Power transmission apparatus, power transmission/reception apparatus, and method of transmitting power

• US 8,575,782 B2
• Filed: 03/16/2010
• Issued: 11/05/2013
• Est. Priority Date: 03/31/2009
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Yoshikawa, Hiroyasu
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): PARRIES, DRU M
• Application Number:
  US12/724,938
• Publication Number:
  US 20100244578A1
• Time in Patent Office: 1,330 Days
• Field of Search: 307/104
• US Class Current: 307/104
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment

Abstract

A power transmission apparatus includes: a power source; a power transmission coil that transmits electric power supplied from the power source outward as magnetic energy through magnetic resonance; a peak searching unit that searches for a drive frequency at which the magnetic energy transmitted outward has a peak; a peak split detector that detects splitting of the drive frequency at which the magnetic energy transmitted outward has a peak; a selection unit that selects a higher-frequency side frequency among split drive frequencies generated by the splitting; and a drive unit that drives the power transmission coil using the frequency selected by the selection unit.

Claims

1. A power transmission apparatus comprising:

a power source;

a power transmission coil that transmits electric power supplied from the power source outward as magnetic energy through magnetic resonance;

a peak searching unit that searches for a drive frequency at which the magnetic energy transmitted outward has a peak;

a peak split detector that detects splitting of the drive frequency at which the magnetic energy transmitted outward has a peak;

a selection unit that selects a higher-frequency side frequency among split drive frequencies generated by the splitting; and

a drive unit that drives the power transmission coil using the frequency selected by the selection unit.

2. The power transmission apparatus according to claim 1, further comprising:

a power supply coil that supplies electric power from the power source to the power transmission coil through electromagnetic induction.

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

a magnetic field sensor that measures the magnetic energy transmitted outward by the power transmission coil,

wherein the peak detector searches for a drive frequency at which the magnetic energy transmitted outward has a peak on the basis of a change in a measurement result of the magnetic field sensor caused by changing the drive frequency.

4. The power transmission apparatus according to claim 3, further comprising:

a monitoring unit that monitors the measurement result obtained by the magnetic field sensor by fixing the drive frequency,

wherein the peak searching unit starts to search for a drive frequency at which the magnetic energy transmitted outward has a peak when the measurement result of the magnetic field sensor has been determined to exceed a threshold from a result of monitoring performed by the monitoring unit.

5. The power transmission apparatus according to any one of claim 1, wherein the power transmission coil has a resonance frequency corresponding to a resonance frequency of a power reception coil that receives magnetic energy through magnetic resonance.

6. A power transmission/reception apparatus that supplies electric power from a power transmission coil in a power transmission apparatus to a power reception coil in a power reception apparatus by causing magnetic resonance to be generated between the power transmission coil and the power reception coil, the power transmission/reception apparatus comprising:

a peak searching unit that searches for a drive frequency for the power transmission coil at which the electric power supplied through the magnetic resonance has a peak;

a peak split detector that detects splitting of the drive frequency at which the electric power supplied through the magnetic resonance has a peak;

a selection unit that selects a higher-frequency side frequency among split drive frequencies generated by the splitting; and

a drive unit that drives the power transmission coil using the frequency selected by the selection unit.

7. A control method of transmitting electric power from a power transmission coil to a power reception coil by causing magnetic resonance to be generated between the power transmission coil and the power reception coil, the control method comprising:

searching for a drive frequency at which the electric power supplied through the magnetic resonance has a peak;

detecting splitting of the drive frequency at which the electric power supplied through the magnetic resonance has a peak;

selecting a higher-frequency side frequency among split drive frequencies generated by the splitting; and

driving the power transmission coil using the frequency selected in the selecting.