KR20210132629A - Apparatus and method for detecting foreign object in wireless power transmitting system - Google Patents

Abstract

The present invention relates to a device and a method for detecting a foreign object in a wireless power transmission system. According to the present specification, a wireless power transmission device comprises: a primary core block for transmitting wireless power to a wireless power receiving device by being combined with a secondary core block provided in the wireless power receiving device by magnetic induction or magnetic resonance; an electric driving unit connected to the primary core block, and applying an AC signal necessary for the primary core block to transmit the wireless power; a control unit coupled to the electric driving unit, and generating a control signal to control the AC signal; and a current measuring unit for measuring current flowing through the primary core block, and obtaining a current measurement value obtained by converting the current into a numerical value suitable to be analyzed by the control unit. Accordingly, a foreign object between the wireless power transmission device and the wireless power receiving device can be recognized without the assistance of the wireless power receiving device. Also, when a foreign object is detected, wireless power transmission is stopped or a user is allowed to remove the foreign object.

Description

Apparatus and method for detecting foreign substances in a wireless power transmission system

The present invention relates to wireless power transmission, and more particularly, to an apparatus and method for detecting foreign substances in a wireless power transmission system.

In general, in order to charge a portable terminal such as a mobile phone, a notebook computer, or a PDA, the portable terminal needs to receive electrical energy (or power) from an external charger. Such a portable terminal includes a battery cell for storing the supplied electrical energy and a circuit for charging and discharging the battery cell (supplying electrical energy to the portable terminal).

The electrical connection method between a charger and a battery cell for charging electric energy to a battery cell is to receive commercial power, convert it into voltage and current corresponding to the battery cell, and supply electric energy to the battery cell through the terminal of the battery cell. Includes terminal supply method.

This terminal supply method is accompanied by the use of a physical cable or wire. Therefore, when handling a lot of terminal-supply type equipment, many cables occupy a considerable work space, are difficult to organize, and are not good in appearance. In addition, the terminal supply method may cause problems such as an instantaneous discharge phenomenon due to a different potential difference between the terminals, burnout and fire caused by foreign substances, natural discharge, and deterioration of the life and performance of the battery pack.

Recently, in order to solve the above problems, a charging system (hereinafter referred to as a wireless power transmission system) and control methods using a wireless power transmission method have been proposed. The wireless power transmission method is also referred to as a contactless power transmission method or a no point of contact power transmission method. The wireless power transmission system includes a wireless power transmission device for supplying electrical energy in a wireless power transmission method, and a wireless power reception device for charging a battery cell by receiving electrical energy wirelessly supplied from the wireless power transmission device.

In the terminal supply method, if the terminal is connected well between the charger and the terminal, it is unlikely that there will be obstacles such as foreign substances that interfere with charging. On the other hand, in the wireless power transmission system, due to the characteristic of contactless charging, foreign substances may be inserted between the wireless power receiver and the wireless power transmitter during charging. If a foreign substance such as metal is caught between the wireless power transmitter and the wireless power receiver, power transmission may not be performed smoothly due to the foreign substance, and problems such as product burnout and explosion may occur due to overload and heat of foreign substances. have. Accordingly, there is a need for an apparatus and method capable of detecting foreign substances in a wireless power transmission system.

An object of the present invention is to provide an apparatus and method for detecting foreign substances in a wireless power transmission system.

Another technical object of the present invention is to provide an apparatus and method for detecting foreign substances based on a current induced in a primary coil in a wireless power transmission system.

Another technical object of the present invention is to provide an apparatus and method for performing an operation corresponding to detection of foreign substances in a wireless power transmission system.

Another technical object of the present invention is to provide a wireless power transmission apparatus and method having a foreign matter detection function in a wireless power transmission system.

According to one aspect of the present invention, there is provided a wireless power transmitter for detecting foreign substances. The device is connected to the primary core block and the primary core block for transmitting wireless power to the wireless power receiver by combining the secondary core block provided in the wireless power receiver by magnetic induction or magnetic resonance, and An electric driving unit for applying an alternating current (AC) signal required for the primary core block to transmit the wireless power, a control unit connected to the electric driving unit and generating a control signal for controlling the AC signal, and the 1 and a current measuring unit for measuring a current flowing in the car core block and obtaining a current measured value obtained by converting the current into a numerical value suitable for interpretation by the control unit.

The control unit may detect a foreign substance existing between the wireless power transmitter and the wireless power receiver based on a result of comparing the current measurement value with a reference value.

According to another aspect of the present invention, there is provided a method for detecting foreign substances by a wireless power transmitter having a primary core block. The method comprises the steps of applying an AC signal necessary for transmitting wireless power to the primary core block, and combining the secondary core block provided in the wireless power receiver and the primary core block by magnetic induction or magnetic resonance. Transmitting wireless power to the wireless power receiver, measuring the current flowing in the primary core block to obtain a current measurement value, and based on a result of comparing the current measurement value with a reference value, the wireless power transmission and detecting a foreign substance present between the device and the wireless power receiver.

