KR20150117005A - Flexible wireless power collection apparatus - Google Patents

Abstract

The present invention relates to a collecting device in a wireless power transmitting system. The collecting device includes a secondary coil generating an induced current by being induced by an electromagnetic field resonated by a predetermined frequency from the collecting device; an impedance matching part connected to both ends of the secondary coil to be resonated by the same frequency as the predetermined frequency by being combined with the secondary coil; a rectifying circuit rectifying the induced current, induced to the secondary coil, into a DC current by being connected to an output terminal of the impedance matching part; and a support supporting the secondary coil, the impedance matching part, and the rectifying circuit. The support is formed of a flexible material.

Description

[0001] Flexible wireless power collection apparatus [0002]

The present invention relates to a wireless power collecting apparatus, and more particularly, to a wireless power collecting apparatus that increases a power transmission distance by supplying high-voltage AC power to a primary coil of a power supply apparatus, The present invention relates to a flexible power collector having a feature capable of curved surface deflection in a current collector that compensates for a transmission efficiency deteriorated as approaching a car coil.

In recent years, users' preference for portable electronic devices has been increasing, and these electronic devices have become essential elements for providing a ubiquitous environment to users. Various electronic devices supporting communication functions are moving from a communication method using wire cables such as a telephone line, a network cable and a headphone cable to a communication method using wireless such as Bluetooth and wireless LAN. Currently, rechargeable batteries are mostly responsible for the power supply of portable electronic devices, so the introduction of wireless charging technology in the field of battery charging in the future will be a breakthrough.

Such wireless charging techniques can be roughly classified into electromagnetic induction, magnetic resonance, and electromagnetic wave.

In the electromagnetic induction method, the alternating magnetic field is generated in the transmitting part, and the current is induced according to the change of the magnetic field in the receiving part to generate energy. The magnetic resonance method converts a power into an electromagnetic field that resonates in the transmitter and transmits the electromagnetic field, and receives power by using a resonance coil having the same resonance frequency in the receiver.

Finally, the electromagnetic wave (RF) method converts energy into microwave which is advantageous for wireless transmission and transmits energy.

One of the major technical issues in wireless power transmission technology is to increase the power transmission distance, and in this respect, the magnetic resonance method has advantages over the magnetic induction method. However, due to an increase in the size of the secondary coil required to secure a constant power transmission distance, it is difficult to implement the antenna in a small receiving device such as a mobile device or a medical device in a living body.

On the other hand, there is a method of increasing the strength of the magnetic field generated by the resonance coil by amplifying the voltage applied to the power-supply-side resonance coil, thereby increasing the power transmission distance. Korean Utility Model Publication No. 2012-0033758 discloses that a coil (electromagnetic field generator) 411 is provided separately from a resonance coil (electromagnetic field resonator) 412 on the power feeding side in order to amplify a voltage applied to the power-supply side resonance coil, And a method of amplifying the voltage or current applied to the resonance coil by the principle of the transformer between the resonance coil and the resonance coil. However, the amplifier using the transformer principle has a disadvantage in that it can be limitedly used depending on the size of the feeding device due to the increase of the size of the device.

In addition, since curved smart phones are being released as a trend of smart phones in recent years, and the use of wearable electronic devices has been expanded, it has been difficult to implement a magnetic induction type wireless charging current collector corresponding thereto, Was desired.

In order to solve the above problems, it is an object of the present invention to provide a wireless power collecting apparatus which is applicable to flexible electronic apparatuses by providing a flexible power collecting apparatus.

Another object of the present invention is to provide a power collecting apparatus which has a charging system that can effectively shield a signal such as noise generated in a load unit while solving the problem of a decrease in transmission efficiency appearing in a region close to the power supply apparatus There is.

