Receiving circuit for magnetic coupling resonant wireless power transmission

1. A receiving circuit for magnetic coupling resonant wireless power transmission comprising:

a resonant circuit comprising a resonant coil and a resonant capacitor;

a rectifying circuit having an input electrically connected to two terminals of the resonant capacitor;

a storage capacitor having two terminals electrically connected to an output of rectifying circuit; and

an output circuit having an input electrically connected to the two terminals of the storage capacitor and an output configured to be electrically connected to a battery, the output circuit configured to operate as a filter in a first mode and as a boost converter in a second mode.

2. The receiving circuit for magnetic coupling resonant wireless power transmission according to claim 1 , wherein the output circuit comprises an inductor, a diode and a metal oxide semiconductor field effect transistor, wherein a first terminal of the inductor is electrically connected to a first one of the two terminals of the storage capacitor, a second terminal of the inductor is electrically connected to an anode of the diode and a drain of the metal oxide semiconductor field effect transistor, a source of the metal oxide semiconductor field effect transistor is electrically connected to a second one of the two terminals of the storage capacitor, and a cathode of the diode and a source of the metal oxide semiconductor field effect transistor act as an output of the output circuit.

3. The receiving circuit for magnetic coupling resonant wireless power transmission according to claim 2 , wherein the output circuit comprises a filtering capacitor and a first switch connected in series and electrically connected to the drain and source of the metal oxide semiconductor field effect transistor.

4. The receiving circuit for magnetic coupling resonant wireless power transmission according to claim 3 , wherein the output circuit comprises a second switch connected in parallel with the diode.

5. The receiving circuit for magnetic coupling resonant wireless power transmission according to claim 1 , wherein the rectifying circuit is a full bridge rectifying circuit.

6. A system comprising:

a resonant wireless transmitting circuit; and

a receiving circuit comprising:

a resonant circuit comprising a resonant coil and a resonant capacitor;

a rectifying circuit having an input electrically connected to an output of the resonant circuit;

a storage capacitor having two terminals electrically connected to an output of rectifying circuit; and

an output circuit configured to operate as a filter in first mode and as a boost converter in a second mode and comprising an inductor, a diode, a metal oxide semiconductor field effect transistor, a filtering capacitor and a first switch, wherein a first terminal of the inductor is electrically connected to a first one of the two terminals of the storage capacitor, a second terminal of the inductor is electrically connected to an anode of the diode and a drain of the metal oxide semiconductor field effect transistor, a source of the metal oxide semiconductor field effect transistor is electrically connected to a second one of the two terminals of the storage capacitor, a cathode of the diode and a source of the metal oxide semiconductor field effect transistor act as an output of the output circuit configured to be electrically connected to a battery,

and the filtering capacitor and the first switch are connected in series between the drain and the source of the metal oxide semiconductor field effect transistor.

7. The system according to claim 6 , wherein the output circuit further comprises a second switch connected in parallel with the diode.

8. The system according to claim 7 , further comprising:

a main control device including a main central processing unit (CPU), a main transceiver module and a first driver module;

a sub control device including a sub CPU, a sub transceiver module and a second driver module;

a charging detection module configured to detect a charging status of the battery and to provide charging status data of the battery to the sub CPU;

a voltage detection module configured to detect a voltage of the storage capacitor and to provide a voltage value of the storage capacitor to the sub CPU;

wherein the sub CPU is configured to transmit the charging status data and the voltage value of the storage capacitor to the main CPU via the sub transceiver module and the main transceiver module, the main CPU is configured to control a semiconductor switch of the resonant wireless transmitting circuit to operate the resonant wireless transmitting circuit in a pulse frequency modulation via the first driver module according to the charging status data and the voltage value of the storage capacitor, and the sub CPU is configured to control the metal oxide semiconductor field effect transistor to switch off and control the first switch and the second switch to be in on-state or off-state simultaneously via the second driver module according to the charging status data and the voltage value of the storage capacitor; or

the sub CPU is configured to transmit the charging status data and the voltage value of the storage capacitor to the main CPU via the sub transceiver module and the main transceiver module, the main CPU is configured to control the semiconductor switch of the resonant wireless transmitting circuit to switch off via the first driver module according to the charging status data and the voltage value of the storage capacitor, the sub CPU is configured to control the metal oxide semiconductor field effect transistor to operate in a pulse width modulation and control the first switch and the second switch to be in off-state simultaneously via the second driver module according to the charging status data and the voltage value of the storage capacitor.

9. A method of operating the system according to claim 8 , the method comprising:

(a) when the voltage of the battery is lower than a first predetermined threshold voltage, controlling the resonant transmitting circuit to operate in a pulse frequency modulation and the metal oxide semiconductor field effect transistor to switch off; and

(b) when the voltage of the battery is higher than the first predetermined threshold voltage, controlling the resonant transmitting circuit to work intermittently, wherein:

when the voltage value of the storage capacitor is higher than a second predetermined threshold voltage, controlling the resonant transmitting circuit to switch off and the metal oxide semiconductor field effect transistor to operate in a pulse width modulation, so that the storage capacitor charges the battery; and

when the voltage value of the storage capacitor is lower than the second predetermined threshold voltage, controlling the resonant transmitting circuit to operate in a pulse frequency modulation and the metal oxide semiconductor field effect transistor to switch off, so that the resonant transmitting circuit charges the storage capacitor via the resonant circuit and the rectifying circuit.

10. The method according to claim 9 , wherein the receiving circuit further comprises a filtering capacitor and a first switch, wherein the filtering capacitor and the first switch are connected in series and electrically connected to the drain and source of the metal oxide semiconductor field effect transistor, and wherein the method further comprises:

in the step (a), controlling the first switch to switch on; and

in the step (b), controlling the first switch to switch off.

11. The method according to claim 10 , wherein the receiving circuit further comprises a second switch connected in parallel with the diode, and wherein the method further comprises:

in the step (a), controlling the second switch to switch on; and

in the step (b), controlling the second switch to switch off.

12. An apparatus comprising:

a resonant circuit comprising a resonant coil and a resonant capacitor;

a rectifying circuit having an input electrically connected to the resonant capacitor;

a storage capacitor electrically connected to an output of rectifying circuit; and

an output circuit having an input electrically connected to the storage capacitor and an output configured to be connected to a battery, the output circuit further configured to operate as a filter in a first mode and as a boost converter in a second mode.

13. The apparatus of claim 12 : wherein the output circuit comprises:

an inductor having first terminal connected to the storage capacitor;

a diode having an anode connected to a second terminal of the inductor and a cathode configured to be connected to a first terminal of the battery;

a transistor having a first terminal connected to the anode of the diode and the second terminal of the inductor and a second terminal configured to be connected to a second terminal of the battery; and

a filter capacitor and switch connected in series between the second terminal of the inductor and the second terminal of the battery.

14. The apparatus of claim 13 , further comprising a control circuit configured to close the switch in the first mode and to open the switch in the second mode.

15. The apparatus of claim 14 , wherein the switch comprises a first switch and further comprising a second switch connected in parallel with the diode.

16. The apparatus of claim 15 , wherein the control circuit is configured to close the switch in the first mode and to open the switch in the second mode.

17. The apparatus of claim 12 , further comprising a resonant wireless transmission circuit wirelessly coupled to the resonant circuit and configured to operate in a pulse frequency modulation (PFM) when the output circuit is in the first mode and to be deactivated when the output circuit is in the second mode.

18. The apparatus of claim 17 , further comprising a control circuit configured to control the resonant wireless transmission circuit and the output circuit responsive to a state of the battery and/or a state of the storage capacitor.