KR102198935B1 - Apparatus and method for detecting foreign object in wireless power transmitting system - Google Patents

Abstract

The present invention relates to an apparatus and method for detecting foreign matter in a wireless power transmission system. In this specification, a foreign material detection operation is performed before initial charging, when a foreign material is not detected until charging starts, a foreign material detection operation is performed during charging, and a foreign material is not detected while receiving the power signal, the temperature sensor It includes limiting the power based on.

Description

Foreign matter detection device and method in wireless power transmission system {APPARATUS AND METHOD FOR DETECTING FOREIGN OBJECT IN WIRELESS POWER TRANSMITTING SYSTEM}

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

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

The electrical connection method between the charger and the battery cell for charging electric energy in the battery cell is to supply electric energy to the battery cell through the terminal of the battery cell by converting it into voltage and current corresponding to the battery cell by receiving commercial power. Includes terminal supply method.

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

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

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

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

Another technical object of the present invention is to provide an apparatus and method for detecting foreign substances in the initial recognition stage.

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

Another technical problem of the present invention is to provide an apparatus and method for performing an operation of limiting power in response to foreign matter detection in a wireless power transmission system.

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

According to an aspect of the present invention, a method of detecting a foreign substance in a wireless power receiver includes the steps of performing a foreign substance detection operation before initial charging, and when a foreign substance is not detected until charging starts, one-way communication or two-way communication is used. And performing a foreign material detection operation during charging, and when a foreign material is not detected in the foreign material detection operation during charging, sensing a fine foreign material that has not been detected with a temperature sensor to limit power.

According to another aspect of the present invention, a wireless power receiving device for detecting foreign matter is 2 for receiving wireless power from the wireless power transmitting device by combining a primary core block provided in the wireless power transmitting device by magnetic induction or magnetic resonance. Rectification that is connected to the primary core block and the secondary core block, and provides power to the control unit and external load by performing full-wave rectification on the AC waveform generated in the secondary core block. And a control unit that measures an initial voltage of the unit and an output terminal connected to the external load, and controls the wireless power receiver to enter a foreign matter detection phase when the initial voltage is in a reference voltage range, and , The control unit performs a foreign substance detection operation before initial charging, or when a foreign substance is not detected until charging starts, performs a foreign substance detection operation during charging using one-way communication or two-way communication, or the foreign substance detection operation during the charging. If no foreign matter is detected in the, the power is limited by detecting the undetected fine foreign matter with the temperature sensor.

Since the wireless power transmission device according to the present invention can detect the foreign matter at any point during charging from before the start of charging, the probability of detecting the foreign matter may increase. In addition, since the method of detecting foreign substances in each step is clearly defined, implementation of foreign substance detection is facilitated. Further, the wireless power transmitter may detect foreign substances based on information exchanged with the wireless power receiver, or may detect foreign substances without the information, thereby enabling detection of foreign substances compatible with various products. In this way, when a foreign material is detected, the wireless power transmission is stopped or the user is allowed to remove the foreign material, thereby preventing damage to the device by the foreign material.

1 shows components of a wireless power transmission system according to an example of the present invention.
2 is a flow chart illustrating a method of detecting foreign substances in a wireless power transmission system according to an example of the present invention.
3 is a flowchart illustrating a method of detecting foreign substances in a wireless power transmission system according to another example of the present invention.
4 is a flowchart illustrating a method of detecting foreign substances in a wireless power transmission system according to another example of the present invention.
5 is a flowchart illustrating a method of detecting foreign substances in a wireless power transmission system according to an example of the present invention.
6 is a flowchart illustrating an operation of a wireless power transmission system according to another example of the present invention.
7 is a flowchart illustrating an operation of a wireless power transmission system according to another example of the present invention.
8 is a block diagram showing a wireless power transmission apparatus according to an example of the present invention.
9 is a block diagram showing a wireless power transmission apparatus according to another example of the present invention.
10 is a block diagram showing a wireless power receiver according to an example of the present invention.

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

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

Referring to FIG. 1, a wireless power transmission system 100 includes a wireless power transmission device 110 and one wireless power reception device 150-1 or n wireless power reception devices 150-1,...,150. -n).

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

The wireless power receiving devices 150-1,...,150-n are detachable from the wireless power transmitting device 110, and each wireless power receiving device 150-1,...,150-n is A secondary core block coupled with an electromagnetic field generated by the primary core block of the wireless power transmission device 110 when it is in the vicinity of the wireless power transmission device 110 is provided. The secondary core block may include a core and one or more secondary coils.

The wireless power transmitter 110 transmits power to the wireless power receiver 150-1,...,150-n without direct electrical contact. At this time, it is said that the primary core block and the secondary core block are magnetically inductively coupled or resonantly inductively coupled to each other. The primary or secondary coil can have any suitable shape, but can be a copper wire wound around a high permeability formation, such as ferrite or amorphous metal.

Wireless power receiver (150-1,...,150-n) is usually connected to an external load (not shown. Here, also referred to as the actual load of the wireless power receiver), the wireless power transmission device 110 The received power is supplied to an external load. For example, the wireless power receiver 150-1, ..., 150-n may each carry a portable electric or electronic device or an object that consumes or stores power, such as a rechargeable battery cell or battery.

2 is a flow chart illustrating a method of detecting foreign substances in a wireless power transmission system according to an example of the present invention.

Referring to FIG. 2, a foreign object detection operation is performed before initial charging (S200). As an example, the operation of detecting foreign matter before initial charging is shown in FIG. 5 below.

