Foreign object detection method, device and wireless charging system

Abstract

The present invention provides a foreign object detection method, device and wireless charging system, which relates to the technical field of wireless charging. The method includes: in response to the start of the wireless charging system, obtaining the oscillation signal of the transmitting end of the wireless charging system; performing operational amplifier processing on the oscillation signal to obtain the target oscillation signal; sampling the target oscillation signal according to a pre-configured sampling period to obtain multiple sampling signals; extracting the peak signal and valley signal contained in the sampling signal, and calculating the quality factor based on the peak signal and valley signal; and performing foreign object detection based on the quality factor. The foreign object detection method, device and wireless charging system provided by the present invention do not rely on the peak value of the oscillation signal when calculating the quality factor, and have a more flexible sampling period. In addition, the calculation method of the peak signal and valley signal can improve the resolution of the foreign object detection method, thereby increasing the safety of the wireless charging product.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless charging, and in particular to a foreign object detection method, device and wireless charging system. Background Art

[0002] The traditional charging process mainly transmits electrical energy through wires. However, due to its own shortcomings, wired charging has its limitations in special environments such as moisture, flammability, and medical implants, and also brings many inconveniences in daily life.

[0003] Wireless charging technology avoids the shortcomings of traditional charging methods and has attracted more and more attention, especially in the fields of consumer electronics, industrial products, medical services, etc., where it has been increasingly widely used.

[0004] However, the intrusion of metal foreign objects brings hidden dangers to the wireless charging process, especially the intrusion of metal foreign objects into the coil of the wireless charging transmitter, which can easily cause additional losses on the coil surface and serious heating of the metal itself, greatly affecting the user experience. Therefore, foreign object detection is an important function in the safety performance evaluation of wireless charging systems.

[0005] Typically, monitoring the Q factor of the resonant circuit at the transmitter end of wireless charging can be used as an indication of the presence of foreign matter. However, the resolution of foreign matter detection using the Q factor in related technologies is low. For small metal foreign matters that pose a heat threat (such as paper clips, steel sheets, etc.), traditional Q-factor-based foreign matter detection algorithms are difficult to effectively identify, affecting the safety of the overall wireless charging product. Summary of the invention

[0006] In view of this, an object of the present invention is to provide a foreign object detection method, device and wireless charging system to alleviate the above technical problems.

[0007] In a first aspect, an embodiment of the present invention provides a foreign object detection method, which is applied to a transmitter of a wireless charging system, the method comprising: in response to the start-up of the wireless charging system, obtaining an oscillation signal of the transmitter of the wireless charging system; wherein the oscillation signal is generated by a resonant circuit of the transmitter; performing operational amplifier processing on the oscillation signal to obtain a target oscillation signal corresponding to the oscillation signal; sampling the target oscillation signal according to a preconfigured sampling period to obtain a plurality of sampling signals contained in the sampling period; extracting peak signals and valley signals contained in the plurality of sampling signals, and calculating a quality factor corresponding to the resonant circuit based on the peak signals and the valley signals; and performing foreign object detection at the transmitter based on the quality factor.

[0008] In combination with the first aspect, an embodiment of the present invention provides a first possible implementation of the first aspect, wherein the above-mentioned step of sampling the target oscillation signal according to a preconfigured sampling period includes: sampling the peak signal and the trough signal of the target oscillation signal in each signal period to obtain a sampling signal containing the peak signal and the trough signal; determining the peak signal as the peak signal, and determining the trough signal as the valley signal.

[0009] In combination with the first aspect, an embodiment of the present invention provides a second possible implementation of the first aspect, wherein the transmitting end of the above-mentioned wireless charging system is configured with a frequency measurement circuit; the frequency measurement circuit is used to generate a trigger signal that matches the frequency of the oscillation signal to measure the frequency of the oscillation signal; the step of sampling the target oscillation signal according to a pre-configured sampling period also includes: configuring the sampling period based on the trigger signal, so as to sample the target oscillation signal based on the sampling period under the triggering of the trigger signal.

[0010] In combination with the second possible implementation of the first aspect, an embodiment of the present invention provides a third possible implementation of the first aspect, wherein the above-mentioned step of configuring the sampling period based on the trigger signal includes: configuring the sampling frequency of the sampling period to be a multiple frequency of the trigger signal based on the frequency of the trigger signal; or, configuring the frequency of the trigger signal to be the sampling frequency of the sampling period.

[0011] In combination with the third possible implementation of the first aspect, an embodiment of the present invention provides a fourth possible implementation of the first aspect, wherein the above-mentioned step of sampling the target oscillation signal based on the sampling period includes: if the sampling frequency of the sampling period is a multiple frequency of the trigger signal, then based on the sampling frequency of the multiple frequency, the positive half-wave signal value and the negative half-wave signal value of the target oscillation signal are collected in each signal period; the positive half-wave signal value is determined as the peak signal, and the negative half-wave signal value is determined as the valley signal.

[0012] In combination with the third possible implementation of the first aspect, an embodiment of the present invention provides a fifth possible implementation of the first aspect, wherein the above-mentioned step of sampling the target oscillation signal based on the sampling period further includes: if the sampling frequency of the sampling period is the frequency of the trigger signal, then within each sampling period, multiple sampling signals are collected based on the sampling frequency; the maximum value of the sampling signal is determined as the peak signal, and the minimum value of the sampling signal is determined as the valley signal.

