KR20120128554A - Power transmitting device and method for detecting non-power receiving target - Google Patents

Abstract

PURPOSE: A power transmitter and a method for detecting a non-power receiving target are provided to precisely determine foreign materials by comparing a measurement value with a received value. CONSTITUTION: If the change of a load is sensed above a critical value, power for communication is transmitted(205). It is determined whether a subscription request about a multiple wireless power transmission network is received in preset time by corresponding to power transmission(210). It is determined whether the change of the load is within a preset range based on the initial information of a power receiver(225). If the change of the load exceeds the preset range, the power receiver to send the subscription request is determined as the non-power receiving target(215). The power transmission for the determined non-power receiving target is stopped(245). [Reference numerals] (200) Sensing a load change?; (205) Transmitting power for communication; (210) Receiving a network subscription request message?; (215) Determining a non-power receiving object; (220) Comparing a reference load value with a load change value; (225) Is it within an allowable range?; (230) Is a network subscription possible?; (235) Transmitting a network subscription approval message; (240) Transmitting a network subscription refusal message; (245) Stopping power transmission to a corresponding charging object; (AA) Start; (BB,DD,FF,II) No; (CC,EE,GG,HH) Yes; (JJ) Finish

Description

[0001] POWER TRANSMITTING DEVICE AND METHOD FOR DETECTING NON-POWER RECEIVING TARGET [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a wireless power transmission / reception technology applied to a wireless charging technique, and more particularly, to a power transmitter for non-power receiving target detection in a resonant mode wireless power transmission / reception technique and a method thereof.

The wireless power transmission system consists of a power transmitter and a power receiver. Power transmission between the power transmitter and the power receiver is a structure in which power is transmitted between the primary coil of the power transmitter and the secondary coil of the power receiver. Such a structure is the same structure used in various power transmission systems.

The communication method used in the wireless power transmission system having the above structure can be classified into two types.

There is an in-band communication method in which communication is performed through a coil through which electric power is transmitted and an out-band method in which communication is performed through a communication terminal separate from a coil through which electric power is transmitted.

The wireless power transmission system in US2009-0133942A1, a patent of SEIKO EPSON, one of the in-band systems, operates as in Figs. 1 and 2. Fig. As shown in Figures 1 and 2, the power receiver transmits data using load modulation, and the power transmitter transmits data using frequency modulation. This communication method is an in-band method in which wireless power transmission is performed simultaneously.

In the conventional technique, after the ID authentication step for detecting foreign objects, the power transmitter sends a signal at a specific frequency and observes the width of the pulse wave. The observed value is compared with the reference value to determine whether or not the foreign substance is present.

Then, the reference value is obtained by measuring the width of the pulse wave in the previous stage of power transmission. The obtained reference value is used as a criterion for judging that a foreign object has come in when a power transmission is performed.

As described above, conventionally, when the power transmitter does not receive the ID authentication frame for the substance detected in the ID authentication step, it controls to stop power transmission. As a result, the power transmitter performs the interruption of the power transmission, but it is difficult to judge that the operation is regarded as detecting an abnormal receiving device or foreign matter and the power transmission is stopped. In addition, since the measured value is conventionally used as a reference value, it is difficult to detect a non-power receiving object when the power receiver and the foreign object are placed on the charge deck at the same time.

In addition, the prior art describes a control method of power transmission suitable for a single wireless power transmission environment, and does not consider a method for detecting a non-power receiving object in a multiple wireless power transmission environment.

As described above, in a wireless power transmission environment, when an abnormal condition such as an unhealthy power receiver or a foreign substance such as a metallic material is located in the charging area, unintended operation such as power loss / malfunction due to overload, This can happen. Therefore, there is a need for a technology to detect when an invalid device or foreign matter is located in a charging area in a wireless power transmission system.

In order to solve the above problems, the present invention provides a power transmitter and method for efficiently detecting a non-power receiving target in a wireless power transmission system.

The present invention also provides a power transmitter and method for detecting a non-power receiving target to ensure efficiency of power transmission in a multiple wireless power transmission environment.