If a foreign material is detected before initial charging (S205), a power limiting operation corresponding to the foreign material detection is performed (S225).

If a foreign material is not detected before initial charging (S205), when charging starts, a foreign material detection operation is performed during charging (S210).

For example, while charging, one-way communication may be performed to detect foreign matter. As an example, the operation of detecting foreign matters using one-way communication during charging is shown in FIG. 6 below.

As another example, a foreign substance may be detected by performing bidirectional communication while charging. As an example, an operation of detecting foreign substances using bidirectional communication during charging is shown in FIG. 7 below.

As another example, while charging, the one-way communication and the two-way communication may be performed simultaneously or independently to detect foreign matter.

When a foreign material is detected during charging (S215), a power limiting operation corresponding to the foreign material detection is performed as in step S225.

When a foreign material is not detected during charging (S215), when a problem occurs in power transmission due to a fine foreign material that has not been detected, power is limited based on a temperature sensor (or thermistor) to protect power transmission (e.g., power off ) (S220). The temperature sensor may be attached to a receiving device or a transmitting device.

Alternatively, even after the power limiting operation corresponding to foreign matter detection is performed in step S225, power is limited based on a temperature sensor (or thermistor) in order to protect power transmission when a problem occurs in power transmission due to a fine foreign matter that has not been detected.

3 is a flowchart illustrating a method of detecting foreign substances in a wireless power transmission system according to another example of the present invention.

Referring to FIG. 3, a foreign object detection operation is performed before initial charging (S300). As an example, the operation of detecting foreign matter before initial charging is shown in FIG. 5 below.

If a foreign material is detected before initial charging (S305), a power limiting operation corresponding to the foreign material detection is performed (S315).

When a foreign material is not detected before initial charging (S305), and a problem occurs in power transmission due to a fine foreign material that is not detected, power is limited based on a temperature sensor (or thermistor) to protect power transmission (e.g. Hang up) (S310). The temperature sensor may be attached to a receiving device or a transmitting device.

Alternatively, even after the power limiting operation corresponding to foreign matter detection is performed in step S315, power is limited based on a temperature sensor (or thermistor) in order to protect power transmission when a problem occurs in power transmission due to a fine foreign matter that has not been detected.

4 is a flowchart illustrating a method of detecting foreign substances in a wireless power transmission system according to another example of the present invention.

Referring to FIG. 4, when charging starts, a foreign object detection operation is performed during charging (S400).

For example, while charging, one-way communication may be performed to detect foreign matter. As an example, the operation of detecting foreign matters using one-way communication during charging is shown in FIG. 6 below.

As another example, a foreign substance may be detected by performing bidirectional communication while charging. As an example, an operation of detecting foreign substances using bidirectional communication during charging is shown in FIG. 7 below.

As another example, while charging, the one-way communication and the two-way communication may be performed simultaneously or independently to detect foreign matter.

When a foreign substance is detected during charging (S405), a power limiting operation corresponding to the foreign substance detection is performed (S415).

When a foreign material is not detected during charging (S405), when a problem occurs in power transmission due to a fine foreign material that has not been detected, power is limited based on a temperature sensor (or thermistor) to protect power transmission (e.g., power off )(S410). The temperature sensor may be attached to a receiving device or a transmitting device.

Alternatively, even after the power limiting operation corresponding to foreign matter detection is performed in step S415, power is limited based on a temperature sensor (or thermistor) in order to protect power transmission when a problem occurs in power transmission due to a fine foreign matter that has not been detected.

Now, the operation of detecting a foreign substance according to the present invention will be described separately before initial charging and after charging (eg, use of one-way communication or use of two-way communication).

<1. Foreign matter detection operation before initial charging>

5 is a flowchart illustrating a method of detecting foreign substances in a wireless power transmission system according to an example of the present invention. This corresponds to step S200 of FIG. 2 or step S300 of FIG. 3.

Referring to FIG. 5, in the ping phase, the wireless power transmitter performs digital ping. At this time, the wireless power transmitter transmits a power signal of an operating point to the wireless power receiver (S500).

Upon receiving the power signal of the ping phase, the wireless power receiver generates a signal strength packet indicating the received strength of the power signal and transmits it to the wireless power transmitter (S505). Then, the wireless power receiver generates an identification packet indicating a unique ID of the wireless power receiver and configuration information of the wireless power receiver, and transmits the identification packet and configuration information to the wireless power transmitter (S510).

The wireless power receiver measures the received power (S515). From this point, it enters the step of setting the initial voltage V _i .

The wireless power receiver determines whether a termination reason such as over voltage power (OVP), over current power (OCP), or full charge occurs (S520). If OVP, OCP, full charge, or other type of charge reason occurs, the wireless power receiver ends the charge (S525). If the type reason does not occur, the wireless power receiving device determines whether it is in a state of receiving wireless power from the wireless power transmitting device, that is, charging (S530).

In step S530, if it is being charged, the wireless power receiver compares the received power against the requested power, generates a power control packet based on the result, and transmits the power control packet to the wireless power transmitter (S535). In step S535, if it is not charging, the wireless power receiver determines whether the initial voltage V _i is in a hold state (S540). When the value of the initial voltage V _{i in} the normal state is within the reference voltage range (for example, 7.0V to 10.5V), the wireless power receiver is initially set. As a result, the initial voltage V _i becomes a hold state, and the wireless power receiver can enter the foreign matter detection phase.

