Switching circuits to reduce leakage current in inductive charging

Abstract

To provide methods and wireless charging pads for reducing leakage current in wireless power transfer.SOLUTION: A method of wireless power transfer in a wireless charging system includes the steps of: toggling a switching circuit of a ground pad alternately and sequentially between a first switch configuration (e.g., a high voltage configuration) and a second switch configuration (e.g., a low voltage configuration) of an H bridge switching circuit 202, with an unbalanced duty cycle; and causing wireless power transfer from the ground pad to a vehicle pad of a vehicle using a voltage v1. The voltage across a resonant tank 204 electrically connected to the switching circuit is different from a medium voltage for both the first switch configuration and the second switch configuration. The switching circuit provides the high voltage, the low voltage or the medium voltage across the resonant tank.SELECTED DRAWING: Figure 2A-D

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority to U.S. Provisional Patent Application No. 63 / 647,305, entitled "SWITCHING CIRCUITS TO REDUCE LEAKAGE CURRENT IN INDUCTIVE CHARGING," filed May 14, 2024, the technical disclosure of which is incorporated herein by reference in its entirety for all purposes. This application claims priority to U.S. Provisional Patent Application No. 63 / 705,343, entitled "SWITCHING CIRCUITS TO REDUCE LEAKAGE CURRENT IN INDUCTIVE CHARGING," filed October 9, 2024, the technical disclosure of which is incorporated herein by reference in its entirety for all purposes.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates to systems and methods for wireless charging. More particularly, embodiments of the present disclosure relate to wireless charging systems and mechanisms for charging vehicles using wireless charging circuitry. [Background technology]

[0003] Generally described, inductive charging, commonly referred to as wireless charging, is a type of wireless power transfer. Inductive charging uses electromagnetic induction to generate or supply electricity to a device without necessarily requiring a physical electrical connection. Specifically, various devices may be placed near a charging station or inductive pad without precise alignment or electrical contact, a physical dock, electrical plug, or the like. Such devices may include, but are not limited to, vehicles, manufacturing equipment, home appliances, medical devices, and the like. Summary of the Invention [Problem to be solved by the invention]

[0004] The systems, methods, and devices of the present disclosure each have several innovative embodiments, no single one of which is solely responsible for all of the desirable attributes disclosed herein. Details of one or more implementations of the subject matter described herein are set forth in the accompanying drawings and the description below.

[0005] In some aspects, the technology described herein relates to a method of wireless power transfer, the method including alternately and sequentially toggling a switching circuit of a ground pad between a first switch configuration and a second switch configuration with an unbalanced duty cycle, wherein a voltage across a resonant tank electrically connected to the switching circuit is different from a medium voltage in both the first switch configuration and the second switch configuration, the switching circuit being configured to provide a high voltage, a low voltage, or a medium voltage across the resonant tank, and using the voltage to cause wireless power transfer from the ground pad to a vehicle pad of a vehicle.

[0006] In some aspects, the technology described herein relates to a method, wherein the medium voltage is associated with a third switch configuration in which the switching circuit does not switch during switching.

[0007] In some aspects, the technology described herein relates to a method, wherein the switching circuit is an H-bridge circuit and the intermediate voltage is 0 volts.

[0008] In some aspects, the technology described herein relates to a method, wherein the switching circuit is a stacked half-bridge circuit, and the intermediate voltage is half of a first voltage associated with the first switch configuration.

[0009] In some aspects, the techniques described herein relate to a method, wherein the switching includes being in a first switch configuration for at least 60% of the switching cycle and being in a second switch configuration for the remainder of the switching cycle.

[0010] In some aspects, the techniques described herein relate to a method, wherein the switching includes being in a first switch configuration for at least 70% of the switching cycle and being in a second switch configuration for the remainder of the switching cycle.

[0011] In some aspects, the technology described herein relates to a method, wherein the switching is performed in response to detecting that the voltage of a battery pack of the vehicle meets a threshold.

[0012] In some aspects, the technology described herein relates to a method, wherein the switching is performed in response to detecting that a charge level of a battery pack of the vehicle meets a threshold.

[0013] In some aspects, the technology described herein relates to a method, wherein the voltage across the resonant tank has an opposite polarity in the second switch configuration as compared to the first switch configuration.

[0014] In some aspects, the technology described herein relates to a method, wherein a vehicle includes a battery pack configured to charge based on wireless power transmission, and the voltage range of the battery pack of the vehicle is between 100 volts and 1000 volts.

[0015] In some aspects, the technology described herein relates to a method of operating a vehicle pad in a wireless charging environment, the method including: receiving power wirelessly from a ground pad at a vehicle pad of a vehicle, the vehicle pad including a switching circuit; and alternately and sequentially switching the switching circuit with an unbalanced duty cycle between a first switch configuration associated with a high voltage across a resonant tank and a second switch configuration associated with a low voltage across the resonant tank, the switching circuit configured to provide one of a high voltage, a low voltage, or a medium voltage across the resonant tank, the medium voltage being lower than the high voltage and higher than the low voltage.

[0016] In some aspects, the technology described herein relates to a method, wherein the medium voltage is associated with a third switch configuration in which the switching circuit does not switch during switching.

[0017] In some aspects, the technology described herein relates to a method, wherein the switching circuit is an H-bridge circuit and the intermediate voltage is 0 volts.

[0018] In some aspects, the technology described herein relates to a method in which the switching circuit is a stacked half-bridge circuit, and the medium voltage is half of the high voltage.

[0019] In some aspects, the techniques described herein relate to a method, wherein the switching includes being in a first switch configuration for at least 60% of the switching cycle and being in a second switch configuration for the remainder of the switching cycle.

[0020] In some aspects, the techniques described herein relate to a method, wherein the switching includes being in a first switch configuration for at least 60% of the switching cycle and being in a second switch configuration for the remainder of the switching cycle.

[0021] In some aspects, the technology described herein relates to a method, wherein the switching is performed in response to detecting that the voltage of the battery pack meets a threshold.

[0022] In some aspects, the technology described herein relates to a method, wherein the switching is performed in response to detecting that the charge level of the battery pack meets a threshold.

[0023] In some aspects, the technology described herein relates to a method, wherein the voltage across the resonant tank has an opposite polarity in the second switch configuration as compared to the first switch configuration.

[0024] In some aspects, the technology described herein relates to a method, wherein the voltage range of the battery pack of the vehicle is between 100 volts and 1000 volts.

[0025] In some aspects, the technology described herein relates to a wireless charging pad including: a resonant tank including a coil arranged for wireless power transfer; a switching circuit electrically connected to the resonant tank, the switching circuit configurable in at least a first switch configuration associated with a high voltage across the resonant tank, a second switch configuration associated with a low voltage across the resonant tank, and a third switch configuration associated with a medium voltage across the resonant tank, the medium voltage being higher than the low voltage and lower than the high voltage; and a switch control circuit configured to alternately and sequentially switch the switching circuit between the first switch configuration and the second switch configuration with an unbalanced duty cycle, wherein the wireless charging pad is configured to transfer sufficient wireless power to charge a vehicle battery pack with an operating voltage of at least 350 volts.

[0026] In some aspects, the technology described herein relates to a wireless charging pad, wherein the switching circuit includes an H-bridge circuit and the medium voltage is 0 volts.

[0027] In some aspects, the technology described herein relates to a wireless charging pad, wherein the voltage across the resonant tank has an opposite polarity in the second switch configuration compared to the first switch configuration.

[0028] In some aspects, the technology described herein relates to a wireless charging pad, wherein the switching circuit includes a stacked half-bridge circuit and the medium voltage is half of the high voltage.

[0029] In some aspects, the technology described herein relates to a wireless charging pad where the low voltage is 0 volts.

[0030] In some aspects, the technology described herein relates to a wireless charging pad, wherein switching the switching circuitry includes being in a first switch configuration for at least 60% of the switching cycle and being in a second switch configuration for the remainder of the switching cycle.

[0031] In some aspects, the technology described herein relates to a wireless charging pad, wherein the switching includes being in a first switch configuration for at least 70% of the switching cycle and being in a second switch configuration for the remainder of the switching cycle.

[0032] In some aspects, the technology described herein relates to a wireless charging pad in which the alternating and sequential switching of the switching circuitry is performed in response to detecting that the voltage of the battery pack meets a threshold.

[0033] In some aspects, the technology described herein relates to a wireless charging pad in which the alternating and sequential switching of the switching circuitry is performed in response to detecting that the charge level of the battery pack meets a threshold.

[0034] In some aspects, the technology described herein relates to a wireless charging pad, wherein the wireless charging pad is a vehicle pad for a vehicle.

[0035] In some aspects, the technology described herein relates to a wireless charging pad, wherein the wireless charging pad is a grounding pad.

[0036] In some aspects, the technology described herein relates to a wireless charging pad where the vehicle's battery pack voltage ranges from 100 volts to 1000 volts.

[0037] In some aspects, the technology described herein relates to a wireless charging pad including: a resonant tank including a coil arranged for wireless power transfer; a stacked half-bridge circuit electrically connected to the resonant tank, the stacked half-bridge circuit configurable with at least a first switch configuration associated with a high voltage across the resonant tank, a second switch configuration associated with zero volts across the resonant tank, and a third switch configuration associated with a medium voltage across the resonant tank, the medium voltage being a positive voltage lower than the high voltage; and a switch control circuit configured to alternately and sequentially switch the stacked half-bridge circuit between the first switch configuration and the second switch configuration with an unbalanced duty cycle, wherein the wireless charging pad is configured to transfer sufficient wireless power to charge a vehicle battery pack with an operating voltage of at least 350 volts.

[0038] In some aspects, the technology described herein relates to a wireless charging pad where the medium voltage is half the high voltage.

[0039] In some aspects, the technology described herein relates to a wireless charging pad where the vehicle's battery pack voltage ranges from 100 volts to 1000 volts.

[0040] In some aspects, the technology described herein relates to a wireless charging pad, wherein the wireless charging pad is a vehicle pad for a vehicle.

