Capacitance in a wireless power apparatus

Abstract

This disclosure provides systems, methods and apparatuses for managing capacitance in a wireless power apparatus. The wireless power apparatus can be a type of Power Receiver or Power Transceiver that supports different power transfer modes associated with a variety of power levels such as watts (5W), 15W, or 25W, among other examples. In some aspects, a wireless power apparatus can manage the capacitance of the PRx tank circuit or PTx tank circuit based on one or more factors, such as the power transfer mode, the power level, power profile, a coupling factor, the power transfer direction, or a combination of multiple factors.

Description

CAPACITANCE IN A WIRELESS POWER APPARATUSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This International Application claims the benefit of priority India Provisional Patent Application No. 202411013129, filed February723, 2024, assigned to the assignee hereof, the disclosure of which is incorporated by reference.TECHNICAL FIELD

[0002] This disclosure relates generally to wireless power and some aspects relate to capacitance in a wireless power apparatus to support transmission and / or reception of wireless power at various power levels.DESCRIPTION OF RELATED TECHNOLOGY

[0003] A wireless power system includes a Power Transmitter (PTx) and a Power Receiver (PRx). Inductive coupling can enable wireless power transfer between a primary7coil of the Power Transmitter and a secondary coil of the Power Receiver. For magnetic inductive coupling, the primary coil of the Power Transmitter produces an electromagnetic field during a power state of the wireless power system. The electromagnetic field induces a voltage in the secondary coil of the Power Receiver when the secondary coil is present in the electromagnetic field. Some wireless power systems can accomplish the inductive coupling using resonant magnetic coupling at farther distances. Using either technique, the primary coil of the Power Transmitter can wirelessly transfer power to the secondary coil of the Power Receiver. The Power Receiver can provide the received power to operate a load. Example loads might include a motor, a heating element, electronics, or a power storage device, among other examples.

[0004] Wireless power technologies continue to evolve as manufacturers and consumers develop new capabilities. Consumers continue to adopt wireless power technology for new applications and deployment scenarios. For example, some advances in wireless power technology enable a wireless power apparatus to alternatively operate as a Power Transmitter or a Power Receiver. Meanwhile, engineers continue to develop techniques to increase the amount of power that can be transferred from a Power Transmitter to a Power Receiver. There is a desire to improve efficiency of wireless power transfer at various power levels and various transmission and / or reception modes.BRIEF SUMMARY

[0005] The systems, methods, and apparatuses of this disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

[0006] One aspect of this disclosure can be implemented as a wireless power apparatus. The wireless power apparatus includes a power transfer coil and a capacitance component capable of coupling different capacitance levels to the power transfer coil. The wireless power apparatus includes a controller to cause the capacitance component to couple a selected capacitance level from among the different capacitance levels based, at least in part, on a power transfer mode of the wireless power apparatus. For example, the power transfer mode can be based on different power transmission and / or reception levels, different wireless power profiles, operating frequencies, or other parameters.

[0007] Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0008] Like reference numbers and designations in the various drawings indicate like elements. Note that the relative dimensions of the figures may not be drawn to scale.

[0009] FIG. l is a block diagram of an example wireless power system.

[0010] FIG. 2A shows an example Power Transmitter.

[0011] FIG. 2B shows an example Power Receiver.

[0012] FIG. 3 shows a simplified diagram of the Power Transmitter and Power Receiver of FIG. 2A and FIG. 2B, respectively, in which capacitors are sized according to a traditional design.

[0013] FIG. 4 shows a simplified diagram of the Power Transmitter and Power Receiver in which capacitors are designed for capacitance tuning based on power level.

[0014] FIG. 5A shows the voltage gain through frequency domain analysis of the system of FIG. 3 operating in 1 Watt (W) power transfer mode.

[0015] FIG. 5B shows the plots derived from the time domain analysis of the system of FIG.3 operating in 15W power transfer mode.

[0016] FIG. 6A shows the voltage gain through frequency domain analysis of the system of FIG. 3 operating in 25W power transfer mode.

[0017] FIG. 6B shows the plots derived from the time domain analysis of the system of FIG.3 operating in 25W power transfer mode.

[0018] FIG. 7A shows the voltage gain through frequency domain analysis of the system of FIG. 4 operating in 25W power transfer mode.

[0019] FIG. 7B shows the plots derived from the time domain analysis of the system of FIG.4 operating in 25W power transfer mode.

[0020] FIG. 8 shows an example implementation in which a Power Transmitter performs a frequency sweep to determine an operating frequency for MPP.

[0021] FIG. 9A shows an example wireless power apparatus operating as a Power Receiver for a first power level, such as a baseline power profile (BPP) power transfer mode.

[0022] FIG. 9B shows the example wireless power apparatus operating as a Power Receiver for a second power level, such as a magnetic power profile (MPP) power transfer mode.

[0023] FIG. 9C shows the example wireless power apparatus operating as a Power Transmitter (sometimes referred to as a Power Transceiver) for a first power level, such as BPP power transfer mode.

[0024] FIG. 9D shows the example wireless power apparatus operating as a Power Transmitter (or Power Transceiver) for a second power level, such as MPP power transfer mode.

[0025] FIG. 10A shows an example diagram of tuning capacitors implemented as a default capacitor and switchable capacitors.

[0026] FIG. 10B shows an example diagram of tuning capacitors implemented as a capacitor bank.

[0027] FIG. 10C shows an example diagram of tuning capacitors implemented as a tunable capacitor.

[0028] FIG. 11 shows a system diagram in which an example Power Receiver operates as a Power Transmitter.

[0029] FIG. 12 shows the voltage gains through frequency domain analysis of the system of FIG. 11 using capacitance tuning at various power levels.

[0030] FIG. 13 illustrates a block diagram of an example apparatus for use in a wireless power system.DETAILED DESCRIPTION

[0031] The following description is directed to certain implementations for the purpose of describing innovative aspects of this disclosure. However, a person having ordinary skill in the art will readily recognize that the teachings herein can be applied in a multitude of different ways. The described implementations can be implemented in any means, apparatus, system, or method for transmitting or receiving wireless power.

[0032] As described above, a wireless power system includes a Power Transmitter (PTx) and a Power Receiver (PRx). A Power Transmitter also may be referred to as a wireless power transmission apparatus. A Power Receiver also may be referred to as a wireless power reception apparatus. A Power Receiver includes a secondary coil configured to wirelessly receive power via inductive coupling with a primary coil of the Power Transmitter. A wireless power standard can support different power levels (such as 5 Watts (5W), 15W, 25W, etc.) using different operating parameters. For example, a first wireless power mode (referred to as baseline power profile (BPP) mode) can support up to 5W wireless power transfer using an operating frequency in the range of 110 kilohertz (kHz) to 205 kHz (typically BPP mode has a nominal frequency of 128 kHz). A second wireless power transfer mode (referred to as magnetic power profile (MPP) mode) can operate at higher frequencies (such as 360 kHz) and can support higher power levels (such as 15W, or higher). In some implementations, an MPP mode can be used when a Power Receiver and a Power Transmitter both have magnets that can improve the alignment and coupling of the two devices. MPP mode currently supports up to 15W and may continue to increase as the MPP mode is further developed. It is desirable to support 2 W or higher using MPP mode.

