KR101286585B1 - Wireless power transmitting system using frequency splitting and method thereof - Google Patents

Abstract

Disclosed are a wireless power transmission system and method using frequency splitting characteristics. The wireless power transmission system using the frequency splitting characteristic includes a transmitting device for performing wireless power transmission to a receiving system using a predetermined frequency and a controller capable of controlling a frequency used by the transmitting device. When frequency splitting occurs, the controller tracks a frequency to be used by the transmitter by using a splitting frequency calculated based on a natural resonance frequency, and supplies power to a determined frequency determined as a result of the tracking. The transmitting device can be controlled to transmit.

Description

Wireless power transmission system using frequency splitting characteristics and its method {Wireless power transmitting system using frequency splitting and method

The present invention relates to a wireless power transmission system and method using frequency splitting characteristics, and more particularly, in the magnetic resonance power transmission, when the distance between the transmission system and the receiving system is close, the transmission efficiency at the resonant frequency is lowered and other frequencies A frequency splitting phenomenon occurs in which the maximum efficiency occurs in the wireless power transmission system that can have excellent transmission efficiency by tracking a frequency having a high transmission efficiency even in this frequency splitting phenomenon. And to a method thereof.

In modern society, wireless communication is used in many fields. However, power supply of electronic devices is still mainly used for wired power transmission using power lines.

For example, when a wall-mounted TV is to be attached to a wall, it is preferable to embed an aesthetic power line into the wall, but there may be a problem in that the building itself may be deformed and construction cost may be high. In addition, various devices (eg, rice cookers, microwave ovens, electric ovens, coffee pots, etc.) are safe to connect the power line only when the device is operated, but the power supply (eg, multi-tap) There was an inconvenience to turn off and on) or to plug in and unplug the power cord from the outlet. In addition, this inconvenience causes standby power consumption problems when the devices are continuously connected to a power source.

In addition, in order to build a high-end multimedia environment, in addition to wall-mounted TVs, 5.1 channel speakers, etc., or numerous power lines need to be connected to a power strip for the operation of a computer and numerous peripheral devices. Risk of fire due to Therefore, the importance of wireless power transmission technology is increasing.

Wireless power transmission methods include magnetic induction power transmission and magnetic resonance power transmission methods. The self-induction power transmission method has a high transmission efficiency but has a problem that the efficiency decreases rapidly with distance due to the charging distance close to the contact.

Magnetic resonance power transmission is mainly used for relatively long distances (eg, a few meters), and no specific studies have been conducted on the close distances.

However, although power transmission over a relatively long distance is important, it may be necessary to perform power transmission at a close distance using the same system if necessary. Since the magnetic induction power transmission method is not efficient at a long distance, it may be necessary to use the magnetic resonance power transmission method to perform the power transmission regardless of the distance.

Magnetic resonance power transmission can be seen that the frequency splitting phenomenon is less efficient at close range. Such frequency splitting characteristics have been disclosed in "Waves and Fields in optoelectronics", Prentice-Hall, 1983. and "Wirelss power transfer via strongly coupled magnetic resonances", science, 2007.
These frequency splitting characteristics are physically unavoidable, and studies to date have been verifying performance over a long distance to avoid this problem.

Therefore, there is a need for a system and method capable of guaranteeing a certain level of transmission efficiency even if transmission efficiency is reduced due to frequency splitting occurring in a close distance in a magnetic resonance power transmission method.

1) "Waves and Fields in optoelectronics", Prentice-Hall, 1983. 2) "Wirelss power transfer via strongly coupled magnetic resonances", science, 2007

Therefore, the technical problem to be achieved by the present invention is that when the magnetic resonance power transmission, the frequency is split at both frequencies centered around the natural resonance frequency, the transmission efficiency is lowered at the natural resonance frequency and the maximum efficiency appears rather at close distance. The phenomenon occurs, and to provide a system and method that can compensate for the transmission efficiency degradation due to such frequency splitting.

The wireless power transmission system using a frequency splitting characteristic for solving the technical problem is capable of controlling a transmitting device for performing wireless power transmission to a receiving system using a predetermined frequency and the frequency used by the transmitting device. And a controller, when the frequency splitting occurs, tracking the frequency to be used by the transmitting apparatus by using the splitting frequency calculated based on the natural resonance frequency, and tracking result. The transmitter may be controlled to transmit power at the determined determination frequency.

