Systems and methods for optimal delivery of pulsed wireless power - Patents.com

Abstract

To provide a system and a method for optimally delivering pulsed wireless power by using a transmitter assembly useful for optimizing delivery of the wireless power to a plurality of receivers.SOLUTION: Each receiver measures its own need for power battery and transmits a measurement value thereof as a request to a transmitter. The transmitter is configured to normalize and compare battery need requests. Then, the transmitter allocates pulses of wireless power among the requesting receivers according to their battery need.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] [Background technology]

[0002] Many useful applications are based on the transmission of radio pulses, such as radar detection, which uses transmitted and reflected pulsed microwave signals, and medical ablation, which uses pulsed microwaves to ablate targeted body tissue.

[0003] Regarding pulsed signals for wirelessly delivering power, Powercast filed Patent Application Publication No. 2007-2009-11494 in January 2007. This application describes pulsing for optimizing wireless power transmission.

[0004] The above-mentioned Patent Document 1 describes the advantages of pulsing for wireless power supply as follows: -Improved rectifier efficiency Increase in output voltage Obtain the same amount of DC power with less average transmission power

[0005] A low average transmit power has the following advantages: -Reduction of human body safety distance - Wideband operation possible Recharges at lower average power than continuous wave power transmission Increased range and RF penetration at higher power levels - attenuating targets without increasing average output power.

[0006] However, Patent Document 1 does not disclose the unique problems that arise from wireless power delivery, nor does it disclose solutions to these unique problems. · Sequential delivery Reception attenuation Variable charging state Storage consumption Each of these issues is discussed below.

[0007] Sequential delivery refers to the fact that in wireless power systems, most or all of the power generated by a transmitter is typically delivered to one or a few receivers at a time. One reason is that signal strength falls off dramatically with distance due to the inverse square law (signal strength falls off as the square of the distance). That is, at any one time, most or all of the transmitter power is preferentially delivered to only one or a few receivers.

[0008] Reception attenuation refers to the fact that the strength of the power signal delivered by a receiver can be reduced by various factors such as distance from the transmitter, obstacles between the transmitter and receiver, and orientation of the receiver.

[0009] The variable charge state refers to the state of a charge holding device within the receiver, which is typically a battery but can also be a capacitor, that exhibits a state of charge ranging from zero to full.

[0010] Storage consumption relates to the rate at which a charge storage device (eg, a battery) loses charge. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] U.S. Patent Application No. 20070149162 Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention describes a solution to these major problems of wireless power delivery. [Means for solving the problem]

[0013] In accordance with the present invention, a system and method are provided for optimally delivering pulsed wireless power using a transmitter assembly useful for optimizing the delivery of wireless power to multiple receivers. Each receiver measures its own battery power demand and transmits the measurement as a request to the transmitter. The transmitter is configured to normalize and compare the battery demand requests. The transmitter then allocates pulses of wireless power among the requesting receivers according to battery demand.

[0014] It should be noted that the various features of the present invention described above can be implemented alone or in combination. These and other features of the present invention will be explained in more detail in the detailed description of the invention in conjunction with the following drawings.

[0015] In order that the invention may be more clearly appreciated, some embodiments will now be described by way of example with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a high-level block diagram illustrating a wireless transmitter and multiple receivers. [Figure 2A] FIG. 1 illustrates a circuit configured to calculate the state of charge of a battery. [Figure 2B] FIG. 2 illustrates a circuit configured to calculate the power consumption of a battery. [Figure 3] FIG. 2 illustrates a circuit configured to calculate the received power of a battery. [Figure 4] FIG. 10 illustrates another circuit configured to calculate the received power of a battery. [Figure 5] FIG. 1 shows a circuit configured to calculate the state of charge, power consumption, and power received by a battery. [Figure 6] FIG. 1 illustrates a circuit configured to detect whether a battery is overcharged. [Figure 7] FIG. 1 illustrates a series of pulses for a transmitter communicating with multiple receivers. [Figure 8]FIG. 1 illustrates a series of power pulses forming a power burst. [Figure 9] FIG. 1 illustrates an example of a transmitter-receiver communication scheme in which the receiver is not detected by the transmitter. [Figure 10] FIG. 1 illustrates an example of a transmitter-receiver communication scheme in which one receiver is detected by the transmitter. [Figure 11] FIG. 1 illustrates an example of a transmitter-receiver communication scheme in which a receiver detected by the transmitter is recognized as an authorized receiver. [Figure 12] FIG. 1 illustrates an example of a transmitter-receiver communication scheme in which a licensed receiver is receiving wireless power. [Figure 13-1] FIG. 1 illustrates an example of a transmitter-receiver communication scheme in which a transmitter recognizes and provides power to at least two receivers. [Figure 13-2] FIG. 1 illustrates an example of a transmitter-receiver communication scheme in which a transmitter recognizes and provides power to at least two receivers. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE INVENTION The present invention will now be described in detail with reference to several embodiments thereof, as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. However, it will be apparent to one skilled in the art that the embodiments may be practiced without some or all of these specific details. In other instances, well-known process steps and / or structures have not been described in detail in order to avoid unnecessarily obscuring the present invention. The features and advantages of the embodiments may be better understood with reference to the drawings and the following description.

[0018] The aspects, features, and advantages of exemplary embodiments of the present invention will be understood in connection with the following description taken in conjunction with the accompanying drawings. Those skilled in the art will appreciate that the described embodiments of the present invention are merely illustrative and not limiting, and are presented by way of example only. Any feature disclosed herein may be replaced by an alternative feature serving the same or a similar purpose, unless expressly stated otherwise. Accordingly, many other modified embodiments are contemplated to be within the scope of the present invention as defined herein and its equivalents. Because the embodiments disclosed herein are merely examples, absolute and / or sequential terms such as "will," "will not," "shall," "shall not," "must," "must not," "first," "initially," "next," "subsequently," "before," "after," "lastly," and "finally" are not intended to limit the scope of the present invention.

[0019] The present invention relates to a system and method for transmitting and receiving pulsed wireless power. Figure 1 is a high-level block diagram 1 showing a transmitter 2 transmitting wireless communication 3 and wireless power 4. A number of receivers 5a, 5b, 5c, 5n communicate with the transmitter 2 through wireless signals 6a, 6b, 6c, 6n, respectively. The receivers 5a, 5b, 5c, 5n recover the required wireless power 7a, 7b, 7c, 7n transmitted by the transmitter 2.

[0020] Pulsing of wireless power signals facilitates sequential delivery because individual pulses can be distributed to different receivers by changing the transmitter's phase, frequency, time, amplitude, or direction. Although the detailed description herein relates to phased pulsing, the invention is equally applicable to other signal modulation approaches.

[0021] Furthermore, the description below relates to delivering pulses to one receiver at a time. However, the present invention includes approaches that involve powering a subset of receivers at a time. For example, in a frequency-modulated pulsing approach, several subsets of receivers may be tuned to receive a particular frequency. When the transmitter delivers a pulse at that frequency, the receivers in two or more subsets are simultaneously charged.

[0022] In one embodiment of the present invention, wireless power delivery by a transmitter to multiple receivers is disclosed. The following description relates to batteries as the charge storage means for these receivers. However, the present invention applies equally to any storage means, such as capacitors and supercapacitors.

[0023] Furthermore, beyond battery power needs, some receivers may have more critical / urgent power needs than other receivers, for example, a life-saving receiver (e.g., a heart pump) may have more pressing power needs than a non-critical receiver (e.g., a toy), which are independent of the respective battery power needs of the two devices.

[0024] One embodiment of the above-described invention relates to variable battery demand. Satisfying the variable battery demands of one or more receivers includes the following functions: Battery demand measurement Battery demand communication Battery demand reception -Satisfying battery demand

[0025] When measuring battery demand, there are several schemes that a receiver can use to determine its own demand before transmitting to the transmitter. These schemes range from simple voltage measurements to sophisticated calculations. In the latter case, they can even be predictive, providing an estimate of the expected future situation and determining the amount of power required to meet the expected demand if it occurs.

[0026] The receiver must make various measurements and, in some embodiments, various calculations before it can send the necessary information to the transmitter.

[0027] Electronic circuitry located within or associated with the receiver measures the key metrics necessary to calculate battery demand. Three continuously varying metrics ("battery demand metrics") useful for measuring battery demand are: The state of charge ("State of Charge"), which indicates how charged the battery is Consumption ("Consumption"), which indicates how much of the battery charge is being consumed Received power ("received power"), which indicates how much power the battery is receiving is.

[0028] All other things being equal between the two batteries, -Charge state is lower than the other consumption is higher than the other, or -Received power is lower than the other In this case, one of the two has a larger power demand.

[0029] For a typical battery, each of the three battery demand metrics tends to fluctuate relatively frequently (eg, within seconds or fractions of a second).

[0030] Electronic circuits within the receiver measure some or all of the battery demand metrics, and alternative embodiments of these circuits are described below.

[0031] A first of these embodiments discloses an individual circuit for each metric. FIG. 2A shows a circuit 10 configured to calculate the state of charge of a battery. In circuit 10, voltage source 11 represents the incoming power charging battery 12. Battery 12 is connected to operational amplifier ("op amp") 14 through resistor 13. A second resistor 15 sets the gain of op amp 14. The op amp positive "+" terminal is connected to voltage reference ("VREF") 16, which can be set in at least two ways.

