Wireless Power Transfer Network

A wireless power transfer system includes a wireless power transmitter configured to transmit a query power signal and a wireless power receiver that is in an energy depleted state that is configured to transmit a backscatter signal in response to receipt of the query power signal. The wireless power transmitter is configured to detect the backscatter signal from the wireless power receiver, determine from the backscatter signal if a wireless power delivery requirement of the wireless power receiver is met, and deliver wireless power to the wireless power receiver if the wireless power delivery requirement is met.

TECHNICAL FIELD

The aspects of the disclosed embodiments relate generally to far field wireless power transmission (WPT) and, more particularly to wireless power delivery to energy depleted apparatus in a wireless power transfer network (WPTN).

BACKGROUND

In far-field WPT, to increase the power delivery and communication range, high gain antennas and beam-forming techniques are desired for long range wireless power transfer. However, for increased gain the wireless power transmitter has to know where the wireless power receiver is, or has to find the best direction to send energy to it.

Typically, the wireless power receiver apparatus to be powered can initiate a communication by its own, or it is located within the transmitter's field of view (FOV). If the wireless power receiver apparatus does not have an energy source or is not located within the wireless power transmitter's FOV due to the use of high gain antennas, detection becomes more challenging.

Backscatter signaling can be useful as a feedback mechanism in wireless power transfer systems and ultra-low power receivers. However, backscatter signaling generates a clock and/or data modulation signal within the wireless power receiver. The use of a processing unit to generate such signal uses a certain amount of power and can introduce additional delay to the scanning/detection of battery-less power receivers due to the initialization of protocols, overheads and possible signal sampling.

Thus, there is a need for improved apparatus and methods that can efficiently identify, locate and provide wireless electrical power to energy depleted wireless power receiver apparatus in a WPTN. Accordingly, it would be desirable to provide methods and apparatuses that address at least some of the problems described above.

SUMMARY

The aspects of the disclosed embodiments are directed to a wireless power transfer system that allows the fast detection and delivery of wireless power by focusing the energy from a high gain beam-forming/beam-shaping antenna towards a battery-less wireless power receiver apparatus or a wireless power receiver apparatus with a depleted battery. This and other objectives are solved by the subject matter of the independent claims. Further advantageous embodiments can be found in the dependent claims.

According to a first aspect, the above and further objectives and advantages are obtained by a wireless power transfer system. In one embodiment, the wireless power transfer system includes a wireless power transmitter apparatus configured to transmit a query power signal (fQPS) and a wireless power receiver apparatus in an energy depleted state that is configured to transmit a backscatter signal (fBS) in response to receipt of fQPS. The wireless power transmitter apparatus is configured to detect fBSfrom the wireless power receiver apparatus, determine from the detected fBSif a wireless power delivery requirement of the wireless power receiver apparatus is met, and deliver wireless power to the wireless power receiver apparatus if the wireless power delivery requirement is met. The aspects of the disclosed embodiments enable the detection of targets, such as battery-less wireless power receiver apparatus, or wireless power receiver apparatus that cannot initiate signaling to request wireless power.

In a possible implementation form the wireless power transmitter apparatus is configured to switch to a continuous wave (CW) mode to deliver power to the wireless power receiver apparatus. The wireless power receiver apparatus cooperates with the wireless power transmitter apparatus in order to be detectable and to allow the wireless power transmitter to find the best direction to transmit the radio frequency (RF) energy.

In a possible implementation form the wireless power transmitter apparatus is configured to transmit a backscatter carrier signal (fBC). The aspects of the disclosed embodiments enable the detection of targets, such as battery-less wireless power receiver apparatus, or wireless power receiver apparatus that cannot initiate signaling to request wireless power.

In a possible implementation form the fQPSincludes a power signal (fWPT) and a query modulation signal component (fn). The frequency of oscillation is related with the input RF power enabling the detection of targets, such as battery-less wireless power receiver apparatus, or wireless power receiver apparatus that cannot initiate signaling to request wireless power.

In a possible implementation form the fBScomprises an fBCmodulated by an fnof the fQPS. The frequency of oscillation is related with the input RF power enabling the detection of targets, such as battery-less wireless power receiver apparatus, or wireless power receiver apparatus that cannot initiate signaling to request wireless power.

In a possible implementation form the fQPSis a pulse modulated signal with a specific pulse period. The frequency of oscillation is related with the input RF power enabling the detection of targets, such as battery-less wireless power receiver apparatus, or wireless power receiver apparatus that cannot initiate signaling to request wireless power.

In a possible implementation form the wireless power transmitter apparatus is configured to transmit the fQPSin a plurality of directions (Dm). The aspects of the disclosed embodiments do not need to try every beam direction and there is no need for processing, which allows for speeding up the detection time and power delivery.

In a possible implementation form the wireless power transmitter apparatus is configured to transmit the fQPSin a plurality of sub-directions (Dm, k). The aspects of the disclosed embodiments do not need to try every beam direction and there is no need for processing, which allows for speeding up the detection time and power delivery.

In a possible implementation form the wireless power transmitter apparatus is configured to transmit the fQPSin one direction of the Dmor Dm, kat a time. The wireless power receiver device can be detected and the best direction to transmit the energy can be known even if the wireless power system is within a highly multipath environment or at non-line-of-sight conditions.

In a possible implementation form the wireless power transmitter apparatus is configured to record a direction associated with a detected fBSbased on the Dmof the corresponding transmitted fQPS. The wireless power receiver device cooperates with the wireless power transmitter device in order to be detectable and to allow the wireless power transmitter device to find the best direction to transmit the RF energy.

In a possible implementation form the fBStransmitted by the wireless power receiver apparatus is a signal modulated by an fnof the fQPS. The frequency of oscillation is related with the input RF power enabling the detection of targets, such as battery-less wireless power receiver apparatus, or wireless power receiver apparatus that cannot initiate signaling to request wireless power.

In a possible implementation form the wireless power transmitter apparatus is configured to determine from the fnthat the pre-determined amount of RF power is being delivered to the wireless power receiver apparatus. The frequency of oscillation is related with the input RF power enabling the detection of targets, such as battery-less wireless power receiver apparatus, or wireless power receiver apparatus that cannot initiate signaling to request wireless power.

In a possible implementation form the wireless power transmitter apparatus includes a backscatter apparatus configured to transmit an fBCwhen the wireless power transmitter apparatus transmits the fQPSand to detect the fBStransmitted by the wireless power receiver apparatus. The fBCis transmitted whenever the wireless power transmitter apparatus wants to listen to a wireless power receiver apparatus.

In a possible implementation form the fBCcan be transmitted simultaneously with the fn. The fBCis transmitted whenever the wireless power transmitter apparatus wants to listen to a wireless power receiver apparatus.

In a possible implementation form the wireless power receiver apparatus is configured to transmit the fBSwhen an RF power of the fQPSreceived by the wireless power receiver apparatus exceeds a pre-determined power threshold. The fBSis generated when the wireless power receiver apparatus is receiving a certain amount of RF power, which can be less than the RF power required to operate the receiver.