The wireless power transmitter according to the present invention can recognize a foreign substance stuck between the wireless power transmitter and the wireless power receiver without the help of the wireless power receiver, and when a foreign substance is detected, stop the wireless power transmission or cause the user to By removing the foreign material, it is possible to prevent damage to the device due to the foreign material.

1 illustrates components of a wireless power transmission system according to an example of the present invention.
2 is a block diagram illustrating a wireless power transmitter according to an example of the present invention.
3 is a block diagram illustrating a wireless power transmitter according to another example of the present invention.
4 is an operation flowchart of a wireless power transmission system according to an example of the present invention.
5 is an operation flowchart of a wireless power transmitter according to an example of the present invention.
6 is an operation flowchart of a wireless power transmitter according to another example of the present invention.

As used hereinafter, the term "wireless power" is used to mean any form of energy associated with electric, magnetic, electromagnetic fields, etc. transmitted from a transmitter to a receiver without the use of physical electromagnetic conductors. Wireless power may also be referred to as a power signal, and may refer to an oscillating magnetic flux enclosed by a primary coil and a secondary coil. Power conversion in a system is described herein for wirelessly charging devices including, for example, mobile phones, cordless phones, iPods, MP3 players, headsets, and the like. In general, a basic principle of wireless energy transfer includes, for example, a magnetic induction coupling method or a magnetic resonance coupling (ie, resonance induction) method using frequencies less than 30 MHz. However, a variety of frequencies may be used, including frequencies that permit license-exempt operation at relatively high emission levels, for example below 135 kHz (LF) or at 13.56 MHz (HF).

1 illustrates components of a wireless power transmission system according to an example of the present invention.

Referring to FIG. 1 , a wireless power transmission system 100 includes a wireless power transmitter 110 and one wireless power receiver 150-1 or n wireless power receivers 150-1, ..., 150 -n).

The wireless power transmitter 110 includes a primary core block. The primary core block may include a core and one or more primary coils 111 . The wireless power transmitter 110 may have any suitable shape, but one preferred configuration is a flat platform with a power transmission surface, on or near the platform, each wireless power receiver 150-1, ...,150-n) may be located.

The wireless power receivers 150-1, ..., 150-n are detachable from the wireless power transmitter 110, and each of the wireless power receivers 150-1, ..., 150-n is When in the vicinity of the wireless power transmitter 110 is provided with a secondary core block (secondary core block) coupled with the electromagnetic field generated by the primary core block of the wireless power transmitter 110. The secondary core block may include one or more secondary coils 151 .

The wireless power transmitter 110 transmits power to the wireless power receivers 150-1, ..., 150-n without direct electrical contact. In this case, the primary core block and the secondary core block are said to be magnetically inductively coupled or resonantly inductively coupled to each other. The primary coil or the secondary coil may have any suitable shape, but may be, for example, a copper wire wound around a high permeability formation such as ferrite or an amorphous metal.

The wireless power receivers 150-1, ..., 150-n are usually connected to an external load (not shown here, also referred to as an actual load of the wireless power receiver), and wirelessly from the wireless power transmitter 110 The received power is supplied to an external load. For example, the wireless power receivers 150-1, ..., 150-n may be transported to objects that consume or store power, such as portable electric or electronic devices or rechargeable battery cells or batteries, respectively.

2 is a block diagram illustrating a wireless power transmitter according to an example of the present invention.

Referring to FIG. 2 , the wireless power transmitter 200 includes a primary coil 210 , an electric driving unit 220 , a control unit 230 , and a current measuring unit 240 .

The electric driving unit 220 is connected to the primary coil 210 to apply electric driving signals to the primary coil 210 to generate an electromagnetic field.

The control unit 230 is connected to the electric driving unit 220 and generates a control signal 231 for controlling an AC signal required when the primary coil 210 generates an induced magnetic field or generates magnetic resonance.

The current measuring unit 240 measures the current flowing through the primary coil 210 . In particular, the current measured by the current measuring unit 240 may be an alternating current. The current measuring unit 240 may be a current sensor. Alternatively, the current measuring unit 240 may be a transformer that lowers the high current flowing through the primary coil to a low current.

The current measurement unit 240 obtains a current measurement value I _measured from the current flowing in the primary coil 210 and inputs it to the control unit 230 . The measured current I _measured may be converted into a DC value suitable for recognition by the control unit 230 . That is, the current measuring unit 240 measures a relatively high alternating current flowing through the primary coil 210, and maps the _{measured high current to a current measured value I measured, which is a value suitable for the control unit 230 to interpret (} mapping), and input the current measured value I _measured to the control unit 230 .

Hereinafter, an operation of each component of the wireless power transmitter 200 for detecting a foreign object is specifically disclosed.

