Power transmission device and non-contact power feeding system

• US 10,432,029 B2
• Filed: 09/09/2016
• Issued: 10/01/2019
• Est. Priority Date: 10/15/2015
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Ikefuji, Yoshihiro
• Primary Examiner(s): Cavallari, Daniel J
• Application Number:
  US15/768,327
• Publication Number:
  US 20180342898A1
• Time in Patent Office: 1,117 Days
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• 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
• CPC Class Codes: H04W 4/80 Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication

Abstract

In a non-contact power feeding system which is formed with a power transmission device that includes a power transmission-side resonant circuit including a power transmission-side coil and a power reception device that includes a power reception-side resonant circuit including a power reception-side coil and which can transmit and receive power by a magnetic field resonance method, the control circuit of the power transmission device supplies, before the power transmission, a predetermined determination alternating current voltage to the power transmission-side resonant circuit so as to detect the amplitude of a current flowing through the power transmission-side coil at that time. The control circuit controls the performance of the power transmission based on the current amplitude detection value.

Claims

1. A power transmission device which can transmit power to a power reception device by a magnetic field resonance method, the power transmission device comprising:

a power transmission-side resonant circuit which includes a power transmission-side coil for performing the power transmission;

a power transmission circuit which can supply an alternating current voltage to the power transmission-side resonant circuit;

a detection circuit which detects an amplitude of a current flowing through the power transmission-side coil; and

a control circuit which performs power transmission control on the power by controlling a state of the supply of the alternating current voltage to the power transmission-side resonant circuit,

wherein before the power transmission, the control circuit acquires, as a determination amplitude detection value, a detection value by the detection circuit when a predetermined determination alternating current voltage is supplied to the power transmission-side resonant circuit, and controls, based on the determination amplitude detection value, performance of the power transmission through a determination as to whether or not the power reception device can perform proper power reception.

2. The power transmission device according to claim 1,

wherein when the determination amplitude detection value is equal to or less than a predetermined reference value, the control circuit determines that the power reception device can perform the proper power reception so as to allow the performance of the power transmission whereas when the determination amplitude detection value is not equal to or less than the predetermined reference value, the control circuit restricts the performance of the power transmission.

3. The power transmission device according to claim 1,

wherein after the control circuit receives, from the power reception device, a response signal for a predetermined signal transmitted wirelessly from the power transmission device, the control circuit performs processing including the acquisition of the determination amplitude detection value.

4. A non-contact power feeding system which comprises:

a power transmission device that includes a power transmission-side resonant circuit including a power transmission-side coil for transmitting power; and

a power reception device that includes a power reception-side resonant circuit including a power reception-side coil for receiving the power and which can transmit and receive the power by a magnetic field resonance method,

wherein the power transmission device includes;

a power transmission circuit which can supply an alternating current voltage to the power transmission-side resonant circuit;

a detection circuit which detects an amplitude of a current flowing through the power transmission-side coil; and

a control circuit which performs power transmission control on the power by controlling a state of the supply of the alternating current voltage to the power transmission-side resonant circuit, and

before the power transmission, the control circuit acquires, as a determination amplitude detection value, a detection value by the detection circuit when a predetermined determination alternating current voltage is supplied to the power transmission-side resonant circuit, and controls, based on the determination amplitude detection value, performance of the power transmission through a determination as to whether or not the power reception device can perform proper power reception.

5. The non-contact power feeding system according to claim 4,

wherein when the determination amplitude detection value is equal to or less than a predetermined reference value, the control circuit determines that the power reception device can perform the proper power reception so as to allow the performance of the power transmission whereas when the determination amplitude detection value is not equal to or less than the predetermined reference value, the control circuit restricts the performance of the power transmission.

6. The non-contact power feeding system according to claim 4, wherein after the control circuit receives, from the power reception device, a response signal for a predetermined signal transmitted wirelessly from the power transmission device, the control circuit performs processing including the acquisition of the determination amplitude detection value.

7. The non-contact power feeding system according to claim 4,

wherein the power reception device includes a change/short circuit which can change a resonant frequency of the power reception-side resonant circuit from a reference frequency that is a resonant frequency at a time of the power reception or can short-circuit the power reception-side coil,

before the power transmission, the control circuit can perform:

first processing for determining whether or not a foreign object is present that differs from the power reception device and that can generate a current based on a magnetic field generated in the power transmission-side coil; and

second processing for determining whether or not the power reception device can perform the proper power reception,

in the first processing, in a state where the power reception device changes the resonant frequency of the power reception-side resonant circuit or short-circuits the power reception-side coil according to a signal by communication from the power transmission device, a predetermined foreign object determination alternating current voltage is supplied to the power transmission-side resonant circuit, a detection value by the detection circuit at that time is acquired as a foreign object detection amplitude detection value and whether or not the foreign object is present is determined based on the foreign object detection amplitude detection value and

when it is determined that the foreign object is present, the performance of the power transmission is restricted.

8. The non-contact power feeding system according to claim 7,

wherein when the control circuit determines that the foreign object is not present and determines that the power reception device can perform the proper power reception, the control circuit allows the performance of the power transmission.

9. The non-contact power feeding system according to claim 7,

wherein the control circuit determines, in the first processing, whether or not the foreign object detection amplitude detection value falls outside a predetermined range so as to determine whether or not the foreign object is present.

10. The non-contact power feeding system according to claim 7, wherein when the determination amplitude detection value is acquired, the changing or the short-circuiting by the change/short circuit is not performed.