Efficient Wireless Power Receiver

Abstract

This dual-mode DC / DC converter system for use in a wireless power transmitter / receiver uses conventional logic circuits operating at voltages well above 1V to efficiently drive the DC / DC converter circuit while being powered from a low voltage, less than 1V, output by a photovoltaic cell. Two separate control modules may control the DC / DC converter. The first uses a simple control to switch the converter and can be powered by the low voltage generated by the PV. Once a voltage above approximately 1.5V is generated at the output of the DC / DC converter, a second, more complex controller becomes powered up and controls the voltage conversion process. The second, more complex controller can efficiently drive the converter and adapt its control functions to respond to logic input commands and received sensor outputs. The complex controller may operate independently or in conjunction with the simple controller to further increase efficiency.

Description

[Technical Field]

[0001] SUMMARY This disclosure describes techniques related to the field of receiver design in systems for wireless power transmission, and in particular, techniques for optimizing the efficiency and operation of such receivers across all phases of their operation. [Background technology]

[0002] Wireless power systems in which a transmitter transmits electromagnetic power in the form of a beam from the transmitter to a remote electronic device are well known in the art. The remote electronic device may include a receiver for receiving and controlling the power and a device for using or storing the received power. Such systems are described in the following patent publications and patents: U.S. Patent No. 6,299,234 for "Directional Optical Transmitter and Receiver," U.S. Patent No. 6,299,234 for "Wireless Laser Power Transmitter," U.S. Patent No. 6,299,234 for "Spatially Distributed Laser Resonator," U.S. Patent No. 6,299,234 for "System for Optical Wireless Power Supply," U.S. Patent No. 6,299,234 for "Wireless Power Distribution System," U.S. Patent No. 6,299,234 for "System for Optical Wireless Power Supply ...Multiple Beam Wireless Power Transmission System," and U.S. Patent No. 6,299,234 for "Wireless Power Transmission System," all commonly owned by the present applicant. These systems consist of a transmitter that generates a power beam (typically a laser beam) and a receiver that converts the beam into usable power for use by or storage for use by a client device or for other electronic circuitry not part of the receiver.

[0003] The transmitter typically includes a beam generator, a beam deflection system used to direct the beam toward the receiver, and in most cases must also include a safety system. The safety system often relies on feedback from the receiver to indicate that the power beam has been received, assist in centering the beam on the receiver's power absorbing element, and carry identification data on the receiver back to the transmitter so that safety deviations from the planned transmission can be detected and corrected. Such a communication channel, often referred to as a "back channel" or "feedback channel," uses a signal emitter in the receiver to send feedback information and a signal detector in the transmitter to receive feedback information from the receiver.

[0004] The primary function of a receiver is to generate power for use by other systems or components or to store energy for current or future use. Such other systems may include products such as mobile phones or laptops, or products that use remote wireless charging rather than being connected to a mains power source or having replaceable batteries. The receiver is often built into the product or device it is designed to supply power to, with some of the receiver's components located on the same subsystem as components of that client device or product, or distributed around the client product or device. The term "client" is used herein to describe a product or device that is the ultimate user of the wirelessly transmitted power. Therefore, in light of these descriptions, the receiver is distinguished from any other part of a product with which it may be integrated or with which it may be intended to operate. That is, the receiver is the part of such an integrated product that receives power transmission from a power transmitter and handles and processes the received power until it is stored in a storage device such as a battery or capacitor, or until it is provided for use by the product in which it is incorporated or an associated product. All other parts of such products come under the heading of "Client", particularly those relating to the end use of electricity.

[0005] The disclosures of each publication mentioned in this section and other sections of the specification are each incorporated herein by reference in their entirety. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2007 / 036937 [Patent Document 2] International Publication No. 2009 / 083990 [Patent Document 3] International Publication No. 2012 / 172541 [Patent Document 4] International Publication No. 2017 / 009854 [Patent Document 5] International Publication No. 2017 / 033192 [Patent Document 6] International Publication No. 2017 / 158605 [Patent Document 7] International Publication No. 2017 / 179051 [Patent Document 8] International Publication No. 2019 / 135226 [Patent Document 9] U.S. Patent No. 11,444,491 [Patent Document 10] International Publication No. 2017 / 033192 Summary of the Invention

[0007] The present disclosure seeks to provide novel systems and methods that overcome at least some of the drawbacks of prior art systems and methods. This disclosure describes new exemplary receiver configurations intended for use in wireless power transmission systems that have high efficiency, resulting in improved overall power transmission efficiency over currently used receivers. While these new receiver configurations are advantageous for any receiver capable of transmitting wireless energy to a receiver client device, they are particularly advantageous for systems that do not include a permanent power source, such as a battery, and that are powered solely by a laser beam illuminating an optical-to-electrical power converter (typically a photovoltaic cell, in the case of an optical power beam). Additionally, these new configurations are also useful when a battery cannot be used to power the internal components of the receiver, such as when the battery is external to the receiver or is severely depleted.

[0008] The most common form of local wireless power transmission is optical transmission using a laser beam, and although this is the example used in this disclosure to illustrate such a wireless power receiver, it should be understood that the receiver described and claimed in this disclosure is intended to cover all forms of wireless power transmission and reception, including radio frequency electromagnetic wave transmission that uses an antenna for the receiving process.

