KR102559302B1 - Antenna apparatus andwireless poser transmission and reception system comprising the same - Google Patents

Abstract

The antenna device of the embodiment may include a shielding coil unit including a coil, an inner coil surrounding at least a portion of the coil, and an outer coil connected to the inner coil and spaced apart from the inner coil.
The embodiment has an effect of effectively removing a leakage magnetic field while preventing a decrease in power transmission efficiency by forming a shielding coil of a double loop.

Description

Antenna device and wireless power transmission and reception system including the same

The embodiment relates to a wireless power transmission and reception system for transmitting and receiving wireless power.

In general, most electrical devices in use require direct connection through an object such as a cable, which causes restrictions on the use of electrical devices by users. In this regard, cases of applying wireless power transmission technology that can wirelessly supply electric energy to devices that use high power such as mobile phone charging, home appliances such as TVs, and electric vehicles and electric railways are increasing.

Wireless charging technology can supply electrical energy even if a device that supplies electrical energy and a device that uses electrical energy are not directly connected through a material such as a wire. Accordingly, in supplying electrical energy to a device that uses electrical energy, it has received a lot of attention in terms of improving use restrictions and convenience for users.

Among various types of wireless power transmission technologies, wireless power transmission technology based on the principle of magnetic induction is most widely used based on the advantages of providing power transmission efficiency and high power transmission capacity.

In the magnetic induction wireless power transmission technology, when an alternating current having a specific frequency is applied to a coil, a magnetic field is generated in the coil, and the coil exposed to the generated magnetic field receives electric energy according to the law of magnetic induction. Accordingly, electrical energy may be supplied by magnetic induction coupling without a direct electrical connection between the two coils.

In the magnetic induction type wireless power transmission, a high density magnetic field is generated to transmit electric energy while the device is operating, and in this process, a leakage magnetic field is generated around the device. When a person is exposed to a leaky magnetic field generated around a wireless power transmission device, it has a negative effect on the human body, so it is required to reduce the effect on the human body due to the leaked magnetic field.

To reduce the leakage magnetic field, various types of shielding methods may be applied, such as configuring an enclosure with a material such as aluminum or generating an offset magnetic field capable of canceling the leakage magnetic field. However, the conventionally proposed shielding method has a problem in that the efficiency of wireless power transmission is lowered.

Reduction in wireless power transmission efficiency means loss of supplied electrical energy, and in this case, unnecessary waste of energy occurs. That is, even if the efficiency decreases at the same rate, a greater loss of electric energy may occur in a high-power device such as an electric vehicle compared to a low-power device such as a mobile phone.

In order to solve the above problems, an object of the embodiment is to provide an antenna device capable of effectively removing a leakage magnetic field without reducing power transmission efficiency and a wireless power transmission/reception system including the same.

The antenna device of the embodiment may include a shielding coil unit including a coil, an inner coil surrounding at least a portion of the coil, and an outer coil connected to the inner coil and spaced apart from the inner coil.

A phase of the inner coil may have the same phase as a magnetic field generated from the coil, and a phase of the outer coil may have a reverse phase from a magnetic field leaked from the coil.

The number of turns of the outer coil may be determined using information about a radius between the inner and outer coils and information on the number of turns of the outer coil compared to the number of turns of the inner coil.

A direction of the current flowing in the inner coil may correspond to a direction of the current flowing in the coil, and a direction of the current flowing in the outer coil may be opposite to a direction of the current flowing in the coil.

The coil may be formed in a spiral shape, and the inner coil may be disposed to surround an outer side of the coil.

The inner coil may further include a first inner coil disposed inside the coil.

The coil may be formed in a spiral shape, and the inner coil may be disposed between radially disposed coils.

In addition, the wireless power transmitting and receiving device according to the embodiment includes a power feeding coil unit including a power feeding coil and a power feeding shielding coil including a first inner coil arranged to surround at least a portion of the power feed coil, a first outer coil connected to the first inner coil and spaced apart from the first inner coil, a power collecting coil and a second inner coil arranged to surround at least a portion of the power collecting coil, and the second inner coil connected to the second inner coil. and a current collecting coil unit including a current collecting shielding coil including a second outer coil disposed spaced apart from the second outer coil.

