CN114189063A - Metal foreign body detecting device - Google Patents
Metal foreign body detecting device Download PDFInfo
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- CN114189063A CN114189063A CN202010955591.3A CN202010955591A CN114189063A CN 114189063 A CN114189063 A CN 114189063A CN 202010955591 A CN202010955591 A CN 202010955591A CN 114189063 A CN114189063 A CN 114189063A
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- 239000002184 metal Substances 0.000 title claims abstract description 56
- 238000001514 detection method Methods 0.000 claims abstract description 114
- 230000010355 oscillation Effects 0.000 claims abstract description 31
- 238000013459 approach Methods 0.000 claims abstract description 7
- 239000003990 capacitor Substances 0.000 claims description 41
- 238000010586 diagram Methods 0.000 description 13
- 238000006243 chemical reaction Methods 0.000 description 8
- 230000005540 biological transmission Effects 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/60—Circuit arrangements or systems for wireless supply or distribution of electric power responsive to the presence of foreign objects, e.g. detection of living beings
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
- G01V3/10—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
- H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
Abstract
The invention discloses a metal foreign body detection device, which comprises a foreign body detection coil, a relay and a foreign body detection circuit and is suitable for a wireless charging device. The wireless charging device is provided with a transmitting coil, a first digital signal processor and a receiving coil. The foreign body detection coil is arranged on the transmitting coil. The relay is connected with the foreign matter detection coil. The foreign matter detection circuit is connected with the relay and the first digital signal processor. The transmitting coil transmits a power signal to the receiving coil during a power supply time. In a foreign matter detection time which is not the power supply time, the relay is started, and the foreign matter detection coil and the foreign matter detection circuit generate an oscillation signal as a judgment basis for the metal foreign matter to approach the wireless charging device.
Description
Technical Field
The present invention relates to a metal foreign object detection device, and more particularly, to a metal foreign object detection device of a wireless charging device.
Background
At present, the metal foreign matter detection method mostly uses a primary power detection method or a resonance waveform comparison method to achieve metal foreign matter detection, and if the foreign matter detection is performed by an instant power detection method or a resonance waveform comparison method, it is difficult to detect a small-sized metal foreign matter at a high power, and a phenomenon that the metal foreign matter is heated is easy to occur, thereby generating high temperature and danger.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a metal foreign object detection device, which includes a foreign object detection coil, a relay and a foreign object detection circuit, and is suitable for a wireless charging device. The wireless charging device is provided with a transmitting coil, a first digital signal processor and a receiving coil. The foreign body detection coil is arranged above the transmitting coil. The relay is connected with the foreign matter detection coil. The foreign matter detection circuit is connected with the relay and the first digital signal processor. In a foreign matter detection time which is not the power supply time, the relay is started, and the foreign matter detection coil and the foreign matter detection circuit generate oscillation signals which are used as a judgment basis for the metal foreign matter to approach the wireless charging device. In one embodiment, the relay includes a relay coil, a diode, a first switch, and a second switch. The foreign object detection coil includes a first coil and a second coil. The first end of the relay coil is connected with the positive end of the diode and the first digital signal processor. The negative terminal of the diode is connected with the second terminal of the relay coil. The second end of the first switch is connected with the first end of the first coil. The second end of the second switch is connected with the second end of the first coil and the second end of the second coil.
In one embodiment, the foreign object detection circuit further includes an auxiliary resonant circuit and an oscillation detection circuit. The auxiliary resonant circuit comprises a first transistor, a first capacitor and a second capacitor. The control end of the first transistor is connected with the shared voltage source and the first end of the second capacitor. The first end of the first capacitor is connected with a shared voltage source. The first end of the first transistor is connected with the second end of the first capacitor and the first end of the first coil. The second terminal of the first transistor is coupled to a reference potential. The second end of the second capacitor is connected with the first end of the second coil. The oscillation detecting circuit comprises a second transistor and a third capacitor. The first end of the second transistor is connected with the shared voltage source and the first end of the third capacitor. The second end of the second transistor is connected with the second end of the third capacitor and grounded. The control end of the second transistor is connected with the first end of the first transistor.