When the control unit 230 sends the control signal 231 corresponding to the reference AC signal to the electric drive unit 220 , the electric drive unit 220 applies the reference AC signal to the primary coil 210 . Here, the reference AC signal is an environment free of foreign substances, that is, in an environment free of obstacles to the transmission of wireless power, so that the transmission efficiency of wireless power stays within a normal range (or that can satisfy the power requirement level of the receiving device) It may be a value obtained experimentally as an AC signal. When the reference AC signal is applied to the primary coil 210 , the reference current I _ref flows through the primary coil 210 , and at this time, the wireless power W _ref is transmitted.

However, if a foreign substance appears between the wireless power transmitter 200 and the wireless power receiver, the wireless power receiver receives only _{W ref} -W _FO , which is the remaining power except _{for the power W FO consumed by the foreign substance.} From the standpoint of the wireless power receiver, if W _F0 is not received, a power increase request message is transmitted to the wireless power transmitter 200 to request more power. The power up request message may be referred to as a control error packet. Conversely, when the wireless power receiver receives power greater than or equal to the required power, it may transmit a power down request message to the wireless power transmitter 200 .

The wireless power receiver may continuously transmit a power up request message or a power down request message to the wireless power transmitter 200 until the required power is satisfied. For example, the wireless power transmitter 200 receiving the power increase request message increases the intensity of the current flowing through the primary coil 210 so that higher power is transmitted as a response accordingly. More specifically, in order to cause a larger current to flow in the primary coil 210 , the control unit 230 controls the control signal 231 so that an AC signal greater than the reference AC signal can be applied to the primary coil 210 . ) can be adjusted. This series of processes is collectively referred to as power control.

As a result of the power control, a _{state in which the measured} current I measured in the primary coil 210 is greater than a predetermined period may occur. _{That I measured} , a current greater than the _{reference current I ref} , is flowing through the primary coil 210 for the transmission of the required power, it means that the transmission efficiency of wireless power is lowered, and at the same time, It may mean that a certain amount of power is continuously consumed by the As such, when a relatively excessive current flows in the primary coil 210 , the control unit 230 determines that a foreign material is present. That is, the control unit 230 may detect an element, for example, a foreign material, such as a metal, that may interfere with the transmission of wireless power based on the _{current measured value I measured .}

The control unit 230 may use _{any one or a combination of two or more parameters such as a reference current I ref} , a reference range (I _low to I _high ), a reference AC signal, and a foreign material detection time t for foreign material detection. In addition, parameters such as the reference current I _ref , the reference range (I _low to I _high ), the reference AC signal, and the foreign material detection time t may be stored in the control unit 230 as initial setting values. The reference current I _ref and the reference range I _low to I _high may be referred to as a reference value.

As an example, the control unit 230 compares the _{current measured value I measured} with the reference current I _{ref .} In addition, when the _measured current I measured exceeds the reference current I _ref (ie, I _measured > I _ref ), it is determined that a foreign material is detected. On the other hand, if the measured current I _measured is equal to or less than the reference current I _{ref (ie, I measured} ≤ I _ref ), it is determined that there is no foreign material. Here, the reference current I _ref may be defined, for example, as follows according to the rated power (W) of the wireless power receiver.

Rx power(unit : W) Tx AC current(unit : A) Max AC current(unit : A) 2.5 0.998 1.05 3 1.328 1.5 4 1.664 1.85 5 1.925 2.05

Referring to Table 1, when the rated power (W) of the wireless power receiver (Rx) is 2.5W, 3W, 4W, or 5W, the AC current flowing through the primary core block of the wireless power transmitter (Tx) is experimentally 0.998A, 1.328A, 1.664A, and 1.925A, respectively. In addition, the allowable reference current in the primary core block, that is, I _ref , is 1.05A, 1.5A, 1.85A, and 2.05A, respectively.

As another example, the control unit 230 checks whether _{the current measured value I measured} falls within the reference range I _low to I _{high .} And if the current measured value I _measured falls within the reference range (ie, I _low ≤ I _measured ≤ I _high ), it is determined that there is no foreign material. On the other hand, if the current measured value I _measured does not fall within the reference range (ie, I _measured > I _high or I _measured < I _low ), it is determined that the foreign material is detected.

The control unit 230 may attempt to detect the foreign material at a time t predetermined by the system or standard.

As an example, the time t at which the control unit 230 attempts to detect foreign substances may be after every power control time. For example, after the wireless power transmitter 200 receives a power up request message or a power down request message from the wireless power receiver to raise or lower the AC signal, the measured current flowing through the primary coil 210 can be used to detect foreign substances.

As another example, the time t at which the control unit 230 attempts to detect the foreign material may be a predetermined constant detection period. For example, the detection period should be at least shorter than the time it takes for the foreign material to generate heat above a certain temperature. This is because, if the heat of foreign substances becomes severe, it may cause serious safety problems such as fire and burns of the body. Therefore, it is preferable that the detection cycle is set to a value whose stability has been verified by an experiment, thereby preventing various risks that may be caused during charging, such as heat generated by foreign substances during wireless charging.