[0009] Generally, a receiver includes a number of electronic subsystems or components that have the following functions: (a) An energy converter that converts electromagnetic beams into electrical energy. In the case of optical power transmission, this is achieved through the use of photovoltaic (PV) cells or arrays. In this disclosure, the optical case with PV is used as an example implementation, but it should be understood that the receivers described herein are not intended to be limited to optical receivers. (b) A maximum power point tracking (MPPT) circuit or similar circuit that optimizes power extraction from a photovoltaic energy converter. Such optimization typically considers the maximum power point, but may also consider other factors, such as safety, PV voltage limits, PV temperature limits, required output voltage, battery availability, and, especially, the overall safety and efficiency of the system, to set a reference load on the PV for optimal operating conditions. Such a circuit is necessary for MPPT because the efficiency of power transfer from a PV cell depends on the power level and degree of focusing of the incident beam, the temperature of the PV cell, and the electrical characteristics of the load to which the incident power is directed. As these conditions change, there are changes in the load characteristics and load impedance that provide the highest power transfer. The system is optimized to maintain the most efficient power transfer as the load characteristics change. MPPT is the process of adjusting the load characteristics as the power source conditions change and as the load conditions change. A well-designed MPPT circuit presents an optimal load to the photovoltaic cell and then converts the voltage, current, or frequency to suit other devices or systems. However, the optimization circuit may alternatively be designed to maximize system efficiency rather than maximize PV efficiency, taking into account DC / DC conversion, PV temperature, phosphor yield, and other factors. (c) One or more sensors for measuring the power produced by the receiver, the incident beam characteristics, any safety-related parameters, and in some cases other parameters. (d) A DC / DC converter circuit converts the voltage of the power generated by the PV cell to a voltage level useful for the efficient operation of conventional electronic circuits. IR-optimized PV cells typically output current at low voltages, typically less than 1 V, much lower than the voltages required for the operation of electronic semiconductor devices, especially digital electronic components in logic circuits. MPPT optimization typically dictates the generation of a voltage that varies based on operating conditions, but this voltage may be inappropriate for many electronic circuits. For example, if 1 W of power is converted to 5 V by the MPPT circuit, 1 W of power will be obtained at 5 V (ignoring losses due to the conversion process). However, if a client device, including any energy storage devices and load components, requires only 0.5 W at 5 V, it is important to continue providing power at 5 V to avoid damage to the client device components. As a result, operation at the maximum power point is impossible, and DC / DC conversion must be performed independently of the MPPT. A DC / DC converter is a boost converter adapted to output a current at a voltage that allows the operation of electronic circuits at a high level of efficiency, usually 5V but typically 1.7V, 3.7V, 7.6V, 12V, or other voltages that are specific to a given electronic circuit.

[0010] One problem that wireless power receivers must address is that the amount of power the receiver receives from transmitted wireless power is limited, variable, and unpredictable because it depends on receiving a beam from the transmitter. In particular, to conserve onboard stored power, receivers are typically placed in sleep mode or turned off, requiring a minimum input energy to wake up and begin receiving transmitted power. Such a wake-up process, using a first minimum amount of energy, is described in commonly owned U.S. Patent No. 6,244,999, entitled "Wireless Power Distribution System." Additionally, when a transmitter is searching for a receiver to which wireless power is to be transmitted, the level of power transmitted to the receiver is very low until the transmit beam locks onto a receiver found during the scan, resulting in a low output voltage of the PV cell. As a result, the receiver initially operates at a very low efficiency and is unable to quickly achieve an output power level corresponding to the power transmitted by the transmitter to the receiver.

[0011] Light-to-power converters typically generate voltages below 1 V. Most currently available digital electronic components, especially logic circuits, require high voltages to operate. Due to this limitation, and because the availability of components, especially logic components, that operate at such low voltages is very limited, prior art receiver controllers are generally powered from the output of a DC / DC converter rather than directly from the PV cell. Designing an efficient circuit with a controller powered from the voltage generated by the photovoltaic cell without DC / DC conversion remains very challenging.

[0012] Simple converters have low efficiency and offer only limited control over the output voltage. On the other hand, complex logic-based DC / DC converters have high current conversion efficiency, making them much more advantageous for use in wireless power systems, but they require voltages significantly greater than 1 V to operate, and such voltage levels are generally not available from PV cells. This is particularly true during search and start-up procedures, and especially for use in systems that do not have an additional voltage source such as an on-board battery, and therefore rely solely on power received from the wireless power transmission system.

[0013] This disclosure describes a novel DC / DC converter system for use in a wireless power transmitter receiver that allows conventional logic circuits operating at voltages well above 1 V to be used to efficiently drive the DC / DC converter circuitry and MPPT or similar optimization circuitry while being powered solely from the low-voltage PV output.

[0014] The present system achieves this by using two separate control modules to control the DC / DC conversion functions. The first, initial voltage conversion is performed using a simple, basic control module, either analog or digital, to control the operation of the converter's switching sequence. Such a simple control module can be as basic as a predetermined fixed-frequency source, a signal generator that outputs a pulsed or sinusoidal signal, or a function generator, and therefore has the advantage of being able to be implemented without electronic logic functions and be powered by voltages significantly below 1.5V or even below 1V (these are the voltage levels generated by PV systems). However, such simple switching control of the converter results in less than optimal conversion efficiency and lacks logic-based adaptive features that can adapt to changing conditions, such as changes in power or environmental changes. Throughout this disclosure, such simple control systems will be referred to as simple or basic control modules or functions to distinguish them from more complex control systems that include logic circuit functions.

[0015] Once a voltage greater than approximately 1.5V is generated at the output of the DC / DC converter, a second primary controller is powered up from this higher voltage to control the voltage conversion process. Now supplied with a suitably high voltage, this primary controller is able to drive the converter in an efficient manner and also adapt its control functions in response to received logic input commands. Such a primary controller operating at a higher voltage can be more complex than a simple first-stage controller, incorporating multiple logic function circuits, receiving multiple sensor inputs, and generating calculated output commands based on those inputs. Thus, this primary controller can be designed to adapt to a variety of different parameters, such as current requirements and availability, desired output voltage, client device requirements, environmental or operating temperature, and other variable parameters, while still providing a stable level of desired output to the client device.

[0016] The first, low-efficiency, simple controller mode is therefore temporary, allowing direct operation from the PV, for example, while the PV is outputting a low voltage from the transmitter's low-power scanning mode. During low-efficiency controller operation, many of the receiver subsystems are turned off or in a power-saving, sleep, or at least wake-up mode while they are on. Such systems include the backchannel transmission system, the ADC, and the main controller. In many cases, even client devices may be disconnected from the DC / DC converter output during this first phase.

