KR20230077346A - Efficient wireless power charging apparatus and method thereof - Google Patents

Abstract

The present invention relates to a wireless power charging device for efficiently managing charging status, and a method therefor. The present invention comprises: at least one transmitting end that transmits power using power provided from a power supply unit and each includes a transmitting resonator unit including one capacitor and one inductor; at least one receiving end that receives power transmitted from the at least one transmitting end and each including a receiving resonator including one capacitor and one inductor, and a load performing charging using the received power; and a control unit that proceeds with wireless charging by determining the output current of the at least one transmitting end using the mutual inductance between the at least one transmitting end and the at least one receiving end, and adjusts the output current of the at least one transmitting end by using the importance of the at least one receiving end with respect to the at least one transmitting end depending on whether the current receiving power of the at least one receiving end reaches the target receiving power, and the received power control direction for adjusting the received power of the at least one receiving end.

Description

Efficient wireless power charging device and method thereof {EFFICIENT WIRELESS POWER CHARGING APPARATUS AND METHOD THEREOF}

The present invention relates to an efficient wireless power charging device and method thereof, and relates to a wireless power charging device and method capable of providing the maximum amount of power required by a receiving end by detecting a change in a wireless charging environment.

Wireless power transmission refers to supplying power to electronic devices wirelessly instead of wired, and since devices requiring power can be charged wirelessly without connecting to a power outlet, related research is being actively conducted. Magnetic induction method, magnetic resonance method, microwave method, etc. are being studied for wireless power transmission technology.

A wireless power transmitter includes a transmitter that wirelessly transmits power and a receiver that receives the transmitted power. The transmitter transmits power to the receiver by generating a magnetic field and radiating it to the receiver. For power transmission, a transmitter and a receiver use coils, and when they have the same resonant frequency, maximum power transfer can occur in a wireless power transmitter.

Meanwhile, wireless charging may be performed by configuring one or more transmitter and receiver, and one transmitter may transmit power to a plurality of receivers or one receiver may receive power from a plurality of transmitters. In this situation, when it is necessary to adjust the power received by a receiving end, the transmission power control of the transmitting end supplying power to the receiving end is required. Since the received power due to this is different for each receiving end, and each transmitting end transmits power to other receiving ends in addition to the corresponding receiving end, it is difficult to determine which transmitting end needs to control the transmit power.

In addition, the wireless charging environment may change during the charging process, such as intrusion of foreign substances, increase or decrease in the number of receivers, and changes in the status of receivers, and these changes in the charging environment may not be reflected in the progress of wireless charging. Otherwise, it is difficult to perform wireless charging with maximum efficiency, and a method for efficiently performing wireless charging by detecting changes in the environment of the receiving end is required.

The present invention relates to a wireless power charging device and method capable of maximally providing power required by a receiving end.

In addition, the present invention relates to a wireless power charging device and method capable of efficiently performing wireless charging by detecting a change in the charging environment.

The present invention transmits power using power supplied from the power supply unit and includes at least one transmitting end each including a transmission resonator unit including one capacitor and one inductor; at least one receiving end each including a reception resonator that receives the power transmitted from the at least one transmitting end and includes a capacitor and an inductor and a load that performs charging using the received power; Wireless charging is performed by determining the output current of the at least one transmitting end using mutual inductance between the at least one transmitting end and the at least one receiving end, and whether the current received power of the at least one receiving end reaches the target received power. A control unit for adjusting the output current of the at least one transmitting end using the importance of the at least one receiving end to the at least one transmitting end and a received power control direction for adjusting the received power of the at least one receiving end according to It relates to a wireless power charging device that does.

Here, the control unit may determine the importance by considering the degree of influence of the power transmitted from the transmitting end on each receiving end between one transmitting end and at least one receiving end.

In addition, the control unit determines the level of importance according to the magnitude of mutual inductance between any one transmitting end and at least one receiving end, and has a non-zero mutual inductance between any one transmitting end and at least one receiving end. The level of importance may be determined by setting the total number of receiving ends to be the highest value of the importance and subtracting a predetermined value from the highest value for the next rank.

In addition, the control unit maintains the output current of the at least one transmitting end at the current state when the current received power of the at least one receiving end reaches the target receiving power, and the current receiving power of the at least one receiving end reaches the target reception power. When all of the power falls below or exceeds the power, the output current of the at least one transmitter may be adjusted.

In addition, if the current received power of a portion of the at least one receiving end falls short of or exceeds the target received power, the control unit determines whether the current received power of at least one receiving end having the highest importance for the at least one transmitting end reaches the target receiving power. The output current of the transmitter may be adjusted according to whether or not the

In addition, the control unit controls the output current of the at least one transmitting end using [Equation 5].

[Equation 5]

At this time, S _t is any one of increasing, decreasing, and maintaining in the current control direction of the t-th transmitter

W _tk is the importance of the k-th receiver to the t-th transmitter

d _k is any one of (+1), 0, and (-1) in the received power control direction for the k-th receiving terminal.

On the other hand, the present invention transmits power by using the power supplied from the power supply unit, and at least one transmitting end each including a transmission resonator including one capacitor and one inductor; at least one receiving end each including a reception resonator that receives the power transmitted from the at least one transmitting end and includes a capacitor and an inductor and a load that performs charging using the received power; Using the change in impedance viewed from the at least one transmitting end to the at least one receiving end, whether or not the wireless charging environment changes in a predetermined time unit is determined, and the output current of the at least one transmitting end is determined, and the determined output current and Wireless power charging including a control unit that compares the output current of the at least one transmitting end received from the sensing unit to determine whether the change in the wireless charging environment is any one of a change in the at least one receiving end itself and an intrusion of a foreign substance into a charging area It's about the device.

Here, the control unit determines the impedance viewed from the at least one transmitting end to the at least one receiving end in units of a predetermined time, and when the change in the determined impedance exceeds a predetermined range, it is possible to check whether the wireless charging environment changes.

In addition, the control unit may determine the output current I _mt of the at least one transmitting terminal using [Equation 6].

[Equation 6]

At this time, I _MONt is the output current of the current controller of the t-th transmitter

In addition, the control unit may check the change of the at least one receiving terminal itself when the determined output current and the received output current of the at least one transmitting terminal are the same or the difference is within a predetermined range.

In addition, the control unit may determine that the foreign matter has entered the charging area when the determined output current is different from the received output current of the at least one transmitter or the difference exceeds a predetermined range.