[0013] In combination with the second possible implementation of the first aspect, an embodiment of the present invention provides a sixth possible implementation of the first aspect, wherein the above method also includes: acquiring the frequency of the oscillation signal measured by the frequency measurement circuit; performing frequency compensation on the quality factor based on the frequency of the oscillation signal to obtain a compensated quality factor; and performing foreign object detection at the transmitting end based on the compensated quality factor.

[0014] In a second aspect, an embodiment of the present invention further provides a foreign object detection device, which is applied to a transmitting end of a wireless charging system, and the device includes: an acquisition module, which is used to respond to the startup of the wireless charging system and acquire an oscillation signal of the transmitting end of the wireless charging system; wherein the oscillation signal is generated by the resonant circuit of the transmitting end; a processing module, which is used to perform operational amplifier processing on the oscillation signal to obtain a target oscillation signal corresponding to the oscillation signal; a sampling module, which is used to sample the target oscillation signal according to a preconfigured sampling period to obtain multiple sampling signals contained in the sampling period; an extraction signal, which is used to extract peak signals and valley signals contained in the multiple sampling signals, and calculate the quality factor corresponding to the resonant circuit based on the peak signals and the valley signals; a detection module, which is used to perform foreign object detection at the transmitting end based on the quality factor.

[0015] In a third aspect, an embodiment of the present invention further provides a wireless charging system, comprising a transmitter; wherein a controller of the transmitter is configured with the foreign object detection device described in the second aspect.

[0016] In combination with the third aspect, an embodiment of the present invention provides a first possible implementation of the third aspect, wherein the above-mentioned transmitting end includes a transmitting coil, a resonant circuit connected to the transmitting coil, and a foreign object detection circuit connected to the resonant circuit; the resonant circuit and the foreign object detection circuit are both connected to the controller of the transmitting end.

[0017] In combination with the first possible implementation of the third aspect, an embodiment of the present invention provides a second possible implementation of the third aspect, wherein the above-mentioned foreign object detection circuit includes an operational amplifier processing circuit and a frequency measurement circuit connected to the operational amplifier processing circuit; wherein the operational amplifier processing circuit is used to obtain the oscillation signal generated by the resonant circuit, perform operational amplifier processing on the oscillation signal, and obtain a target oscillation signal corresponding to the oscillation signal; the frequency measurement circuit is used to generate a trigger signal that matches the frequency of the oscillation signal, so as to measure the frequency of the oscillation signal based on the trigger signal.

[0018] The embodiments of the present invention bring the following beneficial effects:

[0019] The foreign object detection method, device and wireless charging system provided by the embodiments of the present invention can respond to the start of the wireless charging system and obtain the oscillation signal of the transmitting end of the wireless charging system; perform operational amplifier processing on the oscillation signal to obtain a target oscillation signal corresponding to the oscillation signal; sample the target oscillation signal according to a pre-configured sampling period to obtain multiple sampling signals contained in the sampling period; further extract the peak signal and valley signal contained in the multiple sampling signals to calculate the quality factor corresponding to the resonant circuit based on the peak signal and valley signal; finally perform foreign object detection at the transmitting end based on the quality factor. Since the sampling period can be configured and, when calculating the quality factor, the peak signal and valley signal in the sampling signal are extracted instead of the peak value of the oscillation signal, while adopting a more flexible sampling period, compared with the method of calculating the quality factor based on the peak value of the oscillation signal, the method of calculating the peak signal and valley signal can also improve the resolution of the foreign object detection method, thereby increasing the safety of the wireless charging product.

[0020] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 A schematic diagram of a foreign body detection circuit provided by an embodiment of the present invention;

[0024] Figure 2 A flow chart of a foreign body detection method provided by an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of a target oscillation signal provided by an embodiment of the present invention;

[0026] Figure 4 It is a foreign body detection circuit of CNTQ algorithm;

[0027] Figure 5A comparison diagram of quality factors provided by an embodiment of the present invention;

[0028] Figure 6 A schematic structural diagram of a foreign body detection device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0030] Typically, in a wireless charging system, when the resonant circuit of the transmitter is affected by the receiver system and foreign objects within the field range of the generated electromagnetic field, its quality factor will cause a more obvious step change. Therefore, monitoring the quality factor of the resonant circuit of the transmitter can be used as a detection indicator of the presence of foreign objects.

[0031] The quality factor is also called the Q factor, or the Q-Factor coil quality factor. There are many ways to determine the quality factor of the resonant circuit in the wireless charging system. Currently, the Q-Factor coil quality factor detection method is mostly used.

[0032] Specifically, when the wireless charging system is in operation, it is necessary to continuously charge and then discharge the resonant circuit to generate several times of intracavity attenuated oscillation signals. The attenuated oscillation signal is input to the wireless charging processing chip at the transmitting end, and the processing chip then outputs the sine number (CNT) between two fixed voltage thresholds Vx and Vy, and the coil quality factor Q is obtained by calculation.

[0033] Specifically, the calculation formula of the quality factor Q can be expressed as:

[0034] =

[0035] Where Vx is the amplitude of the x-th sine wave, Vy is the amplitude of the y-th sine wave, and CNT=yx.

[0036] At present, in the relevant technology, the algorithm of the above-mentioned quality factor Q is generally: after the sine number (CNT) between the fixed Vx and Vy is measured by the hardware circuit, the current Q value is calculated, so it is also referred to as the CNTQ algorithm. Under this algorithm, Vx and Vy are fixed values, CNT is a changing value following the metal intrusion, and the minimum change of CNT is 1, resulting in the measurement of Q value is not continuous, or the resolution is low. When tiny foreign objects invade or the foreign objects are located at the edge, the CNTQ algorithm is difficult to identify.

