KR101996127B1 - Wireless power transmission system based on Coupled Electric Field - Google Patents

Abstract

The present invention relates to a wireless power transmission system based on an electric field coupling method which can guarantee a higher performance with a simpler circuit configuration, and more particularly, to a transmission device for converting a DC voltage into an AC voltage. A pair of link capacitors for wirelessly transmitting the AC voltage of the transmission device by an electric field coupling method; And a receiving device that performs impedance matching through a Leakage-Enhanced Transformer (LET) transformer that simultaneously provides a transformer function and an inductor function, converts the AC voltage transmitted through the link capacitor to a DC voltage, can do.

Description

[0001] The present invention relates to a wireless power transmission system based on an electric field coupling method,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless power transmission system, and more particularly, to a wireless power transmission system based on an electric field coupling method, which enables a more improved performance with a simpler circuit configuration.

Currently, the wireless power transmission system is used in various fields. As a typical example of the wireless power transmission system, a car or a mobile wireless charging is used. In this case, an electric field is formed in a transmitting / And a combination method.

FIG. 1 is a view for explaining a conventional electric field coupling system based wireless power transmission system.

As shown in FIG. 1 (a), a conventional wireless power transmission system includes a transmitter 10 for converting energy received in a DC form into an AC form, a receiver 20 for converting an AC voltage back to a DC voltage, , And a link capacitor (30).

1 (b) is an equivalent circuit of FIG. 1 (a). Referring to FIG. 1 (a), when the link capacitor of the wireless power transmission system is in a pico to nano unit, the voltage stress is increased by a multiple of the system resonance quality factor Q .

Therefore, it can be seen that an impedance matching network as shown in FIG. 1 (c), which is a method of canceling the impedance of the capacitor using an inductor or a transformer, must be provided on both sides of the transmitter 10 and the receiver 20 .

As a result, the conventional wireless power transmission system has disadvantages in that the impedance matching network must be provided on both sides of the transmitter and the receiver so that the system volume increases, and the system design becomes complicated. In addition, since a magnetic element must be provided on each of the transmission side and the reception side, the system power factor is lowered and the capacitor voltage stress is also increased.

1. Chunting Chris Mi, Giuseppe Buja, Su Y. Choi and Chun T. Rim, "Modern Advances in Wireless Power Transfer Systems for Roadway Powered Electric Vehicles," IEEE Trans. on Industrial Electronics, vol. 63, no. 10, pp. 6533-6545, Oct. 2016 2. Michael P. Theodoridis, "Effective Capacitive Power Transfer," IEEE Trans. on Power Electronics, vol. 27, no. 12, pp. 4906-4913, Dec. 2012 3. Sung-Jin Choi, "Design Guidelines for a Capacitive Wireless Power Transfer System with Input / Output Matching Transformers," Journal of Electrical Engineering & Technology, vol.11, no. 6, pp. 1665-1663, Nov. 2016 4. C. W. T. Mclyman, Transformer and Inductor Design Handbook, 4th ed., CRC Press, 2011 E. E. Snelling, Soft Ferrites-Properties and Applications, second ed., London Iliffe Books LTD, pp. 377-358, 1969

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, an object of the present invention is to provide an electric field coupling system based wireless power transmission system which can simplify a system configuration by providing an impedance matching network in only one of a transmitting side and a receiving side .

It is also intended to provide a wireless power transmission system based on an electric field coupling scheme in which the capacitor voltage stress is reduced and the system power factor is increased so that the system performance can be improved.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a receiving apparatus for receiving an AC voltage wirelessly transmitted in an electric field coupling manner through a link capacitor according to an embodiment of the present invention includes an LET (Leakage- An impedance matching unit for performing impedance matching through a transformer; And a rectifier for rectifying an AC voltage transmitted through the impedance matching unit to generate and output a DC voltage.

