase, it is advantageous for the thickness of the intermediate space 300a to be small in order to minimize or at least reduce a disparity between a distance between the electronic device <NUM> and the first transmitting coil <NUM> and a distance between the electronic device <NUM> and the second transmitting coil <NUM>. When the disparity is large, one of the first and second transmitting coils <NUM> and <NUM> may have an unintended disproportionate effect on the electronic device <NUM> compared to the other one of the first and second transmitting coils <NUM> and <NUM>. Accordingly, in one or more embodiments, the thickness of the intermediate space 300a may be sufficiently small such that the first and second transmitting coils <NUM> and <NUM> are substantially coplanar to advantageously minimize or at least reduce the disproportionate effect of one of the first and second transmitting coils <NUM> and <NUM> on the electronic device <NUM>.

In some embodiments, a thickness of the first main rod 120a at the area of overlap <NUM> is less than a thickness of the first main rod 120a at an area outside of the area of overlap <NUM>. For example, the first main rod 120a may have an indent or recess (e.g., a step) at the area of overlap <NUM> that faces the second main rod 220a. When one or both of the first and second main rods 120a and 220a have such an indent or recess, the distance between the first and second transmitting coils <NUM> and <NUM> may be reduced. In some embodiments, the indent or recess in one or both of the first and second main rods 120a and 220a may allow the first and second wires <NUM> and <NUM> to be coplanar (or substantially coplanar).

The first thick portion 120b may be at an end (or end portion) of the first main rod 120a, and a thickness of the first thick portion 120b may be greater than a thickness of the first main rod 120a. For example, as shown in <FIG>, the first thick portion 120b may protrude toward the second transmitting coil <NUM> (e.g., in the negative Z-axis direction). Similarly, the second thick portion 220b may be at an end (or end portion) of the second main rod 220a, and a thickness of the second thick portion 220b may be greater than a thickness of the second main rod 220a. For example, the second thick portion 220b may protrude toward the first transmitting coil <NUM> (e.g., in the Z-axis direction). For example, the second thick portion 220b of the second transmitting coil <NUM> may protrude in a direction opposite to a protruding direction of the first thick portion 120b of the first transmitting coil <NUM>. Because the first and second thick portions 120b and 220b of the first and second transmitting coils <NUM> and <NUM> may protrude toward the second and first transmitting coils <NUM> and <NUM>, respectively, the distance along the Z-axis direction between the ends of the first rod <NUM> and the ends of the second rod <NUM> may be reduced or eliminated, and thus, the ends of the first and second rods <NUM> and <NUM> may be substantially coplanar.

The first wire <NUM> may be wound around the first rod <NUM> in any suitable configuration. The second wire <NUM> may be wound around the second rod <NUM> in any configuration that the first wire <NUM> may be wound around the first rod <NUM>. In some embodiments, the first wire <NUM> is wound around the first main rod 120a and is not wound around the first thick portion 120b. The first wire <NUM> may be wound around substantially the entire length of the first main rod 120a. For example, the first wire <NUM> and the first main rod 120a may form a solenoid. In some embodiments, the first wire <NUM> is wound around two ends (or two end portions) of the first main rod 120a to form first and second sub-coils 110a and 110b at the two ends (or two end portions) of the first main rod 120a, and the first wire <NUM> exposes, and is not wound around, a portion (e.g., an exposed intermediate or central portion) of the first main rod 120a between the first and second sub-coils 110a and 110b. The exposed portion of the first main rod 120a may include a portion of the first main rod 120a corresponding to the area of overlap <NUM> between the first and second transmitting coils <NUM> and <NUM>. When the first wire <NUM> is not wound around the first main rod 120a at the area of overlap <NUM>, the thickness of the first transmitting coil <NUM> at the area of overlap <NUM> may be reduced.

The first sub-coil 110a may be electrically coupled (e.g., electrically connected) to the second sub-coil 110b in series or in parallel. When the first sub-coil 110a is electrically coupled (e.g., electrically connected) to the second sub-coil 110b in series, the first wire <NUM> may electrically couple (e.g., electrically connect) the first sub-coil 110a to the second sub-coil 110b by extending across the area of overlap <NUM> on the first main rod 120a and on a side of the first main rod 120a facing away from the second transmitting coil <NUM>.

In some embodiments, the first sub-coil 110a is not electrically coupled (e.g., electrically connected) to the second sub-coil 110b, and the first and second sub-coils 110a and 110b are separately driven. In such embodiments, the first and second sub-coils 110a and 110b may be synchronously driven so that the magnetic fields generated by the first and second sub-coils coils 110a and 110b oscillate in phase.