If it is not in the V _i hold state, the wireless power receiver generates a power control packet and transmits it to the wireless power transmitter as in the case of charging (S535). If V _i hold state, the wireless power receiver enters the foreign matter detection phase. Here, the wireless power receiver generates a foreign substance state packet and transmits it to the wireless power transmitter (S545).

The foreign matter state packet according to the present invention includes a preamble, a header, a message, and a checksum. The preamble can be composed of a minimum of 11 bits to a maximum of 25 bits, and the values of all bits can be set to 0. The preamble is used by the wireless power transmitter to accurately detect the start bit of the header of the foreign substance state packet and synchronize the incoming data.

The header indicates the type of packet, and may consist of 8 bits. As an example, the value of the header of the foreign matter state packet may be '0x00'. In this case, the message may have a value of 0, that is, set to '0x00'. As another example, the header value of the foreign material status packet may be '0x05', which is the same as the header of the charge status packet. However, by setting the value of the 1-byte message of the charge status packet to '0x00', it may be indicated that the packet is a foreign material status packet. That is, the foreign matter state packet is included in the charge state packet.

The wireless power transmission apparatus checks whether the received packet is a foreign substance state packet based on the value of the header or message of the received packet. And, if it is determined that the foreign matter state packet has been received, the wireless power transmission device detects the foreign matter (S550). The operation of checking the foreign matter status packet and the foreign matter detection are performed by the control unit of the wireless power transmission device.

<2. Foreign matter detection while charging>

<2-1. Foreign matter detection using one-way communication while charging>

6 is a flowchart illustrating an operation of a wireless power transmission system according to another example of the present invention. This corresponds to step S210 of FIG. 2 or step S400 of FIG. 4.

6, the wireless power transmitter searches for a wireless power receiver (S600). At this time, the wireless power transmitter is in a charging standby state until the wireless power receiver is searched.

If the detected object is a wireless power receiver, the wireless power transmitter enters the charging mode and transmits wireless power to the wireless power receiver (S605). In the charging mode, the wireless power transmitter applies power to the primary coil to generate an induced magnetic field or resonance.

The wireless power transmitter measures a current flowing through the primary coil, and the wireless power transmitter obtains a current measurement value from the current flowing through the primary coil (S610). The current measured by the wireless power transmission device may be an AC current. The current measurement value may be converted into a DC value suitable for recognition by the control unit in the wireless power transmission device. That is, the wireless power transmission device measures a relatively high AC current flowing through the primary coil, and maps the measured high current to a current measurement value that is a value suitable for the control unit to analyze as shown in Table 1.

The wireless power transmission device detects foreign matter by using any one or a combination of two or more of parameters such as a reference current I _ref , a reference range (I _low to I _high ), a reference AC signal, and a foreign matter detection time t (S615) ). In addition, parameters such as the reference current I _ref , the reference range (I _low ~ I _high ), the reference AC signal, and the foreign matter detection timing t may be pre-stored in the wireless power transmitter as initial setting values.

The wireless power transmitter continuously transmits power to the wireless power receiver if no foreign matter is detected (S620). In addition, the wireless power transmitter obtains the current measurement value of the primary coil again at a time t predetermined by the system or standard (S610), and may attempt to detect foreign matters based on this (S615).

On the other hand, when a foreign substance is detected, the wireless power transmission device cuts off the wireless power transmitted to the wireless power reception device (S625).

<2-2. Foreign matter detection operation using two-way communication while charging>

7 is a flowchart illustrating an operation of a wireless power transmission system according to another example of the present invention. This corresponds to step S210 of FIG. 2 or step S400 of FIG. 4.

For example, performing two-way communication means that when power is transmitted from the transmitting device to the receiving device, the receiving device notifies the received power value to the transmitting device, and if the power loss is more than a predetermined reference value, it is determined as FOD. Say what to do. For example, performing two-way communication means that when the transmitting device transmits 7 to 10W of power to the receiving device and receives 5W of power from the receiving device, the received power value '5W' is notified to the transmitting device, and the power loss is 2W. It is more than the predetermined reference value of 1W, so it is judged as FOD. Through this, it is possible to detect the FOD in the power transmission step.

When two-way communication is specifically described with reference to FIG. 7, the wireless power transmitter searches for a wireless power receiver (S700). At this time, the wireless power transmitter is in a charging standby state until the wireless power receiver is searched.

If the detected object is a wireless power receiver, the wireless power transmitter enters the charging mode and transmits wireless power to the wireless power receiver (S705). In the charging mode, the wireless power transmitter applies power to the primary coil to generate an induced magnetic field or resonance.

The wireless power transmission device transmits a transmission power measurement report indicating the measured transmission power to the wireless power reception device (S710). For example, the wireless power transmitter transmits a transmission power measurement report to the wireless power receiver as an FSK signal. Here, the FSK signal refers to a signal transmitted using the FSK method.

The FSK signal may include a simple amount of power (eg, amount of transmit power). In this case, the wireless power transmission device may transmit the FSK signal at a constant period. This is because the wireless power receiver may not know when to transmit the FSK signal. The predetermined period may be a period in which a predetermined number of data signals are transmitted (eg, an ASK signal is constant).

For example, the amount of transmission power may be a value obtained by measuring the power generated by the main coil by the wireless power transmitter according to an AC current signal.

