CN116191696A - Wireless charging device and foreign matter detection method, device, circuit and equipment thereof - Google Patents

Abstract

The application provides a wireless charging device and a foreign matter detection method, device, circuit and equipment thereof, wherein the method comprises the following steps: a damped oscillation signal processing circuit is applied to process a damped oscillation signal of the wireless power supply transmitter to be tested to obtain a corresponding pulse signal; determining two target amplitudes of the damped oscillation signal and a target period number between the two target amplitudes according to the pulse signal; determining the current oscillation frequency and the current quality factor of the wireless power supply transmitter to be tested based on the two target amplitude values and the target cycle number; and determining whether foreign matters exist in the working range of the wireless power supply transmitter to be detected based on the current oscillation frequency, the current quality factor, the preset standard quality factor and the preset standard oscillation frequency. The method and the device can output the pulse signal which accurately reflects the damped oscillation signal of the wireless power transmitter, so that the current quality factor and the current oscillation frequency of the wireless power transmitter can be calculated based on the pulse signal, and more accurate foreign matter detection can be realized.

Description

Wireless charging device and foreign object detection method, device, circuit and equipment thereof

Technical Field

The present application belongs to the field of wireless charging technology, and specifically relates to a wireless charging device and a foreign object detection method, device, circuit and equipment thereof.

Background Art

Wireless charging technology is a technology that uses the principle of magnetic resonance to charge devices without the help of wires. It is derived from wireless power transmission technology, which uses magnetic resonance to transmit charges in the air between the charger (wireless power transmitter) and the electronic device. The coil and capacitor of the charger form resonance between the charger and the device to achieve efficient transmission of electrical energy.

In the alternating electromagnetic field formed by the coil and the capacitor, if there is a metal foreign body, an eddy current effect will occur, generating a large amount of heat, causing abnormal charging process and even burning the electronic equipment being charged. Therefore, in the current wireless charging technology, wireless power transmitters all use foreign body detection modules. However, the current foreign body detection methods either use defective integration methods, or require the use of expensive chips, or require the construction of complex circuits. There is no unified, reliable, and cost-effective detection method, which has caused industry pain points.

Summary of the invention

The present application proposes a wireless charging device and a foreign object detection method, device, circuit and equipment thereof. The circuit can output a pulse signal that accurately reflects the damped oscillation signal of the wireless power transmitter, so as to calculate the current quality factor and current oscillation frequency of the wireless power transmitter based on the pulse signal, thereby achieving more accurate foreign object detection.

The first embodiment of the present application provides a damped oscillation signal processing circuit, including at least one group of voltage divider circuits and at least one group of pulse output circuits;

The voltage divider circuit comprises a first resistor, a third resistor and a voltage divider node, one end of the first resistor is connected to the second power supply voltage, and the other end is connected to the voltage divider node; one end of the third resistor is connected to the damped oscillation signal, and the other end is connected to the voltage divider node;

The pulse output circuit includes a second resistor, a transistor and a pulse output node, one end of the second resistor is connected to the first power supply voltage, and the other end is connected to the pulse output node; the base of the transistor is connected to the voltage divider node, and the collector and emitter of the transistor are respectively connected to the pulse output node and the common end.

In some embodiments of the present application, a clamping circuit is further included, one end of the clamping circuit is connected to the common end, and the other end is connected to the voltage dividing node, and the clamping circuit is used to clamp the circuit of the voltage dividing node to within a preset threshold.

In some embodiments of the present application, the clamping circuit includes a diode, an anode of the diode is connected to the common terminal, and a cathode of the diode is connected to the voltage dividing node.

In some embodiments of the present application, the damped oscillation signal processing circuit includes two groups of voltage divider circuits and two groups of pulse output circuits, and the two groups of voltage divider circuits have different threshold voltages; the threshold voltage represents the amplitude of the damped oscillation signal when the transistor is at a cut-off voltage.

An embodiment of the second aspect of the present application provides a chip on which the damped oscillation signal processing circuit described in the first aspect is integrated.

An embodiment of a third aspect of the present application provides a foreign object detection device for wireless charging, comprising:

The damped oscillation signal processing circuit described in the first aspect is used to process the damped oscillation signal of the wireless power transmitter to be tested to obtain a corresponding pulse signal;

A parameter calculation module, used to determine the current oscillation frequency and the current quality factor of the wireless power transmitter to be tested according to the pulse signal;

A foreign object detection module is used to determine whether there is a foreign object within the working range of the wireless power transmitter based on the current oscillation frequency, the current quality factor, and a preset standard quality factor and a preset standard oscillation frequency.

In some embodiments of the present application, a calibration module is also included, which is used to detect the actual voltage of the voltage divider node of the damped oscillation signal processing circuit when the pulse signal undergoes a logical change; and calibrate the threshold voltage of the damped oscillation signal processing circuit based on the actual voltage.

An embodiment of a fourth aspect of the present application provides a wireless charging device, including a wireless power transmitter, and also includes the foreign object detection device for wireless charging described in the third aspect.

The fifth aspect of the present application provides a wireless charging foreign object detection method, including:

Applying the damped oscillation signal processing circuit described in the first aspect to process the damped oscillation signal of the wireless power transmitter to be tested to obtain a corresponding pulse signal;

Determining two target amplitudes of the damped oscillation signal and a target number of cycles between the two target amplitudes according to the pulse signal;

Determining a current oscillation frequency and a current quality factor of the wireless power transmitter under test based on the two target amplitudes and the target number of cycles;

Based on the current oscillation frequency, the current quality factor, and a preset standard quality factor and a preset standard oscillation frequency, it is determined whether there is a foreign object within the working range of the wireless power transmitter to be tested.