The wireless power transfer device <NUM> may generate a magnetic field by driving the first AC current through the first wire <NUM> and/or driving the second AC current through the second wire <NUM>. The first and second AC currents may be driven in phase (i.e., with about <NUM>° phase difference between the first and second AC currents) or about <NUM>° out of phase. A direction of the magnetic field generated by the wireless power transfer device <NUM> may be controlled by controlling (e.g., setting or changing) a first amplitude of the first AC current, a second amplitude of the second AC current, and a phase difference between the first and second AC currents (e.g., the wireless power transfer device <NUM> is configured to rotate the direction of the magnetic field by differentially driving the first and second transmitting coils <NUM> and <NUM>). Accordingly, the direction of the magnetic field can be rotated by changing these parameters.

<FIG> shows how the direction of a magnetic field generated by the wireless power transfer device <NUM> can be rotated according to a non-limiting example. <FIG> show graphs of the voltages applied to the first and second transmitting coils <NUM> and <NUM> as a function of time for five states shown in <FIG>. The numerical values shown in the graphs of <FIG> represent non-limiting examples. Beginning with a first state (<NUM>) as shown in <FIG> and <FIG>, the first amplitude of the first AC current of the first wire <NUM> is at <NUM>, the second amplitude of the second AC of the second wire <NUM> current is at <NUM>, and the direction of the magnetic field at a point above the area of overlap <NUM> may oscillate between the Y-axis direction and the negative Y-axis direction.

To rotate the magnetic field clockwise to a second position corresponding to a second state (<NUM>) as shown in <FIG> and <FIG>, the first and second AC currents are driven in phase, the first amplitude is increased while the second amplitude is decreased until they are the same (each at an amplitude of <NUM>), and the direction of the magnetic field at the point will oscillate between <NUM>° between the X-axis direction and the Y-axis direction and <NUM>° between the negative X-axis direction and the negative Y-axis direction.

To rotate the magnetic field clockwise to a third position corresponding to a third state (<NUM>) as shown in <FIG> and <FIG>, the first and second AC currents are driven in phase, the first amplitude is increased while the second amplitude is decreased until the first amplitude is at <NUM> and the second amplitude is at <NUM>, and the direction of the magnetic field at the point will oscillate between the X-axis direction and the negative X-axis direction.

To rotate the magnetic field to a fourth position corresponding to a fourth state (<NUM>) as shown in <FIG> and <FIG>, the first and second AC currents are driven <NUM>° out of phase, the first amplitude is decreased while the second amplitude is increased until the first and second amplitudes are the same (each at <NUM>), and the direction of the magnetic field at the point will oscillate between <NUM>° between the X-axis direction and the negative Y-axis direction and <NUM>° between the negative X-axis direction and the Y-axis direction.

To rotate the magnetic field to a fifth position corresponding to a fifth state (<NUM>) as shown in <FIG> and <FIG>, the first and second AC currents are driven <NUM>° out of phase, the first amplitude is decreased while the second amplitude is increased until the first amplitude is at <NUM> and the second amplitude is at <NUM>, and the direction of the magnetic field at the point may oscillate between the negative Y-axis direction and the Y-axis direction, similar to the first state (<NUM>). As used herein, the terms "first amplitude" and "second amplitude" refer to the peak amplitude.

Accordingly, the direction of the magnetic field at a point above the area of overlap <NUM> may be rotated to have any direction in the X-Y plane (any of quadrants I-IV of the X-Y plane in <FIG>) by gradually adjusting the first amplitude of the first AC current and the second amplitude of the second AC current, and by shifting the first and second AC currents between being in-phase and being <NUM>° out of phase. For example, when the first and second AC currents are in phase, the magnetic field at the point may have any direction in the first and third quadrants I and III of the X-Y plane by suitably setting the first and second amplitudes. Furthermore, when the first and second AC currents are <NUM>° out of phase, the magnetic field at the point may have any direction in the second and fourth quadrants II and IV of the X-Y plane by suitably setting the first and second amplitudes.

Although a direction of the magnetic field generated by the wireless power transfer device <NUM> at a point above the area of overlap <NUM> has been described with respect to <FIG>, it will be understood that the direction of the magnetic field at any point around the wireless power transfer device <NUM> may be controlled (e.g., rotated) as described above by controlling the first and second amplitudes and by controlling the phase difference between the first and second AC currents. The direction of the magnetic field at points away from regions above or below the area of overlap <NUM> may have a directional component along the Z-axis direction, whereas a direction of the magnetic field at regions above or below the area of overlap <NUM> may have substantially no Z-axis component.

The wireless power transfer device <NUM> may also include a power source, such as a rechargeable battery (e.g., a lithium-ion battery pack) or non-rechargeable battery (e.g., a replaceable battery), or the wireless power transfer device <NUM> may be configured to couple to (e.g., connect to), and be powered from, an external power source, such an electrical outlet. In some embodiments, the wireless power transfer device <NUM> includes a rechargeable battery and a power management system. A charger profile of the rechargeable battery may be set to not perform trickle charging, and the rechargeable battery may be allowed to charge to a set percentage of battery state of charge (SoC) of the rechargeable battery, for example, a percentage within a range of about <NUM>% to about <NUM>% of the SoC. The SoC of the rechargeable battery may refer to the maximum charge that the rechargeable battery is able to store.

