Power transmission system

• US 8,987,941 B2
• Filed: 08/10/2011
• Issued: 03/24/2015
• Est. Priority Date: 08/10/2010
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Ichikawa, Keiichi
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): Laguerre, Carlos
• Application Number:
  US13/207,015
• Publication Number:
  US 20120038218A1
• Time in Patent Office: 1,322 Days
• Field of Search: 307/104, 455/62, 455/63.368, 455/703, 455/71, 455/75, 455/113, 455/136, 455/150.1, 455/161.1, 455/164.1, 455/169.1, 455/193.2, 455/195.1, 455/227, 455/262
• US Class Current: 307/104
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H02J 7/0049 Detection of fully charged condition

Abstract

A power transmission system a power transmission apparatus, a center frequency acquiring unit, and a control unit. The power transmission apparatus includes a primary-side coupling electrode electrically configured to couple to a secondary-side coupling electrode and connected load circuit of a power receiving apparatus, a high-frequency voltage generating circuit configured to generate and apply a high-frequency voltage to the primary-side coupling electrode, and a driving power circuit that supplies driving power to the high-frequency voltage generating circuit. The center frequency acquiring unit acquires a center frequency at which a high-frequency high voltage applied to coupling electrode is minimized in a state in which a low load is applied to the secondary-side coupling electrode of the power receiving apparatus and the frequency of the generated high-frequency voltage is varied. The control unit sets a driving frequency of the high-frequency voltage generating circuit at or near the center frequency to supply power to the power receiving apparatus.

Claims

1. A power transmission system comprising:

a power transmission apparatus including a primary-side coupling electrode configured to electrically couple to a secondary-side coupling electrode and connected to a load circuit of a power receiving apparatus, a high-frequency voltage generating circuit configured to generate and apply a high-frequency voltage to the primary-side coupling electrode, and a driving power circuit that supplies driving power to the high-frequency voltage generating circuit;

a center frequency acquiring unit configured to sweep a frequency range to acquire a center frequency in a state in which electrical coupling between the secondary-side coupling electrode and the load circuit is weakened, the center frequency being a frequency at which the generated high-frequency voltage is minimized or substantially minimized with respect to variation in frequency of the high-frequency voltage generated by the high-frequency voltage generating circuit; and

a control unit configured to set a driving frequency, which is the frequency of the high-frequency voltage generated by the high-frequency high voltage generating circuit, to the center frequency or a frequency near the center frequency and supply power to the power receiving apparatus;

wherein a resonant frequency of a first resonant circuit composed of the primary-side coupling electrode and the high-frequency voltage generating circuit substantially coincides with a resonant frequency of a second resonant circuit composed of the secondary-side coupling electrode and the load circuit, and

wherein the center frequency acquiring unit is further configured to acquire the high-frequency voltage within a frequency range including the frequencies of two coupling modes occurring in a state in which the first resonant circuit is coupled to the second resonant circuit.

2. The power transmission system according to claim 1,

wherein a resonant frequency of a first resonant circuit composed of the primary-side coupling electrode and the high-frequency voltage generating circuit substantially coincides with a resonant frequency of a second resonant circuit composed of the secondary-side coupling electrode and the load circuit, and

wherein the control unit is further configured to set the driving frequency within a frequency range from a higher frequency, among the frequencies of two coupling modes occurring in a state in which the first resonant circuit is coupled to the second resonant circuit, to the center frequency.

3. The power transmission system according to claim 1, further comprising:

a voltage detecting unit configured to detect a high-frequency voltage generated by the high-frequency voltage generating circuit,

wherein the control unit is further configured to stop the supply of the power from the driving power circuit to the high-frequency voltage generating circuit if the voltage detected by the voltage detecting unit is lower than a threshold value.

4. The power transmission system according to claim 1,

wherein the power transmission apparatus further includes a current detecting unit configured to detect an amount of current supplied from the driving power circuit to the high-frequency voltage generating circuit or an amount of current supplied from the high-frequency voltage generating circuit to the primary-side coupling electrode, and

wherein the control unit is further configured to monitor the detected amount of supplied current in a state in which the high-frequency voltage generating circuit is operated at a monitoring frequency different from the driving frequency and, if the detected amount of supplied current is higher than or equal to a threshold value, the control unit operates the high-frequency voltage generating circuit at the driving frequency to supply power to the power receiving apparatus.

5. The power transmission system according to claim 1,

wherein the power transmission apparatus further includes a current detecting unit configured to detect the amount of current supplied from the driving power circuit to the high-frequency voltage generating circuit or the amount of current supplied from the high-frequency voltage generating circuit to the primary-side coupling electrode, and

wherein the control unit is further configured to stop the supply of the power from the driving power circuit to the high-frequency voltage generating circuit if the detected amount of supplied current is lower than or equal to a threshold value.

6. The power transmission system according to claim 1, further comprising:

the power receiving apparatus including the secondary-side coupling electrode electrically couplable to the primary-side coupling electrode and the load circuit connected to the secondary-side coupling electrode.

