Reverse wireless charging

Abstract

Embodiments of the present disclosure relate to reverse wireless charging. A method and system for operating a power circuit capable of transmitting wireless power and receiving wireless power are provided. The method includes determining that the power circuit is operating in a receive mode and, based thereon, having a first equivalent capacitance. The method further includes determining that the power circuit is operating in a transmit mode and, based thereon, having a second equivalent capacitance. The first equivalent capacitance is different from the second equivalent capacitance.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to wireless charging, and in particular embodiments, to a system and method for reverse wireless charging. BACKGROUND

[0002] A wireless power system provides a method for wireless energy transfer between at least two devices. A transmitting device generates an electromagnetic field and a receiving device receives energy using inductive coupling. The receiving device stores the energy in a battery or consumes power in a load.

[0003] The efficiency of the energy transfer depends mainly on the coupling factor between the transmitting side coil and the receiving side coil, the angle of the coils, the state of the load or battery, and the operating temperature of the transmitting and receiving devices.

[0004] Reverse wireless charging refers to a feature that enables a receiving device in a first wireless power system to act as a transmitting device in a second wireless power system. As an example, a first mobile device capable of reverse wireless charging can charge itself when placed on a charging pad, and can charge a second mobile device when the second mobile device is placed on (or near) the first mobile device. Thus, the first mobile device has the advantage of being able to function as a charging pad for the second mobile device.

[0005] Typically, a device capable of reverse wireless charging uses the same coil to receive and transmit wireless energy. An inductance-capacitance (LC) tank circuit including the shared coil in both operating modes determines the resonant frequency of the device. Because the design is typically optimized for the receive operating mode, this rigidity of the LC tank circuit structure reduces the coupling factor during the transmit operating mode.

[0006] Therefore, a robust and reliable system and method for improving coupling in the transmit and receive operating modes in a device capable of reverse wireless charging is desirable. SUMMARY

[0007] A first aspect relates to a method of operating a power circuit. The method includes that the power circuit has a first mode and a second mode corresponding to receiving power using inductive charging and transmitting power at a coil of the power circuit, respectively. The method further includes determining that the power circuit is operating in the first mode and, based thereon, coupling the coil in series with a parallel coupling of a first capacitor of the power circuit and a second capacitor of the power circuit. Additionally, the method includes determining that the power circuit is operating in the second mode and, based thereon, coupling the coil in series with the first capacitor and coupling the second capacitor to a reference potential.

[0008] In a first implementation of the method according to the first aspect, the tank circuit of the power circuit in the second mode comprises the coil in series with the first capacitor. The equivalent capacitance and the equivalent inductance of the tank circuit in the second mode are about 300 millimicrofarad and 8 microhenry, respectively.

[0009] In a second implementation of the method according to the first aspect or any preceding implementation of the first aspect, the resonant frequency of the power circuit is determined from the equivalent inductance and the equivalent capacitance of the tank circuit.

[0010] In a third implementation of the method according to the first aspect or any preceding implementation of the first aspect, the second capacitor is coupled in series to the switch. The coupling of the coil in series with the parallel coupling of the first capacitor and the second capacitor comprises setting the switch in a closed position.

[0011] In a fourth implementation of the method according to the first aspect or any preceding implementation of the first aspect, the second capacitor is coupled in series to the switch. The coupling of the coil in series with the first capacitor and the coupling of the second capacitor to the reference potential comprises setting the switch in an open position.

[0012] In a fifth implementation of the method according to the first aspect or any preceding implementation of the first aspect, the second capacitor is coupled in series to the switch. The switch comprises a first transistor arranged in series with a second transistor.

[0013] In a sixth implementation of the method according to the first aspect or any preceding implementation of the first aspect, the determining whether the power circuit is operating in the first mode or in the second mode is from a signal received from an external device.

[0014] A second aspect relates to a device comprising a coil, a tank circuit, a non-transitory memory storage, and a processor. The coil is configured to operate in a first mode and a second mode, the first mode and the second mode corresponding to receiving power and transmitting power, respectively, using inductive charging. The tank circuit in the first mode comprises the coil, a first capacitor, and a second capacitor. The tank circuit in the second mode comprises the coil and the second capacitor. The non-transitory memory storage comprises instructions. The processor is in communication with the non-transitory memory storage and executes the instructions to: (1) determine that the coil is operating in the first mode, and based thereon, couple the coil in series with a parallel coupling of the first capacitor and the second capacitor, and (2) determine that the coil is operating in the second mode, and based thereon, couple the coil in series with the first capacitor and couple the second capacitor to a reference potential.

[0015] In a first implementation form of the device according to the first aspect, the tank circuit in the second mode comprises the coil in series with the first capacitor. The equivalent capacitance and the equivalent inductance of the tank circuit in the second mode are about 300 millimicrofarad and 8 microhenry, respectively.

[0016] In a second implementation form of the device according to the second aspect or any preceding implementation form of the second aspect, the second capacitor is coupled in series to the switch. Coupling the coil in series with the parallel coupling of the first capacitor and the second capacitor comprises setting the switch in a closed position.