Referring to <FIG>, which illustrates a wireless power transfer system according to some embodiments, the rechargeable battery of the wireless power transfer device <NUM> may be recharged through a power port or connector of the wireless power transfer device <NUM> that interfaces with a charging cradle <NUM>. The wireless power transfer device <NUM> may be configured to be placed in or fixed to the charging cradle <NUM>, and the wireless power transfer device <NUM> may be configured to detect the presence of a voltage at the power port or connector when it is placed in or fixed to the charging cradle <NUM>. In some embodiments, the wireless power transfer device <NUM> is configured to allow the rechargeable battery to charge if the detected voltage value is equal to a set value or within a set range.

Referring again to <FIG>, the driver <NUM> may include a first driver <NUM> to drive the first transmitting coil <NUM> and a second driver <NUM> to drive the second transmitting coil <NUM>. In some embodiments, each of the first and second drivers <NUM> and <NUM> include a class D MOSFET bridge module, and the first and second drivers <NUM> and <NUM> may be respectively coupled (e.g., connected) in series to the first and second wires <NUM> and <NUM> through a capacitor to create a series resonant tank circuit, which may be tuned to <NUM>. At the tuned frequency, the circuit may have the lowest impedance and highest quality factor.

Each of the first and second drivers <NUM> and <NUM> may receive an independent digital output signal from a digital port of the controller <NUM>. Each of the digital output signals may be a driver signal, for example, a <NUM> frequency, <NUM>% duty cycle square wave. The two independent digital output signals may allow phase shifting between the first and second AC currents.

Each of the first and second drivers <NUM> and <NUM> may include an isolation current sensor respectively coupled (e.g., connected) in series with the first and second wires <NUM> and <NUM>. The isolation current sensors may be configured to convert a current passing through the first and second drivers <NUM> and <NUM> into a proportional voltage which is rectified and signal conditioned. The signal may then be routed to an analog port of the controller <NUM> to be used as current feedback.

In some embodiments, the power modulation electronics <NUM> includes first power modulation electronics <NUM> and second power modulation electronics <NUM>. The first and second power modulation electronics <NUM> and <NUM> may be respectively configured to provide power to the first and second drivers <NUM> and <NUM>. The first and second power modulation electronics <NUM> and <NUM> may be independently controlled by respective analog output control signals received from the controller <NUM>. In some embodiments, each of the first and second power modulation electronics <NUM> and <NUM> includes a single-ended primary-inductor converter (SEPIC) DC-to-DC converter that is configured to step-up or step-down a system bus voltage received at an input and to output the stepped-up or stepped-down voltage.

Each of the first and second power modulation electronics <NUM> and <NUM> may be configured to monitor their respective output voltages and provide overcurrent protection. In some embodiments, the first and second power modulation electronics <NUM> and <NUM> are configured to attenuate their respective output voltages, filter their output voltages via a capacitor, and couple (e.g., connect) their output voltages to respective analog inputs of the controller <NUM>. For example, the first and second power modulation electronics <NUM> and <NUM> may be configured to provide their respective output voltages to the controller <NUM> as analog voltage feedback signals. The controller <NUM> may be configured to then provide respective digital signals to the first and second power modulation electronics <NUM> and <NUM> to enable or disable the first and second power modulation electronics <NUM> and <NUM> from providing power to the first and second drivers <NUM> and <NUM>.

In some embodiments, the controller <NUM> is a Bluetooth™ low energy system on chip controller (BLE SOC). The controller <NUM> may be programmed via a JTAG or USB-C connector. In some embodiments, the controller <NUM> is configured to provide two analog output control signals to the first and second power modulation electronics <NUM> and <NUM>, and the controller <NUM> is configured to receive two analog voltage feedback signals from the first and second power modulation electronics <NUM> and <NUM>, which are utilized to monitor and adjust output power and to detect supply faults. Furthermore, the controller <NUM> may be configured to provide two digital output signals to the first and second drivers <NUM> and <NUM> to drive the first and second transmitting coils <NUM> and <NUM>, and the controller <NUM> may be configured to provide two digital output signals to enable or disable the first and second power modulation electronics <NUM> and <NUM>. The two digital output signals may be wave pulses having a frequency and duty cycle, such as <NUM> and <NUM>% duty cycle.