Said LET transformer comprising: an EE type core; And a primary winding and a secondary winding having a winding ratio of N: 1 and spaced from each other by a preset interval.

"의 식에 따라 계산되는 공진 양호도(Q)와 "

"의 식에 따라 계산되는 공진 주파수(f_o)를 가지며, 상기 n_eff는 유효 권선비, 상기 R_eq는 AC 등가 부하 저항, 상기 L_r는 누설 인덕턴스, 상기 C_link는 링크 캐패시터인 것을 특징으로 한다. And the LET transformer is "

Quot; Q " and "

"Has a resonance frequency (f _o) is calculated according to the formula, wherein n _eff is the effective turns ratio, the R _eq is AC equivalent load resistance, wherein L _r is the leakage inductance, the C _link may be a link capacitor .

"의 조건을 만족시키도록 최대 전압 이득(M)이 결정되며, 상기 V_cap,stress는 캐패시터 전압 스트레스, 상기 V_cap,maximum는 최대 캐패시터 전압 스트레스, 상기 Q는 공진 양호도, 상기 V_in는 입력 전압인 것을 특징으로 한다. And the LET transformer is "

"Is the maximum voltage gain (M) is determined so as to satisfy the condition, the V _{cap, stress} is the capacitor voltage stress, wherein the V _{cap, maximum} is the maximum capacitor voltage stress, the Q is the resonance quality factor, the V _in is input Voltage.

"의 식에 따라 결정되는 코어 크기를 가지며, 상기 A_e는 코어 횡단면 영역의 크기(cm²), 상기 A_w는 권선 영역 또는 코어의 크기(cm²), 상기 P_O는 출력 전력, 상기 K_f는 파형 팩터, 상기 B_max는 최대 자계 밀도, 상기 f는 스위칭 주파수, 상기 K_u는 권선 충전율, 상기 J_rms는 전류 밀도인 것을 특징으로 한다. And the LET transformer is "

Wherein A _e is the size (cm ² ) of the core cross-sectional area, A _w is the size of the winding area or core (cm ² ), P _o is the output power, K _f is a waveform factor, B _max is a maximum magnetic field density, f is a switching frequency, K _u is a winding packing rate, and J _rms is a current density.

"의 식에 따라 결정되는 1차측 권선 수(N_s)와, "

" 내지 "

"의 범위에서 결정되는 2차측 권선 수(N_p)를 가지며, 상기 N은 권선비, 상기 n_eff는 유효 권선비, 상기 k는 0.98~0.99의 상수, 상기 V_sec는 AC 등가 부하 저항(R_eq) 양단에 걸리는 전압, 상기 A_e는 코어 횡단면 영역의 크기(cm²), 상기 B_max는 최대 자계 밀도, 상기 f는 스위칭 주파수, 상기 K_f는 파형 팩터, 상기 K_u는 권선 충전율, 상기 A_w는 권선 영역 또는 코어의 크기(cm²), 상기 A_Cu는 권선 횡단면 영역의 크기(cm²), 상기 Δ는 권선 이격율인 것을 특징으로 한다. And the LET transformer is "

(N _s ) determined in accordance with the equation of "

"To"

"Can the secondary coil, which is determined in a range of (N _p) to have, wherein N is a turn ratio, the n _eff is the effective turns ratio, wherein k is (R _eq) constant, the V _sec of 0.98 ~ 0.99 is AC equivalent load resistor Wherein A f is a switching frequency, K _f is a waveform factor, K _u is a winding charging rate, A _w is a voltage applied across both ends, A _e is a size (cm ² ) of a core cross section area, B _max is a maximum magnetic field density, (Cm < ² >) of the winding area or core, A _Cu is the size (cm ² ) of the winding cross section area, and Δ is the winding spacing ratio.

