Wireless power transmission device

Patent metadata

Field	Value
Publication number	US-2016013658-A1
Application number	US-201414770598-A
Country	US
Kind code	A1
Filing date	Feb 27, 2014
Priority date	Mar 5, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

A wireless power transmission device includes a detection coil and a capacitor that configure a resonance circuit. An oscillation circuit generates high-frequency current corresponding to a detection frequency for performing presence detection of an electric appliance and metal. A presence detection circuit performs presence detection of the electric appliance and the metal based on an output voltage obtained by exciting the detection coil with the high-frequency current having the detection frequency. A detection condition changing circuit performs an initial value setting mode that changes a detection condition of the presence detection circuit in accordance with a resonance characteristic. The detection condition changing circuit includes a detection frequency changing circuit that changes the detection frequency in accordance with the resonance characteristic.

First claim

1 . A wireless power transmission device that performs wireless power supplying on a power reception device arranged in an electric appliance using an electromagnetic induction effect, the wireless power transmission device comprising:
a detection coil; a capacitor that configures a resonance circuit with the detection coil; an oscillation circuit configured to excite the detection coil with high-frequency current, wherein the oscillation circuit is capable of generating high-frequency current corresponding to a detection frequency for performing presence detection of the electric appliance and metal; an output detection circuit configured to generate output voltage in accordance with excitation current flowing through the detection coil; a presence detection circuit configured to perform presence detection of the electric appliance and the metal based on the output voltage obtained by exciting the detection coil with the high-frequency current having the detection frequency; and a detection condition changing circuit that is capable of performing an initial value setting mode that changes a detection condition of the presence detection circuit in accordance with a resonance characteristic determined by the detection coil and the capacitor, wherein the detection condition changing circuit includes a detection frequency changing circuit configured to change the detection frequency in accordance with the resonance characteristic.

2 . The wireless power transmission device according to claim 1 , wherein
the detection coil is a primary coil; the oscillation circuit is further capable of generating high-frequency current corresponding to a power supplying resonance frequency, which differs from the detection frequency, and performing wireless power supplying from the primary coil excited by the high-frequency current having the power supplying resonance frequency to a secondary coil of the power reception device using an electromagnetic induction effect.

3 . The wireless power transmission device according to claim 1 , further comprising a setting surface on which the electric appliance is set, wherein
the setting surface is divided into one or more areas, and the detection coil is arranged in each area.

4 . (canceled)

5 . The wireless power transmission device according to claim 1 , wherein the detection frequency changing circuit includes
a frequency adjustment circuit configured to provide the oscillation circuit with a control signal for controlling an adjusted frequency for adjusting the detection frequency; a first comparison circuit configured to compare the output voltage, which is obtained by exciting the detection coil with high-frequency current having the adjusted frequency and generated by the oscillation circuit, with a first target voltage; and a first setting circuit configured to set the detection frequency to the adjusted frequency, which was used when the output voltage reached the first target voltage, based on a comparison result from the first comparison circuit.

6 . The wireless power transmission device according to claim 5 , wherein the frequency adjustment circuit is configured to change the adjusted frequency so that the adjusted frequency decreases step by step from a frequency higher than a resonance frequency having the resonance characteristic.

7 . The wireless power transmission device according to claim 5 , further comprising a memory that stores the detection frequency, wherein
the detection frequency changing circuit is configured to update the detection frequency stored in the memory, wherein when a comparison difference value of a new detection frequency, which is to be used for updating, and a previous detection frequency, which is stored in the memory, is in a predetermined range, the detection frequency changing circuit does not rewrite the new detection frequency over the previous detection frequency.

8 . The wireless power transmission device according to claim 5 , wherein
the presence detection circuit is configured to read the output voltage, which is obtained by exciting the detection coil with the high-frequency current having the detection frequency, from the output detection circuit based on a detection read time; and the detection condition changing circuit further includes a detection read time changing circuit configured to change the detection read time in accordance with the resonance characteristic.

9 . The wireless power transmission device according to claim 8 , wherein the detection read time changing circuit includes:
a read time adjustment circuit configured to provide the output detection circuit with a sampling signal based on an adjusted read time for adjusting the detection read time; a second comparison circuit configured to read the output voltage, which is obtained by exciting the detection coil with the high-frequency current having the detection frequency, in response to the sampling signal and compare the output voltage with a second target voltage; and a second setting circuit configured to set the detection read time to the adjusted read time used when the output voltage reaches the second target voltage, based on a comparison result from the second comparison circuit.

10 . The wireless power transmission device according to claim 9 , wherein the read time adjustment circuit is configured to change the adjusted read time so that the output voltage approaches the second target voltage step by step.

11 . The wireless power transmission device according to claim 9 , comprising a memory configured to store the detection read time, wherein
the detection read time changing circuit is configured to update the detection read time stored in the memory, wherein when a comparison difference value of a new detection read time, which is to be used for updating, and a previous detection read time, which is stored in the memory, is in a predetermined range, the detection read time changing circuit does not rewrite the new detection read time over the previous detection read time.

12 . The wireless power transmission device according to claim 5 , wherein
the presence detection circuit is configured to drive the oscillation circuit with a pulse drive signal corresponding to a detection duty ratio and generate the high-frequency current having the detection frequency, and the detection condition changing circuit further includes a detection duty ratio changing circuit configured to change the detection duty ratio in accordance with the resonance characteristic.

13 . The wireless power transmission device according to claim 12 , wherein the detection duty ratio changing circuit includes:
a duty ratio adjustment circuit configured to provide the oscillation circuit with an excitation control signal that controls an adjusted duty ratio for adjusting the detection duty ratio; a second comparison circuit configured to read the output voltage, which is obtained by exciting the detection coil with the high-frequency current having the detection frequency generated with the adjusted duty ratio, and compare the output voltage with a second target voltage; and a second setting circuit configured to set the detection duty ratio to the adjusted duty ratio used when the output voltage reaches the second target voltage, based on a comparison result from the second comparison circuit.

14 . The wireless power transmission device according to claim 13 , wherein the duty ratio adjustment circuit is configured to change the adjusted duty ratio so that the output voltage approaches the second target voltage step by step.

15 . The wireless power t

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Kohara Hiroshi
• Ozaki Mamoru
• Tsujimoto Toyohiko

Classifications

• H02J50/90

  involving detection or optimisation of position, e.g. alignment · CPC title

• H02J50/12

  of the resonant type · CPC title

• H02J50/60

  responsive to the presence of foreign objects, e.g. detection of living beings · CPC title

• H02J7/47

  Arrangements for checking compatibility or authentication between one component, e.g. a battery or a battery charger, and another component, e.g. a power source · CPC title

• H02J5/005 Primary

  Electricity · mapped topic