When a foreign material is detected, the control unit 230 blocks the wireless power transmission by controlling the electric driving unit 220 so as not to apply an AC signal to the primary coil 210 .

3 is a block diagram illustrating a wireless power transmitter according to another example of the present invention.

Referring to FIG. 3 , the wireless power transmitter 300 includes a primary core block 310 including m primary coils 310-1, ... 310-m, a switching unit 320, and an electric drive. It includes a unit 330 , a control unit 340 and a current measurement unit 350 .

The switching unit 320 selectively connects all or at least one of the m primary coils 310-1, ... 310-m to the electric driving unit 330 by a switching method.

The electric driving unit 330 may be connected to the m primary coils 310-1, ... 310-m through the switching unit 320, and the n primary coils 310-1 to generate an electromagnetic field. ,...310-n) or at least one primary coil selected from among the n primary coils 310-1, ...310-n, the electric driving signals are applied.

The control unit 340 is connected to the electric drive unit 330, and controls the AC signal required when the n primary coils 310-1, ... 310-n generate an induced magnetic field or generate resonance. A control signal 341 is generated.

The current measuring unit 350 measures the currents flowing through the m primary coils 310-1, ... 310-m individually or by summing them. In particular, the current measured by the current measuring unit 240 may be an alternating current. The current measuring unit 240 may be a current sensor. Alternatively, the current measuring unit 240 may be a transformer that lowers the high current flowing through the primary coil to a low current.

As an example, the current measuring unit 350 selects only the primary coil through which current flows from the m primary coils 310-1, ... 310-m, and individually measures the current flowing through each of the selected primary coils. and a plurality of individual current measurement values I ₁ , I ₂ , ...I _m are acquired and input to the control unit 340 . Current measurement values I ₁ , I ₂ , ...I _m may be converted into DC values suitable for recognition by the control unit 340 . That is, the current measuring unit 350 measures a relatively high alternating current flowing in the primary coils 310-1, ..., 310-m, and the control unit 340 is suitable for interpreting the measured high current. The numerical current measured values I ₁ , I ₂ , ...I _m are mapped as shown in Table 1, and the current measured values I ₁ , I ₂ , ...I _m are input to the control unit 340 . do.

As another example, the current measurement unit 350 selects only the primary coil through which current flows from the m primary coils 310-1, ... 310-m, and measures the current flowing through the selected primary coil. , one total current measurement value I _SELECTED is input to the control unit 340 .

As another example, the current measurement unit 350 measures the total current flowing in all of the m primary coils 310-1, ... 310-m, and transmits one total current measurement value I _TOTAL to the control unit ( 340).

The control unit 340 may use _{any one or a combination of two or more parameters such as a reference current I ref} , a reference range (I _low to I _high ), a reference AC signal, and a foreign material detection time t for foreign material detection. In addition, parameters such as the reference current I _ref , the reference range (I _low to I _high ), the reference AC signal, and the foreign material detection time t may be stored in the control unit 340 as initial setting values.

As an example, the control unit 340 _{compares the current measurements I 1} , I ₂ ,...I _m with the reference current I _ref , respectively. and if at least one of the current measurements I ₁ , I ₂ ,...I _{m exceeds the reference current I ref} (ie I ₁ or I ₂ or ...I _m > I _ref ), foreign matter judged to have been detected. On the other hand, if the current measurement values I ₁ , I ₂ , ...I _m are all below the reference current I _ref (ie, I ₁ and I ₂ and ...I _m ≤ I _ref ), it is determined that there is no foreign material. .

As another example, the control unit 230 _{checks whether the current measurement values I 1} , I ₂ , ...I _m belong to the reference ranges I _low to I _{high , respectively.} And if at least one of the current measurement values I ₁ , I ₂ ,...I _m falls within the reference range (ie, I _low ≤ I ₁ or I ₂ or ...I _m ≤ I _high ), there is no foreign substance. judge On the other hand, if the current measurements I ₁ , I ₂ ,...I _m do not all fall within the reference range (ie I ₁ and I ₂ and ...I _m > I _high or I ₁ and I ₂ and ... I _m < I _low ) It is judged that a foreign object is detected.

As another example, the control unit 340 compares the _{current measured value I SELECTED} with the reference current I _{ref .} And when the current measured value I _SELECTED exceeds the reference current I _ref (ie, I _SELECTED > I _ref ), it is determined that a foreign substance is detected. On the other hand, if the current measurement value I _SELECTED is less than or equal to the reference current I _{ref (ie, I SELECTED} ≤ I _ref ), it is determined that there is no foreign material.