"의 식에 따라 높이(h_w)와 폭(b_w)이 결정되는 권선 윈도우, "

"의 식에 따라 가로 길이(A)와 세로 길이(B)가 결정되는 코어 중앙 다리, 및 "

"의 식에 따라 결정되는 1차측 권선과 2차측 권선간 거리(s_w)를 가지며, 상기 k는 0.98~0.99의 상수, 상기 μ_o은 공기 투자율, 상기 N_p는 2차측 권선 수, 상기 l_w는 권선 평균 길이, 상기 Δ는 권선 이격율인 것을 특징으로 한다. The LET transformer is "

Quot ;, the winding window in which the height h _w and the width b _w are determined,

"And " B " are determined according to the expression"

Has a "primary-side winding and the secondary-side distance (s _w) between wires, which is determined according to the following equation, wherein k is a constant, the μ _o of 0.98 ~ 0.99 is air permeability, wherein N _p is the secondary number of turns, the l _w is an average winding length, and? is a winding separation ratio.

According to another aspect of the present invention, there is provided a wireless power transmission system based on an electric field coupling method, comprising: a transmitter for converting a DC voltage to an AC voltage; A pair of link capacitors for wirelessly transmitting the AC voltage of the transmission device by an electric field coupling method; And a receiving device that performs impedance matching through a Leakage-Enhanced Transformer (LET) transformer that simultaneously provides a transformer function and an inductor function, converts the AC voltage transmitted through the link capacitor to a DC voltage, can do.

An impedance matching unit for receiving an AC voltage wirelessly transmitted in an electric field coupling manner through the link capacitor and performing an impedance matching through the LAK (Leakage-Enhanced Transformer) transformer; And a rectifier for rectifying an AC voltage transmitted through the impedance matching unit to generate and output a DC voltage.

The transmitting apparatus includes a switching unit that converts a DC voltage to an AC voltage through a transistor-based full-bridge converter.

According to another aspect of the present invention, there is provided a wireless power transmission system based on an electric field coupling method, comprising: a DC-DC converter for converting a DC voltage to an AC voltage and outputting an LET A transmission device for performing impedance matching through a transformer; A pair of link capacitors for wirelessly transmitting the AC voltage of the transmission device by an electric field coupling method; And a receiving device for converting the AC voltage transmitted through the link capacitor to a DC voltage and delivering the DC voltage to the load.

The transmitter includes a switching unit for converting a DC voltage to an AC voltage through a transistor-based full-bridge converter; And an impedance matching unit for performing impedance matching through the LAK (Leakage-Enhanced Transformer) transformer.

The receiving apparatus includes a rectifying unit for rectifying an AC voltage transmitted through the link capacitor to generate and output a DC voltage.

The wireless power transmission system of the present invention can provide an impedance matching network in only one of the transmitting apparatus and the receiving apparatus so that the system structure can be drastically reduced.

Also, the impedance matching network can be implemented with only one LET transformer, so that the structure of the impedance matching network can be simplified.

In addition, since only one LET transformer is used for system resonance, the system power factor is increased, and the system resonance goodness is reduced in proportion to the winding ratio of the LET transformer, thereby also reducing the capacitor voltage stress.

FIG. 1 is a view for explaining a conventional electric field coupling system based wireless power transmission system.
FIG. 2 is a view for explaining an electric field coupling type wireless power transmission system according to an embodiment of the present invention. Referring to FIG.
3 is a diagram illustrating a structure of an LET transformer according to an embodiment of the present invention.
4 is a view for explaining a topology design method of an LET transformer according to an embodiment of the present invention.
5 is a graph showing a 1 / Gain curve according to the resonance frequency fo and the resonance goodness degree Q. FIG.
6 is a view illustrating a wireless power transmission system based on an electric field coupling scheme according to another embodiment of the present invention.
FIGS. 7 and 8 are diagrams for explaining a performance of a wireless power transmission system based on an electric field coupling method according to an embodiment of the present invention.

