阅读说明：本技术 增强的异物检测方法 (Enhanced foreign object detection method ) 是由 I·谢尔曼 E·马赫 于 2019-06-26 设计创作，主要内容包括：根据本公开的一个方面,提供确定校准信号强度因子的方法,该方法用于通过定位在发射器顶部的接收器进行异物检测的增强方法,确定校准信号强度因子的方法包括：在第一位置处测量由发射器发起的数字ping产生的第一信号强度,其中,第一位置是最佳耦合位置；确定第一位置的第一Q因子,其中第一Q因子是报告的Q因子；在第二位置处测量由发射器发起的另一数字ping产生的第二信号强度；确定第二位置的第二Q因子；根据第一信号强度、第二信号强度、第一Q因子和第二Q因子确定校准信号强度因子。根据本公开主题的另一方面,通过位于发射器顶部的接收器进行异物检测的增强方法,该方法包括：测量由发射器发起的数字ping产生的信号强度；通过用校准后的信号强度因子归一化信号强度来确定校准后的信号强度值；以及将校准后的信号强度和报告的Q因子的值传送给发射器,其中发射器基于这些值执行异物检测。(According to one aspect of the present disclosure, there is provided a method of determining a calibration signal strength factor for use in an enhanced method of foreign object detection by a receiver positioned atop a transmitter, the method of determining a calibration signal strength factor comprising: measuring a first signal strength resulting from a digital ping initiated by the transmitter at a first location, wherein the first location is an optimal coupling location; determining a first Q factor for the first location, wherein the first Q factor is a reported Q factor; measuring a second signal strength resulting from another digital ping initiated by the transmitter at the second location; determining a second Q factor for the second location; a calibration signal strength factor is determined based on the first signal strength, the second signal strength, the first Q factor, and the second Q factor. According to another aspect of the disclosed subject matter, an enhanced method of foreign object detection by a receiver located atop a transmitter, the method comprising: measuring a signal strength generated by a digital ping initiated by the transmitter; determining a calibrated signal strength value by normalizing the signal strength with the calibrated signal strength factor; and transmitting the calibrated signal strength and the reported values of the Q-factor to a transmitter, wherein the transmitter performs foreign object detection based on the values.)

1. A method of determining a calibration signal strength factor for use in an enhanced method of foreign object detection by a receiver positioned atop a transmitter, said method of determining a calibration signal strength factor comprising:

measuring a first signal strength resulting from a digital ping initiated by a transmitter at a first location, wherein the first location is an optimal coupling location;

determining a first Q factor for the first location, wherein the first Q factor is a reported Q factor;

measuring a second signal strength resulting from another digital ping initiated by the transmitter at the second location;

determining a second Q factor for the second location;

determining a calibration signal strength factor based on the first signal strength, the second signal strength, the first Q factor, and the second Q factor.

2. An enhanced method of foreign object detection by the receiver of claim 1 located on top of the transmitter, the method comprising:

measuring a signal strength generated by a digital ping initiated by the transmitter;

determining a calibrated signal strength value by normalizing the signal strength with the calibrated signal strength factor; and

transmitting the calibrated signal strength and the reported values of the Q-factor to the transmitter, wherein the transmitter performs foreign object detection based on these values.

3. An enhanced method of foreign object detection by a transmitter located below a receiver, the method comprising:

obtaining a calibrated signal strength value and a reported Q factor value from the receiver;

determining a system Q factor according to the measured decay time;

normalizing the system Q factor by using the corrected signal intensity to determine a normalized Q factor; and

performing foreign object detection by comparing the system Q factor to the normalized Q factor, wherein if the system Q factor is greater than the normalized Q factor, then there is at least one foreign object, otherwise there is no foreign object.

4. An enhanced method of foreign object detection by the transmitter of claim 2 located below the receiver, the method comprising:

obtaining a calibrated signal strength value and a reported Q factor value from the receiver;

determining a system Q factor from the measured decay time and the reported Q factor value;

normalizing the system Q factor by using the corrected signal intensity to determine a normalized Q factor; and

performing foreign object detection by comparing the system Q factor to the normalized Q factor, wherein if the system Q factor is greater than the normalized Q factor, then there is at least one foreign object, otherwise there is no foreign object.

5. An enhanced method of detecting foreign objects by a wireless power system placing the receiver of claim 1 on top of a transmitter, the method comprising:

measuring, by the receiver, a signal strength resulting from a digital ping initiated by the transmitter;

determining, by the receiver, a calibrated signal strength value by normalizing signal strength with a calibrated signal strength factor; and

transmitting the calibrated signal strength and reported values of the Q-factor to the transmitter, wherein the transmitter performs foreign object detection based on these values;

transmitting the value of the calibrated signal strength and the reported Q-factor to the transmitter;

determining, by the transmitter, a system Q factor based on the measured decay time;

determining, by the transmitter, a normalized Q factor by normalizing the system Q factor using the calibrated signal strength; and

performing, by the transmitter, foreign object detection by comparing the system Q factor to the normalized Q factor, wherein if the system Q factor is greater than the normalized Q factor, then there is at least one foreign object, otherwise there is no foreign object.