As another example, the control unit 340 checks whether _{the current measurement value I SELECTED} falls within the reference range I _low to I _{high .} And if the current measurement value I _SELECTED falls within the reference range (ie, I _low ≤ I _SELECTED ≤ I _high ), it is determined that there is no foreign substance. On the other hand, if the current measured value I _SELECTED does not fall within the reference range (ie, I _SELECTED > I _high or I _SELECTED < I _low ), it is determined that a foreign substance has been detected.

As another example, the control unit 340 compares the _{current measured value I TOTAL} to the reference current I _{ref .} And if the current measured value I _TOTAL exceeds the reference current I _ref (ie, I _TOTAL > I _ref ), it is determined that a foreign object is detected. On the other hand, if the current measured value I _TOTAL is less than or equal to the reference current I _{ref (ie, I TOTAL} ≤ I _ref ), it is determined that there is no foreign material.

As another example, the control unit 340 checks whether _{the current measurement value I TOTAL} falls within the reference range I _low to I _{high .} And if the current measured value I _TOTAL falls within the reference range (ie, I _low ≤ I _TOTAL ≤ I _high ), it is determined that there is no foreign substance. On the other hand, if the current measured value I _TOTAL does not fall within the reference range (ie, I _TOTAL > I _high or I _TOTAL < I _low ), it is determined that a foreign object is detected.

The control unit 340 may attempt to detect the foreign material at a time t predetermined by the system or standard.

As an example, the time t at which the control unit 340 attempts to detect foreign substances may be after every power control time. For example, after the wireless power transmitter 300 receives a power up request message or a power down request message from the wireless power receiver and raises or lowers the AC signal, the current flowing through the primary core block 310 is measured. You can try to detect foreign substances using the value.

As another example, the time t at which the control unit 340 attempts to detect the foreign material may be a predetermined constant detection period. For example, the detection period should be at least shorter than the time it takes for the foreign material to generate heat above a certain temperature. This is because, if the heat of foreign substances becomes severe, it may cause serious safety problems such as fire and burns of the body. Therefore, it is preferable that the detection period is set to a value whose stability has been verified by an experiment, thereby preventing various risks that may be caused during charging, such as heat generated by foreign substances during wireless charging.

When a foreign material is detected, the control unit 340 blocks the wireless power transmission by controlling the electric driving unit 330 so as not to apply an AC signal to the primary core block 310 .

The wireless power transmitter 110 of FIG. 1 may be the wireless power transmitter 200 of FIG. 2 or the wireless power transmitter 300 of FIG. 3 .

According to the present invention, since it is not necessary for the wireless power receiver to transmit specific information to the wireless power transmitter 200 based on a promised information transmission standard for foreign matter detection, signaling overhead can be reduced.

It is a very important technical issue to detect a foreign material with a minimum delay before it heats up. This is because, if the foreign material is easily heated due to the nature of the foreign material, a long delay until the foreign material is detected may cause a serious problem. However, according to the present invention, since the wireless power transmitter 200 can detect foreign substances by itself, there is a delay for detecting foreign substances, for example, the time when the wireless power receiver generates specific information, the specific information There is an effect that the time transmitted to the wireless power transmitter 200 and the time for the wireless power transmitter 200 to decode and interpret the specific information become unnecessary.

Furthermore, even when the wireless power receiver is a model of a lower version that cannot transmit the specific information, the wireless power transmission system according to the present invention can provide compatibility with the model.

4 is an operation flowchart of a wireless power transmission system according to an example of the present invention.

Referring to FIG. 4 , the wireless power transmitter searches for a wireless power receiver ( S400 ). At this time, the wireless power transmitter is placed in a charging standby state until the wireless power receiver is found.

If the detected object is a wireless power receiver, the wireless power transmitter enters a charging mode and transmits wireless power to the wireless power receiver (S405). In the charging mode, the wireless power transmitter applies power to the primary coil to generate an induced magnetic field or resonance.

The wireless power transmitter measures the current flowing in the primary coil, and the wireless power transmitter acquires a current measurement value from the current flowing in the primary coil (S410). The current measured by the wireless power transmitter may be an alternating current. The current measurement value may be converted into a DC value suitable for recognition by a control unit in the wireless power transmitter. That is, the wireless power transmitter measures a relatively high alternating current flowing through the primary coil, and maps the measured high current to a current measurement value, which is a value suitable for the control unit to interpret, as shown in Table 1.

The wireless power transmitter performs foreign material detection by using any one or a combination of two or more parameters such as _{reference current I ref} , reference range (I _low ~ I _{high ), reference AC signal, and foreign material detection time t (S415)} ). In addition, parameters such as the reference current I _ref , the reference range (I _low to I _high ), the reference AC signal, and the foreign material detection time t may be stored in advance in the wireless power transmitter as initial setting values.

The wireless power transmitter continuously transmits power to the wireless power receiver when no foreign matter is detected (S420). In addition, the wireless power transmitter acquires the current measurement value of the primary coil again at a time t predetermined by the system or standard (S410), and based on this, may attempt to detect foreign substances (S415).

