FEED UNIT AND FEED SYSTEM

• US 20140300196A1
• Filed: 03/06/2014
• Published: 10/09/2014
• Est. Priority Date: 04/08/2013
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Bunsen, Keigo
• Granted Patent: US 9,954,397 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: H02J 50/10 using inductive coupling
• 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 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H04B 5/0037 for power transfer
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

A feed unit includes: a power transmission coil configured to perform power transmission using a magnetic field; a coupling coefficient calculation section configured to calculate a coupling coefficient between the power transmission coil and a power reception coil in a unit to be fed with power. The coupling coefficient calculation section measures frequency characteristics of input impedance in a non-operating state of a rectification circuit in the unit to be fed with power, and uses a measurement result of the frequency characteristics to calculate the coupling coefficient.

Claims

1. A feed unit comprising:

a power transmission coil configured to perform power transmission using a magnetic field;

a coupling coefficient calculation section configured to calculate a coupling coefficient between the power transmission coil and a power reception coil in a unit to be fed with power, wherein

the coupling coefficient calculation section measures frequency characteristics of input impedance in a non-operating state of a rectification circuit in the unit to be fed with power, and uses a measurement result of the frequency characteristics to calculate the coupling coefficient.

2. The feed unit according to claim 1, wherein the coupling coefficient calculation section detects frequencies at extreme values of the input impedance from the measurement result of the frequency characteristics, and uses the frequencies at the extreme values to calculate the coupling coefficient.

3. The feed unit according to claim 2, wherein the coupling coefficient calculation section detects both a frequency at a minimum value of the input impedance and a frequency at a maximum value of the input impedance as frequencies at the extreme values, and uses both the frequencies to calculate the coupling coefficient.

4. The feed unit according to claim 3, wherein when a resonance frequency in a resonance circuit including the power transmission coil is denoted by f1 and a resonance frequency in a resonance circuit including the power reception coil is denoted by f2, the resonance frequencies f1 and f2 are set to satisfy (f1<

<

f2).

5. The feed unit according to claim 2, wherein the coupling coefficient calculation section detects frequencies at two minimum values of the input impedance as the frequencies at the extreme values, and uses the frequencies at the two minimum values to calculate the coupling coefficient.

6. The feed unit according to claim 5, wherein when a resonance frequency in a resonance circuit including the power transmission coil is denoted by f1 and a resonance frequency in a resonance circuit including the power reception coil is denoted by f2, the resonance frequencies f1 and f2 are set to satisfy (f1=f2).

7. The feed unit according to claim 1, wherein the coupling coefficient calculation section measures the frequency characteristics with use of a weak signal to measure the frequency characteristics in the non-operating state of the rectification circuit.

8. The feed unit according to claim 7, wherein the rectification circuit is put into the non-operating state when the weak signal passes through a bypass route with respect to the rectification circuit in the unit to be fed with power.

9. The feed unit according to claim 8, wherein

the bypass route is disposed between a pair of input terminals of the rectification circuit, and

a capacitor or a parasitic capacitance component is provided on the bypass route.

10. The feed unit according to claim 1, further comprising

an AC signal generation section configured to supply, to the power transmission coil, an AC signal to perform the power transmission, wherein

the AC signal generation section is in the non-operating state in addition to the rectification circuit when the frequency characteristics are measured.

11. The feed unit according to claim 1, wherein

the coupling coefficient calculation section includes

a measurement signal generation section configured to generate a measurement signal to measure the frequency characteristics,

a current detection section configured to detect a current flowing through the power transmission coil,

a control section configured to control a voltage and a frequency of the measurement signal, and

a calculation section configured to calculate the input impedance based on the current detected by the current detection section and the voltage set by the control section, and

the control section continuously varies the frequency of the measurement signal to allow the calculation section to obtain the frequency characteristics.

12. The feed unit according to claim 1, further comprising

a parameter setting section configured to set a parameter in the power transmission with use of the coupling coefficient calculated by the coupling coefficient calculation section.

13. The feed unit according to claim 12, wherein

the coupling coefficient calculation section calculates the coupling coefficient before activation of the unit to be fed with power, and

the parameter setting section varies a parameter in an activation signal of the unit to be fed with power according to magnitude of the coupling coefficient calculated by the coupling coefficient calculation section.

14. The feed unit according to claim 13, wherein the parameter setting section sets a voltage of the activation signal to satisfy inverse relationship with respect to the coupling coefficient.

15. The feed unit according to claim 12, wherein the parameter setting section uses the coupling coefficient calculated by the coupling coefficient calculation section to set a power transmission frequency in the power transmission.

16. The feed unit according to claim 1, wherein the coupling coefficient calculation section uses the measurement result of the frequency characteristics to detect whether the unit to be fed with power exists in the vicinity of the feed unit.

17. The feed unit according to claim 16, wherein the coupling coefficient calculation section detects whether the unit to be fed with power exists in the vicinity of the feed unit depending on whether the measurement result of the frequency characteristics is within a predetermined range.

18. The feed unit according to claim 1, further comprising

a power transmission control section configured to control operation in the power transmission according to magnitude of the coupling coefficient calculated by the coupling coefficient calculation section, wherein

the power transmission control section does not perform the power transmission when the coupling coefficient is equal to or lower than a first threshold.

19. The feed unit according to claim 18, wherein the power transmission control section performs the power transmission after control of decreasing received power is performed in the unit to be fed with power when the coupling coefficient is larger than the first threshold and equal to or lower than a second threshold.

20. A feed system provided with one or a plurality of electronic apparatuses and a feed unit, the one or the plurality of electronic apparatuses each having a power reception coil and a rectification circuit, the feed unit being configured to perform power transmission using a magnetic field to the electronic apparatuses, the feed unit comprising:

a power transmission coil configured to perform the power transmission;

a coupling coefficient calculation section configured to calculate a coupling coefficient between the power transmission coil and the power reception coil, wherein

the coupling coefficient calculation section measures frequency characteristics of input impedance in a non-operating state of the rectification circuit, and uses a measurement result of the frequency characteristics to calculate the coupling coefficient.