The controller may control the transmitter to transmit power at a natural resonance frequency, and then control the transmitter to transmit power at the determined frequency when frequency splitting occurs.

The controller may receive information about a coupling coefficient from the receiving system and calculate the splitting frequency based on the received information and the natural resonance frequency.

The controller controls the transmitting device to transmit power to the receiving system by using the calculated splitting frequency, and changes the frequency by a predetermined first unit while transmitting efficiency between the frequency before the change and the frequency after the change. The process of selecting a better frequency can be performed at least once.

The controller may select a frequency having a better transmission efficiency between the frequency before the change and the frequency after the change based on predetermined control information received from the receiving system.

When the controller determines the frequency having the maximum transmission efficiency while tracking by using the first unit, the controller changes the frequency by a second unit having a value smaller than the first unit to track the determined frequency. Can be.

The wireless power transmission system using a frequency splitting characteristic for solving the technical problem is capable of controlling a transmitting device for performing wireless power transmission to a receiving system using a predetermined frequency and the frequency used by the transmitting device. Includes a controller,

The controller determines a frequency determined by a natural resonance frequency, a split frequency calculated based on the natural resonance frequency, or a frequency tracking result performed based on the split frequency according to whether or not frequency splitting occurs. The transmitter may be controlled to transmit power to any one of the following.

A wireless power transmission system using a frequency splitting characteristic for solving the technical problem is a receiver for receiving power transmitted using a predetermined frequency from the transmission system and the power size of the power received by the receiver And a controller for transmitting predetermined control information to the transmission system on the basis of the identified power size, wherein the controller transmits power while changing the frequency, the power according to the frequency before the change. The control information to be output to the transmission system may be determined by comparing the magnitude and the magnitude of power according to the changed frequency.

The controller may transmit control information to be transmitted to the transmission system while selectively changing the impedance of the receiver.

The controller may selectively change an impedance of the receiver by controlling a switch for selectively connecting the receiver with a predetermined additional resistor.

When power using a natural resonance frequency is transmitted from the transmission system, the controller may calculate a coupling coefficient based on the magnitude of the transmitted power, and transmit information on the calculated coupling coefficient to the transmission system.

In a wireless power transmission method using a frequency splitting characteristic for solving the technical problem, a transmission system transmits power to a reception system using a natural resonance frequency, the transmission system coupling coefficient received from the reception system Calculating a splitting frequency on the basis of information on and transmitting power to the receiving system using the calculated splitting frequency, and based on the control information transmitted from the receiving system in response to the transmitting; Tracking the determined frequency for the transmission system to use.

Tracking the determination frequency to be used by the transmission system based on the control information transmitted from the reception system, selecting a frequency having a better transmission efficiency among the frequency before the change and the frequency after the change while changing the frequency by a predetermined first unit. It may include the step of performing at least once.

The tracking of the determination frequency to be used by the transmission system based on the control information transmitted from the reception system is a value smaller than the first unit when a frequency having the maximum transmission efficiency is determined while tracking using the first unit. The method may further include tracking the determined frequency by changing a frequency by a second unit having a.

In a wireless power transmission method using a frequency splitting characteristic for solving the technical problem, the transmission system determines whether frequency splitting has occurred, and the transmission system calculates the splitting frequency according to the determination result. Step, performing frequency tracking based on the calculated splitting frequency to confirm a determined frequency, and the transmission system uses either the calculated splitting frequency or the determined determined frequency to a receiving system. Transmitting power.

Therefore, according to the wireless power transmission system and the method using the frequency splitting characteristic according to an embodiment of the present invention, even if frequency splitting occurs by tracking the frequency with excellent transmission efficiency, the power using the tracked frequency Since the transmission, the transmission efficiency of a certain level or more can be guaranteed.

In addition, regardless of whether the distance between the transmitting system and the receiving system is relatively long or close enough to cause frequency splitting, it is possible to perform wireless power transmission with a certain level or more efficiency using the same system. have.

In addition, when the predetermined information is transmitted between the transmission system and the reception system for frequency tracking, impedance mismatch can be used, so that frequency tracking can be performed at a relatively low cost.