[0037] Therefore, for small metal foreign objects that pose a heat threat, such as paper clips and steel sheets, the traditional CNTQ foreign object detection algorithm is difficult to effectively identify at the edge of the coil, affecting product safety.

[0038] Based on this, a foreign object detection method, device and wireless charging system provided by the embodiments of the present invention can effectively alleviate the above technical problems and thereby improve the resolution of foreign object detection.

[0039] To facilitate understanding of this embodiment, a foreign matter detection method disclosed in an embodiment of the present invention is first introduced in detail.

[0040] In a possible implementation, the foreign object detection method provided in an embodiment of the present invention is applied to a transmitting end of a wireless charging system. Specifically, the wireless charging system also includes a receiving end. During the wireless charging process, the transmitting end and the receiving end of the wireless charging system realize signal transmission by means of coil coupling.

[0041] Specifically, in an embodiment of the present invention, the transmitting end of the wireless charging system includes a transmitting coil, a resonant circuit connected to the transmitting coil, and a foreign object detection circuit connected to the resonant circuit; the resonant circuit and the foreign object detection circuit are both connected to the controller of the transmitting end. The controller of the transmitting end can control the transmitting end during the wireless charging process, and at the same time, execute the foreign object detection method provided by the embodiment of the present invention to realize foreign object detection at the transmitting end.

[0042] For ease of understanding, Figure 1 A schematic diagram of a foreign body detection circuit is shown, wherein Figure 1 In the figure, a driving schematic diagram of part of the transmitting end circuit is also shown, such as Figure 1 As shown, it includes a full-bridge drive circuit composed of power tubes G1, G2, G3, and G4, as well as the self-inductance Lp of the wireless transmitting coil at the transmitting end, and a resonant capacitor Cp connected in series with Lp. Lp and Cp are also called resonant devices of the resonant circuit.

[0043] Furthermore, the foreign body detection circuit in the embodiment of the present invention further includes an operational amplifier processing circuit and a frequency measurement circuit connected to the operational amplifier processing circuit;

[0044] The operational amplifier processing circuit is used to obtain the oscillation signal generated by the resonant circuit, perform operational amplifier processing on the oscillation signal, and obtain a target oscillation signal corresponding to the oscillation signal;

[0045] The frequency measurement circuit is used to generate a trigger signal that matches the frequency of the oscillation signal, so as to measure the frequency of the oscillation signal, that is, the resonant frequency, based on the trigger signal.

[0046] Specifically, Figure 1In the figure, Vin represents the input electrical signal. During the charging process, under the control of the controller, the resonant circuit of the wireless charging system is continuously charged first and then discharged, generating several times of intracavity attenuated oscillation signals, namely Figure 1 The signal A1 in the embodiment of the present invention is the oscillation signal, that is, the oscillation signal in the embodiment of the present invention is an attenuated oscillation signal, also known as an attenuated ringing signal. In actual use, Figure 1 Lp and Cp in the circuit form an LC circuit, which oscillates freely by decay. The acquisition nodes of the foreign object detection circuit are arranged at both ends of the resonant capacitor Cp to collect the differential signal at both ends of the resonant capacitor Cp, and then obtain the decayed oscillation signal at both ends of the resonant capacitor Cp. The decayed oscillation signal is further processed by the operational amplifier processing circuit and the frequency measurement circuit for subsequent calculation.

[0047] It should be understood that in addition to the above Figure 1 The LC resonant circuit in the embodiment of the present invention is applicable to a variety of transmitting coils. The specific application is subject to actual use, and the embodiment of the present invention does not limit this.

[0048] Specifically, Figure 1 In the embodiment, the operational amplifiers OP1 and OP2 constitute the operational amplifier processing circuit in the embodiment of the present invention, the operational amplifiers OP1 and OP3, and the comparator CMP1 constitute the frequency measurement circuit in the embodiment of the present invention, wherein the reference voltage signal Vref corresponding to the input end of the operational amplifier OP2 can be used to adjust the reference voltage or bias voltage of the output signal of the operational amplifier OR2; and the reference voltage signal Vref corresponding to the input end of the operational amplifier OP1, OP3, and the comparator CMP1 can also adjust the corresponding reference voltage. The specific value of the reference voltage signal Vref can be set according to the actual usage, and the embodiment of the present invention is not limited to this.

[0049] In addition, Figure 1 The circuit also includes a plurality of resistors, which can adjust the proportional coefficient of the corresponding operational amplifier to be amplified or reduced, and are used in conjunction with the operational amplifier and the comparator to form the operational amplifier processing circuit and the frequency measurement circuit.

[0050] Further, if Figure 1 As shown, a calculation unit 10 and a frequency measurement unit 20 are also configured at the transmitting end, the output end of the operational amplifier processing circuit is connected to the calculation unit 10 , and the output end of the frequency measurement circuit is connected to the frequency measurement unit 20 .

[0051] In actual use, the above-mentioned calculation unit 10 and frequency measurement unit 20 can be configured with a separate processing chip for calculation, or they can be integrated into the controller of the transmitting end and the controller performs the calculation. The specific settings can be made according to the actual usage situation, and the embodiment of the present invention does not limit this.

