Power feeding system during travelling
In a dynamic wireless power transfer system, a power transmission coil is provided in a road. A power transmission circuit supplies electric power to the power transmission coil. A power reception coil is provided in a vehicle. A power reception circuit is connected to the power reception coil. A relay circuit is provided in a tire of the vehicle. The relay circuit includes at least two relay coils that are connected in series. The relay circuit transfers electric power from the power transmission coil to the power reception coil by one relay coil of the two relay coils opposing the power transmission coil and the other relay coil opposing the power reception coil. A resonance frequency of the relay circuit is a frequency that is within a fixed range that is centered on an applied frequency of an alternating-current voltage that is applied to the power transmission coil.
1. A dynamic wireless power transfer system comprising:
a power transmission coil that is provided in a road;
a power transmission circuit that supplies electric power to the power transmission coil;
a power reception coil that is provided in a vehicle;
a power reception circuit that is connected to the power reception coil; and
a relay circuit that (i) is provided in a tire of the vehicle, (ii) includes at least two relay coils that are connected in series and arranged at positions that are different from each other in a circumferential direction of the tire, and (iii) transfers electric power from the power transmission coil to the power reception coil by first and second relay coils of the at least two relay coils, the first relay coil opposing the power transmission coil and the second relay coil opposing the power reception coil, wherein
a resonance frequency of the relay circuit is a frequency that is within a fixed range that is centered on an applied frequency of an alternating-current voltage that is applied to the power transmission coil.
2. The dynamic wireless power transfer system according to claim 1 , wherein:
the relay circuit includes a resonance capacitor that is connected in series to the at least two relay coils; and
a capacitance of the resonance capacitor is a capacitance at which the resonance frequency of the relay circuit is within the fixed range that is centered on the applied frequency, when inductance of the relay circuit is equal to or greater than a magnitude that is prescribed in advance.
3. The dynamic wireless power transfer system according to claim 2 , wherein:
the capacitance of the resonance capacitor is a capacitance at which the resonance frequency of the relay circuit is the applied frequency, when the inductance of the relay circuit is a local maximum.
4. The dynamic wireless power transfer system according to claim 3 , wherein:
the relay coils of the relay circuit correspond to a plurality of phases that have differing phases.
5. The dynamic wireless power transfer system according to claim 4 , further comprising:
a control apparatus that controls operations of the power transmission circuit, wherein
the vehicle includes
a front wheel tire and a rear wheel tire as the tire,
a first relay circuit that is provided in the front wheel tire and a second relay circuit that is provided in the rear wheel tire as the relay circuit, and
a first power transmission coil that transmits electric power to the first relay circuit that is provided in the front wheel tire and a second power transmission coil that transmits electric power to the second relay circuit that is provided in the rear wheel tire as the power transmission coil, and
the control apparatus adjusts a phase of a first voltage that is applied to the first power transmission coil and a phase of a second voltage that is applied to the second power transmission coil.
6. The dynamic wireless power transfer system according to claim 5 , wherein:
the phase of the second voltage is a phase that cancels out a magnetic flux that is generated by the phase of the first voltage.
7. The dynamic wireless power transfer system according to claim 6 , wherein:
the control apparatus controls the phase of the first voltage and the phase of the second voltage to be opposite phases.
8. The dynamic wireless power transfer system according to claim 7 , wherein:
the control apparatus
acquires wheelbase information of the vehicle from the vehicle, and
adjusts the phase of the first voltage and the phase of the second voltage.
9. The dynamic wireless power transfer system according to claim 8 , wherein:
the control apparatus
acquires steering angle information and vehicle speed information of the vehicle, and
controls magnitudes of the first voltage and the second voltage based on the steering angle information and the vehicle speed information.
10. The dynamic wireless power transfer system according to claim 9 , wherein:
the control apparatus
controls a timing from when a voltage is applied to the first power transmission coil until a voltage is applied to the second power transmission coil based on the vehicle speed information and the wheelbase information of the vehicle.
11. The dynamic wireless power transfer system according to claim 1 , wherein:
the relay coils of the relay circuit correspond to a plurality of phases that have differing phases.
12. The dynamic wireless power transfer system according to claim 1 , further comprising:
a control apparatus that controls operations of the power transmission circuit, wherein
the vehicle includes
a front wheel tire and a rear wheel tire as the tire,
a first relay circuit that is provided in the front wheel tire and a second relay circuit that is provided in the rear wheel tire as the relay circuit, and
a first power transmission coil that transmits electric power to the first relay circuit that is provided in the front wheel tire and a second power transmission coil that transmits electric power to the second relay circuit that is provided in the rear wheel tire as the power transmission coil, and
the control apparatus adjusts a phase of a first voltage that is applied to the first power transmission coil and a phase of a second voltage that is applied to the second power transmission coil.
13. The dynamic wireless power transfer system according to claim 5 , wherein:
the control apparatus
acquires wheelbase information of the vehicle from the vehicle, and
adjusts the phase of the first voltage and the phase of the second voltage.
14. The dynamic wireless power transfer system according to claim 5 , wherein:
the control apparatus
acquires steering angle information and vehicle speed information of the vehicle, and
controls magnitudes of the first voltage and the second voltage based on the steering angle information and the vehicle speed information.
15. The dynamic wireless power transfer system according to claim 5 , wherein:
the control apparatus
acquires vehicle speed information and wheelbase information of the vehicle from the vehicle, and
controls a timing from when a voltage is applied to the first power transmission coil until a voltage is applied to the second power transmission coil based on the vehicle speed information and the wheelbase information of the vehicle.
16. The dynamic wireless power transfer system according to claim 1 , wherein:
the first and second relay coils are located at diametrically opposite portions of a circumference of the tire.
17. The dynamic wireless power transfer system according to claim 16 , wherein:
the first and second relay coils do not overlap each other in the circumferential direction of the tire.
18. The dynamic wireless power transfer system according to claim 1 , wherein:
the first and second relay coils do not overlap each other in the circumferential direction of the tire.
19. The dynamic wireless power transfer system according to claim 1 , wherein:
the at least two relay coils includes at least two pairs of the relay coils, the relay coils of each of the pairs arranged at positions that are different from each other in the circumferential direction of the tire.
20. The dynamic wireless power transfer system according to claim 19 , wherein:
the relay coils of each of the pairs are located at diametrically opposite portions of a circumference of the tire and do not overlap each other in the circumferential direction of the tire.