KR20170075608A - wireless power transmission module having variable inductor - Google Patents

Abstract

A wireless power transmission module having a variable inductor is provided. A wireless power transmission module having a variable inductor according to an exemplary embodiment of the present invention includes a wireless power transmission coil that operates in a resonant manner with an operating frequency in the range of 6.765 MHz to 6.795 MHz, And a variable inductor part electrically connected to the coil for varying the total inductance so that the center frequency of the operating frequency is within the range of 6.765 MHz to 6.795 MHz to operate at a resonant frequency, And a control coil wound around the magnetic core a plurality of times in a direction different from the winding direction of the variable coil, wherein the magnetic core has a frequency range of 6.765 MHz to 6.795 MHz (= Μ "/ μ ') may be less than or equal to 0.05. According to this, the transmission coil and the electric As to vary the total inductance through the variable inductor unit which is connected to the center frequency of the operating frequency located in a predetermined frequency range, it is possible to increase the power transfer efficiency to operate as a resonant frequency.

Description

[0001] The present invention relates to a wireless power transmission module having variable inductors,

The present invention relates to a wireless power transmission module, and more particularly, to a wireless power transmission module in which when a wireless power transmission is performed by a resonance method, a total inductance is varied so that a center frequency of a resonance frequency is within a predetermined range through a variable inductor, And more particularly to a wireless power transmission module having a variable inductor capable of increasing the power consumption of the wireless power transmission module.

The wireless terminal includes a wireless charging function for wirelessly charging a built-in battery. The wireless charging is performed by receiving a wireless power from a wireless power transmission module built in a wireless terminal.

Such wireless charging uses a magnetic induction method and a self-resonance method.

The magnetic induction system or the self-resonance system described above uses a magnetic field, which is the same in that an electromagnetic field is created using a coil and electric power is transmitted through the electromagnetic field. However, the magnetic induction method uses an electromagnetic induction phenomenon between coils, and the self resonance method uses magnetic resonance between coils.

That is, the magnetic induction method is a principle in which the magnetic field generated in the primary coil flows the induced current to the secondary coil to supply energy when the coils made with the same frequency are superposed on each other, and the magnetic resonance method does not directly contact the charging mat It is characterized by the ability to transmit power.

The self-resonance method is basically the same as the magnetic induction method in which the current is converted into electromagnetic through the coil, but it is transmitted to the resonance frequency to send it away. That is, the self resonance system is configured to include a capacitor and a coil in the wireless power transmission module and the wireless power reception module, so that resonance occurs in a predetermined frequency band, and wireless power is transmitted to perform wireless charging.

At this time, the self-resonant system operates in the frequency range of 6.765 MHz to 6.795 MHz. When the center frequency of the operating frequency is in the band of 6.765 MHz to 6.795 MHz and resonance is performed by operating at the resonant frequency, The maximum charging efficiency can be obtained.

However, since the wireless power transmission module is mass-produced in a large unit, the probability that the center frequency of the operating frequency for resonance is out of the range of 6.765 MHz to 6.795 MHz becomes very high. If the center frequency of the operating frequency deviates from the range of 6.765 MHz to 6.795 MHz, the amplitude of the resonance frequency becomes smaller and the radiation loss increases, so that the charging efficiency is lowered.

Also, when the positions of the wireless power receiving module and the wireless power transmitting module are excessively close at the time of wireless power transmission, a split phenomenon occurs in a range of 6.765 MHz to 6.795 MHz, which causes a problem of deteriorating power transmission efficiency.

KR 10-2015-0002047 A

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a variable inductor unit that varies a total inductance through a variable inductor unit electrically connected to a transmission coil, And it is an object of the present invention to provide a wireless power transmission module having a variable inductor capable of improving power transmission efficiency.