[0032] In the first of at least two ways to set voltage reference (VREF) 16, the voltage is set higher than the maximum expected voltage value of the battery. This causes operational amplifier 14 to create a range of positive values ​​for analog-to-digital converter ("ADC") 17, regardless of the battery's state of charge. ADC 17 digitizes the signal from operational amplifier 14 and provides 8-bit data to microprocessor 18. Microprocessor 18 can be configured to generate a table 19 listing battery voltages and % battery fullness.

[0033] In the second of at least two ways to set the voltage reference (VREF) 16, the voltage is set to correspond to a voltage value slightly higher than that reached when the battery can no longer safely provide power. This changed sign is a condition that is easily tested by the microprocessor 18, making software easier to write.

[0034] 2B shows a circuit 20 configured to calculate battery consumption. Circuit 20 includes a "+" power terminal connected to a voltage source 21 representing received power, and two resistors 23 and 25. and an operational amplifier 24. Two resistors 23 and 25 set the gain of the operational amplifier 24.

[0035] Resistor 23 connects the positive "+" and negative "-" input terminals of operational amplifier 24 together and has a very low resistance (eg, on the order of 1-5 milliohms).

[0036] Resistor 25 connects the negative "-" input of op amp 24 to the output terminal of op amp 24. The output signal of op amp 24 is connected to the input of ADC 27. ADC 27 digitizes the signal from op amp 24 and provides 8-bit data to microprocessor 28.

[0037] Resistor 25 should be selected so that the maximum expected power extraction (by electronic device 22) causes the output voltage from op-amp 24 to be near the maximum value that the ADC 27 input stage can read.

[0038] The received power can be calculated using circuit 30 shown in Figure 3. An antenna 31 is connected to the primary side of a transformer 32. The secondary side of transformer 32 is connected to a rectifier diode 36 and a capacitor 39. The voltage across capacitor 39 is nearly DC (DC with some ripple) and is configured to be proportional to the power received by the antenna.

[0039] Another embodiment for calculating received power is shown in Figure 4. Circuit 40 is configured to measure the current flowing into "Electronics" 22 in addition to the voltage across capacitor 39. The analog voltage "VA" at point A is proportional to the current flowing through "Electronics" 22. The analog voltage "VB" at point B is proportional to the voltage across capacitor 39. The analog voltages VA and VB are multiplied together in mixer 47. Thus, the output voltage "VC" of mixer 47 at point C is proportional to the power received by the antenna. Voltage VC is digitized in ADC 37 and then provided to microprocessor 18. Circuit 40 can be configured to provide power in watts and deliver it wirelessly to a receiver.

[0040] In yet another embodiment for measuring received power, the analog voltages V A and V B in Figure 4 can be digitized using two analog-to-digital converters (ADCs), not shown. The outputs of the two ADCs can then be easily multiplied digitally, and the digital result made available to the microprocessor 18.

[0041] In another embodiment, a single electronic circuit can be configured to measure all three of the battery demand metrics. This embodiment makes six measurements ("raw metrics"): V[RF] (Volts from RF) A[RF] (Amps from RF) V[S] (Volts at storage) A[S] (Amperes in storage) V[D] (volts at the device) A[D] (Amps at device)

[0042] These six raw (actual) metrics are measured using circuit 50 shown in Figure 5. Rectifying antenna (rectenna) 51 supplies power to storage battery 52 (e.g., a battery) through ammeter A[RF] 53. The storage battery supplies power to electronic device 22 through ammeters A[S] 55 and A[D] 57. Voltmeter V[RF] 54 measures the smoothed voltage of rectenna 51, voltmeter V[S] 56 measures the voltage across storage battery 52, and voltmeter V[D] 58 measures the voltage across electronic device 22.

[0043] Preferentially, these six measurements are taken simultaneously enough to minimize errors due to time delays between the measurements of the associated fluctuating voltages and currents when multiplied together.

[0044] Once these six raw metrics have been measured, a calculation is performed to obtain the battery demand metrics. Consumption = A[D] It is calculated as:

[0045] The received power can be obtained by multiplying the voltage and current from the rectenna as follows: Received power = W[RF] = V[RF] * A[RF]

[0046] The third battery demand metric—state of charge—is a percentage of total storage capacity. This metric can be measured in several ways.

[0047] In the first method, the state of charge can be obtained by observing the slightly fluctuating voltage of the storage device and using a look-up table to determine the SOC value. State of charge ~=f{V[S]}

[0048] In the second method, the state of charge can be determined by continuously summing the instantaneous current supplied to (or drawn from) the storage device and applying an appropriate correction factor, known in the art as "coulomb counting." State of charge ~=g{Sum(A[S])}

[0049] Both methods of measuring state of charge have well-known challenges that are the subject of ongoing research and improvement. In both cases, state of charge is converted to a unitless number - a percentage of the device's total charge capacity.

[0050] If no measurement of A[S] is provided, only V[S]. One drawback is that the look-up table only provides accurate values ​​for the "no load" condition after the battery has been resting for a period of time. With an additional ammeter, the second equation (State of Charge ~=g{Sum(A[RF]-A[D])}) can be replaced with: State of charge ~=h{Sum(V[S]*A[S])}

[0051] Note that the function g{} provides amperes, and the function h{} provides watts or watt*seconds depending on how h{} is calculated.

[0052] In addition to continuously varying battery demand metrics, some embodiments of the present invention also utilize slowly varying metrics. These latter metrics include storage capacity and maximum charge ("battery rating metrics").

[0053] The storage capacity of a battery ("storage capacity") relates to the maximum charge that the battery can hold. This metric is used to calculate the battery's state of charge, which can be expressed as a percentage of the storage capacity. Storage capacity is typically measured in ampere-hours. Attempting to charge a battery beyond its rated storage capacity typically results in heat generation and possibly damage to the battery.

[0054] In addition to storage capacity, batteries have a maximum charge capacity ("max charge"), which is a measure of how quickly the battery can absorb a charge. Putting too much energy into a battery in too short a time can damage the battery. The maximum charge capacity is It can be measured in watts*seconds per second (joules), which is equivalent to watts (i.e., W*s / s=W).

[0055] Storage capacity varies widely between batteries. Furthermore, batteries are typically rated by their static storage capacity. These ratings are calculated and published by battery manufacturers. Manufacturers typically publish graphs showing how these ratings degrade over time.

[0056] Like storage capacity, maximum charge capacity is usually rated as a battery's static rating, and manufacturers provide data sheets showing how this rating decreases over time.

[0057] One embodiment of the present invention uses the static ratings of storage capacity and maximum charge provided by these manufacturers.

[0058] However, a preferred embodiment calculates battery rating metrics directly because the actual performance of a battery with respect to these metrics can vary from its static rating due to inefficient recharging practices, but this variation (often a degradation) in battery performance occurs over periods much longer than seconds (e.g., weeks, months, or even years).

[0059] Today, battery rating metrics are generally not measured in storage in the equipment in use.

[0060] A direct method of detecting when the maximum charge has been exceeded would be useful. Figure 6 shows an electronic circuit 60 configured to detect when the maximum charge of a battery 61 has been exceeded. Two thermistors A 62 and B 63 are employed. A thermistor is a type of resistor whose resistance varies more with temperature than a standard resistor. Thermistors are widely used in devices where current is limited for circuit protection.

[0061] Thermistor A 62 is exposed to ambient temperature, while thermistor B 63 is in close contact with battery 61. When battery 61 heats up due to overcharging, the resulting heat causes the resistance of thermistor B 63 to fluctuate, resulting in a change in the voltage across B 63. Comparator circuit 64 detects the voltage difference between thermistors A 62 and B 63 and generates an analog voltage V at point C that is supplied to ADC 65, which digitizes the analog voltage output V of comparator circuit 64. The digital signal is then supplied to microprocessor 18. To ensure that thermistor B 63 is in close contact with battery 61, a cylindrical clamp 66 can be used to hold thermistor B 63 to battery 61. A blot 67 can be used to secure clamp 66 around battery 61.

[0062] The binary value "overcharged" is ambiguous, meaning either "exceeding maximum charge" or "charged beyond 100% storage capacity", however either meaning is valid (batteries will also overheat if they are discharged too quickly, but it is easy to determine whether they are charging or discharging by checking the sign of the draw: negative means charging, positive means discharging).

[0063] Once the battery demand metric has been measured and converted to a digital representation, the instantaneous battery demand can be calculated. The instantaneous battery demand is a single metric that represents the current battery demand.

[0064] Let function f represent the instantaneous battery demand, and s, d, and r represent the state of charge, consumed power, and received power, respectively. Then, function f(s, d, r) is the instantaneous battery demand.

[0065] Some constraints on the function f(s, d, r) are: In the case of two receivers and identical receivers for the two measurements, If d and r are equal, f is high for a receiver with low s. If d and s are equal, f is high for a receiver with low r. If r and s are equal, f is high for a high-d receiver.

[0066] A practical alternative to the logical function f is the "Time to Disable" ("TTD"). TTD is a predicted measurement of how long a storage device will continue to provide energy at its current level, after which the storage device is predicted to have used up all of its stored energy. At that point, dependent electronic devices will cease functioning (i.e., "disable") because they are no longer receiving energy.

[0067] When calculating TTD, the goal is to obtain the remaining charge ("residual charge") in the storage battery (or battery) and determine the time until depletion. TTD=Residual charge (As) / Consumption (A)=A*s / A=s

[0068] Residual charge is calculated from the state of charge (percentage) and the storage capacity, which is usually measured in ampere hours (A*h or Ah) and can be easily converted to ampere seconds (A*s or As). Residual charge (As) = State of charge (%) * Storage capacity (Ah) * 3600

[0069] Thus, the TTD parameter estimates the number of seconds that the storage device can support the current power consumption level.

