Tunable impedance circuit for wireless charging devices

Abstract

We provide a wireless charging pad that allows you to adjust the impedance of a tunable impedance circuit in order to adjust the resonant frequency. [Solution] The wireless charging pad includes an H-bridge circuit which is a switching circuit, a resonant tank, and an impedance control circuit. The resonant tank includes a coil having a resonant frequency, electrically connected to the switching circuit and arranged for wireless power transmission, and a tunable impedance circuit. The impedance control circuit adjusts the impedance of the tunable impedance circuit to adjust the resonant frequency of the resonant tank.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims priority to U.S. Provisional Patent Application No. 63 / 705,359, filed on October 9, 2024, and entitled "TUNABLE IMPEDANCE CIRCUITS FOR WIRELESS CHARGING DEVICE", and U.S. Patent Application No. 19 / 324,982, filed on September 10, 2025, and entitled "TUNABLE IMPEDANCE CIRCUITS FOR WIRELESS CHARGING DEVICE", the technical disclosures of which are hereby incorporated by reference in their entirety for all purposes.

[0002] This disclosure relates to systems and methods for wireless charging. More specifically, embodiments of the present disclosure relate to efficient wireless power transfer between a wireless power transmitter and a wireless power receiver by adjusting impedance.

Background Art

[0003] <L000021>Batteries are components of a wide range of battery - powered devices, equipment, or various transportation platforms, such as electric vehicles, robots, electric bikes, electric motorcycles, drones, and many other types of devices. Batteries can be paired with wireless charging devices and arranged to receive energy through electromagnetic coupling between a receiving pad and the wireless charging device. Specifically, a wireless charging device can use one or more internal coils to induce an electromagnetic field, and one or more corresponding receiving coils connected to the battery can capture these electromagnetic fields within a specific proximity to the charging device. There are various technical challenges associated with wireless charging.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Each of the systems, methods, and devices disclosed herein has several innovative embodiments, but not one alone embodies all of the desirable characteristics disclosed herein. Details of one or more implementations of the subject matter described herein are given in the accompanying drawings and the following description.

[0005] In some embodiments, the technology described herein relates to a wireless charging pad, the wireless charging pad comprising a switching circuit and a resonant tank having a resonant frequency and being electrically connected to the switching circuit, the resonant tank including a coil arranged for wireless power transmission, the resonant tank including a tunable (variable, adjustable) impedance circuit, and an impedance control circuit configured to adjust the impedance of the tunable impedance circuit to adjust the resonant frequency of the resonant tank.

[0006] In some embodiments, the technology described herein relates to a wireless charging pad, wherein the tunable impedance circuit includes a switch and a capacitor, and the impedance control circuit is configured to adjust the impedance of the tunable impedance circuit by changing the state of the switch.

[0007] In some embodiments, the technology described herein relates to a wireless charging pad, wherein the switch is in parallel with the capacitor.

[0008] In some embodiments, the technology described herein relates to a wireless charging pad, wherein the switch is in series with a capacitor.

[0009] In some embodiments, the technology described herein relates to a wireless charging pad, wherein the tunable impedance circuit includes a plurality of series circuits in parallel with each other, each of which includes a switch in series with a capacitor.

[0010] In some embodiments, the technology described herein relates to a wireless charging pad, wherein the tunable impedance circuit includes a plurality of parallel circuits in series with respect to each other, and each of the parallel circuits includes a switch in parallel with a capacitor.

[0011] In some embodiments, the technology described herein relates to a wireless charging pad, wherein the wireless charging pad is a grounding pad.

[0012] In some embodiments, the technology described herein relates to a wireless charging pad, wherein the wireless charging pad is a vehicle pad.

[0013] In some embodiments, the technology described herein relates to a wireless charging pad, and the switching circuit includes an H-bridge circuit.

[0014] In some embodiments, the technology described herein relates to a wireless charging pad, and the switching circuit includes a stacked half-bridge circuit.

[0015] In some embodiments, the technology described herein relates to a wireless charging pad, wherein the impedance control circuit is configured to adjust the impedance based on a mismatch between the resonant frequency of a resonant tank and the resonant frequency of a second resonant tank circuit of a second wireless charging pad positioned adjacent to the wireless charging pad for wireless charging.

[0016] In some embodiments, the technology described herein relates to a wireless charging pad, wherein the resonant tank includes a capacitor, and the tunable impedance circuit, coil, and capacitor are electrically connected in series.

[0017] In some embodiments, the technology described herein relates to a wireless charging pad, wherein the resonant tank includes a capacitor connected in series with a coil, and the tunable impedance circuit and coil are connected in parallel.

[0018] In some aspects, the techniques described herein relate to a wireless charging pad, the resonant tank has an LCC architecture, and the tunable impedance circuit is connected in series with the inductor of the resonant tank.

[0019] In some aspects, the techniques described herein relate to a wireless charging pad, the resonant tank has an LCC architecture, and the tunable impedance circuit is connected in parallel with the inductor of the resonant tank.

[0020] In some aspects, the techniques described herein relate to a wireless charging pad, and the tunable impedance circuit and the coil are connected in series.

[0021] In some aspects, the techniques described herein relate to a method of wireless power transfer, the method including detecting an inconsistency in a resonant frequency between a first resonant tank of a ground pad and a second resonant tank of a vehicle pad, adjusting an impedance of a tunable impedance circuit based on the detection to reduce the inconsistency in the resonant frequency, and wirelessly transmitting power from the ground pad to the vehicle pad after the adjustment.

[0022] In some aspects, the techniques described herein relate to a method, wherein the first resonant tank of the ground pad includes a tunable impedance circuit.

[0023] In some aspects, the techniques described herein relate to a method, wherein the second resonant tank of the vehicle includes a tunable impedance circuit.

[0024] In some aspects, the techniques described herein relate to a method, wherein the inconsistency in the resonant frequency is related to a misalignment between the ground pad and the vehicle pad.

[0025] In some aspects, the techniques described herein relate to a method, and the resonance frequency mismatch is related to at least one of a vehicle platform, an object disposed between a ground pad and a vehicle pad, or a manufacturing process.

[0026] In some aspects, the techniques described herein relate to a method, and the tunable impedance circuit includes a switch and a capacitor, and adjusting the impedance includes switching the state of the switch.

[0027] In some aspects, the techniques described herein relate to a method, and the tunable impedance circuit includes a switch and a capacitor, and adjusting includes changing the state of the switch.

[0028] In some aspects, the techniques described herein relate to a method, and the switch is in parallel with the capacitor.

[0029] In some aspects, the techniques described herein relate to a method, and the switch is in series with the capacitor.

[0030] In some aspects, the techniques described herein relate to a method, and the tunable impedance circuit includes a plurality of series circuits in parallel with each other, and each of the series circuits includes a switch in series with a capacitor.

