Object detection during wireless charging

Abstract

This invention provides a method and system that can reliably detect foreign objects on a wireless charging pad under various temperature conditions. [Solution] An object detector 300 for reliably detecting foreign objects on a wireless charging pad utilizes a set of induction coils 202 contained in a resonant tank and excites the resonant tank using a signal in a frequency range that includes or is close to the nominal resonant frequency of the resonant tank. The object detector 300 detects metallic objects based on the increase in the resistance of the induction coils 202 and the decrease in the inductance of the induction coils 202. The object detector 300 accurately detects foreign objects by distinguishing between changes in frequency and amplitude caused by temperature and those caused by foreign objects by analyzing the shift and / or distribution in the resonant frequency and output amplitude (e.g., output voltage peak).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to wireless charging technology. More specifically, embodiments of the present disclosure relate to detecting an object on a wireless charging device under various temperatures.

BACKGROUND ART

[0002] Wireless charging devices can be used to wirelessly charge vehicles such as electric vehicles equipped with battery packs. A wireless charging device can wirelessly transmit power received from an external source such as a grid or a solar cell to an electric vehicle (for example, via induction). To charge an electric vehicle, the wireless charging device can be arranged under the electric vehicle. Energy is transmitted wirelessly through air in the form of a magnetic field. To ensure the safety of wireless charging, it is desirable to detect objects on or near the surface of a wireless charging device (for example, a wireless charging pad).

SUMMARY OF THE INVENTION

[0003] The systems, methods, and devices of the present disclosure each have several innovative embodiments, and not all of the desirable attributes disclosed herein are solely responsible for only one of them. The details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the following description.

[0004] In some aspects, the technology described in the present specification relates to a wireless charging system, which includes a resonant tank including a coil, an exciter electrically connected to the resonant tank, and a processing circuit in communication with at least the exciter, wherein the processing circuit is configured to cause the exciter to excite the resonant tank, determine a first parameter indicative of the inductance of the excited coil and a second parameter indicative of the resistance of the coil associated with the excited coil, and detect an object based on the first parameter indicative of a decrease in inductance and the second parameter indicative of an increase in resistance, compared to a case where no object is present.

[0005] In some embodiments, the technology described herein relates to a wireless charging system, wherein a first parameter includes the resonant frequency of the resonant tank, and a second parameter includes the amplitude of the output voltage of the resonant tank.

[0006] In some embodiments, the technology described herein relates to a wireless charging system, wherein a processing circuit is configured to excite a resonant tank by applying at least sequentially a plurality of first signals to the resonant tank, each of the plurality of first signals being generated based on a frequency among a plurality of frequencies, and the processing circuit is configured to determine a first parameter and a second parameter by at least measuring the output amplitude at the output terminal of the resonant tank associated with each of the plurality of first signals applied to the resonant tank in order to obtain a plurality of first output amplitudes, and selecting one of a plurality of frequencies corresponding to a first maximum output amplitude among the plurality of first output amplitudes as the first resonant frequency of the resonant tank, wherein the first parameter includes a first resonant frequency and the second parameter includes a first maximum output amplitude.

[0007] In some embodiments, the techniques described herein relate to a wireless charging system, wherein the step of detecting an object includes determining that a first point in a two-dimensional plane, representing a first resonant frequency and a first maximum output amplitude, lies on a first side of a distribution boundary in the two-dimensional plane, and, in response to the determination that the first point lies on a first side of a distribution boundary in the two-dimensional plane, generating a first processing result indicating that an object is present on the coil.

[0008] In some embodiments, the technology described herein relates to a wireless charging system, wherein the processing circuit is configured to cause an exciter to sequentially apply a second plurality of signals to a resonant tank, each of the second plurality of signals being generated based on a frequency among a plurality of frequencies, and to obtain a second plurality of output amplitudes, by measuring the output amplitude at the output terminal of the resonant tank as each of the second plurality of signals is applied to the resonant tank, by selecting one of a plurality of frequencies corresponding to a second maximum output amplitude among the second plurality of output amplitudes as the second resonant frequency of the resonant tank, by determining that a second point in a two-dimensional plane representing the second resonant frequency and the second maximum output amplitude is on the second side of the distribution boundary in the two-dimensional plane, and in response to the determination that the second point is on the second side of the distribution boundary in the two-dimensional plane, generate a second processing result indicating that there is no object in the coil.

[0009] In some embodiments, the technology described herein relates to a wireless charging system in which a first temperature associated with the resonant tank during the application of a first plurality of signals to the resonant tank is different from a second temperature associated with the resonant tank during the application of a second plurality of signals to the resonant tank.

[0010] In some embodiments, the technology described herein relates to a wireless charging system, wherein the processing circuit is configured to cause a wireless charging pad to initiate inductive power transmission to another wireless charging pad based on a second processing result.

[0011] In some embodiments, the technology described herein relates to a wireless charging system in which the distribution boundary includes a line in a two-dimensional plane, with a first side of the distribution boundary being below the distribution boundary and a second side of the distribution boundary being above the distribution boundary.

[0012] In some embodiments, the technology described herein relates to a wireless charging system, wherein the processing circuit is configured to define a distribution boundary based on the distribution of a plurality of points in a two-dimensional plane, each of which represents the resonant frequency of a resonant tank and the maximum output amplitude at the output terminal under corresponding operating conditions related to a resonant tank in which no object is present on the coil.

[0013] In some embodiments, the technology described herein relates to a wireless charging system, where the output amplitude at the output terminal includes the voltage at the output terminal.

[0014] In some embodiments, the technology described herein relates to a wireless charging system, wherein the multiple frequencies include or are close to the nominal resonant frequency of the resonant tank.

[0015] In some embodiments, the technology described herein relates to a wireless charging system, wherein the object is a metallic object.