In an implementation, the auxiliary resonant circuit also includes a potentiometer. The second end of the first transistor is grounded through the potentiometer, and the reference potential is changed along with the resistance value modulation of the potentiometer.
In one embodiment, the oscillation detecting circuit further includes a first resistor and a second resistor. One end of the first resistor is connected with the second end of the second transistor. One end of the second resistor is connected with the second end of the first resistor. The second end of the second resistor is grounded. The first digital signal processor is connected with a node between the first resistor and the second resistor. The first digital signal processor controls the frequency and the electric quantity of the power signal transmitted by the transmitting coil and the on-off of the detection relay according to the current flowing through the node or the voltage of the node so as to judge whether the metal foreign matter is close to the wireless charging device.
In one embodiment, the metallic foreign object detection apparatus further includes a display control unit. The display control unit comprises a voltage follower, a comparator and a light-emitting component. The first input end of the voltage follower is connected with the output end of the voltage follower. The second input end of the voltage follower is connected with a node of the oscillation detection circuit. The output end of the voltage follower is connected with the input end of the first digital signal processor. The first input end of the comparator is connected with the node. The first end of the fourth capacitor is connected with the shared voltage source and the second input end of the comparator. The comparator is configured to compare the voltages of the node and the fourth capacitor to output a comparison signal. The light-emitting component is connected with the output end of the comparator. The light-emitting component is configured to emit light when the metal foreign object approaches the wireless charging device according to the comparison signal.
In one embodiment, the third transistor of the first digital signal processor outputs a control signal to turn off the relay when the transmitting coil transmits the power signal.
In one embodiment, the relay includes a relay coil, a diode, a first switch, and a second switch. The foreign object detection coil is a detection coil. The first end of the relay coil is connected with the positive end of the diode and the first digital signal processor. The negative terminal of the diode is connected with the second terminal of the relay coil. The second end of the first switch is connected with the first end of the detecting coil. The second end of the second switch is connected with the second end of the detecting coil.
In one embodiment, the metallic foreign object detection apparatus further includes a display control unit. The display control unit is connected with the foreign matter detection circuit so as to enable the display control unit to emit light when the metal foreign matter is close to the wireless charging device.
In one embodiment, the foreign object detection circuit includes an auxiliary resonant circuit and an oscillation detection circuit. The oscillation detecting circuit comprises a first resistor and a second resistor. The first digital signal processor is connected to a node between the first resistor and the second resistor. The first digital signal controls the frequency and the electric quantity of the power signal transmitted by the transmitting coil and the on-off of the relay according to the current flowing through the node or the voltage of the node so as to judge whether the metal foreign matter is close to the wireless charging device.
As described above, the present invention provides a metal foreign object detection device, which can be used to detect whether a metal foreign object is placed above a wireless charging device, so as to prevent the metal foreign object from interfering with the charging of the wireless charging device and causing a high temperature burnout when the wireless charging device charges an electronic device such as a mobile phone (remote wireless).
For a better understanding of the features and technical content of the present invention, reference should be made to the following detailed description and accompanying drawings, which are provided for purposes of illustration and description only and are not intended to limit the invention.
Drawings
Fig. 1 is a block diagram of a primary side of a wireless charging device and a metal foreign object detection device according to an embodiment of the invention.
Fig. 2 is a block diagram of a secondary side of the wireless charging device.
Fig. 3 is a circuit layout diagram of the metal foreign object detection device according to the embodiment of the invention.
Fig. 4 is a circuit layout diagram of a metal foreign object detection device according to another embodiment of the invention.
Fig. 5 is a timing waveform diagram of a power supply time and a foreign object detection time of the wireless charging device according to the embodiment of the invention.
Fig. 6 is a circuit layout diagram of a metal foreign object detection device according to still another embodiment of the present invention.
