Foreign object detection and related devices, methods, and systems

Abstract

Foreign object detection and related devices, methods, and systems are disclosed. In one embodiment, an apparatus includes: one or more induction coils, the one or more induction coils being wirelessly coupled with another induction coil; a series capacitor electrically connected in series with the one or more induction coils; and a controller to determine a coil current flowing through the one or more induction coils in response to a capacitor voltage potential difference across the series capacitor, and to determine a coil power in response to the determined coil current and a coil voltage potential difference across the one or more induction coils.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of the priority date of U.S. Provisional Patent Application No. 63 / 364,682, filed on May 13, 2022, entitled “FOREIGN OBJECT DETECTION AND RELATED APPARATUSES, METHODS, AND SYSTEMS,” the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates generally to foreign object detection in proximity to one or more induction coils, and more particularly to estimating a transmit power of the one or more induction coils in response to a capacitor voltage potential difference of a series capacitor and a coil voltage potential difference of the one or more induction coils. Background Art

[0004] Wireless power transfer technology is widely used to transfer power from one system to another in a wide range of applications. Qi is the most widely adopted wireless charging standard, and it has spread to almost all consumer mobile phone brands. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] While the present disclosure concludes with claims that particularly point out and distinctly claim specific examples, the various features and advantages of examples within the scope of the present disclosure may be more readily ascertained from the following description when read in conjunction with the accompanying drawings, in which:

[0006] Figure 1 is a block diagram of a wireless power system according to various examples;

[0007] Figure 2 is a schematic block diagram of a wireless power system according to one or more examples;

[0008] Figure 3 is a circuit diagram of a transmitter without a power filter according to one or more examples;

[0009] Figure 4 is a circuit diagram of a transmitter including a power filter according to one or more examples;

[0010] Figure 5 is a circuit diagram of a transmitter without a power filter according to one or more examples;

[0011] Figure 6 is a circuit diagram of a transmitter including a power filter according to one or more examples;

[0012] Fig. 7A , Figure 7B and Figure 7C are the corresponding graphs of the capacitor and coil voltage waveforms of the receiver under various load conditions;

[0013] Figures 8 to 12 is a flow chart of a detailed end-to-end method of determining coil power of a transmitter according to one or more examples;

[0014] Fig.13 is a flowchart for describing a method of determining coil power of a transmitter according to one or more examples; and

[0015] Fig.14 is a block diagram of circuits that, in some examples, may be used to implement the various functions, operations, actions, processes and / or methods disclosed herein. DETAILED DESCRIPTION

[0016] In the following detailed description, reference is made to the accompanying drawings which form a part of the present disclosure, and in which specific examples in which the present disclosure may be practiced are shown by way of example. These examples are described in sufficient detail to enable one of ordinary skill in the art to practice the present disclosure. However, other examples enabled herein may be utilized, and structural, material, and process changes may be made without departing from the scope of the present disclosure.

[0017] The illustrations presented herein are not intended to be actual views of any particular method, system, device, or structure, but are merely idealized representations used to describe examples of the present disclosure. In some cases, similar structures or components in the various drawings may retain the same or similar numbering for the convenience of the reader; however, the similarity of numbering does not necessarily mean that the structure or component is the same in size, composition, configuration, or any other attribute.

[0018] The following description may include examples to help enable a person of ordinary skill in the art to practice the disclosed examples. The use of the terms "exemplary," "such as," and "for example" means that the related description is illustrative, and while the scope of the present disclosure is intended to encompass the examples and legal equivalents, the use of such terms is not intended to limit the examples or the scope of the present disclosure to the specified components, steps, features, functions, etc.

[0019] It should be readily understood that the components of the examples as generally described herein and illustrated in the accompanying drawings may be arranged and designed in a variety of different configurations. Therefore, the following description of various examples is not intended to limit the scope of the present disclosure, but is merely representative of various examples. Although various aspects of these examples may be presented in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0020] In addition, the specific implementations shown and described are only examples and should not be construed as the only way to implement the present disclosure, unless otherwise specified herein. Elements, circuits, and functions can be shown in block diagram form so as not to obscure the present disclosure with unnecessary details. On the contrary, the specific implementations shown and described are only exemplary and should not be construed as the only way to implement the present disclosure, unless otherwise specified herein. Additionally, the partitioning of logic between block definitions and individual blocks is an example of a specific implementation. It will be apparent to those of ordinary skill in the art that the present disclosure can be practiced through many other partitioning solutions. In most cases, details about timing considerations, etc. have been omitted, where such details are not required to obtain a complete understanding of the present disclosure and are within the capabilities of those of ordinary skill in the relevant art.

[0021] Those of ordinary skill in the art will appreciate that information and signals may be represented using any of a variety of different technologies and techniques. For clarity of presentation and description, some of the figures may illustrate signals as single signals. Those of ordinary skill in the art will appreciate that a signal may represent a signal bus, where the bus may have a variety of bit widths, and that the present disclosure may be implemented on any number of data signals, including a single data signal.

[0022] The various exemplary logic blocks, modules, and circuits described in conjunction with the examples disclosed herein may be implemented or implemented with a general purpose processor, a special purpose processor, a digital signal processor (DSP), an integrated circuit (IC), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor (which may also be referred to herein as a host processor or simply a host) may be a microprocessor, but in an alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. When a general purpose computer including a processor is used to execute computing instructions (e.g., software code) associated with the examples disclosed herein, the general purpose computer is considered to be a special purpose computer.

[0023] Examples can be described according to processes depicted as flow charts, flow diagrams, structure diagrams, or block diagrams. Although flow charts can describe operable actions as continuous processes, many of these actions can be performed in another sequence, in parallel, or substantially simultaneously. In addition, the order of actions can be rearranged. The processes herein may correspond to methods, threads, functions, procedures, subroutines, subprograms, other structures, or combinations thereof. In addition, the methods disclosed herein can be implemented by hardware, software, or both. If implemented in software, functions can be stored or transmitted to a computer-readable medium as one or more instructions or codes. Computer-readable media include both computer storage media and communication media, and the communication media include any media that is conducive to transferring a computer program from one location to another.

[0024] Any reference to elements herein using names such as "first," "second," etc. does not limit the quantity or order of those elements unless such limitations are explicitly stated. Rather, these names may be used herein as a convenient method of distinguishing between two or more elements or instances of elements. Thus, reference to a first element and a second element does not mean that only two elements may be employed there, or that the first element must precede the second element in some manner. Furthermore, unless otherwise indicated, a group of elements may include one or more elements.

[0025] As used herein, the term "substantially" in reference to a given parameter, attribute, or condition refers to and includes the degree to which a person of ordinary skill in the art would understand that the given parameter, attribute, or condition is satisfied with a small degree of variance, such as, for example, within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, attribute, or condition that is substantially satisfied, the parameter, attribute, or condition may be satisfied by at least 90%, by at least 95%, or even by at least 99%.

[0026] The Qi wireless system includes a transmitter and a receiver. The transmitter controls the power transmitted to the receiver based on feedback received from the receiver. The transmitter includes at least one coil to which the receiver coil is coupled (e.g., inductively coupled) in the wireless system. In a multi-coil transmitter design, there are multiple transmitter coils that overlap each other so that the receiver coil can be placed on any of the transmitter coils. This provides spatial freedom for receiver placement, and close placement on the transmitter ensures power transfer. This is in contrast to a single coil transmitter, in which the receiver coil should be properly aligned with the transmitter coil for power transfer.