On the other hand, the power is transmitted using the power supplied from the power supply unit, and at least one transmitting end each including a transmission resonator including one capacitor and one inductor and the power transmitted from the at least one transmitting end are received, and one capacitor and determining a mutual inductance between a reception resonator including one inductor and at least one receiving end each including a load that performs charging using the received power; determining an output current of the at least one transmitting end using mutual inductance between the at least one transmitting end and the at least one receiving end, and performing wireless charging; Receive power control direction for adjusting the importance of the at least one receiving end to the at least one transmitting end and the received power of the at least one receiving end according to whether the current received power of the at least one receiving end reaches the target receiving power. It relates to a wireless power charging method comprising the step of adjusting the output current of the at least one transmitting terminal by using.

Here, the process of adjusting the output current of the transmitting end includes: checking the total number of receiving ends having mutual inductance other than '0' between any one transmitting end and at least one receiving end; The step of setting the total number as the highest value of the importance and determining the level of importance by subtracting a predetermined value from the highest value as the next priority.

In addition, the process of adjusting the output current of the transmitting end may include maintaining the output current of the at least one transmitting end at the current state when the current reception power of the at least one receiving end reaches the target reception power; The method may include adjusting an output current of the at least one transmitting node when the current reception power of the at least one receiving node falls below or exceeds the target reception power.

In addition, the process of adjusting the output current of the transmitting end may include the current reception of at least one receiving end having the highest importance for the at least one receiving end when the current reception power of a portion of the at least one receiving end falls short of or exceeds the target receiving power. The method may include adjusting an output current of the transmitter depending on whether or not the power reaches a target reception power.

On the other hand, the present invention transmits power using the power provided from the power supply unit, and the reception resonator unit includes one capacitor and one inductor in at least one transmitting terminal each including a transmission resonator unit including one capacitor and one inductor. And a process of checking whether or not a change in the wireless charging environment in units of a predetermined time by using a change in impedance looking at at least one receiving terminal each including a load that performs charging using the received power; determining an output current of the at least one transmitting terminal; A process of comparing the determined output current with the output current of the at least one transmitting terminal received from the sensing unit to determine whether the change in the wireless charging environment is any one of a change in the at least one receiving terminal itself and an intrusion of a foreign substance into the charging area can include

In addition, the process of determining whether the wireless charging environment changes may include determining an impedance viewed from the at least one transmitting end toward the at least one receiving end in units of a predetermined time; When the determined change in impedance exceeds a predetermined range, a process of checking whether the wireless charging environment is changed may be included.

In addition, the process of determining which one is the same, if the determined output current and the output current of the at least one transmitting terminal received from the sensing unit are the same or the difference is within a predetermined range, the change of the at least one receiving terminal itself may include a process of verifying.

In addition, the process of confirming any one of the above includes a process of confirming that the foreign matter invades the charging area when the determined output current and the received output current of the at least one transmitting terminal are different or the difference exceeds a predetermined range. can include

In the present invention, even when a receiving end receives power from a plurality of transmitting ends or when a transmitting end transmits power to a plurality of receiving ends, when the received power of the receiving end is less than or exceeds the target reception power, the transmit power of the transmitting end is controlled to control the receiving end. Received power can be adjusted. In addition, in the relationship between the transmitting end and the receiving end, the power supply can be efficiently controlled since the transmitting end and the receiving end having the highest influence are identified and power is supplied in consideration of the importance of the receiving end to the transmitting end. In addition, since it is possible to quickly and accurately determine whether or not the wireless charging environment has changed, wireless charging can be performed with maximum efficiency, and unnecessary power consumption can be prevented by checking whether or not foreign substances have entered.

1 is a diagram showing the configuration of a wireless power charging device according to an embodiment of the present invention.
2 is a diagram for explaining a transmitting end and a receiving end of a wireless power charging device according to an embodiment of the present invention.
3 is a diagram for explaining a connection relationship between a plurality of transmitting ends and a plurality of receiving ends of a wireless power charging device according to an embodiment of the present invention.
4 is a diagram for explaining a method of determining whether charging is in progress in a wireless power charging device according to an embodiment of the present invention.
5 is a diagram for explaining a method of determining mutual inductance in a wireless power charging device according to an embodiment of the present invention.
6 is a diagram for explaining a method of controlling an output current of a transmitter in a wireless power charging device according to an embodiment of the present invention.
7 is a diagram for explaining a method of determining a wireless charging environment change in a wireless power charging device according to an embodiment of the present invention.
8(a) and 8(b) are flowcharts illustrating the operation of a wireless power charging device according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with drawings. In describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted.

1 is a diagram showing the configuration of a wireless power charging device 10 according to an embodiment of the present invention.

Referring to FIG. 1, the wireless power charging device 10 of the present invention includes a power supply unit 100, an amplification unit 110, a communication unit 120, a sensing unit 130, a resonator unit 140, a rectifier unit 150, It includes a conversion unit 160 and a control unit 170.

The power supply unit 100 supplies power to the wireless power charging device 10 of the present invention, and supplies AC (Alternating Current) or DC (Direct Current) power, for example.

The amplification unit 110 amplifies power supplied from the power supply unit 100 and may be configured as a power amplifier.

The communication unit 120 is for communication inside the external device or the wireless power charging device 10 of the present invention, and is a short-range communication means such as Bluetooth or Wi-fi or LTE or 5G (5G) It may include a communication means capable of communicating by accessing a mobile communication network according to various mobile communication standards, such as the like.

The sensing unit 130 detects voltage or current at a predetermined position of the wireless power charging device 10 of the present invention, and may include various sensors.

The resonator 140 transmits power by resonance between coils, and includes at least one transmit resonator and at least one receive resonator including a capacitor and an inductor, respectively.

The rectifier 150 is for changing AC current into DC current, and may be configured as a rectifier. The rectifying unit 150 rectifies the current generated in the reception resonance unit.

The conversion unit 160 is to keep the voltage provided for charging constant in order to meet the voltage condition for charging, and can be configured as a DC-DC converter, and the voltage according to the conversion ratio. can be adjusted.

The control unit 140 controls the wireless power charging device 10 as a whole of the present invention, such as determining the mutual inductance of the resonator 140 and the current or voltage of the transmitter so that wireless power charging can proceed with maximum efficiency.