6. An enhanced method of detecting foreign objects by a receiver located atop a transmitter, the method comprising:

determining a reported Q factor at a best coupling location with a transmitter;

calculating a minimum time indicative of a maximum period of time that the receiver can maintain a power pause by the transmitter without interrupting its operation, wherein the calculated minimum time is based on parameters including a time constant and a minimum operating voltage of a rectifier of the receiver; and

transmitting the reported values of the Q-factor, the minimum time, and/or the parameters to a transmitter, wherein the transmitter performs foreign object detection based on the values.

7. An enhanced method of foreign object detection by a transmitter located below a receiver, the method comprising:

obtaining a minimum time value for a reported Q factor value and/or parameter value from the receiver;

determining a time slot from the minimum time value or a calculation of the minimum time based on the parameter value;

suspending power output to the receiver for a duration equal to one time slot;

performing repeated voltage or current measurements during the time slot to determine a decay time of the transmitter, wherein the measurements begin shortly after the start of the time slot;

calculating a system Q factor from the repeated measurements; and

performing foreign object detection by comparing the system Q factor to a reported Q factor, wherein if the reported Q factor is greater than the system Q factor, then there is at least one foreign object, otherwise there is no foreign object.

8. An enhanced method of foreign object detection by a transmitter located below the receiver of claim 6, the method comprising:

obtaining a minimum time value for the reported Q factor value and/or parameter value from the receiver of claim 6;

determining a time slot from the minimum time value or a calculation of the minimum time based on the parameter value;

suspending power output to the receiver for a duration equal to one time slot;

performing repeated voltage or current measurements during the time slot to determine a decay time of the transmitter, wherein the measurements begin shortly after the start of the time slot;

calculating a system Q factor from the repeated decay time measurements; and

foreign object detection is performed by comparing the system Q factor to a reported Q factor, wherein if the reported Q factor is greater than the system Q factor, then there is at least one foreign object, otherwise there is no foreign object.

9. An enhanced method of foreign object detection by a wireless power system having a receiver placed on top of a transmitter, the method comprising:

determining, by the receiver, a reported Q-factor at a best coupling location with the transmitter;

calculating, by the receiver, a minimum time indicative of a maximum period of time for which the receiver can maintain a power pause by the transmitter without interrupting its operation, wherein the calculated minimum time is based on parameters including a time constant and a minimum operating voltage of a rectifier of the receiver; and

transmitting the reported value of the Q factor, the minimum time value, and/or the parameter value to the transmitter;

determining, by the transmitter, a time slot based on a minimum time value or a calculation of a minimum time based on a parameter value;

suspending, by the transmitter, power output to a receiver for a duration equal to one time slot;

performing, by the transmitter, repeated voltage or current measurements during the time slot to determine a decay time of the transmitter, wherein the measurements begin shortly after the start of the time slot;

calculating a system Q factor from the repeated decay time measurements; and

performing, by the transmitter, foreign object detection by comparing the system Q factor to a reported Q factor, wherein if the reported Q factor is greater than the system Q factor, then there is at least one foreign object, otherwise there is no foreign object.

Technical Field

The subject matter of the present disclosure relates to wireless power charging systems. More particularly, the subject matter of the present disclosure relates to an enhanced method for detecting foreign matter.

Cross Reference to Related Applications

Priority of co-pending U.S. provisional patent application No. 62/690,356 entitled "Improving FOD in WPC" by Itay Sherman and Elieser Mach, filed 2018, 6, month 27, under 35u.s.c. 119 (e); this U.S. provisional application is incorporated herein by reference for all purposes.

Background

The growing demand for wireless power charging systems has led to significant deployment increases in a wide variety of sites, and increased demand to increase the effective charging distance between the transmitter and receiver. Typically, the system is mounted on top of a surface (e.g., a table, bar, etc.) that is accessible to the user, thus requiring a decorative appearance and a non-hazardous mounting. Most deployed systems are using wireless power alliance (WPC) Qi technology, which is constantly being pushed to increase power to meet the demand for high power consuming rechargeable devices such as smart phone laptops.

One of the safety issues associated with wireless power charging techniques is related to the presence of ferromagnetic materials (foreign objects) that may interfere with the wireless power transmitter and wireless power receiver of such systems. These foreign objects near the charging system may absorb energy from the magnetic field generated by the transmitter and cause overheating, ignition, particularly in high power charging.

Some commercially available charging systems employ a foreign object detection mechanism that is based on a measurement of the system Q-factor by a transmitter and comparing it to a reported Q-factor by a receiver. This mechanism requires that each power receiver (PRx) must store a Q factor value that is measured when optimally coupled to a reference transmitter during production. According to this mechanism, PRx transfers its stored Q factor to PTx each time it is placed on PTx, and PTx determines the Q factor by the PRx placed on it. The difference between the stored Q factor and the determined Q factor above a threshold is used by commercially available systems to indicate the presence of a foreign object.

It should be noted that cumulative testing for commercially available mechanisms showed greater than 25% inaccuracy in foreign body detection. It is an object of the present disclosure to provide an accurate method for foreign object detection.