A phase of the first inner coil may have the same phase as a magnetic field generated from the power supply coil, and a phase of the first outer coil may have a reverse phase with a magnetic field leaked from the power supply coil.

The number of turns of the first outer coil may be determined using information about a radius between the first inner coil and the first outer coil and information on the number of turns of the outer coil compared to the number of turns of the first inner coil.

A direction of the current flowing in the first inner coil may correspond to a direction of the current flowing in the feeding coil, and a direction of the current flowing in the first outer coil may be opposite to a direction of the current flowing in the feeding coil.

The embodiment has an effect of preventing power transmission efficiency from decreasing by forming a double loop shielding coil.

In addition, the embodiment has an effect of effectively removing a leakage magnetic field by forming a double loop shielding coil.

1 is a block diagram illustrating a wireless power transmission and reception system according to an embodiment.
2 is a schematic perspective view illustrating the antenna device of FIG. 1;
3 is a diagram illustrating current flowing through an antenna device according to an embodiment.
4 is a diagram illustrating the generation of a magnetic field according to a current flowing through an antenna device according to an embodiment.
5 is a graph showing an example of determining a resonant frequency of a shielding coil.
6 is a graph showing a magnetic field phase vector diagram of a shielding coil.
7 is a diagram showing an example of generation of a magnetic field according to mutual inductance.
8 is a diagram showing an example of actual inductance according to the phase of an external magnetic field.
9 is a circuit diagram showing a 2-coil equivalent circuit including the effect of a shielding coil.
FIG. 10 is a diagram illustrating a schematic view of a geometric distance of a coil with respect to a point p.
11 is a diagram illustrating measurement points of a leakage magnetic field.
12 is a graph showing currents of a power feeding coil and a collecting coil when a shielding coil according to an embodiment is not applied.
13 is a graph showing currents of a power feeding coil and a collecting coil when a shielding coil according to an embodiment is applied.
14 is a graph comparing supply power and power reaching a load when a shielding coil according to an embodiment is not applied.
15 is a graph comparing supply power and power reaching a load when a shielding coil according to an embodiment is applied.
16 is a graph comparing efficiency according to whether or not a shielding coil is applied.
17 is a graph showing simulation results of a shielding effect according to the presence or absence of a shielding coil according to an embodiment.
18 is a graph showing simulation results for electromagnetic interference (EMI) to check the degree of influence on peripheral electronic devices.
19 to 21 are diagrams illustrating modified examples of an antenna device according to an embodiment.

Hereinafter, embodiments will be described in detail with reference to the drawings.

1 is a block diagram showing a wireless power transmission and reception system according to an embodiment, FIG. 2 is a schematic perspective view showing the antenna device of FIG. 1, FIG. 3 is a diagram showing current flowing through the antenna device according to the embodiment, FIG. 4 is a diagram showing the generation of a magnetic field according to the current flowing through the antenna device according to the embodiment, FIG. 5 is a graph showing an example of determining a resonance frequency of a shielding coil, FIG. It is a diagram showing an example of the generation of a magnetic field according to the inductance, FIG. 8 is a diagram showing an example of the actual inductance according to the phase of the external magnetic field, FIG. 9 is a circuit diagram showing a 2-coil equivalent circuit including the effect of the shielding coil, FIG. 10 is a diagram showing the geometric distance of the coil with respect to the point p, FIG. 13 is a graph showing the current of the feeding coil and the current collecting coil when the shielding coil according to the embodiment is applied, FIG. 14 is a graph comparing power supplied and power reached at load when the shielding coil according to the embodiment is not applied, and FIG. 15 is a graph comparing power supplied and power reached at load when the shielding coil according to the embodiment is applied, and FIG. 17 is a graph showing simulation results for shielding effects according to the presence or absence of a shielding coil according to an embodiment, and FIG. 18 is a graph showing simulation results for electromagnetic interference (EMI) to confirm the degree of influence on nearby electronic devices.