[0027] One of the functions of a transmitter is to detect the presence of a foreign object (FO) in its vicinity. The Qi specification recommends two methods for foreign object detection (FOD), namely Q and power loss. The Qi specification mentions using coil current to estimate the power transmitted to the receiver at a specific moment. At the same time, the receiver also measures the power it receives at its coil and transmits the number back to the transmitter. The transmitter calculates the power loss using the difference between the power transmitted by the transmitter and the power received by the receiver. When there is a foreign object between the transmitter and the receiver, the power loss value is higher than when there is no foreign object between the transmitter and the receiver. If the power loss exceeds a limit value (e.g., a predetermined threshold), it can be determined that a foreign object exists. Thus, the power loss difference can be used to detect foreign objects. This method can be used to detect foreign objects independently of the changing configuration of the transmitter.

[0028] The Qi power loss method suggests using a current sensor to measure the current flowing through the coil and using the current sensor to estimate the losses in the transmitter. There are several losses in the transmitter starting from the point where the power loss is measured (usually at the direct current (DC) input to the H-bridge). The H-bridge metal oxide semiconductor field effect transistors (MOSFETs), filter components, coil change switches, and finally the coils themselves have resistance, resulting in losses in these components. The power loss value may depend at least in part on several factors, such as the transmit coil to receive coil coupling ratio, the transmit coil and receive coil inductance, the components used in the transmitter, the accuracy of the power measurement at the transmitter and receiver, etc. Foreign object detection can be used to prevent foreign objects from overheating, which can cause catastrophic failures and dangers.

[0029] Avoiding overheating of foreign objects in the automotive space may be helpful. However, considering that current sensor-based foreign object detection may be relatively expensive, the cost of implementing foreign object detection may be relatively high. For example, complex circuits such as CT or Hall effect sensors may be used to perform coil current measurement, which is not preferred in the automotive industry. In addition, current sensor-based foreign object detection may be sensitive to vibrations, which may cause component failure. Although coil voltage-based power estimation may rely on estimating the power loss through the coil, such voltage-based power estimation methods may have limited accuracy.

[0030] Various examples disclosed herein relate to estimating power loss under different conditions and without using current sensors to detect foreign objects. Various examples disclosed herein can use low-cost hardware while providing reliable power estimation. Various examples disclosed herein can operate reliably with a variety of different transmitter topologies, multiple receivers, multiple transmitter-to-receiver coupling characteristics, multiple different output loads, and multiple input voltage potentials. Various examples disclosed herein relate to estimating approximate power loss in a system based at least in part on calibration data. Various examples disclosed herein can reduce the need for calibration and provide accurate power measurements under various conditions.

[0031] According to one or more examples, the coil voltage potential and the capacitor voltage potential may be used in place of the coil current. The capacitor voltage potential may be used to derive the current flowing through the capacitor by differentiating the capacitor voltage potential. Since the coil and capacitor are electrically connected in series, the capacitor current is substantially the same as the current flowing through the coil. The capacitor current, and by extension the coil current, may be determined on a sample-by-sample basis using the capacitor voltage potential. The coil voltage potential may be measured simultaneously with the capacitor voltage potential.

[0032] To match the delays in the two channels, the average value of the coil voltage potential may be considered. The dot product of the coil voltage potential and the capacitor current provides the active power on the transmitter coil. The active power may be calculated based on the average coil voltage and coil current samples over a number of fundamental cycles (1-5). The resulting power thus calculated may be an estimate of the power sent to the receiver.

[0033] This power may be averaged to determine the active transmit power. It may be measured by the transmitter and receiver at predetermined time intervals. Such time intervals may be determined during protocol negotiation (e.g., 1 millisecond time intervals). The receiver may transmit the power received at its end to the transmitter substantially once per second. The transmitter calculates the difference between the transmitted power and the power received by the receiver. If this power loss exceeds a predetermined threshold, it may be determined that a foreign object is present.

[0034] In some examples, when a receiver is placed on a transmitter and the transmitter stage continues to transfer power, an estimate of the transmitter power may be calculated every millisecond. Once the power supplied to the receiver is known at a given moment, the power loss may be calculated by subtracting the amount of receiver power shared by the receiver at the same moment. The power loss value may be compared to a predetermined threshold to determine if a foreign object is present. If a foreign object is present, the power loss value may be larger than the power loss value in the absence of a foreign object because both the receiver and the foreign object contribute additional losses as the transmitter supplies its own losses. This results in a larger power loss value than if no foreign object is present. When a foreign object is detected, the transmitter may stop supplying power to the receiver to avoid heating the foreign object and to avoid wasting power.

[0035] In some examples, various examples disclosed herein can ensure that transmitter power loss matches at different control variable points depending on transmitter to receiver coupling, receiver load, and receiver output voltage potential. In addition, various examples disclosed herein can work with a variety of receiver designs (e.g., approximately 165). If the power loss value is not accurate, there may be false trips due to the absence of a foreign object, or the transmitter may fail to stop power in the presence of a foreign object.

[0036] Various examples disclosed herein can provide accurate active power calculations independent of transmitter configuration, reduce or eliminate the need for calibration for a given design, eliminate the need for coil current sensing circuitry at the transmitter, enable reliable detection of foreign objects at transmitters with multiple receivers and varying load conditions, and can be implemented using simple, low-cost hardware.

[0037] According to various examples, a foreign object may be detected using simple hardware, sensing a transmitter coil voltage potential, sensing a series capacitor voltage potential, receiving an indication of received power from a wireless power receiver. Coil current may be estimated (e.g., implemented using software and / or hardware), transmitter coil active power may be calculated, and a power difference between the transmitted power and the received power may be calculated (e.g., at regular intervals). A power loss exceeding a threshold indicates the presence of a foreign object (e.g., if the power difference is greater than a predetermined threshold).

[0038] The various examples disclosed herein may be implemented by a wireless power transmitter. However, the various examples disclosed herein may also be implemented in other situations involving object detection.

[0039] According to various examples, a low-cost solution can be used to detect the presence of a foreign object proximate to a transmitter coil (e.g., on a transmitter surface) when a receiver is present. The power transmitted by the transmitter coil can be accurately calculated using samples of the coil voltage potential and the series capacitor voltage potential (e.g., samples acquired via a differential amplifier circuit). The estimated power transmitted by the transmitter coil can be compared to the power received by the receiver, and when the power loss exceeds a threshold, it can be determined that a foreign object is present between the transmitter coil and the receiver coil. The various examples can be implemented using minimal on-board hardware, and reliable performance under multiple dynamic conditions can be achieved.

[0040] Figure 1 1 is a block diagram of a wireless power system 100 according to one or more examples. The wireless power system 100 includes a transmitter 102 and a receiver 104. The transmitter 102 is powered by a DC voltage source 106, and the receiver 104 is connected to a load 108. Power is transferred from the transmitter 102 to the receiver 104 (i.e., from the transmitter coil 112 to the receiver coil 114) through a set of coupled coils 110. The transmitter 102 controls the power transferred by controlling the input voltage, frequency, phase, and / or duty cycle of the signal applied to the transmitter coil 112. Power is transferred via magnetic flux linkage; there is no physical connection between the transmitter 102 and the receiver 104. Power transfer is effective when the transmitter coil 112 and the receiver coil 114 are placed one above the other and aligned.