Disclosure of Invention

According to a first aspect of the presently disclosed subject matter, a method of determining a calibration signal strength factor for use in an enhanced method of foreign object detection by a receiver positioned atop a transmitter, the method of determining a calibration signal strength factor comprising: measuring a first signal strength resulting from a digital ping initiated by a transmitter at a first location, wherein the first location is an optimal coupling location; determining a first Q factor for the first location, wherein the first Q factor is a reported Q factor; measuring a second signal strength resulting from another digital ping initiated by the transmitter at the second location; determining a second Q factor for the second location; determining a calibration signal strength factor based on the first signal strength, the second signal strength, the first Q factor, and the second Q factor.

According to another aspect of the disclosed subject matter, an enhanced method of foreign object detection by a receiver located atop a transmitter, the method comprising: measuring a signal strength generated by a digital ping initiated by the transmitter; determining a calibrated signal strength value by normalizing the signal strength with the calibrated signal strength factor; and transmitting the calibrated signal strength and the reported values of the Q-factor to the transmitter, wherein the transmitter performs foreign object detection based on these values.

An enhanced method of foreign object detection by a transmitter located below a receiver, the method comprising: obtaining a calibrated signal strength value and a reported Q factor value from the receiver; determining a system Q factor according to the measured decay time; normalizing the system Q factor by using the corrected signal intensity to determine a normalized Q factor; and performing foreign object detection by comparing the system Q factor to the normalized Q factor, wherein if the system Q factor is greater than the normalized Q factor, then there is at least one foreign object, otherwise there is no foreign object.

According to yet another aspect of the presently disclosed subject matter, an enhanced method of foreign object detection by a wireless power system having a receiver placed on top of a transmitter, the method comprising: measuring, by the receiver, a signal strength resulting from a digital ping initiated by the transmitter; determining, by the receiver, a calibrated signal strength value by normalizing signal strength with a calibrated signal strength factor; and

transmitting the calibrated signal strength and reported values of the Q-factor to the transmitter, wherein the transmitter performs foreign object detection based on these values; transmitting the value of the calibrated signal strength and the reported Q-factor to the transmitter; determining, by the transmitter, a system Q factor based on the measured decay time; determining, by the transmitter, a normalized Q factor by normalizing the system Q factor using the calibrated signal strength; and performing, by the transmitter, foreign object detection by comparing the system Q factor to the normalized Q factor, wherein if the system Q factor is greater than the normalized Q factor, then there is at least one foreign object, otherwise there is no foreign object.

According to yet another aspect of the presently disclosed subject matter, an enhanced method of detecting foreign objects is performed by a receiver located atop a transmitter, the method comprising: determining a reported Q factor at a best coupling location with a transmitter; calculating a minimum time indicative of a maximum period of time that the receiver can maintain a power pause by the transmitter without interrupting its operation, wherein the calculated minimum time is based on parameters including a time constant and a minimum operating voltage of a rectifier of the receiver; and communicating the reported values of the Q factor, the minimum time, and/or the parameters to a transmitter, wherein the transmitter performs foreign object detection based on the values.

According to yet another aspect of the disclosed subject matter, an enhanced method of foreign object detection by a transmitter located below a receiver, the method comprising: obtaining a minimum time value for a reported Q factor value and/or parameter value from the receiver; determining a time slot from the minimum time value or a calculation of the minimum time based on the parameter value; suspending power output to the receiver for a duration equal to one time slot; performing repeated voltage or current measurements during the time slot to determine a decay time of the transmitter, wherein the measurements begin shortly after the start of the time slot; calculating a system Q factor from the repeated measurements; and performing foreign object detection by comparing the system Q factor to the reported Q factor, wherein if the reported Q factor is greater than the system Q factor, then there is at least one foreign object, otherwise there is no foreign object.

According to yet another aspect of the disclosed subject matter, an enhanced method of foreign object detection by a wireless power system having a receiver placed on top of a transmitter, the method comprising: determining, by the receiver, a reported Q-factor at a best coupling location with the transmitter; calculating, by the receiver, a minimum time indicative of a maximum period of time for which the receiver can maintain a power pause by the transmitter without interrupting its operation, wherein the calculated minimum time is based on parameters including a time constant and a minimum operating voltage of a rectifier of the receiver; and transmitting the reported value of the Q factor, the minimum time value and/or the parameter value to the transmitter; determining, by the transmitter, a time slot based on a minimum time value or a calculation of a minimum time based on a parameter value; suspending, by the transmitter, power output to a receiver for a duration equal to one time slot; performing, by the transmitter, repeated voltage or current measurements during the time slot to determine a decay time of the transmitter, wherein the measurements begin shortly after the start of the time slot; calculating a system Q factor from the repeated decay time measurements; and performing, by the transmitter, foreign object detection by comparing the system Q factor to the reported Q factor, wherein if the reported Q factor is greater than the system Q factor, then at least one foreign object is present, otherwise no foreign object is present.

Drawings

By way of example only, some embodiments of the disclosed subject matter are described with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the disclosed subject matter only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the disclosed subject matter. In this regard, no attempt is made to show structural details of the disclosed subject matter in more detail than is necessary for a fundamental understanding of the disclosed subject matter, the description taken with the drawings making apparent to those skilled in the art how the various forms of the disclosed subject matter may be embodied in practice.