On the other hand, the wireless power transmitter cuts off the wireless power transmitted to the wireless power receiver when a foreign substance is detected (S425).

5 is an operation flowchart of a wireless power transmitter according to an example of the present invention. This is an operation according to the wireless power transmitter of FIG. 2 .

Referring to FIG. 5 , the wireless power transmitter is placed in a charging standby state until the wireless power receiver is found ( S500 ).

At this time, the wireless power transmitter continuously searches for an object to transmit power (S505). If the object is not detected, the wireless power transmitter returns to the charging standby again (S500).

If an object is detected, the wireless power transmitter determines whether the detected object is a wireless power receiver capable of normally receiving wireless power (S510). If the detected object is not the wireless power receiver, the wireless power transmitter cuts off power (S515).

If the detected object is a wireless power receiver, the wireless power transmitter enters a charging mode (S520). In the charging mode, the wireless power transmitter applies power to the primary coil to generate an induced magnetic field or resonance.

The wireless power transmitter measures the current flowing through the primary coil (S525). In particular, the current measured by the wireless power transmitter may be an alternating current.

The wireless power transmitter obtains a current measured value I _measured from the current flowing in the primary coil (S530). The measured current I _measured may be converted into a DC value suitable for recognition by a control unit in the wireless power transmitter. That is, the wireless power transmitter measures a relatively high AC current flowing through the primary coil, _{and maps the measured} high current to a current measurement value I measured, which is a value suitable for the control unit to interpret, as shown in Table 1.

The wireless power transmitter performs foreign material detection by using any one or a combination of two or more parameters such as _{reference current I ref} , reference range (I _low ~ I _{high ), reference AC signal, and foreign material detection time t (S535)} ). In addition, parameters such as the reference current I _ref , the reference range (I _low to I _high ), the reference AC signal, and the foreign material detection time t may be stored in advance in the wireless power transmitter as initial setting values.

As an example, the wireless power transmitter compares the _measured current I measured with the reference current I _{ref .} In addition, when the _measured current I measured exceeds the reference current I _ref (ie, I _measured > I _ref ), it is determined that a foreign material is detected. On the other hand, if the measured current I _measured is equal to or less than the reference current I _{ref (ie, I measured} ≤ I _ref ), it is determined that there is no foreign material.

As another example, the wireless power transmitter checks whether the current measured value I _measured falls within a reference range (I _low to I _high ). And if the current measured value I _measured falls within the reference range (ie, I _low ≤ I _measured ≤ I _high ), it is determined that there is no foreign material. On the other hand, if the current measured value I _measured does not fall within the reference range (ie, I _measured > I _high or I _measured < I _low ), it is determined that the foreign material is detected.

The wireless power transmitter cuts off the wireless power transmitted to the wireless power receiver when a foreign substance is detected (S515).

On the other hand, the wireless power transmitter continuously transmits power to the wireless power receiver when no foreign matter is detected (S540). And the wireless power transmitter measures the current of the primary coil again at a time t predetermined by the system or standard (S525), and obtains a current measurement value (S530), and based on this, it can try to detect foreign substances ( S535).

As an example, the time t at which the wireless power transmitter attempts to detect foreign substances may be after every power control time. For example, after the wireless power transmitter receives a power up request message or a power down request message from the wireless power receiver and raises or lowers the AC signal, it detects foreign substances using the current measurement value flowing through the primary coil. you can try

As another example, the time t at which the wireless power transmitter attempts to detect foreign substances may be a predetermined constant detection period. For example, the detection period should be at least shorter than the time it takes for the foreign material to generate heat above a certain temperature. This is because, if the heat of foreign substances becomes severe, it may cause serious safety problems such as fire and burns of the body. Therefore, it is preferable that the detection period is set to a value whose stability has been verified by an experiment, thereby preventing various risks that may be caused during charging, such as heat generated by foreign substances during wireless charging.

6 is an operation flowchart of a wireless power transmitter according to another example of the present invention. This is an operation according to the wireless power transmitter of FIG. 3 .

Referring to FIG. 6 , the wireless power transmitter is placed in a charging standby state until the wireless power receiver is found ( S600 ).

At this time, the wireless power transmitter continuously searches for an object to transmit power using m primary coils (S605). If an object is not detected in at least one of the m primary coils, the wireless power transmitter returns to the charging standby again (S600).

If an object is detected in at least one primary coil, the wireless power transmitter determines whether the detected object is a wireless power receiver capable of normally receiving wireless power (S610). If the detected object is not the wireless power receiver, the wireless power transmitter cuts off power (S615).

If the detected object is a wireless power receiver, the wireless power transmitter enters a charging mode (S620). In the charging mode, the wireless power transmitter applies power to the primary coil to generate an induced magnetic field or resonance.

The wireless power transmitter measures the currents flowing through the m primary coils individually or by summing them up (S625). In particular, the current measured by the wireless power transmitter may be an alternating current.