BRIEF DESCRIPTION OF THE DRAWINGS A brief description of each drawing is provided to more fully understand the drawings recited in the description of the invention.
1 is a view showing a schematic configuration of a conventional wireless power transmission system.
2 is a view for explaining a frequency splitting phenomenon when the distance is close in the magnetic resonance wireless power transmission.
3 is a view showing a schematic configuration of a wireless power transmission system according to an embodiment of the present invention.
4 is a view showing a schematic configuration of a receiving apparatus included in a receiving system according to an embodiment of the present invention.
5 is a schematic flowchart illustrating a process of tracking a frequency by a transmission system according to a wireless power transmission method according to an embodiment of the present invention.
6 is a schematic flowchart illustrating an operation of a receiving system for frequency tracking according to a wireless power transmission method according to an embodiment of the present invention.
FIG. 7 is a diagram illustrating a simulation result of a transmission efficiency when frequency splitting occurs in association with a frequency and a coupling coefficient in a wireless power transmission method according to an exemplary embodiment of the present invention.
8 is a view showing a result of simulating the performance when the wireless power transmission method according to an embodiment of the present invention is applied.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

Also, in this specification, when any one element 'transmits' data to another element, the element may transmit the data directly to the other element, or may be transmitted through at least one other element And may transmit the data to the other component.

Conversely, when one element 'directly transmits' data to another element, it means that the data is transmitted to the other element without passing through another element in the element.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.

1 is a view showing a schematic configuration of a conventional wireless power transmission system.

The conventional wireless power transmission system may include a transmitter 10 and a receiver 20 as shown in FIG.

The transmitting device 10 may include a transmitting resonant coil part 11 and a transmitting coil part 12, and the receiving device 20 includes a receiving coil part 21 and a receiving resonant coil part 22. can do.

Since such a wireless power transmission system is well known, only briefly, the transmission resonant coil unit 11 applies a current to the transmission resonant coil L1 using a predetermined alternating current power. Current is induced in the part 12 of the transmitting coil L2, which may result in a magnetic field. Then, current is sequentially induced in the receiving coil L3 of the receiving coil part 21 and the receiving resonant coil L4 of the receiving resonant coil part 22 of the receiving device, and consequently, a predetermined value in the load resistor R _L. Will consume power.

1 illustrates a configuration of the transmitter 10 and the receiver 20 related to power transmission, that is, resistors Rt, RL, r1, r2, r3, r4, and coils L1, L2, L3, L4. Although only capacitors C1, C2, C3, and C4 are schematically illustrated, the transmitter 10 and the receiver 20, in addition to the configuration shown in FIG. According to the type and function of the device 20, a predetermined antenna unit, a memory unit, a charging unit for charging and storing power, receiving data through magnetic field communication and transmitting the information stored in the mevory unit in response to the received data It can be easily inferred by the average expert in the technical field of the present invention that the controller part for the overall control of the back light may be further provided.

On the other hand, the transmission efficiency of the wireless power is changed according to the frequency used by the transmitter 10, and the frequency that enables the power transmission with the maximum efficiency is the resonance frequency. The resonance frequency may be expressed as in Equation 1.

는 각각 상기 송신장치(10)와 수신장치(20)의 공진 주파수를 나타내며,

와

는 각각 송신장치(10)의 등가적인 인덕턴스(inductance)와 캐패시턴스(capacitance)이고,

와

은 각각 수신장치(20)의 등가적인 인덕턴스와 캐패시턴스를 나타낸다. here,

Represents the resonant frequencies of the transmitter 10 and the receiver 20, respectively.

Wow

Are the equivalent inductance and capacitance of the transmitter 10, respectively.

Wow

Denotes the equivalent inductance and capacitance of the receiver 20, respectively.

If the values of inductance and capacitance of the transmitter 10 and the receiver 20 are the same, therefore, when power is transmitted using the inherent resonance frequency, power consumed by the transmitter 10 may be minimized, and at the same time, The power consumed by the receiver 20 can also be minimized, resulting in the best transmission efficiency.

및

)에 거의 영향을 미치지 않지만, 거리가 가까워지는 경우에는 상기 송신장치(10)와 상기 수신장치(20)에 각각 포함된 코일 간의 뮤츄얼 인덕턴스로 인해 각각의 인덕턴스(

및

) 값이 변하게 된다. 이러한 이유로 전달되는 전력의 주파수 특성이 변경된다. 변경되는 주파수 특성은 도 2를 참조하여 설명하도록 한다.When the distance between the transmitter 10 and the receiver 20 is relatively far, the value of the mutual inductance is small enough so that each inductance (

And

) Has little effect, but if the distance is getting closer, the mutual inductance between the transmitter 10 and the coils included in the receiver 20, respectively,

And

) Value will change. For this reason, the frequency characteristics of the delivered power change. The changed frequency characteristic will be described with reference to FIG. 2.

