Detection circuit, wireless transmission device and object detection method

Abstract

The invention provides a detection circuit, wireless transmission equipment and an object detection method. The detection circuit comprises a frequency generator, a driving circuit, a resonance circuit and a controller. The frequency generator is used for generating square wave signals. The driving circuit is connected with the output end of the frequency generator and used for amplifying the square wave signal. The resonance circuit is connected with the output end and the input end of the drive circuit and used for converting the square wave signal into an oscillation signal. And the controller is connected with the resonance circuit and is used for determining the quality factor of the resonance circuit according to the voltage of the oscillation signal so as to determine whether an object is detected. Whether the foreign matter exists near the wireless transmission equipment or not can be simply and quickly detected, and meanwhile, the power consumption is low and the reliability is high.

Description

Technical Field

[0001] This application relates to the field of wireless transmission technology, and in particular to a detection circuit, a wireless transmission device, and a method for object detection. Background Technology

[0002] With the increasing development of wireless transmission technology, its applications are becoming more and more widespread due to its good functionality, high reliability, security, long service life, and contactless and wear-free characteristics.

[0003] However, wireless transmission also has disadvantages compared to wired transmission. If foreign objects appear around the wireless power transmission coil, it can cause the temperature of the wireless transmission device to rise sharply, potentially leading to damage.

[0004] Currently, there are many methods for detecting foreign objects in wireless charging receivers. For example, using a temperature sensor to detect abnormally high-temperature areas on the surface of a wireless charging device has the advantage of high adaptability, but the disadvantages are high cost and complex implementation. Another method is to detect the presence of foreign objects by measuring the current of the wireless charging device. This method can detect the presence of foreign objects to a certain extent and prevent the system temperature from rising; however, this method has low reliability. Furthermore, both of these methods detect objects during energy transmission, resulting in high energy consumption and cost. Summary of the Invention

[0005] This application provides a simple, fast, low-power, and highly reliable detection circuit, wireless transmission device, and object detection method.

[0006] This application provides a detection circuit, including:

[0007] A frequency generator is used to generate square wave signals.

[0008] A driving circuit, connected to the output of the frequency generator, is used to amplify the square wave signal;

[0009] A resonant circuit, connected to the output and input terminals of the driving circuit, is used to convert the square wave signal into an oscillating signal; and

[0010] A controller, connected to the resonant circuit, is used to determine the quality factor of the resonant circuit based on the voltage of the oscillation signal, and thus determine whether an object has been detected.

[0011] Optionally, the detection circuit further includes a sampling circuit connected to the resonant circuit and the controller; the sampling circuit is used to acquire the oscillation period of the oscillation signal and two sets of voltage values ​​of the oscillation signal separated by one oscillation period; the controller is used to: determine the quality factor of the resonant circuit based on the two sets of voltage values, and then determine whether an object is detected.

[0012] Optionally, the formula for calculating the quality factor of the resonant circuit is:

[0013]

[0014] Where Q is the quality factor of the resonant circuit, α is the attenuation factor, and v C (t) and v C (t+T) represents the two sets of voltage values.

[0015] Optionally, the frequency generator is used to generate multiple square wave signals with the resonant frequency of the resonant circuit as the center and a preset frequency as the step.

[0016] Optionally, the detection circuit includes a ground terminal and a reference voltage terminal; the resonant circuit includes:

[0017] capacitance;

[0018] The first resistor is connected in series with the capacitor between the output and input terminals of the driving circuit;

[0019] The second resistor is connected in series with the capacitor and the first resistor between the output terminal of the driving circuit and the ground terminal; and

[0020] The third resistor connects the input terminal of the driving circuit and the reference voltage terminal.

[0021] Optionally, the detection circuit further includes a filtering circuit connected to the resonant circuit and the controller, used to filter the oscillation signal; the controller is used to determine the quality factor of the resonant circuit based on the voltage value of the filtered oscillation signal.

[0022] This application provides a wireless transmission device, including:

[0023] The detection circuit as described in any of the above; and

[0024] An energy transmission circuit is connected to the controller; the controller is used to: if an object is detected, control the energy transmission circuit to transmit energy to the object, and confirm the category of the object based on the feedback signal sent by the object; the category includes receiving devices and foreign objects.