In a possible implementation form the wireless power receiver apparatus has a plurality of query power signal receiver paths, where individual ones of the plurality of query power signal receiver paths are associated with a different pre-determined power threshold. The wireless power receiver apparatus is configured to transmit the fBSwhen a received power associated with the fQPSexceeds a pre-determined power threshold of one of the plurality of query power signal receiver paths. The aspects of the disclosed embodiments provide a single path for each fQPSand each path has its own power threshold.

In a possible implementation form the wireless power transmitter apparatus is further configured, when the pre-determined received amount of power is less than the required amount of power to transmit a next query power signal (fQPSn+1), the fQPSn+1associated with a received RF power that is higher than an RF power of the fQPS. The aspects of the disclosed embodiments can iteratively query for a higher amount of RF power delivered until the power delivery requirements of the wireless power receiver are met.

In a possible implementation form the wireless power transmitter apparatus is further configured to determine the Dmassociated with the fBSand transmit the fQPSn+1in Dk,massociated with the Dm. The aspects of the disclosed embodiments enable a fast focus of the beam direction for wireless power delivery.

In a possible implementation form when the wireless power transmitter apparatus does not detect the fBS, the wireless power transmitter apparatus is further configured to change a beam pattern (Pk) with a beam width (φk) and gain (gk) associated with the fQPSto a next beam pattern (Pk+1) with a next beam width (φk+1) and next gain (gk+1), where the φk+1of the Pk+1is narrower than the φkof the Pkand the next gain (gk+1) is greater than the gk; and transmit the fQPSwith the φk+1and gk+1. When the wireless power transmitter does not detect the fBSthis can trigger the use of the fQPSwith a new beam pattern of narrower width and higher gain. To overcome propagation path loss, the beam width is traded for antenna gain.

In a possible implementation form the wireless power transmitter apparatus is further configured to iteratively narrow the φk+1of the Pk+1until the fBSdetected by the wireless power transmitter apparatus indicates that the required amount of power is being delivered to the wireless power receiver apparatus. Narrowing the beam width will increase the antenna gain.

In a possible implementation form the wireless power receiver apparatus includes a switching apparatus (T1) configured to modulate the fBCto generate the fBS. An input sensitivity of the T1is less than an input power threshold required to power on the wireless power receiver apparatus. The aspects of the disclosed embodiments enable the generation of the backscatter signal even when the wireless power receiver is not receiving enough RF power to be operational.

According to a second aspect, the above and further objectives and advantages are obtained by a wireless power transmitter apparatus. In one embodiment, the wireless power transmitter apparatus is configured to transmit an fQPS; detect an fBSsent from a wireless power receiver apparatus; determine from the detected fBSif a wireless power delivery requirement of the wireless power receiver apparatus is met; and deliver wireless power to the wireless power receiver apparatus if the wireless power delivery requirement is met. The aspects of the disclosed embodiments enable the detection of targets, such as battery-less wireless power receiver apparatus, or wireless power receiver apparatus that cannot initiate signaling to request wireless power.

In a possible implementation form, the wireless power transmitter apparatus is configured to transmit an fBCwhen the fQPSis being transmitted. The wireless power transmitter apparatus can transmit the fBCwhen it wants to listen to a wireless power receiver apparatus.

According to a third aspect, the above and further objectives and advantages are obtained by a wireless power receiver apparatus. In one embodiment, the wireless power receiver apparatus is configured to receive an fQPSand transmit an fBSwhen an RF power of the fQPSreceived by the wireless power receiver apparatus exceeds a pre-determined power threshold. The aspects of the disclosed embodiments enable the detection of targets, such as battery-less wireless power receiver apparatus, or wireless power receiver apparatus that cannot initiate signaling to request wireless power.

In a possible implementation form the wireless power receiver apparatus forms the fBSby modulating a received fBCwith an fnof the fQPS. The frequency of oscillation is related with the input RF power enabling the detection of targets, such as battery-less wireless power receiver apparatus, or wireless power receiver apparatus that cannot initiate signaling to request wireless power.

According to a fourth aspect, the above and further objectives and advantages are obtained by a method. In one embodiment the method includes transmitting an fQPSfrom a wireless power transmitter apparatus, detecting an fBSsent from a wireless power receiver apparatus in an energy depleted state responsive to the fQPS, determining from the fBSif a wireless power delivery requirement of the wireless power receiver is met, and delivering wireless power to the wireless power receiver apparatus when the wireless power delivery requirement is met. The aspects of the disclosed embodiments enable the detection of targets, such as battery-less wireless power receiver apparatus, or wireless power receiver apparatus that cannot initiate signaling to request wireless power.

In a possible implementation form, when the fBSis not detected, the method further comprises changing a Pkassociated with the fQPSto a Pk+1, wherein an φk+1of the Pk+1is narrower than an φkof the Pkand a gk+1is greater than a gk, and transmitting the fQPSwith the Pk+1. The aspects of the disclosed embodiments enable fast detection and delivery of wireless power to a wireless power receiver device by focusing the RF energy from a high gain beam-forming/beam-shaping antenna towards the battery-less wireless power receiver device or wireless power receiver device with a depleted battery.

In a possible implementation form, when the pre-determined amount of delivered power is less than the required amount of power, the method further includes transmitting an fQPSn+1, the fQPSn+1associated with a received RF power that is higher than an RF power of the fQPS. The aspects of the disclosed embodiments enable fast detection and delivery of wireless power to a wireless power receiver device by focusing the RF energy from a high gain beam-forming/beam-shaping antenna towards the battery-less wireless power receiver device or wireless power receiver device with a depleted battery.

In a possible implementation form the wireless power transmitter apparatus is a high-gain beam shaping antenna. The aspects of the disclosed embodiments enable fast detection and delivery of wireless power to a wireless power receiver device by focusing the RF energy from a high gain beam-forming/beam-shaping antenna towards the battery-less wireless power receiver device or wireless power receiver device with a depleted battery.

In a possible implementation form the wireless power receiver apparatus is in an energy depleted state. The aspects of the disclosed embodiments enable fast detection and delivery of wireless power to a wireless power receiver device by focusing the RF energy from a high gain beam-forming/beam-shaping antenna towards the battery-less wireless power receiver device or wireless power receiver device with a depleted battery.

According to a fifth aspect, the above and further objectives and advantages are obtained by a non-transitory computer readable medium having stored thereon program instructions. The program instructions, when executed by a processor, are configured to cause the processor to perform the method according to any one or more of the possible implementation forms described herein.

These and other aspects, implementation forms, and advantages of the exemplary embodiments will become apparent from the embodiments described herein considered in conjunction with the accompanying drawings. It is to be understood, however, that the description and drawings are designed solely for purposes of illustration and not as a definition of the limits of the disclosure, for which reference should be made to the appended claims. Additional aspects and advantages of the disclosure will be set forth in the description that follows, and in part will be obvious from the description, or may be learned by practice of the disclosure. Moreover, the aspects and advantages of the disclosure may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

DESCRIPTION OF EMBODIMENTS

Referring toFIG.1, a schematic block diagram of an exemplary WPTN or system10incorporating aspects of the disclosed embodiments is illustrated. The wireless power transfer system10of the disclosed embodiments is configured to provide wireless power transfer services. The wireless power transfer services can include, but are not limited to, far-field wireless charging. The aspects of the disclosed embodiments are directed to fast detection and fast focus of the energy emitted by high gain wireless power antenna systems of a wireless power transmitter apparatus100to a wireless power receiver apparatus200that cannot initiate a signaling request. Such wireless power receiver apparatus200include, but are not limited to, battery-less apparatus, apparatus with a depleted battery that is to be re-charged and apparatus that are otherwise in an energy depleted state.