[0016] In some embodiments, the techniques described herein relate to a method for detecting an object for wireless charging, the method comprising: causing an exciter to excite a resonant tank of a wireless charging pad, the resonant tank comprising a coil; determining a first parameter indicating the inductance of the coil and a second parameter indicating the resistance of the coil associated with the excited coil; and detecting an object based on the first parameter indicating a decrease in inductance and the second parameter indicating an increase in resistance compared to the absence of an object.

[0017] In some embodiments, the techniques described herein relate to methods, wherein the step of exciting a resonant tank includes the step of sequentially applying a plurality of first signals to the resonant tank, each of the plurality of first signals being generated based on a frequency among a plurality of frequencies, and the step of determining a first parameter and a second parameter includes the step of measuring the output amplitude at the output terminal of the resonant tank when each of the plurality of first signals is applied to the resonant tank in order to obtain a plurality of first output amplitudes, and the step of selecting one of a plurality of frequencies corresponding to a first maximum output amplitude among the plurality of first output amplitudes as the first resonant frequency of the resonant tank, wherein the first parameter includes the first resonant frequency, and the second parameter includes the first maximum output amplitude.

[0018] In some embodiments, the techniques described herein relate to methods, the steps of detecting an object include determining that a first point in a two-dimensional plane, representing a first resonant frequency and a first maximum output amplitude, lies on a first side of a distribution boundary in the two-dimensional plane, and, in response to the determination that the first point lies on a first side of a distribution boundary in the two-dimensional plane, generating a first processing result indicating that an object is present on a wireless charging pad.

[0019] In some embodiments, the technique described herein relates to a method, the method further comprising: causing an exciter to sequentially apply a second plurality of signals to a resonant tank, each of the second plurality of signals being generated based on a frequency among a plurality of frequencies; measuring the output amplitude at the output terminal of a resonant tank in order to apply each of the second plurality of signals to the resonant tank and obtain a second plurality of output amplitudes; selecting one of a plurality of frequencies corresponding to a second maximum output amplitude among the second plurality of output amplitudes as the second resonant frequency of the resonant tank; determining that a second point in a two-dimensional plane representing the second resonant frequency and the second maximum output amplitude lies on a second side of a distribution boundary in the two-dimensional plane; and generating a second processing result indicating that there is no object on the wireless charging pad in response to the determination that the second point lies on a second side of a distribution boundary in the two-dimensional plane.

[0020] In some embodiments, the techniques described herein relate to methods, the methods being performed while a wireless charging pad is not inductively transmitting power to another wireless charging pad.

[0021] In some embodiments, the technology described herein relates to a method for detecting an object for wireless charging, the method comprising the steps of: exciting a resonant tank of a wireless charging pad, the resonant tank comprising a coil; and detecting an object on the wireless charging pad based on the fact that the resistance of the coil increases and the inductance of the coil decreases while the resonant tank is being excited.

[0022] In some aspects, the techniques described in this specification relate to a method, wherein exciting a resonant tank comprises sequentially applying a first plurality of signals to the resonant tank, each of the first plurality of signals being generated based on a frequency of a plurality of frequencies.

[0023] In some aspects, the techniques described in this specification relate to a method, wherein detecting an object comprises measuring an output amplitude at an output terminal of the resonant tank associated with each of a first plurality of signals applied to the resonant tank to obtain a first plurality of output amplitudes, selecting one of the plurality of frequencies corresponding to a first maximum output amplitude among the first plurality of output amplitudes as a first resonant frequency of the resonant tank, determining that a first point in a two-dimensional plane representing the first resonant frequency and the first maximum output amplitude is on a first side of a distribution boundary in the two-dimensional plane, and in response to determining that the first point is on the first side of the distribution boundary in the two-dimensional plane, generating a first processing result indicating that the object is present on a wireless charging pad.

[0024] Various combinations of the features, embodiments, and aspects enumerated above and below are also disclosed and contemplated by the present disclosure.

[0025] Additional embodiments of the present disclosure are described below with reference to the appended claims, which may serve as an additional overview of the present disclosure. [Brief Description of the Drawings]

[0026] Throughout the drawings, reference numerals are reused to indicate correspondence between referenced elements. The drawings are provided to illustrate examples of the subject matter described in the present specification, and are not intended to limit the scope thereof.

[0027] Embodiments of the present disclosure are described with reference to the accompanying drawings, in which like reference numerals refer to like elements.

[0028] [Figure 1]shows a perspective view of an exemplary wireless charging pad in which embodiments of the present disclosure may be implemented.

[0029] [Figure 2] is a top view of the wireless charging pad of Figure 1, illustrating an enlarged view of a particular portion of the wireless charging pad, in accordance with some embodiments of the present disclosure.

[0030] [Figure 3] is an exemplary schematic diagram of the components of an object detector for detecting one or more foreign objects on a wireless charging pad (e.g., the wireless charging pad of Figure 1), in accordance with some embodiments of the present disclosure.

[0031] [Figure 4] shows an exemplary curve of the output amplitude at the output terminal of the resonant tank of the wireless charging pad with respect to the corresponding frequency of the signal used to excite the resonant tank, in accordance with some embodiments of the present disclosure.

[0032] [Figure 5] shows an exemplary distribution graph of the maximum output amplitude at the output terminal of the resonant tank of the wireless charging pad with respect to the corresponding resonant frequency of the resonant tank, in accordance with some embodiments of the present disclosure. DETAILED DESCRIPTION

[0033] The following descriptions of specific embodiments present various descriptions of those specific embodiments. However, the innovations described herein can be implemented in numerous different ways, for example, as defined and encompassed by the claims. In this description, similar reference numbers refer to drawings in which the terms may indicate identical or functionally similar elements. It will be understood that the elements shown in the drawings are not necessarily drawn to scale. Furthermore, it will be understood that a particular embodiment may include more elements and / or subsets of elements shown in the drawings than those shown. Furthermore, some embodiments may incorporate any suitable combination of features from two or more drawings. Any suitable principles and advantages of the embodiments disclosed herein can be implemented together with one another.