The FSK signal switches or selects a variable frequency (e.g., 140 or 140.3 Khz) in a certain range for converting one fixed power frequency (f ₀ , for example, 145 kHz) required by the receiving device. Thus, it refers to a signal that transmits 0 and 1 values. As another example, it refers to a signal that transmits a data signal including a 0 value and a 1 value using a phase.

As an example, the wireless power transmitter may measure power generated by the main coil according to the AC current signal, configure a transmission power measurement report indicating the measured generated power, and transmit it to the wireless power receiver. In this way, control information is transmitted from the wireless power transmitter to the wireless power receiver (for example, control information can be transmitted with an FSK signal), or from the wireless power receiver to the wireless power transmitter. Two-way communication through which control information is transmitted is possible.

The wireless power transmission device performs PWM using an inverter and generates a frequency allowed for the required power (or required power) of the wireless power receiver.

The required power of the wireless power receiver generates a duty cycle or voltage, and the duty cycle or voltage value is the power value of the wireless power transmitter. That is, the power of the wireless power transmission device may be expressed as a voltage applied to the inverter, a duty setting, and a frequency.

In the step of transmitting power by the wireless power transmitter, a set value (eg, voltage, duty frequency) is transmitted to the wireless power receiver by an FSK method.

At this time, the wireless power receiver stops receiving the existing data signal (eg, ASK signal) and receives the FSK signal. For example, the reception operation of the FSK signal includes a demodulation operation of the FSK signal.

The FSK signal may be transmitted at a constant period 750. For example, the constant period 750 may be a transmission period of a predetermined time (eg, 3 seconds and 5 seconds) or a predetermined number of data signals (eg, ASK signals).

The FSK signal may be transmitted simultaneously with wireless power. That is, S705 and S710 may be performed simultaneously.

Subsequently, the wireless power receiver detects a foreign object based on the transmission power measurement report (S715). For example, the FSK signal including the received power value measured by the wireless power receiver and the generated power measurement report is calculated, and if the difference value is more than a predetermined reference value, it is determined as FOD. As another example, the wireless power receiver determines the FOD if the'receive power-transmission power' is more than a predetermined reference value.

For example, the measured received power value may be information indicating whether a difference between the power indicated by the transmission power measurement report and the requested power is greater than, equal to, or less than a threshold. For example, if the difference between the power indicated by the transmission power measurement report and the requested power is greater than the threshold, the'received power measurement result = 1'is set, and the difference between the power indicated by the transmission power measurement report and the requested power is the threshold. If less than or equal to,'receive power measurement result = 0'may be set. Or, on the contrary, when the difference between the power indicated by the transmission power measurement report and the required power is greater than or equal to the threshold value,'received power measurement result = 1'is set, and the difference between the power indicated by the transmission power measurement report and the required power When is less than the threshold, it may be set to'receive power measurement result = 0'. For example, let's say the threshold is 1W. As in the above example, in a situation where the power indicated by the transmission power measurement report is 12W and the required power is 10W, the difference is 2W, which is greater than the threshold value of 1W. In this case, the reception power measurement result indicates 1. If the difference between the power indicated by the transmission power measurement report and the required power is greater than the threshold, this may mean that a foreign object has been detected. Accordingly, the wireless power transmission device 40 may recognize this as a foreign matter detection declaration.

The wireless power receiving device transmits an ASK signal including a foreign substance detection result to the wireless power transmitting device (S720).

The ASK signal may include a power control signal, an FOD detection signal, an emergency signal or a buffer signal.

In addition, the ASK signal may include information on required power of the wireless power receiver. The required power information refers to information that requests the wireless power transmitter to generate wireless power based on a magnetic induction method, and the wireless power transmitter checks the required power information and generates a control signal so that the power indicated in the required power information is induced. This is the information to be generated. For example, when the requested power information indicates 10W, the wireless power transmission device generates a control signal so that 10W is transmitted.

The ASK signal may be transmitted in the form of a control error packet, a rectified packet, or a charger state.

Subsequently, the wireless power transmission device may transmit wireless power based on the received ASK signal (S725).

Since it is impossible to transmit and receive data signals (eg, ASK signals or FSK signals) at the same time, transmission or reception is performed sequentially. On the other hand, since power is continuously generated through the induction frequency, it is possible to transmit the power signal and the data signal at the same time. Accordingly, wireless power may be transmitted simultaneously or at any time regardless of the time point at which the ASK signal and the FSK signal are transmitted and received.

According to the steps S720 and S725, the ASK signal and the wireless power may be transmitted and received multiple times.

When a certain period 750 elapses with respect to step S710, the wireless power transmitter transmits a transmission power measurement report indicating the measured transmit power to the wireless power receiver (S730). For example, the wireless power transmitter transmits a transmission power measurement report to the wireless power receiver as an FSK signal. The constant period 750 may be a transmission period of a predetermined time (eg, 3 seconds and 5 seconds) or a predetermined number of data signals (eg, ASK signals).

On the other hand, if it is determined that the foreign matter is detected by the wireless power receiver, the wireless power transmitter may perform a measure for detecting the foreign matter (not shown in the drawing). For example, the wireless power transmitter may enter a cut-off mode in which driving of the main coil is reduced or stopped. As a result, heat generation of the parasitic load may be prevented, and the supply of inefficient induced power may be limited or stopped.

8 is a block diagram showing a wireless power transmission apparatus according to an example of the present invention.

Referring to FIG. 8, the wireless power transmission device 800 includes a primary coil 810, an electric driving unit 820, a control unit 830, and a current measuring unit 840.

