KR102493154B1 - Foreign Object Detector and wireless charging system - Google Patents

Abstract

The present invention relates to a foreign material detection device for determining whether a foreign material is present by sensing both an impedance change and an induced voltage change of a detection coil.

Description

Foreign object detection device and wireless charging system {Foreign Object Detector and wireless charging system}

The present invention relates to a foreign matter detection device and a wireless charging system of a wireless charging system.

As research on electronic devices continues, research on wireless charging systems that supply electrical energy to electronic devices is also being conducted.

Many companies are immersed in research and development on wireless charging systems for mobile terminals and wireless charging systems for electric vehicles.

During wireless charging, when a metal foreign substance is present between the transmitter and the receiver, there is a risk of fire by increasing the temperature of the system.

In order to detect these foreign substances, various foreign substance detection methods such as camera installation have been introduced, but additional devices are required and there is a problem in detection reliability.

An object of the present invention is to provide a foreign matter detection device used in a low-cost wireless charging system with high foreign matter detection reliability in order to solve the above problems.

In addition, an object of the present invention is to provide a wireless charging system including a foreign matter detection device.

The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, the foreign material detection device according to an embodiment of the present invention determines whether a foreign material is present by detecting both an impedance change and an induced voltage change of a detection coil.

Details of other embodiments are included in the detailed description and drawings.

According to an embodiment of the present invention, one or more of the following effects are provided.

First, there is an effect of providing a foreign matter detection device that is easy to install and inexpensive.

Second, the detection sensitivity is high, so that even small-sized foreign matter can be detected, and the reliability of foreign matter detection is increased.

Third, there is an effect of enabling foreign matter to be detected even during charging or in a non-charging state.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a diagram showing the appearance of a wireless charging system according to an embodiment of the present invention.
2 is a block diagram of a wireless charging system according to an embodiment of the present invention.
3 is a diagram referenced to describe a wireless charging method according to an embodiment of the present invention.
4 is a system configuration diagram of a foreign matter detection device according to an embodiment of the present invention.
5 is a side view of a combination of coils according to an embodiment of the present invention.
6A to 6B are diagrams referenced for explaining magnetic flux density in a combination of coils according to an embodiment of the present invention.
7 is a diagram referenced to describe a foreign matter detection device according to an embodiment of the present invention.
8 illustrates a part of the detection circuit when no induced voltage is generated.
9 illustrates a part of the detection circuit when an induced voltage is generated.
10 illustrates an induced voltage waveform when a foreign substance is introduced according to an embodiment of the present invention.
11 illustrates the output of the detection circuit when residual induced voltage is present according to an embodiment of the present invention.
12 is a diagram referenced for explaining a current of a detection coil when a residual induced voltage exists according to an embodiment of the present invention.
13A to 13D are diagrams referenced to describe first to third signal processors according to an embodiment of the present invention.
14 shows simulation waveforms according to the magnitude of a voltage induced in a detection coil according to an embodiment of the present invention.
15A is a diagram referenced to describe a second signal processing unit or a third signal processing unit according to an embodiment of the present invention.
16 is a flowchart referenced for explaining the operation of the foreign matter detection device according to the embodiment of the present invention.
17A is a diagram referenced to describe a signal processing unit according to an embodiment of the present invention.
FIG. 17B is a diagram referenced to describe a signal processed by the signal processing unit of FIG. 17A.
18A is a diagram referenced to describe a signal processing unit according to an embodiment of the present invention.
FIG. 18B is a diagram referenced to describe a signal processed by the signal processing unit of FIG. 18A.
19 is a flowchart referenced to explain the operation of the foreign matter detection device according to an embodiment of the present invention.

Hereinafter, the embodiments disclosed in this specification will be described in detail with reference to the accompanying drawings, but the same or similar elements are given the same reference numerals regardless of reference numerals, and redundant description thereof will be omitted. The suffixes "module" and "unit" for components used in the following description are given or used together in consideration of ease of writing the specification, and do not have meanings or roles that are distinct from each other by themselves. In addition, in describing the embodiments disclosed in this specification, if it is determined that a detailed description of a related known technology may obscure the gist of the embodiment disclosed in this specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in this specification, the technical idea disclosed in this specification is not limited by the accompanying drawings, and all changes included in the spirit and technical scope of the present invention , it should be understood to include equivalents or substitutes.

Terms including ordinal numbers, such as first and second, may be used to describe various components, but the components are not limited by the terms. These terms are only used for the purpose of distinguishing one component from another.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no other element exists in the middle.

Singular expressions include plural expressions unless the context clearly dictates otherwise.

In this application, terms such as "comprise" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

1 is a diagram showing the appearance of a wireless charging system according to an embodiment of the present invention.

2 is a block diagram of a wireless charging system according to an embodiment of the present invention.

Referring to the drawing, the wireless charging system 100 may include a power transmission device 10 and a power reception device 20.

The wireless charging system 100 may be used for wireless charging of electric vehicle batteries, wireless charging of mobile terminal batteries, and the like.