[0033] In order to efficiently transfer wireless power between a Power Transmitter and a Power Receiver, one or both devices might adjust the capacitance of a tank circuit. A tank circuit in each wireless power apparatus includes a power transfer coil and other circuit components (such as capacitors, inductors, resistors, etc.). For example, the PRx tank circuit can include the secondary coil and one or more capacitors that are selectively enabled. Similarly, a PTx tank circuit includes a power transfer coil and one or more capacitors. As the BPP and MPP modes continue to evolve, there is a need for greater flexibility to implement different capacitance levels. For example, the higher power levels of the MPP mode cannot be achieved unless capacitance of the PRx tank circuit is reduced below traditional implementations for the existing input (PTx) and output voltage (PRx) designs of the devices. Meanwhile, there is a desire for the PRx tank circuit to maintain compatibility with lower pow er levels associated with BPP mode.

[0034] In addition to supporting different power levels, there is an interest in supporting new types of wireless power apparatuses. For example, an apparatus might include a first Power Receiver that is capable of operating as a Power Transmitter, such that the first Power Receiver can transmit wireless power to another Power Receiver. In this configuration, the first Power Receiver might be referred to as a Power Transceiver or any other term to distinguish it from a traditional single-capability Power Receiver or Power Transmitter. Other terms for a Power Transceiver might include a “power trans-receiver,” a wireless power transmit and receive unit (WPTRU), or Power Transmit-Receiver (PTRx), among other examples. A Power Transceiver can be any device that is capable of alternatively operating as a Power Receiver and a Power Transmitter. Current designs of a wireless power apparatus are inadequate to support the increasing variety of power levels (e.g., power transfer modes) and transmission / reception capabilities.

[0035] This disclosure provides systems, methods and apparatuses for managing capacitance in a wireless power apparatus. The wireless power apparatus can be a type of Power Receiver or Power Transceiver that supports different power transfer modes associated with a variety of power levels (such as BPP mode, MPP mode at 15W, or MPP mode at 25W, among other examples). For brevity, the phrases wireless power apparatus, Power Receiver, Power Transceiver, or “Power Receiver operating as a Power Transmitter” can be used interchangeably. In some aspects, a Power Receiver can manage the capacitance of the PRx tank circuit based on one or more factors, such as the power transfer mode, the power level, a coupling factor, the power transfer direction, or a combination of multiple factors. In some implementations, the PRx tank circuit has a minimum capacitance that is based on the amount of capacitance associated with a high power wireless power transmission or reception mode. Additional capacitance can be added using switches (or a capacitor bank or a tunable capacitor) based on the present operating state of the Power Receiver.

[0036] Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. A wireless power apparatus can support higher power transfer levels (such as 25W. 50W, or higher) which might not otherwise be possible with traditional capacitance levels. The higher power transfer levels can enable wireless fast charging of mobile devices, thus increasing user satisfaction and enjoyment. In some implementations, the disclosed techniques enable a wireless power apparatus (such as a mobile device, wireless power hub, or other appliance) to support both transmission and reception of wireless power at a variety of different power levels. For example, the wireless power apparatus can receive wireless power from a Power Transmitter and store power for a later time. At a later time, the wireless power apparatus can obtain thestored power and transmit wireless power (sometimes referred to as “reverse charging7’) to a Power Receiver.

[0037] FIG. 1 is a block diagram of an example wireless power system 100. The example wireless power system 100 includes a Power Transmitter 110 and a Power Receiver 130. The Power Transmitter 110 includes a power transfer coil 116 (sometimes referred to as a primary coil) and a PTx controller 120. The power transfer coil 116 may be associated with a Power Transmitter circuit 114 (sometimes also referred to as a power signal generator, or a driver circuit, or a driver). The power transfer coil 116 may be a wire coil which transmits wireless power (which also may be referred to as wireless energy). The power transfer coil 116 may transmit wireless energy using an inductive or a resonant magnetic field. The Power Transmitter circuit 114 may include components (not shown) to prepare the wireless power. For example, the Power Transmitter circuit 114 may include one or more switches, drivers, series capacitors, rectifiers, inverters, or other components. In some implementations, the Power Transmitter circuit 114 includes an inverter and a PTx resonant tank circuit (which can be referred to as a “tank circuit” for brevity ). The PTx controller 120 may be implemented as a microcontroller, dedicated processor, integrated circuit, application specific integrated circuit (ASIC) or any other suitable electronic device.

[0038] A power source 112 provides power to the power transmitter unit 118. In some implementations, the power source 112 may convert alternating current (AC) power to direct current (DC) power. For example, the power source 112 may include a converter that receives an AC power from an external power supply and converts the AC power to a DC power used by the Power Transmitter circuit 114. Alternatively, or additionally, a component (such as an inverter) of the Power Transmitter circuit 114 may convert the DC power to the AC power. The power source 112 may be integrated as part of the Power Transmitter 110 or may be external to the Power Transmitter 110. In some implementations, the Power Transmitter 110 causes the power source 112 to regulate the DC output voltage of the power source 112. For example, the PTx controller 120 can set DC voltage of the power source 112 based on information (such as a value indicating a requested power) received from the Power Receiver 130. The Power Transmitter 110 can receive power configuration information from the Power Receiver 130 and use the information to set a parameter (such as the DC output voltage of the power source 112). In some implementations, the Power Transmitter 110 includes a DC-DC converter (not shown) between the power source 112 and the Power Transmitter circuit 114 to control the variable DC output voltage.

[0039] The PTx controller 120 is connected to a communication interface 122. The communication interface 122 is connected to a first communication coil 124. In someimplementations, the communication interface 122 and the first communication coil 124 may be collectively referred to as a first communication unit. In some implementations, the first communication unit may support short-range radio frequency communication, such as NearField Communication (NFC) or Bluetooth (BT). NFC is a technology by which data transfer occurs on a carrier frequency of 13.56 Megahertz (MHz). The first communication unit also may support any suitable communication protocol. The first communication unit may contain modulation and demodulation circuits to wirelessly communicate via the first communication coil 124. Alternatively, or additionally, the PTx controller 120 may use frequency, amplitude, current, or voltage modulation of a wireless power signal to communicate via an in-band communication link (not shown) that includes the power transfer coil 116.

[0040] In the example of FIG. 1, an example apparatus 160 includes a Power Receiver 130 and other components (such as a converter 142, an energy storage unit 144, a load 162, a load controller 164, and / or a user interface 166). The Power Receiver 130 includes a power transfer coil 132 (sometimes referred to as a “secondary coil” to distinguish from the primary coil of a Power Transmitter), a PRx tank circuit 136 (or “tank circuit”), a bridge circuit 140, a PRx controller 146, and a communication interface 148. The converter 142 can operate as a buck or boost converter to alter the voltage of electricity being supplied to the energy storage unit 144 (when the Power Receiver 130 is being operated for power reception) or being drawn from the energy storage unit 144 (when the Power Receiver 130 is being for power transmission). In some implementations, the apparatus 160 also includes a load controller 164 and a user interface 166 (such as a button, switch, touchpad, indicator, touch screen, or wireless local area network interface). The bridge circuit 140 can be a rectifier. In some implementations, the bridge circuit 140 is capable of operating as a rectifier or an inverter, and may be implemented as an active bridge. The PRx tank circuit 136 can include a capacitor or other components to enable the secondary power transfer coil 132 to receive the wireless power 168 during the power state. Although not shown, a small capacitor can be used before the bridge circuit 140 and a load capacitance can be used after the bridge circuit 140 to match impedance and to filter a high frequency component of the rectifier voltage. In accordance with aspects of this disclosure, the PRx tank circuit 136 includes a capacitance component that can alter the capacitance of the PRx tank circuit 136 depending on different power levels, power transmission or reception modes, or power profile, among other examples.

