Power transmission device and wireless power transmission system using the power transmission device

• US 9,466,987 B2
• Filed: 12/13/2013
• Issued: 10/11/2016
• Est. Priority Date: 12/19/2012
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Tamaki, Kazutaka, Kurata, Hitoyoshi
• Primary Examiner(s): Kim, Jung
• Assistant Examiner(s): BUKHARI, AQEEL H
• Application Number:
  US14/105,678
• Publication Number:
  US 20140167523A1
• Time in Patent Office: 1,033 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices

Abstract

A power transmission device includes a power conversion circuit that outputs an alternating voltage in order to generate an alternating magnetic field and a control circuit used to control a frequency of the alternating voltage. The control circuit sets, in a predetermined frequency range, the frequency of the alternating voltage to a higher one of a first frequency at which transmission efficiency is highest and a second frequency at which a voltage generated in the power receiving device is highest, and performs power transmission.

Claims

1. A power transmission device that wirelessly transmits alternating current power to a power receiving device, the power transmission device comprising:

a power conversion circuit that outputs an alternating voltage in order to generate an alternating magnetic field; and

a control circuit used to control a frequency of the alternating voltage, wherein

the control circuit sets, in a predetermined frequency range, the frequency of the alternating voltage to a higher one of a first frequency at which transmission efficiency is highest and a second frequency at which a voltage generated in the power receiving device is highest, and performs power transmission.

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

a power source circuit that supplies direct current power to the power conversion circuit,

wherein the control circuit sets the frequency of the alternating voltage and thereafter causes a supply voltage, which is to be supplied to the power conversion circuit, to be higher than a supply voltage obtained before the frequency of the alternating voltage is set.

3. The power transmission device according to claim 1, wherein

the power conversion circuit is a switching circuit, and

the control circuit sets the frequency of the alternating voltage and thereafter changes a duty ratio of a switching operation of the power conversion circuit, the duty ratio being obtained before the frequency of the alternating voltage is set.

4. A wireless power transmission system comprising:

the power transmission device according to claim 1; and

a power receiving device.

5. A wireless power transmission system comprising:

the power transmission device according to claim 2; and

a power receiving device.

6. A wireless power transmission system comprising:

the power transmission device according to claim 3; and

a power receiving device.