When the wireless charging system 100 is used for wireless charging of an electric vehicle battery, the power transmission device 10 may be installed in a charging station or the like, and the power reception device 20 may be provided inside the vehicle.

When the wireless charging system 100 is used for wireless charging of a battery of a mobile terminal, the power transmission device 10 may be configured in a portable format, and the power reception device 20 may be provided inside the mobile terminal. .

According to the embodiment, the power transmission device 10 is provided inside the vehicle, and a mobile terminal having the power reception device 20 and a wireless charging system may be configured.

The power transmission device 10 may include an AC/DC converter 11 , a DA/AC inverter 12 , a resonance tank 13 and a transmission pad 14 .

The AC/DC converter 11 may convert alternating current electrical energy provided from the grid 1 into direct current.

The DC/AC converter 12 converts electric energy in a direct current form into electrical energy in an alternating current form. At this time, the DC/AC converter 12 may generate a high-frequency signal of tens to hundreds of kHz.

The resonance tank 13 compensates for impedance suitable for wireless charging.

The transmission pad 14 transmits electrical energy wirelessly.

The transmission pad 14 includes a transmission coil 15 inside.

The power receiving device 20 may include a receiving pad 21 , a resonance tank 22 and a rectifier 23 .

The receiving pad 23 wirelessly receives electrical energy.

The receiving pad 23 includes a receiving coil 25 inside.

The transmitting pad 14 and the receiving pad 23 include a coil set (transmitting coil 15 and receiving coil 25) having magnetic coupling.

The transmitting pad 14 and the receiving pad 23 transfer electric energy through a magnetic field generated by a high-frequency driving signal without physical contact between electrodes.

When a metallic foreign object exists between the receiving pad 14 and the receiving pad 23, eddy current loss occurs. In this case, there is a risk of fire or the like.

The resonance tank 22 compensates for impedance suitable for wireless charging.

The rectifier 21 converts alternating current electrical energy into direct current electrical energy in order to supply direct current electrical energy to the battery 30 .

The battery 30 may be provided in a vehicle or mobile terminal.

3 is a diagram referenced to describe a wireless charging method according to an embodiment of the present invention.

Referring to FIG. 3 , the wireless charging system may use an inductive coupling method or a resonant coupling method.

In the inductive coupling method, when the intensity of the current flowing in the primary coil of two adjacent coils is changed, the magnetic field is changed by the current, which causes the magnetic field to pass through the secondary coil. It uses the principle that magnetic flux is changed and induced electromotive force is generated on the side of the secondary coil. That is, according to this method, an induced electromotive force is generated when only the current of the primary coil is changed while the two coils are brought close to each other without spatially moving the two wires. In this case, the frequency characteristics are not greatly affected, but the alignment and distance between the transmitting device (eg, wireless charging device) and the receiving device (eg, mobile terminal) including each coil (Distance) affects power efficiency.

In the Resonance Coupling method, a resonance frequency is applied to a primary coil of two coils separated by a certain distance, and a part of the magnetic field change generated by applying a resonance frequency to a secondary coil of the same resonance frequency ( It uses the principle that induced electromotive force is generated in the secondary coil by being applied to the coil. That is, according to this method, when the transmitting and receiving devices respectively resonate at the same frequency, electromagnetic waves are transmitted through a short-range electromagnetic field, so there is no energy transmission when the frequencies are different. In this case, the selection of frequency can be an important issue. Since there is no energy transfer between resonant frequencies spaced apart by a predetermined distance or more, a device to be charged may be selected through resonant frequency selection. If only one device is assigned to one resonant frequency, selection of the resonant frequency may mean selecting a device to be charged.

Compared to the inductive coupling method, the resonant coupling method has an advantage that an alignment and a distance between the transmitting device and the receiving device including each coil relatively less affect power efficiency.

4 is a system configuration diagram of a foreign matter detection device according to an embodiment of the present invention.

Referring to FIG. 4 , the foreign matter detection device 200 includes a combination of a plurality of detection coils and an induced voltage canceling coil (hereinafter, a combination of coils) 201a, 201b, ..., 201n (hereinafter, 201) and detection circuit 270.

The combination 201 of a plurality of coils may be located between the transmitting pad 14 and the receiving pad 21 .

For example, a combination 201 of a plurality of coils may be disposed on the transmission pad 14 .

For example, a combination 201 of a plurality of coils may be disposed on the receiving pad 21 .

A combination 201 of a plurality of coils may cover the transmission pad 14 .

For example, the transmission pad 14 may be formed in a rectangular shape. The induced voltage canceling coil 212 of the combination 201 of the plurality of coils may be formed in a polygonal shape. The combination of the combination 201 of a plurality of polygonal coils can cover the entire rectangular transmission pad 14 .

For example, the receiving pad 21 may be formed in a rectangular shape. The induced voltage canceling coil 212 of the combination 201 of the plurality of coils may be formed in a polygonal shape. The combination of the combination 201 of a plurality of polygonal coils can cover the entire rectangular reception pad 21 .