According to another aspect of the present invention, there is provided a method for detecting a non-power receiving object in a power transmitter, the method comprising: performing power transmission for communication upon detecting a load change of a predetermined threshold value or more; And determining whether the load change is within a predetermined range based on the initial information of the power receiver included in the subscription request, Determining that the power receiver that has sent the join request is a non-power receiving target when the load change exceeds the predetermined range; and stopping power transmission to the determined non-power receiving subject .

The present invention also provides a power transmitter for detecting a non-power receiving object, comprising: a communication unit that performs wireless communication; a power supply unit that supplies power to generate a resonance frequency signal determined by the control unit; A voltage / current measurement unit for measuring a voltage and a current of a signal, a resonance signal generation unit for transmitting the power delivered from the power supply unit to one or more power receivers, a load / The control unit controls to transmit power for communication through the resonance signal generating unit, and when a join request for a multiple wireless power transmission network is received within a predetermined time corresponding to the power transmission, Based on the initial information of the receiver, the load change is within a predetermined range The control unit determines that the power receiver that has sent the join request is determined to be a non-power receiving target and stops power transmission to the determined non-power receiving subject if the load change exceeds the predetermined range .

According to the present invention, power transmission to a foreign object in a wireless power transmission lowers the efficiency of the system and may cause an accident due to a failure or overheating of the system. However, by detecting such foreign matter, the safety of the wireless power transmission system can be secured There is an advantage.

Also, since the power receiver according to the present invention informs the power transmitter of its own load characteristic, the power transmitter has an advantage that the measured value and the received value are compared with each other to determine whether there is foreign matter accurately.

Also, the power transmitter according to the present invention can detect the presence of foreign matter even if the power receiver and the foreign object are simultaneously located in the charge valid region.

In addition, in the multi-radio power transmission environment according to the present invention, it is considered that various kinds of radio power receivers are mixed and charged. Therefore, the power transmitter can monitor the power transmission state of each power receiver, It is possible to precisely monitor the size and efficiency of the power being transmitted.

FIG. 1 and FIG. 2 are diagrams illustrating an operation process of a conventional wireless power transmission system,
3 is a diagram illustrating a configuration of a multiple wireless power transmission system according to an embodiment of the present invention;
FIG. 4 is a detailed internal block diagram of a power transmitter and a power receiver in a multi-radio power transmission system according to an embodiment of the present invention;
FIG. 5 and FIG. 6 are flowcharts illustrating a process of detecting a non-power receiving object in a power transmitter according to an embodiment of the present invention;
7 is a flow chart of operation in a power receiver according to an embodiment of the present invention;

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. It is to be noted that the same components in the drawings are denoted by the same reference numerals and symbols as possible even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

The present invention provides a method for detecting non-power receiving objects in a multiple wireless power transmission system. To this end, according to the present invention, when a change in load is detected in a power transmitter, it is determined whether an authentication request message is received in response to power transmission for communication, and if an authentication request message is received, Determining whether the load variation is within a predetermined range based on the initial information, and determining the power receiver as a non-power receiving target when the load variation exceeds the predetermined range. By doing so, it is possible to detect foreign matter even if the electric power receiver and the foreign matter are simultaneously located in the charge effective region.

Prior to describing the present invention, the foreign matter is defined as follows. A foreign object is another material that receives power in addition to the intended power receiver when the power transmitter transmits power, including metallic materials, electronics that are not communicating with the power transmitter, and power receivers that the power transmitter does not intend. In the following description, such a foreign substance is collectively referred to as a non-electric power receiving object.

Hereinafter, a configuration of a wireless power transmission system according to an embodiment of the present invention will be described with reference to FIG.

Referring to FIG. 3, the power transmitter 30 detects the location of a power transmission object on the charge deck using a load detection function, and enables wireless power transmission to one or more power receivers . The power transmitter 30 and the power receiver 31 communicate with each other with a separate communication system from the wireless power transmission.

The value of the voltage (or current) measured in the primary coil of the power transmitter 30 is changed when the power receiver 31 is located within a valid range of the primary coil of the power transmitter 30, that is, in the charging effective area. That is, the voltage value measured by the load change changes. However, the same phenomenon may occur even if the Invalid Power Receiver 32 or the Invalid Materials 33 are located within the effective range of the primary coil of the power transmitter 30. [ Further, a load change may occur even when the abnormal power receiver 32 or the foreign matter 33 together with the power receiver 31 are located in the charge valid region at the same time.

