Patent Application
20180083488
The present disclosure relates generally to wireless power transfer and communication. More specifically, this disclosure relates to methods and apparatus for wirelessly communicating via electronic devices that may have small power storage units and/or small antennas (e.g., smart watches, mobile phones, compact fitness wearable devices, implantable devices, etc.).
Electronic devices may have small power storage units (e.g., batteries) and/or small antennas that provide poor inductive coupling. Accordingly, these electronic devices may not have any power or small amounts of power available when they are placed on a wireless charging device. Additionally, the small antennas and poor coupling of the electronic devices may mean that a smaller amount of power is transferred in a given power transfer instance (e.g., power beacon). Accordingly, when the electronic device is placed on the charging device, the electronic device may have insufficient power to communicate with the charging device to initiate charging procedures. Furthermore, the electronic device may be unable to communicate with the charging device to request additional power beacons due to the lack of power at the electronic device. Thus, there is a need for methods and apparatus for enabling the electronic devices having no or low power levels to effectively and efficiently communicate with the charging device with minimal power expenditures.
Various implementations of methods and devices within the scope of the appended claims each have several aspects, no single one of which is solely responsible for the desirable attributes described herein. Without limiting the scope of the appended claims, some prominent features are described herein.
An aspect of this disclosure is an apparatus for receiving power wirelessly. The apparatus may be characterized by an impedance having a reactance component and the apparatus comprises an antenna circuit, and a control circuit. The antenna circuit is configured to receive inductive power from a magnetic field generated by a power transmitter. The antenna circuit is also configured to communicate with the power transmitter. The control circuit is coupled to the antenna circuit and is configured to vary the reactance component of the impedance to a level sufficient for allowing detection as communication from the antenna circuit by the power transmitter.
An aspect of this disclosure is a method for receiving power wirelessly. The method is performed by an apparatus characterized by an impedance having a reactance component. The method comprises receiving inductive power from a magnetic field generated by a power transmitter. The method further comprises varying the reactance component of the impedance to a level sufficient for allowing detection of the varying as communication by the power transmitter. The method also comprises communicating with the power transmitter via varying the reactance component of the impedance.
Another aspect of this disclosure is another apparatus for receiving wireless power.
The apparatus is also characterized by an impedance having a reactance component. The apparatus comprises means for receiving inductive power from a magnetic field generated by a power transmitter. The apparatus also comprises means for varying the reactance component of the impedance to a level sufficient for allowing detection of the varying as communication by the power transmitter. The apparatus further comprises means for communicating with the power transmitter.
Details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims.
The various features illustrated in the drawings may not be drawn to scale. Accordingly, the dimensions of the various features may be arbitrarily expanded or reduced for clarity. In addition, some of the drawings may not depict all of the components of a given system, method or device. Finally, like reference numerals may be used to denote like features throughout the specification and figures.
The detailed description set forth below in connection with the appended drawings is intended as a description of exemplary implementations and is not intended to represent the only implementations in which the invention may be practiced. The term “exemplary” used throughout this description means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other exemplary implementations. The detailed description includes specified details for the purpose of providing a thorough understanding of the exemplary implementations. In some instances, some devices are shown in block diagram form.
Wirelessly transferring power may refer to transferring any form of energy associated with electric fields, magnetic fields, electromagnetic fields, or otherwise from a transmitter to a receiver without the use of physical electrical conductors (e.g., power may be transferred through free space). The power output into a wireless field (e.g., a magnetic field) may be received, captured by, or coupled by a “receiving coil” to achieve power transfer.
In one exemplary implementation, the transmitter 104 and the receiver 108 are configured according to a mutual resonant relationship. When the resonant frequency of the receiver 108 and the resonant frequency of the transmitter 104 are substantially the same or very close, transmission losses between the transmitter 104 and the receiver 108 are reduced. As such, wireless power transfer may be provided over a larger distance in contrast to purely inductive solutions that may require large antenna coils which are very close (e.g., sometimes within millimeters). Resonant inductive coupling techniques may thus allow for improved efficiency and power transfer over various distances and with a variety of inductive coil configurations.
