High efficiency wireless power receiver

Abstract

A dual mode DC / DC converter system for use in a wireless power transfer receiver and allows for efficient driving of DC / DC converter circuits using conventional logic circuits operating at voltages above 1 V, even when powered at low voltages (even below 1 V) output from photovoltaic cells. Two separate control modules may control the DC / DC converter, the first control module switching the converter using simple control, capable of being powered by a low voltage generated by the PV. Once a voltage above about 1.5 V is generated at the output of the DC / DC converter, a second, more complex controller may become powered up and control the voltage conversion process, more efficiently driving the converter, and can adapt its control functionality according to the received logic input instructions and sensor outputs. The complex controller may operate independently or in combination with the simple controller to further improve efficiency.

Description

Technical Field

[0001] The present disclosure describes techniques related to the field of receiver design in systems for wireless power transfer, and in particular techniques for optimizing the efficiency and operation of such receivers at all stages of their operation. Background Art

[0002] Wireless power delivery 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 received power, and a device for using or storing the received power. Such systems are described in patent publications and patents WO2007 / 036937 for “Directional optical transmitter and receiver”, WO2009 / 083990 for “Wireless laser power transmitter”, WO2012 / 172541 for “Spatially distributed laser resonator”, WO2017 / 009854 for “System for optical wireless power supply”, WO2017 / 033192 for “Wireless power distribution system”, WO2017 / 158605 for “System for optical wireless power supply”, WO2017 / 179051 for “System for optical wireless power supply”, WO / 2019 / 135226 for “Multi-beam wireless power transfer system” and US11,444,491 for “Wireless power transfer system”, all of which are jointly owned by the present applicant. These systems consist of a transmitter that generates a power beam (usually a laser beam) and a receiver that converts the beam into usable electrical power for use by a client device or storage for such use, or another electronic circuit that is not part of the receiver.

[0003] The transmitter typically includes a beam generator, a beam deflection system for aiming the beam at the receiver, and in most cases, a safety system should also be included. The safety system typically relies on feedback from the receiver indicating that the power beam has been received and to help center the beam on the receiver power absorbing element, and to communicate identification data on the receiver back to the transmitter so that any safety diversions from the planned transmission can be detected and corrected. Such a communication channel is often referred to as a "backchannel" or "feedback channel" or similar terms, and uses a signal transmitter on the receiver to send feedback information, and a signal detector on the transmitter to receive feedback information from the receiver.

[0004] The primary function of the receiver is to generate power for use by other systems or components, or for energy storage 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 fitted with replaceable batteries. The receiver is typically built into the product or device it is designed to power, and parts of the receiver components may be on the same subsystem as components of its client device or product, or they may be distributed around the client product or device. The term "client" is used here to describe the product or device that is the end user of the wirelessly transmitted power. According to these descriptions, the receiver is therefore distinguished from any other part of the product it may be integrated into or intended to operate with, because the receiver is the part of such an integrated product that receives the transmission from the power transmitter and handles and processes the received power until the power is stored in a storage device (such as a battery or capacitor) or is fed to the product in which the receiver is built or associated with it for use. All other parts of such a product fall into the category of "client", especially those related to the end use power.

[0005] The disclosures of each of the publications mentioned in this section and elsewhere in this specification are incorporated herein by reference in their entirety. Summary of the invention

[0006] The present disclosure attempts to provide novel systems and methods that overcome at least some of the shortcomings of prior art systems and methods. The present disclosure describes new exemplary receiver configurations for wireless power transfer systems that have higher efficiency than currently used receivers, such that the overall power transfer efficiency is increased. While these new receiver configurations are advantageous for any receiver whose function is to transfer 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, in the case of an optical power beam, are powered solely by a laser beam that illuminates an optical-to-electrical power converter, which is typically a photovoltaic cell. In addition, these new configurations are also useful in situations where 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.

[0007] Although the most common form of local wireless power transmission is optical transmission using a laser beam, and 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 using antennas for the reception process, including radio frequency electromagnetic wave transmission.

[0008] Generally speaking, a receiver consists of several electronic subsystems or components that perform the following functions:

[0009] (a) An energy converter for converting an electromagnetic beam into electrical energy, which is achieved in the case of optical power transmission using photovoltaic (PV) cells or arrays. The optical case with PV will be used as an exemplary embodiment in this disclosure, but it should be understood that the receivers described herein are not limited to optical receivers.

[0010] (b) Maximum power point tracking (MPPT) circuits or similar circuits to optimize power extraction from a photovoltaic energy converter. While such optimization typically considers the maximum power point, it may also consider other factors such as safety, voltage limitations of the PV, temperature limitations of the PV, desired output voltage, and battery availability, and in particular the overall safety and efficiency of the system, to set the reference load applied to the PV for optimal operating conditions. In the case of MPPT, such circuits are needed because the power transfer efficiency of the 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 fed by the input power. As these conditions change, the load characteristics and load impedance that provide the highest power transfer also change. As the load characteristics change, the system is optimized to maintain the highest power transfer efficiency. MPPT is the process of adjusting load characteristics as power and load conditions change. A well-designed MPPT circuit provides the optimal load for the PV cell and then converts the voltage, current, or frequency to accommodate other devices or systems. However, the optimization circuit may alternatively be designed to optimize for maximum system efficiency rather than maximum PV efficiency, taking into account DC / DC conversion, PV temperature or fluorescence yield, and other factors.

[0011] (c) One or more sensors to measure the power produced by the receiver, the incident beam characteristics, any safety-related parameters, and in some cases other parameters.