[0017] The second, high efficiency controller mode is the mode in which the converter operates once it is fully powered up and supplying power to a client device. In this mode, the majority of the generated power is supplied to the client, while only a small portion is used to operate the power receiver itself with all of the associated sub-circuitry, such as the back-channel link mentioned above, the power conversion function itself, the MPPT circuitry, and other functions described in more detail in the Detailed Description section below.

[0018] That is, the receiver of the present disclosure achieves high efficiency by implementing two operating modes for the voltage converter function: a low efficiency mode and a subsequent high efficiency mode, each with its own characteristics and distinct functionality.

[0019] Low efficiency mode is (a) The switch of the DC / DC converter is operated by the circuit supplied by the PV; (b) the back-channel communication system is inoperable; and (c) the primary controller is off or asleep at the start of this low efficiency mode and turns on only when this mode is completed or near completion; (d) the system's analog-to-digital circuitry (ADC) is off at the start of this mode and turns on only when this mode is complete or near completion; (e) The client device may in some cases be disconnected from the output of the DC / DC converter; It features some of the following:

[0020] High efficiency mode is (f) the primary controller is on and is powered by the output of the inductor of the DC / DC converter if only a single inductor / switch converter assembly is used, or by the output of the inductor of the second stage DC / DC converter if such a second converter circuit is used; (g) the back channel can be or is sometimes turned on, at least periodically powered from the output of the first stage inductor; (h) the ADC is powered by the output of the first stage inductor and is on at least periodically; (i) the client device receives a majority of the energy generated by the PV and a majority of the energy generated at the output of the inductor, whether it is a single-stage inductor or a second-stage inductor; It is characterized by at least some of the following.

[0021] The low efficiency initial mode typically ends after a voltage above 1V occurs and after the primary controller completes a self-check routine.

[0022] Once the primary controller is operational, it performs a self-evaluation to ensure that the subsystems are operating without fault, turns on at least one ADC, and typically uses a multiplexer system (MUX) to measure the values ​​of various sensors, such as sensors that measure the current or voltage or power generated by the photovoltaic cell, sensors that measure the power of the light beam shining on the photovoltaic cell, and sensors that measure the temperature of various components such as the photovoltaic cell or the controller itself.

[0023] The ADC, and typically the sensor amplifier, is powered by the output of the first stage inductor during the highly efficient second stage.

[0024] The primary controller then uses the measured data, as well as parameters such as the desired output voltage, to calculate the switching speed and duty cycle that needs to be applied to the primary controller switches, and optionally, for those implementations that utilize only second stage conversion, disconnects the initial simple controller module and drives the converter switches itself, as described in the detailed description section below. In an alternative transition to the primary controller, the primary controller takes over first, and then immediately thereafter measures parameters to optimize operation.

[0025] Once stable operation is reached, the main controller is used to start subsystems such as the ADC circuit, MPPT circuit, and back-channel signal emitter using the power generated by the inductor of the first stage DC / DC converter.

[0026] At this stage, the controller uses the signal emitter and back-channel communication link to send data packets back to the transmitter, allowing the transmitter to transmit a desired and safe level of power to the receiver. The controller may also send data regarding the receiver temperature; if the receiver temperature exceeds a threshold, the transmitter is designed to withhold power from the receiver for a short period of time, wait for the temperature to drop, and then power up again.

[0027] Depending on the measured power, the controller uses an ADC (typically using a MUX) to send at least

number

[0028] The average power dissipation in the inductor and the average power dissipation in the switch are affected by the signal that drives the switch. Therefore, a signal optimized based on measurements from various sensors, such as the drive signal generated by the master controller, will result in higher conversion efficiency from the same inductor and switch than if they were driven by a simple controller. However, in some designs, it is advantageous to use two sets of one inductor and multiple switches, as described in the detailed description below.

[0029] During the second stage, the main controller optimizes the drive signal, the timing of the signal emitter, and the power mode of the ADC so that the power loss in the coil, plus the power loss in the switch, plus the power consumed by the signal emitter, plus the power loss used to operate the MTTP circuit, if used, is less than 50% of the power generated by the DC / DC converter circuit radiated by the inductor, which in turn is less than 50% of the power generated by the optical / electrical converter. This can be expressed by the following equation:

[0030] (Pmppt+Pcoil+Pswitch+Pse) / Pdcdc<0.5 where: Pmmpt is the power used to power the MPPT circuit, if included Pcoil is the average power loss in the inductor during operation, Pswitch is the average power dissipated in the switch during operation, Pse is the power used by the signal emitter, Pdcdc is the power generated by the DC / DC converter circuit.

[0031] As the power generated by the optical-to-electrical converter decreases, the primary controller is programmed to reduce power losses in at least some of the inductors, switches, ADC circuitry, the controller itself, and the signal emitter to improve the percentage of power delivered to other circuits, particularly the client circuits targeted for the receiving function. As previously mentioned, the receiver should deliver at least 50% of its output power to the client device if necessary. To achieve this goal, consideration must be given to situations in which the power available from wireless power transmission is less than optimal, or significantly less than optimal power transmission. In such situations, a lower level of power is allocated for auxiliary tasks necessary to enable delivery of output power from the receiver. This lower level of power may be an absolute value, rather than a percentage of the output power. This saving of output power not directly used can be achieved by at least some of the following: (i) Reducing the back-channel power or the number of data bits transmitted from the back-channel link to the transmitter. (ii) Reducing the duty cycle of the MPPT or ADC test. (iii) reducing the duty cycle of safety testing; (iv) Reducing the duty cycle at which the controller operates in a high power consumption mode. (v) Reducing the duty cycle at which auxiliary systems such as ADCs can operate. (vi) Saving power in the DC / DC conversion process by using a system optimized for low available power.