The controller <NUM> may be configured to control the power output from each of the first and second drivers <NUM> and <NUM> by controlling the respective bus voltages of the first and second power modulation electronics <NUM> and <NUM>. The controller <NUM> may also be configured to control the phase difference between the first and second AC currents by changing a phase difference between the digital output signal pulse signals it provides to the first and second drivers <NUM> and <NUM>. Accordingly, by controlling the power of the first and second AC currents and the phase difference between the first and second AC currents, the controller <NUM> may control the direction and magnitude of the magnetic fields generated by the first and second transmitting coils <NUM> and <NUM>.

The wireless power transfer device <NUM> may be configured (e.g., via the controller <NUM>) to communicate various suitable information to the user. Such information may include information about charging of the wireless power transfer device <NUM>, information about charging of the electronic device <NUM>, and various faults (e.g., defects, overheating, etc.). More details regarding what information the wireless power transfer device <NUM> may communicate to the user will be described below with reference to FIGS. <NUM>-<NUM>. The wireless power transfer device <NUM> may communicate the information via any suitable means, for example, auditory signals, visual signals, and/or haptic feedback signals (e.g., vibrational signals). For example, referring to <FIG>, the charger <NUM> may include a human interface circuit that includes a piezoelectric based speaker, a vibration motor, and/or an LED light configured to communicate information.

The electronic device <NUM> may be an implantable device (e.g., a device that is configured to be inserted in vivo). In some embodiments where the electronic device <NUM> is an implantable medical device, the electronic device <NUM> may include a casing <NUM> that encases the components of the electronic device <NUM>. In some embodiments, as shown in <FIG>, the entire casing <NUM> may include a metallic material. In some other embodiments, as shown in <FIG>, a first portion 21A of the casing <NUM> may include a ceramic material and a second portion of 21B of the casing <NUM> may include a metallic material. The first portion 21A may cover the receiver coil <NUM>, and the second portion 21B may cover the other components of the electronic device <NUM> (e.g., the detector <NUM> and the transmitter <NUM>). The size and configuration of the first and second portions 21A and 21B may depend, for example, on the sizes, shapes, and relative positions of the receiver coil <NUM> and the other components of the electronic device <NUM>. In some embodiments, a portion of the casing <NUM> may include a plastic, an epoxy, and/or a polymer material.

The electronic device <NUM> is not limited to implantable devices or medical devices, and the electronic device <NUM> may be any suitable device configured to receive power and/or generate an electrical current via electromagnetic induction. In some embodiments, the electronic device <NUM> may be configured to store energy of the current generated in the receiver coil <NUM>, for example, in a capacitor. However, the present disclosure is not limited thereto, and the electronic device <NUM> may be configured in some embodiments to utilize the current without storing the energy of the current. For example, energy of the current generated in the receiver coil <NUM> may be utilized to drive or power other components in the electronic device <NUM>.

When the electronic device <NUM> is in the proximity of the wireless power transfer device <NUM>, and the wireless power transfer device <NUM> generates an oscillating magnetic field, a current may be generated in the receiver coil <NUM> by electromagnetic induction via the oscillating magnetic field. The receiver coil <NUM> may be, for example, a solenoid with a ferrimagnetic (e.g., soft ferrite) core.

The detector <NUM> may be electrically coupled (e.g., electrically connected) to the receiver coil <NUM> and configured to detect information about the current (e.g., the power or amplitude of the current) generated in the receiver coil <NUM>.

The transmitter <NUM> may transmit the information detected by the detector <NUM> to the receiver <NUM> of the wireless power transfer device <NUM>, but the present disclosure is not limited thereto. The transmitter <NUM> may be configured to transmit the information to any suitable receiver outside of the electronic device <NUM> that is able to receive the information transmitted by the transmitter <NUM>. In some embodiments, the transmitter <NUM> transmits information wirelessly, for example, via Bluetooth™ low energy (BLE).

Aligning the orientation of magnetic field at the receiver coil <NUM> with the receiver coil <NUM> increases the efficiency at which the wireless power transfer device <NUM> transfers power to the electronic device <NUM> compared to otherwise comparable wireless power transfer devices and receiver coils in which the magnetic field is misaligned. Accordingly, the wireless power transfer device <NUM> may rotate the magnetic field in order to align (e.g., optimally align) the magnetic field with the receiver coil <NUM>.

A feedback system that monitors (e.g., directly or indirectly monitors) the relative direction of the magnetic field at the receiver coil <NUM> may be utilized to align (or to enable an operator to align) the magnetic field with the receiver coil <NUM>. The feedback system may allow the wireless power transfer device <NUM> to automatically align the magnetic field with, or to create a magnetic field that is aligned with, the receiver coil <NUM> at the receiver coil <NUM> without requiring a user to manually adjust the position and/or orientation of the wireless power transfer device <NUM> after placing the wireless power transfer device <NUM> in proximity with the electronic device <NUM>. Two example feedback systems will now be described in more detail.