In the figure:

fig. 1 illustrates a block diagram of a system for wireless power charging, in accordance with some exemplary embodiments of the disclosed subject matter;

fig. 2 illustrates a flow diagram of a method for foreign object detection, according to some exemplary embodiments of the disclosed subject matter; and is

Fig. 3 illustrates a flow diagram of another method for foreign object detection, according to some exemplary embodiments of the disclosed subject matter.

Detailed Description

Before explaining at least one embodiment of the disclosed subject matter in detail, it is to be understood that the disclosed subject matter is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The disclosed subject matter is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. The drawings are generally not to scale. Unnecessary elements are omitted from some of the figures for clarity.

The terms "comprising," including, "" containing, "" including, "and" having, "and combinations thereof, mean" including, but not limited to. The term "consisting of … …" has the same meaning as "including and limited to".

The term "consisting essentially of … …" means that the composition, method, or structure may include other ingredients, steps, and/or components, but does not materially alter the basic and novel characteristics of the claimed composition, method, or structure.

As used herein, the singular forms "a", "an" and "the" include the plural forms unless the context clearly dictates otherwise. For example, the term "compound" or "at least one compound" may include a plurality of compounds, including mixtures thereof.

Throughout this application, various embodiments of the presently disclosed subject matter can be presented in a range format. It is to be understood that the description of the range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosed subject matter. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range.

It is to be understood that certain features of the disclosed subject matter, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosed subject matter which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination, or as suitable in any other described embodiment of the disclosed subject matter. Certain features described in the context of various embodiments should not be considered essential features of those embodiments unless the embodiment is inoperable without those elements.

One technical problem solved by the disclosed subject matter is the presence of unwanted metal objects (foreign bodies), which may lead to efficiency losses and possible safety hazards by absorbing a part of the electromagnetic field. In view of the ever-increasing power trend of wireless charging systems on the market, potential safety hazards become more serious. Typically, metal objects, such as coins, paperclips, or any ferromagnetic object, are attached to or located on or near a chargeable device (load), such as a cell phone case, a laptop computer; otherwise the transmitter may affect the magnetic field.

It should be noted that in the presence of a specific receiver (Rx), the Q factor of the transmitter (Tx)Is not fixed and may depend on the vertical distance between the Rx and Tx surfaces [ Z gap]But may vary. The main cause of this variation is a change in the reflected resistance, not just the inductance and/or frequency. When a typical receiver (i.e., a receiver embedded in a device with "friendly metal") is close to Tx, the friendly metal reflects a high resistance to Tx, while when the device is far from Tx, the reflected resistance decreases significantly. For reference receivers, this effect is less pronounced because they generally do not contain "friendly metals".

In the present disclosure, the term "device" refers to a device, such as a smartphone, a phone, a tablet, a laptop, etc., that can be charged by the wireless power supply system of the present invention. Also, in the present disclosure, the term "friendly metal" refers to an assembly that is an integral part of the device construction in which the receiver is embedded, the "friendly metal" having ferromagnetic properties that interact with the magnetic field and consume a portion of the energy.

In commercially available systems, the receiver will measure the signal strength resulting from a digital ping signal sent by the transmitter (Tx) and send a value representing the signal strength back to the Tx each time it is placed on the Tx. Cumulative tests have shown that the signal strength is not severely affected by the presence of small foreign objects, but the signal strength is strongly affected by the Z-gap, and therefore can indicate the Z-gap, i.e. the distance between the Rx and Tx surfaces, even if foreign objects are present. However, the lack of a clear, universal signal strength calibration method limits the use of signal strength for measuring Z-gap.

In commercially available wireless power systems, the Tx receives its stored Q factor from the Rx before establishing a power contract. Tx is then based on its own measured value of decay time (τ)The own Q, i.e., the system Q factor, is determined and then compared to the Rx reported Q factor to determine if a foreign object is present.

Another technical problem addressed by the disclosed subject matter is that the Q factor reported by Rx does not take into account the Z gap, which in practical applications may be different from the zero gap of Rx with the reference transmitter for laboratory conditions. Cumulative testing of Rx (e.g., 0 to 5 mm) over a typical Tx in various Z gaps for foreign material shows a definite systematic Q factor error that varies between 20% and 40% depending on the Z gap. This commercially available method leads to a ambiguous situation where it is unclear whether foreign matter is present or not, which is part of the technical problem solved by the present disclosure. An example of such possible ambiguity is that Rx with good coupling can produce a system Q factor similar to Rx with high z-gap and small foreign objects.

It should also be noted that commercially available methods using frequency-based foreign object detection similarly cause ambiguous situations based on cumulative testing. For example, Rx located above a typical Tx with a Z gap of 5mm without foreign objects has a higher attenuation frequency than the same Rx and Tx with a Z gap of 1.2 mm with foreign objects. Therefore, attenuating the frequency measurement alone is not sufficient to detect foreign objects.

It should also be noted that the commercially available methods using measured decay times (or derived Q-factors) are also not unique enough. For example, the cumulative test shows that the Q-factors of Tx and Rx measured when the Z-gap is 5mm with foreign matter are higher than the Q-factors of Tx and Rx calculated when the Z-gap is 0 without foreign matter.

One technical solution is to provide a precise foreign body mechanism that overcomes the above-mentioned disadvantages of the commercially available mechanisms.