According to an aspect of the present invention, there is provided a current collector of a wireless power transmission system, comprising: a secondary coil that is induced by an electromagnetic field resonating at a predetermined frequency from a power feeding device of the wireless power transmission system to generate an induced current; An impedance matching unit connected to both ends of the secondary coil and resonating at the same frequency as the predetermined frequency in association with the secondary coil; A rectifying circuit connected to an output terminal of the impedance matching unit and rectifying the induction current induced in the secondary coil to a direct current; And a supporting member for supporting the secondary coil, the impedance matching unit, and the rectifying circuit, wherein the supporting member is made of a flexible material, and the secondary coil is located within a predetermined distance from the primary coil of the power feeding device, And the secondary coil receives power from the power supply device through an electromagnetic induction method when the resonance between the secondary coil and the secondary coil is broken.

The present invention also relates to a method of manufacturing a semiconductor device, wherein the support is at least one selected from the group consisting of polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polycarbonate (PC), polyethylene sulfone (PES), polyimide PAR), polycyclic olefin (PCO), crosslinked epoxy, and crosslinked urethane film. The present invention also provides a flexible wireless power collector.

The present invention also provides a flexible wireless power collecting apparatus characterized in that the thickness of the support is 0.01 to 1 mm.

The present invention also provides a flexible wireless power collecting apparatus characterized in that the thickness of the support is 0.1 to 0.5 mm.

The present invention also provides a flexible wireless power collecting apparatus, wherein the impedance matching unit includes a first capacitor connected to one side of the secondary coil and a second capacitor connected to the other side of the secondary coil.

The first capacitor and the second capacitor of the present invention may shield the parasitic impedances of the first capacitor and the second capacitor at the time of calculating the input impedance of the power supply device of the wireless power transmission system To provide a flexible wireless power collecting device.

And the first capacitor and the second capacitor of the present invention have capacitances equal to each other.

Further, the present invention provides a current collector of a wireless power transmission system, wherein the rectifier circuit is implemented by a bridge rectifier in which four diodes are coupled by a bridge.

The present invention also provides a flexible wireless power collecting device, wherein the power collecting device is connected to an output terminal of the rectifying circuit in parallel to smooth the output power of the rectifying circuit.

The present invention further provides a flexible wireless power collecting apparatus, wherein the power collecting apparatus further includes a load unit connected to an output terminal of the rectifying circuit to consume rectified power.

The present invention also provides a flexible wireless power collecting apparatus, wherein the load unit includes a charging circuit for charging the secondary battery using the rectified power.

The wireless power collecting apparatus according to the present invention has an effect that the support is formed of a flexible polymer and is applicable to a flexible electronic apparatus by providing a flexible power collecting apparatus.

Further, the present invention can efficiently supply high-voltage AC power to the primary coil by generating AC power from a DC power supply using a switching element and amplifying the generated AC power again using an LC resonance circuit, By amplifying the power using a passive element in addition to the element, power conversion loss is small, which is advantageous in miniaturizing the size of the current collector.

Further, unlike other amplifiers or transformer-type amplifiers that can be used to supply high-voltage AC power to the primary coil, the present invention does not amplify an input signal but uses an input signal as a switching signal to supply a DC The voltage can be efficiently changed to an AC signal.

Further, by supplying high-voltage AC power to the primary coil, the present invention can provide an electromagnetic induction-type electromagnetic induction method using a strong electromagnetic field generated from the primary coil even in a situation where resonance is broken due to the proximity of the primary coil and the secondary coil within an optimum distance. Power is supplied to the car coil, thereby eliminating dead zones.

Further, the present invention provides a magnetic field strength adjusting unit capable of adjusting the intensity of an electromagnetic field generated by a primary coil, thereby effectively forming a magnetic field space, i.e., a wireless charging space, corresponding to various human / have.

Further, by connecting the impedance matching portions to both ends of the secondary coil of the current collector, it is possible to solve the problem of lowering the transmission efficiency of the current collector in the region close to the power feeder, There is an effect of shielding.