[0032] That is, in accordance with an exemplary implementation of the devices and systems described in this disclosure, a receiver is provided that converts an optical power beam into electrical power for use by an electronic system. (i) a power conversion element adapted to convert optical beam power at a first voltage into a current; (ii) a signal emitter adapted to transmit information regarding the operation of the receiver back to the system that transmitted the optical power beam; (iii) a voltage conversion circuit adapted to convert a current having a first voltage into a current having a second voltage higher than the first voltage; Including, the voltage conversion circuit includes at least one inductor and at least one switch, the at least one switch being continuously switched between an open position and a closed position by a signal from at least one of the first electronic switching module and the second electronic switching module; The electronic switching module a first electronic switching module adapted to switch at least one switch in a first mode at a rate and duty cycle provided by the signal generating circuit, the first electronic switching module being powered by a power output of the power conversion element; a second electronic switching module adapted to switch the at least one switch in a second mode at a variable speed and / or a variable duty cycle provided by the at least one controller according to at least a requirement of the receiver, the second electronic switching module being powered by a power output of the voltage conversion circuit; the second electronic switching module is adapted to begin operation only when the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold; It is characterized by where: (iv) the signal radiator may be powered by the output of the voltage conversion circuit; (v) the signal emitter may be adapted to begin operation only after the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold; (vi) The signal emitter may be adapted to commence operation only after receiving a signal from the at least one controller.

[0033] In such a receiver, the second electronic switching module may operate at a second voltage, thereby enabling the second electronic switching module to operate the voltage conversion circuit with a power conversion efficiency higher than the power conversion efficiency of the voltage conversion circuit operated by the first electronic switching module in the first mode.

[0034] In such a receiver, high conversion efficiency of the voltage conversion circuit operated by the second electronic switching module may be achieved at least because a second voltage at a higher level compared to the first voltage enables operation of multiple semiconductor switching devices in the second electronic operating switch module with a closing resistance lower than the closing resistance of the switching devices in the first electronic switching module.

[0035] In addition, a higher conversion efficiency of the voltage conversion circuit operated by the second electronic switching module than that achieved by using the signal generation circuit of the first electronic switching module may be achieved at least due to the efficient control of the required switching parameters by using the at least one controller to adapt the switching parameters to the requirements of the receiver.

[0036] In any of the above-described receivers, the at least one inductor may be common to both the first electronic switching module and the second electronic switching module, in which case the at least one controller should be adapted to prevent the first and second electronic switching modules from operating the at least one switch simultaneously.

[0037] Further, in any of the above-described receivers, the at least one controller may be adapted to output a disable signal that terminates operation of the signal generating circuit of the first electronic switching module when the second voltage exceeds a predetermined second threshold level.

[0038] In an alternative implementation of the receiver described above, the first electronic switching module and the second electronic switching module may operate with separate inductors. In such a case, the use of separate inductors requires that the second electronic switching module be enabled to provide an output current at a voltage independent of the second voltage output of the voltage converter. Furthermore, the use of separate inductors enables the at least one controller to supply the first electronic switching module with the second voltage, thereby achieving improved operating efficiency of the multiple semiconductor switching devices in the first electronic switching module.

[0039] According to a further implementation of any of the receivers described above, the signal emitter comprises: the received optical beam power; a portion of the optical beam power absorbed by the power conversion element; an output from a power conversion element; An output from a voltage conversion element; and the temperature of the power conversion element.

[0040] In such an implementation of such a receiver, the emitter is adapted to transmit a digital signal to the transmitter that generates the optical power beam, so that the level of the optical power beam transmitted to the receiver can be adjusted according to the information transmitted by the signal emitter.

[0041] Additionally, in any of the receivers described above, the emitters may be activated by the at least one controller only when the second electronic switching module begins operation.

[0042] In that case, the signal emitter must have at least

number

[0043] Additionally, in any of the above-described receivers, the at least one controller may include a maximum power point tracking (MPPT) circuit adapted to optimize power extraction from the photovoltaic cell and the voltage converter circuit.

[0044] According to further implementations of such receivers, the operation of auxiliary circuits and power dissipation in the receiver may be controlled so that at least 50% of the power generated by the optical-to-electrical converter is used by the electronic system during the period when the second electronic switching module begins operation. In such cases, the auxiliary circuits and power dissipation may be controlled as follows: a maximum power point tracking circuit; the average power loss in the coil during operation; the average power dissipated in the switch during operation; The power used by the signal emitter and may include at least one of:

[0045] According to any of the receivers described above, there is further provided a receiver according to any of the previous claims, adapted so that the optical power beam that the receiver converts into electricity may be a laser beam.

[0046] Additionally, in any such receiver, the power conversion element may be at least one photovoltaic cell.

[0047] Additionally, the power conversion element may be a single photovoltaic cell, and the receiver may operate efficiently with a transmit beam having a profile with at least one hot spot, or may operate with a non-uniformized beam.

[0048] According to another exemplary implementation of the method described in the present disclosure, a method is also provided for converting the power of an optical beam transmitted to a receiver into electrical power for use by an electronic system, the method comprising: (i) converting the optical beam power into a current at a first voltage using a power conversion element; (ii) converting the current at the first voltage to a current at a second voltage higher than the first voltage using at least one voltage conversion circuit, each voltage conversion circuit including an inductor and a switch, the switch being continuously switched between an open position and a closed position by signals from at least one of the first electronic switching module and the second electronic switching module; a first electronic switching module adapted to switch at least one switch in a first mode at a rate and duty cycle provided by the repetitive signal generating circuit, the first electronic switching module being powered by the power output of the power conversion element; a second electronic switching module adapted to switch at least one switch in a second mode at a variable speed and / or a variable duty cycle provided by the at least one controller according to at least a requirement of the receiver, the second electronic switching module being powered by a power output of the voltage conversion circuit; (iii) enabling a second electronic switching module to begin operation only when the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold; Includes.

[0049] The method further comprises: (iv) transmitting from the receiver signal emitter information regarding the operation of the receiver back to the transmission system from which the power of the optical beam was transmitted; (v) using the information to adjust the power of the light beam transmitted to the receiver; Including, The signal emitter is (a) Powered by the output of a voltage converter circuit; (b) adapted to begin operation only after the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold; (c) adapted to initiate operation only after receiving a signal from at least one controller.

[0050] Any of these methods may further include disabling operation of the first electronic switching module and disabling only the second electronic switching module to operate at least one switch of the single voltage conversion circuit. In such a case, disabling the first electronic switching module and enabling only the second electronic switching module to operate at least one switch of the voltage conversion circuit may be dictated by the use of only a single inductor in the single voltage conversion circuit.