[0041] Figure 2 is a block diagram of a wireless power system 200 without a power filter according to one or more examples. Figure 1 Wireless power systems, Figure 2 The wireless power system 200 includes a transmitter 202 and a receiver 204. In one or more examples, the transmitter 202 is included as part of a first device and the receiver 204 is included as part of a second device, where the second device is separate and apart from the first device (e.g., the second device can be movable and repositionable independently of the first device).

[0042] The transmitter 202 is powered by a DC voltage source 206, and the receiver 204 is connected to a load 208. Generally speaking, power is transferred from the transmitter 202 to the receiver 204 through a set of coupled coils 210 (i.e., from a transmitter coil 212 (Lp) of the transmitter 202 to a receiver coil 214 (Lp) of the receiver 204). s )).

[0043] The transmitter 202 includes an H-bridge inverter 220 and a capacitor 222 (C p). Capacitor 222 may be referred to as a “transmitter tank capacitor” and more generally as a “series capacitor”. Controller 224 may drive H-bridge inverter 220 with a pulse width modulated (PWM) signal 226 or pulses. In one or more examples, controller 224 may be a microcontroller, such as a dsPIC microcontroller, but is not limited thereto. In one or more examples, PWM signal 226 may be a fixed frequency or a variable frequency, which may depend on the specific topology of transmitter 202.

[0044] Receiver 204 includes capacitor 230 (C s )、Capacitor 232(C sp ), bridge rectifier 234 (diode bridge), and communication and voltage control circuit 236. Capacitor 230 is electrically connected in series with receiver coil 214, and capacitor 232 is electrically connected in parallel with the series-connected capacitor 230 and receiver coil 214. Capacitor 230 (C s ) may be referred to as a "receiver tank capacitor" and more generally as a "series capacitor". The receiver coil 214 and capacitors 230 and 232 form a resonant tank circuit. The output of the resonant tank circuit passes through a bridge rectifier 234 which rectifies the voltage. The output of the bridge rectifier 234 passes through a buck converter or low dropout (LDO) regulator which provides a fixed voltage at the load 208.

[0045] As described herein, the transmitter 202 is used to determine whether a foreign object 290 is present between the transmitter coil 212 and the receiver coil 214. In one or more examples, the controller 224 can calculate the coil power of the transmitter 202, which can be used to calculate the power loss for detecting the foreign object 290. To do this, the controller 224 provides an input 250 to a first analog-to-digital converter (ADC) channel to sample the capacitor voltage across the capacitor 222 (Cp). The coil current can be calculated based on the sampled capacitor voltage. Note that since the capacitor 222 is coupled in series with the transmitter coil 212, the current flowing through the capacitor 222 is the same as the coil current. In addition, the controller 224 provides an input 252 to a second ADC channel to sample the coil voltage across the transmitter coil 212 (Lp).

[0046] The calculation of the coil power based on the above-obtained signal (eg, Figures 8 to 12 , Fig.13 In one or more examples, the transmitter 202 can determine whether the foreign object 290 is present without using conventional current sensors to measure the current flowing through the transmitter coil 212 and / or estimate losses in the transmitter 202 .

[0047] Figure 3is a circuit diagram of a transmitter 202A without a power filter according to one or more examples. Figure 3 The transmitter 202A illustrates an example of a device that can be used as Figure 2 The transmitter hardware of the transmitter 202. Figure 3 As shown, transmitter 202A is a multi-coil transmitter.

[0048] The H-bridge inverter 220 includes a plurality of switches 310, including switches 302, 304, 306, and 308 (respectively represented by S a , S b , S c and S d In one or more examples, switches 302, 304, 306, and 308 are MOSFETs driven by MOSFET drivers. A controller (e.g., Figure 2 A controller 224 of the embodiment of the present invention can control the operation of the H-bridge inverter 220. More specifically, the MOSFET driver input can be operably coupled to and / or controlled by a PWM pin on the controller. In operation, switches 302 and 308 are turned on during the positive half cycle, while switches 304 and 306 are turned on during the other half cycle. In one or more examples, the operating frequency can be fixed at 125kHz for the selected topology.

[0049] The transmitter 202A includes a plurality of coils 322, 324 and 326 (respectively labeled L 1 , L 2 and L 3 ) of the coil array 320. The plurality of switches 330 include switches 332, 334, and 336. The respective coils 322, 324, and 326 of the coil array 320 are connected to the switches 332, 334, and 336 (respectively indicated as S 1 , S 2 and S 3 ) are coupled in series.

[0050] Capacitor 222 has a first end coupled between switches 302 and 306 and a second end coupled to ends of coils 322, 324, and 326. A resonant tank circuit may be formed by capacitor 222 (Cp) and a selected one of coils 322, 324, and 326 connected across the output of the H-bridge inverter 220. The input of the H-bridge inverter 220 may be directly from the source or from the output of a four-switch buck-boost converter (FSBBC), which may control the input voltage provided to the H-bridge inverter 220.

[0051] The H-bridge inverter 220 applies an AC voltage across the resonant tank circuit formed by the capacitor 222 and a selected one of the coils 322, 324, and 326. When one of the switches 332, 334, and 336 is closed, it places the corresponding one of the coils 322, 324, and 326 in the resonant tank circuit (only one of the coils 322, 324, and 326 is connected to the H-bridge inverter 220 at a time). In one or more examples, the switches 332, 334, and 336 can be made of back-to-back MOSFETs for conducting bidirectional AC current in the resonant tank circuit. These switches can be controlled by a controller and can be switched as described.

[0052] Figure 4 is a circuit diagram of a transmitter 202B including a power filter 402 according to one or more examples. Figure 4 The transmitter 202B and Figure 3 The transmitter is the same as that of , but includes a power filter 402 . Figure 4 The transmitter 202B can be used as Figure 2 The transmitter 202 of FIG.

[0053] The power filter 402 includes an additional LC filter located between the H-bridge inverter 220 and the resonant tank circuit. The power filter 402 includes an inductor 404 (L f1 )、Inductor 406 (L f2 ) and capacitor 408 (C f ). Inductor 404 is coupled in series with capacitor 222 and one end is coupled between switches 302 and 306. Inductor 406 has a first end coupled between switches 304 and 308 and a second end coupled to ends of switches 332, 334, and 336. Capacitor 408 has a first end coupled between capacitor 222 and inductor 404 and a second end coupled to a second end of inductor 406.

[0054] The resonant frequency of the power filter 402 is much higher than the resonant frequency of the resonant tank circuit. The power filter 402 is included to apply only the fundamental switching frequency to the resonant tank circuit. Without the power filter 402, a square wave waveform including the fundamental frequency and odd harmonics is applied to the resonant tank circuit. The power filter 402 reduces high frequency electromagnetic (EM) radiation generated from the transmitter 202B.

[0055] Figure 5 is a circuit diagram of a transmitter 202C without a power filter according to one or more examples. Figure 5 The transmitter 202C is similar to Figure 2 The transmitter 202 can be used as Figure 2 The transmitter 202 of FIG.