The combination 201 of a plurality of coils may sense an object.

Here, the object may be defined as a metallic foreign material located between the transmission pad 14 and the reception pad 21 .

If a metallic foreign substance is located between the transmitting pad 14 and the receiving pad 21, charging may not be performed smoothly, and safety problems may occur due to deterioration.

Each of the plurality of coil combinations 201 includes detection coils 210a, 210b, ..., 210n (hereinafter, 210) and induced voltage canceling coils 212a, 212b, ..., 212n (hereinafter, 212). can include

The detection coil 210 and the induced voltage canceling coil 212 may be stacked with each other.

For example, an induced voltage canceling coil 212 may be stacked on the detection coil 210 . In this case, the detection coil 210 may constitute a first layer, and the induced voltage canceling coil 212 may constitute a second layer.

For example, the detection coil 210 may be stacked on the induced voltage canceling coil 212 . In this case, the induced voltage canceling coil 212 may constitute a first layer, and the detection coil 210 may constitute a second layer.

For example, the detection coil 210 and the induced voltage canceling coil 212 are located at the center of the first shape defined by the winding of the coil in the detection coil 210 and the winding of the coil in the induced voltage canceling coil 210. may be stacked such that the center of the second shape defined by is matched. For example, an imaginary line connecting the center of the first shape and the center of the second shape may be perpendicular to the ground.

The combination 201 of a plurality of coils may be composed of a plurality of layers.

For example, the detection coil 210 and the induced voltage canceling coil 212 may be alternately disposed to form the first layer 291 .

For example, the induced voltage canceling coil 212 and the detection coil 210 may be alternately disposed to form the second layer 292 .

The detection circuit 270 is electrically connected to the combination 201 of a plurality of coils.

The detection circuit 270 may output a signal that is a basis for determining whether an object exists or not, based on data received from the combination 201 of a plurality of coils.

The detection circuit 270 may output a signal that is a basis for determining whether an object exists based on a change in impedance of the detection coil 210 .

5 is a side view of a combination of coils according to an embodiment of the present invention.

The detection coil 210 may be wound in a first direction.

For example, the first direction may be a clockwise direction.

The detection coil 210 may be wound a predetermined number of times in the first direction 311 .

The detection coil 210 may be wound a larger number of times than the induced voltage canceling coil 212 .

For example, the number of windings of the detection coil 210 may be determined based on a value obtained by multiplying the number of windings of the induced voltage canceling coil 212 by the ratio of the area of the first shape and the area of the second shape. The first shape may be a shape defined by coil winding of the detection coil 210 . The second shape may be a shape defined by winding of the coil of the induced voltage canceling coil 212 .

The detection coil 210 may have a first shape having a first area.

A first shape having a first area may be defined in the detection coil 210 by winding the coil.

In FIG. 6, a rectangle is exemplified as the first shape, but is not limited thereto, and the first shape may be a polygon, a circle, or an ellipse.

The first shape may be smaller than the second shape defined by winding of the coil in the induced voltage canceling coil 212 . That is, the first area may be smaller than the second area.

The number of windings of the detection coil 210 may be determined by the number of windings of the induced voltage canceling coil 212 .

For example, the number of windings of the detection coil 210 may be determined based on a value obtained by multiplying the number of windings of the induced voltage canceling coil 212 by the ratio of the area of the first shape and the area of the second shape. .

Due to this feature, object detection sensitivity can be maximized without canceling the inductance of the combination of coils while canceling the induced voltage due to the charging magnetic field.

As illustrated in FIG. 6A , the first shape may be a first rectangle.

The length of one side of the first rectangle may be 1/2 times the length of one side of the second rectangle.

Meanwhile, the first shape may have a shape different from the second shape.

For example, the first shape may be a rectangle and the second shape may be a hexagon.

For example, the first shape may be a hexagon and the second shape may be a rectangle.

For example, the first shape may be a circle, and the second shape may be a rectangle or a hexagon.

The first shape and the second shape may be determined by object detection sensitivity and shapes of the receiving pad and the transmitting pad.

The induced voltage canceling coil 212 may be wound in the second direction. The second direction may be a direction different from the first direction.

For example, the second direction may be counterclockwise.

The induced voltage canceling coil 212 may be wound a predetermined number of times in the second direction.

The induced voltage canceling coil may be wound fewer times than the detection coil 210 .

On the other hand, the number of windings may be named a turn.

The induced voltage canceling coil 212 may have a second shape having a second area.

A second shape having a second area may be defined by winding the coil in the induced voltage canceling coil 212 .

In FIG. 6A, a rectangle is exemplified as the second shape, but is not limited thereto, and the second shape may be a polygon, a circle, or an ellipse.

The second shape may be larger than the first shape defined by winding of the coil in the detection coil 210 . That is, the second area may be larger than the first area.

As illustrated in FIG. 6A , the second shape may be a second rectangle larger than the first rectangle.

In this way, since the first shape and the second shape have a rectangular shape, it is advantageous to cover the entirety of the rectangular transmitting pads 14 and receiving pads 21 by the plurality of sensing devices 201 .