[0012] (d) A DC / DC converter circuit for converting the voltage of the power generated by the photovoltaic cell to a voltage level more useful for efficient operation of conventional electronic circuits. IR-optimized photovoltaic cells typically output current at a low voltage (usually less than 1V), which is much lower than the voltage required for operation of electronic semiconductor devices, especially digital electronic components in logic circuits. MPPT optimization generally requires the generation of a voltage that varies depending on operating conditions, but this voltage may not be suitable for many electronic circuits. For example, if the MPPT circuit converts 1W of electrical power to 5V, then 1W will be generated at 5V (ignoring losses due to the conversion process). However, if the client device (including any energy storage devices and load components) only requires 0.5W at 5V, it is very important to continue to power it at 5V to avoid damaging the components of the client device. Therefore, operation at the maximum power point becomes impossible, and the DC / DC conversion should be performed independently of the MPPT. A DC / DC converter is a step-up converter that is adapted to output current at a voltage that enables the electronic circuit to operate at high efficiency, usually 5V, but also often 1.7V, 3.7V, 7.6V, 12V or other voltages commonly specified for certain electronic circuits.

[0013] One of the problems that wireless power receivers have to deal with is that the amount of power they receive from the transmitted wireless power is limited, variable and unpredictable because it depends on the beam received from the transmitter. In particular, in order to save power in onboard storage, the receiver is often in sleep mode or even turned off, so that a minimum input energy is required to wake up and start receiving the transmitted power. Such a wake-up process using a first minimum amount of energy is described in the international patent publication WO2017 / 033192 for "Wireless Power Distribution System" co-owned by the present applicant. In addition, when the transmitter is searching for a receiver to which to transmit wireless power, until the transmitted beam is locked onto the receiver it found during the scanning process, the power level transmitted to the receiver is very low, and therefore the output voltage of the PV cell is also low. Therefore, there is a problem that the receiver may initially operate at a very low efficiency and therefore cannot quickly reach the output power level according to the power sent to it by the transmitter.

[0014] Photovoltaic power converters typically produce voltages of less than 1V. Most currently available digital electronic components, especially logic circuits, require higher 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 usually powered by the output of a DC / DC converter rather than directly from the PV cell. In the absence of DC / DC conversion, it remains very difficult to design an efficient circuit for a controller powered by the voltage generated by a photovoltaic cell.

[0015] Simple converters have low efficiency and limited control over the output voltage. On the other hand, more complex logic-based DC / DC converters have higher current conversion efficiency and are therefore more suitable for use in wireless power systems. More complex logic-based DC / DC converters require voltages much higher than 1V to operate, and PV cells are generally unable to provide such voltage levels. This is especially true during the search and start-up process, especially when used in systems that do not have an additional voltage source (such as an on-board battery) and therefore rely solely on the power received from the wireless power transfer system.

[0016] The present disclosure describes a novel DC / DC converter system for a wireless power transfer receiver that allows the use of conventional logic circuits operating at voltages well above 1V to efficiently drive DC / DC converter circuits and MPPT or similar optimization circuits, even when powered only by a low voltage PV output.

[0017] Current systems achieve this by using two separate control modules to control the DC / DC conversion functions. The first initial voltage conversion is performed by using a simple basic control module (analog or digital) to control the operation of the switching process of the converter. Because this simple control module (which can be basically like a predetermined fixed frequency source or signal generator), whether outputting pulse-type or sinusoidal signal forms, or a function generator, can be implemented without including electronic logic functions, it has the advantage that it can be powered by voltages significantly lower than 1.5V or even lower than 1V, which are the voltage levels produced by PV. However, this simple switching control of the converter results in conversion efficiency below optimal levels, and there are no logic-based adaptive features to enable it to adapt to changing conditions, such as power changes or environmental changes. Throughout this disclosure, this simple control system is referred to as a simple or basic control module or feature to distinguish it from more complex control systems that include logic circuit functions.

[0018] Once a voltage above about 1.5V is generated at the output of the DC / DC converter, a second master controller can now be powered from this higher voltage and control the voltage conversion process. Since this master controller is now powered by a suitably higher voltage, it will drive the converter in a more efficient manner and also has the ability to adjust its control functions based on the logic input instructions it receives. Since this master controller operating from a higher voltage can be more complex than a simple first-stage controller, it can contain logic function circuits and can receive sensor inputs and generate calculated output instructions based on these inputs. Therefore, it can be designed to accommodate a variety of different parameters, such as current requirements and availability, required output voltage, client device requirements, ambient or operating temperature, and other variable parameters, while still providing the required output to the client device at a stable level.

[0019] Therefore, the first, less efficient, simple controller mode is a temporary mode in which operation is enabled directly from the PV even when the PV output is low voltage, such as from a low power scan mode of the transmitter. During the low efficiency controller operation, many receiver subsystems are either off, in a power save mode, a sleep mode, or at least a wake-up mode during which they are turned on. These systems include the backchannel transmission system, the ADC, and the host controller. In many cases, even the client device may be disconnected from the output of the DC / DC converter during this first phase.

[0020] The second high-efficiency controller mode is the mode in which the converter operates after it is fully powered up and providing power to the client device. In this mode, most of the power generated is provided to the client, while only a small portion of the power is used to operate the power receiver itself, as well as all of its attached sub-circuits, such as the aforementioned backchannel link, the power conversion function itself, the MPPT circuit, and other functions, which will be more fully described in the detailed description section below.

[0021] Therefore, the receiver of the present disclosure achieves its higher efficiency by implementing two operating modes of the voltage converter function, namely a low efficiency mode followed by a high efficiency mode. Each of these modes has its own characteristics and different functions.

[0022] The low efficiency mode is characterized by at least some of the following:

[0023] (a) The DC / DC converter switch is operated by a PV-powered circuit;

[0024] (b) The reverse channel communication system is not working;

[0025] (c) the main controller is shut down or hibernated when the low efficiency mode begins and is turned on only when the mode is completed or nearly completed;

[0026] (d) the system analog-to-digital circuit (ADC) is turned off at the beginning of the mode and turned on only when the mode is completed or nearly completed; and

[0027] (e) In some cases, the client device may be disconnected from the output of the DC / DC converter.