[0052] Specifically, after the acquisition node of the foreign object detection circuit acquires the attenuated oscillation signal at both ends of the resonant capacitor Cp, the attenuated oscillation signal is proportionally reduced by the operational amplifiers OP1 and OP2 to obtain a low-amplitude oscillation signal, which is then calculated by the calculation unit 10. Further, the calculation unit 10 can usually perform DA conversion, sampling and restoration on the low-amplitude oscillation signal for subsequent calculations. In addition, after the attenuated oscillation signal is reduced by the operational amplifiers OP1 and OP3, it passes through the comparator CMP1 to obtain a trigger signal with the same frequency as the attenuated oscillation signal, such as a square wave signal with the same frequency as the attenuated oscillation signal, etc., which can be used for the subsequent frequency measurement unit to accurately calculate the resonant frequency.

[0053] Specifically, based on the above Figure 1 The foreign object detection circuit shown, Figure 2 A flow chart of a foreign body detection method is shown, and the foreign body detection process is further explained. Figure 2 As shown, the following steps are included:

[0054] Step S202, in response to the wireless charging system being started, obtaining an oscillation signal of a transmitter of the wireless charging system;

[0055] The oscillation signal is generated by the resonant circuit of the transmitting end; for example, Figure 1 The signal A1 in the figure is usually an attenuated oscillation signal generated by a resonant circuit, also known as an attenuated ringing signal.

[0056] Step S204, performing operational amplifier processing on the oscillation signal to obtain a target oscillation signal corresponding to the oscillation signal;

[0057] refer to Figure 1 The process of step S204 generally refers to the processing process of the operational amplifier processing circuit, for example, the operational amplifiers OP1 and OP2 are scaled down, etc. Figure 1 The obtained signal A3 is the target oscillation signal.

[0058] Step S206, sampling the target oscillation signal according to a pre-configured sampling period to obtain a plurality of sampling signals contained in the sampling period;

[0059] Step S208, extracting peak signals and valley signals contained in the plurality of sampled signals, and calculating a quality factor corresponding to the resonant circuit based on the peak signals and valley signals;

[0060] Step S210: Perform foreign object detection at the transmitting end based on the quality factor.

[0061] In specific implementation, the pre-configured sampling period is usually less than or equal to the signal period of the oscillation signal. Assuming that the oscillation signal is an oscillation signal similar to a sine signal, the sampling period at this time is usually less than or equal to the signal period of the sine signal. Therefore, the above-mentioned multiple adopted signals may include the peak and trough signals of the oscillation signal, or may not include the peak and trough signals. In the embodiment of the present invention, it is only necessary to extract the peak signal and the valley signal contained in the sampling signal for calculation. Not only can the flexibility of signal acquisition be improved, but also a sampling period less than the signal period can be set to obtain a quality factor with higher resolution.

[0062] Further, when calculating the quality factor, you can refer to the calculation formula:

[0063] =

[0064] Where Q represents the quality factor, Vx is the amplitude of the x-th sine wave, Vy is the amplitude of the y-th sine wave, and CNT=yx.

[0065] In actual use, in an embodiment of the present invention, considering that there are multiple oscillation cycles in an oscillation signal, when calculating the above-mentioned quality factor, Vx and Vy can be determined at intervals of a certain period, that is, the amplitude of the x-th period can be taken as Vx, and the amplitude of the y-th period can be taken as Vy. At this time, CNT=yx, and the above-mentioned quality factor can be calculated.

[0066] In the embodiment of the present invention, Vx can be expressed as the difference between the peak signal and the valley signal, and Vy can be expressed as the difference between the peak signal and the valley signal after an interval of several cycles. The specific settings can be made according to actual usage, and the embodiment of the present invention does not limit this.

[0067] Furthermore, after the quality factor is calculated based on the above method, foreign object detection can be further implemented in step S210. Specifically, when foreign object detection is performed at the transmitting end based on the quality factor, when a foreign object appears, the quality factor will have a step jump. Therefore, a detection threshold can be pre-configured, that is, when it is determined under experimental conditions that there is no foreign object, the value range of the quality factor is determined, and the detection threshold is determined based on the value range. When a foreign object appears, the quality factor has a step jump, and when the jump range is greater than the detection threshold, it can be determined that a foreign object is present.

[0068] The specific detection method and the jump method for determining the quality factor can be set according to actual usage conditions, and the embodiment of the present invention does not limit this.

[0069] Therefore, the foreign object detection method provided by the embodiment of the present invention can respond to the start-up of the wireless charging system and obtain the oscillation signal of the transmitting end of the wireless charging system; perform operational amplifier processing on the oscillation signal to obtain a target oscillation signal corresponding to the oscillation signal; sample the target oscillation signal according to a pre-configured sampling period to obtain multiple sampling signals contained in the sampling period; further extract the peak signal and the valley signal contained in the multiple sampling signals to calculate the quality factor corresponding to the resonant circuit based on the peak signal and the valley signal; finally, perform foreign object detection at the transmitting end based on the quality factor. Since the sampling period can be configured, and when calculating the quality factor, the peak signal and the valley signal in the sampling signal are extracted instead of relying on the peak value of the oscillation signal. Therefore, while adopting a more flexible sampling period, compared with the method of calculating the quality factor relying on the peak value of the oscillation signal, the method of calculating the peak signal and the valley signal can also improve the resolution of the foreign object detection method, thereby increasing the safety of the wireless charging product.

[0070] In actual use, considering that the oscillation signal has a signal waveform similar to a sinusoidal signal, in the embodiment of the present invention, in the above step S206, when sampling the target oscillation signal, the peak signal and the trough signal in each signal cycle can be captured.

[0071] Specifically, Figure 3 A schematic diagram of a target oscillation signal is shown. In actual use, the target oscillation signal will include a DC bias part that is unrelated to the quality factor of the resonant circuit. The specific value of the bias of the DC bias part cannot be determined, and even a time-varying bias phenomenon may occur. In order to avoid the influence of the DC bias part on the quality factor calculation, in an embodiment of the present invention, the peak value of the target oscillation signal can be directly captured.