It will be reminded that the signal strength that can be measured by Rx depends mainly on the Z-gap, i.e. the strength between Rx and Tx surfaces, but is less affected by foreign objects such as coins. It is also reminded that the reference Q factor reported by Rx does not reflect the possible variation of the Z gap, since in most cases the reference Q factor is measured when the Z gap is equal to 0, and therefore the reported value is lower than the worst case Q factor.

In some exemplary embodiments of the disclosed subject matter, Rx will be configured to perform a calibration procedure on the signal strength measurements based on calibration information obtained and stored at the factory or production line of the receiver. In addition, Rx should also transmit the value of the calibrated signal strength to Tx along with a reference Q factor to allow the foreign object detection mechanism to be adjusted for a particular Z gap setting.

One technical effect of utilizing the disclosed subject matter is to utilize calibrated signal strengths, reported values, to normalize the reported Q factors to correlate signal strengths with measured Q factors for different Z slots. Additionally or alternatively, the transmitter should normalize the reported Q factor with the value of the calibration signal strength and then perform the foreign object detection process.

Another technical solution is an enhancement method for determining the system Q-factor, which is based on a measurement of the decay time of the transmitter. In some exemplary embodiments, the transmitter may be configured to perform the measurement process also during operation (charging) without interrupting the operation of the receiver. The enhancement method of the present disclosure is configured to cancel the effect of the receiver primarily from the decay time measurement of the transmitter.

The technical effect of using an enhancement method to determine the system Q factor improves the accuracy of the determined system Q factor, thereby facilitating foreign object detection.

Referring now to fig. 1, shown is a block diagram of a system for wireless power charging, in accordance with some exemplary embodiments of the disclosed subject matter. The system for wireless power charging includes a transmitter (Tx)100 and a receiver (Rx) 200.

In some exemplary embodiments, the system may be adapted to utilize Tx 100 to charge a user's rechargeable device (load) 20 through an inductive power adapter using Rx 200 or directly to charge a load 20 with an embedded Rx 200. Rx 200 may include at least one secondary coil (Ls)210 and a capacitor (Cs)230, which together form an LC resonant circuit.

In some exemplary embodiments, Tx 100 may include transmitter electronics (Tx-electric) 150, at least one primary coil (Lt)110, and at least one capacitor Ct 130 configured to induce a current in the coil of Rx 200. The Tx-electric 150 includes a controller 151; a full or half bridge driver 152, a DC current sensor 153, a DC voltage sensor 154 and an AC current sensor 155.

The controller 151 may be a Central Processing Unit (CPU), microprocessor, electronic circuit, Integrated Circuit (IC), or the like. Additionally or alternatively, the controller 151 may be implemented as firmware written or ported to a particular processor, such as a Digital Signal Processor (DSP) or microcontroller, or may be implemented as hardware, such as a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), or configurable hardware. Controller 151 may be used to perform the calculations required by Tx 110 or any of its subcomponents.

In some exemplary embodiments of the disclosed subject matter, the controller 151 is configured to determine the following parameters:

a. the DC voltage across the PS 160 is measured by acquiring and measuring the results of the DC voltage sensor 154.

b. The DC current provided by PS 160 is obtained and measured by the results of DC current sensor 153.

c. By acquiring and measuring the result of the alternating current sensor 155, alternating current is supplied to Lt 110. Alternatively, the output AC current may be determined by sensing the instantaneous current flowing from the power supply to the driver with a DC current sensor 153.

It is noted that determining the ac current parameter may include peak current, average of absolute current, RMS current, amplitude of the first harmonic, any combination thereof, and the like.

In some exemplary embodiments, the controller 151 includes a semiconductor memory component (not shown). The memory may be a permanent or volatile memory such as FLASH memory, Random Access Memory (RAM), Programmable Read Only Memory (PROM), reprogrammable memory (FLASH), any combination thereof, or the like.

In some exemplary embodiments, memory retains reserved program code to activate the controller 151 to perform actions associated with determining a Pulse Width Modulation (PWM) signal to control the full-bridge or half-bridge driver 152. The driver 152 may regulate the output current flowing through Lt110, i.e., the power provided by Tx 100, by modulating the operating frequency and/or duty cycle of the current flowing through Lt 110. In some exemplary embodiments, the PWM signal generated in controller 151 adjusts the modulation to meet the requirements of wirelessly charging a load, such as load 20. In an alternative embodiment, the amplitude of the DC power supply may be controlled. Also, the PWM signal frequency and duty cycle may be set by the controller 151 within an operating frequency range suitable for the power requirements of the load 20. In some exemplary embodiments, the memories may retain program code to activate the controller 151 to send a digital ping to the receiver and perform actions related to any of the steps shown in fig. 2 and 3.

In some exemplary embodiments, controller 151 may utilize its memory to maintain connection software, monitoring information, configuration and control information, and applications associated with billing management of the disclosed system.

In some example embodiments, controller 151 may be configured to communicate with load 20 based on a protocol that conforms to the following communication standard: power alliance (PM); the Wireless Power Consortium (WPC) and the air fuel consortium (AirFuel Alliance). According to these communication methods, but not limited thereto, the controller 151 may be configured to acquire the user's credentials from the load 20 in order to authenticate the user for granting and regulating the charging service. Additionally or alternatively, controller 151 may also be configured to obtain its power requirements from device 20.