Detailed Description
The following is a description of embodiments of the present invention with reference to specific embodiments, and those skilled in the art will understand the advantages and effects of the present invention from the disclosure of the present specification. The invention is capable of other and different embodiments and its several details are capable of modifications and various changes in detail, all without departing from the spirit and scope of the present invention. The drawings of the present invention are for illustrative purposes only and are not intended to be drawn to scale. The following embodiments will further explain the related art of the present invention in detail, but the disclosure is not intended to limit the scope of the present invention. In addition, the term "or" as used herein should be taken to include any one or combination of more of the associated listed items as the case may be.
Referring to fig. 1, fig. 2 and fig. 5, wherein fig. 1 is a block diagram of a primary side of a wireless charging device and a metal foreign object detection device according to an embodiment of the present invention; fig. 2 is a block diagram of a secondary side of the wireless charging device; fig. 5 is a timing waveform diagram of a power supply time and a foreign object detection time of the wireless charging device according to the embodiment of the invention.
The metal foreign object detection device 5 of the embodiment of the invention includes a foreign object detection coil 12, a relay 13 and a foreign object detection circuit 14 shown in fig. 1, and can be disposed inside the wireless charging device.
The metal foreign object detection device 5 is suitable for a wireless charging device. As shown in fig. 1, the primary side 6 (transmitting end) of the wireless charging device includes a transmitting coil 11, a first digital signal processor 15, a dc-ac converting circuit 16, a first communication module 17, a first dc-dc converting circuit 18, an electromagnetic interference controller 19, an ac-dc converter 20, and an external power supply 21.
As shown in fig. 2, the secondary side 8 (receiving end) of the wireless charging device includes a receiving coil 22, a rectifier 23, a second communication module 24, a second digital signal processor 25, a second dc-dc conversion circuit 26, a voltage detection circuit 27, a battery charging control circuit 28, a current detection circuit 29, and a battery 30.
It should be understood that the present invention is not limited to the arrangement of all circuit elements illustrated in the present embodiment, and the circuit elements may be increased or decreased in practice according to actual requirements.
As shown in fig. 1, the ac-dc converter 20 may receive ac mains power from an external power supply 21 and convert the ac mains power into dc voltage. The EMI controller 19 is connected to the ac-dc converter 20 to filter out electromagnetic interference (EMI) noise of the dc voltage received from the ac-dc converter 20.
The first dc-dc conversion circuit 18 may be connected to the electromagnetic interference controller 19 and the first digital signal processor 15. The emi controller 19 may supply the dc voltage with the filtered emi noise to the first dc-dc converting circuit 18, so as to adjust the dc voltage through the first dc-dc converting circuit 18, and supply the adjusted dc voltage to the first digital signal processor 15, so as to provide the first digital signal processor 15 with the required power for operation.
The dc-ac conversion circuit 16 is connected to the first digital signal processor 15, the electromagnetic interference controller 19, and the transmitting coil 11. The emi controller 19 may supply the dc voltage with the emi filtered out to the dc-ac converting circuit 16. The first digital signal processor 15 may control the dc-ac converting circuit 16 to convert the dc voltage into the ac voltage and supply the ac voltage to the transmitting coil 11, so that the transmitting coil 11 may transmit the power signal toward the foreign object detecting coil 22 shown in fig. 2 within the power supply time T1 shown in fig. 5.
The foreign object detection coil 12 is disposed above the transmission coil 11 of fig. 1 (fig. 1 is a block diagram), and the foreign object detection coil 12 is preferably disposed between the transmission coil 11 and the reception coil 22. When the transmitting coil 11 transmits the power signal, a metal foreign object is placed on the transmitting coil 11 or close to the transmitting coil 11, and the metal foreign object may generate an eddy current due to the influence of the magnetic beam and the magnetic field between the transmitting coil 11 and the receiving coil 22, so that the metal foreign object is heated to a high temperature, which may cause a danger.
In order to prevent the transmitting coil 11 and the receiving coil 22 from inducing ac voltage and burning out the metal foreign object at high temperature to affect the circuit components, the metal foreign object detecting device 5 of the present embodiment is disposed in the wireless charging device, so as to achieve the purpose of detecting the metal foreign object.