In some embodiments of the present application, determining two target amplitudes of the damped oscillation signal and a target number of cycles between the two target amplitudes according to the pulse signal includes:

Determine two target moments according to the change edge of the pulse signal, the time difference between the two target moments being the target cycle number;

The amplitudes corresponding to the two target moments are determined as the two target amplitudes.

In some embodiments of the present application, determining two target moments according to the change edge of the pulse signal includes:

Determine the falling edge time and the rising edge time of each pulse signal generated by the damped oscillation signal according to the pulse signal;

Based on the falling edge moment and rising edge moment of the Mth pulse signal, and the falling edge moment and rising edge moment of the Nth pulse signal, the intermediate moment of generating the Mth pulse signal and the intermediate moment of generating the Nth pulse signal are determined as the two target moments respectively; M and N are two different natural numbers respectively.

In some embodiments of the present application, determining two target amplitudes of the damped oscillation signal and a target number of cycles between the two target amplitudes according to the pulse signal includes:

Determining the initial amplitude of the damped oscillation signal as one of the target amplitudes, and determining the threshold voltage for generating the pulse signal as another target amplitude;

The number of pulse signals generated by the pulse signal is determined as the target cycle number.

In some embodiments of the present application, the damped oscillation signal processing circuit includes two groups of voltage divider circuits and two groups of pulse output circuits, and the two groups of voltage divider circuits have different threshold voltages;

Determining two target amplitudes of the damped oscillation signal and a target number of cycles between the two target amplitudes according to the pulse signal comprises:

Determine the number of first pulse signals and the number of second pulse signals respectively generated by the two threshold voltages;

The two threshold voltages are determined as the two target amplitudes, and the difference between the first pulse signal number and the second pulse signal number is determined as the target cycle number.

In some embodiments of the present application, it also includes:

Detecting the actual voltage of the voltage-dividing node of the damped oscillation signal processing circuit when the pulse signal undergoes a logic change;

The threshold voltage of the damped oscillation signal processing circuit is calibrated based on the actual voltage.

An embodiment of the sixth aspect of the present application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method described in the fifth aspect when executing the computer program.

The embodiment of the seventh aspect of the present application provides a computer-readable storage medium on which a computer program is stored, and the program is executed by a processor to implement the method described in the fifth aspect.

The technical solution provided in the embodiments of the present application has at least the following technical effects or advantages:

The foreign body detection method provided in the embodiment of the present application can collect sufficient parameters based on the pulse signal output by the damped oscillation signal processing circuit, and calculate according to the physical meaning of the LC oscillation circuit to obtain a more accurate and reliable oscillation frequency and quality factor. And because the present embodiment can measure the oscillation frequency f, it can meet the "foreign body detection method based on the natural frequency of the system" in the 1.3 version of the Qi protocol, increasing the applicability of the foreign body detection method. In addition, because the present embodiment can measure the Q value and oscillation frequency f of the system, it can determine whether there is a metal foreign body within the alternating electromagnetic field of the wireless power transmitter, whether there is a possible power receiver, whether there is a receiving device and a metal foreign body coexisting, and even determine the degree of influence of foreign bodies on charging efficiency, etc., so as to achieve more detailed foreign body judgment.

BRIEF DESCRIPTION OF THE DRAWINGS

By reading the detailed description of the preferred embodiment below, various other advantages and benefits will become clear to those of ordinary skill in the art. The accompanying drawings are only used for the purpose of illustrating the preferred embodiment and are not considered to be limitations of the present application. In addition, the same reference symbols are used to represent the same components throughout the accompanying drawings.

In the attached picture:

FIG1 is a schematic diagram showing a damped oscillation signal generated by a second-order system constructed by a resonant capacitor and a transmitting coil of a wireless power transmitter in an embodiment of the present application;

FIG2 shows a schematic diagram of the structure of a damped oscillation signal processing circuit provided in an embodiment of the present application;

FIG3 is a schematic diagram showing a flow chart of a wireless charging foreign object detection method provided in an embodiment of the present application;

FIG4 shows a schematic diagram of a second-order system structure constructed by a resonant capacitor and a transmitting coil of a wireless power transmitter to be tested in an embodiment of the present application;

FIG5 is a schematic diagram of a damped oscillation curve when no load is applied in an embodiment of the present application;

FIG6 is a schematic diagram showing a damped oscillation curve in the presence of metal foreign matter in an embodiment of the present application;

FIG7 shows a damped oscillation curve after connecting to a wireless receiving device in one embodiment of the present application;

FIG8 is a schematic diagram showing the corresponding relationship between the output pulse signal _{T_OUT} , the input damped oscillation signal T_IN, and the voltage signal of the voltage division node in the embodiment of the present application;

FIG9 is a schematic diagram showing the relationship between the pulse signal output by the damped oscillation signal processing circuit and the damped oscillation signal in an embodiment of the present application;

FIG10 is a schematic diagram showing the structure of a foreign object detection device for wireless charging provided in an embodiment of the present application;

FIG11 is a schematic structural diagram of a foreign object detection device for wireless charging provided in another embodiment of the present application;

FIG12 shows a schematic structural diagram of an electronic device provided by an embodiment of the present application;

FIG. 13 shows a schematic diagram of a storage medium provided in an embodiment of the present application.

DETAILED DESCRIPTION

The exemplary embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by technicians in the field to which this application belongs.

When detecting foreign objects in wireless charging equipment, an indirect foreign object detection method of monitoring current, voltage and power can be used, or Q value detection, also known as quality factor detection, can be performed. Before charging, the Q value of the oscillation system of the wireless charging device is measured to determine whether there is a foreign object. Among them, Q = 2π* stored energy/energy consumed by one oscillation. In the current technical scheme, when calculating the Q value, only the relationship between the amplitude change of the damped oscillation and time is often measured, while the measurement of the oscillation frequency is ignored (or not collected due to technical limitations). However, for a wireless receiving device including an LC oscillation circuit, when there is a metal foreign object, after the metal foreign object is connected to the wireless receiving device, the frequency of the LC oscillation circuit will change, which will then affect the change of the Q value. Therefore, only calculating the Q value through the relationship between the amplitude change of the damped oscillation and time may cause a large deviation in the calculation result, making it impossible to accurately determine whether there is a metal foreign object.