In a first feedback system, the wireless power transfer device <NUM> generates an initial magnetic field and rotates the initial magnetic field (e.g., in the manner described above with reference to <FIG>). As the initial magnetic field is rotated, the detector <NUM> detects information (e.g., power or amplitude) of the current generated in the receiver coil <NUM>. The power received in the receiver coil <NUM> (e.g., the power of the current generated in the receiver coil <NUM>) may correlate with how aligned the initial magnetic field is with the receiver coil <NUM>. Accordingly, a maximum detected power may correspond to alignment (e.g., optimal alignment) between the initial magnetic field and the receiver coil <NUM>. The maximum detected power also indicates what values of the first amplitude, the second amplitude, and the relative phase between the first and second AC currents generate a magnetic field that will be aligned with the receiver coil <NUM>. After this information is obtained, the wireless power transfer device <NUM> may generate a magnetic field aligned with the receiver coil <NUM> to charge (or drive) the electronic device <NUM>.

In a second feedback system, load modulation may be utilized. Load modulation is described in Griffith, <CIT> and <NPL>), the entire content of each of which is incorporated herein by reference.

In the second feedback system, the wireless power transfer device <NUM> may generate an initial magnetic field and rotate the initial magnetic field (e.g., in the manner described above with reference to <FIG>). The electronic device <NUM> may include a modulation resistance coupled (e.g., connected in parallel) to the receiver coil <NUM>, and the modulation resistance can be turned on and off to cause the receiver coil <NUM> to transmit a signal back to the wireless power transfer device <NUM> while the electronic device <NUM> receives power from the wireless power transfer device <NUM>. Information in the signal may be controlled, for example, by the clock rate at which the modulation resistance is turned on and off. The signal may include information about how aligned (i.e., the degree or extent of alignment) the initial magnetic field is with the receiver coil <NUM>. The signal may be measured by a demodulator in the wireless power transfer device <NUM> that is coupled to one or both of the first and second transmitting coils <NUM> and <NUM>. The information in the signal may be utilized to determine what values of the first amplitude, the second amplitude, and the relative phase between the first and second AC currents generate a magnetic field that will be aligned with the receiver coil <NUM>. After this information is obtained, the wireless power transfer device <NUM> may generate a magnetic field that is aligned with the receiver coil <NUM> to charge (or drive) the electronic device <NUM>.

In some embodiments, the values of the first amplitude, the second amplitude, and the phase difference between the first and second AC currents that can generate a magnetic field that is aligned with the receiver coil <NUM> may be determined after the wireless power transfer device <NUM> rotates the magnetic field through a range of degrees (e.g., the wireless power transfer device <NUM> sweeps the magnetic field through a range of orientations), for example, a full <NUM>° sweep (<NUM>° when taking into account the oscillating nature of the magnetic field), but the present disclosure is not limited thereto. For example, information regarding how aligned the initial magnetic field is with the receiver coil <NUM> may be continuously monitored, and the wireless power transfer device <NUM> (e.g., the controller <NUM> of the wireless power transfer device <NUM>) may stop the rotation when alignment (e.g., optimal alignment) between the initial magnetic field and the receiver coil <NUM> has been detected. The wireless power transfer device <NUM> may then charge (or drive) the electronic device <NUM>.

The wireless power transfer device <NUM> may be configured to transfer power to the electronic device <NUM> regardless of where the electronic device <NUM> is positioned relative to the wireless power transfer device <NUM>. For example, <FIG> and <FIG> show schematic side views of the wireless power transfer device <NUM> and electronic device <NUM> of the wireless power transfer system of <FIG> with the electronic device <NUM> in two different positions relative to the wireless power transfer device <NUM>. That is, <FIG> and <FIG> show side views of a plane substantially defined by the first and second transmitting coils <NUM> and <NUM>. <FIG> shows a non-limiting example where the wireless power transfer device <NUM> transfers power to the electronic device <NUM> while being positioned above (e.g., while an area of overlap between the first and second transmitting coils <NUM> and <NUM> is positioned above) the electronic device <NUM>. <FIG> shows a non-limiting example where the wireless power transfer device <NUM> transfers power to the electronic device while the electronic device <NUM> is positioned at the side of the wireless power transfer device <NUM> (e.g., at the side of the first and second transmitting coils <NUM> and <NUM>).

Various modes of operating a wireless power transfer system will now be described in more detail with reference to <FIG>. <FIG> illustrates an initialization mode; <FIG> illustrates an error mode; <FIG> illustrates a find the electronic device mode; <FIG> illustrates an optimize location mode; <FIG> illustrates an electronic device charging mode; and <FIG> illustrates a wireless power transfer device charging mode.

Referring to <FIG>, an Initialization mode may begin at stage S100. The initialization mode may begin, for example, when the wireless power transfer device <NUM> is placed in the charging cradle <NUM>, when a charge button is pressed, or when the wireless power transfer device <NUM> is trying to recover from a recoverable error. The charge button may be a button on the wireless power transfer device <NUM> that allows a user to initialize the wireless power transfer device <NUM> for charging the electronic device <NUM>.

