Power transmitting device and wireless power transmission system
A power transmitting device according to one embodiment includes a power transmitting antenna, an oscillator, control circuitry, and a communication circuit. The control circuitry sets an initial value of a phase shift amount, causes the oscillator to output preliminary AC power of a voltage corresponding to the initial value, reduces the phase shift amount from the initial value at predetermined time intervals, causes the oscillator to output preliminary AC power of each voltage corresponding to each of the reduced phase shift amounts, fixes the phase shift amount upon activation of control circuitry in the power receiving device upon receipt of a first response signal indicating the activation of the control circuitry in the power receiving device from the power receiving device through the communication circuit, and transmits the AC power while maintaining the voltage corresponding to the fixed phase shift amount.
1. A power transmitting device comprising:
a power transmitting antenna that transmits AC power wirelessly to the power receiving antenna of a power receiving device;
an oscillator that includes i) a first switching element group connected to a high potential terminal of DC power supply and ii) a second switching element group connected to a low potential terminal of the DC power supply, iii) a first terminal connected to the first switching element group and iv) a second terminal connected to the second switching element groups, and the oscillator converts DC power of the DC power supply into the AC power by using the first and second switching element groups and outputs the AC power to the power transmitting antenna via the first terminal and the second terminal;
a communication circuit that receives signals from the power receiving device; and
control circuitry operative to:
supply pulse signals which control the first and second switching element groups to the oscillator;
change a phase shift amount between a first pulse signal and a second pulse signal, the first pulse signal supplied to one of the first and second switching element groups, the second pulse signal supplied to the other one of the first and second switching element groups;
cause the oscillator to change the voltage of the AC power output;
set an initial value of the phase shift amount when a current flowing through the power transmitting antenna exceeds a predetermined value after the power transmitting antenna transmits the AC power to the power receiving antenna;
cause the oscillator to output preliminary AC power of a voltage corresponding to the initial value of the phase shift amount, and to reduce the phase shift amount from the initial value, and to output preliminary AC power of each voltage corresponding to each of the reduced phase shift amounts;
fix the phase shift amount when the communication circuit receives a first response signal indicating an activation of a control circuitry in the power receiving device in order to wait for reception of a second response signal indicating a maximum power set in the power receiving device; and
cause the oscillator to output the AC power while maintaining the voltage corresponding to the fixed phase shift amount.
2. The power transmitting device according to claim 1 , wherein
the first response signal includes a signal strength packet specified by the Qi standard of WPC (wireless power consortium).
3. The power transmitting device according to claim 2 , wherein
the signal strength packet includes a signal strength value indicating a voltage corresponding to a phase shift amount upon activation of the control circuitry in the power receiving device.
4. The power transmitting device according to claim 1 , wherein
the second response signal includes a configuration packet specified by the Qi standard of WPC (wireless power consortium).
5. The power transmitting device according to claim 1 , wherein
the control circuitry waits for a third response signal indicating a manufacturer ID of the power receiving device to be transmitted from the power receiving device after the second response signal.
6. The power transmitting device according to claim 5 , wherein
the third response signal includes an identification packet specified by the Qi standard of WPC (wireless power consortium).
7. The power transmitting device according to claim 5 , wherein
the control circuitry waits for a fourth response signal to be transmitted from the power receiving device after the third response signal, the fourth response signal including a control error value indicating a difference value between a required voltage value of the power receiving device and a voltage value of the AC power from the power transmitting antenna.
8. The power transmitting device according to claim 7 , wherein
the fourth response signal includes a control error packet specified by the Qi standard of WPC (wireless power consortium).
9. The power transmitting device according to claim 7 , wherein
the control circuitry performs control, upon receipt of the fourth response signal, to reduce the difference value, which is indicated by the control error signal included in the fourth response signal, close to zero by changing the voltage of the AC power based on a change in the phase shift amount.
10. The power transmitting device according to claim 1 , wherein
the first switching element group includes at least two switching elements, and
the second switching element group includes at least two switching elements.
11. The power transmitting device according to claim 1 , wherein
the control circuitry reduces the phase shift amount from the initial value every time the pulse signal is supplied to the oscillator.
12. A wireless power transmission system comprising:
a power receiving device that includes a power receiving antenna; and
a power transmitting device that includes
a power transmitting antenna that transmits AC power wirelessly to the power receiving antenna of the power receiving device;
an oscillator that includes i) a first switching element group connected to a high potential terminal of DC power supply and ii) a second switching element group connected to a low potential terminal of the DC power supply, iii) a first terminal connected to the first switching element group and iv) a second terminal connected to the second switching element groups, and the oscillator converts DC power of the DC power supply into the AC power by using the first and second switching element groups and outputs the AC power to the power transmitting antenna via the first terminal and the second terminal;
a communication circuit that receives signals from the power receiving device; and
control circuitry operative to:
supply pulse signals which control the first and second switching element groups to the oscillator;
change a phase shift amount between a first pulse signal and a second pulse signal, the first pulse signal supplied to one of the first and second switching element groups, the second pulse signal supplied to the other one of the first and second switching element groups;
change the voltage of the AC power output from the oscillator;
set an initial value of the phase shift amount when a current flowing through the power transmitting antenna exceeds a predetermined value after the power transmitting antenna transmits the AC power to the power receiving antenna;
cause the oscillator to output preliminary AC power of a voltage corresponding to the initial value, and to reduce the phase shift amount from the initial value, and to output preliminary AC power of each voltage corresponding to each of the reduced phase shift amounts;
fix the phase shift amount when the communication circuit receives a first response signal indicating an activation of a control circuitry in the power receiving device in order to wait for reception of a second response signal indicating a maximum power set in the power receiving device; and
cause the oscillator to output the AC power while maintaining the voltage corresponding to the fixed phase shift amount.
13. A power transmitting device comprising:
a power transmitting antenna that transmits the AC power wirelessly to the power receiving antenna of a power receiving device;
an oscillator that includes i) a first switching element group connected to a high potential terminal of DC power supply and ii) a second switching element group connected to a low potential terminal of the DC power supply, iii) a first terminal connected to the first switching element group and iv) a second terminal connected to the second switching element groups, and the oscillator converts DC power of the DC power supply into the AC power by using the first and second switching element groups and outputs the AC power to the power transmitting antenna via the first terminal and the second terminal;
a communication circuit that receives signals from the power receiving device; and
control circuitry operative to:
supply to the oscillator pulse signals which control the first and second switching element groups;
change a phase shift amount between a first pulse signal and a second pulse signal, the first pulse signal supplied to one of the first and second switching element groups, the second pulse signal supplied to the other one of the first and second switching element groups;
change the voltage of the AC power output from the oscillator;
set an initial value of the phase shift amount when a current flowing through the power transmitting antenna exceeds a predetermined value after the power transmitting antenna transmits the AC power to the power receiving antenna;
cause the oscillator to output preliminary AC power of a voltage corresponding to the initial value, and to reduce the phase shift amount from the initial value, and to output preliminary AC power of each voltage corresponding to each of the reduced phase shift amounts;
fix the phase shift amount when the communication circuit receives a first response signal indicating an activation of a control circuitry in the power receiving device in order to wait for reception of a second response signal including control information used for the transmission of the AC power; and
cause the oscillator to output the AC power while maintaining the voltage corresponding to the fixed phase shift amount.
14. The power transmitting device according to claim 13 , wherein
the first switching element group includes at least two switching elements, and
the second switching element group includes at least two switching elements.