The receiver 108 may receive power when the receiver 108 is located in the wireless field 105 produced by the transmitter 104. The wireless field 105 corresponds to a region where energy output by the transmitter 104 may be captured by the receiver 108. The wireless field 105 may correspond to the “near-field” of the transmitter 104 as will be further described below. The wireless field 105 may also operate over a longer distance than is considered “near field.” The transmitter 104 may include a transmit antenna 114 (e.g., a coil) for transmitting energy to the receiver 108. The receiver 108 may include a receive antenna or coil 118 for receiving or capturing energy transmitted from the transmitter 104. The near-field may correspond to a region in which there are strong reactance fields resulting from the currents and charges in the transmit antenna 114 that minimally radiate power away from the transmit antenna 114. The near-field may correspond to a region that is within about one wavelength (or a fraction thereof) of the transmit antenna 114.
The filter and matching circuit 226 may filter out harmonics or other unwanted frequencies and match the impedance of the transmitter 204 to the impedance of the transmit antenna 214. As a result of driving the transmit antenna 214, the transmit antenna 214 may generate a wireless field 205 to wirelessly output power at a level sufficient for charging a battery 236.
The receiver 208 may include a receive circuitry 210 that may include a matching circuit 232 and a rectifier circuit 234. The matching circuit 232 may match the impedance of the receive circuitry 210 to the receive antenna 218. The rectifier circuit 234 may generate a direct current (DC) power output from an alternate current (AC) power input to charge the battery 236, as shown in
The receiver 208 may be configured to determine whether an amount of power transmitted by the transmitter 204 and received by the receiver 208 is appropriate for charging the battery 236.
The antenna 352 may include an air core or a physical core such as a ferrite core (not shown).
The transmit or receive circuitry 350 may form/include a resonant circuit. The resonant frequency of the loop or magnetic antennas is based on the inductance and capacitance. Inductance may be simply the inductance created by the antenna 352, whereas, capacitance may be added to the antenna's inductance to create a resonant structure at a desired resonant frequency. As a non-limiting example, a capacitor 354 and a capacitor 356 may be added to the transmit or receive circuitry 350 to create a resonant circuit. For a transmit circuitry, a signal 358 may be an input at a resonant frequency to cause the antenna 352 to generate a wireless field 105/205. For receive circuitry, the signal 358 may be an output to power or charge a load (not shown). For example, the load may comprise a wireless device configured to be charged by power received from the wireless field.
Other resonant circuits formed using other components are also possible. As another non-limiting example, a capacitor may be placed in parallel between the two terminals of the circuitry 350.
Referring to
The transmit circuitry 402 may receive power through a number of power sources (not shown). The transmit circuitry 402 may include various components configured to drive the transmit antenna 404. In some exemplary implementations, the transmit circuitry 402 may be configured to adjust the transmission of wireless power based on the presence and constitution of the receiver devices as described herein. As such, the transmitter 400 may provide wireless power efficiently and safely.
The transmit circuitry 402 may further include a controller 415. In some implementations, the controller 415 may be a micro-controller. In other implementations, the controller 415 may be implemented as an application specified integrated circuit (ASIC). The controller 415 may be operably connected, directly or indirectly, to each component of the transmit circuitry 402. The controller 415 may be further configured to receive information from each of the components of the transmit circuitry 402 and perform calculations based on the received information. The controller 415 may be configured to generate control signals for each of the components that may adjust the operation of that component. As such, the controller 415 may be configured to adjust the power transfer based on a result of the calculations performed by it.
The transmit circuitry 402 may further include a memory 420 operably connected to the controller 415. The memory 420 may comprise random access memory (RAM), electrically erasable programmable read only memory (EEPROM), flash memory, or non-volatile RAM. The memory 420 may be configured to temporarily or permanently store data for use in read and write operations performed by the controller 415. For example, the memory 420 may be configured to store data generated as a result of the calculations of the controller 415. As such, the memory 420 allows the controller 415 to adjust the transmit circuitry 402 based on changes in the data over time.
The transmit circuitry 402 may further include an oscillator 412 operably connected to the controller 415. The oscillator 412 may be configured as the oscillator 222 as described above in reference to
The transmit circuitry 402 may further include a driver circuit 414 operably connected to the controller 415 and the oscillator 412. The driver circuit 414 may be configured as the driver circuit 224 as described above in reference to
The transmit circuitry 402 may further include a low pass filter (LPF) 416 operably connected to the transmit antenna 404. The low pass filter 416 may be configured as the filter portion of the filter and matching circuit 226 as described above in reference to
The transmit circuitry 402 may further include a fixed impedance matching circuit 418 operably connected to the low pass filter 416 and the transmit antenna 404. The matching circuit 418 may be configured as the matching portion of the filter and matching circuit 226 as described above in reference to
Transmit antenna 404 may be implemented as an antenna strip with the thickness, width and metal type selected to keep resistance losses low.