Referring to FIG. 1, a wireless power transmission and reception system 1000 according to an embodiment may include a power supply unit 100, a wireless power transmitter 200, antenna devices 300 and 400, a wireless power receiver 500, and a load stage 600. Here, the antenna device may include either one or both of the power supply coil unit 300 and the power collecting coil unit 400 . In the embodiment, the wireless power transmitter 200 and the power supply coil unit 300 of the antenna device have been described as separate components, but the power transmitter 200 and the power supply coil unit 300 may be configured as one unit.

The wireless power transmitter 200 is connected to the power supply unit 100 and may receive power from the power supply unit 100 . Here, the power supply unit 100 may generate AC power having a predetermined frequency.

Wireless power transmission may transmit and receive power using an electromagnetic induction method or a resonance method.

The wireless power transmitter 200 may include an inverter, a capacitor, and a rectifier for power conversion, but is not limited thereto.

The wireless power transmitter 200 receives commercial power, converts it to the operating frequency of the wireless power transmission/reception system 1000, and supplies it to the power supply coil unit 300. A time-varying magnetic field according to the operating frequency may be generated in the power supply coil unit 300. At this time, the current collector coil unit 400 is exposed to a time-varying magnetic field generated by the power supply coil unit 300, and in this process, magnetic induction coupling is generated so that electric energy can be transmitted.

The wireless power receiver 500 may convert the received power and supply it to the load stage 500. The load stage 500 may be a car, a train, a mobile phone, or a computer itself or a battery included therein to store or consume electrical energy, but is not limited thereto.

In order to effectively supply electric energy through magnetic field coupling between the power supply coil unit 300 and the collector coil unit 400, a resonance phenomenon can occur with respect to the operating frequency of the wireless power transmission/reception system 1000. A resonance circuit can be configured using a capacitor.

On the other hand, the antenna device including the power supply coil unit 300 for transmitting and receiving power and the power collecting coil unit 400 may be provided with a shielding means for shielding a phenomenon in which power efficiency is reduced in the coil and a magnetic field leaking. Here, the shielding means may be a shielding coil.

As shown in FIG. 2 , the power supply coil unit 300 of the antenna device may include a power supply coil 310 and a power supply shielding coil 320 disposed adjacent to the power supply coil 310 . Here, the power supply shielding coil 320 may be designed to have a double loop.

The power supply coil 310 may be formed in a spiral shape. Alternatively, the power supply coil 310 may be formed in various shapes such as a polygonal shape or an elliptical shape.

The power supply shielding coil 320 may be disposed to surround the power supply coil 310 . The power supply shielding coil 320 may include a first inner coil 322 and a first outer coil 324 . The first inner coil 322 may be disposed to surround the outside of the power supply coil 310 . The first outer coil 324 may be spaced apart from the first inner coil 322 . A connection coil 326 may be formed between the first outer coil 322 and the first inner coil 324 such that one end thereof is connected.

The first inner coil 322 generates an auxiliary field having the same magnetic field vector as the magnetic field transmitted from the power supply coil 310 to the current collector coil 410, thereby preventing a decrease in wireless power transmission efficiency. The first outer coil 324 may generate a shielding magnetic field that cancels out a leakage magnetic field generated from the power supply coil 310 .

Since the power supply shielding coil 320 is formed in a double loop, it can be operated to prevent deterioration in efficiency and reduce a leakage magnetic field, and as a result, shielding can be performed without deterioration in efficiency.

The collecting coil unit 400 of the antenna device may include a collecting coil 410 and a collecting shielding coil 420 disposed adjacent to the collecting coil 410 . Here, the current collection shielding coil 420 may be designed to have a double loop.

The current collecting coil 410 may be formed in a spiral shape, but the shape is not limited.

The current collection shielding coil 420 may be disposed adjacent to the current collection coil 410 . The current collection shielding coil 420 may include a second inner coil 422 and a second outer coil 424 . The second inner coil 422 may be disposed to surround the outside of the current collecting coil 410 . The second outer coil 424 may be spaced apart from the second inner coil 422 . A connection coil 426 may be disposed between the second outer coil 424 and the second inner coil 422 such that one end thereof is connected.