[0041] In some aspects, the technology described herein relates to a wireless charging pad, wherein the wireless charging pad is a grounding pad. [Brief explanation of the drawings]

[0042] Throughout the drawings, reference numbers are reused to indicate correspondence between referenced elements. The drawings are provided to illustrate examples of the subject matter described herein, but not to limit the scope thereof.

[0043] Embodiments of the present disclosure will now be described with reference to the accompanying drawings, in which like reference numerals refer to like elements.

[0044] [Figure 1A] 1 illustrates an exemplary wireless charging environment in which embodiments of the present disclosure may be implemented.

[0045] [Figure 1B] FIG. 1B is a block diagram illustrating the example wireless charging environment of FIG. 1A, in accordance with some embodiments of the present disclosure.

[0046] [Figure 1C] 1 shows an illustration of a grounding pad that can function as a wireless charging device according to some embodiments of the present disclosure.

[0047] [Figure 2A-D] 1 illustrates an example circuit schematic diagram of a wireless charging system according to some embodiments of the present disclosure.

[0048] [Figure 3] 1 shows an example block diagram of a wireless charging pad according to some embodiments of the present disclosure.

[0049] [Figure 4A] 4 illustrates an example switch configuration of the H-bridge circuit of the wireless charging pad of FIG. 3 in accordance with some embodiments of the present disclosure. [Figure 4B] 4 illustrates an example switch configuration of the H-bridge circuit of the wireless charging pad of FIG. 3 in accordance with some embodiments of the present disclosure. [Figure 4C] 4 illustrates an example switch configuration of the H-bridge circuit of the wireless charging pad of FIG. 3 in accordance with some embodiments of the present disclosure. [Figure 4D] 4 illustrates an example switch configuration of the H-bridge circuit of the wireless charging pad of FIG. 3 in accordance with some embodiments of the present disclosure.

[0050] [Figure 5A]4 illustrates example waveforms of voltage amplitudes associated with operation of the wireless charging pad of FIG. 3 in accordance with some embodiments of the present disclosure. [Figure 5B] 4 illustrates example waveforms of voltage amplitudes associated with operation of the wireless charging pad of FIG. 3 in accordance with some embodiments of the present disclosure.

[0051] [Figure 6] 4 illustrates example voltage and current waveforms associated with operation of the wireless charging pad of FIG. 3 in accordance with some embodiments of the present disclosure. [Figure 7A] 4 illustrates example voltage and current waveforms associated with operation of the wireless charging pad of FIG. 3 in accordance with some embodiments of the present disclosure. [Figure 7B] 4 illustrates example voltage and current waveforms associated with operation of the wireless charging pad of FIG. 3 in accordance with some embodiments of the present disclosure. [Figure 8A] 4 illustrates example voltage and current waveforms associated with operation of the wireless charging pad of FIG. 3 in accordance with some embodiments of the present disclosure. [Figure 8B] 4 illustrates example voltage and current waveforms associated with operation of the wireless charging pad of FIG. 3 in accordance with some embodiments of the present disclosure.

[0052] [Figure 9] 1 illustrates an example circuit schematic diagram of a portion of a wireless charging system, according to some embodiments of the present disclosure.

[0053] [Figure 10] 1 shows an example block diagram of a wireless charging pad according to some embodiments of the present disclosure.

[0054] [Figure 11A] 11 illustrates an example switch configuration of the switching circuitry of the wireless charging pad of FIG. 10 in accordance with some embodiments of the present disclosure. [Figure 11B]11 illustrates an example switch configuration of the switching circuitry of the wireless charging pad of FIG. 10 in accordance with some embodiments of the present disclosure. [Figure 11C] 11 illustrates an example switch configuration of the switching circuitry of the wireless charging pad of FIG. 10 in accordance with some embodiments of the present disclosure. [Figure 11D] 11 illustrates an example switch configuration of the switching circuitry of the wireless charging pad of FIG. 10 in accordance with some embodiments of the present disclosure.

[0055] [Figure 12A] 11 shows example waveforms of voltage amplitudes associated with operation of the wireless charging pad of FIG. 10 in accordance with some embodiments of the present disclosure. [Figure 12B] 11 shows example waveforms of voltage amplitudes associated with operation of the wireless charging pad of FIG. 10 in accordance with some embodiments of the present disclosure.

[0056] [Figure 13] 11 illustrates example voltage and current waveforms associated with operation of the wireless charging pad of FIG. 10 in accordance with some embodiments of the present disclosure. [Figure 14] 11 illustrates example voltage and current waveforms associated with operation of the wireless charging pad of FIG. 10 in accordance with some embodiments of the present disclosure. [Figure 15] 11 illustrates example voltage and current waveforms associated with operation of the wireless charging pad of FIG. 10 in accordance with some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0057] The following detailed description of certain embodiments presents various descriptions of specific embodiments. However, the novel ideas described herein may be embodied in many different ways, for example, as defined and covered by the claims. This description refers to the drawings, in which like reference numbers and / or terminology may indicate identical or functionally similar elements. It will be understood that the elements depicted in the drawings are not necessarily drawn to scale. It will also be understood that certain embodiments may include more elements and / or a subset of the elements depicted in the drawings. Furthermore, some embodiments may incorporate any suitable combination of features from two or more drawings. Headings are provided for convenience only and do not affect the scope or meaning of the claims.

[0058] Generally described, one or more aspects of the present disclosure relate to systems and methods for wirelessly charging a battery pack with improved energy transfer efficiency. Illustratively, aspects of the present disclosure relate to a wireless charging circuit that can reduce power losses resulting from leakage currents associated with a coil (e.g., a ground pad coil and / or a vehicle pad coil) by controlling switches in power electronics. In some embodiments, a switch control circuit may control switches in a switching circuit (e.g., an H-bridge circuit, a stacked half-bridge circuit, etc.) to switch between some switch configurations without switching to other switch configuration(s). Thus, the voltage across a resonant tank interfaced to the switching circuit may be a high voltage or a low voltage, but may not be a medium voltage during such switching.

[0059] In some embodiments, when the switching circuit is an H-bridge circuit, the high voltage may be in the range of 300 to 600 volts, the low voltage may be in the range of −300 to −600 volts, and the medium voltage may be around 0 volts. In other embodiments, when the switching circuit is a stacked half-bridge circuit, the high voltage may be in the range of 700 to 1000 volts, the low voltage may be around 0 volts, and the medium voltage may be in the range of 350 to 500 volts.

[0060] For example, if the switching circuit is an H-bridge circuit, the switch control circuit may control the switches of the H-bridge circuit to switch between switch configurations without shorting out the resonant tank when wirelessly charging a vehicle (e.g., the voltage across the resonant tank may switch between a high voltage (e.g., between 300 volts and 600 volts) and a low voltage (e.g., between −300 volts and −600 volts) rather than remaining at a medium voltage of approximately 0 volts). The resonant tank may be interfaced to the H-bridge circuit. The switch control circuit may control the switches of the H-bridge circuit to repeatedly switch between the two switch configurations for unequal time durations (e.g., remaining in one switch configuration 60% to 80% of the time and remaining in the other switch configuration 40% to 20% of the time) without shorting out the resonant tank. Advantageously, avoiding or reducing the occurrence of shorting out the resonant tank may reduce the common-mode voltage associated with the resonant tank and the H-bridge circuit.

[0061] As another example, if the switching circuit is a stacked half-bridge circuit, the switch control circuit may control the switches of the stacked half-bridge circuit to switch between switch configurations such that the voltage across a resonant tank interfaced to the stacked half-bridge circuit switches between a high voltage (e.g., between 700 and 1000 volts) and a low voltage (e.g., around 0 volts) without remaining at a medium voltage (e.g., between 350 and 500 volts).

[0062] In embodiments disclosed herein, leakage currents associated with wireless charging systems may be reduced as a result of the switch control methods disclosed herein, which may reduce energy consumption, reduce electromagnetic interference, and / or minimize conducted and radiated emissions.

[0063] A wireless charging device can be used to wirelessly charge a vehicle, such as an electric vehicle, having a battery pack. The wireless charging device (e.g., a ground pad or vehicle pad) can wirelessly transmit (e.g., via induction) power received from an external source, such as a grid, a solar cell, or the like, to the electric vehicle. The ground pad can be placed under the vehicle pad of the electric vehicle to charge the electric vehicle. A wireless charging direct current (DC) / DC converter (also called an integrated DC / DC power converter) can include a DC / alternating current (AC) inverter in the ground pad and an AC / DC rectifier in the vehicle pad. Power can be transmitted wirelessly from the ground pad to the vehicle pad.

[0064] During operation of a wireless charging system, leakage current may be generated across a charging coil (e.g., a vehicle pad coil and / or a ground pad coil). For example, the ground pad coil may generate leakage current associated with the ground pad. This leakage current may flow through a parasitic capacitor to a heat sink associated with the ground pad. In some cases, a relatively high leakage current may be generated due to a planar shape, a relatively large surface area, and / or a relatively large parasitic capacitance associated with the charging coil. This may result in significant energy loss and undesirable power transfer efficiency. To adapt to different operating points under various voltages and power levels to reduce coil current, a medium voltage (e.g., 0 volts in the case of an H-bridge switching circuit) may be applied across the resonant tank (e.g., by shorting the resonant tank) for a fraction of the time (e.g., 10%, 20%, 30%, 40%) during wireless charging. However, the medium voltage applied across the resonant tank may increase the common-mode voltage associated with the resonant tank. An increase in common mode voltage can lead to an increase in leakage current, which can contribute to power loss or energy waste.

[0065] To address at least some of the above problems, some embodiments of the present disclosure relate to a wireless charging pad capable of charging a battery pack with reduced leakage current. In some embodiments, while wirelessly charging the battery pack, a switch control circuit may control switches of an H-bridge circuit to switch between particular configurations with imbalance or unequal durations without shorting the resonant tank or causing the voltage across the resonant tank to be at an intermediate voltage around 0 volts for a significant amount of time (e.g., more than 10% of the operating time). In some embodiments, the switch control circuit may control the H-bridge circuit to repeatedly switch between a first switch configuration associated with a high voltage (e.g., v volts, where v is greater than 100) and a second switch configuration associated with a low voltage (e.g., −v volts) without switching to a third switch configuration associated with an intermediate voltage around 0 volts. The H-bridge circuit may be in the first switch configuration between 60% and 80% of the total operating time and in the second switch configuration between 40% and 20% of the total operating time.