[0025] This application also provides an object detection method, including:

[0026] Multiple square wave signals are generated by taking the resonant frequency of a resonant circuit as the center and the preset frequency as the step.

[0027] The multiple square wave signals are converted into oscillating signals through a resonant circuit;

[0028] Acquire the voltage value of the oscillation signal;

[0029] The quality factor of the resonant circuit is determined based on the voltage value.

[0030] If the quality factor is not less than a predetermined quality factor threshold, it is determined that no object was detected;

[0031] If the quality factor is less than the quality factor threshold, it is determined that an object has been detected.

[0032] Optionally, after determining that an object has been detected, the object detection method further includes:

[0033] Energy is transferred to the object;

[0034] If a feedback signal is received from the object, the object is determined to be a receiving device.

[0035] If no feedback signal is received from the object, the object is determined to be a foreign object.

[0036] Optionally, the quality factor threshold is predetermined through the following steps:

[0037] In the absence of any object, multiple square wave signals are generated with the resonant frequency of the resonant circuit as the center and a preset frequency as the step.

[0038] The resonant circuit converts the plurality of square wave signals into oscillating signals.

[0039] Acquire the voltage value of the oscillation signal;

[0040] Based on the voltage value, the quality factor of the resonant circuit is determined and used as the quality factor threshold.

[0041] In some embodiments, a frequency generator produces a square wave signal, a resonant circuit converts the square wave signal into an oscillation signal, and a controller determines the quality factor of the resonant circuit based on the voltage of the oscillation signal. Since the presence of foreign objects near the detection circuit will produce different energy attenuations and generate different oscillation signals, the degree of energy attenuation can be determined based on the quality factor of the oscillation signal, thereby determining whether an object has been detected near the detection circuit. By measuring the voltage of the oscillation signal and calculating the quality factor, objects can be detected simply, quickly, with low power consumption and high reliability.

[0042] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0043] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0044] Figure 1 The diagram shown is a circuit diagram of one embodiment of the detection circuit of this application.

[0045] Figure 2 As shown Figure 1 The diagram shows the signal output by the frequency generator and drive circuit.

[0046] Figure 3 The diagram shown is a waveform of an embodiment of the oscillation signal when there are no objects near the detection circuit.

[0047] Figure 4 The diagram shown is a waveform of an embodiment of the oscillation signal when an object is present near the detection circuit.

[0048] Figure 5 As shown Figure 1 A partial circuit diagram of another embodiment of the detection circuit shown.

[0049] Figure 6 The diagram shown is a flowchart of an embodiment of the object detection method provided in this application. Detailed Implementation

[0050] This application provides a detection circuit, a wireless transmission device, and an object detection method. The detection circuit, wireless transmission device, and object detection method of this application will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the features of the following embodiments and implementations can be combined with each other.

[0051] Figure 1 The diagram shown is a circuit diagram of one embodiment of the detection circuit 10 of this application. Figure 1 As shown, the detection circuit 10 includes: a frequency generator 11, a drive circuit 12, a resonant circuit 13, and a controller 14.

[0052] Frequency generator 11 is used to generate square wave signals. Frequency generator 11 is the signal source for detection circuit 10. Frequency generator 11 can be configured to generate square wave signals of a fixed frequency. Frequency generator 11 can be configured to generate multiple square wave signals of different frequencies. Frequency generator 11 can be implemented in various ways, such as using a crystal oscillator, a 555 timer circuit, or the PWM (pulse width modulation) function of a microcontroller.

[0053] In some embodiments, the frequency generator 11 is used to generate multiple square wave signals with the resonant frequency of the resonant circuit 13 as the center and a preset frequency as the step.

[0054] The resonant circuit 13 has a resonant frequency. The preset frequency can be pre-set according to the usage scenario of the detection circuit 10. The frequency generator 11 is used to generate a square wave signal with the resonant frequency of the resonant circuit 13. The frequency generator 11 is also used to generate multiple square wave signals within a preset time period, the frequencies of which are respectively: the resonant frequency plus or minus n preset frequencies. Through frequency scanning, the above multiple square wave signals are superimposed together and input to the drive circuit 12.