The length of one side of the second quadrangle may be twice the length of one side of the first quadrangle.

Due to this characteristic, it is possible to cover the entirety of the rectangular transmitting pad 14 and the receiving pad 21 without a dead zone.

Here, the dead zone may be an area where no object is sensed.

The induced voltage canceling coil 212 may be wound around an area other than the area where the detection coil 210 is stacked.

The induced voltage canceling coil 212 is preferably wound around the outside of the second shape.

The induced voltage canceling coil 212 is preferably wound so as to be spaced apart from the detection coil 210 as far as possible.

The induced voltage canceling coil 212 may be wound 1 to 3 times.

When it is wound more than four times, the total inductance of the combination of coils 201 is reduced, and the sensitivity of object detection is reduced.

The number of windings of the detection coil 210 may be greater than the number of windings of the induced voltage canceling coil 212 .

Also, an area of the second shape of the induced voltage canceling coil 212 may be larger than an area of the first shape of the detection coil 210 .

Due to this, the induced voltage formed in the coil combination 201 by the external magnetic field is canceled by the voltage applied to each of the detection coil 210 and the induced voltage canceling coil 212 .

6A to 6B are diagrams referenced for explaining magnetic flux density in a combination of coils according to an embodiment of the present invention.

6A illustrates a top view of a combination 201 of coils.

6B shows magnetic flux densities at multiple points of a combination of coils 201 .

The foreign matter detection performance is determined depending on whether the offset of the induced voltage is offset to a level at which metal detection is possible.

The distribution of the magnetic field on the transmission pad 14 may not be uniform, which may degrade detection performance.

As shown in FIG. 6B, the magnetic field distribution shows nonlinear characteristics due to the shape of the inside of the detection coil 210. Due to this, the cancellation voltage by the induced voltage cancellation coil 212 is limited to several hundred mV.

This is the detection signal variation level when the impedance of the detection coil 210 is changed by a metal material such as a clip or nail.

Since the magnitude of the offset voltage for detecting a substance of a corresponding size must be several tens of mV, it is difficult to detect a metal substance of a small size using the corresponding method.

Hereinafter, a foreign material detection device capable of detecting a small-sized metal material will be described.

7 is a diagram referenced to describe a foreign matter detection device according to an embodiment of the present invention.

8 illustrates a part of the detection circuit when no induced voltage is generated.

9 illustrates a part of the detection circuit when an induced voltage is generated.

10 illustrates an induced voltage waveform when a foreign substance is introduced according to an embodiment of the present invention.

11 illustrates the output of the detection circuit when residual induced voltage is present according to an embodiment of the present invention.

12 is a diagram referenced for explaining a current of a detection coil when a residual induced voltage exists according to an embodiment of the present invention.

13A to 13D are diagrams referenced to describe first to third signal processors according to an embodiment of the present invention.

The foreign matter detection device 200 may detect foreign matter positioned between the transmission pad 14 and the reception pad 21 of the wireless charging system 100 .

Referring to the drawing, the foreign matter detection apparatus 200 includes at least one detection coil 210, at least one induced voltage canceling coil 212, a detection circuit 270, a first signal processor 241, and a second signal. A processing unit 242 and a third signal processing unit 243 may be included.

At least one detection coil 210, at least one induced voltage canceling coil 212, a detection circuit 270, a first signal processing unit 241, a second signal processing unit 242, and a third signal processing unit 243 , can be electrically connected to each other.

The detection coil 210 may be disposed on the transmission pad 14 or the reception pad 21 .

The induced voltage canceling coil 212 may be stacked with the detection coil 210 .

The induced voltage canceling coil 212 may cancel the induced voltage formed in the detection coil 210 .

The induced voltage may be generated by a magnetic field generated at the transmission pad 14 and/or the reception pad 21 during power transmission.

Descriptions of FIGS. 4 to 6B may be applied to the detection coil 210 and the induced voltage canceling coil 212 .

The detection circuit 270 may generate a signal for detecting a foreign substance located between the transmission pad 14 and the reception pad 21 .

Referring to FIG. 10 , as described above, even when the induced voltage formed in the detection coil 210 is canceled by the induced voltage canceling coil 212, the induced voltage some will remain

A of FIG. 10 shows the residual induced voltage of the detection coil 210 before inputting the metal material.

Due to the induced voltage canceling coil 212, the residual induced voltage of the detection coil 210 becomes smaller than the voltage value of the power supply unit 199.

10B shows a change in the residual induced voltage of the detection coil 210 after the metal material is input.

When the metal material is input, the induced voltage canceling function of the induced voltage canceling coil 212 is affected, so that the induced voltage applied to the detection coil 210 changes.

When the induced voltage changes, if the detection circuit 270 is designed so that the maximum value of the voltage change is lower than the voltage value of the power supply unit 199, the foreign matter detection function is performed at a level that does not cause malfunction/failure of the detection circuit 270. this becomes possible

11 can be described as an output waveform of the detection circuit 270. The output of the detection circuit 270 can be understood as a signal obtained by converting the current of the detection coil 210 into a voltage form.