[0066] In some embodiments, in the first switch configuration, the voltage across the two tank terminals of the resonant tank coupled to the H-bridge circuit may be v. In the second switch configuration, the voltage across the two tank terminals of the resonant tank coupled to the H-bridge circuit may be −v. Advantageously, common-mode voltages and leakage currents associated with the resonant tank and the H-bridge circuit may be reduced due to repeatedly switching between the first and second switch configurations, compared to a situation in which the resonant tank is shorted for a significant amount of time (e.g., more than 10% of the total operating time).

[0067] In some other embodiments, when the switching circuit is a stacked half-bridge circuit, the switch control circuit may control the switches of the stacked half-bridge circuit to switch between a first switch configuration associated with a high voltage and a second switch configuration associated with a low voltage. The switch control circuit may switch the switching circuit between the first switch configuration and the second configuration without setting the switching circuit to a third switch configuration associated with a medium voltage. In this manner, the voltage across a resonant tank interfaced with the stacked half-bridge circuit may be a high voltage (e.g., V, where V is between 700 volts and 1000 volts) when the stacked half-bridge circuit is in the first switch configuration, or a low voltage (e.g., 0 volts) when the stacked half-bridge circuit is in the second switch configuration. However, the voltage across the resonant tank may not be a medium voltage (e.g., 0.5 V), which is half or 50% of the high voltage, during such switching. Advantageously, leakage current associated with the wireless charging system may be reduced. Such switching operations may also reduce energy consumption, reduce electromagnetic interference, and / or minimize conducted and radiated emissions. Furthermore, controlling the stacked half-bridge circuit to switch between the first switch configuration and the second switch configuration without switching to a third switch configuration may extend the voltage range for charging the vehicle's battery pack (e.g., allow the battery pack to be charged at a higher voltage).

[0068] While various aspects are described according to example embodiments and feature combinations, those skilled in the art will understand that the examples and feature combinations are exemplary in nature and should not be construed as necessarily limiting. More specifically, aspects of the present application may be applicable to various types of vehicle charging mechanisms, power sources, interfaces, etc. Furthermore, while schematic diagrams of particular H-bridge circuits for charging batteries and / or battery packs under different voltage levels are described, such example H-bridge circuit schematic diagrams should not be construed as necessarily limiting. Accordingly, those skilled in the art will understand that aspects of the present application are not necessarily limited in application to any particular type of vehicle, vehicle charging infrastructure, communications, or example interactions between a vehicle, an owner / user, and a wireless battery charging system.

[0069] Wireless Charging Overview Generally described, inductive charging, commonly referred to as wireless charging, is a type of wireless power transfer. Inductive charging uses electromagnetic induction to generate or supply electricity to a device without the need for a physical electrical connection. Specifically, various devices can be placed near a charging station or inductive pad without precise alignment or electrical contact, or the need for a physical dock, electrical plug, or the like. Such devices include, but are not limited to, vehicles, manufacturing equipment, consumer electronics, medical devices, and the like.

[0070] According to aspects of the present application, an inductive charging system is configured to transfer energy through inductive coupling between components. An exemplary charging system includes a transmitting component that may be configured as a charging station or charging pad. A charging pad for wirelessly transferring power to a vehicle may be referred to as a grounding pad. An alternating current (AC) current from a power source (e.g., an input current) passes through an induction coil within the charging station or charging pad. Based on the input current, charge moving through the induction coil (e.g., a grounding pad coil) generates (or induces) a magnetic field. Illustratively, the strength of the magnetic field may vary at least in part due to changes or fluctuations in the amplitude of the input current. The changing magnetic field generates AC current in an induction coil on a receiving device (e.g., a vehicle pad coil). The induced AC current within the receiving device may then pass through a rectifier, which converts the induced AC current to DC current. Finally, the receiving vehicle may include additional charging components and / or systems that utilize the converted DC current to charge a battery system, provide operating power, or a combination thereof.

[0071] If an exemplary inductive charging system uses resonant inductive coupling components / techniques, a longer distance between the ground pad and the vehicle pad coil can be achieved. More specifically, in some embodiments, a capacitor can be connected to each inductive coil to create two LC circuits with specific resonant frequencies. The frequency of the alternating current is matched to the resonant frequencies. In addition, the matched frequencies can 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, can be utilized for energy transfer efficiency purposes.

[0072] FIG. 1A is an illustrative diagram of an environment 100 for implementing an inductive-based wireless charging system in accordance with various aspects of the present application. The environment 100 may illustratively correspond to a commercial implementation, such as a parking lot, parking space, or charging booth. The environment 100 may also correspond to a private or other non-commercial implementation, such as a private home. As an illustrative 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 according to an inductive charging methodology. As also shown in FIG. 1A , the grounding pad 102, which may also be referred to as a transmitting component, may correspond to a stand-alone component that may be operable to be mounted or positioned on a floor 104 or other flat surface. In some other embodiments, the grounding pad 102 may be integrated into or combined with other devices or components.

[0073] The grounding pad 102 may be connected to one or more power sources, such as 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 provide input AC current as described herein. The grounding pad 102 may be connected to the power source via a direct electrical connection 106, such as through a junction box 108 positioned on a wall surface 118.

[0074] 1A , in one embodiment, the grounding pad 102 corresponds to a form factor that enables positioning of the floor 104 for wireless charging with 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 top surface of the grounding pad 102. Illustratively, 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 top surface of the grounding pad 102 and the underside of the vehicle meets certain criteria, such as a minimum distance between the grounding pad coil and the vehicle pad coil, a maximum distance between the grounding pad coil and the vehicle pad coil, etc. In some embodiments, the vehicle pad and / or the grounding pad 102 (or a combination thereof) may be configured with additional components to adjust (e.g., statically and / or dynamically adjust) such distance or otherwise change the relative orientation between the grounding pad 102 and the vehicle.

[0075] In some embodiments, the grounding pad 102 can be configured to charge a vehicle's battery pack, which can have a nominal voltage greater than 200 volts (e.g., a nominal voltage of approximately 350 volts or 355 volts) and a maximum voltage of 400 volts. In some embodiments, the grounding pad 102 can be configured to provide 800 volts of DC power. In some embodiments, the grounding pad 102 can provide a voltage ranging from approximately 100 volts to 1000 volts. The grounding pad 102 can wirelessly transmit sufficient power to charge a battery pack at such voltages.

[0076] 1B shows a block diagram of an environment 100 including a wireless charging device 111 (e.g., a grounding pad 102) that communicates wirelessly with a vehicle 112, such as via an induction-based magnetic field. The wireless charging device 111 is further connected to one or more energy sources 110. While the wireless charging device 111 is shown with a direct connection to the energy source 110, at least a portion of the input AC current may be supplied via wireless transmission methods. Additionally, in embodiments having multiple power sources, the environment may also include various switching components to allow energy selection from individual energy sources 110 or combinations of energy sources 110.

[0077] 1C shows a block diagram of a ground pad 102 that can function as the wireless charging device 111 (shown in FIG. 1B). The ground pad 102 can include at least a ground pad coil 122 for generating a magnetic field from an input current provided by the energy source 110. As shown in FIG. 1C, the input current can be provided by a direct electrical connection 106.

[0078] In some embodiments, the grounding pad 102 may also include various sensor components 124A, 124B, 124C, 124D related to the charging process. By way of example, the sensor components 124A, 124B, 124C, 124D may be configured for various functions such as vehicle 112 detection, object detection, vehicle distance measurement, environmental sensors (e.g., temperature sensors, moisture sensors), pressure sensors, etc. In one embodiment, the sensor components 124A, 124B, 124C, 124D may include radar sensors. The sensor components 124A, 124B, 124C, 124D may include logic and processing components related to the charging process, including operational measurements, operational control, safety measurements, communication components, and the like.

[0079] Wireless charging system with an H-bridge circuit 2A-2D show schematic circuit diagrams of exemplary wireless charging systems 200A-200D. As shown in FIGS. 2A-2D, each of wireless charging systems 200A-200D may include a ground pad (e.g., ground pad 102) and a vehicle pad attached to or otherwise integrated with a vehicle. For example, the ground pad of wireless charging system 200A may include capacitor 212A, H-bridge circuit 202A, and resonant tank 204A, as shown in FIG. 2A. The vehicle pad of wireless charging system 200A may include capacitor 214A, H-bridge circuit 208A, and resonant tank 206A, as shown in FIG. 2A. In some embodiments, power may be transferred from a power source (not shown in FIG. 2A) through H-bridge circuit 202A, resonant tank 204A, resonant tank 206A, and H-bridge circuit 208A to a vehicle battery pack (not shown in FIG. 2A). The power transfer may include wireless power transfer from the ground pad coil L1 to the vehicle pad coil L2. Any of the wireless charging systems 200A-200D may be implemented according to any suitable principles and advantages disclosed herein.

[0080] 2A shows a circuit diagram of a wireless charging system 200A. As shown in FIG. 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, an inductor L f1 and capacitor C f1 and C1 are coupled between the H-bridge circuit 202A in the ground pad and the ground pad coil L1, and inductor L f2 and capacitor C f2 and C2 are coupled between the H-bridge circuit 208A in the vehicle pad and the vehicle pad coil L2.

[0081] 2B shows a circuit diagram of a wireless charging system 200B. As shown in FIG. 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, an inductor L f1 and capacitor C f1 and C1 are coupled between the H-bridge circuit 202A in the ground pad and the ground pad coil L1, and series capacitor C2 is coupled between the H-bridge circuit 208A in the vehicle pad and the vehicle pad coil L2.

[0082] FIG. 2C illustrates a circuit schematic diagram of a wireless charging system 200C. As shown in FIG. 2C, the wireless charging system 200C corresponds to a series-LCC circuit architecture. As shown, 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, a series capacitor C1 is coupled between the H-bridge circuit 202A in the ground pad and the ground pad coil L1, and an inductor L f2 and capacitor C f2 and C2 are coupled between the H-bridge circuit 208A in the vehicle pad and the vehicle pad coil L2.

