WIRELESS POWER TRANSFER CONTROL METHOD AND WIRELESS POWER TRANSFER SYSTEM

• US 20170063168A1
• Filed: 11/15/2016
• Published: 03/02/2017
• Est. Priority Date: 05/20/2014
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Uchida, Akiyoshi
• Granted Patent: US 10,693,322 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment

Abstract

A wireless power transfer control method for a system including at least one power source and at least two power receivers, wirelessly transfers power from the power source to each of the power receivers using one of magnetic field resonance and electric field resonance, including a simultaneous power transfer mode in which power is simultaneously transferred to the power receivers; and a time-division power transfer mode in which power is sequentially transferred to the power receivers by time-division switching. The wireless power transfer control method includes setting an evaluation index for each of the power receivers; and performing wireless power transfer by switching between the simultaneous power transfer mode and the time-division power transfer mode, on the basis of the evaluation index.

Claims

1. A wireless power transfer control method for a system including at least one power source and at least two power receivers, wirelessly transfers power from the power source to each of the power receivers using one of magnetic field resonance and electric field resonance, comprising:

a simultaneous power transfer mode in which power is simultaneously transferred to the power receivers; and

a time-division power transfer mode in which power is sequentially transferred to the power receivers by time-division switching, wherein the wireless power transfer control method comprises;

setting an evaluation index for each of the power receivers; and

performing wireless power transfer by switching between the simultaneous power transfer mode and the time-division power transfer mode, on the basis of the evaluation index.

2. The wireless power transfer control method according to claim 1, wherein

the evaluation index is calculated on the basis of

a first index indicating a degree of coupling of electromagnetic fields in the power source and an interval between the power receivers, and

a second index indicating a degree of loss of the electromagnetic fields in the power source and the interval between the power receivers.

3. The wireless power transfer control method according to claim 2, wherein

the first index comprises a k value,

the second index comprises a Q value, and

the evaluation index is calculated as a product of the k value and the Q value.

4. The wireless power transfer control method according to claim 3, wherein

the k value is calculated on the basis of specification information defined between the power source and the power receiver and a relative positional relationship between the power source and the power receiver.

5. The wireless power transfer control method according to claim 1, wherein

power transfer is performed in the time-division power transfer mode for a power receiver, the evaluation index of which is smaller than a predetermined first set value, and

power transfer is performed in the simultaneous power transfer mode for a plurality of power receivers, the evaluation indices of which are not less than the predetermined first set value.

6. The wireless power transfer control method according to claim 5, wherein

when at least three power receivers have the evaluation index that is not less than the first set value, the power receivers are classified into a group on the basis of values of the evaluation indices, and

it is determined that power transfer is performed in the simultaneous power transfer mode for a plurality of power receivers within the group.

7. The wireless power transfer control method according to claim 6, wherein

the power receivers are classified into a group on the basis of values of the evaluation indices so that power receivers having close evaluation indices belong to an identical group.

8. The wireless power transfer control method according to claim 6, wherein

when a reduction in power transfer efficiency falls outside a tolerance upon power transfer to a plurality of power receivers within the group in the simultaneous power transfer mode, power transfer is performed in the time-division power transfer mode instead of the simultaneous power transfer mode.

9. The wireless power transfer control method according to claim 5, wherein

power transfer to the power receivers in the simultaneous power transfer mode is performed by setting a power distribution ratio on the basis of a power requirement of each power receiver.

10. The wireless power transfer control method according to claim 7, wherein

the power distribution ratio is set by shifting a resonance point of a power receiver resonance coil in a power receiver having a power requirement lower than a received power thereof.

11. The wireless power transfer control method according to claim 10, wherein

the resonance point of the power receiver resonance coil is shifted by changing a capacitance of a capacitor in the power receiver resonance coil.

12. The wireless power transfer control method according to claim 10, wherein

the setting of the power distribution ratio is predefined as preliminary arithmetic data.

13. A wireless power transfer system including at least one power source and at least two power receivers, and wirelessly transfers power from the power source to each of the power receivers using one of magnetic field resonance and electric field resonance, wherein the wireless power transfer system comprises:

a simultaneous power transfer mode in which power is simultaneously transferred to the power receivers; and

a time-division power transfer mode in which power is sequentially transferred to each of the power receivers by time-division switching, wherein

wireless power transfer is performed by switching between the simultaneous power transfer mode and the time-division power transfer mode, on the basis of an evaluation index set for each of the power receivers.

14. The wireless power transfer system according to claim 13, wherein

the evaluation index comprises a product of

a k value indicating a degree of coupling of electromagnetic fields in the power source and an interval between the power receivers, and

a Q value indicating a degree of loss of the electromagnetic fields in the power source and the interval between the power receivers.

15. The wireless power transfer system according to claim 13, wherein

power transfer is performed in the time-division power transfer mode for a power receiver, the evaluation index of which is smaller than a predetermined first set value, and

power transfer is performed in the simultaneous power transfer mode for a plurality of power receivers, the evaluation indices of which are not less than the predetermined first set value.

16. The wireless power transfer system according to claim 15, wherein

when at least three power receivers have the evaluation index that is not less than the first set value, the power receivers are classified into a group on the basis of values of the evaluation indices, and

it is determined that power transfer is performed in the simultaneous power transfer mode for a plurality of power receivers within the group.

17. The wireless power transfer system according to claim 16, wherein

when a reduction in power transfer efficiency falls outside a tolerance upon power transfer to a plurality of power receivers within the group in the simultaneous power transfer mode, power transfer is performed in the time-division power transfer mode instead of the simultaneous power transfer mode.

18. The wireless power transfer system according to claim 13, wherein

the wireless power transfer system comprises at least two power sources and performs three-dimensional wireless power transfer to each of the power receivers.