[0055] The drive circuit 12 is connected to the output terminal of the frequency generator 11 and is used to amplify the square wave signal.

[0056] The driving circuit 12 amplifies the square wave signal, increasing the energy carried by the signal to ensure sufficient power to drive the subsequent resonant circuit 13. In some embodiments, the driving circuit 12 includes an operational amplifier and a transistor. In some embodiments, the driving circuit 12 includes a MOSFET. The frequency generator 11 generates different square wave signals, requiring different driving circuits 12 to be adapted.

[0057] Figure 2 As shown Figure 1 The diagram shows the signals output by the frequency generator 11 and the drive circuit 12. Waveform A is the square wave signal output by the frequency generator 11, and waveform B is the square wave signal amplified by the drive circuit 12. It can be seen that the drive circuit 12 amplifies the amplitude of the square wave signal generated by the frequency generator 11, giving it more energy to drive the subsequent circuitry.

[0058] The resonant circuit 13 connects the output and input terminals of the drive circuit 12, and is used to convert the square wave signal into an oscillating signal. The resonant circuit 13 includes a capacitor and / or an inductor. Figure 1 In the illustrated embodiment, the resonant circuit 13 consists of a capacitor and an inductor. When a square wave signal passes through the resonant circuit 13, the charge oscillates between the elements due to the action of the capacitor or inductor, thereby generating an oscillating signal. If there is no object near the detection circuit 10, the square wave signal will not experience energy attenuation after passing through the resonant circuit 13. If there is an object near the detection circuit 10, the square wave signal will experience energy attenuation after passing through the resonant circuit 13 due to interference from the object, and the frequency or amplitude of the resulting oscillation signal will change.

[0059] Figure 3 The diagram shown is a waveform of an embodiment of the oscillation signal when there is no object near the detection circuit 10.

[0060] Figure 4 The diagram shown is a waveform of an embodiment of the oscillation signal when an object is present near the detection circuit 10.

[0061] Depend on Figure 3 and Figure 4 It can be seen that when an object is present near the detection circuit 10, the amplitude of the oscillation signal decreases significantly. The amplitude change of the oscillation signal can be obtained through sampling by the sampling circuit 15. Therefore, by detecting the oscillation signal generated by the resonant circuit 13, it can be determined whether an object is present near the detection circuit 10.

[0062] The controller 14 is connected to the resonant circuit 13 and is used to determine the quality factor of the resonant circuit 13 based on the voltage of the oscillation signal, thereby determining whether an object has been detected.

[0063] The quality factor reflects the ability of the resonant circuit 13 to store and release energy at its resonant frequency, i.e., the energy level of the oscillation signal. When an object approaches the resonant circuit 13, the quality factor changes due to its influence on the circuit parameters.

[0064] The controller 14 is responsible for monitoring the voltage of the oscillation signal in the resonant circuit 13 and determining the quality factor of the resonant circuit based on this voltage. The quality factor is then used to determine whether an object exists near the detection circuit 10.

[0065] In some embodiments, the frequency generator 11 generates a square wave signal, the resonant circuit 13 converts the square wave signal into an oscillation signal, and the controller 14 determines the quality factor of the resonant circuit 13 based on the voltage of the oscillation signal. Since the presence of foreign objects near the detection circuit 10 will produce different energy attenuations and generate different oscillation signals, the degree of energy attenuation can be determined based on the quality factor of the oscillation signal, thereby determining whether an object has been detected near the detection circuit 10. By measuring the voltage of the oscillation signal and calculating the quality factor, objects can be detected simply, quickly, with low power consumption and high reliability.

[0066] The detection circuit 10 also includes a sampling circuit 15, connected to the resonant circuit 13 and the controller 14. The sampling circuit 15 is used to acquire the oscillation period of the oscillation signal and two sets of voltage values ​​separated by one oscillation period. The controller 14 is used to determine the quality factor of the resonant circuit 13 based on the two sets of voltage values, and thus determine whether an object has been detected.

[0067] The sampling circuit 15 can acquire the oscillation period of the oscillation signal and the voltage value of the oscillation signal to obtain the amplitude change of the oscillation signal fluctuation.

[0068] In some embodiments, the quality factor of the resonant circuit 13 is determined by formula (1).