[0083] 2D shows a circuit schematic diagram of wireless charging system 200D. As shown in FIG. 2D, wireless charging system 200D corresponds to a series-series circuit architecture. As shown, wireless charging system 200D includes capacitor 212D, H-bridge circuit 202D, resonant tank 204D, resonant tank 206D, H-bridge circuit 208D, and capacitor 214D. In the series-series circuit architecture, series capacitor C1 is coupled between H-bridge circuit 202A in the ground pad and ground pad coil L1, and series capacitor C2 is coupled between H-bridge circuit 208A in the vehicle pad and vehicle pad coil L2.

[0084] Exemplary Wireless Charging Pad 3 illustrates an exemplary wireless charging pad 300 according to some embodiments of the present disclosure. The wireless charging pad 300 includes an H-bridge circuit 322, a resonant tank 324, and a switch control circuit 326. The wireless charging pad 300 can charge a vehicle's battery pack over a relatively wide voltage range through switching the switches in the H-bridge circuit 322. Any suitable principles and advantages of the wireless charging pad 300 may be implemented in an environment according to any suitable principles and advantages of FIGS. 1A-1C.

[0085] Wireless charging pad 300 may be mounted on any ground pad or vehicle pad of wireless charging systems 200A-200D to reduce leakage current associated with the ground pad coil and / or vehicle pad coil. For example, wireless charging pad 300 may be a vehicle pad and / or ground pad of any of wireless charging systems 200A-200D. In some embodiments, H-bridge circuit 322 may correspond to any of H-bridge circuit 202A, H-bridge circuit 208A, H-bridge circuit 202B, H-bridge circuit 208B, H-bridge circuit 202C, H-bridge circuit 208C, H-bridge circuit 202D, and H-bridge circuit 208D. Resonant tank 324 may correspond to any of resonant tank 204A, resonant tank 206A, resonant tank 204B, resonant tank 206B, resonant tank 204C, resonant tank 206C, resonant tank 204D, and resonant tank 206D.

[0086] In some embodiments, rather than switching the switches of the H-bridge circuit 322 to short-circuit the resonant tank 324 for a significant amount of time (e.g., more than 10% of the total operating time), the switch control circuit 326 may control the switches of the H-bridge circuit 322 to prevent the H-bridge circuit 322 from shorting out the resonant tank 324 while the H-bridge circuit 322 wirelessly charges the vehicle. Advantageously, the common-mode voltage and leakage current associated with the resonant tank 324 and the H-bridge circuit 322 may be reduced compared to a situation in which the resonant tank 324 is short-circuited for a significant amount of time (e.g., 10% of the total operating time).

[0087] The switch control circuit 326 can provide control signals to control the states of the switches of the H-bridge circuit 322 (e.g., switches 322-1 to 322-4 in FIGS. 4A to 4D). The switch control circuit 326 can be implemented by any suitable circuit configuration to control the states of the switches of the H-bridge circuit 322. If the switches of the H-bridge circuit 322 have gates (e.g., the switches are FETs or IGBTs), the switch control circuit 326 can provide control signals to the gates of the H-bridge. In such a case, the switch control circuit 326 can be referred to as a gate drive circuit.

[0088] Exemplary H-Bridge Switch Configuration 4A-4D illustrate example switch configurations of an H-bridge circuit 322 that may be controlled by a switch control circuit 326 according to some embodiments of the present disclosure. FIG. 4A illustrates that the H-bridge circuit 322 may be configured by the switch control circuit 326 into a switch configuration 410, which may be referred to as a positive configuration. The positive configuration of FIG. 4A is a high-voltage configuration. FIG. 4B illustrates that the H-bridge circuit 322 may be configured by the switch control circuit 326 into a switch configuration 420, which may be referred to as a negative configuration. The negative configuration of FIG. 4B is a low-voltage configuration. FIG. 4C illustrates that the H-bridge circuit 322 may be configured by the switch control circuit 326 into a switch configuration 430, which may be referred to as a zero-1 configuration. FIG. 4D illustrates that the H-bridge circuit 322 may be configured by the switch control circuit 326 into a switch configuration 440, which may be referred to as a zero-2 configuration. The zero-1 and zero-2 configurations of FIGS. 4C and 4D, respectively, are medium-voltage configurations.

[0089] The H-bridge circuit 322 includes four switches, namely, switch 322-1, switch 322-2, switch 322-3, and switch 322-4. These switches may be any suitable power electronics switches, such as n-type field-effect transistors, arranged to switch sufficient voltage 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 switches of the H-bridge circuit 322 may be arranged to pass several hundred volts. The H-bridge circuit 322 includes a first half-bridge and a second half-bridge. The first half-bridge includes switches 322-1 and 322-2. The second half-bridge includes switches 322-3 and 322-4.

[0090] As shown in Figure 4A, in switch configuration 410, 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, 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, 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, switch 322-1 is closed, switch 322-2 is open, switch 322-3 is open, and switch 322-4 is closed.

[0091] In some embodiments, rather than switching to switch configuration 430 and / or switch configuration 440, switch control circuit 326 may control switches 322-1, 322-2, 322-3, and 322-4 to switch between switch configuration 410 and switch configuration 420 at unequal time durations. Thus, resonant tank 324 is not shorted during wireless charging of a vehicle. Compared to a situation in which H-bridge circuit 322 switches to switch configuration 430 and / or switch configuration 440, common-mode voltages and leakage currents associated with resonant tank 324 and H-bridge circuit 322 may be reduced, as shown in FIGS. 6 , 7A, 7B, 8A, and 8B.

[0092] Example Voltage Amplitude Waveform The H-bridge circuit can repeatedly switch between various (e.g., two or more) switch configurations. Examples of switching between various switch configurations are discussed with reference to FIGS. 5A and 5B. Switching between such various switch configurations can be performed by an H-bridge circuit on the ground pad, an H-bridge circuit on the vehicle pad, or an H-bridge circuit on both the ground pad and the vehicle pad. In some cases, switching between such various switch configurations can be performed by an H-bridge circuit on the ground pad, where the vehicle pad can have a different switching circuit topology. In other cases, switching between such various switch configurations can be performed by an H-bridge circuit on the vehicle pad, where the ground pad can have a different switching circuit topology.

[0093] In some examples, the switch control circuit 326 can cause the H-bridge to alternately and sequentially switch between two switch configurations associated with non-zero voltages in response to the wireless charging pad detecting one or more conditions. The one or more conditions can include, but are not limited to, a battery voltage meeting a threshold, such as above a high voltage threshold or below a low voltage threshold, a battery charge level meeting a threshold, such as above a high charge threshold or below a low charge threshold, a voltage supplied to the ground pad meeting a threshold, such as above a high voltage threshold or below a low voltage threshold, a lighter load interfaced to the H-bridge circuit, a lower or higher voltage range associated with the battery pack being charged, or the like. Alternatively or additionally, the one or more conditions can include a battery voltage within a particular range (e.g., due to a battery pack having a different voltage level or a different level of battery pack state of charge), a voltage supplied to the ground pad within a particular range, a specified power level within a particular range, parking inaccuracies within a particular range, or measured inductance variations within a particular range. Switching switching configurations according to any suitable principles and advantages disclosed herein can be used as a default mode or the only switching mode in some applications. Switching configurations according to any suitable principles and advantages disclosed herein may be used for wireless power transfer associated with charging one or more particular battery chemistries in various instances.

[0094] 5A shows example waveforms 550A and 560A associated with the operation of the wireless charging pad 300 of FIG. 3 in accordance with some embodiments of the present disclosure. More specifically, waveforms 550A and 560A show the voltage amplitude and voltage across the resonant tank 324 as the H-bridge circuit 322 switches between various switch configurations. The voltage across the resonant tank 324 may correspond to voltage v1 associated with any of resonant tank 204A, resonant tank 204B, resonant tank 204C, or resonant tank 204D (shown in FIGS. 2A-2D ), or voltage v2 associated with any of resonant tank 206A, resonant tank 206B, resonant tank 206C, or resonant tank 206D (shown in FIGS. 2A-2D ).

[0095] Waveform 550A is associated with H-bridge circuit 322 switching between switch configuration 410, switch configuration 430 or 440, and switch configuration 420. In waveform 550A, H-bridge circuit 322 is in switch configuration 430 or 440, then in switch configuration 410, then in switch configuration 430 or 440, and then in switch configuration 420, in one switching cycle. In a switching cycle, H-bridge circuit 322 may be in a switch configuration in waveform 550A for one-quarter or another suitable duration (e.g., more than or less than one-quarter) of the switching cycle before switching to another switch configuration. In some embodiments, in a switching cycle, H-bridge circuit 322 is in switch configuration 430, then in switch configuration 410, then in switch configuration 430, and then in switch configuration 420. In some embodiments, during a switching cycle, H-bridge circuit 322 is in switch configuration 440, then in switch configuration 410, then in switch configuration 440, and then in switch configuration 420. In some embodiments, during a switching cycle, H-bridge circuit 322 is in switch configuration 430, then in switch configuration 410, then in switch configuration 440, and then in switch configuration 420. In some embodiments, during a switching cycle, H-bridge circuit 322 is in switch configuration 440, then in switch configuration 410, then in switch configuration 430, and then in switch configuration 420.

[0096] Waveform 550A shows two switching cycles. When the H-bridge circuit 322 is in switch configuration 410, the voltage across the resonant tank 324 may be around v. When the H-bridge circuit 322 is in switch configuration 430 or 440, the voltage across the resonant tank 324 may be around 0 V, indicating that the resonant tank 324 may be shorted. When the H-bridge circuit 322 is in switch configuration 420, the voltage across the resonant tank 324 may be around -v. In some embodiments, v may be in the range of 200 V to 400 V.