[0034] Generally speaking, one or more embodiments of the present disclosure relate to detecting objects on or near the surface of a wireless charging device (e.g., a wireless charging pad) to mitigate undesirable heat generation that could lead to undesirable consequences (e.g., ignition). More specifically, some embodiments of the present disclosure relate to methods and systems that can reliably detect foreign objects on a wireless charging pad at a variety of temperatures. In some embodiments, the object detector can utilize a set of induction coils contained in a resonant tank, and the resonant tank can be excited using a signal in a frequency range including or close to the nominal resonant frequency of the resonant tank (e.g., using one or more half-bridge circuits). The object detector can detect metallic objects based on an increase in the resistance of the coil and a decrease in the inductance of the coil. This can be distinguished from temperature changes when no metallic object is present, and an increase in temperature can increase both the inductance and resistance of the coil. By analyzing the shift and / or distribution in the resonant frequency and output amplitude (e.g., output voltage peak), the object detector can accurately detect foreign objects by distinguishing between frequency and amplitude changes attributable to temperature and those attributable to foreign objects. Such an analysis can take into account shifts in both the inductance and resistance of the coil.

[0035] In the field of wireless charging technology, the detection of foreign objects (e.g., metallic objects) on or near the charging surface can be important. Objects on the charging surface may be heated by induced eddy currents during the charging process, which can lead to thermal events or safety hazards. For example, during inductive charging, the magnetic field generated by the wireless charging pad can cause unintended heating of foreign objects placed on the wireless charging pad. Unintended heating can pose a significant risk to both the wireless charging pad, the surrounding environment, and / or the user.

[0036] Specific solutions for detecting metallic objects in wireless charging systems may include fixed-frequency detection techniques, which typically involve monitoring changes in the output amplitude of a resonant tank circuit to identify the presence of a metallic object. However, such techniques may not be reliable or robust to changes in ambient temperature and / or device temperature. More specifically, temperature changes in or around the wireless charging pad can cause changes in the inductance and resistance of the induction coil within the wireless charging pad. Changes in inductance and resistance due to temperature changes can lead to false detections or missed detections in metallic object detection. The lack of detection robustness to temperature changes in such solutions can limit their effectiveness and reliability, especially in environments with significant temperature fluctuations.

[0037] To address at least some of the above-mentioned problems, some embodiments of the present disclosure disclose an object detector that can distinguish between changes in the inductance and resistance of an induction coil caused by foreign matter and changes in the inductance and resistance of an induction coil caused by temperature, thereby enabling reliable detection of the presence of foreign matter on a charging surface.

[0038] In some embodiments, the object detector may include a set of induction coils (e.g., 50, 60, 70, 80, 90, and / or other numbers of induction coils) each contained within a resonant tank (e.g., an RLC resonant tank). The object detector may excite the resonant tank using a signal in a frequency range including or close to the nominal resonant frequency of the resonant tank (e.g., via frequency sweep) and capture the output amplitude (e.g., output voltage) of the resonant tank at various frequencies to acquire resulting data. The resulting data may include multiple pairs of output amplitudes of the resonant tank and corresponding frequencies. The resulting data may be fitted to a curve (e.g., a quadratic curve) to accurately identify the resonant frequency of the resonant tank and the maximum output amplitude of the resonant tank. By analyzing the shift or change in the resonant frequency and the output amplitude (e.g., determining significant deviations from the linear trend formed by the resonant frequency and voltage peak), the object detector can accurately detect foreign objects by distinguishing between changes in resonant frequency and output amplitude caused by temperature and those caused by foreign objects (e.g., metallic foreign objects).

[0039] In some embodiments, the object detector or wireless charging system may include a resonant tank having a coil, an exciter electrically connected to the resonant tank, and a processing circuit that communicates with at least the exciter. The processing circuit can control the exciter to sequentially apply a plurality of signals to the resonant tank, each of which is generated based on a frequency in a frequency range (e.g., using frequency sweeps that extend below and above the nominal resonant frequency of the resonant tank). While each of the plurality of signals is applied, the processing circuit can measure the output amplitude at the output terminal of the resonant tank to obtain a plurality of output amplitudes. The processing circuit can identify the maximum output amplitude among the plurality of output amplitudes and select a frequency within the frequency range corresponding to the maximum output amplitude as the resonant frequency of the resonant tank. The processing circuit can then map the resonant frequency and the maximum output amplitude to a point in a two-dimensional plane (e.g., a plane with the resonant frequency as one axis and the maximum output amplitude as the other axis), determine that the point lies on one side of a distribution boundary in the two-dimensional plane (e.g., below a distribution boundary that separates the temperature change distribution from the object presence distribution), and accordingly generate a processing result indicating the presence of an object on the coil.

[0040] Advantageously, by being able to distinguish between temperature-induced and foreign-object-induced changes in resonant frequency and output amplitude, the object detector can reduce false detections or missed detections in object detection while operating under ambient conditions and / or temperature variations associated with the wireless charging device. The ability to distinguish between temperature-induced and foreign-object-induced changes further enables the object detector to detect foreign objects over a temperature range and immediately after a wireless charging session has stopped (e.g., when the wireless charging pad is still warmer than before the wireless charging session started) or ended. These capabilities may be important for ensuring safety and mitigating or preventing thermal events when charging is interrupted or completed, for example, because a biological object may be detected near the wireless charging pad, and foreign objects may be introduced into the wireless charging pad after wireless charging has been stopped. Furthermore, the object detection method performed by the object detector can be performed without continuous execution, operation, or manipulation, and the object detector can be performed without startup calibration.

