KR101252282B1 - Apparatus and method for transmiting a wireless power - Google Patents

Abstract

The wireless power transmitter of the self-resonant wireless power transmission system outputs an output impedance of the transmission resonator at a resonance frequency of the transmission resonator according to a voltage reflected from the transmission resonator for transmitting power to the wireless power receiver through magnetic resonance. Match with.

Description

Wireless power transmission apparatus and method {APPARATUS AND METHOD FOR TRANSMITING A WIRELESS POWER}

The present invention relates to a wireless power transmission apparatus and method, and more particularly to a wireless power transmission apparatus and method of a self-resonant wireless power transmission system.

Recently, a wireless power transmission technology that can supply and charge a small multimedia device without a power line has been studied.

The magnetic resonant wireless power transmission system, which is one of wireless power transmission technologies, is based on a resonance coupling method in which electromagnetic waves move from a transmitter to a receiver through a magnetic field when the transmitter and the receiver resonate at the same frequency.

The self-resonant wireless power transmission system is more advanced than the inductive coupling method, and there is no limitation on the frequency band and is robust to the medium-range wireless power transmission. In addition, since the magnetic resonance wireless power transmission system uses magnetic resonance, it has a property that is harmless to the human body in theory.

In such a self-resonant wireless power transmission system, power consumption is determined according to power transmission efficiency. In addition, when the arrangement of the transmitter coil and the receiver coil of the transmitter is shifted, there is a problem in that the power transmission efficiency is lowered. Arrangement of the transmitting coil of the transmitter and the receiving coil of the receiver in a physically parallel state is not easy, and thus a decrease in power transmission efficiency may be inevitable. Therefore, a self-resonant wireless power transmission system is required a technology that can increase the power transmission efficiency in order to reduce the power consumption.

The technical problem to be solved by the present invention is to provide a wireless power transmission apparatus and method that can increase the power transmission efficiency.

According to an embodiment of the present invention, an apparatus for transmitting power wirelessly using magnetic resonance is provided. The wireless power transmitter includes a voltage controlled oscillator for generating a power signal to be transmitted wirelessly, a transmission resonator for transmitting the power signal to the wireless power receiver using a resonance coupling method with the wireless power receiver at a resonant frequency, and An impedance matching unit for controlling the output impedance of the transmission resonator according to the voltage reflected from the transmission resonator.

The wireless power transmitter further includes a controller for outputting a control signal corresponding to a difference between the voltage reflected from the transmission resonator and a reference voltage, wherein the impedance matching unit operates according to the control signal to output output impedance of the transmission resonator. Can be matched to the impedance at the resonance frequency of the transmission resonator.

The controller may include an operational amplifier configured to generate a control signal corresponding to a difference between the voltage reflected from the transmission resonator and the reference voltage.

The control unit may further include a variable gain amplifier for amplifying the control signal.

The control unit may further include a low pass filter for removing high frequency components from the control signal amplified by the variable gain amplifier.

The wireless power transmitter may further include a power amplifier amplifying the power signal and transmitting the amplified power signal to the transmission resonator.

The impedance matching unit includes at least one variable capacitor connected in series and in parallel between the power amplifier and the transmission resonator, wherein a value of the at least one variable capacitor is a value of the voltage reflected from the transmission resonator and the reference voltage. In response to the difference, the output impedance of the transmission resonator may be changed to match the impedance at the corresponding resonance frequency.

The controller may output the control signal to the power amplifier, and the power amplifier may change the amplification gain according to the voltage level of the control signal.

The power amplifier may include a first coupler for transmitting an input power signal to the transmission resonator, a driving power amplifier connected to the voltage controlled oscillator and amplifying the input power signal with a first gain, and a second input power signal. A main power amplifier amplified to a gain and output to the first coupler, and a control signal amplified to the first gain to the main power amplifier when the difference between the reflected voltage and the reference voltage is equal to or greater than a set voltage level, And a second coupler configured to transfer a control signal amplified to the first gain to the first coupler when the difference between the reflected voltage and the reference voltage is less than the set voltage level.

According to another embodiment of the present invention, a method for transmitting power in a wireless power transmission apparatus is provided. The wireless power transmission method may include generating a power signal to be transmitted wirelessly, transmitting the power signal to a wireless power receiver through a magnetic resonance in a transmission resonator having a natural frequency, and applying a voltage reflected from the transmission resonator. And measuring the output impedance of the transmission resonator according to the difference between the reflected voltage and the reference voltage.