[0017] In a third implementation form of the device according to the second aspect or any preceding implementation form of the second aspect, the second capacitor is coupled in series to the switch. Coupling the coil in series with the first capacitor and coupling the second capacitor to the reference potential comprises setting the switch in an open position.

[0018] In a fourth implementation form of the device according to the second aspect or any preceding implementation form of the second aspect, the second capacitor is coupled in series to the switch. The switch comprises a first transistor arranged in series with the second transistor.

[0019] In a fifth implementation form of the device according to the second aspect or any preceding implementation form of the second aspect, the device is a semiconductor package.

[0020] In a sixth implementation form of the device according to the second aspect or any preceding implementation form of the second aspect, the device is a mobile device, a tablet, a cellular phone, a mobile power supply, or a battery pack.

[0021] In a seventh implementation form of the device according to the second aspect or any preceding implementation form of the second aspect, determining whether the coil is operating in the first mode or in the second mode is according to a signal received from an external device.

[0022] A third aspect relates to a method comprising: having an inductance capacitance (LC) tank circuit configured to transmit and receive wireless power using a coil of the LC tank circuit, the LC tank circuit having a first effective capacitance and an effective inductance corresponding to transmitting wireless power, the LC tank circuit having a second effective capacitance and the effective inductance corresponding to receiving wireless power.

[0023] In a first implementation form of the method according to the third aspect, determining whether the LC tank circuit is transmitting wireless power or receiving wireless power is according to a signal received from an external device.

[0024] In a second implementation of the method according to the third aspect or any preceding implementation of the third aspect, the LC tank circuit comprises a variable capacitor having a first capacitance value corresponding to the first effective capacitance, and the variable capacitor has a second capacitance value corresponding to the second effective capacitance.

[0025] In a third implementation of the method according to the third aspect or any preceding implementation of the third aspect, the method further comprises providing a control signal to the variable capacitor to vary the capacitance value of the variable capacitor between the first capacitance value and the second capacitance value in dependence on whether the wireless power is transmitted or received, respectively.

[0026] In a fourth implementation of the method according to the third aspect or any preceding implementation of the third aspect, the LC tank circuit comprises a coil for transmitting the wireless power and receiving the wireless power. The effective inductance of the LC tank circuit corresponds to the inductance of the coil.

[0027] The fourth aspect relates to a method comprising having an inductor-capacitor (LC) tank circuit configured to operate in a transmit mode and a receive mode for transmitting wireless energy and receiving wireless energy, respectively. The method further comprises arranging components of the LC tank circuit for transmitting the wireless energy. The LC tank circuit has an effective inductance and a first effective capacitance. And the method further comprises arranging components of the LC tank circuit for receiving the wireless energy. The LC tank circuit has the same effective inductance and a second effective capacitance different from the first effective capacitance.

[0028] Various embodiments can be implemented in hardware, software, or any combination thereof. BRIEF DESCRIPTION OF DRAWINGS

[0029] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings in which

[0030] Figure 1 is a simplified schematic diagram of an embodiment of a wireless power system;

[0031] Figure 2 is a simplified schematic diagram of another embodiment of a wireless power system;

[0032] Figure 3A is a simplified block diagram of an embodiment of a reverse chargeable device;

[0033] Figure 3B is a simplified block diagram of another embodiment of a reverse chargeable device;

[0034] Figure 4 is a schematic diagram of an inductor-capacitor (LC) tank circuit; and

[0035] Figure 5 is a flowchart of an embodiment of a method of operating a reverse chargeable device. DETAILED DESCRIPTION

[0036] The present disclosure provides a number of applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments are merely illustrative of specific configurations and are not limiting of the scope of the claimed embodiments. Features from different embodiments can be combined to form other embodiments unless otherwise indicated. Changes or modifications can also be made to the described embodiments without departing from the spirit or scope of the disclosure as defined in the claims.

[0037] While various aspects of the present invention are described primarily in the context of the Qi wireless interface standard for devices having a resonant frequency of approximately 100 kilohertz (kHz) and an operating frequency of approximately 125 kHz, it should also be appreciated that these inventive aspects can also be applicable to any other type of reverse wireless charging having different resonant frequencies and operating frequencies. Thus, embodiments of the present disclosure can be widely used to provide a shared inductance-capacitance (LC) tank circuit in a device having reverse wireless charging capability that can be optimally configured to provide a target resonant frequency in both transmit and receive modes. Further, embodiments of the present invention can operate without compliance with the Qi standard.

[0038] Generally, a device capable of transmitting wireless energy and receiving wireless energy has a shared LC tank circuit for operating in each of a transmit operating mode and a receive operating mode. The LC tank circuit primarily includes a coil and a capacitor. The inductance of the coil in the device depends on, but is different from, the inductance of a typical transmit coil. Because the typical use of the device is to charge a battery or power up the device, the capacitance of the LC tank circuit is selected to combine with the inductance to provide a resonant frequency for optimal receive mode operation. Thus, the rigidity of the structure of the shared LC tank circuit optimized for receive mode provides weak coupling in transmit mode because the corresponding resonant frequency is off the desired frequency on the frequency spectrum.