In order to achieve the above object, the present invention provides a wireless power transmission module including a wireless power transmission coil that operates in a resonant mode with an operating frequency of 6.765 MHz to 6.795 MHz, And a variable inductor unit for varying the total inductance so that the center frequency of the operating frequency is within a range of 6.765 MHz to 6.795 MHz to operate at a resonant frequency, wherein the variable inductor unit includes a hollow magnetic core and an outer circumferential surface of the magnetic core And a control coil wound around the magnetic core a plurality of times in a direction different from a winding direction of the variable coil, wherein the magnetic core has a magnetic permeability of 100 to 350 in a frequency range of 6.765 MHz to 6.795 MHz , And tan ㅿ (= μ "/ μ ') is 0.05 or less.

Further, the control coil may be wound on the magnetic core in a direction perpendicular to the winding direction of the variable coil.

Also, the magnetic core may be made of Ni-Zn ferrite.

The inductance of the variable coil may be in the range of 0.5 μH to 5 μH, and the inductance of the control coil may be in the range of 5 μH to 300 μH.

In addition, the inductance of the control coil can be varied in a range of 0.00001 μH to 3 μH.

The variable inductor unit may further include a current varying unit for changing the amount of current supplied to the control coil through a correction signal. The current varying unit may include a coupler coupled to the transmission coil to detect the frequency and phase of the transmission coil, And a comparator that is electrically connected to the power supply unit and generates a correction signal by comparing the frequency and phase of the power supply unit with the frequency and phase of the source detection unit and the transmission coil and the frequency and phase of the power supply unit .

According to the present invention, the total inductance can be varied through the variable inductor unit electrically connected to the transmission coil, so that the center frequency of the operating frequency is positioned within a predetermined frequency range to operate at a resonant frequency, thereby enhancing the power transmission efficiency.

FIG. 1 is a conceptual diagram illustrating a concept that electric power is transmitted to a wireless power receiving module through a wireless power transmission module having a variable inductor according to an embodiment of the present invention. FIG.
FIG. 2 is a diagram showing the arrangement relationship of the variable coil, the control coil, and the magnetic body in the variable inductor unit applied to FIG. 1;
3 is a conceptual view of a current varying part applied to a wireless power transmission module having a variable inductor according to the present invention,
4 is a flowchart illustrating a process of varying the inductance of a variable coil through a wireless power transmission module having a variable inductor according to an embodiment of the present invention,
FIG. 5 is a graph illustrating a frequency of a wireless power transmission module having a variable inductor according to an exemplary embodiment of the present invention. FIG. 5 is a graph illustrating a frequency characteristic of a variable inductor when a center frequency is out of a range of 6.765 MHz to 6.795 MHz. B) shows a state where the center frequency is in the range of 6.765 MHz to 6.795 MHz, and when the split occurs, if the split is compensated through the variable inductor unit Fig.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

Referring to FIG. 1, a wireless power transmission module 100 having a variable inductor according to an exemplary embodiment of the present invention is for wirelessly transmitting power without contact with a wireless power receiving module 10.

That is, the wireless power transmission module 100 having the variable inductor transmits power using a resonance coupling method based on an electromagnetic resonance phenomenon generated by a wireless power signal of a specific frequency. Here, the specific frequency may be 6.765 MHz to 6.795 MHz.

More specifically, electromagnetic resonance occurs in the receiving coil 12 of the wireless power receiving module 10 by the wireless power signal transmitted from the transmitting coil 112 of the wireless power transmitting module 100, Power is transmitted from the wireless power transmission module 100 to the wireless power receiving module 10 due to the resonance phenomenon.

Here, the wireless power receiving module 10 may be installed in a portable electronic device such as a mobile phone, a PDA, a PMP, a tablet, a multimedia device, etc., and may be driven using power transmitted from the wireless power transmission module 100, The main battery of the portable electronic device may be charged by using the power transmitted from the power transmission module 100. [

Here, the resonance refers to a phenomenon in which the vibration system receives an external force having a frequency equal to the natural frequency thereof periodically and the amplitude thereof increases sharply. In such a resonance, when a plurality of vibrating bodies spaced within a certain distance oscillate at the same frequency (resonance frequency), the plurality of vibrating bodies resonate with each other, and in this case, the resistance between the vibrating bodies decreases . To this end, at least one coil and a capacitor are used to constitute a resonant circuit.