[0031] In some aspects, the techniques described herein relate to a method, and the tunable impedance circuit includes a plurality of parallel circuits in series with each other, and each of the parallel circuits includes a switch in parallel with a capacitor.

Brief Description of the Drawings

[0032] These and other features, aspects, and advantages of the present disclosure are described with reference to the drawings of particular embodiments. It should be understood that the accompanying drawings, which are incorporated herein and form a part of this specification, are for the purpose of illustrating the concepts disclosed herein and are not to scale.

[0033] [Figure 1A] This document illustrates an exemplary wireless charging environment in which embodiments of the present disclosure may be implemented.

[0034] [Figure 1B] Figure 1A is a block diagram showing an exemplary wireless charging environment according to some embodiments of the present disclosure.

[0035] [Figure 1C] This disclosure shows representations of grounding pads that can function as wireless charging devices, according to several embodiments of this disclosure.

[0036] [Figure 2] Figures 2A to 2D show exemplary circuit schematics of wireless charging systems according to several embodiments of the present disclosure.

[0037] [Figure 3] An exemplary block diagram of a wireless charging pad according to several embodiments of the present disclosure is shown.

[0038] [Figure 4A] The following are exemplary switch configurations of the H-bridge circuit of the wireless charging pad shown in Figure 3, according to some embodiments of the present disclosure. [Figure 4B] The following are exemplary switch configurations of the H-bridge circuit of the wireless charging pad shown in Figure 3, according to some embodiments of the present disclosure. [Figure 4C] The following are exemplary switch configurations of the H-bridge circuit of the wireless charging pad shown in Figure 3, according to some embodiments of the present disclosure. [Figure 4D] The following are exemplary switch configurations of the H-bridge circuit of the wireless charging pad shown in Figure 3, according to some embodiments of the present disclosure.

[0039] [Figure 5A] This is an exemplary schematic circuit diagram of a wireless charging system having a tunable impedance circuit according to some embodiments of the present disclosure. [Figure 5B] This is an exemplary schematic circuit diagram of a wireless charging system having a tunable impedance circuit according to some embodiments of the present disclosure. [Figure 5C] This is an exemplary schematic circuit diagram of a wireless charging system having a tunable impedance circuit according to some embodiments of the present disclosure. [Figure 5D] This is an exemplary schematic circuit diagram of a wireless charging system having a tunable impedance circuit according to some embodiments of the present disclosure. [Figure 5E] This is an exemplary schematic circuit diagram of a wireless charging system having a tunable impedance circuit according to some embodiments of the present disclosure.

[0040] [Figure 6A] The following are illustrative schematic circuit diagrams of tunable impedance circuits for wireless charging according to several embodiments of the present disclosure. [Figure 6B] The following are illustrative schematic circuit diagrams of tunable impedance circuits for wireless charging according to several embodiments of the present disclosure. [Figure 6C] The following are illustrative schematic circuit diagrams of tunable impedance circuits for wireless charging according to several embodiments of the present disclosure. [Figure 6D] The following are illustrative schematic circuit diagrams of tunable impedance circuits for wireless charging according to several embodiments of the present disclosure. [Figure 6E] The following are illustrative schematic circuit diagrams of tunable impedance circuits for wireless charging according to several embodiments of the present disclosure. [Modes for carrying out the invention]

[0041] The following detailed descriptions of specific embodiments present various descriptions of those specific embodiments. However, the novel ideas described herein may be embodied in many different ways, for example, as defined and covered by the claims. In this description, similar reference numerals and / or terms refer to drawings in which identical or functionally similar elements may be shown. It will be understood that the elements shown in the drawings are not necessarily drawn to scale. Furthermore, it will be understood that a particular embodiment may include more elements and / or subsets of elements shown in the drawings than those shown. Furthermore, some embodiments may incorporate any suitable combination of features from two or more drawings. The headings provided herein are for convenience only and do not necessarily affect the claims or their meaning. introduction

[0042] Aspects of this disclosure relate to systems and methods for wirelessly charging a battery pack via wireless power transmission. This disclosure discloses a wireless charging device including a tunable impedance circuit. The tunable impedance circuit may be specifically designed to adjust the impedance of a wireless power charging system. Exemplaryly, the tunable impedance circuit may be implemented on the transmitter side and / or receiver side of a wireless charging system. The tunable impedance circuit can adjust the impedance on the transmitter side and / or receiver side to efficiently transmit wireless power.

[0043] Generally speaking, efficient wireless power transmission between a wireless power transmitter and receiver in a wireless charging system can be achieved by reducing the mismatch in resonant frequencies between the transmitter and receiver. For example, if the resonant frequencies of the resonant tanks of the transmitter and receiver of a wireless charging system are mismatched, the wireless power generated by the transmitter's coil may not be fully (or efficiently) transmitted to the receiver's coil. Therefore, reducing the mismatch in resonant frequencies between the transmitter and receiver of a wireless charging system can be important for achieving efficient wireless power transmission. The resonant frequency is based on the impedance of the transmitter and receiver of the wireless charging system. For example, the resonant frequency of a resonant tank can be changed by adjusting the impedance of the resonant tank of the transmitter or receiver. Adjusting the impedance may include adjusting the capacitance and / or inductance of the resonant tank. Since the resonant frequency of a tank circuit can be set based on the capacitance and inductance of the tank circuit, the resonant frequency of the tank circuit can be shifted by adjusting the impedance. Maximum power transmission between the transmitter and receiver of a wireless charging system can be achieved when the resonant frequencies of the transmitter and receiver are the same.

[0044] As disclosed herein, a tunable impedance circuit can adjust the resonant frequency of a tank circuit before and / or during a wireless charging process. Exemplarily, a wireless charging device may incorporate an electrical circuit that generates an AC signal and a transmitting coil that induces an electromagnetic field. The AC signal may be supplied to the transmitting coil at a specific resonant frequency. The resonant frequency may be based on the impedance of a tunable impedance circuit in a resonant tank. By matching the resonant frequencies of the tank circuit, including these coils, power can be efficiently transmitted from the transmitting coil to the receiving coil. The tunable impedance circuits disclosed herein can adjust impedance in a variety of wireless charging environments.

[0045] In various embodiments, wireless charging devices may be used to charge vehicles such as electric vehicles having a battery pack. In these embodiments, the wireless charging device may be implemented as a grounding pad or a vehicle pad. For example, a grounding pad may be located beneath the vehicle pad of an electric vehicle for charging the electric vehicle. A wireless charging DC / DC converter (also called an integrated DC / DC power converter) may include a DC / AC inverter in the grounding pad and an AC / DC rectifier in the vehicle pad. Power may be transmitted wirelessly from the grounding pad to the vehicle pad. In some embodiments, the vehicle pad may also transmit wireless power by receiving a DC signal from the vehicle's battery pack. For example, the vehicle pad may receive a DC signal from the battery pack and convert it to an AC signal by implementing a DC / AC inverter.