[0028] The high efficiency mode is characterized by at least some of the following:

[0029] (f) the primary controller is turned on and is powered by the output of the inductor of the DC / DC converter when only a single inductor / switch converter assembly is used, or by the output of the inductor of the second stage DC / DC converter when such a second converter circuit is used;

[0030] (g) the reverse channel may be powered at least periodically by the output of the first stage inductor, or may be turned on from time to time;

[0031] (h) the ADC is powered by the output of the first stage inductor and is at least periodically turned on; and

[0032] (i) Whether it is a single-stage inductor or a second-stage inductor, the client device receives most of the energy generated by the PV and most of the energy generated at the output of the inductor, where both stages have their own switching circuits.

[0033] The low efficiency initial mode typically ends after a voltage greater than 1V is generated and the main controller completes its self-test routine.

[0034] Once the main controller is operational, it performs a self-assessment, which ensures that the subsystems are functioning without fault, turns on at least one ADC, and usually uses a multiplexer system (MUX) to measure the values ​​of various sensors, such as sensors for measuring the current or voltage or power produced by the PV cell, or sensors for measuring the power of the light beam shining on the PV cell; or sensors for measuring the temperature of various components, such as the PV cell or the controller itself.

[0035] The ADC, and often the amplifier used for the sensor, is usually powered by the output of the inductor of the first stage during the high efficiency second stage.

[0036] The master controller then uses the measured data, along with parameters such as the desired output voltage, to calculate the switching rate and duty cycle that needs to be applied to the master controller switches, optionally disconnecting the initial simple controller module for those implementations that utilize only the second stage conversion, as will be explained in the detailed description section below, and driving the converter switches themselves. In an alternative transition to the master controller, it can first take over the functionality and only then measure parameters and optimize operation.

[0037] Once stable operation is achieved, a main controller is used, which uses the power generated by the inductor of the first-stage DC / DC converter to operate subsystems such as the ADC circuit, the MPPT circuit, and the signal transmitter of the reverse channel.

[0038] At this stage, the controller can use the signal transmitter and the backchannel communication link to send data packets back to the transmitter so that the transmitter can send the required safe power level to the receiver. The controller can also send data about the temperature of the receiver. When the receiver temperature exceeds a threshold, the transmitter is designed to stop powering the receiver for a short period of time to allow the temperature to decrease and then power it on again.

[0039] Based on the measured electrical power (usually using a MUX and using an ADC), the controller can make the signal transmitter at least once per A data packet is sent every 10 seconds, where P is the electrical power produced by the power conversion element in Watts. This is very important for stable reporting of the "keep alive" signal to the transmitter.

[0040] The average power loss in the inductor and the average power consumption in the switch are affected by the signal driving the switch. Therefore, an optimized signal based on the measurements of various sensors, such as the drive signal generated by the main controller, will produce higher conversion efficiency from the same inductor and the same switch than when driven by a simple controller. However, in some designs, it is more advantageous to use two inductor and switch sets, as described in the detailed description below.

[0041] During the second phase, the master controller optimizes the drive signal, the timing of the signal transmitter and the power mode of the ADC so that the power loss on the coil plus the power loss on the switch plus the power consumed by the signal transmitter plus the power loss for actuating the MTTP circuit (if used) should be less than 50% of the power generated by the DC / DC converter circuit, as sent by the inductor, and therefore of course less than 50% of the power generated by the optoelectronic converter. This can be represented by the following expression:

[0042] (Pmppt+Pcoil+Pswitch+Pse) / Pdcdc<0.5

[0043] in

[0044] Pmmpt is the power used to power the MPPT circuit, if included;

[0045] Pcoil is the average power loss across the inductor during operation;

[0046] Pswitch is the average power loss in the switch during operation;

[0047] Pse is the power used by the signal transmitter; and

[0048] Pdcdc is the power produced by the DC / DC converter circuit.

[0049] When the power generated by the photovoltaic photoelectric converter decreases, the main controller is programmed to reduce the power loss of at least some of the inductors, switches, ADC circuits, the controller itself, and the signal transmitter to increase the percentage of power delivered to other circuits, especially the client circuit, which is the target of the receiver function. As mentioned earlier, the receiver should provide at least 50% of the output to supply the client device if necessary. In achieving this goal, it is necessary to consider the situation where the available power for wireless power transmission is lower than the optimal power, or even much lower than the optimal power transmission. In this case, a lower level of power is budgeted for the auxiliary tasks required to achieve the receiver output power supply. This lower power level may be an absolute value rather than a percentage of the power output. This saving of output power that is not directly used can be achieved by at least some of the following:

[0050] (i) Reduce the reverse channel power, or even reduce the number of data bits sent by the reverse channel link to the transmitter.

[0051] (ii) Reduce the duty cycle of the MPPT or ADC test.

[0052] (iii) Reduce the duty cycle of safety testing.

[0053] (iv) Reduce the duty cycle of the controller operating in higher power consumption mode.

[0054] (v) Reduce the operating duty cycle of auxiliary systems such as ADC.

[0055] (vi) Save power during DC / DC conversion by using an optimized system tailored for lower available power.

[0056] Therefore, according to an exemplary implementation of the devices and systems described in the present disclosure, there is provided a receiver for converting an optical power beam into electrical power for use by an electronic system, the receiver comprising:

[0057] (i) a power conversion element adapted to convert the beam power into a current at a first voltage,

[0058] (ii) a signal transmitter adapted to transmit information about the operation of the receiver back to the system transmitting the optical power beam, and

[0059] (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, the voltage conversion circuit comprising at least one inductor and at least one switch, the at least one circuit being continuously switched between an open position and a closed position by a signal from at least one of the first electronic switch module and the second electronic switch module,

[0060] The electronic switch module is characterized in that:

[0061] The first electronic switch module is adapted to switch the at least one switch in a first mode at a rate and a duty cycle provided by the signal generating circuit, the first electronic switch module being powered by the electrical power output by the power conversion element,

[0062] the second electronic switch module being adapted to switch the at least one switch in a second mode of either or both of a variable rate and a variable duty cycle provided by at least one controller, at least according to a requirement of the receiver, the second electronic switch module being powered by the electrical power output by the voltage conversion circuit, and

[0063] The second electronic switch module is adapted to start operating only when the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold,

[0064] And among them:

[0065] (iv) The signal transmitter can be powered by the output of the voltage conversion circuit,

[0066] (v) the signal transmitter may be adapted to start operating only after the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold, and

[0067] (vi) The signal transmitter may be adapted to commence operation only upon receipt of a signal from at least one controller.

