Power control for overvoltage protection in a wireless power system

Abstract

This disclosure provides systems, methods and apparatuses for a power control in a wireless power system. The disclosed techniques enable a Power Transmitter to mitigate an overvoltage condition of the Power Receiver. In some aspects, the Power Transmitter adjusts an operating point of the wireless power signal based on a control error (CE) data packet from the Power Receiver. The Power Transmitter determines an average baseline power after processing the CE data packet. The Power Transmitter can further adjust the operating point before receiving the next CE data packet. In some aspects the Power Transmitter adjusts the operating point when an average measured power differs from the average baseline power. The Power Transmitter can adjust the operating point betw een instances of a periodic control error (CE) data packets to mitigate overvoltage conditions resulting from a sudden load change at the Power Receiver.

Description

POWER CONTROL FOR OVERVOLTAGE PROTECTION IN A WIRELESS POWERSYSTEMTECHNICAL FIELD

[0001] This disclosure relates generally to wireless power, and to overvoltage protection in a wireless power system.DESCRIPTION OF RELATED TECHNOLOGY

[0002] A wireless power system includes a Power Transmitter (PTx, sometimes also referred to as a wireless power transmission apparatus) and a Power Receiver (PRx, sometimes also referred to as a wireless power reception apparatus). The Power Transmitter includes a primary coil that produces an electromagnetic field during a power transfer phase to induce a voltage in a secondary coil of the Power Receiver when the secondary coil is placed in proximity to the primary coil. When the secondary coil is coupled to a rectifier, the induced voltage can generate power. Thus, the Power Transmitter can wirelessly transfer power to the Power Receiver. The power may be transferred using inductive coupling or resonant coupling between the primary' coil and the secondary coil. The Power Receiver can provide the generated power to operate a load (such as a motor, a heating element, electronics, or a power storage device, among other examples).

[0003] During the power transfer phase, the Power Transmitter controls the operating point of a wireless power signal. In a traditional wireless power system, the Power Transmitter controls the operating point based on feedback information (such as a control error value) from the Power Receiver. The operating point might include a voltage, frequency, phase, or other parameters of the wireless power signal. The Power Receiver periodically communicates the feedback information in a control error data packet (CE data packet). Each CE data packet may include control error value that causes the Power Transmitter to modify an amount of pow er, current, voltage, or another parameter of the operating point. CE data packets are communicated during communication periods based on a communication protocol for the wireless power system. There is an inherent delay between each CE data packet based on timing of the communication periods. As wireless power systems are used to transfer higher power levels, the delay between CE data packets could result in an overvoltage condition occurring during the delay. The timing for communication periods might be too slow or the control error value provided too infrequently to enable the Power Receiver to communicate about load changes or power requirements. Additionally, because higher powerwireless power systems can experience large changes in load power requirements, there is a potential for overvoltage conditions to occur in the time between the CE data packets.BRIEF SUMMARY

[0004] 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.

[0005] In one aspect, a method performed by a Power Transmitter, includes transmitting a wireless power signal to a Power Receiver, receiving a first control error value from the Power Receiver, adjusting an operating point of the wireless power signal based on the first control error value, determining an average baseline power (Pbaseiine) of the wireless power signal during a Pbaseiine measurement period after said adjusting the operating point, calculating a average calculated power (P calculated) of the wireless power signal during at least one P calculated measurement period after the Pbaseiine measurement period and before receiving a second control error value from the Power Receiver, and controlling the operating point based, at least in part, on a difference between the Pbaseiine and the Pcakuiated.

[0006] In one aspect, a method performed by a Power Transmitter, includes transmitting a wireless power signal to a Power Receiver, adjusting an operating point of the wireless power signal based on periodic control error (CE) data packets received from the Power Receiver, the periodic CE data packets including at least a first CE data packet and a second CE data packet, mitigating an overvoltage condition of the Power Receiver when a load of the Power Receiver changes during the control error interval (tintervai) between the first CE data packet and the second CE data packet, where mitigating the overvoltage condition includes adjusting the operating point based on a difference between a baseline power (Pbaseiine) of the wireless power signal based on first measurements at the Power Transmitter after the first CE data packet, and a calculated power (Pcaicuiated) of the wireless power signal based on second measurements at the Power Transmitter after the Pbaseiine.

[0007] In one aspect, a method performed by a Power Receiver, includes communicating power configuration information to the Power Transmitter, the power configuration information enabling overvoltage protection for a load of the Power Receiver, receiving a wireless power signal from the Power Transmitter, and periodically communicating control error values to the Power Transmitter during a power transfer phase.

[0008] 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. Otherfeatures, aspects, and advantages will become apparent from the description, the drawings, and the claims.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0009] Like reference numbers and designations in the various drawings indicate like elements. To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced. Note that the relative dimensions of the figures may not be drawn to scale.

[0010] FIG. 1 is a block diagram of an example wireless power system that includes an example Power Transmitter and an example Power Receiver.

[0011] FIG. 2A illustrates an example direct current (DC) voltage of a Power Transmitter in which the DC voltage varies in a proportional manner depending on the power required by a Power Receiver.

[0012] FIG. 2B illustrates an example direct current (DC) voltage of a Power Transmitter in which the DC voltage varies in a step manner depending on the power required be a Power Receiver.

[0013] FIG. 3 illustrates a message flow diagram of an example wireless power transmission process.

[0014] FIG. 4 illustrates an example of a control loop performed between a Power Transmitter and a Power Receiver.

[0015] FIG. 5 illustrates a conceptually illustrating a controller for a Power Transmitter to control an operating point according to some aspects of this disclosure.

[0016] FIG. 6 is a timing diagram showing power control according to some aspects of this disclosure.

[0017] FIG. 7A illustrates electrical parameters of a wireless power system using a traditional controller absent the techniques of this disclosure.

[0018] FIG. 7B illustrates electrical parameters of a wireless power system using a power controller with overvoltage protection according to some aspects of this disclosure.

[0019] FIG. 8 is a flow diagram illustrating example operations of a process for power control by a Power Transmitter.

[0020] FIG. 9 is a flow diagram illustrating example operations of another process for power control.

[0021] FIG. 10 is a flow diagram illustrating example operations of a process for overvoltage protection.

[0022] FIG. 11 is a flow diagram illustrating example operations of a process of a Power Receiver.

[0023] FIG. 12 depicts a conceptual diagram of an example message for communicating power configuration information according to some aspects of this disclosure.

[0024] FIG. 13 is a block diagram of an example apparatus for use in a wireless power system.DETAILED DESCRIPTION

[0025] 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.

[0026] A wireless power system may include a Power Transmitter (sometimes referred to as a Power Transmitter, or PTx) integrated with or otherwise disposed on an interface surface of the Power Transmitter. The wireless power system also may include a Power Receiver (sometimes referred to as a Power Receiver, or PRx). The Power Transmitter may include a primary coil configured to wirelessly transmit power via a magnetic field to a secondary coil in the Power Receiver. In some implementations, the Power Transmitter may include a countertop-mounted primary coil or a primary coil that is embedded or manufactured in a surface on which a cordless appliance can be placed. The cordless appliance may include a Power Receiver for wirelessly receiving power. A secondary coil of the Power Receiver may obtain wireless energy from the magnetic field and provide it to a power receiving circuit. The power receiving circuit may convert the energy and utilize it to charge or power a load. A Power Receiver may be included or integrated with a cordless appliance having a variable load (such as a blender, heating element, a fan, among other examples).