[0046] Wireless power transmission in wireless charging systems may have technical limitations regarding its efficiency, such as inductance changes that reduce the efficiency of wireless power transmission between the wireless power transmitting device (e.g., grounding pad) and the wireless power receiving device (e.g., vehicle pad). For example, such inductance changes can result from a variety of factors, such as misalignment between the charging pad and the vehicle, differences in vehicle platforms (sedan, sports utility vehicle, truck, etc.), metal objects such as floor or underground rebar (one or more), manufacturing tolerances, or one or more of the same kind. Such inductance changes can affect the resonant frequency of the grounding pad (ground side) and / or cause mismatch in the vehicle pad (e.g., the vehicle's receiving coil on the vehicle side). This resonant frequency mismatch between the grounding pad and the vehicle pad can lead to inefficiencies in wireless power transmission by drawing higher currents, resulting in increased energy consumption as the system draws more current to maintain the same power level. Such resonant frequency mismatches can also result in larger phase shifts. Furthermore, the current waveforms between the charging pad and the vehicle pad may also be mismatched, resulting in additional energy consumption and higher power loss. The combination of higher current and phase shift can lead to significant energy consumption. This inefficiency can reduce the overall effectiveness of the wireless charging system. This deficiency can also drive up costs, as it will require the implementation of larger and more robust electrical and mechanical components to compensate for the power loss.

[0047] Typically, both the wireless charging device (e.g., included in the grounding pad) and the vehicle's receiving device (e.g., included in the vehicle pad) incorporate separate resonant tanks with resonant frequencies for wireless power transmission. Matching the resonant frequencies of the resonant tank circuits can result in efficient wireless power transmission. However, as mentioned above, one or more environmental conditions can cause changes in the resonant frequencies on both the charging and / or receiving sides. These mismatches in resonant frequencies can significantly contribute to the inefficiency of wireless power transmission.

[0048] To address, if not all, of the technical challenges described above, embodiments of the present disclosure relate to circuits and methods for mitigating resonant frequency mismatches and / or inductance changes. This may include mitigating resonant frequency mismatches between tank circuits on the ground side (e.g., ground pad) and the vehicle side (e.g., vehicle pad). Embodiments of the present disclosure provide various configurations of tunable impedance circuits. These tunable impedance circuits have various switch configurations, capacitor array configurations, switch positions, and capacitor array positions in a wireless charging system.

[0049] A tunable impedance circuit may be implemented within the resonant tank circuit of the grounding pad and / or vehicle pad. The tunable impedance circuit may be connected to a transmitting charging coil (e.g., within the grounding pad) or a receiving coil of a wireless charging system (e.g., within the vehicle pad). The tunable impedance circuit can influence the resonant frequency of the resonant tank. Advantageously, the resonant frequency of the resonant tank can be tuned to various environmental conditions that may result in inductance changes and resonant frequency mismatches.

[0050] In some embodiments, a tunable impedance circuit can match the resonant frequency of the vehicle pad's resonant tank with the resonant frequency of the ground pad's resonant tank. For example, the tunable impedance circuit can adjust the resonant frequency of the ground pad's resonant tank by controlling one or more switches in the tunable impedance circuit, thereby matching its resonant frequency with that of the vehicle pad's resonant tank. In various examples disclosed herein, each switch in the tunable impedance circuit may include one or more switches, such as metal oxide semiconductor field-effect transistors (MOSFETs).

[0051] The tunable impedance circuit can adjust the impedance so that the resonant frequency associated with the capacitance and inductance of the grounding pad's tank circuit is approximately equal to the resonant frequency associated with the capacitance and inductance of the vehicle pad's tank circuit, where the grounding pad and the vehicle pad are coupled for wireless charging.

[0052] The tunable impedance circuit may be adjusted once or multiple times per wireless charging cycle. The tunable impedance circuit may be adjusted before a wireless charging cycle. Alternatively or additionally, the tunable impedance circuit may be adjusted during a wireless charging cycle. Such adjustments may be dynamic or periodic. The tunable impedance circuit may be adjusted based on one or more of the following: the inductance of the tank circuit, the capacitance of the tank circuit, and the coupling coefficient. As an example, the tunable capacitance circuit may be adjusted based on the inductance of the tank circuit, the capacitance of the tank circuit, and the coupling coefficient. As another example, the tunable capacitance circuit may be adjusted based on the inductance of the tank circuit of the ground pad, the capacitance of the tank circuit of the ground pad, the coupling coefficient between the ground pad and the vehicle pad, the inductance of the tank circuit of the vehicle pad, and the capacitance of the tank circuit of the vehicle pad.

[0053] Various tunable impedance circuit configurations that can be implemented in grounding pads and / or vehicle pads are disclosed. These tunable impedance circuits can be configured in various ways by changing the state of one or more switches to adjust the effective impedance of the tunable impedance circuit. Examples of such configurations are shown, for example, in Figures 6A to 6E.

[0054] While various embodiments are described according to exemplary combinations of features, those skilled in the art will understand that the examples and feature combinations are illustrative in nature and should not necessarily be interpreted as limiting. More specifically, embodiments of this application may be applicable to various types of vehicle charging mechanisms, power supplies, interfaces, etc. Furthermore, while certain tunable impedance circuit configurations are described, such exemplary configurations should not necessarily be interpreted as limiting. Accordingly, those skilled in the art will understand that embodiments of this application are not necessarily limited to any particular type of vehicle, vehicle charging infrastructure, communication, or exemplary interaction between a vehicle, owner / user, and wireless battery charging system. Overview of Wireless Charging

[0055] Generally speaking, inductive charging, commonly referred to as wireless charging, is a type of wireless power transmission. Inductive charging uses electromagnetic induction to generate or supply electricity to a device without requiring a physical electrical connection. Specifically, various devices can be placed near a charging station or induction pad without requiring precise alignment or electrical contact, or physical docks, electrical plugs, and similar devices. Such devices include, but are not limited to, vehicles, manufacturing equipment, consumer electronics, and medical devices.

[0056] According to embodiments of this application, an inductive charging system is configured to transmit energy through inductive coupling between its components. An exemplary charging system includes a transmission component which may be configured as a charging station or charging pad. A charging pad for wirelessly transmitting power to a vehicle may be called a grounding pad. An alternating current (e.g., input current) from a power source passes through an induction coil in the charging station or charging pad. Based on the input current, the charges moving through the induction coil (e.g., grounding pad coil) generate (or induce) a magnetic field. Exemplarily, the strength of the magnetic field may vary at least in part with changes or fluctuations in the amplitude of the input current. The changing magnetic field generates an alternating current in an induction coil on a receiving device (e.g., vehicle pad coil). The induced alternating current in the receiving device can then pass through a rectifier which converts the induced alternating current into a direct current. Finally, the receiving vehicle may include additional charging components and / or systems which utilize the converted direct current to charge a battery system, supply operating power, or a combination thereof.