In this case, the power transmission to the non-power receiving target lowers the efficiency of the power transmission, and may cause an accident due to overloading due to failure or overheating. Therefore, by detecting the non- There is a need to ensure safety.

As described above, the present invention provides a wireless power transmission system composed of a power transmitter having wireless power transmission capability and a plurality of power receivers having wireless power reception capability to a plurality of power receivers. According to the present invention, It is possible to detect an ineffective non-power receiving object among the objects to be charged even if a plurality of objects to be charged are located.

Reference is made to Fig. 4 to describe a method for detecting such non-power receiving objects. 4 illustrates an internal block diagram of a power transmitter and a power receiver constituting a wireless power transmission system according to an embodiment of the present invention.

4, the power transmitter 100 includes a power supply unit 10 configured by a VCO (Voltage Control Oscillator) or the like to supply power to the control unit 18 to generate a determined resonance frequency signal, a power supply unit 10, An amplifier 12 for amplifying a signal generated by the power supply unit 10 at a high output according to a power supplied from the power supply unit 10 according to a high output signal generated by the amplification unit 12, A resonance signal generating unit 14 for transmitting the signal to one or more power receivers through a wireless resonance signal, a voltage / current measuring unit 16 for measuring voltage and current of a signal generated in the power supply unit 10, In particular, the current and voltage of the resonance signal wirelessly transmitted in accordance with the current and voltage detected by the voltage / current measuring unit 16, For controlling the operation of the power supply unit 10 and the amplification unit 12 to maintain the power consumption of the wireless power transmission operation and to communicate with the power receiver 110 in connection with the wireless power transmission operation under the control of the control unit 18. [ And a wireless communication unit 19 configured by applying a selected one of various wireless local area communication methods. Here, the resonance signal generating unit 14 includes a charging substrate on which the power receiver can be positioned above the resonance signal generating unit 14.

In addition, the power transmitter 100 may further include a sensor unit 17 configured to detect the presence of the power receiver 110 and to provide a detection signal to the control unit 18, such as an object detection sensor. In this case, the controller 18 of the power transmitter 100 may be configured as an MCU (Micro Controller Unit), and the detecting operation of the non-power receiving object according to the present invention will be described in detail later with reference to FIGS. 5 and 6 I will explain.

The power receiver 110 includes a resonance signal receiving unit 24 for receiving the wireless resonance signal transmitted from the resonance signal generating unit 14 of the power transmitter 100, A smoothing unit 21 for smoothing the DC power rectified by the rectifying unit 22 and a smoothing unit 21 for smoothing the DC power supplied from the smoothing unit 21, A constant voltage generating unit 20 for converting a power source to a desired operating power source (for example, +5 V) in a portable terminal or the like to which the power receiver is applied, a voltage measuring unit 26 for measuring an input voltage of the constant voltage generating unit 20, A control unit 28 for collectively controlling the wireless power receiving operation of the power receiver 110, determining a power receiving state according to a detection signal of the voltage detecting unit 26, and providing information on a power receiving state . At this time, the controller 18 of the power receiver 110 may also be configured as an MCU or the like.

In addition, the power receiver 110 is provided with a wireless communication unit 29 configured by applying a selected one of various wireless local area communication methods to communicate with the power transmitter 100 in connection with the wireless power receiving operation under the control of the control unit 28, As shown in FIG. The wireless communication unit 29 can transmit and receive various information and messages required for the wireless charging process through the short distance wireless communication under the control of the control unit 28. [

Figs. 5 and 6 are operational flowcharts for detecting a non-power receiving object in the power transmitter 100, and Fig. 6 is a view subsequent to Fig. 5. Fig. The identification code 'A' is used to indicate that the step 235 of FIG. 5 is connected to the step 300 of FIG. 6, and the identification code 'B' is used to indicate that step 330 of FIG. 6 and step 215 of FIG. , And an identification code 'C' is used to indicate that step 340 of FIG. 6 and step 245 of FIG. 5 are connected.