[0027] During a power transfer phase, the Power Receiver may communicate feedback information to the Power Transmitter via a communication channel. The Power Receiver may communicate the feedback information during communication periods. The power feedback information may indicate presence or status, among other examples. For example, the feedback information may include a power request, a null communication (to indicate presence without feedback), or Power Receiver feedback. For example, the Power Transmitter and the Power Receiver may communicate via Near-Field Communication(NFC). BluetoothTM. or other communications techniques. A transfer of wireless power may be controlled by some types of feedback information such as a control error data packet (CE data packet) or a power control packet from the Power Receiver to the Power Transmitter. Each CE data packet includes a control error value (such as a voltage error (V error). The control error value can be referred to as feedback information or control information. While examples in this disclosure are based on delay between CE data packets, the same techniques are applicable for delays between other types of power control information, such as power control packets or received power packets.

[0028] The Power Transmitter periodically adjusts an operating point (such as voltage or current) of the wireless power signal based on the feedback information from the Power Receiver. For example, the Power Transmitter can adjust the operating point based on a control error value in a CE data packet. A power controller can implement part of a control loop in which the Power Receiver periodically communicates control error values that can cause the Power Transmitter to adjust the operating point. However, the control error values are communicated during communication periods according to a communication protocol. In some implementations, each communication period occurs after a communication silent period (tsiient) that follows the end of a previous power control packet. In some implementations, the CE data packets are communicated according to a control error interval (tintcrval). A Power Receiver is expected to send CE data packets throughout the power transfer phase. The tintervai represents a time interval between the starts of consecutive CE data packets. The tintervai does not need to be constant and may vary within limits defined by the communication protocol. For example, the tintervai might vary in a range between 0 milliseconds (ms) and 700 ms. In some implementations, the target tintervai is approximately 250 ms.

[0029] As wireless power systems evolve to increase power levels, the periodic CE data packets may be insufficient to quickly adjust the operating point due to delay or communication inefficiency. For example, a Power Receiver could have a large change in load power requirement (such as from 300 watts (W) to 0W or 5W). The load change can result in a very high instantaneous overvoltage on the Power Receiver circuits or could damage the Power Receiver. To mitigate overvoltage, some Power Receivers might include a load capacitance. The load capacitance can slow down the raise of overvoltage; however the added load capacitance might take additional space or add expense to the Power Receiver. As Power Receiver manufacturers are free to choose the load capacitance based on load power, cost, and space constraints, the time during which the voltage in the Power Receiverrises from nominal to an allowable overvoltage condition depends on the load thrown level and the size of load capacitance.

[0030] This disclosure provides systems, methods and apparatuses for power control in a wireless power system. The described power control enables a Power Transmitter to mitigate an overvoltage condition of the Power Receiver. In some implementations, the Power Transmitter monitors changes in power at the Power Transmitter circuit and adjusts the operating point when an average measured power is different from a baseline power established by the traditional control loop. The Power Transmitter can adjust the operating point of the wireless power signal more frequently than would otherwise occur using only periodic CE data packets. For example, the Power Transmitter can adjust the operating point to mitigate an overvoltage condition that would otherwise occur between CE data packets.

[0031] The Power Transmitter determines a baseline power (Pbaseiine) of the wireless power signal. For example, the Pbaseiine can be calculated after adjusting the operating point using a control error value. The Pbaseiine is based on first measurements (such as voltage and current measurements) at the Power Transmitter during a Pbaseiine measurement period. The first measurements might be obtained from a direct current (DC) input to a power driver or at a tank circuit of the Power Transmitter. The Power Transmitter can average the first measurements over a power averaging time (such as 0.5 ms, 1 ms, or 2 ms, as examples). A first instance of the power averaging time following a change in operating point may be referred to as the Pbaseiine measurement period (or baseline measurement period) because the Pbaseiine is determined during the first instance of the power averaging time. The Power Transmitter can determine the power averaging time based on its own operating parameters, parameters received from the Power Receiver, or a combination thereof. After determining the Pbaseiine, the Power Transmitter periodically calculates an average calculated power (Pcaicuiated) based on an average of subsequent measurements (referred to as second measurements) at the Power Transmitter. Similar to the first measurements, the second measurements might include voltage and current measurements at a DC input or at a tank circuit of the Power Transmitter. Each instance of the Pcaicuiated may be determined over a power averaging time referred to as a Pcaicuiated measurement period. In some implementations, the durations of the Pbaseiine measurement period and each of the Pcaicuiated measurement period may be the same duration based on the power averaging time. In some implementations, the Pcaicuiated can be referred to as a measured power (Pmeasured), an average power (Paverage), or an actual power (Pactual). The Power Transmitter can calculate a power error value (Perror) based on a difference between the Pbaseiine and the Pcaicuiated. In some implementations, the power controller can use similar operating point calculations (such as aproportional-integral-derivative (PID) algorithm) that is used with a control error value. For example, the Power Transmitter can use the power error value to adjust a reference current that is used for the PID algorithm.

[0032] In some implementations, the Power Receiver can send additional information (which may be referred to as power configuration information) to the Power Transmitter during a configuration phase or negotiation phase to assist the Power Transmitter in determining an operating point, power control settings, or both. For example, the power configuration information might include a value of load capacitance used in the Power Receiver, a rated load voltage, an allowable overvoltage level, a time taken to reach an allowable overvoltage condition from a rated nominal voltage condition when the load is thrown from a full load to no load, a power averaging time for the Power Transmitter to use in calculating the Pbaseiine or Pcakuiated, or any combination of the above-mentioned information. The Power Transmitter can use the power configuration information to determine at least one of the speed, duration, and intervals at which averaging of the Pcakuiated needs to be carried out in order to detect a change in power before the overvoltage condition. Additionally, or alternatively, the Power Receiver can communicate a suggested power averaging time based on empirical test results using the Power Receiver with a standard Power Transmitter in a test environment.

[0033] Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. A Power Transmitter can control the operating point of a wireless power signal more frequently than the tintervai associated with CE data packets. The Power Transmitter can adjust the operating point based on measurements at the Power Transmitter between the CE data packets, sometimes without the need to receive measurement information from the Power Receiver. By utilizing the disclosed power control, a Power Transmitter can be responsive to feedback information (such as CE data packets) from the Power Receiver while also mitigating overvoltage conditions that would otherwise occur between CE data packets. The described power control can enable wireless power system to support battery charging applications of a Power Receiver or applications of a Power Receiver in which the load is power by the wireless power without a battery.

[0034] FIG. 1 is a block diagram of an example wireless power system 100 that includes an example Power Transmitter 102 and an example Power Receiver 1 18. In FIG. 1, dashed lines represent communications to distinguish from solid lines that represent electrical circuit lines.

[0035] The Power Transmiter 102 includes a primary coil 104 and a transmission (TX) controller 108. The primary coil 104 may be associated with a power transmitter circuit 106 (sometimes also referred to as a power signal generator or a driver circuit). The primary coil 104 may be a wire coil which transmits wireless power (which also may be referred to as wireless energy). The primary coil 104 may transmit wireless energy using inductive or magnetic resonant field. The power transmitter circuit 106 may include components (not shown) to prepare the wireless power. For example, the power transmitter circuit 106 may include one or more switches, drivers, series capacitors, rectifiers, inverters, or other components. In some implementations, the power transmitter circuit 106, PTX controller 108 and other components (not shown) may be collectively referred to as a power transmitter unit 110. Some or all of the power transmitter unit 110 may be embodied as an integrated circuit (IC) that implements features of this disclosure for controlling and transmitting wireless power to one or more wireless power reception apparatuses. The PTX controller 108 may be implemented as a microcontroller, dedicated processor, integrated circuit, application specific integrated circuit (ASIC) or any other suitable electronic device.

[0036] A power source 112 provides power to the power transmitter unit 110. 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 powder to a DC powder used by the power transmitter circuit 106. Alternatively, or additionally, a component (such as an inverter) of the power transmitter circuit 106 may convert the DC power to the AC power. The power source 112 may be integrated as part of the Power Transmitter 102 or may be external to the Power Transmitter 102.