[0070] Over time, multiple readings of the TTD for each receiver satisfy the same constraint on the negative of the function f (ie, −f) as described above.

[0071] As another example of calculating instantaneous battery demand, any of the three battery demand metrics can serve as a rough estimate: instantaneous battery demand can be equal to state of charge, consumed power, or received power.

[0072] One reason for using the above battery demand metric instead of TTD is the simplification of the measurement electronics required in the receiver.

[0073] In one embodiment of the present invention, different receivers may employ different battery demand measurements: one receiver may employ TTD, another receiver may employ one of the battery demand metrics, and yet another receiver may use another variation on the battery demand metric.

[0074] The instantaneous battery demand can provide an inaccurate indication of the true demand because from moment to moment the instantaneous battery demand can vary widely.

[0075] Therefore, a preferred embodiment of the present invention calculates a smoothed battery demand that is calculated based on multiple readings of the instantaneous battery demand.

[0076] For example, a moving average can smooth out fluctuating instantaneous battery demand readings to provide a smoothed battery demand. An example moving average smoothing algorithm can be represented as a series of steps that calculate a smoothed result for each successive reading. Total = Total - Display Value (This) Display value (This) = New display value Total = Total + Display Value (This) This=Next(This) Return (total / count)

[0077] With this assumption, "Count" contains the number of items in the moving average range. The result the first "Count" produces is ignored. The "Next" function recognizes "Count" and "This" wraps around to the beginning of the "Display Values" array after it reaches the end of the "Display Values" array.

[0078] In the above example, the feedback (sum / count) is equal to the instantaneous battery demand, e.g., instantaneous TTD. Therefore, the value returned by the algorithm is the smoothed battery demand, e.g., smoothed TTD.

[0079] The above illustrates one smoothing function, however, many alternative smoothing functions are known in the art and the present invention can use any smoothing function.

[0080] Another consideration in measuring true battery demand is that the receiver's battery consumption history is useful for predicting future demand. In this approach, the most recent "feedback (total / count)" readings, as used to calculate smoothed battery demand, are not sufficient. To predict battery demand, preferably the previous readings span weeks or months, rather than just seconds or minutes, in order to recognize useful patterns.

[0081] Preferably, the receiver's history data is stored in the receiver, because when a receiver's history is kept in its serving wireless power transmitter, if the receiver moves between different transmitters over the course of a day (e.g., a mobile phone moves from home to car to work to restaurant and back to work to car to home, some or all of which locations host transmitters that charge the phone), the transmitter will have only a partial record of the history available.

[0082] The time to start predicting the future is the moment when wireless power becomes available to the receiver again. A wireless power "session" is the period between the time wireless power becomes available to the receiver and the next time wireless power becomes available, including any intermediate time when wireless power was unavailable. A session begins when power becomes available to satisfy the predicted demand, and the calculation of the prediction should begin at the same time.

[0083] For each session, "session data" is collected that characterizes the session. An example of such data is: Session Data Start timestamp HHMMSS Days of the week 1-7 Session Duration seconds Power availability period seconds Average received power level W Total energy consumption Ws

[0084] The start timestamp is the start of the session. The day of the week is the day of the week on which the session start timestamp began. The session duration is how long the session lasts.

[0085] The power available period is the length of time during which the received power (V[RF]*A[RF]) exceeds zero.

[0086] The average received power level is the average received power during the session. It is calculated by summing periodic readings of the received power over the entire session to the received power level and dividing the latter by the power availability period.

[0087] Total energy expenditure is calculated by multiplying the sum of the expenditures by the session duration (V[D]*A[D]) in watt-seconds (Ws).

[0088] After a sufficient number of "Session Data" records have been collected, a session data record can be found with a start timestamp value close to the current system time when a prediction is needed. All records that fit that criteria can have the mean, median, or mean (or other statistical parameter) calculated (perhaps by taking into account the day of the week) to provide the following parameters: Baseline session duration seconds Reference power available period seconds Reference received power level average W Baseline total energy expenditure Ws (whole session)

[0089] Parameter names beginning with "criterion" are used to predict the future based on past conditions. These parameters (and possibly others) are used to derive useful metrics. Predicted energy demand (Ws) = Baseline total energy consumption (Ws) Predicted received energy (Ws) = Reference received power level average (W) * Reference power available period (s)

[0090] Using these metrics, it can be calculated how many seconds the receiver needs to remain in a location where it can receive radio power. With the appropriate calculations, and a prediction based on past similar sessions, the transmitter can send an email alert to the receiver. An example alert is shown below: You are leaving a wireless power source earlier than recommended. Your iPhone® is expected to last until approximately 10 PM with normal use. If you stay for another 9 minutes and get wireless power, you can extend it to 11 PM. Please transmit from your wireless battery.

[0091] This email can be generated like this: TOD is the time of day. Additional energy demand (Ws) = predicted energy demand (Ws) - predicted received energy (Ws) If the additional energy demand is greater than 0, Battery Energy (Ws) = State of Charge (%) * Storage Capacity (Ws) Predicted no-power period (s) = Reference session period (s) - Reference power available period (s) Predicted final power consumption (W) = Reference total energy consumption (Ws) / Predicted no-power period (s) Battery remaining seconds (s) = Battery energy (Ws) / Estimated final power consumption (W) Battery Time of Day (TOD) = Current Time Stamp (TOD) + Battery Seconds Remaining Additional demand time = Additional energy demand / Reference received power average Expanded Time of Day (TOD) = Start Timestamp + Base Session Duration Email (user ID, battery depletion time, additional demand time, extension time) End of if statement

[0092] The battery seconds remaining can be used to provide a value for the predicted TTD.

[0093] The above description relates to a method for measuring battery demand, which in one embodiment of the present invention is implemented in a receiver. The only aspect of these methods that must be implemented is the electronic circuitry that measures the demand metric.

[0094] For example, the electronic circuits described above for measuring state of charge, consumption, and received power are located in the receiver, as are the separate circuits disclosed for measuring the raw (actual) metrics (V[RF], A[RF], V[S], A[S], V[D], S[D]).

[0095] However, either the receiver or the transmitter can calculate the instantaneous, smoothed, or predicted battery demand.

[0096] Additionally, in the case of multiple receivers, different receivers may calculate different demand measurements. For example, one receiver may measure one of a raw metric, a battery demand metric, an instantaneous battery demand, a smoothed battery demand, or a predicted battery demand (collectively "battery demand"). Other receivers may measure other forms of estimating battery demand.

[0097] Once the receiver has calculated the battery needs, the next step is for the receiver to communicate this information to the transmitter.

[0098] In one embodiment of the present invention, this battery demand information is digitally encoded and transmitted wirelessly by the receiver to the transmitter as data packets.

[0099] The representation of numbers in various bit and byte schemes has a history of several decades. Generally, for numbers to be used with mathematical functions, it is necessary to know the range of numbers that occur and the precision desired for the numbers. The number of bits used in the encoding scheme affects both of these properties.

[0100] The receiver generates and transmits a battery demand packet, which contains information about the receiver's battery demand.

[0101] The battery demand packet is preceded by 1) a header containing a start byte, 2) a receiver ID that identifies which receiver is sending the data, and 3) a message type that indicates the battery demand type of the packetized information.

[0102] In one embodiment, the packetized information is encoded into a byte stream, and a modulator sends the bytes to a radio transmitter, with the entire message being a series of bits.

[0103] One embodiment encodes the packet header as follows:

[0104] Start bytes. These are a specific, immutable sequence of bytes that are unlikely to appear in real data, allowing the input scanner to recognize the start of a data transmission by continuously looking for this sequence of bytes. The number of bytes varies depending on the implementation, but often exceeds 8 bytes.

[0105] Receiver ID byte. This byte is assigned by the transmitter when the receiver introduces itself.

[0106] Message Type. These bytes disclose the particular encoding scheme used in the data section of the message. Two bytes provide more than enough for over 50,000 possible values. Provide for Message Type: In embodiments where different receivers measure battery demand differently, the message type also indicates which battery demand formula was used (e.g., smoothed storage capacity).

[0107] In one embodiment, the data portion of the battery demand packet includes one or more of three battery demand metrics.

[0108] Received power. For a suitable measurement figure for received power, one can expect a range of approximately 5 milliwatts (mW) to 5 watts, or approximately 1000. The accuracy required by the transmitter allows for a difference of approximately 10 mW, so 3 significant digits is sufficient. If the measurement is coded with 10 bits, the result is 3 significant decimal digits, or 1024 unique values. Adding more bits can improve the precision or range, or both, so representing the received power measurement as a 16-bit signed integer is more than sufficient, providing a range of values ​​from -32 W to +32 W in 1 mW increments.

[0109] State of Charge. Due to the difficulty of deriving an accurate state of charge value from the battery voltage, transmitters make do with just one significant digit in a range of 10 values. In other words, "percent full charge" ranging from about 10% to 100% in 10% increments is state of the art. This requires less than 4 bits of information.

[0110] Consumption. Consumption figures are likely to be in the range of about 0-500mA, and do not need to be as precise as in increments of about 1mA. This is a range of about 500 values, with an accuracy of less than 3 significant digits. Therefore, less than 9 bits of information are required.

[0111] In one embodiment, the receiver encodes all three metrics above. Once digitally encoded, the data is packetized.