As shown in FIG. 3 , when the current I _WPT is generated, the current flowing through the first inner coil 322 is generated as I _SH-in in the same direction as the current I _WPT of the power supply coil 310 . In addition, since the first outer coil 326 is designed as a reverse turn wound in the opposite direction to the first inner coil 322, a current in a direction opposite to that of the first inner coil 322 may be generated.

As shown in FIG. 4, the first inner coil 322 disposed adjacent to the power supply coil 310 has the same phase as the wireless power transmission and the magnetic field and is synthesized, and the first outer coil 326 has an antiphase (180 degree difference) with respect to the leakage magnetic field. As a result, the first inner coil 322 preserves the phase of wireless power transmission and shields the leakage magnetic field works in principle. The current collection shielding coil 420 may also be operated in the same manner as above.

For the above-described operation of the shielding coil, the power supply coil 310 and the first inner coil 322 of the power supply shielding coil 320 must generate a magnetic field of the same phase. By regulating the capacitor for this, it can be achieved.

As shown in FIG. 5 , by designing the first inner coil 322 to have a higher resonant frequency with respect to the operating frequency, it is possible to control the power supply coil 310 to generate current in the same phase. Accordingly, it can be controlled to generate a magnetic field generated according to the current or a magnetic field vector of the same phase.

In the same way, the second inner coil 422 may be designed to have a higher resonant frequency with respect to the operating frequency, so that currents in the same phase may be generated with respect to the current collector 410 .

As shown in FIG. 6, B _TX and B _RX mean magnetic fields generated by the power supply coil 310 (TX) and the power collecting coil 410 (RX), and B _TS-in and B _TS-out may mean magnetic fields generated by the first inner coil 322 and the first outer coil 324 of the power supply shielding coil 320.

6, it can be seen that the magnetic fields B _TS-in and B _RS-in generated in the first inner coil 322 and the second inner coil 422 of the power supply shielding coil 320 and the current collector shield coil 420 are generated in the same direction with respect to the magnetic field B _TX in the power supply coil 310 and the magnetic field B _RX in the current collector coil 410.

In addition, it can be seen that the magnetic fields B _TS-out and B _RS-out generated from the first outer coil 324 and the second outer coil 424 of the power feeding shielding coil 320 and the current collecting shielding coil 420 have an antiphase with respect to B _TX , B _RX , B _TS-in , and B _RS-in .

Through the relationship between the magnetic field vectors, it can be seen that the inner coils of the shielding coils 320 and 420 assist wireless power transmission, and the outer coils of the shielding coils 320 and 420 cancel the leakage magnetic field.

The operation of the shielding coil according to the coupling coefficient condition is as follows. Here, the shielding coil may be used as a general term for a power feeding shielding coil and a current collecting shielding coil.

When the shielding coil is made of only the outer coil, energy for generating a magnetic field in the outer coil is supplied from the wireless power transmission coil, which can be determined by mutual inductance between the wireless power transmission coil and the shielding coil as shown in Equation 1.

[Equation 1]

Here, iX means an arbitrary wireless power transmission coil, and iS may mean an arbitrary shielding coil. That is, it can be seen that the mutual inductance M _iSiX of an arbitrary wireless power transmission coil and an arbitrary shielding coil is determined by the coupling coefficient k _iXiS between the two coils and the inductances L _iX and L _iS of the two coils.

Since the shielding coil used in the embodiment has a structure of an inner coil and an outer coil, the final inductance of Equation 1 may be determined by the total sum of mutual inductance with the inner coil and mutual inductance with the outer coil as in Equation 2.

[Equation 2]

Mutual inductance conditions for Equation 2 are as shown in FIGS. 3 to 5. Each condition may lead to a different operation of the shielding coil.

[Equation 3]

[Equation 4]

[Equation 5]

Equation 3 means the case where the mutual inductance for the inner coil of the shielding coil and the mutual inductance for the outer coil are the same. In this case, the inner coil and the outer coil of the shielding coil generate magnetic fields in opposite directions to each other. Mutual inductance with a wireless power transmission coil converges to zero.