According to an exemplary embodiment of the present invention, it is possible to compensate for a decrease in power transmission efficiency due to mechanical misalignment of a coil causing a resonance on a transmitting side and a coil generating a resonance on a receiving side in a self-resonant wireless power transmission system.

1 is a diagram illustrating a self-resonant wireless power transmission system according to an exemplary embodiment of the present invention.
FIG. 2 is a diagram illustrating the controller shown in FIG. 1.
3 is a flowchart illustrating a method of operating a wireless power transmitter according to an embodiment of the present invention.
4 is a diagram illustrating an impedance matching method in a control unit according to an exemplary embodiment of the present invention.
5 is a diagram illustrating a wireless power transmitter according to a second embodiment of the present invention.
FIG. 6 is a diagram illustrating the power amplifier shown in FIG. 5.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification and claims, when a section is referred to as "including " an element, it is understood that it does not exclude other elements, but may include other elements, unless specifically stated otherwise.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between . When an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

Now, a wireless power transmission apparatus and method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

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

Referring to FIG. 1, a self-resonant wireless power transmission system includes a wireless power transmitter 100 and a wireless power receiver 200.

The wireless power transmitter 100 wirelessly transmits power to the wireless power receiver 200 through magnetic resonance. The wireless power receiver 200 may receive power from the wireless power transmitter 100 and supply the power to a device that consumes power. Here, the power consuming device may be, for example, a battery operated mobile communication terminal.

The wireless power transmitter 100 includes a power supply unit 110, a voltage controlled oscillator (VCO) 120, a power amplifier 130, an impedance matching unit 140, a transmission resonator 150, and a controller ( 160).

The power supply unit 110 converts an AC voltage input through an AC power source (not shown) into a DC voltage, and then supplies the VCO 120, the power amplifier 130, the impedance matching unit 140, and the controller 160. do. The VCO 120, the power amplifier 130, the impedance matching unit 140, and the controller 160 are driven by receiving a DC voltage from the power supply 110.

The VCO 120 receives a DC voltage from the power supply 110 to generate an AC power signal, for example, 10 MHz, and transmits the power signal to the power amplifier 130.

The power amplifier 130 amplifies the power signal generated by the VCO 120 and transmits the amplified power signal to the transmission resonator 150 through the impedance matching unit 140. The power amplifier 130 may include a driving power amplifier 131 that amplifies a power signal with a set gain (eg, 10-20 dB).

The impedance matching unit 140 matches the output impedance of the transmission resonance unit 150 to an impedance at a corresponding resonance frequency, for example, 50 ohm impedance under the control of the controller 160. Here, the output impedance of the transmission resonator 150 represents the impedance of the transmission resonator 150 as viewed by the power amplifier 130 from the rosin resonator 150.

The transmission resonator 150 may include at least one coil causing magnetic resonance. The transmission resonator 150 generates a magnetic resonance at a natural resonance frequency and transmits a power signal to the wireless power receiver 200. That is, the transmission resonator 150 generates a self-resonance at a natural resonant frequency to store a power signal, and then the reception resonator 210 of the wireless power receiver 200 may have a resonance frequency of the transmission resonator 150. When resonating at the same resonance frequency, the power signal stored in the resonance coupling method is transferred to the reception resonator 210 of the wireless power receiver 200.

In the apparatus 100 for transmitting power wirelessly, the transmission resonator 150 and the reception resonator 210 have a maximum power transmission efficiency in a state in which the transmission resonator 150 is mechanically arranged in parallel. In other words, if the transmission resonator 150 and the reception resonator 210 are not arranged in parallel, the degree of deterioration in power transmission efficiency is increased. This is equivalent to an impedance mismatch at the inherent resonance frequency of the transmission resonator 150. Impedance mismatch at the resonant frequency of the transmission resonator 150 causes an increase in the reflection coefficient, and since the transmission resonator 150 reflects the power signal in proportion to the reflection coefficient, power transmission efficiency is lowered.

The control unit 160 measures the voltage of the power reflected from the transmission resonator 150 (hereinafter referred to as “reflection voltage”), and controls the impedance matching unit 140 according to the reflected voltage to transmit transmission resonator 150. By minimizing the reflection coefficient to a value close to zero, the output impedance of is matched to the impedance at its natural resonance frequency. When the reflection coefficient is 0, this may mean that the power transmission efficiency is maximized.

The wireless power receiver 200 includes a reception resonator 210, a rectifier 220, and a load 230.

The reception resonator 210 may include at least one coil causing magnetic resonance. The reception resonator 210 generates a magnetic resonance at the same resonance frequency as the transmission resonator 150 to receive a power signal from the transmission resonator 150, and transmits the received power signal to the rectifier 220.