[0069]

[0070] Where Q is the quality factor of resonant circuit 13, α is the attenuation factor, and v C (t) and v C(t+T) represents two sets of voltage values ​​of the oscillation signal separated by one oscillation cycle.

[0071] As can be seen from formula (1), when measuring the Q value, it is only necessary to confirm the period T of the damped oscillation, and then sample two voltage values ​​v at intervals of period T during the oscillation process. C (t) and v C The Q value can be calculated using (t+T).

[0072] The quality factor Q can also be determined by the energy stored in the resonant circuit 13 and the energy consumed in each oscillation cycle.

[0073] The amplitude and peak-to-peak value of the oscillation signal can directly reflect the energy status of the oscillation circuit. According to formula (1), the relationship between the amplitude and peak-to-peak value of the oscillation signal and the energy can be obtained, as shown in formula (2) and formula (3).

[0074]

[0075] Among them, v C (t) represents the initial voltage of the oscillation signal amplitude, v C (t+T) represents the amplitude value of the oscillation period T of the oscillation signal.

[0076]

[0077] Among them, v p-p (t) represents the initial voltage of the peak-to-peak oscillation signal, v C (t+T) represents the peak-to-peak value of the oscillation signal with an interval of oscillation period T.

[0078] As can be seen from formulas (2) and (3), the peak-to-peak value of the oscillation signal is consistent with the periodic decay of the amplitude value.

[0079] According to formula (1), As shown in Table 1, when the value of αT is less than 0.2, the relationship between αT and 1-e -αT They can be approximated as equal.

[0080] αT 1 0.5 0.3 0.2 0.18 0.16 0.14 0.12 0.1 <![CDATA[1-e -αT ]]> 0.632 0.393 0.259 0.181 0.165 0.148 0.131 0.113 0.095

[0081] Table 1

[0082] Therefore, formula (4) can be derived.

[0083]

[0084] That is, when Q is greater than 16, Q can be approximately calculated using formula (4).

[0085] After determining the quality factor of the resonant circuit 13 based on the voltage values ​​of the oscillation signals at intervals of oscillation cycles, since the quality factors corresponding to the presence or absence of an object near the detection circuit 10 are different, it is possible to determine whether an object has been detected based on the value of the quality factor.

[0086] The detection circuit 10 also includes a filter circuit 16, connected to the resonant circuit 13 and the controller 14, for filtering the oscillation signal. The controller 14 is used to determine the quality factor of the resonant circuit 13 based on the voltage value of the filtered oscillation signal.

[0087] The filter circuit 16 can remove noise and unwanted interference components from the oscillation signal, filtering out high-frequency noise and other spurious waves, making the oscillation signal purer and obtaining a smoother waveform curve, which is beneficial for subsequent processing and analysis of the oscillation signal. The controller 14 includes a voltage measurement module, which is used to measure the voltage value of the filtered oscillation signal, and then determine the quality factor of the resonant circuit 13 based on the voltage value.

[0088] Figure 5 As shown Figure 1 A partial circuit diagram of another embodiment of the detection circuit 10 shown.

[0089] like Figure 5 As shown, the detection circuit 10 includes a ground terminal GND and a reference voltage terminal V1. The resonant circuit 13 includes a capacitor C, a first resistor R1, a second resistor R2, and a third resistor R3.

[0090] The first resistor R1 and capacitor C are connected in series between the output and input terminals of the drive circuit 12.

[0091] The second resistor R2, along with the capacitor C and the first resistor R1, are connected in series between the output terminal of the drive circuit 12 and the ground terminal GND.

[0092] The third resistor R3 is connected to the input terminal of the drive circuit 12 and the reference voltage terminal V1.

[0093] Capacitor C can interact directly or indirectly with the object being detected. The presence of the object may change the capacitance of capacitor C or affect the electric field distribution in the circuit, thereby changing the resonant frequency or impedance of resonant circuit 13. The first resistor R1 is connected in series with capacitor C, forming a basic RC (resistor-capacitor) network. The RC network can affect the charging and discharging time constant of resonant circuit 13, thus affecting the response speed of resonant circuit 13 to external changes. The second resistor R2, connected in series with capacitor C and the first resistor R1, is connected between the output terminal of drive circuit 12 and ground terminal GND. It is used to divide the voltage of the first resistor R1, preventing excessive energy from being allocated to it. Furthermore, the second resistor R2 also acts as a current limiter, preventing damage to circuit components under certain conditions (e.g., short circuit). The third resistor R3 is connected between the input terminal of drive circuit 12 and the reference voltage terminal V1. The third resistor R3 can be used to set the bias voltage of resonant circuit 13, ensuring that resonant circuit 13 operates within its normal operating range.