[0039] Accordingly, there is a need for an improved system and method to overcome these limitations in devices having reverse wireless charging capability. Various embodiments of the present disclosure provide a system and method that provides a configurable LC tank circuit for each of a transmit operating mode and a receive operating mode. In other words, the LC tank circuit has a first configuration optimized for receive mode and a second configuration optimized for transmit mode.

[0040] Aspects of the disclosure provide an LC tank circuit that includes a switch to either disconnect a first capacitor from a second capacitor or electrically couple the first capacitor with the second capacitor. Thus, the switch provides a first configuration corresponding to receive mode operation, where the first capacitor is disconnected from the second capacitor, and a second configuration corresponding to transmit mode operation, where the first capacitor is arranged in parallel with the second capacitor. In another embodiment, a variable capacitor is used that has a first value optimized for transmit mode and a second value optimized for receive mode. These and other details are discussed in greater detail below.

[0041] Figure 1 A simplified schematic of a wireless power system 100 is illustrated. The wireless power system 100 includes a transmit device 110 and a reverse-chargeable device 120. The transmit device 110 wirelessly transfers power 140 to the reverse-chargeable device 120, i.e., the reverse-chargeable device 120 operates in receive mode. Figure 1 The power source 112 generates an alternating current (AC) at the transmit coil 116 that induces a magnetic field at the coil 122. The induced magnetic field induces an AC voltage at the coil 122 through mutual coupling. The rectifier 126 converts the AC voltage to a DC voltage. The regulator 130 converts the DC voltage from the rectifier 126 to match a desired DC voltage for the load 132.

[0042] The transmit device 110 can be a base station, e.g., a charging pad, that provides inductive power to the reverse-chargeable device 120. The transmit device 110 includes a power source 112, a power source side capacitor 114, and a transmit coil 116.

[0043] The power source 112 is any device that generates alternating current (AC) power that is supplied to the transmit coil 116. In an embodiment, the transmit device 110 can include a DC-AC inverter to provide the AC power.

[0044] The transmit coil 116 can be a loop antenna or a magnetic antenna. The transmit coil 116 can include a physical core (e.g., a ferrite core) or an air core and can be implemented as an antenna strip or using a Litz wire.

[0045] The power source side capacitor 114 and the transmit coil 116 combine to form a transmit LC tank circuit 118. The power source 112 drives the transmit LC tank circuit 118 that generates an electromagnetic field at the transmit coil 116.

[0046] The reverse-chargeable device 120 can be, for example, a mobile device, a tablet, a cellular phone, a mobile power source, a battery pack, or other such device. The reverse-chargeable device 120 includes a receive coil 122 that can be as described above. Figure 1The illustrated arrangement (or can not be as Figure 1 The illustrated arrangement) of the coil 122, the capacitors 124 and 128, the rectifier 126, the regulator 130, and the load 132. The reverse-chargeable device 120 can include Figure 1 other components not depicted in FIG. 1, such as long-term storage (e.g., non-volatile memory, etc.), non-transitory computer-readable media, one or more antenna elements, drivers, demodulators, modulators, filter circuits, and impedance matching circuits.

[0047] The coil 122 is similar in features and structure to the transmit coil 116 and is arranged in series with the capacitor 124, which coil 122 and capacitor 124 combine to form an LC tank circuit 123.

[0048] The rectifier 126 is a device that converts alternating current (AC) voltage to direct current (DC) voltage. The rectifier 126 can be any type of rectifier, such as a low impedance synchronous rectifier with full-wave or half-wave rectification; or an active rectifier. Figure 1 The illustrated rectifier 126 is a bridge rectifier; however, other types of rectifiers are also contemplated.

[0049] The regulator 130 is a device that maintains a constant output voltage for the load 132. The regulator 130 receives an input voltage from the rectifier 126. The regulator 130 can be any type of voltage regulator, such as a linear regulator (e.g., a low-dropout (LDO) linear regulator). In some embodiments, the rectifier 126 and the regulator 130 can be part of a switched-mode power supply (SMPS) circuit.

[0050] The capacitor 128 is used to reduce any ripple at the input of the regulator 130 from the rectifier 126. The capacitor 128 can be referred to as a smoothing capacitor or tank capacitor.

[0051] The load 132 receives the delivered power. The load 132 can be a charge storage device, such as a battery. For example, the load 132 can be a battery of a cellular telephone.

[0052] Figure 2 A simplified schematic of a wireless power system 200 is illustrated. The wireless power system 200 includes a reverse-chargeable device 120 and a receiving device 210. The reverse-chargeable device 120 wirelessly transmits power 240 to the receiving device 210, i.e., the reverse-chargeable device 120 is in Figure 2The system is operating in transmit mode. Power source 212 generates alternating current (AC) at coil 122, which induces a magnetic field at receiving coil 222. The induced magnetic field induces an AC voltage at receiving coil 222 through mutual coupling. Rectifier 226 converts the AC voltage to DC voltage. Regulator 230 converts the DC voltage to match the desired DC voltage of load 232. Power source 212 uses, for example, energy stored in load 132 to provide alternating current at coil 122.