[0041] While the embodiments of this disclosure describe exemplary components, interactions, and routines, those skilled in the art will understand that one or more embodiments of this disclosure may be implemented according to various environments, system architectures, customer computing device architectures, etc. More specifically, embodiments of this application may be applicable under different contexts (e.g., associated with grounding pads, vehicle pads, and wireless charging pads for charging vehicles or other devices via wireless charging). Similarly, references to specific devices, such as wireless charging pads, should be considered general references and are not intended to provide additional meaning or configurations for individual wireless charging pads. Furthermore, the examples and exemplary configurations are not intended to be limiting and should not be construed as limiting the scope of this disclosure. Furthermore, the examples are intended to be illustrative in nature and should not be construed as limiting.

[0042] Figure 1 shows a perspective view of an exemplary wireless charging pad 100 (e.g., a grounding pad) that can carry out embodiments of the present disclosure. As shown in Figure 1, the wireless charging pad 100 may include at least a mini-coil board 102 and a housing 104. Although not shown in Figure 1, in some examples the mini-coil board 102 may be a printed circuit board (PCB) housed and enclosed within the housing 104. For example, the mini-coil board 102 may be located below the top of the housing 104 (e.g., a plate, sheet, or plastic sheet) and may be covered by it. As shown in Figure 1, above the mini-coil board 102 there is a foreign object 190 which may be a metallic object (e.g., a nail, coin, etc., as shown). The foreign object 190 is located on top of the housing 104 and can be directly contacted.

[0043] Although not readily apparent in Figure 1, in some examples the wireless charging pad 100 may include a charging coil (not shown in Figure 1) and an object detector (e.g., an object detector 300 described with reference to Figure 3). For example, the charging coil and object detector may be located inside the housing 104 (e.g., below the top of the housing 104). The charging coil may generate a magnetic field from an input current supplied from an energy source (e.g., a junction box not shown in Figure 1) to charge an electric vehicle by enabling wireless charging, such as induction-based wireless charging. In some examples the wireless charging pad 100 may be configured to charge the battery pack of an electric vehicle, which may have a nominal voltage greater than 200 volts (e.g., a nominal voltage of about 350 or 355 volts) and a maximum voltage of 400 volts. In some examples the wireless charging pad 100 may be configured to supply 800 volts of DC power. In some embodiments the wireless charging pad 100 may supply voltages in the range of about 200 volts to 800 volts.

[0044] In some examples, the object detector may include a set of induction coils contained within a resonant tank, and the resonant tank can be excited using a signal in a frequency range including or close to the nominal resonant frequency of the resonant tank (e.g., using one or more half-bridge circuits). By analyzing the shift and / or distribution of the resonant frequency and the output amplitude (e.g., output voltage peak), the object detector can accurately detect the foreign object 190 above the mini-coil board 102 of the wireless charging pad 100 by distinguishing between changes caused by temperature and changes caused by the foreign object 190.

[0045] In some examples, an object detector can use a set of induction coils to detect foreign objects 190 when the charging coil is not operating to enable wireless charging. Thus, the object detector can preferably "actively" detect objects above the mini-coil board 102 while the wireless charging pad 100 is not transmitting power by wireless charging. The set of induction coils can be mounted on a printed circuit board. The set of induction coils may be located within the housing 104 of the wireless charging pad 100. Each coil in the set of induction coils can be smaller than the coils of the wireless charging pad 100 used for wireless power transmission.

[0046] Figure 2 is a top view of a wireless charging pad 100 according to some embodiments of the present disclosure, showing an enlarged view of a particular part of the wireless charging pad 100. As shown in Figure 2, a set of induction coils 202 can be arranged on a mini coil board 102. As described above, a plastic sheet or other suitable material of the housing 104 of the wireless charging pad 100 can be placed between the mini coil board 102 and the foreign object 190. The mini coil board 102 can be configured to detect the foreign object 190 through the housing 104.

[0047] In some examples, a set of induction coils 202 may be included in and / or utilized by an object detector (e.g., an object detector 300 as described with reference to Figure 3) to detect foreign objects 190. The object detector may utilize a set of induction coils 202 included in a resonant tank and may excite the resonant tank using a signal in a frequency range including or close to the nominal resonant frequency of the resonant tank (e.g., using one or more half-bridge circuits not shown in Figure 2). By analyzing the resonant frequency and the shift in the maximum output amplitude (e.g., output voltage peak), the object detector can accurately detect the foreign object 190 by accurately distinguishing between changes caused by temperature and changes caused by the foreign object 190.

[0048] In some examples, a set of induction coils 202 may include 50, 60, 70, 80, 90, or any other suitable number of induction coils. In some examples, each induction coil may have a nominal inductance of approximately, at least, or at least about 5 microhenries (μH), 6 μH, 7 μH, 8 μH, 9 μH, 10 μH, 11 μH, 12 μH, 13 μH, 14 μH, 15 μH, or any suitable range of values ​​between any two of these values. In some examples, each induction coil may have a nominal resistance of approximately, at least, or at least about 1 ohm, 2 ohms, 3 ohms, 4 ohms, 5 ohms, 6 ohms, 7 ohms, 8 ohms, 9 ohms, 10 ohms, or any suitable range of values ​​between any two of these values.

