Feed unit and feed system

• US 9,424,985 B2
• Filed: 06/25/2013
• Issued: 08/23/2016
• Est. Priority Date: 07/31/2012
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Uramoto, Yoichi, Tanaka, Masayuki, Kozakai, Osamu
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): Pham, Duc M
• Application Number:
  US13/926,420
• Publication Number:
  US 20140035364A1
• Time in Patent Office: 1,155 Days
• Field of Search: 307/104
• US Class Current: 1/1
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 7/00045 Authentication, i.e. circuits for checking compatibility between one component, e.g. a battery or a battery charger, and another component, e.g. a power source

Abstract

A feed unit includes: a power transmission coil provided to perform power transmission with use of a magnetic field; a parallel LC resonance circuit including the power transmission coil; a series LC resonance circuit; an alternating-current signal generating section supplying the parallel LC resonance circuit and the series LC resonance circuit with an alternating-current signal used to perform the power transmission; and a control section controlling the alternating-current signal generating section with use of a predetermined control signal, the control section performing frequency control of the control signal to allow a circuit current that flows upon the power transmission to become smaller.

Claims

1. A feed unit comprising:

a power transmission coil provided to perform power transmission with use of a magnetic field;

a parallel LC resonance circuit including the power transmission coil;

a series LC resonance circuit;

an alternating-current signal generating section configured to supply the parallel LC resonance circuit and the series LC resonance circuit with an alternating-current signal used to perform the power transmission; and

a control section configured to control the alternating-current signal generating section with use of a predetermined control signal, the control section configured to perform frequency control of the control signal to allow a circuit current that flows upon the power transmission to become smaller over a preset range of frequencies in a neighborhood of a resonant frequency of resonance operation.

2. The feed unit according to claim 1, wherein the control section configured to perform the frequency control to allow the circuit current to become smaller in a frequency domain during the resonance operation in which the series LC resonance circuit and the parallel LC resonance circuit are used in combination.

3. The feed unit according to claim 2, wherein

the circuit current exhibits concave frequency characteristics in the frequency domain in the neighborhood of the resonant frequency, and

the control section is configured to perform the frequency control to allow the circuit current to substantially take a local minimum value.

4. The feed unit according to claim 1, wherein

when a present frequency of the control signal is f1, a frequency determined by subtracting a predetermined frequency from the f1 is f0, a frequency determined by adding the predetermined frequency to the f1 is f2, the circuit current is I(f0) when the control signal has the frequency of f0, the circuit current is I(f1) when the control signal has the frequency of f1, and the circuit current is I(f2) when the control signal has the frequency of f2,

the control section is configured to perform the frequency control by updating the f1 whenever necessary in accordance with a relative magnitude relationship between the I(f0), the I(f1), and the I(f2).

5. The feed unit according to claim 1, wherein

the control section is configured to receive a request for an electromotive force value in an electronic device by utilizing communication between the feed unit and the electronic device, and

the control section further has a function of controlling a duty ratio of the control signal in response to the request for the electromotive force value.

6. The feed unit according to claim 5, wherein

the control section is configured to control controls the duty ratio to be decreased when receiving a request for a decrease in the electromotive force value, and

the control section is configured to control controls the duty ratio to be increased when receiving a request for an increase in the electromotive force value.

7. The feed unit according to claim 5, wherein a feeding period in which the power transmission to the electronic device is performed and a communication period in which the communication between the feed unit and the electronic device is performed are set time-divisionally.

8. The feed unit according to claim 1, wherein

the alternating-current signal generating section includes a switching amplifier including a switching element, and

the control section is configured to control ON-and-OFF operation of the switching element with the use of the control signal.

9. The feed unit according to claim 1, further comprising a current detection section configured to detect the circuit current, wherein

the control section is configured to perform the frequency control with use of the circuit current detected by the current detection section.

10. A feed system comprising:

one or a plurality of electronic devices, and

a feed unit performing power transmission to each of the electronic devices with use of a magnetic field, the feed unit including,

a power transmission coil provided to perform the power transmission,

a parallel LC resonance circuit including the power transmission coil,

a series LC resonance circuit,

an alternating-current signal generating section configured to supply the parallel LC resonance circuit and the series LC resonance circuit with an alternating-current signal used to perform the power transmission, and

a control section configured to control the alternating-current signal generating section with use of a predetermined control signal, the control section configured to perform frequency control of the control signal to allow a circuit current that flows upon the power transmission to become smaller over a preset range of frequencies in a neighborhood of a resonant frequency of resonance operation.

11. The feed system according to claim 10, wherein the control section is configured to perform the frequency control to allow the circuit current to become smaller in a frequency domain in the neighborhood of the resonant frequency during the resonance operation in which the series LC resonance circuit and the parallel LC resonance circuit are used in combination.

12. The feed system according to claim 10, wherein

the circuit current exhibits concave frequency characteristics in a frequency domain in the neighborhood of the resonant frequency, and

the control section is configured to perform the frequency control to allow the circuit current to substantially take a local minimum value.