2 is a diagram for explaining the transmitting end 200 and the receiving end 210 of the wireless power charging device 10 according to an embodiment of the present invention.

Referring to FIG. 2 , the wireless power charging device 10 of the present invention includes a transmitting end 200 for transmitting power and a receiving end 210 for receiving power to enable charging.

The transmitter 200 includes a control unit 170, a power supply unit 100, an amplifier 110, and a transmission resonator 220, and the receiver 210 includes a reception resonator 230, a rectifier 150, and a conversion unit. (160) and load R _L . 2 shows the control unit 170 as the transmitting end 200, the control unit 170 is configured to control the wireless power charging device 10 of the present invention as a whole, including not only the transmitting end 200 but also the receiving end 210. can

In addition, although not shown in FIG. 2 , the sensing unit 130 may sense voltage or current at predetermined positions of the transmitting end 200 and the receiving end 210 and communicate with each other through the communication unit 120 . For example, current or voltage sensed through Bluetooth communication may be transmitted/received or control information may be transmitted/received.

A description of each character shown in FIG. 2 is as follows.

V _P : Output voltage of the amplifier 110

I _P : output current of the transmitting end 200

C _P : capacitance of the transmission resonator 220

L _P : Self-inductance of the transmitting resonator 220

M : mutual inductance

I _S : receiving current of the receiving terminal 210

C _S : capacitance of the receiving resonator 230

L _S : self-inductance of the receiving resonator 230

V _R : output voltage of the rectifier 150

V _Out : Charging voltage of the load of the receiving end 210

R _L : Load impedance of the receiving end 210

3 is a diagram for explaining a connection relationship between a plurality of transmitting ends 200a, 200b, and 200c and a plurality of receiving ends 210a, 210b, and 210c of the wireless power charging device 10 according to an embodiment of the present invention.

Hereinafter, a case in which power is transmitted from a plurality of transmitters to a plurality of receivers will be described, and the same can be applied to the case of transmitting power from one transmitter or receiving power from one receiver.

Referring to FIG. 3, the wireless power charging device 10 according to an embodiment of the present invention includes first to t transmitting terminals 200a, 200b, and 200c and first to q receiving terminals 210a, 210b, and 210c. It is configured so that power charging can proceed in the first through q-th receiving nodes 210a, 210b, and 210c using the power transmitted by the first to t-th transmitting nodes 200a, 200b, and 200c. At this time, each of the first to t-th transmitting ends 200a, 200b, and 200c may include the same or similar configuration as the transmitting terminal 200 described in FIG. 2, and the first to q-th receiving ends 210a, 210b, and 210c may include the same or similar configuration as the receiving end 210 of FIG. 2 .

In addition, each of the first to t-th transmitting ends 200a, 200b, and 200c and the first to q-th receiving ends 210a, 210b, and 210c have the same size of each component such as capacitance, inductance, and impedance as other transmitting or receiving ends. It can be configured or configured differently from each other. In addition, the power supply unit 100 and the control unit 170 are configured as one component and applied to the entire wireless power charging device 10 of the present invention, and the amplifier 110, the transmission resonance unit 220, the sensing unit ( 130) is composed of a plurality of components included in each of the first to t-th transmission terminals 200a, 200b, and 200c, and includes a reception resonance unit 230, a rectification unit 150, a conversion unit 160, and a sensing unit 130 may be composed of a plurality of components included in each of the first to qth receiving terminals 210a, 210b, and 210c. In addition, the communication unit 120 is composed of one component in the first to t-th transmitting ends 200a, 200b, and 200c and applied to the entire transmitting end, and included in each of the first to q-th receiving ends 210a, 210b, and 210c. It can consist of multiple components. In addition, the control unit 170 controls the power supplied to the first through t-th transmitting terminals 200a, 200b, and 200c by using the power supplied from the power supply unit 100.

A mutual inductance equal to M _tq is generated between the first to t-th transmitting ends 200a, 200b, and 200c and the first to q-th receiving ends 210a, 210b, and 210c between each transmitting end and each receiving end. In addition, when foreign matter invades the charging area, since the foreign matter also has an inductance and a load of the foreign matter, between the first to t transmitting terminals 200a, 200b, and 200c and the foreign material, the first to q receiving terminals 210a, 210b, and 210c Mutual inductance also occurs between the

4 is a diagram for explaining a method of determining whether charging is in progress in the wireless power charging device 10 according to an embodiment of the present invention.

In order to minimize power consumption, the wireless power charging device 10 of the present invention operates in a power saving mode before the receiving end enters the charging area of the first through t-th transmitting ends 200a, 200b, and 200c. In the power saving mode, when an object enters the charging area of the transmitting end, the controller 170 checks whether a receiving end capable of wireless charging is within the charging area of the transmitting end, and proceeds with wireless charging. At this time, since foreign substances may enter the charging area, after checking whether there is an arbitrary object in the charging area, it is determined whether the object is a chargeable receiving end or a foreign substance.

Hereinafter, the t-th transmitter 200c will be described, and the same or similar can be applied to other transmitters.

4 is a diagram showing an equivalent circuit when an arbitrary object enters the charging area of the t-th transmitter 200c. As shown in FIG. 4, the equivalent circuit includes two MOS-FETs, a resistor, a capacitor, and an inductor, and descriptions of each character are as follows.

CCS _t (400): Current control unit of the t-th transmitter 200c

w: operating angular frequency of the t-th transmitter 200c

I _mt : Output current of the t-th transmitter 200c

V _Pt : Input voltage of the t th transmitter 200c

R _Pt : internal resistance of the t-th transmitter 200c

C _Pt : capacitance of the t-th transmitter 200c

L _Pt : inductance of the t th transmitter 200c

Zu.o 410: Impedance of a predetermined object viewed from the t th transmitter 200c

Z _int : Impedance viewed from the t th transmitter (200c) to all receivers

CCS _t (400) controls the current supplied to the t-th transmitter 200c, and for example, according to the control signal received from the MCU (Micro Controller Unit), the t-th in a predetermined current unit such as 0.01 (A) The amount of current supplied to the transmitter 200c is controlled.

When the sensing unit 130 senses the input voltage or output current of the t-th transmitting end 200c and transmits the detected input voltage or output current to the control unit 170, the control unit calculates the impedance (Z _int ) using [Equation 1] Decide.

