KR20130096210A - Apparatus for transmitting wireless power, apparatus for receiving wireless power, system for transmitting wireless power and method for transmitting wireless power - Google Patents

Abstract

PURPOSE: A wireless power transmitting device, a wireless power receiving device, a wireless power transmitting system, and a wireless power transmitting method easily grasp information by varying output impedance. CONSTITUTION: A transmitting unit (210) receives power from a power source. The transmitting unit transmits the power to a wireless power receiving device. A detecting unit (220) measures input impedance of a wireless power transmitting device. The detecting unit detects a change in output impedance of the wireless power receiving device. The detecting unit receives information from the wireless power transmitting device. [Reference numerals] (220) Detecting unit; (230) Determination unit; (240) Power control unit; (330) Driving control unit

Description

WIRELESS POWER AND METHOD FOR TRANSMITTING WIRELESS POWER}

The present invention relates to a wireless power transmitter, a wireless power receiver, a wireless power transmission system and a wireless power transmission method.

In the 1800s, electric motors and transformers using electromagnetic induction principles began to be used, and then radio waves and lasers were used to transmit the electric energy to the desired devices wirelessly. A method of transmitting electrical energy by radiating the same electromagnetic wave has also been attempted. Our electric toothbrushes and some wireless shavers are actually charged with electromagnetic induction. To date, energy transmission methods using wireless methods include magnetic induction, magnetic resonance, and long-distance transmission technology using short wavelength radio frequencies.

In recent years, among such wireless power transmission techniques, energy transmission using self resonance is widely used.

In the wireless power transmission system using self-resonance, since the electric signals formed on the transmission side and the reception side are wirelessly transmitted through the coil, the user can easily charge electronic devices such as portable devices.

Also, the wireless power transmitter may perform power transmission by receiving state information of the wireless power receiver. Since a separate communication channel or means for transmitting data from the wireless power receiver to the wireless power transmitter is expensive, a load modulation method is used. Load modulation is a method of recognizing that the input impedance of the wireless power transmitter is changed by changing the load (impedance) of the wireless power receiver.

However, the existing load modulation method is limited to a magnetic induction wireless power transmission system.

As a related prior patent document there is Republic of Korea Patent Publication No. 10-2008-0095642.

An object of the present invention is to provide a magnetic resonance-based wireless power transmitter, a wireless power receiver, a wireless power transmission system, and a wireless power transmission method capable of detecting the phase of the input impedance to know information of the wireless power receiver.

The wireless power transmitter for wirelessly transmitting power to a wireless power receiver according to an embodiment of the present invention includes a transmitter and a wireless power transmitter for transmitting power supplied from a power source to the wireless power receiver using resonance. And a detector configured to measure an input impedance and detect a change in output impedance of the wireless power receiver using the measured input impedance.

In accordance with still another aspect of the present invention, there is provided a wireless power receiver that wirelessly receives power from a wireless power transmitter. And a receiver configured to receive the power adjusted based on the variable information of the output impedance from the wireless power transmitter using resonance.

According to another aspect of the present invention, there is provided a power transmission method of a wireless power transmission system, the method comprising: varying an output impedance of a wireless power receiver; Detecting a change in the output impedance based on the detected input impedance.

According to an embodiment of the present invention, the information of the wireless power receiver may be grasped through the phase of the input impedance that is changed by varying the output impedance.

Meanwhile, various other effects will be directly or implicitly disclosed in the detailed description according to the embodiment of the present invention to be described later.

1 is a block diagram of a self-resonant wireless power transmission system 1000 according to an embodiment of the present invention.
2 illustrates a case where the switch SW of the impedance varying part 320 is opened according to an exemplary embodiment.
3 illustrates a case where the switch SW of the impedance varying part 320 is short-circuited according to an exemplary embodiment.
4 is a flowchart illustrating a wireless power transmission method of a wireless power transmission system according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be easily understood by those skilled in the art.

1 is a block diagram of a self-resonant wireless power transmission system 100 according to an embodiment of the present invention.

Referring to FIG. 1, the wireless power transmission system 1000 may include a power source 100, a wireless power transmitter 200, a wireless power receiver 300, and a load stage 400.

The wireless power transmitter 200 may include a transmitter 210, a detector 220, a determiner 230, and a power adjuster 240.

The transmission unit 210 may include a transmission inductive coil part 211 and a transmission resonant coil part 212.

The wireless power receiver 300 includes a receiver 310, an impedance variable unit 320, and a driving controller 330.