[0037] In some implementations, the Power Transmitter 102 causes the power source 112 to regulate the DC output voltage of the power source 112. For example, the powder source 112 can regulate the DC output voltage to different levels based on the power delivered (such as the Pipeline determined by the Power Transmitter) to the Power Receiver 118 or the rated power of the Power Receiver 118. In some implementations, the PTX controller 108 can set DC voltage of the power source 112 based on information (such as a required power) received from the Power Receiver 118. The DC output voltage can vary proportionally to power delivered to the Pow er Receiver 118 as shown in FIG. 2A. In other implementations, the DC output voltage can be varied in a step manner to maintain the same value for a range of pow er delivered to the Power Receiver 118 as shown in FIG. 2B. The 102 can regulate the DC output voltage level of the power source 112 to maximize the overall efficiency of the wireless power system 100. The Power Transmitter 102 can receive power configuration information fromthe Power Receiver 118 and use the information to set a parameter (such as the DC output voltage of the power source 112). The Power Transmitter 102 can receive the power configuration information during various operating phases, such as the configuration phase or power transfer phase. In some implementations, the Power Transmitter 102 includes a DC- DC converter (not shown) between the power source 112 and the Power Transmitter circuit 106 to control the variable DC output voltage .

[0038] The PTX controller 108 is connected to a first communication interface 114. The first communication interface 114 is connected to a first communication coil 116. In some implementations, the first communication interface 114 and the first communication coil 116 may be collectively referred to as the first communication unit 122. In some implementations, the first communication unit 122 may support Near-Field Communication (NFC). NFC is a technology by which data transfer occurs on a carrier frequency of 13.56 Megahertz (MHz). In some implementations, the first communication unit 122 may support Bluetooth (BT) communications. The first communication unit 122 also may support any suitable communication protocol. The first communication unit 122 may contain modulation and demodulation circuits to wirelessly communicate via the first communication coil 116. Alternatively, or additionally, the TX controller 108 may use frequency modulation to communicate via an in-band communication link (not shown) that includes the primary coil 104.

[0039] The Power Receiver 118 may include a secondary coil 120, a rectifier 124, a receiver (RX) controller 126, a second communication interface 130, a load controller 134, a load 128, and a memory (not shown). In some implementations, the load 128 can include a drive (not shown) for controlling at least one parameter such as charging current, speed, or torque of the load. In some implementations, the rectifier 124 may be omitted. In some implementations, a series switch (not shown) may be included in series with the secondary coil 120 or in series between the rectifier 124 and the load 128. Although not shown, a load capacitance can be used after the rectifier 124 to reduce the rate of rise of load voltage that would otherwise occur when the load 128 suddenly reduces power consumption. Although shown as different components, some components may be packaged or implemented in the same hardware. For example, in some implementations, the RX controller 126 and the load controller 134 may be implemented as a single controller. The RX controller 126, the load controller 134, or any combination thereof, may be implemented as a microcontroller, dedicated processor, integrated circuit, application specific integrated circuit (ASIC) or any other suitable electronic device.

[0040] The PTX controller 108 may detect the presence or proximity of a Power Receiver 118. This detection may happen during a periodic pinging process of the first communication interface 114. During the pinging process, the first communication interface 114 also may supply power to the second communication interface 130 when the Power Receiver 118 is in proximity of the Power Transmitter 102. The second communication interface 130 may ■‘wake up” and power-up the RX controller 126 and may send a reply signal back to the first communication interface 114. Prior to power transfer, a handshaking process may take place during which the PTX controller 108 may receive configuration data related to the power rating of the receiver, among other information. The PTX controller 108 may control characteristics of wireless power it provides to the Power Receiver 118 based on the configuration data.

[0041] An RX controller 126 may be operationally coupled to the rectifier 124 and the second communication interface 130. The second communication interface 130 may contain modulation and demodulation circuits to wirelessly communicate via the second communication coil 132. Thus, the RX controller 126 may wirelessly communicate feedback information to the PTX controller 108 via the second communication interface 130 to the first communication interface 114 using NFC communications. Alternatively, or additionally, the RX controller 126 may use load modulation to communicate via an in-band communication link (not shown) that includes the secondary' coil 120.

[0042] A load controller 134 may be operationally coupled to the load 128 and the second communication interface 130. The load controller 134 may detect changes to load states such as change in charging currents in a battery charging application. . The load controller 134 also may determine a load voltage reference. The load controller 134 also may load voltage references, load current, and any other suitable information to the RX controller 126 or the second communication interface 130 for communication to the Power Transmitter 102. The RX controller 126 may additionally determine and provide feedback information indicating a measured load voltage available to the load 128. In some feedback messages, the feedback information may include a reference voltage indicating a required voltage for the load 128. In some feedback messages, the feedback information may indicate an error in the output voltage of the load 128. In some feedback messages, the feedback information may include the required power for the load. Although the RX controller 126 and load controller 134 are shown separately, they may be included in the same component of the Power Receiver 118.

[0043] The Power Transmitter 102 controls an operating point of the Power Transmitter circuit 106 using a control loop and a control algorithm as described further with reference to FIG. 4 and FIG. 5. When the PTX controller 108 receives a control error value from thePower Receiver 118, the PTX controller 108 calculates a reference current (Reference) using the control error value. The PTX controller 108 also obtains a measured current (Imeasured) using sensors (not shown), where the Imeasured is a current at the Power Transmitter circuit 106. The PTX controller 108 uses the Reference, the Imeasured, and the control algorithm to calculate an operating point for the Power Transmitter circuit 106. The operating point can be a voltage (also referred to as operating voltage), a current (also referred to as an operating current), a duty cycle, a phase shift, or other parameter which controls the how the Power Transmitter circuit 106 drives the wireless power signal to the primary coil 104.

[0044] Additionally, in accordance with aspects of this disclosure, the PTX controller 108 can adjust the operating point based on a change in transferred power, where the change after a first CE data packet and before a second CE data packet. The PTX controller 108 can determine a Pbaseiine based on first measurements during a Pbaseiine measurement period after adjusting the operating point in response to the first CE data packet. Then, the PTX controller 108 can calculate a Pcaicuiated based on second measurements during a Pcaicuiated measurement period after the Pbaseiine measurement period. If the Pcaicuiated deviates from the Pb as eline by a threshold amount, the change might be the result of a load change at the Power Receiver. The PTX controller 108 can adjust the operating point in response to the change without waiting for the next CE data packet or power control packet to report the change.

[0045] FIG. 2A illustrates an example direct current (DC) voltage of a Power Transmitter in which the DC voltage varies in a proportional manner depending on the power required by a Power Receiver. A first chart 200a shows the DC output voltage of a power source in the Power Transmitter. The DC output voltage can increase as a proportional variable to achieve an increase in power delivered to the Power Receiver. In some implementations, the Power Receiver communicates a power requirement to the Power Transmitter. In some implementations, the Power Transmitter can measure the transmitted power. The Power Transmitter sets the DC output voltage in the power source based on a calculation proportional to the power requirement or the transmitted power.

[0046] FIG. 2B illustrates an example direct current (DC) voltage of a Power Transmitter in which the DC voltage varies in a step manner depending on the power required be a Power Receiver. In one implementation, the DC voltage may be varied in a step manner depending on the power transmitted by the Power Transmitter. A second chart 200b shows the DC output voltage of a power source in the Power Transmitter based on the power requirement of the Power Receiver. The DC output voltage might have steps at different DC output voltage levels to achieve different ranges of power delivered to the Power Receiver. In some implementations, the Power Transmitter receives a communication from the Power Receiverrequesting an amount of power or a power requirement. The Power Transmitter determines which range includes the requested amount of power or the power requirement. The Power Transmitter sets the DC output voltage in the power source to a DC output voltage level that corresponds to the determined range.