The transmitting coil 11 transmits a power signal to the receiving coil 22 during the power supply time T1 as shown in fig. 5. The foreign object detection is not performed while the power signal is transmitted from the transmitting coil 11, and the power supply time T1 is shifted from the foreign object detection time T2 as shown in fig. 5.
Therefore, the first digital signal processor 15 is connected to the relay 13. The first digital signal processor 15 controls the relay 13 to remain closed for the power supply time T1 (i.e., the time when the transmitting coil 11 transmits the power signal to the receiving coil 22) as shown in fig. 5.
Upon entering the foreign object detection time T2 shown in fig. 5, the first digital signal processor 15 controls the relay 13 to open. When the relay 13 is turned on, the foreign object detection circuit 14 and the foreign object detection coil 12 are allowed to detect whether a metal foreign object is approaching. The first dsp 15 can determine the energy attenuation degree of the oscillation signal according to the voltage at the node NA between the first resistor R1 and the second resistor R2 shown in fig. 3 or fig. 4, so as to determine whether a foreign object is near the wireless charging device.
As shown in fig. 2, the rectifier 23 of the secondary side 8 of the wireless charging device is connected to the receiving coil 22, the second dc-dc conversion circuit 26, and the voltage detection circuit 27. The rectifier 23 rectifies the power signal received by the winding coil 22, and then supplies the rectified power signal to the second dc-dc conversion circuit 26 and the voltage detection circuit 27.
The second dc-dc conversion circuit 26 may be connected to the second digital signal processor 25. The second dc-dc conversion circuit 26 may convert the voltage of the power signal rectified by the rectifier 23 into a lower or larger voltage, and supply the lower or larger voltage to the second digital signal processor 25.
The voltage detection circuit 27 may be connected to the second digital signal processor 25. The voltage detection circuit 27 may detect a voltage value of the power signal rectified by the voltage detection circuit 27, and output the detected voltage value to the second digital signal processor 25.
The first digital signal processor 15 can determine whether there is a metal foreign object approaching according to the obtained voltage value change. When it is determined that a foreign object is close to the wireless charging device, the dc-ac conversion circuit 16 is controlled to continuously supply the power signal of the power to the transmitting coil 11 for the power supply time T1 shown in fig. 5, and then switch to the foreign object detection time T2 for continuously detecting the foreign object, so that the switching operation is repeated for the power supply time T1 and the foreign object detection time T2 until it is determined that the metal foreign object is removed or away from the wireless charging device, and the wireless charging device is switched to the full-carrier (all duty) of the power supply state with high voltage for the later time portion shown in fig. 5.
The first digital signal processor 15 can control the dc-ac converting circuit 16 to determine the time and frequency of the power signal transmitted from the transmitting coil 11 to the foreign object detecting coil 12 and the power of the power signal according to the obtained voltage variation. It should be understood that the invention is not limited to the length of the power supply time T1 illustrated in FIG. 5, and can be adjusted according to actual requirements.
On the contrary, when the first dsp 15 determines that no metal foreign object is close to the foreign object detection coil 12, the foreign object detection is stopped, and the battery 30 of the wireless charging device can be used to charge the electronic device, such as a mobile phone or a pen. At this time, the receiving coil 22 can obtain power with a large amount of power enough to charge an electronic device such as a mobile phone or a pen.
Please refer to fig. 3, which is a circuit layout diagram of the metal foreign object detection apparatus according to the embodiment of the present invention.
As shown in fig. 3, the foreign object detection circuit 14 of the metallic foreign object detection apparatus according to the embodiment of the present invention includes an auxiliary resonant circuit 141 and an oscillation detection circuit 142, where the auxiliary resonant circuit 141 includes a first transistor Q1, a first capacitor C1, a second capacitor C2, a potentiometer 31, a fifth capacitor C5, and a third resistor R3. The oscillation detecting circuit 142 may include a second transistor Q2, a third capacitor C3, a first resistor R1 and a second resistor R2. The foreign object detection coil 12 of the metallic foreign object detection device may include a first coil L1 and a second coil L2.