The receive circuitry 502 may be operably coupled to the receive antenna 504 and the load 550. The receive circuitry may be configured as the receive circuitry 210 as described above in reference to
The receive circuitry 502 may include a processor-signaling controller 516 configured to coordinate the processes of the receiver 500 described below.
The receive circuitry 502 provides an impedance match to the receive antenna 504. The receive circuitry 502 includes power conversion circuitry 506 for converting a received energy into charging power for use by the load 550. The power conversion circuitry 506 includes an AC-to-DC converter 508 coupled to a DC-to-DC converter 510. The AC-to-DC converter 508 rectifies the AC energy signal received at the receive antenna 504 into a non-alternating power while the DC-to-DC converter 510 converts the rectified AC energy signal into an energy potential (e.g., voltage) that is compatible with the load 550. Various AC-to-DC converters are contemplated including partial and full rectifiers, regulators, bridges, doublers, as well as linear and switching converters.
The receive circuitry 502 may further include a matching circuit 512. The matching circuit 512 may comprise one or more resonant capacitors in either a shunt or a series configuration. In some implementations these resonant capacitors may tune the receive antenna to a specific frequency or to a specific frequency range (e.g., a resonant frequency).
The load 550 may be operably connected to the receive circuitry 502. The load 550 may be configured as the battery 236 as described above in reference to
In some implementations, the chargeable device 610 may be within a charging region of the charging device 605 (e.g., placed on a charging surface of the charging device 605). When the charging device 605 is configured to charge other devices (e.g., in a charging mode), the charging device 605 may broadcast one or more beacon signals (“beacons”) to communicate with chargeable devices placed within its charging region. Additionally, these beacons (or other beacons broadcast by the charging device 605) may provide power to the chargeable device 610 within its charging region. These beacons may be used to communicate any necessary information (e.g., identification and detection of presence of charging device, charging parameters, charging details, device specifics, etc.) that may relate to the effective and safe charging of the chargeable device 610). In some implementations, examples of these parameters may include output current, output voltage, etc. These beacons may also provide power to the chargeable device 610 to allow the chargeable device 610 to be able to communicate with the charging device 605. For example, the chargeable device 610 may receive the power and/or communication beacon and communicate back to the charging device 605 via Bluetooth, near field communications (NFC), or another power transfer independent communication method or via back scattering or other in band communications.
In some embodiments, the chargeable device 610 may not receive sufficient power (i.e., an amplitude of an induced voltage at the chargeable devices may be too small) from the power/communication beacon broadcast by the charging device 605. This may be caused by low coupling between the charging device 605 and the chargeable device 610, for example, due the small size of the chargeable device 610 and/or their antennas. The small induced voltage may result in the chargeable device 610 having insufficient power to “boot” and enter a charging relationship with the charging device 605 (e.g., begin receiving charging power from the charging device 605). Accordingly, the chargeable device 610 may use power (i.e., the received power or power stored in the chargeable devices) to broadcast a long beacon extension (LBE) request to the charging device 605. The LBE request may comprise a request that a longer power/communication beacon be broadcast by the charging device 605 to provide the chargeable device 610 with sufficient energy to establish charging relationships as described herein.
In some implementations, the LBE request may simulate a pulsating large load at a given frequency and with a given amplitude (e.g., using one or more large and long power pulses). These simulated pulses may be generated as back scatter or in band signaling communications by the chargeable device 610 for the charging device 605 to identify. However, such pulses, which effectively change an impedance of the chargeable device 610 as seen by the charging device 605, may have specific requirements for the charging device 605 to be able to identify them as communications from the chargeable device 610. For example, to enable the charging device 605 to identify the power pulses as back scatter or in band signaling, the power pulses may need a power (amplitude) of at least 500 mW and a period of 10 ms with a duty cycle of 50% at the chargeable devices 610.