As an example, the wireless power transmitter selects only the primary coil through which the current flows from the m primary coils, individually measures the current flowing through each of the selected primary coils, and a plurality of individual current measurement values I ₁ , I ₂ , ...I _m are acquired (S630). Current measurement values I ₁ , I ₂ , ...I _m may be converted into DC values suitable for recognition by the wireless power transmitter. That is, the wireless power transmitter measures a relatively high alternating current flowing through the primary coil, _{and maps the measured high current to current measurement values I 1} , I ₂ , ...I _m as shown in Table 1.

As another example, the wireless power transmitter selects only the primary coil through which the current flows from the m primary coils, and measures the current flowing through the selected primary coil to obtain a current measurement value.

As another example, the wireless power transmitter measures the total current flowing through all m primary coils, and obtains _{one total current measurement value I TOTAL .}

The wireless power transmitter may use _{any one or a combination of two or more of parameters such as a reference current I ref} , a reference range (I _low ~ I _high ), a reference AC signal, and a foreign material detection time t for foreign matter detection. And parameters such as the reference current I _ref , the reference range (I _low ~ I _high ), the reference AC signal, and the foreign substance detection time t may be stored in the wireless power transmitter as initial setting values.

As an example, the wireless power transmitter compares the current measured values I ₁ , I ₂ , ...I _m and the reference current I _ref . and if at least one of the current measurements I ₁ , I ₂ ,...I _{m exceeds the reference current I ref} (ie I ₁ or I ₂ or ...I _m > I _ref ), foreign matter judged to have been detected. On the other hand, if the current measurement values I ₁ , I ₂ , ...I _m are all below the reference current I _ref (ie, I ₁ and I ₂ and ...I _m ≤ I _ref ), it is determined that there is no foreign material. .

As another example, the wireless power transmitter checks whether the current measurement values I ₁ , I ₂ , ...I _m belong to a reference range (I _low to I _{high ), respectively.} And if at least one of the current measurement values I ₁ , I ₂ ,...I _m falls within the reference range (ie, I _low ≤ I ₁ or I ₂ or ...I _m ≤ I _high ), there is no foreign substance. judge On the other hand, if the current measurements I ₁ , I ₂ ,...I _m do not all fall within the reference range (ie I ₁ and I ₂ and ...I _m > I _high or I ₁ and I ₂ and ... I _m < I _low ) It is judged that a foreign object is detected.

As another example, the wireless power transmitter compares the current measurement value I _SELECTED with the reference current I _ref . And when the current measured value I _SELECTED exceeds the reference current I _ref (ie, I _SELECTED > I _ref ), it is determined that a foreign substance is detected. On the other hand, if the current measurement value I _SELECTED is less than or equal to the reference current I _{ref (ie, I SELECTED} ≤ I _ref ), it is determined that there is no foreign material.

As another example, the wireless power transmitter checks whether the current measurement value I _SELECTED is within the reference range (I _low ~I _high ). And if the current measurement value I _SELECTED falls within the reference range (ie, I _low ≤ I _SELECTED ≤ I _high ), it is determined that there is no foreign substance. On the other hand, if the current measured value I _SELECTED does not fall within the reference range (ie, I _SELECTED > I _high or I _SELECTED < I _low ), it is determined that a foreign substance has been detected.

As another example, the wireless power transmitter compares the current measurement value I _TOTAL with the reference current I _ref . And if the current measured value I _TOTAL exceeds the reference current I _ref (ie, I _TOTAL > I _ref ), it is determined that a foreign object is detected. On the other hand, if the current measured value I _TOTAL is less than or equal to the reference current I _{ref (ie, I TOTAL} ≤ I _ref ), it is determined that there is no foreign material.

As another example, the wireless power transmitter checks whether the current measurement value I _TOTAL falls within a reference range (I _low to I _high ). And if the current measured value I _TOTAL falls within the reference range (ie, I _low ≤ I _TOTAL ≤ I _high ), it is determined that there is no foreign substance. On the other hand, if the current measured value I _TOTAL does not fall within the reference range (ie, I _TOTAL > I _high or I _TOTAL < I _low ), it is determined that a foreign object is detected.

When a foreign material is detected, the wireless power transmitter controls not to apply an AC signal to the m primary core blocks to block the wireless power transmission (S615). On the other hand, the wireless power transmitter continuously transmits power to the wireless power receiver when no foreign matter is detected (S640). And the wireless power transmitter measures the current of the m primary coils again at a time t predetermined by the system or standard (S625), and acquires the current measurement value (S630), and based on this, it is possible to try to detect foreign substances. There is (S635). In this case, the wireless power transmitter may attempt to detect foreign substances at a time t predetermined by the system or standard.