The components detailed above may be implemented as one or more sets of interrelated computer instructions that are executed, for example, by controller 151 or by another processor. The components are arranged as one or more executables, dynamic libraries, static libraries, methods, functions, services, etc., and are programmed in any programming language in any computing environment.

Referring now to fig. 2, a flow diagram of a method for foreign object detection is shown, according to some exemplary embodiments of the disclosed subject matter.

In step 201, a first signal strength may be measured S1. In some exemplary embodiments, Rx measures a first signal strength when Rx is at a first position on the reference PTx and at optimal coupling S1. Wherein the first position is defined as no gap (Z-vertical axis) between Rx and Tx, i.e., Z-gap is 0; the best coupling is defined as the best alignment between Rx and Tx (X-Y plane).

In step 202, a first Q factor may be determined. In some exemplary embodiments, Rx determines a first Q factor Q1 when located at a first position on reference PTx and at optimal coupling. In some exemplary embodiments, the first Q factor Q1 is equal to the reported Q factor.

In step 203, a second signal strength may be measured S2. In some exemplary embodiments, when Rx is located at a second position on the reference PTx and is in optimal coupling, Rx measures a second signal strength S2. Wherein the second position is defined as a higher gap, e.g. 5mm, e.g. a Z-gap of 5 mm.

In step 204, a second Q factor may be determined. In some exemplary embodiments, Rx determines a second Q factor Q2 when located at a second position on the reference PTx and at the best coupling.

In step 205, a calibrated signal strength factor (G) may be calculated for determining a calibrated signal strength [ S' ]. In some exemplary embodiments, Rx may perform the following calculations to determine factor G.

ΔQ＝Q₂-Q₁

ΔS＝S₂-S₁

Where F is a fixed factor, typically F ═ 10; 200 is a baseline value defining absolute perfect alignment; g is a factor that compensates for the signal strength measured by the Rx manufacturer, which is the relationship between Tx and Tx measured by the Rx of the present disclosure at any given Z-gap and unknown coupling quality (i.e., typical use of wireless power charging).

In some exemplary embodiments, steps 201 through 205 may be performed at the production line as part of a factory setup or initial configuration or at the time of commissioning the receiver.

In step 206, the calibrated signal strength S' may be determined and transmitted to the transmitter along with the reported Q factor Q1. It should be noted that in a typical operation process, when an Rx is placed on a Tx, the Rx may perform a signal strength measurement of a digital ping initiated by the transmitter, which results in an uncalibrated measured signal strength S3. In some exemplary embodiments, Rx may determine the calibrated signal strength S' using the following equation.

S′＝200-(S₃-S₁)*G

In step 207, the reported Q factor [ Q1] and the calibrated signal strength [ S' ] may be obtained from Rx times Tx.

In step 208, a system Q factor [ Qs ] may be determined. In some exemplary embodiments, Tx may determine Qs based on measured decay times before or after establishing a power contract with any given Rx. In general, Rx determines Qs when it is placed on it.

In step 209, a normalized Q factor [ Qn ] may be determined. In some exemplary embodiments, the following calculation may be made by Tx to determine the normalized Q factor.

In step 210, the presence of foreign matter may be detected. In some exemplary embodiments, if Qs is greater than Qn, there is no foreign matter, and if Qs is less than Qn, there is foreign matter.

The following table is an exemplary test case, including measurements and calculations for a device with embedded Rx, which was tested at four different Z-gaps (0, 1.2, 2.5 and 5 mm) with and without small foreign objects.

Z gap [ mm ]]	0	1.2	1.2	2.5	2.5	5	5
								Presence of foreign matter	Whether or not	Whether or not	Is that	Whether or not	Is that	Whether or not	Is that
Inductance [ mu H]	35.17	31.85	30.365	29.53	28.76	27.35	26.45
								Resistance [ m omega ]]	460	495	600	288	426	348	426
Maximum value of voltage [ V ]]	3.57	4.62	5.37	6.127	5.87	10.075	11.85
								Voltage 37% [ V ]]	1.32	1.71	1.99	2.27	2.17	3.725	4.38
Decay time [ μ Sec.]	140	158	93	162	115	173	146
								The decay frequency [ kHz.]	86.7	90.9	93.8	95.14	96	98.4	98.7
Signal strength	163	152	144	134	137	100	95
								Calculated system Q factor	44	49.6	29.2	50.9	36.2	54.35	45.9
Calibrated messageNumber strength	200	182	168	153	158	96	88
								Normalized Q { Qn }	40	41.8	43.2	44.7	44.2	50.4	51.2
Q margin based on Q1	+4	+9.6	-11.8	+10.9	-3.8	+14.35	+5.9
								Qn based Q margin	+4	+4	-14	+6.2	-8	+4	-5.3

Another technical solution is an enhancement method for determining the system Q-factor, which is based on a measurement of the decay time of the transmitter. In some exemplary embodiments, the transmitter may be configured to perform the measurement process also during operation (charging) without interrupting the operation of the receiver. The enhancement method of the present disclosure is configured to cancel the effect of the receiver primarily from the decay time measurement of the transmitter.