[0072] Specifically, the peak value (Vpk) and valley value (Vva) of each sine wave can be captured by configuring the sampling period, and the peak value of the x-th sine wave is Vpkx, and the valley value is Vvax.

[0073] That is, in the above step S206, when the target oscillation signal is sampled according to the pre-configured sampling period, the peak signal and the trough signal of the target oscillation signal in each signal period can be sampled to obtain a sampling signal including the peak signal and the trough signal, that is, Figure 3 The peak signals shown are Vpk1, Vpk2, ..., and the valley signals Vva1, Vva2, .... The peak signals are then determined as peak signals, and the valley signals are determined as valley signals.

[0074] At this time, Vx=Vpkx-Vvax is used as the amplitude of the x-th sine wave. By substituting it into the previous formula, the quality factor Q of the resonant circuit can be calculated.

[0075] Among them, for the implementation method of the above-mentioned sampling peak signal and trough signal, it is usually required that the sampling period is smaller, that is, the smaller the sampling period, the better the restoration of the oscillation signal, so that the peak signal and trough signal extracted from each period are more real, and the quality factor Q value calculated using the amplitude obtained from these periods is more accurate.

[0076] In actual use, considering that the process of capturing the peak signal and the trough signal of the target oscillation signal has the characteristics of a large number of signal acquisitions and a high frequency, the hardware requirements and the processing capabilities of the controller are relatively high. Therefore, in an embodiment of the present invention, when sampling the target oscillation signal, it is also possible to adopt a method of reducing the sampling frequency for sampling. At the same time, it is also possible to avoid encountering a higher resonant frequency in actual applications, which reduces the ability to restore the oscillation signal, misses the peak and trough values ​​in a sinusoidal period, and leads to inaccurate calculation of the quality factor.

[0077] Specifically, in order to achieve the above-mentioned method of reducing the sampling frequency, the embodiment of the present invention is based on Figure 1 The frequency measurement circuit shown is implemented.

[0078] That is, the transmitting end of the wireless charging system in the embodiment of the present invention is configured with a frequency measurement circuit; the frequency measurement circuit is used to generate a trigger signal matching the frequency of the oscillation signal to measure the frequency of the oscillation signal; for example, Figure 1 The square wave signal A2 with the same frequency as the oscillation signal triggers the starting point of the sampling period so as to perform sampling in a specific manner or at a specific period without sampling the peak and trough values ​​of the sine wave. The calculation can also be performed based on the above-mentioned quality factor calculation formula.

[0079] Specifically, based on the above-mentioned frequency measurement circuit, in an embodiment of the present invention, when sampling the target oscillation signal according to a preconfigured sampling period, the sampling period can be first configured based on the trigger signal, so that the target oscillation signal can be sampled based on the sampling period under the triggering of the trigger signal.

[0080] The trigger signal in the embodiment of the present invention is a trigger signal that matches the frequency of the oscillation signal, and is usually a signal with the same frequency as the oscillation signal, for example, Figure 1 Square wave signal A2 with the same frequency.

[0081] Furthermore, when the sampling period is configured based on the trigger signal, the sampling frequency of the sampling period can be configured as a multiple of the trigger signal frequency based on the frequency of the trigger signal; or the frequency of the trigger signal can be configured as the sampling frequency of the sampling period.

[0082] Among them, the multiplied frequency usually refers to an even-numbered multiplied frequency, such as 2-multiplied frequency, etc., so as to ensure that the positive and negative half-waves have two symmetrical sampling points (Vx, Vy) in one cycle to facilitate the calculation of the amplitude.

[0083] Further, when the target oscillation signal is sampled based on the sampling period, if the sampling frequency of the sampling period is a multiple frequency of the trigger signal, the positive half-wave signal value and the negative half-wave signal value of the target oscillation signal are collected in each signal period based on the sampling frequency of the multiple frequency; the positive half-wave signal value is determined as the peak signal, and the negative half-wave signal value is determined as the valley signal.

[0084] Further, if the sampling frequency of the sampling period is the frequency of the trigger signal, multiple sampling signals are collected based on the sampling frequency in each sampling period; the maximum value in the sampling signal is determined as the peak signal, and the minimum value in the sampling signal is determined as the valley signal.

[0085] That is, in the embodiment of the present invention, there are two ways to sample the target oscillation signal:

[0086] (1) Using a double frequency, for example, a sampling frequency of 2 times, in this case, two values ​​of the positive half-wave and the negative half-wave in each signal cycle can be extracted as sampling signals, such as Figure 3 Vpkx and Vvax within a sinusoidal period. At this time, Vx=Vpkx-Vvax. As the amplitude of the x-th sinusoid, it is substituted into the previous formula to calculate the quality factor Q of the resonant circuit.

[0087] (2) Use a sampling frequency that is the same as the target oscillation signal. In this case, multiple signals can be sampled at the same time point in each signal cycle. Then, a certain algorithm is used to select the maximum and minimum values ​​of the sampled signal in the signal cycle as the peak signal and valley signal, respectively. The difference is taken as Vx, which can also be substituted into the previous formula to calculate the quality factor Q of the resonant circuit.