2 is a view for explaining a frequency splitting phenomenon when the distance is close in the magnetic resonance wireless power transmission.

In FIG. 2, the solid line in the center represents a frequency when the coupling coefficient k is 0.1, that is, when the distance is relatively long, and the transmission efficiency (S ₂₁ , the ratio of the output voltage to the input voltage) at this time. In addition, the other solid line indicates the frequency and transmission efficiency when the coupling coefficient k is 0.01, that is, when the distances of the two devices 10 and 20 are relatively close to each other within a certain distance.

Referring to FIG. 2, when the distance between the transmitter 10 and the receiver 20 is relatively far (k = 0.1), a peak having the best transmission efficiency at the resonant frequency appears.

However, when the distance is approached within a certain distance to affect the coils included in each of the transmitter 10 and the receiver 20 (k = 0.01), the peak having the best transmission efficiency is based on the natural resonance frequency. One will appear on each side. This phenomenon is called frequency splitting.

As a result, in the magnetic resonance wireless power transmission due to such frequency splitting, there is a problem in that the transmission efficiency is sharply reduced when using the natural resonance frequency at a close distance. Due to this, the magnetic resonance wireless power transmission has been mainly used only in a long distance where the frequency splitting does not occur.

The present invention can provide a technical idea that can guarantee a certain degree of transmission efficiency even in an environment where such frequency splitting occurs.

Mathematically, the frequency (hereinafter, 'spliting frequency') of each of two peaks in which frequency splitting occurs may be expressed as Equation (2).

는 회로의 고유 공진 주파수이며

는 저항 때문에 생기는 회로 고유의 디케이 레이트(decay rate)를 나타낸다. 또한,

는 커플링 계수이며 두 코일간에 얼마나 영향을 주는지에 대한 팩터(factor)로 사용된다. 이때 커플링 계수는 다음과 같은 수학식 3을 만족하게 된다. here

Is the natural resonant frequency of the circuit

Represents the inherent decay rate due to resistance. Also,

Is the coupling factor and is used as a factor for how much influence is between the two coils. In this case, the coupling coefficient satisfies Equation 3 below.

Accordingly, the low frequency and the high frequency of the splitting frequencies may be represented by Equations 4 and 5, respectively.

Accordingly, when such frequency splitting occurs, the wireless power transmission system according to the spirit of the present invention tracks a frequency (hereinafter, referred to as 'determined frequency') newly used for power transmission, and determines a determined frequency according to the tracking result. By using the power transmission to ensure the transmission efficiency over a certain level even if frequency splitting occurs. Tracking a frequency may mean a series of processes for searching for frequencies with better transmission efficiency.

The determination frequency may be any one of the two splitting frequencies described above. That is, the wireless power transmission system directly determines one of the splitting frequencies, which can be calculated by Equations 4 and 5, as a determination frequency, and performs power transmission using the determined determination frequency.

Theoretically, although the transmission efficiency may be the best at the splitting frequency, the transmission efficiency may not be the maximum at the splitting frequency for the surrounding environment or other reasons. For example, the value of the coupling coefficient k may be inaccurate and there may be various reasons.

Accordingly, the wireless power transmission system according to an embodiment of the present invention can determine the determined frequency by tracking a frequency having a higher transmission efficiency based on the splitting frequency.

As shown in FIG. 2, the wireless power transmission system may perform frequency tracking using any one of two splitting frequencies. In general, the transmission efficiency may be better at a lower frequency of the two splitting frequencies, and the wireless power transmission system may perform frequency tracking based on the lower frequency.

According to the technical idea of the present invention, a gradient algorithm may be used for frequency tracking. An example of such a gradient algorithm will be described later.

Therefore, in the case where frequency splitting occurs, the wireless power transmission system according to the technical concept of the present invention may compensate for the decrease in transmission efficiency by performing power tracking at a new frequency by performing frequency tracking based on the splitting frequency. It can be effective.