[0112] In one packetization approach, two bytes are allocated to each of the three battery demand metrics as follows: Received power 2 bytes Charge status 2 bytes Consumption: 2 bytes

[0113] This adds up to 6 bytes for the battery demand information data packet.

[0114] In another packetization approach, the three battery demand metrics are represented by a minimal bit pattern. Received power 10 bits Charge status 4 bits Consumption 9 bits 23 bits total (or about 3 bytes)

[0115] The advantage of the second approach is that it reduces the data payload size by 50%. The disadvantage of this approach is that it slows down the computation at the transmitter because it must first encode the three bytes into the three metrics, a step that is required in the six-byte packet approach.

[0116] In another embodiment of the present invention, the receiver encodes and packetizes the raw battery demand metric rather than the higher level battery demand metric.

[0117] The raw metric voltage does not go beyond approximately + / - 30 volts, so resolving it to the nearest millivolt is sufficient. Thus, on a scale of 2 byte signed integers, you can read -32.767 volts to +32.767 volts in 1 millivolt increments.

[0118] The raw metric current does not go out to roughly + / - 3 amps, so resolving it to the nearest 100 microamps is sufficient. So, on a 2-byte signed integer scale, you can read -3.2767 to +3.2767 amp volts in 100 microamp increments.

[0119] So for six raw metrics (three voltages and three currents), a 12 byte allocation is sufficient.

[0120] The packets resulting from the raw metrics can be constructed as follows: header Start byte: 2 bytes, 16 bits Receiver ID 1 byte 8 bits Message type 2 bytes 16 bits data V[RF] 2 bytes 16 bits A[RF] 2 bytes 16 bits V[S] 2 bytes 16 bits A[S] 2 bytes 16 bits V[D] 2 bytes 16 bits A[D] 2 bytes 16 bits Total 17 bytes, 136 bits

[0121] The tradeoff between packetizing battery demand metrics versus raw metrics is packet size (larger size means longer transmission time) versus computation cycles (larger computations mean higher overhead). Packetizing battery demand metrics saves transmitted bytes but pushes computation to the receiver, while the opposite is true for packetizing raw metrics.

[0122] Battery rating metrics (maximum charge and storage capacity) are useful for calculating battery demand, but the values ​​of these parameters tend to change relatively slowly, making it wasteful for the receiver to transmit these values ​​every time a fluctuating battery demand value is transmitted.

[0123] Battery rating metrics slowly decrease over months and years of use. As mentioned above, these parameters can be periodically recalculated based on careful receiver measurements or using simple approximations such as linear predictions based on calendar dates.

[0124] The minimum battery rating packet contains these values. header Starting byte: 2 bytes Receiver ID 1 byte Message type 2 bytes data Maximum charge capacity 2 bytes [0..65535]mW Storage capacity 2 bytes [0..65535]Wh

[0125] Battery rating packets are used to accommodate infrequent but important updates to these values. However, because these are rare packets, one multi-purpose packet can serve more than one purpose by loading these special packets with many fields.

[0126] For example, the periodic battery rating packet may also include many other parameters related to the receiver. Device ID A specific device, possibly a serial number Manuf Manufacturer name Part # SKU or Part Number Lot Lot number for tracking Fixes Hardware / Software fix level Special number for MAC communication Device type: Mobile phone Battery Type Part# Maximum charge capacity 2 bytes 0..65535mW Storage capacity 2 bytes [0..65535Wh

[0127] The receiver wirelessly transmits the battery demand packet to the transmitter, either by using a bypass or by adding the packet to the beacon signal.

[0128] In a preferred embodiment, the receiver generates a beacon signal, the purpose of which is to announce the receiver's presence to the transmitter.

[0129] Beacon signals are subject to many strict constraints on timing, duration, and repetition rate. Every bit of data added to the length of a beacon signal reduces the time available for the transmission of wireless power from the transmitter. Therefore, the smallest amount of data possible should be included with the ID portion of the beacon signal. In one embodiment, the beacon is designed with a minimum start byte and no message seed or data portion; a bypass is used for the latter.

[0130] In yet another preferred embodiment, a bypass is used for the entire battery demand packet.In another embodiment, a battery demand packet is transmitted with each beacon.

[0131] The battery demand packet sent as a preamble to the beacon is sent every time a beacon is transmitted, which in one preferred embodiment may be about 10 milliseconds.

[0132] Packets transmitted on the side path are not constrained by beacons and can be transmitted at any frequency, including continuously, especially if the frequency is changed from that used by the transmitter to deliver radio power to the receiver.

[0133] As mentioned above, battery rating packets are sent much less frequently (measured in seconds) than battery demand packets.

[0134] In one embodiment, the receiver sends a battery full message to the wireless power transmitter when it is full, indicating that the receiver does not need the transmitter any more at that time and does not want to burden the transmitter with additional battery demand packets until a demand occurs.

[0135] In another embodiment, when the battery is full, the receiver simply stops all communication to the transmitter, which then assumes that the receiver has left the area.

[0136] In both embodiments, the receiver further senses a need for wireless power and then detects the presence of a transmitter. Once this is done, the normal induction process that all receivers must go through can be performed, following which the receiver will begin transmitting battery demand packets as described herein.

[0137] If multiple receivers transmit battery demand packets wirelessly, the next step is for the transmitter to receive these packets.

[0138] The transmitter has at least one central collection point for receiving battery demand packets, which may be a data controller within (or associated with) the transmitter. The transmitter receives wireless battery demand packets from zero, one, or multiple receivers.

[0139] In a typical installation, multiple wireless power receivers may be placed in close proximity to at least one wireless power transmitter, and the multiple receivers may then transmit battery demand packets to a data controller.

[0140] Interference between multiple uncoordinated transmissions must be prevented. Packets can be coordinated by having the wireless power transmitter poll each receiver for battery demand packets. Alternatively, multiple many-to-one messaging schemes, such as CSMA-CD, are well known in the data communications art.

[0141] Generally, a radio transceiver within the data controller communicates with a receiver. The transceiver receives the data line and presents a signal that is converted into bits by a data detector, possibly passed through decoding circuitry, and comes out as a stream of bytes. These bytes are moved to a data input channel of a processor that looks for a particular series of bytes that constitutes the start of a data block header.

[0142] Typically, as mentioned above, the header will contain details such as a media access control byte (MAC address) or receiver ID so the controller knows which receiver sent the message. The final header byte usually encodes the message type. Once this is found in the data stream, the remaining bytes take on meaning depending on the protocol that assigns what the bits mean in a particular message type.

[0143] This packet parsing approach is standard for many protocols and there are numerous examples in the art.

[0144] Once the message types are identified, the specific data parameters under which those messages are designed to be transmitted can be retrieved from the data stream.

[0145] Using the message type from the packet header, the data controller can extract a particular encoded battery demand (eg, raw or battery demand metric, instantaneous, smoothed, or predicted).

[0146] A large number of message types result from a variety of message types that are similar to each other or contain similar types of data, but differ in encoding, higher level meaning, or purpose.

[0147] The data controller must normalize the variable data into a common demand format, which in the preferred embodiment is TTD.

[0148] In one embodiment, all receivers always transmit their raw metrics in the same way and with the same encoding, using the same message type. In this case, the TTD is calculated by dividing these by 1 using the formula above. It can be calculated from the readings.

[0149] In another embodiment, different message types may transmit the same required data, but with different encoding or higher-level meanings with respect to the raw data represented by the lower-level raw metric. For example, all receivers use the same function for battery demand (e.g., TTD), but some receivers transmit the raw metric, some receivers transmit the battery demand metric, and yet other receivers transmit the TTD.

[0150] In this case, each receiver is transmitting complete information to calculate the value of TTD. For battery demand packets that contain TTD, no further processing is required. For packets that contain battery demand metrics, TTD is calculated using the function described above. For packets that contain raw metrics, the formula described above is used to convert these values ​​to battery demand metrics. The TTD function is then applied to calculate the value of TTD.

[0151] In a third embodiment, different receivers use non-coexisting measurement sets or implement special features that rely on unique capabilities of custom receiver hardware or software. In these cases, some means of normalizing the data is required.

[0152] For example, if a receiver measures and communicates only consumption or state of charge, the transmitter must make estimates for the missing data in order to normalize those measurements to TTD. These estimates can be derived from manufacturer data on the baseline performance of the receiver battery.

[0153] Once the battery demand packets have been received and normalized to a common reading (preferably TTD), the transmitter is ready to optimally meet these demand requests.

[0154] Any type of wireless power transmission approach can be used in the present invention, for example: Phased microwave arrays, such as those developed by OmniLectric Ultrasound, such as that developed by UBeam Magnetic resonance, such as that developed by Witricity Infrared lasers, such as those developed by Powerbeam Atmospheric energy capture, such as that developed by PowerCast Any other wireless power transmission technology

[0155] The present invention applies to all wireless transmission technologies because they all can deliver power via pulses, some of which are constrained by the choice of pulse modulation approach (e.g., frequency modulation instead of phase, time, or directed transmitters).

[0156] However, the present invention applies to all means of generating at least two pulses of wireless power, each pulse being transmitted to one of two receivers located at different locations.

[0157] However, the preferred embodiment described below employs phased microwave array technology (described in US Pat. No. 8,159,364 to Ominiectric) which uses phased pulsing in the transmitter.

[0158] The ability to direct power from multiple antennas in a phased array to a single receiver has many advantages. One advantage described here is the ability to direct specific amounts of power to different receivers based on demand.

[0159] It is well known in the art that power can be transmitted as a series of pulses that are collected and smoothed by one electronic circuit to provide a constant power source to another electronic circuit.