[0049] Figure 3 is an exemplary schematic diagram of components of an object detector 300 for detecting foreign objects, such as foreign objects 190, on the mini-coil board 102 of a wireless charging pad 100, according to some embodiments of the present disclosure. As shown in Figure 3, the object detector 300 may include at least an induction coil 202 of a resonant tank 302, an exciter 306 (e.g., a signal generator), and a processing circuit 308. As described above, the induction coil 202 may be located on the mini-coil board 102. The resonant tank 302 may have an output terminal 304. The object detector 300 may be located within a wireless charger, wireless charging device, or wireless charging pad (e.g., wireless charging pad 100). The resonant tank 302 may include an induction coil 202 and a capacitor C RES It can include...

[0050] In some examples, the resonant tank 302 includes or may be an RLC resonant tank. The exciter 306 may include a half-bridge circuit and may be embodied as an integrated circuit (IC). The processing circuit 308 may be embodied as a microprocessor, central processing unit (CPU), digital signal processor (DSP), microcontroller, or any other suitable processor or processing / control circuit. The resonant tank 302 may have a nominal resonant frequency which can be determined at least in part based on the nominal inductance and nominal resistance associated with the induction coil 202.

[0051] During operation, the exciter 306 can excite the resonant tank 302 using a signal in a frequency range that includes or is close to the nominal resonant frequency of the resonant tank 302 (for example, via frequency sweep). For example, the exciter 306 can generate a signal that sweeps from a frequency below the nominal resonant frequency to a frequency above the nominal resonant frequency. The signal can be injected into the resonant tank 302 under various operating conditions associated with the resonant tank 302 (e.g., temperature changes around the resonant tank 302 and / or the presence of foreign matter around the resonant tank 302). The output amplitude at the output terminal 304 of the resonant tank 302 can be filtered and processed (e.g., using low-pass filtering and high-pass filtering, peak detection, etc.) before being captured by the processing circuit 308 to acquire the resulting data. The resulting data may include multiple pairs of the output amplitude at the output terminal 304 of the resonant tank 302 and the corresponding frequencies of the signal used to excite the resonant tank 302. As described above, the resulting data can be obtained under temperature changes (e.g., changes in ambient temperature) and / or in the presence of foreign matter around the resonant tank 302.

[0052] The processing circuit 308 can determine a first parameter representing the inductance of coil 202 and a second parameter representing the resistance of coil 202. The resonant frequency is a parameter representing the inductance of coil 202. The resonant frequency is 1 / (L 2 The voltage can be proportional to 1 / R, where L is the coil inductance. The maximum output voltage amplitude of the resonant tank indicates the resistance of coil 202. This voltage can be proportional to 1 / R, where R is the coil resistance. The processing circuit 308 can detect object 190 based on a first parameter indicating a decrease in inductance and a second parameter indicating an increase in resistance, compared to the case where object 190 is not present.

[0053] In some examples, the processing circuit 308 can fit the resulting data using one or more curves (e.g., quadratic curves) to accurately identify the resonant frequency of the resonant tank 302 and the maximum output voltage amplitude at the output terminal 304 of the resonant tank 302. Exemplary curves fitted by the processing circuit 308 to identify the resonant frequency of the resonant tank 302 and the maximum output amplitude at the output terminal 304 of the resonant tank 302 are illustrated with reference to Figure 4.

[0054] By analyzing the shift and / or change in the resonant frequency and the shift and / or change in the maximum output amplitude at output terminal 304 (for example, determining significant deviations from the linear trend formed by the resonant frequency and voltage peak), the processing circuit 308 can distinguish between changes in the resonant frequency and maximum output amplitude caused by temperature and those caused by foreign matter (e.g., metallic foreign matter), and accurately detect foreign matter. An example of a method for distinguishing between changes in the resonant frequency of the resonant tank 302 and changes in the maximum output amplitude at output terminal 304 caused by temperature and those caused by foreign matter (e.g., foreign matter 190) based on deviations from a linear trend will be explained with reference to Figure 5.

[0055] In some examples, as shown in Figure 3, for instance, the object detector 300 may include 80 induction coils 202, each contained within 80 resonant tanks 302. The object detector 300 may include fewer exciters 306 than induction coils 202, and a multiplexing circuit may be used to transmit signals generated by the same exciters 306 to different resonant tanks 302. For example, the object detector 300 may include five exciters 306, and a multiplexing circuit may be used so that each of the five exciters 306 can be used to excite 16 resonant tanks 302.

[0056] Figure 4 shows exemplary curves 400 representing the output amplitude at the output terminal 304 of the resonant tank 302 with respect to the corresponding frequencies of signals used to excite the resonant tank 302 according to several embodiments of the present disclosure. The Y-axis represents the output amplitude at the output terminal 304. The X-axis represents the frequency corresponding to the output amplitude.

[0057] As shown in Figure 4, exemplary curves 400 can be used or fitted by processing circuit 308 to identify the resonant frequency of the resonant tank 302 and the maximum output amplitude at the output terminal 304 of the resonant tank 302. For example, based on curve 406, the resonant frequency of the resonant tank 302 (e.g., the frequency value at the X-axis position indicated by arrow 404) and the maximum output amplitude at the output terminal 304 of the resonant tank 302 (e.g., the voltage value at the Y-axis position indicated by arrow 402) can be identified. More specifically, the resonant frequency indicated by arrow 404 and the voltage value indicated by arrow 402 can be identified based on the peak or maximum value of curve 406. In some examples, each of the curves 400 (e.g., curve 406) can correspond to operating conditions related to the resonant tank 302 and / or the wireless charging pad 100 (e.g., temperature changes around the resonant tank 302 and / or the presence of foreign matter 190 around the resonant tank 302).

[0058] Figure 5 shows an exemplary distribution graph 500 of the maximum output amplitude at the output terminal 304 of the resonant tank 302 against the corresponding resonant frequency of the resonant tank 302, according to several embodiments of the present disclosure. The Y-axis represents the maximum output amplitude at the output terminal 304. The X-axis represents the corresponding resonant frequency. In some examples, each point in the distribution graph 500 can be obtained by using or fitting each of the curves 400. For example, one of the points in the distribution graph 500 may correspond to the resonant frequency and maximum output amplitude obtained based on the curve 406 in Figure 4.