The relay 13 includes a relay coil 131, a diode DE, a first switch SW1, and a second switch SW 2. A first terminal of the primary side of the relay coil 131 is connected to a positive terminal of the diode DE and a first terminal of the third transistor Q3 of the first digital signal processor 15. A second end of the primary side of the relay coil 131 is connected to a negative end of the diode. A second terminal, e.g., a source, of the third transistor Q3 is grounded. The first digital signal processor 15 can output a low-level digital signal through a general purpose input/output pin GPIO, and the low-level digital signal is transmitted to the control terminal of the third transistor Q3 of the first digital signal processor 15 through the resistor R6 to control the operation of the third transistor Q3, so as to turn off the relay 13.
When the relay 13 is turned off, the foreign substance detection circuit 14 shown in fig. 3 does not perform foreign substance detection. At this time, the transmitting coil 11 shown in fig. 1 may transmit a power signal to the receiving coil 22 shown in fig. 2, providing power required for subsequently performing foreign object detection or charging.
A first terminal of the first switch SW1 of the relay 13 is connected to a first terminal of the first transistor Q1, and a second terminal of the first switch SW1 is connected to a first terminal of the first coil L1. A first terminal of the second coil L2 is connected to the control terminal of the first transistor Q1 through a second capacitor C2. A first terminal of a second switch SW2 of the relay 13 is connected to a first terminal of a second transistor Q2. A second terminal of the second switch SW2 is connected to the second terminal of the first coil L1 and the second terminal of the second coil L2. The first coil L1 and the second coil L2 of the foreign object detection coil 12 of fig. 1 can be disposed on a printed circuit board.
The control terminal, e.g., the base, of the first transistor Q1 is connected to a common voltage source VCC through a third resistor R3 and to a first terminal of a second capacitor C2. The second terminal of the second capacitor C2 is connected to the first terminal of the second coil L2. A first terminal of the first transistor Q1 is connected to a second terminal of the first capacitor C1. A first terminal of the first capacitor C1 is connected to the common voltage source VCC. A first terminal of the third resistor R3 may be connected to a first terminal of a fifth capacitor C5. A second terminal of the fifth capacitor C5 may be connected to ground.
The second terminal of the first transistor is coupled to a reference potential RF. For example, the auxiliary resonant circuit 141 further includes a potentiometer 31. The second terminal of the first transistor Q1 is grounded through the potentiometer 31. The reference potential RF value is changed as the resistance value of the potentiometer 31 is modulated within a resistance value range.
The oscillation detecting circuit 142 includes a second transistor Q2 and a third capacitor C3. The control terminal of the second transistor Q2 is connected to the first terminal of the first transistor Q1. A first terminal of the second transistor Q2 is connected to the common voltage source VCC and a first terminal of the third capacitor C3. A second terminal of the second transistor Q2 is connected to a second terminal of the third capacitor C3.
The second end of the second transistor Q2 may be directly grounded, or grounded through the first resistor R1 and the second resistor R2 inside the oscillation detecting circuit 142 in this embodiment. The node NA between the first resistor R1 and the second resistor R2 is connected to the input terminal of the first digital signal processor 15.
When the relay 13 shown in fig. 3 is turned on during the foreign object detection time T2 shown in fig. 5, the first switch SW1 of the relay 13 connects the first coil L1 of the receiving coil to the first terminal of the first transistor Q1, and the second switch SW2 of the relay 13 connects the second coil L2 of the receiving coil to the first terminal of the second transistor Q2.
Thus, the first transistor Q1, the first coil L1 and the first capacitor C1 are connected in parallel to generate resonance, and the second coil L2 is connected to the control terminal of the first transistor Q1 through the second capacitor C2 to form positive feedback, so as to enter an oscillation state. Then, the resistance of the potentiometer 31 can be adjusted to make the auxiliary resonant circuit 141 in a critical state of oscillation and non-oscillation.