At this time, the resonance frequency is determined by the inductance and the capacitance in the circuit according to the following equation (1).

Where f is the resonant frequency, L is the inductance, and C is the capacitance.

In a circuit for forming a magnetic field using a coil, the inductance is determined by the number of revolutions of the coil and the like, and the capacitance can be determined by a gap or an area between a pair of electrodes facing each other.

Referring to FIG. 1 again, a wireless power transmission module 100 having a variable inductor according to an embodiment of the present invention includes a transmission coil 112 and a transmission coil 112 And a capacitor 114 for determining a specific resonance frequency.

The transmission coil 112 converts the power supplied from the power supply unit 116 into a wireless power signal and transmits the wireless power signal to the wireless power receiving module 10. The radio power signal transmitted by the transmission coil 112 is formed in the form of a magnetic field having a vibration characteristic.

Thereby, a specific resonance frequency is determined based on the inductance of the transmission coil 112 and the capacitance of the capacitor 114.

Here, the wireless power transmission module 100 may further include circuits capable of adjusting characteristics such as a frequency, an applied voltage, and a current used for generating a wireless power signal in the transmission coil 112.

For example, the circuits may include an inverter (not shown) that converts the DC power supplied from the power supply unit 116 to AC power. Thus, the alternating current converted through the inverter can cause the magnetic field to be generated in the transmission coil 112 by driving the transmission coil 112 and the capacitor 114.

In addition, the circuits may perform the process of identifying the wireless power receiving module 10 according to a result of detecting the presence of the wireless power receiving module 10, determine whether to start wireless power transmission, (Not shown) that can determine at least one of the frequency, voltage, and current of the transmitting coil 112 to generate a signal.

For example, the controller may be used to generate the wireless power signal according to a power control message including at least one of a power amount information, a charging status information, and identification information of an electronic device including the wireless power transmission module 100 One or more characteristics of the frequency, current, and voltage can be determined.

The wireless power receiving module 10 includes a receiving coil 12 and a capacitor 14 so that a resonance phenomenon can occur due to a magnetic field formed in the wireless power transmission module 100. The receiving coil 12, And the resonance frequency determined on the basis of the capacitance of the capacitor 14 is equal to the resonance frequency of the magnetic field generated in the transmission coil 112. [

At this time, the wireless power transmission module 100 according to the present invention is positioned within the frequency range of 6.765 MHz to 6.795 MHz, in which the center frequency of the operating frequency generated by the transmission coil 112 is transmitted by a resonant method, And a variable inductor unit 120 for varying the inductance of the transmission coil 112 so as to operate with the variable inductor unit.

Generally, since the wireless power transmission module 100 is mass-produced in large units, the probability that the center frequency of the operating frequency for resonance is out of the range of 6.765 MHz to 6.795 MHz becomes very high. If the center frequency of the operating frequency deviates from the range of 6.765 MHz to 6.795 MHz, a frequency having a relatively smaller amplitude than the center frequency operates at a resonance frequency, resulting in an increase in the radiation loss, resulting in a decrease in the power transmission efficiency.

Also, when the positions of the wireless power receiving module and the wireless power transmitting module are excessively close at the time of wireless power transmission, splitting phenomenon occurs in the range of 6.765 MHz to 6.795 MHz, and the power transmission efficiency is lowered.

In the present invention, in order to solve this problem, the inductance of the transmission coil 112 is varied through the variable inductor unit 120 so that the center frequency of the operating frequency is located within a predetermined frequency range to operate at a resonant frequency, .

2, the variable inductor unit 120 includes a hollow magnetic body core 126, a variable coil 122 wound on the outer periphery of the magnetic core 126 a plurality of times, And a control coil 124 wound around the core 126 a plurality of times in a direction different from the winding direction of the variable coil 122.