[0057] When an exemplary inductive charging system uses components / techniques of resonant inductive coupling, a longer distance can be obtained between the grounding pad and the vehicle pad coil. More specifically, in some embodiments, a capacitor may be connected to each inductive coil to create two LC circuits having a specific resonant frequency. The frequency of the alternating current is matched to the resonant frequency. In addition, the matched frequency may be further selected depending on the typical distance between the transmitting and receiving devices, taking peak efficiency into consideration. Furthermore, the use of other materials for the receiving coil, such as silver-plated copper or possibly aluminum, to minimize weight and reduce resistance may be utilized for the purpose of energy transmission efficiency.

[0058] Figure 1A is an illustrative diagram of an environment 100 for implementing an inductive-based wireless charging system according to various embodiments of this application. Environment 100 can, exemplary, correspond to commercial implementations such as parking lots, parking spaces, and charging booths. Environment 100 can also correspond to personal or other non-commercial implementations such as private homes. As an exemplary example, an implementation of an inductive-based wireless charging system in a non-commercial implementation may include a grounding pad 102 configured to generate a variable magnetic field by an inductive charging methodology. As also shown in Figure 1A, the grounding pad 102, also called a transmitting component, can correspond to a standalone component that may be operable to be mounted or positioned on a floor 104 or another plane. In some other embodiments, the grounding pad 102 may be integrated with or combined with other devices or components.

[0059] The grounding pad 102 may be connected to one or more power sources, such as an input from a utility company, a real-time power source (e.g., a solar or wind energy source), a stored energy cell, or a combination thereof. The power source is configured to supply an input alternating current as described herein. The grounding pad 102 may be connected to the power source via a direct electrical connection 106, such as via a junction box 108 located on the wall surface 118.

[0060] As shown in Figure 1A, in one embodiment, the grounding pad 102 corresponds to a form factor that enables the positioning of the floor 104 for wirelessly charging a vehicle having a vehicle pad coil. The grounding pad 102 may have a form factor such that the vehicle is positioned directly above the upper surface of the grounding pad 102. Exemplaryly, the dimensions of the grounding pad 102 (e.g., the height and width of the grounding pad 102) may be configured such that the distance between the upper surface of the grounding pad 102 and the bottom surface of the vehicle satisfies certain criteria such as the minimum distance between the grounding pad coil and the vehicle pad coil, and the maximum distance between the grounding pad coil and the vehicle pad coil. In some embodiments, the vehicle pad and / or grounding pad 102 (or a combination thereof) may be configured to have additional components for adjusting such distances (e.g., statically and / or dynamically) or otherwise for changing the relative orientation between the grounding pad 102 and the vehicle.

[0061] In some embodiments, the grounding pad 102 can be configured to charge the vehicle's battery pack, which may have a nominal voltage exceeding 200 volts (e.g., a nominal voltage of about 350 or 355 volts) and a maximum voltage of 400 volts. In some embodiments, the grounding pad 102 can be configured to supply 800 volts of DC power. In some embodiments, the grounding pad 102 can supply a voltage range of about 200 volts to 800 volts. The grounding pad 102 can wirelessly transmit enough power to charge the battery pack at such voltages.

[0062] Figure 1B shows a block diagram of an environment 100 including a wireless charging device 111 (e.g., a grounding pad 102) that wirelessly communicates with a vehicle 112 via an inductive-based magnetic field or the like. The wireless charging device 111 is further connected to one or more energy sources 110. Although the wireless charging device 111 is shown to have a direct connection to the energy sources 110, at least a portion of the input AC current may be supplied via a wireless transmission method. In addition, in embodiments having multiple power sources, the environment may also include various switching components for selecting energy from individual energy sources 110 or combinations of energy sources 110.

[0063] Figure 1C shows a block diagram of a grounding pad 102 that can function as a wireless charging device 111 (shown in Figure 1B). The grounding pad 102 may include at least a grounding pad coil 122 for generating a magnetic field from an input current supplied from an energy source 110. As shown in Figure 1C, the input current may be supplied by a direct electrical connection 106.

[0064] In some embodiments, the grounding pad 102 may also include various sensor components 124A, 124B, 124C, and 124D relating to the charging process. For example, sensor components 124A, 124B, 124C, and 124D may be configured for various functions such as vehicle detection, object detection, distance measurement to the vehicle, environmental sensors (e.g., temperature sensors, moisture sensors), pressure sensors, and others of the same kind. In one embodiment, sensor components 124A, 124B, 124C, and 124D may include radar sensors. Sensor components 124A, 124B, 124C, and 124D may also include logic and processing components relating to the charging process, including motion measurement, motion control, safety measurement, communication components, and others of the same kind. Wireless charging system with H-bridge circuit

[0065] Figures 2A to 2D show schematic circuit diagrams of exemplary wireless charging systems 200A to 200D. As shown in Figures 2A to 2D, each of the wireless charging systems 200A to 200D may include a grounding pad (e.g., grounding pad 102) and a vehicle pad that is attached to or otherwise integrated with the vehicle. For example, the grounding pad of wireless charging system 200A may include a capacitor 212A, an H-bridge circuit 202A, and a resonant tank 204A, as shown in Figure 2A. The vehicle pad of wireless charging system 200A may include a capacitor 214A, an H-bridge circuit 208A, and a resonant tank 206A, as shown in Figure 2A. In some embodiments, power may be transmitted from a power source (not shown in Figure 2A) to the vehicle's battery pack (not shown in Figure 2A) through the H-bridge circuit 202A, the resonant tank 204A, the resonant tank 206A, and the H-bridge circuit 208A. This power transmission may include wireless power transmission from the coil L1 of the grounding pad to the coil L2 of the vehicle pad. Any of the wireless charging systems 200A to 200D may be implemented according to any suitable principles and advantages disclosed herein.

[0066] Figure 2A shows a schematic circuit diagram of the wireless charging system 200A. As shown in Figure 2A, the wireless charging system 200A corresponds to an LCC-LCC circuit architecture. As shown, the wireless charging system 200A includes a capacitor 212A, an H-bridge circuit 202A, a resonant tank 204A, a resonant tank 206A, an H-bridge circuit 208A, and a capacitor 214A. In the LCC-LCC circuit architecture, the inductor L f1 and capacitor C f1 And C1 is coupled between the H-bridge circuit 202A and the ground pad coil L1 in the ground pad, and the inductor L f2 and capacitor C f2 And C2 is coupled between the H-bridge circuit 208A in the vehicle pad and the vehicle pad coil L2.