Of course, the wireless power transmission system according to the technical concept of the present invention may transmit power by using a natural resonance frequency in an environment where frequency splitting does not occur.

A schematic configuration of a wireless power transmission system according to an embodiment of the present invention for this technical concept is shown in FIGS. 3 and 4.

3 is a view showing a schematic configuration of a wireless power transmission system according to an embodiment of the present invention, Figure 4 is a view showing a schematic configuration of a receiving apparatus included in a receiving system according to an embodiment of the present invention. .

3 and 4, the wireless power transmission system 1 according to the embodiment of the present invention may include a transmission system 100 and a reception system 200.

The transmission system 100 may include a transmission controller 110 and a transmission device 120.

The transmitter 120 may be implemented to include the same or similar configuration as the conventional transmitter 10 shown in FIG. 1. The transmission controller 110 may control a frequency used by the transmitter 120 to transmit power. In addition, the transmission controller 110 may perform a predetermined operation as described later. For example, the transmission controller 110 may be implemented by including a predetermined microprocessor. Of course, the transmission controller 110 may further control other components of the transmission system 100 according to the type or function of the transmission system 100.

The receiving system 200 may include a receiving controller 210 and a receiving device 220. The reception controller 210 may detect the magnitude of the power received by the reception device 220 as described below, and store the magnitude of the detected power. In addition, a predetermined operation can be performed.

An embodiment of the receiver 220 may be as shown in FIG. 4.

As shown in FIG. 1, the receiver 220 according to an exemplary embodiment of the present invention has a predetermined additional resistance _R'L and 222 to the reception resonance coil unit 22 included in the conventional receiver 20. And a switch 221 may be further included. The additional resistor 222 may be connected to a load resistor R _L , and the switch 221 may be implemented to selectively connect the load resistor R _L and the additional resistor 222. The switch 221 may be turned on / off by the control of the reception controller 210. That is, the receiver 220 may be implemented to transmit predetermined information to the transmission system 100 through an impedance mismatch, and various modifications for performing impedance mismatch are possible. The average expert in the invention will be able to reason easily.

As described above, according to the technical idea of the present invention, the receiver system 200 is simply provided with only the additional resistor 222 and the switch 221 so that the reception system 200 implements the technical idea of the present invention with the transmission system 100. Information can be sent. The control information may be information used by the transmission system 100 to perform frequency tracking.

That is, in order to implement the technical idea of the present invention, it is necessary to be able to transmit predetermined information from the reception system 200 to the transmission system 100. To this end, the receiving system 200 may be provided with a separate communication means (not shown) for transmitting information to the transmission system 100. However, in this case, the cost and energy consumption for providing a separate communication means may be large, and a separate power source may be provided in the receiving system 200. Therefore, when implemented to perform impedance mismatch as shown in FIG. 4, it is possible to transmit information at low cost.

Impedance mismatch is a method mainly used for the information transmission method of the RFID, when applied to the wireless power transmission system 1 according to the technical idea of the present invention, the transmission system 100 in the reception system 200 efficiently It is possible to transmit predetermined information. Since the process of information transmission through the impedance mismatch is well known, only briefly, the receiver 220 may be in an impedance match with the transmitter 120 when the switch 221 is opened. . However, when the switch 221 is closed by the control of the receiving controller 210, the additional resistor 222 is connected to lower the overall impedance of the receiving device 220. Then, in the transmission system 100, a signal having a lower magnitude than that of an impedance match may be detected. Therefore, two signals having different magnitudes may be detected by the transmission system 100 under the control of the switch 221. That is, the reception controller 210 can transmit digital information having values of 0 and 1 to the transmission system 100 by controlling the switch 221. Therefore, the receiving system 200 may transmit information as described later using the impedance mismatch to the transmitting system 100.

When a frequency splitting occurs in the wireless power transmission system 1 according to an exemplary embodiment of the present invention which can have such a configuration, a process of tracking a frequency will be described with reference to FIGS. 5 and 6.

5 is a schematic flowchart illustrating a process of tracking a frequency by a transmission system according to a wireless power transmission method according to an embodiment of the present invention. 6 is a schematic flowchart illustrating an operation of a receiving system for frequency tracking according to a wireless power transmission method according to an embodiment of the present invention.