In view of the fact that there is no unified, reliable and cost-effective foreign body detection method as mentioned above, the embodiments of the present application propose a wireless charging device and its foreign body detection method, device, damped oscillation signal processing circuit, electronic equipment and medium. The foreign body detection method is based on the damped oscillation signal processing circuit, and the execution body of the specific calculation and foreign body analysis and detection steps may include but is not limited to: MCU, FPGA, digital logic unit and other processing modules with digital logic processing functions. The damped oscillation signal processing circuit includes at least one group of voltage divider circuits and at least one group of pulse output circuits; wherein the voltage divider circuit includes a first resistor, a third resistor and a voltage divider node, one end of the first resistor is connected to the second power supply voltage, and the other end is connected to the voltage divider node; one end of the third resistor is connected to the damped oscillation signal, and the other end is connected to the voltage divider node. The pulse output circuit includes a second resistor, a transistor and a pulse output node, one end of the second resistor is connected to the first power supply voltage, and the other end is connected to the pulse output node; the base of the transistor is connected to the voltage divider node, and the collector and emitter of the transistor are respectively connected to the pulse output node and the common end. The damped oscillation signal processing circuit can process the damped oscillation signal of the wireless power transmitter to be tested and generate a corresponding pulse signal. By collecting and analyzing the pulse signal, the current oscillation frequency and quality factor of the wireless power transmitter to be tested can be determined, and then the calculated oscillation frequency and quality factor are compared with the preset oscillation frequency and quality factor. Based on the principle of the wireless power transmitter and the physical properties of metal, it can be determined whether there is foreign matter within the working range of the wireless power transmitter.

The embodiment of the present application constructs a second-order system based on the resonant capacitor and the transmitting coil of the wireless power transmitter. After a step signal is input into the system, a damped oscillation signal as shown in Figure 1 can be generated at one end of the transmitting coil in response to the step signal. When calculating the Q value, the damping coefficient ζ of the damped oscillation signal can be referred to to calculate the Q value. The specific calculation process is as follows:

Since the LC oscillation circuit is a second-order linear system, a differential equation can be established:

Wherein, R is the load of the second-order system, which may be but is not limited to an electronic device capable of wireless charging; L is the inductance of the transmitting coil, in Henry; C represents the capacitance value of the resonant capacitor, in Farad; U _C (t) represents the capacitor voltage of the resonant capacitor at time t, i(t) represents the current of the second-order system at time t, and U _in (t) represents the voltage of the second-order system at time t, that is, the amplitude of the damped oscillation signal.

Assuming the capacitor voltage is the output, after Laplace transform, the transfer function of the second-order system can be obtained:

And because of the resonance characteristics:

Get the function of a typical second-order system:

Among them, ζ is the damping coefficient; _ω0 is the resonant angular frequency of the damped oscillation signal; R is the load of the second-order system, which can be but is not limited to electronic devices capable of wireless charging; L is the inductance of the transmitting coil, in Henry; C represents the capacitance value of the resonant capacitor, in Farad.

Comparing the above formula with the definition of Q value, we can get (at resonance):

have to:

Furthermore, when calculating the Q value, the amplitude voltage attenuation curve of the damped oscillation signal from 1 to 0 can be proposed:

Take any two points t ₀ and t ₁ on the curve:

The calculation formula of damping coefficient and Q value can be obtained:

If we consider the periodicity of the sine curve, and take the peak points U _C1 and U _C2 on the damped wave U _C (t), the time interval between them is t ₁ -t ₀ =nT, then:

Based on the principle of wireless power transmitter and the physical properties of metal, it can be analyzed that over time, within the alternating electromagnetic field of the wireless power transmitter, the Q value and the oscillation frequency f will change as follows:

If there is no metal device in the alternating electromagnetic field, the Q value is the largest, and the oscillation frequency is determined by the natural oscillation frequency of the transmitter and remains unchanged;

If there is only metal foreign matter in the alternating electromagnetic field (inductive load), the Q value will be greatly reduced and the oscillation frequency will remain unchanged;

If there is only a wireless power receiver in the alternating electromagnetic field (with a capacitive load), the Q value will decrease slightly and the oscillation frequency will change (determined by the natural frequency of the wireless power receiver).

After calculating the above Q value and the oscillation frequency f=1/T, the above process can be applied to continuously collect and calculate the Q value and oscillation frequency f of the system, and further determine whether there is a metal foreign object within the alternating electromagnetic field of the wireless power transmitter, whether there is a possible power receiver, and even determine the degree of influence of the foreign object on the charging efficiency.

However, the amplitude and oscillation period of the damped oscillation signal are often difficult to detect and not easy to obtain directly. The damped oscillation signal processing circuit provided in this embodiment is used to process the damped oscillation signal of the wireless power transmitter to be tested and generate a corresponding pulse signal. By collecting and analyzing the pulse signal, the amplitude and oscillation period of the damped oscillation signal can be obtained.

The embodiments of the present application are described in detail below.