As an example, the time t at which the wireless power transmitter attempts to detect foreign substances may be after every power control time. For example, after the wireless power transmitter receives a power up request message or a power down request message from the wireless power receiver and raises or lowers the AC signal, foreign matter is detected using a current measurement value flowing through the primary core block can try

As another example, the time t at which the wireless power transmitter attempts to detect foreign substances may be a predetermined constant detection period (detection period). For example, the detection period should be at least shorter than the time it takes for the foreign material to generate heat above a certain temperature. This is because, if the heat of foreign substances becomes severe, it may cause serious safety problems such as fire and body burns. Therefore, it is preferable that the detection cycle is set to a value whose stability is verified by an experiment, thereby preventing various risks that may be caused during charging, such as heat generated by foreign substances during wireless charging.

All of the above-described functions may be performed by a processor such as a microprocessor, a controller, a microcontroller, an application specific integrated circuit (ASIC), etc. according to software or program code coded to perform the functions. The design, development and implementation of the above code will be apparent to those skilled in the art based on the description of the present invention.

Although the present invention has been described with reference to embodiments, those of ordinary skill in the art can variously modify and change the present invention within the scope without departing from the technical spirit and scope of the present invention. You will understand. Therefore, the present invention is not limited to the above-described embodiments, and it will be said that all embodiments within the scope of the following claims are included.

Claims (12)

As a wireless power transmitter for detecting foreign substances,
a primary core block configured to transmit wireless power to a wireless power receiver by magnetic induction or magnetic resonance;
an electric driving unit configured to apply an alternating current (AC) signal necessary for the primary core block to transmit the wireless power;
a control unit configured to generate a control signal for controlling the AC signal; and
a current measuring unit configured to obtain a current measured value from the current flowing into the primary core block
includes,
The control unit detects a foreign substance based on a result of comparing the current measurement value with a reference value in response to the power control of the wireless power being performed,
The reference value is a current measurement value when the transmission efficiency of wireless power falls within a normal range in an environment free from foreign substances, the wireless power transmitter. The method of claim 1,
The reference value is a reference current,
If the current measurement value exceeds the reference current, the control unit determines that a foreign substance is detected,
If the current measurement value is equal to or less than the reference current, the control unit determines that no foreign matter is detected, the wireless power transmitter. The method of claim 1,
The reference value is a reference range,
If the current measurement value falls within the reference range, the control unit determines that no foreign matter is detected,
If the current measurement value does not fall within the reference range, the control unit determines that a foreign material is detected, the wireless power transmitter. The method of claim 1,
The primary core block includes a plurality of primary coils,
The wireless power transmitter further comprises a switching unit for selectively connecting all or at least one of the plurality of primary coils with the electric driving unit by using a switching method, the wireless power transmitter. 5. The method of claim 4,
The current measurement unit selects only a primary coil through which a current flows from among the plurality of primary coils, and measures a current flowing through the selected primary coil to obtain a plurality of individual current measurement values,
The control unit determines that a foreign material is detected when at least one of the plurality of individual current measurement values exceeds the reference value, and the control unit detects a foreign material when all of the plurality of individual current measurement values are less than or equal to the reference value It is determined that it is not, a wireless power transmitter. 5. The method of claim 4,
The current measurement unit measures the total amount of current flowing through the plurality of primary coils to obtain one total current measurement,
The control unit determines that foreign matter is detected when the one total current measurement value exceeds the reference value, and determines that foreign matter is not detected when the one total current measurement value is less than or equal to the reference value power transmitter. The method of claim 1,
The control unit is also to perform the detection of the foreign matter at a time t predetermined by the system or standard, the wireless power transmitter. 8. The method of claim 7,
The predetermined time t is a predetermined period shorter than the time period it takes for the foreign material to generate heat above the predetermined temperature, the wireless power transmitter. A method of detecting foreign substances using a wireless power transmitter having a primary core block, the method comprising:
applying an alternating current (AC) signal necessary for wireless power transmission to the primary core block;
transmitting the wireless power to a wireless power receiver by magnetic induction or magnetic resonance;
obtaining a current measurement value from the current flowing into the primary core block; and
detecting foreign substances based on a result of comparing the current measurement value with a reference value in response to the power control of the wireless power being performed
including,
Wherein the reference value is a current measurement value when the transmission efficiency of wireless power falls within a normal range in an environment free of foreign substances. 10. The method of claim 9,
The reference value is a reference current,
If the current measurement value exceeds the reference current, it is determined that a foreign substance is detected,
If the current measured value is less than or equal to the reference current, it is determined that the foreign material is not detected. 10. The method of claim 9,
The reference value is a reference range,
If the current measurement value falls within the reference range, it is determined that foreign matter is not detected,
If the current measurement value does not fall within the reference range, it is determined that the foreign material is detected. 10. The method of claim 9,
The primary core block includes a plurality of primary coils,
the current measurements correspond to a plurality of individual measurements of current flowing through the plurality of primary coils;
When at least one of the plurality of individual measured values exceeds the reference value, it is determined that a foreign substance has been detected,
When all of the plurality of individual measured values are less than or equal to the reference value, it is determined that no foreign matter is detected.

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