[0088] In the specific implementation, it is assumed Figure 1 The calculation unit 10 in the embodiment can be configured with an ADC sampling function. Taking the trigger signal as a square wave signal as an example, the above two sampling methods can be triggered by the square wave signal. For example, by triggering the ADC sampling function by the double edges of the square wave signal, the sampling method (1) can be realized, that is, each edge triggers a sampling, achieving a 2x frequency sampling effect. At this time, symmetrical points can be sampled in the positive and negative half waves of each sine cycle, and the two points are exactly 180° apart in phase. The difference between the two points sampled in the cycle is taken as the amplitude. Even if they are not peak and valley values, because of the 180° phase difference, the quality factor Q calculated by these amplitudes is also accurate.

[0089] Furthermore, the sampling method (2) mentioned above can be realized through the single-edge triggering ADC sampling function of the square wave signal. For example, only the rising or falling edge can be triggered. In this case, it is the same-frequency sampling. After the trigger, multiple points are sampled to obtain an array. The maximum and minimum values ​​in the array are taken and subtracted to obtain the amplitude, and the accurate quality factor Q can be obtained.

[0090] Compared with the method of relying on a high sampling rate to obtain the peak value of each signal cycle, the above two sampling methods do not require a high sampling rate for the ADC function and are more applicable.

[0091] In actual use, taking into account the fact that under actual working conditions, some metals have a greater impact on the frequency, further frequency compensation can be performed on the quality factor Q of the above-mentioned resonant circuit and the resonant frequency measured by the frequency measurement circuit to ensure the effect of foreign object detection.

[0092] Specifically, in an embodiment of the present invention, the frequency of the oscillation signal measured by the frequency measurement circuit, that is, the resonant frequency, can also be obtained, and then the quality factor is frequency compensated based on the frequency of the oscillation signal to obtain a compensated quality factor; foreign object detection is performed at the transmitting end based on the compensated quality factor.

[0093] Specifically, when frequency compensation is performed on the quality factor, the quality factor after frequency compensation may be calculated according to the following calculation formula, expressed as Qcomp, and the calculation formula is expressed as follows:

[0094] =

[0095] Among them, Q is the quality factor obtained by the above method, F is the frequency of the oscillation signal measured by the frequency measurement circuit, that is, the resonant frequency, and Fcali is the no-load oscillation frequency set by the factory.

[0096] In actual use, for working conditions where frequency has a greater impact, foreign object detection can be performed by detecting a step jump in the quality factor after the above-mentioned frequency compensation, or the quality factor Q and the quality factor Qcomp after frequency compensation can be detected at the same time. The specific details shall be based on the actual use situation and are not limited in this embodiment of the present invention.

[0097] For example, foreign matter that has a small impact on the quality factor but a large impact on the frequency can also be detected when the quality factor Qcomp after the frequency compensation is used, thereby ensuring the foreign matter detection effect.

[0098] Furthermore, for ease of understanding, the foreign matter detection method in the embodiment of the present invention is further compared and explained with the CNTQ algorithm in the related art.

[0099] Specifically, Figure 4A foreign object detection circuit of a CNTQ algorithm is shown, including a transmitting coil L, a series resonant capacitor C, a parallel resonant capacitor Cpar, and compensation inductors L1 and L2, wherein the transmitting coil L, the series resonant capacitor C, the parallel resonant capacitor Cpar and the compensation inductors L1 and L2 form a resonant circuit. Figure 4 In the embodiment, after charging and discharging through the full bridge circuit 30, the resonant circuit generates an attenuated oscillation signal B1, and Figure 4 In the example, the foreign body detection circuit can collect the attenuated oscillation signal B1 on both sides of the resonant capacitor C. In addition, Figure 4 It also includes multiple resistors, which are used in conjunction with operational amplifiers and comparators, as well as logic devices, etc. to achieve the detection function. The specific parameters and models of the resistors and logic devices can be set according to actual usage, and the embodiment of the present invention does not limit this.

[0100] and, Figure 4 In the embodiment, the reference voltage signal Vref corresponding to the input terminal of the operational amplifier OP5 can also be used to adjust the reference voltage or bias voltage of the output signal of the operational amplifier OR5; and the reference voltage signal Vref corresponding to the input terminal of the operational amplifier OP4, OP6, and the comparator CMP can also be used to adjust the corresponding reference voltage. The specific value of the reference voltage signal Vref can be set according to the actual usage, and the embodiment of the present invention is not limited to this.

[0101] In the CNTQ algorithm, the upper threshold V1 of the comparator CMP2 and the lower threshold V2 of the comparator CMP3 are used to limit the final output square wave signal B2 of the same frequency between two fixed peak voltages Vx and Vy. The transmitter of the wireless charging system can obtain the CNT between Vx and Vy through the number of flips of the square wave signal B2 of the same frequency, and finally calculate the Q value.

[0102] Taking Vx=2.8V, Vy=0.08V as an example, the calculation process of the minimum change of Q is: Q= , and assuming Figure 4 The no-load quality factor of the foreign object detection circuit shown is about 23. At this time, the minimum resolution of the CNTQ algorithm is a change of one CNT, with a resolution of 3.8% (0.88 / 23). When the rate of change of the Q value caused by the intrusion of foreign objects is less than 3.8%, the CNTQ algorithm cannot recognize it.

[0103] Based on the foreign body detection method provided by the aforementioned embodiment of the present invention, the above Figure 4The operational amplifiers OP4 and OP5 in the embodiment can also proportionally reduce the attenuated oscillation signal to obtain a low-frequency oscillation signal B3. The oscillation signal B3 and the square wave signal B2 of the same frequency can be applied to the foreign body detection method in the embodiment of the present invention. The operational amplifiers OP4 and OP6 reduce the oscillation signal in order to obtain the square wave signal B2. In addition, the output end of the operational amplifier OP6 can usually be connected to a peak detection circuit, such as a Figure 4 The dotted line portion in the middle outputs the peak value Vpeak to the comparators CMP2 and CMP3. The specific foreign matter detection circuit can also be set according to actual usage, and the embodiment of the present invention is not limited to this.