The electric drive unit 820 is connected to the primary coil 810 to apply an electric drive signal, such as an AC signal, to the primary coil 810 to generate an electromagnetic field.

The control unit 830 is connected to the electric drive unit 820 and generates a control signal 831 that controls the AC signal required when the primary coil 810 generates an induced magnetic field or generates magnetic resonance. , It is input to the electric drive unit 820.

The control unit 830 controls operations in a ping phase, an ID identification and configuration phase, a foreign matter detection phase, and a power transmission phase of the wireless power transmitter 800. In addition, the control unit 830 may generate a packet required in each phase and transmit it to the wireless power receiver or receive a packet from the wireless power receiver.

Here, the ping phase may be defined as an attempt to discover an object capable of receiving wireless power. In the ping phase, the control unit 830 performs digital ping, and the control unit 830 controls the primary coil 810 to transmit a power signal at an operating point. The signal 831 is applied to the electric drive unit 820. And, when a correct signal strength packet is received within a specific time window from the wireless power receiver, the control unit 830 identifies the state of the wireless power transmitter 800 by ID and Transition to the construction phase.

Further, in the ID identification and configuration phase, the control unit 830 identifies the wireless power receiver and collects configuration information of the wireless power receiver. In this case, the control unit 830 receives an identification packet or an identification packet and configuration information from the wireless power receiver.

In addition, in the foreign matter detection phase, the control unit 830 performs foreign object detection (FOD), and when no foreign matter is detected, transitions the wireless power transmission device 800 to the power transmission phase, and wireless power is reduced. The control signal 831 is applied to the electric drive unit 820 to be transmitted. On the other hand, when a foreign substance is detected, the control unit 830 stops applying the control signal 831 and enters an emergency mode. According to this, before the power transmission phase in which the wireless power transmitter 800 transmits the wireless power to the wireless power receiver in earnest, foreign matter detection is performed. That is, since foreign matter detection is performed immediately after the wireless power transmission device 800 and the wireless power receiving device complete identification (or recognition) between each other, the risk of performing foreign matter detection during wireless power transmission is prevented in advance. Can be prevented.

In this embodiment, the foreign matter detection phase and the power transmission phase are separately classified, but the two phases may be integrated into one phase and controlled. Alternatively, the foreign matter detection phase may belong to the power transmission phase and may be controlled by one procedure. Hereinafter, the foreign matter detection phase will be described as having an independent status.

The current measurement unit 840 obtains a current measurement value I _measured from the current flowing in the primary coil 810 and inputs it to the control unit 830. The current measurement value I _measured may be converted into a DC value suitable for recognition by the control unit 830. That is, the current measurement unit 840 measures a relatively high AC current flowing through the primary coil 810, and maps the _measured high current to a current measurement value I _measured , which is a value suitable for the control unit 830 to analyze ( mapping), and inputs the current measured value I _measured to the control unit 830.

Hereinafter, it will be described in detail what operation each component of the wireless power transmitter 800 performs to detect a foreign object.

When the control unit 830 sends a control signal 831 corresponding to the reference AC signal to the electric drive unit 820, the electric drive unit 820 applies the reference AC signal to the primary coil 810. Here, the reference AC signal ensures that the transmission efficiency of the wireless power stays within the normal range (or satisfies the required power level of the receiving device) in an environment without foreign substances, that is, an environment where there are no obstacles to the transmission of wireless power. It may be a value obtained experimentally as an AC signal. When a reference AC signal is applied to the primary coil 810, a reference current I _ref flows through the primary coil 810, and at this time, wireless power W _ref is transmitted.

However, if a foreign matter appears between the wireless power transmitter 800 and the wireless power receiver, the wireless power receiver receives only the remaining power W _ref -W _FO except for the power W _FO consumed by the foreign matter. From the standpoint of the wireless power receiver, if it does not receive as much as W _F0 , a power increase request message is transmitted to the wireless power transmitter 800 to request more power. The power up request message may be referred to as a control error packet. On the contrary, when the wireless power receiver receives power equal to or greater than the required power, a power down request message may be transmitted to the wireless power transmitter 800.

The wireless power receiver may continuously transmit a power up request message or a power down request message to the wireless power transmitter 800 until the required power is satisfied. For example, the wireless power transmitter 800 receiving the power increase request message increases the intensity of the current flowing through the primary coil 810 so that higher power is transmitted as a response thereto. More specifically, in order to allow a larger current to flow through the primary coil 810, the control unit 830 includes a control signal 831 so that an AC signal larger than the reference AC signal can be applied to the primary coil 810. ) Can be adjusted. This series of processes is collectively referred to as power control.

As a result of the power control, a state in which the current measured value in the primary coil 810 is greater than a predetermined period may occur. The fact that I _measured , which is a larger current than the reference current I _ref , flows through the primary coil 810 for the transmission of the required power, means that the transmission efficiency of wireless power is lowered, and at the same time, it is applied to foreign substances other than the wireless power receiver. This may mean that a certain amount of power is continuously consumed. As described above, when a relatively excessive current flows through the primary coil 810, the control unit 830 determines that foreign matters exist. That is, the control unit 830 may detect an element that causes an obstacle to transmission of wireless power, for example, a foreign material such as metal, based on the current measured value I _measured .

