Low-power-consumption wireless charging foreign matter detection method and system

Abstract

The invention discloses a low-power-consumption wireless charging foreign matter detection method. The method comprises the following steps: measuring a damped oscillation waveform; performing envelope detection on the damped oscillation waveform, and sampling to obtain an envelope average voltage VCOIL; analyzing whether the difference value between the average envelope voltage VCOIL and the reference voltage Va is smaller than a preset threshold value or not; if yes, wireless communication transmission is started for the to-be-detected object, and whether the to-be-detected object returns a communication packet is detected; and if yes, determining that the to-be-detected object is a charging device with a wireless charging function. Therefore, in a low-power-consumption standby dormant state, envelope detection is periodically carried out on the damped oscillation signal, the envelope average voltage is measured, whether the to-be-detected object is placed on the wireless charging area is judged, then wireless communication with the to-be-detected object is carried out to judge whether the to-be-detected object is the foreign matter or the charging equipment, the foreign matter can be accurately recognized only based on a simple operation circuit, the operation power consumption is low, and the reliability is high. The method effectively avoids the phenomenon of false triggering of wireless charging, and is suitable for equipment scenes with limited electric energy, such as mobile power supplies.

Description

Technical Field

[0001] This invention relates to the field of wireless charging detection technology, and in particular to a low-power wireless charging foreign object detection method and system. Background Technology

[0002] Currently, wireless charging is widely used in various types of electronic devices, and correspondingly, various types of wireless charging devices have emerged. Besides the conventional wireless charging docks that connect to an external power source, there are also power banks with wireless charging capabilities. In practical applications, to reduce standby power consumption when idle and to achieve instant charging when the device is placed, wireless charging devices often enter a low-power sleep mode when idle, maintaining operation with a current of around μA and periodically checking if any electronic device is placed in the charging area waiting to be charged. Understandably, if a metallic foreign object is placed in the wireless charging area, it may accidentally trigger the wireless charging device to supply power, creating a safety hazard and wasting power. Furthermore, since power banks are often stored together with other items and devices, this phenomenon of accidental triggering of wireless charging is more pronounced with power banks that have limited capacity. Existing solutions for foreign object detection in wireless charging either require adding detection components, significantly increasing component costs, or the detection process consumes high amounts of power, greatly increasing the standby power consumption of the power bank. Summary of the Invention

[0003] The first aspect of this embodiment discloses a low-power wireless charging foreign object detection method, specifically including: Measure the damped oscillation waveform; The envelope of the damped oscillation waveform is detected and sampled to obtain the average envelope voltage VCOIL; Analyze whether the difference Δ between the envelope average voltage VCOIL and the reference voltage Va is less than a preset threshold. If so, initiate wireless communication transmission to the object under test and detect whether the object under test returns a communication packet; If so, the object under test is determined to be a charging device with wireless charging function.

[0004] As an optional implementation, the supply voltage VDC is obtained by sampling the power supply. Set coefficients It is set based on the ratio of the voltage divider resistors in the envelope detector unit; The reference voltage ; The difference .

[0005] As an optional implementation, if the object under test generates an induced electromotive force based on the high-frequency magnetic field, the damped oscillation waveform will experience pulse attenuation, and the envelope average voltage VCOIL will decrease.

[0006] As an optional implementation, the power supply is a storage battery; The value of the supply voltage VDC varies with the capacity of the battery; The coefficient ∂ is used to limit the fluctuation range of the reference voltage Va.

[0007] As an optional implementation, the method further includes: If the difference Δ between the envelope voltage VCOIL and the reference voltage Va is not less than the preset threshold, then the object under test is determined to be a foreign object, or the object under test is determined to be not completely placed in the wireless charging area.

[0008] As an optional implementation, the method further includes: If the object under test does not return a communication packet, the object under test is determined to be a foreign object, and the foreign object is locked based on the damped oscillation waveform corresponding to the foreign object; And, it enters a sleep state, waiting to be periodically woken up, in order to measure the damped oscillation waveform of the H-bridge drive unit.

[0009] The second aspect of this embodiment discloses a low-power wireless charging foreign object detection system, specifically including: A detection module consisting of an H-bridge driving unit and an LC resonant unit measures and outputs a damped oscillation waveform. The envelope detection module acquires the damped oscillation waveform and samples it to obtain the envelope average voltage VCOIL; The data processing module analyzes whether the difference Δ between the envelope average voltage VCOIL and the supply voltage VDC is less than a preset threshold. The communication detection module is used to initiate wireless communication transmission for the object under test when the difference Δ is less than the preset threshold, and to detect whether the object under test returns a communication packet.