In this example, the calibrated signal intensity [ S ' ] is calculated based on the signal intensity measurements at the Z gap 0mm ' and the Z gap 5mm ' of the device without foreign matter. Tx normalizes the reference Q factor using the reported S value to produce Qn, which will be used for foreign object detection.

In some exemplary embodiments, the G values derived from these measurements depicted in the table are:

in the above example, Rx reports a Q factor that is 10% lower than the minimum Q factor measured on the surface (i.e., 40).

As can be seen from the measurements described in the above table, the calibration procedure eliminates ambiguity in foreign object detection for variable Z-gaps, providing a deterministic result with good margins even for small foreign objects. In contrast, with the Q1 margin, if the device is 5[ mm ] above the surface and there is a foreign object on the surface, then no foreign object is detected.

The above exemplary embodiment utilizes an approximately linear relationship of signal strength and Q factor. In another exemplary embodiment, the relationship between signal strength and Q factor is determined by performing a multi-point calibration on Rx (i.e., measuring the Q factor across multiple Z gaps and calibrating the signal strength accordingly). Additionally or alternatively, other relationships between the strength and the Q factor may be used in Rx reporting or Tx calculation of the Q factor.

In yet another exemplary embodiment, the information of the ringing frequency may be combined to further improve foreign object detection. The presence of a foreign object may increase the ringing frequency, but is not distinguishable from the increase in the Z-gap itself. However, given a Z-gap or Q-factor, a reference attenuation frequency may be defined for a given Z-gap or Q-factor, so that a measurement frequency higher than this frequency can be used to detect the presence of a foreign object.

Given the above examples and exemplary embodiments, the measured Q factor is used for the minimum and maximum Z-gaps, and based thereon a linear approximation of the decay frequency relative to the measured Q factor is defined, allowing some additional frequency margin of 2 KHz.

F_{Threshold value}Fmin + (Qdecay-Qmin) gain + fmalign 1.0435 Qdecay +43.69

Using the above threshold and comparing it with the actual measured decay frequency will provide a correct detection of foreign objects for all the above situations.

Referring now to fig. 3, fig. 3 illustrates a flow chart of another method for foreign object detection, according to some exemplary embodiments of the disclosed subject matter.

In some exemplary embodiments, the measurement of the decay time of the transmitter used to determine the system Q factor may be configured to perform the measurement process also during charging without interrupting the operation of the receiver. This enhanced method of the present disclosure is intended to mainly counteract the effects of the receiver during the decay time measurement of the transmitter.

In step 301, the receiver (Rx) may report the Q factor and Tmin to the transmitter (Tx). In some exemplary embodiments, based on a time constant [ τ ]]To calculate Tmin, the time constant is given by Cr230 and R_LProduct definition of 250, (. tau. ═ Cr. R) of FIG. 1_L). Due to the charging behavior of the capacitor Cr 240, the voltage decay of the charged Cr 240 (assuming the rectifier 240 captures to charge it) will be exponential, with a time constant equal to τ. Therefore, the following equation can be usedTo calculate Tmin (minimum time), where Vrec is the voltage output of rectifier 240, Vmin is the minimum voltage required for Rx before Rx operation is interrupted, and R_LIs the typical load resistance on Rx.

Additionally, or alternatively, instead of calculating Tmin, Rx may report Cr230, R to Tx_L250. The values of τ, Vrect, Vmin; and any combination so that Tx can calculate Tmin. In addition, Rx should also report the so-called "reported" Q factor, which is the standard Q factor measured during production Rx, as previously described.

In step 302, the transmitter may initiate a decay time measurement. In some exemplary embodiments, Tx may set a time slot (Tslot) less than or equal to a minimum time (Tmin), where Tslot is effectively the duration that Tx may suspend charging Rx without interrupting its operation. It should be noted that in one embodiment Tx will also calculate Tmin at this step, in which embodiment Rx reports its Tmin calculation parameters, i.e. resonant circuit value and Vmin, to Tx instead of calculating Tmin.

In step 303, the transmitter may suspend charging the receiver for a time slot equal to Tslot. In some exemplary embodiments, Tx stops its power driver operation from the driving coil Ls 110 for a period Tslot shorter than Tmin, thus causing Cr230 to start to decay. By doing so, the power for Rx charging is gradually reduced without interrupting the Rx operation.

In step 304, the transmitter may repeatedly measure the decay time. In some exemplary embodiments, Tx begins repeating the measurement shortly after Tslot begins (e.g., a preset time or a preset number of cycles, such as two cycles), where one cycle may be at least one resonant frequency cycle. In some exemplary embodiments, the decay time may be determined based on repeated measurements of the voltage or current of Ltl 10 and/or the resonant capacitor Ctl30 of fig. 1 during the remaining time of Tslot. Additionally or alternatively, Rx may also determine the ringing frequency based on the same measurements.

For example, it may be based on measurementsAnd the time interval between peaks to determine the decay time. Additionally, or alternatively, the decay time is determined by the following equation:where Δ t is the time interval between peaks; a1 and a2 are the amplitudes of two consecutive peaks. Additionally or alternatively, the ringing frequency f may be determined as 1/Δ t based on the time interval between the peaks of the measured voltage/current.