[0056] As previously described, the controller 224 can calculate the coil power of the transmitter 202. The coil power can be used to calculate the power loss for detecting foreign objects. To this end, the controller 224 provides an input 250 to the first ADC channel to sample the capacitor voltage across the capacitor 222 (Cp). The coil current can be calculated based on the sampled capacitor voltage. Since the capacitor 222 is coupled in series with the transmitter coil 212, the current flowing through the capacitor 222 is the same as the coil current. The differential amplifier 502 is used to provide a capacitor measurement signal indicating the capacitor voltage potential difference across the capacitor 222. The differential amplifier 502 includes a first input terminal and a second input terminal electrically connected across the capacitor 222, and an output 506 coupled to the input 250 of the first ADC channel. In addition, the controller 224 also provides an input 252 to the second ADC channel to sample the coil voltage across the transmitter coil 212 (Lp). The differential amplifier 504 is used to provide a coil measurement signal indicating the coil voltage potential difference across the transmitter coil 212. The differential amplifier 504 includes first and second input terminals electrically connected across the transmitter coil 212 , and an output 508 coupled to the input 252 of the second ADC channel.

[0057] The calculation of the coil power based on the above-obtained signal (eg, Figures 8 to 12 , Fig.13 ). In one or more examples, the transmitter 202C can determine whether a foreign object is present without using conventional current sensors to measure current flowing through the transmitter coil 212 and / or estimate losses in the transmitter.

[0058] Thus, two (2) dedicated ADCs are provided that are capable of sampling the input at a very high rate. As a non-limiting example, approximately twenty (20) samples may be taken per 120kHz cycle, yielding a sampling frequency of 2.4MHz. The two dedicated ADCs may be triggered by the same signal so that high frequency sampling may be performed simultaneously. In one or more examples, this ensures that the sampling and processing delays are the same for both signals.

[0059] Figure 6 is a circuit diagram of a transmitter 202D with a power filter 402 according to one or more examples. Figure 6 The transmitter 202D and Figure 3 The transmitter is the same as that of FIG. 1 , but includes a power filter 402, as described with respect to FIG. Figure 4 described. Figure 6 The transmitter 202D can be used as Figure 2 The transmitter 202 of FIG.

[0060] Fig. 7A , Figure 7B and Figure 7C700A, 700B, and 700C are respective graphs of capacitor and coil voltage waveforms of a receiver under various load conditions. In respective graphs 700A, 700B, 700C, the y-axis represents voltage potential and the x-axis represents time.

[0061] Fig. 7A Graph 700A of exemplifies coil voltage potential waveform 704A and capacitor voltage potential waveform 706A, respectively, at a minimum load (0.75W) on the receiver. Also shown is a PWM signal 702 associated with coil voltage potential waveform 704A and capacitor voltage potential waveform 706A. Note that the two waveforms 704A and 706A are nearly out of phase (180 degree phase angle) with each other. The derivative of the capacitor voltage will produce a 90 degree phase angle, resulting in a large reactive power circulating in the LC component of the resonant tank circuit. The active power in this case is close to zero (0) because the current and voltage across the coil will exhibit a 90 degree phase angle.

[0062] Figure 7B Graph 700B of exemplifies coil voltage potential waveform 704B and capacitor voltage potential waveform 706B, respectively, at a medium load (7.5W) on the receiver. The medium load is about 50% of the rated load on the receiver. Also shown is a PWM signal 702 associated with coil voltage potential waveform 704B and capacitor voltage potential waveform 706B. Note that the phase angle of waveforms 704B and 706B is less than 180 degrees, as observed in a "no load" or minimum load condition. This results in a phase angle of about 60 degrees between the coil voltage and the coil current, and active power is supplied to the load. There is still a large circulating current that results in reactive power, which is not supplied to the load.

[0063] Figure 7C 700C of FIG. 700C illustrates coil voltage potential waveform 704C and capacitor voltage potential waveform 706C at full load (15W), respectively. PWM signal 702 associated with coil voltage potential waveform 704B and capacitor voltage potential waveform 706B is also shown. Note that the phase angle between waveforms 704C and 706C has been reduced (relative to the phase angle of waveforms 704B / 706B and 704A / 706A), and the amplitude of waveforms 704C and 706C has been increased (relative to the amplitude of waveforms 704B / 706B and 704A / 706A). This results in an increase in the active power supplied to the load. The phase angle between the coil voltage and the current is further reduced to about 45 degrees. Generally speaking, when the phase angle between the coil voltage and the current is zero (0), the maximum power is transmitted. In theory, when the load is only resistive, the phase angle between the coil voltage and the current is zero (0). However, this is not a feasible possibility because the receiver utilizes an inductive-resistive (LR) load.

[0064] Figures 8 to 12 is a flow chart of a detailed end-to-end method for determining coil power of a transmitter according to one or more examples. In one or more examples, the end-to-end method can be performed by a controller (e.g., a microcontroller such as a dsPIC microcontroller, but not limited thereto) using a direct memory access (DMA) module. In one or more examples, the end-to-end method for determining coil power can be used to determine power consumption for foreign object detection.

[0065] Figure 8 8 is a flow chart illustrating a method 800 for performing DMA initialization according to one or more examples. A large amount of data calculations can be performed on the Qi function. Since data is sampled at a very high frequency, the DMA module can be used to sample and store data independently of the processor computing power.

[0066] from Figure 8 Starting from the start block 802, two (2) DMA channels ( Figure 8 Step 804). Two (2) DMA inputs are selected and compared to the coil voltage (V coil ) and capacitor voltage (V cap )'s corresponding ADC channel ( Figure 8 Set the same DMA trigger for the coil voltage and capacitor voltage ( Figure 8 That is, the two DMA channels are triggered by the same trigger source (eg, software trigger source). A buffer having a buffer size is allocated to the corresponding DMA channel for storing the sampled data ( Figure 8 In one or more examples, the buffer size can vary from a single cycle of size twenty (20) to ten (10) cycles of size two hundred (200). Figure 8 The flowchart of ends at end block 812 .

[0067] Fig. 9 1 is a flow chart illustrating a method 900 of performing a data acquisition process according to one or more examples. In one or more examples, the data acquisition process can be a background DMA data acquisition process. In one or more examples, the method can be performed when a DMA channel is triggered by a software trigger.

[0068] from Fig. 9 Starting from the start block 902, the pointer is set to zero (0) ( Fig. 9 The coil voltage (V coil ) and capacitor voltage (V cap )sampling( Fig. 9 Step 906). Then increment the pointer ( Fig. 9 If the buffer is not yet full (e.g., Fig. 9 ), then repeat steps 906 and 908. In this way, the DMA module continuously triggers the coil voltage (V coil ) and capacitor voltage (V cap ) until the buffer is full. When the buffer is full, Fig. 9 The flowchart of ends at end block 912. In one or more examples, when the buffer is full, the DMA module generates an interrupt for an interrupt service routine (ISR) when the buffer is full (see, e.g., Fig.10 ).

[0069] Fig.10 1 is a flow chart illustrating a method 1000 for calculating coil current, coil voltage, and coil power according to one or more examples. In one or more examples, Fig.10 The method can be about Fig. 9 In one or more examples, the data stored by the DMA module is processed on a sample-by-sample basis to calculate active power as follows.

[0070] exist Fig.10 Starting from the start block 1002, the coil current (I coil ) based on the capacitor voltage (V cap ) to calculate ( Fig.10 Step 1004). Calculate the coil voltage (V coil ) to compensate for the delay ( Fig.10 The active power (i.e., coil power) is based on the coil current (I coil ) and coil voltage (V coil Then, the power average value within a time period (for example, 1 ms, but not limited thereto) is calculated. Fig.10 The flowchart of ends at end block 1012 .