In some implementations, an amount of power that the chargeable device 610 receives from the beacon broadcast by the charging device 605 may be directly associated with a size of the receiving antenna of the chargeable device 610. Accordingly, when the chargeable device 610 (e.g., a wearable device or an implant, or other chargeable electronic device that may have an antenna with a size smaller than that of the transmitting antenna of the charging device 605) is placed within the charging area of the charging device 605, the chargeable device 610 may receive insufficient power via the beacon to communicate effectively with the charging device 605. In such a situation, when the chargeable device 610 is placed within the charging region of the charging device 605, the chargeable device 610 will not be charged by the charging device 605. Thus, the small chargeable device 610 including the receiver antenna that is smaller in size than the transmitting antenna of the charging device 605 may utilize another mechanism of generating the LBE and/or communicating with the charging device 605.
The impedance adjustment circuit 714 may comprise one or more components configured to adjust, tune, and/or modulate an impedance of the receiver 700. In some embodiments, the impedance adjustment circuit 714 may be integrated with one or more of the circuits of the receiver 700, such as the matching circuit 512.
The impedance (Z) of the receiver 700 is typically made up of two components: a resistance component (R, corresponding to a “real part” of the impedance, Z) and/or a reactance component (X, corresponding to an “imaginary part” of the impedance, Z). The impedance Z of the receiver 700 may be represented in of the resistance R and the reactance X components, as shown in Equation 1:
Z=R+jX (Equation 1)
The impedance adjustment circuit 714 may be configured to tune or modify the reactance component X of the impedance Z of the receiver 700, thereby varying the impedance Z of the receiver 700 as seen by the charging device 605 (of
The impedance adjustment circuit 714 may be operably coupled to the antenna 504, the controller 516, and the load 550 directly or via one or more other circuits. The controller 516 may be configured to control the one or more capacitors and/or inductors of the impedance adjustment circuit 714 to cause the reactance component X and/or the resistance component R of the receiver 700 to be changed and/or adjusted. These changes may generate the power pulses for communication by the receiver 700 to the charging device 605, as described herein. The change in the reactance component X of the impedance Z of the receiver 700 as seen by the charging device 605 may be more easily detectable by the charging device 605 than corresponding changes to the resistance component R. This may be because the reactance component X changes may detune a transmit circuit of the charging device 605. In other words, the charging device 605 may be more sensitive to changes in the reactance component X of the impedance Z of the receiver 700 as compared to changes in the resistance component R. Therefore, the reactance component X changes by the impedance adjustment circuit 714 may be result in shorter duration and/or lower power pulses by the receiver 700 as compared to corresponding power pulses due to resistance component R changes of the impedance Z of the receiver 700.
For example, when the impedance Z of the receiver 700 as seen by the charging device 605 is changed by modulating the resistance component R, the corresponding power pulses may need at least a 10 ms duration and a 50% duty cycle. However, when the impedance Z of the receiver 700 is changed by modulating the reactance component X, the corresponding power pulses may need only a 20 μs duration and less than a 50% duty cycle. In some aspects, the duty cycle may be greater than 50%. Accordingly, the duty cycle may be any value while the duration of the pulses is approximately 20 μs. Furthermore, the shorter duration pulses may result in less wasted power than the longer duration pulses of changes to the resistance component R of the impedance Z, as the power from the pulses is generally shunted to ground and/or through a dissipative component of the receiver 700, and thus lost as thermal energy.
Furthermore, when the impedance Z of the receiver 700 as seen by the charging device 605 is changed by modulating the resistance component R, the corresponding power pulses may need at least a 500 mV amplitude at the receiver 700. However, when the impedance Z of the receiver 700 is changed by modulating the reactance component X, the corresponding power pulses may need only an amplitude of less than 100 mV at the receiver 700. The reduced amplitude that still results in detection by the charging device 605 may also result in less wasted power, as less power is expended by the receiver 700 to generate the pulses that communicate with the charging device 605.
Furthermore, while communicating back to the charging device 605 for extending the long beacon using modulation of its reactance component X, the receiver 700 has to control the power to its output without (1) damaging the chargeable device 610, (2) dissipating too much power (e.g., as heat that may cause excessive power loss), or (3) losing excessive power to components of the receiver 700 (e.g., the load 650) that may utilize received power for various tasks. In some implementations, the excessive power dissipation may cause an increase in a temperature of the chargeable device 610 that could damage receiver 700 and the power lost to the power dissipation may not be available for more vital purposes.