[0053] The receiving device 210 may be, for example, a mobile device, tablet computer, cellular phone, power bank, battery pack, or other such device. In some embodiments, the receiving device 210 may be a second reversible charging device operating in receiving mode.

[0054] The receiving device 210 includes devices that can, for example, Figure 2 The arrangement shown (or may be less) Figure 2 The arrangement shown includes a receiving coil 222, capacitors 224 and 228, a rectifier 226, a regulator 230, and a load 232. The receiving coil 222, capacitors 224 and 228, rectifier 226, regulator 230, and load 232 are in relation to a reference. Figure 1 Similar to their similarly named counterparts discussed with respect to reverse-chargeable device 120, receiving device 210 may include... Figure 2 Additional components not depicted include long-term storage devices (e.g., non-volatile memory), non-transitory computer-readable media, one or more antenna elements, drivers, demodulators, modulators, filter circuits, and impedance matching circuits.

[0055] Figure 1 The mutual inductance between the transmitting device 110 and the reverse rechargeable device 120 depends primarily on the resonant frequencies of the transmitting LC energy storage circuit 118 and the LC energy storage circuit 123, and on the spacing and angle between the transmitting coil 116 and the coil 122. Similarly, Figure 2 The mutual inductance between the reverse rechargeable device 120 and the receiving device 210 depends primarily on the resonant frequencies of the LC energy storage circuit 123 and the receiving LC energy storage circuit 223, as well as on the spacing and angle between the coil 122 and the receiving coil 222.

[0056] Typically, the performance characteristics of the transmitting LC energy storage circuit 118, the LC energy storage circuit 123, and the receiving LC energy storage circuit 223 depend on their interconnection with other integrated circuit components in their respective devices. However, the LC energy storage circuits in this disclosure are discussed separately and are summarized as the main power transmission elements of the transmitting device 110, the reverse rechargeable device 120, and the receiving device 210, respectively.

[0057] The inductance of the transmit coil 116, the coil 122, and the receive coil 222 generally depends on their windings and physical dimensions. The windings of the coils are generally tightly coupled, and the inner diameter of the receive coil 222 is generally kept within about 75% to 100% of the inner diameter of the transmit coil 116 to ensure proper system performance and improve coupling. In other words, the inductance of the receive coil 222 is primarily dependent on the inductance of the transmit coil 116.

[0058] Accordingly, in the reverse chargeable device 120, the inductance and physical dimensions of the coil 122 are constrained by the imposed limitations of operating in the receive mode. By extension, the operational characteristics of the LC tank 123 are constrained by these same limitations.

[0059] The interface standard specifies wireless power transfer and its related functionalities, and provides a range of operating frequencies for proper power transfer from the transmit device to the receive device.

[0060] In an embodiment, the equivalent inductance and equivalent capacitance of the transmit LC tank 118 are selected based on the target resonant frequency of the transmit device 110. As previously noted, the inductance of the coil 122 depends on the size and value of the transmit coil 116. The value of the capacitor 124 is then selected to provide enhanced mutual coupling between the LC tank 123 and the LC tank 118. Generally, since the primary operational goal of the reverse chargeable device 120 is to charge or receive power from the transmit device 110 for optimal mutual coupling, the LC tank 123 is designed for receive mode operation.

[0061] In an embodiment, to operate within the Qi standard, the capacitance and inductance of the transmit LC tank 118 are about 400 nanofarads (nF) and about 6.3 micro-henries (μH), respectively. Accordingly, the target resonant frequency of the transmit device is about 100 kilohertz (kHz). In this embodiment, the inductance of the coil 122 is about 8 μH, and the capacitance of the capacitor 124 is about 500 nF to ensure maximum efficiency in wireless power transfer.

[0062] Generally, the operating frequency of the transmit device 110 is set to be higher than the resonant frequency of the transmit LC tank 118 to allow a level of adjustment and control over the transferred energy. Accordingly, in an embodiment in which the transmit LC tank 118 is designed to resonate at a frequency of about 100 kHz, the operating frequency is, for example, greater than 110 kHz.

[0063] In an embodiment, the resonant frequency of the transmit LC tank circuit 118 is about 100 kHz, and the operating frequency of the transmit device 110 is about 125 kHz. In this example embodiment, the decrease in operating frequency from 125 kHz toward the resonant frequency of 100 kHz increases the power delivered to the reverse-chargeable device 120. In contrast, an increase in operating frequency decreases the energy delivered to the reverse-chargeable device 120.

[0064] Figure 2 The LC tank circuit 123 includes Figure 1 the coil 122 and the capacitor 124 previously described in the transmit device 110. The receive LC tank circuit 223 includes a capacitor 224 and a receive coil 222.

[0065] The resonant frequency (f) of a tank circuit can be estimated using the following equation: where L is the inductance of the tank circuit, and C is the capacitance of the tank circuit.