As shown inFIG.1, the wireless power transfer system10comprises a wireless power transmitter apparatus100and a wireless power receiver apparatus200. Although only one wireless power transmitter apparatus100and one wireless power receiver apparatus200are shown inFIG.1, the aspects of the disclosed embodiments are not so limited. In alternate embodiments, the wireless power transfer system10can include any suitable number of wireless power transmitter apparatus100and wireless power receiver apparatus200, other than including one.

As illustrated inFIG.1, the wireless power transmitter apparatus100is configured to transmit an fQPS. The wireless power receiver apparatus200is configured to detect the fQPSand transmit an fBSin reply. The fQPSis generally configured to “ask” the wireless power receiver apparatus200if it is collecting, at least, a certain predefined amount of power.

In this example, the wireless power receiver apparatus200is in an energy depleted state, generally meaning that the wireless power receiver apparatus200does not have enough stored energy to initiate communication with the wireless power transmitter apparatus100. If the wireless power receiver apparatus200can “answer” with the fBS, that generally indicates that the wireless power receiver apparatus200is receiving at least a certain amount of RF power. This certain amount of RF power may be less than the power used to operate the wireless power receiver apparatus200.

In one embodiment, the wireless power transmitter apparatus100is configured to detect the fBSfrom the wireless power receiver apparatus200, determine from the detected fBSif a wireless power delivery requirement of the wireless power receiver apparatus200is met, and deliver wireless power to the wireless power receiver apparatus200if the wireless power delivery requirement is met.

In a typical wireless power transfer system, the use of high gain antennas to deliver wireless power generally uses some kind of localization and/or feedback technique in order to focus the narrow beam toward the wireless power receiver and minimize the transmission losses by choosing the best transmission technique. However, these techniques generally include the receiver apparatus being powered on to initiate communication and detection.

Where backscatter signaling is used, such backscatter signaling generates a clock and/or data modulation signal within the wireless power receiver. This signal is usually generated with a processing unit, such as a microcontroller or a voltage controlled oscillator (VCO). The use of a processing unit to generate the modulation signal uses a certain amount of power and can introduce additional delay to the scanning/detection of battery-less power receivers due to the initialization of protocols, overheads and possible signal sampling.

The aspects of the disclosed embodiments enable the detection of targets, such as battery-less wireless power receiver apparatus, or wireless power receiver apparatus that cannot initiate signaling to request wireless power. The wireless power receiver apparatus200of the disclosed embodiments can be detected and the best direction to transmit the RF energy can be determined even if the wireless power receiver apparatus200is within a highly multipath environment or non-line-of-sight conditions. The wireless power receiver apparatus cooperates 200 with the wireless power transmitter apparatus100in order to be detectable and to allow the wireless power transmitter apparatus100to find the best direction to transmit the energy.

In the example ofFIG.1, the wireless fQPStransmitted by the wireless power transmitter apparatus100, also referred to herein are used to detect and to query a wireless power receiver200about its received wireless power signal strength. Based on the response of the wireless power receiver apparatus200to the fQPSthrough backscatter signaling, the wireless power transmitter apparatus100may iteratively adjust its Pkuntil it delivers the required amount of power.

Each fQPSis generally configured to “ask” the wireless power receiver apparatus200if it is collecting, at least, a certain predefined amount of power. The wireless power receiver apparatus200is configured to answer the fQPSfrom the wireless power transmitter apparatus100through backscatter signaling. The aspects of the disclosed embodiments use backscatter signaling but without generating a backscatter modulation signal within the wireless power receiver apparatus200, thus providing a low cost and simple solution.

FIG.2illustrates a schematic block diagram of one example of a backscatter communication link between a wireless power transmitter apparatus100and a wireless power receiver apparatus200in a WPTN10incorporating aspects of the disclosed embodiments. As illustrated in the example ofFIG.2, the wireless power transmitter100is equipped with a backscatter module102. In the example ofFIG.2, the backscatter module102includes a backscatter transmitter104and a backscatter reader106. The backscatter transmitter104is coupled to an antenna114and the backscatter reader106is coupled to an antenna116.

The backscatter transmitter104is configured to transmit an fBC. The fBCis used whenever the wireless power transmitter apparatus100wants to “listen” for a wireless power receiver apparatus200.

The backscatter reader106is generally configured to listen for the feedback provided by the wireless power receiver apparatus200. As described herein, the feedback is generally in the form of the fBS. In one embodiment, the fBSgenerally comprises the fBC, modulated by an fnof the fQPS.

The wireless power transfer system10of the disclosed embodiments is configured to operate with two different frequencies. As used herein, fWPTrefers to the carrier frequency used for wireless power transfer. The frequency fBCrefers to the carrier frequency transmitted by the backscatter transmitter104and used for feedback through backscatter signaling. The aspects of the disclosed embodiments generally use distinct carrier frequencies for successful operation.

In one embodiment, the backscatter module102is configured to continuously transmit a CW fBCthrough the backscatter module transmitter104. The fBSis generally configured to “illuminate” the whole FOV of the wireless power transmitter apparatus100. Typically, low gain antennas are employed to transmit the fBC.

In one embodiment, the wireless power receiver apparatus200shown inFIG.2includes an energy receiving block202and a backscatter modulator204. The energy receiving block202is responsible to convert the wireless energy collected by the receiving antenna206of the wireless power receiver200into usable direct current (DC) energy, which will be used to power up the wireless power receiver apparatus200.

In the example ofFIG.2, the backscatter module204of the wireless power receiver apparatus200includes a receive/transmit antenna208and a switch S1. As further described herein, S1is generally configured to switch the antenna208between two termination loads shown as Z1and Z2.

S1is configured by a data/clock modulation signal210. The load terminations Z1and Z2may be a matched load and a pure reactive load for amplitude-shift keying (ASK) modulation, or pure reactive loads with 180 degrees of phase shift for binary phase-shift keying (BPSK) modulation. The aspects of the disclosed embodiments can include other modulations, which can be generated by adding additional termination loads, such as for example M-ary phase-shift keying (M-PSK) and quadrature phase-shift keying (QPSK).

S1can be any suitable type of switching apparatus. Examples include, but are not limited to, a transistor or a diode. The backscatter module204is configured to modulate and transmit the fBCback to the wireless power transmitter apparatus100based on predefined conditions.