11A shows an output waveform of the detection circuit 270 before the metal material is introduced.

11B shows an output waveform of the detection circuit 270 after the metal material is introduced.

Since the magnitude of the residual induced voltage is changed before and after inputting the metal material, the output aspect of the detection circuit 270 is changed before and after inputting the metal material.

Regardless of the residual induced voltage, the slope and peak value of the output of the detection circuit 270 vary according to the change in the impedance of the detection coil 210.

The actual waveform of FIG. 11 is a superposition of the amount of change according to the presence or absence of residual induced voltage and the amount of impedance change of the detection coil 210 .

Since the frequency of the residual induced voltage and the switching frequency of the switching unit 220 are different from each other, each output characteristic can be separated using a filter.

12 can be explained as a change in current flowing through the detection coil 210 by the current sensor 230 (or a change in amplified current).

When the switching frequency of the switching unit 220 is sufficiently greater than the frequency of the residual induced voltage, analysis is possible by dividing the residual induced voltage into a positive cycle and a negative cycle, as shown in the table of indicator 197. .

It can be seen that the calculated maximum current IL1 of the detection coil 210 in each condition is affected by the magnitude of the residual induced voltage and the switching frequency (1/TSW1) of the switching unit 220.

As illustrated in FIGS. 8 to 9 , the detection circuit 270 may include a power supply unit 199 , a switching unit 220 , a current sensing unit 230 , and a diode 239 .

The power supply unit 199 may supply direct current power (DC).

The switching unit 220 may be disposed between the DC power supply 199 and the detection coil 210 .

The switching unit 220 may control the connection between the DC power supply and the detection coil 210 .

The diode 239 may be a freewheeling diode. The diode 239 may be connected in parallel with the detection coil 210 . The diode 239 can prevent reverse flow.

The switching unit 220 may include a metal oxide semiconductor field effect transistor (MOSFET) controlled based on a pulse width modulation (PMW) signal.

The number of switching units 220 corresponding to the number of detection coils 210 may be provided.

A plurality of switches included in the switching unit 220 may be synchronized and simultaneously turned on or simultaneously turned off.

The current sensing unit 230 may sense a change in current flowing through the detection coil 210 according to turning on and off of the switching unit 220 .

The current sensing unit 230 may include a sensing resistor. In this case, the sensing resistor may be serially connected to the detection coil 210 .

The current sensing unit 230 may include a Hall element.

The number of current detectors 230 corresponding to the number of detection coils 210 may be provided.

Referring to FIGS. 13A to 13D , the first signal processing unit 241 may separate the first signal generated by the current sensing unit 230 into a second signal and a third signal based on a frequency band.

The first signal may be defined as a signal corresponding to a change in current flowing through the detection coil 210 according to a change in impedance in the presence of an induced voltage.

The first signal may be a signal having an RL transient response form.

The second signal may be defined as a signal based on the switching frequency of the switching unit 220 .

The switching frequency may have a frequency different from that of the induced voltage.

For example, the switching frequency may be hundreds of kHz or higher.

For example, the induced voltage may have a frequency of 80-90 kHz.

The third signal may be defined as a signal based on the frequency of the induced voltage formed in the detection coil 210 .

The first signal processing unit 241 may include an amplifier 701, an ADC 702, a low pass filter (LPF) 703 and a high pass filter (HPF) 704. there is.

The amplifier 701 may amplify the output signal of the detection circuit 270 . The amplifier 701 may amplify the first signal.

An analog-to-digital converter (ADC) 702 may convert the amplified analog output signal into a digital signal. The ADC 702 may convert the amplified first signal into a digital signal.

The low pass filter 703 may separate the second signal from the first signal.

The high pass filter 704 may separate the third signal from the first signal.

Depending on the embodiment, as illustrated in FIG. 13D , the low pass filter 703 and the high pass filter 704 may be omitted.

The second signal processor 242 may compare the second signal and the first reference signal to output a first determination signal.

For example, the second signal processor 242 may compare the integral value of the second signal with the reference value and output the first determination signal.

For example, the second signal processing unit 242 may compare the peak value of the second signal with the reference value and output the first discrimination signal.

For example, the second signal processing unit 242 may compare the average value of the second signal with the reference value and output the first determination signal.

For example, the second signal processing unit 242 may compare the maximum value of the second signal with the reference value and output the first discrimination signal.

For example, the second signal processing unit 242 may compare the slope of the second signal with a reference value and output the first discrimination signal.

For example, the second signal processing unit 242 may compare the maximum/minimum amount of change of the second signal with a reference value and output the first determination signal.

As illustrated in FIG. 13D , the second signal processing unit 242 synchronizes the output of the detection circuit 270 with the charging frequency between the transmitting pad 14 and the receiving pad 21 to compare positive cycles of the induced voltage or A first discrimination signal may be output through comparison between negative cycles.

The first discrimination signal may be a DC signal.