[0071] The coil current can be calculated at each sample except the first one. The coil current can be calculated or derived by differentiating the capacitor voltage based on the following expression,

[0072]

[0073] The digital equivalent is

[0074]

[0075] Where C is the capacitor (V cap ) in Farads (F), and T samp is the sampling time in seconds. If the sampling period is fixed, C / T can be calculated in advancesamp and use it as a constant.

[0076] The calculation of the coil current results in an additional delay at each sample. To compensate for this delay, an average operation is performed on the coil voltage so that I coil and V coil The coil voltage (average value) can be calculated or derived based on the following expression:

[0077]

[0078] In at least some or many instances, if this step is omitted, the power calculation may be erroneous.

[0079] Fig.11 1 is a flow chart illustrating a method 1100 for performing power loss calculations according to one or more examples. Fig.11 Starting at the start block 1102, the transmitter loss (P tl )( Fig.11 Step 1104). Calculate the active power (P tx )( Fig.11 Step 1106). Obtain the receiver power (P rx )( Fig.11 Step 1108). Calculate the power loss (P loss )( Fig.11 Step 1110). If the power loss (P loss ) is greater than the power threshold (P thresh )( Fig.11 Step 1112), it can be determined that there is a foreign object ( Fig.11 Step 1114). Fig.11 The flowchart of ends at end block 1116 .

[0080] Active power is averaged over the entire interval by V coil_a and I coil The dot product is calculated as

[0081]

[0082] The dot product is usually calculated as a scalar given by

[0083]

[0084] Fig.12 1 is a flow chart illustrating a method 1200 for performing a power loss calculation flow chart when a receiver is placed on a transmitter according to one or more examples. The method 1200 begins at a start block 1202, where a coil voltage (V coil), in step 1206, the capacitor voltage (V cap ), in step 1208, the coil current (I coil ) and measuring or obtaining active power (P tx ) can be related to Fig.10 Steps 1212, 1214, 1216 and 1218 may be performed in the same or similar manner as described above with respect to steps 1004, 1106, 1008 and 1010. Fig.11 The same or similar manner as described above is performed. Fig.12 The flowchart of ends at end block 1220 .

[0085] Regarding step 1210, the transmitter active power through the coil is calculated using the equation given above. Regarding step 1212, the receiver transmits the power (P rx ). With respect to step 1214, the transmitter power loss is calculated at predetermined times (eg, typically every 1 ms in synchronization with the receiver). The power loss may be calculated as

[0086] P loss =P tx -P rx .

[0087] If P loss >P thresh , it indicates that there is a foreign object between the transmitter and the receiver because FO consumes power. If P loss <P thresh , the transmitted power is received by the receiver.

[0088] Fig.13 1 is a flow chart describing a method 1300 for determining coil power of a transmitter according to one or more examples. In one or more examples, the coil power can be used to calculate power loss for detecting foreign objects. In one or more examples, the method can be performed by a controller of a transmitter, wherein the transmitter has one or more induction coils and a series capacitor electrically connected in series with the one or more induction coils.

[0089] exist Fig.13 , obtaining a pre-capacitor voltage sample of the signal sampled via the first ADC channel ( Fig.13 The previous capacitor voltage sample of the signal indicates the previous capacitor voltage potential difference across the series capacitor. Then the current capacitor voltage sample of the signal sampled via the first ADC channel is obtained ( Fig.13The current capacitor voltage sample of the signal indicates a current capacitor voltage potential difference across the series capacitor. In one or more examples, the previous capacitor voltage sample and the current capacitor voltage sample are consecutive samples. The coil current is determined at least in part based on a rate of change between the previous capacitor voltage sample and the current capacitor voltage sample sampled via the first ADC channel ( Fig.13 In one or more specific examples of step 1306, the coil current is determined based at least in part on a ratio of a difference between a previous capacitor voltage sample and a current capacitor voltage sample over a time period between the previous capacitor voltage sample and the current capacitor voltage sample.

[0090] In one or more examples, the following steps 1308 and 1310 are performed substantially simultaneously with the just described steps 1302 and 1304. Obtain the previous coil voltage sample ( Fig.13 The previous coil voltage sample of the signal indicates the previous coil voltage potential difference across the one or more induction coils. Then, the current coil voltage sample of the signal sampled via the second ADC channel is obtained ( Fig.13 The current coil voltage sample of the signal indicates a current coil voltage potential difference across one or more induction coils. In one or more examples, the previous coil voltage sample and the current coil voltage sample are consecutive samples. The coil voltage (e.g., average value) is determined based at least in part on the previous coil voltage sample and the current coil voltage sample ( Fig.13 In one or more examples of step 1312, the coil voltage potential difference is determined based at least in part on an average of a previous coil voltage sample and a current coil voltage sample.

[0091] The coil power is then determined based at least in part on the determined coil current and the determined coil voltage. Fig.13 In one or more examples, the power loss is determined based at least in part on the determined coil power and a received power indicated by a communication received from another induction coil. In one or more examples, in response to determining that the power loss exceeds a predetermined threshold, it is determined that the foreign object is proximate to one or more induction coils.

[0092] Thus, according to one or more specific examples, two (2) separate but identical channels may be used to sample the coil voltage and the capacitor voltage at (e.g., substantially) exactly the same time. The coil current may be derived from the capacitor voltage, which may result in a phase lag in the current channel because two (2) consecutive samples are required to calculate the current value. In order to match the phase between the current channel and the voltage channel, the coil voltage is averaged with its previous value. Without such phase matching, the calculated dot product may be inaccurate, which may result in erroneous foreign object detection.

[0093] Those skilled in the art will appreciate that the functional elements (eg, functions, operations, actions, processes and / or methods) of the examples disclosed herein may be implemented in any suitable hardware, software, firmware, or combination thereof. Fig.14 Non-limiting examples of specific implementations of the functional elements disclosed herein are illustrated.In some examples, some or all of the functional elements disclosed herein may be performed by hardware specifically implemented to perform the functional elements.

[0094] Fig.14 1400 is a block diagram of a circuit 1400 that, in some examples, can be used to implement various functions, operations, actions, processes, and / or methods disclosed herein. The circuit 1400 includes one or more processors 1402 (sometimes referred to herein as "processors 1402") that are operably coupled to one or more data storage devices (sometimes referred to herein as "storage devices 1404"). The storage devices 1404 include machine executable code 1406 stored thereon, and the processor 1402 includes logic circuits 1408. The machine executable code 1406 includes information describing functional elements that can be implemented (e.g., executed) by the logic circuits 1408. The logic circuits 1408 are suitable for implementing (e.g., executing) the functional elements described by the machine executable code 1406. When the functional elements described by the machine executable code 1406 are executed, the circuit 1400 should be regarded as dedicated hardware for performing the functional elements disclosed herein. In some examples, processor 1402 may be configured to execute functional elements described by machine executable code 1406 sequentially, concurrently (eg, on one or more different hardware platforms), or in one or more parallel process flows.