At this time, the control coil 124 is wound on the magnetic core 126 in a direction perpendicular to the winding direction of the variable coil 122. This is so that the current of the control coil 124 can minimize the influence of magnetic saturation of the variable coil 122. [

Here, the variable coil 122 is connected in series with the transmission coil 112.

The inventors have found that the inductance in the variable coil 122 when the variable coil 122 and the control coil 124 are wound in the direction perpendicular to the magnetic core 126 as a result of repetition of the exemplary experiment is smaller than the inductance of the control coil 124 , But it remains constant when the current flowing through the variable coil 122 changes, as shown in Table 1 below.

This is because the variable coil 122 wound on the outer circumferential surface of the magnetic core 126 is independent of the magnetic permeability of the magnetic core 126 and is perpendicular to the winding direction of the variable coil 122 Since the control coil 124 wound in the direction of the magnetic core 126 is subject to the magnetic permeability of the magnetic core 126.

In the table 1, the first row shows the amount of current flowing through the variable coil 122, the first column shows the amount of current flowing through the control coil 124, and the remaining column shows the inductance value of the variable coil 122.

Accordingly, when the variable coil 122 and the control coil 124 are wound in the direction perpendicular to the magnetic core 126 and the variable coil 122 and the transmission coil 112 are connected in series, The inductance of the variable coil 122 is changed by varying the amount of current supplied to the variable coil 122 and the inductance of the variable coil 122 and the inductance of the transmission coil 112 are changed by the change in inductance of the variable coil 122 The overall inductance of the wireless power transmission module 100 is also changed.

Here, the current supplied to the control coil 124 is provided through a power supply unit 128 electrically connected to the variable inductor unit 120.

In this case, the variable inductor unit 120 according to the present invention further includes a current varying unit 130 to generate a correction signal when necessary and change the amount of current supplied to the control coil 124 side.

The current varying unit 130 controls the power supply unit 128 by a correction signal to control the amount of current supplied to the control coil 124 side.

3, the current varying unit 130 includes a coupler 131, a source detecting unit 132, and a comparator 133. The coupler 131, the source detecting unit 132,

The coupler 131 is coupled to the transmission coil 112 to detect the frequency and phase of the transmission coil 112. The source detection unit 132 is electrically connected to the power supply unit 116, And detects the frequency and phase of the power supply unit 116. [

3, the comparator 133 compares information on the frequency and phase of the transmission coil 112 detected through the coupler 131 and information on the frequency and phase of the transmission coil 112 detected by the power detection unit 132 116 to determine whether the center frequency of the operating frequency is located in the frequency band of 6.765 MHz to 6.795 MHz and whether or not the split occurs in the frequency band of 6.765 MHz to 6.795 MHz do.

Accordingly, when the center frequency of the operating frequency deviates from the frequency band of 6.765 MHz to 6.795 MHz, or when the split occurs in the frequency band of 6.765 MHz to 6.795 MHz, the comparator 133 generates a correction signal, The amount of current supplied to the control coil 124 side is changed.

That is, when the correction signal is generated by the comparator 133, the amount of current supplied from the power supply unit 128 to the control coil 124 side is varied according to the correction signal, thereby changing the inductance of the variable coil 122, The inductance of the entire power transmission module 100 is changed.

Accordingly, the electromagnetic resonance generated in the reception coil 12 by the wireless power signal transmitted from the transmission coil 112 is set so that the center frequency of the operation frequency is in the range of 6.765 MHz to 6.795 MHz, The portion having the maximum amplitude of the center frequency of the operating frequency that is not split can be changed to be located within the frequency band of 6.765 MHz to 6.795 MHz to operate at the resonant frequency, thereby improving the overall power transmission efficiency

This can be confirmed by the graph shown in FIG.

5A, when the center frequency of the operating frequency deviates from the frequency band of 6.765 MHz to 6.795 MHz, the amount of current supplied to the control coil 124 is changed by the correction signal generated by the comparator 133 The inductance of the variable coil 122 is changed. Accordingly, the entire inductance of the wireless power transmission module 100 is changed so that the center frequency of the operating frequency is shifted to be within the frequency band of 6.765 MHz to 6.795 MHz, so that it can operate at the resonant frequency.