Referring to FIG. 5, in step 200, the power transmitter 100 determines whether a load change of a predetermined threshold value or more is detected. The load change will change the voltage or current value measured at the primary coil of the power transmitter 100, for example, if the power receiver is located within a valid range of the primary coil of the power transmitter 100. Here, the voltage value or the current value is measured through the voltage / current measurement unit 16 of the power transmitter 100, and the load variation value is calculated using the voltage value or the current value measured by the control unit 18. That is, the load change value is calculated by comparing the currently measured load value with the previously measured load value. If the difference between the measured load value and the previous load value is greater than the predetermined threshold value, it is assumed that the load change has occurred. If the previously measured load value does not exist, the measured load value is compared with the initial load value to calculate the load change value, and the calculated load change value is compared with a predetermined threshold value. If the load change value is greater than or equal to a predetermined threshold value, the calculated load change value is stored.

If nothing is located in the charging effective area of the power transmitter 100 and the object to be charged enters or falls within the charging effective area, the measured voltage value or the measured current value in the power transmitter 100 is changed. Similarly, assuming that the power transmitter 100 is already transmitting a constant power to the object to be charged, the load change is detected even when a new object to be charged is located in the charge effective region.

At this time, even if an invalid electronic device or a metallic material is located within the effective range, a load change exceeding a predetermined threshold value may occur. Therefore, it is necessary for the power transmitter 100 to determine whether the charging object is a normal power receiver or a non-power receiving object such as an invalid electronic device or metal material when a load change occurs.

To this end, according to the present invention, the non-power receiving object is determined through the following method.

If a load change exceeding a predetermined threshold value is detected, the power transmitter 100 determines that an object to receive electric power is detected in the charge effective area, and transmits power for communication in step 205. At this time, the power transmitter 100 may try to communicate first to inquire whether it is a power receiver that is an object to receive power, that is, a power target to be charged. Otherwise, the power transmitter 100 tries to communicate You may. FIG. 5 illustrates a case where the charging object first tries to communicate in response to such power transmission.

Accordingly, the power receiver that receives the power and is the charging target transmits a network join request message to join the network. Here, a multi-radio power transmission is performed, and a configuration including a power transmitter that transmits power to one or more power receivers and their power receivers is defined as a network. Therefore, the network join request message includes initial information for notifying that the power receiver to be charged is a valid power receiver. This initial information includes the power receiver ID, the protocol version, the reference load value at the power receiver, and the reference efficiency value at the power receiver.

In step 210, the power transmitter 100 determines whether a network join request message is received within a time limit from the charging target that received the power. At this time, the power transmitter 100 receives the network join request message through the wireless communication unit 19, and the reception of the message is performed through the wireless communication unit 19 as described above. However, in the case of a foreign substance such as a metallic substance, the voltage value or the current value measured by the power transmitter 100 can be changed, but communication can not be performed, so that the power transmitter 100 can not respond to the power transmission. That is, it can not inform itself that it is a valid power receiver.

Therefore, if the network join request message is not received, the communication is not performed. Therefore, the power transmitter 100 proceeds to step 215 and determines that the charge object generating the load change is the non-power reception object. That is, it is judged that the cause of the load change is foreign matter.

If the network subscription request message is received within the time limit in step 210, the power transmitter 100 can distinguish it from other power receivers based on the power receiver ID in the initial information of the power receiver included in the network subscription request message, The communication protocol used to communicate with the distinct power receivers is determined based on the protocol version. At this time, the power transmitter 100 judges whether the power receiver is valid by using a load value which is changed when the power receiver is communicated with the power receiver and the power receiver is located in the charging effective area.

To this end, the power transmitter 100 compares the reference load value of the power transmitter 100 with the load variation value obtained through the load detection in step 200 in step 220. [ Here, the reference load value of the power transmitter 100 is determined by reflecting the reference load value from the power receiver so that the load value changed when the power receiver is located in the charge valid region is determined.

For example, assuming that a measured value when there is nothing in the charging effective area of the power transmitter 100 is A and a measured value that is changed as the power receiver is located in the charging effective area is B, For example, the difference between A and B or B is defined as a reference load.

