KR101994749B1 - Apparatus for transmiting power wirelessly - Google Patents

Abstract

According to one technical aspect of the present invention, there is provided a wireless power transmission apparatus comprising: a voltage step-up unit that operates at a fixed duty ratio to step up an input power source in a first mode and operates at a variable duty ratio in a second mode to step up the input power source; And an inverter outputting an alternating current from a power source boosted by the boosting unit in operation, wherein the boosting unit and the inverter can commonly use at least one switching device.

Description

[0001] APPARATUS FOR TRANSMITTING POWER WIRELESSLY [0002]

The present invention relates to a wireless power transmission apparatus.

With the advancement of wireless technology, wireless technology is being developed in various ways such as transmitting data as well as data. In particular, recently, a wireless power transmission technology capable of charging electric power to an electronic device even in a non-contact state has been developed.

The wireless power transmission device according to the wireless power transmission technology can be applied to various environments such as a table or an automobile interior, and accordingly, there is a demand for downsizing.

Further, in order to transmit power stably even in an environment where the position of the wireless power receiving apparatus is fluctuated or the like, the wireless power transmitting apparatus is required to transmit various kinds of information There is a demand

Korean Patent Registration No. 10-0306972 Korean Patent Registration No. 10-0820461 Japanese Patent Application Laid-Open No. 2015-502131

It is an object of one embodiment according to the present invention to provide a wireless power transmission apparatus which can provide a miniaturization of a wireless power transmission apparatus and can also provide a longer charging distance.

One technical aspect of the present invention proposes an embodiment of a wireless power transmission apparatus. In an embodiment of the wireless power transmission apparatus, in the first mode, the operation duty is fixed and the operation frequency is varied to increase the input power. In the second mode, the operation duty is varied and the operation frequency is fixed And a second operation mode in which the operation duty is fixed and the operation frequency is varied in the first mode and the operation duty is varied and the operation frequency is fixed in the second mode, And an inverter for outputting an alternating current from a power source boosted by the boosting unit, wherein the boosting unit and the inverter can commonly use at least one switching device.

Another aspect of the present invention proposes another embodiment of a wireless power transmission apparatus. Another embodiment of the wireless power transmission apparatus includes a voltage boosting unit for boosting an input power according to an alternate switching operation of the first switch and the second switch and a voltage boosting unit for boosting the input power according to the alternating switching operation of the first switch and the second switch Wherein the first switch and the second switch are operated at a variable operating frequency in a normal mode, and when the operating frequency is variable in the normal mode to reach a reference frequency, And can be switched to the boost mode operated at the operating frequency.

The solution of the above-mentioned problems does not list all the features of the present invention. Various means for solving the problems of the present invention can be understood in detail with reference to specific embodiments of the following detailed description.

The wireless power receiving apparatus according to the embodiment of the present invention has the effect of providing a miniaturization of the wireless power transmitting apparatus and providing a longer charging distance.

1 is a diagram illustrating an example of application of a wireless power transmission apparatus according to an embodiment of the present invention.
2 is a circuit diagram illustrating a wireless power transmission apparatus according to an embodiment of the present invention.
3 is a graph showing the relationship between the voltage gain and the operating frequency of the wireless power transmission apparatus shown in Fig.
4 is a view for explaining how the mode is divided according to the distance between the wireless power transmission apparatus and the wireless power reception apparatus.
5 is a view for explaining an application signal of the switch of the wireless power transmission apparatus shown in FIG.
6 is a circuit diagram illustrating a wireless power transmission apparatus according to another embodiment of the present invention.
7 is a circuit diagram illustrating a wireless power transmission apparatus according to another embodiment of the present invention.
8 is a circuit diagram illustrating a wireless power transmission apparatus according to another embodiment of the present invention.
9 is a graph showing the coil current and output voltage of a wireless power transmission apparatus according to an embodiment of the present invention.
10 is a graph showing an output voltage according to a change in duty ratio in a wireless power transmission apparatus according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

Meanwhile, the meaning of the terms described in the present invention should be understood as follows. It is to be understood that when an element is referred to as being "connected" to another element, it may be directly connected to the other element, although other elements may be present in between. On the other hand, when an element is referred to as being " directly connected " to another element, it should be understood that there are no other elements in between. On the other hand, other expressions that describe the relationship between components, such as 'between' and 'between' or 'neighboring to' and 'directly adjacent to' should be interpreted as well.

1 is a diagram illustrating an example of application of a wireless power transmission apparatus according to an embodiment of the present invention.