FIG. 1 schematically shows a form of a flexible current collector according to an embodiment of the present invention.
2 is a schematic block diagram of a power collecting apparatus of a wireless power transmission system according to an embodiment of the present invention.
3 is a schematic block diagram of a power collecting apparatus of a wireless power transmission system according to another embodiment of the present invention.
4 is an exemplary circuit diagram illustrating the current collector of Fig.
5 is a schematic block diagram of a power supply device corresponding to a power collecting device of a wireless power transmission system according to an embodiment of the present invention.
Fig. 6 is an exemplary circuit diagram of a switching element, a magnetic field intensity adjusting section, an LC resonant inverter, and a primary coil.
Figure 7 shows the voltage and current waveforms of the circuit of Figure 6;
8 is a view for explaining a change in mutual inductance according to the distance between the power supply coil and the current collector coil.
9 is a graph showing power transmission efficiency according to the distance between the power supply coil and the current collector coil.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that, in the drawings, the same components or parts have the same reference numerals as much as possible. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted so as to avoid obscuring the subject matter of the present invention.

The terms " about ", " substantially ", etc. used to the extent that they are used herein are intended to be taken to mean an approximation of, or approximation to, the numerical values of manufacturing and material tolerances inherent in the meanings mentioned, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.

The radio power transmission system of the magnetic resonance method described in the present invention includes a power feeding device for converting electric power into an electromagnetic field for resonance and transmitting the electric power and a power collecting device for receiving electric power using a resonance coil having the same resonance frequency as the power supply side resonance coil do.

FIG. 1 is a schematic view of a flexible power collector according to an embodiment of the present invention, and FIG. 2 is a schematic block diagram of a power collector of a wireless power transmission system according to an embodiment of the present invention.

The current collector according to the present invention can be flexibly formed to have flexibility, so that it can be applied to a flexible device such as a curved smart phone or a wearable electronic device. The degree of bending can be freely set up and down and left and right as shown in Figs. 1 (a) and 1 (b).

2, the power collecting apparatus 100 includes a secondary coil 110, an impedance matching unit 120, a rectifying circuit 130, a smoothing circuit 140, and a load unit 150. The flexible wireless power collector according to the present invention includes the secondary coil 110, the impedance matching unit 120, the rectifying circuit 130, the smoothing circuit 140, the load unit 150, Not shown).

The secondary coil 110 has a resonance frequency coinciding with the resonance frequency of the magnetic field formed by the primary coil of the power supply device, and thus receives power from the current collector device by forming a resonance channel with the primary coil.

The impedance matching unit 120 is connected to the secondary coil 110 to adjust the resonance frequency of the secondary coil by compensating the impedance, and in calculating the input impedance of the primary coil, impedance matching of the secondary coil 110 It has an effect of shielding the parasitic impedance and the like of the rear end of the part 120. [

The rectifying circuit 130 rectifies the alternating current generated in the secondary coil 110 to a direct current. The rectifying circuit 130 may be composed of various types of rectifying circuits such as a half-wave rectifying circuit, a full-wave rectifying circuit, a bridge rectifying circuit, and a double voltage rectifying circuit.

The smoothing circuit 140 smoothes the output voltage rectified by the rectifying circuit 130.

Specifically, the smoothing circuit 140 is connected in parallel to the output terminal of the rectifying circuit 130, and can smooth the output power of the rectifying circuit 130.

The load section 150 consumes the rectified DC power. Specifically, the load unit 150 receives the DC converted power through the rectifying circuit 130 and the smoothing circuit 140, and performs a desired function of the power receiving apparatus. In implementation, the load unit 150 may include a charging circuit and a secondary battery, and the secondary battery may be charged using a rectified DC power source. In particular, the charging circuit may include a protection circuit such as an overvoltage and an overcurrent prevention circuit, a temperature sensing circuit, and the like, and may include a charge management module that collects and processes information such as the state of charge of the secondary battery.