[0059] As shown in Figure 5, most points in the distribution graph 500 follow a linear trend represented by line 502. This may be due to the fact that both the resonant frequency and the maximum output amplitude at the output terminal 304 of the resonant tank 302 change approximately linearly with the temperature associated with the resonant tank 302. More specifically, the maximum output amplitude can correlate linearly with the resistance of the induction coil 202 of the resonant tank 302. In certain applications, the resistance of the induction coil 202 of the resonant tank 302 can correlate linearly with temperature by the temperature-dependent increase in copper resistivity. The resonant frequency of the resonant tank 302 can correlate linearly with the temperature of the resonant tank 302 and / or its ambient temperature, since temperature changes can cause the trace of the induction coil 202 to expand, thereby affecting the inductance of the induction coil 202.

[0060] In some examples, the linear trend represented by line 502 can be used by the processing circuit 308 to distinguish between changes in the resonant frequency of the resonant tank 302 and changes in the maximum output amplitude at the output terminal 304 that are due to temperature and those that are due to foreign matter (e.g., foreign matter 190). For example, if the temperature of the resonant tank 302 and / or the ambient temperature rises when there is no foreign matter near the resonant tank 302, the maximum output amplitude and the corresponding resonant frequency obtained by the processing circuit 308 via the fitting curve (e.g., curve 400) may shift from the upper right of the distribution graph 500 (e.g., region 504 with a higher maximum output amplitude and a higher corresponding resonant frequency) to the lower left of the distribution graph 500 (e.g., region 506 with a lower maximum output amplitude and a lower corresponding resonant frequency). This may be due to a temperature rise that can increase both the resistance of the induction coil 202 and the inductance of the induction coil. In Figure 5, region 504 can correspond to a cold start, and region 506 can correspond to cooling after charging.

[0061] However, if foreign matter (e.g., foreign matter 190) is present around the resonant tank 302, the maximum output amplitude and corresponding resonant frequency obtained by the processing circuit 308 via the fitting curve (e.g., curve 400 in Figure 4) may deviate significantly from line 502 (e.g., across boundary 510 toward the lower right of distribution graph 500) to move into region 508. Region 508 can correspond to metallic foreign matter on the surface of the wireless charger. If foreign matter 190 is present around the resonant tank 302, the resistance of the induction coil 202 of the resonant tank 302 may increase, and the inductance of the induction coil 202 may decrease. Therefore, the deviation from line 502 beyond boundary 510 can indicate a change in coil resistance or inductance that is not solely attributable to the temperature of the resonant tank 302 and / or ambient temperature, which can certainly indicate the presence of foreign matter 190.

[0062] Advantageously, by being able to distinguish between temperature-induced and foreign-object-induced changes in resonant frequency and maximum output amplitude, the object detector 300 (e.g., processing circuit 308) can reliably detect foreign objects while operating under ambient and / or temperature changes associated with the wireless charging pad 100, thereby reducing false detections or missed detections in object detection. The ability to distinguish between temperature-induced and foreign-object-induced changes further enables the object detector 300 to detect foreign objects over a temperature range and immediately after a wireless charging session has stopped (e.g., when the wireless charging pad 100 is still warmer than before the wireless charging session started) or ended. These capabilities may be important for ensuring safety and mitigating or preventing thermal events when charging is interrupted or completed, for example, because a biological object may be detected near the wireless charging pad 100, and a foreign object 190 may be introduced into the wireless charging pad 100 immediately after wireless charging is stopped. Such functionality also allows the wireless charging pad 100 to recover from malfunctions associated with the passive mode object detection (PMOD) system, without which user intervention would be required for recovery. Furthermore, the object detection method performed by the object detector 300 (e.g., injecting signals of a certain frequency range, obtaining a mapping between the output amplitude and the corresponding frequency, and fitting the curve to identify the maximum output amplitude and resonant frequency) can be performed without continuous execution, operation, or manipulation, and the object detector 300 can be performed without initial calibration.

[0063] The foregoing disclosure is not intended to limit this disclosure to the exact form or specific field of use disclosed. Therefore, various alternative embodiments and / or modifications to this disclosure, whether expressly described or implied herein, are possible in light of this disclosure. While embodiments of this disclosure have been described in this manner, those skilled in the art will recognize that modifications in form and detail can be made without departing from the scope of this disclosure. Therefore, the scope of protection is limited by the claims.

[0064] It should be understood that not all objectives or benefits will necessarily be achieved by following any specific example described herein. Therefore, for example, a person skilled in the art will recognize that some examples may be manipulated to achieve or optimize one benefit or set of benefits taught herein, without necessarily achieving other objectives or benefits that may be taught or suggested herein.

[0065] All processes described herein can be fully automated by being implemented in software code modules executed by a processing system comprising one or more processors. The code modules may be stored in any type of non-temporary computer-readable medium or other computer storage device. Some or all of the methods may be implemented in dedicated computer hardware.

[0066] Many other variations not described herein will be apparent from this disclosure. For example, depending on the embodiment, any particular operation, event, or function of any of the algorithms described herein may be executed in a different order, and may be added, merged, or completely excluded (for example, not all described actions or events are necessary for the implementation of the algorithm). Furthermore, in some examples, the operations or events may be executed not sequentially, but concurrently, for example, through multithreading, interrupt handling, or via multiple processors or processor cores, or on other parallel architectures. In addition, different tasks or processes may be executed by different machines and / or computing systems that can work together.