In the case of Equation 4, it means that the mutual inductance with the outer coil is greater than the inner coil of the shielding coil. In this case, the outer coil of the shielding coil generates a magnetic field in the same phase as the arbitrary wireless power transmission coil, and the inner coil generates a magnetic field of antiphase. As shown in FIG.

The ratio of turns between the inner coil and the outer coil of the shielding coil is equal to 1:1, and if the inner coil of the shielding coil is adjacent to the wireless power transmission coil relative to the outer coil, it is difficult to achieve this condition. However, when the outer coil is designed to have a large number of turns in the turn ratio between the inner coil and the outer coil of the shielded coil, care must be taken that these operating conditions occur because they may have high inductance even at a low coupling coefficient.

In the case of Equation 5, it means that the inner coil of the shielding coil has a larger mutual inductance than the outer coil. In this case, a magnetic field in phase with an arbitrary wireless power transmission coil is generated in the inner coil of the shielding coil, and a magnetic field in antiphase is generated in the outer coil. As shown in FIG.

Here, the condition of FIG. 7B is the normal operation of the shielding coil corresponding to the embodiment, and in this case, loss due to the shielding coil is prevented by the harmonized region, and the shielding operation occurs.

The preservation of wireless power efficiency is as follows. The quality factor described below may mean an index for determining a peak value and a bandwidth of an electrical response from an operating frequency in wireless power transmission.

The wireless power transmission/reception system with a low quality factor has a wide bandwidth from the operating frequency, and thus can operate robustly against changes in operating performance due to changes in various operating conditions occurring during the wireless power transmission process. However, there is a disadvantage that the maximum value of the wireless power transmission/reception efficiency is lower than that of a system having a high quality factor.

Conversely, a wireless power transmission/reception system having a high quality factor increases the maximum value of wireless power transmission efficiency, and under ideal operating conditions, it is possible to secure higher power transmission efficiency compared to wireless power transmission having a low quality factor. However, a wireless power transmission/reception system designed to have a too high quality factor due to a small bandwidth from the center frequency may be unstable compared to a wireless power transmission/reception system having a low quality factor in terms of operational robustness.

Such a quality factor of wireless power transmission can also be used as an index for determining a maximum power transfer condition.

Since the amount of power transmission is determined according to the degree of magnetic field coupling between the two coils that transmit and receive power according to the quality factor of wireless power transmission, the quality factor can be designed to have an appropriate quality factor rather than unconditionally pursuing high or low.

That is, the quality factor of the wireless power transmission coil may be closely related to power transmission efficiency. The quality factor (Q-factor) of the coil is as shown in Equation 6, and the resulting coil-to-coil efficiency: ) may be the same as Equation 7.

[Equation 6]

[Equation 7]

Looking at Equation 6 for the quality factor, in order to increase the quality factor Q _ix when the operating frequency w is the same, the internal resistance R _ix present in any wireless power transmission coil must be reduced or the inductance L _ix of the coil must be increased. It can be seen that.

The internal resistance of a coil is a factor that increases linearly with the unit length of the coil, and as the number of turns increases, the internal resistance also increases.

That is, the quality factor of the wireless power transmission coil designed with a specific number of turns does not change the quality factor after the design variable is set, so that the power transmission efficiency between coils is determined under given conditions as in the equation.

However, when a coil generating a magnetic field is nearby, the actual inductance is determined by the self inductance of the wireless power transmission coil and the mutual inductance with the external magnetic field.

At this time, the effect of the external magnetic field on the wireless power transmission coil may be defined as in Equation 8, and in the case of the example shown in FIG.

[Equation 8]

[Equation 9]

[Equation 10]

The shielding coil according to the embodiment is installed in each of the feeding coil and the collecting coil, and the generated magnetic field is also generated in the same phase with respect to the feeding coil and the collecting coil in the region of the inner coil of the shielding coil. As a result, the actual inductance of the feeding or collecting coil is increased.