[0094] By selecting appropriate capacitor C, first resistor R1, second resistor R2, and third resistor R3, such as Figure 5 The resonant circuit 13 shown can generate a stable oscillation signal, maintain a stable output of the oscillation signal, and generate an oscillation signal waveform that is easy to calculate the quality factor.

[0095] This application also provides a wireless transmission device, including: the detection circuit 10 and the power transmission circuit as described above.

[0096] The energy transfer circuit is connected to the controller 14. The controller 14 is used to: control the energy transfer circuit to transfer energy to the object if an object is detected, and confirm the object's category based on the feedback signal sent by the object; the category includes receiving devices and foreign objects.

[0097] The wireless transmission device is used to transmit energy to the receiving device. The detection circuit 10 is used to detect the presence of objects near the wireless transmission device. The energy transmission circuit is used to transmit energy to the objects. When the object is the receiving device, the energy transmission circuit transmits energy to the receiving device, charging it. When the object is a foreign object, the energy transmission circuit transmitting energy to the foreign object will cause an anomaly in the wireless transmission device, so this should be prevented. When the detection circuit 10 detects an object, the energy transmission circuit transmits energy to the object. The receiving device and the foreign object have different feedback signals. The controller 14 determines whether the object is a receiving device or a foreign object based on these feedback signals. If the object is a receiving device, the energy transmission circuit can transmit energy to it normally; if the object is a foreign object, the energy transmission circuit stops transmitting energy to it. Since the energy transmission circuit transmits only a small amount of energy before receiving the feedback signal, it can quickly identify the type of object before the wireless transmission device generates a large amount of heat, reducing power consumption and preventing abnormal heating caused by foreign objects, thus protecting the wireless transmission device.

[0098] In some embodiments, the resonant circuit 13 adopts, for example... Figure 5 The circuit shown. The rated parameters of capacitor C, first resistor R1, second resistor R2, and third resistor R3 are determined based on the rated parameters of the energy transfer circuit. The rated parameters of capacitor C, first resistor R1, second resistor R2, and third resistor R3 determine whether the resonant circuit 13 can generate a stable oscillation signal and whether the detection circuit 10 can accurately detect nearby objects. Since, after detecting an object, it is necessary to determine the specific category of the object based on the feedback signal sent by the object in response to the signal of the energy transfer circuit, the rated parameters of capacitor C, first resistor R1, second resistor R2, and third resistor R3 need to match the rated parameters of the energy transfer circuit to meet the capability of detecting receiving devices adapted to the energy transfer circuit. Among them, the rated parameters of capacitor C include rated voltage, capacitance, temperature coefficient, etc. The rated parameters of first resistor R1, second resistor R2, and third resistor R3 include rated power, resistance value, temperature coefficient, etc. The rated parameters of the energy transfer circuit include operating voltage and operating current, power requirements, frequency characteristics, etc. In some embodiments, the rated voltage and rated power of capacitor C, first resistor R1, second resistor R2, and third resistor R3 are determined based on the operating voltage and current range of the energy transfer circuit. The power to be shared by first resistor R1, second resistor R2, and third resistor R3 is determined based on the power requirements of the energy transfer circuit, thereby determining appropriate resistance values. The capacitance of capacitor C and the resistance values ​​of first resistor R1, second resistor R2, and third resistor R3 are determined based on the frequency characteristics of the energy transfer circuit.

[0099] Figure 6 The diagram shown is a flowchart of an embodiment of the object detection method 20 provided in this application.

[0100] The detection circuit 10 of this application is used to execute the object detection method 20.

[0101] The object detection method 20 includes steps 21 to 27.

[0102] Step 21: Using the resonant frequency of a resonant circuit as the center and a preset frequency as the step, generate multiple square wave signals.