[0051] Alternatively, in such a method, the at least one inductor and at least one switch may be two inductors and two switches, one inductor and one switch associated with each of the first electronic switching module and the second electronic switching module, and both electronic switching modules enabled to operate simultaneously, one in each of the separate voltage conversion circuits.

[0052] Finally, according to yet another example implementation of the device described in the present disclosure, there is further provided a receiver that provides power from the transmit beam to a device associated with the receiver, the receiver comprising: (i) a power conversion element adapted to convert the power of the beam into a current at a first voltage; (ii) a voltage conversion circuit adapted to convert a current having a first voltage into a current having a second voltage higher than the first voltage for application to a device associated with the receiver; (iii) a comparator circuit adapted to prevent application of current from the voltage converter to a device associated with the receiver when the second voltage exceeds a first threshold input to the comparator as a reference level; (iv) an electronically controlled switch having a bypass resistor, the electronically controlled switch adapted to maintain a minimum current to a device associated with the receiver when the second voltage falls below a second threshold voltage; and Includes. [Brief explanation of the drawings]

[0053] The present invention will be more fully understood and appreciated from the following detailed description taken in conjunction with the drawings.

[0054] [Figure 1] 1 is a schematic diagram of a typical receiver circuit according to a general exemplary implementation of the circuit of the present disclosure, with certain electronic components of the circuit shown; [Figure 2] FIG. 1 is a block diagram of a first exemplary implementation of a two-stage conversion and control system of the present disclosure. [Figure 3] FIG. 10 is a block diagram of a second exemplary implementation of the two-stage conversion and control system of the present disclosure. [Figure 4] FIG. 10 is a block diagram of a third exemplary implementation of the two-stage conversion and control system of the present disclosure. [Figure 5] 1 shows one circuit arrangement for efficient use of incident power, especially for storing power in peripheral devices when incident power is low. DETAILED DESCRIPTION OF THE INVENTION

[0055] Reference is now made to FIG. 1, which schematically illustrates a typical receiver circuit, including certain circuit components, according to one exemplary implementation of the circuitry of the present disclosure. Fuller details of the receiver are provided below. In the receiver circuit shown in FIG. 1, before receiving power and during the initial stages of power reception and conversion, the main controller is shut down because there is insufficient voltage to operate the main controller, as well as all peripheral devices and circuits. These include circuits such as outputs to the client device, any battery charging circuitry, a backchannel communication link with the optical power transmission system to the receiver, ADC circuits providing digital inputs from various sensors to the main controller, any measurement circuitry, an optically actuated backchannel LED, and any other auxiliary circuit functions. In fact, the only active circuit in the receiver is the photovoltaic cell PV. The photovoltaic cell PV does not provide an output current unless illuminated by an illuminating power beam, but responds to incident illumination by generating an output current whose voltage corresponds to the intensity of the illuminated power beam.

[0056] Referring now more closely to the receiver details, similar to prior art wireless power receivers that use a laser beam 1 as a source of wireless power, a photovoltaic cell 15 (hereafter PV) performs light-to-electrical conversion and outputs a current A1 at a voltage V1, typically well below 1 V, when the receiver first detects the incident power beam 1, which may be at a very low level. However, such a voltage level is insufficient to properly operate complex logic circuits based on digital electronics. Therefore, the PV output is input to a conventional DC / DC boost converter circuit 17, including an inductor 11 and a transistor switch 12. In this circuit, the switch timing is operated by a basic control module 13. The basic control module 13 may simply be a low-power signal generator without any other control inputs, or it may have a very limited set of simple control inputs and capabilities so that it can operate with minimal power consumption from the low output voltage of the PV 15. The switched inductor output current is rectified by a diode 14 to provide a current with a DC voltage V2 that is higher than the voltage output V1 from the PV cell. This simple DC / DC boost converter, which can operate at very low power levels, provides an output DC current A2 from inductor 11 and rectifier diode 14 at a voltage level V2, here typically above 1 V, since the DC / DC converter is configured as a boost converter, as shown in FIG.

[0057] The receiver of the present disclosure differs from such prior art receivers in that this output DC current A2 is now at a voltage V2 sufficient to wake up and power the receiver's primary controller 10. The primary controller 10 contains digital logic circuitry that processes inputs from measurement sensors and peripheral devices, provides control outputs to other peripheral devices or circuits of the receiver, and also provides output current to the receiver client circuitry 16. However, just as importantly, the primary controller 10 can be powered by a high V DDBy operating in this manner, the entire power conversion process from input optical power to the desired output power can now be made efficient. In effect, the primary controller 10 now takes over control of the simple DC / DC boost converter 17 that was initially powered from the basic controller 13. The primary controller 10, with its sufficient logic control capabilities, can now calculate the optimal duty cycle of the inductor 11 and the optimal switching frequency of the DC / DC boost converter 17 depending on the operational needs of the receiver. Such calculation power requires a stable voltage at a level higher than the PV-generated voltage V1, which is not available until the primary controller 10 begins operation. In this case, the primary controller can operate the DC / DC boost converter 17 in the optimal mode depending on the inputs and outputs of the peripheral and output devices at any moment and under any circumstances of receiver operation. If the basic controller were used to switch the DC / DC converter 17, this level of operational flexibility would not be readily available. That is, the logic function of the main controller 10 can check the currents flowing, the voltages of the various circuits, the loads applied by the output device or devices, and now controls the entire power conversion process.

[0058] A particular feature of the receiver electronic architecture described above is that the primary controller 10 is driven by the output V2 of the DC / DC converter 17 and is therefore inoperable to control the DC / DC converter until the converter itself is operating using the primary controller 13. Thus, although the primary controller 10 is driven by the output of the DC / DC converter 17, it also acts as the primary control input to the DC / DC converter 17 once the high power primary controller mode begins operation.