)를 이용하여 상기 수신시스템(200)으로 전력을 전송할 수 있다(S100). 그러면, 상기 수신시스템(200)은 소정의 전력을 수신할 수 있다(S200). 그러면, 상기 수신시스템(200)은 수신된 전력의 크기에 기초하여 커플링 계수(k) 값을 산출하고, 이를 상기 송신시스템(100)으로 전송할 수 있다(S210, S110). 5 and 6, the transmission system 100 has a natural resonance frequency (

Power can be transmitted to the receiving system 200 using the (S100). Then, the receiving system 200 may receive a predetermined power (S200). Then, the receiving system 200 may calculate a coupling coefficient (k) value based on the magnitude of the received power and transmit it to the transmitting system 100 (S210 and S110).

If the frequency splitting occurs, the wireless power transmission system 1 may determine whether or not the occurrence. For example, when the magnitude of power received by the reception system 200 suddenly decreases, the reception system 200 determines that frequency splitting has occurred, and transmits information on the transmission system 100 to the transmission system 100. have.

Then, the transmission system 100 calculates a value of a predetermined splitting frequency (eg, a low frequency splitting frequency) based on the coupling coefficient k value, and calculates the calculated splitting frequency. Power may be transmitted to the receiving system 200 by using the steps S120 and S220. According to an embodiment of the present disclosure, when frequency splitting occurs, the wireless power transmission system 1 may continue to transmit power at the splitting frequency. Even in this case, there may be an increase in transmission efficiency. However, as described above, the splitting frequency may not be the maximum efficiency due to the surrounding environment. Therefore, according to the spirit of the present invention, the wireless power transmission system 1 may perform frequency tracking based on the split frequency. The frequency tracking may be performed through a predetermined gradient algorithm.

For example, the transmission system 100 may change the frequency (eg, decrease by the first unit) by the first predetermined unit in the splitting frequency (S140). Of course, it is also possible to receive a predetermined confirmation signal (ack (nowledge) signal) from the receiving system 200 before (S240, S130). The power may be transmitted using the changed frequency (S150 and S250). Then, the transmission system 100 may select a frequency having better transmission efficiency among the frequency before the change and the frequency after the change. This selection may be performed based on the control information received from the receiving system 200 (S160, S270, S280).

The reception system 200 may store a power value (a magnitude of power) received from the transmission system 100 to output the control information (S230). When receiving power at the changed frequency (S250), it is possible to compare the magnitude of the stored power with the magnitude of the currently received power (S260). Then, predetermined control information indicating information on which power is larger may be output to the transmission system 100 (S270 and S280). For example, the first control information may be information indicating that the magnitude of the currently received power is larger (that is, the transmission efficiency is better). Therefore, the transmission system 100 may change again by a predetermined unit (eg, further decrease by the first unit). Then, using the changed frequency again (S170), power transmission may be performed at the changed frequency to receive control information to the receiving system 200 (S150, S160). The second control information may indicate a case where the magnitude of the currently received power is smaller.

As described above, the wireless power transmission system 1 changes the frequency by a predetermined first unit in a specific direction (for example, a direction of decreasing frequency) based on the first control information and the second control information, and thus the transmission efficiency. While tracking this good frequency, it is possible to detect a predetermined frequency that no longer improves transmission efficiency.

Then, the wireless power transmission system 1 uses the second unit having a smaller value than the first unit on the basis of the detected frequency (S140, S150, S250, S260, S270, S280, S170). ) Can be performed. Frequency tracking may be performed until the unit used for tracking becomes a predetermined value.

By repeating this process, the wireless power transmission system 1 can detect a crystal frequency having a relatively good transmission efficiency (or indicating a maximum efficiency) in the current channel environment.

Then, the wireless power transmission system 1 may perform power transmission using the detected frequency.

FIG. 7 is a diagram illustrating a simulation result of a transmission efficiency when frequency splitting occurs in association with a frequency and a coupling coefficient in a wireless power transmission method according to an exemplary embodiment of the present invention.

FIG. 7 shows simulation results using the configuration as shown in FIGS. 3 and 4, wherein the transmitter 120 is the same as the transmitter 10 shown in FIG. 1. Where Rt = RL = 50, L1 = L4 = 1uH, C1 = C4 = 235pF, r1 = r4 = 0.25, k12 = k34 = 0.1, L2 = L3 = 20uH, C2 = C3 = 12.6pF, r2 = r3 = 1 The coupling coefficient between the transmitter 120 and the receiver 220 was changed from 0.001 to 0.3. At this time, the resonance frequency f0 = 10MHz and the frequency was changed from 8MHz to 12MHz.