[0041] Although shown as different components, some components may be packaged or implemented in the same hardware. For example, in some implementations, the PRx controller 146 and the load controller 164 may be implemented as a single controller. The PRx controller 146, the load controller 164, the communication interface 148, or anycombination thereof, may be implemented as a microcontroller, dedicated processor, integrated circuit, application specific integrated circuit (ASIC) or any other suitable electronic device. The communication interface 148 and the second communication coil 150 can be collectively referred to as a second communication unit. The second communication unit might also include a power harvester (not shown) that can harvest energy from the communication signals and provide harvested bias power to the PRx controller 146 or the load controller 164.

[0042] The PTx controller 120 may detect the presence or proximity of a Power Receiver 130. This detection may happen during a periodic pinging process of the communication interface 122. During the pinging process, the communication interface 122 supplies power to the communication interface 148 via communication signals 170 when the Power Receiver 130 is in proximity’ to the Power Transmitter 110. The communication interface 148 can send a reply signal back to the communication interface 122 to confirm that it is a Power Receiver. Prior to power transfer, a handshaking process may take place during which the PTx controller 120 may receive identification and configuration data, among other information, from the Power Receiver 130. The PTx controller 120 may control characteristics of wireless power it provides to the Power Receiver 130 based on the configuration data.

[0043] A PRx controller 146 may be operationally coupled to the bridge circuit 140 and the communication interface 148. The communication interface 148 may contain modulation and demodulation circuits to wirelessly communicate via the second communication coil 150. Thus, the PRx controller 146 may wirelessly communicate feedback information to the PTx controller 120 via the communication interface 148 to the communication interface 122 using short-range radio frequency communication, such as NFC. Alternatively, or additionally, the PRx controller 146 may use load modulation to communicate via an in-band communication link (not shown) that includes the power transfer coil 132.

[0044] A load controller 164 may be operationally coupled to the load 162 and the PRx controller 146 (or to the communication interface 148. coupling not shown in Fig. 2). The load controller 164 may detect changes to load states. The load controller 164 also may determine a load voltage reference and / or a power requirement of the load. The load controller 164 also may send load voltage references, load current, load power requirement and any other suitable information to the PRx controller 146 or the communication interface 148 for communication to the Power Transmitter 110. During a power state, the PRx controller 146 may additionally determine and provide one or more feedback information indicating a measured load voltage, load current, load power requirement, and power available to the load 162. In some feedback messages, the feedback information may include areference voltage indicating a required voltage for the load 162. In some feedback messages, the feedback information may indicate an error in the output voltage of the load 162. In some feedback messages, the feedback information may include the required power for the load. Although the PRx controller 146 and load controller 164 are shown separately, they may be included in the same component of the Power Receiver 130.

[0045] Some appliances are equipped with safety7features, such as a disconnect switch 134, that are operated in conjunction with the operating states. For example, the disconnect switch 134 might be maintained in an open position to prevent the flow of current to the load 162 when the Power Receiver 130 is in the pre-power states (such as a standby state, a discovery state, or and a connected state). Before transitioning to the powder state, the PRx controller 146 might cause the disconnect switch 134 to move to a closed position to enable the flow of current to the load 162. In an emergency condition (such as excessive voltage or current), the PRx controller 146 might open the disconnect switch 134 to prevent damage to the load 162 or other components of the Power Receiver 130 or the apparatus 160. After the disconnect switch 134 is closed, the PRx controller 146 can communicate a message to the PTx controller 120 to cause the wireless power system to transition to the power state. Alternatively, or additionally, the PRx controller 146 can communicate a power request to begin the transmission of the wireless power 168.

[0046] Aspects of this disclosure are related to capacitance levels in the PTx tank circuit (such as the Power Transmitter circuit 114) and / or the PRx tank circuit 136. The Power Transmitter 110 and the Power Receiver 130 may operate at different operating frequencies depending on the amount of wireless power 168. As an example, the PRx tank circuit 136 may include a capacitance component capable of coupling different capacitance levels to the power transfer coil 132. The PRx controller 146 may be configured to control the capacitance component. For example, the PRx controller 146 may cause the capacitance component to couple a selected capacitance level from among the different capacitance levels based, at least in part, on a power transfer mode (e.g., transmission or reception, first power profile or second power profile, etc.) of the apparatus 160. In some implementations, the power transfer mode is based on whether the Power Receiver 130 is presently configured for a first power profile (such as BPP) or a second power profile (such as MPP). This disclosure provides several example configuration for the capacitor component, such as those described with reference to FIG. 4, FIG. 10A, FIG. 10B, and FIG. 10C.

[0047] FIG. 2A shows a diagram 200 of an example Power Transmitter. A controller (not shown) such as the PTX controller 120 of FIG. 1 can control the pow er source 112 and the Power Transmitter circuit 114. For example, the controller can provide Vin control signal202 to the power source 112 to adjust the amount of power being supplied to the Power Transmitter circuit 114. The Power Transmitter circuit 114 can include an inverter (such as a plurality of switches) to adjust the frequency and AC voltage of the power signal being supplied to the power transfer coil 116. The controller can provide a phase control signal 204 to the inverter to control activation of the various switches. A PTx tank circuit 262 includes one or more capacitors (which are labeled as Ctxl 210, Ctx2 212, and Ctx3 214) that are coupled to the power transfer coil 116.

[0048] In FIG. 2A. the capacitance levels of the capacitors 210. 212, and 214 are based on a traditional design in which the Ctxl 210 is 68 nanoFarads (nF), the Ctx2 212 is 33 nF, and the Ctx3 214 is 390 nF. Notice that the Ctxl 210 is always connected such that the minimum capacitance of the PTx tank circuit is 68 nF. When a first switch (shown as Stl 220) is in the closed position (e.g., the switch is "on"), the total capacitance of Ctxl 210 (68 nF) and the Ctx2 212 (33 nF) is combined to cause the PTx tank circuit to have 101 nF. When both the first switch and a second switch (shown as St2 222) are closed, the capacitance (390 nF) is added to the PTx tank circuit to cause a total capacitance of 490 nF. Typically, during a digital ping (or any pre-power phase), the Stl 220 and the St2 222 are in the closed position so that all capacitance is coupled for an initial presumption that the Power Transmitter and Power Receiver (not shown) will use a BPP power transfer mode with low power (e.g., 5W). Upon a determination that both the Power Transmitter and the Power Receiver support a higher power transfer mode (e.g., MPP at 15W), the Power Transmitter can selectively open or close the switches Stl 220 and St2222 based on the degree of coupling between the Power Transmitter and the Power Receiver. For example, when there is a low degree of coupling, the Power Transmitter might open both the Stl 220 and the St2 222. As a result, the minimum capacitance that the Power Transmitter in FIG. 2A can support is 68 nF. As shown in FIG. 6A and FIG. 6B, the capacitance of 68 nF may prevent the Power Transmitter from actually transferring power at 25W. Thus, there is a need to reduce the amount of capacitance in the PTx tank circuit 262 or in the PRx tank circuit.