Embodiment 1

Please refer to Figure 2, which is a schematic diagram of the structure of the damped oscillation signal processing circuit provided in the embodiment of the present application. As shown in Figure 2, the circuit includes at least one group of voltage divider circuits and at least one group of pulse output circuits. Among them, the voltage divider circuit includes a first resistor R1, a third resistor R3 and a voltage divider node, one end of the first resistor R1 is connected to the second power supply voltage U2, and the other end is connected to the voltage divider node; one end of the third resistor R3 is connected to the damped oscillation signal, and the other end is connected to the voltage divider node. The pulse output circuit includes a second resistor R2, a transistor and a pulse output node, one end of the second resistor R2 is connected to the first power supply voltage U1, and the other end is connected to the pulse output node; the base of the transistor is connected to the voltage divider node, and the collector and emitter of the transistor are respectively connected to the pulse output node and the common end.

The voltage dividing node can be any node between the first resistor R1 and the third resistor R3, the pulse output node is used to output the pulse signal, and the common end can be understood as the zero reference voltage of the entire circuit. The first power supply voltage U1 and the second power supply voltage U2 are both system operating voltages (can be but not limited to 3.3V, 5V, etc.).

It should be noted that the damped oscillation signal processing circuit can be an analog circuit (referring to a circuit used to transmit, transform, process, amplify, measure and display analog signals), which can be specifically integrated into a discrete chip and implemented as a hardware peripheral of the MCU. When the MCU has high integration, it can also be directly integrated into the MCU chip to save additional chips. This embodiment does not make specific limitations on this.

As shown in FIG2 , the transistor can be specifically an NPN type. In this case, the base of the transistor is connected to the voltage-dividing node, the collector can be connected to the pulse output node, and the emitter is connected to the common terminal. In this way, only a very small current is needed to turn on the transistor. After the transistor is turned on, when the selected second resistor is relatively large, the voltage-dividing voltage of the second resistor is equivalent to the first power supply voltage, so that the pulse output node outputs a low level. When the transistor is cut off, no current passes through the second resistor, and the first power supply voltage can be output from the pulse output node in its entirety, so the pulse output node can output a high level.

For example, in the above transistor open-drain circuit, the first power supply voltage U1 = 3.30V, the second resistor R2 = 10kΩ, when the base current I _O = 0.33mA when the transistor is turned on, the cut-off voltage V _OFF = 0.63V.

When the voltage U _T1 of the voltage division node is equal to 3.3V, the output voltage U _OUT of the pulse output node is 0V, that is, a low level is output.

When the voltage U _T1 of the voltage division node is equal to 0V, the output voltage U _OUT of the pulse output node is 3.3V, that is, a high level is output.

It is assumed that the boundary voltage of the logic change (the output voltage changes from a low level to a high level, or from a high level to a low level) is the above-mentioned cut-off voltage V _OFF .

Then the ideal output logic of the transistor is (the relationship between U _T1 and U _OUT ):

Since when U _T1 <V _OFF , the overcurrent I _BE of the base and emitter is 0, then according to the currents passing through the first resistor R1 and the third resistor R3 being equal, the following formula can be obtained (where U2 is the second power supply voltage connected to the first resistor):

Then we can get:

Therefore, the logic threshold value V _TH of the amplitude voltage U _IN of the damped oscillation signal input to the system can also be called the threshold voltage of the circuit ₍ the relationship between U _IN and U _T1 ):

It can be further obtained that the relationship between the output pulse signal T _OUT (voltage value is U _OUT ), the input damped oscillation signal T _IN (voltage value is U _IN ) and the logic threshold V _TH is as follows:

At the same time, it can be found that R1 and R3 form a linear resistor network. The circuit complies with the voltage superposition principle, so that the test point T1 and the input signal T _IN are in a linear function relationship. By calculating and selecting R ₁ and R ₃ , the logic threshold V _TH can be set, and the threshold voltage of the circuit can be further adjusted. That is, when the threshold value of U _OUT changes, the voltage value of the input damped oscillation signal T _IN is U _IN .

It should be noted that FIG2 shows a connection mode in which the transistor is an NPN type, but this embodiment does not specifically limit the type of the transistor, and it can also be a PNP type, as long as the current outflow terminal is connected to the common terminal and the current inflow terminal is connected to the first power supply voltage, the cutoff and amplification functions of the transistor can be realized.

The damped oscillation signal processing circuit provided in the present embodiment has a simple structure and does not require integrated circuit devices such as operational amplifiers and comparators, but can accurately obtain a pulse signal corresponding to the damped oscillation signal, and then accurately calculate the target amplitude and target oscillation period of the damped oscillation signal, thereby determining the current oscillation frequency and quality factor of the wireless power transmitter to be tested, and then comparing the calculated oscillation frequency and quality factor with the preset oscillation frequency and quality factor. Based on the principle of the wireless power transmitter and the physical properties of metal, it can be determined whether there is a foreign object within the working range of the wireless power transmitter.

In some embodiments, the damped oscillation signal processing circuit also includes a clamping circuit, one end of which is connected to a common end and the other end is connected to a voltage divider node. The clamping circuit is used to clamp the circuit of the voltage divider node to within a preset threshold to prevent the negative voltage amplitude of the base connection from being too large and damaging the transistor.

The preset threshold value can be set according to the withstand voltage characteristic of the transistor so as to provide better protection for the transistor.

Specifically, the clamping circuit includes a diode, the positive electrode of the diode is connected to the common terminal, and the negative electrode is connected to the voltage dividing node. By applying the characteristics of the diode being forward conductive and reverse cutoff, the diode can be reversely connected to the above-mentioned voltage dividing node T1 to clamp the voltage at point T1 to within a preset threshold, which can protect the triode.

Furthermore, the damped oscillation signal processing circuit includes two groups of voltage dividers and two groups of pulse output circuits, and the two groups of voltage dividers have different threshold voltages; the threshold voltage represents the amplitude of the damped oscillation signal when the transistor is at the cut-off voltage. In this way, two pulse signals with different amplitudes can be obtained based on the input damped oscillation signal.