5B, when the split occurs in the frequency band of 6.765 MHz to 6.795 MHz, the amount of current supplied to the control coil 124 is changed by the correction signal generated by the comparator 133, 122 are changed. Accordingly, the total inductance of the wireless power transmission module 100 is changed so that the portion having the maximum amplitude of the center frequency of the operating frequency without splitting is changed to be located within the frequency band of 6.765 MHz to 6.795 MHz, Frequency. ≪ / RTI >

In FIGS. 5A and 5B, black indicates a frequency in which the position of the center frequency of the operation frequency is corrected by the control coil 124, and red and green indicate the frequencies in which the control coil 124 is not supplied with power Indicates the frequency of the initial state.

A coil having an inductance in a range of 0.5 μH to 5 μH is used as the variable coil 122, a coil having an inductance in a range of 5 μH to 300 μH is used as the control coil 124, Is set to be variable within the range of 0.00001 μH to 3 μH.

 In addition, a magnetic material having a magnetic permeability of 100 to 350 and a tan ㅿ (= μ "/ μ ') of 0.05 or less is used in the magnetic core 126 in the frequency band of 6.765 MHz to 6.795 MHz, Is the permeability, and [micro] is the investment loss rate).

At this time, the magnetic body can be used as long as it satisfies the above-mentioned characteristics.

For example, the magnetic material may be an amorphous alloy or a nanocrystalline alloy ribbon, polymer, ferrite, or the like, and Ni-Zn ferrite may be used.

As described above, the wireless power transmission module 100 having the variable inductor according to the present invention can vary the entire inductance through the variable inductor unit 120, and can easily perform the correction so that the center frequency of the operating frequency is located in the frequency band of 6.765 MHz to 6.795 MHz. So that the radiation loss can be reduced and the overall power transmission efficiency can be increased.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: Wireless power transmission module with variable inductor
112: Transmission coil 114: Capacitor
116: power supply unit 120: variable inductor unit
122: Variable coil 124: Control coil
126: magnetic core 127: amplifier
128: Power supply unit 130: Current variable unit
131: coupler 132: source detector
133: comparator

Claims (7)

1. A wireless power transmission module comprising a wireless power transmission coil operating in a resonant manner with an operating frequency in the range of 6.765 MHz to 6.795 MHz,
And a variable inductor unit electrically connected to the transmission coil for varying the total inductance so that the center frequency of the operating frequency is within a range of 6.765 MHz to 6.795 MHz to operate at a resonant frequency,
The variable inductor unit includes a hollow magnetic core, a variable coil wound around the outer periphery of the magnetic core a plurality of times, and a control coil wound around the magnetic core a plurality of times in a direction different from the winding direction of the variable coil,
Wherein the magnetic core has a variable inductor having a permeability of 100 to 350 in a frequency range of 6.765 MHz to 6.795 MHz and a tan ㅿ (= μ "/ μ ') of 0.05 or less.
(Where mu is the permeability and mu is the investment loss rate) The method according to claim 1,
Wherein the control coil has a variable inductor that is wound around the magnetic core in a direction perpendicular to the winding direction of the variable coil. The method according to claim 1,
Wherein the magnetic core has a variable inductor made of Ni-Zn ferrite. The method according to claim 1,
Wherein the inductance of the variable coil is in the range of 0.5 μH to 5 μH and the inductance of the control coil is in the range of 5 μH to 300 μH. 5. The method of claim 4,
Wherein the inductance of the control coil has a variable inductor that varies in a range of 0.00001 μH to 3 μH. The method according to claim 1,
Wherein the variable inductor unit further comprises a variable inductor, the variable inductor further comprising a current varying unit for changing the amount of current supplied to the control coil through a correction signal. The method according to claim 6,
A current detector for detecting a frequency and a phase of the transmitting coil and a current detector for detecting a frequency and a phase of the transmitting coil; And a comparator that compares the frequency and phase of the power supply to generate a correction signal.

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