The control unit 830 may use any one or a combination of two or more of parameters such as a reference current I _ref , a reference range (I _low ~ I _high ), a reference AC signal, and a foreign material detection time t for foreign material detection. In addition, parameters such as a reference current I _ref , a reference range (I _low to I _high ), a reference AC signal, and a foreign substance detection timing t may be stored in the control unit 830 as initial setting values. The reference current I _ref and the reference range (I _low ~ I _high ) may be referred to as a reference value.

As an example, the control unit 830 compares the current measured value I _measured and the reference current I _ref . And if the current measured value I _measured exceeds the reference current I _ref (ie I _measured > I _ref ), it is judged that a foreign object has been detected. On the other hand, if the current measured value I _measured is less than or equal to the reference current I _ref (ie, I _measured ≤ I _ref ), it is determined that there are no foreign substances. Here, the reference current I _ref may be defined, for example, as follows according to the rated power (W) of the wireless power receiver.

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

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

As another example, the control unit 830 checks whether the current measurement value I _measured falls within a reference range (I _low to I _high ). And if the current measured value I _measured falls within the standard range (ie, I _low ≤ I _measured ≤ I _high ), it is judged that there is no foreign substance. On the other hand, if the current measurement value I _measured does not fall within the standard range (ie, I _measured > I _high or I _measured <I _low ), it is determined that a foreign object has been detected.

The control unit 830 may attempt to detect the foreign matter at a time t predetermined by the system or standard.

As an example, a time point t at which the control unit 830 attempts to detect a foreign matter may be after every power control time point. For example, after the wireless power transmitter 800 receives a power up request message or a power down request message from the wireless power receiver and raises or lowers the AC signal, the current measured value flowing through the primary coil 810 You can try to detect foreign objects using.

As another example, the time point t at which the control unit 830 attempts to detect a foreign substance may be a predetermined detection period. For example, the detection period should be at least shorter than the time it takes for the foreign material to heat up above a certain temperature. This is because if the heat generation of foreign substances becomes severe, it may cause serious problems in safety due to fire and body burns. Therefore, it is preferable that the detection period is set to a value whose stability has been verified by an experiment, thereby preventing various dangers that may occur during charging, such as heat generated by foreign substances during wireless charging.

When a foreign substance is detected, the control unit 830 blocks the transmission of wireless power by controlling the electric drive unit 820 so as not to apply an AC signal to the primary coil 810.

9 is a block diagram showing a wireless power transmission apparatus according to another example of the present invention.

Referring to FIG. 9, the wireless power transmission device 900 includes a primary core block 910 including m primary coils 910-1,...910-m, a switching unit 920, and electric drive. A unit 930, a control unit 940, and a current measurement unit 950 are included.

The switching unit 920 selectively connects all or at least one of the m primary coils 910-1, ... 910-m to the electric drive unit 930 by a switching method.

The electric drive unit 930 may be connected to the m primary coils 910-1, ... 910-m through the switching unit 920, and n primary coils 910-1 to generate an electromagnetic field. , ... 310-n) simultaneously or to at least one primary coil selected from among n primary coils 910-1,...310-n.

The control unit 940 is connected to the electric drive unit 930 to control an AC signal required when the n primary coils 910-1,...310-n generate an induced magnetic field or generate resonance. A control signal 941 is generated.

The current measuring unit 950 measures the currents flowing through the m primary coils 910-1, ... 910-m individually or by summing them. In particular, the current measured by the current measuring unit 840 may be an AC current. The current measurement unit 840 may be a current sensor. Alternatively, the current measurement unit 840 may be a transformer that lowers a high current flowing through the primary coil to a low current.

As an example, the current measuring unit 950 selects only the primary coils through which current flows from m primary coils 910-1,...910-m, and individually measures the current flowing through each of the selected primary coils. And, a plurality of individual current measurement values I ₁ , I ₂ ,...I _m are acquired and input to the control unit 940. Current measurement values I ₁ , I ₂ ,...I _m may be converted into DC values suitable for recognition by the control unit 940. That is, the current measurement unit 950 measures a relatively high alternating current flowing through the primary coils 910-1,...,910-m, and the control unit 940 analyzes the measured high current. Mapping as shown in Table 1 to numerical current measurement values I ₁ , I ₂ ,...I _m , and inputting the current measurement values I ₁ , I ₂ ,...I _m to the control unit 940 do.

As another example, the current measuring unit 950 selects only the primary coils through which current flows from m primary coils 910-1,...910-m, and measures the current flowing through the selected primary coils. , One total current measurement value I _SELECTED is input to the control unit 940.

As another example, the current measurement unit 950 measures the total current flowing in all m primary coils 910-1,...910-m, and one total current measurement value I _TOTAL is _converted into the control unit ( 940).

The control unit 940 may use any one or a combination of two or more of parameters such as a reference current I _ref , a reference range (I _low ~ I _high ), a reference AC signal, and a foreign material detection timing t for foreign material detection. In addition, parameters such as a reference current I _ref , a reference range (I _low to I _high ), a reference AC signal, and a foreign substance detection time t may be stored in the control unit 940 as initial setting values.

As an example, the control unit 940 compares the measured current values I ₁ , I ₂ ,...I _m and the reference current I _ref , respectively. And if at least one of the current measurement value and current measurement value I ₁ , I ₂ ,...I _m exceeds the reference current I _ref (i.e., I ₁ or I ₂ or ...I _m > I _ref ), a foreign object It is determined that this has been detected. On the other hand, if the current measurement values I ₁ , I ₂ , ...I _m are all less than the reference current I _ref (i.e., I ₁ and I ₂ and ...I _m ≤ I _ref ), it is determined that there are no foreign substances. .