[0047] FIG. 3 illustrates a message flow diagram of an example wireless power transmission process. Referring to FIG. 3, a Power Transmitter 102 detects that a Power Receiver 118 is located in a charging area in a standby mode (block 302). There may be various methods for detecting the Power Receiver 118 by the Power Transmitter 102. and not limited to a specific method in the present disclosure. As an example, the Power Transmitter 102 may detect that the Power Receiver 118 is located in a charging area by periodically emitting analog ping of a specific frequency, and based on detection current for this, resonance shift or capacitance change. As another example, the Power Transmitter 102 may periodically transmit a detection signal and the Power Receiver 118 may transmit a response signal (for example, a CE data packet or a signal strength packet). The Power Transmitter 102 may detect that the Power Receiver 118 is located in the charging area based on receiving the response signal within a predetermined time period following the detection signal. As yet another example, the Power Receiver 118 may transmit a searching signal or an advertisement signal to the Power Transmitter 102. The searching signal or the advertisement signal may traditionally be transmitted using short range radio frequency communication (such as Bluetooth™). The Power Transmitter 102 may detect the Power Receiver 118 based on reception of the searching signal or the advertisement signal.

[0048] In some implementations, in preparation for a wireless power transmission, the Power Transmitter 102 may optionally transmit an information request signal 304 to the Power Receiver 118. The information request signal 304 may be a signal for requesting an ID and power information of the Power Receiver 118. As an example, the information request signal 304 may be transmitted in the form of a data packet message. As another example, the information request signal 304 may be transmitted in the form of digital ping according to a predefined standard between the Power Transmitter 102 and the Power Receiver 118. In response to the information request signal 304, the Power Receiver 118 may optionally transmit the ID and configuration information 306 to the Power Transmitter 102. For example, the configuration information may include a nominal power or a maximum amount of power that is needed by the Power Receiver 118. In some implementations, the ID and configuration information 306 can also include power configuration information to assist the Power Transmitter 102 in setting a duration of the Pbaseiine measurement period and the Pcaicuiatcd measurement periods, a threshold for overvoltage protection, or other parameters ofthe power controller. In some implementations, the information request signal 304 and the ID and configuration information 306 may be communicated using out-of-band communication (separate from the wireless power signal) such as NFC or Bluetooth.

[0049] Based on the ID and configuration information 306, the Power Transmitter 102 configures parameters (referred to as an operating point) for power transmission and performs a wireless power transmission 308 to the Power Receiver 118. For example, the Power Transmitter 102 may create a power transmission contract based on the ID and the configuration information and may control the wireless power transmission 308 according to the power transmission contract. The process, performed by the Power Transmitter 102, from the start to the end of the wireless pow er transmission 308 to the Power Receiver 118 may be called a (wireless) power transfer phase 314. The Power Receiver 118 may provide the received wireless power to an external load such as a battery.

[0050] During the power transfer phase 314, the Power Receiver 118 transmits a CE data packet (such as (CE data packets 310a, 310b, 310c) periodically or aperiodically to the Pow er Transmitter 102. After each CE data packet, the Power Transmitter 102 might perform the control process as described with reference to FIG. 5. The CE data packets are communicated during communication periods. In some implementations, the communication periods occur during periodic intervals that are allocated for communication. For example, each communication period might begin within a time interval (such as control error interval tintervai) after the start of a previous CE data packet. The tintervai might vary in a range from 0 ms to 700 ms (with a specified target of 250 ms). The Power Receiver can communicate the CE data packet within limits specified for the tintervai. Thus, the tintervai might create a periodicity for the CE data packets 310a, 310b, and 310c. In some implementations, the Power Receiver attempts to communicate a next CE data packet at the target tintervai time of 250 ms following the start of the preceding CE data packet. Depending on when the Power Receiver communicates each CE data packet, there may be a variable delay (T) of as much as 700 milliseconds (ms) between CE data packets 310a, 310b, and 310c.

[0051] In some instances, a load state can change during the delay (T). For example, FIG. 3 shows a load change 312 occurring soon after the first CE data packet 310a. Based on the tintervai, the Power Receiver 118 may not communicate the next CE data packet (the second CE data packet 310b) for up to 700 ms. Absent the techniques of this disclosure, the load change 312 can cause a high instantaneous overvoltage in the Power Receiver 118. For example, a load may change from a high powder requirement (such as 200W) to a low power requirement (such as 0W or 5W). Because a traditional power controller is configured to maintain operating point betw een CE data packets, the Power Transmitter 102 might transmitwireless power using the same control inputs that was used to transmit 200W power requirement for a period of time until the next CE data packet 310b can indicate a new power setting based on the load change 312.

[0052] FIG. 4 illustrates an example of a control loop 400 performed between a Power Transmitter 102 and a Power Receiver 118. Referring to FIG. 4, the Power Receiver 118 selects a desired control point (block 402). For example, the control point may be based on a current, voltage, or power requirement of a load of the Power Receiver 118. The Power Receiver 118 determines an actual control point 406 based on the wireless power signal 422 received by the power pickup unit 408 (such as the secondary coil and rectifier as described with reference to FIG. 1).

[0053] At block 404, the Power Receiver 118 calculates a control error value using the desired control point and the actual control point. For example, the Power Receiver 118 may calculate the control error value through the (relative) difference between a desired voltage (or current) and an actual voltage (or current). The Power Receiver 118 generates control signaling 410 based on the control error value and transmits this to the Power Transmitter 102. In a traditional communication technique, the control signaling 410 may be encoded in a CE data packet.

[0054] The Power Transmitter 102 receives the control signaling 410. The Power Transmitter 102 can use the control signaling 410 to set a new operating point if it is required (block 416). Here, for example, the operating point may be at least one of amplitude, a frequency and a duty cycle of an AC voltage applied to a primary' coil. To determine the new operating point (block 416), the Power Transmitter 102 may determine a new primary cell current (block 412). The new primary cell current may be based on an actual primary cell current (block 420) and the control signaling 410. The Power Transmitter 102 may determine a control towards the new primary' cell current (block 414) and determine the new operating point (block 416) to meet the new primary cell current.

[0055] The Power Transmitter 102 transmits the wireless power signal 422 to the Power Receiver 118 based on the new operating point (determined in block 416) via the power conversion unit 418 (such as the Power Transmitter unit 110 described with reference to FIG. 1). Absent the techniques of this disclosure, the Power Transmitter 102 may maintain the operating point until a new control signaling is received from the Power Receiver 118.

[0056] FIG. 4 describes control loop 400 including aspects of the Power Transmitter 102 and the Power Receiver 118. Implementations of blocks 412. 414, 416 and 420 can be further described as a PID algorithm or control algorithm of a controller (such as PTX controller 108described with reference to FIG. 1 or a processor) of the Power Transmitter 102. FIG. 5 provides a description of a traditional PID algorithm of the controller, as well as a modification to the PID algorithm to support changes in operating point between CE data packets.

[0057] FIG. 5 illustrates a conceptually illustrating a controller 500 for a Power Transmitter to control an operating point according to some aspects of this disclosure. The controller 500 can implement the process of blocks 412, 414, 416 and 420 (combined) as described with reference to FIG. 4. The controller 500 can be implemented as a TX controller (such as PTX controller 108 described with reference to FIG. 1) or processor of the Power Transmitter. For brevity, the operations of the controller 500 are described as operations of the Power Transmitter.

[0058] The Power Transmitter receives a control error value. In FIG. 5, the control error value is a V error 504. The Power Transmitter also obtains the Imeasured 506, which is a present current measured at the Power Transmitter unit of the Power Transmitter. At block 502, the Power Transmitter calculates the reference current (Ireference) 508 by a sum of the Imeasured and the Imeasured multiplied with the Verror 504 and a variable factor (k). During an adjustment based on a CE data packet, the Ireference 508 is then compared at block 510 with the Imeasured 506 to calculate the Error 512. The lerroi 512 represents the difference between the Ireference 508 and the Imeasured 506. Then a PID Controller 514 calculates the operating point signal 516 to provide to the driver (such as Power Transmitter unit 110) to control the operating point.