[0068] In such a receiver, operation of the second electronic switching module at the second voltage may enable the second electronic switching module to actuate the voltage conversion circuit with a power conversion efficiency higher than that of the voltage conversion circuit operated by the first electronic switching module in the first mode.

[0069] In such a receiver, a higher conversion efficiency of the voltage conversion circuit actuated by the second electronic switch module can be achieved, at least because the higher level of the second voltage compared to the first voltage enables the semiconductor switching device within the second electronically operated switch module to operate with a lower closing resistance than the closing resistance of the switching device in the first electronic switch module.

[0070] Furthermore, at least due to adapting the switching parameters to the receiver requirements by using at least one controller to more effectively control the desired switching parameters, a higher conversion efficiency of the voltage conversion circuit actuated by the second electronic switch module can be achieved than that achieved by using the signal generating circuit in the first electronic switch module.

[0071] In any of the above receivers, at least one inductor may be common to both the first electronic switch module and the second electronic switch module. In this case, at least one controller should be adapted to prevent the first electronic switch module and the second electronic switch module from operating at least one switch simultaneously.

[0072] Furthermore, in any of the receivers described above, when the second voltage exceeds a predetermined second threshold level, the at least one controller may be adapted to output a disable signal to terminate operation of the signal generating circuit of the first electronic switch module.

[0073] In an alternative embodiment of the above receiver, the first electronic switch module and the second electronic switch module can be operated with separate inductors. In this case, the use of separate inductors should enable the second electronic switch module to provide an output current at a voltage that is independent of the second voltage output of the voltage converter. In addition, the use of separate inductors enables at least one controller to provide the second voltage to the first electronic switch module, so that an increase in the operating efficiency of the semiconductor switch device within the first electronic switch assembly is achieved.

[0074] According to yet another implementation of any of the above receivers, the signal transmitter is adapted to send a signal comprising information based on data from a sensor measuring at least one of:

[0075] The received beam power,

[0076] the portion of the beam power absorbed by the power conversion element,

[0077] The output from the power conversion element,

[0078] the output from the voltage conversion element, and

[0079] The temperature of the power conversion element.

[0080] In such an implementation of such a receiver, the transmitter may be adapted to send a digital signal to the transmitter generating the optical power beam, such that the level of the optical power beam sent to the receiver may be adjusted according to the information sent by the signal transmitter.

[0081] Furthermore, in any of the above receivers, the transmitter may be activated by the at least one controller only when the second electronic switch module starts to operate.

[0082] In this case, the signal transmitter can be A digital signal is sent at least once per second, where P is the electrical power generated by the power conversion element.

[0083] Furthermore, in any of the above receivers, 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.

[0084] According to another implementation of the receiver, during the period when the second electronic switch module starts to work, the power loss in the receiver and the operation of the auxiliary circuit can be controlled so that at least 50% of the power generated by the photoelectric converter is provided to the electronic system for use. In this case, the auxiliary circuit and the power loss may include at least one of the following:

[0085] Maximum power point tracking circuit,

[0086] The average power loss in the coil during operation,

[0087] The average power loss in the switch during operation, and

[0088] The power used by the signal transmitter.

[0089] According to any of the above receivers, there is also provided a receiver according to any of the preceding claims, adapted so that the optical power beam converted into electrical energy by the receiver may be a laser beam.

[0090] Furthermore, in any such receiver, the power conversion element may be at least one photovoltaic cell.

[0091] Furthermore, the power conversion element may be a single photovoltaic cell, enabling the receiver to efficiently operate using a transmit beam having at least one hot spot profile, or to operate using a non-uniform beam.

[0092] According to another exemplary implementation of the method described in the present disclosure, there is also provided a method for converting a light beam sent to a receiver into power for use by an electronic system, comprising:

[0093] (i) converting the beam power into a current at a first voltage by using a power conversion element,

[0094] (ii) converting a current of a first voltage into a current of a second voltage higher than the first voltage by using at least one voltage conversion circuit, each voltage conversion circuit comprising an inductor and a switch, the switch being continuously switched between an open position and a closed position by a signal from at least one of the first electronic switch module and the second electronic switch module, wherein:

[0095] The first electronic switch module is adapted to switch the at least one switch in a first mode at a rate and a duty cycle provided by the repetitive signal generating circuit, the first electronic switch module being powered by the electrical power output by the power conversion element, and

[0096] the second electronic switch module is adapted to switch the at least one switch in a second mode at any one or both of a variable rate and a variable duty cycle provided by at least one controller, at least according to a requirement of the receiver, the third electronic switch module is powered by the electrical power output by the voltage conversion circuit,

[0097] and

[0098] (iii) The second electronic switch module starts operating only when the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold value.

[0099] This method may also include the following steps:

[0100] (iv) transmitting information about the operation of the receiver from a signal transmitter on the receiver back to the transmitting system from which said beam of power was transmitted, and

[0101] (v) using this information to adjust the power of the light beam sent to the receiver,

[0102] in,

[0103] (a) the signal transmitter is powered by the output of the voltage conversion circuit,

[0104] (b) the signal transmitter is adapted to start operating only after the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold, and

[0105] (c) The signal transmitter is adapted to commence operation only after receiving a signal from the at least one controller.

[0106] Any of these methods may also include the steps of disabling the operation of the first electronic switch module and enabling only the second electronic switch module to operate at least one switch of the single voltage conversion circuit. In this case, the first electronic switch module may be forced to be disabled and only the second electronic switch module may be enabled to operate at least one switch of the voltage conversion circuit by using only a single inductor in the single voltage conversion circuit.