[0104] Specifically, an aluminum ring was used to conduct a comparative test on the quality factors of the two methods. Under the same hardware and the same metal foreign matter, the aluminum ring was moved laterally from the position of (0, 0, 5) mm until it could not be recognized.

[0105] The results are as follows Figure 5 As shown, Figure 5 In the quality factor comparison diagram shown, the horizontal axis represents the moving distance of the foreign matter, the vertical axis represents the change ratio of the quality factor, the circular pattern represents the change ratio of the quality factor under the traditional CNTQ algorithm, and the triangular pattern represents the change ratio of the quality factor of the foreign matter detection method in the embodiment of the present invention.

[0106] Among them, the above Figure 4 Under the corresponding CNTQ algorithm, the quality factor Q value shows a step change, and the movement of the aluminum ring causes a change of at least 4% in the quality factor Q value, for example Figure 5 In the figure, when the aluminum ring moves to ±16mm, the Q value changes by 4.1%, which is unrecognizable.

[0107] In the foreign body detection method in the embodiment of the present invention, the quality factor Q changes continuously with the movement distance of the aluminum ring, and the minimum resolution can reach less than 1%. The Q value of the foreign body detection method in the embodiment of the present invention changes by 8.3% when the aluminum ring moves to ±16mm, and the change rate reaches 4.2% when it moves to ±20mm. The test results show that the foreign body detection method in the embodiment of the present invention has a significantly stronger foreign body recognition capability than the CNTQ algorithm in the related art.

[0108] Therefore, compared with the CNTQ algorithm in the related art, in which the minimum CNT change is 1, in the foreign body detection method in the embodiment of the present invention, since both Vx and Vy can follow the change of foreign bodies, the actual quality factor Q can be restored with higher resolution, and the foreign body recognition capability under harsh working conditions such as tiny foreign bodies and foreign bodies at the edge of the coil can be enhanced. In terms of the stability, accuracy and resolution of the quality factor Q, the foreign body detection method in the embodiment of the present invention is superior to the traditional CNTQ algorithm in the related art.

[0109] Further, based on the above embodiment, the embodiment of the present invention also provides a foreign body detection device, which is applied to the transmitting end of the wireless charging system, such as Figure 6 The structure diagram of a foreign body detection device is shown in FIG. The foreign body detection device comprises:

[0110] The acquisition module 60 is used to acquire an oscillation signal of a transmitter of the wireless charging system in response to the wireless charging system being started; wherein the oscillation signal is generated by a resonant circuit of the transmitter;

[0111] A processing module 62, configured to perform operational amplifier processing on the oscillation signal to obtain a target oscillation signal corresponding to the oscillation signal;

[0112] A sampling module 64 is used to sample the target oscillation signal according to a pre-configured sampling period to obtain a plurality of sampling signals contained in the sampling period;

[0113] Extracting signal 66, used to extract peak signals and valley signals contained in the plurality of sampling signals, and calculate the quality factor corresponding to the resonant circuit based on the peak signals and the valley signals;

[0114] The detection module 68 is used to perform foreign object detection at the transmitting end based on the quality factor.

[0115] The foreign matter detection device provided in the embodiment of the present invention has the same technical features as the foreign matter detection method provided in the above embodiment, and therefore can also solve the same technical problems and achieve the same technical effects.

[0116] Furthermore, an embodiment of the present invention also provides a wireless charging system, which includes a transmitter; wherein a controller of the transmitter is configured with the above-mentioned foreign object detection device.

[0117] Furthermore, the wireless charging system in the embodiment of the present invention also includes a receiving end, and the transmitting end is used to couple electric energy to the receiving end to wirelessly charge the load of the receiving end.

[0118] Specifically, the transmitting end includes a transmitting coil, a resonant circuit connected to the transmitting coil, and a foreign object detection circuit connected to the resonant circuit; the resonant circuit and the foreign object detection circuit are both connected to a controller of the transmitting end.

[0119] Furthermore, the foreign object detection circuit includes an operational amplifier processing circuit and a frequency measurement circuit connected to the operational amplifier processing circuit; wherein the operational amplifier processing circuit is used to obtain the oscillation signal generated by the resonant circuit, perform operational amplifier processing on the oscillation signal, and obtain a target oscillation signal corresponding to the oscillation signal; the frequency measurement circuit is used to generate a trigger signal that matches the frequency of the oscillation signal, so as to measure the frequency of the oscillation signal based on the trigger signal.

[0120] Specifically, the operational amplifier processing circuit and the frequency measurement circuit can refer to Figure 1 The foreign body detection circuit shown will not be described in detail here.

[0121] The computer program product of the foreign object detection method, device and wireless charging system provided in the embodiments of the present invention includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the method described in the previous method embodiments. The specific implementation can be found in the method embodiments, which will not be repeated here.