[0067] Figure 2B shows a schematic circuit diagram of the wireless charging system 200B. As shown in Figure 2B, the wireless charging system 200B corresponds to an LCC-series circuit architecture. As shown, the wireless charging system 200B includes a capacitor 212B, an H-bridge circuit 202B, a resonant tank 204B, a resonant tank 206B, an H-bridge circuit 208B, and a capacitor 214B. In the LCC-series circuit architecture, the inductor L f1 and capacitor C f1 And C1 is coupled between the H-bridge circuit 202A and the grounding pad coil L1 in the grounding pad, and the series capacitor C2 is coupled between the H-bridge circuit 208A and the vehicle pad coil L2 in the vehicle pad.

[0068] Figure 2C shows a schematic circuit diagram of the wireless charging system 200C. As shown in Figure 2C, the wireless charging system 200C corresponds to a series-LCC circuit architecture. As illustrated, the wireless charging system 200C includes a capacitor 212C, an H-bridge circuit 202C, a resonant tank 204C, a resonant tank 206C, an H-bridge circuit 208C, and a capacitor 214C. In the series-LCC circuit architecture, the series capacitor C1 is coupled between the H-bridge circuit 202A in the grounding pad and the grounding pad coil L1, and the inductor L f2 and capacitor C f2 And C2 is coupled between the H-bridge circuit 208A in the vehicle pad and the vehicle pad coil L2.

[0069] Figure 2D shows a schematic circuit diagram of the wireless charging system 200D. As shown in Figure 2D, the wireless charging system 200D corresponds to a series-series circuit architecture. As illustrated, the wireless charging system 200D includes a capacitor 212D, an H-bridge circuit 202D, a resonant tank 204D, a resonant tank 206D, an H-bridge circuit 208D, and a capacitor 214D. In the series-series circuit architecture, the series capacitor C1 is coupled between the H-bridge circuit 202A and the grounding pad coil L1 in the grounding pad, and the series capacitor C2 is coupled between the H-bridge circuit 208A and the vehicle pad coil L2 in the vehicle pad. Exemplary wireless charging pad

[0070] Figure 3 shows an exemplary wireless charging pad 300 according to several embodiments of the present disclosure. The wireless charging pad 300 may include an H-bridge circuit 322, a resonant tank 324, a tunable impedance circuit 600, a switch control circuit 326, and an impedance control circuit 336. The tunable impedance circuit 600 may be implemented within the resonant tank 324. The tunable impedance circuit 600 may also be a standalone circuit and may be connected to the resonant tank 324 according to various configurations, for example, as described with reference to Figures 6A to 6E.

[0071] The wireless charging pad 300 can charge the vehicle's battery pack over a relatively wide voltage range by switching an H-bridge circuit 322. The H-bridge circuit 322 is an example of a switching circuit that can supply voltage to the resonant tank 324 for wireless power transmission. Any suitable principles and advantages of the wireless charging pad 300 can be implemented in the environment according to any suitable principles and advantages shown in Figures 1A to 1C.

[0072] The wireless charging pad 300 can implement any grounding pad or vehicle pad of the wireless charging system 200A-200D. In some embodiments, the H-bridge circuit 322 can correspond to any of the H-bridge circuits 202A, 208A, 202B, 208B, 202C, 208C, 202D, and 208D. The H-bridge circuit 322 is an example of a switching circuit. In some other embodiments, any other suitable switching circuit can be implemented instead of the H-bridge circuit 322. For example, in high-voltage applications, a stacked half-bridge can be implemented instead of the H-bridge circuit. The resonant tank 324 can correspond to any of the resonant tanks 204A, 206A, 204B, 206B, 204C, 206C, 204D, and 206D.

[0073] The tunable impedance circuit 600 can be implemented within the resonant tank 324 as shown in Figures 5A to 5E below. In addition, the tunable impedance circuit 600 can accommodate any configuration shown in Figures 6A to 6B below. The impedance control circuit 336 can control some of the switches included within the tunable impedance circuit 600 as shown in Figures 6A to 6E below. In some embodiments, the switches of the tunable impedance circuit 600 can be implemented as field-effect transistors (FETs), such as metal-oxide-semiconductor field-effect transistors (MOSFETs), and / or mechanical switches, etc. In these embodiments, the impedance control circuit 336 can supply a control signal to the gate of the transistor. In such cases, the impedance control circuit 336 may be called a gate drive circuit.

[0074] The impedance control circuit 336 can generate a control signal based on the mismatch in resonant frequencies between the resonant tanks 204A-204D included in the ground pad and the resonant tanks 206A-206D included in the vehicle pad. Therefore, the impedance control circuit 336 can reduce such mismatches in resonant frequencies and improve efficiency in wireless power transmission. In some examples, the control signal may exceed the matching of resonant frequencies and may depend on one or more of the resonant frequencies (inductance and capacitance values) of both the ground and vehicle sides, as well as the ground pad DC voltage, vehicle pad DC voltage (battery voltage), charging power level, or coupling coefficient.

[0075] As shown in Figures 4A to 4D, the H-bridge circuit 322 may include switches 322-1, 322-2, 322-3, and 322-4. In some embodiments, the switch control circuit 326 may control some of switches 322-1, 322-2, 322-3, and 322-4 to periodically switch between open and closed states, rather than periodically switching each of switches 322-1, 322-2, 322-3, and 322-4, and may control some of switches 322-1, 322-2, 322-3, and 322-4 to remain open or closed without toggling.

[0076] The switch control circuit 326 can provide control signals to control the state of the switches of the H-bridge circuit 322 (for example, switches 322-1 to 322-4 in Figures 4A to 4D). The switch control circuit 326 can be implemented by any suitable circuit configuration to control the state of the switches of the H-bridge circuit 322. If the switches of the H-bridge circuit 322 have gates (for example, the switches are FETs or IGBTs), the switch control circuit 326 can provide control signals to the gates of the H-bridge. In such instances, the switch control circuit 326 may be called a gate drive circuit. Example H-bridge switch configuration

[0077] Figures 4A to 4D show exemplary switch configurations of an H-bridge circuit 322 that can be controlled by a switch control circuit 326 according to some embodiments of the present disclosure. Figure 4A shows that the H-bridge circuit 322 can be configured by the switch control circuit 326 into a switch configuration 410 which may be called a positive configuration. Figure 4B shows that the H-bridge circuit 322 can be configured by the switch control circuit 326 into a switch configuration 420 which may be called a negative configuration. Figure 4C shows that the H-bridge circuit 322 can be configured by the switch control circuit 326 into a switch configuration 430 which may be called a zero-one configuration. Figure 4D shows that the H-bridge circuit 322 can be configured by the switch control circuit 326 into a switch configuration 440 which may be called a zero-two configuration.

[0078] The H-bridge circuit 322 includes four switches: switch 322-1 (also referred to herein as "AP"), switch 322-2 (also referred to herein as "AN"), switch 322-3 (also referred to herein as "BN"), and switch 322-4 (also referred to herein as "BP"). These switches may be suitable for any power electronics, such as n-type field-effect transistors, arranged to switch a voltage sufficient for wireless charging as disclosed herein. In certain applications, the H-bridge circuit 322 may include metal-oxide-semiconductor field-effect transistors (MOSFETs). Alternatively or additionally, the H-bridge circuit 322 may include insulated-gate bipolar transistors (IGBTs). The H-bridge circuit 322 may include a first half-bridge and a second half-bridge. The first half-bridge may include switches 322-1 and 322-2. The second half-bridge may include switches 322-3 and 322-4.