The receiver 310 includes a reception resonance coil unit 311, a reception induction coil unit 312, and an impedance variable unit 320. The power generated by the power source 100 is transmitted to the wireless power transmitter 200, and is transmitted to the wireless power receiver 300 which is in resonance with the wireless power transmitter 200 by a magnetic resonance phenomenon. Power delivered to the wireless power receiver 300 is delivered to the load stage 400 via a rectifier circuit (not shown). The load stage 400 may refer to any device requiring a rechargeable battery or other power, and in the embodiment of the present invention, the load resistance is represented by RL. In one embodiment, the load stage 400 may be included in the wireless power receiver 300.

More specifically, the power source 100 is an AC power source that provides AC power of a predetermined frequency.

The wireless power transmitter 200 includes a transmission induction coil unit 211 and a transmission resonance coil unit 212. The transmission induction coil unit 211 is connected to the power source 100, and the AC current flows. When an alternating current flows through the transmission induction coil unit 211, an alternating current is also induced in the transmission resonance coil unit 212 which is physically spaced by electromagnetic induction. The power transmitted to the transmitting resonance coil part 212 is transmitted to the wireless power receiving apparatus 300 which forms a resonant circuit with the wireless power transmitting apparatus 200 by self resonance.

Power can be transmitted by self resonance between two LC circuits whose impedance is matched. Such power transmission by self-resonance enables power transmission to a higher efficiency, farther than the power transmission by electromagnetic induction.

The transmission induction coil unit 211 includes a transmission induction coil L1 and a capacitor C1. Here, the capacitance of the capacitor C1 may be a fixed value.

One end of the capacitor C1 is connected to one end of the power source 100, and the other end of the capacitor C1 is connected to one end of the transmission induction coil L1. The other end of the transmission induction coil L1 is connected to the other end of the power source 100.

The transmission resonant coil unit 212 includes a transmission resonant coil L2, a capacitor C2, and a resistor R2. The transmission resonant coil L2 includes one end connected to one end of the capacitor C2 and the other end connected to one end of the resistor R2. The other end of the resistor R2 is connected to the other end of the capacitor C2. The resistance R2 represents the amount generated by the power loss in the transmission resonance coil L2 as a resistance.

The detector 220 may detect a first input impedance Z1, which is an impedance when the power source 100 faces the wireless power transmitter 200.

The detector 220 may detect a phase of the first input impedance Z1 through the detected first input impedance Z1. The phase of the first input impedance Z1 refers to a phase difference between an input voltage and an input current output from the power source 100.

The detector 220 detects a change in the output impedance ZL by the impedance varying unit 320 of the wireless power receiver 300 to be described later using the detected phase difference.

The detector 220 may detect a phase of 0 degrees or 90 degrees according to the operation of the impedance varying unit 320 to be described later.

The phase detection of the detector 220 may determine the state of the wireless power receiver 300, specifically, the open or shorted state of the switch SW of the impedance varying unit 320 to be described later.

The determination unit 230 determines state information of the wireless power receiver 300 according to the detected first input impedance. In an embodiment, the state information of the wireless power receiver 300 may be information about a current charge amount or a change of the charge amount of the wireless power receiver 300. In addition, the wireless power receiver 300 may be information indicating that the charging is completed.

The power controller 240 adjusts the power delivered to the wireless power receiver 300 according to the determined state information of the wireless power receiver 300. The power adjuster 240 controls the power source 100 to adjust the power delivered to the wireless power transmitter 200, and accordingly adjusts the power delivered to the wireless power receiver 300.

As a result, the phase detection process may mean a process in which the wireless power transmitter 200 determines the state of the wireless power receiver 300. That is, the wireless power receiver 300 transmits its own state information to the wireless power transmitter 200, and the wireless power transmitter 200 receives appropriate power according to the received state information of the wireless power receiver 300. Send it.

The wireless power transmitter 200 may obtain information on the current charging amount of the wireless power receiver 300 through phase detection of the first input impedance Z1 and perform power transmission corresponding thereto.

The wireless power receiver 300 includes a receiver 310 and an impedance variable unit 320.

The receiver 310 includes a reception resonance coil unit 311 and a reception induction coil unit 312.

The reception resonance coil portion 311 includes a reception resonance coil L3, a capacitor C3, and a resistor R3. The reception resonance coil L3 includes one end connected to one end of the capacitor C3 and the other end connected to one end of the resistor R3. The other end of the resistor R3 is connected to the other end of the capacitor C2. The resistor R3 is a resistor that represents the amount of power loss occurring in the receiving resonant coil L3.

The reception induction coil unit 312 includes a reception induction coil L4 having both ends connected to both ends of the impedance variable unit 320, respectively. The receiving induction coil L4 may further include a capacitor (not shown), forming a circuit having appropriate inductance and capacitance values.