In addition, since the power feeding shielding coil operates dependently on the power supply coil and the current collecting shielding coil operates dependently on the current collecting coil, the shielding coil corresponding to each wireless power transmission coil is converted as the same phase with respect to each corresponding coil. In this case, a wireless power transmission/reception system composed of a total of four coils can be replaced as an equivalent circuit composed of two coils as shown in FIG.

In this case, the actual inductances of the power feeding coil and the collecting coil are as shown in Equations 11 and 12, and the quality factors according to the inductance may be expressed by Equations 13 and 14.

[Equation 11]

[Equation 12]

[Equation 13]

[Equation 14]

That is, when the above quality factor including the effect of the mutual inductance of the shielding coil is compared with the quality factor when the shielding coil is not included, as shown in FIG. 9, the mutual inductance corresponding to _MTX and M _RX corresponding to the same phase is added, and since the actual number of turns of the power supply and collector coils does not increase, they have the same internal resistance, so the quality factor is improved as a result.

Based on these influences, the power supply coil and the collector coil have higher quality factors, and as a result, power transmission efficiency between coils may increase.

At this time, since the actual inductance of each feeding and collecting coil changes, the resonant capacitors for the feeding and collecting coils must be changed to match the actual inductance, and the method for determining the capacitance according to the actual inductance is as shown in Equation 15.

[Equation 15]

As confirmed in the equivalent circuit for the previous four coils, each shielding coil for the power supply coil and the power collector coil also has internal resistance, so as a result, electrical energy is consumed.

[Equation 16]

That is, when the shielding coil is applied through Equation 16, loss from the power supply shielding coil and losses from the current-collecting shield coil It can be seen that is added.

However, since the increase in power transmission efficiency obtained through the improvement of the quality factor is greater than the loss additionally generated by the shielding coil, as a result, even if the shielding coil is applied, the efficiency may not decrease or the efficiency may increase depending on the design method.

Hereinafter, a method for determining shielding performance will be described.

A diagram of the entire coil of the wireless power transmission and reception system including the shielding coil of the embodiment may be shown as shown in FIG. 10 .

Assuming that the magnetic field at a specific point p is calculated, the strength of the magnetic field can be calculated based on a geometric distance from the central axis of the coil to the point p.

All coils have the same coaxial axis, and the geometric distance to point p can be calculated on Cartesian coordinates represented by x, y, and z axes.

Since the power supply coil (TX) and the power supply shielding coil (TS) are located on a coplanar plane, and the current collector coil (RX) and the current collector shield coil (RS) are located on a coplanar plane, each geometric distance for point p on the geometric distance can be calculated as in Equations 17 and 18.

[Equation 17]

[Equation 18]

At this time, the density of the total magnetic field generated in one coil can be calculated as shown in Equation 19 through the integral of the closed surface over the entire length of the coil.

In Equation 19, B is the magnetic flux density, i means an arbitrary variable for the power supply coil (TX), power collector coil (RX), power supply shield coil (TS), and power collector shield coil (RS), and n is the coil. If it has a plurality of turns, it may mean the number for each turn.

For example, if the number of turns of a coil consists of 10 turns, the total magnetic field generated in the coil can be obtained by integrating the magnetic fields generated in each turn from the first turn to the 10th turn and adding all the values.

[Equation 19]

The magnetic field strength at a specific point p can be defined as in Equation 20 by reflecting the distance from the central axis of the coil to the point p and the difference between the radii occurring in each of the coils composed of a plurality of turns.

[Equation 20]

[Equation 21]

[Equation 22]

[Equation 23]

Referring to Equation 21, when a spiral coil composed of a plurality of turns is designed, each turn is generated by accumulating a difference in radius equal to the cross-sectional area of the coil, and this difference affects the magnetic field strength at a specific point p.

That is, it can be said that each radius of each turn and the magnetic field strength at point p of the coil turn for the corresponding radius are calculated and summed up.

The equation is an equation for showing an example of magnetic field calculation for a single layer coil having multiple turns, and the coil has multiple layers or a complex structure composed of multiple turns and multiple layers. Formulas for coils may exist separately.