[0079] As shown in Figure 4A, in switch configuration 410 (e.g., positive configuration), switch 322-1 is closed, switch 322-2 is open, switch 322-3 is closed, and switch 322-4 is open. As shown in Figure 4B, in switch configuration 420 (e.g., negative configuration), switch 322-1 is open, switch 322-2 is closed, switch 322-3 is open, and switch 322-4 is closed. As shown in Figure 4C, in switch configuration 430 (e.g., zero-one configuration), switch 322-1 is open, switch 322-2 is closed, switch 322-3 is closed, and switch 322-4 is open. As shown in Figure 4D, in switch configuration 440 (e.g., zero-two configuration), switch 322-1 is closed, switch 322-2 is open, switch 322-3 is open, and switch 322-4 is closed. Example of a tunable impedance circuit in a wireless charging pad

[0080] Figures 5A to 5E show five examples of tunable impedance circuits 600 included in the grounding pad of a wireless charging system. As shown in Figures 5A to 5E, the tunable impedance circuits 600 may be implemented within the resonant tanks 204A to 204D of the grounding pad. The tunable impedance circuits 600 can adjust the resonant frequencies of the resonant tanks 204A to 204D by adjusting the impedance of the tunable impedance circuits 600. Adjusting the impedance of the tunable impedance circuits 600 may involve controlling one or more switches (for example, one or more switches shown in Figures 6A to 6E). By adjusting the impedance of the tunable impedance circuits 600, the mismatch in resonant frequencies between the tank circuit of the grounding pad and the tank circuit of the vehicle pad can be reduced.

[0081] By adjusting the impedance of the tunable impedance circuit 600, changes in inductance between the ground pad inductor L1 and the vehicle pad inductor L2 can be compensated for. For example, one or more environmental conditions may cause such changes in inductance. One or more environmental conditions may include, but are not limited to, misalignment between the ground pad and the vehicle pad. Alternatively or additionally, the manufacturing process may result in an impedance difference between the resonant tanks of the ground pad and the vehicle pad.

[0082] The tunable impedance circuit 600 in the grounding pad can adjust the resonant frequency of the grounding pad's resonant tank to reduce mismatch with the resonant frequency of the vehicle pad's resonant tank. Figures 5A to 5E show the tunable impedance circuit 600 implemented in the grounding pad, but the tunable impedance circuit 600 can be implemented in the vehicle pad in a similar manner to its implementation on the grounding pad, either alternatively or additionally. In certain applications, both the grounding pad and the vehicle pad may include separate tunable impedance circuits.

[0083] Figure 5A shows an example of a wireless charging system 500A having an LCC-LCC circuit architecture. As shown, the wireless charging system 500A includes a resonant tank containing a tunable impedance circuit 600 in series with an inductor Lf1.

[0084] Figure 5B shows an example of a wireless charging system 500B that can be formed based on an LCC-LCC circuit architecture. As shown in Figure 5B, the tunable impedance circuit 600 can be connected in parallel with the inductor Lf1 in the resonant tank.

[0085] Figure 5C shows an example of a wireless charging system 500C having a series-series circuit architecture. As shown, the wireless charging system 500C may include a tunable impedance circuit 600 in series with a capacitor C1 in a resonant tank.

[0086] Figure 5D shows an example of a wireless charging system 500D that can be formed based on a series-series circuit architecture. As shown in Figure 5D, the tunable impedance circuit 600 is in parallel with capacitor C1 in a resonant tank.

[0087] Figure 5E shows an example of a wireless charging system 500E that includes a tunable impedance circuit 600. As shown in Figure 5E, the tunable impedance circuit 600 implements the capacitance of the grounding pad's tank circuit. Such a tunable impedance circuit 600 can be a tunable capacitance circuit. The grounding pad's tank circuit of the wireless charging system 500E does not include any capacitors other than the tunable impedance circuit 600 directly connected to L1.

[0088] The tunable impedance circuit 600 may be implemented in other suitable architectures, but is not limited to, the LCC-series circuit architecture 200B (e.g., as shown in Figure 2B) and the series-LCC circuit architecture 200C (e.g., as shown in Figure 2C). For example, in the LCC-series circuit architecture 200B, the tunable impedance circuit 600 may be implemented in the same manner as shown in Figures 5A and 5B. Furthermore, in the series-LCC circuit architecture 200C, the tunable impedance circuit 600 may be implemented in the same manner as shown in Figures 5C and 5D. Exemplary tunable impedance circuit

[0089] A resonant tank in a wireless charging system may include a tunable impedance circuit. The tunable impedance circuit can be any circuit suitable for adjusting the impedance of the resonant tank to improve the performance of the wireless charging system. An exemplary tunable impedance circuit includes a switched-capacitor circuit with one or more switches that switch in or out one or more capacitors from the effective impedance of the tunable impedance circuit. The switched-capacitor circuit may include any suitable number of switches and any suitable number of capacitors. The switched-capacitor circuit may include any suitable series and / or parallel arrangement of one or more capacitors and one or more switches.

[0090] Figures 6A to 6E show examples of tunable impedance circuits 600A to 600E. Any one of the tunable impedance circuit configurations 600A to 600E can implement one of the tunable impedance circuits 600 in the wireless charging systems 500A to 500E. In some embodiments, a switch control circuit 326 is coupled to the control terminals of each switch included in the tunable impedance circuits 600A to 600E, allowing control of these switches to adjust the effective impedance of the tunable impedance circuit. For illustrative purposes, Figures 6A to 6E show two switching circuits. However, the appropriate principles and advantages of this disclosure can be applied to three or more switching circuits. In addition, any combination of the features of Figures 6A to 6E can be implemented in a tunable impedance circuit.

[0091] Figure 6A shows an example of a tunable impedance circuit 600A. The tunable impedance circuit 600A may include two switching circuits 610-1 and 610-2 connected in series. As shown in Figure 6A, the first switching circuit 610-1 may include a first capacitor 612-1, a second capacitor 612-2, and a switch 614-1, connected in parallel with each other. In addition, the second switching circuit 610-2 may include two capacitors 612-3 and 612-4 and a switch 614-2. The two capacitors 612-3 and 612-4 and the switch 614-2 are connected in parallel. The capacitance values ​​of each of the capacitors 612-1 to 612-4 may be determined based on the specific application, and this disclosure does not limit these values. For example, but not limited to, the capacitance values ​​of each of the capacitors 612-1 to 612-4 may be different, or one or more capacitors 612-1 to 612-4 may have the same capacitance value.