Embodiment 2

Based on the same concept as the damped oscillation signal processing circuit described above, this embodiment further provides a chip on which a damped oscillation signal processing circuit as described in any of the above embodiments is integrated.

Specifically, the chip can be a dedicated chip including the above-mentioned discrete devices, or can be an MCU integrated chip, as long as it can realize the function of the circuit and output a pulse signal corresponding to the damped oscillation signal.

The chip provided in this embodiment is based on the same concept as the above-mentioned damped oscillation signal processing circuit, so it can at least achieve the beneficial effects that the above-mentioned damped oscillation signal processing circuit can achieve, and any implementation of the above-mentioned damped oscillation signal processing circuit can be applied to the chip provided in this embodiment, which will not be repeated here.

Embodiment 3

Based on the same concept as the damped oscillation signal processing circuit described above, this embodiment further provides a wireless charging foreign object detection method, as shown in FIG3 , the method includes the following steps:

Step S1, using the damped oscillation signal processing circuit to process the damped oscillation signal of the wireless power transmitter to be tested, to obtain a corresponding pulse signal.

As shown in Figure 4, it is a schematic diagram of the second-order system structure constructed by the resonant capacitor and the transmitting coil of the wireless power transmitter to be tested in this embodiment. The damped oscillation signal generated when the second-order system is working can be collected at the TEST point in the figure. Among them, L is the transmitting coil, C is the resonant capacitor, SW1 and SW2 are the power supply voltages of the LC oscillation circuit respectively. Based on this system, the generation process of the damped oscillation signal is as follows:

1) In the initial balanced state, both SW1 and SW2 output 0V.

2) SW1 outputs 1V and SW2 outputs 0V to charge LC (a damped oscillation from 0 to 1 will occur).

3) Wait for 1ms until LC charging is complete and reaches equilibrium (no oscillation at this time);

4) SW1 and SW2 both output 0V to discharge LC (a damped oscillation from 1 to 0 will occur at this time).

The "1V" output by the above-mentioned SW1 is the amplitude of the step signal. In the wireless charging system, 1V to 9V can usually be selected.

It is understandable that the energy stored in the LC circuit of the wireless power transmitter is relatively fixed. The attenuation conditions under different conditions are shown in Figures 5 to 7 (the horizontal axis in the figure is time, in microseconds; the vertical axis is the voltage value, in volts), where Figure 5 is the damped oscillation curve when no-load, at which time only the bus resistance of the loop is consuming energy, and the oscillation amplitude decays relatively slowly. Figure 6 is the damped oscillation curve after connecting to the wireless receiving device. The receiving end induces current, which increases the consumption of one channel. The oscillation amplitude decays relatively faster, and the system resonant frequency changes. Figure 7 is the damped oscillation curve after connecting to a metal foreign body. When there is a metal foreign body, the foreign body end induces current. Since there is no capacitor in the loop and the resistance is small, the oscillation amplitude decays very quickly.

Based on the structure and principle of the damped oscillation signal processing circuit provided in the first embodiment, in this embodiment, the relationship between the logic threshold V _TH and the cut-off voltage V _OFF is:

It can be calculated that the relationship between the output pulse signal _{T_OUT} (voltage value is _UOUT ), the input damped oscillation signal T_IN (voltage value is _UIN ) and the logic threshold _VTH is as follows:

It can be obtained from the experiment that the corresponding relationship between the output pulse signal _{T_OUT} (voltage value is _UOUT ), the input damped oscillation signal T_IN (voltage value is _UIN ), and the voltage signal of the voltage division node is shown in FIG8 .

Step S2, determining two target amplitudes of the damped oscillation signal and a target number of cycles between the two target amplitudes according to the pulse signal.

The target amplitude may be the amplitude corresponding to any two moments in the attenuation process of the damped oscillation signal, as long as the target number of cycles between the two moments can be determined. The target number of cycles may be an integer or not, and this embodiment does not specifically limit this. In order to facilitate calculation and acquisition, this embodiment may select the amplitude corresponding to the peak moment of the damped oscillation signal as the target amplitude.

In some embodiments, step S2 may include the following processing: determining two target moments according to the changing edge of the pulse signal, the time difference between the two target moments being the target cycle number; determining the amplitudes corresponding to the two target moments as two target amplitudes.

This embodiment may use an MCU or other digital logic unit in combination with a clock to record the changing edge of the pulse signal output by the damped oscillation signal processing circuit. The time of the first falling edge is recorded as t _F1 , the time of the first rising edge is recorded as t _R1 , ... the time of the Nth falling edge is recorded as t _Fn , and the time of the Nth rising edge is recorded as t _Rn .

The relationship between the pulse signal output by the damped oscillation signal processing circuit and the damped oscillation signal is shown in Figure 9. The middle time between the rising edge and the falling edge of any pulse signal can be determined as the target time, and the amplitude corresponding to the target time is determined as the target amplitude.

Specifically, the falling edge moment and rising edge moment of each pulse signal generated by the damped oscillation signal can be determined according to the pulse signal. Then, based on the falling edge moment and rising edge moment of the Mth pulse signal and the falling edge moment and rising edge moment of the Nth pulse signal, the middle moment of generating the Mth pulse signal and the middle moment of generating the Nth pulse signal are determined as two target moments respectively; M and N are two different natural numbers respectively.

Since the damped oscillation curve is a sine wave, the relationship between the amplitude VA _n of the Nth cycle and the edge time t _Fn , t _Rn can be calculated by trigonometric function as follows, where the switching threshold V _TH and the oscillation period T have been calculated:

A complete damped oscillation curve will generate N pulses, and the corresponding amplitudes are calculated by taking the Nnth pulse and the Nth pulse as VA _Nn and VA _N. For example, the corresponding amplitudes can be calculated by selecting the sixth to last pulse and the last pulse.