For example, the second signal processor 242 may generate a high signal when a difference occurs between the second signal and the first reference signal.

For example, the second signal processor 242 may generate a low signal when a difference does not occur between the second signal and the first reference signal.

The outputted first discrimination signal may be provided to the processor 271 .

The processor 271 may determine whether a foreign substance is present based on the first determination signal.

Meanwhile, sub-components of the second signal processing unit 242 will be described with reference to FIG. 15A and later.

The third signal processor 243 may compare the third signal and the second reference signal to output a second determination signal.

For example, the third signal processing unit 243 may compare the integral value of the third signal with the reference value and output the second discrimination signal.

For example, the third signal processing unit 243 may compare the peak value of the third signal with the reference value and output the second determination signal.

For example, the third signal processing unit 243 may compare the average value of the third signal with the reference value and output the second determination signal.

For example, the third signal processing unit 243 may compare the maximum value of the third signal with the reference value and output the second determination signal.

For example, the third signal processing unit 243 may compare the slope of the third signal with a reference value and output a second determination signal.

For example, the third signal processing unit 243 may output a second discrimination signal by comparing the maximum/minimum amount of change of the third signal with a reference value.

As illustrated in FIG. 13D , the second signal processing unit 243 synchronizes the output of the detection circuit 270 with the charging frequency between the transmitting pad 14 and the receiving pad 21 to compare positive cycles of the induced voltage or A second discrimination signal may be output through comparison between negative cycles.

The second discrimination signal may be a DC signal.

For example, the third signal processor 243 may generate a high signal when a difference occurs between the third signal and the second reference signal.

For example, the third signal processor 243 may generate a low signal when a difference does not occur between the third signal and the second reference signal.

The output second determination signal may be provided to the processor 271 .

The processor 271 may determine whether a foreign substance is present based on the second determination signal.

Meanwhile, sub-structures of the third signal processing unit 243 will be described with reference to FIG. 15A and later.

The processor 271 may be electrically connected to each component of the foreign material detection device 200 .

The processor 271 may control each component of the foreign material detection device.

The processor 271 may determine whether or not there is a foreign substance located between the transmission pad 14 and the reception pad 21 according to a signal based on the second signal and the third signal.

The processor 271 may determine whether an object exists based on the change in impedance of the detection coil 210 .

For example, when a high signal is received from the second signal processor 242, the processor 271 may determine that a foreign substance exists between the transmission pad 14 and the reception pad 21.

The processor 271 may determine whether an object exists based on an induced voltage value applied to the detection coil 210 .

For example, when a high signal is received from the third signal processor 243, the processor 271 may determine that a foreign substance exists between the transmission pad 14 and the reception pad 21.

The processor 271 may generate a signal for outputting an alarm when it is determined that a foreign material exists between the transmission pad 14 and the reception pad 21 .

Depending on the embodiment, the foreign matter detection device 200 may include a separate alarm unit.

The processor 271 may control the alarm unit to output an alarm.

The processor 271 may provide a signal for stopping wireless charging to the wireless charging system 100 .

Depending on the embodiment, the processor 271 may serve as the second signal processing unit 242 and the third signal processing unit 243 .

Meanwhile, the foreign material detection apparatus 200 may further include a memory.

The memory may store a reference value to be described later.

According to embodiments, memory may be classified as a sub-element of the processor 271 .

Meanwhile, the processor 271 includes application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), and processors. , controllers, micro-controllers, microprocessors, and other electrical units for performing functions.

14 shows simulation waveforms according to the magnitude of a voltage induced in a detection coil according to an embodiment of the present invention.

Referring to FIG. 14 , indicator 1401 indicates three waveforms (green: 0V, blue: 2V, red: 5V) according to the magnitude of the voltage induced in the detection coil 210.

Indicator 1402 indicates a current waveform of the detection coil 210 accordingly.

It can be confirmed that the current of the detection coil 210 increases in a section where the magnitude of the voltage induced in the detection coil 210 becomes smaller than zero.

As the induced voltage decreases, it can be seen that not only the peak current but also the waveform having the form of a sinusoidal wave is seen.

This is because the switch turn-on time is shorter than the time for the current to decay to zero. Rather, it is more helpful for detection performance because it can clearly show the change in induced voltage.

15A is a diagram referenced to describe a second signal processing unit or a third signal processing unit according to an embodiment of the present invention.

FIG. 15B is a diagram referenced to describe a signal processed in FIG. 15A

Referring to FIGS. 15A and 15B , the second signal processing unit 242 may compare the two signals with the first reference signal and output a first determination signal.

The second signal processor 242 may include an integrator 720 and a comparator 730 .

The integrator 720 may integrate the second signal for a preset period of time.

The integrator 720 may output a signal by integrating the second signal for a preset time.

Indicator codes 741 and 742 illustrate second signals integrated over a preset time period.

In particular, indicator code 741 illustrates a case in which a foreign material exists around the detection coil 210, and indicator code 742 illustrates a case in which a foreign material does not exist around the detection coil 210.