[0095] When implemented by the logic circuit 1408 of the processor 1402, the machine executable code 1406 is used to adapt the processor 1402 to perform the operations of the examples disclosed herein. For example, the machine executable code 1406 may adapt the processor 1402 to perform Figure 8 Method 800, Fig. 9 Method 900, Fig.10 Method 1000, Fig.11 Method 1100, Fig.12 Method 1200 and / or Fig.13 For example, the machine executable code 1406 may cause the processor 1402 to execute at least a portion or all of the method 1300. Figure 2 Controller, Figure 5 The controller and / or Figure 6 As a specific non-limiting example, the machine executable code 1406 may cause the processor 1402 to determine the transmit power of the one or more induction coils in response to the capacitor voltage potential difference across the series capacitor and the coil voltage potential difference across the one or more induction coils. As another specific non-limiting example, the machine executable code 1406 may cause the processor 1402 to determine the power loss by subtracting the receiver power indicated by the receiver from the transmit power, and compare the power loss to a predetermined threshold to determine whether the foreign object is close to the one or more induction coils.

[0096] Processor 1402 may include a general-purpose processor, a special-purpose processor, a central processing unit (CPU), a microcontroller, a programmable logic controller (PLC), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, other programmable devices, or any combination thereof designed to perform the functions disclosed herein. When a general-purpose computer including a processor is to execute functional elements corresponding to a machine executable code 1406 (e.g., software code, firmware code, hardware description) associated with the examples of the present disclosure, the general-purpose computer is considered a special-purpose computer. It should be noted that a general-purpose processor (also referred to as a host processor or simply a host in this article) can be a microprocessor, but in an alternative, processor 1402 may include any conventional processor, controller, microcontroller, or state machine. Processor 1402 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0097] In some examples, storage device 1404 includes volatile data storage device (e.g., random access memory (RAM)), non-volatile data storage device (e.g., flash memory, hard disk drive, solid state drive, erasable programmable read-only memory (EPROM), etc.). In some examples, processor 1402 and storage device 1404 may be implemented as a single device (e.g., semiconductor device product, system on chip (SOC), etc.). In some examples, processor 1402 and storage device 1404 may be implemented as independent devices.

[0098] In some examples, machine executable code 1406 may include computer readable instructions (e.g., software code, firmware code). As a non-limiting example, the computer readable instructions may be stored by storage device 1404, directly accessed by processor 1402, and executed by processor 1402 using at least logic circuit 1408. Also as a non-limiting example, the computer readable instructions may be stored on storage device 1404, transferred to a memory device (not shown) for execution, and executed by processor 1402 using at least logic circuit 1408. Thus, in some examples, logic circuit 1408 includes logic circuit 1408 that can be configured in an electrically manner.

[0099] In some examples, machine executable code 1406 may describe hardware (e.g., circuits) to be implemented in logic circuit 1408 to perform a functional element. The hardware may be described at any of a variety of abstraction levels from low-level transistor layout to a high-level description language. At a high level of abstraction, a hardware description language (HDL) may be used, such as an IEEE standard hardware description language (HDL). As a non-limiting example, a VERILOG TM 、SYSTEMVERILOG TM or Very Large Scale Integration (VLSI) Hardware Description Language (VHDL TM ).

[0100] The HDL description may be converted into a description at any of a variety of other abstraction levels as desired. As a non-limiting example, the high-level description may be converted into a logic-level description, such as a register transfer language (RTL), a gate-level (GL) description, a layout-level description, or a mask-level description. As a non-limiting example, the micro-operations to be performed by the hardware logic circuits (e.g., gates, flip-flops, registers, but not limited thereto) of the logic circuit 1408 may be described in RTL and then converted into a GL description by a synthesis tool, and the GL description may be converted into a layout-level description by a placement and routing tool, which corresponds to the physical layout of an integrated circuit, discrete gate or transistor logic, discrete hardware components, or a combination thereof of a programmable logic device. Therefore, in some examples, the machine executable code 1406 may include an HDL, RTL, GL description, a mask-level description, other hardware descriptions, or any combination thereof.

[0101] In examples where the machine executable code 1406 includes a hardware description (at any level of abstraction), a system (not shown, but including the storage device 1404) may implement the hardware description described by the machine executable code 1406. As a non-limiting example, the processor 1402 may include a programmable logic device (e.g., an FPGA or a PLC), and the logic circuit 1408 may be electrically controlled to implement circuits corresponding to the hardware description into the logic circuit 1408. Also as a non-limiting example, the logic circuit 1408 may include hard-wired logic components manufactured by a manufacturing system (not shown, but including the storage device 1404) according to the hardware description of the machine executable code 1406.

[0102] Regardless of whether the machine executable code 1406 includes computer readable instructions or a hardware description, the logic circuit 1408 is suitable for performing the functional elements described by the machine executable code 1406 when implementing the functional elements of the machine executable code 1406. It should be noted that although the hardware description may not directly describe the functional elements, the hardware description indirectly describes the functional elements that the hardware elements described by the hardware description are capable of performing.

[0103] As used in this disclosure, the term "module" or "component" may refer to a specific hardware implementation for performing the actions of a module or component and / or a software object or software routine that may be stored on and / or executed by general-purpose hardware of a computing system (e.g., a computer-readable medium, a processing device, etc.). In some examples, the different components, modules, engines, and services described in this disclosure may be implemented as objects or processes executed on a computing system (e.g., as separate threads). Although some of the systems and methods described in this disclosure are generally described as being implemented in software (stored on and / or executed by general-purpose hardware), specific hardware implementations or combinations of software and specific hardware implementations are possible and contemplated.

[0104] As used in this disclosure, the term "combination" referring to a plurality of elements may include any combination of all elements or various subcombinations of certain elements. For example, the phrase "A, B, C, D, or a combination thereof" may refer to any one of A, B, C, or D; a combination of each of A, B, C, and D; and any subcombination of A, B, C, or D, such as A, B, and C; A, B, and D; A, C, and D; B, C, and D; A and B; A and C; A and D; B and C; B and D; or C and D.

[0105] The terms used in this disclosure, especially in the appended claims (e.g., the bodies of the appended claims) are generally intended to be “open” terms (e.g., the term “comprising” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “including” should be interpreted as “including but not limited to,” etc.).

[0106] Additionally, if a specific number of introduced claim recitations is intended, such intent will be expressly recited in the claim, and in the absence of such a recitation, no such intent is present. For example, as an aid to understanding, the following appended claims may contain the use of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that a claim recitation introduced by the indefinite article "a" or "an" will limit any particular claim containing such introduced claim recitation to an example containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and an indefinite article, such as "a" or "an" (e.g., "a" and / or "an" may be interpreted to mean "at least one" or "one or more"); the same is true when a definite article is used to introduce a claim recitation.

[0107] In addition, even if a specific number of an introduced claim recitation is explicitly recited, one skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the unmodified recitation "two recitations" means at least two recitations, or two or more recitations, in the absence of other modifying elements). Moreover, in those instances where a conventional phrase like "at least one of A, B, and C, etc." or "one or more of A, B, and C, etc." is used, such construction is generally intended to include A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together, etc.

[0108] Any separate word or phrase presenting two or more alternative terms, whether in the specification, claims or drawings, should be understood to include the possibility of one of the terms, any one of the terms, or both of the terms. For example, the phrase "A or B" should be understood to include the possibility of "A" or "B" or "A and B".