[0107] Alternatively, in this method, the at least one inductor and the at least one switch can be two inductors and two switches, and the inductor and the switch are associated with each of the first electronic switch module and the second electronic switch module, so that both the first electronic switch module and the second electronic switch module are enabled to operate simultaneously, with one electronic switch module on each of the separate voltage conversion circuits.

[0108] Finally, according to another exemplary implementation of the device described in the present disclosure, a receiver is also provided, the receiver being configured to provide power from a transmitted beam to a device associated with the receiver, the receiver comprising:

[0109] (i) a power conversion element adapted to convert beam power into a current at a first voltage,

[0110] (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,

[0111] (iii) a comparator circuit adapted to prevent current from the voltage converter from being applied to a device associated with the receiver if the second voltage is above a first threshold, the first threshold being input to the comparator circuit as a reference level, and

[0112] (iv) an electronically controlled switch having a shunt resistor adapted to maintain a minimum current to a device associated with the receiver if the second voltage drops below a second threshold voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0113] The present invention will be more fully understood and appreciated from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0114] Figure 1 schematically illustrates a typical receiver circuit of a general exemplary implementation of a circuit according to the present disclosure, showing certain electronic components of the circuit;

[0115] Figure 2 is a block diagram of a first exemplary implementation of a two-stage conversion and control system of the present disclosure;

[0116] Figure 3 is a block diagram of a second exemplary implementation of a two-stage conversion and control system of the present disclosure;

[0117] Figure 4 is a block diagram of a third exemplary implementation of a two-stage conversion and control system of the present disclosure; and

[0118] Figure 5A circuit arrangement is shown for efficient use of incident power for storage in a peripheral device, in particular at low incident powers.

[0119] Specific implementation method

[0120] Reference now Figure 1 , which schematically illustrates a typical receiver circuit according to an exemplary implementation of the circuit of the present disclosure, including specific components of the circuit. More details of the receiver will be described in detail below. Figure 1 In the receiver circuit shown, prior to receiving power, and during the initial operating phase of power reception and conversion, the main controller is shut down because there is insufficient voltage to operate it, as are all peripheral devices and circuits, including the output of the client device, any battery charging circuits, the backchannel communication link to the optical power transmission system of the receiver, the ADC circuits used to provide digital inputs from various sensors to the main controller, any measurement circuits, the LEDs used to operate the optically actuated backchannel, and any other such auxiliary circuit functions. In fact, the only active circuit in the receiver is that of the photovoltaic cell PV, which will not provide output current as long as there is no illumination power beam impinging on it, but it will respond to any incident illumination by producing an output current, the voltage of which will depend on the intensity of the impinging power beam.

[0121] Referring now more fully to the details of the receiver, as with prior art wireless power receivers using a laser beam 1 as a source of wireless power, a photovoltaic cell 15 (hereafter referred to as PV) performs a photoelectric conversion and outputs a current A1 at a voltage V1, which is typically well below 1V when the receiver first detects the incident power beam 1 which may be at a very low level. However, such voltage levels are insufficient for complex logic circuits based on digital electronics to operate properly. Therefore, the PV output is input into a conventional DC / DC boost converter circuit 17, which includes an inductor 11 and a transistor switch 12, where the switching timing is operated by a basic control module 13, which may simply be a low power signal generator without any other control inputs, or with a very limited set of simple control inputs and capabilities so that it can operate at the low output voltage of the PV 15 with minimal power consumption. The switched inductor output current is rectified by a diode 14 to provide a current having a DC voltage V2 that is higher than the voltage output V1 of the PV cell. This simple DC / DC boost converter can operate at very low power levels, providing an output DC current A2 from the inductor 11 and the rectifier diode 14, now the voltage level V2 is typically above 1V, because the DC / DC converter is configured as a boost converter, such as Figure 1 shown.

[0122] The receiver of the present disclosure differs from such prior art receivers in that the output DC current A2 is now at a voltage V2 sufficient to wake up and power the receiver's main controller 10, which includes digital logic circuits that process inputs from measurement sensors and peripherals and provide control outputs to other peripherals or circuits of the receiver and provide output current to the receiver client circuits 16. However, it is also important to note that by supplying a higher V DD Operating the main controller 10, the entire power conversion process from input optical power to the required output power can now be made more efficient. In fact, the main controller 10 now takes over the control of the simple DC / DC boost converter 17 from the basic controller 13, which was originally powered by it. The main controller 10 with complete logic control functions can now calculate the optimal duty cycle and optimal switching frequency of the inductor 11 of the DC / DC boost converter 17 according to the operating needs of the receiver. This calculation capability requires a stable voltage higher than the voltage V1 generated by the PV, and this voltage is not available before the main controller 10 starts operating. The main controller can then start the DC / DC boost converter 17 in an optimized mode according to the input and output of the peripheral devices and output devices at each moment and situation of the receiving operation. This level of operational flexibility is not easily obtained when using a basic controller to switch the DC / DC converter 17. Therefore, the logic function of the main controller 10 is able to check the current, the voltage on the various circuits, the load applied by one or more output devices, and now control the entire power conversion process.

[0123] A particular feature of the above electronic architecture of the receiver is that the main controller 10 is operated by the output V2 of the DC / DC converter 17 and is therefore not operable to control the DC / DC converter until the converter itself is operated using the basic controller 13. Therefore, even though the main controller 10 is operated by the output of the DC / DC converter 17, once the high power main controller mode begins operation, the controller 10 also acts as the main control input on the DC / DC converter 17.