[0010] As an optional implementation, the H-bridge driving unit includes MOSFETs Q1, Q2, Q4 and Q3 connected in series in a ring, and the LC resonant unit includes an inductor L1 and a capacitor C5 connected in series. The MOSFET Q1 and MOSFET Q3 are connected to a power supply voltage VDC, and the MOSFET Q2 and MOSFET Q4 are grounded. The MOSFET Q1 and the MOSFET Q2 are connected to one end of the inductor L1 in the LC resonant unit, and the MOSFET Q3 and the MOSFET Q4 are connected to one end of the capacitor C5 in the LC resonant unit. When the periodic signal PWM1H turns on the MOSFET Q1 and the periodic signal PWM2L turns on the MOSFET Q4, while the periodic signal PWM1L turns off the MOSFET Q2 and the periodic signal PWM2H turns off the MOSFET Q3, the H-bridge driving unit provides a single short pulse signal to the LC resonant unit, and the LC resonant unit is charged. Then, when the short pulse signal ends, the periodic signal PWM1H turns off the MOSFET Q1, the periodic signal PWM2H turns off the MOSFET Q3, and at the same time, the periodic signal PWM1L turns on the MOSFET Q2, the periodic signal PWM2L turns on the MOSFET Q4, and the LC resonant unit enters the damped oscillation state. A port VC is provided between the inductor L1 and the capacitor C5 to output the damped oscillation waveform.

[0011] As an optional implementation, the envelope detection module includes resistors R20, R21, and R22 connected in series with capacitor C11. The positive terminal of diode D3 is connected to port VC, and the negative terminal is connected to resistors R20 and R21. A port VCO is connected between resistor R21 and resistor R22, and the port VCO is used to output the envelope average voltage VCOIL; The capacitor C13 is connected in parallel with the resistor R22.

[0012] As an optional implementation, the data processing module obtains the envelope average voltage VCOIL through the port VCO, and compares the difference Δ between the envelope average voltage VCOIL and the supply voltage VDC accordingly. The communication detection module is used to identify the device under test as a charging device with wireless charging function after detecting the communication packet returned by the device under test, and output a charging command to start wireless charging.

[0013] Compared with the prior art, this embodiment has the following beneficial effects: In this embodiment, in the low-power standby sleep state, the damped oscillation signal envelope is periodically detected to measure the average envelope voltage. Based on this, it is determined whether there is a test object placed on the wireless charging area. Then, it attempts to wirelessly communicate with the test object to determine whether it is a foreign object or a charging device. Based on only a simple computing circuit, it can accurately identify foreign objects, has low operating power consumption, and effectively avoids the phenomenon of accidental wireless charging. It is suitable for device scenarios with limited power, such as power banks. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in this embodiment, the accompanying drawings used in the embodiment will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the workflow of a low-power wireless charging foreign object detection method disclosed in this embodiment; Figure 2 This is a waveform diagram of the damped oscillation waveform formed by the H-bridge driving unit charging the LC resonant unit in a low-power wireless charging foreign object detection method disclosed in this embodiment. Figure 3 This is a waveform diagram of a low-power wireless charging foreign object detection method disclosed in this embodiment when there is no object in the wireless charging area; Figure 4 This is a waveform diagram of the test object placed in the wireless charging area in a low-power wireless charging foreign object detection method disclosed in this embodiment. Figure 5 This is a schematic diagram of the system structure of a low-power wireless charging foreign object detection system disclosed in this embodiment; Figure 6 This is a schematic diagram of the circuit principle of the detection module in a low-power wireless charging foreign object detection system disclosed in this embodiment; Figure 7 This is a schematic diagram of the circuit principle of the envelope detection module in a low-power wireless charging foreign object detection system disclosed in this embodiment. Detailed Implementation

[0016] The technical solutions in this embodiment will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1 Please see Figures 1-4 This embodiment discloses a low-power wireless charging foreign object detection method, including: 101. Measure the damped oscillation waveform.

[0018] In this embodiment, if the object under test generates an induced electromotive force based on a high-frequency magnetic field, the damped oscillation waveform generated by the H-bridge drive unit will experience pulse attenuation, and the envelope average voltage VCOIL will decrease.

[0019] Specifically, in a wireless charging device, an H-bridge driver circuit is used to generate a high-frequency changing AC voltage to act on the transmitting coil, causing it to output a high-frequency changing magnetic field. Subsequently, the receiving coil on the charging device is subjected to the magnetic field, generating an induced electromotive force, which is rectified and output as a DC voltage, thereby realizing wireless charging.

[0020] Here, the damped oscillation waveform is generated by the LC resonant circuit connected to the H-bridge drive circuit.