The reception resonance coil portion 311 maintains the self resonance state at the resonance frequency with the transmission resonance coil portion 212. [ That is, the reception resonant coil unit 311 is coupled to the transmission resonant coil unit 212 so that an alternating current flows, and the electric power is supplied to the wireless power receiver 300 in a non-radiative manner. I can deliver it.

The reception induction coil unit 312 receives power from the reception resonant coil unit 311 by electromagnetic induction, and the power received by the reception induction coil unit 312 is rectified through a rectifier circuit (not shown) so that the load stage ( 400).

The impedance variable part 320 may include a switch SW and a capacitor C4. The switch SW includes one end connected to one end of the capacitor C4 and the other end connected to the other end of the load terminal 400. One end of the load end 400 is connected to the other end of the capacitor (C4).

The impedance variable part 320 may vary the output impedance ZL viewed from the receiving induction coil L4 to the load terminal 400. The impedance variable part 320 varies the output impedance ZL through the switch SW, thereby changing the first input impedance Z1.

Hereinafter, a process of changing the first input impedance Z1 by the impedance variable part 320 will be described.

The third input impedance Z3 and the second input impedance Z2 to be described later may be detected by further adding a detector (not shown) to the wireless power receiver 300.

The third input impedance Z3 may refer to an impedance measured when the load resonant coil L3 is viewed from the load terminal 400, and may be expressed as Equation 1 below.

[Equation 1]

Here, w is a resonant frequency when resonating between the transmission resonant coil L2 and the reception resonant coil L3, and M3 means mutual inductance between the reception resonant coil L3 and the reception coil L4. Also, ZL means the output impedance. Equation 1 is an expression based on the frequency domain, and the following equations are also based on the frequency domain.

The second input impedance Z2 means an impedance measured when the wireless power transmission apparatus 200 looks at the wireless power reception apparatus 300 and can be expressed as Equation (2).

&Quot; (2) "

Here, M2 means mutual inductance between the transmission resonant coil L2 and the reception resonant coil L3, and C3 means a capacitor expressed when the reception resonant coil unit 311 is converted into an equivalent circuit. Further, R3 represents a resistance generated by a loss in the reception resonance coil L3.

The capacitor C3 and the leakage resistance R3 may be fixed values, but the mutual inductance M2 may be changed according to the coupling coefficient K2 between the transmission resonance coil L2 and the reception resonance coil L3.

The coupling coefficient K2 indicates the degree of electromagnetic coupling between the transmitting resonant coil L2 and the receiving resonant coil L3. The coupling coefficient K2 represents the degree of electromagnetic coupling between the transmitting resonant coil L2 and the receiving resonant coil L3. And the position, distance, direction, and position between the first and second electrodes 300.

The first input impedance Z1 means an impedance measured when the power source 100 is viewed from the side of the wireless power transmission apparatus 200 and can be expressed as Equation (3).

&Quot; (3) "

Here, M1 denotes mutual inductance between the transmission induction coil L1 and the transmission resonance coil L2.

In Equations 1 to 3, R2 and R2 are assumed to have very small values and are set to 0 ohms, and the transmission induction coil L1 and the capacitor C1, the transmission resonance coil L2 and the capacitor ( C2), when the reception resonance coil L3 and the capacitor C3 are all determined to resonate at the resonance frequency w, the first input impedance Z1 can be summarized as shown in [Equation 4].

&Quot; (4) "

Equation (4) can be summarized as Equation (8) by using Equations (5) to (7), which is an expression showing the relationship between mutual inductance and each coupling coefficient.

&Quot; (5) "

&Quot; (6) "

[Equation 7]

[Equation 8]

Referring to Equation 8, the first input impedance Z1 may vary as the output impedance ZL is changed. This process will be described in detail with reference to FIGS.

The driving controller 330 controls the impedance variable part 320 by applying a control signal to the impedance variable part 320. The control signal may be a driving signal for opening or shorting the switch SW.

Next, the change in the output impedance ZL and the first input impedance Z1 according to the opening or shorting of the switch SW will be described with reference to FIGS. 2 to 3.

2 illustrates a case where the switch SW of the impedance varying part 320 is opened according to an exemplary embodiment.

When the switch SW is opened by the control signal of the driving controller 330, the impedance variable part 320 may be represented by the circuit of FIG. 2.

In this case, the output impedance ZL may be expressed as shown in [Equation 9].

&Quot; (9) "

When a value is set such that the reception induction coil L4 and the capacitor C4 resonate at the resonance frequency w, the first input impedance Z1 may be summarized as in Equation 10.

 &Quot; (10) "

In this case, only the real component exists in the first input impedance Z1. If the first input impedance Z1 has only a real component, it means that there is no phase difference between the input voltage and the input current input from the power source 100.