As a result, at a specific point p, the feeding coil magnetic field B _pTX , the collecting coil magnetic field B _pRX , the inner coil magnetic field of the feeding shielding coil B _pTS-in , the inner coil magnetic field of the collecting shielding coil B _pTS-in , the outer coil of the feeding shielding coil B _pTS-out , the outer coil magnetic field of the collecting shielding coil B _pRS-out , etc. It can be calculated as 24.

[Equation 24]

Regarding shielding performance, since the magnetic field generated from the feeding coil and the inner coil of the feeding shielding coil are in phase, and the magnetic fields generated from the collecting coil and the inner coil of the current collecting shielding coil are in phase, the shielding magnetic field for the corresponding magnetic field is generated by the outer coil of each shielding coil.

As a result, the maximum shielding performance is defined as Equation 25 in which the sum of the strength of the magnetic field generated from the inner coil of each shielding coil and the inner coil of each shielding coil and the sum of the shielding magnetic field generated from the outer coil of each shielding coil approaches 0.

[Equation 25]

Hereinafter, the result of performing the simulation according to the embodiment will be described.

-Simulation model design-

The inventive technology was applied to a 200W class wireless power transmission and reception system operating at a frequency of 85 khz, and the efficiency and shielding performance thereof were reviewed.

The results were compared by simulating the case where the technology of the embodiment was not applied and the case where the technology of the embodiment was applied, respectively, and the parameters used in the simulation are as follows.

When the shielding coil is applied, it can be seen that the capacitors applied to the power supply coil (TX) and the power collector coil (RX) are set differently, which is the result of applying the capacitance calculated through Equation 15 to the actual inductance change.

[Table 1]

[Table 2]

The coil structure used in the simulation is as shown in FIG. 2, and the leakage magnetic field measurement point for confirming the shielding effect was measured at three points, such as 200 mm, 250 mm, and 300 mm in height, starting from the outer coil of the shielding coil as shown in FIG.

- Simulation model results -

As shown in FIGS. 12 and 13 , it can be seen that the case where the shielding coil is applied and the case where it is not, the current generated in the current collector coil (RX) is similar, but the current of the power supply coil has a difference of about 5A.

Through the current comparison of each coil, it can be confirmed that the increased quality factor is increased due to the increase in actual inductance due to the effect of the shielding coil, and as a result, a higher magnetic field is transmitted to the collecting coil even at a low current.

In addition, as shown in FIG. 14, when the shielding coil is not applied, it can be confirmed that a loss of about 13W occurs because power of about 225W is supplied and power of 212W is transmitted.

As shown in FIG. 15, when the shielding coil is applied, it can be confirmed that a power loss of about 12W occurs because about 204W of power is delivered by supplying about 216W of power.

Through this, it can be confirmed that there is no difference in power loss when compared with the case where the shielding coil is not applied in terms of power loss.

16 is a simulation result of efficiency between a case in which a shielding coil is not applied and a case in which a shielding coil is applied, and the efficiency is calculated as a ratio of supplied power and transmitted power. FIG. 16A is a simulation result of the efficiency when the shielding coil is not applied, showing a power transfer efficiency of about 94.3%, and FIG. 16B shows a power transfer efficiency of about 94.4%.

Based on this, it can be confirmed that the reduction in efficiency does not occur even when the shielded coil is applied.

As shown in FIG. 17, it can be confirmed that the leakage magnetic field is reduced when the shielding coil is applied compared to the case where the shielding coil is not applied, and the average leakage magnetic field reduction rate is about 73%.

In addition, FIG. 18 is a simulation result of electromagnetic interference (EMI) to confirm the degree of influence on nearby electronic devices, and the magnetic field strength was measured at a distance of 6 m from the wireless power transmission device.

Compared to the case where the shielding coil is not applied, it can be confirmed that about 8dB of electromagnetic interference is reduced in the entire measurement period when the shielding coil is applied.

Through these examples, it was confirmed that the inventive shielding method can secure a high level of shielding performance without reducing the efficiency of wireless power transmission.