When a metal foreign object approaches the first coil L1 and the second coil L2 of the foreign object detection coil 12, an eddy current is generated, and the energy of oscillation is absorbed, so that the oscillation signal is consumed and attenuated to weaken the amplitude of the oscillation signal, and the energy of the feedback signal of the feedback winding of the second coil L2 is insufficient to reduce the amplitude or stop oscillation, thereby stopping the second transistor Q2. Therefore, the first dsp 15 can determine the energy attenuation degree of the oscillation signal according to the voltage at the node NA between the first resistor R1 and the second resistor R2, and accordingly determine whether there is a metal foreign object approaching the wireless charging device.
Please refer to fig. 4, which is a circuit layout diagram of a metal foreign object detection apparatus according to another embodiment of the present invention. Compared to the metallic foreign object detection apparatus shown in fig. 3, the metallic foreign object detection apparatus shown in fig. 4 may further include a display control unit 50, wherein the display control unit 50 includes a voltage follower 32, a comparator 33, and a light emitting element LED.
A first voltage input terminal of the voltage follower 32 is connected to the common voltage source VCC, and a second voltage input terminal of the voltage follower 32 is grounded. The output terminal of the voltage follower 32 is connected to a first input terminal, such as an inverting input terminal, of the voltage follower 32 and to the input terminal of the first digital signal processor 15.
A second input terminal, for example, a non-inverting input terminal, of the voltage follower 32 may be connected to a node NA between the first resistor R1 and the second resistor R2 of the oscillation detecting circuit 142 to obtain a voltage of the node NA. The second input terminal of the voltage follower 32 is connected to the second terminal of the second transistor Q2 (via the first resistor R1), and is grounded (via the second resistor R2).
The voltage follower 32 may be configured to output a foreign object detection signal according to a voltage of a first input terminal, such as an inverting input terminal, of the voltage follower 32 and a voltage of the node NA, and the first dsp 15 may determine whether a metal foreign object is close to the wireless charging device.
On the other hand, the first input terminal, e.g., the non-inverting input terminal, of the comparator 33 may be connected to the node NA between the first resistor R1 and the second resistor R2 to obtain the voltage of the node NA.
A second input terminal, e.g., an inverting input terminal, of the comparator 33 is connected to the common voltage source VCC through a fourth resistor R4 and is grounded through a fifth resistor R5. The fifth resistor R5 is connected in parallel with the fourth capacitor C4. The second input terminal of the comparator 33 can obtain the voltage of the fifth resistor R5 or the fourth capacitor C4.
The comparator 33 may compare the voltage of the fifth resistor R5 (or the voltage of the fourth capacitor C4) with the voltage of the node NA to output a comparison signal. The positive terminal of the light emitting component LED, e.g. a light emitting diode, is connected to the output of the comparator 33 via a seventh resistor R7. The negative terminal of the light emitting component LED is grounded.
When the metal foreign matter is not close to the wireless charging device, the light emitting component LED receives the comparison signal of the low level, and the light emitting component LED does not emit light at the moment. However, when the metal foreign object is close to the wireless charging device, the light emitting component LED receives the comparison signal of high level to emit light, so as to warn the user to remove the foreign object, thereby preventing the metal foreign object from being influenced by the magnetic beam of the wireless charging device to generate eddy current, so that the metal foreign object is further heated to generate danger.
Please refer to fig. 6, which is a circuit layout diagram of a metal foreign object detection apparatus according to still another embodiment of the present invention. Unlike fig. 3 and 4, the relay 13 of the metallic foreign object detection apparatus according to the embodiment of the present invention shown in fig. 6 is connected to the foreign object detection coil 12 as a single detection coil L. Two ends of the detection coil L are respectively connected to the second end of the second switch SW2 and the second end of the first switch SW 1. The first terminal of the first switch SW1 and the first terminal of the second switch SW2 are respectively connected to the foreign object detection circuit 14, and the structure thereof is similar to that of fig. 3, and the auxiliary resonant circuit 141 and the oscillation detection circuit 142 are provided. The relay coil 131 of the relay 13 may be connected to the output terminal of the first digital signal processor 15 as shown in fig. 1 to switch the relay 13 on or off by the first digital signal processor 15.