1, a wireless power receiving apparatus 200 may be magnetically coupled to a wireless power transmission apparatus 100 adjacent to a wireless power transmission apparatus 100, for example, by magnetic resonance or magnetic induction, Lt; / RTI >

The wireless power receiving apparatus 200 can provide the received electric power to the electronic device 300. [ The wireless power receiving apparatus 200 may be provided as a component in the electronic device 300 or may be a separate device connected to the electronic device 300. [

The wireless power receiving apparatus 200 is adjacent to the wireless power transmitting apparatus 100, but may be fixed or its position may be varied.

Accordingly, even when the distance from the wireless power receiving apparatus 200 becomes long, the wireless power transmission apparatus 100 according to an embodiment of the present invention can provide stable charging by transmitting a higher power corresponding to the distance .

2 is a circuit diagram illustrating a wireless power transmission apparatus according to an embodiment of the present invention.

Referring to FIG. 2, the wireless power transmission apparatus 100 may include a boosting unit 110 and an inverter 120. According to an embodiment, the wireless power transmission apparatus 100 may further include a transmission resonator 130. [

The boosting unit 110 can boost the input power supply Vin. The input power supply (Vin) is a DC power supply. According to an embodiment, the wireless power transmission apparatus 100 may further include an AC / DC conversion circuit that receives an AC power and generates a DC input power (Vin).

The boosted power is stored in the output capacitor Co and the alternating current generated by the switching operation of the inverter 120 is input to the transmission resonator 130 to perform wireless charging.

The boosting unit 110 includes a first switch SW1, an output capacitor Co having one end connected to one end of the first switch SW1 and the other end connected to the other end of the DC input power supply Vin, An inductor L1 whose one end is connected to one end of the input power supply Vin and the other end is connected to the other end of the first switch SW1 is connected to the other end of the first switch SW1 at one end, And a second switch SW2 connected to the other end of the DC input power supply Vin.

The inverter 120 may include a first switch SW1 and a second switch SW2. That is, the booster 110 and the inverter 120 can commonly use at least one switching element.

In the illustrated example, the voltage booster section 110 and the inverter 120 commonly include a first switch SW1 and a second switch SW2.

That is, the first switch SW1 and the second switch SW2 are alternately switched to boost the input power source to store the output capacitor Co, and the output capacitor Co can be charged by the alternating switching operation, The alternating current can be outputted from the electric charge stored in the capacitor Cs.

The boosting unit 110 may be switched and controlled differently depending on the mode. The inverter 120 commonly uses the booster 110 and at least one switching element, so that the inverter 120 can also be switched and controlled differently depending on the mode.

For example, the mode may include a normal mode and a boost mode.

In the normal mode, the step-up unit 110 can perform a switching operation at a fixed ratio to boost the input power. Accordingly, the inverter 120 can also perform switching operation at a fixed duty ratio to output an alternating current.

On the other hand, the distance from the wireless power receiving apparatus can be changed due to a change in the position of the wireless power receiving apparatus. Accordingly, it is necessary to adjust the size of the transmission power, which can be controlled differently for each mode.

For example, in the normal mode, the voltage step-up unit 110 and the inverter 120 operate at a fixed ratio, so that the operating frequency of the switch can be varied to control the magnitude of the output power. That is, the voltage step-up unit 110 and the inverter 120 can operate at a variable frequency in the normal mode.

In the boost mode, the voltage boosting unit 110 can perform a switching operation at a variable rate to boost the input power. Accordingly, the inverter 120 can also perform switching operation at a variable rate to output an alternating current.

Meanwhile, in the boost mode, the boosting unit 110 and the inverter 120 are operated at a variable rate, and in this case, the operating frequency of the switch can be fixed. That is, since the magnitude of the transmission power in the boost mode is determined by controlling the duty ratio, the operating frequency of the switches common to the voltage booster unit 110 and the inverter 120 may be a fixed frequency.

In the boost mode, the magnitude of the power supply stepped up by the voltage step-up unit 100 is larger than the magnitude of the power supply in the normal mode. Since the voltage booster section 110 and the inverter 120 share at least some switching elements, the boost ratio is increased more than the duty ratio in the normal mode in order to increase the output in the fixed frequency state, . Therefore, switching is performed based on a higher DC power source, so that a higher output can be obtained.

To be more specific, the first switch SW1 and the second switch SW2 are operated with a variable operating frequency in the normal mode. In the boost mode, It can be seen that it operates with a fixed operating frequency.