[0049] FIG. 2B shows a diagram 201 of an example Power Receiver 130 and an example load 230. The Power Receiver 130 includes the power transfer coil 132 coupled to a PRx tank circuit 264 and a bridge circuit 140. The PRx tank circuit 264 includes a plurality of capacitors, further described below. A small capacitor (shown as CD 244) might be coupled in parallel with the power transfer coil 132. In the example of FIG. 2B, the Power Receiver 130 is operating as a traditional Power Receiver such that the bridge circuit 140 provides a rectified voltage (Vrect) to the converter 142. The converter 142 supplies a DC voltage to the energy storage unit 144. In some implementations, an apparatus also includes a dumpload 260 (either as part of the example load 230 or the Power Receiver 130). The dump load 260 can consume a small amount of current (such as 50 milliamps (mA)), referred to as ballast current, during times when the load 230 load is under a “no load” or a very light load condition. The dump load 260 can ensure that a minimum current is drawn. For example, when the load 230 (or energy storage unit 144) is disconnected or drawing less than 50 mA, the dump load 260 can draw ballast current to round the total equivalent DC current up to 50 mA. When the load 230 (or energy storage unit 144) is connected and drawing more than 50 mA, ballast current is not effective or has negligible impact. As further described with reference to FIG. 9A to FIG. 9D, for a Power Receiver that also supports a wireless power transmission operation, the dump load 260 might be disabled or disconnected.

[0050] Returning to the PRx tank circuit 264, FIG. 2B shows capacitance levels of the capacitors (Crxl 240 and Crx2 242) are based on a traditional design in which the Crxl 240 is 174 nF and the Crx2 242 is 536 nF. The Crxl 240 is always connected such that the minimum capacitance of the PRx tank circuit 264 (in this design) is 174 nF). During a digital ping initially in BPP mode, the switch Sri 250 is open so that the capacitance is only 174 nF (based on the Crxl 240). When the Power Transmitter (not shown) and the Power Receiver both support MPP mode, the PRx controller (now shown) can cause the Sri 250 to close such that the total capacitance of the PRx tank circuit 264 is 710 nF. A first potential problem with the traditional design shown in FIG. 2B is that the minimum capacitance (Crxl 240, 174 nF) may not be suitable for a wireless power system where the degree of inductive coupling is low and the MPP 25W power transfer mode is used. Another potential problem with the traditional design shown in FIG. 2B is that the minimum capacitance (Crxl 240, 174 nF) may not support an MPP wireless power transmission operation (e.g., reverse charging) when the Power Receiver 130 is operated as a Power Transmitter (or Power Transceiver) to transmit power to a different Power Receiver.

[0051] FIG. 3 shows a simplified diagram 300 of the Power Transmitter and Powder Receiver of FIG. 2A and FIG. 2B, respectively , in which capacitors are sized according to a traditional design. FIG. 3 omits (for brevity) some elements of the Power Transmitter and the Power Receiver shown in FIG. 2A and FIG. 2B, respectively. However, the Power Transmitter and Power Receiver can include the elements described in FIG. 1, FIG. 2A, and FIG. 2B. For brevity7, the power source and inverter (Power Transmitter circuit 114) are collectively shown as an input voltage 302 on the Power Transmitter side. On the Power Receiver side, the diagram 300 focuses on the capacitance elements, while other elements (such as a bridge circuit, converter, etc.) are collectively shown as an example load 230.

[0052] FIG. 3 is provided to illustrate the capacitance levels of various capacitors in a traditional design of the Power Transmitter and the Power Receiver. Table 1 further lists these capacitance levels for reference.Table 1. Traditional capacitance levels

[0053] Initially the Power Transmitter and the Power Receiver may presume a BPP mode. In the BPP mode, the Stl 220 and St2 222 are closed (so that the PTX tank circuit has a total capacitance of 491 nF). In the BPP mode, the Sri 250 is open (so that the PRx tank circuit has a total capacitance of 174 nF).

[0054] After communicating capability information and determining coupling, the Power Transmitter and the Power Receiver can change to the MPP mode. In the MPP mode, when there is a high degree of coupling, the Stl 220 is closed making the PTx tank circuit capacitance 101 nF. In the MPP mode, when there is a low degree of coupling, the Stl 220 is open making the PTx tank circuit capacitance 68 nF. In a traditional implementation, for MPP, the Power Receiver closes Sri 250 making the PRx tank circuit capacitance 710 nF, regardless of the degree of coupling.

[0055] However, as shown in FIG. 5A through FIG. 6B, the minimum capacitance levels shown in FIG. 3 may not support 25W power transfer in the MPP mode. In this disclosure, the phrases "‘high coupling” or ‘"high degree of coupling” can refer to a system in which a measured coupling coefficient is greater than or equal to 0.81. The phrases “low coupling” or “low degree of coupling” can refer to a system in which a measured coupling coefficient is less than 0.81. A coupling coefficient (also sometimes referred to as a coupling factor) is a measured parameter that represents how well the Power Transmitter and Power Receiver are magnetically coupled and can vary based on alignment of their respective power transfer coils.

[0056] FIG. 4 shows a simplified diagram 400 of the Power Transmitter and Power Receiver in which capacitors are designed for capacitance turning based on power level. FIG. 4 is similar to the features of FIG. 3 except that the capacitance levels are different and the Power Receiver can support different capacitance levels. Table 2 lists the capacitance levels for reference.Table 2. New capacitance levels (first example)

[0057] In the example of FIG. 4, the Power Transmitter capacitors might be the same as previously described with reference to FIG. 3. However, Power Receiver might have different capacitance levels to better support the MPP high power (e.g., 25W) mode. The original CRxl (174 nF) has been split up to two capacitors (CRxl l 440 and Crxl2 444), having capacitance levels of 27 nF and 100 nF, respectively. The Crx2 442 is 583 nF. In the MPP mode (at 25W) with low coupling, the Power Receiver can open Sri 450 to make the total capacitance of the PRx tank circuit 127 nF. FIG. 7A and FIG. 7B show how the lower capacitance (compared to the lowest possible capacitance of FIG. 3) can improve operation at 25W MPP power transfer mode.

[0058] The example in Table 2 is based on an example implementation in which the capacitance levels on the Power Transmitter are unchanged from the traditional capacitance levels and the capacitance levels on the Power Receiver are changed. However, other example implementations are possible. For example. Table 3 shows a different example implementation in which the capacitance on the Power Transmitter might be changed.Table 3. New capacitance levels (second example)

[0059] Other examples are possible, such as reduced minimum capacitance on both the Power Receiver and the Power Transmitter. Furthermore, while the example in FIG. 4 is based on the Power Receiver having at least three capacitors, the number of capacitors can be increased to permit more capacitance level options.

[0060] FIG. 5A and FIG. 5B show the voltage gain through a frequency domain analysis 500 and plots derived from a time domain analysis 510, respectively, of the system of FIG. 3 operating in 15W power transfer mode using MPP. The frequency domain analysis 500 shows that at MPP the operating frequency is 360 kHz and the magnitude of the voltage gain is -0.73 decibels (dB) (shown at arrow 502). In this simulation, there was an 89% efficiency. The voltage input (voltage to the power transfer coil of the Power Transmitter) was 19 volts (V) at 15W. The voltage output at the power transfer coil of the Power Receiver was 17.4V. In particular, attention is brought to the PTx voltage signal in the time domain analysis 510showing that there is good margin for controlling the power transfer. Shown at arrow 512, the duration of the voltage changes on the PTx voltage signal shows the Power Transmitter still has margin available to increase or decrease duration of the voltage changes to control the amount of power being transferred. Since the load power is at 15W, the MPP mode is operating successfully using the traditional capacitance levels shown in FIG. 3. However, as shown in FIG. 6A and FIG. 6B, when MPP is changed to 25W mode, the traditional capacitance levels are not suitable to support the 25W power transfer.