At stage S101, the wireless power transfer device <NUM> may determine whether a voltage of an internal battery (e.g., a rechargeable battery) of the wireless power transfer device <NUM> is greater than or equal to a minimum voltage. If the voltage of the internal battery is less than the minimum voltage, then the wireless power transfer device <NUM> may repeat stage S101. However, if the voltage of the internal battery is greater than or equal to the minimum voltage, the wireless power transfer device <NUM> may initialize the system of the wireless power transfer device <NUM> at stage S102.

After the wireless power transfer device <NUM> is initialized at stage S102, the wireless power transfer device <NUM> may perform a power up self-test at stage S103. For example, the wireless power transfer device <NUM> may test for internal faults (e.g., defects) or errors during stage S103, and the wireless power transfer device <NUM> may begin an error mode at stage S200 if the wireless power transfer device <NUM> detects an error such that the power up self-test fails. However, if at stage S103 the power up self-test is passed, the wireless power transfer device <NUM> may measure a voltage of the internal battery at stage S104 and communicate to the user the SoC of the internal battery at stage S105.

At stage S106, the wireless power transfer device <NUM> may determine whether the SoC of the internal battery is sufficient to charge (or drive) the electronic device <NUM>. If the SoC of the internal battery is insufficiently low, the wireless power transfer device <NUM> may alert the user at S107 and proceed to stage S108. However, if at stage S106 the SoC is determined to be sufficient, the wireless power transfer device <NUM> may determine whether the charge button has been pressed at stage S108.

If the charge button has been pressed, the wireless power transfer device <NUM> may determine whether it is in a self-charging mode at stage S109. If the wireless power transfer device <NUM> is not in the self-charging mode, then the wireless power transfer device <NUM> may begin the find electronic device mode at stage S300. However, if at stage S109 the wireless power transfer device <NUM> is in the self-charging mode, the wireless power transfer device <NUM> may proceed to stage S110. Furthermore, if at stage S108 it is determined that the charge button has not been pressed, the wireless power transfer device <NUM> may detect whether a power supply from the charging cradle <NUM> is available.

If the wireless power transfer device <NUM> detects the power supply from the charger cradle <NUM>, the wireless power transfer device <NUM> may begin the wireless power transfer device charging mode at stage S600. However, if at stage S110 the wireless power transfer device <NUM> does not detect the power supply from the charger cradle <NUM>, the wireless power transfer device <NUM> may determine at stage S111 whether a set (e.g., predetermined) amount of time has passed since a previous stage, for example, stage S102 or stage S103.

If the wireless power transfer device <NUM> determines that the set amount of time has not elapsed, then the wireless power transfer device <NUM> may proceed to stage S104. However, if the set amount of time has elapsed, then the wireless power transfer device <NUM> may turn off at stage S112.

Referring to <FIG>, after the error mode begins at stage S200, the wireless power transfer device <NUM> may determine at stage S201 whether it is able to recover from (e.g., resolve or remedy) the fault. If the wireless power transfer device <NUM> is able to recover from the fault, the wireless power transfer device <NUM> may begin the initialization mode at stage S100. However, if the wireless power transfer device <NUM> is unable to recover from the fault, the wireless power transfer device <NUM> may alert the user at stage S202 that the wireless power transfer device <NUM> is unable to recover. The wireless power transfer device <NUM> may then end the error mode at stage S203. In some embodiments, the wireless power transfer device <NUM> may turn off at stage S203.

Referring to <FIG>, after the find electronic device mode begins at stage S300, the wireless power transfer device <NUM> may communicate to the user that the find electronic device mode has started. The wireless power transfer device <NUM> may drive the first and second transmitting coils <NUM> and <NUM> to generate and rotate an initial magnetic field at stage S302. At stage S303, the wireless power transfer device <NUM> may be placed at an initial position in approximate or estimated proximity to the electronic device <NUM>, and the wireless power transfer device <NUM> may be moved slowly around the initial position. At stage S304, the wireless power transfer device <NUM> may communicate information to the user regarding whether the electronic device <NUM> has been located, for example, by receiving a signal from the electronic device <NUM>, while the wireless power transfer device <NUM> is moved around the initial position.

The wireless power transfer device <NUM> may determine at stage S305 whether the electronic device <NUM> has been located within a set amount of time, for example, from a previous stage such as S303. If the electronic device <NUM> has not been located when the set amount of time elapses, the wireless power transfer device <NUM> may stop driving the first and second transmitting coils <NUM> and <NUM> to terminate the initial magnetic field at stage S306. The wireless power transfer device <NUM> may then communicate to the user that the electronic device <NUM> was not found at stage S307, and the wireless power transfer device <NUM> may turn off at stage S308. However, if at stage S305 the wireless power transfer device <NUM> determines within the set amount of time that the electronic device <NUM> has been found, then the wireless power transfer device <NUM> may communicate to the user that the electronic device <NUM> has been found at stage S309. The wireless power transfer device <NUM> may then begin an optimize location mode at stage S400.