The rectifier 220 rectifies the power signal and supplies the rectified power signal to the load 230. Here, the load 230 may be installed outside the wireless power receiver 200 unlike FIG. 1.

FIG. 2 is a diagram illustrating the controller shown in FIG. 1.

2, the controller 160 includes an AC / DC converter 161, an operational amplifier 162, a variable gain amplifier 163, and a filter 164.

The AC / DC converter 161 measures the reflected voltage of the alternating current, converts the reflected voltage of the alternating current into direct current, and transfers the reflected voltage to the non-inverting terminal (+) of the operational amplifier 162.

The operational amplifier 162 is a non-inverting terminal (+) connected to the AC / DC converter 161 and an inverting terminal (-) to which the reference voltage Vref is input and an output terminal connected to the variable gain amplifier 160. It includes.

The operational amplifier 162 outputs a difference between the reflected voltage input to the non-inverting terminal (+) and the reference voltage Vref input to the inverting terminal (−) through the output terminal. In this case, the operational amplifier 162 may amplify and output a difference between the voltage input to the non-inverting terminal (+) and the reference voltage Vref input to the inverting terminal (−).

Here, the reference voltage Vref may be set to an arbitrary value according to the application environment of the self-resonant wireless power transmission system or other reference.

The variable gain amplifier 163 amplifies the output voltage from the operational amplifier 162 and outputs it to the filter 164.

The filter 164 is, for example, a low pass filter. The filter 164 removes a high frequency component from an output signal of the variable gain amplifier 163 and outputs the high frequency component to the impedance matching unit 140. Then, the impedance matching unit 140 matches the output impedance of the transmission resonance unit 150 to the impedance at the corresponding resonance frequency according to the voltage level of the output signal of the filter 164. As such, when the output impedance of the transmission resonator 150 is matched to the impedance at the resonance frequency, the reflection coefficient becomes 0 and the reflected power is lost. Therefore, the transmission resonator 150 and the reception resonator 210 The degradation in power transfer efficiency due to mechanical misalignment can be compensated.

3 is a flowchart illustrating a method of operating a wireless power transmitter according to an exemplary embodiment of the present invention, and FIG. 4 is a diagram illustrating an impedance matching method in a controller according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the power supply unit 110 of the apparatus 100 for transmitting power wirelessly may include a VCO 120, a power amplifier 130, an impedance matching unit 140, a transmission resonator 150, and a controller 160. Supply DC voltage.

The VCO 120 generates a power signal (S310), the power signal is amplified through the power amplifier 130 (S320), and the amplified power signal is a magnetic field of the transmission resonator 150 and the reception resonator 210. The transmission resonator 150 is transmitted from the transmission resonator 150 to the reception resonator 210 through a resonance coupling method by resonance (S330). In this case, power transmission efficiency may be reflected by the transmission resonator 150 and the transmission resonator 150 and the reception resonator 210 due to a mechanical arrangement mismatch or other factors, such that the power signal may be reflected.

Referring to FIG. 4, the controller 160 monitors the power reflected by the transmission resonator 150 by measuring the reflected voltage at the transmission resonator 150 (S410).

The controller 160 outputs a difference between the reflected voltage and the reference voltage Vref (S420).

The impedance matching unit 140 matches the output impedance of the transmission resonance unit 150 with the impedance at the corresponding resonance frequency according to the difference between the reflected voltage and the reference voltage Vref (S430). Here, various methods may be used as a method of matching the output impedance of the transmission resonance unit 150 with the impedance at the corresponding resonance frequency. For example, the impedance matching unit 140 may include a plurality of variable capacitors (not shown) connected in series and in parallel between the power amplifier 130 and the transmission resonator unit 150. In response to the difference between the reflected voltage and the reference voltage Vref, the output impedance of the transmission resonator 150 is changed to match the impedance at the corresponding resonance frequency. Therefore, since the value of the variable capacitor is changed according to the difference between the reflected voltage and the reference voltage Vref, the output impedance of the transmission resonator 150 may be matched to the impedance at the corresponding resonance frequency.

The reflection coefficient of the transmission resonator 150 is also affected by the distance between the transmission resonator 150 and the reception resonator. As the distance between the transmission resonator 150 and the reception resonator 210 increases, a reflection coefficient may increase, thereby further deteriorating power transmission efficiency. However, there is a limit in compensating for the power transmission efficiency lowered by the impedance matching by the impedance matching unit 140.

FIG. 5 is a diagram illustrating an apparatus for transmitting power wirelessly according to a second embodiment of the present invention, and FIG. 6 is a diagram illustrating the power amplifier illustrated in FIG. 5.