[0092] Figure 6B shows another example of the tunable impedance circuit 600A. As shown in Figure 6B, the tunable impedance circuit 600B can include the tunable impedance circuit 600A connected in series with capacitor circuits 620-1 and 620-2. In some embodiments, the tunable impedance circuit 600A and the two capacitor circuits 620-1 and 620-2 are connected in series with each other. Each of the capacitor circuits 620-1 and 620-2 can include two capacitors connected in parallel with each other. Capacitors 622-1 and 622-2 are connected in parallel within capacitor circuit 620-1. Capacitors 622-3 and 622-4 are connected in parallel within capacitor circuit 620-2. Figure 6B shows that the tunable impedance circuit can include a switched capacitor circuit and a fixed capacitor.

[0093] Figure 6C shows an example of a tunable impedance circuit 600C. The tunable impedance circuit 600C includes hybrid parallel-series and series-parallel switched capacitance arrays. The tunable impedance circuit 600C includes a fixed capacitance circuit 630-1, a switched capacitance circuit 630-2, and a tunable impedance circuit 600B. As shown in Figure 6C, the fixed capacitance circuit 630-1 and the switched capacitance circuit 630-2 are connected in parallel.

[0094] The fixed capacitance circuit 630-1 may include a parallel combination of series capacitors. For example, capacitors 632-1 and 632-2 are in series with respect to the series combination of capacitors 632-3 and 632-4. In some embodiments, the fixed capacitance circuit 630-1 may include four capacitors 632-1 to 632-4, where each pair of capacitors is connected in series, and two pairs of series capacitors are connected in parallel with respect to each other. For example, the first pair of capacitors 632-1 and 632-2 are connected in series, and the second pair of capacitors 632-3 and 632-4 are connected in series. Then, the first pair of capacitors 632-1 and 632-2 and the second pair of capacitors 632-3 and 632-4 are connected in parallel, and this parallel connection forms the fixed capacitance circuit 630-1.

[0095] The switched-capacitor circuit 630-2 may include multiple series circuits, each containing a capacitor in series with a switch, where the series circuits are in parallel with one another. For example, a first series circuit includes switch 634-1 in series with capacitors 632-5 and 632-6, and a second series circuit includes switch 634-2 in series with capacitors 632-7 and 632-8. The first series circuit is in parallel with the second series circuit in the switched-capacitor circuit 630-2. As shown in Figure 6C, the switched-capacitor circuit 630-2 may include four capacitors 632-5 to 632-8 and two switches 634-1 to 634-2. As shown, a first group of switches 634-1, capacitors 632-5 and 632-6 may be connected in series, and a second group of switches 634-2, capacitors 632-7 and 632-8 may be connected in series. The first group and the second group may be connected in parallel.

[0096] Figure 6D shows an example of a tunable impedance circuit 600D. The tunable impedance circuit 600D may include a switch 644 connected (in series) to the tunable impedance circuit 600A. The tunable impedance circuit 600A includes capacitors 612-1 to 612-4 and switches 614-1 and 614-2. As shown, the terminals of switch 644 are coupled at node 647 to the first terminals of capacitors 612-1 and 612-2 and to switch 614-1. Switch 644 allows the tunable impedance circuit 600A to be selectively electrically connected or disconnected from the node.

[0097] Figure 6E shows another example of the tunable impedance circuit 600E. As shown in Figure 6E, the tunable impedance circuit 600E may include four capacitors 652-1 to 652-4 and switches 654-1 to 654-3. In some embodiments, the first switch 654-1, the first capacitor 652-1, and the second capacitor 652-2 can be connected in series to form the first switching group 650-1. The second switch 654-2, the third capacitor 652-3, and the fourth capacitor 652-4 can be connected in series to form the second switching group 650-2. The first switching group 650-1, the second switching group 650-2, and the third switch 654-3 may be connected in parallel with each other.

[0098] In some other embodiments, a varactor capacitor may be implemented instead of a switched-capacitor circuit including a capacitor and a switch. In these embodiments, the switch control circuit 326 can adjust the capacitance of the varactor capacitor by applying a bias voltage to the varactor capacitor. Furthermore, in some other embodiments, a tunable impedance circuit can adjust the inductance or a combination of inductance and capacitance.

[0099] In some embodiments, various architectures of the tunable impedance circuit may be constructed by combining two or more tunable impedance circuits 600A to 600E. For example, tunable impedance circuits 600D and 600E may be connected in series. As another example, tunable impedance circuits 600A and 600C may be connected in series. These examples are provided for illustrative purposes only, and this disclosure is not limited to these examples.

[0100] The foregoing disclosure is not intended to limit the disclosure to the very form or specific field of use disclosed. Therefore, it is intended that various alternative embodiments and / or variations of the disclosure, whether expressly described or implied herein, are possible in light of the disclosure. Having described embodiments of the disclosure in this manner, those skilled in the art will recognize that modifications can be made in form and detail without departing from the scope of the disclosure. Accordingly, the disclosure is limited only by the claims.

[0101] It should be understood that not all objectives or benefits are necessarily achieved according to any particular embodiment described herein. Therefore, for example, those skilled in the art will recognize that some embodiments may operate in a manner that achieves or optimizes one benefit or group of benefits taught herein, without necessarily achieving other objectives or benefits that may be taught or suggested herein.

[0102] All processes described herein can be embodied in software code modules executed by a computing system including a computer or processor, thereby enabling complete automation. The code modules can be stored in any type of non-temporary computer-readable medium or other computer storage device. Some or all of the methods can be embodied in dedicated computer hardware.

[0103] Many variations beyond those described herein will become apparent from this disclosure. For example, depending on the embodiment, some of the operations, events, or functions of any of the algorithms described herein may be executed in a different order, and may be added, merged, or completely excluded (for example, not all described operations or events are necessary for the practice of the algorithm). Furthermore, in some embodiments, operations or events may be executed in parallel, not sequentially, for example, through multithreading, interrupt handling, or through multiple processors or processor cores, or on other parallel architectures. In addition, different tasks or processes may be executed by different machines and / or computing systems that can work together.

[0104] The various exemplary logic blocks and modules described in relation to the embodiments disclosed herein may be implemented or executed by machines such as processing units or processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. The processor may be a microprocessor, but in alternative examples, the processor may be a controller, microcontroller, or state machine, or a combination thereof. The processor may include electrical circuits that process computer-executable instructions. In some embodiments, the processor includes an FPGA or other programmable device that performs logical operations without processing computer-executable instructions. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, a microprocessor combined with a DSP core, or any other such configuration. While this specification primarily describes digital technologies, the processor may also include primarily analog components. Computing environments can include, but are not limited to, any type of computer system based on a microprocessor, mainframe computer, digital signal processor, portable computing device, device controller, or in-device computing engine.