[0059] As shown in FIG. 1 , the primary controller provides outputs to or receives inputs from a number of other circuits and peripheral devices. Such peripheral devices include analog-to-digital conversion circuitry ADC 19 used to convert analog signals, such as V1, A1, V2, or A2, from measurement probes or sensors into digital signals for input to the primary controller 10. In addition, a backchannel communication link and its signal source (not shown in FIG. 1 but labeled Comm in FIGS. 2, 3, and 4 below) may be powered up so that the transmitter can receive commands to provide more power to the receiver when needed. Furthermore, depending on the available power and the power required by the client device 16, the primary controller can direct current to the client device or direct current to charge its battery or capacitor. Additionally, the primary controller can perform complex optimization procedures for output current generation, similar to those performed by MPPT circuits, as described further below. Such complex optimization procedures cannot be performed using the simple control modes present in the early stages of boost converter operation.

[0060] It should be emphasized that the specific auxiliary circuits shown in Figure 1 and described above and elsewhere herein are exemplary circuits and are not necessarily part of the inventive receiver architecture concepts of the present disclosure. There may be more or fewer such auxiliary circuits in a particular receiver configuration, and those shown in Figure 1 are used to illustrate a selection of the most common or important functions of a receiver.

[0061] The manner in which the receiver of the present disclosure starts up in the absence of an external power source for the receiver other than the incident low-power scanning laser power beam 1 can be explained as follows: Before the receiver first detects a substantial incident laser beam, the PV cells output a current A1 at a low wattage. This is not only due to the PV cells not operating at their most efficient load due to their low electricity-to-power conversion efficiency, but also because backchannel communication with the transmitter is inoperative at this stage and the transmitter is not receiving any voltage supply from the main controller. Therefore, the transmitter cannot operate in a high-power mode in the absence of instructions over the backchannel communication link. The emitted laser beam 1 is therefore merely a scanning beam seeking the receiver and is at a low power level. Similarly, other peripheral devices are also inoperative because the DC / DC converter is not being operated by the main controller and cannot provide the output voltage required for operation at this initial stage. In other words, the receiver draws very little current and is essentially in sleep mode.

[0062] Upon detecting the incident laser beam 1 and before being in a state that provides confirmation to the transmitter that the transmitted scanning beam has struck the actual receiver, because the back-channel communication link is still inactive, the primary controller receives a low voltage signal from the PV cell sufficient to activate the primary controller 13, which in turn enables the primary controller 13 to operate the DC / DC boost converter 17 in its initial mode, thereby providing sufficient output voltage so that the primary controller 10 can begin operation. Only when the DC / DC boost converter 17 provides enough output power to enable the primary controller to start up and drive the DC / DC conversion in an efficient manner will the peripheral devices 18a, 18b, 18c, ... be turned on by receiving operating voltage from the converter now operated by the primary controller 10, thereby enabling the primary controller to provide efficient control of the DC / DC converter, providing substantially more output power than the initial mode would provide.

[0063] To increase the output voltage from a PV cell, some optical power receivers achieve high voltages by connecting multiple cells in series. However, such series-connected PV cells have the disadvantage of being unable to tolerate local hot spots in the incident laser beam, and therefore, to operate efficiently, they generally require a beam that does not have regions of its typical beam profile where the intensity exceeds twice the average beam intensity. If the generated laser beam is likely to have such hot spots, the receiver must be equipped with a beam homogenizer to enable beam transmission to such a multi-cell PV. One additional advantage of the receiver of the present application is that a single photovoltaic cell, preferably having one to three junctions, can be used as the light-to-electricity conversion element, thereby eliminating the need for beam homogenization in the receiver and achieving volume, weight, and cost advantages. Because a single PV cell, as mentioned above, produces a low output voltage that is typically below the minimum voltage required to operate conventional digital electronics, the presently described receiver is particularly optimized for efficient conversion of received optical power by such an optical-to-electrical converter, making it particularly useful for use in receiving unhomogenized laser beams for conversion to electrical power.

[0064] Reference is now made to Figures 2, 3 and 4, which show schematically three different ways of implementing the receiver configuration described above. These schematic block diagrams also show details of the logic paths used for the sequential operation of two separate control functions of the DC / DC boost converter 17 of Figure 1.

[0065] A block diagram of a first implementation of a two-stage conversion and control system is shown in Figure 2. A feature of the arrangement of Figure 2 is that the inductor of the DC / DC boost converter is a shared component used by both the first stage control of the converter using the primary controller 13 and the final stage control mode using the main controller 10 of Figure 1.

[0066] The following circuit elements are shown in FIG.

[0067] LVS (Low Voltage Switcher). This is the basic controller 13 in Figure 1, whose purpose is to provide the duty cycle and frequency for switching the converter. It contains a switch, a low voltage oscillator, and basic control logic that can operate from the low drive voltage available during receiver start-up. The power to operate it is its V DD It is powered directly from the low PV voltage applied to the input. However, the efficiency of LVS is low because the PV does not output a high enough voltage to efficiently operate the semiconductor devices in an LVS.

[0068] The HES (High Efficiency Switcher) contains a low resistance switch that requires a high voltage drive. Such voltage is only available once the primary controller is operational. Once operational, the primary controller Contr provides a disable signal DIS to the first mode controller LVS, turning LVS off. As a result, only the primary controller now operates the high efficiency switch to switch the DC / DC boost converter. At this stage, the shared inductor L, previously used in the early stage converter operation, is still used in the converter circuit. The primary controller Contr can now be operated to give optimum efficiency for the conversion process.

[0069] PMS (Power Measurement System): Contains PV current and voltage measurement circuitry and ADC circuitry that provides digital information about the measured current and voltage levels.

[0070] Comm (Communication link) refers to the back-channel communication link between the receiver and the transmitter. It is intended to provide safe operation of the transmitter. The receiving end of the back-channel communication link includes a signal emitter for transmitting received data to the transmitter.

[0071] Contr.: The main controller that contains the control logic including the CPU that manages the entire system.

[0072] In the implementation example of Figure 2, both switches LVS and HES share a common inductor L. This means that only one of the multiple switching controls can be active at any given time. The LVS is powered up first and generates the high voltage that operates the other modules of the system. The main controller Contr then disables the LVS through its DIS input and enables the HES through its CTR input, thereby achieving a highly efficient and wide-range power conversion process. Sharing the inductor L reduces the size and cost of the system, as inductors are relatively bulky components.