For example, the operating frequencies of the first switch SW1 and the second switch SW2 may be changed corresponding to a change in distance from the wireless power receiving apparatus in the normal mode, and fixed at the reference frequency in the boost mode.

The first switch SW1 and the second switch SW2 operate at a fixed duty ratio in the normal mode to boost the input power source and operate at a variable duty ratio in the boost mode to output an alternating current.

In one embodiment, the duty ratio in the normal mode may be adjacent to 50%, and the duty ratio in the boost mode may exceed 50%.

That is, the following Equation (1) is an expression representing the input / output relationship of the voltage-up unit.

[Equation 1]

Vo = Vin / (1-D)

Here, Vin denotes an input voltage of the step-up unit, Vo denotes an output voltage of the step-up unit, and D denotes a duty ratio of the switch.

In the example in which the normal mode operates at the duty ratio of 50%, the output of the boosting portion is twice the input of the boosting portion. On the other hand, since the duty ratio of the boost mode may exceed 50%, the output of the boosting unit in the boost mode has a higher output than the output in the normal mode

Thus, when higher power is needed, it operates according to the boost mode, so that a higher output can be easily achieved.

Equation (2) below is a formula representing the output voltage of the inverter section.

&Quot; (2) "

Vinv = 2 (2 Vin) * sin (wt) / pi

Equation 2 is the inverter output voltage when the input voltage is doubled in the normal mode and operated as a half bridge inverter, which is identical to the output voltage of the full bridge inverter operating on the basis of the input power .

In one embodiment, booster 110 may be operated in an initial mode of operation such that the duty rate is gradually increased, starting at a duty ratio of 0% to reaching the fixed duty ratio. The initial operation mode is applied to a situation where the operation is started in the non-operation (stop) state.

This is because the boosting unit 110 boosts the input power through the alternating switching, thereby causing a predetermined ripple to be generated in the boosted power supply. That is, it is possible to prevent the ripple of the boosted power supply by performing soft switching up to a fixed ratio in the initial operation of the boosting unit 110.

The wireless power transmission apparatus 100 further includes a control unit (not shown) for controlling operations of the boost unit 110 and the inverter 120, that is, the operation of the switches included in the boost unit 110 and the inverter 120 can do.

The control unit may include at least one processing unit. According to an embodiment, the control unit may further include a memory. The processing unit may include, for example, a central processing unit (CPU), a graphics processing unit (GPU), a microprocessor, an application specific integrated circuit (ASIC), field programmable gate arrays (FPGA) Core. The memory may be a volatile memory (e.g., RAM, etc.), a non-volatile memory (e.g., ROM, flash memory, etc.), or a combination thereof.

The control unit may include a gate driver. The wireless power transmission apparatus 100 may separately include a gate driver for driving the switches included in the voltage step-up unit 110 or the inverter 120 according to a control signal provided from the control unit.

Hereinafter, the control unit will be described as an example including a gate driver, but the control unit and the gate driver can be distinguished according to the embodiment as described above.

The control unit can control the operation frequency of the plurality of switches included in the voltage step-up unit 110 or the inverter 120 according to a change in distance from the wireless power receiving apparatus in the normal mode.

The control unit controls the operation frequency of the plurality of switches to be lowered when the distance from the wireless power receiving apparatus increases. When the operation frequency reaches the reference frequency, the control unit fixes the operation frequency at the reference frequency and switches from the normal mode to the boost mode .

The control unit can control the duty ratios of the plurality of switches included in the voltage step-up unit 110 or the inverter 120 according to a change in distance from the wireless power receiving apparatus in the boost mode.

Fig. 3 is a graph showing the relationship between the voltage gain of the wireless power transmission apparatus shown in Fig. 2 and the operating frequencies of the first and second switches, and an example of the control of the control unit will be described with reference to Fig.

Referring to FIG. 3, in the normal mode, the control unit may set the duty ratio of the switches to a fixed value, for example, a duty ratio of 50%, and operate the first frequency F1.

When the wireless power receiving apparatus is somewhat distant or when a higher output is requested, the control unit sets the operating frequency of the switches to be higher than the first gain G1 at the first frequency F1 Can be lowered from the first frequency (F1) to the second frequency (F2).

That is, the control unit can increase the output while controlling the switches at a fixed duty ratio by changing the frequency of the switches to be lower as the higher output is required in the normal mode.

Meanwhile, the control unit can set the reference frequency Fs as the minimum limit operating frequency. That is, as described above, the control unit lowers the operation frequency for higher output in the normal mode, and when the operation frequency reaches the reference frequency Fs, the control unit can exit the normal mode and operate in the boost mode.