The methods and apparatus described herein allow for the control of the output power of the receiver 700 while enabling the receiver 700 to participate in back scatter or in band signaling communications. In some implementations, the impedance adjustment circuit 714 may be configured to alternate between “capacitive” and “inductive” reactance component X changes as seen by the charging device 605. This may be accomplished by adjusting the impedance Z with the impedance adjustment circuit 714 to be above and/or below resonance by modulating the impedance Z with either the capacitive or the inductive reactance X. The resonance of the receiver 700 may occur when the capacitive and inductive reactances are equal in magnitude and cancel because they are 180 degree out of phase from each other (e.g., the capacitive reactance has a negative value corresponding to a positive inductive reactance value and the sum of both equals zero). The impedance Z may be increased by increasing the inductive reactance X, as the inductive reactance component of the impedance Z is positive. The impedance Z may be reduced by increasing the capacitive reactance X, as the capacitive reactance component of the impedance Z is negative. Thus, increasing the inductance reactance X may change the resonance of the receiver 700 to be above resonance while increasing the capacitive reactance X may change the resonance of the receiver 700 to be below resonance.
As described herein, power received by the receiver 700 may be maximized at resonance (e.g., when the capacitive and inductive reactances cancel). As the impedance increases (e.g., the impedance moves away from resonance), an amount of power received by the receiver 700 may drop. However, the power received by the receiver 700 may be controlled by detuning one or more components of the receiver 700. Thus, changes in the impedance may be compensated for by creating a positive reactance (via the inductive reactance) or a negative reactance (via the capacitive reactance). The power received by the receiver 700 versus the reactance of the receiver 700 shown as a graph (not shown) may have a bell shape where power received is maximized when the reactance is zero.
Such alternating between positive and negative reactance components X may allow the charging device 605 to more easily identify and/or detect impedance Z changes at the receiver 700. Thus, the receiver 700 may enable communications with the charging device 605 by maintaining a magnitude of impedance but changing the sign of the impedance via alternating the capacitive or inductive reactance component values. Additionally, the alternating between positive and negative reactance components X may further simplify the maintenance of output power by the receiver 700, which is especially advantageous in minimizing: (1) damage to the receiver 700 and/or the chargeable device 610, (2) excessive power dissipation, and/or (3) loss of power to the components of the receiver 700. Additionally, such alternating between positive and negative reactance components X may provide simplified communications between the receiver 700 and the charging device 605 during power transfer (e.g., charging of the chargeable device 610). The receiver 700 may maintain its output power at desired levels while switching between the capacitive and inductive reactance X modulations/variables to communicate zeros and ones to the charging device 605. The changing of the sign of the reflected reactance component X may be effected by jumping between positive and negative reactance component X values (corresponding to frequencies above and below resonance). For example, a positive reactance component X value causes the receiver 700 to effectively change its resonant frequency to be above the frequency at which the receiver 700 operates (for receiving power and/or communicating). Similarly, a negative reactance component X value causes the receiver 700 to effectively change its resonant frequency to be below the frequency at which the receiver 700 operates. In some implementations, maintaining the output power may comprise maintaining a level of power output to the load 550 to be within a desired threshold range, where the threshold range is either determined by the user or by design of the load 550, while changing the impedance of the receiver 700. In some implementations, the threshold range may include limits beyond which the load 550 will receive insufficient power to operate or may be damaged by the power levels received.
In some embodiments, the receiver 700 may further comprise a rectifier circuit (not shown) configured to modulate a phase displacement between a phase of a current of the receiver 700 and a phase of a voltage of the receiver 700. Modulation of a phase displacement may comprise movement of the phase of the current with regard to the phase of the voltage. In a synchronous rectifier, there is a defined phase between the current and voltage that pass through the rectifier. By using an appropriate rectifier circuit, the phase of the current with regard to the phase of the voltage may be varied or modulated. By changing the phase of the current with respect to the phase of the voltage, an amount of power output or transferred to a load may be varied. Additionally, this phase modulation may also be used to vary or modulate the impedance of the receiver 700 (both the resistance component R and the reactance component X). In some embodiments, the rectifier circuit may be used in combination with the impedance adjustment circuit 714 to adjust an impedance of the receiver 700 while maintaining a constant output to the load 550 of the receiver 700.
In some implementations, an additional inductor (not shown) may be included in the diagram 750. If the additional inductor is a variable inductor, then the additional inductor could contribute to the change of impedance by adding a variable inductive component, thus corresponding to the impedance adjustment circuit 714. However, the additional inductor may be lossy. In some implementations, the EMI filter may reduce harmonics generated by the rectifier (since it is a non-linear circuit) and may limit an effect of the harmonics on the receive antenna 504. In some implementations, the variable capacitor U2 may be replaced by a combined variable capacitance and variable inductance component or circuit.