The clock and/or data modulation signal210shown inFIG.2is configured to modulate the fBCand enable the module204to send the fBSback to the wireless power transmitter100. As described herein, the signal210is generated only when the wireless power receiver200has enough energy to operate. Although the backscatter module204of the wireless power receiver apparatus200relies on the clock/data modulation signal210, the wireless power receiver apparatus200does not require a processing unit to generate such signal210. The use of a processing unit would be a critical source of power consumption and delay due to the initialization overheads that would occur after turn-on of such a processing unit. The lack of a processing unit, analog-to-digital converter (ADC) sampling or the generation of such signal within the wireless power receiver200itself, allows the wireless power receiver200to be fast, simple and low cost.

The backscatter reader106of the backscatter apparatus102shown inFIG.2is configured to detect the fBSsent by the wireless power receiver apparatus200. As described further herein, the detection of the fBSor absence of detection of the fBSwill trigger an action in the wireless power transmitter apparatus100.

Although a bi-static backscatter configuration is shown in the example ofFIG.2, the aspects of the disclosed embodiments are not so limited. In alternate embodiments, any suitable backscatter configuration can be considered, such as a mono-static configuration. Mono-static configuration uses a single antenna for transmit and receive. A circulator may be used to separate the transmitter from the receiver in this implementation.

As described further herein, the aspects of the disclosed embodiments rely on beam-forming/beam-shaping antennas and backscatter communications in a wireless power transfer system10that can detect and focus wireless power towards a wireless power receiver apparatus200in an energy depleted state. These wireless power receiver apparatus200are generally disposed or otherwise positioned within the range of high gain wireless power transmitting antenna systems112of the wireless power transmitter apparatus100.

In one embodiment, the wireless power transmitter apparatus100is a high gain antenna array112with beam-forming and/or beam-shaping capabilities. The wireless power transmitter apparatus100may produce Pxfor the fQPSwith different φkand gk, as well as transmit the fQPSin several directions. The wireless power transmitter apparatus100is configured to trade its maximum gain for a larger beam-width.

In one embodiment, the wireless power transmitter apparatus100can include a processor(s) or processing unit108. The processing unit108can be a microcontroller, digital signal processor (DSP) or field-programmable gate array (FPGA), for example. The processing unit or processor108is configured to provide the control signals for setting the phase and/or amplitude of the fQPSthat is fed to each element of the antenna112of the wireless power transmitter apparatus100. One or more of the phase and amplitude of the fQPSdescribed herein can be adjusted to a form an φkwith a specific beam-width and with a maximum RF power intensity towards specific Dmor Dm,k. This is also known as beam-forming or beam-shaping.

When the Pkis shaped, the maximum gain can decrease. In one embodiment, a look-up table of phases and/or amplitudes is stored within a memory110or other suitable storage medium of the processing unit108. This look-up table can be accessed to identify the control signals that are applied to generate certain Pk. For example, in one embodiment, the look-up table should contain the control signals that are used to generate the Pkthat cover several segments of the total FOV of the wireless power transmitter100as is described herein. Examples of such Pkwith different φkare shown inFIGS.7and8.

In one embodiment, the wireless power transmitter100will include or be communicatively connected to the memory or storage apparatus110. The memory110is generally configured to store or maintain information or data related to the wireless power transmitter apparatus100and the wireless power receiver apparatus200. In addition to the phase, amplitude and control signals described above, the information stored in the memory110could also include, but is not limited to, a capability of each wireless power transmitter apparatus100, a number and type of antennas, a number of supported beam directions, per unit power delivery capabilities, a type of the wireless power receiver apparatus200, a type of battery, remaining charging time, priority and receiver identifier.

FIG.3illustrates a schematic block diagram of the wireless power transmitter apparatus100. In this example the wireless power transmitter apparatus100includes the backscatter module102and the wireless power transmitter120. The backscatter module102, which in this example includes the backscatter transmitter104and the backscatter reader106of the backscatter module102may or may not be co-located with the wireless power transmitter120. The wireless power transmitter120of the wireless power transmitter apparatus100is generally configured to switch between CW operation and pulsed operation at f1, f2, . . . fN, where N is the total number of pulsed signals.

Referring to the example ofFIG.3, CW operation is set by mixing the fWPT(typically in the gigahertz (GHz) range) generated by a power source with a DC component302. CW operation will be used when the best direction to transmit the RF energy to the wireless power receiver200is found, as is further described herein.

In pulsed operation, the fWPTis mixed, via mixer304, with a low frequency oscillator such as one of f1, f2, . . . fN. In one embodiment, the low frequency oscillator f1, f2, . . . fNis in the megahertz (MHz) range. A single VCO may be used to generate the low frequency signals f1, f2, . . . fN, also referred to herein as “query modulation signal component fn” for descriptive purposes only.

This mixing will produce an ON/OFF wireless fQPS, with fn, which will be used to detect and to query the wireless power receiver apparatus200. Based on the response, or lack of response by the wireless power receiver apparatus200to the fQPS, the wireless power transmitter apparatus100shall be guided until it delivers the required power to the wireless power receiver apparatus200. As used herein, the term “required power” generally refers to an amount of received RF power that is needed for the wireless power receiver apparatus200to operate.

The fnof the fQPSis generally configured to “ask” the wireless power receiver200if it is collecting, at least, a certain predefined amount of power. The amount of RF power associated with the fnis known by the wireless power transmitter apparatus100. For example, in one embodiment, the amount of RF power associated with a specific fnis stored in the memory110.

In one embodiment, instead of an up-conversion architecture, a switch S2, or other similar apparatus may be used to switch ON/OFF the fWPTgenerated by the VCO at the frequencies f1, f2, . . . fN, effectively creating pulse modulation. In one embodiment, an additional pulse shaping block may be added to smooth out the pulsed waveform and to decrease the out-of-band spectrum emission.

In one embodiment, the processing unit108of the wireless power transmitter apparatus100is configured to control the CW operation, pulsed operation and the pulse period by sending a control signal306to the switch S2. As further described herein, the processing unit108can also be configured to control which φkshould be used at any given time instant. The CW or pulsed power signal, generally referred to herein as “query power signal fQPS” can then be amplified via an amplifier308to a transmission power level and delivered to the transmitting antenna array112of the wireless power transmitter apparatus100.

The pulsed wireless fQPSntransmitted by the wireless power transmitter apparatus100as shown inFIG.3are used to detect and query a wireless power receiver apparatus200about its received wireless power signal strength. Based on the response of the wireless power receiver apparatus200to the fQPSn, through backscatter signaling, as described further herein, the wireless power transmitter apparatus100is configured to iteratively adjust the Pkof the fQPSnuntil the required amount of power is delivered. The wireless power transmitter apparatus100is configured to switch to the CW mode of operation once it is determined that the required amount of power is being delivered.

FIG.4illustrates one example of a wireless power receiver apparatus200incorporating aspects of the disclosed embodiments. The wireless power receiver apparatus200is generally configured to answer to the fQPSsent from the wireless power transmitter apparatus100through backscatter signaling.

As is shown in this example, an RF-DC converter402is configured to convert the collected RF energy of the fQPSat fWPTto usable DC energy. A low-pass filter404is added to the output of the RF-DC converter402to filter out the fundamental frequency fWPTof the fQPSand the harmonics generated by the rectifying process. The low-pass filter404is configured to allow DC and the low frequency modulations f1, f2. . . fNof the fQPSto pass through, where fN<<1/RC<<fWPT.