[Equation 1]

When a predetermined object is located within the charging area of the t-th transmitter 200c, an impedance Zu.o is generated due to the object, which causes the impedance Z _int to increase. Through this, when the size of the impedance (Z _int ) exceeds a predetermined threshold value, it is determined that an arbitrary object is located within the charging area. Thereafter, it is determined whether an object is a receiving end capable of wireless power charging or a foreign substance that is difficult to charge, and wireless charging is performed in the case of the receiving end, and charging is not performed in the case of a foreign object.

For example, the control unit 170 determines that the resonant angular frequency (w _o ) of the resonator unit of the t-th transmitter (200c) before an object is located within the charging area is the same as the resonant angular frequency (w _o ') after being located within the charging area. It is determined whether it is a foreign substance or not, or the output current (I _mt ) detected by the detector 130 is equal to or within a predetermined range as the output current (I _mt ) calculated using [Equation 6] discussed below. It is possible to determine whether there is a foreign substance by using whether or not there is a foreign substance.

When an object is identified as a receiving end, the number of receiving ends is checked using a short-range communication means such as Bluetooth to proceed with wireless charging, and a mutual inductance value and sign between the transmitting end and the receiving end are determined.

5 is a diagram for explaining a method of determining mutual inductance in the wireless power charging device 10 according to an embodiment of the present invention.

The controller 170 may determine the mutual inductance through the method described in Application No. 10-2019-0092894 (filed date: 2019.07.31), and the present invention uses the mutual inductance determined through the method described in Application No. 10-2019-0092894. available.

For example, as shown in FIG. 5, the equivalent circuit of the wireless power charging device includes the first to t transmission resonance circuit units 300, 320, and 340, the first to t power supply units VS1, VS2, and VSt, and the first to q reception resonance circuit units ( 310, 330, 350) and load resistors (RL1, RL2, RLq). When power is supplied to the first to t-th transmission resonance circuit units 300, 320, and 340 from the first to t-th power supply units VS1, VS2, and VSt, input voltages VP1, VP2, VPt) is generated, and reception voltages VR1, VR2, and VRq are generated in the first to qth reception resonance circuit units 310, 330, and 350.

At this time, a mutual inductance value for efficiently transmitting power from the first to t-th transmission resonance circuit units 300, 320, and 340 to the first to q-th reception resonance circuit units 310, 330, and 350 is determined as in [Equation 2].

[Equation 2]

At this time, M _tq : Mutual inductance of the t-th transmission resonance circuit unit and the q-th reception resonance circuit unit

I _Pt : input current of the t-th transmission resonant circuit

w: Operating angular frequency of the t-th transmission resonant circuit unit

R _Lq : load resistance of the qth reception resonance circuit

V _Rq : receiving voltage of the qth receiving resonant circuit unit

Z _Sq : Impedance of the qth reception resonant circuit

C _Sq : capacitor of the qth receiving resonant circuit

L _Sq : Self inductance of the qth receiving resonant circuit

R _Sq : internal resistance of the qth receiving resonant circuit

In the present invention, in order to determine the mutual inductance value, the mutual inductance value is determined through [Equation 2] in a state in which power is supplied to only one transmission resonance circuit unit and power supply is cut off to the other resonance circuit unit.

For example, after supplying current I _P1 only to the first transmission resonance circuit unit 300 and cutting off the power supply to the second transmission resonance circuit unit to the t-th transmission resonance circuit unit 320 , 340 , each other related to the first transmission resonance circuit unit 300 Determine the inductance (M _11, M ₁₂ to M _1q ). Thereafter, the current I _P2 is supplied only to the second transmission resonance circuit unit 320 and the power supply is cut off to the first transmission resonance circuit unit 300 and the third transmission resonance circuit unit (not shown) to the t-th resonance circuit unit 340. Mutual inductances (M _{21 ,} M ₂₂ to M _2q ) related to the second transmission resonant circuit unit 320 are determined. All mutual inductance values can be determined by proceeding to the t transmission resonant circuit unit 340 in the same way.

Meanwhile, when the mutual inductance value is determined, a sign of the mutual inductance is determined, and the sign of the mutual inductance is determined as in [Equation 3].

[Equation 3]

if) V _Rq,in-phase > V _{Rq,out of phase} (+)

if) V _Rq,in-phase < V _{Rq,out of phase} (-)

At this time, V _Rq,in-phase is the voltage generated in the q-th receiving resonance circuit when a predetermined same magnitude and same-phase current is supplied to the reference transmission resonance circuit and the transmission resonance circuit for determining the code, and V _{Rq,out of phase} is a voltage generated in the q-th receiving resonance circuit unit when currents of the same magnitude and opposite phases flow to the reference transmission resonance circuit unit and the transmission resonance circuit unit for determining the code. At this time, the supply of power to other transmission resonance circuit units other than the reference transmission resonance circuit unit and the transmission resonance circuit unit for determining the code is cut off.

If the sign of the mutual inductance is (+), it indicates the case where the phase is the same, and (-) indicates the case where the phase is opposite. In addition, the reference transmission resonant circuit part can be arbitrarily determined, and the signs of mutual inductances related to the reference transmission resonance circuit part are all (+).

For example, if the first transmission resonance circuit unit 300 is determined as the reference transmission resonance circuit unit, the signs of mutual inductances M ₁₁ to M _1q related to the first transmission resonance circuit unit 300 are all (+).

The first transmission resonance circuit unit 300 as a reference for determining the sign of the mutual inductance (M ₂₁ to M _2q ) related to the second transmission resonance circuit unit 320 and the second transmission resonance circuit unit 320 for determining the code A current having the same magnitude and the same phase is supplied to the receiving voltage of the first receiving resonance circuit unit to the qth receiving resonance circuit unit 310 or 350 . Thereafter, currents of the same magnitude and opposite phases are supplied to the first transmission resonance circuit unit 300 and the second transmission resonance circuit unit 320 to measure the received voltages of the first reception resonance circuit unit to the qth reception resonance circuit unit 310,350. do. When the reception voltages of the first reception resonance circuit unit to the q-th reception resonance circuit unit 310 or 350 are measured, a mutual inductance sign is determined using [Equation 3]. In this way, the signs of the mutual inductances of the third transmission resonance circuit unit (not shown) to the t-th transmission resonance circuit unit 340 may be determined.

6 is a diagram for explaining a method of controlling an output current of a transmitter in a wireless power charging device 10 according to an embodiment of the present invention.