[0103] The resonant circuit has a resonant frequency. The preset frequency can be pre-set according to the application scenario of the object detection method 20. Multiple square wave signals are generated, and the frequencies of these square wave signals are respectively: the resonant frequency plus or minus n preset frequencies. The above multiple square wave signals are superimposed and output together.

[0104] Step 22: Convert multiple square wave signals into oscillating signals using a resonant circuit.

[0105] A resonant circuit includes either a capacitor or an inductor. When a square wave signal passes through the resonant circuit, the charge oscillates between the capacitors or inductors, generating an oscillation signal. The frequency and amplitude of the oscillation signal vary with the frequency of the input square wave signal, reaching their maximum amplitude near the resonant frequency. The presence of an object near the detection circuit 10 affects the resonant frequency and amplitude of the resonant circuit, resulting in different oscillation signals.

[0106] Step 23: Collect the voltage value of the oscillation signal.

[0107] The voltage value reflects the response strength of the resonant circuit at different frequencies.

[0108] Step 24: Determine the quality factor of the resonant circuit based on the voltage value.

[0109] The quality factor reflects the ability of the resonant circuit 13 to store and release energy at the resonant frequency, i.e., the energy status of the oscillation signal. By substituting the voltage value of the collected oscillation signal into the formula (1) or formula (5) mentioned above, the quality factor of the resonant circuit under different scenarios can be determined.

[0110] Step 25: Determine whether the quality factor is less than the predetermined quality factor threshold.

[0111] The quality factor threshold is a preset value that determines whether an object's quality factor has been detected.

[0112] In some embodiments, the quality factor threshold is predetermined by the following steps: in the absence of an object, multiple square wave signals are generated with the resonant frequency of the resonant circuit as the center and a preset frequency as the step; the multiple square wave signals are converted into oscillation signals by the resonant circuit; the voltage value of the oscillation signal is collected; and the quality factor of the resonant circuit is determined based on the voltage value as the quality factor threshold.

[0113] In the absence of an object, the quality factor is measured according to the methods shown in steps 21 to 24. The quality factor at this time corresponds to the absence of an object near the detection circuit 10, and this quality factor is used as the quality factor threshold. Based on experience and multiple experiments, it can be found that the quality factor is greater than 16 when no object is present. Therefore, the quality factor threshold can be obtained through formula (5).

[0114] In some embodiments, the method shown in steps 21 to 24 is repeated to measure multiple quality factors, and the average value of the multiple quality factors is taken as the quality factor threshold. This can eliminate the possibility that a single test cannot accurately measure the quality factor, thereby improving the reliability and accuracy of the quality factor threshold.

[0115] Step 26: If the quality factor is not less than the predetermined quality factor threshold, it is determined that no object was detected.

[0116] Step 27: If the quality factor is less than the quality factor threshold, it is determined that an object has been detected.

[0117] As mentioned earlier, the presence of an object causes energy loss in the resonant circuit, resulting in a decrease in the quality factor of the oscillation signal generated by the circuit. If the quality factor is high, not less than the quality factor threshold, it indicates low energy loss in the resonant circuit, suggesting that no object is approaching or affecting it; therefore, it is determined that no object was detected. If the quality factor is below the quality factor threshold, it means that the energy loss of the resonant circuit has increased, possibly due to the proximity of an external object altering the circuit's electrical characteristics (such as inductance or capacitance), thus affecting the resonant frequency and quality factor. Therefore, it is determined that an object was detected.

[0118] The object detection method 20 can quickly and reliably detect the presence of an object near the detection circuit 10 using a non-contact method and a relatively simple circuit.

[0119] In some embodiments, after determining that an object has been detected, the object detection method 20 further includes: transmitting energy to the object; if a feedback signal from the object is received, determining that the object is a receiving device; if no feedback signal from the object is received, determining that the object is a foreign object.