In some embodiments, the above step S2 may also include the following processing: determining the initial amplitude of the damped oscillation signal as one of the target amplitudes, determining the threshold voltage for generating the pulse signal as another target amplitude; and determining the number of pulse signals generated by the pulse signal as the target cycle number.

In practical applications, in order to reduce the amount of calculation of the MCU and the design complexity of the digital logic unit, this embodiment can simplify the calculation process by taking approximate values.

Since the initial amplitude VA ₀ of the damped oscillation signal is fixed (i.e., the amplitude of the step signal, which can be selected according to the application scenario), the 0th pulse amplitude VA ₀ is equal to a target amplitude of the step signal; when the last pulse, the edge time t _Fn is very close to t _Rn , and the final amplitude VA _N is similar to V _TH , that is, V _TH can be used as another target amplitude. The initial amplitude VA ₀ and the final amplitude VA _N are both fixed, so the two variables can be pre-calculated and converted into a constant K. Accordingly, the quality factor Q can be obtained according to the function calculation relationship: Q = K ₁ πN.

The simplified Q value calculation formula also has obvious resolution and can realize the function of foreign object detection in wireless charging application scenarios.

In some other embodiments, the damped oscillation signal processing circuit includes two groups of voltage divider circuits and two groups of pulse output circuits, and the two groups of voltage divider circuits have different threshold voltages. The above step S2 may also include the following processing: determining the first pulse signal number and the second pulse signal number generated by the two threshold voltages respectively; then determining the two threshold voltages as two target amplitudes, and determining the difference between the first pulse signal number and the second pulse signal number as the target cycle number.

In practical applications, in order to reduce the amount of MCU calculations and the design complexity of digital logic units, but compared with "Simplified Solution 1", higher anti-interference performance is required. This case proposes a solution idea that can be achieved by designing two switch thresholds.

By designing two voltage divider circuits and a transistor amplifier circuit, the voltage divider parameters are set to thresholds V _{TH_HIGH} and V _{TH_LOW} respectively.

The switch threshold of one channel is V _{TH_LOW} , with a total of N _LOW pulses; the switch threshold of the other channel is V _{TH_HIGH} , with a total of N _HIGH pulses. The amplitude of the last pulse of the two logic outputs is approximately equal to the switch threshold. Since the preset switch threshold is a fixed value, the logarithmic function can be calculated in advance and the constant can be taken as K to save MCU calculation.

The quality factor Q can be obtained according to the functional calculation relationship: Q = K ₂ (N _HIGH -N _LOW ).

Relatively speaking, this solution actually increases the scale of analog electronics to reduce the scale of digital electronics. Specifically, it can simplify the complexity of MCU software or the scale of digital logic units. Similarly, the simplified Q value calculation formula has sufficient resolution and higher anti-interference performance, which is sufficient to realize the function of foreign object detection in wireless charging application scenarios.

In other embodiments, the foreign object detection method may also include the following processing: detecting a logical change in a pulse signal, detecting an actual voltage at a voltage divider node of a damped oscillation signal processing circuit; and calibrating a threshold voltage of the damped oscillation signal processing circuit based on the actual voltage.

In actual applications, due to the temperature characteristics of the transistor, this solution will have a certain temperature drift and need to be calibrated. In most wireless charging systems, the main control MCU already has DAC and ADC peripherals, and can use either one to achieve parameter calibration. Because it is based on existing carriers, this module does not increase additional costs and is very friendly to cost-sensitive products.

Specifically, U ₂ can be connected to the DAC output of the MCU and calibrated before measuring the Q value, so that U ₂ decreases from 3.3V, and the DAC voltage value U _{2_DAC} when the U _{T_OUT} output logic changes is recorded. Since V _TH = 0V at this time, we get:

Set V _{DAC_SET} = V _{DAC_TH} - ΔV,

For example, if V′ _TH = 80mV, R ₃ = 4.7kΩ, and R ₁ = 1kΩ, the influence of system temperature drift can be eliminated dynamically and in real time through the DAC by simply setting ΔV = 17mV.

When the NPN is turned on, U _T1 can be approximately considered as V _OFF . The MCU only needs to start ADC acquisition after the logic of U _{T_OUT} changes, and measure the voltage of U _T1 through ADC to obtain V _{T1_ADC} , and the current voltage threshold V _TH ′ can be calculated.

Simply substituting the compensated V _TH ′ value into the Q value calculation can eliminate the effect of temperature drift.

For example, the maximum ADC frequency of some MCUs is about 850KHz, which is sufficient to complete several ADC sampling cycles in this application scenario.

Step S3, determining the current oscillation frequency and the current quality factor of the wireless power transmitter to be tested based on the two target amplitudes and the target number of cycles.

After determining the above two target amplitudes and target number of cycles, substitute the calculation formula for the oscillation frequency f into:

The quality factor Q can be obtained according to the functional calculation formula: Q = f(VA _Nn , VA _N , n).

The specific Q value calculation formula is:

The Q value calculated above is relatively accurate, but due to the high amount of calculation, an ordinary MCU needs about 1ms of calculation time. In the wireless charging application scenario, the foreign object detection interval is at least 300ms, which is enough for the MCU to perform calculations.

Step S4, based on the current oscillation frequency, the current quality factor, and the preset standard quality factor and the preset standard oscillation frequency, determine whether there is a foreign object within the working range of the line power transmitter to be tested.

The preset standard quality factor and the preset standard oscillation frequency are respectively the standard quality factor and the standard oscillation frequency measured when the power transmitter to be tested leaves the factory or before use.