In the present invention, since power is transmitted and received between at least one transmitter or receiver, the control unit 170 sets a subset that can be regarded as an independent transmitter or receiver unaffected by other transmitters or receivers in order to increase charging efficiency. . If subsets are set, output currents I _{P1 ,} I P2 , and I _Pt of each of the first through t-th transmitting terminals 200a, 200b _, and 200c for maximum efficiency can be determined more quickly.

The controller 170 sets a subset using a matrix of mutual inductance (M _tq ). In the matrix, a row denotes a transmitting end, a column denotes a receiving end, and i row and j column denote mutual coupling between the ith transmitting end and the jth receiving end. In this configured state, if all the elements of the row and column preceding the predetermined mutual inductance are '0', it is regarded as a separate subset from the mutual inductance. As an example, FIG. 6 shows the wireless charging device 10 as first to fourth transmitting ends (Tx ₁ , Tx ₂ , Tx ₃ , Tx ₄ ) and first to third receiving ends (Rx ₁ , Rx ₂ , Rx ₃ ). If configured, it shows how to determine the subset.

In FIG. 6 , the first receiving end (Rx ₁ ) receives power from the first and second transmitting ends (Tx ₁ and Tx ₂ ), and the second receiving end (Rx ₂ ) receives power from the second and third transmitting ends (Tx ₂ and Tx _{3 )} . ), and the third receiving terminal (Rx ₃ ) receives power from the fourth transmitting terminal (Tx ₄ ). Mutual inductance (M ₄₃ ) between the third receiving terminal (Rx ₃ ) and the fourth transmitting terminal (Tx ₄ ) constitutes a separate subset because elements in the previous row and column are all '0'. Accordingly, the mutual inductances M ₁₁ , M ₂₁ , M ₂₂ , and M ₃₂ constitute one subset, and the mutual inductance M ₄₃ constitute one subset. That is, the third receiver (Rx ₃ ) and the fourth transmitter (Tx ₄ ) constitute one subset, and the remaining transmitters and receivers constitute one subset.

을 구하며, 이때, Particle Swarm Optimization, Simmulated Annealing, Generic Algorithm 등을 이용할 수 있다.When the subsets are determined, an optimization algorithm is applied to each subset to determine output currents I _{P1 ,} I _P2 , and I _Pt of the first through t-th transmitting terminals 200a, 200b, and 200c. For example, in consideration of the limiting conditions when charging the wireless charging device 10

, and at this time, Particle Swarm Optimization, Simmulated Annealing, Generic Algorithm, etc. can be used.

When the output currents I _{P1 ,} I _{P2 , and} I _Pt of the first to t-th transmitting ends 200a , 200b , and 200c are determined, the control unit 170 transmits the determined current to the first through q-th receiving ends 210a , 210b , and 210c. ) to allow charging to proceed. At this time, the first to qth receiving ends 210a, 210b, and 210c charge with maximum efficiency through the output currents I _P1, I _{P2, and} I _Pt of the first to t transmitting ends 200a, 200b, and 200c. To do this, it is necessary to monitor the power received from each receiving end and control the output currents (I _P1, I _P2, I _Pt ) of each transmitting end.

For example, when there are a plurality of transmitters and receivers, the power transmitted by one transmitter affects the plurality of receivers, and a higher power than the target received power (hereinafter referred to as 'target received power') is received by one receiver. Since the other receiving end can receive power lower than the target receiving power, the output of each transmitting end so that the power received at each receiving end (hereinafter referred to as 'current receiving power') reaches the target receiving power of each receiving end as much as possible. It is necessary to control the current.

To this end, the control unit 170 uses the mutual inductance determined between the first to t-th transmitting ends 200a, 200b, and 200c and the first to q-th receiving ends 210a, 210b, and 210c to determine the importance of each receiving end for each transmitting end. decide Here, the importance indicates the degree of influence of the power transmitted from the transmitting end to each receiving end between any one transmitting end and each receiving end, and is determined according to the size of the mutual inductance between any one transmitting end and each receiving end. Mutual inductance It is preferable to use the absolute value of .

Since the importance is determined between one transmitting end and each receiving end, the maximum value of the importance is the total number of receiving ends having mutual inductance other than '0' with the corresponding transmitting end, and the maximum value and the minimum value are determined from the maximum value to the predetermined value according to the importance. It is determined by subtracting the value of each, and the predetermined value is preferably '1'. The minimum value of importance is '0', and when mutual inductance is '0' between any one transmitting end and each receiving end, the minimum value becomes '0'.

For example, when wireless charging is performed by transmitting power from the first and second transmitting ends to the first to third receiving ends, the mutual inductance is determined between each transmitting end and the receiving end to generate mutual inductance as shown in [Table 1] look at the case In [Table 1], the number of receivers having non-zero mutual inductance between the first transmitter and the first to third receivers is 2, and the number of receivers having non-zero mutual inductance between the second transmitter and the first to third receivers is 2. It can be seen that the number of receivers having mutual inductance is two.

_{Rx1 Rx2 Rx3 Tx1} 120 95 0 _Tx2 0 -45 80

Since the receiving end having the highest mutual inductance between the first transmitting end and the first to third receiving ends is the first receiving end, the receiving end having the greatest importance for the first transmitting end is the first receiving end, and the importance level of the first receiving end becomes '2'. Since the second receiving end has the second highest mutual inductance, '1' is subtracted from the maximum value and the importance level becomes '1', and the third receiving end has the minimum value and the importance level becomes '0'. Also, in the case of the second transmitter, since the receiver having the highest mutual inductance is the third receiver, the receiver having the greatest importance for the second transmitter is the third receiver, and the importance level of the third receiver is '2'. Since the second receiving terminal has the second highest mutual inductance, '1' is subtracted from the maximum value and the importance level becomes '1', and the first receiving terminal becomes '0' as the minimum value.

Meanwhile, the control unit 170 checks the current reception power of each reception unit using the reception voltage or reception current of each reception unit transmitted from the sensing unit 130 and determines whether the target reception power has been reached in each reception unit. In each receiver, if the target reception power is not reached, the reception power should be increased. If the target reception power is reached, the current state should be maintained, and if the target reception power is exceeded, the reception power should be decreased. To this end, the control unit 170 determines a received power control direction in order to adjust the received power for each receiving end. For example, if the received power control direction is '+1', it indicates that the current received power does not reach the target received power and the received power must be increased. '-1' indicates that the current received power exceeds the target received power and thus the received power '0' indicates that the current reception power reaches the target reception power and the reception power should be maintained.