The foreign object detection circuit 14 is connected to the display control unit 50, so that the display control unit 50 emits light when a metal foreign object approaches the wireless charging device. In addition, the oscillation detecting circuit 142 of the foreign object detecting circuit 14 includes a first resistor R1 and a second resistor R2. The first digital signal processor 15 controls the frequency and the power of the power signal transmitted by the transmitting coil 11 and the on/off of the detecting relay 13 according to the current flowing through the node NA between the first resistor R1 and the second resistor R2 or the voltage of the node NA, as shown in fig. 3, so as to determine whether the metal foreign object is close to the wireless charging device.
[ advantageous effects of the embodiments ]
The metal foreign object detection device provided by the invention has the beneficial effects that the metal foreign object detection device can be used for detecting whether the metal foreign object is placed above the wireless charging device or not, so that when the wireless charging device charges an electronic device such as a mobile phone (remote wireless), a pen power and the like, the metal foreign object interferes the charging of the wireless charging device and the metal foreign object is burnt due to overheating, and a charging circuit of the wireless charging device and a circuit component of the metal foreign object detection device are further influenced.
The disclosure above is only a preferred embodiment of the present invention and is not intended to limit the claims, so that all the modifications and equivalents of the disclosure and drawings are included in the claims.
Claims (10)
1. A metallic foreign object detection device adapted to a wireless charging device having a transmitting coil, a first digital signal processor and a receiving coil, wherein the transmitting coil transmits a power signal to the receiving coil during a power supply time, the metallic foreign object detection device comprising:
the foreign matter detection coil is arranged above the transmitting coil;
the relay is connected with the foreign matter detection coil; and
the foreign matter detection circuit is connected with the relay and the first digital signal processor;
the relay is started in the foreign matter detection time which is not the power supply time, and the foreign matter detection coil and the foreign matter detection circuit generate oscillation signals which are used as judgment basis for the fact that metal foreign matters are close to the wireless charging device.
2. The apparatus according to claim 1, wherein the relay comprises a relay coil, a diode, a first switch and a second switch, and the foreign object detection coil comprises a first coil and a second coil;
wherein a first end of the relay coil is connected with a positive end of the diode and the first digital signal processor, and a negative end of the diode is connected with a second end of the relay coil;
wherein the second end of the first switch is connected to the first end of the first coil;
wherein a second terminal of the second switch is connected to a second terminal of the first coil and a second terminal of the second coil.
3. The apparatus of claim 2, wherein the foreign object detection circuit further comprises an auxiliary resonant circuit and an oscillation detection circuit, wherein the auxiliary resonant circuit comprises a first transistor, a first capacitor and a second capacitor, a control terminal of the first transistor is connected to a common voltage source and a first terminal of the second capacitor, a first terminal of the first capacitor is connected to the common voltage source, a first terminal of the first transistor is connected to a second terminal of the first capacitor and a first terminal of the first coil, a second terminal of the first transistor is coupled to a reference potential, a second terminal of the second capacitor is connected to a first terminal of the second coil, the oscillation detection circuit comprises a second transistor and a third capacitor, a first terminal of the second transistor is connected to the common voltage source and a first terminal of the third capacitor, and the second end of the second transistor is connected with the second end of the third capacitor and grounded, and the control end of the second transistor is connected with the first end of the first transistor.
4. The apparatus as claimed in claim 3, wherein the auxiliary resonant circuit further comprises a potentiometer, the second terminal of the first transistor is grounded via the potentiometer, and the reference voltage varies according to a resistance value of the potentiometer.