The shielding method according to the embodiment does not have to be designed in the same form as the model used in the embodiment, and the user desires through various variables such as the radius and application position of the inner and outer coils of the shielding coil, and the difference in the number of turns. It can be transformed into a form and used.

In addition, through such a design change, it can be modified and operated so that more effects occur in terms of shielding performance and efficiency.

19 to 21 are diagrams illustrating modified examples of an antenna device according to an embodiment. Here, the antenna device may include a power supply coil unit and a power collecting coil unit, but a convenient power supply coil unit will be described as a representative, and the configuration of the power collecting coil unit may be the same as that of the power supply coil unit.

As shown in FIG. 19 , the power supply coil unit 300 of the antenna device may include a power supply coil 310 and a power supply shielding coil 320 .

The power supply coil 310 may be formed in a spiral shape. Alternatively, the power supply coil 310 may be formed in various shapes such as a polygonal shape or an elliptical shape. The power supply coil 310 may be radially overlapped.

The power supply shielding coil 320 may be disposed to surround the power supply coil 310 . The power supply shielding coil 320 may include a first inner coil 322 and a first outer coil 324 .

The first inner coil 322 may be disposed between the radially disposed power supply coils 310 . The first outer coil 324 may be spaced apart from the first inner coil 322 . A connection coil 326 may be formed between the first outer coil 322 and the first inner coil 324 such that one end thereof is connected.

As shown in FIG. 20 , the power supply coil unit 300 of the antenna device may include a power supply coil 310 and a power supply shielding coil 320 .

The power supply coil 310 may be formed in a spiral shape. Alternatively, the power supply coil 310 may be formed in various shapes such as a polygonal shape or an elliptical shape. The power supply coil 310 may be radially overlapped.

The power supply shielding coil 320 may be disposed to surround the power supply coil 310 . The power supply shielding coil 320 may include a first inner coil 322 and a first outer coil 324 .

The first inner coil 322 may be disposed to surround the outside of the power supply coil. The first outer coil 324 may be spaced apart from the first inner coil 322 . A connection coil 326 may be formed between the first outer coil 322 and the first inner coil 324 such that one end thereof is connected.

In addition, a third inner coil 321 may be further disposed inside the power supply coil 310 . A connection coil may be connected between the third inner coil 321 and the first inner coil 322 .

As shown in FIG. 21 , the first inner coil 322 of the power supply shielding coil may be disposed between the power supply coils 310 radially overlapping each other. That is, since the first inner coil 322 is disposed between the radially spaced power supply coils 310 , power efficiency may be prevented from being lowered.

Although the above has been described with reference to drawings and embodiments, those skilled in the art can variously modify and change the embodiments without departing from the technical spirit of the embodiments described in the claims below. It will be appreciated.

100: power supply
200: wireless power transmitter
300: power supply coil unit
400: collector coil unit
500: wireless power receiver
600: load

Claims (11)

delete delete coil; and
A shielding coil unit including an inner coil adjacent to the coil and an outer coil connected to the inner coil and spaced apart from the inner coil,
The number of turns of the outer coil is determined using information on a radius between the inner coil and the outer coil and information on the number of turns of the outer coil compared to the number of turns of the inner coil. delete According to claim 3,
The coil is formed in a spiral shape, and the inner coil is disposed to surround an outer side of the coil. According to claim 3,
The inner coil further includes a first inner coil disposed inside the coil. According to claim 3,
The coil is formed in a spiral shape, and the inner coil is disposed between radially disposed coils. delete delete A power supply coil unit including a power supply coil and a power supply shielding coil including a first inner coil adjacent to the power supply coil and a first outer coil connected to the first inner coil and spaced apart from the first inner coil; and
A current collecting coil unit including a current collecting coil including a current collecting coil, a second inner coil adjacent to the current collecting coil, and a current collecting shielding coil including a second outer coil connected to the second inner coil and spaced apart from the second inner coil,
The number of turns of the first outer coil is determined using information on the radius between the first inner coil and the first outer coil and information on the number of turns of the first outer coil compared to the number of turns of the first inner coil Wireless power transceiving device.
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