[0021] It is understandable that, such as Figure 2 As shown, if there are no objects in the wireless charging area, the damped oscillation waveform will exhibit standard exponential decay, and the damped oscillation waveform will have a large number of pulses and decay slowly.

[0022] Conversely, if an object is placed in the wireless charging area, the object will absorb the energy of the damped oscillation waveform, reducing the number of pulses in the damped oscillation waveform and accelerating its decay.

[0023] Therefore, by measuring the damped oscillation waveform, no additional detection components are needed. The existing drive components of the device are monitored, and with the help of a simple computing circuit, it is possible to initially detect whether there is an object placed on the wireless charging area. It has low power consumption and no special requirements for the device itself. It is suitable for scenarios such as power banks with limited power and need to maintain low power consumption under normal conditions.

[0024] 102. Detect the envelope of the damped oscillation waveform and sample to obtain the average envelope voltage VCOIL.

[0025] In this embodiment, the analysis and detection scheme for damped oscillation waveforms specifically involves measuring the envelope average voltage of its sampling interval.

[0026] For example, taking a wireless charging device with wireless charging capabilities as an example, such as Figure 3 As shown, if there are no objects in its wireless charging area, the average envelope voltage VCOIL may be 4.9~5.6V.

[0027] When an object is placed in its wireless charging area, such as Figure 4 As shown, since part of the energy of the damped oscillation waveform is absorbed by the object, the envelope average voltage VCOIL decreases, possibly to 3.2~4V.

[0028] Therefore, by measuring the envelope average voltage VCOIL of the damped oscillation waveform, it is possible to analyze whether there is an object in the current wireless charging area.

[0029] 103. Analyze whether the difference Δ between the envelope average voltage VCOIL and the reference voltage Va is less than the preset threshold.

[0030] In this embodiment, the wireless charging device may be a portable power source, powered by a battery. The battery's output voltage varies during use, resulting in a variable, non-constant, envelope average voltage (VCOIL). Therefore, determining the presence of an object in the wireless charging area solely based on the envelope average voltage (VCOIL) is not sufficiently accurate. This embodiment combines this with a reference voltage (Va) for more accurate analysis.

[0031] As an optional implementation, the supply voltage VDC is obtained by sampling the power supply. Set coefficients It is set based on the ratio of the voltage divider resistors in the envelope detector unit; Reference voltage ; Difference .

[0032] As an optional implementation, the power supply is a storage battery; The value of the supply voltage VDC varies with the battery capacity; coefficient Used to limit the fluctuation range of the reference voltage Va.

[0033] Here, in addition to sampling and analyzing the envelope average voltage VCOIL at the driver end, the supply voltage VDC is also sampled and analyzed at the power supply end, and a coefficient is used. Adjust the supply voltage VDC and compare the difference between the accurate reference voltage Va and the current envelope average voltage VCOIL to eliminate the possibility of inaccurate analysis caused by changes in the supply voltage.

[0034] Specifically, if the difference Δ is less than a preset threshold, it is considered that an object is placed in the wireless charging area, and the process proceeds to step 104 for further identification.

[0035] As another optional implementation, if the difference Δ between the envelope average voltage VCOIL and the reference voltage Va is not less than a preset threshold, the object under test is determined to be a foreign object, or the object under test is determined not to be completely placed in the wireless charging area.

[0036] Furthermore, if there are foreign objects placed in the wireless charging area, or if the test object is not completely placed in the wireless charging area, or if the wireless charging area is empty, no further identification is required, and the device will enter a low-power sleep state, waiting for the next periodic wake-up.

[0037] It is evident that by employing a two-stage discrimination method, many interference scenarios can be effectively eliminated based on the envelope average voltage VCOIL, without the need for dedicated detection components to perform full-process detection and analysis for each trigger state, thus effectively reducing detection power consumption.

[0038] 104. Initiate wireless communication transmission to the device under test and detect whether the device under test returns a communication packet.

[0039] In this embodiment, after determining that an object to be tested is placed on the wireless charging area, wireless communication transmission is further initiated on the object to be tested to determine whether it is a charging device or a metallic foreign object.

[0040] As an optional implementation, a digital ping is initiated to the device under test. If the device under test is a charging device with wireless charging capability, a communication packet with the wireless charging protocol will be returned to achieve protocol handshake. At this point, step 105 is initiated.

[0041] As another optional implementation, if the object under test does not return a communication packet, the object under test is determined to be a foreign object, and the foreign object is locked based on the damped oscillation waveform corresponding to the foreign object; Additionally, it enters a dormant state, waiting to be periodically awakened to measure the damped oscillation waveform.