[0061] FIG. 6A and FIG. 6B show the voltage gain through a frequency domain analysis 600 and plots derived from a time domain analysis 610, respectively, of the system of FIG. 3 operating in 25W power transfer mode using MPP. The frequency domain analysis 600 and time domain analysis 610 show that MPP systems using traditional capacitance levels cannot reach 25W power transfer without system modification. The frequency domain analysis 600 shows that at MPP 360 kHz operating frequency (shown at arrow 502), the magnitude of the voltage gain is now -2.58 dB (compared to -0.73 dB for 15W). The voltage input was 19 volts (V) at 25W. However, the voltage output at the power transfer coil of the Power Receiver was only 14. IV and the load power only reached approximately 20W (below the target 25W). Furthermore, when considering potential losses in the power transfer, phase shift control and dead time between switches, it is possible that even the 14V voltage output cannot be satisfied. Attention is brought to the PTx voltage signal in the time domain analysis 610 showing that there is little or no margin (shown at arrow 612) remaining for the Power Transmitter to increase the power transfer. In other words, the Power Transmitter has exhausted or reached saturation of the duty cycle in the PTx input voltage. Thus, FIG. 6A and FIG. 6B show that the traditional capacitance levels are not suitable to transfer 25W of power using MPP mode. This is because the minimum capacitance levels in the traditional designs do not enable sufficient gain to support the 25W power transfer.

[0062] FIG. 7A and FIG. 7B show the voltage gain through a frequency domain analysis 700 and plots derived from the time domain analysis 710, respectively, of the system of FIG. 4 operating in 25W power transfer mode using MPP. The frequency domain analysis 700 shows that at MPP 360 kHz operating frequency (shown at arrow 702). the magnitude of the voltage gain is -1.1 decibels (db). The voltage input of the Power Transmitter was 19V at 25 W. The voltage output at the power transfer coil of the Power Receiver was 14V. Attention is brought to the PTx voltage signal in the time domain analysis 710 showing that there is good margin for controlling the power transfer. Shown at arrow 712, the duration of the voltage changes on the PTx voltage signal show the Power Transmitter still has margin available to increase or decrease duration of the voltage changes to control the amount ofpower being transferred. Since the load power is at 25W. the MPP mode is operating successfully using the traditional capacitance levels shown in FIG. 4.

[0063] FIG. 8 shows an example implementation in which a Power Transmitter performs a frequency sweep to determine an operating frequency for MPP. The diagram 800 shows a Power Transmitter can perform a frequency sweep while the Power Receiver is present. The Power Receiver may have the dump load 260 (ballast load) connected during a frequency sweep as part of a test. The load 230 may be disconnected. In some implementations, as part of MPP mode, the Power Transmitter performs a test that includes the frequency sweep to detect a frequency that provides suitable or optimal gain to supply the desired power level (such as 25W). Although 360 kHz might be a traditional operating frequency for MPP mode, the Power Transmitter may determine that a different frequency (such as 310-320 kHz) provides better voltage gain.

[0064] In the example of FIG. 8, the PRx controller 146 connects the dump load 260. The PTx controller 120 uses a phase control signal 204 to adjust the operating frequency of the wireless power signal generated by the Power Transmitter circuit 114 (e.g., an inverter). In some aspects, the PRx controller 146 can measure a parameter (such as voltage, current, frequency, etc.) using a sensor (not shown) in the circuit that includes the dump load 260. The PRx controller 146 can communicate measurements to the PTx controller 120 (such as using communication signals 170 via the communication interfaces 148 and 122). The PTx controller 120 can use the reported measurements to calculate the gain at a plurality of different tested operating frequencies of the frequency sweep. In some aspects, the gain is calculated as GaindB= log10(yout / Vin) ■> where Vout is the voltage measured at the dump load 260 and Vin is the voltage supplied from the Power Transmitter circuit 114 to the PTx power transfer coil. In a frequency sweep, the Power Transmitter can test a plurality of step-wise operating frequencies or can gradually modify the operating frequencies based on a direction that increases the gain. In some implementations, the frequency modification can occur prior to a power transfer phase and / or prior to a power negotiation phase. Alternatively, or additionally, the Power Transmitter can continually modify the operating frequency during a power transfer phase to test a change in frequency and either accept the change if the calculated gain improves based on the change or revert the change if the calculated gain decreases based on the change.

[0065] In one aspect, a Power Transmitter includes a power transfer coil to transmit a wireless power signal to a Power Receiver. The Power Transmitter also includes an inverter to generate the wireless power signal. The Power Transmitter also includes a controller configured to cause the power transfer coil to transmit wireless power to the Power Receiverduring a frequency sweep test, operate the inverter at a plurality of different operating frequencies as part of the frequency sweep test, calculate voltage gains at the different operating frequencies, and select an operating frequency for the inverter based on the calculated voltage gains. The Power Transmitter may also include where the controller is configured to select the operating frequency based on which one of the different operating frequencies causes the highest voltage gain from among the calculated voltage gains. The Power Transmitter may also include where the controller is configured to extrapolate the calculated voltage gains for the different operating frequencies to estimate voltage gains at other operating frequencies, and select the operating frequency based on the estimated voltage gams at other operating frequencies. The Power Transmitter may also include further includes a communication unit configured to receive one or more communications from the Power Receiver during the frequency sweep test, the one or more communications indicating measured voltages for all or a subset of the different operating frequencies of the frequencysweep test, where the controller is configured to calculate the voltage gains based, at least in part on the measured voltages received from the Power Receiver and a measured input voltage generated by the inverter.

[0066] In FIG. 4, FIG. 7A and FIG. 7B, the possible changes to capacitance levels are described based on suitability- for higher power transfer (such as 25W or above). In addition to supporting higher power throughput, the choice of a lower minimum capacitance on the Power Receiver can also enable another feature, sometimes referred to as reverse charging. The Power Receiver can operate as a Power Transmitter. To do so, the Power Receiver should have a low enough minimum capacitance to match the traditional design of a Power Transmitter.

[0067] In addition to changing the capacitance levels of a Power Receiver, other modifications might be implemented. FIG. 9A through FIG. 9B show how operation of various components in a Power Receiver might change depending on the power transfer mode. Table 4 is provided as a reference to distinguish the various figures.Table 4. Overview of example power transfer modes

[0068] FIG. 9A shows an example wireless power apparatus in a first power transfer mode 900a. The apparatus is operating as a Power Receiver for a first power level, such as a BPP power transfer mode for wireless power reception. The capacitance 902a of the PRx tank circuit is 127 nF. The bridge circuit 904a operates as a rectifier providing 12V of rectified voltage (Vrect) to the converter 906a. The converter 906a is a buck converter to regulate the voltage to a proper level for the energy storage unit 144. The dump load 908 and bridge capacitor (Cd) are connected.

[0069] FIG. 9B shows the example wireless power apparatus in a second power transfer mode 900b. The apparatus is operating as a Power Receiver for a second power level, such as an MPP power transfer mode for wireless power reception at 15W. The capacitance 902b of the PRx tank circuit is 710 nF. The bridge circuit 904b operates as a rectifier providing 12V- 14V of rectified voltage (Vrect) to the converter 906b. The converter 806b is a buck converter to regulate the voltage to a proper level for the energy storage unit 144. The dump load 908 and bridge capacitor (Cd) are connected.

[0070] FIG. 9C shows the example wireless power apparatus in a third power transfer mode 900c. The apparatus is operating as a Power Transmitter (sometimes referred to as a Power Transceiver) for a first power level, such as BPP power transfer mode for wireless power transmission at 5W. The capacitance 902c of the PRx tank circuit is 127 nF. The bridge circuit 804c operates as an inverter providing an AC signal to the power transfer coil. In some implementations, the converter 906c is a boost converter to regulate the voltage from the energy storage unit 144 to a proper level for inverter. Alternatively, the converter 906c might be shorted or bypassed. For example, a bypass switch (not shown) might connect power from the energy storage unit 144 directly to bridge circuit 904c (inverter). In another implementation, one of the semiconductor switches of the converter 806d can be used for the bypass action. In the example of FIG. 9C, the dump load 908 and the bridge capacitor (Cd) are disconnected (shown at arrow 910 and 912, respectively).