[0059] Bold lines in FIG. 5 indicate an example modification to the controller 500 to enable the controller 500 to adjust the operating point between CE data packets based on power measurements. The example modification includes a power delta calculation 518 and adder 532 added to a traditional controller 500. In the power delta calculation 518, the Power Transmitter calculates a P error 526 based on a difference 524 between the Pcaicuiated 520 with the Pbaseiine 522. The Pbaseiine 522 is the average pow er calculated at the Power Transmitter after adjusting the operating point based on a previous control error value. The Pbaseiine 522 can be an average of the power over a power averaging time (referred to as the Pbaseiine measurement period) that occurs after a change to the operating point. The Pcaicuiated 520 is a periodically calculated average power at the Power Transmitter after the Pbaseiine is determined. Since both the Pbaseiine 522 and the Pcaicuiated 520 are averaged separately, the power averaging time (Pcaicuiated measurement period) for Pcaicuiated 520 might be the same or different from the power averaging time (Pbaseiine measurement period) for the Pbaseiine 522. In some implementations, the first instance of the power averaging time is referred to as thePbaseiine measurement period and the subsequent instances of the power averaging time are referred to as P calculated measurement periods.

[0060] For both the Pbaseiine and the Pcaicuiated, the Power Transmitter can obtain voltage and current measurements at the Power Transmitter without the need for a communication from the Power Receiver. For example, the voltage and current measurements can be obtained from a DC input to the Power Transmitter unit (such as the DC input to an inverter). In another example, the voltage and current measurements can be obtained from a tank circuit connected to the output of the power transmitter unit. The tank circuit includes the primary coil and the resonant capacitor of the Power Transmitter. In some implementations, the P error 526 might be adjusted by a variable factor (k2) at block 528. The P error 526 (or the adjusted Perror 530) can be added (at block 532) to the Leference 508 to generate a modified reference current Leference 434. Then, at block 510, the Power Transmitter uses the modified Leference 534 and the Imeasured 506 to calculate the terror 512. The rest of the calculation proceeds as normal, including the PID Controller 514 using the nor 512 (which is now based on the modified Leference 534) to determine the operating point signal 51 . In some implementations, the power delta calculation 518 can be added directly to the output of the PID Controller 514 to affect the operating point signal 516. The Power Transmitter can use the power delta calculation 518 to sense sudden changes in power between two consecutive CE data packets. The power delta calculation 518 causes a change to the 516. Thus, in response to the sudden change in power, the Power Transmitter reduces the voltage and / or current applied to the primary tank circuit to avoid an overvoltage in the Power Receiver. In some implementations, the power delta calculation 518 can be any calculation in which the Power Transmitter senses a sudden change in power delivered to the Power Receiver that is not related to a change in operating point based on the feedback-based control mechanism.

[0061] Referring back to the power delta calculation 518, the Pcaicuiated 520 and the Pbaseiine 522 can be further described in relation to timing for feedback-based control mechanism. For example, the Pbaseiine 522 may be calculated immediately or soon after adjusting the operating point based on the most recent control error value and blocks 502, 510, and 514. The Pbaseiine 522 may change after each iteration of the control loop and after each time the operating point is adjusted using the control error value. The Power Transmitter might store the Pbaseiine in a memory for use with the power delta calculation 518 done in between two consecutive CE data packets. In contrast, the Pcaicuiated 520 is based on voltage and current measurements obtained after the Pbaseiine 522 has been calculated. The Pcaicuiated 520 can vary based on load changes that impact the Power Transmitter tank circuit or driver circuit. When a large load change occurs, the Pcaicuiated 520 can experience a large change. Thus, the Power Transmittercan quickly react (such as within 1-2 ms) to large load changes that occur after one CE data packet and before the next CE data packet (which may be up to 250 ms later).

[0062] FIG. 6 is a timing diagram 600 showing power control according to some aspects of this disclosure. As described with reference to FIG. 3. the Power Receiver 118 periodically transmits CE data packets 310a, 310b, and 310c. Each CE data packet includes a control error value. The Power Receiver 118 communicates the CE data packets 310a, 310b, and 310c during communication periods. FIG. 6 shows a control error interval 602 (tintervai) between the start of a first CE data packet 310a and a start of a second CE data packet 310b). FIG. 6 shows the communication period 604 when the Power Receiver 118 communicates the CE data packet 310b.

[0063] After each CE data packet 310a, 310b and 310c, the Power Transmitter 102 adjusts the operating point based on the control error value in the CE data packets. Furthermore, the Power Transmitter 102 determines the Pbasdinc 522. Subsequently, the Power Transmitter 102 obtains voltage and current measurements at the Power Transmitter to calculate the Pcaicuiated 520. The Pcaicuiated 520 can be measured and calculated often between each communication period. For example, the Pcaicuiated might be measured and calculated often during the control error interval 602 between the first CE data packet 310a and the second CE data packet 310b. The Power Transmitter 102 calculates the P error based on a difference between the Pcaicuiated 520 and the Pbaseiine 522. The Perror can be used with the power delta calculation 518 as described with reference to FIG. 5. The Power Transmitter 102 modifies the Reference used to calculate the terror for the PID algorithm. The Power Transmitter 102 can adjust the operating point as needed during the control error interval 602, even before the next CE data packet (such as the second CE data packet 310b) is received.

[0064] FIG. 7A illustrates electrical parameters 700b of a wireless power system using a traditional controller absent the techniques of this disclosure. The charts in FIG. 7A are time plots of the PTx current, PTx voltage, PTx tank power at the Power Transmitter in relation to the load current, load voltage, PRx tank current. PRx tank voltage, and load switch at the Power Receiver.

[0065] A first control error value might be communicated in a first CE data packet during a first communication period. For brevity, the first CE data packet is illustrated as a first communication event 702). Absent the techniques of this disclosure, the Power Transmitter would set the operating point based on the first control error value and then maintain the operating point until the next CE data packet (illustrated as a second communication event 704). Elowever, at time 706, the Power Receiver may have a load change (also referred to asa load switch, load throw, or load transition). For example, the load power requirement may change from 200W to 5W. The load current 708 might drop as a result of the load change. However, because the Power Transmitter is maintaining the operating point until the second communication event 704, the load voltage 710 and the PRx tank voltage 714 may increase. An overvoltage condition can occur which can damage the load or the Power Receiver or create an unsafe fire or electrical hazard. The overvoltage condition can last until the second communication event 704 when the Power Transmitter receives a new control error value and adjusts the operating point for the PTx current, PTx voltage, and PRx tank power (shown at circle 716).

[0066] FIG. 7B illustrates electrical parameters 700b of a wireless power system using a power controller with overvoltage protection according to some aspects of this disclosure. After the first communication event 702, the Power Transmitter might adjust the operating point of the wireless power signal. The Power Transmitter determines the Pbaseiine during the Pbaseiine measurement period 720 after adjusting the operating point based on the control error value received at the first communication event 702. Following the Pbaseiine measurement period 720, the Power Transmitter might measure and calculate the Pcaicuiated during the Pcaicuiated measurement period 722. Although only one Pcaicuiated measurement period 722 is illustrated, the may be several Pcaicuiated measurement periods after the Pbaseiine measurement period 720 and before the second communication event 704.