[0160] Power from one source can be distributed to multiple destination circuits by sending individual power pulses to different circuits that smooth the pulses.

[0161] Proper pulse distribution is achieved by transmitting an optimal number of pulses to each receiver, which recovers power from the transmitted pulses to obtain the power it needs for use as needed.

[0162] When different power requirements must be met, each receiver can be targeted with a power pulse sufficient to meet the receiver's specific requirements. If all power pulses are the same size, receivers requiring more current (e.g., receivers with low TTD) can receive more pulses, and receivers requiring less power (e.g., receivers with high TTD) can receive fewer pulses. Other schemes can be employed, for example, when the power pulses are of various sizes (e.g., individual pulses can be represented as multiple minimum pulses).

[0163] The transmitter must know the power needs of all receivers in the receiver group before it can calculate the pulse distribution.

[0164] This information is obtained from the receiver itself and the collected information allows the total power delivered and pulse distribution to be calculated.

[0165] Note that the transmitter is collecting information about which receivers need to receive power and distribute pulses.

[0166] FIG. 7 shows an example scheme 70 in which a transmitter is configured to communicate with four receivers A, B, C, and F. Receiver A transmits a beacon pulse 71, followed by receiver B transmitting two beacon pulses 72 and 73. Every beacon cycle 74, the transmitter transmits four pulses to these receivers. For the first beacon 71 transmitted by A, A receives all four pulses 75 because no other receivers indicate a battery need. For the second beacon 72 transmitted by B, all four receivers represent approximately equal battery needs. Therefore, the transmitter distributes four power pulses 76, 77, 78, and 79 to the four receivers B, A, C, and F, respectively. One power pulse is directed to each of the four receivers.

[0167] In one embodiment, the transmitter transmits, for example, 100 pulses per beacon cycle. The transmitter allocates these 100 pulses among the receivers. The number of pulses sent to each of these receivers can be calculated as follows: #Pulses allocated to receiver i = round((demand of receiver i / total demand of all receivers) * 100)

[0168] If demand is expressed as TTD, a different allocation function is needed, e.g. Function: TTD2PULSE Convert a list of TTD values ​​to a list of pulse counts GIVEN INPUT ARRAY=TTD[1...N] CALCULATE OUTPUT ARRAY=NUMPULSES[1...N] NORMALISE=SUM(TTD[1...N]) WEIGHT[1...N]=NORMALISE / TTD[1...N] WEIGHTSUM=SUM(WEIGHT[1...N]) PULSRFACTOR=WEIGHTSUM / MAXPULSES NUMPULSES[1...N]=WEIGHT[1...N]*PULSRFACTOR Another final line NUMPULSES[1...N]=MAX(1,WEIGHT[1...N]*PULSRFACTOR)

[0169] This method distributes pulses among receivers according to their respective battery demands, expressed as TTD.

[0170] The two allocation schemes described above are merely examples, and the present invention supports any other approach to allocating available pulses to receivers according to their respective battery demands.

[0171] The wireless power and data controller and transmitter cooperate with multiple receivers to deliver power to those receivers. The following section describes one embodiment of a transmitter that interacts with zero, one, or two receivers in accordance with the present invention.

[0172] The receiver can detect when it gets a power burst from the transmitter. Each power burst contains multiple power pulses. Each pulse can be directed to one of multiple receivers. In one preferred embodiment, for example, there are 100 power pulses per burst, although any ratio is acceptable in the present invention.

[0173] Figure 8 shows a number of power pulses within a burst, i.e., a power burst 81 consisting of 100 pulses. Consider providing 26 of these power pulses to nine receivers. Receiver #1 receives four power pulses 82, receiver #2 receives seven pulses 83, and receiver #9 receives three pulses 84. As mentioned above, this discrepancy in pulse distribution between the receivers is due to differences in the battery demands of each receiver.

[0174] Although a power pulse contains energy directed to a specific receiver, not all power bursts need to contain a power pulse for every active receiver, in other words, a particular receiver can be excluded from a power burst by not having a power pulse allocated within that particular burst.

[0175] The transmitter uses a bypass to communicate beacon requests to the receivers, asking the receivers to identify themselves and begin expressing their power needs.

[0176] All receivers within range of the transmitter receive all beacon requests. However, each beacon request is directed to only one receiver. This is achieved by using a unique receiver ID in the message. Each receiver within range checks to see if a particular beacon request is serviced.

[0177] If two receivers request power at the same time, collisions must be avoided. This is achieved by having each receiver ignore one beacon request and respond to the next. For example, with two receivers, one receiver can skip even-numbered requests and the other receiver can skip odd-numbered requests.

[0178] In the example below, the receivers send their battery demand packets as part of their beacons. As mentioned above, this approach is one embodiment of the present invention. In another embodiment, the receiver bypass sends a battery demand packet regardless of the beacon.

[0179] Consider the first simple case, where there are no receivers in the vicinity of the transmitter. A simple scheme 90 corresponding to this case is shown in Figure 9. A single wireless power transmitter 91 broadcasts a series of general announcements ("timed announcements") 92 at time intervals 93 (e.g., every 5 seconds). Anticipating eventually finding a nearby receiver, the transmitter terminates with timed announcements 92 from a single antenna 94, called a "proxy." The special antenna proxy 94 is part of a cluster of antennas 95 at the transmitter 91. The timed announcements 92 can be received by a potential receiver "client" 96. Communication scheme 90 can be considered an example of the case where no receivers are present or do not have the corresponding power. In either case, no signal is returned from the receiver.

[0180] FIG. 10 shows another example of transmitter-receiver communication. In communication scheme 100, client receiver 96 eventually disappears from the environment. The receiver receives a "timed announcement" 92, waits a random amount of time, and responds with a "random interruption" 101 or an "insufficient" message 102. In this communication scheme 100, the transmitter determines (from the content of the "insufficient" message) that the sender is not authorized to receive power. In this case, transmitter 91 replies with a "cannot help" message 103. Client receiver 96 receives this message and marks the transmitter and its structural modification level as unavailable. This prevents client receiver 96 from unnecessarily contacting transmitter 91 again until reconfiguration occurs (which may occur when the receiver receives new authorization to receive power).

[0181] Figure 11 shows another example of transmitter-receiver communication. Communication scheme 110 illustrates the successful introduction of client-receiver 96 into the transmitter's list of authorized receivers. As described above, the receiver receives a "timed announcement" 92, waits a random amount of time for a "random pause" 101, and responds with an "insufficient" message 102. For this receiver, the transmitter 91 determines that the receiver should indeed be allowed to receive power. In this case, the transmitter 91 responds with a receiver ID selected from a pool of available receiver IDs. Once this receiver ID is selected (the order is irrelevant and must be different), for example, in the communication scheme 110 shown in Figure 11, it announces to the receiver that it is "client #3" 111.

[0182] The receiver receives this message and returns a "My Story" message 112. In one embodiment, this message is a Battery Rating Packet, which is compiled and sent by the receiver after being assigned a receiver ID by the transmitter 91.

[0183] Once the transmitter 91 receives this packet, it determines how to treat the receiver and sends a "please send a beacon" message 113 to the receiver.

[0184] The exemplary communication scheme 120 shown in FIG. 12 describes the case where a successfully authorized client-receiver 96 interacts with a transmitter 91 that does not have a receiver within range.

[0185] Upon receiving the transmitter's "send beacon" message 113, the client-receiver 96 transmits a first beacon 121. The first beacon 121 causes every antenna in the transmitter array to determine the exact phase angle of the receiver's signal at that antenna. This allows all antennas in the transmitter 91 to capture phase information and calculate the complex conjugate of the phase angles of each antenna in the cluster. These phase angles can later be used to transmit a single pulse of wireless power 122 from all those antennas back to the receiver.

[0186] The phase angles of the transmissions returning from all antenna elements are arranged to peak as they pass through the location of the receiver's receive antenna (and nowhere else by design), thus providing a power pulse to a receiver with circuitry designed to capture the energy and derive power from it.

[0187] If the receiver detects that it has received one or more power pulses in the burst, it transmits a second beacon 123 and then receives another power burst 124. This interaction continues until the transmitter 91 stops delivering power bursts.

[0188] When a receiver in "beacon send" mode detects an unknown power pulse, it waits for another "send beacon" command 125 from the transmitter proxy. The "send beacon" command 125 means "send one beacon" and also has a skip factor, which instructs the receiver not to respond to every power pulse with a beacon, but to skip some number of power pulses before sending a beacon.

[0189] Now consider the case where at least two receivers are waiting for a beacon request. In the example communication 130 shown in Figure 13, communication begins with the interaction of one transmitter 91 and one client receiver 131, called "A." Client receiver A 131 detects the power burst 132 and transmits a beacon signal 133 requesting another burst with a zero skip factor.

[0190] The transmitter 91 finds a time to send another "Scheduled Announcement" 134. A second client receiver B 135 (e.g., receiver #6) receiving the "Scheduled Announcement" 134 delays for a random period and "Random Interrupt" 101, responding to the request with a "Missing" message 102.

[0191] At this point, the transmitter 91 determines that the second client receiver B 135 is authorized to receive the power pulse, so the wireless transmitter 91 selects another receiver ID from the free receiver ID pool and uses the proxy 93 to send a "This is receiver #6" message 136.

[0192] During this period, client receiver A 131 transmits a beacon message 133 and anticipates another power burst in response. Because the transmitter is configuring a second client receiver B 135, this beacon is ignored. Client receiver A 131 notices the missing power burst and changes mode. By transmitting a beacon instead of being solicited, this new mode waits for a beacon request before transmitting. The new mode also skips a configurable number of beacon requests before responding.