When the simulation is performed in such an environment, frequency splitting does not occur when the distance between two circuits is small and the coupling coefficient is small, but frequency splitting occurs when the coupling coefficient becomes large due to the distance. You can check it.

In this situation, the results of simulating the performance improvement by performing the wireless power transmission method according to the embodiment of the present invention are shown in FIG. 8.

8 is a view showing a result of simulating the performance when the wireless power transmission method according to an embodiment of the present invention is applied.

FIG. 8 shows a result of performing frequency tracking through the gradient algorithm as described above using a low splitting frequency at the shared resonance frequency as described above.

In order to compare with the technical idea of the present invention, the transmission efficiency when the frequency of the power supply source is fixed at the intrinsic resonance frequency is shown as shown in FIG. 8.

As shown in FIG. 8, when the distance is relatively large and the interference is small, there is no significant difference in transmission efficiency. However, when the frequency is split due to the distance, the wireless power transmission method according to the technical concept of the present invention is effective. It can be seen that this can be significantly improved.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (15)

In the wireless power transmission system using the resonance,
A transmitting device for performing wireless power transmission to a receiving system using a predetermined frequency; And
It includes a controller that can control the frequency used by the transmitter,
The controller,
When frequency splitting occurs, information about a coupling coefficient is received from the receiving system, and a split frequency is calculated by the following equation based on the received information and the natural resonant frequency. and,
And a frequency splitting characteristic that tracks a frequency to be used by the transmitter using the calculated splitting frequency and controls the transmitter to transmit power at a determined frequency determined as a result of the tracking.
[Mathematical Expression]

(here

Is the natural resonant frequency of the circuit

Represents the inherent decay rate due to resistance. Also,

Is the coupling factor)
The method of claim 1, wherein the controller,
The transmitter is controlled to transmit power at a natural resonant frequency, and when the frequency splitting occurs, the transmitter is controlled to transmit power at the determined frequency. system.
delete The method of claim 1, wherein the controller,
The transmission device is controlled to transmit power to the receiving system using the calculated splitting frequency, and the frequency is changed between the frequency before the change and the frequency after the change while the frequency is changed by a predetermined first unit, and has a better transmission efficiency. Wireless power transmission system using a frequency splitting characteristic that performs at least one process of selecting a.
The method of claim 4, wherein the controller,
And a frequency splitting characteristic for selecting a frequency having a higher transmission efficiency between the frequency before the change and the frequency after the change, based on predetermined control information received from the receiving system.
The method of claim 4, wherein the controller,
When the frequency having the maximum transmission efficiency is determined while tracking using the first unit, the frequency is split by changing the frequency by a second unit having a value smaller than the first unit to track the determined frequency. Wireless power transmission system using the automatic setting characteristic.
delete delete delete delete delete In the wireless power transmission method using resonance,
The transmission system transmitting power to the reception system using the natural resonance frequency;
Calculating, by the transmission system, the splitting frequency using the following equation based on information on the coupling coefficient received from the receiving system and the natural resonance frequency;
Transmitting power to the receiving system using the calculated splitting frequency; And
Tracking a determined frequency for use by the transmitting system based on control information received from the receiving system in response to the transmission; And
Wireless power transmission method using a frequency splitting characteristic comprising the step of transmitting power at a determined frequency determined as a result of the tracking.
[Mathematical Expression]

(here

Is the natural resonant frequency of the circuit

Represents the inherent decay rate due to resistance. Also,

Is the coupling factor)
The method of claim 12, wherein tracking the determination frequency to be used by the transmission system based on the control information transmitted from the reception system,
And performing at least one step of selecting a frequency having a higher transmission efficiency among the frequency before the change and the frequency after the change while changing the frequency by a predetermined first unit.
The method of claim 13, wherein the tracking of the determination frequency to be used by the transmission system based on the control information transmitted from the reception system comprises:
If the frequency having the maximum transmission efficiency is determined while tracking using the first unit, changing the frequency by a second unit having a value smaller than the first unit to track the determined frequency. Wireless power transmission method using pleating characteristics.
delete

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