[0124] like Figure 1 As shown, the main controller provides outputs to or receives inputs from a plurality of other circuits and peripherals. Such peripherals include analog-to-digital converter circuit ADC 19 for converting analog signals (such as, for example, V1, A1, V2 or A2) from measurement probes or sensors into digital signals for input into the main controller 10. In addition, a reverse channel communication link and its signal source ( Figure 1 Not shown, but in the following Figure 2 , 3The master controller may be configured to provide power to the receiver (designated as Comm in Figure 4) to direct the transmitter to provide more power to the receiver when needed. In addition, depending on the available power and the power required by the client device 16, the master controller may direct current to the client device, or to its battery or capacitor for charging. In addition, the master controller may perform a complex optimization process on the generation of the output current, which is similar to the process performed by the MPPT circuit, which will be further explained below. In the initial stages of the boost converter operation, this complex optimization process cannot be performed using a simple control mode.

[0125] It should be emphasized that Figure 1 The specific auxiliary circuits shown in and discussed above and elsewhere are exemplary circuits and are not necessarily part of the inventive concept of the receiver architecture of the present disclosure. In a specific receiver configuration, there may be more or less such auxiliary circuits, Figure 1 The circuits shown are intended to illustrate a selection of the most common or important functions of a receiver.

[0126] In the absence of any external power source for the receiver other than the incident low power scanning laser power beam 1, the manner in which the receiver of the present disclosure starts up can be described as follows. Before the receiver first detects a substantial incident laser beam, the PV cell outputs a current A1 at a low wattage, not only because the efficiency of the electrical to electrical power conversion is low, causing the PV to not operate in the most efficient load, but also because the backchannel communication to the transmitter does not work at this stage because it does not receive any voltage from the main controller. Therefore, the transmitter cannot operate in a higher power mode without instructions via the backchannel communication link. Therefore, any incident laser beam 1 is just looking for the scanning beam of the receiver and has a low power level. Similarly, other peripheral devices do not work because the DC / DC converter is not operated by the main controller and is therefore unable to provide the output voltage required for its operation in the initial stage. Therefore, the receiver uses very little current and is essentially in sleep mode.

[0127] Upon detection of the incident laser beam 1, and before being in a position to provide confirmation to the transmitter that the transmitted scanning beam has been incident on the real receiver, since the backchannel communication link is still inactive, the base controller receives a low voltage signal from the PV cell sufficient to actuate the base controller 13, so that the base controller 13 can operate the DC / DC boost converter 17 in its initial mode, thereby providing sufficient output voltage so that the main controller 10 can now start operating. Only when the DC / DC boost converter 17 provides sufficient output to enable the main controller to start and drive the DC / DC conversion in a more efficient manner, the peripheral devices 18a, 18b, 18c, ... receive operating voltages from the converters now operated by the main controller 10 and are therefore switched on, thereby enabling the main controller to efficiently control the DC / DC converters to provide more output power than the initial mode could provide.

[0128] In order to increase the output voltage from PV cells, some optical power receivers use multiple cells connected in series to achieve higher voltages. However, a disadvantage of such series-connected PV cells is that they cannot withstand local hot spots in the incident laser beam, and in order to operate efficiently, they generally require a beam with no area in the beam profile where the beam intensity is typically more than twice the average beam intensity. When the generated laser beam is likely to have such hot spots, the receiver should be equipped with a beam homogenizer to enable the beam to be transmitted to such multiple cells PV. An additional advantage of the receiver of the present application is that a single photovoltaic cell, preferably with 1-3 junctions, can be used as an optical to electrical power conversion element, so that beam homogenization is not required in the receiver, thereby achieving volume, weight and cost advantages. As described above, since a single PV cell produces a low output voltage, typically below the minimum required to operate conventional digital electronics, the receiver described herein is specifically optimized to efficiently convert the optical power received by such an optical-to-electrical power converter, and is particularly suitable for receiving an unhomogenized laser beam for conversion into electrical power.

[0129] Reference now Figure 2 , Figure 3 and Figure 4 , which schematically illustrate three different ways in which the above receiver configuration can be implemented. These schematic block diagrams also show Figure 1 More logic paths are used in the sequential operation of the two separate control functions of the DC / DC boost converter 17.

[0130] Figure 2 is a block diagram of the first implementation of a two-stage conversion and control system. Figure 2 A characteristic feature of the arrangement is that the inductor of the DC / DC boost converter is a shared component which is controlled by the first stage of the converter using a basic controller 13 and then by the inductor using Figure 1 The main controller 10 (in Figure 2 The final level control mode, marked as Contr) in , is used by both.

[0131] exist Figure 2 The following circuit elements are shown:

[0132] LVS (Low Voltage Switch) - This is Figure 1 The basic controller 13 is used to provide the duty cycle and frequency at which the converter is switched. It contains switches that can be operated from the low drive voltage available during the start-up of the receiver, a low voltage oscillator and basic control logic. The power used to operate it is directly supplied by the V DD The low PV voltage at the input provides. However, LVS has low efficiency because the PV does not output a voltage high enough to effectively operate the semiconductor devices in the LVS.

[0133] HES (High Efficiency Switches) - This contains low resistance switches that require higher drive voltages, which are only available after the main controller is put into operation. Once the main controller Contr is operational, it provides a disable signal DIS to the first mode controller LVS to shut down the LVS so that now only the main controller operates the high efficiency switches to provide switching to the DC / DC boost converter. At this stage, the shared inductor L that was previously used in the initial stage converter operation is still used in the converter circuit. The main controller Contr can now be operated to provide the best efficiency of the conversion process.

[0134] PMS (Power Measurement System) - includes PV current and voltage measurement circuits and ADC circuits to provide digital information about the measured current and voltage levels.

[0135] Comm (communication link) represents a back-channel communication link between a receiver and a sender to provide secure operation of the sender's transmissions. The receiver end of the back-channel communication link includes a signal transmitter to send the receiver data to the sender.

[0136] Contr.-Main controller, which contains the control logic including the CPU that manages the entire system.

[0137] exist Figure 2 In the implementation, both switches LVS and HES share a common inductor L, which means that only one switch control can be active at any point in time. The LVS is powered on first, generating a high voltage to operate the other modules of the system. Then, the main controller Contr disables the LVS through its DIS input and enables the HES through its CTR input, so that an efficient and widely applicable power conversion process can now be achieved. Sharing the inductor L reduces the size and cost of the system, the inductor is a relatively bulky component.