The support is characterized by being made of a flexible material, and it is made of a flexible material so that the current collector can have a flexible characteristic. Accordingly, the secondary coil 110, the impedance matching unit 120, the rectifying circuit 130, the smoothing circuit 140, and the load unit 150 can be supported on the support. The shapes in which the secondary coil 110, the impedance matching unit 120, the rectifying circuit 130, the smoothing circuit 140, and the load unit 150 are supported may be formed on one side of the support or inside the support .

Examples of the case where the support is formed inside the support include two sheets of thin supports each having a secondary coil 110, an impedance matching unit 120, a rectifying circuit 130, a smoothing circuit 140, (150) is positioned and then adhered.

The flexible material constituting the support is preferably made of a polymer material. Examples of such supports include polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polycarbonate (PC), polyethylene sulfone (PES), polyimide (PI), polyarylate , Polycyclic olefin (PCO), crosslinked epoxy, crosslinked urethane film, and the like.

On the other hand, the thickness of the support is preferably 0.01 to 1 mm, more preferably 0.1 to 0.5 mm. When the thickness is within the above-mentioned range, the current collector can be made flexible, so that the shape deformation can be made freely according to the flexible electronic equipment.

3 is a schematic block diagram of a power collecting apparatus of a wireless power transmission system according to another embodiment of the present invention.

As shown in FIG. 3, in the present embodiment, the impedance matching units may be arranged in series at both ends of the secondary coil 210. That is, the first impedance matching unit 220 may be connected to one end of the secondary coil 210, and the second impedance matching unit 225 may be disposed at the other end.

The sum of the capacitive reactances of the two impedance matching parts 220 and 225 is matched with the inductive reactance of the secondary coil 210 so that the two impedance matching parts 220 and 225 and the secondary coil 210 are fed Resonates at the same frequency as the resonance frequency of the device. The electric field and the magnetic field oscillating at the resonance frequency near the primary coil resonate with the secondary coil resonating at the same resonance frequency.

The rectifier circuit 230 is connected to the output terminals of the first impedance matching unit 220 and the second impedance matching unit 225. A smoothing circuit 240 is connected to the output terminal of the rectifying circuit 230 to smoothen the rectified power and a rectifier 250 is connected to an output terminal of the smoothing circuit 240 to supply rectified power.

4 is an exemplary circuit diagram illustrating the current collector of Fig.

Referring to FIG. 4, one side of the first capacitor 320 is connected to one side of the secondary coil 310, and one side of the second capacitor 325 is connected to the other side of the secondary coil 310. The rectifier circuit 230 of FIG. 3 is implemented by a bridge rectifier circuit 330, which is a full-wave rectifier circuit composed of four diodes in FIG. 4. The other side of the first capacitor 320 and the other side of the second capacitor 325 are connected to a bridge Is connected to the input terminal of the rectifier circuit (330). The smoothing circuit 240 and the load unit 250 of FIG. 3 are schematically represented by a smoothing capacitor 340 and a resistor 350.

In this embodiment, the first capacitor 320 and the second capacitor 325 are disposed at both ends of the secondary coil 310, so that a capacitor that performs an impedance matching function only at one side of the secondary coil 310 It is possible to effectively shield the non-periodic repulsive signal generated at the load side as compared with the arrangement of the secondary coil, and to shield the parasitic impedance or the like of the rear end of the impedance matching portion of the secondary coil in calculating the input impedance of the primary coil It is effective.

At this time, the capacitor carries only the AC component without transmitting the DC component delivered from the secondary coil 310 to the subsequent stage. The circuit shown in FIG. 4 is an embodiment of the present invention, and the present invention is not limited to this, and includes all the impedance matching units that function to prevent the resonance frequency change due to the parasitic impedance.

It is preferable that the first capacitor 320 and the second capacitor 325 have the same capacitance. In this case, voltages opposite to each other are applied to the capacitors 320 and 325, A smoothed voltage corresponding to twice the voltage applied to one of the capacitors 320 and 325 is applied to both ends of the smoothing capacitor 340 to which a rectified voltage is applied by the rectifying circuit 230.