[0097] Waveform 560A is associated with H-bridge circuit 322 repeatedly switching between switch configurations 410 and 420 without switching to switch configuration 430 or switch configuration 440. Waveform 560A corresponds to H-bridge circuit 322 alternating and sequentially between switch configurations 410 and 420. When H-bridge circuit 322 is in switch configuration 410, the voltage across resonant tank 324 may be approximately v. When H-bridge circuit 322 is in switch configuration 420, the voltage across resonant tank 324 may be approximately -v. Waveform 560A shows that during a switching cycle, H-bridge circuit 322 is in switch configuration 410 approximately 25% of the time and in switch configuration 420 approximately 75% of the time. Thus, waveform 560A has an unbalanced duty cycle. In some other applications, H-bridge circuit 322 may have any other suitable unbalanced duty cycles for the switching cycles, such as, but not limited to, (a) 70% for switch configuration 420 and 30% for switch configuration 410, or (b) 80% for switch configuration 420 and 20% for switch configuration 410.

[0098] The modulation scheme corresponding to waveform 560A may achieve the same or substantially the same short-circuit functionality as the modulation scheme corresponding to waveform 550A. Furthermore, the relatively high leakage current penalty associated with switch configuration 430 of waveform 550A is avoided in waveform 560A. Furthermore, less switching occurs in each switching cycle to generate waveform 560A compared to generating waveform 550A. Thus, switching losses and dead-time losses are reduced in the switching cycles associated with waveform 560A compared to the switching cycles associated with waveform 550A.

[0099] FIG. 5B shows example waveforms 550A and 560B associated with operation of the wireless charging pad 300 according to some embodiments of the present disclosure.

[0100] As described above, waveform 550A is associated with H-bridge circuit 322 switching between switch configuration 410, switch configuration 430, and switch configuration 420 in a sequence that repeats with each switching cycle. For each switching cycle, H-bridge circuit 322 is in a switch configuration that applies a voltage of approximately 0 volts across resonant tank 324 for half of the switching cycle. When H-bridge circuit 322 is in switch configuration 410, the voltage across resonant tank 324 may be approximately v. When H-bridge circuit 322 is in switch configuration 430, the voltage across resonant tank 324 may be approximately 0 V. When H-bridge circuit 322 is in switch configuration 420, the voltage across resonant tank 324 may be approximately -v.

[0101] Waveform 560B is associated with H-bridge circuit 322 repeatedly switching between switch configuration 410 and switch configuration 420 without switching to switch configuration 430 or switch configuration 440. Waveform 560B corresponds to H-bridge circuit 322 alternating and sequentially between switch configuration 410 and switch configuration 420. When H-bridge circuit 322 is in switch configuration 410, the voltage across resonant tank 324 may be approximately v. When H-bridge circuit 322 is in switch configuration 420, the voltage across resonant tank 324 may be approximately -v. Waveform 560B is similar to waveform 560A, except waveform 560B is in switch configuration 410 more than switch configuration 420. For example, FIG. 5B corresponds to H-bridge circuit 322 being in switch configuration 410 approximately 75% of the time and in switch configuration 420 approximately 25% of the time. In some other applications, H-bridge circuit 322 may have any other suitable unbalanced duty cycles for the switching cycles, such as, but not limited to, (a) 70% for switch configuration 410 and 30% for switch configuration 420, or (b) 80% for switch configuration 410 and 20% for switch configuration 420.

[0102] In some embodiments, switch control circuit 326 may control H-bridge circuit 322 to alternately switch between switch configuration 410 and switch configuration 420 with an unbalanced duty cycle without switching to switch configuration 430 and / or switch configuration 440 to avoid shorting out resonant tank 324. An unbalanced duty cycle is a non-50 / 50 duty cycle. With an unbalanced duty cycle, H-bridge circuit 322 can be in one of two switch configurations for at least 60% of the switching cycle and in the other of the two switch configurations for the remainder of the switching cycle. In some such applications, H-bridge circuit 322 can be in one of two switch configurations for at least 70% or 80% of the switching cycle and in the other of the two switch configurations for the remainder of the switching cycle. Compared to a situation where the resonant tank 324 is shorted, the common-mode voltage and leakage current associated with the resonant tank and H-bridge circuit can be reduced due to alternating and sequential switching between the switch configuration 410 and the switch configuration 420 with unequal duty cycles.

[0103] Exemplary Voltage and Current Waveforms 6, 7A, 7B, 8A, and 8B show example waveforms associated with the operation of wireless charging system 200D of FIG. 2D in accordance with some embodiments of the present disclosure. Any suitable principles and advantages disclosed with reference to any of FIGS. 7A, 7B, 8A, and 8B may be applied to any of H-bridge circuit 202A, H-bridge circuit 208A, H-bridge circuit 202B, H-bridge circuit 208B, H-bridge circuit 202C, and / or H-bridge circuit 208C. For example, switch control circuit 326 may control any of the H-bridge circuits disclosed herein according to any suitable principles and advantages disclosed with reference to waveform 560A and / or waveform 560B.

[0104] 6 shows voltage and current waveforms associated with wireless charging system 200D when both H-bridge circuit 202D and H-bridge circuit 208D switch according to waveform 550A. Waveform 602 shows the common-mode voltage of the ground pad (e.g., the voltage between the midpoint of capacitor 212D and the midpoint of ground pad coil L1). Waveform 604 shows the common-mode voltage of the vehicle pad (e.g., the voltage between the midpoint of capacitor 214D and the midpoint of vehicle pad coil L2). Waveform 612 shows the voltage across resonant tank 204D (e.g., v1 shown in FIG. 2D). Waveform 614 shows the voltage across resonant tank 206D (e.g., v2 shown in FIG. 2D). Waveform 622 shows the current through resonant tank 204D. Waveform 624 shows the current through resonant tank 206D.

[0105] Waveform 602 shows that the common mode voltage of the ground pad is non-zero and varies within a relatively wide range (e.g., varying between 250V and -250V). This can cause significant leakage current on the ground pad of Figure 2D. Waveform 604 shows that the common mode voltage of the vehicle pad is non-zero and varies within a relatively wide range (e.g., varying between 200V and -200V). This can be associated with significant leakage current on the vehicle pad of Figure 2D.

[0106] 7A shows voltage and current waveforms associated with wireless charging system 200D when H-bridge circuit 202D switches according to waveform 560A and H-bridge circuit 208D switches according to waveform 550A. Waveform 702 shows the common-mode voltage of the ground pad (e.g., the voltage between the midpoint of capacitor 212D and the midpoint of ground pad coil L1). Waveform 704 shows the common-mode voltage of the vehicle pad (e.g., the voltage between the midpoint of capacitor 214D and the midpoint of vehicle pad coil L2). Waveform 712 shows the voltage across resonant tank 204D (e.g., v1 shown in FIG. 2D). Waveform 714 shows the voltage across resonant tank 206D (e.g., v2 shown in FIG. 2D). Waveform 722 shows the current through resonant tank 204D. Waveform 724 shows the current through resonant tank 206D.

[0107] Waveform 702 shows that the common mode voltage of the ground pad is around zero (e.g., fluctuating around 0V), which can be associated with a significant reduction in leakage current on the ground pad in Figure 2D. Waveform 704 shows that the common mode voltage of the vehicle pad is non-zero (e.g., fluctuating between 200V and -200V), which can be associated with a significant leakage current on the vehicle pad in Figure 2D.

[0108] 7B shows voltage and current waveforms associated with wireless charging system 200D when both H-bridge circuit 202D and H-bridge circuit 208D switch according to waveform 560A. Waveform 752 shows the common-mode voltage of the ground pad (e.g., the voltage between the midpoint of capacitor 212D and the midpoint of ground pad coil L1). Waveform 754 shows the common-mode voltage of the vehicle pad (e.g., the voltage between the midpoint of capacitor 214D and the midpoint of vehicle pad coil L2). Waveform 762 shows the voltage across resonant tank 204D (e.g., v1 shown in FIG. 2D). Waveform 764 shows the voltage across resonant tank 206D (e.g., v2 shown in FIG. 2D). Waveform 772 shows the current through resonant tank 204D. Waveform 774 shows the current through resonant tank 206D.

[0109] 7B shows that when both H-bridge circuits 202D and 208D in wireless charging system 200D are switched to correspond to waveform 560A, the magnitude of the common-mode voltage on both the ground pad and the vehicle pad is less than approximately 20 microvolts. Waveform 752 shows that the common-mode voltage on the ground pad is around zero (e.g., fluctuating around 0 V). This is associated with a significant reduction in leakage current on the ground pad in FIG. 2D. Waveform 754 shows that the common-mode voltage on the vehicle pad is around zero (e.g., fluctuating around 0 V). This is associated with a significant reduction in leakage current on the vehicle pad in FIG. 2D.

[0110] Simulations show similar performance associated with waveforms 560A and 560B of wireless charging system 200D.

[0111] 8A shows voltage and current waveforms associated with wireless charging system 200D when H-bridge circuit 202D switches according to waveform 560B and H-bridge circuit 208D switches according to waveform 550A. Waveform 802 shows the common-mode voltage of the ground pad (e.g., the voltage between the midpoint of capacitor 212D and the midpoint of ground pad coil L1). Waveform 804 shows the common-mode voltage of the vehicle pad (e.g., the voltage between the midpoint of capacitor 214D and the midpoint of vehicle pad coil L2). Waveform 812 shows the voltage across resonant tank 204D (e.g., v1 shown in FIG. 2D). Waveform 814 shows the voltage across resonant tank 206D (e.g., v2 shown in FIG. 2D). Waveform 822 shows the current through resonant tank 204D. Waveform 824 shows the current through resonant tank 206D.

[0112] Waveform 802 shows that the common mode voltage of the ground pad is around zero (e.g., fluctuating around 0V), which can be associated with the reduced leakage current on the ground pad in Figure 2D. Waveform 804 shows that the common mode voltage of the vehicle pad is non-zero and varies over a relatively wide range (e.g., fluctuating between 200V and -200V), which can be associated with the significant leakage current on the vehicle pad in Figure 2D.

[0113] 8B shows voltage and current waveforms associated with wireless charging system 200D when both H-bridge circuit 202D and H-bridge circuit 208D switch according to waveform 560B. Waveform 852 shows the common-mode voltage of the ground pad (e.g., the voltage between the midpoint of capacitor 212D and the midpoint of ground pad coil L1). Waveform 854 shows the common-mode voltage of the vehicle pad (e.g., the voltage between the midpoint of capacitor 214D and the midpoint of vehicle pad coil L2). Waveform 862 shows the voltage across resonant tank 204D (e.g., v1 shown in FIG. 2D). Waveform 864 shows the voltage across resonant tank 206D (e.g., v2 shown in FIG. 2D). Waveform 872 shows the current through resonant tank 204D. Waveform 874 shows the current through resonant tank 206D.