[0193] Returning to the second client receiver B 135 (receiver #6) immediately after receiving the "This is receiver #6" message 136, it responds by sending its own "My Story" message 137. Upon receiving this packet from the second client receiver B 135 (receiver #6), the wireless power transmitter 91 has two active client receivers, client receiver A 131 and client receiver B 135, that require power and are both waiting for a beacon request.

[0194] Continuing with the communication example 130 shown in FIG. 13, immediately after transmitter 91 solicits and receives a beacon request from each of two active client receivers (client receiver A 131 and client receiver B 135), the two beacons set the phase relationship of all antennas. To determine which receiver is the most likely to be beaconed, a power pulse can be directed at either desired receiver. Both receivers will be waiting for a power pulse (from somewhere within the power burst) and will be expected to ignore the first power burst and not beacon back, as if they were both aligned.

[0195] A way is needed to have one receiver precede the other, so that one responds to odd bursts and the other responds to even bursts. Otherwise, both respond to odd (or even) bursts, and their beacons interfere. The way to have one receiver ignore a burst is to have no pulse within the burst for that receiver. Thus, as shown in FIG. 13, the entire power burst is directed only to client receiver A 131, which detects the pulse and skips the beacon it transmits accordingly. The second client receiver B 135 (receiver #6) does not receive the power pulse within that power burst, so it continues to wait for the first power burst. The second client receiver B 135 (receiver #6) is ready to skip the first power burst.

[0196] Next, a second power burst containing power pulse 138 is transmitted to both client receiver A 131 and the second client receiver B 135 (receiver #6). Both receivers check their skip states and find that client receiver A 131 has already skipped enough (once), while the second client receiver B 135 (receiver #6) has not yet skipped. Therefore, the wireless power transmitter receives a beacon from client receiver A 131, which is currently skipping an odd-numbered power burst. The next power burst will be either even or odd, and will receive a beacon from either client receiver A 131 or the second client receiver B 135 (receiver #6) based on which skip factor it is commanded to use.

[0197] A skip factor of more than two can be used. In the case of three receivers, for example, a skip factor of two would cause each receiver to skip transmitting a beacon if either of the other two receivers is receiving the beacon. This scheme can work with multiple receivers, but it relies on unimpeded reception of the beacon from each receiver.

[0198] In another embodiment, receivers and transmitters can interact by having the transmitter request beacons from receivers it recognizes, eliminating the need for a skip factor. The receiver responds to a "timed announcement" with a data packet ("my story") that describes itself. A specific beacon request naming that receiver can be responded to at any time determined by the transmitter. Once a receiver responds with a beacon, the receiver receives power from the pulse in the next power burst. This is an inefficient protocol because time must be spent requesting beacon transmissions from each receiver rather than having them wait their turn.

[0199] In a preferred embodiment, the normalized battery demand data provided by the data controller to the transmitter is TTD, allowing the transmitter to compare receivers by TTD, including instantaneous, smoothed, and predicted TTD.

[0200] In another embodiment ("1Bit Directive"), the demand data is either "1" or "0", where "1" corresponds to more power ("Power Up") and "0" corresponds to less power ("Power Down"). This alternative embodiment provides less information about the battery demand, but is advantageous in preferred embodiments because it is less complex.

[0201] The 1-bit directive allows the receiver to monitor the sign (+ or -) of the stored battery current and request more power when current is flowing out of the battery, and request less power when power is flowing into the battery.

[0202] The receiver also requests a power reduction when the maximum charge is exceeded and when the charge state is "full" (e.g., above 100% or 90%).

[0203] The receiver task can be expressed in Program Design Language (PDL) as follows: If battery current > 0, then If battery current > maximum charge Demanding "power reduction" or If the charging state is full Demanding "power reduction" or Demanding "increased electricity" End of if statement End of if statement Demanding "increased electricity" End of if statement

[0204] The above code increases power demand until the maximum charge is exceeded or the charge state is full. This is done regardless of fluctuations in consumption. The code snippet only needs to be run once per beacon. Electronic circuitry can easily implement this code using circuit design techniques known in the art.

[0205] A minimal packet contains just the necessary information, including a start byte, a receiver ID, and possibly one or two message types. Message types are pre-assigned numbers. These numbers usually refer to a particular layout of the data section of the message.

[0206] One possibility is to have a layout with one bit in the data section that carries the power up or power down directive. Alternatively, the header can adopt a message layout with no data bits in the data section. Instead, the message type itself carries the power up or power down directive.

[0207] A packet comprises one or more of a start byte, a receiver ID, a message type byte, and data bytes.

[0208] Start Byte: This can be two bytes containing, for example, "0xA55A", which may be a rare long sequence.

[0209] Receiver ID byte: This receiver ID can be anything that is unique. In the IEEE802 format, assume that a particular receiver has 01:23:45:67:89:AB. However, this kind of ID is too long for a beacon. With the protocol described above, the receiver ID is assigned by the wireless power transmitter. One byte can uniquely identify over 200 receivers. For this example, the byte "0xAB" is chosen.

[0210] Message Type: Two bytes are allocated to convey the 1-bit directive layout. It is efficient to have unrelated, frequently used message types with increased and decreased power versions. Alternatively, message type 0x62 is the message type for 1-bit directives that have one bit of data in the layout.

[0211] Data Byte: In another 1-Bit directive embodiment, the packet contains a data byte. The minimum count is likely to be 1 byte, so power up can be coded as "0x01" and power down as "0x00", thus carrying more than the 1 bit of information needed to be transmitted.

[0212] An example of a 1-bit directive message (in hex) is "A5 5A AB 62 01".

[0213] This message is split into two start bits "A5" and "5A", followed by the receiver ID "AB" (assigned by the wireless power transmitter) and the message type "62". The #62 message type is known to have a single byte containing a single bit in the least significant (right-most) position. The code to extract message 62 is as follows: Power Increase = ("0x01" == Payload (O))

[0214] Payload is a byte array received from the data portion of the receiver beacon. There is only one payload byte at zero offset. If payload is equal to "0x01", then the requested power increase is true, or the requested power increase is false (which is actually a requested power decrease, which is equivalent in this scheme). The outline of the packet contents is as follows: Receiver # Receiver ID of the receiver to communicate with Increase in electricity: The truth behind the demand for increased electricity

[0215] This information is provided to the transmitter, which keeps track of each receiver's requirements.

[0216] If a one-bit up / down signal is transmitted by the receiver at every beacon, the result can be thought of as similar to a pulse-width modulated feedback signal.

[0217] In the Program Design Language (PDL) format, the sender performs the following steps: For each receiver, If the power is increased [receiver] Increase pulse count [receiver] or Decrease pulse count [Receiver] End of if statement Next Receiver

[0218] Number of pulses [receiver] is the number of power pulses the transmitter currently allocates to the receiver.

[0219] In one embodiment, for example, 100 beacons per second and 100 pulses per beacon cycle are obtained from all receivers in the area (other counts are possible, 100 was chosen as an example for ease of calculation).

[0220] With 100 beacons per second, a single receiver can request a power increase. In response, the transmitter smoothly increases or decreases power from 0 to 100 pulses per second. With appropriate protection, the "increase" and "decrease" codes can be prevented from exceeding the 100 pulse allocation. For example, if 20 receivers compete, each receiver will cover the range within 5 seconds in this example. This is a sufficient response time.

[0221] Once the transmitter knows the number of pulses allocated to each receiver, if the total number of allocated pulses ("total pulses") is less than or equal to the available pulses, the transmitter allocates the pulses as follows: Pulse = I For each receiver, (I=0; I<number of pulses [receiver]; I++) Receiver pulse [pulse++] = receiver Next I Next Receiver

[0222] It starts by allocating pulses from the first power pulse in the burst. The code goes through the receiver list and allocates to each subsequent receiver the number of pulses it is allotted.

[0223] The 1-bit directive approach to pulse distribution can also be called "ramp dither." For example, if a mobile phone is left unused overnight near a transmitter, the battery will be fully charged in the morning, and the pulse rate will hover around zero power at the receiver.

[0224] When a cell phone is turned on in the morning, battery current immediately begins to drain from the cell phone's circuits, requesting more power. These requests continue until the transmitter power level rises enough to exceed the demand from the receiver electronics, causing a request to decrease power.

[0225] The transmitter increases the number of pulses for its receiver up to a certain value, then hovers around a level that just provides the required power. If the increase process goes on too long, the charge state no longer indicates "full" and an additional power increase is required until the charge state returns to "full."

[0226] At the transmitter, the total number of pulses exceeds the total number available (eg, 100 pulses in the example above). Several approaches are possible to reduce the total number required.

[0227] One approach is to divide the total pulses by a factor of, say, 100, to get a "division factor." The number of pulses for each receiver is then divided by that factor to determine the actual number of pulses transmitted. This results in all receivers being equally underpowered, which is problematic for some receivers.

[0228] Soon all underpowered receivers will request all 100 pulses. This results in all receivers receiving the same amount of power, which may cause problems for some receivers. However, a reasonable response would be for, say, 20 receivers to receive 1 / 20 of the total available radio power.

[0229] Another approach is for the code to iteratively go through the list, subtracting 1 from every receiver's allocation until the total number is 100. In this example, a 10 millisecond burst of power pulses can be sent.