Specifically, when the initial reference load of the power transmitter 100 is 500 mA and the reference load value from the power receiver, that is, the impedance value indicated by the power receiver is 10 ?, the impedance value is taken into consideration based on the initial reference load For example, the reference load value at the power transmitter 100 is determined at 300 mA. If a new power receiver is additionally located in the charging effective area, the reference load value at the power transmitter 100 is calculated based on the initial reference load, the reference load value of the existing power receiver, and the reference load value of the new power receiver .

Therefore, the reference load value that is compared with the load change value in step 220 is the reference load value in the power transmitter that reflects the reference load value from the power receiver. If the power transmitter 100 was performing power transmission to one or more power receivers, the reference load value, i.e., the impedance value, from each power receiver would be different, The value will also vary.

If the reference load value is compared with the load change value, the power transmitter 100 determines whether the difference between the calculated load change value and the reference change value is within a predetermined allowable range. Here, the allowable range may be a range based on the reference change value, and in this case, it may be implemented to determine whether the load change value falls within the allowable range.

If the power receiver 100 is out of the allowable range in step 225, the power transmitter 100 proceeds to step 215 and transmits a network join request message. In step 215, It is determined that it is a power reception target. For example, it is determined that the device can not perform the wireless charging specified by the manufacturer or the protocol. The power transmitter 100 proceeds to step 245 to stop the power transmission to the charging object. Thus, according to the present invention, by comparing the reference load value and the load change value, the power transmitter 100 can judge the foreign object approaching the valid power receiver at the same time.

On the other hand, if the comparison result is within the allowable range in step 225, the power transmitter 100 determines that the power receiver that sent the network join request message is a valid power receiver, and determines in step 230 whether the power receiver can join the network . That is, it is determined whether or not a network can be joined for multiple wireless power transmission. For example, if it is determined that the number of power receivers performing charging in power transmitter 100 has already reached the maximum number of charging targets, it may be difficult to further join the power receiver that sent the network join request to the network. And may determine that joining of the wireless power transmission network is not possible if the protocol version of the power receiver is higher than the protocol version of the multiple wireless power transmission network.

Accordingly, if the network subscription is not available in step 230, the power transmitter 100 transmits a network subscription rejection message to the power receiver that sent the network subscription request message in step 240. In step 245, the power transmitter 100 stops transmission of electric power to the power receiver that has transmitted the corresponding charging object, that is, the network join request message.

If the network subscription is available in step 230, the power transmitter 100 transmits a network subscription grant message in step 235 in response to the network subscription request message. The network join acknowledgment message includes the network ID to which the power receiver belongs, schedule information, etc., and the allocation schedule information for the power receiver is time information for preventing the charging time for each power receiver from overlapping when there are a plurality of power receivers. The power receiver receiving the network join acknowledgment message uses the network ID provided from the power transmitter 100 to transmit the message to the power transmitter 100 thereafter.

After transmitting the network join acknowledgment message in step 235, the power transmitter 100 proceeds to step 300 of FIG. 6 and determines whether a power transmission request message is received within the time limit from the power receiver. If the power transmission request message is not received within the time limit, the power transmitter 100 proceeds to step 245 of FIG. 5 and does not perform power transmission to the power receiver because the power receiver is not requesting charging, .

Otherwise, when the power transmission request message is received, the power transmitter 100 determines in step 305 whether power transmission is possible. The power transmission request message includes the reference voltage of the power receiver, the reference current, and the reference efficiency value. Accordingly, the power transmitter 100 calculates necessary power values at the power receiver using the information included in the power transmission request message. For example, if the maximum output power value in the power transmitter 100 is 20 W and the power receiver is capable of charging at 10 W, that is, if the required power value at the power receiver is 10 W, then the power transmitter 100 When the sum of the power value measured due to the power already transmitted to the other power receiver and the power value required by the power receiver exceeds the maximum output power value, the power transmitter 100 can transmit power to the power receiver . Otherwise, it is determined that power transmission to the power receiver is possible.