5 is a schematic block diagram of a power supply device corresponding to a power collecting device of a wireless power transmission system according to an embodiment of the present invention.

5, the power feeding device 400 includes a power supply unit (not shown), a frequency generator 410, a power amplifier 430, a switching unit 440, an LC resonance inverter 450, a Magnetic Field Strength Controller 460, and a primary coil 470.

A power supply unit (not shown) supplies power to each configuration of the power supply device 400. Specifically, the power supply unit receives power supplied from the outside of the power supply device 400, converts the power to a voltage necessary for each configuration in the power supply device 400, and supplies the converted power to each configuration of the power supply device 400 have.

The frequency generator 410 generates a power carrier signal having a predetermined frequency required for power transmission.

The power amplifier 430 regulates the signal level of the power carrier signal applied to the switching device 440. The input power carrier signal is preferably biased to be close to the pinch-off voltage of the switching device 440.

The switching element 440 operates as an ON-OFF switch driven according to the power carrier signal, and is turned ON when the signal level of the power carrier signal is High and OFF when it is Low. The switching element 440 may be implemented as a BJT, a MOSFET, a MESFET, or the like.

The LC resonant inverter 450 generates AC power from the DC power source through the switching operation of the switching device 440 and forms the LC resonance circuit with the generated AC power to generate AC power at a high voltage Conversion. Here, the resonance frequency of the LC resonance circuit is equal to the oscillation frequency of the power carrier signal generated in the frequency generator 410.

The magnetic field intensity adjusting unit 460 adjusts the intensity of the electromagnetic field generated in the primary coil 470 by changing the impedance value of the LC resonant inverter 450 viewed from the primary coil side. That is, by adjusting the magnitude of the AC voltage amplified in the primary coil 470, the intensity of the electromagnetic field generated in the primary coil 470 can be adjusted, and as a result, the power transmission distance can be controlled. The impedance of the power transmission channel between the power feeding device 400 and the power collecting device can be changed according to the environment in which the power feeding device 400 is disposed and the power transmission distance required by the user using the power feeding device or the location of the power feeding device Can be different. Accordingly, by controlling the intensity of the magnetic field generated in the primary coil 470, a magnetic field space, that is, a wireless charging space can be efficiently formed in response to various human / environmental factors.

The primary coil 470 is coupled to the secondary coil of the current collector with a resonant frequency to transmit the resonant power to the secondary coil. That is, the primary coil 470 supplied with the high-frequency power by the LC resonant inverter 450 forms an electromagnetic field oscillating at a resonant frequency. Therefore, the energy supplied to the primary coil 470 exists as an electric field and a magnetic field that vibrate at a resonant frequency in the vicinity of the primary coil 470. At this time, if a secondary coil is placed near the primary coil 470, the resonance frequency of the secondary coil coincides with the resonance frequency of the magnetic field, so that an energy transmission path is formed between the primary coil 470 and the secondary coil And electric power is transmitted to the power collector side.

The power feeding device 400 may further include a magnetic polarity controller 420. The magnetic polarity controller 420 inverts the phase of the power carrier signal applied to the switching device 440 and consequently controls the polarity of the electromagnetic field generated by the primary coil 470. The magnetic polarity controller 420 may be implemented as a simple inverter and may be located at the next stage of the frequency generator 410 or at the next stage of the power amplifier 430.

The operation of the switching device 440, the LC resonant inverter 450, the magnetic field intensity adjusting unit 460, and the primary coil 470 will be described with reference to the drawings.

Fig. 6 is an exemplary circuit diagram of a switching element, a magnetic field intensity adjusting section, an LC resonant inverter, and a primary coil.

6 illustrates a case in which the MOSFET 441 is used as the switching element 440. In FIG.