Since the current value of the detection coil is different depending on the presence or absence of foreign matter, a difference occurs in the speed at which the integrator output reaches the reference value. Foreign substances can be detected by setting an appropriate reference value using these characteristics.

Comparing the output signals of the integrator according to the presence or absence of foreign matter, when there is a foreign matter at the detection time point (t') (741), the output voltage is higher than the reference value (740). When there is no foreign matter (742), the output voltage is less than the reference value (740) at the time of detection.

It is possible to adjust the sensitivity of the foreign matter detection circuit suitable for the application environment by adjusting the reference value 740 and the detection time point (calibration process).

The waveform of FIG. 15B is a theoretical example of a specific situation, and the waveform characteristics of the presence and absence of foreign matter may be reversed according to the actual measurement process and the physical properties of the foreign matter to be detected.

The comparator 730 may compare the output value 741 of the integrator 720 and the reference value 740 .

The comparator 730 may output a high signal when the output value 741 of the integrator 720 is greater than or equal to the reference value 740 .

When receiving a high signal, the processor 271 may determine that a metallic foreign material exists around the detection coil 210 .

The comparator 730 may output a low signal when the output value 741 of the integrator 720 is smaller than the reference value 740 .

When receiving a low signal, the processor 271 may determine that there is no metallic foreign material around the detection coil 210 .

Meanwhile, the reference value 740 may be a value set by a test for a current flowing through the detection coil 210 in a state in which there is no foreign matter. The reference value 740 may be a value set based on a value obtained by integrating a current signal flowing through the detection coil 210 for a preset period of time.

Due to this detection method, even minute differences in current values that change due to the presence of foreign substances can be detected through integration, thereby increasing the sensitivity of detecting foreign substances.

Meanwhile, the third signal processing unit 243 may compare the third signal and the second reference signal to output a second determination signal.

The third signal processor 243 may include an integrator 720 and a comparator 730 .

For the integrator 720 and the comparator 730 included in the third signal processor 243, the description of the integrator 720 and the comparator 730 described in FIGS. 15A and 15B may be applied.

16 is a flowchart referenced for explaining the operation of the foreign matter detection device according to the embodiment of the present invention.

Referring to FIG. 16 , the processor 271 may perform calibration. The processor 271 may set a reference value.

The processor 271 may perform a reset operation of the integrator 720 (S810).

In the foreign matter detection method using the integrator 720, a reset operation is necessarily performed before and after detection to prevent the output signal of the integrator 720 from being saturated (eg, a phenomenon in which the maximum value of the output signal of the amplifier is limited to the supply voltage). It should be.

At a detection time point t′ after a certain time elapses after the integrator reset t ₀ , the comparator 730 may output a low signal when there is no foreign material and a high signal when there is a foreign material (S820).

The processor 271 may determine whether the signal received from the comparator 730 is a high signal (S830).

When the received signal is determined to be a high signal, the processor 271 may generate and provide a signal for alarm output (S840).

Thereafter, the processor 271 resets the integrator 720 to repeatedly perform foreign material detection.

17A is a diagram referenced to describe a signal processing unit according to an embodiment of the present invention.

FIG. 17B is a diagram referenced to describe a signal processed by the signal processing unit of FIG. 17A.

Referring to FIGS. 17A and 17B , the second signal processing unit 242 may compare the two signals with the first reference signal and output a first discrimination signal.

The second signal processor 242 may include a peak detector 721 and a comparator 730 .

The peak detector 721 may detect a peak value of the second signal.

The peak detector 721 may detect a peak value of the second signal and output a signal.

Designation numerals 941 and 942 illustrate signals generated by the peak detector 721 .

When there is a foreign substance, the peak value of the sensed value waveform changes due to the change in inductance of the detection coil 210 . Foreign substances can be detected by setting an appropriate reference value using these characteristics.

The comparator 730 may compare the output values 941 and 942 of the peak detector 721 with the reference value 940 .

The comparator 730 may output a high signal when the output value 942 of the peak detector 721 is equal to or greater than the reference value 940 .

When receiving a high signal, the processor 271 may determine that a metallic foreign material exists around the detection coil 210 .

The comparator 730 may output a low signal when the output value 941 of the peak detector 721 is smaller than the reference value 940 .

When receiving a low signal, the processor 271 may determine that there is no metallic foreign material around the detection coil 210 .

Meanwhile, the reference value 940 may be a value set by a test for a current flowing through the detection coil 210 in a state in which there is no foreign matter. The reference value 940 may be a value set based on a peak value of a current flowing through the detection coil 210 .

Meanwhile, the third signal processing unit 243 may compare the third signal and the second reference signal to output a second discrimination signal.

The third signal processor 243 may include a peak detector 721 and a comparator 730 .

For the peak detector 721 and the comparator 730 included in the third signal processor 243, the description of the peak detector 721 and the comparator 730 described in FIGS. 17A and 17B may be applied.

18A is a diagram referenced to describe a signal processing unit according to an embodiment of the present invention.

FIG. 18B is a diagram referenced to describe a signal processed by the signal processing unit of FIG. 18A.