[0071] FIG. 9D shows the example wireless power apparatus in a fourth power transfer mode 800d. The apparatus is operating as a Power Transmitter (or Power Transceiver) for a second power level, such as MPP power transfer mode for wireless power transmission at different power levels such as 5W, 15W or 25 W. The capacitance 902d of the PRx tank circuit is less than 127 nF. As an example, the capacitance is 27 nF (as described with reference to FIG. 4). The bridge circuit 904d operates as an inverter providing an AC signal to the power transfer coil. In some implementations, the converter 906d is a boost converter to regulate the voltage from the energy storage unit 144 to a proper level for inverter. In the example of FIG. 9D, the dump load 908 and the bridge capacitor (Cd) are disconnected (shown at arrow 910 and 912, respectively).

[0072] It should be clear that FIG. 9A through FIG. 9D can describe different operating modes (referred to as power transfer modes) of the same wireless power apparatus. Although the wireless power apparatus might be referred to as a Power Receiver, it can also include the elements and support the capacitance levels described in FIG. 9C and FIG. 9D so that the Power Receiver can also perform wireless power transmission. When configured for wireless power transmission, the Power Receiver might be referred to as a Power Transceiver or a Power Transmitter. In some aspects, the bridge circuit (such as bridge circuit 904a. 904b, 904c, and 904d) is implemented as an active bridge with switches controlled by a controller so that a same bridge circuit component can support both the rectifier operation and inverter operation depending on the power transfer mode.

[0073] In order to implement the various capacitance levels 902a, 902b, 902c and 902d, the wireless power apparatus includes a capacitance component. FIG. 10A through FIG. 10C describes some example capacitance components that might be used for various implementations of this disclosure.

[0074] FIG. 10A shows an example diagram 1000a of tuning capacitors implemented as a default capacitor and switchable capacitors. A default capacitor 1002 (labeled as CRxl l) might be a low capacitance needed to support the highest supported power level of the wireless power apparatus. For example, the default capacitor 1002 can be 27 nF if the wireless power apparatus expects to support 25W MPP power transmission mode. The additional capacitors (referred to as switchable capacitor 1004 and 1006) can be coupled in parallel and are controlled by switches that enable or disable the additional capacitance.

[0075] In other words, the capacitance component might include default capacitor 1002 that is always connected in the tank circuit to couple a first capacitance level that is a lowest capacitance from among different capacitance levels. The first capacitance level is based onthe highest amount of power that the wireless power apparatus can transmit through the power transfer coil. The one or more additional capacitors and corresponding switches are coupled in parallel to the first capacitor such that the one or more additional capacitors provide additional capacitance to support other ones of the different capacitance levels. The wireless power apparatus may also include where the first capacitance level is selected from a group consisting of 27 nF, 29 nF, 31 nF, and 40 nF.

[0076] FIG. 10B shows an example diagram 1000b of tuning capacitors implemented as a capacitor bank 1008. The capacitor bank 1008 can have a plurality of capacitors that can be switched in or out based on the desired capacitance level for a particular power transfer mode, power level, and degree of coupling. It should be understood that a capacitor bank can be used for impedance matching or gain, the capacitor bank 1008 described in this disclosure is designed to support different capacitance levels based on power transfer mode (such as directionality, power level, operating frequency, etc.).

[0077] FIG. 10C shows an example diagram 1000c of tuning capacitors implemented as a tunable capacitor 1010. The tunable capacitor 1010 (sometimes also referred to as a variable capacitor) supports different capacitance levels. For example, the tunable capacitor 1010 can be mechanically or electronically controlled to adjust capacitance of the capacitance component based on the power transfer mode.

[0078] FIG. 11 shows a system diagram 1100 in which an example Power Receiver 1104 operates as a Power Transmitter to transmit wireless power to another Power Receiver 1102. The Power Receiver 1104 (on the right side of FIG. 11) can be the same as described with reference to FIG. 4, FIG. 9C, or FIG. 9D. In this example, the Power Receiver 1104 has a low capacitance (such as 27 nF) in the default capacitor CRxl l so that the Power Receiver 1104 can support MPP power transmission mode at 25 W. The Power Receiver 1104 obtains powder from the energy storage unit 144 and uses a boost converter operation of the converter 142 to provide an input voltage to a bridge circuit (not shown) that operates as an inverter. On the left side of FIG. 11, another Power Receiver 1102 can receive wireless power and use it to power a load 162 (which might also include a battery in some implementations). Other features of the Power Receiver 1102, such as a rectifier, a converter, communication elements, and control elements, are omitted from FIG. 11 for brevity.

[0079] FIG. 12 shows the voltage gains through a frequency domain analysis 1200 of the system of FIG. 11 using capacitance tuning at various power levels. The first plot line 1202 shows the voltage gain when the Power Receiver 1104 uses tuning capacitors selected based on a 5W MPP power transmission mode. A second plot line 1204 shows the voltage gainwhen the Power Receiver 1104 uses tuning capacitors selected based on a 15W MPP power transmission mode. A third plot line 1206 shows the voltage gain when the Power Receiver 1104 uses tuning capacitors selected based on a 25 W MPP power transmission mode. The simulations show that even with a coupling factor of 0.7, by controlling the capacitance level of the capacitance component, the gain curves represented by plot lines 1202, 1204. and 1206 could be optimized for 360 kHz MPP operation.

[0080] FIG. 13 illustrates a block diagram of an example apparatus for use in a wireless power system. In some implementations, the apparatus 1300 may be a wireless power apparatus (such as any of the Power Transmitter, Power Receiver, or Power Transceiver described herein. The apparatus 1300 can include a processor 1302 (possibly including multiple processors, multiple cores, multiple nodes, or implementing multi -threading, etc.). The apparatus 1300 also can include a memory 1304. The memory’ 1304 may be system memory or any one or more of the possible realizations of computer-readable media described herein. The apparatus 1300 also can include a bus 1306 (such as PCI, ISA, PCI-Express, HyperTransport®, InfiniBand®, NuBus,® AHB, AXI, etc.).

[0081] The apparatus 1300 may include one or more controllers 1308 (such as a PTx controller). In some implementations, the controller 1308 can be distributed within the processor 1302, the memory’ 1304, and the bus 1306. The controller 1308 may perform some or all of the operations described herein. For example, the controller 1308 may implement the processes described with reference to any one of FIG. 1 through FIG. 12. or any combination thereof.

[0082] The memory 1304 can include computer instructions executable by the processor 1302 to implement the functionality of the implementations described herein. Any one of these functionalities may be partially (or entirely) implemented in hardware or on the processor 1302. For example, the functionality may be implemented with an application specific integrated circuit, in logic implemented in the processor 1302, in a co-processor on a peripheral device or card, etc. Further, realizations may include fewer or additional components not illustrated in FIG. 13. The processor 1302, the memory 1304, and the controller 1308 may be coupled to the bus 1306. Although illustrated as being coupled to the bus 1306, the memory 1304 may be coupled to the processor 1302 or the controller 1308.

[0083] The apparatus 1300 also includes a capacitance component 1310. The capacitance component 1310 is controlled by the controller 1308. For example, the capacitance component 1310 can be similar to any of the capacitance designs described with reference to FIG. 4, FIG. 9A. FIG. 9B, FIG. 9C, FIG. 9D, FIG. 10A, FIG. 10B, or FIG. 10C.