As described above, the boost mode operates at a fixed frequency and at an alteration ratio, so that the output is controlled. As a result, the control unit can prevent operation below the reference frequency by switching modes.

The reference frequency may be preset, externally input or changed. For example, the reference frequency may correspond to a lower limit of the frequency range defined by the wireless charging standard.

FIG. 4 is a view for explaining how the mode is divided according to the distance between the wireless power transmission apparatus and the wireless power reception apparatus, FIG. 5 is a view for explaining an application signal of the switch of the wireless power transmission apparatus shown in FIG. 2, The change of the switch application signal according to each mode will be described with reference to FIGS. 4 and 5. FIG.

4 shows situations (a) to (c), situation (a) shows the case where the wireless power receiving apparatus 300 is placed on the wireless power transmitting apparatus 100, situation (b) The situation (c) shows a case where the wireless power receiving apparatus 300 is spaced apart from the wireless power transmitting apparatus 100 by a predetermined distance or more.

In the illustrated example, the spacing threshold distance Dt may be a charging distance that is effective when transmitting at maximum power in the normal mode.

The normal mode corresponds to the case where the wireless power receiving apparatus 300 exists within the chargeable range in which the wireless power transmitting apparatus 100 is formed by operating at a fixed ratio in the reference frequency.

That is, in situations (a) and (b), the wireless power transmission apparatus 100 operates as a normal mode and the wireless power transmission apparatus 100 changes the operating frequencies of the switches on the basis of a fixed duty ratio, The controllability is as described.

On the other hand, when the spacing threshold distance Dt, that is, the effective distance that can be charged in the normal mode is out of the range, the wireless power transmission apparatus 100 can operate as a boost mode to form a stronger output.

That is, in the situation (c), the wireless power transmission apparatus 100 operates as a boost mode, and the wireless power transmission apparatus 100 operates at the reference frequency but can change the application rate to increase the output .

The graphs (a) to (c) of FIG. 5 illustrate the switching control signals in the situations (a) to (c) of FIG.

As shown in the graphs (a) and (b) of FIG. 5, in the normal mode, switching control is performed at a fixed ratio - 50% in the illustrated example - , The frequency of the switching control signal is lowered.

Meanwhile, the situation (c) in FIG. 4 is a case where the wireless power receiving apparatus 300 is spaced apart from the wireless power transmitting apparatus 100 by a predetermined distance or more, and in a general comparative example, charging is impossible due to power shortage in this case.

In contrast, in the embodiment of the present invention, the boost mode is applied. In the boost mode, as shown in the graph 3 of FIG. 5, the operation ratio is higher than 50%, so that the boost ratio with respect to the input voltage becomes larger. A large charging output can be provided.

Therefore, in a general comparison example as in the situation (c) of FIG. 4, power can be successfully transmitted wirelessly in an embodiment of the present invention even at a distance where charging is impossible.

4, the distance between the wireless power receiving device and the wireless power transmitting device, that is, the charging distance on the Z axis is enlarged. However, in addition to the charging distance on the Z axis, Direction is also enlarged.

That is, in the boost mode, since the input voltage is boosted at a higher rate to transmit power, the magnetic field formed in the wireless power transmission apparatus is transmitted more strongly, and the X-axis, Y-axis and Z- Because.

Although the above description is based on a half bridge type inverter, a full bridge type inverter can be applied.

6 is a circuit diagram illustrating a wireless power transmission apparatus according to another embodiment of the present invention.

The wireless power transmission apparatus 101 shown in Fig. 6 includes a voltage booster 111, an inverter 121, and a transmission resonator 131. Fig. The boosting unit 111 and the transmission resonator 131 can be understood from the above description.

The boosting unit 110 includes a first switch SW1, an output capacitor Co having one end connected to one end of the first switch SW1 and the other end connected to the other end of the DC input power supply Vin, An inductor L1 whose one end is connected to one end of the input power supply Vin and the other end is connected to the other end of the first switch SW1 is connected to the other end of the first switch SW1 at one end, And a second switch SW2 connected to the other end of the DC input power supply Vin.

The inverter 120 includes the first switch SW1 and the second switch SW2 and has one end connected to one end of the first switch SW1 and the other end connected to the other end of the transmission resonator 131 The third switch SW3 may include a fourth switch SW4 having one end connected to the other end of the third switch SW3 and the other end connected to the other end of the DC input power supply Vin.