Referring to <FIG>, after the optimize location mode begins at stage S400 and at stage S401, the wireless power transfer device <NUM> may be slowly moved, for example, from a second position where the wireless power transfer device <NUM> was located when the electronic device <NUM> was found. The wireless power transfer device <NUM> may continuously communicate information to the user at stage S402 while the wireless power transfer device <NUM> is being moved. The information communicated at stage S402 may include whether the initial magnetic field is aligned with the receiver coil <NUM> and whether power delivered to the electronic device <NUM> is increasing or decreasing. The wireless power transfer device <NUM> may determine whether the initial magnetic field is aligned with the receiver coil <NUM> by utilizing a feedback system as described above.

At stage S403, the wireless power transfer device <NUM> may determine whether the initial magnetic field is aligned with the receiver coil <NUM>. If the initial magnetic field is not aligned, the wireless power transfer device <NUM> may rotate the initial magnetic field as needed (e.g., by utilizing a feedback system as described above) at stage S404 to automatically align the initial magnetic field with the receiver coil <NUM>. However, if at stage S403 the wireless power transfer device <NUM> determines that the initial magnetic field is aligned with the receiver coil <NUM>, then the wireless power transfer device <NUM> may determine at stage S405 whether power delivered to the electronic device <NUM> is increasing as the wireless power transfer device <NUM> is moved. The wireless power transfer device <NUM> may then communicate to the user whether the wireless power transfer device <NUM> is being moved away from the electronic device <NUM> (stage S406) or toward the electronic device <NUM> (stage S407).

At stage S408, the wireless power transfer device <NUM> may determine whether the receiver coil <NUM> is saturated. Saturation of the receiver coil <NUM> may occur when an increase in magnitude of the initial magnetic field at the receiver coil <NUM> does not significantly increase the magnetization of the core material (e.g., ferrimagnetic material) of the receiver coil <NUM>. If it is determined that the receiver coil <NUM> is saturated, the first and second amplitudes of the first and second currents used to generate the initial magnetic field may be reduced at stage S409, and the wireless power transfer device <NUM> may again determine whether the receiver coil <NUM> is saturated at stage S408. However, if at stage S408 it is determined that the receiver coil <NUM> is not saturated, the wireless power transfer device <NUM> may determine whether the wireless power transfer device <NUM> is at an optimal position and/or orientation at stage S410. The optimal position and/or orientation may correspond to a position and/or orientation of the wireless power transfer device <NUM> that results in a maximum power received in the receiver coil at set amplitudes of the first and second AC currents that do not saturate the receiver coil <NUM>.

If it is determined that the wireless power transfer device <NUM> is at an optimal position and/or orientation, the wireless power transfer device <NUM> may communicate to the user to stop moving the wireless power transfer device <NUM> at stage S411, and the wireless power transfer device <NUM> may begin the electronic device charging mode at stage S500. However, if at stage S410 it is determined that the wireless power transfer device <NUM> is not at an optimal position and/or orientation, the wireless power transfer device <NUM> may conduct a test to detect faults at stage S412. If a fault is detected, the wireless power transfer device <NUM> may begin the error mode at stage S200. However, if no faults are detected, the wireless power transfer device <NUM> may determine whether information from the electronic device <NUM> is still being received at stage S413.

If information from the electronic device <NUM> is still being received, the user may continue to move the wireless power transfer device <NUM> at stage S401. For example, the wireless power transfer device <NUM> may prompt the user to continue to move the wireless power transfer device <NUM>. However, if at stage S413 the wireless power transfer device <NUM> determines that information is not being received from the electronic device <NUM>, the wireless power transfer device <NUM> may communicate to the user at stage S414 that the electronic device <NUM> has been lost, and the wireless power transfer device <NUM> may begin the find electronic device mode at stage S300.

Referring to <FIG>, after the electronic device charging mode begins at stage S500, information from the electronic device <NUM> may be continuously received and monitored at stage S501, and the wireless power transfer device <NUM> may communicate information about the electronic device <NUM> (e.g., SoC of a battery or of an energy storage in the electronic device <NUM>) to the user at stage S502.

At stage S503, the wireless power transfer device <NUM> may determine whether the electronic device <NUM> has reached a set SoC of the electronic device <NUM>. For example, the wireless power transfer device <NUM> may determine whether the electronic device <NUM> has reached a fully charged state. If the electronic device <NUM> has reached the set SoC, the wireless power transfer device <NUM> may stop driving the first and second transmitting coils <NUM> and <NUM> at stage S504 to terminate the magnetic field generated by the wireless power transfer device <NUM>. The wireless power transfer device <NUM> may then communicate to the user that the charge is complete at stage S505 before turning off at stage S506.