[0084] FIG. 1 through FIG. 13 and the operations described herein are examples meant to aid in understanding example implementations and should not be used to limit the potential implementations or limit the scope of the claims. Some implementations may perform additional operations, fewer operations, operations in parallel or in a different order, and some operations differently.

[0085] The foregoing disclosure provides illustration and description but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the aspects. While the aspects of the disclosure have been described in terms of various examples, any combination of aspects from any of the examples is also within the scope of the disclosure. The examples in this disclosure are provided for pedagogical purposes. Alternatively, or in addition to the other examples described herein, examples include any combination of the following enumerated example implementation options (referred to as clauses for clarity).

[0086] Clause 1 : A wireless power apparatus, comprising: a power transfer coil; a capacitance component capable of coupling different capacitance levels to the power transfer coil; and a controller to cause the capacitance component to couple a selected capacitance level from among the different capacitance levels based, at least in part, on a power transfer mode of the wireless power apparatus.

[0087] Clause 2: The wireless power apparatus of clause 1, wherein the power transfer mode is based on an amount of power being transferred through the power transfer coil.

[0088] Clause 3: The wireless power apparatus of clause 1 or 2, wherein the power transfer mode is further based on whether the wireless power apparatus is presently configured for a first power profile or a second power profile.

[0089] Clause 4: The wireless power apparatus of clause 3, wherein the first power profile is a baseline power profile (BPP) that supports power transmission up to 5 watts (5W), and wherein the second power profile is a magnetic power profile (MPP) that supports power transmission at 15W or greater.

[0090] Clause 5: The wireless power apparatus of any one of clauses 1 to 4, wherein the capacitance component includes: a first capacitor that is always connected to the power transfer coil to couple a first capacitance level that is a lowest capacitance from among the different capacitance levels, wherein the first capacitance level is based on a highest amount of power that the wireless power apparatus can transmit or receive through the power transfer coil; and one or more additional capacitors and corresponding switches coupled in parallel tothe first capacitor such that the one or more additional capacitors provide additional capacitance to support other ones of the different capacitance levels.

[0091] Clause 6: The wireless power apparatus of clause 5, wherein the first capacitance level is selected from a group consisting of 27 nanofarads (nf). 29 nF. 31 nF. and 40 nF.

[0092] Clause 7: The wireless power apparatus of any one of clauses 1 to 4, wherein the capacitance component includes a capacitor bank having a plurality of capacitors that can be switched in or out based on the selected capacitance level for the power transfer mode.

[0093] Clause 8: The wireless power apparatus of any one of clauses 1 to 4, wherein the capacitance component includes a tunable capacitor that supports the different capacitance levels.

[0094] Clause 9: The wireless power apparatus of any one of clauses 1 to 8, wherein the selected capacitance level is one of: less than 68 nanofarads (nf) when the power transfer mode is 25 watts (25 W) transmission mode; 127 nF when the power transfer mode is a 5W transmission or reception mode; or 710 nF when the power transfer mode is 15W reception mode.

[0095] Clause 10: The wireless power apparatus of any one of clauses 1 to 9, wherein the wireless power apparatus supports both wireless power reception and wireless power transmission, and wherein the power transfer mode is based on whether the wireless power apparatus is presently configured for the wireless power reception or the wireless power transmission.

[0096] Clause 11: The wireless power apparatus of any one of clauses 1 to 10, wherein the power transfer mode is one of: a first power reception mode for wireless power reception up to 5 watts (5W) using a baseline power profile (BPP); a second power reception mode for wireless power reception up to 15W using a magnetic power profile (MPP); a third power reception mode for wireless power reception up to 25W using the MPP; or a fourth power reception mode for wireless power reception over 25W using fast charging technology.

[0097] Clause 12: The wireless power apparatus of any one of clauses 1 to 10, wherein the power transfer mode is one of: a first power transmission mode for wireless power transmission up to 5 watts (5W) using a baseline power profile (BPP); a second power transmission mode for wireless power transmission up to 15 W using a magnetic power profile (MPP); a third power transmission mode for wireless power transmission up to 25W using the MPP; or a fourth power transmission mode for wireless power transmission over 25W using fast charging technology.

[0098] Clause 13: The wireless power apparatus of any one of clauses 1 to 10, wherein the wireless power apparatus supports both wireless power reception and wireless power transmission depending on the power transfer mode, and wherein the power transfer mode is one of: a first power reception mode for wireless power reception up to 5 watts (W) using a baseline power profile (BPP); a second power reception mode for wireless power reception up to 15W using a magnetic power profile (MPP): a third power reception mode for wireless power reception up to 25W using the MPP; a fourth power reception mode for wireless power reception over 25W using fast charging technology; a first power transmission mode for wireless power transmission up to 5W using the BPP; a second power transmission mode for wireless power transmission up to 15 W using the MPP; a third power transmission mode for wireless power transmission up to 25W using the MPP; or a fourth power transmission mode for wireless power transmission over 25W using fast charging technology.

[0099] Clause 14: The wireless power apparatus of any one of clauses 1 to 13, wherein the wireless power apparatus supports both wireless power reception and wireless power transmission depending on the power transfer mode, the wireless power apparatus further comprising: a bridge circuit capable of: operating as a rectifier when the power transfer mode is associated with wireless power reception, the rectifier receiving an alternating current (AC) wireless power signal from the power transfer coil and providing a direct current (DC) power signal to a load or an energy storage unit, and operating as an inverter when the power transfer mode is associated with wireless power transmission, the inverter receiving a DC power signal from the energy storage unit and providing an AC wireless power signal to the power transfer coil.

[0100] Clause 15: The wireless power apparatus of clause 14, further comprising: a converter coupled between the bridge circuit and the energy storage unit, wherein the converter is capable of: operating as a buck converter when the power transfer mode is associated with wireless power reception; and operating as a boost converter or bypass circuit when the power transfer mode is associated with wireless power transmission.

[0101] Clause 16: A Power Transmitter, comprising: a power transfer coil to transmit a wireless power signal to a Power Receiver; an inverter to generate the wireless power signal; and a controller configured to: cause the power transfer coil to transmit wireless power to the Power Receiver during a frequency sweep test, operate the inverter at a plurality of different operating frequencies as part of the frequency sweep test, calculate voltage gains at the different operating frequencies, and select an operating frequency for the inverter based on the calculated voltage gains.

[0102] Clause 17: The Power Transmitter of clause 16, wherein the controller is configured to select the operating frequency based on which one of the different operating frequencies causes the highest voltage gain from among the calculated voltage gains.

[0103] Clause 18: The Power Transmitter of clause 16, wherein the controller is configured to extrapolate the calculated voltage gains for the different operating frequencies to estimate voltage gains at other operating frequencies; and select the operating frequency based on the estimated voltage gains at other operating frequencies.

[0104] Clause 19: The Power Transmitter of any one of clauses 16 to 18, further comprising: a communication unit configured to receive one or more communications from the Power Receiver during the frequency sweep test, the one or more communications indicating measured voltages for all or a subset of the different operating frequencies of the frequency sweep test, wherein the controller is configured to calculate the voltage gains based, at least in part, on the measured voltages received from the Power Receiver and a measured input voltage generated by the inverter.

[0105] Clause 20: The Power Transmitter of any one of clauses 16 to 19, wherein the frequency sweep test is performed when the controller implements a first power profile rated for higher than 5 watts (5W), and wherein the selected operating frequency is different from a standard frequency for the first power profile.