[0230] An improvement is to not allow any receiver's allocation to drop below one pulse. A further improvement is to not downgrade the allocation of units that do not have an internal storage, such as a local battery. This "no battery" condition is known to each receiver and can be tested for with a "can be downgraded" code, etc. While total pulses > 100 Receiver = Next (Receiver) If total pulses > 100 If demotable [receiver] Pulse[receiver]=Max(1, Number of pulses [receiver]-1) Recalculate the total pulses End of if statement End of if statement Wend

[0231] This starves all receivers of power that can be downgraded but are equally so. Receivers without internal storage will receive all the power they request, which is the necessary response. One drawback is that the receiver will no longer recharge its battery, creating a graceful failure mode.

[0232] However, a transmitter surrounded by an RF-absorbing environment and many demanding receivers can become overwhelmed, causing high-power receivers to discharge, providing some indication to the transmitter owner that more power is being demanded than the transmitter can supply.

[0233] Embodiments of the present invention that employ predicted battery demand can perform a much more detailed analysis than the other embodiments described above. When predicted usage depends on the transmitter rather than recent usage (e.g., instantaneous battery demand vs. smoothed battery demand), differentiating features of the receiver become more important.

[0234] Below we describe additional parameters that describe these different receiver characteristics and categorize receiver types by power usage. The purpose of this information is to allow the transmitter to collect a richer model of the receivers it serves.

[0235] The main advantage of performing this rich predictive modeling and relying on this model for pulse allocation within a power burst is that it reduces the amount of computation required by the transmitter for each cycle of power burst delivery.

[0236] A drawback of relying on an a priori model of receiver power usage occurs when actual usage deviates significantly from the model.

[0237] In addition to the battery demand and battery rating metrics mentioned above, the predictive modeling is optimized using additional parameters.

[0238] The predictive parameters described below are sufficient to schedule a series of power pulses to be sent to the various receivers, providing a specifically tailored power level for each receiver. If these parameters are available from all receivers to the transmitter, the transmitter can use the values ​​to determine the optimal distribution of the available power pulses.

[0239] Each receiver receives several power pulses necessary to power the receiver and recharge the battery (if one is present) within the time that the receiver expects to receive wireless power, regardless of battery size or current charge level, but at a safe recharge rate to cover anticipated short-term future use.

[0240] Some receivers are permanently mounted on shelves near the transmitter. Other receivers, especially portable receivers, are never used in remote locations with access to wireless power. Some portable receivers access wireless power only for short periods of the day, while others access it periodically overnight.

[0241] The following power availability parameters characterize the receiver's access to wireless power: Wireless available power [...] minutes / day Average duration of wireless power access [...] minutes Number of power access sessions [...] per day

[0242] Preferably, these parameters are also collected and maintained within the receiver itself.

[0243] Some wireless power receivers draw low power, while others draw high. Some receivers draw power continuously to operate throughout the day, while others draw power only when used by a person or when a sensor (or other receiver) is activated. These intermittently powered receivers typically have short or long sessions of power consumption, and the rest of the time they consume very little standby power or no power at all.

[0244] The following power consumption parameters characterize the power consumption of a wireless power receiver: Reference power consumption [...] watts Duration [...] minutes / day Baseline power consumption average session duration [...] minutes Number of power consumption sessions [...] per day

[0245] Preferably, these parameters are measured and maintained within the receiver itself and transmitted on demand to the transmitter when planning the distribution of power pulses.

[0246] Since some receivers may want to manage the power from the transmitter, additional demand parameters can be included. Please provide this level of power [...] watts Transmitter decides by itself [Y / N]

[0247] In one approach, the promise that the requested power level is "N" in this field and "Y" in that field is established, and the transmitter can select the power level to be supplied to the receiver.

[0248] Different types of receivers, categorized by power availability and consumption patterns, tend to generate different types of prediction parameters.

[0249] Receivers that do not have their own means of storing power must be constantly supplied with sufficient power by a wireless power source. The location of these receivers is constantly known to the source, so that wireless power can be directed to the receiver's location. Transmitters can retain their location data even after the mains power is cut off for an extended period, such as during a power outage. Thus, all location information for fully enslaved receivers is stored in the transmitter's non-volatile memory. These receivers can be identified by a "total energy storage capacity" parameter, which is usually zero. One example is an electric water pump that keeps water in the pipes warm by circulating it through a water heater.

[0250] Receivers that must be operational at all times must be supplied with sufficient power at all times by either the transmitter or a large backup battery. This is a similar type of receiver to a fully dependent receiver, except that such receivers typically have local energy storage to power the beacon, ensuring that they receive power from the transmitter when available. A possible example is an oxygen concentrator (a medical receiver that helps with breathing) with a battery backup for use during a power outage.

[0251] Depleted receivers have already exhausted their power reserves and are forced to shut down. These receivers receive priority high-power pulses to quickly recharge, but require special handling.

[0252] Typically, a beacon signal transmitted by a receiver is received by a nearby wireless power source, which then requires special processing to respond by transmitting power to the receiver's location. Because these receivers are portable, their location is unknown. A depleted receiver has no available power to generate a beacon, so a nearby transmitter can sense the receiver. Instead of the beacon "moving the receiver to the power source," the receiver must be moved to the power source.

[0253] In this case, receivers without reserve power can be handled by having at least one specific location that is always supplied with radio power. When a depleted receiver is placed in this "resurrection spot," radio power is supplied to the receiver until it is able to generate a beacon. At this point, if immediate use of the receiver is required, the receiver can be used while being charged as long as it is within range of the radio power source. Even if the receiver requires high power with a fast charging requirement, it is expected that the transmitter will be able to provide enough power to charge and power the receiver while it is within range.

[0254] Receivers with nearly depleted reserve power begin to charge when they enter the wireless power field. This occurs when a beacon signal is detected by a transmitter that can power the receiver. These receivers are given power priority over other receivers that have enough power to operate. Because the current reserve capacity parameter is important for these receivers, a train of quick-charge power pulses can be provided.

[0255] Receivers with high power requirements must be allocated larger power slots from the available power pole than receivers with lower power demands. As technology matures, more power becomes available. Receivers with continuously high power requirements, such as hair dryers, require a stable allocation during use. When a transmitter is supplying power near its capacity, some receivers can tolerate fluctuating power levels and take on the load from the total power output as needed. A good example of this is an electric car charging in a garage. A bad example is a hair dryer that seems to randomly revert to a low-temperature state to cope with the limited capacity of its wireless power source (a hair dryer is likely to be considered defective by most users). The "reference power consumption" parameter is important for identifying these receivers. A hair dryer might want to claim a state such as "immediately supply 1000W without judgment."

[0256] Some receivers, such as radios and televisions, are always in use. As mentioned above, such always-on reception requires providing a stable allocation of power slots. The "average duration of a baseline power consumption session" is important in identifying these receivers.

[0257] Some receivers are used heavily throughout the day, while other receivers, even the same model, are used less. Imagine two identical cell phones: one owned by a stockbroker who always keeps his phone on him, and the other owned by a retiree. Both could reach a public access transmitter with batteries with 50% remaining capacity. That is, one might have four hours' worth of reserve capacity, while the other has four days'. The receivers report the level of baseline use and minutes / day, as well as the reserve capacity. With this information provided to the transmitter, both could still have 80% reserve capacity, even if the stockbroker's phone receives more power.

[0258] Some receivers have limited or intermittent usage patterns. may be used frequently but intermittently, for a few hours a day. Stud finders may only be used every few years. This type of receiver would best be recharged only when it reaches a certain discharge level. Some battery technologies, particularly NiCad batteries, do not respond well to being kept on a charger continuously. Appropriate algorithms used by transmitters can handle these batteries and charge them as needed.

[0259] Some homes use their home intercoms infrequently. If designers anticipate the intercom's wireless power usage, they can use a tiny battery that's enough to send one or two beacons. A "please provide 100mW now" update can be sent whenever the intercom is called upon.

[0260] Electroluminescent night lights can be kept lit without a battery, and their illumination can be controlled by varying the average number of power pulses delivered per second.

[0261] The motion sensor and wall clock will not move out of range of the wireless power.

[0262] For a vacuum cleaner stored in a shed with no nearby wireless power, the wireless power receiver can power up the beeper when the battery needs recharging. The receiver can then be brought back to the enclosure (near a wireless power source) to be recharged, even while in use. A power pulse distribution device could indicate, for example, a low "0 minutes / day of available wireless power" or "4% current reserve capacity," and calculate an appropriate high power rush limited by the "maximum continuous charge of this battery."

[0263] For receivers stored in remote locations, a status repeater allows the receiver to transmit the battery charge level to the transmitter (the repeater only retransmits data to the wireless power transmitter, not power to the receiver). The transmitter then notifies the user that the remote receiver needs charging. The remote status repeater can communicate with the transmitter using power line communication or Wifi, the same wireless communication technology that the transmitter uses to communicate with the receiver.

[0264] While the present invention has been described with reference to several embodiments, it is understood that alterations, modifications, variations, substitutions and equivalents are also within the scope of the present invention, many of which may be implemented alone or in various combinations.

[0265] It should be noted that there are many other ways of implementing the method and apparatus of the present invention, and it is therefore contemplated that the following appended claims will include all such changes, modifications, variations, substitute equivalents, and the like that fall within the true spirit and scope of the present invention.