[0042] Specifically, if the object under test does not respond to a digital ping, it is determined to be a foreign object.

[0043] Here, the foreign object may contain metallic components that can absorb some of the energy of the damped oscillation waveform, and therefore is not identified as a foreign object in step 103. Therefore, a locking tag can be assigned to it for rapid identification during the next periodic wake-up.

[0044] 105. Determine that the object to be tested is a charging device with wireless charging function.

[0045] In this embodiment, if the object under test is detected in the wireless charging area and the object under test returns a communication packet, it can be known that the object under test is a charging device with wireless charging function. At this time, wireless charging is enabled for it based on the wireless charging protocol.

[0046] Compared with the prior art, this embodiment has the following beneficial effects: In this embodiment, only one resistor needs to be added to the existing driving circuit. The voltage comparator can then compare and output detection signals containing both rising and falling edges to determine the switching frequency and load judgment. This significantly reduces the number of components required and greatly improves the detection accuracy.

[0047] Example 2 Please see Figures 5-7 This embodiment discloses a low-power wireless charging foreign object detection system, comprising: The detection module consists of an H-bridge drive unit and an LC resonant unit. The detection module measures and outputs the damped oscillation waveform. The envelope detection module acquires the damped oscillation waveform and samples it to obtain the envelope average voltage VCOIL; The data processing module analyzes whether the difference Δ between the envelope average voltage VCOIL and the supply voltage VDC is less than a preset threshold. The communication detection module is used to initiate wireless communication transmission for the object under test when the difference Δ is less than a preset threshold, and to detect whether the object under test returns a communication packet.

[0048] In this embodiment, a two-stage verification scheme is adopted. First, it is determined whether there is a test object in the wireless charging area and whether the test object is completely placed in the wireless charging area. Then, wireless communication transmission is performed on the test object to determine whether the test object is a charging device with wireless charging function. Based on this, a low-power and high-accuracy foreign object analysis and detection is achieved, which is suitable for low-power power supply devices such as power banks.

[0049] In this embodiment, the H-bridge driving unit includes MOSFETs Q1, Q2, Q4 and Q3 connected in series in a ring, and the LC resonant unit includes an inductor L1 and a capacitor C5 connected in series. The power supply voltage VDC is connected between MOSFETs Q1 and Q3, and the power supply voltage VDC is connected between MOSFETs Q2 and Q4. MOSFETs Q1 and Q2 are connected to one end of inductor L1 in the LC resonant unit, and MOSFETs Q3 and Q4 are connected to one end of capacitor C5 in the LC resonant unit. When the periodic signal PWM1H turns on MOSFET Q1 and the periodic signal PWM2L turns on MOSFET Q4, while the periodic signal PWM1L turns off MOSFET Q2 and the periodic signal PWM2H turns off MOSFET Q3, the H-bridge drive unit provides a single short pulse signal to the LC resonant unit, and the LC resonant unit is charged. Furthermore, after the short pulse signal ends, the periodic signal PWM1H turns off MOSFET Q1, the periodic signal PWM2H turns off MOSFET Q3, and at the same time, the periodic signal PWM1L turns on MOSFET Q2, the periodic signal PWM2L turns on MOSFET Q4, and the LC resonant unit enters the damped oscillation state. A port VC is set between inductor L1 and capacitor C5 to output a damped oscillation waveform.

[0050] Here, the LC resonant unit is excited to enter a damped oscillation state, so that it outputs a damped oscillation waveform, which is used to detect whether the test object is currently obtaining electrical energy through the induced magnetic field.

[0051] In this embodiment, the envelope detection module includes resistors R20, R21, and R22 connected in series with capacitor C11. The positive terminal of diode D3 is connected to port VC, and the negative terminal is connected to resistors R20 and R21. A port VCO is connected between resistors R21 and R22. The port VCO is used to output the envelope average voltage VCOIL. Capacitor C13 is connected in parallel with resistor R22.

[0052] In this embodiment, the data processing module obtains the envelope average voltage VCOIL through the port VCO, and compares the difference Δ between the envelope average voltage VCOIL and the supply voltage VDC accordingly. The communication detection module is used to identify the device under test as a charging device with wireless charging function after detecting the communication packet returned by the device under test, and outputs a charging command to start wireless charging.

[0053] Here, by comparing the difference Δ between the envelope average voltage VCOIL and the supply voltage VDC, it is initially determined whether there is an object in the wireless charging area.