As another example, the control unit 830 checks whether the current measurement values I ₁ , I ₂ ,...I _m each fall within a reference range (I _low to I _high ). And if at least one of the current measurement values I ₁ , I ₂ ,...I _m falls within the reference range (i.e., I _low ≤ I ₁ or I ₂ or ...I _m ≤ I _high ), there is no foreign substance. Judge. On the other hand, if the current measurements I ₁ , I ₂ ,...I _m are not all within the reference range (i.e., I ₁ and I ₂ and ...I _m > I _high or I ₁ and I ₂ and ... I _m <I _low ) It is judged that a foreign substance has been detected.

As another example, the control unit 940 compares the current measurement value I _SELECTED and the reference current I _ref . And, if the current measurement value I _SELECTED exceeds the reference current I _ref (ie, I _SELECTED > I _ref ), it is determined that a foreign substance has been detected. On the other hand, if the current measurement value I _SELECTED is less than or equal to the reference current I _ref (ie, I _SELECTED ≤ I _ref ), it is determined that there is no foreign material.

As another example, the control unit 940 checks whether the current measurement value I _SELECTED falls within a reference range (I _low ~ I _high ). And if the current measurement value I _SELECTED falls within the standard range (i.e., I _low ≤ I _SELECTED ≤ I _high ), it is determined that there is no foreign substance. On the other hand, if the current measurement value I _SELECTED does not fall within the standard range (i.e., I _SELECTED > I _high or I _SELECTED <I _low ), it is judged that a foreign object has been detected.

As another example, the control unit 940 compares the current measured value I _TOTAL to the reference current I _ref . And, if the current measurement value I _TOTAL exceeds the reference current I _ref (ie, I _TOTAL > I _ref ), it is determined that a foreign substance has been detected. On the other hand, if the current measured value I _TOTAL is less than or equal to the reference current I _ref (ie, I _TOTAL ≤ I _ref ), it is determined that there is no foreign matter.

As another example, the control unit 940 checks whether the current measurement value I _TOTAL falls within a reference range (I _low ~ I _high ). And if the current measurement value I _TOTAL falls within the standard range (i.e., I _low ≤ I _TOTAL ≤ I _high ), it is determined that there is no foreign matter. On the other hand, if the current measurement value I _TOTAL does not fall within the reference range (i.e., I _TOTAL > I _high or I _TOTAL <I _low ), it is judged that a foreign material has been detected.

The control unit 940 may attempt to detect a foreign matter at a time t predetermined by a system or standard.

As an example, a time point t at which the control unit 940 attempts to detect a foreign matter may be after every power control time point. For example, after the wireless power transmitter 900 receives a power up request message or a power down request message from the wireless power receiver and raises or lowers the AC signal, the current flowing through the primary core block 910 is measured. You can try to detect foreign objects using the value.

As another example, the time point t at which the control unit 940 attempts to detect a foreign object may be a predetermined detection period. For example, the detection period should be at least shorter than the time it takes for the foreign material to heat up above a certain temperature. This is because if the heat generation of foreign substances becomes severe, it may cause serious problems in safety due to fire and body burns. Therefore, it is preferable that the detection period is set to a value whose stability has been verified by an experiment, thereby preventing various dangers that may occur during charging, such as heat generated by foreign substances during wireless charging.

When a foreign substance is detected, the control unit 940 controls the electric drive unit 930 to not apply an AC signal to the primary core block 910 to block the transmission of wireless power.

The wireless power transmitter 110 of FIG. 1 may be the wireless power transmitter 800 of FIG. 8 or the wireless power transmitter 900 of FIG. 9.

According to the present invention, signaling overhead can be reduced because the wireless power receiver does not need to transmit specific information to the wireless power transmitter based on a promised information delivery standard for foreign matter detection.

It is a very important technical issue to detect foreign substances with minimal delay before heat generation of foreign substances. This is because if heat is easily generated due to the nature of the foreign material, the delay until detection of the foreign material is prolonged can cause a serious problem. However, according to the present invention, since the wireless power transmitter can detect foreign matters by itself, a delay for detecting foreign matters, for example, the time when the wireless power receiver generates specific information, the specific information transmits wireless power There is an effect that the time transmitted to the device and the time for the wireless power transmission device to decode and interpret the specific information are unnecessary.

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

10 is a block diagram showing a wireless power receiver according to an example of the present invention.

Referring to FIG. 10, the wireless power receiver 1000 includes a secondary coil 1010, a rectifying unit 1020, and a control unit 1030.

The rectifying unit 1020 provides full-wave rectification for the AC waveform generated in the secondary coil 1010. For example, the rectification unit 1020 may use four diodes in a full frridge configuration. In addition, the rectifying unit 1020 may provide power to the control unit 1030 and the external load 1040.

The control unit 1030 receives power from the rectification unit 1020 and performs operations such as packet generation and transmission in each phase, and wireless power transmission control. As an example, a load modulation technique may be used for packet transmission. In this case, a packet is transmitted through the secondary coil 1010, and the same frequency band as the frequency band for wireless power transmission is used. As another example, a separate frequency band different from the frequency band for wireless power transmission is used for packet transmission, and the packet is transmitted through techniques such as radio frequency identification (RFID) or Bluetooth or NFC (near field communication). Can be transmitted.

In the ID identification and configuration phase, the control unit 1030 generates an identification packet indicating a unique ID of the wireless power receiver 1000 and configuration information of the wireless power receiver 1000, and generates the identification packet and configuration information. Transmit to wireless power transmission device.