Since the reactance component X changes from pulses of substantially less than 10 ms durations result in sufficiently large impedance Z variations as seen by the charging device 605, an output capacitor (e.g., capacitor C17) may be used to filter an output voltage. The output capacitor may be more efficient and less costly (with regard to component cost and circuit size/spacing). In some implementations, the output capacitor may function as an output regulator, or may be replaced by another component that functions as the output regulator. This is because the output voltage of the receiver 700 during the generated pulses stays within acceptable ranges of the receiver 700 without requiring a shunt regulator.
The first graph 902 shows input power of the charging device 605 as a function of time. Power is shown along the y-axis in milliwatts (mW) while time is shown along the x-axis in microseconds (μs). As shown, the input power of the charging device 605 approaches 100 mW between 0 and 20 μs and 40 μs and 60 μs. The input power of the charging device 605 approaches 0 mW between 80 μs and 100 μs and above approximately 120 μs. Between 20 μs and 40 μs, the graph 902 shows the input power of the charging device 605 as rising approximately 300 mW to approximately 400 mW. Between 60 μs and 80 μs, the graph 902 shows the input power of the charging device 605 as rising approximately 650 mW to approximately 750 mW. Between 100 μs and 120 μs, the graph 902 shows the input power of the charging device 605 as rising over 800 mW to approximately 1000 mW. Accordingly, the graph 902 shows the input power of the charging device 605 as it rises and falls corresponding to power pulses generated by the receiver 700.
The second graph 904 shows a reactance X of the receiver 700 as seen by the charging device 605, as a function of time. The reactance X is shown along the y-axis in Ω while time is shown along the x-axis in microseconds (μs). As shown, the reactance X seen by the charging device 605 approaches −20Ω between 0 and 20 μs. The reactance X seen by the charging device 605 approaches −24Ω between 40 and 60 μs. The reactance X seen by the charging device 605 approaches −30Ω between 80 and 100 μs. Between 20 and 40 μs, the graph 904 shows the reactance X as seen by the charging device 605 as it rises to and levels off at approximately −15Ω. Between 60 and 80 μs, the graph 904 shows the reactance X as seen by the charging device 605 as it rises to and levels off at approximately −7Ω. Between 100 and 120 μs, the graph 904 shows the reactance X as seen by the charging device 605 as it rises to and levels off at approximately −5Ω. Accordingly, the graph 904 shows that for each of the power pulses, the reactance X of the receiver 700 as seen by the charging device 605 increases according to the power received with the power pulses.
The third graph 906 shows a rectified voltage (Vrect) of the receiver 700, as a function of time. Vrect is shown along the y-axis in V while time is shown along the x-axis in microseconds (μs). The graph 906 shows the reactance X of the receiver 700 as seen by the charging device 605 as it rises and falls corresponding to pulses generated by the receiver 700. As shown, the Vrect of the receiver 700 remains level or decreases between 0 and 20 μs, 40 to 60 μs, 80 to 100 μs, and above 120 μs. Between 20 and 40 μs, the graph 906 shows the Vrect of the receiver 700 increasing from 3 to approximately 3.2 V. Between 60 and 80 μs, the graph 906 shows the Vrect the receiver 700 increasing from 3.2 V to approximately 3.6 V. Between 100 and 120 μs, the graph 906 shows the Vrect of the receiver 700 increasing from 3.55 V to approximately 4.0 V. Accordingly, the graph 906 shows that for each of the power pulses, the Vrect of the receiver 700 rises but stays below a critical value of 5.0 V.
When viewed together, the three graphs 902, 904, and 906 show that the short duration pulses (˜20 μs) generate reactance component X changes that are seen by the charging device 605 during the power pulses having magnitudes of between approximately 300 and 900 mV without the pulses exceeding the Vrect requirements of the receiver 700.