[0066] It should be appreciated that the values of the components and the resonant frequency can be determined by other means, such as empirical observation (e.g., on a test bench).

[0067] In an embodiment in which the inductance of the coil 122 is about 8 μΗ and the capacitance of the capacitor 124 is about 500 nF, the resonant frequency of the LC tank circuit 123 in transmit mode is about 80 kHz, which is a shift of approximately 20% from the desired resonant frequency of 100 kHz within the spectrum.

[0068] Since the receive LC tank circuit 223 of the receive device 210 can be designed to be compatible with the Qi standard of about 100 kHz, the shift in resonant frequency reduces the mutual coupling, resulting in a decrease in power transfer efficiency and an increase in charging time of the wireless power system 200.

[0069] Various embodiments of the present disclosure provide a solution to improve mutual coupling in the reverse-chargeable device 120 by providing a tank circuit that can be individually configured in each of a transmit and receive operating mode.

[0070] Figure 3A A simplified block diagram illustrating an embodiment of a reverse-chargeable device 300 is shown. The reverse-chargeable device 300 can be used in place of the reverse-chargeable device 120 in the wireless power system 100 or 200. The reverse-chargeable device 300 advantageously includes an LC tank circuit 310 that can be selectively configured for operation in either transmit or receive mode.

[0071] In addition to the coil 122, the LC tank circuit 310 includes a switch 306 arranged in series with the capacitor 302. The series switch 306 and capacitor 302 are arranged in parallel with the capacitor 304. The switch 306 receives a control signal from the processor 320 to electrically couple or disconnect the capacitor 302 from the LC tank circuit 310. The capacitor 302 is shown as a single capacitor, but in embodiments, the capacitor 302 can include one or more capacitors arranged in series or parallel with each other.

[0072] The processor 320 can be, for example, a microprocessor, microcontroller, digital signal processor, field programmable gate array (FPGA), or application specific integrated circuit (ASIC). The reverse-chargeable device 300 is shown as having a single processor; however, in some embodiments, multiple processors can be included, and the various functions attributed herein to the processor 320 can be distributed across the multiple processors.

[0073] The memory 330 can be configured to store data, programs, firmware, operating systems, and other information, and to make that data, programs, firmware, operating systems, and additional information accessible to the processor 320. The memory 330 can include any type of non-transitory system memory, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or a combination thereof. In embodiments, the memory 330 can include ROM used at boot-up, and DRAM used for program, firmware, and data storage while executing programs. The memory 330 can include, for example, one or more of a solid state drive, a hard disk drive, a disk drive, a removable memory drive, or an optical disk drive.

[0074] The processor 320 provides the control signal to close or open the switch 306 based on the operating mode of the reverse-chargeable device 120. When the switch 306 is in the closed position, the equivalent capacitance of the LC tank circuit 310 is the sum of the capacitance values of the capacitors 302 and 304. Conversely, when the switch 306 is in the open position, the equivalent capacitance of the LC tank circuit 310 is equal to the capacitance of the capacitor 304.

[0075] The equivalent capacitance of the LC tank circuit 310 can be approximated using the following equation: where C, f, and L are the equivalent capacitance, inductance, and resonant frequency, respectively, of the LC tank circuit 310.

[0076] In an embodiment where the resonant frequency of the tank circuit is desired to be about 100 kHz in transmit mode and the inductance of the coil 122 is about 8 μΗ, the equivalent capacitance of the LC tank circuit 310 is about 300 nF. In such an embodiment, since the equivalent capacitance of the LC tank circuit 310 is desired to be about 500 nF to ensure maximum efficiency in receive mode, the capacitance values of the capacitors 304 and 302 are about 300 nF (as calculated) and 200 nF (e.g., 500 nF - 300 nF), respectively. In this embodiment, in receive mode, the switch 306 is in the closed position to provide an equivalent capacitance of about 500 nF for the LC tank circuit 310. Also, in transmit mode, the switch 306 is in the open position to provide an equivalent capacitance of about 300 nF for the LC tank circuit 310.

[0077] Thus, by electrically coupling and decoupling the capacitor 302 from the capacitor 304 within the LC tank circuit 310, respectively, the LC tank circuit 310 can provide better coupling with the transmit device 110 and the receive device 210. Selective disconnection or electrical coupling provides the LC tank circuit 310 with a resonant frequency suitable for the operating mode of the reversible chargeable device 120.

[0078] It should be noted that the switch 306 is shown arranged in series with the capacitor 302; however, in some embodiments, the switch 306 can be arranged in series with the capacitor 304. In such an embodiment, the switch 306 is in the closed position for receive mode operation and the switch 306 is in the open position for transmit mode operation. Also, the values of the capacitors 304 and 302 are selected appropriately for this modified operation.

[0079] The equivalent capacitance values presented herein are exemplary values and appropriate numbers can be determined for any desired resonant frequency.