[0120] After confirming the presence of an object, it's necessary to further determine its category: is it a receiving device or a foreign object? If it's a receiving device, energy can be transmitted normally. If it's a foreign object, energy transmission must be stopped immediately to avoid malfunctions in the wireless transmission device. Different types of objects produce different feedback signals for energy transmission. Receiving devices generate feedback signals and send them to detection circuit 10 due to direct reflection, absorption followed by re-radiation, specific frequency response, or return signals based on energy transmission protocols. Foreign objects, however, do not generate effective feedback signals. This difference can be used to distinguish the object's category. Energy transmission is initiated for the object, and its feedback signal is monitored in real time. If a feedback signal is received, the object is considered a receiving device. If no feedback signal is received, the object does not meet the characteristics of a receiving device and lacks the expected response capability for energy transmission; therefore, the object is considered a foreign object. Since the amount of energy to be transmitted before receiving a feedback signal is small, the object's category can be quickly confirmed before any anomalies occur, preventing anomalies caused by foreign objects.

Claims

1. A detection circuit, characterized by, The detection circuit comprises: a frequency generator for generating a square wave signal; a driving circuit connected to an output terminal of the frequency generator for amplifying the square wave signal; a resonance circuit connected to an output terminal and an input terminal of the driving circuit for converting the square wave signal into an oscillation signal; and a controller connected to the resonance circuit for determining a quality factor of the resonance circuit according to a voltage of the oscillation signal, and further determining whether an object is detected. The detection circuit further comprises a sampling circuit connected to the resonance circuit and the controller, the sampling circuit being configured to collect an oscillation period of the oscillation signal and two sets of voltage values of the oscillation signal separated by one oscillation period, and the controller being configured to determine the quality factor of the resonance circuit according to the two sets of voltage values, and further determine whether the object is detected.

2. The detection circuit of claim 1, wherein, The quality factor of the resonance circuit is calculated according to the following formula:

3. The detection circuit of claim 2, wherein, The frequency generator is configured to generate a plurality of square wave signals centered on a resonance frequency of the resonance circuit and stepped by a preset frequency. where Q is a quality factor of the resonant circuit, a is an attenuation factor, v C (t) and v C (t+T) are the two sets of voltage values.

4. The detection circuit of claim 1, wherein, The detection circuit comprises a ground terminal and a reference voltage terminal.

5. The detection circuit of claim 1, wherein, The resonance circuit comprises: a capacitor; a first resistor connected in series with the capacitor between the output terminal and the input terminal of the driving circuit; a second resistor connected in series with the capacitor and the first resistor between the output terminal of the driving circuit and the ground terminal; and a third resistor connected between the input terminal of the driving circuit and the reference voltage terminal. The detection circuit further comprises a filter circuit connected to the resonance circuit and the controller, the filter circuit being configured to filter the oscillation signal, and the controller being configured to determine the quality factor of the resonance circuit according to a voltage value of the filtered oscillation signal.

6. The detection circuit of claim 1, wherein, The detection circuit comprises:

7. A wireless transmitting device, comprising: the detection circuit according to any one of claims 1-6; and an energy transmission circuit connected to the controller, the controller being configured to control the energy transmission circuit to transmit energy to the object if the object is detected, and determine a category of the object according to a feedback signal transmitted by the object, the category comprising a receiving device and a foreign object. The detection circuit comprises: generating a plurality of square wave signals centered on a resonance frequency of a resonance circuit and stepped by a preset frequency; 8. An object detection method characterized by, converting the plurality of square wave signals into oscillation signals through the resonance circuit; collecting voltage values of the oscillation signals; determining a quality factor of the resonance circuit according to the voltage values; determining that no object is detected if the quality factor is not less than a predetermined quality factor threshold; determining that an object is detected if the quality factor is less than the quality factor threshold. After determining that the object is detected, the object detection method further comprises: transmitting energy to the object; 9. The object detection method of claim 8, wherein, determining that the category of the object is a receiving device if a feedback signal of the object is received; and determining that the category of the object is a foreign object if no feedback signal of the object is received. The quality factor threshold is determined in advance by the following steps: generating a plurality of square wave signals centered on a resonance frequency of a resonance circuit and stepped by a preset frequency in the absence of an object; 10. The object detection method of claim 8, wherein, converting the plurality of square wave signals into oscillation signals through the resonance circuit; collecting voltage values of the oscillation signals; and determining a quality factor of the resonance circuit according to the voltage values. ​ determining a quality factor of the resonant circuit as the quality factor threshold value in dependence on the voltage value.

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