Wireless power transmission apparatus and method and wireless power reception apparatus

1. A wireless power transmission apparatus comprising:

a measurer configured to measure a first value of a current flowing in a source resonator;

a communication unit configured to receive a second value of a charging current of a battery from a wireless power reception apparatus; and

a power controller configured to control an amount of power to be transmitted by the source resonator based on an internal offset and a power transmission efficiency offset, wherein the internal offset determined based on the first value and a reference current value that is distinct from the second value and the power transmission efficiency offset is determined based on the second value and the reference current value.

2. The apparatus of claim 1 , wherein the power controller comprises:

a charging mode determiner configured to determine a charging mode of the battery based on a change in the second value; and

a pulse signal generator configured to generate a pulse signal having a pulse width adjusted based on the determined charging mode of the battery.

3. The apparatus of claim 2 , wherein the charging mode determiner is further configured to determine whether the charging mode of the battery is a constant current (CC) mode in which the value of the charging current of the battery is constant, or a constant voltage (CV) mode in which the value of the charging current of the battery is variable and a value of a charging voltage of the battery is constant.

4. The apparatus of claim 2 , further comprising:

an alternating current-to-direct current (AC/DC) converter configured to convert an AC power supplied from a power supply to a DC power based on the pulse width of the pulse signal; and

a DC-to-AC (DC/AC) converter configured to convert the DC power to an AC power based on a resonant frequency of the source resonator.

5. The apparatus of claim 1 , wherein

the power controller comprises:

an offset calculator configured to calculate the power transmission efficiency offset; and

a pulse signal generator configured to generate a pulse signal having a pulse width adjusted based on the power transmission efficiency offset.

6. The apparatus of claim 1 , wherein

the power controller comprises:

a charging mode determiner configured to determine a charging mode of the battery based on a change in the second value;

an offset calculator configured to calculate the power transmission efficiency offset; and

a pulse signal generator configured to generate a pulse signal having a pulse width adjusted based on the determined charging mode of the battery and the power transmission efficiency offset.

7. The apparatus of claim 6 , further comprising:

a first comparator configured to compare the first value with a reference current value; and

a second comparator configured to compare the second value with the reference current value;

wherein the pulse signal generator is further configured to adjust the pulse width of the pulse signal based on a difference between a result of the comparing by the first comparator and a result of the comparing by the second comparator.

8. The apparatus of claim 1 , wherein the communication unit is further configured to receive, from the wireless power reception apparatus, a value of a current flowing in a rectifier as the second value.

9. The apparatus of claim 1 , wherein the wireless power reception apparatus is configured to receive power from a target resonator;

the source resonator comprises a coil;

the target resonator comprises a coil; and

a ratio of a number of turns of the coil of the source resonator to a number of turns of the coil of the target resonator is a 1:1 ratio.

10. A wireless power reception apparatus comprising:

a rectifier configured to rectify an alternating current (AC) power received from a wireless power transmission apparatus by a target resonator through a mutual resonance with a source resonator to a direct current (DC) power;

a measurer configured to measure a first value of a current flowing in the target resonator; and

a communication unit configured to transmit the first value to the wireless power transmission apparatus,

wherein the AC power is controlled by the wireless power transmission apparatus based on a power transmission efficiency offset and an internal offset, the power transmission efficiency offset determined based on the first value and the reference current value and the internal offset determined based on the reference current value and a second value which is a value of a current flowing in a source resonator.

11. The apparatus of claim 10 , wherein the measurer is further configured to measure a third value of a current flowing from the rectifier into a battery; and

the communication unit is further configured to transmit the third value to the wireless power transmission apparatus.

12. The apparatus of claim 11 , further comprising a controller configured to determine a charging mode of the battery based on a change in the third value.

13. The apparatus of claim 10 , wherein the communication unit is further configured to communicate with the wireless power transmission apparatus using either one or both of an in-band communication scheme using a resonant frequency of the target resonator and an out-band communication scheme using a communication frequency differing from the resonant frequency.

14. A wireless power transmission method comprising:

measuring a first value of a current flowing in a source resonator;

receiving a second value of a charging current of a battery from a wireless power reception apparatus; and

controlling an amount of power to be transmitted by the source resonator based on an internal offset and a power transmission efficiency offset, wherein the internal offset determined based on the first value and a reference current value that is distinct from the second value and the power transmission efficiency offset is determined based on the second value and the reference current value.

15. The method of claim 14 , wherein the controlling comprises:

determining a charging mode of the battery based on a change in the second value; and

generating a pulse signal having a pulse width adjusted based on the determined charging mode of the battery.

16. The method of claim 15 , further comprising:

converting an alternating current (AC) power supplied from a power supply to a direct current (DC) power based on the pulse width of the pulse signal; and

converting the DC power to an AC power based on a resonant frequency of the source resonator.

17. The method of claim 14 , wherein

the controlling comprises:

calculating the power transmission efficiency offset; and

generating a pulse signal having a pulse width adjusted based on the power transmission efficiency offset.

18. The method of claim 14 ,

wherein the controlling comprises:

determining a charging mode of the battery based on a change in the second value;

calculating a power transmission efficiency offset; and

generating a pulse signal having a pulse width adjusted based on the determined charging mode of the battery and calculated power transmission efficiency offset.

19. A wireless power transmission apparatus comprising:

a measurer configured to measure a first information indicative of an amount of power being transmitted by a source resonator;

a communication unit configured to receive, from a wireless power reception apparatus, measured a second information indicative of an amount of power being consumed by a load powered by the wireless reception apparatus; and

a controller configured to control an amount of power to be transmitted by the source resonator based on an internal offset and a power transmission efficiency offset, wherein the internal offset determined based on the first value and a reference current value that is distinct from the second value and the power transmission efficiency offset is determined based on the second value and the reference current value.