[0067] The load change occurs at time 706 as described with reference to FIG. 7B. However, FIG. 7B differs from FIG. 7A because the Power Transmitter compares the Pbaseiine and the Pcaicuiated and determines that the P error (difference between Pbaseiine and Pcaicuiated) is above a threshold. The Power Transmitter adjusts the operating point (shown at circle 712) when the Perror is above the threshold to prevent an overvoltage condition of the Power Receiver. In experimental tests using the described overvoltage protection features, the instantaneous load spike (shown at circle 718) remained for only a brief period of time and below?a threshold (such as 58 Volts (V)).

[0068] FIG. 8 is a flow diagram illustrating example operations of a process 800 for power control by a Powder Transmitter. The operations of the process 800 may be implemented by a controller or processor of a Pow er Transmitter (such as any of the Pow er Transmitters 102 as described herein). In some implementations, the operations of process 800 may be implemented by an apparatus, such as the apparatus 1300 described with reference to FIG. 13. For brevity, the operations are described as performed by an apparatus.

[0069] In block 802. the apparatus transmits a wireless power signal to a Power Receiver. In block 804, the apparatus receives a first control error value from the Power Receiver. In block 806, the apparatus adjusts an operating point of the wireless power signal based on the first control error value. In block 808, the apparatus determines an average baseline power (Pbaseiine) of the wireless power signal during a Pbaseiine measurement period after the adjusting the operating point. In block 810, the apparatus calculates a average calculated power (Pcaicuiated) of the wireless power signal during at least one Pcaicuiated measurement period after the Pbaseiine measurement period and before receiving a second control error value from the Power Receiver. In block 812. the apparatus controls the operating point based, at least in part, on a difference between the Pbaseiine and the Pcaicuiated.

[0070] FIG. 9 is a flow diagram illustrating example operations of another process 900 for power control. The operations of the process 900 may be implemented by a Power Transmitter (such as any of the Power Transmitters 102 as described herein). In some implementations, the operations of process 900 may be implemented by an apparatus, such as the apparatus 1300 described with reference to FIG. 13. For brevity, the operations are described as performed by an apparatus.

[0071] In block 902, apparatus transmits a wireless power signal to a Power Receiver. In block 904, the apparatus adjusts operating point of the wireless power signal based on a first control error value from the Power Receiver. In block 906, apparatus determines a baseline power (Pbaseiine) of the wireless power signal based on first measurements after adjusting the operating point using the first control error value. In blocks 908, 910, 914 and 918, apparatus controls the operating point based on Power Transmitter measurements after the first control error value and before a second control error value. In block 910. the apparatus calculates a calculated power (Pcaicuiated) based on second measurements at the Power Transmitter. In block 912, the apparatus calculates a power error value (Perror) based on a difference between the Pbaseiine and the Pcaicuiated. In block 914, apparatus adjusts the operating point based on the P error.

[0072] At decision block 916, the apparatus determines whether a second control error value has been received from the Power Receiver. If so, the process 900 returns to block 904 to use the second control error value to adjust the operating point. If, at decision block 916, a second control error value has not yet been received, the process 700 returns to blocks 908. 910, 912, and 914.

[0073] FIG. 10 is a flow diagram illustrating example operations of a process 1000 for overvoltage protection. The operations of the process 1000 may be implemented by acontroller or processor of a Power Transmitter (such as any of the Power Transmitters 102 as described herein). In some implementations, the operations of process 1000 may be implemented by an apparatus, such as the apparatus 1300 described with reference to FIG. 13. For brevity, the operations are described as performed by an apparatus.

[0074] In block 1002, the apparatus transmits a wireless power signal to a Power Receiver. In block 1004, the apparatus adjusts an operating point of the wireless power signal based on periodic control error (CE) data packets received from the Power Receiver, the periodic CE data packets including at least a first CE data packet and a second CE data packet. In block 1006, the apparatus mitigates an overvoltage condition of the Power Receiver when a load of the Power Receiver changes during the control error interval (tintervai) between the first CE data packet and the second CE data packet, wherein mitigating the overvoltage condition includes adjusting the operating point based on a difference between a baseline power (Pbaseiine) of the wireless power signal based on first measurements at the Power Transmitter after the first CE data packet and a calculated power (Pcakuiated) of the wireless power signal based on second measurements at the Power Transmitter after the Pbaseiine.

[0075] FIG. 11 is a flow diagram illustrating example operations of a process 1100 of a Power Receiver. The operations of the process 1100 may be implemented by a controller or processor of a Power Receiver (such as any of the Power Receivers 118 as described herein). In some implementations, the operations of process 1100 may be implemented by an apparatus, such as the apparatus 1300 described with reference to FIG. 13. For brevity, the operations are described as performed by an apparatus.

[0076] In block 1102, the apparatus communicates power configuration information to the Power Transmitter, the power configuration information enabling overvoltage protection for a load of the Power Receiver. In block 1104, the apparatus receives a wireless power signal from the Power Transmitter. In block 1106, the apparatus periodically communicating control error values to the Power Transmitter during a power transfer phase.

[0077] The processes 800, 900, 1000 and 1100 are examples of operations. In some implementations, the processes 800, 900, 1000 and 1100 can include other operations or different operations from those described with reference to their respective figures. For example, in some implementations, the Power Transmitter can detect an overvoltage condition of the Power Receiver when the Perror is above a threshold value. The Power Transmitter might communicate an error message to the Power Receiver or present an error message via a user interface of the Power Transmitter or the Power Receiver. In some implementations, the Power Transmitter might cease transmission of the wireless powersignal in response to detecting the overvoltage condition in addition to. or instead of, adjusting the operating point of the wireless power signal. Other variations are possible within the scope of this disclosure.

[0078] FIG. 12 depicts a conceptual diagram of an example message for communicating power configuration information according to some aspects of this disclosure. For example, the message 1202 may be sent from a Power Receiver to a Power Transmitter. In some implementations, the message 1202 may be a configuration message or part of another message. The message 1202 may include a header 1208 and a payload 1204. In some implementations, the header 1208 includes frame control information indicating that the 1202 includes power configuration information. In some implementations, the message 1202 may include a preamble 1206 indicating the start of the message 1202. The pay load 1204 includes one or more information elements 1210, 1212, and 1214.

[0079] Several example information elements 1216 are illustrated in FIG. 12. For example, the power configuration information might include a value indicating the load capacitance 1218 used in the Power Receiver, a rated load voltage 1220, an allowable overvoltage level 1222, a time to reach overvoltage condition 1224 from a rated nominal voltage condition when the load is thrown from a full load to no load, a suggested power averaging time 1226 for the Power Transmitter to use in calculating the Pbaseiine or Pcaicuiated, or any combination of the above-mentioned information. The load capacitance value determines the rate at which overvoltage can occur at the Power Receiver.

[0080] The Power Transmitter can use the power configuration information (such as rated voltage, allowable overvoltage, or a time taken to reach an allowable overvoltage condition from a rated nominal voltage condition when the load is thrown from a full load to no load) to determine the speed at which averaging of the Pcaicuiated needs to be carried out in order to detect a change in power before the overvoltage condition. Additionally, or alternatively, the Power Receiver can communicate a suggested power averaging time based on empirical test results using the Power Receiver with a standard Power Transmitter in a test environment. The Power Receiver can send one or more of the above-referenced power configuration information to the Power Transmitter to help the Power Transmitter determine the power averaging time. The Power Transmitter may set the power averaging time small enough to enable the Power Transmitter to adequately detect the overvoltage condition of the Power Receiver during a load throw event. In some implementations, the Power Transmitter can determine the power averaging time or an upper limit on the power averaging time based on its operating parameters and one or more parameters of the power configuration information. A power averaging time larger than the upper limit can result in the Power Transmitter notacting to prevent an overvoltage in the Power Receiver. In some implementations, the Power Transmitter can determine the time within which the Pbaseiine measurement period occurs after the Power Transmitter adjusts the operating point based on a control error value from the Power Receiver. On the occurrence of deviation of Pcaicuiated from the Pbaseiine, the Power Transmitter can decide the time taken to move to a new operating point depending on the magnitude of the deviation.