Claims

1. A low-power wireless charging foreign object detection method, characterized in that, include: Measure the damped oscillation waveform; The envelope of the damped oscillation waveform is detected and sampled to obtain the average envelope voltage VCOIL; Analyze whether the difference Δ between the envelope average voltage VCOIL and the reference voltage Va is less than a preset threshold. If so, initiate wireless communication transmission to the object under test and detect whether the object under test returns a communication packet; If so, the object under test is determined to be a charging device with wireless charging function.

2. The low-power wireless charging foreign object detection method according to claim 1, characterized in that, include: The supply voltage VDC is obtained by sampling the power supply. Set coefficients It is set based on the ratio of the voltage divider resistors in the envelope detector unit; The reference voltage ; The difference .

3. The low-power wireless charging foreign object detection method according to claim 2, characterized in that, include: If the object under test generates an induced electromotive force based on the high-frequency magnetic field, the damped oscillation waveform will experience pulse attenuation, and the envelope average voltage VCOIL will decrease.

4. The low-power wireless charging foreign object detection method according to claim 2, characterized in that, include: The power supply is a storage battery; The value of the supply voltage VDC varies with the capacity of the battery; The coefficient ∂ is used to limit the fluctuation range of the reference voltage Va.

5. The low-power wireless charging foreign object detection method according to claim 1, characterized in that, The method further includes: If the difference Δ between the envelope voltage VCOIL and the reference voltage Va is not less than the preset threshold, then the object under test is determined to be a foreign object, or the object under test is determined to be not completely placed in the wireless charging area.

6. The low-power wireless charging foreign object detection method according to claim 1, characterized in that, The method further includes: If the object under test does not return a communication packet, the object under test is determined to be a foreign object, and the foreign object is locked based on the damped oscillation waveform corresponding to the foreign object; And, it enters a sleep state, waiting to be periodically woken up, in order to measure the damped oscillation waveform of the H-bridge drive unit.

7. A low-power wireless charging foreign object detection system, characterized in that, include: A detection module consisting of an H-bridge driving unit and an LC resonant unit measures and outputs a damped oscillation waveform. The envelope detection module acquires the damped oscillation waveform and samples it to obtain the envelope average voltage VCOIL; The data processing module analyzes whether the difference Δ between the envelope average voltage VCOIL and the supply voltage VDC is less than a preset threshold. The communication detection module is used to initiate wireless communication transmission for the object under test when the difference Δ is less than the preset threshold, and to detect whether the object under test returns a communication packet.

8. The low-power wireless charging foreign object detection system according to claim 7, characterized in that, include: The H-bridge driving unit includes MOSFETs Q1, Q2, Q4 and Q3 connected in series in a ring, and the LC resonant unit includes an inductor L1 and a capacitor C5 connected in series. The MOSFET Q1 and MOSFET Q3 are connected to a power supply voltage VDC, and the MOSFET Q2 and MOSFET Q4 are grounded. The MOSFET Q1 and the MOSFET Q2 are connected to one end of the inductor L1 in the LC resonant unit, and the MOSFET Q3 and the MOSFET Q4 are connected to one end of the capacitor C5 in the LC resonant unit. When the periodic signal PWM1H turns on the MOSFET Q1 and the periodic signal PWM2L turns on the MOSFET Q4, while the periodic signal PWM1L turns off the MOSFET Q2 and the periodic signal PWM2H turns off the MOSFET Q3, the H-bridge driving unit provides a single short pulse signal to the LC resonant unit, and the LC resonant unit is charged. Then, when the short pulse signal ends, the periodic signal PWM1H turns off the MOSFET Q1, the periodic signal PWM2H turns off the MOSFET Q3, and at the same time, the periodic signal PWM1L turns on the MOSFET Q2, the periodic signal PWM2L turns on the MOSFET Q4, and the LC resonant unit enters the damped oscillation state. A port VC is provided between the inductor L1 and the capacitor C5 to output the damped oscillation waveform.

9. A low-power wireless charging foreign object detection system according to claim 8, characterized in that, include: The envelope detection module includes resistors R20, R21, and R22 connected in series with capacitor C11. The positive terminal of diode D3 is connected to port VC, and the negative terminal is connected to resistors R20 and R21. A port VCO is connected between resistor R21 and resistor R22, and the port VCO is used to output the envelope average voltage VCOIL; The capacitor C13 is connected in parallel with the resistor R22.

10. A low-power wireless charging foreign object detection system according to claim 9, characterized in that, include: The data processing module obtains the envelope average voltage VCOIL through the port VCO, and compares the difference Δ between the envelope average voltage VCOIL and the supply voltage VDC accordingly. The communication detection module is used to identify the device under test as a charging device with wireless charging function after detecting the communication packet returned by the device under test, and output a charging command to start wireless charging.

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