It is noted that the technical terms used in the present invention are used only to describe specific embodiments and are not intended to limit the present invention. In addition, the technical terms used in the present invention should be construed in a sense generally understood by a person having ordinary skill in the art to which the present invention belongs, unless otherwise defined in the present invention, Should not be construed to mean, or be interpreted in an excessively reduced sense. In addition, when a technical term used in the present invention is an erroneous technical term that does not accurately express the concept of the present invention, it should be understood that technical terms can be understood by those skilled in the art. In addition, the general terms used in the present invention should be interpreted according to a predefined or prior context, and should not be construed as being excessively reduced.

Furthermore, the singular expressions used in the present invention include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as "comprising" or "comprising" and the like should not be construed as encompassing various elements or various steps of the invention, Or may further include additional components or steps.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals refer to the same or similar elements, and redundant description thereof will be omitted.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. It is to be noted that the accompanying drawings are only for the purpose of facilitating understanding of the present invention, and should not be construed as limiting the scope of the present invention with reference to the accompanying drawings.

FIG. 2 is a diagram illustrating a wireless power transmission system based on an electric field coupling method according to an embodiment of the present invention. FIG. 2 (a) is a system configuration diagram and FIG. 2 (b) is an equivalent circuit.

2, a wireless power transmission system 100 of the present invention includes a transmitting apparatus 110, a receiving apparatus 120, and a link capacitor 130, and includes a receiving apparatus 120, Only one impedance matching unit 121 is provided.

The transmitting apparatus 110 includes a DC power source 111, a switching unit 112, and the like.

The DC power supply 111 generates and supplies a predetermined DC voltage V _s and the switching unit 112 is implemented as transistor-based full-bridge converters T1 to T4. The four transistors T1 to T4, The DC voltage of the DC power supply 111 is converted into an AC voltage.

The transmission apparatus 110 of the present invention further includes a control circuit (not shown) to control the turn-on / turn-off period of the four switches T1 to T4 by PWM (Pulse Wide Modulation) It goes without saying that the value can be actively varied.

The receiving apparatus 120 includes an impedance matching unit 121, a rectifying unit 122, and the like.

The impedance matching unit 121 includes an LET (Leakage-Enhanced Transformer) transformer (LET) for simultaneously providing an inductor function and a transformer function, thereby performing impedance matching for canceling the capacitor impedance.

2 (b), the LET transformer LET includes a transformer TX1 having a primary side connected to the link capacitor C _link and a secondary side connected to the output end, a series circuit connected to the primary side of the transformer, And a leakage inductance (L _r ) connected thereto. In this case, the parallel connection magnetizing inductance (L _m) that is a primary side transformer is brought to a very large value compared to the leakage inductance (L _r), it can be assumed to be open. That is, LET transformer (LET) of the present invention to the resonant LC system with a leakage inductance (L _r), minimizes the reactive power.

The rectifying unit 122 includes diode-based full-bridge rectifiers D1 to D4 and a capacitor filler C to rectify an AC voltage output from the impedance matching unit 121 to generate and stabilize a DC voltage, And supplies it to the output load R _L.

The link capacitor 130 refers to an AC-link capacitor component for electric connection formed for energy transmission in a physical separation section between the transmission apparatus 110 and the reception apparatus 120, and the transmission apparatus 110 (C _Link1 ) (C _Link2 ) between the output terminal of the receiving apparatus 120 and the input terminal of the receiving apparatus 120. [

As described above, in the present invention, the impedance matching unit 121 is provided only in the receiving apparatus 120, so that the transmitting apparatus 110 can be configured very simply.

Also, the impedance matching unit 121 is realized through a single magnetic element called an LET transformer (LET), thereby making the configuration of the impedance matching unit 121 and the receiving apparatus 120 more simple.

In addition, since there is only one magnetic element, a higher system power factor can be obtained, and the system resonance goodness (Q) also provides an effect of reducing the capacitor voltage stress according to the transformer winding ratio.

Hereinafter, the LET transformer of the present invention will be described in more detail with reference to FIGS. 3 and 4. FIG.

