Apparatus and method for high efficiency variable power transmission

1. A high efficiency variable power transmitting apparatus comprising:

a variable power generating unit configured to output a variable power by modulating, with respect to a time axis, a high frequency signal having a constant amplitude by turning the high frequency signal ON and OFF,

wherein the variable power generating unit comprises a modulated signal generating unit configured to generate a low frequency modulated signal having a duty cycle depending on the requested power level of the target device;

a power amplifier (PA) configured to amplify the variable power to satisfy a requested power level of a target device based on a power supply voltage having a predetermined level; and

a power supply configured to convert an alternating current (AC) voltage received from a power source to a direct current (DC) voltage, generate the power supply voltage having the predetermined level based on the DC voltage, and provide the power supply voltage having the predetermined level to the PA.

2. The apparatus of claim 1 , further comprising a transmitting unit configured to transmit the amplified variable power to the target device through a transmission coil or an antenna.

3. The apparatus of claim 1 , wherein the variable power generating unit comprises:

a high frequency signal generating unit configured to generate the high frequency signal having the constant amplitude; and

a switch controller configured to control ON and OFF states of a switch to modulate the high frequency signal based on the low frequency modulated signal to generate the variable power.

4. The apparatus of claim 1 , wherein the variable power generating unit comprises:

a high frequency signal generating unit configured to generate the high frequency signal having the constant amplitude; and

digital logic processing unit configured to perform a logic operation to modulate the high frequency signal based on the low frequency modulated signal to generate the variable power.

5. The apparatus of claim 1 , wherein the variable power generating unit comprises:

a high frequency signal generating unit configured to generate the high frequency signal having the constant amplitude; and

a controller configured to control operation of the high frequency signal generating unit based on the low frequency modulated signal to generate the variable power.

6. The apparatus of claim 5 , wherein the modulated signal generating unit generates the low frequency modulated signal by performing delta-sigma modulation.

7. The apparatus of claim 1 , wherein the power supply comprises a rectifying unit configured to rectify the AC voltage to generate the DC voltage.

8. The apparatus of claim 1 , wherein the power supply comprises:

a transforming unit configured to transform the AC voltage received from the power source to an AC voltage having a level corresponding to a rated voltage of the PA; and

a rectifying unit configured to rectify the AC voltage having the level corresponding to the rated voltage of the PA to generate the DC voltage.

9. The apparatus of claim 1 , wherein the PA is configured to operate in a switching mode or a saturated mode as an amplifier having a class selected from the group consisting of class D, class E, class F, class E/F, inverse class D, inverse class E, and inverse class F.

10. The apparatus of claim 1 , wherein the PA comprises at least one power device selected from the group consisting of a gallium nitride (GaN) power device, a silicon carbide (SiC) power device, a lateral double diffused metal oxide semiconductor (LDMOS) power device, and a metal oxide semiconductor field effect transistor (MOSFET).

11. A high efficiency variable power transmitting apparatus comprising:

a high frequency signal generating unit configured to generate a high frequency signal having a constant amplitude;

a power amplifier (PA) configured to amplify the high frequency signal to satisfy a requested power level of a target device based on a variable power supply voltage; and

a variable power supply configured to convert an alternating current (AC) voltage received from a power source to a direct current (DC) voltage, modulate the DC voltage with respect to a time axis by turning the DC voltage ON and OFF to generate the variable power supply voltage, and provide the variable power supply voltage to the PA;

wherein the variable power supply comprises a modulated signal generating unit configured to generate a low frequency modulated signal having a duty cycle depending on the requested power level of the target device.

12. The apparatus of claim 11 , wherein the variable power supply comprises:

a rectifying unit configured to rectify the AC voltage to generate the DC voltage and

a switch controller configured to control ON and OFF states of a switch to modulate the DC voltage based on the low frequency modulated signal to generate the variable power supply voltage.

13. The apparatus of claim 12 , wherein the modulated signal generating unit generates the low frequency modulated signal by performing delta-sigma modulation.

14. The apparatus of claim 11 , wherein the PA is configured to operate in a switching mode or a saturated mode as an amplifier having a class selected from the group consisting of class D, class E, class F, class E/F, inverse class D, inverse class E, and inverse class F.

15. The apparatus of claim 11 , wherein the PA comprises at least one power device selected from the group consisting of a gallium nitride (GaN) power device, a silicon carbide (SiC) power device, a lateral double diffused metal oxide semiconductor (LDMOS) power device, and a metal oxide semiconductor field effect transistor (MOSFET).

16. A high efficiency variable power transmitting method comprising:

converting an alternating current (AC) voltage received from a power source to a direct current (DC) voltage;

generating a power supply voltage having a predetermined level based on the DC voltage;

providing the power supply voltage having the predetermined level to a power amplifier (PA);

outputting a variable power by modulating, with respect to a time axis, a high frequency signal having a constant amplitude by turning the high frequency signal ON and OFF,

wherein the outputting comprises generating a low frequency modulated signal having a duty cycle depending on the requested power level of the target device; and

amplifying, using the PA, the variable power to satisfy a requested power level of a target device based on the power supply voltage having the predetermined level.

17. The method of claim 16 , wherein the outputting comprises:

generating the low frequency signal having the constant amplitude; and

controlling ON and OFF states of a switch to modulate the high frequency signal based on the low frequency modulated signal to generate the variable power.