Combined with the damped oscillation curves shown in Figures 4 to 6 above, and the changes in the Q value and oscillation frequency f in the alternating electromagnetic field of the wireless power transmitter, it is possible to determine whether there are foreign objects within the working range of the wireless power transmitter to be tested. That is, if the Q value is greatly reduced and the oscillation frequency remains unchanged, it means that there are only metal foreign objects (inductive load) in the alternating electromagnetic field of the wireless power transmitter to be tested; if the Q value is slightly reduced and the oscillation frequency also changes (determined by the natural frequency of the wireless power receiver), it means that there is a wireless power receiver (capacitive load) in the alternating electromagnetic field of the wireless power transmitter to be tested; if the Q value does not change relative to the standard value, and the oscillation frequency is determined by the natural oscillation frequency of the transmitter and remains unchanged, it means that there are no metal devices in the alternating electromagnetic field of the wireless power transmitter to be tested.

The foreign body detection method provided in this embodiment can collect sufficient parameters based on the pulse signal output by the damped oscillation signal processing circuit, and calculate according to the physical meaning of the LC oscillation circuit, so as to obtain a more accurate and reliable oscillation frequency and quality factor. And because this embodiment can measure the oscillation frequency f of the wireless power transmitter to be tested, it can meet the "foreign body detection method based on the natural frequency of the system" in the 1.3 version of the Qi protocol, and increase the applicability of the foreign body detection method. In addition, because this embodiment can measure the Q value and oscillation frequency f of the wireless power transmitter to be tested, it can determine whether there is a metal foreign body in the alternating electromagnetic field of the wireless power transmitter, whether there is a possible power receiver, whether there is a receiving device and a metal foreign body coexisting, and even determine the degree of influence of the foreign body on the charging efficiency, so as to achieve a more detailed foreign body judgment.

Embodiment 4

Based on the same concept as the damped oscillation signal processing circuit mentioned above, this embodiment also provides a foreign object detection device for wireless charging, as shown in FIG10, the device includes: the damped oscillation signal processing circuit mentioned above, and also includes a parameter calculation module and a foreign object detection module. Among them, the damped oscillation signal processing circuit is used to process the damped oscillation signal of the wireless power transmitter to be tested to obtain a corresponding pulse signal; the parameter calculation module is used to determine the current oscillation frequency and current quality factor of the wireless power transmitter to be tested according to the pulse signal; the foreign object detection module is used to determine whether there is a foreign object in the working range of the wireless power transmitter based on the current oscillation frequency, the current quality factor, and the preset standard quality factor and the preset standard oscillation frequency.

The foreign object detection device provided in this embodiment is based on the same concept as the above-mentioned damped oscillation signal processing circuit, so it can at least achieve the beneficial effects that the above-mentioned damped oscillation signal processing circuit can achieve, and any implementation of the above-mentioned damped oscillation signal processing circuit can be applied to the foreign object detection device provided in this embodiment, which will not be repeated here.

In some embodiments, as shown in FIG. 11 , the foreign object detection device further includes a calibration module, which is used to detect the actual voltage of the voltage divider node of the damped oscillation signal processing circuit when a logic change occurs in the pulse signal; and calibrate the threshold voltage of the damped oscillation signal processing circuit based on the actual voltage.

Embodiment 5

Based on the same concept as the above-mentioned foreign object detection device for wireless charging, this embodiment further provides a wireless charging device, including a wireless power transmitter and also including the above-mentioned foreign object detection device for wireless charging.

The wireless charging device provided in this embodiment is based on the same concept as the above-mentioned foreign object detection device, so it can at least achieve the beneficial effects that the above-mentioned foreign object detection device can achieve, and any implementation of the above-mentioned foreign object detection device can be applied to the wireless charging device provided in this embodiment, which will not be repeated here.

Embodiment 6

The embodiments of the present application also provide an electronic device to execute the above-mentioned foreign object detection circuit. Please refer to Figure 12, which shows a schematic diagram of an electrical device provided by some embodiments of the present application. As shown in Figure 12, the electrical device 40 includes: a processor 400, a memory 401, a bus 402 and a communication interface 403, and the processor 400, the communication interface 403 and the memory 401 are connected via the bus 402; the memory 401 stores a computer program that can be run on the processor 400, and when the processor 400 runs the computer program, it executes the foreign object detection method provided by any of the aforementioned embodiments of the present application.

The memory 401 may include a high-speed random access memory (RAM), and may also include a non-volatile memory, such as at least one disk storage. The communication connection between the device network element and at least one other network element is realized through at least one communication interface 403 (which may be wired or wireless), and the Internet, wide area network, local area network, metropolitan area network, etc. may be used.

The bus 402 may be an ISA bus, a PCI bus, or an EISA bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. Among them, the memory 401 is used to store programs, and the processor 400 executes the program after receiving the execution instruction. The foreign body detection method disclosed in any implementation of the above-mentioned embodiment of the present application can be applied to the processor 400, or implemented by the processor 400.

The processor 400 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the hardware integrated logic circuit or software instructions in the processor 400. The above processor 400 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a readily available programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiments of the present application can be directly embodied as a hardware decoding processor to be executed, or the hardware and software modules in the decoding processor can be executed. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory 401, and the processor 400 reads the information in the memory 401 and completes the steps of the above method in combination with its hardware.

The electrical equipment provided in the embodiment of the present application and the foreign object detection method provided in the embodiment of the present application are based on the same inventive concept and have the same beneficial effects as the methods adopted, operated or implemented therein.

Embodiment 7

The embodiments of the present application also provide a computer-readable storage medium corresponding to the foreign matter detection method provided in the aforementioned embodiments. Please refer to Figure 13, which shows that the computer-readable storage medium is a CD 30 on which a computer program (i.e., a program product) is stored. When the computer program is run by the processor, it will execute the foreign matter detection method provided in any of the aforementioned embodiments.

It should be noted that examples of computer-readable storage media may also include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other optical or magnetic storage media, which are not listed here one by one.