The control unit 170 adjusts the power transmitted to each receiving end by controlling the output current of each transmitting end when the received power control direction of each receiving end is determined. At this time, since the power transmitted from one transmitter affects at least one receiver, for efficient power transmission, considering the power reception status of all receivers or the power reception status of the receiver that has the highest importance for each transmitter, Control the output current.

Specifically, first, the control unit 170 checks whether the current reception powers of the first to q-th receiving ends 210a, 210b, and 210c have all reached the target reception power, and if so, the first to q-th transmitting ends 200a and 200b. , 200c) is maintained at the current state, and if all of them are not reached, it is checked whether the current received powers of the first to qth receiving terminals 210a, 210b, and 210c fall below or exceed the target received power. When all of them fall short or exceed, the importance of the first to qth receiving ends 210a, 210b, and 210c to the first to tth transmitting ends 200a, 200b, and 200c and the first to qth receiving ends 210a, 210b, and 210c ), the output current of the first through t-th transmitting terminals 200a, 200b, and 200c is adjusted using the received power control direction.

In addition, if all of the current reception powers of the first to t-th transmission nodes 200a, 200b, and 200c have the highest importance reach the target reception power, it is checked. If all of them are reached, the output current of the first to t-th transmitting ends 200a, 200b, and 200c is maintained at the current state, and if all of them are not reached, the output current of the first to t-th transmitting ends 200a, 200b, and 200c is maintained. The 1st to t-th transmitters 200a, 200b, and 200c use the importance of the 1st to qth receivers 210a, 210b, and 210c and the received power control direction for the first to qth receivers 210a, 210b, and 210c. Regulates the output current of

If output current control of each transmitting end is required to adjust the current reception power of each receiving end, the controller 170 controls the output current of each transmitting end using [Equation 4].

[Equation 4]

At this time, S _t is the current control direction of the t th transmitter

W _tk is the importance of the k-th receiver to the t-th transmitter

d _k is the received power control direction for the k th receiving end

The controller 170 increases the output current of the t-th transmitter when 'S _t >0', decreases the output current of the t-th transmitter when ' _{S t <} 0', and In this case, the output current of the t th transmitter is maintained. For example, when power is transmitted from the first and second transmitting ends to the first to third receiving ends, the importance between each transmitting end and each receiving end can be summarized as shown in [Table 2].

_{Rx1 Rx2 Rx3 Tx1} 2 One 0 _Tx2 0 One 2

Among these, when d ₁ is (-1), d ₂ is (+1), and d ₃ is (-1), S _t is determined as follows.

Since S ₁ is less than 0, the control unit 170 reduces the output current of the first transmission end, and since S ₂ is less than 0, the control unit 170 reduces the output current of the second transmission end.

7 is a diagram for explaining a method of determining a wireless charging environment change in the wireless power charging device 10 according to an embodiment of the present invention.

While wireless power transmission is in progress between the first to t transmitting ends 200a, 200b, 200c and the first to q receiving ends 210a, 210b, 210c, a change in the wireless charging environment occurs due to a change in the receiving end itself or intrusion of foreign substances. can happen At this time, the change in the receiving end itself is a case where a new receiving end enters the charging area or a receiving end in the existing charging area moves out of the charging area so that the receiving end increases or decreases, when the load of the receiving end itself changes, the receiving end in the charging area This may be the case when moving. When a change occurs in the wireless charging environment, the controller 170 checks the change and controls the wireless charging to proceed efficiently.

Looking at the method of determining the change in the wireless charging environment in the controller 170 with reference to FIG. 7, the t th transmitter 200c looks at the first to q th receivers 210a, 210b, 210c and the foreign matter 300. As shown in FIG. 7, the equivalent circuit includes two MOS-FETs, a resistor, a capacitor, and an inductor, and descriptions of each character are as follows.

Z _Rx1 (410) : Impedance viewed from the t-th transmitter 200c to the 1st receiver

Z _Rx2 (420) : Impedance viewed from the t-th transmitter 200c to the second receiver

Z _Rxq (430): Impedance viewed from the t th transmitter 200c to the q th receiver

_ZFO (440) : Impedance facing the foreign matter in the t th transmitter 200c

The controller 170 checks a change in the wireless charging environment by using the impedance Z _int viewed from the t-th receiving end 200c toward the receiving end.

In FIG. 7, the impedance (Z _int ) can be expressed as in [Equation 5].

[Equation 5]

Impedance (Z _int ) changes when the number of receiving terminals increases or decreases in the charging area, the load of the receiving terminal itself changes, the receiving terminal moves, and foreign matter enters the charging area. Therefore, the control unit 170 checks the impedance (Z _int ) at a predetermined cycle, and if the impedance (Z _int ) is the same or the difference due to the change in the impedance (Z _int ) is within a predetermined range, the wireless charging environment is maintained. If it is determined that it is, and the difference due to the change in impedance (Z _int ) exceeds a predetermined range, it can be determined that a change in the wireless charging environment has occurred.

On the other hand, when a change in the wireless charging environment occurs due to a change in the state of the receiving end, the control unit 170 checks whether the change in the state of the receiving end is a change in the receiving end itself or an intrusion of a foreign substance so that the power charging of the receiving end can proceed smoothly. In order to increase the efficiency of wireless power transmission, the present invention proceeds with wireless charging by making the operating angular frequency (w) of the t-th transmitting end (200c) equal to the resonant angular frequency (w _o ) of the resonance unit of the t-th transmitting end (200c). . At this time, even if the receiving end itself changes, the operating angular frequency (w) operates the same as the resonant angular frequency (w _{o )} . w _o ', so that the operating angular frequency and the resonance angular frequency are different from each other. Through this, the controller 170 determines the output current (I _mt ) of the t-th transmitter 200c using [Equation 6], and the output of the t-th transmitter 200c detected by the detector 130. By comparing the current (I _mt ), it is determined whether it is a change in the receiving terminal itself or an intrusion of a foreign substance.

[Equation 6]

At this time, I _MONt is the output current of the current controller of the t-th transmitting terminal 200c.