However, if at stage S503 the wireless power transfer device <NUM> determines that the set SoC of the electronic device <NUM> has not been reached, it may regulate power transmission to the electronic device <NUM> at stage S507. For example, the wireless power transfer device <NUM> may change the amplitudes of the first and second AC currents to reduce or increase the power provided to the electronic device <NUM>.

At stage S508, the wireless power transfer device <NUM> may determine whether transmission power is at or above a set or predetermined threshold. If the transmission power is at or above the set or predetermined threshold, the wireless power transfer device <NUM> may turn off the first and second transmitting coils <NUM> and <NUM> at stage S509 to terminate the magnetic field. The wireless power transfer device <NUM> may then communicate to the user that the electronic device <NUM> has been lost at stage S510 and begin the find electronic device mode at stage S300.

However, if at stage S508 the wireless power transfer device <NUM> determines that the transmission power is below the set or predetermined threshold, then the wireless power transfer device <NUM> may determine whether any faults have occurred in the wireless power transfer device <NUM> and/or in the electronic device <NUM> at stage S511. If a fault is detected, the wireless power transfer device <NUM> may turn off the first and second transmitting coils <NUM> and <NUM> at stage S512. The wireless power transfer device <NUM> may then communicate to the user that a fault has been found and begin the error mode at stage S200.

However, if at stage S511 the wireless power transfer device <NUM> does not detect any faults, the wireless power transfer device <NUM> may proceed to stage S501 and continue to receive and monitor information received from the electronic device <NUM>.

Referring to <FIG>, the wireless power transfer device <NUM> may begin charging an internal battery via a power supply provided by the charging cradle <NUM> at stage S600 of the wireless power transfer device charging mode. The wireless power transfer device <NUM> may determine a SoC of the internal battery at stage S601 and communicate the SoC to the user at stage S602. At stage S603, the wireless power transfer device <NUM> may determine whether a set SoC of the internal battery has been reached. For example, the wireless power transfer device <NUM> may determine whether the internal battery has been fully charged.

If the wireless power transfer device <NUM> determines that the set SoC of the internal battery has been reached, the wireless power transfer device <NUM> may stop charging the internal battery at stage S604, communicate to the user that the charging process is complete at stage S605, and turn off at stage S606.

However, if at stage S603 the wireless power transfer device <NUM> determines that the internal battery has not reached the set SoC, the wireless power transfer device <NUM> may determine whether the wireless power transfer device <NUM> is still coupled to (e.g., on or in) the charger cradle <NUM> and receiving power from the charger cradle <NUM>. If the wireless power transfer device <NUM> is not coupled to the charger cradle <NUM> or not receiving power from the charger cradle <NUM>, the wireless power transfer device <NUM> may stop charging the internal battery at stage S608, communicate to the user that the charging process has stopped at stage S609, and begin the error mode at stage S200.

However, if at stage S607 the wireless power transfer device <NUM> determines that the wireless power transfer device <NUM> is coupled to the charger cradle <NUM> and is receiving power from the charger cradle <NUM>, the wireless power transfer device <NUM> may continue to charge the internal battery at stage S610. At stage S611, the wireless power transfer device <NUM> may determine whether faults have occurred in the wireless power transfer device <NUM> and/or in the internal battery at stage S611. If a fault is detected, the wireless power transfer device <NUM> may stop the charging process at stage S612, communicate to the client that the charging process has stopped at stage S613, and begin the error mode at stage S200.

However, if at stage S611 the wireless power transfer device <NUM> does not detect any faults, the wireless power transfer device <NUM> may proceed to stage S601 to determine the SoC of the internal battery.

Claim 1:
A wireless power transfer system comprising a wireless power transfer device (<NUM>), the wireless power transfer device (<NUM>) comprising:
a first transmitting coil (<NUM>) oriented along a first axis (100A);
a second transmitting coil (<NUM>) on the first transmitting coil (<NUM>) and oriented along a second axis (200A) different from the first axis (100A);
a nonmagnetic material magnetically decoupling the first transmitting coil (<NUM>) from the second transmitting coil (<NUM>) in an area of overlap (<NUM>) between the first (<NUM>) and second (<NUM>) transmitting coils;
characterised in that the wireless power transfer device (<NUM>) further comprises a driver (<NUM>) configured to provide a first current to the first transmitting coil (<NUM>) and a second current to the second transmitting coil (<NUM>) to generate a magnetic field,
wherein the driver (<NUM>) is configured to differentially drive the first (<NUM>) and second (<NUM>) transmitting coils with the first and second currents, respectively, to control a direction of the magnetic field.