Wireless power receiver and method for controlling the same
A wireless power receiver according to an exemplary embodiment in the present disclosure may include a resonant tank receiving a power signal and varying a resonant frequency in response to a control signal; and a determining unit determining a wireless power transmission mode on the basis of the power signal and outputting the control signal depending on a determination result.
1. A wireless power receiver comprising:
a resonant tank receiving a power signal and varying a resonant frequency in response to a control signal; and
a determining unit determining a wireless power transmission mode on the basis of the power signal and outputting the control signal depending on a determination result, wherein the determining unit comprises
a detecting unit receiving the power signal and outputting a detection signal, and
a controlling unit calculating a pulse width of the detection signal and outputting the control signal depending on the pulse width.
2. The wireless power receiver of claim 1 , wherein the detecting unit is a band-pass filter.
3. The wireless power receiver of claim 1 , wherein the controlling unit outputs the control signal so that the resonant tank of the resonant frequency is adjusted to be a first frequency when the pulse width is higher than a reference value, and outputs the control signal so that the resonant frequency of the resonant tank is adjusted to be a second frequency higher than the first frequency when the pulse width is equal to or lower than the reference value.
4. The wireless power receiver of claim 1 , wherein the controlling unit includes:
a logical AND gate performing a logical AND operation on a clock signal and the detection signal;
a counter counting the number of pulses included in an output signal of the logical AND gate; and
a control signal generating unit outputting the control signal depending on an output value of the counter.
5. The wireless power receiver of claim 1 , wherein the resonant tank includes:
a power receiving coil;
a first capacitor connected between one end of the power receiving coil and an output terminal from which input power is output;
a second capacitor having one end connected to one end of the power receiving coil; and
a switching unit turned on and off in response to the control signal and connected between the other end of the second capacitor and the output terminal.
6. The wireless power receiver of claim 5 , wherein the determining unit receives a signal between the output terminal and the other end of the power receiving coil as the power signal.
7. The wireless power receiver of claim 5 , wherein the determining unit receives signals from both ends of the power receiving coil as the power signal.
8. The wireless power receiver of claim 5 , wherein the switching unit includes a plurality of switches connected to each other in series.
9. The wireless power receiver of claim 5 , further comprising:
a rectifying unit rectifying the input power to output the rectified power; and
an outputting unit receiving the rectified power to output power having a predetermined magnitude.
10. The wireless power receiver of claim 1 , wherein the power signal is a ping signal output from a wireless power transmitter.
11. The wireless power receiver of claim 1 , further comprising a protecting unit limiting a voltage applied to the determining unit to be equal to or lower than a reference voltage.
12. A method for controlling a wireless power receiver including a resonant tank, the method comprising:
receiving a power signal by using the resonant tank;
determining a wireless power transmission mode on the basis of the power signal; and
adjusting a resonant frequency of the resonant tank according to the wireless power transmission mode, wherein the determining of the wireless power transmission mode comprises
filtering the power signal to the output a detection signal,
caluculating a pulse width of the detection signal, and
determining the wireless power transmission mode depending on the pulse width.
13. The method of claim 12 , wherein when the pulse width is higher than a reference value, the resonant frequency of the resonant tank is adjusted to be a first frequency, and
when the pulse width is equal to or lower than the reference value, the resonant frequency of the resonant tank is adjusted to be a second frequency higher than the first frequency.
14. The method of claim 12 , wherein the calculating of the pulse width includes:
performing a logical AND operation on a clock signal and the detection signal to generate a logical AND signal; and
counting the number of pulses of the logical AND signal.
15. The method of claim 12 , wherein the resonant frequency of the resonant tank is adjusted by controlling capacitance of the resonant tank.
16. The method of claim 15 , wherein the resonant tank includes a power receiving coil, a first capacitor connected between one end of the power receiving coil and an output terminal from which input power is output, a second capacitor having one end connected to one end of the power receiving coil, and a switching unit connected between the other end of the second capacitor and the output terminal.
17. The method of claim 16 , wherein the resonant frequency of the resonant tank is adjusted by turning the switching unit on and off.
18. The method of claim 12 , wherein the power signal is a ping signal output from a wireless power transmitter.