As shown in the example ofFIG.4, the DC power produced by the RF-DC converter402is routed through a DC-pass filter406(or RF choke) to the Power Management Unit (PMU)408. In one embodiment, the PMU408is configured to charge a battery410, if any. The PMU408can also be used to power a load412. The load412, can include, but is not limited to, a processing unit or processor, sensor, actuator, dedicated communication module such as WI-FI™, BLUETOOTH™, ZIGBEE™, or any other electronic apparatus or component of the wireless power receiver apparatus200.

In one embodiment, the wireless power receiver apparatus200also comprises a switch S3. One side of S3is coupled or otherwise connected to the output of the RF-DC converter402. The other side of S3is coupled or otherwise connected to a bank of filters414.

As illustrated in the example ofFIG.4, S3is configured to be open when the wireless power receiver apparatus200has enough stored energy to guarantee normal operation. If S3is open, the wireless power receiver apparatus200will not provide any answer to the fQPSas described herein.

In one embodiment, the S3can be configured to be in the closed and connected state when the wireless power receiver apparatus200is in the energy depleted state. When S3is closed the low frequency components (<1/RC) produced by the RF-DC converter402are communicated to the bank of filters414.

When in the energy depleted state, the wireless power receiver apparatus200has no energy to initiate a request for wireless charging. In one embodiment, S3can be a relay with a “closed” default state. S3can be set to “open” by an external control signal provided by a microcontroller or directly from the battery410, if any.

As illustrated in the example ofFIG.4, when S3is in the closed state, the low frequency modulations f1, f2. . . fNof the fQPS, or fn, will be routed to a bank of filters414, also referred to as filter bank414. The filter bank414generally includes a plurality of filters. In one embodiment, the filters in the filter bank414are band-pass filters. As such, no DC power will flow through the band-pass filters.

The filters in the filter bank414are matched to the frequency of the low frequency oscillators f1, f2. . . fNof the wireless power transmitter apparatus ofFIG.3. Thus, for each fn, there will be a corresponding filter in the filter bank414.

In one embodiment, the wireless power receiver apparatus200does not include S3. In this example, a straight connection is provided between the output Voutof the RF-DC converter402and the filter bank414. When there is such a direct connection, the wireless power receiver apparatus200may provide a response to the fQPSfrom the wireless power transmitter apparatus100through the backscatter link even if when the wireless power receiver apparatus200does not use wireless power.

The wireless power transmitter apparatus100ofFIG.3is generally configured to transmit one fQPS, with fn, at a time. For example, if the fQPSwith f1is received by the wireless power receiver apparatus200shown inFIG.4, the f1will be routed through the band-pass filter of the filter bank414with that same pass-frequency or the corresponding low frequency oscillator signal f1.

As shown in the example ofFIG.4, the wireless power receiver apparatus200also includes an attenuation block416that is connected to the output of the filter bank414. The attenuation block416includes a plurality of blocks labelled as Attenuation1to Attenuation N. The individual filters of the filter bank414are connected to respective blocks of the attenuation block416. The combination of S3, filter bank414and attenuation block416generally comprises the query power signal receiver path or paths420. For each fQPSn, and fn, there will be a respective query power signal receiver path420.

In one embodiment, the attenuation of different ones of the blocks in the attenuation block416can vary. For example, an attenuation value of Attenuation1can be less than the attenuation value of Attenuation2, which is less than the attenuation value of Attention N. In alternate embodiments, the blocks of the attenuation block416can have any suitable values.

FIG.5illustrates one example of an attenuation block416. In this example, the attenuation block416includes a plurality of resistive voltage dividers, such as RN,1, RN,2followed by an isolation diode DN. DNis used to ensure isolation between the resistive voltage dividers of the filter block416.

Referring again toFIG.4, in one embodiment, the wireless power receiver apparatus200includes a switch T1. T1will also be referred to herein as the “backscatter” switch T1, and is similar in form and function to S1described with respect toFIG.2. As is shown in the examples ofFIGS.4and5, the output of the attenuation block416is connected to T1.

T1is generally configured to switch between OFF and ON or ON and OFF based on a control input. In one embodiment, T1is a transistor. In alternate embodiments, T1can be any suitable switching apparatus.

As described further herein, when S3is in the closed state, the aspects of the disclosed embodiments provide for the fncomponent of the fQPSto turn T1ON and OFF. This switching will add ON/OFF modulation to the fBCthat is received from the wireless power transmitter apparatus100at a frequency that is equal to the frequency of fn, or the respective low frequency oscillator signal f1, f2. . . fN, portion of the fQPS.

To activate the switching of T1, the peak-to-peak voltage of the fnportion of the fQPSmust be large enough, after attenuation by the corresponding block in attenuation block416, to surpass the threshold of T1. When the peak-to-peak voltage of fnis large enough, the fnwill effectively switch ON/OFF T1, modulating the received fBCat one of the low frequency oscillators f1to fN.

In the example ofFIG.4, T1is configured to alternately connect the backscatter antenna208between a 50 Ohm load and a short circuit. This adds an ON/OFF modulation to the fBCat a frequency that is equal to the frequency of fn. This modulation is similar to what is described with respect to signal210herein.

The generated fBSwill be the fBCmodulated by fn. This modulated signal, also referred to as the backscatter signal fBS, is then sent back to the wireless power transmitter apparatus100, where it can be detected by the backscatter reader104ofFIG.2.

The time used by the feedback mechanism shown inFIG.4to generate fBSresponsive to the fQPSshould be mainly determined by the backscatter free-space propagation delay, allowing it to operate as close as possible to real-time. In one embodiment, crystal oscillators and crystal filters may be used for perfect frequency match. Crystal filters are particular suitable due to high selectivity, eliminating unwanted noise and/or external interferers.

Referring again toFIG.3, in one embodiment, the received fBSis down-converted and filtered by narrow-band band-pass filters320. The narrow-band band pass filters are matched to the ON/OFF frequency of the low frequency oscillator signals f1, f2. . . fNof the wireless power transmitter apparatus100.

In one embodiment, a peak detector322is used to detect the presence of the frequency components of the fn, the low frequency oscillator signals f1, f2. . . fN. The peak detector322can be configured to generate a “high” DC voltage if a frequency component corresponding to the frequency component of the low frequency oscillator signals f1, f2. . . fNis detected and a “low” DC voltage if no frequency component is detected. The output signal324from the peak detector322is then routed to the processing unit108to trigger an action, such as to set a new Pkor a generate a new fQPSn+1.

The fnof the fQPScan be understood as a question to the wireless power receiver apparatus200as to whether the wireless power receiver apparatus200is receiving, at least, a certain predefined amount of RF power. The detection of fBSby the backscatter reader104ofFIG.2means that the wireless power receiver apparatus200answered “yes” to the particular fQPSnsent by the wireless power transmitter apparatus100. If the modulated fBSis not detected, this lack of a response will be understood or interpreted as a “no.”