[0109] Additional non-limiting embodiments of the present disclosure include:

[0110] Embodiment 1: A device, comprising: one or more induction coils, the one or more induction coils being wirelessly coupled to another induction coil; a series capacitor, the series capacitor being electrically connected in series with the one or more induction coils; and a controller, the controller being configured to: determine a coil current flowing through the one or more induction coils in response to a capacitor voltage potential difference across the series capacitor; and determine a coil power in response to the determined coil current and the coil voltage potential difference across the one or more induction coils.

[0111] Embodiment 2: The apparatus of embodiment 1, wherein the controller is configured to determine the power loss in response to the determined coil power and a received power indicated by a communication received from the another induction coil.

[0112] Embodiment 3: The apparatus of any one of Embodiments 1 and 2, wherein the controller is configured to determine that a foreign object is proximate to the one or more induction coils in response to determining that the power loss exceeds a predetermined threshold.

[0113] Embodiment 4: A device according to any one of embodiments 1 to 3, wherein the device comprises a differential amplifier, wherein the differential amplifier comprises a first input terminal and a second input terminal electrically connected across the series capacitor, and wherein the differential amplifier provides a capacitor measurement signal indicating a voltage potential difference of the capacitor to the controller.

[0114] Embodiment 5: According to the device described in any one of embodiments 1 to 4, the device includes a differential amplifier, the differential amplifier includes a first input terminal and a second input terminal electrically connected at both ends of the one or more induction coils, and the differential amplifier provides a coil measurement signal indicating the voltage potential difference of the coils to the controller.

[0115] Embodiment 6: The apparatus of any one of embodiments 1 to 5, wherein the controller is configured to determine the coil current in response to the product of the capacitance of the series capacitor and the rate of change of the capacitor voltage potential difference.

[0116] Embodiment 7: An apparatus according to any one of embodiments 1 to 6, wherein the controller is used to determine the coil current in response to the product between the capacitance of the series capacitor and the following item: the ratio of the difference between a current sample indicating the capacitor voltage potential difference and a previous sample indicating the capacitor voltage potential difference to the time period between the current sample and the previous sample.

[0117] Embodiment 8: The apparatus of any one of Embodiments 1 to 7, wherein the controller is configured to determine the coil voltage potential difference by averaging a current sample of the coil voltage potential difference with a previous sample of the coil voltage potential difference.

[0118] Embodiment 9: The apparatus of any one of Embodiments 1 to 8, wherein the controller is configured to sample and store data indicative of the capacitor voltage potential difference and the coil voltage potential difference using direct memory access (DMA).

[0119] Embodiment 10: The apparatus according to any one of embodiments 1 to 9, wherein the controller comprises two DMA channels, a first of the two DMA channels being used for the capacitor voltage potential difference, and a second of the two DMA channels being used for the coil voltage potential difference.

[0120] Embodiment 11: A method, the method comprising: at a controller of a transmitter including one or more induction coils and a series capacitor electrically connected in series with the one or more induction coils, determining a coil current based at least in part on a rate of change between a previous capacitor voltage sample and a current capacitor voltage sample sampled via a first analog-to-digital converter (ADC) channel, the previous capacitor voltage sample and the current capacitor voltage sample indicating a previous capacitor voltage potential difference and a current capacitor voltage potential difference across the series capacitor; determining a coil voltage based at least in part on a previous coil voltage sample and a current coil voltage sample sampled via a second ADC channel, the previous coil voltage sample and the current coil voltage sample indicating a previous coil voltage potential difference and a current coil voltage potential difference across the one or more induction coils; and determining a coil power based at least in part on the determined coil current and the determined coil voltage.

[0121] Embodiment 12: The method of Embodiment 11, wherein determining the coil voltage comprises determining the coil voltage based at least in part on an average of the previous coil voltage sample and the current coil voltage sample.

[0122] Embodiment 13: A method according to any one of embodiments 11 and 12, wherein determining the coil current is based at least in part on the ratio of the difference between the previous capacitor voltage sample and the current capacitor voltage sample and the time period between the previous capacitor voltage sample and the current capacitor voltage sample.

[0123] Embodiment 14: A method according to any one of Embodiments 11 to 13, wherein the previous capacitor voltage sample and the current capacitor voltage sample include continuous samples, the previous coil voltage sample and the current coil voltage sample include continuous samples, and the previous coil voltage sample and the current coil voltage sample are sampled at substantially the same time as the previous capacitor voltage sample and the current capacitor voltage sample.

[0124] Embodiment 15: A method according to any one of embodiments 11 to 14, wherein the one or more induction coils are used to wirelessly couple with another induction coil, the method comprising: determining, at the controller, a power loss based at least in part on a determined coil power and a received power indicated by a communication received from the other induction coil; and determining that a foreign object is close to the one or more induction coils in response to determining that the power loss exceeds a predetermined threshold.

[0125] Embodiment 16: A device, comprising: one or more induction coils, the one or more induction coils being wirelessly coupled to another induction coil; a series capacitor, the series capacitor being electrically connected in series with the one or more induction coils; and a controller, the controller being configured to: determine a coil current based at least in part on a rate of change between a previous capacitor voltage sample and a current capacitor voltage sample sampled via a first analog-to-digital converter (ADC) channel, the previous capacitor voltage sample and the current capacitor voltage sample indicating a previous capacitor voltage potential difference and a current capacitor voltage potential difference across the series capacitor; determine a coil voltage based at least in part on a previous coil voltage sample and a current coil voltage sample sampled via a second ADC channel, the previous coil voltage sample and the current coil voltage sample indicating a previous coil voltage potential difference and a current coil voltage potential difference across the one or more induction coils; and determine a coil power based at least in part on the determined coil current and the determined coil voltage.

[0126] Embodiment 17: The apparatus of Embodiment 16, wherein the controller is configured to determine the coil voltage based at least in part on an average of the previous coil voltage sample and the current coil voltage sample.

[0127] Embodiment 18: A device according to any one of Embodiments 16 and 17, wherein the controller is used to determine the coil current based on the ratio of the difference between the previous capacitor voltage sample and the current capacitor voltage sample and the time period between the previous capacitor voltage sample and the current capacitor voltage sample.

[0128] Embodiment 19: The apparatus of any one of Embodiments 16 to 18, wherein the controller is configured to determine the power loss based at least in part on the determined coil power and a received power indicated by a communication received from the another induction coil.

[0129] Embodiment 20: The apparatus of any one of Embodiments 16 to 19, wherein the controller is configured to determine that a foreign object is proximate to the one or more induction coils in response to determining that the power loss exceeds a predetermined threshold.

[0130] Embodiment 21: A method, the method comprising: obtaining a previous capacitor voltage sample of a signal sampled via a first analog-to-digital converter (ADC) channel, the previous capacitor voltage sample of the signal indicating a previous capacitor voltage potential difference across a series capacitor electrically connected in series with one or more induction coils of a transmitter for wireless power transmission; obtaining a current capacitor voltage sample of the signal sampled via the first ADC channel, the current capacitor voltage sample of the signal indicating a current capacitor voltage potential difference across the series capacitor; obtaining a previous coil voltage sample of the signal sampled via a second ADC channel, the previous coil voltage sample of the signal indicating a previous coil voltage potential difference across the one or more induction coils; obtaining a current coil voltage sample of the signal sampled via the second ADC channel, the current coil voltage sample of the signal indicating a current coil voltage potential difference across the one or more induction coils; determining a coil current based at least in part on a rate of change between the previous capacitor voltage sample sampled via the first ADC channel and the current capacitor voltage sample; determining a coil voltage based at least in part on an average of the previous coil voltage sample and the current coil voltage sample; and determining a coil power in response to the determined coil current and the determined coil voltage.