The power carrier signal is applied to the gate terminal of the MOSFET 441 to control the ON-OFF state of the MOSFET 441. The input power carrier signal is biased to be close to the pinch-off voltage of the MOSFET 441. The drain terminal of the MOSFET 441 is connected to the DC power source through the inductor L1 451 and the source terminal of the MOSFET 441 is connected to the ground. When the MOSFET 441 is in the ON state, the MOSFET 441 acts as a short circuit to the ground to make the voltage (V _D ) at the drain side node zero.

When the MOSFET 441 is changed from the ON state to the OFF state, the voltage V _{D at the} drain side node is increased. This is because a counter electromotive force is induced in the inductor L1 (451) to suppress a current change, so that the current continues to flow from the inductor L1 (451) even after the MOSFET 441 is turned off, and the charge is accumulated in the capacitor C1 (452). The charge accumulated in the capacitor C1 452 starts to flow toward the capacitor C2 453 after a certain time, so that the voltage V _{D at the} drain side node stops increasing but rather decreases. The voltage (V _D ) at the drain side terminal becomes 0 again before the MOSFET 441 is again turned on.

The capacitor C2 (453) and the primary coil L2 (471) constitute an LC series resonance circuit and operate as a resonance circuit in which energy is exchanged with each other. That is, the voltage (V _D ) at the drain side node is amplified by the LC resonant circuit to which the capacitor C2 453 and the primary coil L2 471 are coupled and consequently a very high voltage is applied to the primary coil L2 471 . The resonance frequency of the LC resonance circuit matches the oscillation frequency of the power carrier signal generated by the frequency generator, and thus the power that the primary coil L2 471 transmits to the electromagnetically coupled secondary coil is the inductor L1 451, Lt; RTI ID = 0.0 > DC < / RTI >

Here, the voltage V _i of the gate terminal, the current i _L flowing in the inductor L 1 451, the current i _D flowing to the drain terminal, the voltage V _D of the drain terminal, the current i _C flowing in the capacitor C1 452, The voltage V _O across the car coil L2 471 will be described with reference to FIG.

Figure 7 shows the voltage and current waveforms of the circuit of Figure 6;

7, the voltage (V _D ) at the drain terminal of the MOSFET 441 is 0 while the MOSFET 441 is in the ON state. When the voltage V _i applied to the gate becomes lower than the threshold value of the MOSFET 441, the MOSFET 441 is cut off, and the voltage V _D of the drain terminal rises . When the current i _C flowing to the capacitor C1 452 becomes zero, the voltage (V _D ) at the drain terminal reaches the peak. When the current flowing through the capacitor C1 (452) becomes negative, the voltage (V _D ) at the drain terminal starts to decrease. Before the MOSFET 441 is again turned ON, the voltage (V _D ) at the drain terminal reaches zero. When the voltage (V _D ) at the drain terminal is applied to the LC resonance circuit passing only the fundamental frequency of the drain voltage waveform, V _O of the waveform as shown is generated.

On the other hand, the magnetic field intensity adjusting section 460 is connected to the contacts of the capacitor C2 453 and the primary coil L2 471 constituting the series resonance circuit, and is connected to the LC resonance inverter 450), it is possible to control the intensity of the electromagnetic field radiated by the primary coil L2 (471). 3 illustrates an example of a magnetic field strength adjusting unit 460 including one variable capacitor VC1 461 and a capacitor C3 462 and a diode D1 463 connected in parallel between the variable capacitor VC1 461 and the ground . A small capacitance change of the variable capacitor VC1 461 when the capacitor C2 453 and the primary coil L2 471 resonate at a resonance frequency substantially equal to the oscillation frequency of the power carrier signal also causes a large influence on the resonance voltage .

The diode D1 463 can function as a protection diode for preventing circuit damage due to external surge voltage or the like.

As described above, in the present embodiment, AC power is generated from the DC power source and amplified by using the LC resonance circuit, so that loss due to power conversion does not occur ideally. However, a slight power conversion loss occurs due to the internal resistance of the switching element in actual implementation.