FIG. 3 is a side view of a transformer, and FIG. 3C is a top view of a transformer according to an embodiment of the present invention. FIG. 3B is a side view of the transformer, .

3 (a) to 3 (c), the LET transformer 131 of the present invention includes a core 310 having an EE structure, a primary winding 321 having a winding ratio of N: 1, And a secondary side winding 322.

If necessary, the primary winding 321 and the secondary winding 322 may be wound directly on the core 310. However, a bobbin 320 fitted to the core 310 of the EE structure may be additionally provided, So that the primary winding 321 and the secondary winding 322 can be formed. And an air gap 330 for physically isolating the primary side winding 321 and the secondary side winding 322 from each other.

When the LET transformer 131 has such a structure, the leakage inductor L _r is naturally formed based on the difference in the number of flux linkages between the primary winding N _P and the secondary winding N _S , (L _m ) is not formed separately. That is, it can be assumed that a magnetizing inductance L _m having a very large value compared to the leakage inductance L _r is generated.

If the magnetizing inductance L _m has a very large value (for example, five times or more) as compared with the leakage inductance L _r , the magnetizing inductance L _m in the equivalent circuit of the LET transformer 131 becomes It can be assumed that it is almost open.

Under this assumption, the equivalent circuit of the LET transformer 131 can be interpreted based on the APR (All Primary Referenced) model, and the AC equivalent load resistance (R _eq ) seen in front of the rectifier and the maximum voltage gain Can be calculated through Equations (1) and (2).

[Equation 1]

&Quot; (2) "

Where V _oFHA and V _iFHA are the fundamental sine input and output, respectively, and n _eff, f _o , Q can be expressed by Equation (3).

&Quot; (3) "

Where f is the switching frequency, f _o is the resonant frequency, and n _eff is the effective winding ratio.

4 is a view for explaining a topology design method of an LET transformer according to an embodiment of the present invention.

First, in step S1, information on the output voltage (V _o ), the input voltage (V _in ), the link capacitor (C _link ), and the load resistance (R _L ) is obtained.

In step S2, the resonance frequency _fo and the maximum voltage gain M are selected and the operating state is determined.

5 is a graph showing a 1 / Gain curve according to the resonance frequency f _o and the resonance goodness degree Q. Referring to this, when the Q value is too large, the capacitor voltage stress (V _{cap, stress} ) Is less than 1, it can be understood that the FHA (Fundamental harmonic approximation) is not established.

In the present invention, the resonance frequency _fo and the maximum voltage gain M are determined on the basis of Equation (4) in consideration of the capacitor voltage stress ( _{Vcap, stress} ) and the receiving apparatus size. That is, the resonant frequency is determined such that the capacitor voltage stress (V _{cap, stress} ) is smaller than the maximum capacitor voltage value (V _{cap, maximum} ) and the size of the receiving device is not too large.

&Quot; (4) "

In step S3, the core size of the LET transformer is determined on the basis of the area calculating equation of Equation (5) under the assumption that the switching frequency and the resonant frequency are similar.

&Quot; (5) "

Where A _e is the size of the core cross-sectional area (cm ² ), A _w is the size of the winding area or core (cm ² ), K _f is the waveform factor (4: square wave, 4.44 sine wave), B _max is the maximum magnetic field density (0.3T: ferrite saturation), f is the switching frequency, K _u is the winding fill factor (typically 0.3 to 0.6), J _rms is the current density (Typically, 500 A / cm ² ), and P _O is the output power.

In step S4, the primary winding number N _p and the secondary winding number N _s of the LET transformer are determined.

The secondary number of turns (N _s) is determined within a range of Equation 6 and 7. Equation (6) is an expression representing the correlation between the saturation limit and the number of windings, and Equation (7) is an expression representing the correlation of the number of tube windings in the maximum winding window area.