The first switch SW1 and the second switch SW2 are commonly used as the step-up unit 111. The third switch SW3 and the fourth switch SW4 Is used separately from the voltage-raising portion 111. [

Equation (3) below represents the output voltage of the full bridge inverter.

&Quot; (3) "

Vinv = 4 (2 Vin) * sin (wt) / pi

Comparing this with Equation 3, it can be seen that the use of a full bridge inverter results in twice the output of the example shown in FIG. In addition, as described above, it is possible to output twice the output of the comparative example of the full bridge inverter method for a general input voltage.

7 is a circuit diagram illustrating a wireless power transmission apparatus according to another embodiment of the present invention.

7, the wireless power transmission apparatus 102 includes a boosting unit 112, an inverter 122, and a transmission resonator 132. [ The transmission resonator 131 can be understood from the above description.

The boosting unit 112 may include a diode D.

That is, the step-up unit 112 includes a first switch SW1, a diode D having an anode connected to one end of the DC input power source and a cathode connected to one end of the first switch, And the other end of which is connected to the cathode of the diode D and the other end of which is connected to the other end of the DC input power supply Vin And a second switch SW2 having one end connected to the other end of the first switch SW1 and the other end connected to the other end of the output capacitor Co.

The inverter 122 may include the first switch SW1 and the second switch SW2.

In the illustrated example, since the step-up unit 112 includes the diode D for preventing the reverse current from entering, when the voltage is boosted by the alternate operation of the first switch SW1 and the second switch SW2, It is possible to prevent the ripple caused by the red switching operation.

8 is a circuit diagram illustrating a wireless power transmission apparatus according to another embodiment of the present invention.

8, the wireless power transmission apparatus 103 includes a boosting section 113, an inverter 123, and a transmission resonator 133. [ The transmission resonator 133 can be understood from the above description.

The boosting unit 112 may serially connect the output capacitor Co to the input power supply Vin.

That is, the voltage-up unit 112 includes a first switch SW1, an output capacitor Co having one end connected to one end of the first switch SW1 and the other end connected to one end of the DC input power source, An inductor L1 having one end connected to one end of the DC input power supply Vin and the other end connected to the other end of the first switch SW1 and one end connected to the other end of the first switch SW1, And a second switch SW2 connected to the other end of the DC input power supply Vin.

The inverter 113 may include the first switch SW1 and the second switch SW2.

The boosting unit 112 connects the negative terminal of the output capacitor Co to the DC input power supply Vin so that the initial voltage of the output capacitor Co becomes the input voltage, So that it is possible to prevent the ripple caused by such alternating switching operation when the voltage is boosted by the alternate operation of the first switch SW1 and the second switch SW2.

9 is a graph showing the coil current and output voltage of a wireless power transmission apparatus according to an embodiment of the present invention.

The graph (a) of FIG. 9 shows the coil current of the embodiment shown in FIG. 2 - denoted by the thick dashed line - and the coil current of the comparative example - denoted by a thin solid line.

The graph (b) shows the output voltage of the embodiment shown in FIG. 2 - denoted by the thick dashed line - and the output voltage of the comparative example - denoted by a thin solid line

The comparative example is a wireless power transmission apparatus including a full bridge inverter operating with input power.

As shown in FIG. 2, it can be seen that the embodiment shown in FIG. 2 applies the half bridge inverter and provides the coil current and the output voltage corresponding to the full bridge inverter of the comparative example.

10 is a graph showing an output voltage according to a change in duty ratio in a wireless power transmission apparatus according to an embodiment of the present invention.

10 is a graph showing the output voltage of the boosting unit, and graph (b) is a graph showing the output voltage of the wireless power transmission apparatus.

The thick line in the graph (a) shows the output voltage of the boosting portion according to the application rate of 50%, and the thin line shows the output voltage of the boosting portion according to the application rate of 70%.

As shown in the figure, the output voltage of the step-up part according to the application rate of 50% is about 10 V, but the output voltage of the step-up part according to the application ratio of 70% is slightly higher than 16 V, .

As a result, as shown in the graph (b), the output voltage of the wireless power transmission apparatus according to the application rate of 50% is about 5V, but the output voltage of the boosting unit according to the application ratio of 70% Which provides a higher output.

As can be seen from the above, in the comparative example, there is a region where charging is not possible due to insufficient gain of the wireless charging transmitter, while in the embodiments of the present invention, it is known that a longer charging distance can be secured by boosting the input voltage .