[0122] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0123] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0124] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0125] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0126] Finally, it should be noted that the above embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that any person skilled in the art can still modify the technical solutions recorded in the above embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A foreign body detection method, characterized in that: Applied to the transmitter of a wireless charging system, the method comprises: In response to the wireless charging system being started, an oscillation signal of a transmitter of the wireless charging system is obtained; wherein the oscillation signal is generated by a resonant circuit of the transmitter; Performing operational amplifier processing on the oscillation signal to obtain a target oscillation signal corresponding to the oscillation signal; Sampling the target oscillation signal according to a preconfigured sampling period to obtain a plurality of sampling signals contained in the sampling period; Extracting peak signals and valley signals contained in the plurality of sampling signals, and calculating a quality factor corresponding to the resonant circuit based on the peak signals and the valley signals; Performing foreign object detection at the transmitting end based on the quality factor; Wherein, the transmitting end of the wireless charging system is configured with a frequency measurement circuit; the frequency measurement circuit is used to generate a trigger signal matching the frequency of the oscillation signal to measure the frequency of the oscillation signal; The step of sampling the target oscillation signal according to a preconfigured sampling period further includes: A sampling period is configured based on the trigger signal, so as to sample the target oscillation signal based on the sampling period under the triggering of the trigger signal; wherein the step of configuring the sampling period based on the trigger signal comprises: configuring the sampling frequency of the sampling period to be a multiple frequency of the trigger signal based on the frequency of the trigger signal; or configuring the frequency of the trigger signal to be the sampling frequency of the sampling period; Specifically, the step of sampling the target oscillation signal based on the sampling period includes: If the sampling frequency of the sampling period is a multiple frequency of the trigger signal, then based on the sampling frequency of the multiple frequency, the positive half-wave signal value and the negative half-wave signal value of the target oscillation signal are collected in each signal period; Determine the positive half-wave signal value as the peak signal, and determine the negative half-wave signal value as the valley signal; or, If the sampling frequency of the sampling period is the frequency of the trigger signal, then in each sampling period, a plurality of sampling signals are collected based on the sampling frequency; The maximum value of the sampled signal is determined as the peak signal, and the minimum value of the sampled signal is determined as the valley signal.

2. The method according to claim 1, characterized in that: The step of sampling the target oscillation signal according to a preconfigured sampling period includes: Sampling the peak signal and the trough signal of the target oscillation signal in each signal cycle to obtain a sampling signal including the peak signal and the trough signal; The peak signal is determined as the peak signal, and the valley signal is determined as the valley signal.

3. The method according to claim 1, characterized in that The method further comprises: Acquire the frequency of the oscillation signal measured by the frequency measurement circuit; Performing frequency compensation on the quality factor based on the frequency of the oscillation signal to obtain a compensated quality factor; Foreign object detection is performed at the transmitting end based on the compensated quality factor.

4. A foreign body detection device, characterized in that: Applied to the transmitting end of a wireless charging system, the device comprises: An acquisition module, configured to acquire an oscillation signal of a transmitter of the wireless charging system in response to the wireless charging system being started; wherein the oscillation signal is generated by a resonant circuit of the transmitter; A processing module, used for performing operational amplifier processing on the oscillation signal to obtain a target oscillation signal corresponding to the oscillation signal; A sampling module, used for sampling the target oscillation signal according to a pre-configured sampling period to obtain a plurality of sampling signals contained in the sampling period; Extracting signals, used to extract peak signals and valley signals contained in the plurality of sampling signals, and calculating the quality factor corresponding to the resonant circuit based on the peak signals and the valley signals; A detection module, configured to perform foreign object detection at the transmitting end based on the quality factor; Wherein, the transmitting end of the wireless charging system is configured with a frequency measurement circuit; the frequency measurement circuit is used to generate a trigger signal matching the frequency of the oscillation signal to measure the frequency of the oscillation signal; The step of sampling the target oscillation signal according to a preconfigured sampling period further includes: A sampling period is configured based on the trigger signal, so as to sample the target oscillation signal based on the sampling period under the triggering of the trigger signal; wherein the step of configuring the sampling period based on the trigger signal comprises: configuring the sampling frequency of the sampling period to be a multiple frequency of the trigger signal based on the frequency of the trigger signal; or configuring the frequency of the trigger signal to be the sampling frequency of the sampling period; Specifically, the step of sampling the target oscillation signal based on the sampling period includes: If the sampling frequency of the sampling period is a multiple frequency of the trigger signal, then based on the sampling frequency of the multiple frequency, the positive half-wave signal value and the negative half-wave signal value of the target oscillation signal are collected in each signal period; Determine the positive half-wave signal value as the peak signal, and determine the negative half-wave signal value as the valley signal; or, If the sampling frequency of the sampling period is the frequency of the trigger signal, then in each sampling period, a plurality of sampling signals are collected based on the sampling frequency; The maximum value of the sampled signal is determined as the peak signal, and the minimum value of the sampled signal is determined as the valley signal.

5. A wireless charging system, characterized in that: The wireless charging system comprises a transmitting end; Wherein, the controller of the transmitting end is configured with the foreign object detection device described in claim 4.

6. The wireless charging system according to claim 5, characterized in that: The transmitting end includes a transmitting coil, a resonant circuit connected to the transmitting coil, and a foreign object detection circuit connected to the resonant circuit; The resonant circuit and the foreign object detection circuit are both connected to the controller of the transmitting end.

7. The wireless charging system according to claim 6, characterized in that: The foreign body detection circuit includes an operational amplifier processing circuit and a frequency measurement circuit connected to the operational amplifier processing circuit; The operational amplifier processing circuit is used to obtain the oscillation signal generated by the resonant circuit, perform operational amplifier processing on the oscillation signal, and obtain a target oscillation signal corresponding to the oscillation signal; The frequency measurement circuit is used to generate a trigger signal matching the frequency of the oscillation signal, so as to measure the frequency of the oscillation signal based on the trigger signal.

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