[0067] The various exemplary logic blocks and modules described in relation to the embodiments disclosed herein may be implemented or executed by machines such as processing units or processors, digital signal processors ("DSPs"), application-specific integrated circuits ("ASICs"), field-programmable gate arrays ("FPGAs") or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. The processor may be a microprocessor, but in alternative examples, the processor may be a controller, microcontroller, or state machine, or a combination thereof. The processor may include electrical circuits for processing computer-executable instructions. In some embodiments, the processor includes an FPGA or other programmable device that performs logical operations without processing computer-executable instructions. The processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessors, a microprocessor combined with a DSP core, or any other such configuration. Although this specification primarily describes digital technologies, the processor may also include primarily analog components. Computing environments can include, but are not limited to, any type of computer system based on a microprocessor, mainframe computer, digital signal processor, portable computing device, device controller, or in-device computing engine.

[0068] Elements of methods, processes, routines, or algorithms described in relation to embodiments disclosed herein can be directly embodied in hardware, software modules executed by a processor device, or a combination of the two. Software modules may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or any other form of non-temporary computer-readable storage medium. Exemplary storage media may be coupled to a processor device so that the processor device can read information from and write information to the storage media. Alternatively, the storage media may be integrated into the processor device. The processor device and storage media may reside within an ASIC. The ASIC may reside within a user terminal. Alternatively, the processor device and storage media may exist as separate components within a user terminal.

[0069] Processes described herein or shown in the figures of this disclosure can be initiated on demand by a user or system administrator in response to an event such as a predetermined or dynamically determined schedule, or in response to any other event. Once such a process is initiated, a set of executable program instructions stored in one or more non-temporary computer-readable media (e.g., hard drives, flash memory, removable media) can be loaded into the memory (e.g., RAM) of a server or other computing device. The executable instructions may then be executed by the hardware-based computer processor of the computing device. In some embodiments, such a process or part thereof can be implemented in series or in parallel on multiple computing devices and / or multiple processors.

[0070] In particular, conditional language such as “can,” “could,” “might,” or “may,” unless otherwise specified, is understood in context to mean that some examples include some features, elements, and / or processes, but others do not. Thus, such conditional language is not generally intended to imply that features, elements, and / or processes are in any way for the sake of the examples, or that these examples necessarily involve logic for determining whether these features, elements, and / or processes should be included in or performed in any particular example, with or without user input or prompting.

[0071] Disjunctive language, such as the phrase "at least one of X, Y, or Z," is generally understood in its context to indicate that an item, term, etc., can be X, Y, Z, or any combination thereof (e.g., X, Y, and / or Z), unless otherwise specified. Therefore, such disjunctive language should not, in general, imply that several examples require at least one X, at least one Y, or at least one Z to exist.

[0072] Any process description, element, or block in the flowcharts described herein and / or shown in the accompanying drawings should be understood as potentially representing a module, segment, or portion of code containing executable instructions for performing a particular logical function or element in the process. The examples described herein include alternative examples in which, as understood by those skilled in the art, elements or functions may be omitted or executed in a different order from the illustrated or described order, including substantially simultaneously or in reverse order, depending on the function included.

[0073] It should be emphasized that many variations and modifications can be made to the above examples, and that these elements should be understood to be found in other acceptable examples. All such modifications and variations are intended to be included within the scope of this disclosure.

[0074] Any process description, element, or block in the flowcharts described herein and / or shown in the accompanying drawings should be understood as potentially representing a module, segment, or portion of code containing executable instructions for performing a particular logical function or element in the process. The examples described herein include implementations in which, as understood by those skilled in the art, elements or functions may be omitted or executed in a different order from that shown or described, including substantially simultaneously or in reverse order, depending on the function included.

[0075] Unless otherwise specified, articles such as "a" or "an" should generally be interpreted as including one or more of the listed items. Therefore, phrases such as "devices configured as" are intended to include one or more of the enumerated devices. Such one or more enumerated devices can also be collectively configured to perform the stated enumeration. For example, "processors configured to perform enumerations A, B, and C" may include a first processor configured to perform enumeration A, working in conjunction with a second processor configured to perform enumerations B and C.

Claims

1. It is a wireless charging system, A resonant tank equipped with a coil, An exciter electrically connected to the resonant tank, A processing circuit that communicates with at least the exciter, wherein the processing circuit is The exciter is used to excite the resonant tank, A first parameter indicating the inductance of the coil and a second parameter indicating the resistance of the coil related to the excited coil are determined. A processing circuit is configured to detect an object based on a first parameter indicating a decrease in inductance and a second parameter indicating an increase in resistance, compared to the case where the object is not present. A wireless charging system equipped with this feature.

2. The wireless charging system according to claim 1, wherein the first parameter includes the resonant frequency of the resonant tank, and the second parameter includes the amplitude of the output voltage of the resonant tank.

3. The processing circuit is configured to excite the resonant tank by applying at least a plurality of first signals sequentially to the resonant tank, and each of the plurality of first signals is generated based on a frequency among a plurality of frequencies. The processing circuit comprises at least, To obtain a first set of multiple output amplitudes, the output amplitude at the output terminal of the resonant tank is measured in relation to each of the first set of multiple signals applied to the resonant tank, The system is configured to determine the first and second parameters by selecting one of the multiple frequencies corresponding to the first maximum output amplitude among the first multiple output amplitudes as the first resonant frequency of the resonant tank, The wireless charging system according to claim 1, wherein the first parameter includes the first resonant frequency and the second parameter includes the first maximum output amplitude.

4. Detecting the aforementioned object means It is determined that the first point in the two-dimensional plane representing the first resonant frequency and the first maximum output amplitude lies on the first side of the distribution boundary in the two-dimensional plane, The wireless charging system according to claim 3, comprising: generating a first processing result indicating that the object is on the coil in response to the determination that the first point is on the first side of the distribution boundary in the two-dimensional plane.