Further, since the booster section and the inverter commonly use at least one switch, the number of the switches and the number of the gate drivers can be reduced, thereby making it possible to reduce the size of the wireless power transmitting apparatus.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the particular forms disclosed. 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, 101, 102, 103: wireless power transmission device
110, 111, 112, 113:
120, 121, 122, 123: Inverter
130, 131, 132, 133: transmission resonator
200: Wireless power receiving device
300: Electronic device

Claims (16)

A boosting unit for boosting the input power by operating the duty to be fixed in the first mode and varying the operating frequency to increase the input power in the second mode and operating the duty so that the operating frequency is fixed; And
In the first mode, the operation duty is fixed and the operation frequency is varied. In the second mode, the operation duty is varied and the operation frequency is fixed so that the operation frequency is changed from a power source boosted by the voltage step- An inverter for outputting an alternating current; Lt; / RTI >
Wherein the boosting unit and the inverter commonly use at least one switching element.
2. The wireless power transmission device according to claim 1,
A controller for controlling the voltage step-up unit and the inverter to operate in either the first mode or the second mode according to a change in distance from the wireless power receiving apparatus;
The wireless power transmission device further comprising:
The radio power transmission device according to claim 1, wherein the chargeable range in the second mode is larger than the chargeable range in the first mode.
The apparatus as claimed in claim 1, wherein the step-
In an initial operating mode, operates to increase the duty rate from a duty rate of 0% to a predetermined fixed duty rate.
3. The apparatus of claim 2, wherein the control unit
Controls the operation duty to be 50% in the first mode and controls the operation duty to exceed 50% in the second mode.
6. The apparatus of claim 5, wherein the control unit
Controlling the boosting unit and the inverter to operate in the first mode and varying the operating frequency in order to increase the output of the wireless power transmitting apparatus in the first mode so that the operating frequency reaches the reference frequency , The operating frequency is fixed to the reference frequency and the first mode is switched to the second mode.
A boosting unit boosting the input power according to an alternating switching operation of the first switch and the second switch; And
An inverter for outputting an alternating current according to the alternate switching operation of the first switch and the second switch; Lt; / RTI >
The first switch and the second switch
Wherein the normal mode is operated at a variable operating frequency and the normal mode is switched to a boost mode operating at a fixed operating frequency when the operating frequency is varied to reach a reference frequency.
8. The method of claim 7, wherein the operating frequency of the first switch is
Is changed in response to a change in distance from the wireless power receiving apparatus in the normal mode, and is fixed at the reference frequency in the boost mode.
8. The apparatus of claim 7, wherein the first switch and the second switch
And operates at a fixed duty ratio in the normal mode and at a variable duty ratio in the boost mode.
10. The method of claim 9,
When a wireless power receiving apparatus exists within a chargeable range in which a wireless power transmitting apparatus is formed by operating at a fixed reference ratio at a reference frequency,
The boost mode
And the wireless power receiving apparatus corresponds to a case where the wireless power receiving apparatus is out of the chargeable range.
10. The apparatus of claim 9, wherein the wireless power transmission apparatus
A control unit for controlling the first switch and the second switch to operate in either the normal mode or the boost mode according to a change in distance from the wireless power receiving apparatus;
The wireless power transmission device further comprising:
12. The apparatus of claim 11, wherein the control unit
Controls the fixed ratio to be 50% in the normal mode, and controls the variable ratio to exceed 50% in the boost mode.
8. The apparatus as claimed in claim 7, wherein the step-
The first switch;
An output capacitor having one end connected to one end of the first switch and the other end connected to the other end of the DC input power supply; And
An inductor having one end connected to one end of the DC input power source and the other end connected to the other end of the first switch;
And a wireless power transmitter.
14. The method of claim 13, wherein the inverter
The first switch; And
A second switch having one end connected to the other end of the first switch and the other end connected to the other end of the DC input power supply;
And a wireless power transmitter.
8. The apparatus as claimed in claim 7, wherein the step-
The first switch;
An output capacitor having one end connected to one end of the first switch and the other end connected to the other end of the DC input power supply;
An inductor having one end connected to one end of the DC input power source and the other end connected to the other end of the first switch; And
A second switch having one end connected to the other end of the first switch and the other end connected to the other end of the DC input power supply;
And a wireless power transmitter.
16. The inverter of claim 15, wherein the inverter
The first switch;
The second switch;
A third switch having one end connected to one end of the first switch and the other end connected to the other end of the transmission resonator; And
A fourth switch having one end connected to the other end of the third switch and the other end connected to the other end of the DC input power supply;
And a wireless power transmitter.

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