[0114] 8B shows that when both H-bridge circuits 202D and 208D in wireless charging system 200D are switched to correspond to waveform 560B, the magnitude of the common-mode voltage on both the ground pad and the vehicle pad is less than approximately 20 microvolts. Waveform 852 shows that the common-mode voltage on the ground pad is near zero (e.g., fluctuating around 0 V). This is associated with a significant reduction in leakage current on the ground pad of FIG. 2D. Waveform 854 shows that the common-mode voltage on the vehicle pad is near zero (e.g., fluctuating around 0 V). This is associated with a significant reduction in leakage current on the ground pad of FIG. 2D.

[0115] Wireless charging system with stacked half-bridge circuit 9 shows an example circuit schematic diagram of a portion of a wireless charging system 900 according to some embodiments of the present disclosure. Portions of the wireless charging system 900 may be inside a vehicle pad and / or ground pad, such as the vehicle pads and / or ground pads shown in FIGS. 2A-2D. In certain wireless charging systems, the vehicle pad may include a stacked half-bridge switching circuit, and the ground pad may include an H-bridge switching circuit.

[0116] 9 , a portion of wireless charging system 900 includes a capacitor 930, a capacitor 940, a stacked half-bridge circuit 950, and a resonant tank 960. Capacitor 930 and capacitor 940 are connected in series in FIG. 9 . Stacked half-bridge circuit 950 includes a switch 952, a switch 954, a switch 956, and a switch 958 connected in series. Resonant tank 960 includes an inductor 962, a capacitor 964, and a capacitor 966 connected in series. The portion of wireless charging system 900 may enable wireless power transfer based on principles similar to those applicable to wireless charging systems 200A, 200B, 200C, and 200D.

[0117] In some embodiments, the stacked half-bridge circuit 950 may be integrated into wireless charging systems 200A, 200B, 200C, and 200D. The stacked half-bridge circuit 950 may replace one or more of the H-bridge circuits of these wireless charging systems. For example, the stacked half-bridge circuit 950 may replace the H-bridge circuit 208A of wireless charging system 200A. As another example, the stacked half-bridge circuit 950 may replace the H-bridge circuit 202B of wireless charging system 200B. As a further example, the stacked half-bridge circuit 950 may replace the H-bridge circuits 202A and 208A in wireless charging system 200A. Compared to the wireless charging systems 200A, 200B, 200C, and 200D shown in FIGS. 2A-2D that utilize H-bridge circuits to facilitate wireless power transfer, some of the wireless charging systems 900 may achieve higher charging voltages by utilizing the stacked half-bridge circuit 950 for wireless power transfer.

[0118] 9, the voltage across resonant tank 960 is designated as v volts. The voltage across stacked half-bridge circuit 950 is designated as Vdc volts. Capacitor 930 and capacitor 940 are connected together at terminal point 970.

[0119] Additional Exemplary Wireless Charging Pads FIG. 10 shows an example block diagram of a wireless charging pad 1000 according to some embodiments of the present disclosure. The wireless charging pad 1000 may function and / or be implemented similarly to the wireless charging pad 300 of FIG. 3 . The wireless charging pad 1000 may be a vehicle pad. The wireless charging pad 1000 may be a ground pad. As shown in FIG. 10 , the wireless charging pad 1000 includes a resonant tank 324, a switching circuit 1022, and a switch control circuit 326. The switching circuit 1022 may be an H-bridge circuit (e.g., H-bridge circuit 322) or a stacked half-bridge circuit (e.g., stacked half-bridge circuit 950). The resonant tank 324 may correspond to any of resonant tank 204A, resonant tank 206A, resonant tank 204B, resonant tank 206B, resonant tank 204C, resonant tank 206C, resonant tank 204D, resonant tank 206D, and resonant tank 960.

[0120] In some embodiments, when the switching circuit 1022 is a stacked half-bridge circuit (e.g., stacked half-bridge circuit 950), the switch control circuit 326 may control the switches of the stacked half-bridge circuit to switch between a first switch configuration associated with a high voltage (e.g., a high-voltage configuration) and a second switch configuration associated with a low voltage (e.g., a low-voltage configuration). During this switching, the switch control circuit 326 may not control the switches of the stacked half-bridge circuit to be in a third switch configuration associated with a medium voltage (e.g., a medium-voltage configuration). Thus, the voltage across the resonant tank 324 interfaced to the stacked half-bridge circuit may be a high voltage (e.g., Vdc volts shown in FIG. 9) when the stacked half-bridge circuit is in the first switch configuration, or a low voltage (e.g., 0 volts) when the stacked half-bridge circuit is in the second switch configuration. However, the voltage across the resonant tank 324 may not be a medium voltage (e.g., 0.5 Vdc volts) that is half or 50% of the high voltage when switching between the first and second switch configurations. Advantageously, leakage currents associated with the wireless charging system may be reduced. Such switching operations may also reduce energy consumption, reduce electromagnetic interference, and / or minimize conducted and radiated emissions. Furthermore, controlling the stacked half-bridge circuit to switch between the first and second switch configurations without switching to a third switch configuration may expand the voltage range for charging the vehicle's battery pack (e.g., allow the battery pack to be charged at a higher voltage).

[0121] In some embodiments, if the switching circuit 1022 is an H-bridge circuit, the switch control circuit 326 may control the switches of the H-bridge as described above with reference to FIGS. 3, 4A-4D, and / or 5A-5B.

[0122] In certain applications, the switch control circuit 326 can detect that the switching circuit 1022 is a stacked half-bridge circuit and, based on this detection, control the switching circuit 1022. In certain applications, the switch control circuit 326 can detect that the switching circuit 1022 is an H-bridge circuit and, based on this detection, control the switching circuit 1022.

[0123] Exemplary Stacked Half-Bridge Circuit Configuration 11A, 11B, 11C, and 11D show example switch configurations of the switching circuit 1022 of the wireless charging pad 1000 of FIG. 10 in accordance with some embodiments of the present disclosure. More specifically, FIGS. 11A-11D show example switch configurations of the switching circuit 1022 when the switching circuit 1022 is a stacked half-bridge circuit (e.g., the stacked half-bridge circuit 950 of FIG. 9). FIG. 11A shows that the switching circuit 1022 can be configured by the switch control circuit 326 into switch configuration 1110, which may be referred to as a high-voltage configuration. FIG. 11B shows that the switching circuit 1022 can be configured by the switch control circuit 326 into switch configuration 1120, which may be referred to as a low-voltage configuration. FIG. 11C shows that the switching circuit 1022 can be configured by the switch control circuit 326 into switch configuration 1130, which may be referred to as a medium-voltage 1 configuration. FIG. 11D shows that switching circuit 1022 can be configured by switch control circuit 326 into switch configuration 1140, which can be referred to as the medium voltage 2 configuration.

[0124] The switching circuit 1022 shown in Figures 11A, 11B, 11C, and 11D includes four switches (e.g., switch 952, switch 954, switch 956, and switch 958). These switches may be suitable for any power electronics, such as n-type field effect transistors, arranged to switch sufficient voltage for wireless charging as disclosed herein. In certain applications, the switching circuit 1022 may include metal oxide semiconductor field effect transistors (MOSFETs). Alternatively, or in addition, the switching circuit 1022 may include insulated gate bipolar transistors (IGBTs). The switches of the switching circuit 1022 may be arranged to pass several hundred volts.

[0125] 11A, in switch configuration 1110, switch 952 is closed, switch 954 is open, switch 958 is closed, and switch 956 is open. In switch configuration 1110, a voltage Vdc is present across the resonant tank including inductor 962 and capacitor 964. As shown in FIG. 11B, in switch configuration 1120, switch 952 is open, switch 954 is closed, switch 958 is open, and switch 956 is closed. In switch configuration 1120, 0 volts is present across the resonant tank including inductor 962 and capacitor 964. As shown in FIG. 11C, in switch configuration 1130, switch 954 is open, switch 952 is closed, switch 956 is closed, and switch 958 is open. In switch configuration 1130, a voltage of 0.5 Vdc is present across the resonant tank including inductor 962 and capacitor 964. 11D, in switch configuration 1140, switch 954 is closed, switch 952 is open, switch 956 is open, and switch 958 is closed. In switch configuration 1140, a voltage of 0.5 Vdc is present across the resonant tank, which includes inductor 962 and capacitor 964.

[0126] In some embodiments, rather than switching to switch configuration 1130 and / or switch configuration 1140, switch control circuit 326 may control switches 954, 956, and 958 to switch between switch 952, switch configuration 1110, and switch configuration 1120 for unequal time durations. Thus, the voltage across resonant tank 324 does not remain at a medium voltage for a significant amount of time (e.g., >10% of the operating time) during wireless charging of a vehicle. Compared to a situation in which switching circuit 1022 switches to switch configuration 1130 and / or switch configuration 1140, common-mode voltages and leakage currents associated with resonant tank 324 and switching circuit 1022 may be reduced, for example, as discussed with reference to FIGS. 13 , 14 , and 15 . Additionally, electromagnetic interference, radiated emissions, and / or energy consumption associated with wireless charging pad 1000 may also be reduced.

[0127] Additional Example Voltage Amplitude Waveforms 12A-12B show example waveforms of voltage amplitudes associated with operation of the wireless charging pad of FIG. 10 in accordance with some embodiments of the present disclosure. FIG. 12A shows example waveforms 1250A and 1260A associated with operation of the wireless charging pad 1000 of FIG. 10 in accordance with some embodiments of the present disclosure. More specifically, waveforms 1250A and 1260A show voltage amplitudes and voltages across the resonant tank 324 when the switching circuit 1022 switches between various switch configurations and the switching circuit 1022 is a stacked half-bridge circuit (e.g., stacked half-bridge circuit 950 of FIG. 9). The voltage across the resonant tank 324 of FIG. 10 may correspond to the voltage v (shown in FIG. 9) associated with the resonant tank 960.