[0080] Figure 3B A simplified block diagram of another embodiment of a reversible chargeable device 350 is illustrated. Similar to the reversible chargeable device 300, the reversible chargeable device 350 can be used in place of the reversible chargeable device 120 in the wireless power system 100 or 200. The reversible chargeable device 350 advantageously includes an LC tank circuit 360 that can be configured for operation in transmit mode or receive mode.

[0081] The LC tank circuit 360 includes the coil 122 and a variable capacitor 362. The variable capacitor 362 can be adjusted using a signal from the processor 320. In an embodiment, the variable capacitor is set to operate at a first capacitance value to provide a resonant frequency in transmit mode. In this embodiment, the variable capacitor is configured to operate at a second capacitance value in receive mode.

[0082] In an example embodiment, in the transmit mode, the coil 122 has an inductance value of about 8 μΗ, and the variable capacitor 362 has a capacitance value of about 300 nF. In an example embodiment, the variable capacitor 362 has a capacitance value of about 500 nF in the receive mode.

[0083] Figure 4 An example schematic diagram of the LC tank circuit 310 is illustrated. The LC tank circuit includes the coil 122, the capacitors 302 and 304, and the switch 306. The switch 306 includes the resistors 404 and 406, the capacitor 408, the switch 400, and the transistors 410 and 412.

[0084] Figure 4 An example circuit representing the switch 306 is illustrated in FIG. 4, which is non-limiting, and other circuits having similar operational characteristics are contemplated. Figure 3A

[0085] The transistors 410 and 412 are arranged as back-to-back transistors, with the drain terminal of the transistor 410 electrically coupled to the source terminal of the transistor 412. The source terminal of the transistor 412 is electrically coupled to the capacitor 302. The drain terminal of the transistor 412 is electrically coupled to the capacitor 302. The gate of each transistor 410 and 412 is electrically coupled to the processor 320.

[0086] The gate of each transistor 410 and 412 is electrically coupled to the source of the transistor 410, which can be electrically coupled to a reference ground through the switch 400 to reduce leakage at the reverse chargeable device in the transmit mode. In an embodiment, the switch 400 is electrically coupled to a reference voltage, and is not necessarily a reference ground, which has a smaller voltage potential than the terminal of the switch electrically coupled to the resistor 404. The processor 320 is electrically coupled to the transistor 400, the gate of the transistor 412, and the switch 400. The processor 320 provides a signal V SIG1 to activate or deactivate the transistors 410 and 412 and the switch 400. The switch 400 is electrically coupled to the processor 320 and transitions between an open position and a closed position according to the signal V SIG2 received from the processor 320.

[0087] In an embodiment corresponding to the transmit mode at the reverse chargeable device 120, the switch 400 is in the open position, and the transistors 410 and 412 are deactivated. In this embodiment, the equivalent capacitance of the LC tank circuit 310 is approximately equal to the value of the capacitance of the capacitor 304.

[0088] ​In the example embodiment, the inductance value of coil 122 is approximately 8 μΗ, and the capacitance value of capacitor 304 is approximately 300 nF. Thus, in this example embodiment, the capacitance value of LC tank circuit 310 in transmit mode is 300 nF. In an operating environment corresponding to an operating voltage of 10 V and an operating frequency of 125 kHz, and with a load of 10 ohms, the adjustment of the capacitance of LC tank circuit 310 from a typical 500 nF to 300 nF provides an approximately 60% increase in power transfer in transmit mode from about 8 watts (W) to about 12.7 W.

[0089] In embodiments in which reverse chargeable device 120 is in receive mode, switch 400 is in the closed position, and transistor 410 and transistor 412 are activated. In this embodiment, the equivalent capacitance of LC tank circuit 310 is approximately equal to the sum of the capacitances of capacitors 302 and 304.

[0090] In the example embodiment, the inductance value of coil 122 is approximately 8 μΗ, and the capacitance value of capacitor 304 is approximately 300 nF. Thus, in this example embodiment, the capacitance value of LC tank circuit 310 in transmit mode is 300 nF. In an operating environment corresponding to an operating voltage of 10 V and an operating frequency of 125 kHz, and with a load of 10 ohms, the adjustment of the capacitance of LC tank circuit 310 from a typical 500 nF to 300 nF provides an approximately 60% increase in power transfer in transmit mode from about 8 watts (W) to about 12.7 W.

[0091] Figure 5 FIG. illustrates a flowchart of an embodiment of a method 500 for operating an LC tank circuit as can be performed by reverse chargeable device 120. At step 510, processor 320 determines whether reverse chargeable device 120 is operating in a first mode corresponding to receiving wireless energy from a transmitting device 110 or a second mode corresponding to transmitting wireless power to a receiving device 210. In embodiments, the determination as to whether the device is operating in the first mode or the second mode is responsive to a signal received from an external device, such as transmitting device 110 or receiving device 210. In embodiments, the signal is an electromagnetic field generated by the external device. In other embodiments, the signal is a communication signal received from the external device, such as a near field communication.