There are N possible fQPSwith N modulations f1, f2. . . fNand N RF power thresholds. In the examples generally described herein, the received RF power associated with fPQS2is greater than the received RF power associated with fPQS1. Similarly, the received RF power associated with fPQSn+1is greater that the received RF power associated with fQPSn.

Also, the attenuation of attenuation block Attenuation2ofFIG.4corresponding to signal f2is greater than the attenuation of attenuation block Attenuation1associated with signal f1. The attenuation of attenuation block Attenuation N associated with fNis greater than the attenuation of attenuation block Attenuation2associated with signal f2. This means that the RF power, or the peak-to-peak voltage of the signal f2, prior to attenuation, has to be greater than the RF power of the signal f1to switch T1ON/OFF, and the RF power of the signal fN, prior to attenuation, has to be greater than the RF power of the signal f2.

When the wireless power transmitter apparatus100is operated in CW mode, meaning it is transmitting wireless power to the wireless power receiver apparatus200, there is no modulation frequency applied to T1. The CW mode will only be set after the wireless power transmitter apparatus100is able to detect that the wireless power receiver apparatus200is receiving the required power to remain operational. During CW mode, the backscatter module204of the wireless power receiver apparatus200is free for other purposes, such as further signaling or information transfer. Using the backscatter module204of the wireless power receiver apparatus200for communications can reduce the energy consumption of the wireless power receiver apparatus200. For example, instead of the wireless power receiver apparatus200using a typical power hungry dedicated communication module, such as WI-FI™, BLUETOOTH™ or ZIGBEE™, for communications, the wireless power receiver apparatus200may use the backscatter module204.

In one embodiment, referring again toFIG.5, during CW operation of the wireless power transmitter apparatus100, an external information/control signal502may be generated within a processing unit of the wireless power receiver apparatus200. In one embodiment, the processor or processing unit of the wireless power receiver apparatus200can comprise an ultra-low power microcontroller. In one embodiment, the signal502can be applied to T1through a diode DS, as shown inFIG.5, allowing the wireless power receiver apparatus200to communicate with the wireless power transmitter apparatus100through backscatter communications.

The voltage produced by an RF-DC converter depends on the input RF power. The higher the input RF power, the higher will be the voltage produced and the DC power. This behavior is represented in the graph ofFIG.6. Since T1has a fixed threshold, the individual attenuations of the attenuation block416corresponding to the signals f1, f2, . . . and fN, is adjusted in order to switch T1ON/OFF at different input RF power levels.

In the example ofFIG.6, three signals, namely f1, f2and f3are defined. The wireless power transmitter apparatus100may switch between CW operation and pulsed operation at f1, f2or f3. As is generally described herein, the pulsed signals f1, f2and f3are used to query the wireless power receiver apparatus200about whether it is receiving at least x, y or z decibel-milliwatts (dBm) of RF power, respectively, from the fQPSn.

Generally, the first pulsed signal, referred to herein as signal f1, is used for detection purposes. If the signal f1is backscattered by the wireless power receiver200as described above, this indicates that the wireless power receiver apparatus200was detected and it is collecting at least x dBm of RF power. The signal f1is generally associated with or is configured to provide a minimum input RF power (x dBm) to surpass the voltage threshold level of T1. The minimum input RF power that triggers such detection at f1is largely dependent on the type of RF-DC converter and its sensitivity. In one embodiment information about the signal f1and the power associated with signal f1can be stored in the memory110shown inFIG.2.

Similarly, the next signal f2is configured to query the wireless power receiver apparatus200to determine whether it is receiving at least y dBm of RF power. The signal f3is configured to determine whether the wireless power receiver apparatus200is receiving at least z dBm. Generally, the RF power level of signal f2will be greater than the RF power level of signal f1, and the RF power level of signal f3will be higher than the RF power level of signal f2.

Referring again toFIG.4, upon receiving an fQPSnassociated or modulated by f1, f2or f3, the RF-DC converter402will produce spectral components at DC and at f1, f2or f3. If the peak-to-peak voltage amplitude of the component produced at f1, f2or f3is large enough, the voltage amplitude will surpass the corresponding attenuation of attenuation block416and the threshold of T1, effectively switching it ON/OFF. The peak-to-peak voltage amplitude of the signal f1, f2or f3is related to the input RF power.

Based on the received power of the signal f1, f2or f3, the wireless power receiver apparatus200will or will not reflect back, or otherwise send to the wireless power transmitter apparatus100the fBCmodulated by the respective frequency f1, f2or f3, referred to as fBS. The transmission or absence of transmission of fBSshall be understood as a “yes” or a “no” to the question “Are you receiving, at least, a certain predefined amount of RF power?” The input RF power level at which the backscatter signaling will occur at f1, f2or f3can be defined by adjusting the value of their corresponding resistors at the attenuator block416shown inFIG.5.

Every attenuation1-N in the attenuation block416(or input RF power threshold) can be set independently. The input RF power required to backscatter a signal at f1and f2is much lower than the one required to keep the wireless power receiver apparatus200fully functional. The aspects of the disclosed embodiments can provide feedback to the wireless power transmitter apparatus100even if the received power is not enough to fully turn the wireless power receiver ON, including a processing unit and/or a dedicated communication module such as WI-FI™, BLUETOOTH™, or ZIGBEE™.

The aspects of the disclosed embodiments enable a fast focus of the required amount of energy towards a wireless power receiver apparatus200located within the FOV of the wireless power transmitter100. Referring again toFIG.1, the wireless power transmitter apparatus100is generally configured to use several combinations of Pkwith different φk, gk, and fQPSn. Although only beam patterns P1, P2and P3are generally referred to herein, the aspects of the disclosed embodiments are not so limited. In alternate embodiments, any suitable number “k” of beam patterns “Pk” can be used.

To transmit wireless power to a wireless power receiver200located far away, Pkwith the narrowest φk(highest gkand highest power delivered) are used. The aspects of the disclosed embodiments allow the wireless power transmitter apparatus100to select one of the64possible beam directions without trying them all, based on the feedback provided by the wireless power receiver apparatus200to the fQPSn.

As shown in the example ofFIG.7, the aspects of the disclosed embodiments segment the total FOV of the antennas112of the wireless power transmitter100.FIG.2illustrates the segmentation of the total FOV and power contours702,704,706produced by the beam patterns P1, P2and P3, respectively. In the example ofFIG.7, the φkof the individual beam patterns P1, P2and P3are different. As shown inFIG.7, the beam width φ1of beam pattern P1is greater than the beam width φ2of beam pattern P2, which is greater than the beam width φ3of beam pattern P3(φ1>φ2>φ3).

The gain g1, g2, g3associated with respective beam patterns P1, P2and P3is also different. Generally, the larger the φkof the Pk, the lower the Gk, also described as the power that the wireless power transmitter apparatus100can deliver through a specific direction. In this example, g1<g2<g3. The Pkwith largest beam-width will have a broader coverage area, but less power delivered, generally per unit area. It is assumed that by using a larger beam pattern, the wireless power transmitter apparatus100can deliver at least x dBm of RF power to any wireless power receiver apparatus200located within its range.