5. The aforementioned processing circuit is The exciter sequentially applies a second plurality of signals to the resonant tank, and each of the second plurality of signals is generated based on the frequency among the plurality of frequencies. In order to obtain a second set of output amplitudes, the output amplitude at the output terminal of the resonant tank is measured when each of the second set of signals is applied to the resonant tank. One of the multiple frequencies corresponding to the second maximum output amplitude among the second multiple output amplitudes is selected as the second resonant frequency of the resonant tank. It is determined that the second point in the two-dimensional plane representing the second resonant frequency and the second maximum output amplitude lies on the second side of the distribution boundary in the two-dimensional plane. The wireless charging system according to claim 4, configured to generate a second processing result indicating that there is no object in the coil, in response to the determination that the second point is on the second side of the distribution boundary in the two-dimensional plane.

6. The wireless charging system according to claim 5, wherein the first temperature associated with the resonant tank during the application of the first plurality of signals to the resonant tank is different from the second temperature associated with the resonant tank during the application of the second plurality of signals to the resonant tank.

7. The aforementioned processing circuit is The wireless charging system according to claim 5, wherein, based on the result of the second processing, the wireless charging pad is configured to initiate inductive power transmission to another wireless charging pad.

8. The wireless charging system according to claim 5, wherein the distribution boundary includes a line in the two-dimensional plane, the first side of the distribution boundary is below the distribution boundary, and the second side of the distribution boundary is above the distribution boundary.

9. The aforementioned processing circuit is The system is configured to define the distribution boundary based on the distribution of a plurality of points in the two-dimensional plane. The wireless charging system according to claim 4, wherein each of the aforementioned points represents the resonant frequency of the resonant tank and the maximum output amplitude at the output terminal under corresponding operating conditions related to the resonant tank in which no object is present on the coil.

10. The wireless charging system according to claim 4, wherein the output amplitude at the output terminal includes the voltage at the output terminal.

11. The wireless charging system according to claim 4, wherein the plurality of frequencies include or are close to the nominal resonant frequency of the resonant tank.

12. The wireless charging system according to claim 1, wherein the object is a metallic object.

13. A method for detecting objects for wireless charging, A step of exciting the resonant tank of a wireless charging pad with an exciter, wherein the resonant tank is equipped with a coil, The steps include determining a first parameter indicating the inductance of the coil and a second parameter indicating the resistance of the coil related to the excited coil, A step of detecting the object based on a first parameter indicating a decrease in inductance and a second parameter indicating an increase in resistance, compared to the case where the object is not present. Methods that include...

14. The step of exciting the resonant tank includes the step of sequentially applying a plurality of first signals to the resonant tank, wherein each of the plurality of first signals is generated based on a frequency among a plurality of frequencies. The step of determining the first parameter and the second parameter is: To obtain a first set of multiple output amplitudes, the output amplitude at the output terminal of the resonant tank is measured when each of the first set of multiple signals is applied to the resonant tank, This includes selecting one of the multiple frequencies corresponding to a first maximum output amplitude among the first multiple output amplitudes as the first resonant frequency of the resonant tank, The method according to claim 13, wherein the first parameter includes the first resonant frequency and the second parameter includes the first maximum output amplitude.

15. The step of detecting the object is, It is determined that the first point in the two-dimensional plane representing the first resonant frequency and the first maximum output amplitude lies on the first side of the distribution boundary in the two-dimensional plane, The method according to claim 14, comprising: generating a first processing result indicating that the object is present on the wireless charging pad in response to the determination that the first point is on the first side of the distribution boundary in the two-dimensional plane.

16. The steps include: causing the exciter to sequentially apply a second plurality of signals to the resonant tank, wherein each of the second plurality of signals is generated based on the frequency among the plurality of frequencies; To obtain a second set of output amplitudes, the steps include measuring the output amplitude at the output terminal of the resonant tank when each of the second set of signals is applied to the resonant tank, The steps include selecting one of the multiple frequencies corresponding to the second maximum output amplitude among the second multiple output amplitudes as the second resonant frequency of the resonant tank, A step of determining that the second point in the two-dimensional plane representing the second resonant frequency and the second maximum output amplitude is on the second side of the distribution boundary in the two-dimensional plane, The process includes the step of generating a second processing result indicating that there are no objects on the wireless charging pad, in response to the determination that the second point is on the second side of the distribution boundary in the two-dimensional plane. The method according to claim 15.

17. The method according to claim 13, wherein the method is performed while the wireless charging pad is not inductively transmitting power to another wireless charging pad.

18. A method for detecting objects for wireless charging, A step of exciting a resonant tank of a wireless charging pad, wherein the resonant tank comprises a coil, The steps include detecting an object on the wireless charging pad based on the fact that the resistance of the coil increases and the inductance of the coil decreases while the resonant tank is excited, Methods that include...

19. The method according to claim 18, wherein the step of exciting the resonant tank comprises sequentially applying a plurality of first signals to the resonant tank, each of which is generated based on a frequency among a plurality of frequencies.

20. The step of detecting the object is, To obtain a first set of multiple output amplitudes, the output amplitude at the output terminal of the resonant tank is measured in relation to each of the first set of multiple signals applied to the resonant tank, Selecting one of the multiple frequencies corresponding to the first maximum output amplitude among the first multiple output amplitudes as the first resonant frequency of the resonant tank, It is determined that the first point in the two-dimensional plane representing the first resonant frequency and the first maximum output amplitude lies on the first side of the distribution boundary in the two-dimensional plane, The method according to claim 19, comprising: generating a first processing result indicating that the object is present on the wireless charging pad in response to the determination that the first point is on the first side of the distribution boundary in the two-dimensional plane.

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