[0092] At step 520, processor 320 arranges LC tank circuit 310 to operate in receive mode. In embodiments, processor 320 activates switch 306 to arrange coil 122 in series with the parallel configuration of capacitors 302 and 304 in LC tank circuit 310. In another embodiment, processor 320 activates variable capacitor 362 to provide a first capacitance value corresponding to proper operation in receive mode.

[0093] At step 530, the processor 320 arranges the LC tank circuit 310 to operate in a transmit mode. In an embodiment, the processor 320 deactivates the switch 306 to arrange the coil 122 in series with the capacitor 302 and disconnected from the capacitor 304 in the LC tank circuit 310. In another embodiment, the processor 320 activates the variable capacitor 362 to provide a second capacitance value corresponding to proper operation in the transmit mode.

[0094] It should be noted that the order of the steps shown is not absolutely required Figure 5 Thus, in principle, the various steps can be performed in a different order than that illustrated. Moreover, certain steps can be skipped, different steps can be added or substituted, or selected steps or groups of steps can be performed in separate applications.

[0095] In this specification, when referring to terms that define absolute positions such as the terms "front", "back", "top", "bottom", "left", "right", or terms that define relative positions such as the terms "above", "under", "upper", "lower", or terms that reference directions such as "horizontal", "vertical", it refers to the orientation of the drawing. The terms "about", "substantially", "approximately", and "on the order of" are used interchangeably herein to indicate approximations which can vary by positive / negative ten percent (10%), preferably positive / negative five percent (5%) of the value being discussed, unless otherwise stated.

[0096] Unless otherwise stated, when referring to two elements being electrically connected together, it means that the elements are directly connected, with no intervening elements other than conductors. When referring to two elements being electrically coupled together, it means that the two elements can be coupled (connected) directly or via one or more other elements.

[0097] While the specification has been described in detail with respect to specific embodiments, it will be appreciated that various changes, alternatives, and modifications can be made without departing from the spirit and scope of the present disclosure defined by the appended claims. In the various drawings, like elements are denoted by like reference numbers throughout. Moreover, the scope of the present disclosure is not intended to be limited to the particular embodiments described in the specification, as the same can vary according to the disclosure given to one of ordinary skill in the art. The scope of the present disclosure is set by the appended claims and their equivalents.

[0098] Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense, and it is intended that any and all modifications, variations, combinations or equivalents that are within the scope of the present disclosure are to be included within the scope of the claims.

Claims

1. A method for operating a power circuit, the method comprising: The power circuit has a first mode and a second mode, which correspond to receiving power and transmitting power using inductive charging at the coil of the power circuit, respectively. The power circuit further includes: A first capacitor, wherein a first node of the first capacitor is coupled to the coil; A second capacitor, the first node of which is coupled to the coil; The circuit includes: A first resistor, the first node of which is coupled to the second node of the second capacitor. A second resistor, wherein the first node of the second resistor is coupled to the second node of the first resistor. A switch, wherein a first node of the switch is coupled to a second node of the second resistor, and the second node of the switch is coupled to a reference ground. A third capacitor, wherein a first node of the third capacitor is coupled to a first node of the first resistor, and a second node of the third capacitor is coupled to a second node of the second resistor. A first transistor, the gate terminal of the first transistor being coupled to the second node of the first resistor, and the source terminal of the first transistor being coupled to the first node of the first resistor. The second transistor has its gate terminal coupled to the gate terminal of the first transistor, its source terminal coupled to the drain terminal of the first transistor, and its drain terminal coupled to the second node of the first capacitor. Determining that the power circuit is operating in the first mode, and based on this, placing the switch arrangement in the off position, and activating the first transistor and the second transistor; and It is determined that the power circuit is operating in the second mode, and based on this, the switch is configured to be in the closed position, and the first transistor and the second transistor are deactivated.

2. The method according to claim 1, wherein the energy storage circuit of the power circuit in the second mode includes the coil connected in series with the first capacitor, wherein the equivalent capacitance and equivalent inductance of the energy storage circuit in the second mode are 300 nanofarads and 8 microhenries, respectively.

3. The method according to claim 2, wherein the resonant frequency of the power circuit is determined based on the equivalent inductance and equivalent capacitance of the energy storage circuit.

4. The method of claim 1, wherein determining whether the power circuit is operating in the first mode or the second mode is based on a signal received from an external device.

5. An electronic device, comprising: First capacitor; A second capacitor, wherein the first node of the second capacitor is coupled to the first node of the first capacitor; The coil is configured to operate in a first mode and a second mode, the first mode and the second mode corresponding to receiving power and transmitting power using inductive charging, respectively. The circuit includes: A first resistor, the first node of which is coupled to the second node of the second capacitor. A second resistor, wherein the first node of the second resistor is coupled to the second node of the first resistor. A switch, wherein a first node of the switch is coupled to a second node of the second resistor, and the second node of the switch is coupled to a reference ground. A third capacitor, wherein a first node of the third capacitor is coupled to a first node of the first resistor, and a second node of the third capacitor is coupled to a second node of the second resistor. A first transistor, the gate terminal of the first transistor being coupled to the second node of the first resistor, and the source terminal of the first transistor being coupled to the first node of the first resistor. The second transistor has its gate terminal coupled to the gate terminal of the first transistor, its source terminal coupled to the drain terminal of the first transistor, and its drain terminal coupled to the second node of the first capacitor. Non-transitory memory storage device, including instructions; and A processor, communicating with the non-transitory memory storage device, wherein the processor executes the instructions to: Determining that the coil is operating in the first mode, and based on this, configuring the switch to the off position, and activating the first transistor and the second transistor, and It is determined that the coil is operating in the second mode, and based on this, the switch is configured to be in the closed position, and the first transistor and the second transistor are deactivated.