[0138] Reference now Figure 3 , which is a block diagram of the second implementation of the two-stage conversion and control system. Figure 3 The arrangement is characterized by Figure 2 The implementation is different and uses two separate DC / DC converters that can work together simultaneously. Each converter then has its own set of inductors and switches to start the pulse mode conversion.

[0139] exist Figure 3 The following circuit elements are shown:

[0140] WUC - Wake-up Converter, which operates directly from the IN LV input of the PV's low voltage output, as well as providing the initial DC / DC boost conversion when the incident laser power on the PV is still low. The WUC is a complete self-contained DC / DC converter, although the efficiency is not high due to its low operating voltage.

[0141] MC is the main converter, which also has its own set of inductors and switches to enable pulse-mode DC / DC conversion, but since it uses a higher voltage V DD Input operation, so it has high conversion efficiency.

[0142] Figure 3 The system wake-up sequence is Figure 2 Same, except in Figure 3 In the operation mode, since the disable signal DIS is not provided to the WUC converter, it continues to operate together with the main converter MC. OUT This is separate from the logic voltage used to output from the main controller Contr, which makes the system more versatile, but at the expense of one additional inductor. One disadvantage is that the less efficient first mode converter WUC always runs from the low input voltage source PV, which reduces the overall efficiency of the system.

[0143] Reference now Figure 4 , which is a block diagram of the third implementation of the two-stage conversion and control system. Figure 4 The arrangement is characterized by Figure 3 In different implementations, once the main converter starts operating, the WUC can switch to a higher voltage source, so that the power efficiency of the WUC reaches that of the main converter MC. Figure 4 The V OUTThe power line applied back to the IN_HV voltage supply input of the WUC is shown. As shown, the WUC can therefore operate from the low PV voltage output IN_LV in startup mode, or from the higher voltage supply IN_HV after the main controller Contr is also running. Therefore, of the three exemplary implementations shown, this implementation has the highest power conversion efficiency.

[0144] One of the main goals of the receivers described herein is to provide optimal delivery of incident beam power to the electronics, devices or storage elements associated with the receiver, these loads are often referred to as client power targets. This goal is particularly important when the received power is at low levels.

[0145] Reference now Figure 5 , which shows an exemplary circuit arrangement for efficiently utilizing incident power, which is used to store the incident power in a peripheral device, especially when the incident power is low.

[0146] VSYS means Figure 2 , Figure 3 or Figure 4 When the voltage is below a first threshold set by R1, R2 and their associated switch S2, the power of the peripheral device connected to Vload is controlled by the setting of switch S2 and the bypass resistor R bp limit, switch S2 turns off when the voltage drops below the set threshold. However, a “keep alive” current always flows through R bp Continue to supply Vload. Vload can be a battery, battery charger, capacitor, supercapacitor or any user device. This keep-alive current is particularly useful, for example, in maintaining the power of memory chips.

[0147] from Figure 4 The voltage output by the main converter VOUT is input to Figure 5 A circuit of , and a voltage proportional to VOUT is generated between R3 and R4. This voltage is compared with the voltage Vref applied to the comparator.

[0148] If the voltage between R3 and R4 is higher than VREF (VREF is a defined second threshold), the switch S1 is turned off, so that the power output from the main converter is disconnected from the peripheral device connected to Vload, thereby avoiding damage to the peripheral device due to the applied overvoltage. The system output voltage when the load is disconnected from the system can be selected by selecting Vref.

[0149] In summary, this arrangement thus ensures that a "keep alive" current is supplied to Vload when the voltage output at VSYS is below a first threshold. When the voltage in VSYS is above a second threshold, the peripherals connected to Vload are disconnected from the power supply in order to avoid damaging the load.

[0150] Example embodiments are provided so that the present disclosure will be thorough and the scope will be fully conveyed to those skilled in the art. Many specific details, such as examples of specific components, devices and methods, are set forth 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 example embodiments may be embodied in many different forms and none of them should be construed as limiting the scope of the present disclosure. In addition, it will be understood by those skilled in the art that the present invention is not limited to what is specifically shown and described above. On the contrary, the scope of the present invention includes combinations and sub-combinations of the various features described above and variations and modifications that those skilled in the art will expect when reading the above description and that are not in the prior art.

Claims

1. A receiver for converting an optical power beam into electrical power for use in an electronic system, the receiver include: a power conversion element adapted to convert the beam power into a current at a first voltage; a signal transmitter adapted to transmit information regarding the operation of said receiver back to a system transmitting said optical power beam; as well as a voltage conversion circuit adapted to convert the current having the first voltage into a current having a second voltage higher than the first voltage, the voltage conversion circuit comprising 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 switch module and the second electronic switch module, The electronic switch module is characterized in that: the first electronic switch module being adapted to switch the at least one switch in a first mode at a rate and a duty cycle provided by the signal generating circuit, the first electronic switch module being powered by the electrical power output by the power conversion element; the second electronic switch module being adapted to switch the at least one switch in a second mode at least in accordance with a requirement of the receiver at either or both of a variable rate and a variable duty cycle provided by at least one controller, the second electronic switch module being powered by the electrical power output by the voltage conversion circuit, and The second electronic switch module is adapted to start operating only when the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold; and in, (i) the signal transmitter is powered by the output of the voltage conversion circuit; (ii) the signal transmitter is adapted to start operating only after the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold; and (iii) The signal transmitter is adapted to start operating only after receiving a signal from the at least one controller.

2. The receiver according to claim 1, in, Operation of the second electronic switch module at the second voltage enables the second electronic switch module to actuate the voltage conversion circuit with a higher power conversion efficiency than the voltage conversion circuit operated by the first electronic switch module in the first mode.