Referring to FIGS. 18A and 18B , the second signal processor 242 may compare the two signals with the first reference signal and output a first determination signal.

The second signal processor 242 may include a low pass filter 722 and a comparator 730 .

The low-pass filter 722 may extract an average value of the second signal.

The low-pass filter 722 may output a signal by extracting an average value of the second signal.

Designation numerals 1141 and 1142 illustrate signals generated by the low-pass filter 722.

When there is a foreign substance, the equivalent resistance of the detection coil 210 increases so that the average value of the sensed value waveform sensed by the current sensor 230 is lowered by the following equation.

math formula

The comparator 730 may compare the output values 1141 and 1142 of the low-pass filter 722 with the reference value 1140.

The comparator 730 may output a low signal when the output value 1141 of the low pass filter 722 is greater than the reference value 1140 .

When receiving a low signal, the processor 271 may determine that there is no metallic foreign material around the detection coil 210 .

The comparator 730 may output a high signal when the output value 1142 of the low pass filter 722 is equal to or less than the reference value 1140 .

When receiving a high signal, the processor 271 may determine that a metallic foreign material exists around the detection coil 210 .

Meanwhile, the reference value 1140 may be a value set by a test for a current flowing through the detection coil 210 in the absence of foreign matter. The reference value 1140 may be a value set based on an average value of current flowing through the detection coil 210 .

Meanwhile, the third signal processing unit 243 may compare the third signal and the second reference signal to output a second discrimination signal.

The third signal processor 243 may include a low pass filter 722 and a comparator 730 .

The description of the low-pass filter 722 and comparator 730 included in the third signal processor 243 may be applied to the low-pass filter 722 and comparator 730 described in FIGS. 18A and 18B.

19 is a flowchart referenced to explain the operation of the foreign matter detection device according to an embodiment of the present invention.

Referring to FIG. 19 , the processor 271 may perform calibration. The processor 271 may set a reference value.

The comparator 730 may output a low signal when there is no foreign material and a high signal when there is a foreign material (S1210).

The processor 271 may determine whether the signal received from the comparator 730 is a high signal (S1220).

When the received signal is determined to be a high signal, the processor 271 may generate and provide a signal for outputting an alarm (S1230).

Thereafter, the processor 271 resets the low-pass filter 722 to repeatedly perform foreign matter detection.

The above-described present invention can be implemented as computer readable code on a medium on which a program is recorded. The computer-readable medium includes all types of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable media include Hard Disk Drive (HDD), Solid State Disk (SSD), Silicon Disk Drive (SDD), ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc. , and also includes those implemented in the form of a carrier wave (eg, transmission over the Internet). Also, the computer may include a processor or a control unit. Accordingly, the above detailed description should not be construed as limiting in all respects and should be considered illustrative. The scope of the present invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

100: wireless charging system
200: foreign matter detection device

Claims (11)

at least one detection coil disposed between the transmitting pad and the receiving pad;
a switching unit disposed between a DC power source and the detection coil;
a current detector sensing a change in current flowing through the detection coil according to turning on and off of the switching unit;
a first signal processor configured to separate the first signal generated by the current sensor into a second signal and a third signal based on a frequency band; and
Based on at least one of the second signal and the third signal, a processor for determining whether or not there is a foreign substance located between the transmission pad and the reception pad; includes,
The first signal processing unit,
Separating the second signal from the first signal based on the switching frequency of the switching unit;
and separating the third signal from the first signal based on the frequency of the induced voltage formed in the detection coil. delete According to claim 1,
The first signal processing unit,
a low pass filter separating the second signal from the first signal; and
and a high pass filter separating the third signal from the first signal. According to claim 1,
A second signal processor configured to compare the second signal with the first reference signal and output a first discrimination signal;
the processor,
A foreign material detection device for determining whether a foreign material is present based on the first determination signal. According to claim 4,
The second signal processing unit,
an integrator integrating the second signal for a predetermined time period; and
Foreign material detection device comprising a; comparator for comparing the output value of the integrator and a reference value. According to claim 4,
The second signal processing unit,
a peak detector detecting a peak value of the second signal; and
and a comparator for comparing an output value of the peak detector with a reference value. According to claim 4,
The second signal processing unit,
a low-pass filter extracting an average value of the second signal; and
and a comparator for comparing an output value of the low-pass filter with a reference value. According to claim 3,
A third signal processor configured to compare the third signal and a second reference signal and output a second discrimination signal;
the processor,
A foreign material detection device for determining whether a foreign material is present based on the second determination signal. According to claim 1,
The foreign material detection device further comprising: an induced voltage canceling coil stacked with the detection coil and canceling an induced voltage formed in the detection coil. According to claim 9,
The detection coil is wound in a first direction,
The induced voltage canceling coil is wound in a second direction a smaller number of times than the detection coil. According to claim 9,
The first shape defined by the winding of the coil in the detection coil,
The foreign matter detection device smaller than the second shape defined by the winding of the coil in the induced voltage canceling coil.

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