[0128] Waveform 1250A is associated with switching circuit 1022 switching between switch configuration 1110, switch configuration 1130 or 1140, and switch configuration 1120. In waveform 1250A, switching circuit 1022 is in switch configuration 1130 or 1140, then in switch configuration 1110, then in switch configuration 1130 or 1140, and then in switch configuration 1120, in one switching cycle. In a switching cycle, switching circuit 1022 may be in a switch configuration in waveform 1250A for one-quarter or other suitable duration (e.g., more than or less than one-quarter) of the switching cycle before switching to another switch configuration. In some embodiments, in a switching cycle, switching circuit 1022 is in switch configuration 1130, then in switch configuration 1110, then in switch configuration 1130, and then in switch configuration 1120. In some embodiments, in a switching cycle, switching circuit 1022 is in switch configuration 1140, then in switch configuration 1110, then in switch configuration 1140, and then in switch configuration 1120. In some embodiments, in a switching cycle, switching circuit 1022 is in switch configuration 1130, then in switch configuration 1110, then in switch configuration 1140, and then in switch configuration 1120. In some embodiments, in a switching cycle, switching circuit 1022 is in switch configuration 1140, then in switch configuration 1110, then in switch configuration 1130, and then in switch configuration 1120.

[0129] Waveform 1250A shows two switching cycles. When switching circuit 1022 is in switch configuration 1110, the voltage across resonant tank 324 may be around a high voltage (e.g., Vdc). When switching circuit 1022 is in switch configurations 1130 or 1140, the voltage across resonant tank 324 may be around a medium voltage (e.g., 0.5 Vdc). When switching circuit 1022 is in switch configuration 1120, the voltage across resonant tank 324 may be around a low voltage (e.g., 0 V). In some embodiments, Vdc may be in the range of 700 V to 1000 V.

[0130] Waveform 1260A is associated with switching circuit 1022 repeatedly switching between switch configuration 1110 and switch configuration 1120 without switching to switch configuration 1130 or switch configuration 1140. Waveform 1260A corresponds to switching circuit 1022 alternating and sequentially between switch configuration 1110 and switch configuration 1120. When switching circuit 1022 is in switch configuration 1110, the voltage across resonant tank 324 may be around Vdc. When switching circuit 1022 is in switch configuration 1120, the voltage across resonant tank 324 may be around 0 volts. Waveform 1260A shows that during a switching cycle, switching circuit 1022 is in switch configuration 1110 around 25% of the time and in switch configuration 1120 around 75% of the time. Thus, waveform 1260A has an unbalanced duty cycle. In some other applications, the switching circuit 1022 may have any other suitable unbalanced duty cycles for the switching cycles, such as, but not limited to, (a) 70% for switch configuration 1120 and 30% for switch configuration 1110, or (b) 80% for switch configuration 1120 and 20% for switch configuration 1110.

[0131] The modulation scheme corresponding to waveform 1260A may achieve the same or substantially the same short-circuit functionality as the modulation scheme corresponding to waveform 1250A. Furthermore, the relatively high leakage current penalty associated with switch configurations 1130 or 1140 of waveform 1250A is avoided in waveform 1260A. Furthermore, less switching occurs in each switching cycle to generate waveform 1260A compared to generating waveform 1250A. Therefore, switching losses and dead-time losses are reduced in the switching cycles associated with waveform 1260A compared to the switching cycles associated with waveform 1250A. Additionally, switching operations based on waveform 1260A may result in reduced energy consumption, reduced electromagnetic interference, and / or reduced conducted and radiated emissions.

[0132] 12B shows example waveforms 1250A and 1260B associated with operation of the wireless charging pad 1000 (e.g., when the switching circuit 1022 is a stacked half-bridge circuit) in accordance with some embodiments of the present disclosure. Waveform 1250A is the same in FIGS. 12A and 12B. As noted above, waveform 1250A is associated with switching circuit 1022 switching between switch configuration 1110, switch configurations 1130 / 1140, and switch configuration 1120 in a sequence that repeats every switching cycle. When switching circuit 1022 is in switch configuration 1110, the voltage across resonant tank 324 may be around Vdc. When switching circuit 1022 is in switch configuration 1130 / 1140, the voltage across resonant tank 324 may be around 0.5 Vdc. When the switching circuit 1022 is in the switch configuration 1120, the voltage across the resonant tank 324 may be around 0 volts.

[0133] Waveform 1260B is associated with switching circuit 1022 repeatedly switching between switch configuration 1110 and switch configuration 1120 without switching to switch configuration 1130 or switch configuration 1140. Waveform 1260B corresponds to switching circuit 1022 alternating and sequentially between switch configuration 1110 and switch configuration 1120. When switching circuit 1022 is in switch configuration 1110, the voltage across resonant tank 324 may be around Vdc. When switching circuit 1022 is in switch configuration 1120, the voltage across resonant tank 324 may be around 0 volts. Waveform 1260B is similar to waveform 1260A, except waveform 1260B is in switch configuration 1120 less than switch configuration 1110. For example, FIG. 12B corresponds to switching circuit 1022 being in switch configuration 1110 approximately 75% of the time and in switch configuration 1120 approximately 25% of the time. In some other applications, switching circuit 1022 may have any other suitable unbalanced duty cycles for the switching cycles, such as, but not limited to, (a) 70% for switch configuration 1110 and 30% for switch configuration 1120, or (b) 80% for switch configuration 1110 and 20% for switch configuration 1120. Compared to the switching cycle associated with waveform 1250A, the common-mode voltage and leakage current associated with resonant tank 324 and switching circuit 1022 may be reduced due to alternating and sequential switching between switch configurations 1110 and 1120 with unbalanced duty cycles. Additionally, switching operations based on waveform 1260B may result in reduced energy consumption, reduced electromagnetic interference, and / or reduced conducted and radiated emissions.

[0134] Additional Exemplary Voltage and Current Waveforms 13, 14, and 15 show example voltage and current waveforms associated with the operation of the wireless charging pad 1000 of FIG. 10 (e.g., when the switching circuit 1022 is a stacked half-bridge circuit) according to some embodiments of the present disclosure.

[0135] 13 illustrates voltage and current waveforms associated with a wireless charging system implementing the exemplary circuit diagram of FIG. 9 on a ground pad and a vehicle pad when stacked half-bridge circuit 950 switches according to waveform 1250A. Waveform 1302 illustrates the common-mode voltage of the ground pad (e.g., the voltage between terminal point 970 and the midpoint of inductor 962 when implemented on a ground pad). Waveform 1304 illustrates the common-mode voltage of the vehicle pad (e.g., the voltage between terminal point 970 and the midpoint of inductor 962 when implemented on a vehicle pad). Waveform 1312 illustrates the voltage across resonant tank 960 implemented on the ground pad. Waveform 1314 illustrates the voltage across resonant tank 960 implemented on the vehicle pad. Waveform 1322 illustrates the current through resonant tank 960 implemented on the ground pad. Waveform 1324 illustrates the current through resonant tank 960 implemented on the vehicle pad.

[0136] Waveform 1302 shows that the common mode voltage of the ground pad is non-zero and varies within a relatively wide range (e.g., varying between 250V and -250V). This can cause significant leakage current on the ground pad. Waveform 1304 shows that the common mode voltage of the vehicle pad is non-zero and varies within a relatively wide range (e.g., varying between 200V and -200V). This can be associated with significant leakage current on the vehicle pad.

[0137] 14 illustrates voltage and current waveforms associated with a wireless charging system implementing the exemplary circuit diagram of FIG. 9 on a ground pad and a vehicle pad when stacked half-bridge circuit 950 switches according to waveform 1260A. Waveform 1452 illustrates the common-mode voltage of the ground pad (e.g., the voltage between terminal point 970 and the midpoint of inductor 962 when implemented on the ground pad). Waveform 1454 illustrates the common-mode voltage of the vehicle pad (e.g., the voltage between terminal point 970 and the midpoint of inductor 962 when implemented on the vehicle pad). Waveform 1462 illustrates the voltage across resonant tank 960 implemented on the ground pad. Waveform 1464 illustrates the voltage across resonant tank 960 implemented on the vehicle pad. Waveform 1472 illustrates the current through resonant tank 960 implemented on the ground pad. Waveform 1474 illustrates the current through resonant tank 960 implemented on the vehicle pad.

[0138] 14 shows that when the stacked half-bridge circuit 950 implemented on both the ground pad and the vehicle pad switches to correspond to waveform 1260A, the magnitude of the common-mode voltage on both the ground pad and the vehicle pad is near 0 volts. Waveform 1452 shows that the common-mode voltage on the ground pad is near zero (e.g., fluctuating around 0 V). This is associated with a significant reduction in leakage current on the ground pad. Waveform 1454 shows that the common-mode voltage on the vehicle pad is near zero (e.g., fluctuating around 0 V). This is associated with a significant reduction in leakage current on the vehicle.

[0139] 15 illustrates voltage and current waveforms associated with a wireless charging system implementing the exemplary circuit diagram of FIG. 9 on a ground pad and a vehicle pad when stacked half-bridge circuit 950 switches according to waveform 1260B. Waveform 1552 illustrates the common-mode voltage of the ground pad (e.g., the voltage between terminal point 970 and the midpoint of inductor 962 when implemented on the ground pad). Waveform 1554 illustrates the common-mode voltage of the vehicle pad (e.g., the voltage between terminal point 970 and the midpoint of inductor 962 when implemented on the vehicle pad). Waveform 1562 illustrates the voltage across resonant tank 960 implemented on the ground pad. Waveform 1564 illustrates the voltage across resonant tank 960 implemented on the vehicle pad. Waveform 1572 illustrates the current through resonant tank 960 implemented on the ground pad. Waveform 1574 illustrates the current through resonant tank 960 implemented on the vehicle pad.