[0105] Elements of methods, processes, routines, or algorithms described in relation to embodiments disclosed herein may be embodied directly in hardware, software modules executed by a processor device, or a combination of the two. Software modules may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or any other form of non-temporary computer-readable storage medium. Exemplary storage media may be coupled to a processor device so that the processor device can read information from and write information to the storage media. Alternatively, the storage media may be integrated into the processor device. The processor device and storage media may reside within an ASIC. The ASIC may reside within a user terminal. Alternatively, the processor device and storage media may exist as separate components within a user terminal.

[0106] The processes described herein or shown in the figures of this disclosure may be initiated on demand when started by a user or system administrator in response to an event such as a predetermined or dynamically determined schedule, or in response to any other event. Once such a process is initiated, a set of executable program instructions stored in one or more non-temporary computer-readable media (e.g., hard drives, flash memory, removable media) may be loaded into the memory (e.g., RAM) of a server or other computing device. The executable instructions may then be executed by the hardware-based computer processor of the computing device. In some embodiments, such a process or part thereof may be implemented in series or in parallel on multiple computing devices and / or multiple processors.

[0107] Unless otherwise specified or understood in the context in which they are used, conditional language such as “can,” “could,” “might,” or “may” is generally used to suggest that some embodiments include certain features, elements, and / or steps, while others do not. Accordingly, such conditional language is not generally intended to imply that features, elements, and / or steps are in some form for an embodiment, nor is it intended to imply that an embodiment necessarily includes logic for determining whether these features, elements, and / or steps should be included in or performed in any particular embodiment, with or without user input or input request.

[0108] Disjunctive phrases such as "at least one of X, Y, or Z" are generally understood, unless otherwise specified, to be used from the context to indicate that an item, term, etc., could be any one of X, Y, or Z, or any combination thereof (e.g., X, Y, and / or Z). Therefore, such disjunctive phrases are generally not intended, nor should they be intended, to imply that some embodiments require the presence of at least one X, at least one Y, or at least one Z, respectively.

[0109] Any process description, element, or block in a flowchart described herein and / or depicted in the accompanying drawings should also be understood to represent a module, segment, or portion of code containing execution instructions for implementing a particular logical function or element in the process. Within the scope of the embodiments described herein, alternative embodiments may be included in which, depending on the function in question, elements or functions may be omitted, executed in an order different from the order illustrated or described, substantially simultaneously or in reverse order, as will be understood by those skilled in the art.

[0110] It should be emphasized that many variations and modifications can be made to the above examples, and that the elements thereof are to be understood to be found in other acceptable embodiments. All such modifications and variations are intended to be incorporated herein within the scope of this disclosure.

[0111] Any process description, element, or block in a flowchart described herein and / or depicted in the accompanying drawings should also be understood to represent a module, segment, or portion of code containing execution instructions for implementing a particular logical function or element in the process. Within the scope of the embodiments described herein, alternative implementations are included in which, as can be understood by those skilled in the art, elements or functions may be omitted, executed in an order different from the order illustrated or described, substantially simultaneously or in reverse order, depending on the function in question.

[0112] Unless otherwise specified, articles such as "a" or "an" should generally be interpreted as including one or more described items. Therefore, phrases such as "devices configured to..." are intended to include one or more enumerated devices. Such enumerated devices may also be collectively configured to perform the stated enumeration. For example, "processors configured to perform enumerations A, B, and C" could include a first processor configured to perform enumeration A, working in conjunction with a second processor configured to perform enumerations B and C.

Claims

1. Switching circuit and A resonant tank having a resonant frequency and being electrically connected to the switching circuit, wherein the resonant tank comprises a coil arranged for wireless power transmission, and the resonant tank comprises a tunable impedance circuit, An impedance control circuit configured to adjust the impedance of the tunable impedance circuit in order to adjust the resonant frequency of the resonant tank, A wireless charging pad equipped with [features].

2. The wireless charging pad according to claim 1, wherein the tunable impedance circuit comprises a switch and a capacitor, and the impedance control circuit is configured to adjust the impedance of the tunable impedance circuit by changing the state of the switch.

3. The wireless charging pad according to claim 2, wherein the switch is in parallel with the capacitor.

4. The wireless charging pad according to claim 2, wherein the switch is in series with the capacitor.

5. The wireless charging pad according to claim 1, wherein the tunable impedance circuit comprises a plurality of series circuits in parallel with each other, and each of the series circuits comprises a switch in series with a capacitor.

6. The wireless charging pad according to claim 1, wherein the tunable impedance circuit comprises a plurality of parallel circuits in series with respect to each other, and each of the parallel circuits comprises a switch in parallel with a capacitor.

7. The wireless charging pad according to claim 1, wherein the wireless charging pad is a grounding pad.

8. The wireless charging pad according to claim 1, wherein the wireless charging pad is a vehicle pad.

9. The wireless charging pad according to claim 1, wherein the switching circuit comprises an H-bridge circuit.

10. The wireless charging pad according to claim 1, wherein the switching circuit comprises a stacked half-bridge circuit.

11. The wireless charging pad according to claim 1, wherein the impedance control circuit is configured to adjust the impedance based on a mismatch between the resonant frequency of the resonant tank and the resonant frequency of a second resonant tank circuit of a second wireless charging pad positioned adjacent to the wireless charging pad for wireless charging.

12. The wireless charging pad according to claim 1, wherein the resonant tank comprises a capacitor, and the tunable impedance circuit, the coil, and the capacitor are electrically connected in series.

13. The wireless charging pad according to claim 1, wherein the resonant tank comprises a capacitor connected in series with the coil, and the tunable impedance circuit and the coil are connected in parallel.

14. The wireless charging pad according to claim 1, wherein the resonant tank has an LCC architecture, and the tunable impedance circuit is connected in series with the inductor of the resonant tank.

15. The wireless charging pad according to claim 1, wherein the resonant tank has an LCC architecture, and the tunable impedance circuit is connected in parallel to the inductor of the resonant tank.

16. The wireless charging pad according to claim 1, wherein the tunable impedance circuit and the coil are connected in series.

17. A method of wireless power transmission, A step of detecting a mismatch in resonant frequencies between a first resonant tank of the grounding pad and a second resonant tank of the vehicle pad, To reduce the mismatch in the resonant frequencies, the step of adjusting the impedance of the tunable impedance circuit based on the detection, After the adjustment, the step is to wirelessly transmit power from the grounding pad to the vehicle pad, Methods that include...

18. The method according to claim 17, wherein the first resonant tank of the grounding pad comprises the tunable impedance circuit.

19. The method according to claim 17, wherein the second resonant tank of the vehicle pad comprises the tunable impedance circuit.

20. The method according to claim 17, wherein the mismatch in resonant frequencies is related to a misalignment between the grounding pad and the vehicle pad.

21. The method according to claim 17, wherein the mismatch in resonant frequencies is related to at least one of the vehicle platform, an object placed between the grounding pad and the vehicle pad, or a manufacturing process.

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