In steps 305 and 306, the transmitter may continue to charge Rx after Tslot ends and calculate the system Q factor based on repeated decay time measurements of the last Tslot.

In step 307, the presence of foreign matter may be detected. In some exemplary embodiments, the transmitter determines the presence of a foreign object if the Q factor reported by Rx is greater than the system Q factor calculated by Tx. Otherwise, if the Rx reported Q factor is less than the system Q factor, no foreign object is detected.

It should be noted that a typical inductive power Rx comprises a resistor connected to a typical resistive load R with a parallel capacitor Cr260_LThe resonant circuit (Ls 210 and Cs230) of the full-wave or half-wave rectifier 240. In some exemplary embodiments, the transmitter stops driving the power signal for a short defined period of time Tslot. The time period Tslot is determined such that the voltage decay of the rectifying capacitor Cr260 will not allow the voltage Vrect to drop below the system defined Vmin. By stopping the power signal in a time slot shorter than Tmin, the design of the present disclosure ensures that Rx power transmission will still continue without interruption.

It is an object of the presently disclosed subject matter to provide the ability to correctly measure the decay pattern on the current or voltage on the Tx in order to extract the decay time and derived Q-factor. The purpose is to be able to measure the Q factor value in the presence of any foreign object at Tx and "friendly metal" at Rx without having to turn off the power supply of the Rx receive circuit.

In steps 302-304, the signal decays when this short interval stops, and the voltage on Rx is higher than the rectifier open circuit voltage, and also higher than Vrect, so Rx receiving immediately after the power driver stops will still have current flowing through its rectifier. As the Rx load reflects to Tx, the signal will decay faster at Tx. This process continues until the induced voltage and the Rx circuit resonant circuit voltage are below the rectifier capacitor voltage. In most exemplary embodiments, 2 to 3 cycles of oscillation (typically 100kHz, i.e. 20-30 μ sec) are required before the decay time measurement begins.

It should be noted that once the rectifier is turned off, the effects of the Rx load and circuit are cancelled out, since little current flows in the Rx resonant circuit. The load is then completely powered by the rectifier capacitor.

It should also be noted that the decay time of Tx is longer when no foreign material is present and friendly metal is minimal. In this case, the decay time constant may be given by 2 × Lt/Rp, where Lt l10 is the Tx circuit inductance and Rp is its parasitic resistance. However, if the decay time of Tx is greater than the decay time of the rectified voltage (Cr × RL), the decay of the Tx induced voltage will be slower than the decay of the rectified voltage and at some point the rectification phase will start conducting again. In this case, Rx may employ the reported Tmin to rely on the estimated time before the commutation phase conduction recovers. In one embodiment, the reported time Tmin is selected as the sum of the times until commutation conductionThe lower of them.

The subject matter of the present disclosure can be systems, methods, and/or computer program products. The computer program product may include a computer-readable storage medium having computer-readable program instructions thereon for causing a processor to perform aspects of the disclosed subject matter.

The computer readable storage medium may be a tangible device that can retain and store the instructions for use by the instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic memory device, a magnetic memory device, an optical memory device, an electromagnetic memory device, a semiconductor memory device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer-readable storage medium includes the following: a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a Static Random Access Memory (SRAM), a portable compact disc read-only memory (CD-ROM), a Digital Versatile Disc (DVD), a memory stick, a floppy disk, a mechanical coding device (e.g., a punch card or a raised structure in a groove having instructions recorded thereon), and any suitable combination of the foregoing. As used herein, a computer-readable storage medium should not be construed as a transitory signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., optical pulses traveling through a fiber optic cable), or an electrical signal transmitted through an electrical wire.

The computer-readable program instructions described herein may be downloaded from a computer-readable storage medium to a corresponding computing/processing device, or downloaded to an external computer or external storage device over a network (e.g., the internet, a local area network, a wide area network, and/or a wireless network). The network may include copper transmission cables, optical transmission fibers, wireless transmissions, routers, firewalls, switches, gateway computers and/or edge servers. The network adapter card or network interface in each computing/processing device receives computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in a computer-readable storage medium within the respective computing/processing device.

Computer readable program instructions for carrying out operations of the disclosed subject matter may be assembler instructions, Instruction Set Architecture (ISA) instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider). In some embodiments, an electronic circuit comprising, for example, a programmable logic circuit, a Field Programmable Gate Array (FPGA), or a Programmable Logic Array (PLA), may personalize the electronic circuit by executing computer-readable program instructions with state information of the computer-readable program instructions in order to perform aspects of the disclosed subject matter.

Aspects of the disclosed subject matter are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosed subject matter. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer-readable program instructions.

These computer-readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer-readable program instructions may also be stored in a computer-readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer-readable storage medium having the instructions stored therein includes an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer, other programmable apparatus or other devices implement the functions/acts specified in the flowchart and/or block diagram block or blocks.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the disclosed subject matter. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosed subject matter. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the presently disclosed subject matter has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the subject matter in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosed subject matter. The embodiment was chosen and described in order to best explain the principles of the disclosed subject matter and the practical application, and to enable others of ordinary skill in the art to understand the disclosed subject matter for various embodiments with various modifications as are suited to the particular use contemplated.