Feed unit including power transmission coil and feed system

• US 9,954,397 B2
• Filed: 03/06/2014
• Issued: 04/24/2018
• 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
• Primary Examiner(s): Amrany, Adi
• Application Number:
  US14/199,451
• Publication Number:
  US 20140300196A1
• Time in Patent Office: 1,510 Days
• Field of Search: 307104
• 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 5/79 for data transfer in combination with power transfer

Abstract

The present disclosure includes a feed unit and a feed system. The feed unit includes a power transmission coil and a coupling coefficient calculation section. The power transmission coil is configured to transmit power to a power reception coil of a receiving unit using a magnetic field. The coupling coefficient calculation section is configured to measure frequency characteristics of input impedance of a rectification circuit of the receiving unit, the rectification circuit being in a non-operating state. The coupling coefficient calculation section is also configured to calculate a coupling coefficient between the power transmission coil and the power reception coil using the frequency characteristics of the input impedance of the rectification circuit that have been measured.

Claims

1. A feed unit comprising:

a power transmission coil configured to transmit power to a power reception coil of a receiving unit using a magnetic field;

a coupling coefficient calculation section configured to

measure frequency characteristics of input impedance of a rectification circuit of the receiving unit, the rectification circuit being in a non-operating state, and

calculate a coupling coefficient between the power transmission coil and the power reception coil using the frequency characteristics of the input impedance of the rectification circuit that have been measured; and

an AC signal generation section configured to supply an AC signal to the power transmission coil, wherein the AC signal generation section and the rectification circuit are in non-operating states when the frequency characteristics are measured by the coupling coefficient calculation section, 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 that is set by the control section,

wherein the control section is configured to continuously vary the frequency of the measurement signal, and

wherein responsive to the control section continuously varying the frequency of the measurement signal, the calculation section is configured to obtain the frequency characteristics.

2. The feed unit according to claim 1, wherein the coupling coefficient calculation section is further configured to

detect frequencies at extreme values of the input impedance from the frequency characteristics that have been measured, and

calculate the coupling coefficient using the frequencies at the extreme values.

3. The feed unit according to claim 2, wherein, to detect the frequencies at the extreme values of the input impedance, the coupling coefficient calculation section is further configured to detect a first frequency at a minimum value of the input impedance and a second frequency at a maximum value of the input impedance, and

wherein, to calculate the coupling coefficient using the frequencies at the extreme values, the coupling coefficient calculation section is further configured to calculate the coupling coefficient using the first frequency and the second frequency.

4. The feed unit according to claim 3, further comprising a first resonance circuit that includes the power transmission coil, wherein when a first resonance frequency in the first resonance circuit is denoted by f1 and a second resonance frequency in a second resonance circuit of the receiving unit that includes 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, to detect the frequencies at the extreme values of the input impedance, the coupling coefficient calculation section is further configured to detect frequencies at two minimum values of the input impedance as the frequencies at the extreme values, and

wherein, to calculate the coupling coefficient using the frequencies at the extreme values, the coupling coefficient calculation section is further configured to calculate the coupling coefficient using the frequencies at the two minimum values.

6. The feed unit according to claim 5, further comprising a first resonance circuit that includes the power transmission coil, wherein when a first resonance frequency in the first resonance circuit is denoted by f1 and a second resonance frequency in a second resonance circuit of the receiving unit that includes 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 power transmission coil is further configured to transmit a weak signal, and

wherein, to measure the frequency characteristics in the non-operating state of the rectification circuit, the coupling coefficient calculation section is configured to measure the frequency characteristics with the weak signal.

8. The feed unit according to claim 1, wherein the control section further includes a parameter setting section that is configured to set a parameter in transmission of the power from the power transmission coil based on the coupling coefficient.

9. The feed unit according to claim 8, wherein

the coupling coefficient calculation section is configured to calculate the coupling coefficient before an activation of the receiving unit,

the power transmission coil is configured to transmit an activation signal, and

the parameter setting section is configured to vary a parameter in the activation signal according to a magnitude of the coupling coefficient that is calculated by the coupling coefficient calculation section.

10. The feed unit according to claim 9, wherein the parameter setting section is configured to set a voltage of the activation signal to satisfy an inverse relationship with respect to the coupling coefficient.

11. The feed unit according to claim 8, wherein the parameter setting section is configured to set a power transmission frequency in transmission of the power from the power transmission coil based on the coupling coefficient.

12. The feed unit according to claim 1, wherein the coupling coefficient calculation section is further configured determine whether the receiving unit is within a vicinity of the feed unit based on the frequency characteristics.

13. The feed unit according to claim 12, wherein the coupling coefficient calculation section is further configured to determine that the receiving unit is within the vicinity of the feed unit when the frequency characteristics are within a predetermined range.

14. The feed unit according to claim 1, wherein the control section further includes a power transmission control section that is configured to control the power that is transmitted from the power transmission coil according to a magnitude of the coupling coefficient calculated by the coupling coefficient calculation section, wherein

the power transmission control section is configured to control the power transmission coil to not transmit the power when the coupling coefficient is equal to or lower than a first threshold.

15. The feed unit according to claim 14, wherein the power transmission control section is configured to control the power transmission coil to transmit the power when the coupling coefficient is larger than the first threshold and equal to or lower than a second threshold.

16. A feed system comprising:

one or more electronic apparatuses, each of the one or more electronic apparatuses having a power reception coil and a rectification circuit; and

a feed unit including

a power transmission coil configured to transmit power to at least one power reception coil of the one or more electronic apparatuses using a magnetic field;

a coupling coefficient calculation section configured to

measure frequency characteristics of input impedance of the rectification circuit of the one or more electronic apparatuses, the rectification circuit being in a non-operating state, and

calculate a coupling coefficient between the power transmission coil and the power reception coil using the frequency characteristics of the input impedance of the rectification circuit that have been measured; and

an AC signal generation section configured to supply an AC signal to the power transmission coil, wherein the AC signal generation section and the rectification circuit are in non-operating states when the frequency characteristics are measured by the coupling coefficient calculation section, 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 that is set by the control section,

wherein the control section is configured to continuously vary the frequency of the measurement signal, and

wherein responsive to the control section continuously varying the frequency of the measurement signal, the calculation section is configured to obtain the frequency characteristics.

17. The feed system according to claim 16, wherein a first electronic apparatus of the one or more electronic apparatuses is configured to

receive a weak signal that passes through a bypass route with respect to the rectification circuit of the first electronic apparatus, the bypass route is disposed between a pair of input terminals of the rectification circuit of the first electronic apparatus, and wherein a capacitor or a parasitic capacitance component is provided on the bypass route, and

responsive to receiving the weak signal that passes through the bypass route, the rectification circuit of the first electronic apparatus remains in the non-operating state.