&Quot; (6) "

&Quot; (7) "

Where V _sec is the voltage across the AC equivalent load resistance (R _eq ) of the receiver, A _Cu is the size of the winding cross section area, and Δ is the winding separation.

The number of primary turns is determined by Equation (8) only when the k value of the LET transformer is known, and the k value is generally 0.98 to 0.99.

&Quot; (8) "

In step S5, the distance (s _w ) between the primary side and the secondary side of the LET transformer is determined.

If the frequency selected in step S2 is used, the value of the leakage inductor L _r can be known. As in the present invention, when fabricating the LET transformer to one-another structure above the EE-core structure, L _r value can be calculated from Equation (9) below.

&Quot; (9) "

Where h _w and b _w are the height and width of the winding window area, and μ _o is the air permeability. _Lw is the average length turn, and? Is the winding spacing, which can be calculated using Equation (10).

&Quot; (10) "

At this time, A and B are the width and length of the core.

And the winding separation rate (?) Can be expressed by Equation (11).

&Quot; (11) "

Then, the distance s _w between the primary-side winding and the secondary-side winding can be obtained by using? Calculated from the equation (11).

As described above, the present invention is the core and the N in the EE type: have a turns ratio of 1, suggested a LED transformer having a preset interval spaced primary and secondary windings, and the resonance frequency (f _o) and By optimizing its topology in consideration of the maximum voltage gain (M), etc., the LED transformer can have reduced capacitor voltage stress.

In the above description, the case where the impedance matching unit 121 is provided in the receiving apparatus 120 has been described. However, it will be appreciated that the transmitting apparatus may be provided with an impedance matching network instead of the receiving apparatus if necessary.

6, the wireless power transmission system according to another embodiment of the present invention includes a transmitter 110 'including a DC power source 111, a switching unit 112, and an impedance matching unit 113 And the receiving apparatus 120 can include only the rectifying unit 122. [

If the turns ratio of the transformer LET (LET) N: If the first, can be calculated according to equation 12 and 13, good resonant system also (Q) and the resonance frequency (f _O).

&Quot; (12) "

&Quot; (13) "

That is, referring to Equation 12 and 13, in the case of the LET transformer (LET), system resonance quality factor (Q) is decreased by the turn ratio (N) to a capacitor voltage stress is reduced, and the resonance frequency (f _O) is N times . ≪ / RTI >

On the other hand, LET transformer (LET) turns ratio is 1: If N, good system resonance also (Q) is the increase in capacitor voltage stress increases by winding ratio as shown in Equation 14, the resonance frequency (f _O) is Equation (15) As shown in FIG.

&Quot; (14) "

&Quot; (15) "

At this time, C _link is a value obtained by serially connecting a pair of link capacitors (C _Link1 and C _Link2 ).

If the size of the receiving device is important and the stress of the capacitor voltage is important, and if the system has a high frequency, the winding ratio of the transformer should be N: 1, the size of the receiving device to be used is important, For systems with large margins and low frequency applications, the transformer turns ratio should be 1: N.

And by performing the topology design method of FIG. 4 based on the system resonance goodness measure Q and the resonant frequency f _{o of} equations 12 and 13 or equations 14 and 15, the LET transformer suitable for the system of FIG. 6 also So that it can be designed.

FIGS. 7 and 8 are diagrams for explaining the performance of a wireless power transmission system based on an electric field coupling method according to an embodiment of the present invention. FIG. 7A is a simulation waveform diagram, FIG. Fig. 8 (a) shows the result of the comparison of the total volume of the magnetic field, and Fig. 8 (b) shows the comparison result of the total loss of the magnetic field.

The output power is 5W, the load resistance is 20Ω (10V / 0.5A), the link capacitor C _link is set to 1nF, the coupling coefficient is set to 0.990, and the input voltage is set to 50V. By designing the topology of the present invention, (Q) is 1, the winding ratio N is about 5, L _r is about 158.3 uF, and the LET transformer having the specification as shown in Table 1 is designed.