If the power transmission is not possible, the power transmitter 100 transmits a power transmission rejection message to the power receiver in step 310. Otherwise, the power transmitter 100 transmits a power transmission acknowledgment message in step 315 if the power power is available.

The power transmitter 100 determines in step 320 whether a power transmission status message is received from the power receiver within a time limit. If a power transmission status message is not received, the power transmitter 100 proceeds to step 245 of FIG. 5 to stop the power transmission to the power receiver. Otherwise, when the power transmission status message is received, the power transmitter 100 determines the validity of the power transmission in step 325. At this time, the power transmission state information transmitted by the power receiver includes a measurement value and a reference efficiency measuring a voltage and a current inputted through a coil or an antenna of the power receiver. The voltage value and the current value are measured by the voltage measuring unit 260 of the power receiver 110, and the voltage value and the current value may have a constant numerical value range or may be expressed as a percentage.

Accordingly, the power transmitter 100 can collect the received power transmission state information, the power value transmitted by the power transmitter 100, and the reference efficiency value included in the initial information of the power receiver to grasp the leakage power, It can be judged. For example, if the power value of the power transmitter 100 is 10W, and the power value calculated through the voltage value or the current value included in the power transmission status information provided from the power receiver is 5W, the power of the power transmitter 100 Value and the power value at the power receiver, the power efficiency value is calculated to be 50%. Here, the power value of the power transmitter 100 is calculated using the voltage value and the current value measured through the voltage / current measurement unit 16. [

The calculated power efficiency value is compared with the reference efficiency value provided by the power receiver to determine the validity of the transmission power. Here, the reference efficiency indicates that the ratio of the power transmitted from the power transmitter 100 to the power received from the power receiver is quantified when the power receiver receives a sufficient amount of power from the power transmitter 100 and is normally charged. If the comparison value, for example, the leakage power value, deviates from the power transmission value tolerance range, for example, 40 to 60%, the power transmitter 100 proceeds to step 215 of FIG. 5 to set the power receiver to an invalid ratio It is determined that it is a power reception target, and the process proceeds to step 245 where power transmission to the power receiver is stopped.

Next, in step 330, the power transmitter 100 determines whether the comparison result between the power value calculated through the measurement by the power transmitter 100 and the reference efficiency value of the power receiver is within the allowable range of the power transmission value in step 330, If it is within the range of the transmission value, the power is transmitted to the power receiver in step 335.

When the power transmitter 100 and the power receiver start the power transmission, the power receiver periodically transmits a transmission power status message including power transmission status information of the power transmitter 100 to the power transmitter 100 periodically or at regular intervals do. Accordingly, the power transmitter 100 returns to step 320 and determines whether a power transmission status message is received unless the power transmitter 100 receives a power transmission completion message from the power receiver in step 340. [ After repeating steps 320 to 335, when the power transmission completion message is received in step 340, the power transmitter 100 determines that the charging of the power receiver is completed, and proceeds to step 245 of FIG. Thereby stopping the power transmission to the base station.

As described above, the wireless power transmission system according to the present invention can be roughly divided into a network subscription step, a power transmission determination step, and a power transmission step, and foreign matter detection is possible at each step.

First, in the network joining step, the power transmitter 100 recognizes the presence of a foreign object when communication is not established for a predetermined period of time by trying to recognize a change value of a load through load detection and attempting communication.

Also, in the power transmission decision step, in the state where the power receiver is joined to the network and the power transmitter 100 is in communication with the power receiving period, the power receiver transmits a message including its ID, protocol version, reference load, And the power transmitter 100 detects a foreign object placed together with the power receiver by comparing the reference load value with the load change value detected in the above. Thereafter, in the power transmission step, when the power receiver periodically or regularly transmits a message including a voltage value and a current value received through a coil or an antenna according to a predetermined rule, the power transmitter 100, which receives the message, And the power to be transmitted is calculated to detect the foreign matter.

As described above, according to the present invention, it is possible to determine whether or not a non-power receiving object exists even if one or more objects to be charged are located in the charging effective area, and it is possible to reliably transmit power to the electric power receiver, .

Reference is now made to Fig. 7 to see the operation of the power receiver corresponding to the operation of the power transmitter of Figs. 5 and 6. Fig.