[0140] 15 shows that when the stacked half-bridge circuit 950 implemented on both the ground pad and the vehicle pad switches to correspond to waveform 1260B, the magnitude of the common-mode voltage on both the ground pad and the vehicle pad is near 0 volts. Waveform 1552 shows that the common-mode voltage on the ground pad is near zero (e.g., fluctuating around 0 V). This is associated with a significant reduction in leakage current on the ground pad. Waveform 1554 shows that the common-mode voltage on the vehicle pad is near zero (e.g., fluctuating around 0 V). This is associated with a significant reduction in leakage current on the vehicle. conclusion

[0141] The foregoing disclosure is not intended to limit the present disclosure to the precise form or particular field of use disclosed. Accordingly, various alternative embodiments and / or modifications to the present disclosure, whether expressly described or implied herein, are contemplated in light of the present disclosure. Having thus described embodiments of the present disclosure, those skilled in the art will recognize that changes can be made in form and detail without departing from the scope of the present disclosure. Accordingly, the present disclosure is limited only by the claims.

[0142] It should be understood that not necessarily all objectives or advantages may be achieved in accordance with any particular embodiment described herein. Thus, for example, those skilled in the art will recognize that some embodiments may operate in a manner that achieves or optimizes one advantage or group of advantages as taught herein, without necessarily achieving other objectives or advantages that may be taught or suggested herein.

[0143] All of the processes described herein may be embodied in software code modules executed by a computing system including a computer or processor, and thereby fully automated. The code modules may be stored in any type of non-transitory computer-readable medium or other computer storage device. Some or all of the methods may be embodied in dedicated computer hardware.

[0144] Many variations beyond those described herein will be apparent from this disclosure. For example, depending on the embodiment, some operations, events, or functions of any of the algorithms described herein may be performed in a different order, or may be added, merged, or entirely omitted (e.g., not all described operations or events may be necessary to practice the algorithm). Furthermore, in some embodiments, operations or events may be performed in parallel rather than sequentially, for example, through multithreading, interrupt processing, or multiple processors or processor cores, or on other parallel architectures. Additionally, different tasks or processes may be performed by different machines and / or computing systems that can function together.

[0145] The various illustrative logic blocks and modules described in connection with the embodiments disclosed herein may be implemented or performed by a machine, such as a processing unit or processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate 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, combinations thereof, etc. A processor may include electrical circuitry that processes computer-executable instructions. In some embodiments, a processor includes an FPGA or other programmable device that performs logical operations without processing computer-executable instructions. A processor may also be implemented as a combination of computing devices, such as, for example, a combination of a DSP and a microprocessor, multiple microprocessors, a microprocessor in combination with a DSP core, or any other such configuration. Although described herein primarily with reference to digital technology, a processor may also include primarily analog components. The computing environment may include any type of computer system, including, but not limited to, a computer system based on a computational engine within a microprocessor, mainframe computer, digital signal processor, portable computing device, device controller, or appliance, to name a few.

[0146] Elements of a method, process, routine, or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor device, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of non-transitory computer-readable storage medium. An exemplary storage medium may be coupled to the processor device such that the processor device can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integral to the processor device. The processor device and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. Alternatively, the processor device and the storage medium may reside as discrete components in a user terminal.

[0147] The processes described herein or illustrated in the figures of this disclosure may be initiated in response to an event, such as a predetermined or dynamically determined schedule, on demand when initiated by a user or system administrator, or in response to some other event. When such processes are initiated, a set of executable program instructions stored on one or more non-transitory computer-readable media (e.g., hard drives, flash memory, removable media, etc.) may be loaded into memory (e.g., RAM) of a server or other computing device. The executable instructions may then be executed by a hardware-based computer processor of the computing device. In some embodiments, such processes, or portions thereof, may be implemented on multiple computing devices and / or multiple processors, either serially or in parallel.

[0148] Unless otherwise specified or understood within the context of use, conditional language such as "can," "could," "might," or "may," among others, is generally used to suggest that some embodiments include certain features, elements, and / or steps, while other embodiments do not. Thus, such conditional language is not generally intended to imply that features, elements, and / or steps are in any way part of an embodiment, or that an embodiment necessarily includes logic for determining whether or not those features, elements, and / or steps are included or performed in any particular embodiment, with or without user input or a request for input.

[0149] Disjunctive language such as the phrase "at least one of X, Y, or Z" is generally understood to be used to indicate that an item, term, etc. can be either X, Y, or Z, or any combination thereof (e.g., X, Y, and / or Z), unless otherwise indicated from context. Thus, such disjunctive language is generally not intended to, and should not, imply that some embodiments require at least one of X, at least one of Y, or at least one of Z, respectively, to be present.

[0150] Any process descriptions, elements, or blocks in the flow diagrams described herein and / or depicted in the accompanying drawings should also be understood as potentially representing modules, segments, or portions of code, including executable instructions for implementing specific logical functions or elements in the process. The scope of the embodiments described herein includes alternative embodiments in which elements or functions may be omitted, performed in a different order than shown or described, or performed substantially simultaneously or in the reverse order, depending on the functionality involved, as can be understood by one of ordinary skill in the art.

[0151] It should be emphasized that many variations and modifications can be made to the above examples, and that the elements thereof should be understood to be among other acceptable embodiments, and all such modifications and variations are intended to be included herein within the scope of this disclosure.

[0152] Any process descriptions, elements, or blocks in the flow diagrams described herein and / or depicted in the accompanying drawings should also be understood as potentially representing modules, segments, or portions of code that contain executable instructions for implementing specific logical functions or elements in the process. The scope of the embodiments described herein includes alternative implementations in which elements or functions may be omitted, performed in a different order than shown or described, or performed substantially simultaneously or in the reverse order, depending on the functionality involved, as can be understood by one of ordinary skill in the art.

[0153] Unless otherwise specified, articles such as "a" or "an" should generally be construed to include one or more described items. Thus, phrases such as "a device configured to" are intended to include one or more of the listed devices. Such one or more listed devices may also be collectively configured to perform the stated enumeration. For example, "a processor configured to perform enumerations A, B, and C" may 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. 1. A method of wireless power transmission, comprising: Alternating and sequentially switching the ground pad switching circuitry between a first switch configuration and a second switch configuration with unequal duty cycles, a voltage across a resonant tank electrically connected to the switching circuit is different from a mid-voltage in both the first switch configuration and the second switch configuration; the switching circuitry configured to provide a high voltage, a low voltage, or the intermediate voltage across the resonant tank; using the voltage to cause wireless power transfer from the ground pad to a vehicle pad of a vehicle; A method comprising:

2. The method of claim 1 , wherein the medium voltage is associated with a third switch configuration in which the switching circuit does not switch during the switching.

3. 2. The method of claim 1, wherein the switching circuit is an H-bridge circuit and the intermediate voltage is 0 volts.

4. 2. The method of claim 1, wherein the switching circuit is a stacked half-bridge circuit and the intermediate voltage is one-half of a first voltage associated with the first switch configuration.

5. 2. The method of claim 1, wherein the switching step comprises being in the first switch configuration for at least 60% of the switching cycle and in the second switch configuration for the remainder of the switching cycle.

6. The method of claim 1 , wherein the switching step is performed in response to detecting that a voltage of a battery pack of the vehicle meets a threshold value.

7. The method of claim 1 , wherein the switching step is performed in response to detecting that a charge level of a battery pack of the vehicle meets a threshold.

8. 2. The method of claim 1, wherein the voltage across the resonant tank has an opposite polarity in the second switch configuration than in the first switch configuration.

9. 2. The method of claim 1, wherein the vehicle comprises a battery pack configured to charge based on the wireless power transmission, and the battery pack of the vehicle has a voltage range between 100 volts and 1000 volts.

10. 1. A method for operating a vehicle pad in a wireless charging environment, comprising: receiving power wirelessly from a ground pad at the vehicle pad of the vehicle, the vehicle pad including a switching circuit; alternating and sequentially switching the switching circuit between a first switch configuration and a second switch configuration with an unbalanced duty cycle, the first switch configuration being associated with a high voltage across a resonant tank and the second switch configuration being associated with a low voltage across the resonant tank; Including, the switching circuit is configured to provide one of the high voltage, the low voltage, or an intermediate voltage across the resonant tank; The method, wherein the medium voltage is lower than the high voltage and higher than the low voltage.

11. The method of claim 10 , wherein the medium voltage is associated with a third switch configuration in which the switching circuit does not switch during the switching.

12. 11. The method of claim 10, wherein the switching step comprises being in the first switch configuration for at least 60% of the switching cycle and in the second switch configuration for the remainder of the switching cycle.

13. The method of claim 10 , wherein the voltage across the resonant tank has an opposite polarity in the second switch configuration as compared to the first switch configuration.

14. The method of claim 10 , further comprising charging a battery pack of the vehicle based on the power received wirelessly from the ground pad.

15. A wireless charging pad, a resonant tank including a coil arranged for wireless power transfer; a switching circuit electrically connected to the resonant tank, the switching circuit being configurable into at least a first switch configuration associated with a high voltage across the resonant tank, a second switch configuration associated with a low voltage across the resonant tank, and a third switch configuration associated with an intermediate voltage across the resonant tank, the intermediate voltage being higher than the low voltage and lower than the high voltage; a switch control circuit configured to alternately and sequentially switch the switching circuit between the first switch configuration and the second switch configuration with unequal duty cycles; Equipped with The wireless charging pad is configured to transfer sufficient wireless power to charge a vehicle battery pack, the battery pack having an operating voltage of at least 350 volts.

16. 16. The wireless charging pad of claim 15, wherein the switching circuit comprises an H-bridge circuit and the intermediate voltage is 0 volts.

17. 17. The wireless charging pad of claim 16, wherein the voltage across the resonant tank has an opposite polarity in the second switch configuration compared to the first switch configuration.

18. 16. The wireless charging pad of claim 15, wherein the switching circuit comprises a stacked half-bridge circuit, and the medium voltage is half the high voltage.

19. 16. The wireless charging pad of claim 15, wherein switching the switching circuitry comprises being in the first switch configuration for at least 60% of the switching cycle and in the second switch configuration for the remainder of the switching cycle.

20. 16. The wireless charging pad of claim 15, wherein alternating and sequentially switching the switching circuits is performed in response to detecting that the voltage of the battery pack meets a threshold value.

Images