디자인 규격 core type EE2519 effective turn ratio (n _eff ) 5 # of turns (pri.) 66 # of turns (sec.) 12 winding separation (s _w ) 3.3 mm wire size (pri.) 0.06 / 20 litz wire size (sec.) 0.1 / 40 litz relative permeability 2400 (PL-7) 측정 결과 series resonant inductor (L _r ) 184.48uH parallel resonant inductor (L _m ) 10.18mH effective turn ratio (n _eff ) 5.12

When the PISM simulation is performed based on this, the simulation waveform of FIG. 7A is obtained.

As a result of implementing and operating the wireless power transmission system according to the designed specifications, the resonance frequency f _o is measured by 361.61 KHz as shown in FIG. 7 (b), which is about 10% different from the simulation result, Is 180mA, and the voltage across C _link1 is measured as 32V at maximum, which is almost identical to the simulation result.

In addition, if the wireless power transmission system according to the prior art described above and the wireless power transmission system according to the present invention are implemented under the same conditions, as shown in FIGS. 8A and 8B, It can be seen that the system has a total volume of the magnetic field about four times smaller than that of the related art and a total loss of the magnetic field about three times smaller than the conventional one.

The features, structures, effects and the like described in the foregoing embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified in other embodiments by those skilled in the art to which the embodiments belong.

Therefore, it should be understood that the present invention is not limited to these combinations and modifications. While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiments may be modified and implemented. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

Claims (13)

A receiving apparatus for receiving an AC voltage wirelessly transmitted in an electric field coupling manner via a link capacitor,
An impedance matching unit that performs impedance matching through a LAK (Leakage-Enhanced Transformer) transformer, which is a magnetic device that simultaneously provides a transformer function and an inductor function; And
And a rectifier for rectifying an AC voltage transmitted through the impedance matching unit to generate and output a DC voltage,
The LET transformer includes:
core; And
A primary winding and a secondary winding wound around the core and having a winding ratio of N: 1 and spaced a predetermined interval,
Wherein a winding separation ratio between the primary winding and the secondary winding is obtained on the basis of the leakage inductance, the height and width of the winding window region, the number of primary turns, and the length and length of the core.
delete The LET transformer according to claim 1,
Wherein the leakage inductance is calculated using a frequency determined according to the following equation (1).
[Equation 1]

"

"
Here, Q denotes the resonance goodness degree, f _o denotes the resonance frequency, n _eff denotes the effective winding ratio, R _eq denotes the AC equivalent load resistance, L _r denotes the leakage inductance, C _link means a link capacitor. 4. The LET transformer of claim 3,
And the resonance frequency is determined according to the following formula (2).
&Quot; (2) "
"

"
Here, V _{cap, stress} is the capacitor voltage stress, V _{cap, maximum} is the maximum capacitor voltage stress, Q is the resonance goodness degree, and V _in is the input voltage. The LET transformer according to claim 4,
Wherein the size of the core of the LET transformer is determined by the following formula (3).
&Quot; (3) "
"

"
Here, the A _e is the effective size (cm ²⁾ of the core cross-section, the A _w is ⁽² cm) the effective size of a winding window area, the P _O is the output power, the K _f is the waveform factor, the B _max is the maximum Wherein f is a switching frequency, K _u is a winding packing rate, J _rms is a current density, and the switching frequency is the resonance frequency. 6. The LET transformer of claim 5,
The primary side turn number N _p is calculated according to the following equation (4)
Wherein the winding separation rate is determined according to the following formulas (5) to (7).
&Quot; (4) "
"

",
Where N is the winding ratio, n _eff is the effective winding ratio, k is a constant of 0.98 to 0.99,
&Quot; (5) "

&Quot; (6) "

&Quot; (7) "