[0081] FIG. 13 is 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 transmission apparatus (such as the Power Transmitter 102) 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 ).

[0082] The apparatus 1300 may include one or more controllers 1308 (such as a TX controller) configured to manage a Power Transmitter circuit 106. 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. 6, or any combination thereof.

[0083] 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 yvith 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.

[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 performadditional 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 implementation options (identified as clauses for reference).

[0086] Clause 1. A method performed by a Power Transmitter, including: transmitting a wireless power signal to a Power Receiver; receiving a first control error value from the Power Receiver; adjusting an operating point of the wireless power signal based on the first control error value; determining an average baseline power (Pbaseiine) of the wireless power signal during a Pbaseiine measurement period after said adjusting the operating point; calculating a average calculated power (P calculated) of the wireless power signal during at least one P calculated measurement period after the Pbaseiine measurement period and before receiving a second control error value from the Power Receiver; and controlling the operating point based, at least in part, on a difference between the Pbaseiine and the Pcaicuiated.

[0087] Clause 2. The method of clause 1, where determining the Pbaseiine includes obtaining first measurements during the Pbaseiine measurement period, and where calculating the Pcaicuiated includes obtaining second measurements during a Pcaicuiated measurement period after the Pbaseiine measurement period.

[0088] Clause 3. The method of clause 2, where the first measurements and the second measurements include voltage and current measurements at a direct current (DC) input of a driver circuit of the Power Transmitter.

[0089] Clause 4. The method of clause 2, where the first measurements and the second measurements include voltage and current measurements at a tank circuit that includes a primary coil of the Power Transmitter.

[0090] Clause 5. The method of any one of clauses 1 to 4, further including: periodically calculating the Pcaicuiated during each of a plurality of Pcaicuiated measurement periods before receiving the second control error value.

[0091] Clause 6. The method of any one of clauses 1 to 5. further including: calculating a power error value (Perror) based on the difference between the Pbaseiine and the Pcaicuiated; and detecting an overvoltage condition of the Power Receiver when the Perror is above a threshold value.

[0092] Clause 7. The method of clause 6, further including communicating an error message to the Power Receiver in response to detecting the overvoltage condition.

[0093] Clause 8. The method of clause 6 or 7, further including ceasing transmission of the wireless power signal in response to detecting the overvoltage condition.

[0094] Clause 9. The method of any one of clauses 1 to 8, further including: receiving a power request from the Power Receiver; and setting a DC output voltage of a power source of the Pow er Transmitter based, at least in part, on the power request, where the operating point is further based on the DC output voltage.

[0095] Clause 10. The method of clause 9, where setting the DC output voltage of the power source includes setting the DC output voltage using a linear proportional calculation of the pow er request, or setting the DC output voltage to a DC output voltage level that corresponds to a range that includes the power request, where the Power Transmitter supports a plurality' of DC output voltage levels that correspond to a plurality of ranges of requested power.

[0096] Clause 11. The method of any one of clauses 1 to 10, where the Pbaseiine is an average baseline power based on a first plurality' of voltage and current measurements over the Pbaseiine measurement period, and where the Pcaicuiated is an average measured power based on a second plurality of voltage and current measurements over the Pcaicuiated measurement period.

[0097] Clause 12. The method of any one of clauses 1 to 11, further including: receiving power configuration information from the Power Receiver; and determining a power averaging time based on the power configuration information, where the Pbaseiine measurement period is a first instance of the poyver averaging time after said adjusting the operating point based on the first control error value, and where the Pcaicuiated measurement period is a subsequent instance of the power averaging time.

[0098] Clause 13. The method of any one of clauses 1 to 11, further including: receiving pow er configuration information from the Pow er Receiver; and determining a duration of the Pbaseiine measurement period, a duration of the Pcaicuiated measurement period, or both, based on the power configuration information.

[0099] Clause 14. The method of clause 12 or 13, where the power configuration information includes: a value of load capacitance used in the Power Receiver, a rated load voltage, an allowable overvoltage level, a time taken to reach an allowable overvoltagecondition from a rated nominal voltage condition when the load is thrown from a full load to no load, a suggested power averaging time communicated by the Power Receiver, or any combination thereof.

[0100] Clause 15. The method of any one of clauses 1 to 14, receiving successive control error (CE) data packets according to a control error interval (tintervai); and after each CE data packet: adjusting the operating point based on a new control error value in a particular CE data packet, determining a new Pbaseiine after said adjusting the operating point based on the new control error value, and controlling the operating point during the tintervai based, at least in part, on a difference between the new Pbaseiine and a new Pcaicuiated after determining the new Pbaseiine.

[0101] Clause 16. The method of clause 15, where the tintervai is in a range from 0 ms to 700 ms, the method further including: periodically calculating the new Pcaicuiated approximately every’ 1-2 ms during the tintervai.

[0102] Clause 17. A method performed by a Power Transmitter, including: transmitting a wireless power signal to a Power Receiver; adjusting an operating point of the wireless power signal based on periodic control error (CE) data packets received from the Power Receiver, the periodic CE data packets including at least a first CE data packet and a second CE data packet; and mitigating an overvoltage condition of the Power Receiver when a load of the Power Receiver changes during a control error interval (tintervai) between the first CE data packet and the second CE data packet, where mitigating the overvoltage condition includes adjusting the operating point based on a difference between a baseline power (Pbaseiine) of the wireless power signal based on first measurements at the Power Transmitter after the first CE data packet, and a calculated power (Pcaicuiated) of the wireless power signal based on second measurements at the Power Transmitter after the Pbaseiine.

[0103] Clause 18. The method of clause 17, where the first measurements include first voltage and current measurements during a Pbaseiine measurement period, and where the second measurements include second voltage and current measurements during a Pcaicuiated measurement period after the Pbaseiine measurement period.

[0104] Clause 19. The method of clause 17 or 18. where the first measurements and the second measurements are measured at a direct current (DC) input of a driver circuit of the Power Transmitter.

[0105] Clause 20. The method of clause 17 or 18. where the first measurements and the second measurements are measured a tank circuit that includes a primary coil of the Power Transmitter.

[0106] Clause 21. A Power Transmitter including: a primary coil configured to transmit a wireless power signal to a Power Receiver; and a TX controller configured to implement any one of the methods any one of clauses 1 to 20.

[0107] Clause 22. A method performed by a Power Receiver, including: communicating power configuration information to a Power Transmitter, the power configuration information enabling overvoltage protection for a load of the Power Receiver; receiving a wireless power signal from the Power Transmitter; and periodically communicating control error values to the Power Transmitter during a power transfer phase.

[0108] Clause 23. The method of clause 22, where the power configuration information includes: a value of load capacitance used in the Power Receiver, a rated load voltage, an allowable overvoltage level, a time taken to reach an allowable overvoltage condition from a rated nominal voltage condition when the load is thrown from a full load to no load, a power averaging time for the Power Transmitter, a duration of a baseline power (Pbaseiine) measurement period, a duration of a calculated power (Pcaicuiated) measurement period, or any combination thereof.

[0109] Clause 24. The method of clause 22 or 23, further including: where the power configuration information indicates a Pbaseiine measurement period for an average baseline power (Pbaseiine), a Pcaicuiated measurement period for an average calculated power (Pcaicuiated), or both, and where the Pbaseiine measurement period and one or more instances of the Pcaicuiated measurement period occur between two successive control error values.

[0110] Clause 25. The method of clause 22, further including: communicating a power request to a Power Transmitter including a request to set a DC output voltage of a power source of the Power Transmitter based, at least in part, on the power request.