The computer-readable storage medium provided in the above-mentioned embodiments of the present application and the foreign matter detection method provided in the embodiments of the present application are based on the same inventive concept and have the same beneficial effects as the method adopted, run or implemented by the application program stored therein.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims (16)

1. A damped oscillation signal processing circuit, comprising at least one group of voltage circuits and at least one group of pulse output circuits; The voltage dividing circuit includes a first resistor, a third resistor and a voltage dividing node, one end of the first resistor is connected to the second power supply voltage, and the other end is connected to the voltage dividing node; one end of the third resistor is connected to the voltage dividing node. The damped oscillation signal, the other end is connected to the voltage divider node; The pulse output circuit includes a second resistor, a triode and a pulse output node, one end of the second resistor is connected to the first power supply voltage, and the other end is connected to the pulse output node; the base of the triode is connected to the voltage dividing node , the collector and emitter of the triode are respectively connected to the pulse output node and the common terminal. 2. The circuit according to claim 1, further comprising a clamping circuit, one end of the clamping circuit is connected to the common terminal, and the other end is connected to the voltage dividing node, and the clamping circuit is used for The circuit of the voltage dividing node is clamped to be within a preset threshold. 3. The circuit according to claim 2, wherein the clamping circuit comprises a diode, the anode of the diode is connected to the common terminal, and the cathode is connected to the voltage dividing node. 4. The circuit according to any one of claims 1-3, wherein the damped oscillation signal processing circuit comprises two sets of voltage circuits and two sets of pulse output circuits, and the two sets of voltage divider circuits have different The threshold voltage; the threshold voltage represents the amplitude of the damped oscillation signal when the triode is at the cut-off voltage. 5. A chip, characterized in that the damped oscillation signal processing circuit according to any one of claims 1-4 is integrated thereon. 6. A foreign object detection device for wireless charging, characterized in that it comprises: The damped oscillation signal processing circuit according to any one of claims 1-4, which is used to process the damped oscillation signal of the wireless power transmitter to be tested to obtain a corresponding pulse signal; A parameter calculation module, configured to determine the current oscillation frequency and the current quality factor of the wireless power transmitter to be tested according to the pulse signal; The foreign object detection module is used to determine whether there is a foreign object within the working range of the wireless power transmitter based on the current oscillation frequency, the current quality factor, the preset standard quality factor and the preset standard oscillation frequency. 7. The foreign object detection device according to claim 6, further comprising a calibration module, the calibration module is used to detect the voltage divider node of the damped oscillation signal processing circuit when the pulse signal undergoes a logic change. and calibrate the threshold voltage of the damped oscillation signal processing circuit based on the actual voltage. 8. A wireless charging device, comprising a wireless power transmitter, further comprising the foreign object detection device for wireless charging according to claim 6 or 7. 9. A method for detecting foreign objects in wireless charging, comprising: Applying the damped oscillation signal processing circuit described in any one of claims 1-4 to process the damped oscillation signal of the wireless power transmitter to be tested to obtain a corresponding pulse signal; determining two target amplitudes of the damped oscillation signal and a target number of cycles between the two target amplitudes according to the pulse signal; determining a current oscillation frequency and a current quality factor of the wireless power transmitter under test based on the two target amplitudes and the target number of cycles; Based on the current oscillation frequency, the current quality factor, the preset standard quality factor and the preset standard oscillation frequency, it is determined whether there is a foreign object within the working range of the wireless power transmitter to be tested. 10. The method according to claim 9, wherein, according to the pulse signal, two target amplitudes of the damped oscillation signal and the target period number between the two target amplitudes are determined ,include: determining two target moments according to the change edge of the pulse signal, and the time difference between the two target moments is the target cycle number; It is determined that amplitudes respectively corresponding to the two target moments are the two target amplitudes. 11. The method according to claim 10, wherein said determining two target moments according to the change edge of said pulse signal comprises: According to the pulse signal, determine the falling edge time and rising edge time of each pulse signal generated by the damped oscillation signal; Based on the falling edge moment and rising edge moment of the Mth pulse signal, and the falling edge moment and rising edge moment of the Nth pulse signal, determine the intermediate moment for generating the Mth pulse signal and generate the Nth pulse The intermediate moments of the signal are respectively the two target moments; the M and the N are two different natural numbers respectively. 12. The method according to claim 9, wherein, according to the pulse signal, two target amplitudes of the damped oscillation signal and the target period number between the two target amplitudes are determined ,include: determining the initial amplitude of the damped oscillation signal as one of the target amplitudes, and determining the threshold voltage for generating the pulse signal as another target amplitude; The number of pulse signals generated by the pulse signal is determined as the target cycle number. 13. The method according to claim 9, wherein the damped oscillation signal processing circuit comprises two groups of voltage-dividing circuits and two groups of pulse output circuits, and the voltage-dividing circuits of the two groups have different threshold voltages; The determining two target amplitudes of the damped oscillation signal according to the pulse signal, and the target number of cycles between the two target amplitudes includes: determining the number of first pulse signals and the number of second pulse signals respectively generated by the two threshold voltages; The two threshold voltages are determined as the two target amplitudes, and the difference between the first pulse signal number and the second pulse signal number is determined as the target cycle number. 14. The method according to any one of claims 9-13, further comprising: Detecting the actual voltage of the voltage dividing node of the damped oscillation signal processing circuit when the pulse signal undergoes a logic change; The threshold voltage of the damped oscillation signal processing circuit is calibrated based on the actual voltage. 15. An electronic device, comprising a memory, a processor, and a computer program stored in the memory and operable on the processor, characterized in that, when the processor executes the computer program, the computer program according to claim The method described in any one of 9-14. 16. A computer-readable storage medium, on which a computer program is stored, wherein the program is executed by a processor to implement the method according to any one of claims 9-14.

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