5. The device as claimed in claim 3, wherein the oscillation detecting circuit further comprises a first resistor and a second resistor, one end of the first resistor is connected to the second end of the second transistor, one end of the second resistor is connected to the second end of the first resistor, the second end of the second resistor is grounded, the first digital signal processor is connected to a node between the first resistor and the second resistor, and the first digital signal processor controls the frequency and the electric quantity of the power signal transmitted by the transmitting coil and detects the on/off of the relay according to the current flowing through the node or the voltage of the node, so as to determine whether the metallic foreign object is close to the wireless charging device.
6. The apparatus according to claim 3, further comprising a display control unit, wherein the display control unit comprises a voltage follower, a comparator and a light emitting device, wherein a first input terminal of the voltage follower is connected to an output terminal of the voltage follower, a second input terminal of the voltage follower is connected to a node of the oscillation detecting circuit, and an output terminal of the voltage follower is connected to an input terminal of the first digital signal processor;
wherein a first input terminal of the comparator is connected to the node, a first terminal of a fourth capacitor is connected to the common voltage source and a second input terminal of the comparator, and the comparator is configured to compare voltages of the node and the fourth capacitor to output a comparison signal;
the light-emitting component is connected with the output end of the comparator and configured to emit light when the metal foreign object approaches the wireless charging device according to the comparison signal.
7. The device as claimed in claim 1, wherein when the power signal is transmitted from the transmitter coil, the third transistor of the first digital signal processor outputs a control signal to turn off the relay.
8. The device of claim 1, wherein the relay comprises a relay coil, a diode, a first switch and a second switch, the foreign object detection coil is a detection coil, a first end of the relay coil is connected to a positive end of the diode and the first digital signal processor, a negative end of the diode is connected to a second end of the relay coil, a second end of the first switch is connected to the first end of the detection coil, and a second end of the second switch is connected to the second end of the detection coil.
9. The apparatus according to claim 8, further comprising a display control unit connected to the foreign object detection circuit for emitting light when the foreign object approaches the wireless charging device.
10. The device of claim 8, wherein the foreign object detection circuit comprises an auxiliary resonant circuit and an oscillation detection circuit, wherein the oscillation detection circuit comprises a first resistor and a second resistor, the first digital signal processor is connected to a node between the first resistor and the second resistor, and the first digital signal controls the frequency and the amount of the power signal transmitted by the transmitting coil and the on/off of the relay according to a current flowing through the node or a voltage of the node to determine whether the foreign object is near the wireless charging device.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010955591.3A CN114189063A (en) | 2020-09-11 | 2020-09-11 | Metal foreign body detecting device |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010955591.3A CN114189063A (en) | 2020-09-11 | 2020-09-11 | Metal foreign body detecting device |
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| TW201739143A (en) * | 2016-04-25 | 2017-11-01 | 財團法人車輛研究測試中心 | Wireless power transmission device and structure of metal foreign matter detection coil thereof allow the controller to immediately stop matter the transmitting antenna to generate electromagnetic wave while detecting the metal foreign matter |
| CN109004771A (en) * | 2018-07-27 | 2018-12-14 | 浙江泰米电子科技有限公司 | A kind of wireless charger and foreign matter detecting method |
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| CN111211598A (en) * | 2020-02-12 | 2020-05-29 | 华为技术有限公司 | Wireless charging circuit, wireless charging method, wireless charging equipment and wireless charging system |
| CN111273357A (en) * | 2018-12-04 | 2020-06-12 | 财团法人车辆研究测试中心 | Controllable foreign matter detection device and method |
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| TW201739143A (en) * | 2016-04-25 | 2017-11-01 | 財團法人車輛研究測試中心 | Wireless power transmission device and structure of metal foreign matter detection coil thereof allow the controller to immediately stop matter the transmitting antenna to generate electromagnetic wave while detecting the metal foreign matter |
| CN110121665A (en) * | 2016-12-27 | 2019-08-13 | Tdk株式会社 | Detection device of metal foreign body, wireless power supply, wireless receiving device and Wireless power transmission system |
| CN109004771A (en) * | 2018-07-27 | 2018-12-14 | 浙江泰米电子科技有限公司 | A kind of wireless charger and foreign matter detecting method |
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