8 is a view for explaining a change in mutual inductance according to the distance between the power supply coil and the current collector coil.

As described above, the energy supplied to the primary coil 711 exists as an electric field and a magnetic field that vibrate at a resonant frequency in the vicinity of the primary coil 711. Since the resonance frequency of the secondary coil 751 coincides with the resonance frequency of the magnetic field when the secondary coil 751 is placed near the primary coil 711 at this time, the primary coil 711 and the secondary coil 751 The energy transmission path is formed and power is transmitted to the current collector side.

When the current collector 750 is moved or the direction is changed while the primary coil 711 and the secondary coil 751 are coupled at the same resonance frequency, the current flows between the primary coil 711 and the secondary coil 751 The mutual inductance M changes. As a result, when the transmission efficiency is moved away from or near the optimum distance, the transmission efficiency sharply decreases.

For example, mutual inductance M between the two coils 711 and 751 increases as the two coils 711 and 751 approach the optimum distance with the highest transmission efficiency. The resonance frequency changed due to the increase of the mutual inductance M is no longer coincident with the power supply frequency supplied to the primary coil 711. [ As a result, the intensity of the current supplied to the primary coil 711 sharply decreases, and the resonance between the primary coil 711 and the secondary coil 751 is also broken. Since k, which is one of the parameters for determining the transmission efficiency, is proportional to the mutual inductance M, the transmission efficiency sharply decreases even though the transmission efficiency should increase as the two coils 711 and 751 are closer to each other. A section where the transmission efficiency sharply decreases within a certain distance is called a dead zone. This is the difference from the electromagnetic induction method.

Methods for compensating for such a change in mutual inductance include a method of changing the power frequency itself according to a change in resonance frequency due to a change in mutual inductance or a method of canceling a change in mutual inductance by adjusting the inductance and capacitance of the feeder 710 And so on.

9 is a graph showing power transmission efficiency according to the distance between the power supply coil and the current collector coil.

In the graph shown in FIG. 9, the curve a shows the power transmission efficiency according to the distance between the current collecting nose which is generally seen when the impedance change due to the change of the position of the secondary coil is not compensated. The curve b shows the power transmission efficiency of the power-saving device according to an embodiment of the present invention. As the distance gets closer, the intensity of the induced current induced in the secondary coil 110 increases and the power transmission efficiency increases. . This effect is due to the following reasons.

First, in the wireless power transmission system according to the present invention, by applying a very high voltage to the power feeding device, a very strong electromagnetic field is formed in the vicinity of the primary coil. The voltage is induced in the secondary coil from the strong electromagnetic field near the primary coil by an electromagnetic induction method even if the resonance is broken due to the proximity of the primary coil and the secondary coil within the optimum distance in this proximity system. This prevents degradation of transmission efficiency in the dead zone.

Second, in the wireless power transmission system according to the present invention, the impedance matching unit is disposed at both ends of the secondary coil of the current collector to cancel the inductive reactance of the secondary coil through the two impedance matching units to match the resonant frequency with the current collector , A resonance current having a phase difference of 180 degrees from each other is caused to flow in the impedance matching portions at both ends of the resonance current. Therefore, at the rectifying circuit output terminal, a voltage twice as high as that in the case where the impedance matching unit is disposed on only one side of the secondary coil is applied. As a result, even if the transmission efficiency is reduced due to the proximity of the primary coil and the secondary coil within an optimum distance, a voltage of a considerable magnitude can be supplied to the load portion of the tertiary coil.

Third, in the wireless power transmission system according to the present invention, since the impedance matching unit is disposed at the rear end of the secondary coil of the current collector, the parasitic impedance can eliminate the influence of the change in the total impedance due to the change in distance between the power feeding device and the current collecting device. In this case, the parasitic impedance means an impedance due to, for example, a rectifying circuit, a smoothing circuit, or a load.