3 illustrates a case where the switch SW of the impedance varying part 320 is short-circuited according to an exemplary embodiment.

When the switch SW is shorted by the control signal of the driving controller 330, the impedance variable part 320 may be represented by the circuit of FIG. 3.

In this case, the output impedance ZL may be expressed as Equation 11 below.

&Quot; (11) "

If a value is set such that the reception induction coil L4 and the capacitor C4 resonate at the resonance frequency w, the first input impedance Z1 may be arranged as shown in Equation 12.

&Quot; (12) "

In this case, only the imaginary component of the first input impedance Z1 exists. The fact that the first input impedance Z1 has only an imaginary component means that a phase difference of 90 degrees occurs between an input voltage and an input current input from the power source 100.

As described above, by detecting the phase difference between the input voltage and the input current at the wireless power transmitter 200, the state of the wireless power receiver 300, that is, the open or shorted state of the switch SW can be known. . Accordingly, the wireless power transmitter 200 may determine the state of the wireless power receiver 300 to perform an appropriate power transmission process.

For example, when the wireless power receiver 300 intends to transmit digital data 1, the driving controller 330 short-circuits the switch SW and opens the switch SW when the digital data 0 is to be transmitted. Let's do it. The detector 220 may detect a phase of the first input impedance Z1 to confirm a short or open of the switch SW, and receive state information of the wireless power receiver 300. The wireless power transmitter 200 receives state information of the wireless power receiver 300 and performs appropriate power transmission.

4 is a flowchart illustrating a wireless power transmission method of a wireless power transmission system according to an embodiment of the present invention.

The configuration of the wireless power transmission system 1000 is as described in FIG.

First, the impedance varying unit 320 varies the output impedance (S101). The output impedance ZL refers to the impedance measured when the receiver 310 looks at the impedance variable part 320 with reference to the wireless power transmission system 1000 of FIG. 1. The impedance variable part 320 may include a switch SW and a capacitor C4, and may change an output impedance through the switch SW.

The detector 220 may detect a phase difference between the input voltage and the input current of the power source 100 according to the change of the output impedance (S103). Here, the phase difference may have a value of 0 degrees or 90 degrees. The detection of the phase difference may be detected through a first input impedance measured when the transmitter 210 is viewed from the power source 100, and the detailed detection process is the same as described with reference to FIGS. 2 to 3.

The detector 220 may detect a change in the output impedance based on the detected phase difference (S105).

Thereafter, the determination unit 230 may determine state information of the wireless power receiver 300 based on the detected output impedance change (S105).

Thereafter, the power controller 240 may control the power source 100 according to the state information of the wireless power receiver 300 to transmit power to the wireless power receiver 300 (S107).

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It should be understood that various modifications may be made by those skilled in the art without departing from the spirit and scope of the present invention.

1000: wireless power transmission system
100: Power source
200: Wireless power transmitting device
210:
220:
230:
240: power control unit
300: Wireless power receiving device
310:
320: impedance variable portion
400: load stage

Claims (8)

A wireless power transmitter for wirelessly transmitting power to a wireless power receiver,
A transmitter for transmitting the power supplied from the power source to the wireless power receiver using resonance; And
A detector configured to measure an input impedance of the wireless power transmitter and detect a change in output impedance of the wireless power receiver using the measured input impedance;
The detection unit
Detecting a change in the output impedance to receive information from the wireless power transmitter
Wireless power transmitter. The method of claim 1,
The detection unit
Detecting a phase difference between an input voltage and an input current of the wireless power transmitter using the measured input impedance, and detecting a change in output impedance of the wireless power receiver using the detected phase difference.
Wireless power transmitter. The method of claim 2,
The phase difference is
Containing one or more phases
Wireless power transmitter. 4. The method of claim 3, wherein the one or more phases are
Including at least one of zero or ninety degrees
Wireless power transmitter. The method of claim 2,
The apparatus may further include a state information determiner configured to determine state information of the wireless power receiver based on the detected phase difference.
Wireless power transmitter. The method of claim 5,
The apparatus may further include a power controller configured to control the power source according to the determined state information of the wireless power receiver to adjust power delivered to the wireless power receiver.
Wireless power transmitter. The method of claim 1,
The transmitting unit,
A transmission induction coil receiving power from the power source; And
And a transmission resonance coil configured to transfer power received from the transmission induction coil through electromagnetic induction to the wireless power receiver using resonance. The method of claim 1,
The information above
Includes state information of the wireless power receiver,
The state information of the wireless power receiver
It includes any one of the current charge amount information of the wireless power receiver and the information on the transition of the charge amount of the wireless power receiver
Wireless power transmitter.

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