The first graph 1002 shows input power of the charging device 605 as a function of time. The power is shown along the y-axis in milliwatts (mW) while time is shown along the x-axis in microseconds (μs); times described herein in relation to the figures may be approximate. The graph 1002 shows the input power of the charging device 605 as it rises and falls corresponding to power pulses generated by the receiver 700 (for example by a boost rectifier). As shown, in comparison with the graphs of
The second graph 1004 shows a rectified voltage (Vrect) of the receiver 700, as a function of time. The rectified voltage is shown along the y-axis in volts (V) while time is shown along the x-axis in microseconds (μs). The graph 1004 shows the reactance X of the receiver 700 as seen by the charging device 605 as it rises and falls corresponding to pulses generated by the receiver 700. As shown, the Vrect of the receiver 700 remains approximately level between 0 and 20 μs, 40 to 60 μs, 80 to 100 μs, and above 120 μs. Between 20 and 40 μs, the graph 1004 shows the Vrect of the receiver 700 maintaining at approximately 3.02 V. Between 60 and 80 μs, the graph 1004 shows the Vrect the receiver 700 increasing from approximately 3.03 V to approximately 3.05 V. Between 100 and 120 μs, the graph 1004 shows the Vrect of the receiver 700 increasing from 3.05 V to approximately 3.3 V. Thus, the graph 1004 shows that for each of the power pulses, the Vrect rises at a less substantial rate than in
The third graph 1006 shows a reactance X of the receiver 700 as seen by the charging device 605, as a function of time. The reactance X is shown along the y-axis in S2 while time is shown along the x-axis in microseconds (μs). As shown, the reactance X seen by the charging device 605 approaches −15Ω between 0 and 20 μs, between 40 and 60 μs, and between 80 and 100 μs. Between 20 and 40 μs, the graph 1006 shows the reactance X as seen by the charging device 605 as it maintains at approximately −15Ω. Between 60 and 80 μs, the graph 1006 shows the reactance X as seen by the charging device 605 as it rises to and levels off at approximately −10Ω. Between 100 and 120 μs, the graph 1006 shows the reactance X as seen by the charging device 605 as it rises to and levels off at approximately −1.5Ω. Accordingly, the graph 1006 shows that for each of the power pulses, the reactance X of the receiver 700 as seen by the charging device 605 increases (e.g., approaches zero) in relation to the power received with the power pulses, because the power received by the receiver 700 increases as the reactance of the receiver 700 approaches zero.
When viewed together, the three graphs 1002, 1004, and 1006 show that the low amplitude modulated pulses generate reactance component X changes that are seen by the charging device without the pulses exceeding the Vrect requirements of the receiver 700.
An apparatus for receiving wireless power may perform one or more of the functions of method 1100, in accordance with certain aspects described herein. The apparatus may be characterized by an impedance having a reactance component. The apparatus may comprise a means for receiving inductive power from a magnetic field generated by a power transmitter. In certain aspects, the means for receiving inductive power from a magnetic field generated by a power transmitter can be implemented by the receive antenna 504 (
In some embodiments, an apparatus for receiving wireless power may comprise, in some aspects, the receiver 700 and the receiver 700 may perform associated functions and methods described herein.
The various operations of methods described above may be performed by any suitable means capable of performing the operations, such as various hardware and/or software component(s), circuits, and/or module(s). Generally, any operations illustrated in the Figures may be performed by corresponding functional means capable of performing the operations.
Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.
The various illustrative logical blocks, modules, circuits, and method steps described in connection with the implementations disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. The described functionality may be implemented in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the implementations.
The various illustrative blocks, modules, and circuits described in connection with the implementations disclosed herein may be implemented or performed with a general purpose hardware processor, a Digital Signal Processor (DSP), an Application Specified Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose hardware processor may be a microprocessor, but in the alternative, the hardware processor may be any conventional processor, controller, microcontroller, or state machine. A hardware processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The steps of a method and functions described in connection with the implementations disclosed herein may be embodied directly in hardware, in a software module executed by a hardware processor, or in a combination of the two. If implemented in software, the functions may be stored on or transmitted as one or more instructions or code on a tangible, non-transitory computer readable medium. A software module may reside in Random Access Memory (RAM), flash memory, Read Only Memory (ROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), registers, hard disk, a removable disk, a CD ROM, or any other form of storage medium known in the art. A storage medium is coupled to the hardware processor such that the hardware processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the hardware processor. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer readable media. The hardware processor and the storage medium may reside in an ASIC.
For purposes of summarizing the disclosure, certain aspects, advantages and novel features s have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular implementation. Thus, the present disclosure may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.
Various modifications of the above-described implementations will be readily apparent, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the implementations shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