[0131] Although the present disclosure describes the present invention with respect to certain illustrative examples, those of ordinary skill in the art will recognize and understand that the present invention is not so limited. Instead, many additions, deletions, and modifications may be made to the illustrative examples and the examples described without departing from the scope of the present invention as claimed below and its legal equivalents. In addition, features from one example may be combined with features of another example while still being included within the scope of the present invention as contemplated by the inventor.

Claims

1. A device, comprising: one or more induction coils wirelessly coupled to another induction coil; a series capacitor electrically connected in series with the one or more induction coils; as well as A controller, the controller being configured to: determining a coil current flowing through the one or more induction coils in response to a capacitor voltage potential difference across the series capacitor; as well as A coil power is determined in response to the determined coil current and a coil voltage potential difference across the one or more induction coils.

2. The apparatus of claim 1, wherein the controller is operative to determine the power loss in response to the determined coil power and a received power indicated by a communication received from the other induction coil. 3 . The apparatus of claim 2 , wherein the controller is operative to determine that a foreign object is proximate to the one or more induction coils in response to determining that the power loss exceeds a predetermined threshold.

4. The apparatus of claim 1 , comprising a differential amplifier including a first input terminal and a second input terminal electrically connected across the series capacitor, the differential amplifier providing a capacitor measurement signal indicative of a voltage potential difference between the capacitors to the controller.

5. The apparatus of claim 1 , comprising a differential amplifier including a first input terminal and a second input terminal electrically connected across the one or more induction coils, the differential amplifier providing a coil measurement signal indicative of a voltage potential difference between the coils to the controller.

6. The apparatus of claim 1, wherein the controller is operative to determine the coil current in response to a product of a capacitance of the series capacitor and a rate of change of a voltage potential difference of the capacitor.

7. The apparatus of claim 1 , wherein the controller is operative to determine the coil current in response to a product of the capacitance of the series capacitor and: a ratio of a difference between a current sample indicating a voltage potential difference of the capacitor and a previous sample indicating a voltage potential difference of the capacitor to a time period between the current sample and the previous sample.

8. The apparatus of claim 1, wherein the controller is to determine the coil voltage potential difference by averaging a current sample of the coil voltage potential difference with a previous sample of the coil voltage potential difference.

9. The apparatus of claim 1, wherein the controller is configured to sample and store data indicative of the capacitor voltage potential difference and the coil voltage potential difference using direct memory access (DMA).

10. The apparatus of claim 9, wherein the controller comprises two DMA channels, a first of the two DMA channels for the capacitor voltage potential difference, and a second of the two DMA channels for the coil voltage potential difference.

11. A method comprising: At a controller of a transmitter including one or more induction coils and a series capacitor electrically connected in series with the one or more induction coils, determining a coil current based at least in part on a rate of change between a previous capacitor voltage sample and a current capacitor voltage sample sampled via a first analog-to-digital converter (ADC) channel, the previous capacitor voltage sample and the current capacitor voltage sample indicating a previous capacitor voltage potential difference and a current capacitor voltage potential difference across the series capacitor; determining a coil voltage based at least in part on a previous coil voltage sample and a current coil voltage sample sampled via a second ADC channel, the previous coil voltage sample and the current coil voltage sample indicating a previous coil voltage potential difference and a current coil voltage potential difference across the one or more induction coils; and A coil power is determined based at least in part on the determined coil current and the determined coil voltage. 12 . The method of claim 11 , wherein determining the coil voltage comprises determining the coil voltage based at least in part on an average of the previous-coil voltage sample and the current coil voltage sample.

13. The method of claim 11, wherein determining the coil current is based at least in part on a ratio of a difference between the previous capacitor voltage sample and the current capacitor voltage sample and a time period between the previous capacitor voltage sample and the current capacitor voltage sample.

14. The method of claim 11, wherein the previous capacitor voltage sample and the current capacitor voltage sample comprise consecutive samples, the previous coil voltage sample and the current coil voltage sample comprise consecutive samples, and the previous coil voltage sample and the current coil voltage sample are sampled at substantially the same time as the previous capacitor voltage sample and the current capacitor voltage sample.

15. The method of claim 11, wherein the one or more induction coils are configured to wirelessly couple with another induction coil, the method comprising: At the controller, determining a power loss based at least in part on the determined coil power and a received power indicated by a communication received from the other induction coil; as well as A foreign object is determined to be proximate to the one or more induction coils in response to determining that the power loss exceeds a predetermined threshold.

16. A device, comprising: one or more induction coils wirelessly coupled to another induction coil; a series capacitor electrically connected in series with the one or more induction coils; as well as A controller, the controller being configured to: determining a coil current based at least in part on a rate of change between a previous capacitor voltage sample and a current capacitor voltage sample sampled via a first analog-to-digital converter (ADC) channel, the previous capacitor voltage sample and the current capacitor voltage sample indicating a previous capacitor voltage potential difference and a current capacitor voltage potential difference across the series capacitor; determining a coil voltage based at least in part on a previous coil voltage sample and a current coil voltage sample sampled via a second ADC channel, the previous coil voltage sample and the current coil voltage sample indicating a previous coil voltage potential difference and a current coil voltage potential difference across the one or more induction coils; and A coil power is determined based at least in part on the determined coil current and the determined coil voltage.

17. The apparatus of claim 16, wherein the controller is operative to determine the coil voltage based at least in part on an average of the previous coil voltage sample and the current coil voltage sample.

18. The apparatus of claim 16, wherein the controller is to determine the coil current based on a ratio of a difference between the previous capacitor voltage sample and the current capacitor voltage sample and a time period between the previous capacitor voltage sample and the current capacitor voltage sample.

19. The apparatus of claim 16, wherein the controller is configured to: The power loss is determined based at least in part on the determined coil power and a received power indicated by a communication received from the other induction coil.

20. The apparatus of claim 19, wherein the controller is configured to: A foreign object is determined to be proximate to the one or more induction coils in response to determining that the power loss exceeds a predetermined threshold.

21. A method comprising: obtaining a previous capacitor voltage sample of a signal sampled via a first analog-to-digital converter (ADC) channel, the previous capacitor voltage sample of the signal indicating a previous capacitor voltage potential difference across a series capacitor electrically connected in series with one or more inductive coils of a transmitter for wireless power transmission; obtaining a current capacitor voltage sample of a signal sampled via the first ADC channel, the current capacitor voltage sample of the signal indicating a current capacitor voltage potential difference across the series capacitor; obtaining a previous coil voltage sample of a signal sampled via a second ADC channel, the previous-coil voltage sample of the signal indicating a previous coil voltage potential difference across the one or more induction coils; obtaining a current coil voltage sample of a signal sampled via the second ADC channel, the current coil voltage sample of the signal indicating a current coil voltage potential difference across the one or more induction coils; determining a coil current based at least in part on a rate of change between the previous capacitor voltage sample and the current capacitor voltage sample sampled via the first ADC channel; determining a coil voltage based at least in part on an average of the previous coil voltage sample and the current coil voltage sample; as well as A coil power is determined in response to the determined coil current and the determined coil voltage.

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