In one embodiment, the largest beam pattern, such as beam pattern φ1ofFIG.7, is configured to provide a minimum input RF power that is delivered to the wireless power receiver apparatus200to enable it to transmit to the wireless power transmitter apparatus100, the fBSmodulated by the signal f1. This particularity can be considered when designing the wireless power transfer system10and defining the RF link budget.

Referring toFIGS.8A-8C, these example shows the use of three (3) beam patterns P1, P2and P3for progressively smaller fields of view, illustrated as FOV802,804,806. The FOVs802,804,806in the examples ofFIGS.8A-8Care divided into four quadrants. The beam width of the particular beam pattern P1, P2and P3being used, is configured to generally cover or encompasses approximately one-quarter (¼) of the total FOV802,804,806.FIGS.8A-8Cshow a target position810of the exemplary wireless power receiver apparatus200in the respective FOV802,804,806.

In this example, the beam patterns with the largest beam-width, namely φ1, are configured to cover approximately ¼ of the total FOV, or use four beam directions to cover the entire FOV. The beam patterns P2are configured to cover approximately 1/16 of the total FOV. The beam patterns P3in this example are configured to cover approximately 1/64 of the total FOV. Thus, to cover the entire FOV, beam pattern P1uses four beam directions, beam pattern P216 beam directions, and beam pattern P364 beam directions. In alternate embodiments, any suitable technique to achieve different beam-width (covered area) and different gain (power delivered) may be used.

In one embodiment, the beam pattern P1can be used for initial detection purposes. The beam pattern P1in the example ofFIG.8Ais designed with the largest beam width. In this example, the beam pattern P1is also used to transmit the query power signal f1. The signal f1in this example is configured to provide a minimum input RF power that is delivered to the target wireless power receiver apparatus200to enable the target wireless power receiver apparatus802to transmit to the wireless power transmitter apparatus100, the fBSmodulated by the modulation component of the query power signal f1. In order to know which beam pattern P1, P2and P3should be configured, the wireless power receiver200will provide feedback to the wireless power transmitter100through backscatter signaling.

In one embodiment, the beam patterns P1, P2and P3can also be used for actual wireless power transfer if the target wireless power receiver apparatus200is close enough to the wireless power transmitter apparatus100. In the example ofFIG.8A, using the beam pattern P1, the wireless power transmitter apparatus100transmits signal f1in the four (4) possible directions. The four directions are selected to generally encompass the entire FOV802of the wireless power transmitter apparatus100. If a wireless power receiver apparatus200is located within the total FOV802of the wireless power transmitter apparatus100, there will be directions from which the backscatter carrier fBSmodulated by f1can be transmitted to the wireless power transmitter apparatus100.

In one embodiment, a direction from which an fBSis transmitted can be determined. For example, the signal f1is transmitted from the wireless power transmitter apparatus100in one direction at a time. If an fBCmodulated by signal f1is transmitted back and detected (also referred to herein as a “response” or backscatter signal fBS), the direction associated with the particular transmission of signal f1can be identified. In alternate embodiments, any suitable manner of determining a direction from which an fBSmodulated by a particular signal f1is transmitted can be used.

In one embodiment, the direction(s) from which a response(s) is received is verified and stored in the memory108. Then, while still using the beam pattern P1with the same beam width, the wireless power transmitter apparatus100switches to the signal f2. The wireless power transmitter apparatus100is configured to transmit the signal f2using beam pattern P1in the direction from which the response to signal f1was received. If the target wireless power receiver apparatus200is within a predetermined range of the wireless power transmitter apparatus100, the response to the signal f2may occur from specific direction that can be identified.

If a response to signal f2is received, fBCmodulated by f2, the wireless power transmitter100is configured to switch to the signal f3while still using the beam pattern φ1. The wireless power transmitter100will transmit the query power signal f3in the direction from which the response to query signal f2was received, which is stored in the memory. If a response to the query signal f3occurs, it means that there is a direction from which the beam pattern P1can be used to deliver sufficient power to keep the wireless power receiver200operating in a fully functional manner. Thus, for the identified direction, the wireless power transmitter apparatus100can deliver z dBm of RF power using beam pattern P1. The wireless power transmitter apparatus100can then switch to CW operation for wireless power delivery using the identified direction and beam pattern P1.

In one embodiment, if the target wireless power receiver apparatus200is beyond a predetermined range, or too far away, from the wireless power transmitter apparatus100, a narrower beam-width Pkto produce a higher gkmay be used in order to find a direction to deliver the required amount of power.

Referring toFIG.8C, the beam pattern P3represents the narrowest beam width of the patterns P1and P2. As shown inFIG.8C, the coverage area of the beam patterns P3, represented by the circular regions, are much narrower as compared to the coverage of P1and P2, due to the higher gain of P3.

If one were to use the beam pattern P3in each of the sixteen quadrants represented inFIG.8C, that would include trying sixty-four possible directions. Trying all sixty-four possible beam directions would not be practical and could be time consuming.

In one embodiment, after a response to signal f1using beam pattern P1is received, the wireless power transmitter apparatus100is configured to switch to signal f2with the same beam pattern P1. The wireless power transmitter apparatus100is configured to scan the direction(s) from which it had a response to the signal f1, using signal f2and beam pattern P1.

In a situation where the wireless power receiver200is far away, or beyond a pre-determined range, there will be no fBSto the query signal f2while using beam pattern P1. In this case, the wireless power transmitter apparatus100will switch to beam pattern P2, which has a narrower beam width than beam pattern P1, Thus, beam pattern P2will provide a higher gain and can deliver additional RF power.

Referring toFIG.8B, in one embodiment, the wireless power transmitter apparatus100is using beam pattern P2, with query signal f2. The wireless power transmitter apparatus100will scan the direction(s) from which it had a response to the query signal f1when using beam pattern P1. Since the beam pattern P2has additional gain, the four (4) sub-directions shown inFIG.8B, each covering 1/16 of the total FOV804, are scanned.

After a response to the query signal f2is detected, the wireless power transmitter apparatus100is configured to switch to the query power signal f3still using the beam pattern P2. The wireless power transmitter apparatus100is configured to scan the sub-directions806from which, in this example, it had a response to the signal f2, now using signal f3and beam pattern P2.

If a response is received from the target wireless power receiver apparatus200to the query signal f3and beam pattern P2this indicates that the wireless power receiver apparatus200is located at or within a range that the beam pattern P2can deliver z dBm of RF power to the target wireless power receiver apparatus200.

However, if there is no response to the signal f3from the target wireless power receiver200, the wireless power transmitter apparatus100is configured to switch to beam pattern P3, which, in this example, is narrower than beam pattern P2. The narrower beam pattern P3is configured to provide additional gain.

In the example ofFIG.8C, the wireless power transmitter apparatus100switches to the beam pattern P3and scans the sub-direction806. This procedure can be repeated until the wireless power transmitter apparatus100finds a direction from which a response to the signal f3occurs.