[0073] Reference is now made to Figure 3, which is a block diagram of a second implementation of a two-stage conversion and control system. A feature of the arrangement of Figure 3, unlike the implementation of Figure 2, is that two separate DC / DC converters are used, both of which can operate simultaneously and together. Each converter in this case has its own set of an inductor and switches that operate the pulse-mode conversion.

[0074] In FIG. 3 the following circuit elements are shown:

[0075] WUC. Wake-up converter. The WUC operates directly from the PV low voltage output at the IN_LV input, providing initial DC / DC boost conversion when the incident laser power on the PV is still low. The WUC is a completely self-contained DC / DC converter, but its efficiency is not high due to its low operating voltage.

[0076] The MC is the main converter. It also has its own set of inductors and switches that operate the pulse-mode DC / DC conversion, but it also has a high voltage V DD It has high conversion efficiency because it is operated using input power.

[0077] The wake-up sequence of the system in Figure 3 is the same as that in Figure 2. However, in the operating mode of Figure 3, the disable signal DIS is not supplied to the WUC converter, so it continues to operate together with the primary converter MC. OUT is separate from the logic voltage used for the output from the main controller Contr. This makes the system more versatile, but at the cost of an additional inductor. One drawback is that the low-efficiency first mode converter WUC is always operating from the low input voltage source PV, reducing the overall system efficiency.

[0078] Now, please refer to Figure 4. Figure 4 is a block diagram of a third implementation of a two-stage conversion and control system. The feature of the arrangement of Figure 4 is that, unlike the implementation of Figure 3, once the main converter starts operation, the WUC is switched to a higher voltage source, so that the power efficiency of the WUC can approach that of the main converter MC. This is because in Figure 4, the V OUT It can be seen that the power line from the PV inverter is applied back to the IN_HV voltage supply input of the WUC. As can be seen, the WUC can therefore operate from the low PV voltage output IN_LV in start-up mode, or from the high voltage supply IN_HV once the main controller Contr is also operating. Therefore, this implementation has the highest power conversion efficiency of the three exemplary implementations shown.

[0079] One of the primary objectives of the presently described receiver is to provide optimal transfer of incident beam power for use in an electronic product, device, or power storage element associated with the receiver (such loads are often referred to as client power destinations). This objective is particularly important when the received power is low.

[0080] Reference is now made to Figure 5, which shows an exemplary circuit arrangement aimed at efficient use of incident power to charge peripheral devices, especially when the incident power is low.

[0081] V represents the voltage output V by any of the systems of Figure 2, Figure 3, or Figure 4. When the voltage falls below a first threshold set by R1, R2, and their associated switch S2, power to the peripheral devices connected at V is turned off by the setup of switch S2, which turns off when the voltage falls below the set threshold, and bypass resistor R bp However, the "keep alive" current is always limited by R bp Vload continues to be supplied through V. Vload can be a battery, a battery charger, a capacitor, a supercapacitor, or any user device. This keep-alive current is particularly useful for maintaining power to memory chips, for example.

[0082] The voltage from the output VOUT of the main converter of Figure 4 is input to the circuit of Figure 5, which generates a voltage proportional to VOUT across R3 and R4. This voltage is compared to the voltage Vref applied to the comparator.

[0083] When the voltage across R3 and R4 exceeds a second defined threshold, VREF, switch S1 turns OFF and the output power from the primary converter is disconnected from the peripheral devices connected to Vload, thereby avoiding damage to the peripheral devices due to applied overvoltage. The system output voltage at which the load is disconnected from the system is selectable by selecting Vref.

[0084] In summary, this arrangement ensures that a "keep alive" current is supplied to Vload when the voltage output at VSYS falls below a first threshold. When the voltage at VSYS rises above a second threshold, the peripheral device connected to Vload is disconnected from the power supply to avoid damaging the load.

[0085] The exemplary embodiments are provided to explain the present disclosure in detail and to fully convey its scope to those skilled in the art. Numerous specific details, such as examples of specific components, devices, and methods, are described to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, and the exemplary embodiments may be embodied in many different forms, none of which should be construed as limiting the scope of the present disclosure. Furthermore, it will be understood by those skilled in the art that the present invention is not limited by what has been particularly shown and described above. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described above, together with variations and modifications that do not exist in the prior art and that would occur to those skilled in the art upon reading the above description.

Claims

1. 1. A receiver that converts an optical power beam into electrical power for use by an electronic system, comprising: a power conversion element adapted to convert the optical beam power at a first voltage into a current; a signal emitter adapted to transmit information regarding the operation of said receiver back to the system that transmitted said optical power beam; a voltage conversion circuit adapted to convert a current having the first voltage into a current having a second voltage higher than the first voltage; Including, the voltage conversion circuit includes at least one inductor and at least one switch; the at least one switch is sequentially switched between an open position and a closed position by a signal from at least one of a first electronic switching module and a second electronic switching module; The electronic switching module the first electronic switching module is adapted to switch the at least one switch in a first mode at a rate and duty cycle provided by a signal generating circuit, the first electronic switching module being powered by a power output of the power conversion element; the second electronic switching module is adapted to switch the at least one switch in a second mode at a variable speed and / or a variable duty cycle provided by at least one controller according to at least the requirements of the receiver, the second electronic switching module being powered by a power output of the voltage conversion circuit; the second electronic switching module is adapted to begin operation only when the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold; It is characterized by The signal emitter (i) powered by the output of the voltage conversion circuit; (ii) adapted to begin operation only after the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold; (iii) a receiver adapted to initiate operation only after receiving a signal from said at least one controller;

2. 2. The receiver of claim 1, wherein the second electronic switching module operating at the second voltage enables the second electronic switching module to operate the voltage conversion circuit with a power conversion efficiency higher than the power conversion efficiency of the voltage conversion circuit operated by the first electronic switching module in the first mode.