Claims

1. 1. A method of operating a wireless power transmitter and one or more wireless power receivers, comprising: receiving, by the wireless power transmitter, one or more signal-encoded data indicative of at least one battery demand metric from the one or more wireless power receivers; the wireless power transmitter allocating wireless power pulses according to the data indicative of the at least one battery demand metric; the wireless power transmitter modulating one or more phases of the wireless power pulses to maximize their power for reception at each location of the one or more wireless power receivers; the wireless power transmitter delivering the wireless power pulses to the one or more wireless power receivers in accordance with the allocating and modulating steps; the one or more wireless power receivers are configured to detect missing wireless power pulses or one or more skipped power pulses; The method further includes the step of the wireless power transmitter receiving at least one beacon signal transmitted by the one or more wireless power receivers in accordance with a skip factor and in response to detecting the missing wireless power pulse or the one or more skipped wireless power pulses.

2. The method of claim 1, further comprising a step in which the wireless power transmitter receives a beacon signal from the one or more wireless power receivers.

3. The method of claim 2 , wherein the modulating step further comprises modulating the one or more phases of the wireless power pulses according to a received phase of the beacon signal.

4. The method of claim 2 , wherein the transmitting step further comprises transmitting the wireless power pulse in response to receiving the beacon signal.

5. receiving the beacon signal includes, in the method, first receiving the beacon signal from the one or more wireless power receivers before the transmitting step is performed; the one or more wireless power receivers are further configured to transmit the at least one beacon signal in accordance with the skip factor; The method of claim 2 , further comprising the step of secondly receiving the at least one beacon signal transmitted by the one or more wireless power receivers in accordance with the skip factor.

6. The method of claim 5 , wherein the skip factor instructs the one or more wireless power receivers not to respond to any wireless power pulses.

7. The method of claim 6 , wherein the skip factor instructs the one or more wireless power receivers to skip a number of wireless power pulses before the at least one beacon signal is transmitted.

8. The method of claim 2, further comprising a step in which the wireless power transmitter transmits a beacon request signal toward the wireless power delivery environment.

9. the one or more wireless power receivers are further configured to transmit the beacon signal in response to the beacon request signal; The method of claim 8 , further comprising processing the beacon signals transmitted from the one or more wireless power receivers.

10. The method of claim 9, further comprising a step in which the wireless power transmitter determines the presence of the one or more wireless power receivers in the wireless power delivery environment based on the beacon signal.

11. The method of claim 1 , wherein the one or more wireless power receivers comprise a plurality of wireless power receivers.

12. 12. The method of claim 11, wherein the allocating step includes allocating the wireless power pulse to at least one wireless power receiver of the plurality of wireless power receivers that has a more urgent power need.

13. The method of claim 1 , wherein the wireless power pulses comprise frequency modulated pulses.

14. The method of claim 1 , wherein the delivering step includes charging at least one energy storage device of or associated with the one or more wireless power receivers.

15. The method of claim 1, further comprising a step in which the wireless power transmitter normalizes the data to display a metric of the at least one battery demand of the one or more wireless power receivers.

16. The method of claim 15 , wherein the allocating step comprises allocating the wireless power pulses to the one or more wireless power receivers according to the normalizing step.

17. The method of claim 1 , wherein the allocating step comprises allocating the wireless power pulses to the one or more wireless power receivers based on predictive modeling.

18. The method of claim 1 , wherein the transmitting step includes the step of directing an antenna to transmit the wireless power pulses to the one or more wireless power receivers in accordance with the allocating and modulating steps.

19. 20. The method of claim 18, wherein the directing step comprises directing a phased array having a plurality of antennas to transmit the wireless power pulses to the one or more wireless power receivers.

20. 20. The method of claim 18, wherein the directing step comprises directing a phased microwave transmit array to transmit the wireless power pulses to the one or more wireless power receivers.

21. The method of claim 1 , wherein the modulating step includes modulating at least one of a transmission frequency, timing, amplitude, and direction of the wireless power pulses.

22. The method of claim 1 , wherein the data indicative of the at least one battery demand metric includes at least one of a state of charge, an amount of power consumed, and an amount of power received.

23. The method of claim 1 , wherein the data indicative of the at least one battery demand metric is encoded and / or encrypted within a data packet.

24. The method of claim 1, further comprising the step of the wireless power transmitter encoding and / or encrypting the data indicating the at least one battery demand metric in a data packet.

25. The method of claim 1, further comprising a step in which the wireless power transmitter calculates the battery demand of the one or more wireless power receivers based on the data indicating a metric of the at least one battery demand.

26. 1. A system comprising a wireless power transmitter and one or more wireless power receivers, The wireless power transmitter includes: A transmitter / receiver, a controller operably coupled to the transceiver, receiving, via the transceiver, the data indicative of at least one battery demand metric of the one or more wireless power receivers; allocating wireless power pulses according to the data indicative of a metric of at least one battery demand of the one or more wireless power receivers; modulating one or more phases of the wireless power pulses to maximize their power for reception at each location of the one or more wireless power receivers; a controller configured to direct the transceiver to deliver the allocated wireless power pulses to the one or more wireless power receivers in the modulated one or more phases; the one or more wireless power receivers are configured to detect missing wireless power pulses or one or more skipped power pulses; The controller is configured to receive, via the transceiver, at least one beacon signal transmitted by the one or more wireless power receivers in accordance with a skip factor and in response to detecting the missing wireless power pulse or the one or more skipped wireless power pulses.

27. 27. The system of claim 26, wherein the controller is further configured to receive, via the transceiver, beacon signals from the one or more wireless power receivers.

28. 28. The system of claim 27, wherein to modulate the one or more phases of the wireless power pulse, the controller is configured to modulate the one or more phases of the wireless power pulse according to a received phase of the beacon signal.

29. 28. The system of claim 27, wherein to direct the transceiver to deliver the assigned wireless power pulse, the controller is configured to direct the transceiver to transmit the wireless power pulse in response to the beacon signal being received.

30. To receive the beacon signal, the controller is configured to first receive the beacon signal from the one or more wireless power receivers before an assigned wireless power pulse is delivered; the one or more wireless power receivers are further configured to transmit the at least one beacon signal in accordance with the skip factor; 28. The system of claim 27, wherein the controller is further configured to second receive the at least one beacon signal transmitted by the one or more wireless power receivers in accordance with the skip factor.

31. 31. The system of claim 30, wherein the skip factor instructs one or more wireless power receivers not to respond to any wireless power pulses.

32. 32. The system of claim 31, wherein the skip factor instructs the one or more wireless power receivers to skip a number of wireless power pulses before the at least one beacon signal is transmitted.

33. 28. The system of claim 27, wherein the controller is further configured to direct the transceiver to transmit a beacon request signal toward the wireless power delivery environment.

34. the one or more wireless power receivers are further configured to transmit the beacon signal in response to the beacon request signal; 34. The system of claim 33, wherein the controller is further configured to process the beacon signals received from the one or more wireless power receivers.

35. 35. The system of claim 34, wherein the controller is further configured to determine a presence of the one or more wireless power receivers in the wireless power delivery environment based on the beacon signals.

36. 27. The system of claim 26, wherein the one or more wireless power receivers comprise a plurality of wireless power receivers.

37. 37. The system of claim 36, wherein to allocate the wireless power pulse, the controller is configured to allocate the wireless power pulse to at least one wireless power receiver of the plurality of wireless power receivers that has a more urgent power need.

38. 27. The system of claim 26, wherein the wireless power pulses comprise frequency modulated pulses.

39. 27. The system of claim 26, wherein the controller is configured to charge at least one energy storage device of or associated with the one or more wireless power receivers to induce the transceiver to deliver the allocated wireless power pulses.

40. 27. The system of claim 26, wherein the controller is further configured to normalize the data indicative of a metric of the at least one battery demand of the one or more wireless power receivers.

41. 41. The system of claim 40, wherein to allocate the wireless power pulses, the controller is configured to allocate the wireless power pulses to the one or more wireless power receivers according to the normalized data indicative of a metric of the battery demand.

42. 27. The system of claim 26, wherein to allocate the wireless power pulses, the controller is configured to allocate the wireless power pulses to the one or more wireless power receivers based on predictive modeling.

43. 27. The system of claim 26, wherein to direct the transceiver to transmit the assigned wireless power pulses, the controller is configured to direct an antenna to transmit the assigned wireless power pulses to the one or more wireless power receivers in the one or more modulated phases.

44. 44. The system of claim 43, further comprising the antenna.

45. 44. The system of claim 43, wherein to direct the transceiver to transmit the assigned wireless power pulse, the controller is further configured to direct a phased array having multiple antennas to transmit the wireless power pulse to the one or more wireless power receivers.

46. 46. ​​The system of claim 45, further comprising the phased array.

47. 44. The system of claim 43, wherein to direct the transceiver to transmit the assigned wireless power pulse, the controller is further configured to direct a phased microwave transmit array to the one or more wireless power receivers to transmit the wireless power pulse.

48. 48. The system of claim 47, further comprising the phased microwave transmit array.

49. 27. The system of claim 26, wherein the controller is further configured to modulate at least one of a transmission frequency, timing, amplitude, and direction of the wireless power pulses.

50. 27. The system of claim 26, wherein the data indicative of the at least one battery demand metric includes at least one of a state of charge, an amount of power consumed, and an amount of power received.

51. 27. The system of claim 26, wherein the data indicative of the at least one battery demand metric is encoded and / or encrypted within a data packet.

52. 27. The system of claim 26, wherein the controller is further configured to calculate a battery demand for the one or more wireless power receivers based on the data indicative of the at least one battery demand metric.

53. 27. The system of claim 26, wherein the controller is further configured to establish wireless communication with the one or more wireless power receivers via the transceiver.

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