Referring to FIG. 5, the controller 160 ′ of the wireless power transmitter 100 ′ controls not only the impedance matching unit 140 but also the power amplifier 130 ′ according to the power reflected from the transmission resonator 150. .

The power amplifier 130 'amplifies the power signal by varying the degree of amplification gain under the control of the controller 160'.

Referring to FIG. 6, the power amplifier 130 ′ includes a driving power amplifier 131, a main power amplifier 132, and couplers 133 and 134.

The driving power amplifier 131 amplifies the power signal with a set gain.

The coupler 133 switches to the main power amplifier 132 or the coupler 134 according to the difference between the reflected voltage and the reference voltage Vref to convert the power signal amplified by the driving power amplifier 131 into the main power amplifier 132. Or to a coupler 134.

The main power amplifier 132 amplifies the input power signal with a set gain (for example, 30 to 40 dB) and transfers the power signal to the coupler 134. Here, the input power signal is a power signal amplified by the driving power amplifier 131, and the gains of the driving power amplifier 131 and the main power amplifier 132 may be the same or different.

The coupler 134 transfers the power signal amplified by the driving power amplifier 131 or the power signal amplified by the main power amplifier 132 to the impedance matching unit 140.

The coupler 133 is basically connected to the coupler 134, and operates when the difference between the reflected voltage and the reference voltage Vref is higher than or equal to a predetermined level to switch to the main power amplifier 132. That is, when the difference between the reflected voltage and the reference voltage Vref is higher than or equal to a predetermined level, the power signal of the VCO 120 is amplified by the sum of the gain of the driving power amplifier 131 and the gain of the main power amplifier 132, thereby transmitting resonance. It is delivered to the unit 150. On the other hand, when the difference between the reflected voltage and the reference voltage (Vref) is less than a predetermined level, the power signal of the VCO 120 is amplified only by the gain of the driving power amplifier 131 is transmitted to the transmission resonator 150.

As such, when the difference between the reflected voltage and the reference voltage Vref is equal to or higher than a predetermined level, the power signal is raised to the maximum in front of the transmission resonator 150 to thereby limit the compensation of the power transfer efficiency by the impedance matching unit 140. It will be able to complement.

An embodiment of the present invention is not implemented only through the above-described apparatus and / or method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded. Such an implementation can be easily implemented by those skilled in the art to which the present invention pertains based on the description of the above-described embodiments.

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, It belongs to the scope of right.

Claims (13)

In an apparatus for transmitting power wirelessly using magnetic resonance,
A voltage controlled oscillator for generating a power signal for transmission wirelessly,
A power amplifier for amplifying the power signal,
A transmission resonator for transmitting the power signal amplified by the power amplifier to the wireless power receiver by using a resonance coupling method with the wireless power receiver at a resonant frequency; and
An impedance matching unit for controlling the output impedance of the transmission resonator according to the voltage reflected from the transmission resonator,
The power amplifier,
A first coupler transferring an input power signal to the transmission resonator;
A driving power amplifier connected to the voltage controlled oscillator and amplifying the input power signal with a first gain;
A main power amplifier amplifying the input power signal with a second gain and outputting the amplified power signal to the first coupler, and
When the difference between the reflected voltage and the reference voltage is equal to or greater than the set voltage level, the control signal amplified by the first gain is transmitted to the main power amplifier, and when the difference between the reflected voltage and the reference voltage is less than the set voltage level. And a second coupler for transmitting the control signal amplified to the first gain to the first coupler. In claim 1,
A controller for outputting a control signal corresponding to the difference between the voltage reflected from the transmission resonator and a reference voltage
More,
And the impedance matching section is operated in accordance with the control signal to match the output impedance of the transmission resonator to an impedance at the resonance frequency of the transmission resonator. In claim 2,
The control unit,
And an operational amplifier configured to generate a control signal corresponding to the difference between the voltage reflected from the transmission resonator and the reference voltage. 4. The method of claim 3,
The control unit,
And a variable gain amplifier for amplifying the control signal. 5. The method of claim 4,
The control unit,
And a low pass filter for removing high frequency components from the control signal amplified by the variable gain amplifier. delete In claim 2,
The impedance matching unit includes at least one variable capacitor connected in series and in parallel between the power amplifier and the transmission resonator,
And the value of the at least one variable capacitor is changed so that the output impedance of the transmission resonator is matched to the impedance at a corresponding resonance frequency in response to a difference between the voltage reflected from the transmission resonator and the reference voltage. delete delete delete delete delete delete

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