Referring to FIG. 7, when the power receiver 110 senses power reception in step 400, it transmits a request message for subscribing to the multiple wireless power transmission network in step 405. FIG. In response to this, in step 410, when a network join acknowledgment message is received from the power transmitter 100, a power transmission request message is transmitted in step 415. Otherwise, the power receiver 100 may return to step 405 if it has not received the network join acknowledgment message, and may retransmit it a predetermined number of times. If the network admission acknowledgment message is not received despite the retransmission for a predetermined number of times or more, it is considered that the subscription is rejected and the process can be terminated.

Next, after transmitting the power transmission request message, it is determined whether a power transmission approval message is received within a predetermined time, that is, a time limit. If the power transmission approval message is not received, charging is not permitted. And terminates. Otherwise, upon receipt of the power transmission acknowledgment message, the power receiver 110 confirms the output power transmission in step 425. That is, charging is performed as the power transmission from the power transmitter 100 is started, and a measurement of the current or voltage received through the voltage measurement unit 26 of the power receiver 110 in response to the power transmission is performed . Here, the output terminal means between the smoothing part 20 and the constant voltage generating part 21.

Accordingly, the power receiver 110 transmits a power transmission status message including the power transmission status information through the measurement to the power transmitter 100 in step 430. In step 435, it is determined whether the power transmission from the power transmitter 100 is completed, that is, the charging is completed. When the power transmission is completed, the output power transmission is stopped in step 440. That is, the power transmission for charging the battery is stopped. Then, the power receiver transmits a power transmission completion message in step 445 to inform the power transmitter 100 that the charging is completed. Thereafter, the power receiver maintains a standby state waiting for power transmission from the power transmitter 100 in step 450. [ The standby state means that the charging of the power receiver is completed but not disconnected from the power transmitter 100.

As described above, the power receiver transmits initial basic information such as its reference voltage value and reference efficiency value to the power transmitter 100, and after the power transmission starts, the power receiver transmits the measured voltage value and the current value to the power transmitter 100 100, thereby enabling wireless power transmission in the power transmitter 100.

At this time, in the wireless power transmission, the power transmission to the foreign substance lowers the efficiency of the system and may cause accidents due to the failure or overheating of the system. Therefore, the method for determining the non-power receiving object in the present invention is a technique for securing the safety of the wireless power transmission system. In particular, since the power receiver informs the power transmitter 100 of its own load characteristic, the power transmitter 100 according to the present invention compares the measured value with the received value to determine whether there is a non-power receiving object precisely .

In addition, in the multi-radio power transmission environment to which the present invention is applied, considering the state where various kinds of power receivers are mixed and charged, when each power receiver periodically transmits its power transmission state information, the power transmitter 100 The power transmission state of the power receiver of the entire system can be monitored and the size and efficiency of the power transmitted in the entire system can be precisely monitored.

Claims (17)