[0111] Clause 26. The method of any one of clauses 22 to 25, further including: receiving an error message from the Power Transmitter, the error message indicating that the Power Transmitter has detected an overvoltage condition based on a sudden change of average power delivered to the Power Receiver between two successive control error values.

[0112] Clause 27. A Power Receiver including: a secondary coil configured to receive a wireless power signal from a Power Transmitter; and a controller configured to implement any one of the methods any one of clauses 22 to 26.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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 circuitry7that is specific to a given function.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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 between any of the illustrated operations. In some circumstances, multitasking and parallelprocessing 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 method performed by a Power Transmitter, comprising: transmitting a wireless power signal to a Power Receiver; receiving a first control error value from the Power Receiver; adjusting an operating point of the wireless power signal based on the first control error value; determining an average baseline power (Pbaseiine) of the wireless power signal during a Pbaseiine measurement period after said adjusting the operating point; calculating an average calculated pow er (Pcaicuiated) of the wireless power signal during at least one Pcaicuiated measurement period after the Pbaseiine measurement period and before receiving a second control error value from the Power Receiver; and controlling the operating point based, at least in part, on a difference between the Pbaseiine and the Pcaicuiated.

2. The method of claim 1. wherein determining the Pbaseiine includes obtaining first measurements during the Pbaseiine measurement period, and wherein calculating the Pcaicuiated includes obtaining second measurements during a Pcaicuiated measurement period after the Pbaseiine measurement period.

3. The method of claim 2, wherein the first measurements and the second measurements include voltage and current measurements at a direct current (DC) input of a driver circuit of the Power Transmitter.

4. The method of claim 2, wherein the first measurements and the second measurements include voltage and current measurements at a tank circuit that includes a primary' coil of the Power Transmitter.

5. The method of any one of claims 1 to 4, further comprising: periodically calculating the Pcaicuiated during each of a plurality of Pcaicuiated measurement periods before receiving the second control error value.

6. The method of any one of claims 1 to 5, further comprising: calculating a pow er error value (P error) based on the difference betw een the Pbaseiine and the P calculated; anddetecting an overvoltage condition of the Power Receiver when the Perror is above a threshold value.

7. The method of claim 6, further comprising communicating an error message to the Power Receiver in response to detecting the overvoltage condition.

8. The method of claim 6 or 7, further comprising ceasing transmission of the wireless power signal in response to detecting the overvoltage condition.

9. The method of any one of claims 1 to 8, further comprising: receiving a power request from the Power Receiver; and setting a DC output voltage of a power source of the Power Transmitter based, at least in part, on the power request, wherein the operating point is further based on the DC output voltage.

10. The method of claim 9, wherein setting the DC output voltage of the power source includes setting the DC output voltage using a linear proportional calculation of the power request, or setting the DC output voltage to a DC output voltage level that corresponds to a range that includes the power request, wherein the Power Transmitter supports a plurality of DC output voltage levels that correspond to a plurality of ranges of requested power.

11. The method of any one of claims 1 to 10, wherein the Pbaseiine is an average baseline power based on a first plurality of voltage and current measurements over the Pbaseiine measurement period, and wherein the Pcaicuiated is an average measured power based on a second plurality of voltage and current measurements over the P calculated measurement period.

12. The method of any one of claims 1 to 11, further comprising: receiving power configuration information from the Power Receiver; and determining a power averaging time based on the power configuration information, wherein the Pbaseiine measurement period is a first instance of the power averaging time after said adjusting the operating point based on the first control error value, and wherein the Pcaicuiated measurement period is a subsequent instance of the power averaging time.

13. The method of any one of claims 1 to 11, further comprising: receiving power configuration information from the Power Receiver; anddetermining a duration of the Pbaseiine measurement period, a duration of the Pcaicuiated measurement period, or both, based on the power configuration information.

14. The method of claim 12 or 13, wherein the power configuration information includes: a value of load capacitance used in the Power Receiver, a rated load voltage, an allowable overvoltage level, a time taken to reach an allowable overvoltage condition from a rated nominal voltage condition when the load is thrown from a full load to no load, a suggested power averaging time communicated by the Power Receiver, or any combination thereof.

15. The method of any one of claims 1 to 14, receiving successive control error (CE) data packets according to a control error interval (tintei-vai); and after each CE data packet: adjusting the operating point based on a new control error value in a particular CE data packet, determining a new Pbaseiine after said adjusting the operating point based on the new control error value, and controlling the operating point during the tintervai based, at least in part, on a difference between the new Pbaseiine and a new Pcaicuiated after determining the new Pbaseiine.

16. The method of claim 15, wherein the tintervai is in a range from 0 ms to 700 ms, the method further comprising: periodically calculating the new Pcaicuiated approximately every’ 1-2 ms during the tintervai.

17. A method performed by a Power Transmitter, comprising: transmitting a wireless power signal to a Power Receiver; adjusting an operating point of the wireless power signal based on periodic control error (CE) data packets received from the Power Receiver, the periodic CE data packets including at least a first CE data packet and a second CE data packet; and mitigating an overvoltage condition of the Power Receiver when a load of the Power Receiver changes during a control error interval (tintervai) between the first CE data packet and the second CE data packet, wherein mitigating the overvoltage condition includes adjusting the operating point based on a difference betw eena baseline power (Pbaseiine) of the wireless power signal based on first measurements at the Power Transmitter after the first CE data packet, and a calculated power (Pcaicuiated) of the wireless power signal based on second measurements at the Power Transmitter after the Pbaseiine.

18. The method of claim 17, wherein the first measurements include first voltage and current measurements during a Pbaseiine measurement period, and wherein the second measurements include second voltage and current measurements during a Pcaicuiated measurement period after the Pbaseiine measurement period.

19. The method of claim 17 or 18, wherein the first measurements and the second measurements are measured at a direct current (DC) input of a driver circuit of the Power Transmitter.

20. The method of claim 17 or 18, wherein the first measurements and the second measurements are measured a tank circuit that includes a primary coil of the Power Transmitter.

21. A Power Transmitter comprising: a primary coil configured to transmit a wireless power signal to a Power Receiver; and a TX controller configured to implement any one of the methods any one of claims 1 to 20.

22. A method performed by a Power Receiver, comprising: communicating power configuration information to a Power Transmitter, the power configuration information enabling overvoltage protection for a load of the Power Receiver; receiving a wireless power signal from the Power Transmitter; and periodically communicating control error values to the Power Transmitter during a power transfer phase.

23. The method of claim 22, wherein the power configuration information includes: a value of load capacitance used in the Power Receiver, a rated load voltage, an allowable overvoltage level, a time taken to reach an allowable overvoltage condition from a rated nominal voltage condition when the load is thrown from a full load to no load, a power averaging time for the Power Transmitter, a duration of a baseline power (Pbaseiine) measurement period,a duration of a calculated power (Pcaieuiated) measurement period, or any combination thereof.

24. The method of claim 22 or 23, further comprising: wherein the power configuration information indicates a Pbaseiine measurement period for an average baseline power (Pbaseiine), a Pcaieuiated measurement period for an average calculated power (Pcaieuiated), or both; and wherein the Pbaseiine measurement period and one or more instances of the Pcaieuiated measurement period occur between two successive control error values.

25. The method of any one of claims 22 to 24, further comprising: communicating a power request to a Power Transmitter including a request to set a DC output voltage of a power source of the Power Transmitter based, at least in part, on the power request.

26. The method of any one of claims 22 to 25, further comprising: receiving an error message from the Power Transmitter, the error message indicating that the Power Transmitter has detected an overvoltage condition based on a sudden change of average power delivered to the Power Receiver between two successive control error values.

27. A Power Receiver comprising: a secondary coil configured to receive a wireless power signal from a Power Transmitter; and a controller configured to implement any one of the methods any one of claims 22 to26.

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