6. The electronic device of claim 5, wherein in the second mode, the coil is connected in series with the first capacitor, and the energy storage circuit comprising the first capacitor, the second capacitor, and the coil has an equivalent capacitance of 300 nanofarads and an equivalent inductance of 8 microhenries in the second mode.

7. The electronic device of claim 5, wherein the device is a semiconductor package.

8. The electronic device of claim 5, wherein the device is a mobile device or a battery pack.

9. The electronic device of claim 8, wherein the mobile device is a tablet computer or a cellular phone, and the battery pack is a power source.

10. The electronic device of claim 5, wherein determining whether the coil is operating in the first mode or the second mode is based on a signal received from an external device.

11. A method for operating an inductor-capacitor LC energy storage circuit, comprising: The system includes an inductor-capacitor (LC) energy storage circuit for transmitting and receiving wireless power using the coil of the LC energy storage circuit, the LC energy storage circuit further comprising: A first capacitor, wherein a first node of the first capacitor is coupled to the coil; A second capacitor, the first node of which is coupled to the coil; The circuit includes: A first resistor, the first node of which is coupled to the second node of the second capacitor. A second resistor, wherein the first node of the second resistor is coupled to the second node of the first resistor. A switch, wherein a first node of the switch is coupled to a second node of the second resistor, and the second node of the switch is coupled to a reference ground. A third capacitor, wherein a first node of the third capacitor is coupled to a first node of the first resistor, and a second node of the third capacitor is coupled to a second node of the second resistor. A first transistor, the gate terminal of the first transistor being coupled to the second node of the first resistor, and the source terminal of the first transistor being coupled to the first node of the first resistor. The second transistor has its gate terminal coupled to the gate terminal of the first transistor, its source terminal coupled to the drain terminal of the first transistor, and its drain terminal coupled to the second node of the first capacitor. The LC energy storage circuit is arranged to have a first effective capacitor and an effective inductor corresponding to the transmitted wireless power. The arrangement includes setting the switch to the closed position and deactivating the first transistor and the second transistor. The LC energy storage circuit is arranged to have a second effective capacitor and an effective inductor corresponding to the received wireless power. The arrangement includes setting the switch to the off position and activating the first transistor and the second transistor.

12. The method of claim 11, further comprising: The LC energy storage circuit determines whether it is transmitting or receiving wireless power based on signals received from external devices.

13. The method of claim 11, wherein the LC energy storage circuit includes a variable capacitor, wherein the variable capacitor has a first capacitance value corresponding to the first effective capacitance, and wherein the variable capacitor has a second capacitance value corresponding to the second effective capacitance.

14. The method of claim 13, wherein the method further comprises: A control signal is provided to the variable capacitor to vary the capacitance value of the variable capacitor between the first capacitance value and the second capacitance value, depending on the transmitted or received wireless power.

15. The method of claim 11, wherein the LC energy storage circuit includes a coil for transmitting and receiving wireless power, wherein the effective inductance of the LC energy storage circuit corresponds to the inductance of the coil.

16. A method for operating an inductor-capacitor LC energy storage circuit, comprising: An LC energy storage circuit with inductance and capacitance is configured to operate in transmit and receive modes, respectively, for transmitting and receiving wireless energy. The LC energy storage circuit includes: coil; A first capacitor, wherein a first node of the first capacitor is coupled to the coil; A second capacitor, the first node of which is coupled to the coil; The circuit includes: A first resistor, the first node of which is coupled to the second node of the second capacitor. A second resistor, wherein the first node of the second resistor is coupled to the second node of the first resistor. A switch, wherein a first node of the switch is coupled to a second node of the second resistor, and the second node of the switch is coupled to a reference ground. A third capacitor, wherein a first node of the third capacitor is coupled to a first node of the first resistor, and a second node of the third capacitor is coupled to a second node of the second resistor. A first transistor, the gate terminal of the first transistor being coupled to the second node of the first resistor, and the source terminal of the first transistor being coupled to the first node of the first resistor. The second transistor has its gate terminal coupled to the gate terminal of the first transistor, its source terminal coupled to the drain terminal of the first transistor, and its drain terminal coupled to the second node of the first capacitor. In response to operating the LC energy storage circuit for transmitting wireless energy, the switch arrangement is placed in the closed position and the first transistor and the second transistor are deactivated; and In response to operating the LC energy storage circuit to receive wireless energy, the switch arrangement is placed in the off position and the first transistor and the second transistor are activated.

Images