A method for detecting a non-power receiving object in a power transmitter,
Performing power transmission for communication when a load change of a predetermined threshold or more is sensed,
Determining whether a join request for a multiple wireless power transmission network is received within a predetermined time corresponding to the power transmission;
Determining whether the load change is within a predetermined range based on initial information of the power receiver included in the subscription request;
Determining a power receiver that has sent the join request as a non-power receiving target when the load change exceeds the predetermined range;
And stopping power transmission to the determined non-power receiving object. The method according to claim 1,
Further comprising the step of, if the subscription request is not received within the predetermined time corresponding to the power transmission, determining that the target detected according to the load change is a non-power receiving target Lt; / RTI > 2. The method of claim 1, wherein the initial information of the power receiver comprises:
Wherein the method comprises at least one of an ID of the power receiver, a protocol version for communication, a reference load value of the power receiver, and a reference efficiency value. The method of claim 1, wherein the step of performing power transmission for the communication comprises:
Measuring a load value of the power transmitter;
Determining that an object to receive power is detected if the measured load value differs from a previously measured load value;
And transmitting power for the communication to an object to receive the power. 4. The method of claim 3, further comprising: calculating a load change value according to the load change;
Comparing the calculated load change value with a reference load value of the power receiver,
Further comprising the step of transmitting a subscription grant message for the network to the power receiver when the comparison result is within the predetermined range. 6. The method of claim 5,
Determining whether a message requesting power transmission is received from the power receiver within a predetermined time corresponding to the transmission of the subscription grant message;
Determining whether power transmission to the power receiver is possible when a message requesting the power transmission is received;
Receiving a status message for power transmission from the power receiver periodically to the power receiver when the power transmission is possible;
Determining whether a power value leaked exceeds a permissible range by using status information on power transmission of the power receiver included in the status message each time the status message is received;
Determining the power receiver as the non-power receiving target when the leakage power value exceeds the allowable range;
And stopping power transmission to the determined non-power receiving object. 7. The method of claim 6, wherein the status information on the power transmission of the power receiver comprises:
And a voltage value or current value measured at the power receiver corresponding to the power transmission from the power transmitter. 8. The method of claim 7, wherein the step of determining whether power transmission to the power receiver is possible comprises:
Determining whether a sum of a power value required for the power receiver and a power value transmitted from the power transmitter calculated using state information on the power transmission of the power receiver is less than a maximum output power value of the power transmitter; Gt; a < / RTI > non-power receiving object. A power transmitter for detecting a non-power receiving object,
A communication unit that performs wireless communication;
A power supply unit for supplying power to generate a resonance frequency signal determined by the control unit,
A voltage / current measuring unit for measuring a voltage and a current of a signal generated by the power supply unit,
A resonance signal generator for transmitting the power delivered from the power supply to one or more power receivers,
Wherein the control unit controls the voltage / current measuring unit to transmit power for communication through the resonance signal generating unit when it detects a load change of a predetermined threshold value or more, and controls the power to be transmitted to the multiple wireless power transmission network The control unit determines whether the load change is within a predetermined range based on the initial information of the power receiver included in the join request and if the load change exceeds the predetermined range, And a control unit for determining that the transmitted power receiver is a non-power receiving target and stopping power transmission to the determined non-power receiving target. 10. The apparatus according to claim 9,
Wherein the control unit determines that the object detected according to the load change is a non-power receiving object if the addition request is not received within the predetermined time through the communication unit corresponding to the power transmission Power transmitter. 10. The method of claim 9, wherein the initial information of the power receiver comprises:
Wherein the power transmitter comprises at least one of an ID of the power receiver, a protocol version for communication, a reference load value of the power receiver, and a reference efficiency value. 10. The apparatus according to claim 9,
And a controller for controlling the voltage / current measuring unit to measure a load value at the output of the power supply unit. When the measured load value differs from the previously measured load value, it is determined that an object to receive power is detected, And transmits power for the communication through the resonance signal generation unit as a target to be received. 10. The apparatus according to claim 9,
Calculating a load change value according to the load change through the voltage / current measuring unit, comparing the calculated load change value with a reference load value of the power receiver, and when the comparison result is within the predetermined range, And transmits a join acknowledgment message to the network through the communication unit to the power receiver. 14. The apparatus of claim 13,
Determining whether a message requesting power transmission is received from the power receiver within a predetermined time period through the communication unit in response to the transmission of the subscription grant message; and upon receiving a message requesting power transmission, Wherein the power transmitter is configured to determine whether power transmission is possible and to receive a status message for power transmission from the power receiver periodically to the power receiver if the power transmission is possible. 15. The apparatus of claim 14,
Determining whether a power value leaked exceeds a permissible range by using status information on power transmission of the power receiver included in the status message each time the status message is received, The control unit determines the power receiver as the non-power receiving target, and stops power transmission to the determined non-power receiving target. 16. The method of claim 15, wherein the status information on the power transmission of the power receiver comprises:
And a voltage value or current value measured at the power receiver corresponding to the power transmission from the power transmitter. 15. The apparatus of claim 14,
Determining whether a sum of a power value required for the power receiver and a power value transmitted from the power transmitter calculated using state information on the power transmission of the power receiver is less than a maximum output power value of the power transmitter, And determines that the power transmission is possible if it is smaller than a maximum output power value of the power transmitter.

Images