3. The receiver according to claim 2, in, At least because the higher level of the second voltage compared to the first voltage enables the semiconductor switching device within the second electronically operated switching module to operate with a lower closing resistance than the closing resistance of the switching device in the first electronic switching module, a higher conversion efficiency of the voltage conversion circuit actuated by the second electronic switching module is achieved.

4. The receiver according to claim 2, in, At least due to the more effective control of the required switching parameters by using the at least one controller to adapt the switching parameters to the receiver requirements, the conversion efficiency of the voltage conversion circuit that realizes the actuation of the second electronic switch module is higher than the conversion efficiency achieved by using the signal generating circuit in the first electronic switch module.

5. A receiver according to any one of the preceding claims, in, The at least one inductor is common to both the first electronic switch module and the second electronic switch module.

6. The receiver according to claim 5, in, The at least one controller is adapted to prevent the first electronic switch module and the second electronic switch module from operating the at least one switch simultaneously.

7. A receiver according to any one of the preceding claims, in, The at least one controller is adapted to output a disable signal to terminate operation of the signal generating circuit of the first electronic switch module when the second voltage exceeds a predetermined second threshold level.

8. A receiver according to any one of claims 1 to 4, in, The first electronic switch module and the second electronic switch module operate with separate inductors.

9. The receiver according to claim 8, in, Using a separate inductor enables the second electronic switch module to provide an output current at a voltage that is independent of the second voltage output by the voltage converter.

10. The receiver according to claim 8, in, Using a separate inductor enables the at least one controller to provide the second voltage to the first electronic switch module such that an increase in operating efficiency of semiconductor switching devices within the first electronic switch module is achieved.

11. A receiver according to any one of the preceding claims, in, The signal transmitter is adapted to transmit a signal comprising information based on data from at least one sensor measuring at least one of: the received power of the light beam; the portion of the beam power absorbed by the power conversion element; an output from the power conversion element; an output from the voltage conversion element; and The temperature of the power conversion element.

12. The receiver according to claim 11, in, The transmitter is adapted to send a digital signal to a transmitter generating the optical power beam, such that the level of the optical power beam sent to the receiver is adjustable according to the information sent by the signal transmitter.

13. The receiver according to claim 1, in, The transmitter is activated by the at least one controller only when the second electronic switch module has begun to operate.

14. The receiver according to claim 13, in, The signal transmitter The digital signal is emitted at least once per second, wherein P is the electric power generated by the power conversion element.

15. A receiver according to any one of the preceding claims, in, 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. A receiver according to any one of the preceding claims, in, During a period in which the second electronic switch module has begun operating, power consumption in the receiver and operation of auxiliary circuits are controlled so that at least 50% of the power generated by the optoelectronic converter is provided for use by the electronic system.

17. The receiver according to claim 16, in, The auxiliary circuits and power losses include at least one of the following: Maximum power point tracking circuit; The average power loss on the coil during operation; the average power loss across the switch during operation; and The power used by the signal transmitter.

18. A receiver according to any preceding claim, adapted such that the optical power beam which the receiver converts to electricity is a laser beam.

19. A receiver according to any one of the preceding claims, in, The power conversion element is at least one photovoltaic cell.

20. A receiver according to any one of the preceding claims, in, The power conversion element is a single photovoltaic cell, enabling the receiver to operate efficiently with a transmit beam having a profile with at least one hot spot, or to operate with a beam that is not homogenized.

21. A method for converting a beam of power sent to a receiver into electrical power for use by an electronic system, include: converting the beam power into a current at a first voltage by using a power conversion element; The current at the first voltage is converted into a current at a second voltage higher than the first voltage by using at least one voltage conversion circuit, each voltage conversion circuit comprising an inductor and a switch, the switch being continuously switched between an open position and a closed position by a signal from at least one of the first electronic switch module and the second electronic switch module, wherein: the first electronic switch module being adapted to switch the at least one switch in a first mode at a rate and a duty cycle provided by a repetitive signal generating circuit, the first electronic switch module being powered by the electrical power output by the power conversion element; and the second electronic switch module being adapted to switch the at least one switch in a second mode at least in accordance with a requirement of the receiver at either or both of a variable rate and a variable duty cycle provided by at least one controller, the second electronic switch module being powered by the electrical power output by the voltage conversion circuit, and The second electronic switch module is enabled to start operating only when the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold.

22. The method according to claim 21, further comprising: The following steps are involved: transmitting information regarding the operation of said receiver from a signal transmitter on said receiver back to a transmission system from which said beam of power was transmitted; as well as using said information to adjust the power of said light beam sent to said receiver, in, (i) the signal transmitter is powered by the output of the voltage conversion circuit; (ii) the signal transmitter starts operating only after the voltage of the current output from the voltage conversion circuit exceeds a predetermined threshold; and (iii) The signal transmitter is adapted to commence operation only after receiving a signal from the at least one controller.

23. The method according to any one of claims 21 and 22, further comprising: The following steps are involved: Operation of the first electronic switch module is disabled, and only the second electronic switch module is enabled to operate the at least one switch of the single voltage conversion circuit.

24. The method according to claim 23, in, The first electronic switch module is forcibly disabled by using only a single inductor in a single voltage conversion circuit, and only the second electronic switch module is enabled to operate the at least one switch of the voltage conversion circuit.

25. The method according to any one of claims 21 and 22, in, At least one inductor and the at least one switch include two inductors and two switches, the inductors and the switches are associated with each of the first electronic switch module and the second electronic switch module, so that both the first electronic switch module and the second electronic switch module are enabled to operate simultaneously, with one electronic switch module on each of the separate voltage conversion circuits.

26. A receiver for providing power from a transmitted beam to a device associated with the receiver, the receiver include: a power conversion element adapted to convert beam power 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 the voltage converter from being applied to a device associated with the receiver if the second voltage is above a first threshold value, the first threshold value being input to the comparator circuit as a reference level; as well as An electronically controlled switch has a shunt resistor adapted to maintain a minimum current to a device associated with the receiver if the second voltage drops below a second threshold voltage.

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