In the case of a change in the receiving terminal itself, such as an increase or decrease in the number of receiving terminals, a change in the load of the receiving terminal, or a movement of the receiving terminal, the output current (I _mt ) of the t-th transmitting terminal 200c determined using [Equation 6] is Even if it is the same as the output current (I _mt ) of the t-th transmitter 200c detected in 130 or an error occurs, a difference occurs within a predetermined error range that has little effect on the efficiency of wireless power transmission. . However, when a foreign substance enters, the output current (I _mt ) of the t-th transmitter 200c calculated using [Equation 6] and the output current of the t-th transmitter 200c detected by the detector 130 (I _mt ) is different or the difference exceeds a predetermined range that has little effect on wireless charging efficiency. In [Equation 6], I _MONt may receive a value sensed by the sensing unit 130 .

In the case of a change in the receiving end itself, the control unit 170 can check whether there is a change in the number of receiving ends through a short-range communication method such as Bluetooth communication or determine whether each receiving end has moved in the charging area by using a change in mutual inductance. In addition, it is possible to check whether the internal load of the receiving end changes through [Equation 7], and the change in the number of receiving ends, the change in the internal load of the receiving end, and whether the receiving end moves can be sequentially checked in a predetermined order.

[Equation 7]

,

,

At this time, Z _Lq is the internal load of the q th receiving terminal 210c.

I _Sq is the receiving current of the q th receiving end 210c

V _Rq is the received voltage of the q th receiving end 210c

When the wireless charging environment changes due to a change in the state of the receiving end, the control unit 170 controls each transmitting end and each transmitting end as shown in FIGS. 5 and 6 when the number of receiving ends increases or decreases or when the receiving end moves. The mutual inductance between the receiving ends is determined and the output current of each transmitting end is controlled to smoothly supply the required power to the receiving end, and the transmission power is adjusted. In addition, when the load of the receiving end itself changes, as shown in FIG. 6, the process of adjusting the transmission power by controlling the output current of each transmitting end is performed. In addition, when a foreign substance invades, since it affects the charging efficiency, wireless charging is stopped by preventing power transmission by blocking the output of each transmitting end.

8(a) and 8(b) are flowcharts illustrating the operation of the wireless power charging device 10 according to an embodiment of the present invention.

Referring to FIGS. 8(a) and 8(b), when an object enters the charging area of the first through t-th transmitting terminals 200a, 200b, and 200c, the control unit 170 checks the object (800). ), if the object is a receiver capable of wireless charging (yes in 805), charging proceeds, and if it is a foreign substance (no in 805), charging does not proceed. When charging is in progress, the control unit 170 determines the mutual inductance between the first to t-th transmitting ends 200a, 200b, and 200c and the first to q-th receiving ends 210a, 210b, and 210c, and sets a subset for each receiving end. By determining the output current of the first through t-th transmitting terminals 200a, 200b, and 200c, charging proceeds (810).

Thereafter, the control unit 170 monitors the charging state of the receiving end and checks whether the current received power of the first through qth receiving ends 210a, 210b, and 210c all reach the target received power. If it reaches (Yes in 815), the output current of the first to t-th transmitting terminals 200a, 200b, and 200c is maintained at the current state (840), and if it does not reach it (No in 815), the first to q-th receiving terminals It is checked whether the current reception powers of (210a, 210b, and 210c) fall below or exceed the target reception power. In the case of less than or exceeding (Yes in 820), the importance of the first to qth receiving ends 210a, 210b, and 210c for the first to t transmitting ends 200a, 200b, and 200c and the first to qth receiving ends 210a , 210b and 210c), the output current of the first through t-th transmitting terminals 200a, 200b, and 200c is adjusted using the received power control direction (830).

In addition, if it does not fall below or exceed (No in 820), it is checked whether the current reception powers of the receiving end having the highest importance for the first through t-th transmitting ends 200a, 200b, and 200c reach the target reception power. If it is reached (Yes in 825), the output current of the first to t-th transmitting terminals 200a, 200b, and 200c is maintained at the current state (840), and if it is not reached (No in 825), the first to t-th transmission terminals 200a, 200b, and 200c are maintained. Using the importance of the first to qth receiving ends 210a, 210b, and 210c for the transmitting ends 200a, 200b, and 200c and the received power control direction of the received power for the first to qth receiving ends 210a, 210b, and 210c to adjust the output current of the first to t-th transmitters 200a, 200b, and 200c (830).

Meanwhile, the controller 170 monitors whether a change in the wireless charging environment occurs during charging through wireless power transmission. Specifically, the control unit 170 uses [Equation 5] and the input voltage or output current of the t-th transmitter 200c received from the sensor 130 in units of a predetermined time at the t-th receiver 200c. Impedance looking at the receiver (Z _int ) Determine (850). If the determined impedance (Z _int ) is the same or changed within a predetermined range (No in 855), the current state is maintained (880), and the changed difference in impedance (Z _int ) exceeds a predetermined range (855 Example) Check the change in the wireless charging state (860).

To this end, the controller 170 uses [Equation 6] and the output current (I _MONt ) of the current controller of the t-th transmitter 200c received from the sensor 130 to calculate the output of the t-th transmitter 200c. The current (I _mt ) is determined, and the determined current is compared with the output current (I _mt ) of the t th transmitter 200c received from the sensing unit 130 . If the current calculated by the control unit 170 and the current detected by the sensing unit 130 are the same or the difference is within a predetermined range (YES in 865), the control unit 170 checks the state change of each receiving terminal itself. Do (870). At this time, the state change of each receiving end itself is whether there is a change in the number of receiving ends, whether there is a change in the internal load of each receiving end, and whether the receiving end has moved in the charging area. When the state change of the receiving end itself is confirmed, the control unit 170 adjusts the transmission power by controlling the output current of the t-th transmitting end 200c (890).

If the current calculated by the control unit 170 and the current detected by the sensing unit 130 are different or the difference exceeds a predetermined range (No in 865), the controller 170 determines that a foreign substance has entered the charging area. After determining, the output of each transmitting end is blocked to stop wireless charging (880).

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention.

Therefore, the scope of the present invention is not limited to the described embodiments, and should be defined by not only the scope of the claims to be described later, but also those equivalent to the scope of these claims.