[0106] Another innovative aspect of the subject matter described in this disclosure can be implemented as a computer-readable medium having stored therein instructions which, when executed by a processor, causes the processor to perform any one of the above-mentioned functionalities.

[0107] Another innovative aspect of the subject matter described in this disclosure can be implemented as a system having means for implementing any one of the above-mentioned functionalities.

[0108] Another innovative aspect of the subject matter described in this disclosure can be implemented as an apparatus having one or more processors configured to perform one or more operations from any one of the above-mentioned methods.

[0109] As used herein, a phrase referring to “at least one of’ or “one or more of’ a list of items refers to any combination of those items, including single members. For example, “at least one of: a, b, or c” is intended to cover the possibilities of: a only, b only, c only, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a and b and c.

[0110] The various illustrative components, logic, logical blocks, modules, circuits, operations and algorithm processes described in connection with the implementations disclosed herein may be implemented as electronic hardware, firmware, software, or combinations of hardware, firmware or software, including the structures disclosed in this specification and the structural equivalents thereof. The interchangeability of hardware, firmware and software has been described generally, in terms of functionality, and illustrated in the various illustrative components, blocks, modules, circuits and processes described above. Whether such functionality is implemented in hardware, firmware or software depends upon the particular application and design constraints imposed on the overall system. [OHl] The hardware and data processing apparatus used to implement the various illustrative components, logics, logical blocks, modules and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. A processor also may be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some implementations, particular processes, operations and methods may be performed by circuitry that is specific to a given function.

[0112] As described above, some aspects of the subject matter described in this specification can be implemented as software. For example, various functions of components disclosed herein, or various blocks or steps of a method, operation, process or algorithm disclosed herein can be implemented as one or more modules of one or more computer programs. Such computer programs can include non-transitory processor-executable or computer-executable instructions encoded on one or more tangible processor-readable or computer-readable storage media for execution by, or to control the operation of, a data processing apparatus including the components of the devices described herein. By way of example, and not limitation, such storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store program code in the form of instructions or data structures. Combinations of the above should also be included within the scope of storage media.

[0113] Various modifications to the implementations described in this disclosure may be readily apparent to persons having ordinary skill in the art, and the generic principles defined herein may be applied to other implementations without departing from the scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.

[0114] Additionally, various features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable subcombination. As such, although features may be described above as acting in particular combinations, and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

[0115] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one or more example processes in the form of a flowchart or flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or betw een any of the illustrated operations. In some circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

Claims

CLAIMSWhat is claimed is:

1. A first wireless power apparatus, comprising: a power transfer coil; a capacitance component capable of coupling different capacitance levels to the power transfer coil; and a controller to: determine a power transfer mode for wireless power transfer between the first wireless power apparatus and a second wireless powder apparatus, and cause the capacitance component to couple a particular capacitance level from among the different capacitance levels based, at least in part, on the power transfer mode.

2. The first wireless power apparatus of claim 1, wherein the controller is configured to: select the particular capacitance level based on the power transfer mode and a degree of coupling between the first wireless power apparatus and the second wireless power apparatus, wherein the particular capacitance level is: a lower capacitance when the degree of coupling is below a threshold, and a higher capacitance when the degree of coupling s greater than or equal to the threshold.

3. The first wireless power apparatus of claim 1 or 2, wherein the power transfer mode is based on a power level of the wireless power transfer, and wherein the power transfer mode includes at least: a first power transfer mode that supports power transfer up to 5 watts (W); a second powder transfer mode that supports power transfer at 15W; a third power transfer mode that supports power transfer up to 25 W; a fourth power transfer mode that supports power transfer over 25W.

4. The first wireless power apparatus of any one of claims 1 to 3, wherein the first wireless pow er apparatus is a Power Transmitter, and wherein the controller is configured to adjust the capacitance component to increase or decrease capacitance based on the power transfer mode and an input voltage of the Power Transmitter until the Power Transmitter has exhausted available input voltage at a low est capacitance.

5. The first wireless power apparatus of any one of claims 1 to 4. wherein the capacitance component includes: a first capacitor that is always connected to the power transfer coil to couple a first capacitance level that is a lowest capacitance from among the different capacitance levels, wherein the first capacitance level is based on a highest amount of power that the first wireless power apparatus can transmit or receive through the power transfer coil; and one or more additional capacitors and corresponding switches coupled in parallel to the first capacitor such that the one or more additional capacitors provide additional capacitance to support other ones of the different capacitance levels.

6. The first wireless power apparatus of any one of claims 1 to 5, wherein the capacitance component includes at least one of: a capacitor bank having a plurality of capacitors that can be switched in or out based on the particular capacitance level for the power transfer mode; or a tunable capacitor that supports the different capacitance levels.

7. The first wireless power apparatus of any one of claims 1 to 6, wherein the first wireless power apparatus supports both wireless power reception operation and wireless power transmission operation, and wherein the particular capacitance level is based on whether the first wireless power apparatus is presently configured for the wireless power reception operation or the wireless power transmission operation.

8. The first wireless power apparatus of claim 7, further comprising: a bridge circuit capable of: operating as a rectifier for the wireless power reception operation, and operating as an inverter for the wireless power transmission operation; a converter coupled to the bridge circuit, the converter capable of: operating as a buck converter for the wireless power reception operation; and operating as a boost converter or bypass circuit for the wireless power transmission operation; and the capacitance component capable of coupling the different capacitance levels for both the wireless power reception operation and the wireless power transmission operation.

9. The first wireless power apparatus of any one of claims 1 to 8. wherein the first wireless power apparatus is a Power Receiver, and the controller is configured to: initially set the capacitance component to an initial capacitance; andadjust the capacitance component to a lower capacitance, lower than the initial capacitance, based on a determination that the lower capacitance is needed for a high power transfer mode.

10. The first wireless power apparatus of claim 9. wherein: the initial capacitance is 710 nanofarads (nf), for a low power transfer mode between the Power Receiver and a Power Transmitter, the low power transfer mode supporting wireless power transfer up to 5 watts (5W); and the lower capacitance is lower than 710 nf, for the high power transfer mode supporting wireless power transfer above 5W when the Power Transmitter has exhausted an available PTx input voltage.

11. A method of a Power Receiver, comprising: initially setting a capacitance component to an initial capacitance, the capacitance component capable of coupling different capacitance levels to a power transfer coil of the Power Receiver; and adjusting the capacitance component to a lower capacitance, lower than the initial capacitance, based on a determination that the lower capacitance is needed for a wireless power reception operation to receive power from a Power Transmitter using a high power transfer mode.

12. The method of claim 11, wherein the initial capacitance is 710 nanofarads (nf), for a low power transfer mode between the Power Receiver and the Power Transmitter, the low power transfer mode supporting wireless power transfer up to 5 watts (5W); and the lower capacitance is lower than 710 nf, for the high power transfer mode supporting wireless power transfer above 5W when the Power Transmitter has exhausted an available PTx input voltage.

13. The method of claim 11 or 12, further comprising: operating the Power Receiver as a Power Transmitter for a wireless power transmission operation in which the Power Receiver transmits powers to another Power Receiver; and selecting a particular capacitance level, from among the different capacitance levels, based on a power level and a degree of coupling between the Power Transmitter and the other Power Receiver, wherein the particular capacitance level is: a lower capacitance when the degree of coupling is below a threshold, anda higher capacitance when the degree of coupling s greater than or equal to the threshold.

14. A wireless power transfer apparatus, comprising a power transfer coil; a capacitance component; and a controller to implement a method according to any one of claims 11 to 13.

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