Here, h _w and b _w mean the height and width of the winding window region, A and B mean the width and length of the core, and S _w means the distance between the primary winding and the secondary winding , l _w means the average winding length, μ _o denotes the magnetic permeability, and air, Ns is the number of secondary coil, and Δ means the winding yigyeokryul. 7. The LET transformer of claim 6,
To the receiving device characterized in that the range of the secondary number of turns (N _s) determined by the equation 8].
&Quot; (8) "

,

Here, the V _sec are AC equivalent load resistor (R _eq) voltage across the A _e is in the core cross section of effective size (cm ^2), the B _max is the maximum magnetic field density, wherein f is the switching frequency, and the K _f is the waveform factor and the K _u is wound packing ratio, the a _w is the effective size (cm ^2), the _Cu of the coil window area a is the cross-sectional area (cm ²⁾ is occupied by a winding, wherein the Δ is spaced winding ratio. A transmitting device for converting a DC voltage into an AC voltage;
A pair of link capacitors for wirelessly transmitting the AC voltage of the transmission device by an electric field coupling method; And
An impedance matching is performed through a Leakage-Enhanced Transformer (LET) transformer, which is a magnetic element that simultaneously provides a transformer function and an inductor function, and the AC voltage transmitted through the link capacitor is converted into a DC voltage, Receiving device,
The LET transformer includes:
core; And
A primary winding and a secondary winding wound around the core and having a winding ratio of N: 1 and spaced a predetermined interval,
Wherein the LC system of the LET transformer is resonated only by a leakage inductance formed on the basis of a difference in the number of flux linkages between the primary winding and the secondary winding. 9. The apparatus of claim 8, wherein the receiving device
An impedance matching unit for receiving an AC voltage wirelessly transmitted in an electric field coupling manner through the link capacitor and performing an impedance matching through the LAK (Leakage-Enhanced Transformer) transformer; And
And a rectifier for rectifying an AC voltage transmitted through the impedance matching unit to generate and output a DC voltage. The apparatus as claimed in claim 8, wherein the transmitting apparatus
And a switching unit for converting a DC voltage to an AC voltage through a transistor-based full-bridge converter. A transmitter that converts impedance of the DC voltage to an AC voltage and performs impedance matching through a Leakage-Enhanced Transformer (LET) transformer, which is a magnetic element that simultaneously provides a transformer function and an inductor function;
A pair of link capacitors for wirelessly transmitting the AC voltage of the transmission device by an electric field coupling method; And
And a receiving device for converting the AC voltage transmitted through the link capacitor to a DC voltage and delivering the DC voltage to the load,
The LET transformer includes:
core; And
A primary winding and a secondary winding wound around the core and having a winding ratio of N: 1 and spaced a predetermined interval,
Wherein a distance between the primary winding and the secondary winding is a distance
Obtaining information on an output voltage, an input voltage, a link capacitor, and a load resistance,
The resonant frequency having the maximum voltage gain is selected in consideration of the capacitor voltage stress and the receiving device size,
Determining an effective winding ratio and a leakage inductance based on the resonance frequency,
Determining a core size of the LET transformer on the assumption that the switching frequency is the resonant frequency,
Calculate the number of turns on the secondary side and the number of turns on the primary side using the voltage across the AC equivalent load resistor and the effective size of the cross section of the core,
Side winding and the secondary winding, using the leakage inductance, the height and width of the winding window region, the number of turns of the primary side, the transverse length and the longitudinal length of the core, and the winding spacing of the primary winding and the secondary winding. Wherein the distance between the first and second antennas is calculated. 12. The apparatus of claim 11, wherein the transmitting device
A switching unit for converting a DC voltage to an AC voltage through a transistor-based full-bridge converter; And
And an impedance matching unit that performs impedance matching through the LAK (Leakage-Enhanced Transformer) transformer. 12. The apparatus of claim 11, wherein the receiving device
And a rectifier for rectifying an AC voltage transmitted through the link capacitor to generate and output a DC voltage.

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