18. The method of claim 16 , wherein the outputting comprises:

generating the high frequency signal having the constant amplitude; and

performing a logic operation to modulate the high frequency signal based on the low frequency modulated signal to generate the variable power.

19. The method of claim 16 , wherein the outputting of the variable power comprises:

generating, using a high frequency signal generating unit, the high frequency signal having the constant amplitude; and

controlling an operation of the high frequency signal generating unit based on the low frequency modulated signal to generate the variable power.

20. The method of claim 19 , wherein the generating of the low frequency modulated signal comprises generating the low frequency modulated signal by performing delta-sigma modulation.

21. A high efficiency variable power transmitting method comprising:

converting an alternating current (AC) voltage received from a power source to a direct current (DC) voltage;

generating a variable power supply voltage by modulating the DC voltage with respect to a time axis by turning the DC voltage ON and OFF,

wherein the generating of the variable power supply voltage comprises generating a low frequency modulated signal having a duty cycle depending on the requested power level of the target device;

providing the variable power supply voltage to a power amplifier (PA);

generating a high frequency signal having a constant amplitude; and

amplifying, using the PA, the high frequency signal to satisfy a requested power level of a target device based on the variable power supply voltage.

22. The method of claim 21 , wherein the generating of the variable power supply voltage comprises:

controlling ON and OFF states of a switch to modulate the DC voltage based on the low frequency modulated signal to generate the variable power supply voltage.

23. The method of claim 22 , wherein the generating of the low frequency modulated signal comprises generating the low frequency modulated signal by performing delta-sigma modulation.

24. A variable power transmitting apparatus comprising:

a variable power generating unit configured to output a variable power by modulating, with respect to a time axis, a high frequency signal having a constant amplitude by turning the high frequency signal ON and OFF, and configured to output a high frequency signal having ON states and OFF states having a duty cycle depending on a requested power level of a target device, the high frequency signal having a constant amplitude during the ON states,

wherein the variable power generating unit comprises:

a modulated signal generating unit configured to generate a low frequency modulated signal having a duty cycle depending on the requested power level of the target device;

a power supply configured to output a power supply voltage having a fixed predetermined level; and

a power amplifier (PA) operated by the power supply voltage having the fixed predetermined level and configured to amplify the high frequency signal to output a variable power satisfying the requested power level of the target device.

25. The apparatus of claim 24 , further comprising a transmitting unit configured to transmit the variable power output from the PA to the target device through a transmission coil comprising a metamaterial or an antenna comprising a metamaterial.

26. The apparatus of claim 24 , wherein the power supply is configured to convert an alternating current (AC) voltage to a direct current (DC) voltage having the fixed predetermined level, and provide the DC voltage to the PA as the power supply voltage having the fixed predetermined level.

27. The apparatus of claim 24 , wherein the PA has a maximum efficiency when operated by the power supply voltage having the fixed predetermined level, and has an efficiency lower than the maximum efficiency when operated by a power supply voltage having a level other than the fixed predetermined level.

28. A variable power transmitting apparatus comprising:

a variable power generating unit configured to output a variable power by modulating, with respect to a time axis, a high frequency signal having a constant amplitude by turning the high frequency signal ON and OFF;

a high frequency signal generating unit configured to output a high frequency signal having ON states and OFF states having a duty cycle depending on a requested power level of a target device, the high frequency signal having a constant amplitude during the ON states;

a variable power supply configured to output a variable power supply voltage having ON states and OFF states having a duty cycle depending on a requested power level of a target device, the variable power supply voltage having a fixed predetermined level during the ON states,

wherein the variable power supply comprises a modulated signal generating unit configured to generate a low frequency modulated signal having a duty cycle depending on the requested power level of the target device; and

a power amplifier (PA) operated by the variable power supply voltage and configured to amplify the high frequency signal to output a variable power satisfying the requested power level of the target device.

29. The apparatus of claim 28 , further comprising a transmitting unit configured to transmit the variable power output from the PA to the target device through a transmission coil comprising a metamaterial or an antenna comprising a metamaterial.

30. The apparatus of claim 28 , wherein the power supply is configured to convert an alternating current (AC) voltage to a direct current (DC) voltage having the fixed predetermined level, turn the DC voltage ON and OFF according to the requested power level of the target device to generate the variable power supply voltage, and provide the variable power supply voltage to the PA.

31. The apparatus of claim 28 , wherein the PA has a maximum efficiency when operated by a power supply voltage having the fixed predetermined level, and has an efficiency lower than the maximum efficiency when operated by a power supply voltage having a level other than the fixed predetermined level.

32. The apparatus of claim 1 , wherein the variable power generating unit comprises:

a modulated signal generating unit configured to determine the durations of the ON and OFF states of the high frequency signal to generate a low frequency modulated signal.

33. The apparatus of claim 1 , wherein the variable power generating unit comprises:

a modulated signal generating unit configured to determine a duty cycle that corresponds to the requested power level within in a predetermined period to generate a low frequency modulated signal,

wherein the length of the predetermined period determines how frequently the duty cycle of the low frequency modulated signal is updated by the modulated signal generating unit, and

wherein the length of the predetermined period determines how frequently the variable power generated by the variable power generating unit is updated.