3. 3. The receiver of claim 2, wherein the high conversion efficiency of the voltage conversion circuit operated by the second electronic switching module is achieved at least because the second voltage, which is at a higher level compared to the first voltage, enables operation of a plurality of semiconductor switching devices in the second electronic operating switch module with a lower closing resistance than the closing resistance of the switching devices in the first electronic switching module.

4. 3. The receiver of claim 2, wherein the higher conversion efficiency of the voltage conversion circuit operated by the second electronic switching module than that achieved by use of the signal generation circuit of the first electronic switching module is achieved at least due to efficient control of the required switching parameters by using the at least one controller to adapt the switching parameters to the requirements of the receiver.

5. 5. The receiver of claim 1, wherein the at least one inductor is common to both the first electronic switching module and the second electronic switching module.

6. 6. The receiver of claim 5, wherein the at least one controller is adapted to prevent the first and second electronic switching modules from operating the at least one switch simultaneously.

7. 7. The receiver of claim 1, wherein the at least one controller is adapted to output a disable signal that terminates operation of the signal generating circuit of the first electronic switching module when the second voltage exceeds a predetermined second threshold level.

8. 5. The receiver of claim 1, wherein the first electronic switching module and the second electronic switching module operate with separate inductors.

9. 9. The receiver of claim 8, wherein the use of the separate inductor enables the second electronic switching module to provide an output current at a voltage that is independent from the second voltage output of the voltage converter.

10. 9. The receiver of claim 8, wherein the use of the separate inductor enables the at least one controller to provide the second voltage to the first electronic switching module, and improved operating efficiency of multiple semiconductor switching devices within the first electronic switching module is achieved.

11. The signal emitter comprises: the received optical beam power; a portion of the optical beam power absorbed by the power conversion element; an output from the power conversion element; an output from the voltage conversion element; the temperature of the power conversion element; 11. A receiver according to claim 1, adapted to transmit a signal containing information based on data from at least one sensor measuring at least one of:

12. 12. The receiver of claim 11, wherein the emitter is adapted to transmit the digital signal to a transmitter that generates the optical power beam, such that a level of the optical power beam transmitted to the receiver can be adjusted in response to information transmitted by the signal emitter.

13. 2. The receiver of claim 1, wherein the emitter is activated by the at least one controller only when the second electronic switching module begins operation.

14. The signal radiator has at least [Equation 1] 14. The receiver of claim 13, emitting the digital signal every second.

15. 15. The receiver of claim 1, wherein the at least one controller includes a maximum power point tracking (MPPT) circuit adapted to optimize power extraction from the photovoltaic cell and the voltage converter circuit.

16. 16. A receiver as described in any one of claims 1 to 15, wherein the operation and power loss of auxiliary circuits in the receiver are controlled so that at least 50% of the power generated by the optical / electrical converter is used by the electronic system during the period when the second electronic switching module starts operating.

17. The auxiliary circuits and power losses are a maximum power point tracking circuit; the average power loss in the coil during operation; the average power dissipation in the switch during operation; the power used by the signal emitter; 17. The receiver of claim 16, comprising at least one of:

18. 18. A receiver according to any one of claims 1 to 17, adapted so that the optical power beam that the receiver converts into electricity may be a laser beam.

19. 19. The receiver of any one of claims 1 to 18, wherein the power conversion element is at least one photovoltaic cell.

20. 20. A receiver as described in any one of claims 1 to 19, wherein the power conversion element is a single photovoltaic cell, and the receiver can operate efficiently with a transmit beam having a profile with at least one hot spot or can operate with a non-uniformized beam.

21. 1. A method for converting the power of an optical beam transmitted to a receiver into electrical power for use by an electronic system, comprising: converting the optical beam power into a current at a first voltage using a power conversion element; converting the current at a first voltage to a current at a second voltage higher than the first voltage using at least one voltage conversion circuit, each including an inductor and a switch, the switches being continuously switched between open and closed positions by signals from at least one of a first electronic switching module and a second electronic switching module; the first electronic switching module is adapted to switch the at least one switch in a first mode at a rate and duty cycle provided by a repetitive signal generating circuit, the first electronic switching module being powered by a power output of the power conversion element; the second electronic switching module is adapted to switch the at least one switch in a second mode at a variable speed and / or a variable duty cycle provided by at least one controller according to at least the requirements of the receiver, the second electronic switching module being powered by the power output of the voltage conversion circuit; enabling the second electronic switching module to begin operation only when the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold; A method comprising:

22. transmitting, from a signal emitter of the receiver, information regarding the operation of the receiver back to the transmission system from which the power of the optical beam was transmitted; using the information to adjust the power of the light beam transmitted to the receiver; further comprising The signal emitter comprises: (i) powered by the output of the voltage conversion circuit; (ii) adapted to begin operation only after the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold; 22. The method of claim 21, wherein (iii) the method is adapted to initiate operation only after receiving a signal from the at least one controller.

23. 23. The method of claim 21, further comprising disabling operation of the first electronic switching module and enabling only the second electronic switching module to operate at least one switch of a single voltage conversion circuit.

24. 24. The method of claim 23, wherein disabling the first electronic switching module and enabling only the second electronic switching module to operate the at least one switch of the voltage conversion circuit is dictated by the use of only a single inductor in a single voltage conversion circuit.

25. 23. The method of claim 21, wherein the at least one inductor and the at least one switch include two inductors and two switches, one inductor and one switch associated with each of the first electronic switching module and the second electronic switching module, both enabled to operate simultaneously, one in each of the separate voltage conversion circuits.

26. a receiver for providing power to a device from the transmitted beam, said device being associated with said receiver; The receiver includes: a power conversion element adapted to convert the power of the beam into a current at a first voltage; a voltage conversion circuit adapted to convert a current having the first voltage into a current having a second voltage higher than the first voltage for application to a device associated with the receiver; a comparator circuit adapted to prevent current from being applied to a device associated with the receiver when the second voltage exceeds a first threshold input to the comparator as a reference level; and an electronically controlled switch having a bypass resistor, the electronically controlled switch adapted to maintain a minimum current to a device associated with the receiver when the second voltage falls below a second threshold voltage; a receiver including:

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