The resonance frequency of each of the power-feeding devices may change in association with the respective total impedance. Therefore, a change in the distance between the current collecting device and the power feeding device causes a change in the total impedance of each of the power collecting devices, resulting in a resonance frequency mismatch between the power collecting devices. The impedance matching unit according to an embodiment of the present invention has an effect of preventing the resonance frequency mismatch due to the total impedance change by excluding the parasitic impedance among the factors of the total impedance change caused by the distance change described above. Accordingly, the coupling between the primary coil and the secondary coil can prevent the impedance mismatch from increasing in a short distance.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. It will be clear to those who have knowledge of.

100: Current collector 110: Secondary coil 120: Impedance matching unit
130: rectification circuit 140: smoothing circuit 150:
210: secondary coil 220: first impedance matching unit
225: second impedance matching unit 230: rectifier circuit 240: smoothing circuit
250: Load section
310: secondary coil 320: first capacitor 325: second capacitor
330: bridge rectifier circuit 340: smoothing capacitor 350: resistor
400: Feeder 410: Frequency generator 420: Magnetic polarity controller
430: power amplifier 440: switching element 441: MOSFET
450: LC resonant inverter 451: inductor L1 452: capacitor C1
453: capacitor C2 460: magnetic field intensity adjusting section 461: variable capacitor VC1
462: capacitor C3 463: diode D1 470: primary coil
471: primary coil L2
710: Feeder 711: Primary coil 750: Current collector
751: Secondary coil

Claims (11)

A power collecting device of a wireless power transmission system,
A secondary coil which is induced by an electromagnetic field resonating at a predetermined frequency from a power feeding device of the wireless power transmission system to generate an induced current;
An impedance matching unit connected to both ends of the secondary coil and resonating at the same frequency as the predetermined frequency in association with the secondary coil;
A rectifying circuit connected to an output terminal of the impedance matching unit and rectifying the induction current induced in the secondary coil to a direct current; And
And a support for supporting the secondary coil, the impedance matching unit, and the rectifier circuit,
Wherein when the secondary coil is close to a primary coil of the power feeding device and the resonance between the electromagnetic field and the secondary coil is broken and the secondary coil is disconnected from the electromagnetic coil Wherein the power is received through an inductive system.
The method according to claim 1,
The support may be a polyimide (PI), a polyethylene naphthalate (PEN), a polyethylene terephthalate (PET), a polycarbonate (PC), a polyethylene sulfone (PES), a polyimide (PI), a polyarylate At least one member selected from the group consisting of cyclic olefin (PCO), crosslinked epoxy, and crosslinked urethane film.
The method according to claim 1,
Wherein the support has a thickness of 0.01 to 1 mm.
The method according to claim 1,
Wherein the support has a thickness of 0.1 to 0.5 mm.
3. The method according to claim 1 or 2,
Wherein the impedance matching unit includes a first capacitor connected to one side of the secondary coil and a second capacitor connected to the other side of the secondary coil.
6. The method of claim 5,
Wherein the first capacitor and the second capacitor comprise:
And shields the parasitic impedances of the first capacitor and the second capacitor at the time of calculating the input impedance of the power supply device of the wireless power transmission system.
6. The method of claim 5,
Wherein the first capacitor and the second capacitor have capacitances equal to each other.
The method according to claim 1,
Wherein the rectifier circuit is implemented by a bridge rectifier in which four diodes are bridge-coupled.
3. The method according to claim 1 or 2,
Wherein the power collecting device further comprises a smoothing circuit connected in parallel to an output terminal of the rectifying circuit and smoothing the output power of the rectifying circuit.
3. The method according to claim 1 or 2,
Wherein the power collecting device further comprises a load unit connected to an output terminal of the rectifying circuit to consume the rectified power.
11. The method of claim 10,
Wherein the load unit includes a charging circuit for charging the secondary battery using the rectified power.

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