When an fBSis received that is modulated by f3, this indicates that the identified direction will enable the wireless power receiver apparatus200to collect the required RF power for its proper operation. Once this direction is determined, the wireless power transmitter apparatus100can switch to CW operation for full charging mode (100% duty-cycle) and switch S3ofFIG.4can be set to “open.” In one embodiment, the incremental gain between beam patterns P1, P2and P3is designed to match the incremental input RF power that is needed to successively switch ON/OFF T1at f1, f2and f3(gφ2−gφ1=y−x and gφ3−gφ2=z−y). When the wireless power receiver apparatus200is within the range of the wireless power transmitter apparatus100, the wireless power receiver apparatus200will successively answer to the different combinations of signals fnand beam patterns Pkand will guide the wireless power transmitter apparatus100until it delivers z dBm of RF power to the wireless power receiver apparatus200.

FIG.9illustrates an exemplary process flow900incorporating aspects of the disclosed embodiments. In this example, an exemplary procedure to deliver the required power to a specific wireless power receiver200by using N power query signals fQPSn(n=1, 2, . . . , N) and k (k=1, 2, . . . , K) beam patterns Pkwith different beam widths φkand gain gkis illustrated. Although the procedure shown inFIG.9is described with respect to sequential scanning, the aspects of the disclosed embodiments are not so limited. In alternate embodiments, any other scanning approach, algorithms or combinations may be used.

At the start at902of the process, the initial values for n of the query modulation signal portion fnof the fQPSand k for the beam pattern Pkare set at 904. In this example, the initial values are n=1 and k=1. The fQPSincludes or is associated with a wireless power transfer signal or carrier fWPT, the modulation component or low frequency oscillator signal fnand a beam pattern Pk. In one embodiment, the fWPTis mixed with fn.

In one embodiment, the query modulation signal f1for the fQPSand the beam width φ1of the beam pattern P1can be obtained from the look-up table in the memory110ofFIG.2. Generally, the values associated with n=1 and k=1 are such that if there is a target wireless power receiver apparatus200within the range or FOV of the wireless power transmitter100, the target wireless power receiver apparatus200will respond or answer to the query power signal fQPSwith query modulation signal f1.

In the first instance, the beam pattern P1has the widest beam width of all of the beam patterns Pkand a corresponding gain gk. The query modulation signal f1will generally be associated with a minimum amount of RF power that is received to have a first answer (backscatter signal fBS) from the wireless power receiver apparatus200. Concurrently with the transmission of the fQPS, an fBCis also transmitted or being transmitted.

In one embodiment, the fQPSwith f1and P1is transmitted at906. Generally, the fQPSis transmitted in all Dm, or Dm,k. In one embodiment, one fQPSis transmitted in one direction at a time.FIG.8Aillustrates an example of the fQPSwith query modulation signal f1being transmitted in all directions.

It is determined or detected at908if an fBSis received. The fBSgenerally comprises the fBCmodulated by the fn.

If it is determined that the fBShas been received, the Dmof the fQPSassociated with the received fBSis determined at910. In one embodiment, Dmof the fQPSis known and stored in the memory108ofFIG.2.

It is determined at912if a power delivery requirement of the wireless power receiver is met. If the wireless power receiver is receiving the required amount of power to operate, the wireless power transmitter apparatus can switch at914to the CW mode for wireless power delivery.

If it is determined at912that the power delivery requirement is not met, it is determined at916whether n is equal to N, where N is the last available fn. When n does not equal N, the value of n is increased at916to n+1. The fQPSwith fn, where n=n+1, is transmitted at906. Thus, in the example where n=1, the next fnis f2. In one embodiment, the RF power associated with query modulation signal f2is higher than the RF power associated with query modulation signal f1. The beam pattern P1in this example does not change.

If it is determined at916that n=N, in one embodiment, this generally indicates that wireless power receiver apparatus200is receiving the required amount of power. In one embodiment, the power delivery requirement and fn=fNhave the same meaning. The wireless power transmitter100can switch at914to CW mode of operation.

If it is determined at908that the fBSis not received, in one embodiment, it is determined at920if n=1 and k=1. If yes, the fQPScontinues to be transmitted at906with query modulation signal f1and beam pattern P1. Since the wireless power receiver apparatus200is in an energy depleted state, it cannot initiate a wireless power charge request. Thus, in this example, the wireless power transmitter apparatus100is configured to continue the querying process at906until a wireless power receiver apparatus200in need of charge comes into range of the wireless power transmitter apparatus100.

If it is determined at920that one or more of n is not equal to 1, or k is not equal to 1, it is determined at922whether the beam pattern Pk=PK, where K is the narrowest beam width of the beam patterns available. If k-K, meaning that the fQPShas been transmitted with the narrowest available beam pattern PK, the target wireless power receiver apparatus is determined at924to be out of range of the wireless power transmitter apparatus. In one embodiment, when it is determined at924that the target wireless power receiver apparatus200is out of range, the wireless power transmitter apparatus can resume or start at902the process900. In this manner, the wireless power transmitter apparatus100is configured to continue the process900until a wireless power receiver apparatus200in a depleted energy state comes into range of the wireless power transmitter apparatus100.

In one embodiment, during CW operation at914, from time to time, the wireless power receiver200shall send an “alive” signal to the wireless power transmitter apparatus100. If the “alive” signal is not received by the wireless power transmitter apparatus100within a predefined time window, this generally indicates that the wireless power receiver apparatus200is no longer in range or that it moved to a new position and it no longer can collect enough RF power to operate.

If so, a reset is triggered and a new detection/scanning is performed, such as that described above with respect toFIG.9. The “alive” signal may be transmitted by a dedicated communication module if available, or it can be transmitted by the backscatter module204of the wireless power receiver device200by driving an external signal418to the backscatter switch T1. This external signal can be generated by a low power microcontroller or any other controlled oscillator and can be connected to T1, as shown inFIGS.4and5. As described herein, during CW operation, the backscatter module204is free for other purposes and it may be used to transmit the “alive” signal.

The aspects of the disclosed embodiments enable the wireless power transmitter apparatus100to select a specific target wireless power receiver apparatus100. For that, the wireless power transmitter apparatus100may use additional query power signals fQPSnand fQPSn+1which are pulsed at specific frequencies fnthat match the desired wireless power receiver apparatus200.

For example, a first wireless power receiver apparatus, such as a humidity sensor, may use query modulation signals f1, f2and f3, and a second wireless power receiver apparatus, such as a temperature sensor, may use query modulation signals f4, f5and f6and so on. By transmitting an fQPSwith specific fn, the wireless power transmitter apparatus100is able to target the desired wireless power receiver apparatus200.

The aspects of the disclosed embodiments enable a rapid identification of an energy depleted wireless power receiver apparatus that cannot otherwise initiate signaling to request wireless power. The receiver can re-use the power query signals to provide the answer to the transmitter with zero latency. As soon as the remote apparatus receives a certain amount of energy, which is much lower than the energy used to keep it fully functional, it will instantaneously inform the transmitting system about its presence and if it is collecting at least a certain amount of RF power. There is no processing associated with the feedback mechanism.

The transmitter may also iteratively adjust the beam pattern based on the received feedback until it delivers the required amount of power to the remote power receiver. The aspects of the disclosed embodiments enable a fast selection of the best beam pattern and beam direction to transmit wireless energy towards a specific power receiver without trying every possible beam direction.