In addition, the control unit 1030 may measure an initial voltage V _i of an output terminal connected to an external load. The initial voltage V _i is a voltage measured by the control unit 1030 before the power transmission phase for receiving wireless power after completing the ID identification and configuration phase. Alternatively, the initial voltage V _i may be defined as the voltage of the output terminal in the standby state before the wireless charging starts.

When the normal state value of the initial voltage V _i exists within the reference voltage range (for example, 7.0V to 10.5V), the control unit 1030 enters the foreign matter detection phase, and the foreign object state packet for foreign matter detection. status packet) and transmits it to the wireless power transmission device. The foreign matter status packet is used to initiate or trigger foreign matter detection in the wireless power transmission device.

In the power transmission phase, the control unit 1030 measures power received through the secondary coil 1010, generates a power control packet, and transmits the power control packet to the wireless power transmitter. That is, the control unit 1030 may receive the requested power by using a packet required for wireless power transmission control.

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

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

Claims (13)

In the method of detecting foreign substances in a wireless power receiver,
Performing a foreign object detection operation before initial charging;
If a foreign material is not detected until charging is started, performing a foreign material detection operation during charging using one-way communication or two-way communication; And
When a foreign material is not detected in the foreign material detection operation during the charging, comprising the step of sensing a fine foreign material that has not been detected with a temperature sensor to limit power,
Foreign matter detection operation before the initial charging
Measuring an initial voltage of an output terminal connected to an external load; And
When the initial voltage is in the hold state and the normal state value of the initial voltage is within a predetermined reference voltage range, entering a foreign matter detection phase, generating a foreign matter state packet, and transmitting it to a wireless power transmission device. Way. The method of claim 1, wherein the operation of detecting foreign substances during charging using the one-way communication comprises:
A method comprising the step of receiving wireless power from a wireless power transmitter that generates an induced magnetic field or resonance by applying power to the primary coil in a charging mode when no foreign matter is detected by the wireless power transmitter. The method of claim 1, wherein the operation of detecting foreign substances during charging using the bidirectional communication comprises:
Receiving a transmission power measurement report indicating the measured transmission power from the wireless power transmission device generating an induced magnetic field or resonance by applying power to the primary coil in a charging mode;
Detecting a foreign matter based on a difference value between the measured transmission power and the measured reception power value; And
And transmitting an ASK signal including a result of detecting the foreign matter to the wireless power transmitter. The method of claim 3, wherein the transmission power measurement report is transmitted as an FSK signal transmitted using an FSK method,
The FSK signal includes a transmission power amount obtained by measuring power generated in the primary coil according to an AC current signal. The method of claim 4,
The FSK signal is repeatedly transmitted every predetermined period,
Wherein the predetermined period is a period in which a predetermined number of data signals are transmitted. The method of claim 4,
The FSK signal is a signal for transmitting 0 or 1 by switching or selecting a variable frequency in a predetermined range for converting a required fixed power frequency. The method of claim 3,
The ASK signal includes requested power information, which is information that requests the wireless power transmitter to generate wireless power based on a magnetic induction method. As a wireless power receiver that detects foreign matter,
A secondary core block for receiving wireless power from the wireless power transmitter by combining the primary core block provided in the wireless power transmitter by magnetic induction or magnetic resonance;
A rectifying unit connected to the secondary core block and providing power to a control unit and an external load by performing full-wave rectification on an AC waveform generated in the secondary core block; And
And a control unit that measures an initial voltage of an output terminal connected to the external load, and controls the wireless power receiver to enter a foreign matter detection phase when the initial voltage is in a reference voltage range,
The control unit
A foreign material detection operation is performed before initial charging, or a foreign material detection operation is performed during charging using one-way communication or two-way communication when a foreign material is not detected until charging starts, or a foreign material is not detected in the foreign material detection operation during charging. If not, the power is limited by detecting a fine foreign object that cannot be detected with a temperature sensor.
Foreign matter detection operation before the initial charging
Measuring the initial voltage of the output terminal connected to the external load; And
When the initial voltage is in the hold state and the value of the normal state of the initial voltage is within a predetermined reference voltage range, entering a foreign matter detection phase, generating a foreign matter state packet, and transmitting it to a wireless power transmission device, Wireless power receiver. The method of claim 8, wherein the control unit
In the charging mode, a transmission power measurement report indicating the measured transmission power is received from the wireless power transmitter that generates an induced magnetic field or resonance by applying power to the primary coil, and the measured transmission power and the measured reception power A wireless power receiver that detects a foreign substance based on a difference value of values, and performs a foreign substance detection operation during charging using the two-way communication by controlling to transmit an ASK signal including the foreign substance detection result to the wireless power transmitter . The method of claim 9, wherein the transmission power measurement report is transmitted as an FSK signal transmitted using an FSK method,
The FSK signal includes a transmission power amount obtained by measuring power generated by the primary coil according to an AC current signal. The method of claim 10,
The FSK signal is repeatedly transmitted every predetermined period,
The predetermined period is a period in which a predetermined number of data signals are transmitted. The method of claim 10,
The FSK signal is a signal for transmitting 0 or 1 by switching or selecting a variable frequency in a predetermined range for converting a required fixed power frequency. The method of claim 9,
The ASK signal includes requested power information, which is information that requests the wireless power transmitter to generate wireless power based on a magnetic induction method.

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