7. The power transmission system according to claim 1, further comprising:

a voltage detecting unit configured to detect a high-frequency voltage generated by the high-frequency voltage generating circuit, wherein the control unit is further configured to stop the supply of the power from the driving power circuit to the high-frequency voltage generating circuit if the voltage detected by the voltage detecting unit is lower than a threshold value.

8. The power transmission system according to claim 1, wherein the power transmission apparatus further includes a current detecting unit configured to detect an amount of current supplied from the driving power circuit to the high-frequency voltage generating circuit or an amount of current supplied from the high-frequency voltage generating circuit to the primary-side coupling electrode, and wherein the control unit is further configured to monitor the detected amount of supplied current in a state in which the high-frequency voltage generating circuit is operated at a monitoring frequency different from the driving frequency and, if the detected amount of supplied current is higher than or equal to a threshold value, the control unit operates the high-frequency voltage generating circuit at the driving frequency to supply power to the power receiving apparatus.

9. The power transmission system according to claim 1, wherein the power transmission apparatus further includes a current detecting unit configured to detect the amount of current supplied from the driving power circuit to the high-frequency voltage generating circuit or the amount of current supplied from the high-frequency voltage generating circuit to the primary-side coupling electrode, and

wherein the control unit is further configured to stop the supply of the power from the driving power circuit to the high-frequency voltage generating circuit if the detected amount of supplied current is lower than or equal to a threshold value.

10. The power transmission system according to claim 1, further comprising:

the power receiving apparatus including the secondary-side coupling electrode electrically couplable to the primary-side coupling electrode and the load circuit connected to the secondary-side coupling electrode.

11. The power transmission system according to claim 2, further comprising:

a voltage detecting unit configured to detect a high-frequency voltage generated by the high-frequency voltage generating circuit,

wherein the control unit is further configured to stop the supply of the power from the driving power circuit to the high-frequency voltage generating circuit if the voltage detected by the voltage detecting unit is lower than a threshold value.

12. The power transmission system according to claim 2,

wherein the power transmission apparatus further includes a current detecting unit configured to detect an amount of current supplied from the driving power circuit to the high-frequency voltage generating circuit or an amount of current supplied from the high-frequency voltage generating circuit to the primary-side coupling electrode, and

wherein the control unit is further configured to monitor the detected amount of supplied current in a state in which the high-frequency voltage generating circuit is operated at a monitoring frequency different from the driving frequency and, if the detected amount of supplied current is higher than or equal to a threshold value, the control unit operates the high-frequency voltage generating circuit at the driving frequency to supply power to the power receiving apparatus.

13. The power transmission system according to claim 2,

wherein the power transmission apparatus further includes a current detecting unit configured to detect the amount of current supplied from the driving power circuit to the high-frequency voltage generating circuit or the amount of current supplied from the high-frequency voltage generating circuit to the primary-side coupling electrode, and

wherein the control unit is further configured to stop the supply of the power from the driving power circuit to the high-frequency voltage generating circuit if the detected amount of supplied current is lower than or equal to a threshold value.

14. The power transmission system according to claim 2, further comprising:

the power receiving apparatus including the secondary-side coupling electrode electrically couplable to the primary-side coupling electrode and the load circuit connected to the secondary-side coupling electrode.

15. The power transmission system according to claim 3,

wherein the power transmission apparatus further includes a current detecting unit configured to detect an amount of current supplied from the driving power circuit to the high-frequency voltage generating circuit or an amount of current supplied from the high-frequency voltage generating circuit to the primary-side coupling electrode, and

wherein the control unit is further configured to monitor the detected amount of supplied current in a state in which the high-frequency voltage generating circuit is operated at a monitoring frequency different from the driving frequency and, if the detected amount of supplied current is higher than or equal to a threshold value, the control unit operates the high-frequency voltage generating circuit at the driving frequency to supply power to the power receiving apparatus.

16. The power transmission system according to claim 3,

wherein the power transmission apparatus further includes a current detecting unit configured to detect the amount of current supplied from the driving power circuit to the high-frequency voltage generating circuit or the amount of current supplied from the high-frequency voltage generating circuit to the primary-side coupling electrode, and

wherein the control unit is further configured to stop the supply of the power from the driving power circuit to the high-frequency voltage generating circuit if the detected amount of supplied current is lower than or equal to a threshold value.

17. The power transmission system according to claim 3, further comprising:

the power receiving apparatus including the secondary-side coupling electrode electrically couplable to the primary-side coupling electrode and the load circuit connected to the secondary-side coupling electrode.

18. The power transmission system according to claim 4,

wherein the power transmission apparatus further includes a current detecting unit configured to detect the amount of current supplied from the driving power circuit to the high-frequency voltage generating circuit or the amount of current supplied from the high-frequency voltage generating circuit to the primary-side coupling electrode, and

wherein the control unit is further configured to stop the supply of the power from the driving power circuit to the high-frequency voltage generating circuit if the detected amount of supplied current is lower than or equal to a threshold value.

19. The power transmission system according to claim 4, further comprising:

the power receiving apparatus including the secondary-side coupling electrode electrically couplable to the primary-side coupling electrode and the load circuit connected to the secondary-side coupling electrode.