100: power supply unit 110: amplification unit
120: communication unit 130: detection unit
140: resonance unit 150: rectification unit
160: conversion unit 170: control unit

Claims (19)

In the wireless power charging device,
at least one transmitting end that transmits power using the power provided from the power supply unit and each includes a transmission resonator unit including one capacitor and one inductor;
at least one receiving end each including a reception resonator that receives the power transmitted from the at least one transmitting end and includes a capacitor and an inductor and a load that performs charging using the received power;
Wireless charging is performed by determining the output current of the at least one transmitting end using mutual inductance between the at least one transmitting end and the at least one receiving end, and whether the current received power of the at least one receiving end reaches the target received power. A control unit for adjusting the output current of the at least one transmitting end using the importance of the at least one receiving end to the at least one transmitting end and a received power control direction for adjusting the received power of the at least one receiving end according to device to do.
According to claim 1,
wherein the control unit determines the degree of importance between one transmitting end and at least one receiving end by considering the degree of influence of the power transmitted by the transmitting end on each receiving end.
According to claim 1,
The control unit determines a level of importance according to the magnitude of mutual inductance between one transmitting end and at least one receiving end,
The level of importance is determined by setting the total number of receiving ends having mutual inductance other than '0' between any one transmitting end and at least one receiving end to the highest value of the importance, and subtracting a predetermined value from the highest value as the next priority. device to do.
According to claim 1,
The control unit maintains an output current of the at least one transmitting terminal at a current state when the current receiving power of the at least one receiving terminal reaches the target receiving power,
Apparatus for adjusting the output current of the at least one transmitting end when the current receiving power of the at least one receiving end falls below or exceeds the target receiving power.
According to claim 1,
The control unit determines whether the current received power of at least one receiving end having the highest importance for the at least one transmitting end reaches the target receiving power when the current received power of a part of the at least one receiving end falls below or exceeds the target receiving power. A device for adjusting the output current of the transmitting end according to.
According to claim 1,
The control unit controls the output current of the at least one transmitting terminal using [Equation 5].
[Equation 5]

At this time, S _t is any one of increasing, decreasing, and maintaining in the current control direction of the t-th transmitter
W _tk is the importance of the k-th receiver to the t-th transmitter
d _k is any one of (+1), 0, and (-1) in the received power control direction for the k-th receiving terminal.
In the wireless power charging device,
at least one transmitting end that transmits power using the power provided from the power supply unit and each includes a transmission resonator unit including one capacitor and one inductor;
at least one receiving end each including a reception resonator that receives the power transmitted from the at least one transmitting end and includes a capacitor and an inductor and a load that performs charging using the received power;
Using the change in impedance viewed from the at least one transmitting end to the at least one receiving end, whether or not the wireless charging environment changes in a predetermined time unit is determined, and the output current of the at least one transmitting end is determined, and the determined output current and A device comprising a control unit for comparing the output current of the at least one transmitting terminal received from the sensing unit to determine whether the change in the wireless charging environment is any one of a change in the at least one receiving terminal itself and a foreign substance intrusion into a charging area.
According to claim 7,
The control unit determines the impedance viewed from the at least one transmitting end to the at least one receiving end in a predetermined time unit, and determines whether the wireless charging environment changes when the change in the determined impedance exceeds a predetermined range. Device.
According to claim 7,
The control unit determines the output current (I _mt ) of the at least one transmitting terminal using [Equation 6].
[Equation 6]

At this time, I _MONt is the output current of the current controller of the t-th transmitter
According to claim 7,
wherein the control unit confirms a change in the at least one receiving terminal itself when the determined output current and the received output current of the at least one transmitting terminal are the same or the difference is within a predetermined range.
According to claim 7,
Wherein the control unit confirms that the foreign matter has entered the charging area when the determined output current and the received output current of the at least one transmitting terminal are different or the difference exceeds a predetermined range.
In the wireless power charging method,
Transmits power using the power supplied from the power supply unit, and receives the power transmitted from at least one transmitting end each including a transmission resonator including one capacitor and one inductor and the at least one transmitting end, and includes one capacitor and one determining a mutual inductance between a receiving resonator including an inductor and at least one receiving terminal each including a load that performs charging using the received power;
determining an output current of the at least one transmitting end using mutual inductance between the at least one transmitting end and the at least one receiving end, and performing wireless charging;
Receive power control direction for adjusting the importance of the at least one receiving end to the at least one transmitting end and the received power of the at least one receiving end according to whether the current received power of the at least one receiving end reaches the target receiving power. and adjusting an output current of the at least one transmitting terminal using
According to claim 12,
The process of adjusting the output current of the transmitting end,
checking the total number of receiving ends having mutual inductance other than '0' between any one transmitting end and at least one receiving end;
and determining a level of importance by setting the total number as the highest value of the importance and subtracting a predetermined value from the highest value as the next priority.
According to claim 12,
The process of adjusting the output current of the transmitting end,
maintaining an output current of the at least one transmitting end at a current state when the current receiving power of the at least one receiving end reaches the target receiving power;
and adjusting an output current of the at least one transmitting node when the current receiving power of the at least one receiving node falls below or exceeds the target receiving power.
According to claim 12,
The process of adjusting the output current of the transmitting end,
When the current received power of a portion of the at least one receiving end falls below or exceeds the target received power, the current received power of at least one receiving end having the highest importance for the at least one transmitting end reaches the target received power according to whether or not the current received power reaches the target received power. A method comprising adjusting an output current of a transmitting end.
In the wireless power charging method,
Power is transmitted using the power provided from the power supply unit, and at least one transmitting terminal each including a transmission resonator unit including one capacitor and one inductor transmits power to a reception resonator unit including one capacitor and one inductor and received power. Checking whether a wireless charging environment changes in units of a predetermined time by using a change in impedance viewed from at least one receiving end each including a load that performs charging using a change in impedance;
determining an output current of the at least one transmitting terminal;
A process of comparing the determined output current with the output current of the at least one transmitting terminal received from the sensing unit to determine whether the change in the wireless charging environment is any one of a change in the at least one receiving terminal itself and an intrusion of a foreign substance into the charging area How to include.
According to claim 16,
The process of checking whether the wireless charging environment changes,
determining an impedance seen from the at least one transmitting end to the at least one receiving end in units of a predetermined time;
A method comprising determining whether the wireless charging environment changes when the determined impedance change exceeds a predetermined range.
According to claim 16,
The process of confirming that any of the above is,
and checking a change in the at least one receiving terminal when the determined output current and the output current of the at least one transmitting terminal received from the sensing unit are the same or the difference is within a predetermined range.
According to claim 16,
The process of confirming that any of the above is,
and confirming that the foreign matter has invaded the charging area when the determined output current is different from the received output current of the at least one transmitter or the difference exceeds a predetermined range.

Images